Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

22 files changed, 18917 insertions, 0 deletions

diff --git a/drivers/mtd/ubi/Kconfig b/drivers/mtd/ubi/Kconfig
new file mode 100644
index 0000000000..2ed77b7b3f
--- /dev/null
+++ b/drivers/mtd/ubi/Kconfig
@@ -0,0 +1,107 @@
+# SPDX-License-Identifier: GPL-2.0-only
+menuconfig MTD_UBI
+	tristate "Enable UBI - Unsorted block images"
+	select CRC32
+	help
+	  UBI is a software layer above MTD layer which admits use of LVM-like
+	  logical volumes on top of MTD devices, hides some complexities of
+	  flash chips like wear and bad blocks and provides some other useful
+	  capabilities. Please, consult the MTD web site for more details
+	  (www.linux-mtd.infradead.org).
+
+if MTD_UBI
+
+config MTD_UBI_WL_THRESHOLD
+	int "UBI wear-leveling threshold"
+	default 4096
+	range 2 65536
+	help
+	  This parameter defines the maximum difference between the highest
+	  erase counter value and the lowest erase counter value of eraseblocks
+	  of UBI devices. When this threshold is exceeded, UBI starts performing
+	  wear leveling by means of moving data from eraseblock with low erase
+	  counter to eraseblocks with high erase counter.
+
+	  The default value should be OK for SLC NAND flashes, NOR flashes and
+	  other flashes which have eraseblock life-cycle 100000 or more.
+	  However, in case of MLC NAND flashes which typically have eraseblock
+	  life-cycle less than 10000, the threshold should be lessened (e.g.,
+	  to 128 or 256, although it does not have to be power of 2).
+
+config MTD_UBI_BEB_LIMIT
+	int "Maximum expected bad eraseblock count per 1024 eraseblocks"
+	default 20
+	range 0 768
+	help
+	  This option specifies the maximum bad physical eraseblocks UBI
+	  expects on the MTD device (per 1024 eraseblocks). If the underlying
+	  flash does not admit of bad eraseblocks (e.g. NOR flash), this value
+	  is ignored.
+
+	  NAND datasheets often specify the minimum and maximum NVM (Number of
+	  Valid Blocks) for the flashes' endurance lifetime. The maximum
+	  expected bad eraseblocks per 1024 eraseblocks then can be calculated
+	  as "1024 * (1 - MinNVB / MaxNVB)", which gives 20 for most NANDs
+	  (MaxNVB is basically the total count of eraseblocks on the chip).
+
+	  To put it differently, if this value is 20, UBI will try to reserve
+	  about 1.9% of physical eraseblocks for bad blocks handling. And that
+	  will be 1.9% of eraseblocks on the entire NAND chip, not just the MTD
+	  partition UBI attaches. This means that if you have, say, a NAND
+	  flash chip admits maximum 40 bad eraseblocks, and it is split on two
+	  MTD partitions of the same size, UBI will reserve 40 eraseblocks when
+	  attaching a partition.
+
+	  This option can be overridden by the "mtd=" UBI module parameter or
+	  by the "attach" ioctl.
+
+	  Leave the default value if unsure.
+
+config MTD_UBI_FASTMAP
+	bool "UBI Fastmap (Experimental feature)"
+	default n
+	help
+	   Important: this feature is experimental so far and the on-flash
+	   format for fastmap may change in the next kernel versions
+
+	   Fastmap is a mechanism which allows attaching an UBI device
+	   in nearly constant time. Instead of scanning the whole MTD device it
+	   only has to locate a checkpoint (called fastmap) on the device.
+	   The on-flash fastmap contains all information needed to attach
+	   the device. Using fastmap makes only sense on large devices where
+	   attaching by scanning takes long. UBI will not automatically install
+	   a fastmap on old images, but you can set the UBI module parameter
+	   fm_autoconvert to 1 if you want so. Please note that fastmap-enabled
+	   images are still usable with UBI implementations without
+	   fastmap support. On typical flash devices the whole fastmap fits
+	   into one PEB. UBI will reserve PEBs to hold two fastmaps.
+
+	   If in doubt, say "N".
+
+config MTD_UBI_GLUEBI
+	tristate "MTD devices emulation driver (gluebi)"
+	help
+	   This option enables gluebi - an additional driver which emulates MTD
+	   devices on top of UBI volumes: for each UBI volumes an MTD device is
+	   created, and all I/O to this MTD device is redirected to the UBI
+	   volume. This is handy to make MTD-oriented software (like JFFS2)
+	   work on top of UBI. Do not enable this unless you use legacy
+	   software.
+
+config MTD_UBI_BLOCK
+	bool "Read-only block devices on top of UBI volumes"
+	default n
+	depends on BLOCK
+	help
+	   This option enables read-only UBI block devices support. UBI block
+	   devices will be layered on top of UBI volumes, which means that the
+	   UBI driver will transparently handle things like bad eraseblocks and
+	   bit-flips. You can put any block-oriented file system on top of UBI
+	   volumes in read-only mode (e.g., ext4), but it is probably most
+	   practical for read-only file systems, like squashfs.
+
+	   When selected, this feature will be built in the UBI driver.
+
+	   If in doubt, say "N".
+
+endif # MTD_UBI
diff --git a/drivers/mtd/ubi/Makefile b/drivers/mtd/ubi/Makefile
new file mode 100644
index 0000000000..543673605c
--- /dev/null
+++ b/drivers/mtd/ubi/Makefile
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_MTD_UBI) += ubi.o
+
+ubi-y += vtbl.o vmt.o upd.o build.o cdev.o kapi.o eba.o io.o wl.o attach.o
+ubi-y += misc.o debug.o
+ubi-$(CONFIG_MTD_UBI_FASTMAP) += fastmap.o
+ubi-$(CONFIG_MTD_UBI_BLOCK) += block.o
+
+obj-$(CONFIG_MTD_UBI_GLUEBI) += gluebi.o
diff --git a/drivers/mtd/ubi/attach.c b/drivers/mtd/ubi/attach.c
new file mode 100644
index 0000000000..ae5abe492b
--- /dev/null
+++ b/drivers/mtd/ubi/attach.c
@@ -0,0 +1,1923 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+/*
+ * UBI attaching sub-system.
+ *
+ * This sub-system is responsible for attaching MTD devices and it also
+ * implements flash media scanning.
+ *
+ * The attaching information is represented by a &struct ubi_attach_info'
+ * object. Information about volumes is represented by &struct ubi_ainf_volume
+ * objects which are kept in volume RB-tree with root at the @volumes field.
+ * The RB-tree is indexed by the volume ID.
+ *
+ * Logical eraseblocks are represented by &struct ubi_ainf_peb objects. These
+ * objects are kept in per-volume RB-trees with the root at the corresponding
+ * &struct ubi_ainf_volume object. To put it differently, we keep an RB-tree of
+ * per-volume objects and each of these objects is the root of RB-tree of
+ * per-LEB objects.
+ *
+ * Corrupted physical eraseblocks are put to the @corr list, free physical
+ * eraseblocks are put to the @free list and the physical eraseblock to be
+ * erased are put to the @erase list.
+ *
+ * About corruptions
+ * ~~~~~~~~~~~~~~~~~
+ *
+ * UBI protects EC and VID headers with CRC-32 checksums, so it can detect
+ * whether the headers are corrupted or not. Sometimes UBI also protects the
+ * data with CRC-32, e.g., when it executes the atomic LEB change operation, or
+ * when it moves the contents of a PEB for wear-leveling purposes.
+ *
+ * UBI tries to distinguish between 2 types of corruptions.
+ *
+ * 1. Corruptions caused by power cuts. These are expected corruptions and UBI
+ * tries to handle them gracefully, without printing too many warnings and
+ * error messages. The idea is that we do not lose important data in these
+ * cases - we may lose only the data which were being written to the media just
+ * before the power cut happened, and the upper layers (e.g., UBIFS) are
+ * supposed to handle such data losses (e.g., by using the FS journal).
+ *
+ * When UBI detects a corruption (CRC-32 mismatch) in a PEB, and it looks like
+ * the reason is a power cut, UBI puts this PEB to the @erase list, and all
+ * PEBs in the @erase list are scheduled for erasure later.
+ *
+ * 2. Unexpected corruptions which are not caused by power cuts. During
+ * attaching, such PEBs are put to the @corr list and UBI preserves them.
+ * Obviously, this lessens the amount of available PEBs, and if at some  point
+ * UBI runs out of free PEBs, it switches to R/O mode. UBI also loudly informs
+ * about such PEBs every time the MTD device is attached.
+ *
+ * However, it is difficult to reliably distinguish between these types of
+ * corruptions and UBI's strategy is as follows (in case of attaching by
+ * scanning). UBI assumes corruption type 2 if the VID header is corrupted and
+ * the data area does not contain all 0xFFs, and there were no bit-flips or
+ * integrity errors (e.g., ECC errors in case of NAND) while reading the data
+ * area.  Otherwise UBI assumes corruption type 1. So the decision criteria
+ * are as follows.
+ *   o If the data area contains only 0xFFs, there are no data, and it is safe
+ *     to just erase this PEB - this is corruption type 1.
+ *   o If the data area has bit-flips or data integrity errors (ECC errors on
+ *     NAND), it is probably a PEB which was being erased when power cut
+ *     happened, so this is corruption type 1. However, this is just a guess,
+ *     which might be wrong.
+ *   o Otherwise this is corruption type 2.
+ */
+
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/crc32.h>
+#include <linux/math64.h>
+#include <linux/random.h>
+#include "ubi.h"
+
+static int self_check_ai(struct ubi_device *ubi, struct ubi_attach_info *ai);
+
+#define AV_FIND		BIT(0)
+#define AV_ADD		BIT(1)
+#define AV_FIND_OR_ADD	(AV_FIND | AV_ADD)
+
+/**
+ * find_or_add_av - internal function to find a volume, add a volume or do
+ *		    both (find and add if missing).
+ * @ai: attaching information
+ * @vol_id: the requested volume ID
+ * @flags: a combination of the %AV_FIND and %AV_ADD flags describing the
+ *	   expected operation. If only %AV_ADD is set, -EEXIST is returned
+ *	   if the volume already exists. If only %AV_FIND is set, NULL is
+ *	   returned if the volume does not exist. And if both flags are
+ *	   set, the helper first tries to find an existing volume, and if
+ *	   it does not exist it creates a new one.
+ * @created: in value used to inform the caller whether it"s a newly created
+ *	     volume or not.
+ *
+ * This function returns a pointer to a volume description or an ERR_PTR if
+ * the operation failed. It can also return NULL if only %AV_FIND is set and
+ * the volume does not exist.
+ */
+static struct ubi_ainf_volume *find_or_add_av(struct ubi_attach_info *ai,
+					      int vol_id, unsigned int flags,
+					      bool *created)
+{
+	struct ubi_ainf_volume *av;
+	struct rb_node **p = &ai->volumes.rb_node, *parent = NULL;
+
+	/* Walk the volume RB-tree to look if this volume is already present */
+	while (*p) {
+		parent = *p;
+		av = rb_entry(parent, struct ubi_ainf_volume, rb);
+
+		if (vol_id == av->vol_id) {
+			*created = false;
+
+			if (!(flags & AV_FIND))
+				return ERR_PTR(-EEXIST);
+
+			return av;
+		}
+
+		if (vol_id > av->vol_id)
+			p = &(*p)->rb_left;
+		else
+			p = &(*p)->rb_right;
+	}
+
+	if (!(flags & AV_ADD))
+		return NULL;
+
+	/* The volume is absent - add it */
+	av = kzalloc(sizeof(*av), GFP_KERNEL);
+	if (!av)
+		return ERR_PTR(-ENOMEM);
+
+	av->vol_id = vol_id;
+
+	if (vol_id > ai->highest_vol_id)
+		ai->highest_vol_id = vol_id;
+
+	rb_link_node(&av->rb, parent, p);
+	rb_insert_color(&av->rb, &ai->volumes);
+	ai->vols_found += 1;
+	*created = true;
+	dbg_bld("added volume %d", vol_id);
+	return av;
+}
+
+/**
+ * ubi_find_or_add_av - search for a volume in the attaching information and
+ *			add one if it does not exist.
+ * @ai: attaching information
+ * @vol_id: the requested volume ID
+ * @created: whether the volume has been created or not
+ *
+ * This function returns a pointer to the new volume description or an
+ * ERR_PTR if the operation failed.
+ */
+static struct ubi_ainf_volume *ubi_find_or_add_av(struct ubi_attach_info *ai,
+						  int vol_id, bool *created)
+{
+	return find_or_add_av(ai, vol_id, AV_FIND_OR_ADD, created);
+}
+
+/**
+ * ubi_alloc_aeb - allocate an aeb element
+ * @ai: attaching information
+ * @pnum: physical eraseblock number
+ * @ec: erase counter of the physical eraseblock
+ *
+ * Allocate an aeb object and initialize the pnum and ec information.
+ * vol_id and lnum are set to UBI_UNKNOWN, and the other fields are
+ * initialized to zero.
+ * Note that the element is not added in any list or RB tree.
+ */
+struct ubi_ainf_peb *ubi_alloc_aeb(struct ubi_attach_info *ai, int pnum,
+				   int ec)
+{
+	struct ubi_ainf_peb *aeb;
+
+	aeb = kmem_cache_zalloc(ai->aeb_slab_cache, GFP_KERNEL);
+	if (!aeb)
+		return NULL;
+
+	aeb->pnum = pnum;
+	aeb->ec = ec;
+	aeb->vol_id = UBI_UNKNOWN;
+	aeb->lnum = UBI_UNKNOWN;
+
+	return aeb;
+}
+
+/**
+ * ubi_free_aeb - free an aeb element
+ * @ai: attaching information
+ * @aeb: the element to free
+ *
+ * Free an aeb object. The caller must have removed the element from any list
+ * or RB tree.
+ */
+void ubi_free_aeb(struct ubi_attach_info *ai, struct ubi_ainf_peb *aeb)
+{
+	kmem_cache_free(ai->aeb_slab_cache, aeb);
+}
+
+/**
+ * add_to_list - add physical eraseblock to a list.
+ * @ai: attaching information
+ * @pnum: physical eraseblock number to add
+ * @vol_id: the last used volume id for the PEB
+ * @lnum: the last used LEB number for the PEB
+ * @ec: erase counter of the physical eraseblock
+ * @to_head: if not zero, add to the head of the list
+ * @list: the list to add to
+ *
+ * This function allocates a 'struct ubi_ainf_peb' object for physical
+ * eraseblock @pnum and adds it to the "free", "erase", or "alien" lists.
+ * It stores the @lnum and @vol_id alongside, which can both be
+ * %UBI_UNKNOWN if they are not available, not readable, or not assigned.
+ * If @to_head is not zero, PEB will be added to the head of the list, which
+ * basically means it will be processed first later. E.g., we add corrupted
+ * PEBs (corrupted due to power cuts) to the head of the erase list to make
+ * sure we erase them first and get rid of corruptions ASAP. This function
+ * returns zero in case of success and a negative error code in case of
+ * failure.
+ */
+static int add_to_list(struct ubi_attach_info *ai, int pnum, int vol_id,
+		       int lnum, int ec, int to_head, struct list_head *list)
+{
+	struct ubi_ainf_peb *aeb;
+
+	if (list == &ai->free) {
+		dbg_bld("add to free: PEB %d, EC %d", pnum, ec);
+	} else if (list == &ai->erase) {
+		dbg_bld("add to erase: PEB %d, EC %d", pnum, ec);
+	} else if (list == &ai->alien) {
+		dbg_bld("add to alien: PEB %d, EC %d", pnum, ec);
+		ai->alien_peb_count += 1;
+	} else
+		BUG();
+
+	aeb = ubi_alloc_aeb(ai, pnum, ec);
+	if (!aeb)
+		return -ENOMEM;
+
+	aeb->vol_id = vol_id;
+	aeb->lnum = lnum;
+	if (to_head)
+		list_add(&aeb->u.list, list);
+	else
+		list_add_tail(&aeb->u.list, list);
+	return 0;
+}
+
+/**
+ * add_corrupted - add a corrupted physical eraseblock.
+ * @ai: attaching information
+ * @pnum: physical eraseblock number to add
+ * @ec: erase counter of the physical eraseblock
+ *
+ * This function allocates a 'struct ubi_ainf_peb' object for a corrupted
+ * physical eraseblock @pnum and adds it to the 'corr' list.  The corruption
+ * was presumably not caused by a power cut. Returns zero in case of success
+ * and a negative error code in case of failure.
+ */
+static int add_corrupted(struct ubi_attach_info *ai, int pnum, int ec)
+{
+	struct ubi_ainf_peb *aeb;
+
+	dbg_bld("add to corrupted: PEB %d, EC %d", pnum, ec);
+
+	aeb = ubi_alloc_aeb(ai, pnum, ec);
+	if (!aeb)
+		return -ENOMEM;
+
+	ai->corr_peb_count += 1;
+	list_add(&aeb->u.list, &ai->corr);
+	return 0;
+}
+
+/**
+ * add_fastmap - add a Fastmap related physical eraseblock.
+ * @ai: attaching information
+ * @pnum: physical eraseblock number the VID header came from
+ * @vid_hdr: the volume identifier header
+ * @ec: erase counter of the physical eraseblock
+ *
+ * This function allocates a 'struct ubi_ainf_peb' object for a Fastamp
+ * physical eraseblock @pnum and adds it to the 'fastmap' list.
+ * Such blocks can be Fastmap super and data blocks from both the most
+ * recent Fastmap we're attaching from or from old Fastmaps which will
+ * be erased.
+ */
+static int add_fastmap(struct ubi_attach_info *ai, int pnum,
+		       struct ubi_vid_hdr *vid_hdr, int ec)
+{
+	struct ubi_ainf_peb *aeb;
+
+	aeb = ubi_alloc_aeb(ai, pnum, ec);
+	if (!aeb)
+		return -ENOMEM;
+
+	aeb->vol_id = be32_to_cpu(vid_hdr->vol_id);
+	aeb->sqnum = be64_to_cpu(vid_hdr->sqnum);
+	list_add(&aeb->u.list, &ai->fastmap);
+
+	dbg_bld("add to fastmap list: PEB %d, vol_id %d, sqnum: %llu", pnum,
+		aeb->vol_id, aeb->sqnum);
+
+	return 0;
+}
+
+/**
+ * validate_vid_hdr - check volume identifier header.
+ * @ubi: UBI device description object
+ * @vid_hdr: the volume identifier header to check
+ * @av: information about the volume this logical eraseblock belongs to
+ * @pnum: physical eraseblock number the VID header came from
+ *
+ * This function checks that data stored in @vid_hdr is consistent. Returns
+ * non-zero if an inconsistency was found and zero if not.
+ *
+ * Note, UBI does sanity check of everything it reads from the flash media.
+ * Most of the checks are done in the I/O sub-system. Here we check that the
+ * information in the VID header is consistent to the information in other VID
+ * headers of the same volume.
+ */
+static int validate_vid_hdr(const struct ubi_device *ubi,
+			    const struct ubi_vid_hdr *vid_hdr,
+			    const struct ubi_ainf_volume *av, int pnum)
+{
+	int vol_type = vid_hdr->vol_type;
+	int vol_id = be32_to_cpu(vid_hdr->vol_id);
+	int used_ebs = be32_to_cpu(vid_hdr->used_ebs);
+	int data_pad = be32_to_cpu(vid_hdr->data_pad);
+
+	if (av->leb_count != 0) {
+		int av_vol_type;
+
+		/*
+		 * This is not the first logical eraseblock belonging to this
+		 * volume. Ensure that the data in its VID header is consistent
+		 * to the data in previous logical eraseblock headers.
+		 */
+
+		if (vol_id != av->vol_id) {
+			ubi_err(ubi, "inconsistent vol_id");
+			goto bad;
+		}
+
+		if (av->vol_type == UBI_STATIC_VOLUME)
+			av_vol_type = UBI_VID_STATIC;
+		else
+			av_vol_type = UBI_VID_DYNAMIC;
+
+		if (vol_type != av_vol_type) {
+			ubi_err(ubi, "inconsistent vol_type");
+			goto bad;
+		}
+
+		if (used_ebs != av->used_ebs) {
+			ubi_err(ubi, "inconsistent used_ebs");
+			goto bad;
+		}
+
+		if (data_pad != av->data_pad) {
+			ubi_err(ubi, "inconsistent data_pad");
+			goto bad;
+		}
+	}
+
+	return 0;
+
+bad:
+	ubi_err(ubi, "inconsistent VID header at PEB %d", pnum);
+	ubi_dump_vid_hdr(vid_hdr);
+	ubi_dump_av(av);
+	return -EINVAL;
+}
+
+/**
+ * add_volume - add volume to the attaching information.
+ * @ai: attaching information
+ * @vol_id: ID of the volume to add
+ * @pnum: physical eraseblock number
+ * @vid_hdr: volume identifier header
+ *
+ * If the volume corresponding to the @vid_hdr logical eraseblock is already
+ * present in the attaching information, this function does nothing. Otherwise
+ * it adds corresponding volume to the attaching information. Returns a pointer
+ * to the allocated "av" object in case of success and a negative error code in
+ * case of failure.
+ */
+static struct ubi_ainf_volume *add_volume(struct ubi_attach_info *ai,
+					  int vol_id, int pnum,
+					  const struct ubi_vid_hdr *vid_hdr)
+{
+	struct ubi_ainf_volume *av;
+	bool created;
+
+	ubi_assert(vol_id == be32_to_cpu(vid_hdr->vol_id));
+
+	av = ubi_find_or_add_av(ai, vol_id, &created);
+	if (IS_ERR(av) || !created)
+		return av;
+
+	av->used_ebs = be32_to_cpu(vid_hdr->used_ebs);
+	av->data_pad = be32_to_cpu(vid_hdr->data_pad);
+	av->compat = vid_hdr->compat;
+	av->vol_type = vid_hdr->vol_type == UBI_VID_DYNAMIC ? UBI_DYNAMIC_VOLUME
+							    : UBI_STATIC_VOLUME;
+
+	return av;
+}
+
+/**
+ * ubi_compare_lebs - find out which logical eraseblock is newer.
+ * @ubi: UBI device description object
+ * @aeb: first logical eraseblock to compare
+ * @pnum: physical eraseblock number of the second logical eraseblock to
+ * compare
+ * @vid_hdr: volume identifier header of the second logical eraseblock
+ *
+ * This function compares 2 copies of a LEB and informs which one is newer. In
+ * case of success this function returns a positive value, in case of failure, a
+ * negative error code is returned. The success return codes use the following
+ * bits:
+ *     o bit 0 is cleared: the first PEB (described by @aeb) is newer than the
+ *       second PEB (described by @pnum and @vid_hdr);
+ *     o bit 0 is set: the second PEB is newer;
+ *     o bit 1 is cleared: no bit-flips were detected in the newer LEB;
+ *     o bit 1 is set: bit-flips were detected in the newer LEB;
+ *     o bit 2 is cleared: the older LEB is not corrupted;
+ *     o bit 2 is set: the older LEB is corrupted.
+ */
+int ubi_compare_lebs(struct ubi_device *ubi, const struct ubi_ainf_peb *aeb,
+			int pnum, const struct ubi_vid_hdr *vid_hdr)
+{
+	int len, err, second_is_newer, bitflips = 0, corrupted = 0;
+	uint32_t data_crc, crc;
+	struct ubi_vid_io_buf *vidb = NULL;
+	unsigned long long sqnum2 = be64_to_cpu(vid_hdr->sqnum);
+
+	if (sqnum2 == aeb->sqnum) {
+		/*
+		 * This must be a really ancient UBI image which has been
+		 * created before sequence numbers support has been added. At
+		 * that times we used 32-bit LEB versions stored in logical
+		 * eraseblocks. That was before UBI got into mainline. We do not
+		 * support these images anymore. Well, those images still work,
+		 * but only if no unclean reboots happened.
+		 */
+		ubi_err(ubi, "unsupported on-flash UBI format");
+		return -EINVAL;
+	}
+
+	/* Obviously the LEB with lower sequence counter is older */
+	second_is_newer = (sqnum2 > aeb->sqnum);
+
+	/*
+	 * Now we know which copy is newer. If the copy flag of the PEB with
+	 * newer version is not set, then we just return, otherwise we have to
+	 * check data CRC. For the second PEB we already have the VID header,
+	 * for the first one - we'll need to re-read it from flash.
+	 *
+	 * Note: this may be optimized so that we wouldn't read twice.
+	 */
+
+	if (second_is_newer) {
+		if (!vid_hdr->copy_flag) {
+			/* It is not a copy, so it is newer */
+			dbg_bld("second PEB %d is newer, copy_flag is unset",
+				pnum);
+			return 1;
+		}
+	} else {
+		if (!aeb->copy_flag) {
+			/* It is not a copy, so it is newer */
+			dbg_bld("first PEB %d is newer, copy_flag is unset",
+				pnum);
+			return bitflips << 1;
+		}
+
+		vidb = ubi_alloc_vid_buf(ubi, GFP_KERNEL);
+		if (!vidb)
+			return -ENOMEM;
+
+		pnum = aeb->pnum;
+		err = ubi_io_read_vid_hdr(ubi, pnum, vidb, 0);
+		if (err) {
+			if (err == UBI_IO_BITFLIPS)
+				bitflips = 1;
+			else {
+				ubi_err(ubi, "VID of PEB %d header is bad, but it was OK earlier, err %d",
+					pnum, err);
+				if (err > 0)
+					err = -EIO;
+
+				goto out_free_vidh;
+			}
+		}
+
+		vid_hdr = ubi_get_vid_hdr(vidb);
+	}
+
+	/* Read the data of the copy and check the CRC */
+
+	len = be32_to_cpu(vid_hdr->data_size);
+
+	mutex_lock(&ubi->buf_mutex);
+	err = ubi_io_read_data(ubi, ubi->peb_buf, pnum, 0, len);
+	if (err && err != UBI_IO_BITFLIPS && !mtd_is_eccerr(err))
+		goto out_unlock;
+
+	data_crc = be32_to_cpu(vid_hdr->data_crc);
+	crc = crc32(UBI_CRC32_INIT, ubi->peb_buf, len);
+	if (crc != data_crc) {
+		dbg_bld("PEB %d CRC error: calculated %#08x, must be %#08x",
+			pnum, crc, data_crc);
+		corrupted = 1;
+		bitflips = 0;
+		second_is_newer = !second_is_newer;
+	} else {
+		dbg_bld("PEB %d CRC is OK", pnum);
+		bitflips |= !!err;
+	}
+	mutex_unlock(&ubi->buf_mutex);
+
+	ubi_free_vid_buf(vidb);
+
+	if (second_is_newer)
+		dbg_bld("second PEB %d is newer, copy_flag is set", pnum);
+	else
+		dbg_bld("first PEB %d is newer, copy_flag is set", pnum);
+
+	return second_is_newer | (bitflips << 1) | (corrupted << 2);
+
+out_unlock:
+	mutex_unlock(&ubi->buf_mutex);
+out_free_vidh:
+	ubi_free_vid_buf(vidb);
+	return err;
+}
+
+/**
+ * ubi_add_to_av - add used physical eraseblock to the attaching information.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ * @pnum: the physical eraseblock number
+ * @ec: erase counter
+ * @vid_hdr: the volume identifier header
+ * @bitflips: if bit-flips were detected when this physical eraseblock was read
+ *
+ * This function adds information about a used physical eraseblock to the
+ * 'used' tree of the corresponding volume. The function is rather complex
+ * because it has to handle cases when this is not the first physical
+ * eraseblock belonging to the same logical eraseblock, and the newer one has
+ * to be picked, while the older one has to be dropped. This function returns
+ * zero in case of success and a negative error code in case of failure.
+ */
+int ubi_add_to_av(struct ubi_device *ubi, struct ubi_attach_info *ai, int pnum,
+		  int ec, const struct ubi_vid_hdr *vid_hdr, int bitflips)
+{
+	int err, vol_id, lnum;
+	unsigned long long sqnum;
+	struct ubi_ainf_volume *av;
+	struct ubi_ainf_peb *aeb;
+	struct rb_node **p, *parent = NULL;
+
+	vol_id = be32_to_cpu(vid_hdr->vol_id);
+	lnum = be32_to_cpu(vid_hdr->lnum);
+	sqnum = be64_to_cpu(vid_hdr->sqnum);
+
+	dbg_bld("PEB %d, LEB %d:%d, EC %d, sqnum %llu, bitflips %d",
+		pnum, vol_id, lnum, ec, sqnum, bitflips);
+
+	av = add_volume(ai, vol_id, pnum, vid_hdr);
+	if (IS_ERR(av))
+		return PTR_ERR(av);
+
+	if (ai->max_sqnum < sqnum)
+		ai->max_sqnum = sqnum;
+
+	/*
+	 * Walk the RB-tree of logical eraseblocks of volume @vol_id to look
+	 * if this is the first instance of this logical eraseblock or not.
+	 */
+	p = &av->root.rb_node;
+	while (*p) {
+		int cmp_res;
+
+		parent = *p;
+		aeb = rb_entry(parent, struct ubi_ainf_peb, u.rb);
+		if (lnum != aeb->lnum) {
+			if (lnum < aeb->lnum)
+				p = &(*p)->rb_left;
+			else
+				p = &(*p)->rb_right;
+			continue;
+		}
+
+		/*
+		 * There is already a physical eraseblock describing the same
+		 * logical eraseblock present.
+		 */
+
+		dbg_bld("this LEB already exists: PEB %d, sqnum %llu, EC %d",
+			aeb->pnum, aeb->sqnum, aeb->ec);
+
+		/*
+		 * Make sure that the logical eraseblocks have different
+		 * sequence numbers. Otherwise the image is bad.
+		 *
+		 * However, if the sequence number is zero, we assume it must
+		 * be an ancient UBI image from the era when UBI did not have
+		 * sequence numbers. We still can attach these images, unless
+		 * there is a need to distinguish between old and new
+		 * eraseblocks, in which case we'll refuse the image in
+		 * 'ubi_compare_lebs()'. In other words, we attach old clean
+		 * images, but refuse attaching old images with duplicated
+		 * logical eraseblocks because there was an unclean reboot.
+		 */
+		if (aeb->sqnum == sqnum && sqnum != 0) {
+			ubi_err(ubi, "two LEBs with same sequence number %llu",
+				sqnum);
+			ubi_dump_aeb(aeb, 0);
+			ubi_dump_vid_hdr(vid_hdr);
+			return -EINVAL;
+		}
+
+		/*
+		 * Now we have to drop the older one and preserve the newer
+		 * one.
+		 */
+		cmp_res = ubi_compare_lebs(ubi, aeb, pnum, vid_hdr);
+		if (cmp_res < 0)
+			return cmp_res;
+
+		if (cmp_res & 1) {
+			/*
+			 * This logical eraseblock is newer than the one
+			 * found earlier.
+			 */
+			err = validate_vid_hdr(ubi, vid_hdr, av, pnum);
+			if (err)
+				return err;
+
+			err = add_to_list(ai, aeb->pnum, aeb->vol_id,
+					  aeb->lnum, aeb->ec, cmp_res & 4,
+					  &ai->erase);
+			if (err)
+				return err;
+
+			aeb->ec = ec;
+			aeb->pnum = pnum;
+			aeb->vol_id = vol_id;
+			aeb->lnum = lnum;
+			aeb->scrub = ((cmp_res & 2) || bitflips);
+			aeb->copy_flag = vid_hdr->copy_flag;
+			aeb->sqnum = sqnum;
+
+			if (av->highest_lnum == lnum)
+				av->last_data_size =
+					be32_to_cpu(vid_hdr->data_size);
+
+			return 0;
+		} else {
+			/*
+			 * This logical eraseblock is older than the one found
+			 * previously.
+			 */
+			return add_to_list(ai, pnum, vol_id, lnum, ec,
+					   cmp_res & 4, &ai->erase);
+		}
+	}
+
+	/*
+	 * We've met this logical eraseblock for the first time, add it to the
+	 * attaching information.
+	 */
+
+	err = validate_vid_hdr(ubi, vid_hdr, av, pnum);
+	if (err)
+		return err;
+
+	aeb = ubi_alloc_aeb(ai, pnum, ec);
+	if (!aeb)
+		return -ENOMEM;
+
+	aeb->vol_id = vol_id;
+	aeb->lnum = lnum;
+	aeb->scrub = bitflips;
+	aeb->copy_flag = vid_hdr->copy_flag;
+	aeb->sqnum = sqnum;
+
+	if (av->highest_lnum <= lnum) {
+		av->highest_lnum = lnum;
+		av->last_data_size = be32_to_cpu(vid_hdr->data_size);
+	}
+
+	av->leb_count += 1;
+	rb_link_node(&aeb->u.rb, parent, p);
+	rb_insert_color(&aeb->u.rb, &av->root);
+	return 0;
+}
+
+/**
+ * ubi_add_av - add volume to the attaching information.
+ * @ai: attaching information
+ * @vol_id: the requested volume ID
+ *
+ * This function returns a pointer to the new volume description or an
+ * ERR_PTR if the operation failed.
+ */
+struct ubi_ainf_volume *ubi_add_av(struct ubi_attach_info *ai, int vol_id)
+{
+	bool created;
+
+	return find_or_add_av(ai, vol_id, AV_ADD, &created);
+}
+
+/**
+ * ubi_find_av - find volume in the attaching information.
+ * @ai: attaching information
+ * @vol_id: the requested volume ID
+ *
+ * This function returns a pointer to the volume description or %NULL if there
+ * are no data about this volume in the attaching information.
+ */
+struct ubi_ainf_volume *ubi_find_av(const struct ubi_attach_info *ai,
+				    int vol_id)
+{
+	bool created;
+
+	return find_or_add_av((struct ubi_attach_info *)ai, vol_id, AV_FIND,
+			      &created);
+}
+
+static void destroy_av(struct ubi_attach_info *ai, struct ubi_ainf_volume *av,
+		       struct list_head *list);
+
+/**
+ * ubi_remove_av - delete attaching information about a volume.
+ * @ai: attaching information
+ * @av: the volume attaching information to delete
+ */
+void ubi_remove_av(struct ubi_attach_info *ai, struct ubi_ainf_volume *av)
+{
+	dbg_bld("remove attaching information about volume %d", av->vol_id);
+
+	rb_erase(&av->rb, &ai->volumes);
+	destroy_av(ai, av, &ai->erase);
+	ai->vols_found -= 1;
+}
+
+/**
+ * early_erase_peb - erase a physical eraseblock.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ * @pnum: physical eraseblock number to erase;
+ * @ec: erase counter value to write (%UBI_UNKNOWN if it is unknown)
+ *
+ * This function erases physical eraseblock 'pnum', and writes the erase
+ * counter header to it. This function should only be used on UBI device
+ * initialization stages, when the EBA sub-system had not been yet initialized.
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int early_erase_peb(struct ubi_device *ubi,
+			   const struct ubi_attach_info *ai, int pnum, int ec)
+{
+	int err;
+	struct ubi_ec_hdr *ec_hdr;
+
+	if ((long long)ec >= UBI_MAX_ERASECOUNTER) {
+		/*
+		 * Erase counter overflow. Upgrade UBI and use 64-bit
+		 * erase counters internally.
+		 */
+		ubi_err(ubi, "erase counter overflow at PEB %d, EC %d",
+			pnum, ec);
+		return -EINVAL;
+	}
+
+	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!ec_hdr)
+		return -ENOMEM;
+
+	ec_hdr->ec = cpu_to_be64(ec);
+
+	err = ubi_io_sync_erase(ubi, pnum, 0);
+	if (err < 0)
+		goto out_free;
+
+	err = ubi_io_write_ec_hdr(ubi, pnum, ec_hdr);
+
+out_free:
+	kfree(ec_hdr);
+	return err;
+}
+
+/**
+ * ubi_early_get_peb - get a free physical eraseblock.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ *
+ * This function returns a free physical eraseblock. It is supposed to be
+ * called on the UBI initialization stages when the wear-leveling sub-system is
+ * not initialized yet. This function picks a physical eraseblocks from one of
+ * the lists, writes the EC header if it is needed, and removes it from the
+ * list.
+ *
+ * This function returns a pointer to the "aeb" of the found free PEB in case
+ * of success and an error code in case of failure.
+ */
+struct ubi_ainf_peb *ubi_early_get_peb(struct ubi_device *ubi,
+				       struct ubi_attach_info *ai)
+{
+	int err = 0;
+	struct ubi_ainf_peb *aeb, *tmp_aeb;
+
+	if (!list_empty(&ai->free)) {
+		aeb = list_entry(ai->free.next, struct ubi_ainf_peb, u.list);
+		list_del(&aeb->u.list);
+		dbg_bld("return free PEB %d, EC %d", aeb->pnum, aeb->ec);
+		return aeb;
+	}
+
+	/*
+	 * We try to erase the first physical eraseblock from the erase list
+	 * and pick it if we succeed, or try to erase the next one if not. And
+	 * so forth. We don't want to take care about bad eraseblocks here -
+	 * they'll be handled later.
+	 */
+	list_for_each_entry_safe(aeb, tmp_aeb, &ai->erase, u.list) {
+		if (aeb->ec == UBI_UNKNOWN)
+			aeb->ec = ai->mean_ec;
+
+		err = early_erase_peb(ubi, ai, aeb->pnum, aeb->ec+1);
+		if (err)
+			continue;
+
+		aeb->ec += 1;
+		list_del(&aeb->u.list);
+		dbg_bld("return PEB %d, EC %d", aeb->pnum, aeb->ec);
+		return aeb;
+	}
+
+	ubi_err(ubi, "no free eraseblocks");
+	return ERR_PTR(-ENOSPC);
+}
+
+/**
+ * check_corruption - check the data area of PEB.
+ * @ubi: UBI device description object
+ * @vid_hdr: the (corrupted) VID header of this PEB
+ * @pnum: the physical eraseblock number to check
+ *
+ * This is a helper function which is used to distinguish between VID header
+ * corruptions caused by power cuts and other reasons. If the PEB contains only
+ * 0xFF bytes in the data area, the VID header is most probably corrupted
+ * because of a power cut (%0 is returned in this case). Otherwise, it was
+ * probably corrupted for some other reasons (%1 is returned in this case). A
+ * negative error code is returned if a read error occurred.
+ *
+ * If the corruption reason was a power cut, UBI can safely erase this PEB.
+ * Otherwise, it should preserve it to avoid possibly destroying important
+ * information.
+ */
+static int check_corruption(struct ubi_device *ubi, struct ubi_vid_hdr *vid_hdr,
+			    int pnum)
+{
+	int err;
+
+	mutex_lock(&ubi->buf_mutex);
+	memset(ubi->peb_buf, 0x00, ubi->leb_size);
+
+	err = ubi_io_read(ubi, ubi->peb_buf, pnum, ubi->leb_start,
+			  ubi->leb_size);
+	if (err == UBI_IO_BITFLIPS || mtd_is_eccerr(err)) {
+		/*
+		 * Bit-flips or integrity errors while reading the data area.
+		 * It is difficult to say for sure what type of corruption is
+		 * this, but presumably a power cut happened while this PEB was
+		 * erased, so it became unstable and corrupted, and should be
+		 * erased.
+		 */
+		err = 0;
+		goto out_unlock;
+	}
+
+	if (err)
+		goto out_unlock;
+
+	if (ubi_check_pattern(ubi->peb_buf, 0xFF, ubi->leb_size))
+		goto out_unlock;
+
+	ubi_err(ubi, "PEB %d contains corrupted VID header, and the data does not contain all 0xFF",
+		pnum);
+	ubi_err(ubi, "this may be a non-UBI PEB or a severe VID header corruption which requires manual inspection");
+	ubi_dump_vid_hdr(vid_hdr);
+	pr_err("hexdump of PEB %d offset %d, length %d",
+	       pnum, ubi->leb_start, ubi->leb_size);
+	ubi_dbg_print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
+			       ubi->peb_buf, ubi->leb_size, 1);
+	err = 1;
+
+out_unlock:
+	mutex_unlock(&ubi->buf_mutex);
+	return err;
+}
+
+static bool vol_ignored(int vol_id)
+{
+	switch (vol_id) {
+		case UBI_LAYOUT_VOLUME_ID:
+		return true;
+	}
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+	return ubi_is_fm_vol(vol_id);
+#else
+	return false;
+#endif
+}
+
+/**
+ * scan_peb - scan and process UBI headers of a PEB.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ * @pnum: the physical eraseblock number
+ * @fast: true if we're scanning for a Fastmap
+ *
+ * This function reads UBI headers of PEB @pnum, checks them, and adds
+ * information about this PEB to the corresponding list or RB-tree in the
+ * "attaching info" structure. Returns zero if the physical eraseblock was
+ * successfully handled and a negative error code in case of failure.
+ */
+static int scan_peb(struct ubi_device *ubi, struct ubi_attach_info *ai,
+		    int pnum, bool fast)
+{
+	struct ubi_ec_hdr *ech = ai->ech;
+	struct ubi_vid_io_buf *vidb = ai->vidb;
+	struct ubi_vid_hdr *vidh = ubi_get_vid_hdr(vidb);
+	long long ec;
+	int err, bitflips = 0, vol_id = -1, ec_err = 0;
+
+	dbg_bld("scan PEB %d", pnum);
+
+	/* Skip bad physical eraseblocks */
+	err = ubi_io_is_bad(ubi, pnum);
+	if (err < 0)
+		return err;
+	else if (err) {
+		ai->bad_peb_count += 1;
+		return 0;
+	}
+
+	err = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
+	if (err < 0)
+		return err;
+	switch (err) {
+	case 0:
+		break;
+	case UBI_IO_BITFLIPS:
+		bitflips = 1;
+		break;
+	case UBI_IO_FF:
+		ai->empty_peb_count += 1;
+		return add_to_list(ai, pnum, UBI_UNKNOWN, UBI_UNKNOWN,
+				   UBI_UNKNOWN, 0, &ai->erase);
+	case UBI_IO_FF_BITFLIPS:
+		ai->empty_peb_count += 1;
+		return add_to_list(ai, pnum, UBI_UNKNOWN, UBI_UNKNOWN,
+				   UBI_UNKNOWN, 1, &ai->erase);
+	case UBI_IO_BAD_HDR_EBADMSG:
+	case UBI_IO_BAD_HDR:
+		/*
+		 * We have to also look at the VID header, possibly it is not
+		 * corrupted. Set %bitflips flag in order to make this PEB be
+		 * moved and EC be re-created.
+		 */
+		ec_err = err;
+		ec = UBI_UNKNOWN;
+		bitflips = 1;
+		break;
+	default:
+		ubi_err(ubi, "'ubi_io_read_ec_hdr()' returned unknown code %d",
+			err);
+		return -EINVAL;
+	}
+
+	if (!ec_err) {
+		int image_seq;
+
+		/* Make sure UBI version is OK */
+		if (ech->version != UBI_VERSION) {
+			ubi_err(ubi, "this UBI version is %d, image version is %d",
+				UBI_VERSION, (int)ech->version);
+			return -EINVAL;
+		}
+
+		ec = be64_to_cpu(ech->ec);
+		if (ec > UBI_MAX_ERASECOUNTER) {
+			/*
+			 * Erase counter overflow. The EC headers have 64 bits
+			 * reserved, but we anyway make use of only 31 bit
+			 * values, as this seems to be enough for any existing
+			 * flash. Upgrade UBI and use 64-bit erase counters
+			 * internally.
+			 */
+			ubi_err(ubi, "erase counter overflow, max is %d",
+				UBI_MAX_ERASECOUNTER);
+			ubi_dump_ec_hdr(ech);
+			return -EINVAL;
+		}
+
+		/*
+		 * Make sure that all PEBs have the same image sequence number.
+		 * This allows us to detect situations when users flash UBI
+		 * images incorrectly, so that the flash has the new UBI image
+		 * and leftovers from the old one. This feature was added
+		 * relatively recently, and the sequence number was always
+		 * zero, because old UBI implementations always set it to zero.
+		 * For this reasons, we do not panic if some PEBs have zero
+		 * sequence number, while other PEBs have non-zero sequence
+		 * number.
+		 */
+		image_seq = be32_to_cpu(ech->image_seq);
+		if (!ubi->image_seq)
+			ubi->image_seq = image_seq;
+		if (image_seq && ubi->image_seq != image_seq) {
+			ubi_err(ubi, "bad image sequence number %d in PEB %d, expected %d",
+				image_seq, pnum, ubi->image_seq);
+			ubi_dump_ec_hdr(ech);
+			return -EINVAL;
+		}
+	}
+
+	/* OK, we've done with the EC header, let's look at the VID header */
+
+	err = ubi_io_read_vid_hdr(ubi, pnum, vidb, 0);
+	if (err < 0)
+		return err;
+	switch (err) {
+	case 0:
+		break;
+	case UBI_IO_BITFLIPS:
+		bitflips = 1;
+		break;
+	case UBI_IO_BAD_HDR_EBADMSG:
+		if (ec_err == UBI_IO_BAD_HDR_EBADMSG)
+			/*
+			 * Both EC and VID headers are corrupted and were read
+			 * with data integrity error, probably this is a bad
+			 * PEB, bit it is not marked as bad yet. This may also
+			 * be a result of power cut during erasure.
+			 */
+			ai->maybe_bad_peb_count += 1;
+		fallthrough;
+	case UBI_IO_BAD_HDR:
+			/*
+			 * If we're facing a bad VID header we have to drop *all*
+			 * Fastmap data structures we find. The most recent Fastmap
+			 * could be bad and therefore there is a chance that we attach
+			 * from an old one. On a fine MTD stack a PEB must not render
+			 * bad all of a sudden, but the reality is different.
+			 * So, let's be paranoid and help finding the root cause by
+			 * falling back to scanning mode instead of attaching with a
+			 * bad EBA table and cause data corruption which is hard to
+			 * analyze.
+			 */
+			if (fast)
+				ai->force_full_scan = 1;
+
+		if (ec_err)
+			/*
+			 * Both headers are corrupted. There is a possibility
+			 * that this a valid UBI PEB which has corresponding
+			 * LEB, but the headers are corrupted. However, it is
+			 * impossible to distinguish it from a PEB which just
+			 * contains garbage because of a power cut during erase
+			 * operation. So we just schedule this PEB for erasure.
+			 *
+			 * Besides, in case of NOR flash, we deliberately
+			 * corrupt both headers because NOR flash erasure is
+			 * slow and can start from the end.
+			 */
+			err = 0;
+		else
+			/*
+			 * The EC was OK, but the VID header is corrupted. We
+			 * have to check what is in the data area.
+			 */
+			err = check_corruption(ubi, vidh, pnum);
+
+		if (err < 0)
+			return err;
+		else if (!err)
+			/* This corruption is caused by a power cut */
+			err = add_to_list(ai, pnum, UBI_UNKNOWN,
+					  UBI_UNKNOWN, ec, 1, &ai->erase);
+		else
+			/* This is an unexpected corruption */
+			err = add_corrupted(ai, pnum, ec);
+		if (err)
+			return err;
+		goto adjust_mean_ec;
+	case UBI_IO_FF_BITFLIPS:
+		err = add_to_list(ai, pnum, UBI_UNKNOWN, UBI_UNKNOWN,
+				  ec, 1, &ai->erase);
+		if (err)
+			return err;
+		goto adjust_mean_ec;
+	case UBI_IO_FF:
+		if (ec_err || bitflips)
+			err = add_to_list(ai, pnum, UBI_UNKNOWN,
+					  UBI_UNKNOWN, ec, 1, &ai->erase);
+		else
+			err = add_to_list(ai, pnum, UBI_UNKNOWN,
+					  UBI_UNKNOWN, ec, 0, &ai->free);
+		if (err)
+			return err;
+		goto adjust_mean_ec;
+	default:
+		ubi_err(ubi, "'ubi_io_read_vid_hdr()' returned unknown code %d",
+			err);
+		return -EINVAL;
+	}
+
+	vol_id = be32_to_cpu(vidh->vol_id);
+	if (vol_id > UBI_MAX_VOLUMES && !vol_ignored(vol_id)) {
+		int lnum = be32_to_cpu(vidh->lnum);
+
+		/* Unsupported internal volume */
+		switch (vidh->compat) {
+		case UBI_COMPAT_DELETE:
+			ubi_msg(ubi, "\"delete\" compatible internal volume %d:%d found, will remove it",
+				vol_id, lnum);
+
+			err = add_to_list(ai, pnum, vol_id, lnum,
+					  ec, 1, &ai->erase);
+			if (err)
+				return err;
+			return 0;
+
+		case UBI_COMPAT_RO:
+			ubi_msg(ubi, "read-only compatible internal volume %d:%d found, switch to read-only mode",
+				vol_id, lnum);
+			ubi->ro_mode = 1;
+			break;
+
+		case UBI_COMPAT_PRESERVE:
+			ubi_msg(ubi, "\"preserve\" compatible internal volume %d:%d found",
+				vol_id, lnum);
+			err = add_to_list(ai, pnum, vol_id, lnum,
+					  ec, 0, &ai->alien);
+			if (err)
+				return err;
+			return 0;
+
+		case UBI_COMPAT_REJECT:
+			ubi_err(ubi, "incompatible internal volume %d:%d found",
+				vol_id, lnum);
+			return -EINVAL;
+		}
+	}
+
+	if (ec_err)
+		ubi_warn(ubi, "valid VID header but corrupted EC header at PEB %d",
+			 pnum);
+
+	if (ubi_is_fm_vol(vol_id))
+		err = add_fastmap(ai, pnum, vidh, ec);
+	else
+		err = ubi_add_to_av(ubi, ai, pnum, ec, vidh, bitflips);
+
+	if (err)
+		return err;
+
+adjust_mean_ec:
+	if (!ec_err) {
+		ai->ec_sum += ec;
+		ai->ec_count += 1;
+		if (ec > ai->max_ec)
+			ai->max_ec = ec;
+		if (ec < ai->min_ec)
+			ai->min_ec = ec;
+	}
+
+	return 0;
+}
+
+/**
+ * late_analysis - analyze the overall situation with PEB.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ *
+ * This is a helper function which takes a look what PEBs we have after we
+ * gather information about all of them ("ai" is compete). It decides whether
+ * the flash is empty and should be formatted of whether there are too many
+ * corrupted PEBs and we should not attach this MTD device. Returns zero if we
+ * should proceed with attaching the MTD device, and %-EINVAL if we should not.
+ */
+static int late_analysis(struct ubi_device *ubi, struct ubi_attach_info *ai)
+{
+	struct ubi_ainf_peb *aeb;
+	int max_corr, peb_count;
+
+	peb_count = ubi->peb_count - ai->bad_peb_count - ai->alien_peb_count;
+	max_corr = peb_count / 20 ?: 8;
+
+	/*
+	 * Few corrupted PEBs is not a problem and may be just a result of
+	 * unclean reboots. However, many of them may indicate some problems
+	 * with the flash HW or driver.
+	 */
+	if (ai->corr_peb_count) {
+		ubi_err(ubi, "%d PEBs are corrupted and preserved",
+			ai->corr_peb_count);
+		pr_err("Corrupted PEBs are:");
+		list_for_each_entry(aeb, &ai->corr, u.list)
+			pr_cont(" %d", aeb->pnum);
+		pr_cont("\n");
+
+		/*
+		 * If too many PEBs are corrupted, we refuse attaching,
+		 * otherwise, only print a warning.
+		 */
+		if (ai->corr_peb_count >= max_corr) {
+			ubi_err(ubi, "too many corrupted PEBs, refusing");
+			return -EINVAL;
+		}
+	}
+
+	if (ai->empty_peb_count + ai->maybe_bad_peb_count == peb_count) {
+		/*
+		 * All PEBs are empty, or almost all - a couple PEBs look like
+		 * they may be bad PEBs which were not marked as bad yet.
+		 *
+		 * This piece of code basically tries to distinguish between
+		 * the following situations:
+		 *
+		 * 1. Flash is empty, but there are few bad PEBs, which are not
+		 *    marked as bad so far, and which were read with error. We
+		 *    want to go ahead and format this flash. While formatting,
+		 *    the faulty PEBs will probably be marked as bad.
+		 *
+		 * 2. Flash contains non-UBI data and we do not want to format
+		 *    it and destroy possibly important information.
+		 */
+		if (ai->maybe_bad_peb_count <= 2) {
+			ai->is_empty = 1;
+			ubi_msg(ubi, "empty MTD device detected");
+			get_random_bytes(&ubi->image_seq,
+					 sizeof(ubi->image_seq));
+		} else {
+			ubi_err(ubi, "MTD device is not UBI-formatted and possibly contains non-UBI data - refusing it");
+			return -EINVAL;
+		}
+
+	}
+
+	return 0;
+}
+
+/**
+ * destroy_av - free volume attaching information.
+ * @av: volume attaching information
+ * @ai: attaching information
+ * @list: put the aeb elements in there if !NULL, otherwise free them
+ *
+ * This function destroys the volume attaching information.
+ */
+static void destroy_av(struct ubi_attach_info *ai, struct ubi_ainf_volume *av,
+		       struct list_head *list)
+{
+	struct ubi_ainf_peb *aeb;
+	struct rb_node *this = av->root.rb_node;
+
+	while (this) {
+		if (this->rb_left)
+			this = this->rb_left;
+		else if (this->rb_right)
+			this = this->rb_right;
+		else {
+			aeb = rb_entry(this, struct ubi_ainf_peb, u.rb);
+			this = rb_parent(this);
+			if (this) {
+				if (this->rb_left == &aeb->u.rb)
+					this->rb_left = NULL;
+				else
+					this->rb_right = NULL;
+			}
+
+			if (list)
+				list_add_tail(&aeb->u.list, list);
+			else
+				ubi_free_aeb(ai, aeb);
+		}
+	}
+	kfree(av);
+}
+
+/**
+ * destroy_ai - destroy attaching information.
+ * @ai: attaching information
+ */
+static void destroy_ai(struct ubi_attach_info *ai)
+{
+	struct ubi_ainf_peb *aeb, *aeb_tmp;
+	struct ubi_ainf_volume *av;
+	struct rb_node *rb;
+
+	list_for_each_entry_safe(aeb, aeb_tmp, &ai->alien, u.list) {
+		list_del(&aeb->u.list);
+		ubi_free_aeb(ai, aeb);
+	}
+	list_for_each_entry_safe(aeb, aeb_tmp, &ai->erase, u.list) {
+		list_del(&aeb->u.list);
+		ubi_free_aeb(ai, aeb);
+	}
+	list_for_each_entry_safe(aeb, aeb_tmp, &ai->corr, u.list) {
+		list_del(&aeb->u.list);
+		ubi_free_aeb(ai, aeb);
+	}
+	list_for_each_entry_safe(aeb, aeb_tmp, &ai->free, u.list) {
+		list_del(&aeb->u.list);
+		ubi_free_aeb(ai, aeb);
+	}
+	list_for_each_entry_safe(aeb, aeb_tmp, &ai->fastmap, u.list) {
+		list_del(&aeb->u.list);
+		ubi_free_aeb(ai, aeb);
+	}
+
+	/* Destroy the volume RB-tree */
+	rb = ai->volumes.rb_node;
+	while (rb) {
+		if (rb->rb_left)
+			rb = rb->rb_left;
+		else if (rb->rb_right)
+			rb = rb->rb_right;
+		else {
+			av = rb_entry(rb, struct ubi_ainf_volume, rb);
+
+			rb = rb_parent(rb);
+			if (rb) {
+				if (rb->rb_left == &av->rb)
+					rb->rb_left = NULL;
+				else
+					rb->rb_right = NULL;
+			}
+
+			destroy_av(ai, av, NULL);
+		}
+	}
+
+	kmem_cache_destroy(ai->aeb_slab_cache);
+	kfree(ai);
+}
+
+/**
+ * scan_all - scan entire MTD device.
+ * @ubi: UBI device description object
+ * @ai: attach info object
+ * @start: start scanning at this PEB
+ *
+ * This function does full scanning of an MTD device and returns complete
+ * information about it in form of a "struct ubi_attach_info" object. In case
+ * of failure, an error code is returned.
+ */
+static int scan_all(struct ubi_device *ubi, struct ubi_attach_info *ai,
+		    int start)
+{
+	int err, pnum;
+	struct rb_node *rb1, *rb2;
+	struct ubi_ainf_volume *av;
+	struct ubi_ainf_peb *aeb;
+
+	err = -ENOMEM;
+
+	ai->ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!ai->ech)
+		return err;
+
+	ai->vidb = ubi_alloc_vid_buf(ubi, GFP_KERNEL);
+	if (!ai->vidb)
+		goto out_ech;
+
+	for (pnum = start; pnum < ubi->peb_count; pnum++) {
+		cond_resched();
+
+		dbg_gen("process PEB %d", pnum);
+		err = scan_peb(ubi, ai, pnum, false);
+		if (err < 0)
+			goto out_vidh;
+	}
+
+	ubi_msg(ubi, "scanning is finished");
+
+	/* Calculate mean erase counter */
+	if (ai->ec_count)
+		ai->mean_ec = div_u64(ai->ec_sum, ai->ec_count);
+
+	err = late_analysis(ubi, ai);
+	if (err)
+		goto out_vidh;
+
+	/*
+	 * In case of unknown erase counter we use the mean erase counter
+	 * value.
+	 */
+	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb) {
+		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb)
+			if (aeb->ec == UBI_UNKNOWN)
+				aeb->ec = ai->mean_ec;
+	}
+
+	list_for_each_entry(aeb, &ai->free, u.list) {
+		if (aeb->ec == UBI_UNKNOWN)
+			aeb->ec = ai->mean_ec;
+	}
+
+	list_for_each_entry(aeb, &ai->corr, u.list)
+		if (aeb->ec == UBI_UNKNOWN)
+			aeb->ec = ai->mean_ec;
+
+	list_for_each_entry(aeb, &ai->erase, u.list)
+		if (aeb->ec == UBI_UNKNOWN)
+			aeb->ec = ai->mean_ec;
+
+	err = self_check_ai(ubi, ai);
+	if (err)
+		goto out_vidh;
+
+	ubi_free_vid_buf(ai->vidb);
+	kfree(ai->ech);
+
+	return 0;
+
+out_vidh:
+	ubi_free_vid_buf(ai->vidb);
+out_ech:
+	kfree(ai->ech);
+	return err;
+}
+
+static struct ubi_attach_info *alloc_ai(void)
+{
+	struct ubi_attach_info *ai;
+
+	ai = kzalloc(sizeof(struct ubi_attach_info), GFP_KERNEL);
+	if (!ai)
+		return ai;
+
+	INIT_LIST_HEAD(&ai->corr);
+	INIT_LIST_HEAD(&ai->free);
+	INIT_LIST_HEAD(&ai->erase);
+	INIT_LIST_HEAD(&ai->alien);
+	INIT_LIST_HEAD(&ai->fastmap);
+	ai->volumes = RB_ROOT;
+	ai->aeb_slab_cache = kmem_cache_create("ubi_aeb_slab_cache",
+					       sizeof(struct ubi_ainf_peb),
+					       0, 0, NULL);
+	if (!ai->aeb_slab_cache) {
+		kfree(ai);
+		ai = NULL;
+	}
+
+	return ai;
+}
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+
+/**
+ * scan_fast - try to find a fastmap and attach from it.
+ * @ubi: UBI device description object
+ * @ai: attach info object
+ *
+ * Returns 0 on success, negative return values indicate an internal
+ * error.
+ * UBI_NO_FASTMAP denotes that no fastmap was found.
+ * UBI_BAD_FASTMAP denotes that the found fastmap was invalid.
+ */
+static int scan_fast(struct ubi_device *ubi, struct ubi_attach_info **ai)
+{
+	int err, pnum;
+	struct ubi_attach_info *scan_ai;
+
+	err = -ENOMEM;
+
+	scan_ai = alloc_ai();
+	if (!scan_ai)
+		goto out;
+
+	scan_ai->ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!scan_ai->ech)
+		goto out_ai;
+
+	scan_ai->vidb = ubi_alloc_vid_buf(ubi, GFP_KERNEL);
+	if (!scan_ai->vidb)
+		goto out_ech;
+
+	for (pnum = 0; pnum < UBI_FM_MAX_START; pnum++) {
+		cond_resched();
+
+		dbg_gen("process PEB %d", pnum);
+		err = scan_peb(ubi, scan_ai, pnum, true);
+		if (err < 0)
+			goto out_vidh;
+	}
+
+	ubi_free_vid_buf(scan_ai->vidb);
+	kfree(scan_ai->ech);
+
+	if (scan_ai->force_full_scan)
+		err = UBI_NO_FASTMAP;
+	else
+		err = ubi_scan_fastmap(ubi, *ai, scan_ai);
+
+	if (err) {
+		/*
+		 * Didn't attach via fastmap, do a full scan but reuse what
+		 * we've aready scanned.
+		 */
+		destroy_ai(*ai);
+		*ai = scan_ai;
+	} else
+		destroy_ai(scan_ai);
+
+	return err;
+
+out_vidh:
+	ubi_free_vid_buf(scan_ai->vidb);
+out_ech:
+	kfree(scan_ai->ech);
+out_ai:
+	destroy_ai(scan_ai);
+out:
+	return err;
+}
+
+#endif
+
+/**
+ * ubi_attach - attach an MTD device.
+ * @ubi: UBI device descriptor
+ * @force_scan: if set to non-zero attach by scanning
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+int ubi_attach(struct ubi_device *ubi, int force_scan)
+{
+	int err;
+	struct ubi_attach_info *ai;
+
+	ai = alloc_ai();
+	if (!ai)
+		return -ENOMEM;
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+	/* On small flash devices we disable fastmap in any case. */
+	if ((int)mtd_div_by_eb(ubi->mtd->size, ubi->mtd) <= UBI_FM_MAX_START) {
+		ubi->fm_disabled = 1;
+		force_scan = 1;
+	}
+
+	if (force_scan)
+		err = scan_all(ubi, ai, 0);
+	else {
+		err = scan_fast(ubi, &ai);
+		if (err > 0 || mtd_is_eccerr(err)) {
+			if (err != UBI_NO_FASTMAP) {
+				destroy_ai(ai);
+				ai = alloc_ai();
+				if (!ai)
+					return -ENOMEM;
+
+				err = scan_all(ubi, ai, 0);
+			} else {
+				err = scan_all(ubi, ai, UBI_FM_MAX_START);
+			}
+		}
+	}
+#else
+	err = scan_all(ubi, ai, 0);
+#endif
+	if (err)
+		goto out_ai;
+
+	ubi->bad_peb_count = ai->bad_peb_count;
+	ubi->good_peb_count = ubi->peb_count - ubi->bad_peb_count;
+	ubi->corr_peb_count = ai->corr_peb_count;
+	ubi->max_ec = ai->max_ec;
+	ubi->mean_ec = ai->mean_ec;
+	dbg_gen("max. sequence number:       %llu", ai->max_sqnum);
+
+	err = ubi_read_volume_table(ubi, ai);
+	if (err)
+		goto out_ai;
+
+	err = ubi_wl_init(ubi, ai);
+	if (err)
+		goto out_vtbl;
+
+	err = ubi_eba_init(ubi, ai);
+	if (err)
+		goto out_wl;
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+	if (ubi->fm && ubi_dbg_chk_fastmap(ubi)) {
+		struct ubi_attach_info *scan_ai;
+
+		scan_ai = alloc_ai();
+		if (!scan_ai) {
+			err = -ENOMEM;
+			goto out_wl;
+		}
+
+		err = scan_all(ubi, scan_ai, 0);
+		if (err) {
+			destroy_ai(scan_ai);
+			goto out_wl;
+		}
+
+		err = self_check_eba(ubi, ai, scan_ai);
+		destroy_ai(scan_ai);
+
+		if (err)
+			goto out_wl;
+	}
+#endif
+
+	destroy_ai(ai);
+	return 0;
+
+out_wl:
+	ubi_wl_close(ubi);
+out_vtbl:
+	ubi_free_all_volumes(ubi);
+	vfree(ubi->vtbl);
+out_ai:
+	destroy_ai(ai);
+	return err;
+}
+
+/**
+ * self_check_ai - check the attaching information.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ *
+ * This function returns zero if the attaching information is all right, and a
+ * negative error code if not or if an error occurred.
+ */
+static int self_check_ai(struct ubi_device *ubi, struct ubi_attach_info *ai)
+{
+	struct ubi_vid_io_buf *vidb = ai->vidb;
+	struct ubi_vid_hdr *vidh = ubi_get_vid_hdr(vidb);
+	int pnum, err, vols_found = 0;
+	struct rb_node *rb1, *rb2;
+	struct ubi_ainf_volume *av;
+	struct ubi_ainf_peb *aeb, *last_aeb;
+	uint8_t *buf;
+
+	if (!ubi_dbg_chk_gen(ubi))
+		return 0;
+
+	/*
+	 * At first, check that attaching information is OK.
+	 */
+	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb) {
+		int leb_count = 0;
+
+		cond_resched();
+
+		vols_found += 1;
+
+		if (ai->is_empty) {
+			ubi_err(ubi, "bad is_empty flag");
+			goto bad_av;
+		}
+
+		if (av->vol_id < 0 || av->highest_lnum < 0 ||
+		    av->leb_count < 0 || av->vol_type < 0 || av->used_ebs < 0 ||
+		    av->data_pad < 0 || av->last_data_size < 0) {
+			ubi_err(ubi, "negative values");
+			goto bad_av;
+		}
+
+		if (av->vol_id >= UBI_MAX_VOLUMES &&
+		    av->vol_id < UBI_INTERNAL_VOL_START) {
+			ubi_err(ubi, "bad vol_id");
+			goto bad_av;
+		}
+
+		if (av->vol_id > ai->highest_vol_id) {
+			ubi_err(ubi, "highest_vol_id is %d, but vol_id %d is there",
+				ai->highest_vol_id, av->vol_id);
+			goto out;
+		}
+
+		if (av->vol_type != UBI_DYNAMIC_VOLUME &&
+		    av->vol_type != UBI_STATIC_VOLUME) {
+			ubi_err(ubi, "bad vol_type");
+			goto bad_av;
+		}
+
+		if (av->data_pad > ubi->leb_size / 2) {
+			ubi_err(ubi, "bad data_pad");
+			goto bad_av;
+		}
+
+		last_aeb = NULL;
+		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb) {
+			cond_resched();
+
+			last_aeb = aeb;
+			leb_count += 1;
+
+			if (aeb->pnum < 0 || aeb->ec < 0) {
+				ubi_err(ubi, "negative values");
+				goto bad_aeb;
+			}
+
+			if (aeb->ec < ai->min_ec) {
+				ubi_err(ubi, "bad ai->min_ec (%d), %d found",
+					ai->min_ec, aeb->ec);
+				goto bad_aeb;
+			}
+
+			if (aeb->ec > ai->max_ec) {
+				ubi_err(ubi, "bad ai->max_ec (%d), %d found",
+					ai->max_ec, aeb->ec);
+				goto bad_aeb;
+			}
+
+			if (aeb->pnum >= ubi->peb_count) {
+				ubi_err(ubi, "too high PEB number %d, total PEBs %d",
+					aeb->pnum, ubi->peb_count);
+				goto bad_aeb;
+			}
+
+			if (av->vol_type == UBI_STATIC_VOLUME) {
+				if (aeb->lnum >= av->used_ebs) {
+					ubi_err(ubi, "bad lnum or used_ebs");
+					goto bad_aeb;
+				}
+			} else {
+				if (av->used_ebs != 0) {
+					ubi_err(ubi, "non-zero used_ebs");
+					goto bad_aeb;
+				}
+			}
+
+			if (aeb->lnum > av->highest_lnum) {
+				ubi_err(ubi, "incorrect highest_lnum or lnum");
+				goto bad_aeb;
+			}
+		}
+
+		if (av->leb_count != leb_count) {
+			ubi_err(ubi, "bad leb_count, %d objects in the tree",
+				leb_count);
+			goto bad_av;
+		}
+
+		if (!last_aeb)
+			continue;
+
+		aeb = last_aeb;
+
+		if (aeb->lnum != av->highest_lnum) {
+			ubi_err(ubi, "bad highest_lnum");
+			goto bad_aeb;
+		}
+	}
+
+	if (vols_found != ai->vols_found) {
+		ubi_err(ubi, "bad ai->vols_found %d, should be %d",
+			ai->vols_found, vols_found);
+		goto out;
+	}
+
+	/* Check that attaching information is correct */
+	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb) {
+		last_aeb = NULL;
+		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb) {
+			int vol_type;
+
+			cond_resched();
+
+			last_aeb = aeb;
+
+			err = ubi_io_read_vid_hdr(ubi, aeb->pnum, vidb, 1);
+			if (err && err != UBI_IO_BITFLIPS) {
+				ubi_err(ubi, "VID header is not OK (%d)",
+					err);
+				if (err > 0)
+					err = -EIO;
+				return err;
+			}
+
+			vol_type = vidh->vol_type == UBI_VID_DYNAMIC ?
+				   UBI_DYNAMIC_VOLUME : UBI_STATIC_VOLUME;
+			if (av->vol_type != vol_type) {
+				ubi_err(ubi, "bad vol_type");
+				goto bad_vid_hdr;
+			}
+
+			if (aeb->sqnum != be64_to_cpu(vidh->sqnum)) {
+				ubi_err(ubi, "bad sqnum %llu", aeb->sqnum);
+				goto bad_vid_hdr;
+			}
+
+			if (av->vol_id != be32_to_cpu(vidh->vol_id)) {
+				ubi_err(ubi, "bad vol_id %d", av->vol_id);
+				goto bad_vid_hdr;
+			}
+
+			if (av->compat != vidh->compat) {
+				ubi_err(ubi, "bad compat %d", vidh->compat);
+				goto bad_vid_hdr;
+			}
+
+			if (aeb->lnum != be32_to_cpu(vidh->lnum)) {
+				ubi_err(ubi, "bad lnum %d", aeb->lnum);
+				goto bad_vid_hdr;
+			}
+
+			if (av->used_ebs != be32_to_cpu(vidh->used_ebs)) {
+				ubi_err(ubi, "bad used_ebs %d", av->used_ebs);
+				goto bad_vid_hdr;
+			}
+
+			if (av->data_pad != be32_to_cpu(vidh->data_pad)) {
+				ubi_err(ubi, "bad data_pad %d", av->data_pad);
+				goto bad_vid_hdr;
+			}
+		}
+
+		if (!last_aeb)
+			continue;
+
+		if (av->highest_lnum != be32_to_cpu(vidh->lnum)) {
+			ubi_err(ubi, "bad highest_lnum %d", av->highest_lnum);
+			goto bad_vid_hdr;
+		}
+
+		if (av->last_data_size != be32_to_cpu(vidh->data_size)) {
+			ubi_err(ubi, "bad last_data_size %d",
+				av->last_data_size);
+			goto bad_vid_hdr;
+		}
+	}
+
+	/*
+	 * Make sure that all the physical eraseblocks are in one of the lists
+	 * or trees.
+	 */
+	buf = kzalloc(ubi->peb_count, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	for (pnum = 0; pnum < ubi->peb_count; pnum++) {
+		err = ubi_io_is_bad(ubi, pnum);
+		if (err < 0) {
+			kfree(buf);
+			return err;
+		} else if (err)
+			buf[pnum] = 1;
+	}
+
+	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb)
+		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb)
+			buf[aeb->pnum] = 1;
+
+	list_for_each_entry(aeb, &ai->free, u.list)
+		buf[aeb->pnum] = 1;
+
+	list_for_each_entry(aeb, &ai->corr, u.list)
+		buf[aeb->pnum] = 1;
+
+	list_for_each_entry(aeb, &ai->erase, u.list)
+		buf[aeb->pnum] = 1;
+
+	list_for_each_entry(aeb, &ai->alien, u.list)
+		buf[aeb->pnum] = 1;
+
+	err = 0;
+	for (pnum = 0; pnum < ubi->peb_count; pnum++)
+		if (!buf[pnum]) {
+			ubi_err(ubi, "PEB %d is not referred", pnum);
+			err = 1;
+		}
+
+	kfree(buf);
+	if (err)
+		goto out;
+	return 0;
+
+bad_aeb:
+	ubi_err(ubi, "bad attaching information about LEB %d", aeb->lnum);
+	ubi_dump_aeb(aeb, 0);
+	ubi_dump_av(av);
+	goto out;
+
+bad_av:
+	ubi_err(ubi, "bad attaching information about volume %d", av->vol_id);
+	ubi_dump_av(av);
+	goto out;
+
+bad_vid_hdr:
+	ubi_err(ubi, "bad attaching information about volume %d", av->vol_id);
+	ubi_dump_av(av);
+	ubi_dump_vid_hdr(vidh);
+
+out:
+	dump_stack();
+	return -EINVAL;
+}
diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
new file mode 100644
index 0000000000..437c5b83ff
--- /dev/null
+++ b/drivers/mtd/ubi/block.c
@@ -0,0 +1,673 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2014 Ezequiel Garcia
+ * Copyright (c) 2011 Free Electrons
+ *
+ * Driver parameter handling strongly based on drivers/mtd/ubi/build.c
+ *   Copyright (c) International Business Machines Corp., 2006
+ *   Copyright (c) Nokia Corporation, 2007
+ *   Authors: Artem Bityutskiy, Frank Haverkamp
+ */
+
+/*
+ * Read-only block devices on top of UBI volumes
+ *
+ * A simple implementation to allow a block device to be layered on top of a
+ * UBI volume. The implementation is provided by creating a static 1-to-1
+ * mapping between the block device and the UBI volume.
+ *
+ * The addressed byte is obtained from the addressed block sector, which is
+ * mapped linearly into the corresponding LEB:
+ *
+ *   LEB number = addressed byte / LEB size
+ *
+ * This feature is compiled in the UBI core, and adds a 'block' parameter
+ * to allow early creation of block devices on top of UBI volumes. Runtime
+ * block creation/removal for UBI volumes is provided through two UBI ioctls:
+ * UBI_IOCVOLCRBLK and UBI_IOCVOLRMBLK.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/mtd/ubi.h>
+#include <linux/blkdev.h>
+#include <linux/blk-mq.h>
+#include <linux/hdreg.h>
+#include <linux/scatterlist.h>
+#include <linux/idr.h>
+#include <asm/div64.h>
+
+#include "ubi-media.h"
+#include "ubi.h"
+
+/* Maximum number of supported devices */
+#define UBIBLOCK_MAX_DEVICES 32
+
+/* Maximum length of the 'block=' parameter */
+#define UBIBLOCK_PARAM_LEN 63
+
+/* Maximum number of comma-separated items in the 'block=' parameter */
+#define UBIBLOCK_PARAM_COUNT 2
+
+struct ubiblock_param {
+	int ubi_num;
+	int vol_id;
+	char name[UBIBLOCK_PARAM_LEN+1];
+};
+
+struct ubiblock_pdu {
+	struct ubi_sgl usgl;
+};
+
+/* Numbers of elements set in the @ubiblock_param array */
+static int ubiblock_devs __initdata;
+
+/* MTD devices specification parameters */
+static struct ubiblock_param ubiblock_param[UBIBLOCK_MAX_DEVICES] __initdata;
+
+struct ubiblock {
+	struct ubi_volume_desc *desc;
+	int ubi_num;
+	int vol_id;
+	int refcnt;
+	int leb_size;
+
+	struct gendisk *gd;
+	struct request_queue *rq;
+
+	struct mutex dev_mutex;
+	struct list_head list;
+	struct blk_mq_tag_set tag_set;
+};
+
+/* Linked list of all ubiblock instances */
+static LIST_HEAD(ubiblock_devices);
+static DEFINE_IDR(ubiblock_minor_idr);
+/* Protects ubiblock_devices and ubiblock_minor_idr */
+static DEFINE_MUTEX(devices_mutex);
+static int ubiblock_major;
+
+static int __init ubiblock_set_param(const char *val,
+				     const struct kernel_param *kp)
+{
+	int i, ret;
+	size_t len;
+	struct ubiblock_param *param;
+	char buf[UBIBLOCK_PARAM_LEN];
+	char *pbuf = &buf[0];
+	char *tokens[UBIBLOCK_PARAM_COUNT];
+
+	if (!val)
+		return -EINVAL;
+
+	len = strnlen(val, UBIBLOCK_PARAM_LEN);
+	if (len == 0) {
+		pr_warn("UBI: block: empty 'block=' parameter - ignored\n");
+		return 0;
+	}
+
+	if (len == UBIBLOCK_PARAM_LEN) {
+		pr_err("UBI: block: parameter \"%s\" is too long, max. is %d\n",
+		       val, UBIBLOCK_PARAM_LEN);
+		return -EINVAL;
+	}
+
+	strcpy(buf, val);
+
+	/* Get rid of the final newline */
+	if (buf[len - 1] == '\n')
+		buf[len - 1] = '\0';
+
+	for (i = 0; i < UBIBLOCK_PARAM_COUNT; i++)
+		tokens[i] = strsep(&pbuf, ",");
+
+	param = &ubiblock_param[ubiblock_devs];
+	if (tokens[1]) {
+		/* Two parameters: can be 'ubi, vol_id' or 'ubi, vol_name' */
+		ret = kstrtoint(tokens[0], 10, &param->ubi_num);
+		if (ret < 0)
+			return -EINVAL;
+
+		/* Second param can be a number or a name */
+		ret = kstrtoint(tokens[1], 10, &param->vol_id);
+		if (ret < 0) {
+			param->vol_id = -1;
+			strcpy(param->name, tokens[1]);
+		}
+
+	} else {
+		/* One parameter: must be device path */
+		strcpy(param->name, tokens[0]);
+		param->ubi_num = -1;
+		param->vol_id = -1;
+	}
+
+	ubiblock_devs++;
+
+	return 0;
+}
+
+static const struct kernel_param_ops ubiblock_param_ops = {
+	.set    = ubiblock_set_param,
+};
+module_param_cb(block, &ubiblock_param_ops, NULL, 0);
+MODULE_PARM_DESC(block, "Attach block devices to UBI volumes. Parameter format: block=<path|dev,num|dev,name>.\n"
+			"Multiple \"block\" parameters may be specified.\n"
+			"UBI volumes may be specified by their number, name, or path to the device node.\n"
+			"Examples\n"
+			"Using the UBI volume path:\n"
+			"ubi.block=/dev/ubi0_0\n"
+			"Using the UBI device, and the volume name:\n"
+			"ubi.block=0,rootfs\n"
+			"Using both UBI device number and UBI volume number:\n"
+			"ubi.block=0,0\n");
+
+static struct ubiblock *find_dev_nolock(int ubi_num, int vol_id)
+{
+	struct ubiblock *dev;
+
+	list_for_each_entry(dev, &ubiblock_devices, list)
+		if (dev->ubi_num == ubi_num && dev->vol_id == vol_id)
+			return dev;
+	return NULL;
+}
+
+static blk_status_t ubiblock_read(struct request *req)
+{
+	struct ubiblock_pdu *pdu = blk_mq_rq_to_pdu(req);
+	struct ubiblock *dev = req->q->queuedata;
+	u64 pos = blk_rq_pos(req) << 9;
+	int to_read = blk_rq_bytes(req);
+	int bytes_left = to_read;
+	/* Get LEB:offset address to read from */
+	int offset = do_div(pos, dev->leb_size);
+	int leb = pos;
+	struct req_iterator iter;
+	struct bio_vec bvec;
+	int ret;
+
+	blk_mq_start_request(req);
+
+	/*
+	 * It is safe to ignore the return value of blk_rq_map_sg() because
+	 * the number of sg entries is limited to UBI_MAX_SG_COUNT
+	 * and ubi_read_sg() will check that limit.
+	 */
+	ubi_sgl_init(&pdu->usgl);
+	blk_rq_map_sg(req->q, req, pdu->usgl.sg);
+
+	while (bytes_left) {
+		/*
+		 * We can only read one LEB at a time. Therefore if the read
+		 * length is larger than one LEB size, we split the operation.
+		 */
+		if (offset + to_read > dev->leb_size)
+			to_read = dev->leb_size - offset;
+
+		ret = ubi_read_sg(dev->desc, leb, &pdu->usgl, offset, to_read);
+		if (ret < 0)
+			break;
+
+		bytes_left -= to_read;
+		to_read = bytes_left;
+		leb += 1;
+		offset = 0;
+	}
+
+	rq_for_each_segment(bvec, req, iter)
+		flush_dcache_page(bvec.bv_page);
+
+	blk_mq_end_request(req, errno_to_blk_status(ret));
+
+	return BLK_STS_OK;
+}
+
+static int ubiblock_open(struct gendisk *disk, blk_mode_t mode)
+{
+	struct ubiblock *dev = disk->private_data;
+	int ret;
+
+	mutex_lock(&dev->dev_mutex);
+	if (dev->refcnt > 0) {
+		/*
+		 * The volume is already open, just increase the reference
+		 * counter.
+		 */
+		goto out_done;
+	}
+
+	/*
+	 * We want users to be aware they should only mount us as read-only.
+	 * It's just a paranoid check, as write requests will get rejected
+	 * in any case.
+	 */
+	if (mode & BLK_OPEN_WRITE) {
+		ret = -EROFS;
+		goto out_unlock;
+	}
+	dev->desc = ubi_open_volume(dev->ubi_num, dev->vol_id, UBI_READONLY);
+	if (IS_ERR(dev->desc)) {
+		dev_err(disk_to_dev(dev->gd), "failed to open ubi volume %d_%d",
+			dev->ubi_num, dev->vol_id);
+		ret = PTR_ERR(dev->desc);
+		dev->desc = NULL;
+		goto out_unlock;
+	}
+
+out_done:
+	dev->refcnt++;
+	mutex_unlock(&dev->dev_mutex);
+	return 0;
+
+out_unlock:
+	mutex_unlock(&dev->dev_mutex);
+	return ret;
+}
+
+static void ubiblock_release(struct gendisk *gd)
+{
+	struct ubiblock *dev = gd->private_data;
+
+	mutex_lock(&dev->dev_mutex);
+	dev->refcnt--;
+	if (dev->refcnt == 0) {
+		ubi_close_volume(dev->desc);
+		dev->desc = NULL;
+	}
+	mutex_unlock(&dev->dev_mutex);
+}
+
+static int ubiblock_getgeo(struct block_device *bdev, struct hd_geometry *geo)
+{
+	/* Some tools might require this information */
+	geo->heads = 1;
+	geo->cylinders = 1;
+	geo->sectors = get_capacity(bdev->bd_disk);
+	geo->start = 0;
+	return 0;
+}
+
+static const struct block_device_operations ubiblock_ops = {
+	.owner = THIS_MODULE,
+	.open = ubiblock_open,
+	.release = ubiblock_release,
+	.getgeo	= ubiblock_getgeo,
+};
+
+static blk_status_t ubiblock_queue_rq(struct blk_mq_hw_ctx *hctx,
+			     const struct blk_mq_queue_data *bd)
+{
+	switch (req_op(bd->rq)) {
+	case REQ_OP_READ:
+		return ubiblock_read(bd->rq);
+	default:
+		return BLK_STS_IOERR;
+	}
+}
+
+static int ubiblock_init_request(struct blk_mq_tag_set *set,
+		struct request *req, unsigned int hctx_idx,
+		unsigned int numa_node)
+{
+	struct ubiblock_pdu *pdu = blk_mq_rq_to_pdu(req);
+
+	sg_init_table(pdu->usgl.sg, UBI_MAX_SG_COUNT);
+	return 0;
+}
+
+static const struct blk_mq_ops ubiblock_mq_ops = {
+	.queue_rq       = ubiblock_queue_rq,
+	.init_request	= ubiblock_init_request,
+};
+
+static int calc_disk_capacity(struct ubi_volume_info *vi, u64 *disk_capacity)
+{
+	u64 size = vi->used_bytes >> 9;
+
+	if (vi->used_bytes % 512) {
+		if (vi->vol_type == UBI_DYNAMIC_VOLUME)
+			pr_warn("UBI: block: volume size is not a multiple of 512, last %llu bytes are ignored!\n",
+				vi->used_bytes - (size << 9));
+		else
+			pr_info("UBI: block: volume size is not a multiple of 512, last %llu bytes are ignored!\n",
+				vi->used_bytes - (size << 9));
+	}
+
+	if ((sector_t)size != size)
+		return -EFBIG;
+
+	*disk_capacity = size;
+
+	return 0;
+}
+
+int ubiblock_create(struct ubi_volume_info *vi)
+{
+	struct ubiblock *dev;
+	struct gendisk *gd;
+	u64 disk_capacity;
+	int ret;
+
+	ret = calc_disk_capacity(vi, &disk_capacity);
+	if (ret) {
+		return ret;
+	}
+
+	/* Check that the volume isn't already handled */
+	mutex_lock(&devices_mutex);
+	if (find_dev_nolock(vi->ubi_num, vi->vol_id)) {
+		ret = -EEXIST;
+		goto out_unlock;
+	}
+
+	dev = kzalloc(sizeof(struct ubiblock), GFP_KERNEL);
+	if (!dev) {
+		ret = -ENOMEM;
+		goto out_unlock;
+	}
+
+	mutex_init(&dev->dev_mutex);
+
+	dev->ubi_num = vi->ubi_num;
+	dev->vol_id = vi->vol_id;
+	dev->leb_size = vi->usable_leb_size;
+
+	dev->tag_set.ops = &ubiblock_mq_ops;
+	dev->tag_set.queue_depth = 64;
+	dev->tag_set.numa_node = NUMA_NO_NODE;
+	dev->tag_set.flags = BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_BLOCKING;
+	dev->tag_set.cmd_size = sizeof(struct ubiblock_pdu);
+	dev->tag_set.driver_data = dev;
+	dev->tag_set.nr_hw_queues = 1;
+
+	ret = blk_mq_alloc_tag_set(&dev->tag_set);
+	if (ret) {
+		dev_err(disk_to_dev(dev->gd), "blk_mq_alloc_tag_set failed");
+		goto out_free_dev;
+	}
+
+
+	/* Initialize the gendisk of this ubiblock device */
+	gd = blk_mq_alloc_disk(&dev->tag_set, dev);
+	if (IS_ERR(gd)) {
+		ret = PTR_ERR(gd);
+		goto out_free_tags;
+	}
+
+	gd->fops = &ubiblock_ops;
+	gd->major = ubiblock_major;
+	gd->minors = 1;
+	gd->first_minor = idr_alloc(&ubiblock_minor_idr, dev, 0, 0, GFP_KERNEL);
+	if (gd->first_minor < 0) {
+		dev_err(disk_to_dev(gd),
+			"block: dynamic minor allocation failed");
+		ret = -ENODEV;
+		goto out_cleanup_disk;
+	}
+	gd->flags |= GENHD_FL_NO_PART;
+	gd->private_data = dev;
+	sprintf(gd->disk_name, "ubiblock%d_%d", dev->ubi_num, dev->vol_id);
+	set_capacity(gd, disk_capacity);
+	dev->gd = gd;
+
+	dev->rq = gd->queue;
+	blk_queue_max_segments(dev->rq, UBI_MAX_SG_COUNT);
+
+	list_add_tail(&dev->list, &ubiblock_devices);
+
+	/* Must be the last step: anyone can call file ops from now on */
+	ret = device_add_disk(vi->dev, dev->gd, NULL);
+	if (ret)
+		goto out_remove_minor;
+
+	dev_info(disk_to_dev(dev->gd), "created from ubi%d:%d(%s)",
+		 dev->ubi_num, dev->vol_id, vi->name);
+	mutex_unlock(&devices_mutex);
+	return 0;
+
+out_remove_minor:
+	list_del(&dev->list);
+	idr_remove(&ubiblock_minor_idr, gd->first_minor);
+out_cleanup_disk:
+	put_disk(dev->gd);
+out_free_tags:
+	blk_mq_free_tag_set(&dev->tag_set);
+out_free_dev:
+	kfree(dev);
+out_unlock:
+	mutex_unlock(&devices_mutex);
+
+	return ret;
+}
+
+static void ubiblock_cleanup(struct ubiblock *dev)
+{
+	/* Stop new requests to arrive */
+	del_gendisk(dev->gd);
+	/* Finally destroy the blk queue */
+	dev_info(disk_to_dev(dev->gd), "released");
+	put_disk(dev->gd);
+	blk_mq_free_tag_set(&dev->tag_set);
+	idr_remove(&ubiblock_minor_idr, dev->gd->first_minor);
+}
+
+int ubiblock_remove(struct ubi_volume_info *vi)
+{
+	struct ubiblock *dev;
+	int ret;
+
+	mutex_lock(&devices_mutex);
+	dev = find_dev_nolock(vi->ubi_num, vi->vol_id);
+	if (!dev) {
+		ret = -ENODEV;
+		goto out_unlock;
+	}
+
+	/* Found a device, let's lock it so we can check if it's busy */
+	mutex_lock(&dev->dev_mutex);
+	if (dev->refcnt > 0) {
+		ret = -EBUSY;
+		goto out_unlock_dev;
+	}
+
+	/* Remove from device list */
+	list_del(&dev->list);
+	ubiblock_cleanup(dev);
+	mutex_unlock(&dev->dev_mutex);
+	mutex_unlock(&devices_mutex);
+
+	kfree(dev);
+	return 0;
+
+out_unlock_dev:
+	mutex_unlock(&dev->dev_mutex);
+out_unlock:
+	mutex_unlock(&devices_mutex);
+	return ret;
+}
+
+static int ubiblock_resize(struct ubi_volume_info *vi)
+{
+	struct ubiblock *dev;
+	u64 disk_capacity;
+	int ret;
+
+	/*
+	 * Need to lock the device list until we stop using the device,
+	 * otherwise the device struct might get released in
+	 * 'ubiblock_remove()'.
+	 */
+	mutex_lock(&devices_mutex);
+	dev = find_dev_nolock(vi->ubi_num, vi->vol_id);
+	if (!dev) {
+		mutex_unlock(&devices_mutex);
+		return -ENODEV;
+	}
+
+	ret = calc_disk_capacity(vi, &disk_capacity);
+	if (ret) {
+		mutex_unlock(&devices_mutex);
+		if (ret == -EFBIG) {
+			dev_warn(disk_to_dev(dev->gd),
+				 "the volume is too big (%d LEBs), cannot resize",
+				 vi->size);
+		}
+		return ret;
+	}
+
+	mutex_lock(&dev->dev_mutex);
+
+	if (get_capacity(dev->gd) != disk_capacity) {
+		set_capacity(dev->gd, disk_capacity);
+		dev_info(disk_to_dev(dev->gd), "resized to %lld bytes",
+			 vi->used_bytes);
+	}
+	mutex_unlock(&dev->dev_mutex);
+	mutex_unlock(&devices_mutex);
+	return 0;
+}
+
+static int ubiblock_notify(struct notifier_block *nb,
+			 unsigned long notification_type, void *ns_ptr)
+{
+	struct ubi_notification *nt = ns_ptr;
+
+	switch (notification_type) {
+	case UBI_VOLUME_ADDED:
+		/*
+		 * We want to enforce explicit block device creation for
+		 * volumes, so when a volume is added we do nothing.
+		 */
+		break;
+	case UBI_VOLUME_REMOVED:
+		ubiblock_remove(&nt->vi);
+		break;
+	case UBI_VOLUME_RESIZED:
+		ubiblock_resize(&nt->vi);
+		break;
+	case UBI_VOLUME_UPDATED:
+		/*
+		 * If the volume is static, a content update might mean the
+		 * size (i.e. used_bytes) was also changed.
+		 */
+		if (nt->vi.vol_type == UBI_STATIC_VOLUME)
+			ubiblock_resize(&nt->vi);
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block ubiblock_notifier = {
+	.notifier_call = ubiblock_notify,
+};
+
+static struct ubi_volume_desc * __init
+open_volume_desc(const char *name, int ubi_num, int vol_id)
+{
+	if (ubi_num == -1)
+		/* No ubi num, name must be a vol device path */
+		return ubi_open_volume_path(name, UBI_READONLY);
+	else if (vol_id == -1)
+		/* No vol_id, must be vol_name */
+		return ubi_open_volume_nm(ubi_num, name, UBI_READONLY);
+	else
+		return ubi_open_volume(ubi_num, vol_id, UBI_READONLY);
+}
+
+static void __init ubiblock_create_from_param(void)
+{
+	int i, ret = 0;
+	struct ubiblock_param *p;
+	struct ubi_volume_desc *desc;
+	struct ubi_volume_info vi;
+
+	/*
+	 * If there is an error creating one of the ubiblocks, continue on to
+	 * create the following ubiblocks. This helps in a circumstance where
+	 * the kernel command-line specifies multiple block devices and some
+	 * may be broken, but we still want the working ones to come up.
+	 */
+	for (i = 0; i < ubiblock_devs; i++) {
+		p = &ubiblock_param[i];
+
+		desc = open_volume_desc(p->name, p->ubi_num, p->vol_id);
+		if (IS_ERR(desc)) {
+			pr_err(
+			       "UBI: block: can't open volume on ubi%d_%d, err=%ld\n",
+			       p->ubi_num, p->vol_id, PTR_ERR(desc));
+			continue;
+		}
+
+		ubi_get_volume_info(desc, &vi);
+		ubi_close_volume(desc);
+
+		ret = ubiblock_create(&vi);
+		if (ret) {
+			pr_err(
+			       "UBI: block: can't add '%s' volume on ubi%d_%d, err=%d\n",
+			       vi.name, p->ubi_num, p->vol_id, ret);
+			continue;
+		}
+	}
+}
+
+static void ubiblock_remove_all(void)
+{
+	struct ubiblock *next;
+	struct ubiblock *dev;
+
+	mutex_lock(&devices_mutex);
+	list_for_each_entry_safe(dev, next, &ubiblock_devices, list) {
+		/* The module is being forcefully removed */
+		WARN_ON(dev->desc);
+		/* Remove from device list */
+		list_del(&dev->list);
+		ubiblock_cleanup(dev);
+		kfree(dev);
+	}
+	mutex_unlock(&devices_mutex);
+}
+
+int __init ubiblock_init(void)
+{
+	int ret;
+
+	ubiblock_major = register_blkdev(0, "ubiblock");
+	if (ubiblock_major < 0)
+		return ubiblock_major;
+
+	/*
+	 * Attach block devices from 'block=' module param.
+	 * Even if one block device in the param list fails to come up,
+	 * still allow the module to load and leave any others up.
+	 */
+	ubiblock_create_from_param();
+
+	/*
+	 * Block devices are only created upon user requests, so we ignore
+	 * existing volumes.
+	 */
+	ret = ubi_register_volume_notifier(&ubiblock_notifier, 1);
+	if (ret)
+		goto err_unreg;
+	return 0;
+
+err_unreg:
+	unregister_blkdev(ubiblock_major, "ubiblock");
+	ubiblock_remove_all();
+	return ret;
+}
+
+void __exit ubiblock_exit(void)
+{
+	ubi_unregister_volume_notifier(&ubiblock_notifier);
+	ubiblock_remove_all();
+	unregister_blkdev(ubiblock_major, "ubiblock");
+}
diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
new file mode 100644
index 0000000000..8ee51e49fc
--- /dev/null
+++ b/drivers/mtd/ubi/build.c
@@ -0,0 +1,1514 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ * Copyright (c) Nokia Corporation, 2007
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём),
+ *         Frank Haverkamp
+ */
+
+/*
+ * This file includes UBI initialization and building of UBI devices.
+ *
+ * When UBI is initialized, it attaches all the MTD devices specified as the
+ * module load parameters or the kernel boot parameters. If MTD devices were
+ * specified, UBI does not attach any MTD device, but it is possible to do
+ * later using the "UBI control device".
+ */
+
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/stringify.h>
+#include <linux/namei.h>
+#include <linux/stat.h>
+#include <linux/miscdevice.h>
+#include <linux/mtd/partitions.h>
+#include <linux/log2.h>
+#include <linux/kthread.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/major.h>
+#include "ubi.h"
+
+/* Maximum length of the 'mtd=' parameter */
+#define MTD_PARAM_LEN_MAX 64
+
+/* Maximum number of comma-separated items in the 'mtd=' parameter */
+#define MTD_PARAM_MAX_COUNT 5
+
+/* Maximum value for the number of bad PEBs per 1024 PEBs */
+#define MAX_MTD_UBI_BEB_LIMIT 768
+
+#ifdef CONFIG_MTD_UBI_MODULE
+#define ubi_is_module() 1
+#else
+#define ubi_is_module() 0
+#endif
+
+/**
+ * struct mtd_dev_param - MTD device parameter description data structure.
+ * @name: MTD character device node path, MTD device name, or MTD device number
+ *        string
+ * @ubi_num: UBI number
+ * @vid_hdr_offs: VID header offset
+ * @max_beb_per1024: maximum expected number of bad PEBs per 1024 PEBs
+ * @enable_fm: enable fastmap when value is non-zero
+ */
+struct mtd_dev_param {
+	char name[MTD_PARAM_LEN_MAX];
+	int ubi_num;
+	int vid_hdr_offs;
+	int max_beb_per1024;
+	int enable_fm;
+};
+
+/* Numbers of elements set in the @mtd_dev_param array */
+static int mtd_devs;
+
+/* MTD devices specification parameters */
+static struct mtd_dev_param mtd_dev_param[UBI_MAX_DEVICES];
+#ifdef CONFIG_MTD_UBI_FASTMAP
+/* UBI module parameter to enable fastmap automatically on non-fastmap images */
+static bool fm_autoconvert;
+static bool fm_debug;
+#endif
+
+/* Slab cache for wear-leveling entries */
+struct kmem_cache *ubi_wl_entry_slab;
+
+/* UBI control character device */
+static struct miscdevice ubi_ctrl_cdev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "ubi_ctrl",
+	.fops = &ubi_ctrl_cdev_operations,
+};
+
+/* All UBI devices in system */
+static struct ubi_device *ubi_devices[UBI_MAX_DEVICES];
+
+/* Serializes UBI devices creations and removals */
+DEFINE_MUTEX(ubi_devices_mutex);
+
+/* Protects @ubi_devices and @ubi->ref_count */
+static DEFINE_SPINLOCK(ubi_devices_lock);
+
+/* "Show" method for files in '/<sysfs>/class/ubi/' */
+/* UBI version attribute ('/<sysfs>/class/ubi/version') */
+static ssize_t version_show(const struct class *class, const struct class_attribute *attr,
+			    char *buf)
+{
+	return sprintf(buf, "%d\n", UBI_VERSION);
+}
+static CLASS_ATTR_RO(version);
+
+static struct attribute *ubi_class_attrs[] = {
+	&class_attr_version.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(ubi_class);
+
+/* Root UBI "class" object (corresponds to '/<sysfs>/class/ubi/') */
+struct class ubi_class = {
+	.name		= UBI_NAME_STR,
+	.class_groups	= ubi_class_groups,
+};
+
+static ssize_t dev_attribute_show(struct device *dev,
+				  struct device_attribute *attr, char *buf);
+
+/* UBI device attributes (correspond to files in '/<sysfs>/class/ubi/ubiX') */
+static struct device_attribute dev_eraseblock_size =
+	__ATTR(eraseblock_size, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_avail_eraseblocks =
+	__ATTR(avail_eraseblocks, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_total_eraseblocks =
+	__ATTR(total_eraseblocks, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_volumes_count =
+	__ATTR(volumes_count, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_max_ec =
+	__ATTR(max_ec, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_reserved_for_bad =
+	__ATTR(reserved_for_bad, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_bad_peb_count =
+	__ATTR(bad_peb_count, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_max_vol_count =
+	__ATTR(max_vol_count, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_min_io_size =
+	__ATTR(min_io_size, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_bgt_enabled =
+	__ATTR(bgt_enabled, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_mtd_num =
+	__ATTR(mtd_num, S_IRUGO, dev_attribute_show, NULL);
+static struct device_attribute dev_ro_mode =
+	__ATTR(ro_mode, S_IRUGO, dev_attribute_show, NULL);
+
+/**
+ * ubi_volume_notify - send a volume change notification.
+ * @ubi: UBI device description object
+ * @vol: volume description object of the changed volume
+ * @ntype: notification type to send (%UBI_VOLUME_ADDED, etc)
+ *
+ * This is a helper function which notifies all subscribers about a volume
+ * change event (creation, removal, re-sizing, re-naming, updating). Returns
+ * zero in case of success and a negative error code in case of failure.
+ */
+int ubi_volume_notify(struct ubi_device *ubi, struct ubi_volume *vol, int ntype)
+{
+	int ret;
+	struct ubi_notification nt;
+
+	ubi_do_get_device_info(ubi, &nt.di);
+	ubi_do_get_volume_info(ubi, vol, &nt.vi);
+
+	switch (ntype) {
+	case UBI_VOLUME_ADDED:
+	case UBI_VOLUME_REMOVED:
+	case UBI_VOLUME_RESIZED:
+	case UBI_VOLUME_RENAMED:
+		ret = ubi_update_fastmap(ubi);
+		if (ret)
+			ubi_msg(ubi, "Unable to write a new fastmap: %i", ret);
+	}
+
+	return blocking_notifier_call_chain(&ubi_notifiers, ntype, &nt);
+}
+
+/**
+ * ubi_notify_all - send a notification to all volumes.
+ * @ubi: UBI device description object
+ * @ntype: notification type to send (%UBI_VOLUME_ADDED, etc)
+ * @nb: the notifier to call
+ *
+ * This function walks all volumes of UBI device @ubi and sends the @ntype
+ * notification for each volume. If @nb is %NULL, then all registered notifiers
+ * are called, otherwise only the @nb notifier is called. Returns the number of
+ * sent notifications.
+ */
+int ubi_notify_all(struct ubi_device *ubi, int ntype, struct notifier_block *nb)
+{
+	struct ubi_notification nt;
+	int i, count = 0;
+
+	ubi_do_get_device_info(ubi, &nt.di);
+
+	mutex_lock(&ubi->device_mutex);
+	for (i = 0; i < ubi->vtbl_slots; i++) {
+		/*
+		 * Since the @ubi->device is locked, and we are not going to
+		 * change @ubi->volumes, we do not have to lock
+		 * @ubi->volumes_lock.
+		 */
+		if (!ubi->volumes[i])
+			continue;
+
+		ubi_do_get_volume_info(ubi, ubi->volumes[i], &nt.vi);
+		if (nb)
+			nb->notifier_call(nb, ntype, &nt);
+		else
+			blocking_notifier_call_chain(&ubi_notifiers, ntype,
+						     &nt);
+		count += 1;
+	}
+	mutex_unlock(&ubi->device_mutex);
+
+	return count;
+}
+
+/**
+ * ubi_enumerate_volumes - send "add" notification for all existing volumes.
+ * @nb: the notifier to call
+ *
+ * This function walks all UBI devices and volumes and sends the
+ * %UBI_VOLUME_ADDED notification for each volume. If @nb is %NULL, then all
+ * registered notifiers are called, otherwise only the @nb notifier is called.
+ * Returns the number of sent notifications.
+ */
+int ubi_enumerate_volumes(struct notifier_block *nb)
+{
+	int i, count = 0;
+
+	/*
+	 * Since the @ubi_devices_mutex is locked, and we are not going to
+	 * change @ubi_devices, we do not have to lock @ubi_devices_lock.
+	 */
+	for (i = 0; i < UBI_MAX_DEVICES; i++) {
+		struct ubi_device *ubi = ubi_devices[i];
+
+		if (!ubi)
+			continue;
+		count += ubi_notify_all(ubi, UBI_VOLUME_ADDED, nb);
+	}
+
+	return count;
+}
+
+/**
+ * ubi_get_device - get UBI device.
+ * @ubi_num: UBI device number
+ *
+ * This function returns UBI device description object for UBI device number
+ * @ubi_num, or %NULL if the device does not exist. This function increases the
+ * device reference count to prevent removal of the device. In other words, the
+ * device cannot be removed if its reference count is not zero.
+ */
+struct ubi_device *ubi_get_device(int ubi_num)
+{
+	struct ubi_device *ubi;
+
+	spin_lock(&ubi_devices_lock);
+	ubi = ubi_devices[ubi_num];
+	if (ubi) {
+		ubi_assert(ubi->ref_count >= 0);
+		ubi->ref_count += 1;
+		get_device(&ubi->dev);
+	}
+	spin_unlock(&ubi_devices_lock);
+
+	return ubi;
+}
+
+/**
+ * ubi_put_device - drop an UBI device reference.
+ * @ubi: UBI device description object
+ */
+void ubi_put_device(struct ubi_device *ubi)
+{
+	spin_lock(&ubi_devices_lock);
+	ubi->ref_count -= 1;
+	put_device(&ubi->dev);
+	spin_unlock(&ubi_devices_lock);
+}
+
+/**
+ * ubi_get_by_major - get UBI device by character device major number.
+ * @major: major number
+ *
+ * This function is similar to 'ubi_get_device()', but it searches the device
+ * by its major number.
+ */
+struct ubi_device *ubi_get_by_major(int major)
+{
+	int i;
+	struct ubi_device *ubi;
+
+	spin_lock(&ubi_devices_lock);
+	for (i = 0; i < UBI_MAX_DEVICES; i++) {
+		ubi = ubi_devices[i];
+		if (ubi && MAJOR(ubi->cdev.dev) == major) {
+			ubi_assert(ubi->ref_count >= 0);
+			ubi->ref_count += 1;
+			get_device(&ubi->dev);
+			spin_unlock(&ubi_devices_lock);
+			return ubi;
+		}
+	}
+	spin_unlock(&ubi_devices_lock);
+
+	return NULL;
+}
+
+/**
+ * ubi_major2num - get UBI device number by character device major number.
+ * @major: major number
+ *
+ * This function searches UBI device number object by its major number. If UBI
+ * device was not found, this function returns -ENODEV, otherwise the UBI device
+ * number is returned.
+ */
+int ubi_major2num(int major)
+{
+	int i, ubi_num = -ENODEV;
+
+	spin_lock(&ubi_devices_lock);
+	for (i = 0; i < UBI_MAX_DEVICES; i++) {
+		struct ubi_device *ubi = ubi_devices[i];
+
+		if (ubi && MAJOR(ubi->cdev.dev) == major) {
+			ubi_num = ubi->ubi_num;
+			break;
+		}
+	}
+	spin_unlock(&ubi_devices_lock);
+
+	return ubi_num;
+}
+
+/* "Show" method for files in '/<sysfs>/class/ubi/ubiX/' */
+static ssize_t dev_attribute_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	ssize_t ret;
+	struct ubi_device *ubi;
+
+	/*
+	 * The below code looks weird, but it actually makes sense. We get the
+	 * UBI device reference from the contained 'struct ubi_device'. But it
+	 * is unclear if the device was removed or not yet. Indeed, if the
+	 * device was removed before we increased its reference count,
+	 * 'ubi_get_device()' will return -ENODEV and we fail.
+	 *
+	 * Remember, 'struct ubi_device' is freed in the release function, so
+	 * we still can use 'ubi->ubi_num'.
+	 */
+	ubi = container_of(dev, struct ubi_device, dev);
+
+	if (attr == &dev_eraseblock_size)
+		ret = sprintf(buf, "%d\n", ubi->leb_size);
+	else if (attr == &dev_avail_eraseblocks)
+		ret = sprintf(buf, "%d\n", ubi->avail_pebs);
+	else if (attr == &dev_total_eraseblocks)
+		ret = sprintf(buf, "%d\n", ubi->good_peb_count);
+	else if (attr == &dev_volumes_count)
+		ret = sprintf(buf, "%d\n", ubi->vol_count - UBI_INT_VOL_COUNT);
+	else if (attr == &dev_max_ec)
+		ret = sprintf(buf, "%d\n", ubi->max_ec);
+	else if (attr == &dev_reserved_for_bad)
+		ret = sprintf(buf, "%d\n", ubi->beb_rsvd_pebs);
+	else if (attr == &dev_bad_peb_count)
+		ret = sprintf(buf, "%d\n", ubi->bad_peb_count);
+	else if (attr == &dev_max_vol_count)
+		ret = sprintf(buf, "%d\n", ubi->vtbl_slots);
+	else if (attr == &dev_min_io_size)
+		ret = sprintf(buf, "%d\n", ubi->min_io_size);
+	else if (attr == &dev_bgt_enabled)
+		ret = sprintf(buf, "%d\n", ubi->thread_enabled);
+	else if (attr == &dev_mtd_num)
+		ret = sprintf(buf, "%d\n", ubi->mtd->index);
+	else if (attr == &dev_ro_mode)
+		ret = sprintf(buf, "%d\n", ubi->ro_mode);
+	else
+		ret = -EINVAL;
+
+	return ret;
+}
+
+static struct attribute *ubi_dev_attrs[] = {
+	&dev_eraseblock_size.attr,
+	&dev_avail_eraseblocks.attr,
+	&dev_total_eraseblocks.attr,
+	&dev_volumes_count.attr,
+	&dev_max_ec.attr,
+	&dev_reserved_for_bad.attr,
+	&dev_bad_peb_count.attr,
+	&dev_max_vol_count.attr,
+	&dev_min_io_size.attr,
+	&dev_bgt_enabled.attr,
+	&dev_mtd_num.attr,
+	&dev_ro_mode.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(ubi_dev);
+
+static void dev_release(struct device *dev)
+{
+	struct ubi_device *ubi = container_of(dev, struct ubi_device, dev);
+
+	kfree(ubi);
+}
+
+/**
+ * kill_volumes - destroy all user volumes.
+ * @ubi: UBI device description object
+ */
+static void kill_volumes(struct ubi_device *ubi)
+{
+	int i;
+
+	for (i = 0; i < ubi->vtbl_slots; i++)
+		if (ubi->volumes[i])
+			ubi_free_volume(ubi, ubi->volumes[i]);
+}
+
+/**
+ * uif_init - initialize user interfaces for an UBI device.
+ * @ubi: UBI device description object
+ *
+ * This function initializes various user interfaces for an UBI device. If the
+ * initialization fails at an early stage, this function frees all the
+ * resources it allocated, returns an error.
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int uif_init(struct ubi_device *ubi)
+{
+	int i, err;
+	dev_t dev;
+
+	sprintf(ubi->ubi_name, UBI_NAME_STR "%d", ubi->ubi_num);
+
+	/*
+	 * Major numbers for the UBI character devices are allocated
+	 * dynamically. Major numbers of volume character devices are
+	 * equivalent to ones of the corresponding UBI character device. Minor
+	 * numbers of UBI character devices are 0, while minor numbers of
+	 * volume character devices start from 1. Thus, we allocate one major
+	 * number and ubi->vtbl_slots + 1 minor numbers.
+	 */
+	err = alloc_chrdev_region(&dev, 0, ubi->vtbl_slots + 1, ubi->ubi_name);
+	if (err) {
+		ubi_err(ubi, "cannot register UBI character devices");
+		return err;
+	}
+
+	ubi->dev.devt = dev;
+
+	ubi_assert(MINOR(dev) == 0);
+	cdev_init(&ubi->cdev, &ubi_cdev_operations);
+	dbg_gen("%s major is %u", ubi->ubi_name, MAJOR(dev));
+	ubi->cdev.owner = THIS_MODULE;
+
+	dev_set_name(&ubi->dev, UBI_NAME_STR "%d", ubi->ubi_num);
+	err = cdev_device_add(&ubi->cdev, &ubi->dev);
+	if (err)
+		goto out_unreg;
+
+	for (i = 0; i < ubi->vtbl_slots; i++)
+		if (ubi->volumes[i]) {
+			err = ubi_add_volume(ubi, ubi->volumes[i]);
+			if (err) {
+				ubi_err(ubi, "cannot add volume %d", i);
+				ubi->volumes[i] = NULL;
+				goto out_volumes;
+			}
+		}
+
+	return 0;
+
+out_volumes:
+	kill_volumes(ubi);
+	cdev_device_del(&ubi->cdev, &ubi->dev);
+out_unreg:
+	unregister_chrdev_region(ubi->cdev.dev, ubi->vtbl_slots + 1);
+	ubi_err(ubi, "cannot initialize UBI %s, error %d",
+		ubi->ubi_name, err);
+	return err;
+}
+
+/**
+ * uif_close - close user interfaces for an UBI device.
+ * @ubi: UBI device description object
+ *
+ * Note, since this function un-registers UBI volume device objects (@vol->dev),
+ * the memory allocated voe the volumes is freed as well (in the release
+ * function).
+ */
+static void uif_close(struct ubi_device *ubi)
+{
+	kill_volumes(ubi);
+	cdev_device_del(&ubi->cdev, &ubi->dev);
+	unregister_chrdev_region(ubi->cdev.dev, ubi->vtbl_slots + 1);
+}
+
+/**
+ * ubi_free_volumes_from - free volumes from specific index.
+ * @ubi: UBI device description object
+ * @from: the start index used for volume free.
+ */
+static void ubi_free_volumes_from(struct ubi_device *ubi, int from)
+{
+	int i;
+
+	for (i = from; i < ubi->vtbl_slots + UBI_INT_VOL_COUNT; i++) {
+		if (!ubi->volumes[i])
+			continue;
+		ubi_eba_replace_table(ubi->volumes[i], NULL);
+		ubi_fastmap_destroy_checkmap(ubi->volumes[i]);
+		kfree(ubi->volumes[i]);
+		ubi->volumes[i] = NULL;
+	}
+}
+
+/**
+ * ubi_free_all_volumes - free all volumes.
+ * @ubi: UBI device description object
+ */
+void ubi_free_all_volumes(struct ubi_device *ubi)
+{
+	ubi_free_volumes_from(ubi, 0);
+}
+
+/**
+ * ubi_free_internal_volumes - free internal volumes.
+ * @ubi: UBI device description object
+ */
+void ubi_free_internal_volumes(struct ubi_device *ubi)
+{
+	ubi_free_volumes_from(ubi, ubi->vtbl_slots);
+}
+
+static int get_bad_peb_limit(const struct ubi_device *ubi, int max_beb_per1024)
+{
+	int limit, device_pebs;
+	uint64_t device_size;
+
+	if (!max_beb_per1024) {
+		/*
+		 * Since max_beb_per1024 has not been set by the user in either
+		 * the cmdline or Kconfig, use mtd_max_bad_blocks to set the
+		 * limit if it is supported by the device.
+		 */
+		limit = mtd_max_bad_blocks(ubi->mtd, 0, ubi->mtd->size);
+		if (limit < 0)
+			return 0;
+		return limit;
+	}
+
+	/*
+	 * Here we are using size of the entire flash chip and
+	 * not just the MTD partition size because the maximum
+	 * number of bad eraseblocks is a percentage of the
+	 * whole device and bad eraseblocks are not fairly
+	 * distributed over the flash chip. So the worst case
+	 * is that all the bad eraseblocks of the chip are in
+	 * the MTD partition we are attaching (ubi->mtd).
+	 */
+	device_size = mtd_get_device_size(ubi->mtd);
+	device_pebs = mtd_div_by_eb(device_size, ubi->mtd);
+	limit = mult_frac(device_pebs, max_beb_per1024, 1024);
+
+	/* Round it up */
+	if (mult_frac(limit, 1024, max_beb_per1024) < device_pebs)
+		limit += 1;
+
+	return limit;
+}
+
+/**
+ * io_init - initialize I/O sub-system for a given UBI device.
+ * @ubi: UBI device description object
+ * @max_beb_per1024: maximum expected number of bad PEB per 1024 PEBs
+ *
+ * If @ubi->vid_hdr_offset or @ubi->leb_start is zero, default offsets are
+ * assumed:
+ *   o EC header is always at offset zero - this cannot be changed;
+ *   o VID header starts just after the EC header at the closest address
+ *     aligned to @io->hdrs_min_io_size;
+ *   o data starts just after the VID header at the closest address aligned to
+ *     @io->min_io_size
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int io_init(struct ubi_device *ubi, int max_beb_per1024)
+{
+	dbg_gen("sizeof(struct ubi_ainf_peb) %zu", sizeof(struct ubi_ainf_peb));
+	dbg_gen("sizeof(struct ubi_wl_entry) %zu", sizeof(struct ubi_wl_entry));
+
+	if (ubi->mtd->numeraseregions != 0) {
+		/*
+		 * Some flashes have several erase regions. Different regions
+		 * may have different eraseblock size and other
+		 * characteristics. It looks like mostly multi-region flashes
+		 * have one "main" region and one or more small regions to
+		 * store boot loader code or boot parameters or whatever. I
+		 * guess we should just pick the largest region. But this is
+		 * not implemented.
+		 */
+		ubi_err(ubi, "multiple regions, not implemented");
+		return -EINVAL;
+	}
+
+	if (ubi->vid_hdr_offset < 0)
+		return -EINVAL;
+
+	/*
+	 * Note, in this implementation we support MTD devices with 0x7FFFFFFF
+	 * physical eraseblocks maximum.
+	 */
+
+	ubi->peb_size   = ubi->mtd->erasesize;
+	ubi->peb_count  = mtd_div_by_eb(ubi->mtd->size, ubi->mtd);
+	ubi->flash_size = ubi->mtd->size;
+
+	if (mtd_can_have_bb(ubi->mtd)) {
+		ubi->bad_allowed = 1;
+		ubi->bad_peb_limit = get_bad_peb_limit(ubi, max_beb_per1024);
+	}
+
+	if (ubi->mtd->type == MTD_NORFLASH)
+		ubi->nor_flash = 1;
+
+	ubi->min_io_size = ubi->mtd->writesize;
+	ubi->hdrs_min_io_size = ubi->mtd->writesize >> ubi->mtd->subpage_sft;
+
+	/*
+	 * Make sure minimal I/O unit is power of 2. Note, there is no
+	 * fundamental reason for this assumption. It is just an optimization
+	 * which allows us to avoid costly division operations.
+	 */
+	if (!is_power_of_2(ubi->min_io_size)) {
+		ubi_err(ubi, "min. I/O unit (%d) is not power of 2",
+			ubi->min_io_size);
+		return -EINVAL;
+	}
+
+	ubi_assert(ubi->hdrs_min_io_size > 0);
+	ubi_assert(ubi->hdrs_min_io_size <= ubi->min_io_size);
+	ubi_assert(ubi->min_io_size % ubi->hdrs_min_io_size == 0);
+
+	ubi->max_write_size = ubi->mtd->writebufsize;
+	/*
+	 * Maximum write size has to be greater or equivalent to min. I/O
+	 * size, and be multiple of min. I/O size.
+	 */
+	if (ubi->max_write_size < ubi->min_io_size ||
+	    ubi->max_write_size % ubi->min_io_size ||
+	    !is_power_of_2(ubi->max_write_size)) {
+		ubi_err(ubi, "bad write buffer size %d for %d min. I/O unit",
+			ubi->max_write_size, ubi->min_io_size);
+		return -EINVAL;
+	}
+
+	/* Calculate default aligned sizes of EC and VID headers */
+	ubi->ec_hdr_alsize = ALIGN(UBI_EC_HDR_SIZE, ubi->hdrs_min_io_size);
+	ubi->vid_hdr_alsize = ALIGN(UBI_VID_HDR_SIZE, ubi->hdrs_min_io_size);
+
+	dbg_gen("min_io_size      %d", ubi->min_io_size);
+	dbg_gen("max_write_size   %d", ubi->max_write_size);
+	dbg_gen("hdrs_min_io_size %d", ubi->hdrs_min_io_size);
+	dbg_gen("ec_hdr_alsize    %d", ubi->ec_hdr_alsize);
+	dbg_gen("vid_hdr_alsize   %d", ubi->vid_hdr_alsize);
+
+	if (ubi->vid_hdr_offset == 0)
+		/* Default offset */
+		ubi->vid_hdr_offset = ubi->vid_hdr_aloffset =
+				      ubi->ec_hdr_alsize;
+	else {
+		ubi->vid_hdr_aloffset = ubi->vid_hdr_offset &
+						~(ubi->hdrs_min_io_size - 1);
+		ubi->vid_hdr_shift = ubi->vid_hdr_offset -
+						ubi->vid_hdr_aloffset;
+	}
+
+	/*
+	 * Memory allocation for VID header is ubi->vid_hdr_alsize
+	 * which is described in comments in io.c.
+	 * Make sure VID header shift + UBI_VID_HDR_SIZE not exceeds
+	 * ubi->vid_hdr_alsize, so that all vid header operations
+	 * won't access memory out of bounds.
+	 */
+	if ((ubi->vid_hdr_shift + UBI_VID_HDR_SIZE) > ubi->vid_hdr_alsize) {
+		ubi_err(ubi, "Invalid VID header offset %d, VID header shift(%d)"
+			" + VID header size(%zu) > VID header aligned size(%d).",
+			ubi->vid_hdr_offset, ubi->vid_hdr_shift,
+			UBI_VID_HDR_SIZE, ubi->vid_hdr_alsize);
+		return -EINVAL;
+	}
+
+	/* Similar for the data offset */
+	ubi->leb_start = ubi->vid_hdr_offset + UBI_VID_HDR_SIZE;
+	ubi->leb_start = ALIGN(ubi->leb_start, ubi->min_io_size);
+
+	dbg_gen("vid_hdr_offset   %d", ubi->vid_hdr_offset);
+	dbg_gen("vid_hdr_aloffset %d", ubi->vid_hdr_aloffset);
+	dbg_gen("vid_hdr_shift    %d", ubi->vid_hdr_shift);
+	dbg_gen("leb_start        %d", ubi->leb_start);
+
+	/* The shift must be aligned to 32-bit boundary */
+	if (ubi->vid_hdr_shift % 4) {
+		ubi_err(ubi, "unaligned VID header shift %d",
+			ubi->vid_hdr_shift);
+		return -EINVAL;
+	}
+
+	/* Check sanity */
+	if (ubi->vid_hdr_offset < UBI_EC_HDR_SIZE ||
+	    ubi->leb_start < ubi->vid_hdr_offset + UBI_VID_HDR_SIZE ||
+	    ubi->leb_start > ubi->peb_size - UBI_VID_HDR_SIZE ||
+	    ubi->leb_start & (ubi->min_io_size - 1)) {
+		ubi_err(ubi, "bad VID header (%d) or data offsets (%d)",
+			ubi->vid_hdr_offset, ubi->leb_start);
+		return -EINVAL;
+	}
+
+	/*
+	 * Set maximum amount of physical erroneous eraseblocks to be 10%.
+	 * Erroneous PEB are those which have read errors.
+	 */
+	ubi->max_erroneous = ubi->peb_count / 10;
+	if (ubi->max_erroneous < 16)
+		ubi->max_erroneous = 16;
+	dbg_gen("max_erroneous    %d", ubi->max_erroneous);
+
+	/*
+	 * It may happen that EC and VID headers are situated in one minimal
+	 * I/O unit. In this case we can only accept this UBI image in
+	 * read-only mode.
+	 */
+	if (ubi->vid_hdr_offset + UBI_VID_HDR_SIZE <= ubi->hdrs_min_io_size) {
+		ubi_warn(ubi, "EC and VID headers are in the same minimal I/O unit, switch to read-only mode");
+		ubi->ro_mode = 1;
+	}
+
+	ubi->leb_size = ubi->peb_size - ubi->leb_start;
+
+	if (!(ubi->mtd->flags & MTD_WRITEABLE)) {
+		ubi_msg(ubi, "MTD device %d is write-protected, attach in read-only mode",
+			ubi->mtd->index);
+		ubi->ro_mode = 1;
+	}
+
+	/*
+	 * Note, ideally, we have to initialize @ubi->bad_peb_count here. But
+	 * unfortunately, MTD does not provide this information. We should loop
+	 * over all physical eraseblocks and invoke mtd->block_is_bad() for
+	 * each physical eraseblock. So, we leave @ubi->bad_peb_count
+	 * uninitialized so far.
+	 */
+
+	return 0;
+}
+
+/**
+ * autoresize - re-size the volume which has the "auto-resize" flag set.
+ * @ubi: UBI device description object
+ * @vol_id: ID of the volume to re-size
+ *
+ * This function re-sizes the volume marked by the %UBI_VTBL_AUTORESIZE_FLG in
+ * the volume table to the largest possible size. See comments in ubi-header.h
+ * for more description of the flag. Returns zero in case of success and a
+ * negative error code in case of failure.
+ */
+static int autoresize(struct ubi_device *ubi, int vol_id)
+{
+	struct ubi_volume_desc desc;
+	struct ubi_volume *vol = ubi->volumes[vol_id];
+	int err, old_reserved_pebs = vol->reserved_pebs;
+
+	if (ubi->ro_mode) {
+		ubi_warn(ubi, "skip auto-resize because of R/O mode");
+		return 0;
+	}
+
+	/*
+	 * Clear the auto-resize flag in the volume in-memory copy of the
+	 * volume table, and 'ubi_resize_volume()' will propagate this change
+	 * to the flash.
+	 */
+	ubi->vtbl[vol_id].flags &= ~UBI_VTBL_AUTORESIZE_FLG;
+
+	if (ubi->avail_pebs == 0) {
+		struct ubi_vtbl_record vtbl_rec;
+
+		/*
+		 * No available PEBs to re-size the volume, clear the flag on
+		 * flash and exit.
+		 */
+		vtbl_rec = ubi->vtbl[vol_id];
+		err = ubi_change_vtbl_record(ubi, vol_id, &vtbl_rec);
+		if (err)
+			ubi_err(ubi, "cannot clean auto-resize flag for volume %d",
+				vol_id);
+	} else {
+		desc.vol = vol;
+		err = ubi_resize_volume(&desc,
+					old_reserved_pebs + ubi->avail_pebs);
+		if (err)
+			ubi_err(ubi, "cannot auto-resize volume %d",
+				vol_id);
+	}
+
+	if (err)
+		return err;
+
+	ubi_msg(ubi, "volume %d (\"%s\") re-sized from %d to %d LEBs",
+		vol_id, vol->name, old_reserved_pebs, vol->reserved_pebs);
+	return 0;
+}
+
+/**
+ * ubi_attach_mtd_dev - attach an MTD device.
+ * @mtd: MTD device description object
+ * @ubi_num: number to assign to the new UBI device
+ * @vid_hdr_offset: VID header offset
+ * @max_beb_per1024: maximum expected number of bad PEB per 1024 PEBs
+ * @disable_fm: whether disable fastmap
+ *
+ * This function attaches MTD device @mtd_dev to UBI and assign @ubi_num number
+ * to the newly created UBI device, unless @ubi_num is %UBI_DEV_NUM_AUTO, in
+ * which case this function finds a vacant device number and assigns it
+ * automatically. Returns the new UBI device number in case of success and a
+ * negative error code in case of failure.
+ *
+ * If @disable_fm is true, ubi doesn't create new fastmap even the module param
+ * 'fm_autoconvert' is set, and existed old fastmap will be destroyed after
+ * doing full scanning.
+ *
+ * Note, the invocations of this function has to be serialized by the
+ * @ubi_devices_mutex.
+ */
+int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
+		       int vid_hdr_offset, int max_beb_per1024, bool disable_fm)
+{
+	struct ubi_device *ubi;
+	int i, err;
+
+	if (max_beb_per1024 < 0 || max_beb_per1024 > MAX_MTD_UBI_BEB_LIMIT)
+		return -EINVAL;
+
+	if (!max_beb_per1024)
+		max_beb_per1024 = CONFIG_MTD_UBI_BEB_LIMIT;
+
+	/*
+	 * Check if we already have the same MTD device attached.
+	 *
+	 * Note, this function assumes that UBI devices creations and deletions
+	 * are serialized, so it does not take the &ubi_devices_lock.
+	 */
+	for (i = 0; i < UBI_MAX_DEVICES; i++) {
+		ubi = ubi_devices[i];
+		if (ubi && mtd->index == ubi->mtd->index) {
+			pr_err("ubi: mtd%d is already attached to ubi%d\n",
+				mtd->index, i);
+			return -EEXIST;
+		}
+	}
+
+	/*
+	 * Make sure this MTD device is not emulated on top of an UBI volume
+	 * already. Well, generally this recursion works fine, but there are
+	 * different problems like the UBI module takes a reference to itself
+	 * by attaching (and thus, opening) the emulated MTD device. This
+	 * results in inability to unload the module. And in general it makes
+	 * no sense to attach emulated MTD devices, so we prohibit this.
+	 */
+	if (mtd->type == MTD_UBIVOLUME) {
+		pr_err("ubi: refuse attaching mtd%d - it is already emulated on top of UBI\n",
+			mtd->index);
+		return -EINVAL;
+	}
+
+	/*
+	 * Both UBI and UBIFS have been designed for SLC NAND and NOR flashes.
+	 * MLC NAND is different and needs special care, otherwise UBI or UBIFS
+	 * will die soon and you will lose all your data.
+	 * Relax this rule if the partition we're attaching to operates in SLC
+	 * mode.
+	 */
+	if (mtd->type == MTD_MLCNANDFLASH &&
+	    !(mtd->flags & MTD_SLC_ON_MLC_EMULATION)) {
+		pr_err("ubi: refuse attaching mtd%d - MLC NAND is not supported\n",
+			mtd->index);
+		return -EINVAL;
+	}
+
+	/* UBI cannot work on flashes with zero erasesize. */
+	if (!mtd->erasesize) {
+		pr_err("ubi: refuse attaching mtd%d - zero erasesize flash is not supported\n",
+			mtd->index);
+		return -EINVAL;
+	}
+
+	if (ubi_num == UBI_DEV_NUM_AUTO) {
+		/* Search for an empty slot in the @ubi_devices array */
+		for (ubi_num = 0; ubi_num < UBI_MAX_DEVICES; ubi_num++)
+			if (!ubi_devices[ubi_num])
+				break;
+		if (ubi_num == UBI_MAX_DEVICES) {
+			pr_err("ubi: only %d UBI devices may be created\n",
+				UBI_MAX_DEVICES);
+			return -ENFILE;
+		}
+	} else {
+		if (ubi_num >= UBI_MAX_DEVICES)
+			return -EINVAL;
+
+		/* Make sure ubi_num is not busy */
+		if (ubi_devices[ubi_num]) {
+			pr_err("ubi: ubi%i already exists\n", ubi_num);
+			return -EEXIST;
+		}
+	}
+
+	ubi = kzalloc(sizeof(struct ubi_device), GFP_KERNEL);
+	if (!ubi)
+		return -ENOMEM;
+
+	device_initialize(&ubi->dev);
+	ubi->dev.release = dev_release;
+	ubi->dev.class = &ubi_class;
+	ubi->dev.groups = ubi_dev_groups;
+	ubi->dev.parent = &mtd->dev;
+
+	ubi->mtd = mtd;
+	ubi->ubi_num = ubi_num;
+	ubi->vid_hdr_offset = vid_hdr_offset;
+	ubi->autoresize_vol_id = -1;
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+	ubi->fm_pool.used = ubi->fm_pool.size = 0;
+	ubi->fm_wl_pool.used = ubi->fm_wl_pool.size = 0;
+
+	/*
+	 * fm_pool.max_size is 5% of the total number of PEBs but it's also
+	 * between UBI_FM_MAX_POOL_SIZE and UBI_FM_MIN_POOL_SIZE.
+	 */
+	ubi->fm_pool.max_size = min(((int)mtd_div_by_eb(ubi->mtd->size,
+		ubi->mtd) / 100) * 5, UBI_FM_MAX_POOL_SIZE);
+	ubi->fm_pool.max_size = max(ubi->fm_pool.max_size,
+		UBI_FM_MIN_POOL_SIZE);
+
+	ubi->fm_wl_pool.max_size = ubi->fm_pool.max_size / 2;
+	ubi->fm_disabled = (!fm_autoconvert || disable_fm) ? 1 : 0;
+	if (fm_debug)
+		ubi_enable_dbg_chk_fastmap(ubi);
+
+	if (!ubi->fm_disabled && (int)mtd_div_by_eb(ubi->mtd->size, ubi->mtd)
+	    <= UBI_FM_MAX_START) {
+		ubi_err(ubi, "More than %i PEBs are needed for fastmap, sorry.",
+			UBI_FM_MAX_START);
+		ubi->fm_disabled = 1;
+	}
+
+	ubi_msg(ubi, "default fastmap pool size: %d", ubi->fm_pool.max_size);
+	ubi_msg(ubi, "default fastmap WL pool size: %d",
+		ubi->fm_wl_pool.max_size);
+#else
+	ubi->fm_disabled = 1;
+#endif
+	mutex_init(&ubi->buf_mutex);
+	mutex_init(&ubi->ckvol_mutex);
+	mutex_init(&ubi->device_mutex);
+	spin_lock_init(&ubi->volumes_lock);
+	init_rwsem(&ubi->fm_protect);
+	init_rwsem(&ubi->fm_eba_sem);
+
+	ubi_msg(ubi, "attaching mtd%d", mtd->index);
+
+	err = io_init(ubi, max_beb_per1024);
+	if (err)
+		goto out_free;
+
+	err = -ENOMEM;
+	ubi->peb_buf = vmalloc(ubi->peb_size);
+	if (!ubi->peb_buf)
+		goto out_free;
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+	ubi->fm_size = ubi_calc_fm_size(ubi);
+	ubi->fm_buf = vzalloc(ubi->fm_size);
+	if (!ubi->fm_buf)
+		goto out_free;
+#endif
+	err = ubi_attach(ubi, disable_fm ? 1 : 0);
+	if (err) {
+		ubi_err(ubi, "failed to attach mtd%d, error %d",
+			mtd->index, err);
+		goto out_free;
+	}
+
+	if (ubi->autoresize_vol_id != -1) {
+		err = autoresize(ubi, ubi->autoresize_vol_id);
+		if (err)
+			goto out_detach;
+	}
+
+	err = uif_init(ubi);
+	if (err)
+		goto out_detach;
+
+	err = ubi_debugfs_init_dev(ubi);
+	if (err)
+		goto out_uif;
+
+	ubi->bgt_thread = kthread_create(ubi_thread, ubi, "%s", ubi->bgt_name);
+	if (IS_ERR(ubi->bgt_thread)) {
+		err = PTR_ERR(ubi->bgt_thread);
+		ubi_err(ubi, "cannot spawn \"%s\", error %d",
+			ubi->bgt_name, err);
+		goto out_debugfs;
+	}
+
+	ubi_msg(ubi, "attached mtd%d (name \"%s\", size %llu MiB)",
+		mtd->index, mtd->name, ubi->flash_size >> 20);
+	ubi_msg(ubi, "PEB size: %d bytes (%d KiB), LEB size: %d bytes",
+		ubi->peb_size, ubi->peb_size >> 10, ubi->leb_size);
+	ubi_msg(ubi, "min./max. I/O unit sizes: %d/%d, sub-page size %d",
+		ubi->min_io_size, ubi->max_write_size, ubi->hdrs_min_io_size);
+	ubi_msg(ubi, "VID header offset: %d (aligned %d), data offset: %d",
+		ubi->vid_hdr_offset, ubi->vid_hdr_aloffset, ubi->leb_start);
+	ubi_msg(ubi, "good PEBs: %d, bad PEBs: %d, corrupted PEBs: %d",
+		ubi->good_peb_count, ubi->bad_peb_count, ubi->corr_peb_count);
+	ubi_msg(ubi, "user volume: %d, internal volumes: %d, max. volumes count: %d",
+		ubi->vol_count - UBI_INT_VOL_COUNT, UBI_INT_VOL_COUNT,
+		ubi->vtbl_slots);
+	ubi_msg(ubi, "max/mean erase counter: %d/%d, WL threshold: %d, image sequence number: %u",
+		ubi->max_ec, ubi->mean_ec, CONFIG_MTD_UBI_WL_THRESHOLD,
+		ubi->image_seq);
+	ubi_msg(ubi, "available PEBs: %d, total reserved PEBs: %d, PEBs reserved for bad PEB handling: %d",
+		ubi->avail_pebs, ubi->rsvd_pebs, ubi->beb_rsvd_pebs);
+
+	/*
+	 * The below lock makes sure we do not race with 'ubi_thread()' which
+	 * checks @ubi->thread_enabled. Otherwise we may fail to wake it up.
+	 */
+	spin_lock(&ubi->wl_lock);
+	ubi->thread_enabled = 1;
+	wake_up_process(ubi->bgt_thread);
+	spin_unlock(&ubi->wl_lock);
+
+	ubi_devices[ubi_num] = ubi;
+	ubi_notify_all(ubi, UBI_VOLUME_ADDED, NULL);
+	return ubi_num;
+
+out_debugfs:
+	ubi_debugfs_exit_dev(ubi);
+out_uif:
+	uif_close(ubi);
+out_detach:
+	ubi_wl_close(ubi);
+	ubi_free_all_volumes(ubi);
+	vfree(ubi->vtbl);
+out_free:
+	vfree(ubi->peb_buf);
+	vfree(ubi->fm_buf);
+	put_device(&ubi->dev);
+	return err;
+}
+
+/**
+ * ubi_detach_mtd_dev - detach an MTD device.
+ * @ubi_num: UBI device number to detach from
+ * @anyway: detach MTD even if device reference count is not zero
+ *
+ * This function destroys an UBI device number @ubi_num and detaches the
+ * underlying MTD device. Returns zero in case of success and %-EBUSY if the
+ * UBI device is busy and cannot be destroyed, and %-EINVAL if it does not
+ * exist.
+ *
+ * Note, the invocations of this function has to be serialized by the
+ * @ubi_devices_mutex.
+ */
+int ubi_detach_mtd_dev(int ubi_num, int anyway)
+{
+	struct ubi_device *ubi;
+
+	if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
+		return -EINVAL;
+
+	ubi = ubi_get_device(ubi_num);
+	if (!ubi)
+		return -EINVAL;
+
+	spin_lock(&ubi_devices_lock);
+	put_device(&ubi->dev);
+	ubi->ref_count -= 1;
+	if (ubi->ref_count) {
+		if (!anyway) {
+			spin_unlock(&ubi_devices_lock);
+			return -EBUSY;
+		}
+		/* This may only happen if there is a bug */
+		ubi_err(ubi, "%s reference count %d, destroy anyway",
+			ubi->ubi_name, ubi->ref_count);
+	}
+	ubi_devices[ubi_num] = NULL;
+	spin_unlock(&ubi_devices_lock);
+
+	ubi_assert(ubi_num == ubi->ubi_num);
+	ubi_notify_all(ubi, UBI_VOLUME_REMOVED, NULL);
+	ubi_msg(ubi, "detaching mtd%d", ubi->mtd->index);
+#ifdef CONFIG_MTD_UBI_FASTMAP
+	/* If we don't write a new fastmap at detach time we lose all
+	 * EC updates that have been made since the last written fastmap.
+	 * In case of fastmap debugging we omit the update to simulate an
+	 * unclean shutdown. */
+	if (!ubi_dbg_chk_fastmap(ubi))
+		ubi_update_fastmap(ubi);
+#endif
+	/*
+	 * Before freeing anything, we have to stop the background thread to
+	 * prevent it from doing anything on this device while we are freeing.
+	 */
+	if (ubi->bgt_thread)
+		kthread_stop(ubi->bgt_thread);
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+	cancel_work_sync(&ubi->fm_work);
+#endif
+	ubi_debugfs_exit_dev(ubi);
+	uif_close(ubi);
+
+	ubi_wl_close(ubi);
+	ubi_free_internal_volumes(ubi);
+	vfree(ubi->vtbl);
+	vfree(ubi->peb_buf);
+	vfree(ubi->fm_buf);
+	ubi_msg(ubi, "mtd%d is detached", ubi->mtd->index);
+	put_mtd_device(ubi->mtd);
+	put_device(&ubi->dev);
+	return 0;
+}
+
+/**
+ * open_mtd_by_chdev - open an MTD device by its character device node path.
+ * @mtd_dev: MTD character device node path
+ *
+ * This helper function opens an MTD device by its character node device path.
+ * Returns MTD device description object in case of success and a negative
+ * error code in case of failure.
+ */
+static struct mtd_info * __init open_mtd_by_chdev(const char *mtd_dev)
+{
+	int err, minor;
+	struct path path;
+	struct kstat stat;
+
+	/* Probably this is an MTD character device node path */
+	err = kern_path(mtd_dev, LOOKUP_FOLLOW, &path);
+	if (err)
+		return ERR_PTR(err);
+
+	err = vfs_getattr(&path, &stat, STATX_TYPE, AT_STATX_SYNC_AS_STAT);
+	path_put(&path);
+	if (err)
+		return ERR_PTR(err);
+
+	/* MTD device number is defined by the major / minor numbers */
+	if (MAJOR(stat.rdev) != MTD_CHAR_MAJOR || !S_ISCHR(stat.mode))
+		return ERR_PTR(-EINVAL);
+
+	minor = MINOR(stat.rdev);
+
+	if (minor & 1)
+		/*
+		 * Just do not think the "/dev/mtdrX" devices support is need,
+		 * so do not support them to avoid doing extra work.
+		 */
+		return ERR_PTR(-EINVAL);
+
+	return get_mtd_device(NULL, minor / 2);
+}
+
+/**
+ * open_mtd_device - open MTD device by name, character device path, or number.
+ * @mtd_dev: name, character device node path, or MTD device device number
+ *
+ * This function tries to open and MTD device described by @mtd_dev string,
+ * which is first treated as ASCII MTD device number, and if it is not true, it
+ * is treated as MTD device name, and if that is also not true, it is treated
+ * as MTD character device node path. Returns MTD device description object in
+ * case of success and a negative error code in case of failure.
+ */
+static struct mtd_info * __init open_mtd_device(const char *mtd_dev)
+{
+	struct mtd_info *mtd;
+	int mtd_num;
+	char *endp;
+
+	mtd_num = simple_strtoul(mtd_dev, &endp, 0);
+	if (*endp != '\0' || mtd_dev == endp) {
+		/*
+		 * This does not look like an ASCII integer, probably this is
+		 * MTD device name.
+		 */
+		mtd = get_mtd_device_nm(mtd_dev);
+		if (PTR_ERR(mtd) == -ENODEV)
+			/* Probably this is an MTD character device node path */
+			mtd = open_mtd_by_chdev(mtd_dev);
+	} else
+		mtd = get_mtd_device(NULL, mtd_num);
+
+	return mtd;
+}
+
+static int __init ubi_init(void)
+{
+	int err, i, k;
+
+	/* Ensure that EC and VID headers have correct size */
+	BUILD_BUG_ON(sizeof(struct ubi_ec_hdr) != 64);
+	BUILD_BUG_ON(sizeof(struct ubi_vid_hdr) != 64);
+
+	if (mtd_devs > UBI_MAX_DEVICES) {
+		pr_err("UBI error: too many MTD devices, maximum is %d\n",
+		       UBI_MAX_DEVICES);
+		return -EINVAL;
+	}
+
+	/* Create base sysfs directory and sysfs files */
+	err = class_register(&ubi_class);
+	if (err < 0)
+		return err;
+
+	err = misc_register(&ubi_ctrl_cdev);
+	if (err) {
+		pr_err("UBI error: cannot register device\n");
+		goto out;
+	}
+
+	ubi_wl_entry_slab = kmem_cache_create("ubi_wl_entry_slab",
+					      sizeof(struct ubi_wl_entry),
+					      0, 0, NULL);
+	if (!ubi_wl_entry_slab) {
+		err = -ENOMEM;
+		goto out_dev_unreg;
+	}
+
+	err = ubi_debugfs_init();
+	if (err)
+		goto out_slab;
+
+
+	/* Attach MTD devices */
+	for (i = 0; i < mtd_devs; i++) {
+		struct mtd_dev_param *p = &mtd_dev_param[i];
+		struct mtd_info *mtd;
+
+		cond_resched();
+
+		mtd = open_mtd_device(p->name);
+		if (IS_ERR(mtd)) {
+			err = PTR_ERR(mtd);
+			pr_err("UBI error: cannot open mtd %s, error %d\n",
+			       p->name, err);
+			/* See comment below re-ubi_is_module(). */
+			if (ubi_is_module())
+				goto out_detach;
+			continue;
+		}
+
+		mutex_lock(&ubi_devices_mutex);
+		err = ubi_attach_mtd_dev(mtd, p->ubi_num,
+					 p->vid_hdr_offs, p->max_beb_per1024,
+					 p->enable_fm == 0);
+		mutex_unlock(&ubi_devices_mutex);
+		if (err < 0) {
+			pr_err("UBI error: cannot attach mtd%d\n",
+			       mtd->index);
+			put_mtd_device(mtd);
+
+			/*
+			 * Originally UBI stopped initializing on any error.
+			 * However, later on it was found out that this
+			 * behavior is not very good when UBI is compiled into
+			 * the kernel and the MTD devices to attach are passed
+			 * through the command line. Indeed, UBI failure
+			 * stopped whole boot sequence.
+			 *
+			 * To fix this, we changed the behavior for the
+			 * non-module case, but preserved the old behavior for
+			 * the module case, just for compatibility. This is a
+			 * little inconsistent, though.
+			 */
+			if (ubi_is_module())
+				goto out_detach;
+		}
+	}
+
+	err = ubiblock_init();
+	if (err) {
+		pr_err("UBI error: block: cannot initialize, error %d\n", err);
+
+		/* See comment above re-ubi_is_module(). */
+		if (ubi_is_module())
+			goto out_detach;
+	}
+
+	return 0;
+
+out_detach:
+	for (k = 0; k < i; k++)
+		if (ubi_devices[k]) {
+			mutex_lock(&ubi_devices_mutex);
+			ubi_detach_mtd_dev(ubi_devices[k]->ubi_num, 1);
+			mutex_unlock(&ubi_devices_mutex);
+		}
+	ubi_debugfs_exit();
+out_slab:
+	kmem_cache_destroy(ubi_wl_entry_slab);
+out_dev_unreg:
+	misc_deregister(&ubi_ctrl_cdev);
+out:
+	class_unregister(&ubi_class);
+	pr_err("UBI error: cannot initialize UBI, error %d\n", err);
+	return err;
+}
+late_initcall(ubi_init);
+
+static void __exit ubi_exit(void)
+{
+	int i;
+
+	ubiblock_exit();
+
+	for (i = 0; i < UBI_MAX_DEVICES; i++)
+		if (ubi_devices[i]) {
+			mutex_lock(&ubi_devices_mutex);
+			ubi_detach_mtd_dev(ubi_devices[i]->ubi_num, 1);
+			mutex_unlock(&ubi_devices_mutex);
+		}
+	ubi_debugfs_exit();
+	kmem_cache_destroy(ubi_wl_entry_slab);
+	misc_deregister(&ubi_ctrl_cdev);
+	class_unregister(&ubi_class);
+}
+module_exit(ubi_exit);
+
+/**
+ * bytes_str_to_int - convert a number of bytes string into an integer.
+ * @str: the string to convert
+ *
+ * This function returns positive resulting integer in case of success and a
+ * negative error code in case of failure.
+ */
+static int bytes_str_to_int(const char *str)
+{
+	char *endp;
+	unsigned long result;
+
+	result = simple_strtoul(str, &endp, 0);
+	if (str == endp || result >= INT_MAX) {
+		pr_err("UBI error: incorrect bytes count: \"%s\"\n", str);
+		return -EINVAL;
+	}
+
+	switch (*endp) {
+	case 'G':
+		result *= 1024;
+		fallthrough;
+	case 'M':
+		result *= 1024;
+		fallthrough;
+	case 'K':
+		result *= 1024;
+		break;
+	case '\0':
+		break;
+	default:
+		pr_err("UBI error: incorrect bytes count: \"%s\"\n", str);
+		return -EINVAL;
+	}
+
+	return result;
+}
+
+/**
+ * ubi_mtd_param_parse - parse the 'mtd=' UBI parameter.
+ * @val: the parameter value to parse
+ * @kp: not used
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of error.
+ */
+static int ubi_mtd_param_parse(const char *val, const struct kernel_param *kp)
+{
+	int i, len;
+	struct mtd_dev_param *p;
+	char buf[MTD_PARAM_LEN_MAX];
+	char *pbuf = &buf[0];
+	char *tokens[MTD_PARAM_MAX_COUNT], *token;
+
+	if (!val)
+		return -EINVAL;
+
+	if (mtd_devs == UBI_MAX_DEVICES) {
+		pr_err("UBI error: too many parameters, max. is %d\n",
+		       UBI_MAX_DEVICES);
+		return -EINVAL;
+	}
+
+	len = strnlen(val, MTD_PARAM_LEN_MAX);
+	if (len == MTD_PARAM_LEN_MAX) {
+		pr_err("UBI error: parameter \"%s\" is too long, max. is %d\n",
+		       val, MTD_PARAM_LEN_MAX);
+		return -EINVAL;
+	}
+
+	if (len == 0) {
+		pr_warn("UBI warning: empty 'mtd=' parameter - ignored\n");
+		return 0;
+	}
+
+	strcpy(buf, val);
+
+	/* Get rid of the final newline */
+	if (buf[len - 1] == '\n')
+		buf[len - 1] = '\0';
+
+	for (i = 0; i < MTD_PARAM_MAX_COUNT; i++)
+		tokens[i] = strsep(&pbuf, ",");
+
+	if (pbuf) {
+		pr_err("UBI error: too many arguments at \"%s\"\n", val);
+		return -EINVAL;
+	}
+
+	p = &mtd_dev_param[mtd_devs];
+	strcpy(&p->name[0], tokens[0]);
+
+	token = tokens[1];
+	if (token) {
+		p->vid_hdr_offs = bytes_str_to_int(token);
+
+		if (p->vid_hdr_offs < 0)
+			return p->vid_hdr_offs;
+	}
+
+	token = tokens[2];
+	if (token) {
+		int err = kstrtoint(token, 10, &p->max_beb_per1024);
+
+		if (err) {
+			pr_err("UBI error: bad value for max_beb_per1024 parameter: %s\n",
+			       token);
+			return -EINVAL;
+		}
+	}
+
+	token = tokens[3];
+	if (token) {
+		int err = kstrtoint(token, 10, &p->ubi_num);
+
+		if (err) {
+			pr_err("UBI error: bad value for ubi_num parameter: %s\n",
+			       token);
+			return -EINVAL;
+		}
+	} else
+		p->ubi_num = UBI_DEV_NUM_AUTO;
+
+	token = tokens[4];
+	if (token) {
+		int err = kstrtoint(token, 10, &p->enable_fm);
+
+		if (err) {
+			pr_err("UBI error: bad value for enable_fm parameter: %s\n",
+				token);
+			return -EINVAL;
+		}
+	} else
+		p->enable_fm = 0;
+
+	mtd_devs += 1;
+	return 0;
+}
+
+module_param_call(mtd, ubi_mtd_param_parse, NULL, NULL, 0400);
+MODULE_PARM_DESC(mtd, "MTD devices to attach. Parameter format: mtd=<name|num|path>[,<vid_hdr_offs>[,max_beb_per1024[,ubi_num]]].\n"
+		      "Multiple \"mtd\" parameters may be specified.\n"
+		      "MTD devices may be specified by their number, name, or path to the MTD character device node.\n"
+		      "Optional \"vid_hdr_offs\" parameter specifies UBI VID header position to be used by UBI. (default value if 0)\n"
+		      "Optional \"max_beb_per1024\" parameter specifies the maximum expected bad eraseblock per 1024 eraseblocks. (default value ("
+		      __stringify(CONFIG_MTD_UBI_BEB_LIMIT) ") if 0)\n"
+		      "Optional \"ubi_num\" parameter specifies UBI device number which have to be assigned to the newly created UBI device (assigned automatically by default)\n"
+		      "Optional \"enable_fm\" parameter determines whether to enable fastmap during attach. If the value is non-zero, fastmap is enabled. Default value is 0.\n"
+		      "\n"
+		      "Example 1: mtd=/dev/mtd0 - attach MTD device /dev/mtd0.\n"
+		      "Example 2: mtd=content,1984 mtd=4 - attach MTD device with name \"content\" using VID header offset 1984, and MTD device number 4 with default VID header offset.\n"
+		      "Example 3: mtd=/dev/mtd1,0,25 - attach MTD device /dev/mtd1 using default VID header offset and reserve 25*nand_size_in_blocks/1024 erase blocks for bad block handling.\n"
+		      "Example 4: mtd=/dev/mtd1,0,0,5 - attach MTD device /dev/mtd1 to UBI 5 and using default values for the other fields.\n"
+		      "example 5: mtd=1,0,0,5 mtd=2,0,0,6,1 - attach MTD device /dev/mtd1 to UBI 5 and disable fastmap; attach MTD device /dev/mtd2 to UBI 6 and enable fastmap.(only works when fastmap is enabled and fm_autoconvert=Y).\n"
+		      "\t(e.g. if the NAND *chipset* has 4096 PEB, 100 will be reserved for this UBI device).");
+#ifdef CONFIG_MTD_UBI_FASTMAP
+module_param(fm_autoconvert, bool, 0644);
+MODULE_PARM_DESC(fm_autoconvert, "Set this parameter to enable fastmap automatically on images without a fastmap.");
+module_param(fm_debug, bool, 0);
+MODULE_PARM_DESC(fm_debug, "Set this parameter to enable fastmap debugging by default. Warning, this will make fastmap slow!");
+#endif
+MODULE_VERSION(__stringify(UBI_VERSION));
+MODULE_DESCRIPTION("UBI - Unsorted Block Images");
+MODULE_AUTHOR("Artem Bityutskiy");
+MODULE_LICENSE("GPL");
diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
new file mode 100644
index 0000000000..f43430b9c1
--- /dev/null
+++ b/drivers/mtd/ubi/cdev.c
@@ -0,0 +1,1108 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+/*
+ * This file includes implementation of UBI character device operations.
+ *
+ * There are two kinds of character devices in UBI: UBI character devices and
+ * UBI volume character devices. UBI character devices allow users to
+ * manipulate whole volumes: create, remove, and re-size them. Volume character
+ * devices provide volume I/O capabilities.
+ *
+ * Major and minor numbers are assigned dynamically to both UBI and volume
+ * character devices.
+ *
+ * Well, there is the third kind of character devices - the UBI control
+ * character device, which allows to manipulate by UBI devices - create and
+ * delete them. In other words, it is used for attaching and detaching MTD
+ * devices.
+ */
+
+#include <linux/module.h>
+#include <linux/stat.h>
+#include <linux/slab.h>
+#include <linux/ioctl.h>
+#include <linux/capability.h>
+#include <linux/uaccess.h>
+#include <linux/compat.h>
+#include <linux/math64.h>
+#include <mtd/ubi-user.h>
+#include "ubi.h"
+
+/**
+ * get_exclusive - get exclusive access to an UBI volume.
+ * @desc: volume descriptor
+ *
+ * This function changes UBI volume open mode to "exclusive". Returns previous
+ * mode value (positive integer) in case of success and a negative error code
+ * in case of failure.
+ */
+static int get_exclusive(struct ubi_volume_desc *desc)
+{
+	int users, err;
+	struct ubi_volume *vol = desc->vol;
+
+	spin_lock(&vol->ubi->volumes_lock);
+	users = vol->readers + vol->writers + vol->exclusive + vol->metaonly;
+	ubi_assert(users > 0);
+	if (users > 1) {
+		ubi_err(vol->ubi, "%d users for volume %d", users, vol->vol_id);
+		err = -EBUSY;
+	} else {
+		vol->readers = vol->writers = vol->metaonly = 0;
+		vol->exclusive = 1;
+		err = desc->mode;
+		desc->mode = UBI_EXCLUSIVE;
+	}
+	spin_unlock(&vol->ubi->volumes_lock);
+
+	return err;
+}
+
+/**
+ * revoke_exclusive - revoke exclusive mode.
+ * @desc: volume descriptor
+ * @mode: new mode to switch to
+ */
+static void revoke_exclusive(struct ubi_volume_desc *desc, int mode)
+{
+	struct ubi_volume *vol = desc->vol;
+
+	spin_lock(&vol->ubi->volumes_lock);
+	ubi_assert(vol->readers == 0 && vol->writers == 0 && vol->metaonly == 0);
+	ubi_assert(vol->exclusive == 1 && desc->mode == UBI_EXCLUSIVE);
+	vol->exclusive = 0;
+	if (mode == UBI_READONLY)
+		vol->readers = 1;
+	else if (mode == UBI_READWRITE)
+		vol->writers = 1;
+	else if (mode == UBI_METAONLY)
+		vol->metaonly = 1;
+	else
+		vol->exclusive = 1;
+	spin_unlock(&vol->ubi->volumes_lock);
+
+	desc->mode = mode;
+}
+
+static int vol_cdev_open(struct inode *inode, struct file *file)
+{
+	struct ubi_volume_desc *desc;
+	int vol_id = iminor(inode) - 1, mode, ubi_num;
+
+	ubi_num = ubi_major2num(imajor(inode));
+	if (ubi_num < 0)
+		return ubi_num;
+
+	if (file->f_mode & FMODE_WRITE)
+		mode = UBI_READWRITE;
+	else
+		mode = UBI_READONLY;
+
+	dbg_gen("open device %d, volume %d, mode %d",
+		ubi_num, vol_id, mode);
+
+	desc = ubi_open_volume(ubi_num, vol_id, mode);
+	if (IS_ERR(desc))
+		return PTR_ERR(desc);
+
+	file->private_data = desc;
+	return 0;
+}
+
+static int vol_cdev_release(struct inode *inode, struct file *file)
+{
+	struct ubi_volume_desc *desc = file->private_data;
+	struct ubi_volume *vol = desc->vol;
+
+	dbg_gen("release device %d, volume %d, mode %d",
+		vol->ubi->ubi_num, vol->vol_id, desc->mode);
+
+	if (vol->updating) {
+		ubi_warn(vol->ubi, "update of volume %d not finished, volume is damaged",
+			 vol->vol_id);
+		ubi_assert(!vol->changing_leb);
+		vol->updating = 0;
+		vfree(vol->upd_buf);
+	} else if (vol->changing_leb) {
+		dbg_gen("only %lld of %lld bytes received for atomic LEB change for volume %d:%d, cancel",
+			vol->upd_received, vol->upd_bytes, vol->ubi->ubi_num,
+			vol->vol_id);
+		vol->changing_leb = 0;
+		vfree(vol->upd_buf);
+	}
+
+	ubi_close_volume(desc);
+	return 0;
+}
+
+static loff_t vol_cdev_llseek(struct file *file, loff_t offset, int origin)
+{
+	struct ubi_volume_desc *desc = file->private_data;
+	struct ubi_volume *vol = desc->vol;
+
+	if (vol->updating) {
+		/* Update is in progress, seeking is prohibited */
+		ubi_err(vol->ubi, "updating");
+		return -EBUSY;
+	}
+
+	return fixed_size_llseek(file, offset, origin, vol->used_bytes);
+}
+
+static int vol_cdev_fsync(struct file *file, loff_t start, loff_t end,
+			  int datasync)
+{
+	struct ubi_volume_desc *desc = file->private_data;
+	struct ubi_device *ubi = desc->vol->ubi;
+	struct inode *inode = file_inode(file);
+	int err;
+	inode_lock(inode);
+	err = ubi_sync(ubi->ubi_num);
+	inode_unlock(inode);
+	return err;
+}
+
+
+static ssize_t vol_cdev_read(struct file *file, __user char *buf, size_t count,
+			     loff_t *offp)
+{
+	struct ubi_volume_desc *desc = file->private_data;
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+	int err, lnum, off, len,  tbuf_size;
+	size_t count_save = count;
+	void *tbuf;
+
+	dbg_gen("read %zd bytes from offset %lld of volume %d",
+		count, *offp, vol->vol_id);
+
+	if (vol->updating) {
+		ubi_err(vol->ubi, "updating");
+		return -EBUSY;
+	}
+	if (vol->upd_marker) {
+		ubi_err(vol->ubi, "damaged volume, update marker is set");
+		return -EBADF;
+	}
+	if (*offp == vol->used_bytes || count == 0)
+		return 0;
+
+	if (vol->corrupted)
+		dbg_gen("read from corrupted volume %d", vol->vol_id);
+
+	if (*offp + count > vol->used_bytes)
+		count_save = count = vol->used_bytes - *offp;
+
+	tbuf_size = vol->usable_leb_size;
+	if (count < tbuf_size)
+		tbuf_size = ALIGN(count, ubi->min_io_size);
+	tbuf = vmalloc(tbuf_size);
+	if (!tbuf)
+		return -ENOMEM;
+
+	len = count > tbuf_size ? tbuf_size : count;
+	lnum = div_u64_rem(*offp, vol->usable_leb_size, &off);
+
+	do {
+		cond_resched();
+
+		if (off + len >= vol->usable_leb_size)
+			len = vol->usable_leb_size - off;
+
+		err = ubi_eba_read_leb(ubi, vol, lnum, tbuf, off, len, 0);
+		if (err)
+			break;
+
+		off += len;
+		if (off == vol->usable_leb_size) {
+			lnum += 1;
+			off -= vol->usable_leb_size;
+		}
+
+		count -= len;
+		*offp += len;
+
+		err = copy_to_user(buf, tbuf, len);
+		if (err) {
+			err = -EFAULT;
+			break;
+		}
+
+		buf += len;
+		len = count > tbuf_size ? tbuf_size : count;
+	} while (count);
+
+	vfree(tbuf);
+	return err ? err : count_save - count;
+}
+
+/*
+ * This function allows to directly write to dynamic UBI volumes, without
+ * issuing the volume update operation.
+ */
+static ssize_t vol_cdev_direct_write(struct file *file, const char __user *buf,
+				     size_t count, loff_t *offp)
+{
+	struct ubi_volume_desc *desc = file->private_data;
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+	int lnum, off, len, tbuf_size, err = 0;
+	size_t count_save = count;
+	char *tbuf;
+
+	if (!vol->direct_writes)
+		return -EPERM;
+
+	dbg_gen("requested: write %zd bytes to offset %lld of volume %u",
+		count, *offp, vol->vol_id);
+
+	if (vol->vol_type == UBI_STATIC_VOLUME)
+		return -EROFS;
+
+	lnum = div_u64_rem(*offp, vol->usable_leb_size, &off);
+	if (off & (ubi->min_io_size - 1)) {
+		ubi_err(ubi, "unaligned position");
+		return -EINVAL;
+	}
+
+	if (*offp + count > vol->used_bytes)
+		count_save = count = vol->used_bytes - *offp;
+
+	/* We can write only in fractions of the minimum I/O unit */
+	if (count & (ubi->min_io_size - 1)) {
+		ubi_err(ubi, "unaligned write length");
+		return -EINVAL;
+	}
+
+	tbuf_size = vol->usable_leb_size;
+	if (count < tbuf_size)
+		tbuf_size = ALIGN(count, ubi->min_io_size);
+	tbuf = vmalloc(tbuf_size);
+	if (!tbuf)
+		return -ENOMEM;
+
+	len = count > tbuf_size ? tbuf_size : count;
+
+	while (count) {
+		cond_resched();
+
+		if (off + len >= vol->usable_leb_size)
+			len = vol->usable_leb_size - off;
+
+		err = copy_from_user(tbuf, buf, len);
+		if (err) {
+			err = -EFAULT;
+			break;
+		}
+
+		err = ubi_eba_write_leb(ubi, vol, lnum, tbuf, off, len);
+		if (err)
+			break;
+
+		off += len;
+		if (off == vol->usable_leb_size) {
+			lnum += 1;
+			off -= vol->usable_leb_size;
+		}
+
+		count -= len;
+		*offp += len;
+		buf += len;
+		len = count > tbuf_size ? tbuf_size : count;
+	}
+
+	vfree(tbuf);
+	return err ? err : count_save - count;
+}
+
+static ssize_t vol_cdev_write(struct file *file, const char __user *buf,
+			      size_t count, loff_t *offp)
+{
+	int err = 0;
+	struct ubi_volume_desc *desc = file->private_data;
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+
+	if (!vol->updating && !vol->changing_leb)
+		return vol_cdev_direct_write(file, buf, count, offp);
+
+	if (vol->updating)
+		err = ubi_more_update_data(ubi, vol, buf, count);
+	else
+		err = ubi_more_leb_change_data(ubi, vol, buf, count);
+
+	if (err < 0) {
+		ubi_err(ubi, "cannot accept more %zd bytes of data, error %d",
+			count, err);
+		return err;
+	}
+
+	if (err) {
+		/*
+		 * The operation is finished, @err contains number of actually
+		 * written bytes.
+		 */
+		count = err;
+
+		if (vol->changing_leb) {
+			revoke_exclusive(desc, UBI_READWRITE);
+			return count;
+		}
+
+		/*
+		 * We voluntarily do not take into account the skip_check flag
+		 * as we want to make sure what we wrote was correctly written.
+		 */
+		err = ubi_check_volume(ubi, vol->vol_id);
+		if (err < 0)
+			return err;
+
+		if (err) {
+			ubi_warn(ubi, "volume %d on UBI device %d is corrupted",
+				 vol->vol_id, ubi->ubi_num);
+			vol->corrupted = 1;
+		}
+		vol->checked = 1;
+		ubi_volume_notify(ubi, vol, UBI_VOLUME_UPDATED);
+		revoke_exclusive(desc, UBI_READWRITE);
+	}
+
+	return count;
+}
+
+static long vol_cdev_ioctl(struct file *file, unsigned int cmd,
+			   unsigned long arg)
+{
+	int err = 0;
+	struct ubi_volume_desc *desc = file->private_data;
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+	void __user *argp = (void __user *)arg;
+
+	switch (cmd) {
+	/* Volume update command */
+	case UBI_IOCVOLUP:
+	{
+		int64_t bytes, rsvd_bytes;
+
+		if (!capable(CAP_SYS_RESOURCE)) {
+			err = -EPERM;
+			break;
+		}
+
+		err = copy_from_user(&bytes, argp, sizeof(int64_t));
+		if (err) {
+			err = -EFAULT;
+			break;
+		}
+
+		if (desc->mode == UBI_READONLY) {
+			err = -EROFS;
+			break;
+		}
+
+		rsvd_bytes = (long long)vol->reserved_pebs *
+					vol->usable_leb_size;
+		if (bytes < 0 || bytes > rsvd_bytes) {
+			err = -EINVAL;
+			break;
+		}
+
+		err = get_exclusive(desc);
+		if (err < 0)
+			break;
+
+		err = ubi_start_update(ubi, vol, bytes);
+		if (bytes == 0) {
+			ubi_volume_notify(ubi, vol, UBI_VOLUME_UPDATED);
+			revoke_exclusive(desc, UBI_READWRITE);
+		}
+		break;
+	}
+
+	/* Atomic logical eraseblock change command */
+	case UBI_IOCEBCH:
+	{
+		struct ubi_leb_change_req req;
+
+		err = copy_from_user(&req, argp,
+				     sizeof(struct ubi_leb_change_req));
+		if (err) {
+			err = -EFAULT;
+			break;
+		}
+
+		if (desc->mode == UBI_READONLY ||
+		    vol->vol_type == UBI_STATIC_VOLUME) {
+			err = -EROFS;
+			break;
+		}
+
+		/* Validate the request */
+		err = -EINVAL;
+		if (!ubi_leb_valid(vol, req.lnum) ||
+		    req.bytes < 0 || req.bytes > vol->usable_leb_size)
+			break;
+
+		err = get_exclusive(desc);
+		if (err < 0)
+			break;
+
+		err = ubi_start_leb_change(ubi, vol, &req);
+		if (req.bytes == 0)
+			revoke_exclusive(desc, UBI_READWRITE);
+		break;
+	}
+
+	/* Logical eraseblock erasure command */
+	case UBI_IOCEBER:
+	{
+		int32_t lnum;
+
+		err = get_user(lnum, (__user int32_t *)argp);
+		if (err) {
+			err = -EFAULT;
+			break;
+		}
+
+		if (desc->mode == UBI_READONLY ||
+		    vol->vol_type == UBI_STATIC_VOLUME) {
+			err = -EROFS;
+			break;
+		}
+
+		if (!ubi_leb_valid(vol, lnum)) {
+			err = -EINVAL;
+			break;
+		}
+
+		dbg_gen("erase LEB %d:%d", vol->vol_id, lnum);
+		err = ubi_eba_unmap_leb(ubi, vol, lnum);
+		if (err)
+			break;
+
+		err = ubi_wl_flush(ubi, UBI_ALL, UBI_ALL);
+		break;
+	}
+
+	/* Logical eraseblock map command */
+	case UBI_IOCEBMAP:
+	{
+		struct ubi_map_req req;
+
+		err = copy_from_user(&req, argp, sizeof(struct ubi_map_req));
+		if (err) {
+			err = -EFAULT;
+			break;
+		}
+		err = ubi_leb_map(desc, req.lnum);
+		break;
+	}
+
+	/* Logical eraseblock un-map command */
+	case UBI_IOCEBUNMAP:
+	{
+		int32_t lnum;
+
+		err = get_user(lnum, (__user int32_t *)argp);
+		if (err) {
+			err = -EFAULT;
+			break;
+		}
+		err = ubi_leb_unmap(desc, lnum);
+		break;
+	}
+
+	/* Check if logical eraseblock is mapped command */
+	case UBI_IOCEBISMAP:
+	{
+		int32_t lnum;
+
+		err = get_user(lnum, (__user int32_t *)argp);
+		if (err) {
+			err = -EFAULT;
+			break;
+		}
+		err = ubi_is_mapped(desc, lnum);
+		break;
+	}
+
+	/* Set volume property command */
+	case UBI_IOCSETVOLPROP:
+	{
+		struct ubi_set_vol_prop_req req;
+
+		err = copy_from_user(&req, argp,
+				     sizeof(struct ubi_set_vol_prop_req));
+		if (err) {
+			err = -EFAULT;
+			break;
+		}
+		switch (req.property) {
+		case UBI_VOL_PROP_DIRECT_WRITE:
+			mutex_lock(&ubi->device_mutex);
+			desc->vol->direct_writes = !!req.value;
+			mutex_unlock(&ubi->device_mutex);
+			break;
+		default:
+			err = -EINVAL;
+			break;
+		}
+		break;
+	}
+
+	/* Create a R/O block device on top of the UBI volume */
+	case UBI_IOCVOLCRBLK:
+	{
+		struct ubi_volume_info vi;
+
+		ubi_get_volume_info(desc, &vi);
+		err = ubiblock_create(&vi);
+		break;
+	}
+
+	/* Remove the R/O block device */
+	case UBI_IOCVOLRMBLK:
+	{
+		struct ubi_volume_info vi;
+
+		ubi_get_volume_info(desc, &vi);
+		err = ubiblock_remove(&vi);
+		break;
+	}
+
+	default:
+		err = -ENOTTY;
+		break;
+	}
+	return err;
+}
+
+/**
+ * verify_mkvol_req - verify volume creation request.
+ * @ubi: UBI device description object
+ * @req: the request to check
+ *
+ * This function zero if the request is correct, and %-EINVAL if not.
+ */
+static int verify_mkvol_req(const struct ubi_device *ubi,
+			    const struct ubi_mkvol_req *req)
+{
+	int n, err = -EINVAL;
+
+	if (req->bytes < 0 || req->alignment < 0 || req->vol_type < 0 ||
+	    req->name_len < 0)
+		goto bad;
+
+	if ((req->vol_id < 0 || req->vol_id >= ubi->vtbl_slots) &&
+	    req->vol_id != UBI_VOL_NUM_AUTO)
+		goto bad;
+
+	if (req->alignment == 0)
+		goto bad;
+
+	if (req->bytes == 0)
+		goto bad;
+
+	if (req->vol_type != UBI_DYNAMIC_VOLUME &&
+	    req->vol_type != UBI_STATIC_VOLUME)
+		goto bad;
+
+	if (req->flags & ~UBI_VOL_VALID_FLGS)
+		goto bad;
+
+	if (req->flags & UBI_VOL_SKIP_CRC_CHECK_FLG &&
+	    req->vol_type != UBI_STATIC_VOLUME)
+		goto bad;
+
+	if (req->alignment > ubi->leb_size)
+		goto bad;
+
+	n = req->alignment & (ubi->min_io_size - 1);
+	if (req->alignment != 1 && n)
+		goto bad;
+
+	if (!req->name[0] || !req->name_len)
+		goto bad;
+
+	if (req->name_len > UBI_VOL_NAME_MAX) {
+		err = -ENAMETOOLONG;
+		goto bad;
+	}
+
+	n = strnlen(req->name, req->name_len + 1);
+	if (n != req->name_len)
+		goto bad;
+
+	return 0;
+
+bad:
+	ubi_err(ubi, "bad volume creation request");
+	ubi_dump_mkvol_req(req);
+	return err;
+}
+
+/**
+ * verify_rsvol_req - verify volume re-size request.
+ * @ubi: UBI device description object
+ * @req: the request to check
+ *
+ * This function returns zero if the request is correct, and %-EINVAL if not.
+ */
+static int verify_rsvol_req(const struct ubi_device *ubi,
+			    const struct ubi_rsvol_req *req)
+{
+	if (req->bytes <= 0)
+		return -EINVAL;
+
+	if (req->vol_id < 0 || req->vol_id >= ubi->vtbl_slots)
+		return -EINVAL;
+
+	return 0;
+}
+
+/**
+ * rename_volumes - rename UBI volumes.
+ * @ubi: UBI device description object
+ * @req: volumes re-name request
+ *
+ * This is a helper function for the volume re-name IOCTL which validates the
+ * request, opens the volume and calls corresponding volumes management
+ * function. Returns zero in case of success and a negative error code in case
+ * of failure.
+ */
+static int rename_volumes(struct ubi_device *ubi,
+			  struct ubi_rnvol_req *req)
+{
+	int i, n, err;
+	struct list_head rename_list;
+	struct ubi_rename_entry *re, *re1;
+
+	if (req->count < 0 || req->count > UBI_MAX_RNVOL)
+		return -EINVAL;
+
+	if (req->count == 0)
+		return 0;
+
+	/* Validate volume IDs and names in the request */
+	for (i = 0; i < req->count; i++) {
+		if (req->ents[i].vol_id < 0 ||
+		    req->ents[i].vol_id >= ubi->vtbl_slots)
+			return -EINVAL;
+		if (req->ents[i].name_len < 0)
+			return -EINVAL;
+		if (req->ents[i].name_len > UBI_VOL_NAME_MAX)
+			return -ENAMETOOLONG;
+		req->ents[i].name[req->ents[i].name_len] = '\0';
+		n = strlen(req->ents[i].name);
+		if (n != req->ents[i].name_len)
+			return -EINVAL;
+	}
+
+	/* Make sure volume IDs and names are unique */
+	for (i = 0; i < req->count - 1; i++) {
+		for (n = i + 1; n < req->count; n++) {
+			if (req->ents[i].vol_id == req->ents[n].vol_id) {
+				ubi_err(ubi, "duplicated volume id %d",
+					req->ents[i].vol_id);
+				return -EINVAL;
+			}
+			if (!strcmp(req->ents[i].name, req->ents[n].name)) {
+				ubi_err(ubi, "duplicated volume name \"%s\"",
+					req->ents[i].name);
+				return -EINVAL;
+			}
+		}
+	}
+
+	/* Create the re-name list */
+	INIT_LIST_HEAD(&rename_list);
+	for (i = 0; i < req->count; i++) {
+		int vol_id = req->ents[i].vol_id;
+		int name_len = req->ents[i].name_len;
+		const char *name = req->ents[i].name;
+
+		re = kzalloc(sizeof(struct ubi_rename_entry), GFP_KERNEL);
+		if (!re) {
+			err = -ENOMEM;
+			goto out_free;
+		}
+
+		re->desc = ubi_open_volume(ubi->ubi_num, vol_id, UBI_METAONLY);
+		if (IS_ERR(re->desc)) {
+			err = PTR_ERR(re->desc);
+			ubi_err(ubi, "cannot open volume %d, error %d",
+				vol_id, err);
+			kfree(re);
+			goto out_free;
+		}
+
+		/* Skip this re-naming if the name does not really change */
+		if (re->desc->vol->name_len == name_len &&
+		    !memcmp(re->desc->vol->name, name, name_len)) {
+			ubi_close_volume(re->desc);
+			kfree(re);
+			continue;
+		}
+
+		re->new_name_len = name_len;
+		memcpy(re->new_name, name, name_len);
+		list_add_tail(&re->list, &rename_list);
+		dbg_gen("will rename volume %d from \"%s\" to \"%s\"",
+			vol_id, re->desc->vol->name, name);
+	}
+
+	if (list_empty(&rename_list))
+		return 0;
+
+	/* Find out the volumes which have to be removed */
+	list_for_each_entry(re, &rename_list, list) {
+		struct ubi_volume_desc *desc;
+		int no_remove_needed = 0;
+
+		/*
+		 * Volume @re->vol_id is going to be re-named to
+		 * @re->new_name, while its current name is @name. If a volume
+		 * with name @re->new_name currently exists, it has to be
+		 * removed, unless it is also re-named in the request (@req).
+		 */
+		list_for_each_entry(re1, &rename_list, list) {
+			if (re->new_name_len == re1->desc->vol->name_len &&
+			    !memcmp(re->new_name, re1->desc->vol->name,
+				    re1->desc->vol->name_len)) {
+				no_remove_needed = 1;
+				break;
+			}
+		}
+
+		if (no_remove_needed)
+			continue;
+
+		/*
+		 * It seems we need to remove volume with name @re->new_name,
+		 * if it exists.
+		 */
+		desc = ubi_open_volume_nm(ubi->ubi_num, re->new_name,
+					  UBI_EXCLUSIVE);
+		if (IS_ERR(desc)) {
+			err = PTR_ERR(desc);
+			if (err == -ENODEV)
+				/* Re-naming into a non-existing volume name */
+				continue;
+
+			/* The volume exists but busy, or an error occurred */
+			ubi_err(ubi, "cannot open volume \"%s\", error %d",
+				re->new_name, err);
+			goto out_free;
+		}
+
+		re1 = kzalloc(sizeof(struct ubi_rename_entry), GFP_KERNEL);
+		if (!re1) {
+			err = -ENOMEM;
+			ubi_close_volume(desc);
+			goto out_free;
+		}
+
+		re1->remove = 1;
+		re1->desc = desc;
+		list_add(&re1->list, &rename_list);
+		dbg_gen("will remove volume %d, name \"%s\"",
+			re1->desc->vol->vol_id, re1->desc->vol->name);
+	}
+
+	mutex_lock(&ubi->device_mutex);
+	err = ubi_rename_volumes(ubi, &rename_list);
+	mutex_unlock(&ubi->device_mutex);
+
+out_free:
+	list_for_each_entry_safe(re, re1, &rename_list, list) {
+		ubi_close_volume(re->desc);
+		list_del(&re->list);
+		kfree(re);
+	}
+	return err;
+}
+
+static long ubi_cdev_ioctl(struct file *file, unsigned int cmd,
+			   unsigned long arg)
+{
+	int err = 0;
+	struct ubi_device *ubi;
+	struct ubi_volume_desc *desc;
+	void __user *argp = (void __user *)arg;
+
+	if (!capable(CAP_SYS_RESOURCE))
+		return -EPERM;
+
+	ubi = ubi_get_by_major(imajor(file->f_mapping->host));
+	if (!ubi)
+		return -ENODEV;
+
+	switch (cmd) {
+	/* Create volume command */
+	case UBI_IOCMKVOL:
+	{
+		struct ubi_mkvol_req req;
+
+		dbg_gen("create volume");
+		err = copy_from_user(&req, argp, sizeof(struct ubi_mkvol_req));
+		if (err) {
+			err = -EFAULT;
+			break;
+		}
+
+		err = verify_mkvol_req(ubi, &req);
+		if (err)
+			break;
+
+		mutex_lock(&ubi->device_mutex);
+		err = ubi_create_volume(ubi, &req);
+		mutex_unlock(&ubi->device_mutex);
+		if (err)
+			break;
+
+		err = put_user(req.vol_id, (__user int32_t *)argp);
+		if (err)
+			err = -EFAULT;
+
+		break;
+	}
+
+	/* Remove volume command */
+	case UBI_IOCRMVOL:
+	{
+		int vol_id;
+
+		dbg_gen("remove volume");
+		err = get_user(vol_id, (__user int32_t *)argp);
+		if (err) {
+			err = -EFAULT;
+			break;
+		}
+
+		desc = ubi_open_volume(ubi->ubi_num, vol_id, UBI_EXCLUSIVE);
+		if (IS_ERR(desc)) {
+			err = PTR_ERR(desc);
+			break;
+		}
+
+		mutex_lock(&ubi->device_mutex);
+		err = ubi_remove_volume(desc, 0);
+		mutex_unlock(&ubi->device_mutex);
+
+		/*
+		 * The volume is deleted (unless an error occurred), and the
+		 * 'struct ubi_volume' object will be freed when
+		 * 'ubi_close_volume()' will call 'put_device()'.
+		 */
+		ubi_close_volume(desc);
+		break;
+	}
+
+	/* Re-size volume command */
+	case UBI_IOCRSVOL:
+	{
+		int pebs;
+		struct ubi_rsvol_req req;
+
+		dbg_gen("re-size volume");
+		err = copy_from_user(&req, argp, sizeof(struct ubi_rsvol_req));
+		if (err) {
+			err = -EFAULT;
+			break;
+		}
+
+		err = verify_rsvol_req(ubi, &req);
+		if (err)
+			break;
+
+		desc = ubi_open_volume(ubi->ubi_num, req.vol_id, UBI_EXCLUSIVE);
+		if (IS_ERR(desc)) {
+			err = PTR_ERR(desc);
+			break;
+		}
+
+		pebs = div_u64(req.bytes + desc->vol->usable_leb_size - 1,
+			       desc->vol->usable_leb_size);
+
+		mutex_lock(&ubi->device_mutex);
+		err = ubi_resize_volume(desc, pebs);
+		mutex_unlock(&ubi->device_mutex);
+		ubi_close_volume(desc);
+		break;
+	}
+
+	/* Re-name volumes command */
+	case UBI_IOCRNVOL:
+	{
+		struct ubi_rnvol_req *req;
+
+		dbg_gen("re-name volumes");
+		req = kmalloc(sizeof(struct ubi_rnvol_req), GFP_KERNEL);
+		if (!req) {
+			err = -ENOMEM;
+			break;
+		}
+
+		err = copy_from_user(req, argp, sizeof(struct ubi_rnvol_req));
+		if (err) {
+			err = -EFAULT;
+			kfree(req);
+			break;
+		}
+
+		err = rename_volumes(ubi, req);
+		kfree(req);
+		break;
+	}
+
+	/* Check a specific PEB for bitflips and scrub it if needed */
+	case UBI_IOCRPEB:
+	{
+		int pnum;
+
+		err = get_user(pnum, (__user int32_t *)argp);
+		if (err) {
+			err = -EFAULT;
+			break;
+		}
+
+		err = ubi_bitflip_check(ubi, pnum, 0);
+		break;
+	}
+
+	/* Force scrubbing for a specific PEB */
+	case UBI_IOCSPEB:
+	{
+		int pnum;
+
+		err = get_user(pnum, (__user int32_t *)argp);
+		if (err) {
+			err = -EFAULT;
+			break;
+		}
+
+		err = ubi_bitflip_check(ubi, pnum, 1);
+		break;
+	}
+
+	default:
+		err = -ENOTTY;
+		break;
+	}
+
+	ubi_put_device(ubi);
+	return err;
+}
+
+static long ctrl_cdev_ioctl(struct file *file, unsigned int cmd,
+			    unsigned long arg)
+{
+	int err = 0;
+	void __user *argp = (void __user *)arg;
+
+	if (!capable(CAP_SYS_RESOURCE))
+		return -EPERM;
+
+	switch (cmd) {
+	/* Attach an MTD device command */
+	case UBI_IOCATT:
+	{
+		struct ubi_attach_req req;
+		struct mtd_info *mtd;
+
+		dbg_gen("attach MTD device");
+		err = copy_from_user(&req, argp, sizeof(struct ubi_attach_req));
+		if (err) {
+			err = -EFAULT;
+			break;
+		}
+
+		if (req.mtd_num < 0 ||
+		    (req.ubi_num < 0 && req.ubi_num != UBI_DEV_NUM_AUTO)) {
+			err = -EINVAL;
+			break;
+		}
+
+		mtd = get_mtd_device(NULL, req.mtd_num);
+		if (IS_ERR(mtd)) {
+			err = PTR_ERR(mtd);
+			break;
+		}
+
+		/*
+		 * Note, further request verification is done by
+		 * 'ubi_attach_mtd_dev()'.
+		 */
+		mutex_lock(&ubi_devices_mutex);
+		err = ubi_attach_mtd_dev(mtd, req.ubi_num, req.vid_hdr_offset,
+					 req.max_beb_per1024, !!req.disable_fm);
+		mutex_unlock(&ubi_devices_mutex);
+		if (err < 0)
+			put_mtd_device(mtd);
+		else
+			/* @err contains UBI device number */
+			err = put_user(err, (__user int32_t *)argp);
+
+		break;
+	}
+
+	/* Detach an MTD device command */
+	case UBI_IOCDET:
+	{
+		int ubi_num;
+
+		dbg_gen("detach MTD device");
+		err = get_user(ubi_num, (__user int32_t *)argp);
+		if (err) {
+			err = -EFAULT;
+			break;
+		}
+
+		mutex_lock(&ubi_devices_mutex);
+		err = ubi_detach_mtd_dev(ubi_num, 0);
+		mutex_unlock(&ubi_devices_mutex);
+		break;
+	}
+
+	default:
+		err = -ENOTTY;
+		break;
+	}
+
+	return err;
+}
+
+/* UBI volume character device operations */
+const struct file_operations ubi_vol_cdev_operations = {
+	.owner          = THIS_MODULE,
+	.open           = vol_cdev_open,
+	.release        = vol_cdev_release,
+	.llseek         = vol_cdev_llseek,
+	.read           = vol_cdev_read,
+	.write          = vol_cdev_write,
+	.fsync		= vol_cdev_fsync,
+	.unlocked_ioctl = vol_cdev_ioctl,
+	.compat_ioctl   = compat_ptr_ioctl,
+};
+
+/* UBI character device operations */
+const struct file_operations ubi_cdev_operations = {
+	.owner          = THIS_MODULE,
+	.llseek         = no_llseek,
+	.unlocked_ioctl = ubi_cdev_ioctl,
+	.compat_ioctl   = compat_ptr_ioctl,
+};
+
+/* UBI control character device operations */
+const struct file_operations ubi_ctrl_cdev_operations = {
+	.owner          = THIS_MODULE,
+	.unlocked_ioctl = ctrl_cdev_ioctl,
+	.compat_ioctl   = compat_ptr_ioctl,
+	.llseek		= no_llseek,
+};
diff --git a/drivers/mtd/ubi/debug.c b/drivers/mtd/ubi/debug.c
new file mode 100644
index 0000000000..27168f511d
--- /dev/null
+++ b/drivers/mtd/ubi/debug.c
@@ -0,0 +1,606 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+#include "ubi.h"
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+#include <linux/module.h>
+#include <linux/seq_file.h>
+
+
+/**
+ * ubi_dump_flash - dump a region of flash.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to dump
+ * @offset: the starting offset within the physical eraseblock to dump
+ * @len: the length of the region to dump
+ */
+void ubi_dump_flash(struct ubi_device *ubi, int pnum, int offset, int len)
+{
+	int err;
+	size_t read;
+	void *buf;
+	loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
+
+	buf = vmalloc(len);
+	if (!buf)
+		return;
+	err = mtd_read(ubi->mtd, addr, len, &read, buf);
+	if (err && err != -EUCLEAN) {
+		ubi_err(ubi, "err %d while reading %d bytes from PEB %d:%d, read %zd bytes",
+			err, len, pnum, offset, read);
+		goto out;
+	}
+
+	ubi_msg(ubi, "dumping %d bytes of data from PEB %d, offset %d",
+		len, pnum, offset);
+	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1, buf, len, 1);
+out:
+	vfree(buf);
+	return;
+}
+
+/**
+ * ubi_dump_ec_hdr - dump an erase counter header.
+ * @ec_hdr: the erase counter header to dump
+ */
+void ubi_dump_ec_hdr(const struct ubi_ec_hdr *ec_hdr)
+{
+	pr_err("Erase counter header dump:\n");
+	pr_err("\tmagic          %#08x\n", be32_to_cpu(ec_hdr->magic));
+	pr_err("\tversion        %d\n", (int)ec_hdr->version);
+	pr_err("\tec             %llu\n", (long long)be64_to_cpu(ec_hdr->ec));
+	pr_err("\tvid_hdr_offset %d\n", be32_to_cpu(ec_hdr->vid_hdr_offset));
+	pr_err("\tdata_offset    %d\n", be32_to_cpu(ec_hdr->data_offset));
+	pr_err("\timage_seq      %d\n", be32_to_cpu(ec_hdr->image_seq));
+	pr_err("\thdr_crc        %#08x\n", be32_to_cpu(ec_hdr->hdr_crc));
+	pr_err("erase counter header hexdump:\n");
+	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
+		       ec_hdr, UBI_EC_HDR_SIZE, 1);
+}
+
+/**
+ * ubi_dump_vid_hdr - dump a volume identifier header.
+ * @vid_hdr: the volume identifier header to dump
+ */
+void ubi_dump_vid_hdr(const struct ubi_vid_hdr *vid_hdr)
+{
+	pr_err("Volume identifier header dump:\n");
+	pr_err("\tmagic     %08x\n", be32_to_cpu(vid_hdr->magic));
+	pr_err("\tversion   %d\n",  (int)vid_hdr->version);
+	pr_err("\tvol_type  %d\n",  (int)vid_hdr->vol_type);
+	pr_err("\tcopy_flag %d\n",  (int)vid_hdr->copy_flag);
+	pr_err("\tcompat    %d\n",  (int)vid_hdr->compat);
+	pr_err("\tvol_id    %d\n",  be32_to_cpu(vid_hdr->vol_id));
+	pr_err("\tlnum      %d\n",  be32_to_cpu(vid_hdr->lnum));
+	pr_err("\tdata_size %d\n",  be32_to_cpu(vid_hdr->data_size));
+	pr_err("\tused_ebs  %d\n",  be32_to_cpu(vid_hdr->used_ebs));
+	pr_err("\tdata_pad  %d\n",  be32_to_cpu(vid_hdr->data_pad));
+	pr_err("\tsqnum     %llu\n",
+		(unsigned long long)be64_to_cpu(vid_hdr->sqnum));
+	pr_err("\thdr_crc   %08x\n", be32_to_cpu(vid_hdr->hdr_crc));
+	pr_err("Volume identifier header hexdump:\n");
+	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
+		       vid_hdr, UBI_VID_HDR_SIZE, 1);
+}
+
+/**
+ * ubi_dump_vol_info - dump volume information.
+ * @vol: UBI volume description object
+ */
+void ubi_dump_vol_info(const struct ubi_volume *vol)
+{
+	pr_err("Volume information dump:\n");
+	pr_err("\tvol_id          %d\n", vol->vol_id);
+	pr_err("\treserved_pebs   %d\n", vol->reserved_pebs);
+	pr_err("\talignment       %d\n", vol->alignment);
+	pr_err("\tdata_pad        %d\n", vol->data_pad);
+	pr_err("\tvol_type        %d\n", vol->vol_type);
+	pr_err("\tname_len        %d\n", vol->name_len);
+	pr_err("\tusable_leb_size %d\n", vol->usable_leb_size);
+	pr_err("\tused_ebs        %d\n", vol->used_ebs);
+	pr_err("\tused_bytes      %lld\n", vol->used_bytes);
+	pr_err("\tlast_eb_bytes   %d\n", vol->last_eb_bytes);
+	pr_err("\tcorrupted       %d\n", vol->corrupted);
+	pr_err("\tupd_marker      %d\n", vol->upd_marker);
+	pr_err("\tskip_check      %d\n", vol->skip_check);
+
+	if (vol->name_len <= UBI_VOL_NAME_MAX &&
+	    strnlen(vol->name, vol->name_len + 1) == vol->name_len) {
+		pr_err("\tname            %s\n", vol->name);
+	} else {
+		pr_err("\t1st 5 characters of name: %c%c%c%c%c\n",
+		       vol->name[0], vol->name[1], vol->name[2],
+		       vol->name[3], vol->name[4]);
+	}
+}
+
+/**
+ * ubi_dump_vtbl_record - dump a &struct ubi_vtbl_record object.
+ * @r: the object to dump
+ * @idx: volume table index
+ */
+void ubi_dump_vtbl_record(const struct ubi_vtbl_record *r, int idx)
+{
+	int name_len = be16_to_cpu(r->name_len);
+
+	pr_err("Volume table record %d dump:\n", idx);
+	pr_err("\treserved_pebs   %d\n", be32_to_cpu(r->reserved_pebs));
+	pr_err("\talignment       %d\n", be32_to_cpu(r->alignment));
+	pr_err("\tdata_pad        %d\n", be32_to_cpu(r->data_pad));
+	pr_err("\tvol_type        %d\n", (int)r->vol_type);
+	pr_err("\tupd_marker      %d\n", (int)r->upd_marker);
+	pr_err("\tname_len        %d\n", name_len);
+
+	if (r->name[0] == '\0') {
+		pr_err("\tname            NULL\n");
+		return;
+	}
+
+	if (name_len <= UBI_VOL_NAME_MAX &&
+	    strnlen(&r->name[0], name_len + 1) == name_len) {
+		pr_err("\tname            %s\n", &r->name[0]);
+	} else {
+		pr_err("\t1st 5 characters of name: %c%c%c%c%c\n",
+			r->name[0], r->name[1], r->name[2], r->name[3],
+			r->name[4]);
+	}
+	pr_err("\tcrc             %#08x\n", be32_to_cpu(r->crc));
+}
+
+/**
+ * ubi_dump_av - dump a &struct ubi_ainf_volume object.
+ * @av: the object to dump
+ */
+void ubi_dump_av(const struct ubi_ainf_volume *av)
+{
+	pr_err("Volume attaching information dump:\n");
+	pr_err("\tvol_id         %d\n", av->vol_id);
+	pr_err("\thighest_lnum   %d\n", av->highest_lnum);
+	pr_err("\tleb_count      %d\n", av->leb_count);
+	pr_err("\tcompat         %d\n", av->compat);
+	pr_err("\tvol_type       %d\n", av->vol_type);
+	pr_err("\tused_ebs       %d\n", av->used_ebs);
+	pr_err("\tlast_data_size %d\n", av->last_data_size);
+	pr_err("\tdata_pad       %d\n", av->data_pad);
+}
+
+/**
+ * ubi_dump_aeb - dump a &struct ubi_ainf_peb object.
+ * @aeb: the object to dump
+ * @type: object type: 0 - not corrupted, 1 - corrupted
+ */
+void ubi_dump_aeb(const struct ubi_ainf_peb *aeb, int type)
+{
+	pr_err("eraseblock attaching information dump:\n");
+	pr_err("\tec       %d\n", aeb->ec);
+	pr_err("\tpnum     %d\n", aeb->pnum);
+	if (type == 0) {
+		pr_err("\tlnum     %d\n", aeb->lnum);
+		pr_err("\tscrub    %d\n", aeb->scrub);
+		pr_err("\tsqnum    %llu\n", aeb->sqnum);
+	}
+}
+
+/**
+ * ubi_dump_mkvol_req - dump a &struct ubi_mkvol_req object.
+ * @req: the object to dump
+ */
+void ubi_dump_mkvol_req(const struct ubi_mkvol_req *req)
+{
+	char nm[17];
+
+	pr_err("Volume creation request dump:\n");
+	pr_err("\tvol_id    %d\n",   req->vol_id);
+	pr_err("\talignment %d\n",   req->alignment);
+	pr_err("\tbytes     %lld\n", (long long)req->bytes);
+	pr_err("\tvol_type  %d\n",   req->vol_type);
+	pr_err("\tname_len  %d\n",   req->name_len);
+
+	memcpy(nm, req->name, 16);
+	nm[16] = 0;
+	pr_err("\t1st 16 characters of name: %s\n", nm);
+}
+
+/*
+ * Root directory for UBI stuff in debugfs. Contains sub-directories which
+ * contain the stuff specific to particular UBI devices.
+ */
+static struct dentry *dfs_rootdir;
+
+/**
+ * ubi_debugfs_init - create UBI debugfs directory.
+ *
+ * Create UBI debugfs directory. Returns zero in case of success and a negative
+ * error code in case of failure.
+ */
+int ubi_debugfs_init(void)
+{
+	if (!IS_ENABLED(CONFIG_DEBUG_FS))
+		return 0;
+
+	dfs_rootdir = debugfs_create_dir("ubi", NULL);
+	if (IS_ERR_OR_NULL(dfs_rootdir)) {
+		int err = dfs_rootdir ? PTR_ERR(dfs_rootdir) : -ENODEV;
+
+		pr_err("UBI error: cannot create \"ubi\" debugfs directory, error %d\n",
+		       err);
+		return err;
+	}
+
+	return 0;
+}
+
+/**
+ * ubi_debugfs_exit - remove UBI debugfs directory.
+ */
+void ubi_debugfs_exit(void)
+{
+	if (IS_ENABLED(CONFIG_DEBUG_FS))
+		debugfs_remove(dfs_rootdir);
+}
+
+/* Read an UBI debugfs file */
+static ssize_t dfs_file_read(struct file *file, char __user *user_buf,
+			     size_t count, loff_t *ppos)
+{
+	unsigned long ubi_num = (unsigned long)file->private_data;
+	struct dentry *dent = file->f_path.dentry;
+	struct ubi_device *ubi;
+	struct ubi_debug_info *d;
+	char buf[8];
+	int val;
+
+	ubi = ubi_get_device(ubi_num);
+	if (!ubi)
+		return -ENODEV;
+	d = &ubi->dbg;
+
+	if (dent == d->dfs_chk_gen)
+		val = d->chk_gen;
+	else if (dent == d->dfs_chk_io)
+		val = d->chk_io;
+	else if (dent == d->dfs_chk_fastmap)
+		val = d->chk_fastmap;
+	else if (dent == d->dfs_disable_bgt)
+		val = d->disable_bgt;
+	else if (dent == d->dfs_emulate_bitflips)
+		val = d->emulate_bitflips;
+	else if (dent == d->dfs_emulate_io_failures)
+		val = d->emulate_io_failures;
+	else if (dent == d->dfs_emulate_power_cut) {
+		snprintf(buf, sizeof(buf), "%u\n", d->emulate_power_cut);
+		count = simple_read_from_buffer(user_buf, count, ppos,
+						buf, strlen(buf));
+		goto out;
+	} else if (dent == d->dfs_power_cut_min) {
+		snprintf(buf, sizeof(buf), "%u\n", d->power_cut_min);
+		count = simple_read_from_buffer(user_buf, count, ppos,
+						buf, strlen(buf));
+		goto out;
+	} else if (dent == d->dfs_power_cut_max) {
+		snprintf(buf, sizeof(buf), "%u\n", d->power_cut_max);
+		count = simple_read_from_buffer(user_buf, count, ppos,
+						buf, strlen(buf));
+		goto out;
+	}
+	else {
+		count = -EINVAL;
+		goto out;
+	}
+
+	if (val)
+		buf[0] = '1';
+	else
+		buf[0] = '0';
+	buf[1] = '\n';
+	buf[2] = 0x00;
+
+	count = simple_read_from_buffer(user_buf, count, ppos, buf, 2);
+
+out:
+	ubi_put_device(ubi);
+	return count;
+}
+
+/* Write an UBI debugfs file */
+static ssize_t dfs_file_write(struct file *file, const char __user *user_buf,
+			      size_t count, loff_t *ppos)
+{
+	unsigned long ubi_num = (unsigned long)file->private_data;
+	struct dentry *dent = file->f_path.dentry;
+	struct ubi_device *ubi;
+	struct ubi_debug_info *d;
+	size_t buf_size;
+	char buf[8] = {0};
+	int val;
+
+	ubi = ubi_get_device(ubi_num);
+	if (!ubi)
+		return -ENODEV;
+	d = &ubi->dbg;
+
+	buf_size = min_t(size_t, count, (sizeof(buf) - 1));
+	if (copy_from_user(buf, user_buf, buf_size)) {
+		count = -EFAULT;
+		goto out;
+	}
+
+	if (dent == d->dfs_power_cut_min) {
+		if (kstrtouint(buf, 0, &d->power_cut_min) != 0)
+			count = -EINVAL;
+		goto out;
+	} else if (dent == d->dfs_power_cut_max) {
+		if (kstrtouint(buf, 0, &d->power_cut_max) != 0)
+			count = -EINVAL;
+		goto out;
+	} else if (dent == d->dfs_emulate_power_cut) {
+		if (kstrtoint(buf, 0, &val) != 0)
+			count = -EINVAL;
+		else
+			d->emulate_power_cut = val;
+		goto out;
+	}
+
+	if (buf[0] == '1')
+		val = 1;
+	else if (buf[0] == '0')
+		val = 0;
+	else {
+		count = -EINVAL;
+		goto out;
+	}
+
+	if (dent == d->dfs_chk_gen)
+		d->chk_gen = val;
+	else if (dent == d->dfs_chk_io)
+		d->chk_io = val;
+	else if (dent == d->dfs_chk_fastmap)
+		d->chk_fastmap = val;
+	else if (dent == d->dfs_disable_bgt)
+		d->disable_bgt = val;
+	else if (dent == d->dfs_emulate_bitflips)
+		d->emulate_bitflips = val;
+	else if (dent == d->dfs_emulate_io_failures)
+		d->emulate_io_failures = val;
+	else
+		count = -EINVAL;
+
+out:
+	ubi_put_device(ubi);
+	return count;
+}
+
+/* File operations for all UBI debugfs files except
+ * detailed_erase_block_info
+ */
+static const struct file_operations dfs_fops = {
+	.read   = dfs_file_read,
+	.write  = dfs_file_write,
+	.open	= simple_open,
+	.llseek = no_llseek,
+	.owner  = THIS_MODULE,
+};
+
+/* As long as the position is less then that total number of erase blocks,
+ * we still have more to print.
+ */
+static void *eraseblk_count_seq_start(struct seq_file *s, loff_t *pos)
+{
+	struct ubi_device *ubi = s->private;
+
+	if (*pos < ubi->peb_count)
+		return pos;
+
+	return NULL;
+}
+
+/* Since we are using the position as the iterator, we just need to check if we
+ * are done and increment the position.
+ */
+static void *eraseblk_count_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+	struct ubi_device *ubi = s->private;
+
+	(*pos)++;
+
+	if (*pos < ubi->peb_count)
+		return pos;
+
+	return NULL;
+}
+
+static void eraseblk_count_seq_stop(struct seq_file *s, void *v)
+{
+}
+
+static int eraseblk_count_seq_show(struct seq_file *s, void *iter)
+{
+	struct ubi_device *ubi = s->private;
+	struct ubi_wl_entry *wl;
+	int *block_number = iter;
+	int erase_count = -1;
+	int err;
+
+	/* If this is the start, print a header */
+	if (*block_number == 0)
+		seq_puts(s, "physical_block_number\terase_count\n");
+
+	err = ubi_io_is_bad(ubi, *block_number);
+	if (err)
+		return err;
+
+	spin_lock(&ubi->wl_lock);
+
+	wl = ubi->lookuptbl[*block_number];
+	if (wl)
+		erase_count = wl->ec;
+
+	spin_unlock(&ubi->wl_lock);
+
+	if (erase_count < 0)
+		return 0;
+
+	seq_printf(s, "%-22d\t%-11d\n", *block_number, erase_count);
+
+	return 0;
+}
+
+static const struct seq_operations eraseblk_count_seq_ops = {
+	.start = eraseblk_count_seq_start,
+	.next = eraseblk_count_seq_next,
+	.stop = eraseblk_count_seq_stop,
+	.show = eraseblk_count_seq_show
+};
+
+static int eraseblk_count_open(struct inode *inode, struct file *f)
+{
+	struct seq_file *s;
+	int err;
+
+	err = seq_open(f, &eraseblk_count_seq_ops);
+	if (err)
+		return err;
+
+	s = f->private_data;
+	s->private = ubi_get_device((unsigned long)inode->i_private);
+
+	if (!s->private)
+		return -ENODEV;
+	else
+		return 0;
+}
+
+static int eraseblk_count_release(struct inode *inode, struct file *f)
+{
+	struct seq_file *s = f->private_data;
+	struct ubi_device *ubi = s->private;
+
+	ubi_put_device(ubi);
+
+	return seq_release(inode, f);
+}
+
+static const struct file_operations eraseblk_count_fops = {
+	.owner = THIS_MODULE,
+	.open = eraseblk_count_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = eraseblk_count_release,
+};
+
+/**
+ * ubi_debugfs_init_dev - initialize debugfs for an UBI device.
+ * @ubi: UBI device description object
+ *
+ * This function creates all debugfs files for UBI device @ubi. Returns zero in
+ * case of success and a negative error code in case of failure.
+ */
+int ubi_debugfs_init_dev(struct ubi_device *ubi)
+{
+	unsigned long ubi_num = ubi->ubi_num;
+	struct ubi_debug_info *d = &ubi->dbg;
+	umode_t mode = S_IRUSR | S_IWUSR;
+	int n;
+
+	if (!IS_ENABLED(CONFIG_DEBUG_FS))
+		return 0;
+
+	n = snprintf(d->dfs_dir_name, UBI_DFS_DIR_LEN + 1, UBI_DFS_DIR_NAME,
+		     ubi->ubi_num);
+	if (n > UBI_DFS_DIR_LEN) {
+		/* The array size is too small */
+		return -EINVAL;
+	}
+
+	d->dfs_dir = debugfs_create_dir(d->dfs_dir_name, dfs_rootdir);
+
+	d->dfs_chk_gen = debugfs_create_file("chk_gen", mode, d->dfs_dir,
+					     (void *)ubi_num, &dfs_fops);
+
+	d->dfs_chk_io = debugfs_create_file("chk_io", mode, d->dfs_dir,
+					    (void *)ubi_num, &dfs_fops);
+
+	d->dfs_chk_fastmap = debugfs_create_file("chk_fastmap", mode,
+						 d->dfs_dir, (void *)ubi_num,
+						 &dfs_fops);
+
+	d->dfs_disable_bgt = debugfs_create_file("tst_disable_bgt", mode,
+						 d->dfs_dir, (void *)ubi_num,
+						 &dfs_fops);
+
+	d->dfs_emulate_bitflips = debugfs_create_file("tst_emulate_bitflips",
+						      mode, d->dfs_dir,
+						      (void *)ubi_num,
+						      &dfs_fops);
+
+	d->dfs_emulate_io_failures = debugfs_create_file("tst_emulate_io_failures",
+							 mode, d->dfs_dir,
+							 (void *)ubi_num,
+							 &dfs_fops);
+
+	d->dfs_emulate_power_cut = debugfs_create_file("tst_emulate_power_cut",
+						       mode, d->dfs_dir,
+						       (void *)ubi_num,
+						       &dfs_fops);
+
+	d->dfs_power_cut_min = debugfs_create_file("tst_emulate_power_cut_min",
+						   mode, d->dfs_dir,
+						   (void *)ubi_num, &dfs_fops);
+
+	d->dfs_power_cut_max = debugfs_create_file("tst_emulate_power_cut_max",
+						   mode, d->dfs_dir,
+						   (void *)ubi_num, &dfs_fops);
+
+	debugfs_create_file("detailed_erase_block_info", S_IRUSR, d->dfs_dir,
+			    (void *)ubi_num, &eraseblk_count_fops);
+
+	return 0;
+}
+
+/**
+ * ubi_debugfs_exit_dev - free all debugfs files corresponding to device @ubi
+ * @ubi: UBI device description object
+ */
+void ubi_debugfs_exit_dev(struct ubi_device *ubi)
+{
+	if (IS_ENABLED(CONFIG_DEBUG_FS))
+		debugfs_remove_recursive(ubi->dbg.dfs_dir);
+}
+
+/**
+ * ubi_dbg_power_cut - emulate a power cut if it is time to do so
+ * @ubi: UBI device description object
+ * @caller: Flags set to indicate from where the function is being called
+ *
+ * Returns non-zero if a power cut was emulated, zero if not.
+ */
+int ubi_dbg_power_cut(struct ubi_device *ubi, int caller)
+{
+	unsigned int range;
+
+	if ((ubi->dbg.emulate_power_cut & caller) == 0)
+		return 0;
+
+	if (ubi->dbg.power_cut_counter == 0) {
+		ubi->dbg.power_cut_counter = ubi->dbg.power_cut_min;
+
+		if (ubi->dbg.power_cut_max > ubi->dbg.power_cut_min) {
+			range = ubi->dbg.power_cut_max - ubi->dbg.power_cut_min;
+			ubi->dbg.power_cut_counter += get_random_u32_below(range);
+		}
+		return 0;
+	}
+
+	ubi->dbg.power_cut_counter--;
+	if (ubi->dbg.power_cut_counter)
+		return 0;
+
+	ubi_msg(ubi, "XXXXXXXXXXXXXXX emulating a power cut XXXXXXXXXXXXXXXX");
+	ubi_ro_mode(ubi);
+	return 1;
+}
diff --git a/drivers/mtd/ubi/debug.h b/drivers/mtd/ubi/debug.h
new file mode 100644
index 0000000000..23676f32b6
--- /dev/null
+++ b/drivers/mtd/ubi/debug.h
@@ -0,0 +1,129 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+#ifndef __UBI_DEBUG_H__
+#define __UBI_DEBUG_H__
+
+void ubi_dump_flash(struct ubi_device *ubi, int pnum, int offset, int len);
+void ubi_dump_ec_hdr(const struct ubi_ec_hdr *ec_hdr);
+void ubi_dump_vid_hdr(const struct ubi_vid_hdr *vid_hdr);
+
+#include <linux/random.h>
+
+#define ubi_assert(expr)  do {                                               \
+	if (unlikely(!(expr))) {                                             \
+		pr_crit("UBI assert failed in %s at %u (pid %d)\n",          \
+		       __func__, __LINE__, current->pid);                    \
+		dump_stack();                                                \
+	}                                                                    \
+} while (0)
+
+#define ubi_dbg_print_hex_dump(l, ps, pt, r, g, b, len, a)                   \
+		print_hex_dump(l, ps, pt, r, g, b, len, a)
+
+#define ubi_dbg_msg(type, fmt, ...) \
+	pr_debug("UBI DBG " type " (pid %d): " fmt "\n", current->pid,       \
+		 ##__VA_ARGS__)
+
+/* General debugging messages */
+#define dbg_gen(fmt, ...) ubi_dbg_msg("gen", fmt, ##__VA_ARGS__)
+/* Messages from the eraseblock association sub-system */
+#define dbg_eba(fmt, ...) ubi_dbg_msg("eba", fmt, ##__VA_ARGS__)
+/* Messages from the wear-leveling sub-system */
+#define dbg_wl(fmt, ...)  ubi_dbg_msg("wl", fmt, ##__VA_ARGS__)
+/* Messages from the input/output sub-system */
+#define dbg_io(fmt, ...)  ubi_dbg_msg("io", fmt, ##__VA_ARGS__)
+/* Initialization and build messages */
+#define dbg_bld(fmt, ...) ubi_dbg_msg("bld", fmt, ##__VA_ARGS__)
+
+void ubi_dump_vol_info(const struct ubi_volume *vol);
+void ubi_dump_vtbl_record(const struct ubi_vtbl_record *r, int idx);
+void ubi_dump_av(const struct ubi_ainf_volume *av);
+void ubi_dump_aeb(const struct ubi_ainf_peb *aeb, int type);
+void ubi_dump_mkvol_req(const struct ubi_mkvol_req *req);
+int ubi_self_check_all_ff(struct ubi_device *ubi, int pnum, int offset,
+			  int len);
+int ubi_debugfs_init(void);
+void ubi_debugfs_exit(void);
+int ubi_debugfs_init_dev(struct ubi_device *ubi);
+void ubi_debugfs_exit_dev(struct ubi_device *ubi);
+
+/**
+ * ubi_dbg_is_bgt_disabled - if the background thread is disabled.
+ * @ubi: UBI device description object
+ *
+ * Returns non-zero if the UBI background thread is disabled for testing
+ * purposes.
+ */
+static inline int ubi_dbg_is_bgt_disabled(const struct ubi_device *ubi)
+{
+	return ubi->dbg.disable_bgt;
+}
+
+/**
+ * ubi_dbg_is_bitflip - if it is time to emulate a bit-flip.
+ * @ubi: UBI device description object
+ *
+ * Returns non-zero if a bit-flip should be emulated, otherwise returns zero.
+ */
+static inline int ubi_dbg_is_bitflip(const struct ubi_device *ubi)
+{
+	if (ubi->dbg.emulate_bitflips)
+		return !get_random_u32_below(200);
+	return 0;
+}
+
+/**
+ * ubi_dbg_is_write_failure - if it is time to emulate a write failure.
+ * @ubi: UBI device description object
+ *
+ * Returns non-zero if a write failure should be emulated, otherwise returns
+ * zero.
+ */
+static inline int ubi_dbg_is_write_failure(const struct ubi_device *ubi)
+{
+	if (ubi->dbg.emulate_io_failures)
+		return !get_random_u32_below(500);
+	return 0;
+}
+
+/**
+ * ubi_dbg_is_erase_failure - if its time to emulate an erase failure.
+ * @ubi: UBI device description object
+ *
+ * Returns non-zero if an erase failure should be emulated, otherwise returns
+ * zero.
+ */
+static inline int ubi_dbg_is_erase_failure(const struct ubi_device *ubi)
+{
+	if (ubi->dbg.emulate_io_failures)
+		return !get_random_u32_below(400);
+	return 0;
+}
+
+static inline int ubi_dbg_chk_io(const struct ubi_device *ubi)
+{
+	return ubi->dbg.chk_io;
+}
+
+static inline int ubi_dbg_chk_gen(const struct ubi_device *ubi)
+{
+	return ubi->dbg.chk_gen;
+}
+
+static inline int ubi_dbg_chk_fastmap(const struct ubi_device *ubi)
+{
+	return ubi->dbg.chk_fastmap;
+}
+
+static inline void ubi_enable_dbg_chk_fastmap(struct ubi_device *ubi)
+{
+	ubi->dbg.chk_fastmap = 1;
+}
+
+int ubi_dbg_power_cut(struct ubi_device *ubi, int caller);
+#endif /* !__UBI_DEBUG_H__ */
diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
new file mode 100644
index 0000000000..655ff41863
--- /dev/null
+++ b/drivers/mtd/ubi/eba.c
@@ -0,0 +1,1709 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+/*
+ * The UBI Eraseblock Association (EBA) sub-system.
+ *
+ * This sub-system is responsible for I/O to/from logical eraseblock.
+ *
+ * Although in this implementation the EBA table is fully kept and managed in
+ * RAM, which assumes poor scalability, it might be (partially) maintained on
+ * flash in future implementations.
+ *
+ * The EBA sub-system implements per-logical eraseblock locking. Before
+ * accessing a logical eraseblock it is locked for reading or writing. The
+ * per-logical eraseblock locking is implemented by means of the lock tree. The
+ * lock tree is an RB-tree which refers all the currently locked logical
+ * eraseblocks. The lock tree elements are &struct ubi_ltree_entry objects.
+ * They are indexed by (@vol_id, @lnum) pairs.
+ *
+ * EBA also maintains the global sequence counter which is incremented each
+ * time a logical eraseblock is mapped to a physical eraseblock and it is
+ * stored in the volume identifier header. This means that each VID header has
+ * a unique sequence number. The sequence number is only increased an we assume
+ * 64 bits is enough to never overflow.
+ */
+
+#include <linux/slab.h>
+#include <linux/crc32.h>
+#include <linux/err.h>
+#include "ubi.h"
+
+/* Number of physical eraseblocks reserved for atomic LEB change operation */
+#define EBA_RESERVED_PEBS 1
+
+/**
+ * struct ubi_eba_entry - structure encoding a single LEB -> PEB association
+ * @pnum: the physical eraseblock number attached to the LEB
+ *
+ * This structure is encoding a LEB -> PEB association. Note that the LEB
+ * number is not stored here, because it is the index used to access the
+ * entries table.
+ */
+struct ubi_eba_entry {
+	int pnum;
+};
+
+/**
+ * struct ubi_eba_table - LEB -> PEB association information
+ * @entries: the LEB to PEB mapping (one entry per LEB).
+ *
+ * This structure is private to the EBA logic and should be kept here.
+ * It is encoding the LEB to PEB association table, and is subject to
+ * changes.
+ */
+struct ubi_eba_table {
+	struct ubi_eba_entry *entries;
+};
+
+/**
+ * ubi_next_sqnum - get next sequence number.
+ * @ubi: UBI device description object
+ *
+ * This function returns next sequence number to use, which is just the current
+ * global sequence counter value. It also increases the global sequence
+ * counter.
+ */
+unsigned long long ubi_next_sqnum(struct ubi_device *ubi)
+{
+	unsigned long long sqnum;
+
+	spin_lock(&ubi->ltree_lock);
+	sqnum = ubi->global_sqnum++;
+	spin_unlock(&ubi->ltree_lock);
+
+	return sqnum;
+}
+
+/**
+ * ubi_get_compat - get compatibility flags of a volume.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ *
+ * This function returns compatibility flags for an internal volume. User
+ * volumes have no compatibility flags, so %0 is returned.
+ */
+static int ubi_get_compat(const struct ubi_device *ubi, int vol_id)
+{
+	if (vol_id == UBI_LAYOUT_VOLUME_ID)
+		return UBI_LAYOUT_VOLUME_COMPAT;
+	return 0;
+}
+
+/**
+ * ubi_eba_get_ldesc - get information about a LEB
+ * @vol: volume description object
+ * @lnum: logical eraseblock number
+ * @ldesc: the LEB descriptor to fill
+ *
+ * Used to query information about a specific LEB.
+ * It is currently only returning the physical position of the LEB, but will be
+ * extended to provide more information.
+ */
+void ubi_eba_get_ldesc(struct ubi_volume *vol, int lnum,
+		       struct ubi_eba_leb_desc *ldesc)
+{
+	ldesc->lnum = lnum;
+	ldesc->pnum = vol->eba_tbl->entries[lnum].pnum;
+}
+
+/**
+ * ubi_eba_create_table - allocate a new EBA table and initialize it with all
+ *			  LEBs unmapped
+ * @vol: volume containing the EBA table to copy
+ * @nentries: number of entries in the table
+ *
+ * Allocate a new EBA table and initialize it with all LEBs unmapped.
+ * Returns a valid pointer if it succeed, an ERR_PTR() otherwise.
+ */
+struct ubi_eba_table *ubi_eba_create_table(struct ubi_volume *vol,
+					   int nentries)
+{
+	struct ubi_eba_table *tbl;
+	int err = -ENOMEM;
+	int i;
+
+	tbl = kzalloc(sizeof(*tbl), GFP_KERNEL);
+	if (!tbl)
+		return ERR_PTR(-ENOMEM);
+
+	tbl->entries = kmalloc_array(nentries, sizeof(*tbl->entries),
+				     GFP_KERNEL);
+	if (!tbl->entries)
+		goto err;
+
+	for (i = 0; i < nentries; i++)
+		tbl->entries[i].pnum = UBI_LEB_UNMAPPED;
+
+	return tbl;
+
+err:
+	kfree(tbl);
+
+	return ERR_PTR(err);
+}
+
+/**
+ * ubi_eba_destroy_table - destroy an EBA table
+ * @tbl: the table to destroy
+ *
+ * Destroy an EBA table.
+ */
+void ubi_eba_destroy_table(struct ubi_eba_table *tbl)
+{
+	if (!tbl)
+		return;
+
+	kfree(tbl->entries);
+	kfree(tbl);
+}
+
+/**
+ * ubi_eba_copy_table - copy the EBA table attached to vol into another table
+ * @vol: volume containing the EBA table to copy
+ * @dst: destination
+ * @nentries: number of entries to copy
+ *
+ * Copy the EBA table stored in vol into the one pointed by dst.
+ */
+void ubi_eba_copy_table(struct ubi_volume *vol, struct ubi_eba_table *dst,
+			int nentries)
+{
+	struct ubi_eba_table *src;
+	int i;
+
+	ubi_assert(dst && vol && vol->eba_tbl);
+
+	src = vol->eba_tbl;
+
+	for (i = 0; i < nentries; i++)
+		dst->entries[i].pnum = src->entries[i].pnum;
+}
+
+/**
+ * ubi_eba_replace_table - assign a new EBA table to a volume
+ * @vol: volume containing the EBA table to copy
+ * @tbl: new EBA table
+ *
+ * Assign a new EBA table to the volume and release the old one.
+ */
+void ubi_eba_replace_table(struct ubi_volume *vol, struct ubi_eba_table *tbl)
+{
+	ubi_eba_destroy_table(vol->eba_tbl);
+	vol->eba_tbl = tbl;
+}
+
+/**
+ * ltree_lookup - look up the lock tree.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ *
+ * This function returns a pointer to the corresponding &struct ubi_ltree_entry
+ * object if the logical eraseblock is locked and %NULL if it is not.
+ * @ubi->ltree_lock has to be locked.
+ */
+static struct ubi_ltree_entry *ltree_lookup(struct ubi_device *ubi, int vol_id,
+					    int lnum)
+{
+	struct rb_node *p;
+
+	p = ubi->ltree.rb_node;
+	while (p) {
+		struct ubi_ltree_entry *le;
+
+		le = rb_entry(p, struct ubi_ltree_entry, rb);
+
+		if (vol_id < le->vol_id)
+			p = p->rb_left;
+		else if (vol_id > le->vol_id)
+			p = p->rb_right;
+		else {
+			if (lnum < le->lnum)
+				p = p->rb_left;
+			else if (lnum > le->lnum)
+				p = p->rb_right;
+			else
+				return le;
+		}
+	}
+
+	return NULL;
+}
+
+/**
+ * ltree_add_entry - add new entry to the lock tree.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ *
+ * This function adds new entry for logical eraseblock (@vol_id, @lnum) to the
+ * lock tree. If such entry is already there, its usage counter is increased.
+ * Returns pointer to the lock tree entry or %-ENOMEM if memory allocation
+ * failed.
+ */
+static struct ubi_ltree_entry *ltree_add_entry(struct ubi_device *ubi,
+					       int vol_id, int lnum)
+{
+	struct ubi_ltree_entry *le, *le1, *le_free;
+
+	le = kmalloc(sizeof(struct ubi_ltree_entry), GFP_NOFS);
+	if (!le)
+		return ERR_PTR(-ENOMEM);
+
+	le->users = 0;
+	init_rwsem(&le->mutex);
+	le->vol_id = vol_id;
+	le->lnum = lnum;
+
+	spin_lock(&ubi->ltree_lock);
+	le1 = ltree_lookup(ubi, vol_id, lnum);
+
+	if (le1) {
+		/*
+		 * This logical eraseblock is already locked. The newly
+		 * allocated lock entry is not needed.
+		 */
+		le_free = le;
+		le = le1;
+	} else {
+		struct rb_node **p, *parent = NULL;
+
+		/*
+		 * No lock entry, add the newly allocated one to the
+		 * @ubi->ltree RB-tree.
+		 */
+		le_free = NULL;
+
+		p = &ubi->ltree.rb_node;
+		while (*p) {
+			parent = *p;
+			le1 = rb_entry(parent, struct ubi_ltree_entry, rb);
+
+			if (vol_id < le1->vol_id)
+				p = &(*p)->rb_left;
+			else if (vol_id > le1->vol_id)
+				p = &(*p)->rb_right;
+			else {
+				ubi_assert(lnum != le1->lnum);
+				if (lnum < le1->lnum)
+					p = &(*p)->rb_left;
+				else
+					p = &(*p)->rb_right;
+			}
+		}
+
+		rb_link_node(&le->rb, parent, p);
+		rb_insert_color(&le->rb, &ubi->ltree);
+	}
+	le->users += 1;
+	spin_unlock(&ubi->ltree_lock);
+
+	kfree(le_free);
+	return le;
+}
+
+/**
+ * leb_read_lock - lock logical eraseblock for reading.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ *
+ * This function locks a logical eraseblock for reading. Returns zero in case
+ * of success and a negative error code in case of failure.
+ */
+static int leb_read_lock(struct ubi_device *ubi, int vol_id, int lnum)
+{
+	struct ubi_ltree_entry *le;
+
+	le = ltree_add_entry(ubi, vol_id, lnum);
+	if (IS_ERR(le))
+		return PTR_ERR(le);
+	down_read(&le->mutex);
+	return 0;
+}
+
+/**
+ * leb_read_unlock - unlock logical eraseblock.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ */
+static void leb_read_unlock(struct ubi_device *ubi, int vol_id, int lnum)
+{
+	struct ubi_ltree_entry *le;
+
+	spin_lock(&ubi->ltree_lock);
+	le = ltree_lookup(ubi, vol_id, lnum);
+	le->users -= 1;
+	ubi_assert(le->users >= 0);
+	up_read(&le->mutex);
+	if (le->users == 0) {
+		rb_erase(&le->rb, &ubi->ltree);
+		kfree(le);
+	}
+	spin_unlock(&ubi->ltree_lock);
+}
+
+/**
+ * leb_write_lock - lock logical eraseblock for writing.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ *
+ * This function locks a logical eraseblock for writing. Returns zero in case
+ * of success and a negative error code in case of failure.
+ */
+static int leb_write_lock(struct ubi_device *ubi, int vol_id, int lnum)
+{
+	struct ubi_ltree_entry *le;
+
+	le = ltree_add_entry(ubi, vol_id, lnum);
+	if (IS_ERR(le))
+		return PTR_ERR(le);
+	down_write(&le->mutex);
+	return 0;
+}
+
+/**
+ * leb_write_trylock - try to lock logical eraseblock for writing.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ *
+ * This function locks a logical eraseblock for writing if there is no
+ * contention and does nothing if there is contention. Returns %0 in case of
+ * success, %1 in case of contention, and a negative error code in case of
+ * failure.
+ */
+static int leb_write_trylock(struct ubi_device *ubi, int vol_id, int lnum)
+{
+	struct ubi_ltree_entry *le;
+
+	le = ltree_add_entry(ubi, vol_id, lnum);
+	if (IS_ERR(le))
+		return PTR_ERR(le);
+	if (down_write_trylock(&le->mutex))
+		return 0;
+
+	/* Contention, cancel */
+	spin_lock(&ubi->ltree_lock);
+	le->users -= 1;
+	ubi_assert(le->users >= 0);
+	if (le->users == 0) {
+		rb_erase(&le->rb, &ubi->ltree);
+		kfree(le);
+	}
+	spin_unlock(&ubi->ltree_lock);
+
+	return 1;
+}
+
+/**
+ * leb_write_unlock - unlock logical eraseblock.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ */
+static void leb_write_unlock(struct ubi_device *ubi, int vol_id, int lnum)
+{
+	struct ubi_ltree_entry *le;
+
+	spin_lock(&ubi->ltree_lock);
+	le = ltree_lookup(ubi, vol_id, lnum);
+	le->users -= 1;
+	ubi_assert(le->users >= 0);
+	up_write(&le->mutex);
+	if (le->users == 0) {
+		rb_erase(&le->rb, &ubi->ltree);
+		kfree(le);
+	}
+	spin_unlock(&ubi->ltree_lock);
+}
+
+/**
+ * ubi_eba_is_mapped - check if a LEB is mapped.
+ * @vol: volume description object
+ * @lnum: logical eraseblock number
+ *
+ * This function returns true if the LEB is mapped, false otherwise.
+ */
+bool ubi_eba_is_mapped(struct ubi_volume *vol, int lnum)
+{
+	return vol->eba_tbl->entries[lnum].pnum >= 0;
+}
+
+/**
+ * ubi_eba_unmap_leb - un-map logical eraseblock.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ * @lnum: logical eraseblock number
+ *
+ * This function un-maps logical eraseblock @lnum and schedules corresponding
+ * physical eraseblock for erasure. Returns zero in case of success and a
+ * negative error code in case of failure.
+ */
+int ubi_eba_unmap_leb(struct ubi_device *ubi, struct ubi_volume *vol,
+		      int lnum)
+{
+	int err, pnum, vol_id = vol->vol_id;
+
+	if (ubi->ro_mode)
+		return -EROFS;
+
+	err = leb_write_lock(ubi, vol_id, lnum);
+	if (err)
+		return err;
+
+	pnum = vol->eba_tbl->entries[lnum].pnum;
+	if (pnum < 0)
+		/* This logical eraseblock is already unmapped */
+		goto out_unlock;
+
+	dbg_eba("erase LEB %d:%d, PEB %d", vol_id, lnum, pnum);
+
+	down_read(&ubi->fm_eba_sem);
+	vol->eba_tbl->entries[lnum].pnum = UBI_LEB_UNMAPPED;
+	up_read(&ubi->fm_eba_sem);
+	err = ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 0);
+
+out_unlock:
+	leb_write_unlock(ubi, vol_id, lnum);
+	return err;
+}
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+/**
+ * check_mapping - check and fixup a mapping
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ * @lnum: logical eraseblock number
+ * @pnum: physical eraseblock number
+ *
+ * Checks whether a given mapping is valid. Fastmap cannot track LEB unmap
+ * operations, if such an operation is interrupted the mapping still looks
+ * good, but upon first read an ECC is reported to the upper layer.
+ * Normaly during the full-scan at attach time this is fixed, for Fastmap
+ * we have to deal with it while reading.
+ * If the PEB behind a LEB shows this symthom we change the mapping to
+ * %UBI_LEB_UNMAPPED and schedule the PEB for erasure.
+ *
+ * Returns 0 on success, negative error code in case of failure.
+ */
+static int check_mapping(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
+			 int *pnum)
+{
+	int err;
+	struct ubi_vid_io_buf *vidb;
+	struct ubi_vid_hdr *vid_hdr;
+
+	if (!ubi->fast_attach)
+		return 0;
+
+	if (!vol->checkmap || test_bit(lnum, vol->checkmap))
+		return 0;
+
+	vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS);
+	if (!vidb)
+		return -ENOMEM;
+
+	err = ubi_io_read_vid_hdr(ubi, *pnum, vidb, 0);
+	if (err > 0 && err != UBI_IO_BITFLIPS) {
+		int torture = 0;
+
+		switch (err) {
+			case UBI_IO_FF:
+			case UBI_IO_FF_BITFLIPS:
+			case UBI_IO_BAD_HDR:
+			case UBI_IO_BAD_HDR_EBADMSG:
+				break;
+			default:
+				ubi_assert(0);
+		}
+
+		if (err == UBI_IO_BAD_HDR_EBADMSG || err == UBI_IO_FF_BITFLIPS)
+			torture = 1;
+
+		down_read(&ubi->fm_eba_sem);
+		vol->eba_tbl->entries[lnum].pnum = UBI_LEB_UNMAPPED;
+		up_read(&ubi->fm_eba_sem);
+		ubi_wl_put_peb(ubi, vol->vol_id, lnum, *pnum, torture);
+
+		*pnum = UBI_LEB_UNMAPPED;
+	} else if (err < 0) {
+		ubi_err(ubi, "unable to read VID header back from PEB %i: %i",
+			*pnum, err);
+
+		goto out_free;
+	} else {
+		int found_vol_id, found_lnum;
+
+		ubi_assert(err == 0 || err == UBI_IO_BITFLIPS);
+
+		vid_hdr = ubi_get_vid_hdr(vidb);
+		found_vol_id = be32_to_cpu(vid_hdr->vol_id);
+		found_lnum = be32_to_cpu(vid_hdr->lnum);
+
+		if (found_lnum != lnum || found_vol_id != vol->vol_id) {
+			ubi_err(ubi, "EBA mismatch! PEB %i is LEB %i:%i instead of LEB %i:%i",
+				*pnum, found_vol_id, found_lnum, vol->vol_id, lnum);
+			ubi_ro_mode(ubi);
+			err = -EINVAL;
+			goto out_free;
+		}
+	}
+
+	set_bit(lnum, vol->checkmap);
+	err = 0;
+
+out_free:
+	ubi_free_vid_buf(vidb);
+
+	return err;
+}
+#else
+static int check_mapping(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
+		  int *pnum)
+{
+	return 0;
+}
+#endif
+
+/**
+ * ubi_eba_read_leb - read data.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ * @lnum: logical eraseblock number
+ * @buf: buffer to store the read data
+ * @offset: offset from where to read
+ * @len: how many bytes to read
+ * @check: data CRC check flag
+ *
+ * If the logical eraseblock @lnum is unmapped, @buf is filled with 0xFF
+ * bytes. The @check flag only makes sense for static volumes and forces
+ * eraseblock data CRC checking.
+ *
+ * In case of success this function returns zero. In case of a static volume,
+ * if data CRC mismatches - %-EBADMSG is returned. %-EBADMSG may also be
+ * returned for any volume type if an ECC error was detected by the MTD device
+ * driver. Other negative error cored may be returned in case of other errors.
+ */
+int ubi_eba_read_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
+		     void *buf, int offset, int len, int check)
+{
+	int err, pnum, scrub = 0, vol_id = vol->vol_id;
+	struct ubi_vid_io_buf *vidb;
+	struct ubi_vid_hdr *vid_hdr;
+	uint32_t crc;
+
+	err = leb_read_lock(ubi, vol_id, lnum);
+	if (err)
+		return err;
+
+	pnum = vol->eba_tbl->entries[lnum].pnum;
+	if (pnum >= 0) {
+		err = check_mapping(ubi, vol, lnum, &pnum);
+		if (err < 0)
+			goto out_unlock;
+	}
+
+	if (pnum == UBI_LEB_UNMAPPED) {
+		/*
+		 * The logical eraseblock is not mapped, fill the whole buffer
+		 * with 0xFF bytes. The exception is static volumes for which
+		 * it is an error to read unmapped logical eraseblocks.
+		 */
+		dbg_eba("read %d bytes from offset %d of LEB %d:%d (unmapped)",
+			len, offset, vol_id, lnum);
+		leb_read_unlock(ubi, vol_id, lnum);
+		ubi_assert(vol->vol_type != UBI_STATIC_VOLUME);
+		memset(buf, 0xFF, len);
+		return 0;
+	}
+
+	dbg_eba("read %d bytes from offset %d of LEB %d:%d, PEB %d",
+		len, offset, vol_id, lnum, pnum);
+
+	if (vol->vol_type == UBI_DYNAMIC_VOLUME)
+		check = 0;
+
+retry:
+	if (check) {
+		vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS);
+		if (!vidb) {
+			err = -ENOMEM;
+			goto out_unlock;
+		}
+
+		vid_hdr = ubi_get_vid_hdr(vidb);
+
+		err = ubi_io_read_vid_hdr(ubi, pnum, vidb, 1);
+		if (err && err != UBI_IO_BITFLIPS) {
+			if (err > 0) {
+				/*
+				 * The header is either absent or corrupted.
+				 * The former case means there is a bug -
+				 * switch to read-only mode just in case.
+				 * The latter case means a real corruption - we
+				 * may try to recover data. FIXME: but this is
+				 * not implemented.
+				 */
+				if (err == UBI_IO_BAD_HDR_EBADMSG ||
+				    err == UBI_IO_BAD_HDR) {
+					ubi_warn(ubi, "corrupted VID header at PEB %d, LEB %d:%d",
+						 pnum, vol_id, lnum);
+					err = -EBADMSG;
+				} else {
+					/*
+					 * Ending up here in the non-Fastmap case
+					 * is a clear bug as the VID header had to
+					 * be present at scan time to have it referenced.
+					 * With fastmap the story is more complicated.
+					 * Fastmap has the mapping info without the need
+					 * of a full scan. So the LEB could have been
+					 * unmapped, Fastmap cannot know this and keeps
+					 * the LEB referenced.
+					 * This is valid and works as the layer above UBI
+					 * has to do bookkeeping about used/referenced
+					 * LEBs in any case.
+					 */
+					if (ubi->fast_attach) {
+						err = -EBADMSG;
+					} else {
+						err = -EINVAL;
+						ubi_ro_mode(ubi);
+					}
+				}
+			}
+			goto out_free;
+		} else if (err == UBI_IO_BITFLIPS)
+			scrub = 1;
+
+		ubi_assert(lnum < be32_to_cpu(vid_hdr->used_ebs));
+		ubi_assert(len == be32_to_cpu(vid_hdr->data_size));
+
+		crc = be32_to_cpu(vid_hdr->data_crc);
+		ubi_free_vid_buf(vidb);
+	}
+
+	err = ubi_io_read_data(ubi, buf, pnum, offset, len);
+	if (err) {
+		if (err == UBI_IO_BITFLIPS)
+			scrub = 1;
+		else if (mtd_is_eccerr(err)) {
+			if (vol->vol_type == UBI_DYNAMIC_VOLUME)
+				goto out_unlock;
+			scrub = 1;
+			if (!check) {
+				ubi_msg(ubi, "force data checking");
+				check = 1;
+				goto retry;
+			}
+		} else
+			goto out_unlock;
+	}
+
+	if (check) {
+		uint32_t crc1 = crc32(UBI_CRC32_INIT, buf, len);
+		if (crc1 != crc) {
+			ubi_warn(ubi, "CRC error: calculated %#08x, must be %#08x",
+				 crc1, crc);
+			err = -EBADMSG;
+			goto out_unlock;
+		}
+	}
+
+	if (scrub)
+		err = ubi_wl_scrub_peb(ubi, pnum);
+
+	leb_read_unlock(ubi, vol_id, lnum);
+	return err;
+
+out_free:
+	ubi_free_vid_buf(vidb);
+out_unlock:
+	leb_read_unlock(ubi, vol_id, lnum);
+	return err;
+}
+
+/**
+ * ubi_eba_read_leb_sg - read data into a scatter gather list.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ * @lnum: logical eraseblock number
+ * @sgl: UBI scatter gather list to store the read data
+ * @offset: offset from where to read
+ * @len: how many bytes to read
+ * @check: data CRC check flag
+ *
+ * This function works exactly like ubi_eba_read_leb(). But instead of
+ * storing the read data into a buffer it writes to an UBI scatter gather
+ * list.
+ */
+int ubi_eba_read_leb_sg(struct ubi_device *ubi, struct ubi_volume *vol,
+			struct ubi_sgl *sgl, int lnum, int offset, int len,
+			int check)
+{
+	int to_read;
+	int ret;
+	struct scatterlist *sg;
+
+	for (;;) {
+		ubi_assert(sgl->list_pos < UBI_MAX_SG_COUNT);
+		sg = &sgl->sg[sgl->list_pos];
+		if (len < sg->length - sgl->page_pos)
+			to_read = len;
+		else
+			to_read = sg->length - sgl->page_pos;
+
+		ret = ubi_eba_read_leb(ubi, vol, lnum,
+				       sg_virt(sg) + sgl->page_pos, offset,
+				       to_read, check);
+		if (ret < 0)
+			return ret;
+
+		offset += to_read;
+		len -= to_read;
+		if (!len) {
+			sgl->page_pos += to_read;
+			if (sgl->page_pos == sg->length) {
+				sgl->list_pos++;
+				sgl->page_pos = 0;
+			}
+
+			break;
+		}
+
+		sgl->list_pos++;
+		sgl->page_pos = 0;
+	}
+
+	return ret;
+}
+
+/**
+ * try_recover_peb - try to recover from write failure.
+ * @vol: volume description object
+ * @pnum: the physical eraseblock to recover
+ * @lnum: logical eraseblock number
+ * @buf: data which was not written because of the write failure
+ * @offset: offset of the failed write
+ * @len: how many bytes should have been written
+ * @vidb: VID buffer
+ * @retry: whether the caller should retry in case of failure
+ *
+ * This function is called in case of a write failure and moves all good data
+ * from the potentially bad physical eraseblock to a good physical eraseblock.
+ * This function also writes the data which was not written due to the failure.
+ * Returns 0 in case of success, and a negative error code in case of failure.
+ * In case of failure, the %retry parameter is set to false if this is a fatal
+ * error (retrying won't help), and true otherwise.
+ */
+static int try_recover_peb(struct ubi_volume *vol, int pnum, int lnum,
+			   const void *buf, int offset, int len,
+			   struct ubi_vid_io_buf *vidb, bool *retry)
+{
+	struct ubi_device *ubi = vol->ubi;
+	struct ubi_vid_hdr *vid_hdr;
+	int new_pnum, err, vol_id = vol->vol_id, data_size;
+	uint32_t crc;
+
+	*retry = false;
+
+	new_pnum = ubi_wl_get_peb(ubi);
+	if (new_pnum < 0) {
+		err = new_pnum;
+		goto out_put;
+	}
+
+	ubi_msg(ubi, "recover PEB %d, move data to PEB %d",
+		pnum, new_pnum);
+
+	err = ubi_io_read_vid_hdr(ubi, pnum, vidb, 1);
+	if (err && err != UBI_IO_BITFLIPS) {
+		if (err > 0)
+			err = -EIO;
+		goto out_put;
+	}
+
+	vid_hdr = ubi_get_vid_hdr(vidb);
+	ubi_assert(vid_hdr->vol_type == UBI_VID_DYNAMIC);
+
+	mutex_lock(&ubi->buf_mutex);
+	memset(ubi->peb_buf + offset, 0xFF, len);
+
+	/* Read everything before the area where the write failure happened */
+	if (offset > 0) {
+		err = ubi_io_read_data(ubi, ubi->peb_buf, pnum, 0, offset);
+		if (err && err != UBI_IO_BITFLIPS)
+			goto out_unlock;
+	}
+
+	*retry = true;
+
+	memcpy(ubi->peb_buf + offset, buf, len);
+
+	data_size = offset + len;
+	crc = crc32(UBI_CRC32_INIT, ubi->peb_buf, data_size);
+	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
+	vid_hdr->copy_flag = 1;
+	vid_hdr->data_size = cpu_to_be32(data_size);
+	vid_hdr->data_crc = cpu_to_be32(crc);
+	err = ubi_io_write_vid_hdr(ubi, new_pnum, vidb);
+	if (err)
+		goto out_unlock;
+
+	err = ubi_io_write_data(ubi, ubi->peb_buf, new_pnum, 0, data_size);
+
+out_unlock:
+	mutex_unlock(&ubi->buf_mutex);
+
+	if (!err)
+		vol->eba_tbl->entries[lnum].pnum = new_pnum;
+
+out_put:
+	up_read(&ubi->fm_eba_sem);
+
+	if (!err) {
+		ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 1);
+		ubi_msg(ubi, "data was successfully recovered");
+	} else if (new_pnum >= 0) {
+		/*
+		 * Bad luck? This physical eraseblock is bad too? Crud. Let's
+		 * try to get another one.
+		 */
+		ubi_wl_put_peb(ubi, vol_id, lnum, new_pnum, 1);
+		ubi_warn(ubi, "failed to write to PEB %d", new_pnum);
+	}
+
+	return err;
+}
+
+/**
+ * recover_peb - recover from write failure.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock to recover
+ * @vol_id: volume ID
+ * @lnum: logical eraseblock number
+ * @buf: data which was not written because of the write failure
+ * @offset: offset of the failed write
+ * @len: how many bytes should have been written
+ *
+ * This function is called in case of a write failure and moves all good data
+ * from the potentially bad physical eraseblock to a good physical eraseblock.
+ * This function also writes the data which was not written due to the failure.
+ * Returns 0 in case of success, and a negative error code in case of failure.
+ * This function tries %UBI_IO_RETRIES before giving up.
+ */
+static int recover_peb(struct ubi_device *ubi, int pnum, int vol_id, int lnum,
+		       const void *buf, int offset, int len)
+{
+	int err, idx = vol_id2idx(ubi, vol_id), tries;
+	struct ubi_volume *vol = ubi->volumes[idx];
+	struct ubi_vid_io_buf *vidb;
+
+	vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS);
+	if (!vidb)
+		return -ENOMEM;
+
+	for (tries = 0; tries <= UBI_IO_RETRIES; tries++) {
+		bool retry;
+
+		err = try_recover_peb(vol, pnum, lnum, buf, offset, len, vidb,
+				      &retry);
+		if (!err || !retry)
+			break;
+
+		ubi_msg(ubi, "try again");
+	}
+
+	ubi_free_vid_buf(vidb);
+
+	return err;
+}
+
+/**
+ * try_write_vid_and_data - try to write VID header and data to a new PEB.
+ * @vol: volume description object
+ * @lnum: logical eraseblock number
+ * @vidb: the VID buffer to write
+ * @buf: buffer containing the data
+ * @offset: where to start writing data
+ * @len: how many bytes should be written
+ *
+ * This function tries to write VID header and data belonging to logical
+ * eraseblock @lnum of volume @vol to a new physical eraseblock. Returns zero
+ * in case of success and a negative error code in case of failure.
+ * In case of error, it is possible that something was still written to the
+ * flash media, but may be some garbage.
+ */
+static int try_write_vid_and_data(struct ubi_volume *vol, int lnum,
+				  struct ubi_vid_io_buf *vidb, const void *buf,
+				  int offset, int len)
+{
+	struct ubi_device *ubi = vol->ubi;
+	int pnum, opnum, err, err2, vol_id = vol->vol_id;
+
+	pnum = ubi_wl_get_peb(ubi);
+	if (pnum < 0) {
+		err = pnum;
+		goto out_put;
+	}
+
+	opnum = vol->eba_tbl->entries[lnum].pnum;
+
+	dbg_eba("write VID hdr and %d bytes at offset %d of LEB %d:%d, PEB %d",
+		len, offset, vol_id, lnum, pnum);
+
+	err = ubi_io_write_vid_hdr(ubi, pnum, vidb);
+	if (err) {
+		ubi_warn(ubi, "failed to write VID header to LEB %d:%d, PEB %d",
+			 vol_id, lnum, pnum);
+		goto out_put;
+	}
+
+	if (len) {
+		err = ubi_io_write_data(ubi, buf, pnum, offset, len);
+		if (err) {
+			ubi_warn(ubi,
+				 "failed to write %d bytes at offset %d of LEB %d:%d, PEB %d",
+				 len, offset, vol_id, lnum, pnum);
+			goto out_put;
+		}
+	}
+
+	vol->eba_tbl->entries[lnum].pnum = pnum;
+
+out_put:
+	up_read(&ubi->fm_eba_sem);
+
+	if (err && pnum >= 0) {
+		err2 = ubi_wl_put_peb(ubi, vol_id, lnum, pnum, 1);
+		if (err2) {
+			ubi_warn(ubi, "failed to return physical eraseblock %d, error %d",
+				 pnum, err2);
+		}
+	} else if (!err && opnum >= 0) {
+		err2 = ubi_wl_put_peb(ubi, vol_id, lnum, opnum, 0);
+		if (err2) {
+			ubi_warn(ubi, "failed to return physical eraseblock %d, error %d",
+				 opnum, err2);
+		}
+	}
+
+	return err;
+}
+
+/**
+ * ubi_eba_write_leb - write data to dynamic volume.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ * @lnum: logical eraseblock number
+ * @buf: the data to write
+ * @offset: offset within the logical eraseblock where to write
+ * @len: how many bytes to write
+ *
+ * This function writes data to logical eraseblock @lnum of a dynamic volume
+ * @vol. Returns zero in case of success and a negative error code in case
+ * of failure. In case of error, it is possible that something was still
+ * written to the flash media, but may be some garbage.
+ * This function retries %UBI_IO_RETRIES times before giving up.
+ */
+int ubi_eba_write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
+		      const void *buf, int offset, int len)
+{
+	int err, pnum, tries, vol_id = vol->vol_id;
+	struct ubi_vid_io_buf *vidb;
+	struct ubi_vid_hdr *vid_hdr;
+
+	if (ubi->ro_mode)
+		return -EROFS;
+
+	err = leb_write_lock(ubi, vol_id, lnum);
+	if (err)
+		return err;
+
+	pnum = vol->eba_tbl->entries[lnum].pnum;
+	if (pnum >= 0) {
+		err = check_mapping(ubi, vol, lnum, &pnum);
+		if (err < 0)
+			goto out;
+	}
+
+	if (pnum >= 0) {
+		dbg_eba("write %d bytes at offset %d of LEB %d:%d, PEB %d",
+			len, offset, vol_id, lnum, pnum);
+
+		err = ubi_io_write_data(ubi, buf, pnum, offset, len);
+		if (err) {
+			ubi_warn(ubi, "failed to write data to PEB %d", pnum);
+			if (err == -EIO && ubi->bad_allowed)
+				err = recover_peb(ubi, pnum, vol_id, lnum, buf,
+						  offset, len);
+		}
+
+		goto out;
+	}
+
+	/*
+	 * The logical eraseblock is not mapped. We have to get a free physical
+	 * eraseblock and write the volume identifier header there first.
+	 */
+	vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS);
+	if (!vidb) {
+		leb_write_unlock(ubi, vol_id, lnum);
+		return -ENOMEM;
+	}
+
+	vid_hdr = ubi_get_vid_hdr(vidb);
+
+	vid_hdr->vol_type = UBI_VID_DYNAMIC;
+	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
+	vid_hdr->vol_id = cpu_to_be32(vol_id);
+	vid_hdr->lnum = cpu_to_be32(lnum);
+	vid_hdr->compat = ubi_get_compat(ubi, vol_id);
+	vid_hdr->data_pad = cpu_to_be32(vol->data_pad);
+
+	for (tries = 0; tries <= UBI_IO_RETRIES; tries++) {
+		err = try_write_vid_and_data(vol, lnum, vidb, buf, offset, len);
+		if (err != -EIO || !ubi->bad_allowed)
+			break;
+
+		/*
+		 * Fortunately, this is the first write operation to this
+		 * physical eraseblock, so just put it and request a new one.
+		 * We assume that if this physical eraseblock went bad, the
+		 * erase code will handle that.
+		 */
+		vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
+		ubi_msg(ubi, "try another PEB");
+	}
+
+	ubi_free_vid_buf(vidb);
+
+out:
+	if (err)
+		ubi_ro_mode(ubi);
+
+	leb_write_unlock(ubi, vol_id, lnum);
+
+	return err;
+}
+
+/**
+ * ubi_eba_write_leb_st - write data to static volume.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ * @lnum: logical eraseblock number
+ * @buf: data to write
+ * @len: how many bytes to write
+ * @used_ebs: how many logical eraseblocks will this volume contain
+ *
+ * This function writes data to logical eraseblock @lnum of static volume
+ * @vol. The @used_ebs argument should contain total number of logical
+ * eraseblock in this static volume.
+ *
+ * When writing to the last logical eraseblock, the @len argument doesn't have
+ * to be aligned to the minimal I/O unit size. Instead, it has to be equivalent
+ * to the real data size, although the @buf buffer has to contain the
+ * alignment. In all other cases, @len has to be aligned.
+ *
+ * It is prohibited to write more than once to logical eraseblocks of static
+ * volumes. This function returns zero in case of success and a negative error
+ * code in case of failure.
+ */
+int ubi_eba_write_leb_st(struct ubi_device *ubi, struct ubi_volume *vol,
+			 int lnum, const void *buf, int len, int used_ebs)
+{
+	int err, tries, data_size = len, vol_id = vol->vol_id;
+	struct ubi_vid_io_buf *vidb;
+	struct ubi_vid_hdr *vid_hdr;
+	uint32_t crc;
+
+	if (ubi->ro_mode)
+		return -EROFS;
+
+	if (lnum == used_ebs - 1)
+		/* If this is the last LEB @len may be unaligned */
+		len = ALIGN(data_size, ubi->min_io_size);
+	else
+		ubi_assert(!(len & (ubi->min_io_size - 1)));
+
+	vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS);
+	if (!vidb)
+		return -ENOMEM;
+
+	vid_hdr = ubi_get_vid_hdr(vidb);
+
+	err = leb_write_lock(ubi, vol_id, lnum);
+	if (err)
+		goto out;
+
+	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
+	vid_hdr->vol_id = cpu_to_be32(vol_id);
+	vid_hdr->lnum = cpu_to_be32(lnum);
+	vid_hdr->compat = ubi_get_compat(ubi, vol_id);
+	vid_hdr->data_pad = cpu_to_be32(vol->data_pad);
+
+	crc = crc32(UBI_CRC32_INIT, buf, data_size);
+	vid_hdr->vol_type = UBI_VID_STATIC;
+	vid_hdr->data_size = cpu_to_be32(data_size);
+	vid_hdr->used_ebs = cpu_to_be32(used_ebs);
+	vid_hdr->data_crc = cpu_to_be32(crc);
+
+	ubi_assert(vol->eba_tbl->entries[lnum].pnum < 0);
+
+	for (tries = 0; tries <= UBI_IO_RETRIES; tries++) {
+		err = try_write_vid_and_data(vol, lnum, vidb, buf, 0, len);
+		if (err != -EIO || !ubi->bad_allowed)
+			break;
+
+		vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
+		ubi_msg(ubi, "try another PEB");
+	}
+
+	if (err)
+		ubi_ro_mode(ubi);
+
+	leb_write_unlock(ubi, vol_id, lnum);
+
+out:
+	ubi_free_vid_buf(vidb);
+
+	return err;
+}
+
+/*
+ * ubi_eba_atomic_leb_change - change logical eraseblock atomically.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ * @lnum: logical eraseblock number
+ * @buf: data to write
+ * @len: how many bytes to write
+ *
+ * This function changes the contents of a logical eraseblock atomically. @buf
+ * has to contain new logical eraseblock data, and @len - the length of the
+ * data, which has to be aligned. This function guarantees that in case of an
+ * unclean reboot the old contents is preserved. Returns zero in case of
+ * success and a negative error code in case of failure.
+ *
+ * UBI reserves one LEB for the "atomic LEB change" operation, so only one
+ * LEB change may be done at a time. This is ensured by @ubi->alc_mutex.
+ */
+int ubi_eba_atomic_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
+			      int lnum, const void *buf, int len)
+{
+	int err, tries, vol_id = vol->vol_id;
+	struct ubi_vid_io_buf *vidb;
+	struct ubi_vid_hdr *vid_hdr;
+	uint32_t crc;
+
+	if (ubi->ro_mode)
+		return -EROFS;
+
+	if (len == 0) {
+		/*
+		 * Special case when data length is zero. In this case the LEB
+		 * has to be unmapped and mapped somewhere else.
+		 */
+		err = ubi_eba_unmap_leb(ubi, vol, lnum);
+		if (err)
+			return err;
+		return ubi_eba_write_leb(ubi, vol, lnum, NULL, 0, 0);
+	}
+
+	vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS);
+	if (!vidb)
+		return -ENOMEM;
+
+	vid_hdr = ubi_get_vid_hdr(vidb);
+
+	mutex_lock(&ubi->alc_mutex);
+	err = leb_write_lock(ubi, vol_id, lnum);
+	if (err)
+		goto out_mutex;
+
+	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
+	vid_hdr->vol_id = cpu_to_be32(vol_id);
+	vid_hdr->lnum = cpu_to_be32(lnum);
+	vid_hdr->compat = ubi_get_compat(ubi, vol_id);
+	vid_hdr->data_pad = cpu_to_be32(vol->data_pad);
+
+	crc = crc32(UBI_CRC32_INIT, buf, len);
+	vid_hdr->vol_type = UBI_VID_DYNAMIC;
+	vid_hdr->data_size = cpu_to_be32(len);
+	vid_hdr->copy_flag = 1;
+	vid_hdr->data_crc = cpu_to_be32(crc);
+
+	dbg_eba("change LEB %d:%d", vol_id, lnum);
+
+	for (tries = 0; tries <= UBI_IO_RETRIES; tries++) {
+		err = try_write_vid_and_data(vol, lnum, vidb, buf, 0, len);
+		if (err != -EIO || !ubi->bad_allowed)
+			break;
+
+		vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
+		ubi_msg(ubi, "try another PEB");
+	}
+
+	/*
+	 * This flash device does not admit of bad eraseblocks or
+	 * something nasty and unexpected happened. Switch to read-only
+	 * mode just in case.
+	 */
+	if (err)
+		ubi_ro_mode(ubi);
+
+	leb_write_unlock(ubi, vol_id, lnum);
+
+out_mutex:
+	mutex_unlock(&ubi->alc_mutex);
+	ubi_free_vid_buf(vidb);
+	return err;
+}
+
+/**
+ * is_error_sane - check whether a read error is sane.
+ * @err: code of the error happened during reading
+ *
+ * This is a helper function for 'ubi_eba_copy_leb()' which is called when we
+ * cannot read data from the target PEB (an error @err happened). If the error
+ * code is sane, then we treat this error as non-fatal. Otherwise the error is
+ * fatal and UBI will be switched to R/O mode later.
+ *
+ * The idea is that we try not to switch to R/O mode if the read error is
+ * something which suggests there was a real read problem. E.g., %-EIO. Or a
+ * memory allocation failed (-%ENOMEM). Otherwise, it is safer to switch to R/O
+ * mode, simply because we do not know what happened at the MTD level, and we
+ * cannot handle this. E.g., the underlying driver may have become crazy, and
+ * it is safer to switch to R/O mode to preserve the data.
+ *
+ * And bear in mind, this is about reading from the target PEB, i.e. the PEB
+ * which we have just written.
+ */
+static int is_error_sane(int err)
+{
+	if (err == -EIO || err == -ENOMEM || err == UBI_IO_BAD_HDR ||
+	    err == UBI_IO_BAD_HDR_EBADMSG || err == -ETIMEDOUT)
+		return 0;
+	return 1;
+}
+
+/**
+ * ubi_eba_copy_leb - copy logical eraseblock.
+ * @ubi: UBI device description object
+ * @from: physical eraseblock number from where to copy
+ * @to: physical eraseblock number where to copy
+ * @vidb: data structure from where the VID header is derived
+ *
+ * This function copies logical eraseblock from physical eraseblock @from to
+ * physical eraseblock @to. The @vid_hdr buffer may be changed by this
+ * function. Returns:
+ *   o %0 in case of success;
+ *   o %MOVE_CANCEL_RACE, %MOVE_TARGET_WR_ERR, %MOVE_TARGET_BITFLIPS, etc;
+ *   o a negative error code in case of failure.
+ */
+int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
+		     struct ubi_vid_io_buf *vidb)
+{
+	int err, vol_id, lnum, data_size, aldata_size, idx;
+	struct ubi_vid_hdr *vid_hdr = ubi_get_vid_hdr(vidb);
+	struct ubi_volume *vol;
+	uint32_t crc;
+
+	ubi_assert(rwsem_is_locked(&ubi->fm_eba_sem));
+
+	vol_id = be32_to_cpu(vid_hdr->vol_id);
+	lnum = be32_to_cpu(vid_hdr->lnum);
+
+	dbg_wl("copy LEB %d:%d, PEB %d to PEB %d", vol_id, lnum, from, to);
+
+	if (vid_hdr->vol_type == UBI_VID_STATIC) {
+		data_size = be32_to_cpu(vid_hdr->data_size);
+		aldata_size = ALIGN(data_size, ubi->min_io_size);
+	} else
+		data_size = aldata_size =
+			    ubi->leb_size - be32_to_cpu(vid_hdr->data_pad);
+
+	idx = vol_id2idx(ubi, vol_id);
+	spin_lock(&ubi->volumes_lock);
+	/*
+	 * Note, we may race with volume deletion, which means that the volume
+	 * this logical eraseblock belongs to might be being deleted. Since the
+	 * volume deletion un-maps all the volume's logical eraseblocks, it will
+	 * be locked in 'ubi_wl_put_peb()' and wait for the WL worker to finish.
+	 */
+	vol = ubi->volumes[idx];
+	spin_unlock(&ubi->volumes_lock);
+	if (!vol) {
+		/* No need to do further work, cancel */
+		dbg_wl("volume %d is being removed, cancel", vol_id);
+		return MOVE_CANCEL_RACE;
+	}
+
+	/*
+	 * We do not want anybody to write to this logical eraseblock while we
+	 * are moving it, so lock it.
+	 *
+	 * Note, we are using non-waiting locking here, because we cannot sleep
+	 * on the LEB, since it may cause deadlocks. Indeed, imagine a task is
+	 * unmapping the LEB which is mapped to the PEB we are going to move
+	 * (@from). This task locks the LEB and goes sleep in the
+	 * 'ubi_wl_put_peb()' function on the @ubi->move_mutex. In turn, we are
+	 * holding @ubi->move_mutex and go sleep on the LEB lock. So, if the
+	 * LEB is already locked, we just do not move it and return
+	 * %MOVE_RETRY. Note, we do not return %MOVE_CANCEL_RACE here because
+	 * we do not know the reasons of the contention - it may be just a
+	 * normal I/O on this LEB, so we want to re-try.
+	 */
+	err = leb_write_trylock(ubi, vol_id, lnum);
+	if (err) {
+		dbg_wl("contention on LEB %d:%d, cancel", vol_id, lnum);
+		return MOVE_RETRY;
+	}
+
+	/*
+	 * The LEB might have been put meanwhile, and the task which put it is
+	 * probably waiting on @ubi->move_mutex. No need to continue the work,
+	 * cancel it.
+	 */
+	if (vol->eba_tbl->entries[lnum].pnum != from) {
+		dbg_wl("LEB %d:%d is no longer mapped to PEB %d, mapped to PEB %d, cancel",
+		       vol_id, lnum, from, vol->eba_tbl->entries[lnum].pnum);
+		err = MOVE_CANCEL_RACE;
+		goto out_unlock_leb;
+	}
+
+	/*
+	 * OK, now the LEB is locked and we can safely start moving it. Since
+	 * this function utilizes the @ubi->peb_buf buffer which is shared
+	 * with some other functions - we lock the buffer by taking the
+	 * @ubi->buf_mutex.
+	 */
+	mutex_lock(&ubi->buf_mutex);
+	dbg_wl("read %d bytes of data", aldata_size);
+	err = ubi_io_read_data(ubi, ubi->peb_buf, from, 0, aldata_size);
+	if (err && err != UBI_IO_BITFLIPS) {
+		ubi_warn(ubi, "error %d while reading data from PEB %d",
+			 err, from);
+		err = MOVE_SOURCE_RD_ERR;
+		goto out_unlock_buf;
+	}
+
+	/*
+	 * Now we have got to calculate how much data we have to copy. In
+	 * case of a static volume it is fairly easy - the VID header contains
+	 * the data size. In case of a dynamic volume it is more difficult - we
+	 * have to read the contents, cut 0xFF bytes from the end and copy only
+	 * the first part. We must do this to avoid writing 0xFF bytes as it
+	 * may have some side-effects. And not only this. It is important not
+	 * to include those 0xFFs to CRC because later the they may be filled
+	 * by data.
+	 */
+	if (vid_hdr->vol_type == UBI_VID_DYNAMIC)
+		aldata_size = data_size =
+			ubi_calc_data_len(ubi, ubi->peb_buf, data_size);
+
+	cond_resched();
+	crc = crc32(UBI_CRC32_INIT, ubi->peb_buf, data_size);
+	cond_resched();
+
+	/*
+	 * It may turn out to be that the whole @from physical eraseblock
+	 * contains only 0xFF bytes. Then we have to only write the VID header
+	 * and do not write any data. This also means we should not set
+	 * @vid_hdr->copy_flag, @vid_hdr->data_size, and @vid_hdr->data_crc.
+	 */
+	if (data_size > 0) {
+		vid_hdr->copy_flag = 1;
+		vid_hdr->data_size = cpu_to_be32(data_size);
+		vid_hdr->data_crc = cpu_to_be32(crc);
+	}
+	vid_hdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
+
+	err = ubi_io_write_vid_hdr(ubi, to, vidb);
+	if (err) {
+		if (err == -EIO)
+			err = MOVE_TARGET_WR_ERR;
+		goto out_unlock_buf;
+	}
+
+	cond_resched();
+
+	/* Read the VID header back and check if it was written correctly */
+	err = ubi_io_read_vid_hdr(ubi, to, vidb, 1);
+	if (err) {
+		if (err != UBI_IO_BITFLIPS) {
+			ubi_warn(ubi, "error %d while reading VID header back from PEB %d",
+				 err, to);
+			if (is_error_sane(err))
+				err = MOVE_TARGET_RD_ERR;
+		} else
+			err = MOVE_TARGET_BITFLIPS;
+		goto out_unlock_buf;
+	}
+
+	if (data_size > 0) {
+		err = ubi_io_write_data(ubi, ubi->peb_buf, to, 0, aldata_size);
+		if (err) {
+			if (err == -EIO)
+				err = MOVE_TARGET_WR_ERR;
+			goto out_unlock_buf;
+		}
+
+		cond_resched();
+	}
+
+	ubi_assert(vol->eba_tbl->entries[lnum].pnum == from);
+	vol->eba_tbl->entries[lnum].pnum = to;
+
+out_unlock_buf:
+	mutex_unlock(&ubi->buf_mutex);
+out_unlock_leb:
+	leb_write_unlock(ubi, vol_id, lnum);
+	return err;
+}
+
+/**
+ * print_rsvd_warning - warn about not having enough reserved PEBs.
+ * @ubi: UBI device description object
+ * @ai: UBI attach info object
+ *
+ * This is a helper function for 'ubi_eba_init()' which is called when UBI
+ * cannot reserve enough PEBs for bad block handling. This function makes a
+ * decision whether we have to print a warning or not. The algorithm is as
+ * follows:
+ *   o if this is a new UBI image, then just print the warning
+ *   o if this is an UBI image which has already been used for some time, print
+ *     a warning only if we can reserve less than 10% of the expected amount of
+ *     the reserved PEB.
+ *
+ * The idea is that when UBI is used, PEBs become bad, and the reserved pool
+ * of PEBs becomes smaller, which is normal and we do not want to scare users
+ * with a warning every time they attach the MTD device. This was an issue
+ * reported by real users.
+ */
+static void print_rsvd_warning(struct ubi_device *ubi,
+			       struct ubi_attach_info *ai)
+{
+	/*
+	 * The 1 << 18 (256KiB) number is picked randomly, just a reasonably
+	 * large number to distinguish between newly flashed and used images.
+	 */
+	if (ai->max_sqnum > (1 << 18)) {
+		int min = ubi->beb_rsvd_level / 10;
+
+		if (!min)
+			min = 1;
+		if (ubi->beb_rsvd_pebs > min)
+			return;
+	}
+
+	ubi_warn(ubi, "cannot reserve enough PEBs for bad PEB handling, reserved %d, need %d",
+		 ubi->beb_rsvd_pebs, ubi->beb_rsvd_level);
+	if (ubi->corr_peb_count)
+		ubi_warn(ubi, "%d PEBs are corrupted and not used",
+			 ubi->corr_peb_count);
+}
+
+/**
+ * self_check_eba - run a self check on the EBA table constructed by fastmap.
+ * @ubi: UBI device description object
+ * @ai_fastmap: UBI attach info object created by fastmap
+ * @ai_scan: UBI attach info object created by scanning
+ *
+ * Returns < 0 in case of an internal error, 0 otherwise.
+ * If a bad EBA table entry was found it will be printed out and
+ * ubi_assert() triggers.
+ */
+int self_check_eba(struct ubi_device *ubi, struct ubi_attach_info *ai_fastmap,
+		   struct ubi_attach_info *ai_scan)
+{
+	int i, j, num_volumes, ret = 0;
+	int **scan_eba, **fm_eba;
+	struct ubi_ainf_volume *av;
+	struct ubi_volume *vol;
+	struct ubi_ainf_peb *aeb;
+	struct rb_node *rb;
+
+	num_volumes = ubi->vtbl_slots + UBI_INT_VOL_COUNT;
+
+	scan_eba = kmalloc_array(num_volumes, sizeof(*scan_eba), GFP_KERNEL);
+	if (!scan_eba)
+		return -ENOMEM;
+
+	fm_eba = kmalloc_array(num_volumes, sizeof(*fm_eba), GFP_KERNEL);
+	if (!fm_eba) {
+		kfree(scan_eba);
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < num_volumes; i++) {
+		vol = ubi->volumes[i];
+		if (!vol)
+			continue;
+
+		scan_eba[i] = kmalloc_array(vol->reserved_pebs,
+					    sizeof(**scan_eba),
+					    GFP_KERNEL);
+		if (!scan_eba[i]) {
+			ret = -ENOMEM;
+			goto out_free;
+		}
+
+		fm_eba[i] = kmalloc_array(vol->reserved_pebs,
+					  sizeof(**fm_eba),
+					  GFP_KERNEL);
+		if (!fm_eba[i]) {
+			ret = -ENOMEM;
+			goto out_free;
+		}
+
+		for (j = 0; j < vol->reserved_pebs; j++)
+			scan_eba[i][j] = fm_eba[i][j] = UBI_LEB_UNMAPPED;
+
+		av = ubi_find_av(ai_scan, idx2vol_id(ubi, i));
+		if (!av)
+			continue;
+
+		ubi_rb_for_each_entry(rb, aeb, &av->root, u.rb)
+			scan_eba[i][aeb->lnum] = aeb->pnum;
+
+		av = ubi_find_av(ai_fastmap, idx2vol_id(ubi, i));
+		if (!av)
+			continue;
+
+		ubi_rb_for_each_entry(rb, aeb, &av->root, u.rb)
+			fm_eba[i][aeb->lnum] = aeb->pnum;
+
+		for (j = 0; j < vol->reserved_pebs; j++) {
+			if (scan_eba[i][j] != fm_eba[i][j]) {
+				if (scan_eba[i][j] == UBI_LEB_UNMAPPED ||
+					fm_eba[i][j] == UBI_LEB_UNMAPPED)
+					continue;
+
+				ubi_err(ubi, "LEB:%i:%i is PEB:%i instead of %i!",
+					vol->vol_id, j, fm_eba[i][j],
+					scan_eba[i][j]);
+				ubi_assert(0);
+			}
+		}
+	}
+
+out_free:
+	for (i = 0; i < num_volumes; i++) {
+		if (!ubi->volumes[i])
+			continue;
+
+		kfree(scan_eba[i]);
+		kfree(fm_eba[i]);
+	}
+
+	kfree(scan_eba);
+	kfree(fm_eba);
+	return ret;
+}
+
+/**
+ * ubi_eba_init - initialize the EBA sub-system using attaching information.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+int ubi_eba_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
+{
+	int i, err, num_volumes;
+	struct ubi_ainf_volume *av;
+	struct ubi_volume *vol;
+	struct ubi_ainf_peb *aeb;
+	struct rb_node *rb;
+
+	dbg_eba("initialize EBA sub-system");
+
+	spin_lock_init(&ubi->ltree_lock);
+	mutex_init(&ubi->alc_mutex);
+	ubi->ltree = RB_ROOT;
+
+	ubi->global_sqnum = ai->max_sqnum + 1;
+	num_volumes = ubi->vtbl_slots + UBI_INT_VOL_COUNT;
+
+	for (i = 0; i < num_volumes; i++) {
+		struct ubi_eba_table *tbl;
+
+		vol = ubi->volumes[i];
+		if (!vol)
+			continue;
+
+		cond_resched();
+
+		tbl = ubi_eba_create_table(vol, vol->reserved_pebs);
+		if (IS_ERR(tbl)) {
+			err = PTR_ERR(tbl);
+			goto out_free;
+		}
+
+		ubi_eba_replace_table(vol, tbl);
+
+		av = ubi_find_av(ai, idx2vol_id(ubi, i));
+		if (!av)
+			continue;
+
+		ubi_rb_for_each_entry(rb, aeb, &av->root, u.rb) {
+			if (aeb->lnum >= vol->reserved_pebs) {
+				/*
+				 * This may happen in case of an unclean reboot
+				 * during re-size.
+				 */
+				ubi_move_aeb_to_list(av, aeb, &ai->erase);
+			} else {
+				struct ubi_eba_entry *entry;
+
+				entry = &vol->eba_tbl->entries[aeb->lnum];
+				entry->pnum = aeb->pnum;
+			}
+		}
+	}
+
+	if (ubi->avail_pebs < EBA_RESERVED_PEBS) {
+		ubi_err(ubi, "no enough physical eraseblocks (%d, need %d)",
+			ubi->avail_pebs, EBA_RESERVED_PEBS);
+		if (ubi->corr_peb_count)
+			ubi_err(ubi, "%d PEBs are corrupted and not used",
+				ubi->corr_peb_count);
+		err = -ENOSPC;
+		goto out_free;
+	}
+	ubi->avail_pebs -= EBA_RESERVED_PEBS;
+	ubi->rsvd_pebs += EBA_RESERVED_PEBS;
+
+	if (ubi->bad_allowed) {
+		ubi_calculate_reserved(ubi);
+
+		if (ubi->avail_pebs < ubi->beb_rsvd_level) {
+			/* No enough free physical eraseblocks */
+			ubi->beb_rsvd_pebs = ubi->avail_pebs;
+			print_rsvd_warning(ubi, ai);
+		} else
+			ubi->beb_rsvd_pebs = ubi->beb_rsvd_level;
+
+		ubi->avail_pebs -= ubi->beb_rsvd_pebs;
+		ubi->rsvd_pebs  += ubi->beb_rsvd_pebs;
+	}
+
+	dbg_eba("EBA sub-system is initialized");
+	return 0;
+
+out_free:
+	for (i = 0; i < num_volumes; i++) {
+		if (!ubi->volumes[i])
+			continue;
+		ubi_eba_replace_table(ubi->volumes[i], NULL);
+	}
+	return err;
+}
diff --git a/drivers/mtd/ubi/fastmap-wl.c b/drivers/mtd/ubi/fastmap-wl.c
new file mode 100644
index 0000000000..863f571f1a
--- /dev/null
+++ b/drivers/mtd/ubi/fastmap-wl.c
@@ -0,0 +1,490 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2012 Linutronix GmbH
+ * Copyright (c) 2014 sigma star gmbh
+ * Author: Richard Weinberger <richard@nod.at>
+ */
+
+/**
+ * update_fastmap_work_fn - calls ubi_update_fastmap from a work queue
+ * @wrk: the work description object
+ */
+static void update_fastmap_work_fn(struct work_struct *wrk)
+{
+	struct ubi_device *ubi = container_of(wrk, struct ubi_device, fm_work);
+
+	ubi_update_fastmap(ubi);
+	spin_lock(&ubi->wl_lock);
+	ubi->fm_work_scheduled = 0;
+	spin_unlock(&ubi->wl_lock);
+}
+
+/**
+ * find_anchor_wl_entry - find wear-leveling entry to used as anchor PEB.
+ * @root: the RB-tree where to look for
+ */
+static struct ubi_wl_entry *find_anchor_wl_entry(struct rb_root *root)
+{
+	struct rb_node *p;
+	struct ubi_wl_entry *e, *victim = NULL;
+	int max_ec = UBI_MAX_ERASECOUNTER;
+
+	ubi_rb_for_each_entry(p, e, root, u.rb) {
+		if (e->pnum < UBI_FM_MAX_START && e->ec < max_ec) {
+			victim = e;
+			max_ec = e->ec;
+		}
+	}
+
+	return victim;
+}
+
+static inline void return_unused_peb(struct ubi_device *ubi,
+				     struct ubi_wl_entry *e)
+{
+	wl_tree_add(e, &ubi->free);
+	ubi->free_count++;
+}
+
+/**
+ * return_unused_pool_pebs - returns unused PEB to the free tree.
+ * @ubi: UBI device description object
+ * @pool: fastmap pool description object
+ */
+static void return_unused_pool_pebs(struct ubi_device *ubi,
+				    struct ubi_fm_pool *pool)
+{
+	int i;
+	struct ubi_wl_entry *e;
+
+	for (i = pool->used; i < pool->size; i++) {
+		e = ubi->lookuptbl[pool->pebs[i]];
+		return_unused_peb(ubi, e);
+	}
+}
+
+/**
+ * ubi_wl_get_fm_peb - find a physical erase block with a given maximal number.
+ * @ubi: UBI device description object
+ * @anchor: This PEB will be used as anchor PEB by fastmap
+ *
+ * The function returns a physical erase block with a given maximal number
+ * and removes it from the wl subsystem.
+ * Must be called with wl_lock held!
+ */
+struct ubi_wl_entry *ubi_wl_get_fm_peb(struct ubi_device *ubi, int anchor)
+{
+	struct ubi_wl_entry *e = NULL;
+
+	if (!ubi->free.rb_node || (ubi->free_count - ubi->beb_rsvd_pebs < 1))
+		goto out;
+
+	if (anchor)
+		e = find_anchor_wl_entry(&ubi->free);
+	else
+		e = find_mean_wl_entry(ubi, &ubi->free);
+
+	if (!e)
+		goto out;
+
+	self_check_in_wl_tree(ubi, e, &ubi->free);
+
+	/* remove it from the free list,
+	 * the wl subsystem does no longer know this erase block */
+	rb_erase(&e->u.rb, &ubi->free);
+	ubi->free_count--;
+out:
+	return e;
+}
+
+/*
+ * has_enough_free_count - whether ubi has enough free pebs to fill fm pools
+ * @ubi: UBI device description object
+ * @is_wl_pool: whether UBI is filling wear leveling pool
+ *
+ * This helper function checks whether there are enough free pebs (deducted
+ * by fastmap pebs) to fill fm_pool and fm_wl_pool, above rule works after
+ * there is at least one of free pebs is filled into fm_wl_pool.
+ * For wear leveling pool, UBI should also reserve free pebs for bad pebs
+ * handling, because there maybe no enough free pebs for user volumes after
+ * producing new bad pebs.
+ */
+static bool has_enough_free_count(struct ubi_device *ubi, bool is_wl_pool)
+{
+	int fm_used = 0;	// fastmap non anchor pebs.
+	int beb_rsvd_pebs;
+
+	if (!ubi->free.rb_node)
+		return false;
+
+	beb_rsvd_pebs = is_wl_pool ? ubi->beb_rsvd_pebs : 0;
+	if (ubi->fm_wl_pool.size > 0 && !(ubi->ro_mode || ubi->fm_disabled))
+		fm_used = ubi->fm_size / ubi->leb_size - 1;
+
+	return ubi->free_count - beb_rsvd_pebs > fm_used;
+}
+
+/**
+ * ubi_refill_pools - refills all fastmap PEB pools.
+ * @ubi: UBI device description object
+ */
+void ubi_refill_pools(struct ubi_device *ubi)
+{
+	struct ubi_fm_pool *wl_pool = &ubi->fm_wl_pool;
+	struct ubi_fm_pool *pool = &ubi->fm_pool;
+	struct ubi_wl_entry *e;
+	int enough;
+
+	spin_lock(&ubi->wl_lock);
+
+	return_unused_pool_pebs(ubi, wl_pool);
+	return_unused_pool_pebs(ubi, pool);
+
+	wl_pool->size = 0;
+	pool->size = 0;
+
+	if (ubi->fm_anchor) {
+		wl_tree_add(ubi->fm_anchor, &ubi->free);
+		ubi->free_count++;
+		ubi->fm_anchor = NULL;
+	}
+
+	if (!ubi->fm_disabled)
+		/*
+		 * All available PEBs are in ubi->free, now is the time to get
+		 * the best anchor PEBs.
+		 */
+		ubi->fm_anchor = ubi_wl_get_fm_peb(ubi, 1);
+
+	for (;;) {
+		enough = 0;
+		if (pool->size < pool->max_size) {
+			if (!has_enough_free_count(ubi, false))
+				break;
+
+			e = wl_get_wle(ubi);
+			if (!e)
+				break;
+
+			pool->pebs[pool->size] = e->pnum;
+			pool->size++;
+		} else
+			enough++;
+
+		if (wl_pool->size < wl_pool->max_size) {
+			if (!has_enough_free_count(ubi, true))
+				break;
+
+			e = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF);
+			self_check_in_wl_tree(ubi, e, &ubi->free);
+			rb_erase(&e->u.rb, &ubi->free);
+			ubi->free_count--;
+
+			wl_pool->pebs[wl_pool->size] = e->pnum;
+			wl_pool->size++;
+		} else
+			enough++;
+
+		if (enough == 2)
+			break;
+	}
+
+	wl_pool->used = 0;
+	pool->used = 0;
+
+	spin_unlock(&ubi->wl_lock);
+}
+
+/**
+ * produce_free_peb - produce a free physical eraseblock.
+ * @ubi: UBI device description object
+ *
+ * This function tries to make a free PEB by means of synchronous execution of
+ * pending works. This may be needed if, for example the background thread is
+ * disabled. Returns zero in case of success and a negative error code in case
+ * of failure.
+ */
+static int produce_free_peb(struct ubi_device *ubi)
+{
+	int err;
+
+	while (!ubi->free.rb_node && ubi->works_count) {
+		dbg_wl("do one work synchronously");
+		err = do_work(ubi);
+
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+/**
+ * ubi_wl_get_peb - get a physical eraseblock.
+ * @ubi: UBI device description object
+ *
+ * This function returns a physical eraseblock in case of success and a
+ * negative error code in case of failure.
+ * Returns with ubi->fm_eba_sem held in read mode!
+ */
+int ubi_wl_get_peb(struct ubi_device *ubi)
+{
+	int ret, attempts = 0;
+	struct ubi_fm_pool *pool = &ubi->fm_pool;
+	struct ubi_fm_pool *wl_pool = &ubi->fm_wl_pool;
+
+again:
+	down_read(&ubi->fm_eba_sem);
+	spin_lock(&ubi->wl_lock);
+
+	/* We check here also for the WL pool because at this point we can
+	 * refill the WL pool synchronous. */
+	if (pool->used == pool->size || wl_pool->used == wl_pool->size) {
+		spin_unlock(&ubi->wl_lock);
+		up_read(&ubi->fm_eba_sem);
+		ret = ubi_update_fastmap(ubi);
+		if (ret) {
+			ubi_msg(ubi, "Unable to write a new fastmap: %i", ret);
+			down_read(&ubi->fm_eba_sem);
+			return -ENOSPC;
+		}
+		down_read(&ubi->fm_eba_sem);
+		spin_lock(&ubi->wl_lock);
+	}
+
+	if (pool->used == pool->size) {
+		spin_unlock(&ubi->wl_lock);
+		attempts++;
+		if (attempts == 10) {
+			ubi_err(ubi, "Unable to get a free PEB from user WL pool");
+			ret = -ENOSPC;
+			goto out;
+		}
+		up_read(&ubi->fm_eba_sem);
+		ret = produce_free_peb(ubi);
+		if (ret < 0) {
+			down_read(&ubi->fm_eba_sem);
+			goto out;
+		}
+		goto again;
+	}
+
+	ubi_assert(pool->used < pool->size);
+	ret = pool->pebs[pool->used++];
+	prot_queue_add(ubi, ubi->lookuptbl[ret]);
+	spin_unlock(&ubi->wl_lock);
+out:
+	return ret;
+}
+
+/**
+ * next_peb_for_wl - returns next PEB to be used internally by the
+ * WL sub-system.
+ *
+ * @ubi: UBI device description object
+ */
+static struct ubi_wl_entry *next_peb_for_wl(struct ubi_device *ubi)
+{
+	struct ubi_fm_pool *pool = &ubi->fm_wl_pool;
+	int pnum;
+
+	if (pool->used == pool->size)
+		return NULL;
+
+	pnum = pool->pebs[pool->used];
+	return ubi->lookuptbl[pnum];
+}
+
+/**
+ * need_wear_leveling - checks whether to trigger a wear leveling work.
+ * UBI fetches free PEB from wl_pool, we check free PEBs from both 'wl_pool'
+ * and 'ubi->free', because free PEB in 'ubi->free' tree maybe moved into
+ * 'wl_pool' by ubi_refill_pools().
+ *
+ * @ubi: UBI device description object
+ */
+static bool need_wear_leveling(struct ubi_device *ubi)
+{
+	int ec;
+	struct ubi_wl_entry *e;
+
+	if (!ubi->used.rb_node)
+		return false;
+
+	e = next_peb_for_wl(ubi);
+	if (!e) {
+		if (!ubi->free.rb_node)
+			return false;
+		e = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF);
+		ec = e->ec;
+	} else {
+		ec = e->ec;
+		if (ubi->free.rb_node) {
+			e = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF);
+			ec = max(ec, e->ec);
+		}
+	}
+	e = rb_entry(rb_first(&ubi->used), struct ubi_wl_entry, u.rb);
+
+	return ec - e->ec >= UBI_WL_THRESHOLD;
+}
+
+/* get_peb_for_wl - returns a PEB to be used internally by the WL sub-system.
+ *
+ * @ubi: UBI device description object
+ */
+static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi)
+{
+	struct ubi_fm_pool *pool = &ubi->fm_wl_pool;
+	int pnum;
+
+	ubi_assert(rwsem_is_locked(&ubi->fm_eba_sem));
+
+	if (pool->used == pool->size) {
+		/* We cannot update the fastmap here because this
+		 * function is called in atomic context.
+		 * Let's fail here and refill/update it as soon as possible. */
+		if (!ubi->fm_work_scheduled) {
+			ubi->fm_work_scheduled = 1;
+			schedule_work(&ubi->fm_work);
+		}
+		return NULL;
+	}
+
+	pnum = pool->pebs[pool->used++];
+	return ubi->lookuptbl[pnum];
+}
+
+/**
+ * ubi_ensure_anchor_pebs - schedule wear-leveling to produce an anchor PEB.
+ * @ubi: UBI device description object
+ */
+int ubi_ensure_anchor_pebs(struct ubi_device *ubi)
+{
+	struct ubi_work *wrk;
+	struct ubi_wl_entry *anchor;
+
+	spin_lock(&ubi->wl_lock);
+
+	/* Do we already have an anchor? */
+	if (ubi->fm_anchor) {
+		spin_unlock(&ubi->wl_lock);
+		return 0;
+	}
+
+	/* See if we can find an anchor PEB on the list of free PEBs */
+	anchor = ubi_wl_get_fm_peb(ubi, 1);
+	if (anchor) {
+		ubi->fm_anchor = anchor;
+		spin_unlock(&ubi->wl_lock);
+		return 0;
+	}
+
+	ubi->fm_do_produce_anchor = 1;
+	/* No luck, trigger wear leveling to produce a new anchor PEB. */
+	if (ubi->wl_scheduled) {
+		spin_unlock(&ubi->wl_lock);
+		return 0;
+	}
+	ubi->wl_scheduled = 1;
+	spin_unlock(&ubi->wl_lock);
+
+	wrk = kmalloc(sizeof(struct ubi_work), GFP_NOFS);
+	if (!wrk) {
+		spin_lock(&ubi->wl_lock);
+		ubi->wl_scheduled = 0;
+		spin_unlock(&ubi->wl_lock);
+		return -ENOMEM;
+	}
+
+	wrk->func = &wear_leveling_worker;
+	__schedule_ubi_work(ubi, wrk);
+	return 0;
+}
+
+/**
+ * ubi_wl_put_fm_peb - returns a PEB used in a fastmap to the wear-leveling
+ * sub-system.
+ * see: ubi_wl_put_peb()
+ *
+ * @ubi: UBI device description object
+ * @fm_e: physical eraseblock to return
+ * @lnum: the last used logical eraseblock number for the PEB
+ * @torture: if this physical eraseblock has to be tortured
+ */
+int ubi_wl_put_fm_peb(struct ubi_device *ubi, struct ubi_wl_entry *fm_e,
+		      int lnum, int torture)
+{
+	struct ubi_wl_entry *e;
+	int vol_id, pnum = fm_e->pnum;
+
+	dbg_wl("PEB %d", pnum);
+
+	ubi_assert(pnum >= 0);
+	ubi_assert(pnum < ubi->peb_count);
+
+	spin_lock(&ubi->wl_lock);
+	e = ubi->lookuptbl[pnum];
+
+	/* This can happen if we recovered from a fastmap the very
+	 * first time and writing now a new one. In this case the wl system
+	 * has never seen any PEB used by the original fastmap.
+	 */
+	if (!e) {
+		e = fm_e;
+		ubi_assert(e->ec >= 0);
+		ubi->lookuptbl[pnum] = e;
+	}
+
+	spin_unlock(&ubi->wl_lock);
+
+	vol_id = lnum ? UBI_FM_DATA_VOLUME_ID : UBI_FM_SB_VOLUME_ID;
+	return schedule_erase(ubi, e, vol_id, lnum, torture, true);
+}
+
+/**
+ * ubi_is_erase_work - checks whether a work is erase work.
+ * @wrk: The work object to be checked
+ */
+int ubi_is_erase_work(struct ubi_work *wrk)
+{
+	return wrk->func == erase_worker;
+}
+
+static void ubi_fastmap_close(struct ubi_device *ubi)
+{
+	int i;
+
+	return_unused_pool_pebs(ubi, &ubi->fm_pool);
+	return_unused_pool_pebs(ubi, &ubi->fm_wl_pool);
+
+	if (ubi->fm_anchor) {
+		return_unused_peb(ubi, ubi->fm_anchor);
+		ubi->fm_anchor = NULL;
+	}
+
+	if (ubi->fm) {
+		for (i = 0; i < ubi->fm->used_blocks; i++)
+			kfree(ubi->fm->e[i]);
+	}
+	kfree(ubi->fm);
+}
+
+/**
+ * may_reserve_for_fm - tests whether a PEB shall be reserved for fastmap.
+ * See find_mean_wl_entry()
+ *
+ * @ubi: UBI device description object
+ * @e: physical eraseblock to return
+ * @root: RB tree to test against.
+ */
+static struct ubi_wl_entry *may_reserve_for_fm(struct ubi_device *ubi,
+					   struct ubi_wl_entry *e,
+					   struct rb_root *root) {
+	if (e && !ubi->fm_disabled && !ubi->fm &&
+	    e->pnum < UBI_FM_MAX_START)
+		e = rb_entry(rb_next(root->rb_node),
+			     struct ubi_wl_entry, u.rb);
+
+	return e;
+}
diff --git a/drivers/mtd/ubi/fastmap.c b/drivers/mtd/ubi/fastmap.c
new file mode 100644
index 0000000000..28c8151a07
--- /dev/null
+++ b/drivers/mtd/ubi/fastmap.c
@@ -0,0 +1,1697 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2012 Linutronix GmbH
+ * Copyright (c) 2014 sigma star gmbh
+ * Author: Richard Weinberger <richard@nod.at>
+ */
+
+#include <linux/crc32.h>
+#include <linux/bitmap.h>
+#include "ubi.h"
+
+/**
+ * init_seen - allocate memory for used for debugging.
+ * @ubi: UBI device description object
+ */
+static inline unsigned long *init_seen(struct ubi_device *ubi)
+{
+	unsigned long *ret;
+
+	if (!ubi_dbg_chk_fastmap(ubi))
+		return NULL;
+
+	ret = bitmap_zalloc(ubi->peb_count, GFP_KERNEL);
+	if (!ret)
+		return ERR_PTR(-ENOMEM);
+
+	return ret;
+}
+
+/**
+ * free_seen - free the seen logic integer array.
+ * @seen: integer array of @ubi->peb_count size
+ */
+static inline void free_seen(unsigned long *seen)
+{
+	bitmap_free(seen);
+}
+
+/**
+ * set_seen - mark a PEB as seen.
+ * @ubi: UBI device description object
+ * @pnum: The PEB to be makred as seen
+ * @seen: integer array of @ubi->peb_count size
+ */
+static inline void set_seen(struct ubi_device *ubi, int pnum, unsigned long *seen)
+{
+	if (!ubi_dbg_chk_fastmap(ubi) || !seen)
+		return;
+
+	set_bit(pnum, seen);
+}
+
+/**
+ * self_check_seen - check whether all PEB have been seen by fastmap.
+ * @ubi: UBI device description object
+ * @seen: integer array of @ubi->peb_count size
+ */
+static int self_check_seen(struct ubi_device *ubi, unsigned long *seen)
+{
+	int pnum, ret = 0;
+
+	if (!ubi_dbg_chk_fastmap(ubi) || !seen)
+		return 0;
+
+	for (pnum = 0; pnum < ubi->peb_count; pnum++) {
+		if (!test_bit(pnum, seen) && ubi->lookuptbl[pnum]) {
+			ubi_err(ubi, "self-check failed for PEB %d, fastmap didn't see it", pnum);
+			ret = -EINVAL;
+		}
+	}
+
+	return ret;
+}
+
+/**
+ * ubi_calc_fm_size - calculates the fastmap size in bytes for an UBI device.
+ * @ubi: UBI device description object
+ */
+size_t ubi_calc_fm_size(struct ubi_device *ubi)
+{
+	size_t size;
+
+	size = sizeof(struct ubi_fm_sb) +
+		sizeof(struct ubi_fm_hdr) +
+		sizeof(struct ubi_fm_scan_pool) +
+		sizeof(struct ubi_fm_scan_pool) +
+		(ubi->peb_count * sizeof(struct ubi_fm_ec)) +
+		(sizeof(struct ubi_fm_eba) +
+		(ubi->peb_count * sizeof(__be32))) +
+		sizeof(struct ubi_fm_volhdr) * UBI_MAX_VOLUMES;
+	return roundup(size, ubi->leb_size);
+}
+
+
+/**
+ * new_fm_vbuf() - allocate a new volume header for fastmap usage.
+ * @ubi: UBI device description object
+ * @vol_id: the VID of the new header
+ *
+ * Returns a new struct ubi_vid_hdr on success.
+ * NULL indicates out of memory.
+ */
+static struct ubi_vid_io_buf *new_fm_vbuf(struct ubi_device *ubi, int vol_id)
+{
+	struct ubi_vid_io_buf *new;
+	struct ubi_vid_hdr *vh;
+
+	new = ubi_alloc_vid_buf(ubi, GFP_KERNEL);
+	if (!new)
+		goto out;
+
+	vh = ubi_get_vid_hdr(new);
+	vh->vol_type = UBI_VID_DYNAMIC;
+	vh->vol_id = cpu_to_be32(vol_id);
+
+	/* UBI implementations without fastmap support have to delete the
+	 * fastmap.
+	 */
+	vh->compat = UBI_COMPAT_DELETE;
+
+out:
+	return new;
+}
+
+/**
+ * add_aeb - create and add a attach erase block to a given list.
+ * @ai: UBI attach info object
+ * @list: the target list
+ * @pnum: PEB number of the new attach erase block
+ * @ec: erease counter of the new LEB
+ * @scrub: scrub this PEB after attaching
+ *
+ * Returns 0 on success, < 0 indicates an internal error.
+ */
+static int add_aeb(struct ubi_attach_info *ai, struct list_head *list,
+		   int pnum, int ec, int scrub)
+{
+	struct ubi_ainf_peb *aeb;
+
+	aeb = ubi_alloc_aeb(ai, pnum, ec);
+	if (!aeb)
+		return -ENOMEM;
+
+	aeb->lnum = -1;
+	aeb->scrub = scrub;
+	aeb->copy_flag = aeb->sqnum = 0;
+
+	ai->ec_sum += aeb->ec;
+	ai->ec_count++;
+
+	if (ai->max_ec < aeb->ec)
+		ai->max_ec = aeb->ec;
+
+	if (ai->min_ec > aeb->ec)
+		ai->min_ec = aeb->ec;
+
+	list_add_tail(&aeb->u.list, list);
+
+	return 0;
+}
+
+/**
+ * add_vol - create and add a new volume to ubi_attach_info.
+ * @ai: ubi_attach_info object
+ * @vol_id: VID of the new volume
+ * @used_ebs: number of used EBS
+ * @data_pad: data padding value of the new volume
+ * @vol_type: volume type
+ * @last_eb_bytes: number of bytes in the last LEB
+ *
+ * Returns the new struct ubi_ainf_volume on success.
+ * NULL indicates an error.
+ */
+static struct ubi_ainf_volume *add_vol(struct ubi_attach_info *ai, int vol_id,
+				       int used_ebs, int data_pad, u8 vol_type,
+				       int last_eb_bytes)
+{
+	struct ubi_ainf_volume *av;
+
+	av = ubi_add_av(ai, vol_id);
+	if (IS_ERR(av))
+		return av;
+
+	av->data_pad = data_pad;
+	av->last_data_size = last_eb_bytes;
+	av->compat = 0;
+	av->vol_type = vol_type;
+	if (av->vol_type == UBI_STATIC_VOLUME)
+		av->used_ebs = used_ebs;
+
+	dbg_bld("found volume (ID %i)", vol_id);
+	return av;
+}
+
+/**
+ * assign_aeb_to_av - assigns a SEB to a given ainf_volume and removes it
+ * from it's original list.
+ * @ai: ubi_attach_info object
+ * @aeb: the to be assigned SEB
+ * @av: target scan volume
+ */
+static void assign_aeb_to_av(struct ubi_attach_info *ai,
+			     struct ubi_ainf_peb *aeb,
+			     struct ubi_ainf_volume *av)
+{
+	struct ubi_ainf_peb *tmp_aeb;
+	struct rb_node **p = &av->root.rb_node, *parent = NULL;
+
+	while (*p) {
+		parent = *p;
+
+		tmp_aeb = rb_entry(parent, struct ubi_ainf_peb, u.rb);
+		if (aeb->lnum != tmp_aeb->lnum) {
+			if (aeb->lnum < tmp_aeb->lnum)
+				p = &(*p)->rb_left;
+			else
+				p = &(*p)->rb_right;
+
+			continue;
+		} else
+			break;
+	}
+
+	list_del(&aeb->u.list);
+	av->leb_count++;
+
+	rb_link_node(&aeb->u.rb, parent, p);
+	rb_insert_color(&aeb->u.rb, &av->root);
+}
+
+/**
+ * update_vol - inserts or updates a LEB which was found a pool.
+ * @ubi: the UBI device object
+ * @ai: attach info object
+ * @av: the volume this LEB belongs to
+ * @new_vh: the volume header derived from new_aeb
+ * @new_aeb: the AEB to be examined
+ *
+ * Returns 0 on success, < 0 indicates an internal error.
+ */
+static int update_vol(struct ubi_device *ubi, struct ubi_attach_info *ai,
+		      struct ubi_ainf_volume *av, struct ubi_vid_hdr *new_vh,
+		      struct ubi_ainf_peb *new_aeb)
+{
+	struct rb_node **p = &av->root.rb_node, *parent = NULL;
+	struct ubi_ainf_peb *aeb, *victim;
+	int cmp_res;
+
+	while (*p) {
+		parent = *p;
+		aeb = rb_entry(parent, struct ubi_ainf_peb, u.rb);
+
+		if (be32_to_cpu(new_vh->lnum) != aeb->lnum) {
+			if (be32_to_cpu(new_vh->lnum) < aeb->lnum)
+				p = &(*p)->rb_left;
+			else
+				p = &(*p)->rb_right;
+
+			continue;
+		}
+
+		/* This case can happen if the fastmap gets written
+		 * because of a volume change (creation, deletion, ..).
+		 * Then a PEB can be within the persistent EBA and the pool.
+		 */
+		if (aeb->pnum == new_aeb->pnum) {
+			ubi_assert(aeb->lnum == new_aeb->lnum);
+			ubi_free_aeb(ai, new_aeb);
+
+			return 0;
+		}
+
+		cmp_res = ubi_compare_lebs(ubi, aeb, new_aeb->pnum, new_vh);
+		if (cmp_res < 0)
+			return cmp_res;
+
+		/* new_aeb is newer */
+		if (cmp_res & 1) {
+			victim = ubi_alloc_aeb(ai, aeb->pnum, aeb->ec);
+			if (!victim)
+				return -ENOMEM;
+
+			list_add_tail(&victim->u.list, &ai->erase);
+
+			if (av->highest_lnum == be32_to_cpu(new_vh->lnum))
+				av->last_data_size =
+					be32_to_cpu(new_vh->data_size);
+
+			dbg_bld("vol %i: AEB %i's PEB %i is the newer",
+				av->vol_id, aeb->lnum, new_aeb->pnum);
+
+			aeb->ec = new_aeb->ec;
+			aeb->pnum = new_aeb->pnum;
+			aeb->copy_flag = new_vh->copy_flag;
+			aeb->scrub = new_aeb->scrub;
+			aeb->sqnum = new_aeb->sqnum;
+			ubi_free_aeb(ai, new_aeb);
+
+		/* new_aeb is older */
+		} else {
+			dbg_bld("vol %i: AEB %i's PEB %i is old, dropping it",
+				av->vol_id, aeb->lnum, new_aeb->pnum);
+			list_add_tail(&new_aeb->u.list, &ai->erase);
+		}
+
+		return 0;
+	}
+	/* This LEB is new, let's add it to the volume */
+
+	if (av->highest_lnum <= be32_to_cpu(new_vh->lnum)) {
+		av->highest_lnum = be32_to_cpu(new_vh->lnum);
+		av->last_data_size = be32_to_cpu(new_vh->data_size);
+	}
+
+	if (av->vol_type == UBI_STATIC_VOLUME)
+		av->used_ebs = be32_to_cpu(new_vh->used_ebs);
+
+	av->leb_count++;
+
+	rb_link_node(&new_aeb->u.rb, parent, p);
+	rb_insert_color(&new_aeb->u.rb, &av->root);
+
+	return 0;
+}
+
+/**
+ * process_pool_aeb - we found a non-empty PEB in a pool.
+ * @ubi: UBI device object
+ * @ai: attach info object
+ * @new_vh: the volume header derived from new_aeb
+ * @new_aeb: the AEB to be examined
+ *
+ * Returns 0 on success, < 0 indicates an internal error.
+ */
+static int process_pool_aeb(struct ubi_device *ubi, struct ubi_attach_info *ai,
+			    struct ubi_vid_hdr *new_vh,
+			    struct ubi_ainf_peb *new_aeb)
+{
+	int vol_id = be32_to_cpu(new_vh->vol_id);
+	struct ubi_ainf_volume *av;
+
+	if (vol_id == UBI_FM_SB_VOLUME_ID || vol_id == UBI_FM_DATA_VOLUME_ID) {
+		ubi_free_aeb(ai, new_aeb);
+
+		return 0;
+	}
+
+	/* Find the volume this SEB belongs to */
+	av = ubi_find_av(ai, vol_id);
+	if (!av) {
+		ubi_err(ubi, "orphaned volume in fastmap pool!");
+		ubi_free_aeb(ai, new_aeb);
+		return UBI_BAD_FASTMAP;
+	}
+
+	ubi_assert(vol_id == av->vol_id);
+
+	return update_vol(ubi, ai, av, new_vh, new_aeb);
+}
+
+/**
+ * unmap_peb - unmap a PEB.
+ * If fastmap detects a free PEB in the pool it has to check whether
+ * this PEB has been unmapped after writing the fastmap.
+ *
+ * @ai: UBI attach info object
+ * @pnum: The PEB to be unmapped
+ */
+static void unmap_peb(struct ubi_attach_info *ai, int pnum)
+{
+	struct ubi_ainf_volume *av;
+	struct rb_node *node, *node2;
+	struct ubi_ainf_peb *aeb;
+
+	ubi_rb_for_each_entry(node, av, &ai->volumes, rb) {
+		ubi_rb_for_each_entry(node2, aeb, &av->root, u.rb) {
+			if (aeb->pnum == pnum) {
+				rb_erase(&aeb->u.rb, &av->root);
+				av->leb_count--;
+				ubi_free_aeb(ai, aeb);
+				return;
+			}
+		}
+	}
+}
+
+/**
+ * scan_pool - scans a pool for changed (no longer empty PEBs).
+ * @ubi: UBI device object
+ * @ai: attach info object
+ * @pebs: an array of all PEB numbers in the to be scanned pool
+ * @pool_size: size of the pool (number of entries in @pebs)
+ * @max_sqnum: pointer to the maximal sequence number
+ * @free: list of PEBs which are most likely free (and go into @ai->free)
+ *
+ * Returns 0 on success, if the pool is unusable UBI_BAD_FASTMAP is returned.
+ * < 0 indicates an internal error.
+ */
+static int scan_pool(struct ubi_device *ubi, struct ubi_attach_info *ai,
+		     __be32 *pebs, int pool_size, unsigned long long *max_sqnum,
+		     struct list_head *free)
+{
+	struct ubi_vid_io_buf *vb;
+	struct ubi_vid_hdr *vh;
+	struct ubi_ec_hdr *ech;
+	struct ubi_ainf_peb *new_aeb;
+	int i, pnum, err, ret = 0;
+
+	ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!ech)
+		return -ENOMEM;
+
+	vb = ubi_alloc_vid_buf(ubi, GFP_KERNEL);
+	if (!vb) {
+		kfree(ech);
+		return -ENOMEM;
+	}
+
+	vh = ubi_get_vid_hdr(vb);
+
+	dbg_bld("scanning fastmap pool: size = %i", pool_size);
+
+	/*
+	 * Now scan all PEBs in the pool to find changes which have been made
+	 * after the creation of the fastmap
+	 */
+	for (i = 0; i < pool_size; i++) {
+		int scrub = 0;
+		int image_seq;
+
+		pnum = be32_to_cpu(pebs[i]);
+
+		if (ubi_io_is_bad(ubi, pnum)) {
+			ubi_err(ubi, "bad PEB in fastmap pool!");
+			ret = UBI_BAD_FASTMAP;
+			goto out;
+		}
+
+		err = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
+		if (err && err != UBI_IO_BITFLIPS) {
+			ubi_err(ubi, "unable to read EC header! PEB:%i err:%i",
+				pnum, err);
+			ret = err > 0 ? UBI_BAD_FASTMAP : err;
+			goto out;
+		} else if (err == UBI_IO_BITFLIPS)
+			scrub = 1;
+
+		/*
+		 * Older UBI implementations have image_seq set to zero, so
+		 * we shouldn't fail if image_seq == 0.
+		 */
+		image_seq = be32_to_cpu(ech->image_seq);
+
+		if (image_seq && (image_seq != ubi->image_seq)) {
+			ubi_err(ubi, "bad image seq: 0x%x, expected: 0x%x",
+				be32_to_cpu(ech->image_seq), ubi->image_seq);
+			ret = UBI_BAD_FASTMAP;
+			goto out;
+		}
+
+		err = ubi_io_read_vid_hdr(ubi, pnum, vb, 0);
+		if (err == UBI_IO_FF || err == UBI_IO_FF_BITFLIPS) {
+			unsigned long long ec = be64_to_cpu(ech->ec);
+			unmap_peb(ai, pnum);
+			dbg_bld("Adding PEB to free: %i", pnum);
+
+			if (err == UBI_IO_FF_BITFLIPS)
+				scrub = 1;
+
+			ret = add_aeb(ai, free, pnum, ec, scrub);
+			if (ret)
+				goto out;
+			continue;
+		} else if (err == 0 || err == UBI_IO_BITFLIPS) {
+			dbg_bld("Found non empty PEB:%i in pool", pnum);
+
+			if (err == UBI_IO_BITFLIPS)
+				scrub = 1;
+
+			new_aeb = ubi_alloc_aeb(ai, pnum, be64_to_cpu(ech->ec));
+			if (!new_aeb) {
+				ret = -ENOMEM;
+				goto out;
+			}
+
+			new_aeb->lnum = be32_to_cpu(vh->lnum);
+			new_aeb->sqnum = be64_to_cpu(vh->sqnum);
+			new_aeb->copy_flag = vh->copy_flag;
+			new_aeb->scrub = scrub;
+
+			if (*max_sqnum < new_aeb->sqnum)
+				*max_sqnum = new_aeb->sqnum;
+
+			err = process_pool_aeb(ubi, ai, vh, new_aeb);
+			if (err) {
+				ret = err > 0 ? UBI_BAD_FASTMAP : err;
+				goto out;
+			}
+		} else {
+			/* We are paranoid and fall back to scanning mode */
+			ubi_err(ubi, "fastmap pool PEBs contains damaged PEBs!");
+			ret = err > 0 ? UBI_BAD_FASTMAP : err;
+			goto out;
+		}
+
+	}
+
+out:
+	ubi_free_vid_buf(vb);
+	kfree(ech);
+	return ret;
+}
+
+/**
+ * count_fastmap_pebs - Counts the PEBs found by fastmap.
+ * @ai: The UBI attach info object
+ */
+static int count_fastmap_pebs(struct ubi_attach_info *ai)
+{
+	struct ubi_ainf_peb *aeb;
+	struct ubi_ainf_volume *av;
+	struct rb_node *rb1, *rb2;
+	int n = 0;
+
+	list_for_each_entry(aeb, &ai->erase, u.list)
+		n++;
+
+	list_for_each_entry(aeb, &ai->free, u.list)
+		n++;
+
+	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb)
+		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb)
+			n++;
+
+	return n;
+}
+
+/**
+ * ubi_attach_fastmap - creates ubi_attach_info from a fastmap.
+ * @ubi: UBI device object
+ * @ai: UBI attach info object
+ * @fm: the fastmap to be attached
+ *
+ * Returns 0 on success, UBI_BAD_FASTMAP if the found fastmap was unusable.
+ * < 0 indicates an internal error.
+ */
+static int ubi_attach_fastmap(struct ubi_device *ubi,
+			      struct ubi_attach_info *ai,
+			      struct ubi_fastmap_layout *fm)
+{
+	struct list_head used, free;
+	struct ubi_ainf_volume *av;
+	struct ubi_ainf_peb *aeb, *tmp_aeb, *_tmp_aeb;
+	struct ubi_fm_sb *fmsb;
+	struct ubi_fm_hdr *fmhdr;
+	struct ubi_fm_scan_pool *fmpl, *fmpl_wl;
+	struct ubi_fm_ec *fmec;
+	struct ubi_fm_volhdr *fmvhdr;
+	struct ubi_fm_eba *fm_eba;
+	int ret, i, j, pool_size, wl_pool_size;
+	size_t fm_pos = 0, fm_size = ubi->fm_size;
+	unsigned long long max_sqnum = 0;
+	void *fm_raw = ubi->fm_buf;
+
+	INIT_LIST_HEAD(&used);
+	INIT_LIST_HEAD(&free);
+	ai->min_ec = UBI_MAX_ERASECOUNTER;
+
+	fmsb = (struct ubi_fm_sb *)(fm_raw);
+	ai->max_sqnum = fmsb->sqnum;
+	fm_pos += sizeof(struct ubi_fm_sb);
+	if (fm_pos >= fm_size)
+		goto fail_bad;
+
+	fmhdr = (struct ubi_fm_hdr *)(fm_raw + fm_pos);
+	fm_pos += sizeof(*fmhdr);
+	if (fm_pos >= fm_size)
+		goto fail_bad;
+
+	if (be32_to_cpu(fmhdr->magic) != UBI_FM_HDR_MAGIC) {
+		ubi_err(ubi, "bad fastmap header magic: 0x%x, expected: 0x%x",
+			be32_to_cpu(fmhdr->magic), UBI_FM_HDR_MAGIC);
+		goto fail_bad;
+	}
+
+	fmpl = (struct ubi_fm_scan_pool *)(fm_raw + fm_pos);
+	fm_pos += sizeof(*fmpl);
+	if (fm_pos >= fm_size)
+		goto fail_bad;
+	if (be32_to_cpu(fmpl->magic) != UBI_FM_POOL_MAGIC) {
+		ubi_err(ubi, "bad fastmap pool magic: 0x%x, expected: 0x%x",
+			be32_to_cpu(fmpl->magic), UBI_FM_POOL_MAGIC);
+		goto fail_bad;
+	}
+
+	fmpl_wl = (struct ubi_fm_scan_pool *)(fm_raw + fm_pos);
+	fm_pos += sizeof(*fmpl_wl);
+	if (fm_pos >= fm_size)
+		goto fail_bad;
+	if (be32_to_cpu(fmpl_wl->magic) != UBI_FM_POOL_MAGIC) {
+		ubi_err(ubi, "bad fastmap WL pool magic: 0x%x, expected: 0x%x",
+			be32_to_cpu(fmpl_wl->magic), UBI_FM_POOL_MAGIC);
+		goto fail_bad;
+	}
+
+	pool_size = be16_to_cpu(fmpl->size);
+	wl_pool_size = be16_to_cpu(fmpl_wl->size);
+	fm->max_pool_size = be16_to_cpu(fmpl->max_size);
+	fm->max_wl_pool_size = be16_to_cpu(fmpl_wl->max_size);
+
+	if (pool_size > UBI_FM_MAX_POOL_SIZE || pool_size < 0) {
+		ubi_err(ubi, "bad pool size: %i", pool_size);
+		goto fail_bad;
+	}
+
+	if (wl_pool_size > UBI_FM_MAX_POOL_SIZE || wl_pool_size < 0) {
+		ubi_err(ubi, "bad WL pool size: %i", wl_pool_size);
+		goto fail_bad;
+	}
+
+
+	if (fm->max_pool_size > UBI_FM_MAX_POOL_SIZE ||
+	    fm->max_pool_size < 0) {
+		ubi_err(ubi, "bad maximal pool size: %i", fm->max_pool_size);
+		goto fail_bad;
+	}
+
+	if (fm->max_wl_pool_size > UBI_FM_MAX_POOL_SIZE ||
+	    fm->max_wl_pool_size < 0) {
+		ubi_err(ubi, "bad maximal WL pool size: %i",
+			fm->max_wl_pool_size);
+		goto fail_bad;
+	}
+
+	/* read EC values from free list */
+	for (i = 0; i < be32_to_cpu(fmhdr->free_peb_count); i++) {
+		fmec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*fmec);
+		if (fm_pos >= fm_size)
+			goto fail_bad;
+
+		ret = add_aeb(ai, &ai->free, be32_to_cpu(fmec->pnum),
+			      be32_to_cpu(fmec->ec), 0);
+		if (ret)
+			goto fail;
+	}
+
+	/* read EC values from used list */
+	for (i = 0; i < be32_to_cpu(fmhdr->used_peb_count); i++) {
+		fmec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*fmec);
+		if (fm_pos >= fm_size)
+			goto fail_bad;
+
+		ret = add_aeb(ai, &used, be32_to_cpu(fmec->pnum),
+			      be32_to_cpu(fmec->ec), 0);
+		if (ret)
+			goto fail;
+	}
+
+	/* read EC values from scrub list */
+	for (i = 0; i < be32_to_cpu(fmhdr->scrub_peb_count); i++) {
+		fmec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*fmec);
+		if (fm_pos >= fm_size)
+			goto fail_bad;
+
+		ret = add_aeb(ai, &used, be32_to_cpu(fmec->pnum),
+			      be32_to_cpu(fmec->ec), 1);
+		if (ret)
+			goto fail;
+	}
+
+	/* read EC values from erase list */
+	for (i = 0; i < be32_to_cpu(fmhdr->erase_peb_count); i++) {
+		fmec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*fmec);
+		if (fm_pos >= fm_size)
+			goto fail_bad;
+
+		ret = add_aeb(ai, &ai->erase, be32_to_cpu(fmec->pnum),
+			      be32_to_cpu(fmec->ec), 1);
+		if (ret)
+			goto fail;
+	}
+
+	ai->mean_ec = div_u64(ai->ec_sum, ai->ec_count);
+	ai->bad_peb_count = be32_to_cpu(fmhdr->bad_peb_count);
+
+	/* Iterate over all volumes and read their EBA table */
+	for (i = 0; i < be32_to_cpu(fmhdr->vol_count); i++) {
+		fmvhdr = (struct ubi_fm_volhdr *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*fmvhdr);
+		if (fm_pos >= fm_size)
+			goto fail_bad;
+
+		if (be32_to_cpu(fmvhdr->magic) != UBI_FM_VHDR_MAGIC) {
+			ubi_err(ubi, "bad fastmap vol header magic: 0x%x, expected: 0x%x",
+				be32_to_cpu(fmvhdr->magic), UBI_FM_VHDR_MAGIC);
+			goto fail_bad;
+		}
+
+		av = add_vol(ai, be32_to_cpu(fmvhdr->vol_id),
+			     be32_to_cpu(fmvhdr->used_ebs),
+			     be32_to_cpu(fmvhdr->data_pad),
+			     fmvhdr->vol_type,
+			     be32_to_cpu(fmvhdr->last_eb_bytes));
+
+		if (IS_ERR(av)) {
+			if (PTR_ERR(av) == -EEXIST)
+				ubi_err(ubi, "volume (ID %i) already exists",
+					fmvhdr->vol_id);
+
+			goto fail_bad;
+		}
+
+		ai->vols_found++;
+		if (ai->highest_vol_id < be32_to_cpu(fmvhdr->vol_id))
+			ai->highest_vol_id = be32_to_cpu(fmvhdr->vol_id);
+
+		fm_eba = (struct ubi_fm_eba *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*fm_eba);
+		fm_pos += (sizeof(__be32) * be32_to_cpu(fm_eba->reserved_pebs));
+		if (fm_pos >= fm_size)
+			goto fail_bad;
+
+		if (be32_to_cpu(fm_eba->magic) != UBI_FM_EBA_MAGIC) {
+			ubi_err(ubi, "bad fastmap EBA header magic: 0x%x, expected: 0x%x",
+				be32_to_cpu(fm_eba->magic), UBI_FM_EBA_MAGIC);
+			goto fail_bad;
+		}
+
+		for (j = 0; j < be32_to_cpu(fm_eba->reserved_pebs); j++) {
+			int pnum = be32_to_cpu(fm_eba->pnum[j]);
+
+			if (pnum < 0)
+				continue;
+
+			aeb = NULL;
+			list_for_each_entry(tmp_aeb, &used, u.list) {
+				if (tmp_aeb->pnum == pnum) {
+					aeb = tmp_aeb;
+					break;
+				}
+			}
+
+			if (!aeb) {
+				ubi_err(ubi, "PEB %i is in EBA but not in used list", pnum);
+				goto fail_bad;
+			}
+
+			aeb->lnum = j;
+
+			if (av->highest_lnum <= aeb->lnum)
+				av->highest_lnum = aeb->lnum;
+
+			assign_aeb_to_av(ai, aeb, av);
+
+			dbg_bld("inserting PEB:%i (LEB %i) to vol %i",
+				aeb->pnum, aeb->lnum, av->vol_id);
+		}
+	}
+
+	ret = scan_pool(ubi, ai, fmpl->pebs, pool_size, &max_sqnum, &free);
+	if (ret)
+		goto fail;
+
+	ret = scan_pool(ubi, ai, fmpl_wl->pebs, wl_pool_size, &max_sqnum, &free);
+	if (ret)
+		goto fail;
+
+	if (max_sqnum > ai->max_sqnum)
+		ai->max_sqnum = max_sqnum;
+
+	list_for_each_entry_safe(tmp_aeb, _tmp_aeb, &free, u.list)
+		list_move_tail(&tmp_aeb->u.list, &ai->free);
+
+	list_for_each_entry_safe(tmp_aeb, _tmp_aeb, &used, u.list)
+		list_move_tail(&tmp_aeb->u.list, &ai->erase);
+
+	ubi_assert(list_empty(&free));
+
+	/*
+	 * If fastmap is leaking PEBs (must not happen), raise a
+	 * fat warning and fall back to scanning mode.
+	 * We do this here because in ubi_wl_init() it's too late
+	 * and we cannot fall back to scanning.
+	 */
+	if (WARN_ON(count_fastmap_pebs(ai) != ubi->peb_count -
+		    ai->bad_peb_count - fm->used_blocks))
+		goto fail_bad;
+
+	return 0;
+
+fail_bad:
+	ret = UBI_BAD_FASTMAP;
+fail:
+	list_for_each_entry_safe(tmp_aeb, _tmp_aeb, &used, u.list) {
+		list_del(&tmp_aeb->u.list);
+		ubi_free_aeb(ai, tmp_aeb);
+	}
+	list_for_each_entry_safe(tmp_aeb, _tmp_aeb, &free, u.list) {
+		list_del(&tmp_aeb->u.list);
+		ubi_free_aeb(ai, tmp_aeb);
+	}
+
+	return ret;
+}
+
+/**
+ * find_fm_anchor - find the most recent Fastmap superblock (anchor)
+ * @ai: UBI attach info to be filled
+ */
+static int find_fm_anchor(struct ubi_attach_info *ai)
+{
+	int ret = -1;
+	struct ubi_ainf_peb *aeb;
+	unsigned long long max_sqnum = 0;
+
+	list_for_each_entry(aeb, &ai->fastmap, u.list) {
+		if (aeb->vol_id == UBI_FM_SB_VOLUME_ID && aeb->sqnum > max_sqnum) {
+			max_sqnum = aeb->sqnum;
+			ret = aeb->pnum;
+		}
+	}
+
+	return ret;
+}
+
+static struct ubi_ainf_peb *clone_aeb(struct ubi_attach_info *ai,
+				      struct ubi_ainf_peb *old)
+{
+	struct ubi_ainf_peb *new;
+
+	new = ubi_alloc_aeb(ai, old->pnum, old->ec);
+	if (!new)
+		return NULL;
+
+	new->vol_id = old->vol_id;
+	new->sqnum = old->sqnum;
+	new->lnum = old->lnum;
+	new->scrub = old->scrub;
+	new->copy_flag = old->copy_flag;
+
+	return new;
+}
+
+/**
+ * ubi_scan_fastmap - scan the fastmap.
+ * @ubi: UBI device object
+ * @ai: UBI attach info to be filled
+ * @scan_ai: UBI attach info from the first 64 PEBs,
+ *           used to find the most recent Fastmap data structure
+ *
+ * Returns 0 on success, UBI_NO_FASTMAP if no fastmap was found,
+ * UBI_BAD_FASTMAP if one was found but is not usable.
+ * < 0 indicates an internal error.
+ */
+int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
+		     struct ubi_attach_info *scan_ai)
+{
+	struct ubi_fm_sb *fmsb, *fmsb2;
+	struct ubi_vid_io_buf *vb;
+	struct ubi_vid_hdr *vh;
+	struct ubi_ec_hdr *ech;
+	struct ubi_fastmap_layout *fm;
+	struct ubi_ainf_peb *aeb;
+	int i, used_blocks, pnum, fm_anchor, ret = 0;
+	size_t fm_size;
+	__be32 crc, tmp_crc;
+	unsigned long long sqnum = 0;
+
+	fm_anchor = find_fm_anchor(scan_ai);
+	if (fm_anchor < 0)
+		return UBI_NO_FASTMAP;
+
+	/* Copy all (possible) fastmap blocks into our new attach structure. */
+	list_for_each_entry(aeb, &scan_ai->fastmap, u.list) {
+		struct ubi_ainf_peb *new;
+
+		new = clone_aeb(ai, aeb);
+		if (!new)
+			return -ENOMEM;
+
+		list_add(&new->u.list, &ai->fastmap);
+	}
+
+	down_write(&ubi->fm_protect);
+	memset(ubi->fm_buf, 0, ubi->fm_size);
+
+	fmsb = kmalloc(sizeof(*fmsb), GFP_KERNEL);
+	if (!fmsb) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	fm = kzalloc(sizeof(*fm), GFP_KERNEL);
+	if (!fm) {
+		ret = -ENOMEM;
+		kfree(fmsb);
+		goto out;
+	}
+
+	ret = ubi_io_read_data(ubi, fmsb, fm_anchor, 0, sizeof(*fmsb));
+	if (ret && ret != UBI_IO_BITFLIPS)
+		goto free_fm_sb;
+	else if (ret == UBI_IO_BITFLIPS)
+		fm->to_be_tortured[0] = 1;
+
+	if (be32_to_cpu(fmsb->magic) != UBI_FM_SB_MAGIC) {
+		ubi_err(ubi, "bad super block magic: 0x%x, expected: 0x%x",
+			be32_to_cpu(fmsb->magic), UBI_FM_SB_MAGIC);
+		ret = UBI_BAD_FASTMAP;
+		goto free_fm_sb;
+	}
+
+	if (fmsb->version != UBI_FM_FMT_VERSION) {
+		ubi_err(ubi, "bad fastmap version: %i, expected: %i",
+			fmsb->version, UBI_FM_FMT_VERSION);
+		ret = UBI_BAD_FASTMAP;
+		goto free_fm_sb;
+	}
+
+	used_blocks = be32_to_cpu(fmsb->used_blocks);
+	if (used_blocks > UBI_FM_MAX_BLOCKS || used_blocks < 1) {
+		ubi_err(ubi, "number of fastmap blocks is invalid: %i",
+			used_blocks);
+		ret = UBI_BAD_FASTMAP;
+		goto free_fm_sb;
+	}
+
+	fm_size = ubi->leb_size * used_blocks;
+	if (fm_size != ubi->fm_size) {
+		ubi_err(ubi, "bad fastmap size: %zi, expected: %zi",
+			fm_size, ubi->fm_size);
+		ret = UBI_BAD_FASTMAP;
+		goto free_fm_sb;
+	}
+
+	ech = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!ech) {
+		ret = -ENOMEM;
+		goto free_fm_sb;
+	}
+
+	vb = ubi_alloc_vid_buf(ubi, GFP_KERNEL);
+	if (!vb) {
+		ret = -ENOMEM;
+		goto free_hdr;
+	}
+
+	vh = ubi_get_vid_hdr(vb);
+
+	for (i = 0; i < used_blocks; i++) {
+		int image_seq;
+
+		pnum = be32_to_cpu(fmsb->block_loc[i]);
+
+		if (ubi_io_is_bad(ubi, pnum)) {
+			ret = UBI_BAD_FASTMAP;
+			goto free_hdr;
+		}
+
+		if (i == 0 && pnum != fm_anchor) {
+			ubi_err(ubi, "Fastmap anchor PEB mismatch: PEB: %i vs. %i",
+				pnum, fm_anchor);
+			ret = UBI_BAD_FASTMAP;
+			goto free_hdr;
+		}
+
+		ret = ubi_io_read_ec_hdr(ubi, pnum, ech, 0);
+		if (ret && ret != UBI_IO_BITFLIPS) {
+			ubi_err(ubi, "unable to read fastmap block# %i EC (PEB: %i)",
+				i, pnum);
+			if (ret > 0)
+				ret = UBI_BAD_FASTMAP;
+			goto free_hdr;
+		} else if (ret == UBI_IO_BITFLIPS)
+			fm->to_be_tortured[i] = 1;
+
+		image_seq = be32_to_cpu(ech->image_seq);
+		if (!ubi->image_seq)
+			ubi->image_seq = image_seq;
+
+		/*
+		 * Older UBI implementations have image_seq set to zero, so
+		 * we shouldn't fail if image_seq == 0.
+		 */
+		if (image_seq && (image_seq != ubi->image_seq)) {
+			ubi_err(ubi, "wrong image seq:%d instead of %d",
+				be32_to_cpu(ech->image_seq), ubi->image_seq);
+			ret = UBI_BAD_FASTMAP;
+			goto free_hdr;
+		}
+
+		ret = ubi_io_read_vid_hdr(ubi, pnum, vb, 0);
+		if (ret && ret != UBI_IO_BITFLIPS) {
+			ubi_err(ubi, "unable to read fastmap block# %i (PEB: %i)",
+				i, pnum);
+			goto free_hdr;
+		}
+
+		if (i == 0) {
+			if (be32_to_cpu(vh->vol_id) != UBI_FM_SB_VOLUME_ID) {
+				ubi_err(ubi, "bad fastmap anchor vol_id: 0x%x, expected: 0x%x",
+					be32_to_cpu(vh->vol_id),
+					UBI_FM_SB_VOLUME_ID);
+				ret = UBI_BAD_FASTMAP;
+				goto free_hdr;
+			}
+		} else {
+			if (be32_to_cpu(vh->vol_id) != UBI_FM_DATA_VOLUME_ID) {
+				ubi_err(ubi, "bad fastmap data vol_id: 0x%x, expected: 0x%x",
+					be32_to_cpu(vh->vol_id),
+					UBI_FM_DATA_VOLUME_ID);
+				ret = UBI_BAD_FASTMAP;
+				goto free_hdr;
+			}
+		}
+
+		if (sqnum < be64_to_cpu(vh->sqnum))
+			sqnum = be64_to_cpu(vh->sqnum);
+
+		ret = ubi_io_read_data(ubi, ubi->fm_buf + (ubi->leb_size * i),
+				       pnum, 0, ubi->leb_size);
+		if (ret && ret != UBI_IO_BITFLIPS) {
+			ubi_err(ubi, "unable to read fastmap block# %i (PEB: %i, "
+				"err: %i)", i, pnum, ret);
+			goto free_hdr;
+		}
+	}
+
+	kfree(fmsb);
+	fmsb = NULL;
+
+	fmsb2 = (struct ubi_fm_sb *)(ubi->fm_buf);
+	tmp_crc = be32_to_cpu(fmsb2->data_crc);
+	fmsb2->data_crc = 0;
+	crc = crc32(UBI_CRC32_INIT, ubi->fm_buf, fm_size);
+	if (crc != tmp_crc) {
+		ubi_err(ubi, "fastmap data CRC is invalid");
+		ubi_err(ubi, "CRC should be: 0x%x, calc: 0x%x",
+			tmp_crc, crc);
+		ret = UBI_BAD_FASTMAP;
+		goto free_hdr;
+	}
+
+	fmsb2->sqnum = sqnum;
+
+	fm->used_blocks = used_blocks;
+
+	ret = ubi_attach_fastmap(ubi, ai, fm);
+	if (ret) {
+		if (ret > 0)
+			ret = UBI_BAD_FASTMAP;
+		goto free_hdr;
+	}
+
+	for (i = 0; i < used_blocks; i++) {
+		struct ubi_wl_entry *e;
+
+		e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
+		if (!e) {
+			while (i--)
+				kmem_cache_free(ubi_wl_entry_slab, fm->e[i]);
+
+			ret = -ENOMEM;
+			goto free_hdr;
+		}
+
+		e->pnum = be32_to_cpu(fmsb2->block_loc[i]);
+		e->ec = be32_to_cpu(fmsb2->block_ec[i]);
+		fm->e[i] = e;
+	}
+
+	ubi->fm = fm;
+	ubi->fm_pool.max_size = ubi->fm->max_pool_size;
+	ubi->fm_wl_pool.max_size = ubi->fm->max_wl_pool_size;
+	ubi_msg(ubi, "attached by fastmap");
+	ubi_msg(ubi, "fastmap pool size: %d", ubi->fm_pool.max_size);
+	ubi_msg(ubi, "fastmap WL pool size: %d",
+		ubi->fm_wl_pool.max_size);
+	ubi->fm_disabled = 0;
+	ubi->fast_attach = 1;
+
+	ubi_free_vid_buf(vb);
+	kfree(ech);
+out:
+	up_write(&ubi->fm_protect);
+	if (ret == UBI_BAD_FASTMAP)
+		ubi_err(ubi, "Attach by fastmap failed, doing a full scan!");
+	return ret;
+
+free_hdr:
+	ubi_free_vid_buf(vb);
+	kfree(ech);
+free_fm_sb:
+	kfree(fmsb);
+	kfree(fm);
+	goto out;
+}
+
+int ubi_fastmap_init_checkmap(struct ubi_volume *vol, int leb_count)
+{
+	struct ubi_device *ubi = vol->ubi;
+
+	if (!ubi->fast_attach)
+		return 0;
+
+	vol->checkmap = bitmap_zalloc(leb_count, GFP_KERNEL);
+	if (!vol->checkmap)
+		return -ENOMEM;
+
+	return 0;
+}
+
+void ubi_fastmap_destroy_checkmap(struct ubi_volume *vol)
+{
+	bitmap_free(vol->checkmap);
+}
+
+/**
+ * ubi_write_fastmap - writes a fastmap.
+ * @ubi: UBI device object
+ * @new_fm: the to be written fastmap
+ *
+ * Returns 0 on success, < 0 indicates an internal error.
+ */
+static int ubi_write_fastmap(struct ubi_device *ubi,
+			     struct ubi_fastmap_layout *new_fm)
+{
+	size_t fm_pos = 0;
+	void *fm_raw;
+	struct ubi_fm_sb *fmsb;
+	struct ubi_fm_hdr *fmh;
+	struct ubi_fm_scan_pool *fmpl, *fmpl_wl;
+	struct ubi_fm_ec *fec;
+	struct ubi_fm_volhdr *fvh;
+	struct ubi_fm_eba *feba;
+	struct ubi_wl_entry *wl_e;
+	struct ubi_volume *vol;
+	struct ubi_vid_io_buf *avbuf, *dvbuf;
+	struct ubi_vid_hdr *avhdr, *dvhdr;
+	struct ubi_work *ubi_wrk;
+	struct rb_node *tmp_rb;
+	int ret, i, j, free_peb_count, used_peb_count, vol_count;
+	int scrub_peb_count, erase_peb_count;
+	unsigned long *seen_pebs;
+
+	fm_raw = ubi->fm_buf;
+	memset(ubi->fm_buf, 0, ubi->fm_size);
+
+	avbuf = new_fm_vbuf(ubi, UBI_FM_SB_VOLUME_ID);
+	if (!avbuf) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	dvbuf = new_fm_vbuf(ubi, UBI_FM_DATA_VOLUME_ID);
+	if (!dvbuf) {
+		ret = -ENOMEM;
+		goto out_free_avbuf;
+	}
+
+	avhdr = ubi_get_vid_hdr(avbuf);
+	dvhdr = ubi_get_vid_hdr(dvbuf);
+
+	seen_pebs = init_seen(ubi);
+	if (IS_ERR(seen_pebs)) {
+		ret = PTR_ERR(seen_pebs);
+		goto out_free_dvbuf;
+	}
+
+	spin_lock(&ubi->volumes_lock);
+	spin_lock(&ubi->wl_lock);
+
+	fmsb = (struct ubi_fm_sb *)fm_raw;
+	fm_pos += sizeof(*fmsb);
+	ubi_assert(fm_pos <= ubi->fm_size);
+
+	fmh = (struct ubi_fm_hdr *)(fm_raw + fm_pos);
+	fm_pos += sizeof(*fmh);
+	ubi_assert(fm_pos <= ubi->fm_size);
+
+	fmsb->magic = cpu_to_be32(UBI_FM_SB_MAGIC);
+	fmsb->version = UBI_FM_FMT_VERSION;
+	fmsb->used_blocks = cpu_to_be32(new_fm->used_blocks);
+	/* the max sqnum will be filled in while *reading* the fastmap */
+	fmsb->sqnum = 0;
+
+	fmh->magic = cpu_to_be32(UBI_FM_HDR_MAGIC);
+	free_peb_count = 0;
+	used_peb_count = 0;
+	scrub_peb_count = 0;
+	erase_peb_count = 0;
+	vol_count = 0;
+
+	fmpl = (struct ubi_fm_scan_pool *)(fm_raw + fm_pos);
+	fm_pos += sizeof(*fmpl);
+	fmpl->magic = cpu_to_be32(UBI_FM_POOL_MAGIC);
+	fmpl->size = cpu_to_be16(ubi->fm_pool.size);
+	fmpl->max_size = cpu_to_be16(ubi->fm_pool.max_size);
+
+	for (i = 0; i < ubi->fm_pool.size; i++) {
+		fmpl->pebs[i] = cpu_to_be32(ubi->fm_pool.pebs[i]);
+		set_seen(ubi, ubi->fm_pool.pebs[i], seen_pebs);
+	}
+
+	fmpl_wl = (struct ubi_fm_scan_pool *)(fm_raw + fm_pos);
+	fm_pos += sizeof(*fmpl_wl);
+	fmpl_wl->magic = cpu_to_be32(UBI_FM_POOL_MAGIC);
+	fmpl_wl->size = cpu_to_be16(ubi->fm_wl_pool.size);
+	fmpl_wl->max_size = cpu_to_be16(ubi->fm_wl_pool.max_size);
+
+	for (i = 0; i < ubi->fm_wl_pool.size; i++) {
+		fmpl_wl->pebs[i] = cpu_to_be32(ubi->fm_wl_pool.pebs[i]);
+		set_seen(ubi, ubi->fm_wl_pool.pebs[i], seen_pebs);
+	}
+
+	ubi_for_each_free_peb(ubi, wl_e, tmp_rb) {
+		fec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+
+		fec->pnum = cpu_to_be32(wl_e->pnum);
+		set_seen(ubi, wl_e->pnum, seen_pebs);
+		fec->ec = cpu_to_be32(wl_e->ec);
+
+		free_peb_count++;
+		fm_pos += sizeof(*fec);
+		ubi_assert(fm_pos <= ubi->fm_size);
+	}
+	fmh->free_peb_count = cpu_to_be32(free_peb_count);
+
+	ubi_for_each_used_peb(ubi, wl_e, tmp_rb) {
+		fec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+
+		fec->pnum = cpu_to_be32(wl_e->pnum);
+		set_seen(ubi, wl_e->pnum, seen_pebs);
+		fec->ec = cpu_to_be32(wl_e->ec);
+
+		used_peb_count++;
+		fm_pos += sizeof(*fec);
+		ubi_assert(fm_pos <= ubi->fm_size);
+	}
+
+	ubi_for_each_protected_peb(ubi, i, wl_e) {
+		fec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+
+		fec->pnum = cpu_to_be32(wl_e->pnum);
+		set_seen(ubi, wl_e->pnum, seen_pebs);
+		fec->ec = cpu_to_be32(wl_e->ec);
+
+		used_peb_count++;
+		fm_pos += sizeof(*fec);
+		ubi_assert(fm_pos <= ubi->fm_size);
+	}
+	fmh->used_peb_count = cpu_to_be32(used_peb_count);
+
+	ubi_for_each_scrub_peb(ubi, wl_e, tmp_rb) {
+		fec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+
+		fec->pnum = cpu_to_be32(wl_e->pnum);
+		set_seen(ubi, wl_e->pnum, seen_pebs);
+		fec->ec = cpu_to_be32(wl_e->ec);
+
+		scrub_peb_count++;
+		fm_pos += sizeof(*fec);
+		ubi_assert(fm_pos <= ubi->fm_size);
+	}
+	fmh->scrub_peb_count = cpu_to_be32(scrub_peb_count);
+
+
+	list_for_each_entry(ubi_wrk, &ubi->works, list) {
+		if (ubi_is_erase_work(ubi_wrk)) {
+			wl_e = ubi_wrk->e;
+			ubi_assert(wl_e);
+
+			fec = (struct ubi_fm_ec *)(fm_raw + fm_pos);
+
+			fec->pnum = cpu_to_be32(wl_e->pnum);
+			set_seen(ubi, wl_e->pnum, seen_pebs);
+			fec->ec = cpu_to_be32(wl_e->ec);
+
+			erase_peb_count++;
+			fm_pos += sizeof(*fec);
+			ubi_assert(fm_pos <= ubi->fm_size);
+		}
+	}
+	fmh->erase_peb_count = cpu_to_be32(erase_peb_count);
+
+	for (i = 0; i < UBI_MAX_VOLUMES + UBI_INT_VOL_COUNT; i++) {
+		vol = ubi->volumes[i];
+
+		if (!vol)
+			continue;
+
+		vol_count++;
+
+		fvh = (struct ubi_fm_volhdr *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*fvh);
+		ubi_assert(fm_pos <= ubi->fm_size);
+
+		fvh->magic = cpu_to_be32(UBI_FM_VHDR_MAGIC);
+		fvh->vol_id = cpu_to_be32(vol->vol_id);
+		fvh->vol_type = vol->vol_type;
+		fvh->used_ebs = cpu_to_be32(vol->used_ebs);
+		fvh->data_pad = cpu_to_be32(vol->data_pad);
+		fvh->last_eb_bytes = cpu_to_be32(vol->last_eb_bytes);
+
+		ubi_assert(vol->vol_type == UBI_DYNAMIC_VOLUME ||
+			vol->vol_type == UBI_STATIC_VOLUME);
+
+		feba = (struct ubi_fm_eba *)(fm_raw + fm_pos);
+		fm_pos += sizeof(*feba) + (sizeof(__be32) * vol->reserved_pebs);
+		ubi_assert(fm_pos <= ubi->fm_size);
+
+		for (j = 0; j < vol->reserved_pebs; j++) {
+			struct ubi_eba_leb_desc ldesc;
+
+			ubi_eba_get_ldesc(vol, j, &ldesc);
+			feba->pnum[j] = cpu_to_be32(ldesc.pnum);
+		}
+
+		feba->reserved_pebs = cpu_to_be32(j);
+		feba->magic = cpu_to_be32(UBI_FM_EBA_MAGIC);
+	}
+	fmh->vol_count = cpu_to_be32(vol_count);
+	fmh->bad_peb_count = cpu_to_be32(ubi->bad_peb_count);
+
+	avhdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
+	avhdr->lnum = 0;
+
+	spin_unlock(&ubi->wl_lock);
+	spin_unlock(&ubi->volumes_lock);
+
+	dbg_bld("writing fastmap SB to PEB %i", new_fm->e[0]->pnum);
+	ret = ubi_io_write_vid_hdr(ubi, new_fm->e[0]->pnum, avbuf);
+	if (ret) {
+		ubi_err(ubi, "unable to write vid_hdr to fastmap SB!");
+		goto out_free_seen;
+	}
+
+	for (i = 0; i < new_fm->used_blocks; i++) {
+		fmsb->block_loc[i] = cpu_to_be32(new_fm->e[i]->pnum);
+		set_seen(ubi, new_fm->e[i]->pnum, seen_pebs);
+		fmsb->block_ec[i] = cpu_to_be32(new_fm->e[i]->ec);
+	}
+
+	fmsb->data_crc = 0;
+	fmsb->data_crc = cpu_to_be32(crc32(UBI_CRC32_INIT, fm_raw,
+					   ubi->fm_size));
+
+	for (i = 1; i < new_fm->used_blocks; i++) {
+		dvhdr->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
+		dvhdr->lnum = cpu_to_be32(i);
+		dbg_bld("writing fastmap data to PEB %i sqnum %llu",
+			new_fm->e[i]->pnum, be64_to_cpu(dvhdr->sqnum));
+		ret = ubi_io_write_vid_hdr(ubi, new_fm->e[i]->pnum, dvbuf);
+		if (ret) {
+			ubi_err(ubi, "unable to write vid_hdr to PEB %i!",
+				new_fm->e[i]->pnum);
+			goto out_free_seen;
+		}
+	}
+
+	for (i = 0; i < new_fm->used_blocks; i++) {
+		ret = ubi_io_write_data(ubi, fm_raw + (i * ubi->leb_size),
+					new_fm->e[i]->pnum, 0, ubi->leb_size);
+		if (ret) {
+			ubi_err(ubi, "unable to write fastmap to PEB %i!",
+				new_fm->e[i]->pnum);
+			goto out_free_seen;
+		}
+	}
+
+	ubi_assert(new_fm);
+	ubi->fm = new_fm;
+
+	ret = self_check_seen(ubi, seen_pebs);
+	dbg_bld("fastmap written!");
+
+out_free_seen:
+	free_seen(seen_pebs);
+out_free_dvbuf:
+	ubi_free_vid_buf(dvbuf);
+out_free_avbuf:
+	ubi_free_vid_buf(avbuf);
+
+out:
+	return ret;
+}
+
+/**
+ * erase_block - Manually erase a PEB.
+ * @ubi: UBI device object
+ * @pnum: PEB to be erased
+ *
+ * Returns the new EC value on success, < 0 indicates an internal error.
+ */
+static int erase_block(struct ubi_device *ubi, int pnum)
+{
+	int ret;
+	struct ubi_ec_hdr *ec_hdr;
+	long long ec;
+
+	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL);
+	if (!ec_hdr)
+		return -ENOMEM;
+
+	ret = ubi_io_read_ec_hdr(ubi, pnum, ec_hdr, 0);
+	if (ret < 0)
+		goto out;
+	else if (ret && ret != UBI_IO_BITFLIPS) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ret = ubi_io_sync_erase(ubi, pnum, 0);
+	if (ret < 0)
+		goto out;
+
+	ec = be64_to_cpu(ec_hdr->ec);
+	ec += ret;
+	if (ec > UBI_MAX_ERASECOUNTER) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	ec_hdr->ec = cpu_to_be64(ec);
+	ret = ubi_io_write_ec_hdr(ubi, pnum, ec_hdr);
+	if (ret < 0)
+		goto out;
+
+	ret = ec;
+out:
+	kfree(ec_hdr);
+	return ret;
+}
+
+/**
+ * invalidate_fastmap - destroys a fastmap.
+ * @ubi: UBI device object
+ *
+ * This function ensures that upon next UBI attach a full scan
+ * is issued. We need this if UBI is about to write a new fastmap
+ * but is unable to do so. In this case we have two options:
+ * a) Make sure that the current fastmap will not be usued upon
+ * attach time and contine or b) fall back to RO mode to have the
+ * current fastmap in a valid state.
+ * Returns 0 on success, < 0 indicates an internal error.
+ */
+static int invalidate_fastmap(struct ubi_device *ubi)
+{
+	int ret;
+	struct ubi_fastmap_layout *fm;
+	struct ubi_wl_entry *e;
+	struct ubi_vid_io_buf *vb = NULL;
+	struct ubi_vid_hdr *vh;
+
+	if (!ubi->fm)
+		return 0;
+
+	ubi->fm = NULL;
+
+	ret = -ENOMEM;
+	fm = kzalloc(sizeof(*fm), GFP_KERNEL);
+	if (!fm)
+		goto out;
+
+	vb = new_fm_vbuf(ubi, UBI_FM_SB_VOLUME_ID);
+	if (!vb)
+		goto out_free_fm;
+
+	vh = ubi_get_vid_hdr(vb);
+
+	ret = -ENOSPC;
+	e = ubi_wl_get_fm_peb(ubi, 1);
+	if (!e)
+		goto out_free_fm;
+
+	/*
+	 * Create fake fastmap such that UBI will fall back
+	 * to scanning mode.
+	 */
+	vh->sqnum = cpu_to_be64(ubi_next_sqnum(ubi));
+	ret = ubi_io_write_vid_hdr(ubi, e->pnum, vb);
+	if (ret < 0) {
+		ubi_wl_put_fm_peb(ubi, e, 0, 0);
+		goto out_free_fm;
+	}
+
+	fm->used_blocks = 1;
+	fm->e[0] = e;
+
+	ubi->fm = fm;
+
+out:
+	ubi_free_vid_buf(vb);
+	return ret;
+
+out_free_fm:
+	kfree(fm);
+	goto out;
+}
+
+/**
+ * return_fm_pebs - returns all PEBs used by a fastmap back to the
+ * WL sub-system.
+ * @ubi: UBI device object
+ * @fm: fastmap layout object
+ */
+static void return_fm_pebs(struct ubi_device *ubi,
+			   struct ubi_fastmap_layout *fm)
+{
+	int i;
+
+	if (!fm)
+		return;
+
+	for (i = 0; i < fm->used_blocks; i++) {
+		if (fm->e[i]) {
+			ubi_wl_put_fm_peb(ubi, fm->e[i], i,
+					  fm->to_be_tortured[i]);
+			fm->e[i] = NULL;
+		}
+	}
+}
+
+/**
+ * ubi_update_fastmap - will be called by UBI if a volume changes or
+ * a fastmap pool becomes full.
+ * @ubi: UBI device object
+ *
+ * Returns 0 on success, < 0 indicates an internal error.
+ */
+int ubi_update_fastmap(struct ubi_device *ubi)
+{
+	int ret, i, j;
+	struct ubi_fastmap_layout *new_fm, *old_fm;
+	struct ubi_wl_entry *tmp_e;
+
+	down_write(&ubi->fm_protect);
+	down_write(&ubi->work_sem);
+	down_write(&ubi->fm_eba_sem);
+
+	ubi_refill_pools(ubi);
+
+	if (ubi->ro_mode || ubi->fm_disabled) {
+		up_write(&ubi->fm_eba_sem);
+		up_write(&ubi->work_sem);
+		up_write(&ubi->fm_protect);
+		return 0;
+	}
+
+	new_fm = kzalloc(sizeof(*new_fm), GFP_KERNEL);
+	if (!new_fm) {
+		up_write(&ubi->fm_eba_sem);
+		up_write(&ubi->work_sem);
+		up_write(&ubi->fm_protect);
+		return -ENOMEM;
+	}
+
+	new_fm->used_blocks = ubi->fm_size / ubi->leb_size;
+	old_fm = ubi->fm;
+	ubi->fm = NULL;
+
+	if (new_fm->used_blocks > UBI_FM_MAX_BLOCKS) {
+		ubi_err(ubi, "fastmap too large");
+		ret = -ENOSPC;
+		goto err;
+	}
+
+	for (i = 1; i < new_fm->used_blocks; i++) {
+		spin_lock(&ubi->wl_lock);
+		tmp_e = ubi_wl_get_fm_peb(ubi, 0);
+		spin_unlock(&ubi->wl_lock);
+
+		if (!tmp_e) {
+			if (old_fm && old_fm->e[i]) {
+				ret = erase_block(ubi, old_fm->e[i]->pnum);
+				if (ret < 0) {
+					ubi_err(ubi, "could not erase old fastmap PEB");
+
+					for (j = 1; j < i; j++) {
+						ubi_wl_put_fm_peb(ubi, new_fm->e[j],
+								  j, 0);
+						new_fm->e[j] = NULL;
+					}
+					goto err;
+				}
+				new_fm->e[i] = old_fm->e[i];
+				old_fm->e[i] = NULL;
+			} else {
+				ubi_err(ubi, "could not get any free erase block");
+
+				for (j = 1; j < i; j++) {
+					ubi_wl_put_fm_peb(ubi, new_fm->e[j], j, 0);
+					new_fm->e[j] = NULL;
+				}
+
+				ret = -ENOSPC;
+				goto err;
+			}
+		} else {
+			new_fm->e[i] = tmp_e;
+
+			if (old_fm && old_fm->e[i]) {
+				ubi_wl_put_fm_peb(ubi, old_fm->e[i], i,
+						  old_fm->to_be_tortured[i]);
+				old_fm->e[i] = NULL;
+			}
+		}
+	}
+
+	/* Old fastmap is larger than the new one */
+	if (old_fm && new_fm->used_blocks < old_fm->used_blocks) {
+		for (i = new_fm->used_blocks; i < old_fm->used_blocks; i++) {
+			ubi_wl_put_fm_peb(ubi, old_fm->e[i], i,
+					  old_fm->to_be_tortured[i]);
+			old_fm->e[i] = NULL;
+		}
+	}
+
+	spin_lock(&ubi->wl_lock);
+	tmp_e = ubi->fm_anchor;
+	ubi->fm_anchor = NULL;
+	spin_unlock(&ubi->wl_lock);
+
+	if (old_fm) {
+		/* no fresh anchor PEB was found, reuse the old one */
+		if (!tmp_e) {
+			ret = erase_block(ubi, old_fm->e[0]->pnum);
+			if (ret < 0) {
+				ubi_err(ubi, "could not erase old anchor PEB");
+
+				for (i = 1; i < new_fm->used_blocks; i++) {
+					ubi_wl_put_fm_peb(ubi, new_fm->e[i],
+							  i, 0);
+					new_fm->e[i] = NULL;
+				}
+				goto err;
+			}
+			new_fm->e[0] = old_fm->e[0];
+			new_fm->e[0]->ec = ret;
+			old_fm->e[0] = NULL;
+		} else {
+			/* we've got a new anchor PEB, return the old one */
+			ubi_wl_put_fm_peb(ubi, old_fm->e[0], 0,
+					  old_fm->to_be_tortured[0]);
+			new_fm->e[0] = tmp_e;
+			old_fm->e[0] = NULL;
+		}
+	} else {
+		if (!tmp_e) {
+			ubi_err(ubi, "could not find any anchor PEB");
+
+			for (i = 1; i < new_fm->used_blocks; i++) {
+				ubi_wl_put_fm_peb(ubi, new_fm->e[i], i, 0);
+				new_fm->e[i] = NULL;
+			}
+
+			ret = -ENOSPC;
+			goto err;
+		}
+		new_fm->e[0] = tmp_e;
+	}
+
+	ret = ubi_write_fastmap(ubi, new_fm);
+
+	if (ret)
+		goto err;
+
+out_unlock:
+	up_write(&ubi->fm_eba_sem);
+	up_write(&ubi->work_sem);
+	up_write(&ubi->fm_protect);
+	kfree(old_fm);
+
+	ubi_ensure_anchor_pebs(ubi);
+
+	return ret;
+
+err:
+	ubi_warn(ubi, "Unable to write new fastmap, err=%i", ret);
+
+	ret = invalidate_fastmap(ubi);
+	if (ret < 0) {
+		ubi_err(ubi, "Unable to invalidate current fastmap!");
+		ubi_ro_mode(ubi);
+	} else {
+		return_fm_pebs(ubi, old_fm);
+		return_fm_pebs(ubi, new_fm);
+		ret = 0;
+	}
+
+	kfree(new_fm);
+	goto out_unlock;
+}
diff --git a/drivers/mtd/ubi/gluebi.c b/drivers/mtd/ubi/gluebi.c
new file mode 100644
index 0000000000..1b980d15d9
--- /dev/null
+++ b/drivers/mtd/ubi/gluebi.c
@@ -0,0 +1,500 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём), Joern Engel
+ */
+
+/*
+ * This is a small driver which implements fake MTD devices on top of UBI
+ * volumes. This sounds strange, but it is in fact quite useful to make
+ * MTD-oriented software (including all the legacy software) work on top of
+ * UBI.
+ *
+ * Gluebi emulates MTD devices of "MTD_UBIVOLUME" type. Their minimal I/O unit
+ * size (@mtd->writesize) is equivalent to the UBI minimal I/O unit. The
+ * eraseblock size is equivalent to the logical eraseblock size of the volume.
+ */
+
+#include <linux/err.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/mtd/ubi.h>
+#include <linux/mtd/mtd.h>
+#include "ubi-media.h"
+
+#define err_msg(fmt, ...)                                   \
+	pr_err("gluebi (pid %d): %s: " fmt "\n",            \
+	       current->pid, __func__, ##__VA_ARGS__)
+
+/**
+ * struct gluebi_device - a gluebi device description data structure.
+ * @mtd: emulated MTD device description object
+ * @refcnt: gluebi device reference count
+ * @desc: UBI volume descriptor
+ * @ubi_num: UBI device number this gluebi device works on
+ * @vol_id: ID of UBI volume this gluebi device works on
+ * @list: link in a list of gluebi devices
+ */
+struct gluebi_device {
+	struct mtd_info mtd;
+	int refcnt;
+	struct ubi_volume_desc *desc;
+	int ubi_num;
+	int vol_id;
+	struct list_head list;
+};
+
+/* List of all gluebi devices */
+static LIST_HEAD(gluebi_devices);
+static DEFINE_MUTEX(devices_mutex);
+
+/**
+ * find_gluebi_nolock - find a gluebi device.
+ * @ubi_num: UBI device number
+ * @vol_id: volume ID
+ *
+ * This function seraches for gluebi device corresponding to UBI device
+ * @ubi_num and UBI volume @vol_id. Returns the gluebi device description
+ * object in case of success and %NULL in case of failure. The caller has to
+ * have the &devices_mutex locked.
+ */
+static struct gluebi_device *find_gluebi_nolock(int ubi_num, int vol_id)
+{
+	struct gluebi_device *gluebi;
+
+	list_for_each_entry(gluebi, &gluebi_devices, list)
+		if (gluebi->ubi_num == ubi_num && gluebi->vol_id == vol_id)
+			return gluebi;
+	return NULL;
+}
+
+/**
+ * gluebi_get_device - get MTD device reference.
+ * @mtd: the MTD device description object
+ *
+ * This function is called every time the MTD device is being opened and
+ * implements the MTD get_device() operation. Returns zero in case of success
+ * and a negative error code in case of failure.
+ */
+static int gluebi_get_device(struct mtd_info *mtd)
+{
+	struct gluebi_device *gluebi;
+	int ubi_mode = UBI_READONLY;
+
+	if (mtd->flags & MTD_WRITEABLE)
+		ubi_mode = UBI_READWRITE;
+
+	gluebi = container_of(mtd, struct gluebi_device, mtd);
+	mutex_lock(&devices_mutex);
+	if (gluebi->refcnt > 0) {
+		/*
+		 * The MTD device is already referenced and this is just one
+		 * more reference. MTD allows many users to open the same
+		 * volume simultaneously and do not distinguish between
+		 * readers/writers/exclusive/meta openers as UBI does. So we do
+		 * not open the UBI volume again - just increase the reference
+		 * counter and return.
+		 */
+		gluebi->refcnt += 1;
+		mutex_unlock(&devices_mutex);
+		return 0;
+	}
+
+	/*
+	 * This is the first reference to this UBI volume via the MTD device
+	 * interface. Open the corresponding volume in read-write mode.
+	 */
+	gluebi->desc = ubi_open_volume(gluebi->ubi_num, gluebi->vol_id,
+				       ubi_mode);
+	if (IS_ERR(gluebi->desc)) {
+		mutex_unlock(&devices_mutex);
+		return PTR_ERR(gluebi->desc);
+	}
+	gluebi->refcnt += 1;
+	mutex_unlock(&devices_mutex);
+	return 0;
+}
+
+/**
+ * gluebi_put_device - put MTD device reference.
+ * @mtd: the MTD device description object
+ *
+ * This function is called every time the MTD device is being put. Returns
+ * zero in case of success and a negative error code in case of failure.
+ */
+static void gluebi_put_device(struct mtd_info *mtd)
+{
+	struct gluebi_device *gluebi;
+
+	gluebi = container_of(mtd, struct gluebi_device, mtd);
+	mutex_lock(&devices_mutex);
+	gluebi->refcnt -= 1;
+	if (gluebi->refcnt == 0)
+		ubi_close_volume(gluebi->desc);
+	mutex_unlock(&devices_mutex);
+}
+
+/**
+ * gluebi_read - read operation of emulated MTD devices.
+ * @mtd: MTD device description object
+ * @from: absolute offset from where to read
+ * @len: how many bytes to read
+ * @retlen: count of read bytes is returned here
+ * @buf: buffer to store the read data
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int gluebi_read(struct mtd_info *mtd, loff_t from, size_t len,
+		       size_t *retlen, unsigned char *buf)
+{
+	int err = 0, lnum, offs, bytes_left;
+	struct gluebi_device *gluebi;
+
+	gluebi = container_of(mtd, struct gluebi_device, mtd);
+	lnum = div_u64_rem(from, mtd->erasesize, &offs);
+	bytes_left = len;
+	while (bytes_left) {
+		size_t to_read = mtd->erasesize - offs;
+
+		if (to_read > bytes_left)
+			to_read = bytes_left;
+
+		err = ubi_read(gluebi->desc, lnum, buf, offs, to_read);
+		if (err)
+			break;
+
+		lnum += 1;
+		offs = 0;
+		bytes_left -= to_read;
+		buf += to_read;
+	}
+
+	*retlen = len - bytes_left;
+	return err;
+}
+
+/**
+ * gluebi_write - write operation of emulated MTD devices.
+ * @mtd: MTD device description object
+ * @to: absolute offset where to write
+ * @len: how many bytes to write
+ * @retlen: count of written bytes is returned here
+ * @buf: buffer with data to write
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int gluebi_write(struct mtd_info *mtd, loff_t to, size_t len,
+			size_t *retlen, const u_char *buf)
+{
+	int err = 0, lnum, offs, bytes_left;
+	struct gluebi_device *gluebi;
+
+	gluebi = container_of(mtd, struct gluebi_device, mtd);
+	lnum = div_u64_rem(to, mtd->erasesize, &offs);
+
+	if (len % mtd->writesize || offs % mtd->writesize)
+		return -EINVAL;
+
+	bytes_left = len;
+	while (bytes_left) {
+		size_t to_write = mtd->erasesize - offs;
+
+		if (to_write > bytes_left)
+			to_write = bytes_left;
+
+		err = ubi_leb_write(gluebi->desc, lnum, buf, offs, to_write);
+		if (err)
+			break;
+
+		lnum += 1;
+		offs = 0;
+		bytes_left -= to_write;
+		buf += to_write;
+	}
+
+	*retlen = len - bytes_left;
+	return err;
+}
+
+/**
+ * gluebi_erase - erase operation of emulated MTD devices.
+ * @mtd: the MTD device description object
+ * @instr: the erase operation description
+ *
+ * This function calls the erase callback when finishes. Returns zero in case
+ * of success and a negative error code in case of failure.
+ */
+static int gluebi_erase(struct mtd_info *mtd, struct erase_info *instr)
+{
+	int err, i, lnum, count;
+	struct gluebi_device *gluebi;
+
+	if (mtd_mod_by_ws(instr->addr, mtd) || mtd_mod_by_ws(instr->len, mtd))
+		return -EINVAL;
+
+	lnum = mtd_div_by_eb(instr->addr, mtd);
+	count = mtd_div_by_eb(instr->len, mtd);
+	gluebi = container_of(mtd, struct gluebi_device, mtd);
+
+	for (i = 0; i < count - 1; i++) {
+		err = ubi_leb_unmap(gluebi->desc, lnum + i);
+		if (err)
+			goto out_err;
+	}
+	/*
+	 * MTD erase operations are synchronous, so we have to make sure the
+	 * physical eraseblock is wiped out.
+	 *
+	 * Thus, perform leb_erase instead of leb_unmap operation - leb_erase
+	 * will wait for the end of operations
+	 */
+	err = ubi_leb_erase(gluebi->desc, lnum + i);
+	if (err)
+		goto out_err;
+
+	return 0;
+
+out_err:
+	instr->fail_addr = (long long)lnum * mtd->erasesize;
+	return err;
+}
+
+/**
+ * gluebi_create - create a gluebi device for an UBI volume.
+ * @di: UBI device description object
+ * @vi: UBI volume description object
+ *
+ * This function is called when a new UBI volume is created in order to create
+ * corresponding fake MTD device. Returns zero in case of success and a
+ * negative error code in case of failure.
+ */
+static int gluebi_create(struct ubi_device_info *di,
+			 struct ubi_volume_info *vi)
+{
+	struct gluebi_device *gluebi, *g;
+	struct mtd_info *mtd;
+
+	gluebi = kzalloc(sizeof(struct gluebi_device), GFP_KERNEL);
+	if (!gluebi)
+		return -ENOMEM;
+
+	mtd = &gluebi->mtd;
+	mtd->name = kmemdup(vi->name, vi->name_len + 1, GFP_KERNEL);
+	if (!mtd->name) {
+		kfree(gluebi);
+		return -ENOMEM;
+	}
+
+	gluebi->vol_id = vi->vol_id;
+	gluebi->ubi_num = vi->ubi_num;
+	mtd->type = MTD_UBIVOLUME;
+	if (!di->ro_mode)
+		mtd->flags = MTD_WRITEABLE;
+	mtd->owner      = THIS_MODULE;
+	mtd->writesize  = di->min_io_size;
+	mtd->erasesize  = vi->usable_leb_size;
+	mtd->_read       = gluebi_read;
+	mtd->_write      = gluebi_write;
+	mtd->_erase      = gluebi_erase;
+	mtd->_get_device = gluebi_get_device;
+	mtd->_put_device = gluebi_put_device;
+
+	/*
+	 * In case of dynamic a volume, MTD device size is just volume size. In
+	 * case of a static volume the size is equivalent to the amount of data
+	 * bytes.
+	 */
+	if (vi->vol_type == UBI_DYNAMIC_VOLUME)
+		mtd->size = (unsigned long long)vi->usable_leb_size * vi->size;
+	else
+		mtd->size = vi->used_bytes;
+
+	/* Just a sanity check - make sure this gluebi device does not exist */
+	mutex_lock(&devices_mutex);
+	g = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
+	if (g)
+		err_msg("gluebi MTD device %d form UBI device %d volume %d already exists",
+			g->mtd.index, vi->ubi_num, vi->vol_id);
+	mutex_unlock(&devices_mutex);
+
+	if (mtd_device_register(mtd, NULL, 0)) {
+		err_msg("cannot add MTD device");
+		kfree(mtd->name);
+		kfree(gluebi);
+		return -ENFILE;
+	}
+
+	mutex_lock(&devices_mutex);
+	list_add_tail(&gluebi->list, &gluebi_devices);
+	mutex_unlock(&devices_mutex);
+	return 0;
+}
+
+/**
+ * gluebi_remove - remove a gluebi device.
+ * @vi: UBI volume description object
+ *
+ * This function is called when an UBI volume is removed and it removes
+ * corresponding fake MTD device. Returns zero in case of success and a
+ * negative error code in case of failure.
+ */
+static int gluebi_remove(struct ubi_volume_info *vi)
+{
+	int err = 0;
+	struct mtd_info *mtd;
+	struct gluebi_device *gluebi;
+
+	mutex_lock(&devices_mutex);
+	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
+	if (!gluebi) {
+		err_msg("got remove notification for unknown UBI device %d volume %d",
+			vi->ubi_num, vi->vol_id);
+		err = -ENOENT;
+	} else if (gluebi->refcnt)
+		err = -EBUSY;
+	else
+		list_del(&gluebi->list);
+	mutex_unlock(&devices_mutex);
+	if (err)
+		return err;
+
+	mtd = &gluebi->mtd;
+	err = mtd_device_unregister(mtd);
+	if (err) {
+		err_msg("cannot remove fake MTD device %d, UBI device %d, volume %d, error %d",
+			mtd->index, gluebi->ubi_num, gluebi->vol_id, err);
+		mutex_lock(&devices_mutex);
+		list_add_tail(&gluebi->list, &gluebi_devices);
+		mutex_unlock(&devices_mutex);
+		return err;
+	}
+
+	kfree(mtd->name);
+	kfree(gluebi);
+	return 0;
+}
+
+/**
+ * gluebi_updated - UBI volume was updated notifier.
+ * @vi: volume info structure
+ *
+ * This function is called every time an UBI volume is updated. It does nothing
+ * if te volume @vol is dynamic, and changes MTD device size if the
+ * volume is static. This is needed because static volumes cannot be read past
+ * data they contain. This function returns zero in case of success and a
+ * negative error code in case of error.
+ */
+static int gluebi_updated(struct ubi_volume_info *vi)
+{
+	struct gluebi_device *gluebi;
+
+	mutex_lock(&devices_mutex);
+	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
+	if (!gluebi) {
+		mutex_unlock(&devices_mutex);
+		err_msg("got update notification for unknown UBI device %d volume %d",
+			vi->ubi_num, vi->vol_id);
+		return -ENOENT;
+	}
+
+	if (vi->vol_type == UBI_STATIC_VOLUME)
+		gluebi->mtd.size = vi->used_bytes;
+	mutex_unlock(&devices_mutex);
+	return 0;
+}
+
+/**
+ * gluebi_resized - UBI volume was re-sized notifier.
+ * @vi: volume info structure
+ *
+ * This function is called every time an UBI volume is re-size. It changes the
+ * corresponding fake MTD device size. This function returns zero in case of
+ * success and a negative error code in case of error.
+ */
+static int gluebi_resized(struct ubi_volume_info *vi)
+{
+	struct gluebi_device *gluebi;
+
+	mutex_lock(&devices_mutex);
+	gluebi = find_gluebi_nolock(vi->ubi_num, vi->vol_id);
+	if (!gluebi) {
+		mutex_unlock(&devices_mutex);
+		err_msg("got update notification for unknown UBI device %d volume %d",
+			vi->ubi_num, vi->vol_id);
+		return -ENOENT;
+	}
+	gluebi->mtd.size = vi->used_bytes;
+	mutex_unlock(&devices_mutex);
+	return 0;
+}
+
+/**
+ * gluebi_notify - UBI notification handler.
+ * @nb: registered notifier block
+ * @l: notification type
+ * @ns_ptr: pointer to the &struct ubi_notification object
+ */
+static int gluebi_notify(struct notifier_block *nb, unsigned long l,
+			 void *ns_ptr)
+{
+	struct ubi_notification *nt = ns_ptr;
+
+	switch (l) {
+	case UBI_VOLUME_ADDED:
+		gluebi_create(&nt->di, &nt->vi);
+		break;
+	case UBI_VOLUME_REMOVED:
+		gluebi_remove(&nt->vi);
+		break;
+	case UBI_VOLUME_RESIZED:
+		gluebi_resized(&nt->vi);
+		break;
+	case UBI_VOLUME_UPDATED:
+		gluebi_updated(&nt->vi);
+		break;
+	default:
+		break;
+	}
+	return NOTIFY_OK;
+}
+
+static struct notifier_block gluebi_notifier = {
+	.notifier_call	= gluebi_notify,
+};
+
+static int __init ubi_gluebi_init(void)
+{
+	return ubi_register_volume_notifier(&gluebi_notifier, 0);
+}
+
+static void __exit ubi_gluebi_exit(void)
+{
+	struct gluebi_device *gluebi, *g;
+
+	list_for_each_entry_safe(gluebi, g, &gluebi_devices, list) {
+		int err;
+		struct mtd_info *mtd = &gluebi->mtd;
+
+		err = mtd_device_unregister(mtd);
+		if (err)
+			err_msg("error %d while removing gluebi MTD device %d, UBI device %d, volume %d - ignoring",
+				err, mtd->index, gluebi->ubi_num,
+				gluebi->vol_id);
+		kfree(mtd->name);
+		kfree(gluebi);
+	}
+	ubi_unregister_volume_notifier(&gluebi_notifier);
+}
+
+module_init(ubi_gluebi_init);
+module_exit(ubi_gluebi_exit);
+MODULE_DESCRIPTION("MTD emulation layer over UBI volumes");
+MODULE_AUTHOR("Artem Bityutskiy, Joern Engel");
+MODULE_LICENSE("GPL");
diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c
new file mode 100644
index 0000000000..01b6448612
--- /dev/null
+++ b/drivers/mtd/ubi/io.c
@@ -0,0 +1,1398 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ * Copyright (c) Nokia Corporation, 2006, 2007
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+/*
+ * UBI input/output sub-system.
+ *
+ * This sub-system provides a uniform way to work with all kinds of the
+ * underlying MTD devices. It also implements handy functions for reading and
+ * writing UBI headers.
+ *
+ * We are trying to have a paranoid mindset and not to trust to what we read
+ * from the flash media in order to be more secure and robust. So this
+ * sub-system validates every single header it reads from the flash media.
+ *
+ * Some words about how the eraseblock headers are stored.
+ *
+ * The erase counter header is always stored at offset zero. By default, the
+ * VID header is stored after the EC header at the closest aligned offset
+ * (i.e. aligned to the minimum I/O unit size). Data starts next to the VID
+ * header at the closest aligned offset. But this default layout may be
+ * changed. For example, for different reasons (e.g., optimization) UBI may be
+ * asked to put the VID header at further offset, and even at an unaligned
+ * offset. Of course, if the offset of the VID header is unaligned, UBI adds
+ * proper padding in front of it. Data offset may also be changed but it has to
+ * be aligned.
+ *
+ * About minimal I/O units. In general, UBI assumes flash device model where
+ * there is only one minimal I/O unit size. E.g., in case of NOR flash it is 1,
+ * in case of NAND flash it is a NAND page, etc. This is reported by MTD in the
+ * @ubi->mtd->writesize field. But as an exception, UBI admits use of another
+ * (smaller) minimal I/O unit size for EC and VID headers to make it possible
+ * to do different optimizations.
+ *
+ * This is extremely useful in case of NAND flashes which admit of several
+ * write operations to one NAND page. In this case UBI can fit EC and VID
+ * headers at one NAND page. Thus, UBI may use "sub-page" size as the minimal
+ * I/O unit for the headers (the @ubi->hdrs_min_io_size field). But it still
+ * reports NAND page size (@ubi->min_io_size) as a minimal I/O unit for the UBI
+ * users.
+ *
+ * Example: some Samsung NANDs with 2KiB pages allow 4x 512-byte writes, so
+ * although the minimal I/O unit is 2K, UBI uses 512 bytes for EC and VID
+ * headers.
+ *
+ * Q: why not just to treat sub-page as a minimal I/O unit of this flash
+ * device, e.g., make @ubi->min_io_size = 512 in the example above?
+ *
+ * A: because when writing a sub-page, MTD still writes a full 2K page but the
+ * bytes which are not relevant to the sub-page are 0xFF. So, basically,
+ * writing 4x512 sub-pages is 4 times slower than writing one 2KiB NAND page.
+ * Thus, we prefer to use sub-pages only for EC and VID headers.
+ *
+ * As it was noted above, the VID header may start at a non-aligned offset.
+ * For example, in case of a 2KiB page NAND flash with a 512 bytes sub-page,
+ * the VID header may reside at offset 1984 which is the last 64 bytes of the
+ * last sub-page (EC header is always at offset zero). This causes some
+ * difficulties when reading and writing VID headers.
+ *
+ * Suppose we have a 64-byte buffer and we read a VID header at it. We change
+ * the data and want to write this VID header out. As we can only write in
+ * 512-byte chunks, we have to allocate one more buffer and copy our VID header
+ * to offset 448 of this buffer.
+ *
+ * The I/O sub-system does the following trick in order to avoid this extra
+ * copy. It always allocates a @ubi->vid_hdr_alsize bytes buffer for the VID
+ * header and returns a pointer to offset @ubi->vid_hdr_shift of this buffer.
+ * When the VID header is being written out, it shifts the VID header pointer
+ * back and writes the whole sub-page.
+ */
+
+#include <linux/crc32.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include "ubi.h"
+
+static int self_check_not_bad(const struct ubi_device *ubi, int pnum);
+static int self_check_peb_ec_hdr(const struct ubi_device *ubi, int pnum);
+static int self_check_ec_hdr(const struct ubi_device *ubi, int pnum,
+			     const struct ubi_ec_hdr *ec_hdr);
+static int self_check_peb_vid_hdr(const struct ubi_device *ubi, int pnum);
+static int self_check_vid_hdr(const struct ubi_device *ubi, int pnum,
+			      const struct ubi_vid_hdr *vid_hdr);
+static int self_check_write(struct ubi_device *ubi, const void *buf, int pnum,
+			    int offset, int len);
+
+/**
+ * ubi_io_read - read data from a physical eraseblock.
+ * @ubi: UBI device description object
+ * @buf: buffer where to store the read data
+ * @pnum: physical eraseblock number to read from
+ * @offset: offset within the physical eraseblock from where to read
+ * @len: how many bytes to read
+ *
+ * This function reads data from offset @offset of physical eraseblock @pnum
+ * and stores the read data in the @buf buffer. The following return codes are
+ * possible:
+ *
+ * o %0 if all the requested data were successfully read;
+ * o %UBI_IO_BITFLIPS if all the requested data were successfully read, but
+ *   correctable bit-flips were detected; this is harmless but may indicate
+ *   that this eraseblock may become bad soon (but do not have to);
+ * o %-EBADMSG if the MTD subsystem reported about data integrity problems, for
+ *   example it can be an ECC error in case of NAND; this most probably means
+ *   that the data is corrupted;
+ * o %-EIO if some I/O error occurred;
+ * o other negative error codes in case of other errors.
+ */
+int ubi_io_read(const struct ubi_device *ubi, void *buf, int pnum, int offset,
+		int len)
+{
+	int err, retries = 0;
+	size_t read;
+	loff_t addr;
+
+	dbg_io("read %d bytes from PEB %d:%d", len, pnum, offset);
+
+	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
+	ubi_assert(offset >= 0 && offset + len <= ubi->peb_size);
+	ubi_assert(len > 0);
+
+	err = self_check_not_bad(ubi, pnum);
+	if (err)
+		return err;
+
+	/*
+	 * Deliberately corrupt the buffer to improve robustness. Indeed, if we
+	 * do not do this, the following may happen:
+	 * 1. The buffer contains data from previous operation, e.g., read from
+	 *    another PEB previously. The data looks like expected, e.g., if we
+	 *    just do not read anything and return - the caller would not
+	 *    notice this. E.g., if we are reading a VID header, the buffer may
+	 *    contain a valid VID header from another PEB.
+	 * 2. The driver is buggy and returns us success or -EBADMSG or
+	 *    -EUCLEAN, but it does not actually put any data to the buffer.
+	 *
+	 * This may confuse UBI or upper layers - they may think the buffer
+	 * contains valid data while in fact it is just old data. This is
+	 * especially possible because UBI (and UBIFS) relies on CRC, and
+	 * treats data as correct even in case of ECC errors if the CRC is
+	 * correct.
+	 *
+	 * Try to prevent this situation by changing the first byte of the
+	 * buffer.
+	 */
+	*((uint8_t *)buf) ^= 0xFF;
+
+	addr = (loff_t)pnum * ubi->peb_size + offset;
+retry:
+	err = mtd_read(ubi->mtd, addr, len, &read, buf);
+	if (err) {
+		const char *errstr = mtd_is_eccerr(err) ? " (ECC error)" : "";
+
+		if (mtd_is_bitflip(err)) {
+			/*
+			 * -EUCLEAN is reported if there was a bit-flip which
+			 * was corrected, so this is harmless.
+			 *
+			 * We do not report about it here unless debugging is
+			 * enabled. A corresponding message will be printed
+			 * later, when it is has been scrubbed.
+			 */
+			ubi_msg(ubi, "fixable bit-flip detected at PEB %d",
+				pnum);
+			ubi_assert(len == read);
+			return UBI_IO_BITFLIPS;
+		}
+
+		if (retries++ < UBI_IO_RETRIES) {
+			ubi_warn(ubi, "error %d%s while reading %d bytes from PEB %d:%d, read only %zd bytes, retry",
+				 err, errstr, len, pnum, offset, read);
+			yield();
+			goto retry;
+		}
+
+		ubi_err(ubi, "error %d%s while reading %d bytes from PEB %d:%d, read %zd bytes",
+			err, errstr, len, pnum, offset, read);
+		dump_stack();
+
+		/*
+		 * The driver should never return -EBADMSG if it failed to read
+		 * all the requested data. But some buggy drivers might do
+		 * this, so we change it to -EIO.
+		 */
+		if (read != len && mtd_is_eccerr(err)) {
+			ubi_assert(0);
+			err = -EIO;
+		}
+	} else {
+		ubi_assert(len == read);
+
+		if (ubi_dbg_is_bitflip(ubi)) {
+			dbg_gen("bit-flip (emulated)");
+			err = UBI_IO_BITFLIPS;
+		}
+	}
+
+	return err;
+}
+
+/**
+ * ubi_io_write - write data to a physical eraseblock.
+ * @ubi: UBI device description object
+ * @buf: buffer with the data to write
+ * @pnum: physical eraseblock number to write to
+ * @offset: offset within the physical eraseblock where to write
+ * @len: how many bytes to write
+ *
+ * This function writes @len bytes of data from buffer @buf to offset @offset
+ * of physical eraseblock @pnum. If all the data were successfully written,
+ * zero is returned. If an error occurred, this function returns a negative
+ * error code. If %-EIO is returned, the physical eraseblock most probably went
+ * bad.
+ *
+ * Note, in case of an error, it is possible that something was still written
+ * to the flash media, but may be some garbage.
+ */
+int ubi_io_write(struct ubi_device *ubi, const void *buf, int pnum, int offset,
+		 int len)
+{
+	int err;
+	size_t written;
+	loff_t addr;
+
+	dbg_io("write %d bytes to PEB %d:%d", len, pnum, offset);
+
+	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
+	ubi_assert(offset >= 0 && offset + len <= ubi->peb_size);
+	ubi_assert(offset % ubi->hdrs_min_io_size == 0);
+	ubi_assert(len > 0 && len % ubi->hdrs_min_io_size == 0);
+
+	if (ubi->ro_mode) {
+		ubi_err(ubi, "read-only mode");
+		return -EROFS;
+	}
+
+	err = self_check_not_bad(ubi, pnum);
+	if (err)
+		return err;
+
+	/* The area we are writing to has to contain all 0xFF bytes */
+	err = ubi_self_check_all_ff(ubi, pnum, offset, len);
+	if (err)
+		return err;
+
+	if (offset >= ubi->leb_start) {
+		/*
+		 * We write to the data area of the physical eraseblock. Make
+		 * sure it has valid EC and VID headers.
+		 */
+		err = self_check_peb_ec_hdr(ubi, pnum);
+		if (err)
+			return err;
+		err = self_check_peb_vid_hdr(ubi, pnum);
+		if (err)
+			return err;
+	}
+
+	if (ubi_dbg_is_write_failure(ubi)) {
+		ubi_err(ubi, "cannot write %d bytes to PEB %d:%d (emulated)",
+			len, pnum, offset);
+		dump_stack();
+		return -EIO;
+	}
+
+	addr = (loff_t)pnum * ubi->peb_size + offset;
+	err = mtd_write(ubi->mtd, addr, len, &written, buf);
+	if (err) {
+		ubi_err(ubi, "error %d while writing %d bytes to PEB %d:%d, written %zd bytes",
+			err, len, pnum, offset, written);
+		dump_stack();
+		ubi_dump_flash(ubi, pnum, offset, len);
+	} else
+		ubi_assert(written == len);
+
+	if (!err) {
+		err = self_check_write(ubi, buf, pnum, offset, len);
+		if (err)
+			return err;
+
+		/*
+		 * Since we always write sequentially, the rest of the PEB has
+		 * to contain only 0xFF bytes.
+		 */
+		offset += len;
+		len = ubi->peb_size - offset;
+		if (len)
+			err = ubi_self_check_all_ff(ubi, pnum, offset, len);
+	}
+
+	return err;
+}
+
+/**
+ * do_sync_erase - synchronously erase a physical eraseblock.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to erase
+ *
+ * This function synchronously erases physical eraseblock @pnum and returns
+ * zero in case of success and a negative error code in case of failure. If
+ * %-EIO is returned, the physical eraseblock most probably went bad.
+ */
+static int do_sync_erase(struct ubi_device *ubi, int pnum)
+{
+	int err, retries = 0;
+	struct erase_info ei;
+
+	dbg_io("erase PEB %d", pnum);
+	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
+
+	if (ubi->ro_mode) {
+		ubi_err(ubi, "read-only mode");
+		return -EROFS;
+	}
+
+retry:
+	memset(&ei, 0, sizeof(struct erase_info));
+
+	ei.addr     = (loff_t)pnum * ubi->peb_size;
+	ei.len      = ubi->peb_size;
+
+	err = mtd_erase(ubi->mtd, &ei);
+	if (err) {
+		if (retries++ < UBI_IO_RETRIES) {
+			ubi_warn(ubi, "error %d while erasing PEB %d, retry",
+				 err, pnum);
+			yield();
+			goto retry;
+		}
+		ubi_err(ubi, "cannot erase PEB %d, error %d", pnum, err);
+		dump_stack();
+		return err;
+	}
+
+	err = ubi_self_check_all_ff(ubi, pnum, 0, ubi->peb_size);
+	if (err)
+		return err;
+
+	if (ubi_dbg_is_erase_failure(ubi)) {
+		ubi_err(ubi, "cannot erase PEB %d (emulated)", pnum);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+/* Patterns to write to a physical eraseblock when torturing it */
+static uint8_t patterns[] = {0xa5, 0x5a, 0x0};
+
+/**
+ * torture_peb - test a supposedly bad physical eraseblock.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to test
+ *
+ * This function returns %-EIO if the physical eraseblock did not pass the
+ * test, a positive number of erase operations done if the test was
+ * successfully passed, and other negative error codes in case of other errors.
+ */
+static int torture_peb(struct ubi_device *ubi, int pnum)
+{
+	int err, i, patt_count;
+
+	ubi_msg(ubi, "run torture test for PEB %d", pnum);
+	patt_count = ARRAY_SIZE(patterns);
+	ubi_assert(patt_count > 0);
+
+	mutex_lock(&ubi->buf_mutex);
+	for (i = 0; i < patt_count; i++) {
+		err = do_sync_erase(ubi, pnum);
+		if (err)
+			goto out;
+
+		/* Make sure the PEB contains only 0xFF bytes */
+		err = ubi_io_read(ubi, ubi->peb_buf, pnum, 0, ubi->peb_size);
+		if (err)
+			goto out;
+
+		err = ubi_check_pattern(ubi->peb_buf, 0xFF, ubi->peb_size);
+		if (err == 0) {
+			ubi_err(ubi, "erased PEB %d, but a non-0xFF byte found",
+				pnum);
+			err = -EIO;
+			goto out;
+		}
+
+		/* Write a pattern and check it */
+		memset(ubi->peb_buf, patterns[i], ubi->peb_size);
+		err = ubi_io_write(ubi, ubi->peb_buf, pnum, 0, ubi->peb_size);
+		if (err)
+			goto out;
+
+		memset(ubi->peb_buf, ~patterns[i], ubi->peb_size);
+		err = ubi_io_read(ubi, ubi->peb_buf, pnum, 0, ubi->peb_size);
+		if (err)
+			goto out;
+
+		err = ubi_check_pattern(ubi->peb_buf, patterns[i],
+					ubi->peb_size);
+		if (err == 0) {
+			ubi_err(ubi, "pattern %x checking failed for PEB %d",
+				patterns[i], pnum);
+			err = -EIO;
+			goto out;
+		}
+	}
+
+	err = patt_count;
+	ubi_msg(ubi, "PEB %d passed torture test, do not mark it as bad", pnum);
+
+out:
+	mutex_unlock(&ubi->buf_mutex);
+	if (err == UBI_IO_BITFLIPS || mtd_is_eccerr(err)) {
+		/*
+		 * If a bit-flip or data integrity error was detected, the test
+		 * has not passed because it happened on a freshly erased
+		 * physical eraseblock which means something is wrong with it.
+		 */
+		ubi_err(ubi, "read problems on freshly erased PEB %d, must be bad",
+			pnum);
+		err = -EIO;
+	}
+	return err;
+}
+
+/**
+ * nor_erase_prepare - prepare a NOR flash PEB for erasure.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock number to prepare
+ *
+ * NOR flash, or at least some of them, have peculiar embedded PEB erasure
+ * algorithm: the PEB is first filled with zeroes, then it is erased. And
+ * filling with zeroes starts from the end of the PEB. This was observed with
+ * Spansion S29GL512N NOR flash.
+ *
+ * This means that in case of a power cut we may end up with intact data at the
+ * beginning of the PEB, and all zeroes at the end of PEB. In other words, the
+ * EC and VID headers are OK, but a large chunk of data at the end of PEB is
+ * zeroed. This makes UBI mistakenly treat this PEB as used and associate it
+ * with an LEB, which leads to subsequent failures (e.g., UBIFS fails).
+ *
+ * This function is called before erasing NOR PEBs and it zeroes out EC and VID
+ * magic numbers in order to invalidate them and prevent the failures. Returns
+ * zero in case of success and a negative error code in case of failure.
+ */
+static int nor_erase_prepare(struct ubi_device *ubi, int pnum)
+{
+	int err;
+	size_t written;
+	loff_t addr;
+	uint32_t data = 0;
+	struct ubi_ec_hdr ec_hdr;
+	struct ubi_vid_io_buf vidb;
+
+	/*
+	 * Note, we cannot generally define VID header buffers on stack,
+	 * because of the way we deal with these buffers (see the header
+	 * comment in this file). But we know this is a NOR-specific piece of
+	 * code, so we can do this. But yes, this is error-prone and we should
+	 * (pre-)allocate VID header buffer instead.
+	 */
+	struct ubi_vid_hdr vid_hdr;
+
+	/*
+	 * If VID or EC is valid, we have to corrupt them before erasing.
+	 * It is important to first invalidate the EC header, and then the VID
+	 * header. Otherwise a power cut may lead to valid EC header and
+	 * invalid VID header, in which case UBI will treat this PEB as
+	 * corrupted and will try to preserve it, and print scary warnings.
+	 */
+	addr = (loff_t)pnum * ubi->peb_size;
+	err = ubi_io_read_ec_hdr(ubi, pnum, &ec_hdr, 0);
+	if (err != UBI_IO_BAD_HDR_EBADMSG && err != UBI_IO_BAD_HDR &&
+	    err != UBI_IO_FF){
+		err = mtd_write(ubi->mtd, addr, 4, &written, (void *)&data);
+		if(err)
+			goto error;
+	}
+
+	ubi_init_vid_buf(ubi, &vidb, &vid_hdr);
+	ubi_assert(&vid_hdr == ubi_get_vid_hdr(&vidb));
+
+	err = ubi_io_read_vid_hdr(ubi, pnum, &vidb, 0);
+	if (err != UBI_IO_BAD_HDR_EBADMSG && err != UBI_IO_BAD_HDR &&
+	    err != UBI_IO_FF){
+		addr += ubi->vid_hdr_aloffset;
+		err = mtd_write(ubi->mtd, addr, 4, &written, (void *)&data);
+		if (err)
+			goto error;
+	}
+	return 0;
+
+error:
+	/*
+	 * The PEB contains a valid VID or EC header, but we cannot invalidate
+	 * it. Supposedly the flash media or the driver is screwed up, so
+	 * return an error.
+	 */
+	ubi_err(ubi, "cannot invalidate PEB %d, write returned %d", pnum, err);
+	ubi_dump_flash(ubi, pnum, 0, ubi->peb_size);
+	return -EIO;
+}
+
+/**
+ * ubi_io_sync_erase - synchronously erase a physical eraseblock.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock number to erase
+ * @torture: if this physical eraseblock has to be tortured
+ *
+ * This function synchronously erases physical eraseblock @pnum. If @torture
+ * flag is not zero, the physical eraseblock is checked by means of writing
+ * different patterns to it and reading them back. If the torturing is enabled,
+ * the physical eraseblock is erased more than once.
+ *
+ * This function returns the number of erasures made in case of success, %-EIO
+ * if the erasure failed or the torturing test failed, and other negative error
+ * codes in case of other errors. Note, %-EIO means that the physical
+ * eraseblock is bad.
+ */
+int ubi_io_sync_erase(struct ubi_device *ubi, int pnum, int torture)
+{
+	int err, ret = 0;
+
+	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
+
+	err = self_check_not_bad(ubi, pnum);
+	if (err != 0)
+		return err;
+
+	if (ubi->ro_mode) {
+		ubi_err(ubi, "read-only mode");
+		return -EROFS;
+	}
+
+	/*
+	 * If the flash is ECC-ed then we have to erase the ECC block before we
+	 * can write to it. But the write is in preparation to an erase in the
+	 * first place. This means we cannot zero out EC and VID before the
+	 * erase and we just have to hope the flash starts erasing from the
+	 * start of the page.
+	 */
+	if (ubi->nor_flash && ubi->mtd->writesize == 1) {
+		err = nor_erase_prepare(ubi, pnum);
+		if (err)
+			return err;
+	}
+
+	if (torture) {
+		ret = torture_peb(ubi, pnum);
+		if (ret < 0)
+			return ret;
+	}
+
+	err = do_sync_erase(ubi, pnum);
+	if (err)
+		return err;
+
+	return ret + 1;
+}
+
+/**
+ * ubi_io_is_bad - check if a physical eraseblock is bad.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to check
+ *
+ * This function returns a positive number if the physical eraseblock is bad,
+ * zero if not, and a negative error code if an error occurred.
+ */
+int ubi_io_is_bad(const struct ubi_device *ubi, int pnum)
+{
+	struct mtd_info *mtd = ubi->mtd;
+
+	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
+
+	if (ubi->bad_allowed) {
+		int ret;
+
+		ret = mtd_block_isbad(mtd, (loff_t)pnum * ubi->peb_size);
+		if (ret < 0)
+			ubi_err(ubi, "error %d while checking if PEB %d is bad",
+				ret, pnum);
+		else if (ret)
+			dbg_io("PEB %d is bad", pnum);
+		return ret;
+	}
+
+	return 0;
+}
+
+/**
+ * ubi_io_mark_bad - mark a physical eraseblock as bad.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to mark
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+int ubi_io_mark_bad(const struct ubi_device *ubi, int pnum)
+{
+	int err;
+	struct mtd_info *mtd = ubi->mtd;
+
+	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
+
+	if (ubi->ro_mode) {
+		ubi_err(ubi, "read-only mode");
+		return -EROFS;
+	}
+
+	if (!ubi->bad_allowed)
+		return 0;
+
+	err = mtd_block_markbad(mtd, (loff_t)pnum * ubi->peb_size);
+	if (err)
+		ubi_err(ubi, "cannot mark PEB %d bad, error %d", pnum, err);
+	return err;
+}
+
+/**
+ * validate_ec_hdr - validate an erase counter header.
+ * @ubi: UBI device description object
+ * @ec_hdr: the erase counter header to check
+ *
+ * This function returns zero if the erase counter header is OK, and %1 if
+ * not.
+ */
+static int validate_ec_hdr(const struct ubi_device *ubi,
+			   const struct ubi_ec_hdr *ec_hdr)
+{
+	long long ec;
+	int vid_hdr_offset, leb_start;
+
+	ec = be64_to_cpu(ec_hdr->ec);
+	vid_hdr_offset = be32_to_cpu(ec_hdr->vid_hdr_offset);
+	leb_start = be32_to_cpu(ec_hdr->data_offset);
+
+	if (ec_hdr->version != UBI_VERSION) {
+		ubi_err(ubi, "node with incompatible UBI version found: this UBI version is %d, image version is %d",
+			UBI_VERSION, (int)ec_hdr->version);
+		goto bad;
+	}
+
+	if (vid_hdr_offset != ubi->vid_hdr_offset) {
+		ubi_err(ubi, "bad VID header offset %d, expected %d",
+			vid_hdr_offset, ubi->vid_hdr_offset);
+		goto bad;
+	}
+
+	if (leb_start != ubi->leb_start) {
+		ubi_err(ubi, "bad data offset %d, expected %d",
+			leb_start, ubi->leb_start);
+		goto bad;
+	}
+
+	if (ec < 0 || ec > UBI_MAX_ERASECOUNTER) {
+		ubi_err(ubi, "bad erase counter %lld", ec);
+		goto bad;
+	}
+
+	return 0;
+
+bad:
+	ubi_err(ubi, "bad EC header");
+	ubi_dump_ec_hdr(ec_hdr);
+	dump_stack();
+	return 1;
+}
+
+/**
+ * ubi_io_read_ec_hdr - read and check an erase counter header.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock to read from
+ * @ec_hdr: a &struct ubi_ec_hdr object where to store the read erase counter
+ * header
+ * @verbose: be verbose if the header is corrupted or was not found
+ *
+ * This function reads erase counter header from physical eraseblock @pnum and
+ * stores it in @ec_hdr. This function also checks CRC checksum of the read
+ * erase counter header. The following codes may be returned:
+ *
+ * o %0 if the CRC checksum is correct and the header was successfully read;
+ * o %UBI_IO_BITFLIPS if the CRC is correct, but bit-flips were detected
+ *   and corrected by the flash driver; this is harmless but may indicate that
+ *   this eraseblock may become bad soon (but may be not);
+ * o %UBI_IO_BAD_HDR if the erase counter header is corrupted (a CRC error);
+ * o %UBI_IO_BAD_HDR_EBADMSG is the same as %UBI_IO_BAD_HDR, but there also was
+ *   a data integrity error (uncorrectable ECC error in case of NAND);
+ * o %UBI_IO_FF if only 0xFF bytes were read (the PEB is supposedly empty)
+ * o a negative error code in case of failure.
+ */
+int ubi_io_read_ec_hdr(struct ubi_device *ubi, int pnum,
+		       struct ubi_ec_hdr *ec_hdr, int verbose)
+{
+	int err, read_err;
+	uint32_t crc, magic, hdr_crc;
+
+	dbg_io("read EC header from PEB %d", pnum);
+	ubi_assert(pnum >= 0 && pnum < ubi->peb_count);
+
+	read_err = ubi_io_read(ubi, ec_hdr, pnum, 0, UBI_EC_HDR_SIZE);
+	if (read_err) {
+		if (read_err != UBI_IO_BITFLIPS && !mtd_is_eccerr(read_err))
+			return read_err;
+
+		/*
+		 * We read all the data, but either a correctable bit-flip
+		 * occurred, or MTD reported a data integrity error
+		 * (uncorrectable ECC error in case of NAND). The former is
+		 * harmless, the later may mean that the read data is
+		 * corrupted. But we have a CRC check-sum and we will detect
+		 * this. If the EC header is still OK, we just report this as
+		 * there was a bit-flip, to force scrubbing.
+		 */
+	}
+
+	magic = be32_to_cpu(ec_hdr->magic);
+	if (magic != UBI_EC_HDR_MAGIC) {
+		if (mtd_is_eccerr(read_err))
+			return UBI_IO_BAD_HDR_EBADMSG;
+
+		/*
+		 * The magic field is wrong. Let's check if we have read all
+		 * 0xFF. If yes, this physical eraseblock is assumed to be
+		 * empty.
+		 */
+		if (ubi_check_pattern(ec_hdr, 0xFF, UBI_EC_HDR_SIZE)) {
+			/* The physical eraseblock is supposedly empty */
+			if (verbose)
+				ubi_warn(ubi, "no EC header found at PEB %d, only 0xFF bytes",
+					 pnum);
+			dbg_bld("no EC header found at PEB %d, only 0xFF bytes",
+				pnum);
+			if (!read_err)
+				return UBI_IO_FF;
+			else
+				return UBI_IO_FF_BITFLIPS;
+		}
+
+		/*
+		 * This is not a valid erase counter header, and these are not
+		 * 0xFF bytes. Report that the header is corrupted.
+		 */
+		if (verbose) {
+			ubi_warn(ubi, "bad magic number at PEB %d: %08x instead of %08x",
+				 pnum, magic, UBI_EC_HDR_MAGIC);
+			ubi_dump_ec_hdr(ec_hdr);
+		}
+		dbg_bld("bad magic number at PEB %d: %08x instead of %08x",
+			pnum, magic, UBI_EC_HDR_MAGIC);
+		return UBI_IO_BAD_HDR;
+	}
+
+	crc = crc32(UBI_CRC32_INIT, ec_hdr, UBI_EC_HDR_SIZE_CRC);
+	hdr_crc = be32_to_cpu(ec_hdr->hdr_crc);
+
+	if (hdr_crc != crc) {
+		if (verbose) {
+			ubi_warn(ubi, "bad EC header CRC at PEB %d, calculated %#08x, read %#08x",
+				 pnum, crc, hdr_crc);
+			ubi_dump_ec_hdr(ec_hdr);
+		}
+		dbg_bld("bad EC header CRC at PEB %d, calculated %#08x, read %#08x",
+			pnum, crc, hdr_crc);
+
+		if (!read_err)
+			return UBI_IO_BAD_HDR;
+		else
+			return UBI_IO_BAD_HDR_EBADMSG;
+	}
+
+	/* And of course validate what has just been read from the media */
+	err = validate_ec_hdr(ubi, ec_hdr);
+	if (err) {
+		ubi_err(ubi, "validation failed for PEB %d", pnum);
+		return -EINVAL;
+	}
+
+	/*
+	 * If there was %-EBADMSG, but the header CRC is still OK, report about
+	 * a bit-flip to force scrubbing on this PEB.
+	 */
+	return read_err ? UBI_IO_BITFLIPS : 0;
+}
+
+/**
+ * ubi_io_write_ec_hdr - write an erase counter header.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock to write to
+ * @ec_hdr: the erase counter header to write
+ *
+ * This function writes erase counter header described by @ec_hdr to physical
+ * eraseblock @pnum. It also fills most fields of @ec_hdr before writing, so
+ * the caller do not have to fill them. Callers must only fill the @ec_hdr->ec
+ * field.
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure. If %-EIO is returned, the physical eraseblock most probably
+ * went bad.
+ */
+int ubi_io_write_ec_hdr(struct ubi_device *ubi, int pnum,
+			struct ubi_ec_hdr *ec_hdr)
+{
+	int err;
+	uint32_t crc;
+
+	dbg_io("write EC header to PEB %d", pnum);
+	ubi_assert(pnum >= 0 &&  pnum < ubi->peb_count);
+
+	ec_hdr->magic = cpu_to_be32(UBI_EC_HDR_MAGIC);
+	ec_hdr->version = UBI_VERSION;
+	ec_hdr->vid_hdr_offset = cpu_to_be32(ubi->vid_hdr_offset);
+	ec_hdr->data_offset = cpu_to_be32(ubi->leb_start);
+	ec_hdr->image_seq = cpu_to_be32(ubi->image_seq);
+	crc = crc32(UBI_CRC32_INIT, ec_hdr, UBI_EC_HDR_SIZE_CRC);
+	ec_hdr->hdr_crc = cpu_to_be32(crc);
+
+	err = self_check_ec_hdr(ubi, pnum, ec_hdr);
+	if (err)
+		return err;
+
+	if (ubi_dbg_power_cut(ubi, POWER_CUT_EC_WRITE))
+		return -EROFS;
+
+	err = ubi_io_write(ubi, ec_hdr, pnum, 0, ubi->ec_hdr_alsize);
+	return err;
+}
+
+/**
+ * validate_vid_hdr - validate a volume identifier header.
+ * @ubi: UBI device description object
+ * @vid_hdr: the volume identifier header to check
+ *
+ * This function checks that data stored in the volume identifier header
+ * @vid_hdr. Returns zero if the VID header is OK and %1 if not.
+ */
+static int validate_vid_hdr(const struct ubi_device *ubi,
+			    const struct ubi_vid_hdr *vid_hdr)
+{
+	int vol_type = vid_hdr->vol_type;
+	int copy_flag = vid_hdr->copy_flag;
+	int vol_id = be32_to_cpu(vid_hdr->vol_id);
+	int lnum = be32_to_cpu(vid_hdr->lnum);
+	int compat = vid_hdr->compat;
+	int data_size = be32_to_cpu(vid_hdr->data_size);
+	int used_ebs = be32_to_cpu(vid_hdr->used_ebs);
+	int data_pad = be32_to_cpu(vid_hdr->data_pad);
+	int data_crc = be32_to_cpu(vid_hdr->data_crc);
+	int usable_leb_size = ubi->leb_size - data_pad;
+
+	if (copy_flag != 0 && copy_flag != 1) {
+		ubi_err(ubi, "bad copy_flag");
+		goto bad;
+	}
+
+	if (vol_id < 0 || lnum < 0 || data_size < 0 || used_ebs < 0 ||
+	    data_pad < 0) {
+		ubi_err(ubi, "negative values");
+		goto bad;
+	}
+
+	if (vol_id >= UBI_MAX_VOLUMES && vol_id < UBI_INTERNAL_VOL_START) {
+		ubi_err(ubi, "bad vol_id");
+		goto bad;
+	}
+
+	if (vol_id < UBI_INTERNAL_VOL_START && compat != 0) {
+		ubi_err(ubi, "bad compat");
+		goto bad;
+	}
+
+	if (vol_id >= UBI_INTERNAL_VOL_START && compat != UBI_COMPAT_DELETE &&
+	    compat != UBI_COMPAT_RO && compat != UBI_COMPAT_PRESERVE &&
+	    compat != UBI_COMPAT_REJECT) {
+		ubi_err(ubi, "bad compat");
+		goto bad;
+	}
+
+	if (vol_type != UBI_VID_DYNAMIC && vol_type != UBI_VID_STATIC) {
+		ubi_err(ubi, "bad vol_type");
+		goto bad;
+	}
+
+	if (data_pad >= ubi->leb_size / 2) {
+		ubi_err(ubi, "bad data_pad");
+		goto bad;
+	}
+
+	if (data_size > ubi->leb_size) {
+		ubi_err(ubi, "bad data_size");
+		goto bad;
+	}
+
+	if (vol_type == UBI_VID_STATIC) {
+		/*
+		 * Although from high-level point of view static volumes may
+		 * contain zero bytes of data, but no VID headers can contain
+		 * zero at these fields, because they empty volumes do not have
+		 * mapped logical eraseblocks.
+		 */
+		if (used_ebs == 0) {
+			ubi_err(ubi, "zero used_ebs");
+			goto bad;
+		}
+		if (data_size == 0) {
+			ubi_err(ubi, "zero data_size");
+			goto bad;
+		}
+		if (lnum < used_ebs - 1) {
+			if (data_size != usable_leb_size) {
+				ubi_err(ubi, "bad data_size");
+				goto bad;
+			}
+		} else if (lnum > used_ebs - 1) {
+			ubi_err(ubi, "too high lnum");
+			goto bad;
+		}
+	} else {
+		if (copy_flag == 0) {
+			if (data_crc != 0) {
+				ubi_err(ubi, "non-zero data CRC");
+				goto bad;
+			}
+			if (data_size != 0) {
+				ubi_err(ubi, "non-zero data_size");
+				goto bad;
+			}
+		} else {
+			if (data_size == 0) {
+				ubi_err(ubi, "zero data_size of copy");
+				goto bad;
+			}
+		}
+		if (used_ebs != 0) {
+			ubi_err(ubi, "bad used_ebs");
+			goto bad;
+		}
+	}
+
+	return 0;
+
+bad:
+	ubi_err(ubi, "bad VID header");
+	ubi_dump_vid_hdr(vid_hdr);
+	dump_stack();
+	return 1;
+}
+
+/**
+ * ubi_io_read_vid_hdr - read and check a volume identifier header.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock number to read from
+ * @vidb: the volume identifier buffer to store data in
+ * @verbose: be verbose if the header is corrupted or wasn't found
+ *
+ * This function reads the volume identifier header from physical eraseblock
+ * @pnum and stores it in @vidb. It also checks CRC checksum of the read
+ * volume identifier header. The error codes are the same as in
+ * 'ubi_io_read_ec_hdr()'.
+ *
+ * Note, the implementation of this function is also very similar to
+ * 'ubi_io_read_ec_hdr()', so refer commentaries in 'ubi_io_read_ec_hdr()'.
+ */
+int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
+			struct ubi_vid_io_buf *vidb, int verbose)
+{
+	int err, read_err;
+	uint32_t crc, magic, hdr_crc;
+	struct ubi_vid_hdr *vid_hdr = ubi_get_vid_hdr(vidb);
+	void *p = vidb->buffer;
+
+	dbg_io("read VID header from PEB %d", pnum);
+	ubi_assert(pnum >= 0 &&  pnum < ubi->peb_count);
+
+	read_err = ubi_io_read(ubi, p, pnum, ubi->vid_hdr_aloffset,
+			  ubi->vid_hdr_shift + UBI_VID_HDR_SIZE);
+	if (read_err && read_err != UBI_IO_BITFLIPS && !mtd_is_eccerr(read_err))
+		return read_err;
+
+	magic = be32_to_cpu(vid_hdr->magic);
+	if (magic != UBI_VID_HDR_MAGIC) {
+		if (mtd_is_eccerr(read_err))
+			return UBI_IO_BAD_HDR_EBADMSG;
+
+		if (ubi_check_pattern(vid_hdr, 0xFF, UBI_VID_HDR_SIZE)) {
+			if (verbose)
+				ubi_warn(ubi, "no VID header found at PEB %d, only 0xFF bytes",
+					 pnum);
+			dbg_bld("no VID header found at PEB %d, only 0xFF bytes",
+				pnum);
+			if (!read_err)
+				return UBI_IO_FF;
+			else
+				return UBI_IO_FF_BITFLIPS;
+		}
+
+		if (verbose) {
+			ubi_warn(ubi, "bad magic number at PEB %d: %08x instead of %08x",
+				 pnum, magic, UBI_VID_HDR_MAGIC);
+			ubi_dump_vid_hdr(vid_hdr);
+		}
+		dbg_bld("bad magic number at PEB %d: %08x instead of %08x",
+			pnum, magic, UBI_VID_HDR_MAGIC);
+		return UBI_IO_BAD_HDR;
+	}
+
+	crc = crc32(UBI_CRC32_INIT, vid_hdr, UBI_VID_HDR_SIZE_CRC);
+	hdr_crc = be32_to_cpu(vid_hdr->hdr_crc);
+
+	if (hdr_crc != crc) {
+		if (verbose) {
+			ubi_warn(ubi, "bad CRC at PEB %d, calculated %#08x, read %#08x",
+				 pnum, crc, hdr_crc);
+			ubi_dump_vid_hdr(vid_hdr);
+		}
+		dbg_bld("bad CRC at PEB %d, calculated %#08x, read %#08x",
+			pnum, crc, hdr_crc);
+		if (!read_err)
+			return UBI_IO_BAD_HDR;
+		else
+			return UBI_IO_BAD_HDR_EBADMSG;
+	}
+
+	err = validate_vid_hdr(ubi, vid_hdr);
+	if (err) {
+		ubi_err(ubi, "validation failed for PEB %d", pnum);
+		return -EINVAL;
+	}
+
+	return read_err ? UBI_IO_BITFLIPS : 0;
+}
+
+/**
+ * ubi_io_write_vid_hdr - write a volume identifier header.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to write to
+ * @vidb: the volume identifier buffer to write
+ *
+ * This function writes the volume identifier header described by @vid_hdr to
+ * physical eraseblock @pnum. This function automatically fills the
+ * @vidb->hdr->magic and the @vidb->hdr->version fields, as well as calculates
+ * header CRC checksum and stores it at vidb->hdr->hdr_crc.
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure. If %-EIO is returned, the physical eraseblock probably went
+ * bad.
+ */
+int ubi_io_write_vid_hdr(struct ubi_device *ubi, int pnum,
+			 struct ubi_vid_io_buf *vidb)
+{
+	struct ubi_vid_hdr *vid_hdr = ubi_get_vid_hdr(vidb);
+	int err;
+	uint32_t crc;
+	void *p = vidb->buffer;
+
+	dbg_io("write VID header to PEB %d", pnum);
+	ubi_assert(pnum >= 0 &&  pnum < ubi->peb_count);
+
+	err = self_check_peb_ec_hdr(ubi, pnum);
+	if (err)
+		return err;
+
+	vid_hdr->magic = cpu_to_be32(UBI_VID_HDR_MAGIC);
+	vid_hdr->version = UBI_VERSION;
+	crc = crc32(UBI_CRC32_INIT, vid_hdr, UBI_VID_HDR_SIZE_CRC);
+	vid_hdr->hdr_crc = cpu_to_be32(crc);
+
+	err = self_check_vid_hdr(ubi, pnum, vid_hdr);
+	if (err)
+		return err;
+
+	if (ubi_dbg_power_cut(ubi, POWER_CUT_VID_WRITE))
+		return -EROFS;
+
+	err = ubi_io_write(ubi, p, pnum, ubi->vid_hdr_aloffset,
+			   ubi->vid_hdr_alsize);
+	return err;
+}
+
+/**
+ * self_check_not_bad - ensure that a physical eraseblock is not bad.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock number to check
+ *
+ * This function returns zero if the physical eraseblock is good, %-EINVAL if
+ * it is bad and a negative error code if an error occurred.
+ */
+static int self_check_not_bad(const struct ubi_device *ubi, int pnum)
+{
+	int err;
+
+	if (!ubi_dbg_chk_io(ubi))
+		return 0;
+
+	err = ubi_io_is_bad(ubi, pnum);
+	if (!err)
+		return err;
+
+	ubi_err(ubi, "self-check failed for PEB %d", pnum);
+	dump_stack();
+	return err > 0 ? -EINVAL : err;
+}
+
+/**
+ * self_check_ec_hdr - check if an erase counter header is all right.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock number the erase counter header belongs to
+ * @ec_hdr: the erase counter header to check
+ *
+ * This function returns zero if the erase counter header contains valid
+ * values, and %-EINVAL if not.
+ */
+static int self_check_ec_hdr(const struct ubi_device *ubi, int pnum,
+			     const struct ubi_ec_hdr *ec_hdr)
+{
+	int err;
+	uint32_t magic;
+
+	if (!ubi_dbg_chk_io(ubi))
+		return 0;
+
+	magic = be32_to_cpu(ec_hdr->magic);
+	if (magic != UBI_EC_HDR_MAGIC) {
+		ubi_err(ubi, "bad magic %#08x, must be %#08x",
+			magic, UBI_EC_HDR_MAGIC);
+		goto fail;
+	}
+
+	err = validate_ec_hdr(ubi, ec_hdr);
+	if (err) {
+		ubi_err(ubi, "self-check failed for PEB %d", pnum);
+		goto fail;
+	}
+
+	return 0;
+
+fail:
+	ubi_dump_ec_hdr(ec_hdr);
+	dump_stack();
+	return -EINVAL;
+}
+
+/**
+ * self_check_peb_ec_hdr - check erase counter header.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to check
+ *
+ * This function returns zero if the erase counter header is all right and
+ * a negative error code if not or if an error occurred.
+ */
+static int self_check_peb_ec_hdr(const struct ubi_device *ubi, int pnum)
+{
+	int err;
+	uint32_t crc, hdr_crc;
+	struct ubi_ec_hdr *ec_hdr;
+
+	if (!ubi_dbg_chk_io(ubi))
+		return 0;
+
+	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_NOFS);
+	if (!ec_hdr)
+		return -ENOMEM;
+
+	err = ubi_io_read(ubi, ec_hdr, pnum, 0, UBI_EC_HDR_SIZE);
+	if (err && err != UBI_IO_BITFLIPS && !mtd_is_eccerr(err))
+		goto exit;
+
+	crc = crc32(UBI_CRC32_INIT, ec_hdr, UBI_EC_HDR_SIZE_CRC);
+	hdr_crc = be32_to_cpu(ec_hdr->hdr_crc);
+	if (hdr_crc != crc) {
+		ubi_err(ubi, "bad CRC, calculated %#08x, read %#08x",
+			crc, hdr_crc);
+		ubi_err(ubi, "self-check failed for PEB %d", pnum);
+		ubi_dump_ec_hdr(ec_hdr);
+		dump_stack();
+		err = -EINVAL;
+		goto exit;
+	}
+
+	err = self_check_ec_hdr(ubi, pnum, ec_hdr);
+
+exit:
+	kfree(ec_hdr);
+	return err;
+}
+
+/**
+ * self_check_vid_hdr - check that a volume identifier header is all right.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock number the volume identifier header belongs to
+ * @vid_hdr: the volume identifier header to check
+ *
+ * This function returns zero if the volume identifier header is all right, and
+ * %-EINVAL if not.
+ */
+static int self_check_vid_hdr(const struct ubi_device *ubi, int pnum,
+			      const struct ubi_vid_hdr *vid_hdr)
+{
+	int err;
+	uint32_t magic;
+
+	if (!ubi_dbg_chk_io(ubi))
+		return 0;
+
+	magic = be32_to_cpu(vid_hdr->magic);
+	if (magic != UBI_VID_HDR_MAGIC) {
+		ubi_err(ubi, "bad VID header magic %#08x at PEB %d, must be %#08x",
+			magic, pnum, UBI_VID_HDR_MAGIC);
+		goto fail;
+	}
+
+	err = validate_vid_hdr(ubi, vid_hdr);
+	if (err) {
+		ubi_err(ubi, "self-check failed for PEB %d", pnum);
+		goto fail;
+	}
+
+	return err;
+
+fail:
+	ubi_err(ubi, "self-check failed for PEB %d", pnum);
+	ubi_dump_vid_hdr(vid_hdr);
+	dump_stack();
+	return -EINVAL;
+
+}
+
+/**
+ * self_check_peb_vid_hdr - check volume identifier header.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to check
+ *
+ * This function returns zero if the volume identifier header is all right,
+ * and a negative error code if not or if an error occurred.
+ */
+static int self_check_peb_vid_hdr(const struct ubi_device *ubi, int pnum)
+{
+	int err;
+	uint32_t crc, hdr_crc;
+	struct ubi_vid_io_buf *vidb;
+	struct ubi_vid_hdr *vid_hdr;
+	void *p;
+
+	if (!ubi_dbg_chk_io(ubi))
+		return 0;
+
+	vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS);
+	if (!vidb)
+		return -ENOMEM;
+
+	vid_hdr = ubi_get_vid_hdr(vidb);
+	p = vidb->buffer;
+	err = ubi_io_read(ubi, p, pnum, ubi->vid_hdr_aloffset,
+			  ubi->vid_hdr_alsize);
+	if (err && err != UBI_IO_BITFLIPS && !mtd_is_eccerr(err))
+		goto exit;
+
+	crc = crc32(UBI_CRC32_INIT, vid_hdr, UBI_VID_HDR_SIZE_CRC);
+	hdr_crc = be32_to_cpu(vid_hdr->hdr_crc);
+	if (hdr_crc != crc) {
+		ubi_err(ubi, "bad VID header CRC at PEB %d, calculated %#08x, read %#08x",
+			pnum, crc, hdr_crc);
+		ubi_err(ubi, "self-check failed for PEB %d", pnum);
+		ubi_dump_vid_hdr(vid_hdr);
+		dump_stack();
+		err = -EINVAL;
+		goto exit;
+	}
+
+	err = self_check_vid_hdr(ubi, pnum, vid_hdr);
+
+exit:
+	ubi_free_vid_buf(vidb);
+	return err;
+}
+
+/**
+ * self_check_write - make sure write succeeded.
+ * @ubi: UBI device description object
+ * @buf: buffer with data which were written
+ * @pnum: physical eraseblock number the data were written to
+ * @offset: offset within the physical eraseblock the data were written to
+ * @len: how many bytes were written
+ *
+ * This functions reads data which were recently written and compares it with
+ * the original data buffer - the data have to match. Returns zero if the data
+ * match and a negative error code if not or in case of failure.
+ */
+static int self_check_write(struct ubi_device *ubi, const void *buf, int pnum,
+			    int offset, int len)
+{
+	int err, i;
+	size_t read;
+	void *buf1;
+	loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
+
+	if (!ubi_dbg_chk_io(ubi))
+		return 0;
+
+	buf1 = __vmalloc(len, GFP_NOFS);
+	if (!buf1) {
+		ubi_err(ubi, "cannot allocate memory to check writes");
+		return 0;
+	}
+
+	err = mtd_read(ubi->mtd, addr, len, &read, buf1);
+	if (err && !mtd_is_bitflip(err))
+		goto out_free;
+
+	for (i = 0; i < len; i++) {
+		uint8_t c = ((uint8_t *)buf)[i];
+		uint8_t c1 = ((uint8_t *)buf1)[i];
+		int dump_len;
+
+		if (c == c1)
+			continue;
+
+		ubi_err(ubi, "self-check failed for PEB %d:%d, len %d",
+			pnum, offset, len);
+		ubi_msg(ubi, "data differ at position %d", i);
+		dump_len = max_t(int, 128, len - i);
+		ubi_msg(ubi, "hex dump of the original buffer from %d to %d",
+			i, i + dump_len);
+		print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
+			       buf + i, dump_len, 1);
+		ubi_msg(ubi, "hex dump of the read buffer from %d to %d",
+			i, i + dump_len);
+		print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1,
+			       buf1 + i, dump_len, 1);
+		dump_stack();
+		err = -EINVAL;
+		goto out_free;
+	}
+
+	vfree(buf1);
+	return 0;
+
+out_free:
+	vfree(buf1);
+	return err;
+}
+
+/**
+ * ubi_self_check_all_ff - check that a region of flash is empty.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to check
+ * @offset: the starting offset within the physical eraseblock to check
+ * @len: the length of the region to check
+ *
+ * This function returns zero if only 0xFF bytes are present at offset
+ * @offset of the physical eraseblock @pnum, and a negative error code if not
+ * or if an error occurred.
+ */
+int ubi_self_check_all_ff(struct ubi_device *ubi, int pnum, int offset, int len)
+{
+	size_t read;
+	int err;
+	void *buf;
+	loff_t addr = (loff_t)pnum * ubi->peb_size + offset;
+
+	if (!ubi_dbg_chk_io(ubi))
+		return 0;
+
+	buf = __vmalloc(len, GFP_NOFS);
+	if (!buf) {
+		ubi_err(ubi, "cannot allocate memory to check for 0xFFs");
+		return 0;
+	}
+
+	err = mtd_read(ubi->mtd, addr, len, &read, buf);
+	if (err && !mtd_is_bitflip(err)) {
+		ubi_err(ubi, "err %d while reading %d bytes from PEB %d:%d, read %zd bytes",
+			err, len, pnum, offset, read);
+		goto error;
+	}
+
+	err = ubi_check_pattern(buf, 0xFF, len);
+	if (err == 0) {
+		ubi_err(ubi, "flash region at PEB %d:%d, length %d does not contain all 0xFF bytes",
+			pnum, offset, len);
+		goto fail;
+	}
+
+	vfree(buf);
+	return 0;
+
+fail:
+	ubi_err(ubi, "self-check failed for PEB %d", pnum);
+	ubi_msg(ubi, "hex dump of the %d-%d region", offset, offset + len);
+	print_hex_dump(KERN_DEBUG, "", DUMP_PREFIX_OFFSET, 32, 1, buf, len, 1);
+	err = -EINVAL;
+error:
+	dump_stack();
+	vfree(buf);
+	return err;
+}
diff --git a/drivers/mtd/ubi/kapi.c b/drivers/mtd/ubi/kapi.c
new file mode 100644
index 0000000000..5db653eacb
--- /dev/null
+++ b/drivers/mtd/ubi/kapi.c
@@ -0,0 +1,855 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+/* This file mostly implements UBI kernel API functions */
+
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/namei.h>
+#include <linux/fs.h>
+#include <asm/div64.h>
+#include "ubi.h"
+
+/**
+ * ubi_do_get_device_info - get information about UBI device.
+ * @ubi: UBI device description object
+ * @di: the information is stored here
+ *
+ * This function is the same as 'ubi_get_device_info()', but it assumes the UBI
+ * device is locked and cannot disappear.
+ */
+void ubi_do_get_device_info(struct ubi_device *ubi, struct ubi_device_info *di)
+{
+	di->ubi_num = ubi->ubi_num;
+	di->leb_size = ubi->leb_size;
+	di->leb_start = ubi->leb_start;
+	di->min_io_size = ubi->min_io_size;
+	di->max_write_size = ubi->max_write_size;
+	di->ro_mode = ubi->ro_mode;
+	di->cdev = ubi->cdev.dev;
+}
+EXPORT_SYMBOL_GPL(ubi_do_get_device_info);
+
+/**
+ * ubi_get_device_info - get information about UBI device.
+ * @ubi_num: UBI device number
+ * @di: the information is stored here
+ *
+ * This function returns %0 in case of success, %-EINVAL if the UBI device
+ * number is invalid, and %-ENODEV if there is no such UBI device.
+ */
+int ubi_get_device_info(int ubi_num, struct ubi_device_info *di)
+{
+	struct ubi_device *ubi;
+
+	if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
+		return -EINVAL;
+	ubi = ubi_get_device(ubi_num);
+	if (!ubi)
+		return -ENODEV;
+	ubi_do_get_device_info(ubi, di);
+	ubi_put_device(ubi);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ubi_get_device_info);
+
+/**
+ * ubi_do_get_volume_info - get information about UBI volume.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ * @vi: the information is stored here
+ */
+void ubi_do_get_volume_info(struct ubi_device *ubi, struct ubi_volume *vol,
+			    struct ubi_volume_info *vi)
+{
+	vi->vol_id = vol->vol_id;
+	vi->ubi_num = ubi->ubi_num;
+	vi->size = vol->reserved_pebs;
+	vi->used_bytes = vol->used_bytes;
+	vi->vol_type = vol->vol_type;
+	vi->corrupted = vol->corrupted;
+	vi->upd_marker = vol->upd_marker;
+	vi->alignment = vol->alignment;
+	vi->usable_leb_size = vol->usable_leb_size;
+	vi->name_len = vol->name_len;
+	vi->name = vol->name;
+	vi->cdev = vol->cdev.dev;
+	vi->dev = &vol->dev;
+}
+
+/**
+ * ubi_get_volume_info - get information about UBI volume.
+ * @desc: volume descriptor
+ * @vi: the information is stored here
+ */
+void ubi_get_volume_info(struct ubi_volume_desc *desc,
+			 struct ubi_volume_info *vi)
+{
+	ubi_do_get_volume_info(desc->vol->ubi, desc->vol, vi);
+}
+EXPORT_SYMBOL_GPL(ubi_get_volume_info);
+
+/**
+ * ubi_open_volume - open UBI volume.
+ * @ubi_num: UBI device number
+ * @vol_id: volume ID
+ * @mode: open mode
+ *
+ * The @mode parameter specifies if the volume should be opened in read-only
+ * mode, read-write mode, or exclusive mode. The exclusive mode guarantees that
+ * nobody else will be able to open this volume. UBI allows to have many volume
+ * readers and one writer at a time.
+ *
+ * If a static volume is being opened for the first time since boot, it will be
+ * checked by this function, which means it will be fully read and the CRC
+ * checksum of each logical eraseblock will be checked.
+ *
+ * This function returns volume descriptor in case of success and a negative
+ * error code in case of failure.
+ */
+struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode)
+{
+	int err;
+	struct ubi_volume_desc *desc;
+	struct ubi_device *ubi;
+	struct ubi_volume *vol;
+
+	dbg_gen("open device %d, volume %d, mode %d", ubi_num, vol_id, mode);
+
+	if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
+		return ERR_PTR(-EINVAL);
+
+	if (mode != UBI_READONLY && mode != UBI_READWRITE &&
+	    mode != UBI_EXCLUSIVE && mode != UBI_METAONLY)
+		return ERR_PTR(-EINVAL);
+
+	/*
+	 * First of all, we have to get the UBI device to prevent its removal.
+	 */
+	ubi = ubi_get_device(ubi_num);
+	if (!ubi)
+		return ERR_PTR(-ENODEV);
+
+	if (vol_id < 0 || vol_id >= ubi->vtbl_slots) {
+		err = -EINVAL;
+		goto out_put_ubi;
+	}
+
+	desc = kmalloc(sizeof(struct ubi_volume_desc), GFP_KERNEL);
+	if (!desc) {
+		err = -ENOMEM;
+		goto out_put_ubi;
+	}
+
+	err = -ENODEV;
+	if (!try_module_get(THIS_MODULE))
+		goto out_free;
+
+	spin_lock(&ubi->volumes_lock);
+	vol = ubi->volumes[vol_id];
+	if (!vol)
+		goto out_unlock;
+
+	err = -EBUSY;
+	switch (mode) {
+	case UBI_READONLY:
+		if (vol->exclusive)
+			goto out_unlock;
+		vol->readers += 1;
+		break;
+
+	case UBI_READWRITE:
+		if (vol->exclusive || vol->writers > 0)
+			goto out_unlock;
+		vol->writers += 1;
+		break;
+
+	case UBI_EXCLUSIVE:
+		if (vol->exclusive || vol->writers || vol->readers ||
+		    vol->metaonly)
+			goto out_unlock;
+		vol->exclusive = 1;
+		break;
+
+	case UBI_METAONLY:
+		if (vol->metaonly || vol->exclusive)
+			goto out_unlock;
+		vol->metaonly = 1;
+		break;
+	}
+	get_device(&vol->dev);
+	vol->ref_count += 1;
+	spin_unlock(&ubi->volumes_lock);
+
+	desc->vol = vol;
+	desc->mode = mode;
+
+	mutex_lock(&ubi->ckvol_mutex);
+	if (!vol->checked && !vol->skip_check) {
+		/* This is the first open - check the volume */
+		err = ubi_check_volume(ubi, vol_id);
+		if (err < 0) {
+			mutex_unlock(&ubi->ckvol_mutex);
+			ubi_close_volume(desc);
+			return ERR_PTR(err);
+		}
+		if (err == 1) {
+			ubi_warn(ubi, "volume %d on UBI device %d is corrupted",
+				 vol_id, ubi->ubi_num);
+			vol->corrupted = 1;
+		}
+		vol->checked = 1;
+	}
+	mutex_unlock(&ubi->ckvol_mutex);
+
+	return desc;
+
+out_unlock:
+	spin_unlock(&ubi->volumes_lock);
+	module_put(THIS_MODULE);
+out_free:
+	kfree(desc);
+out_put_ubi:
+	ubi_err(ubi, "cannot open device %d, volume %d, error %d",
+		ubi_num, vol_id, err);
+	ubi_put_device(ubi);
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(ubi_open_volume);
+
+/**
+ * ubi_open_volume_nm - open UBI volume by name.
+ * @ubi_num: UBI device number
+ * @name: volume name
+ * @mode: open mode
+ *
+ * This function is similar to 'ubi_open_volume()', but opens a volume by name.
+ */
+struct ubi_volume_desc *ubi_open_volume_nm(int ubi_num, const char *name,
+					   int mode)
+{
+	int i, vol_id = -1, len;
+	struct ubi_device *ubi;
+	struct ubi_volume_desc *ret;
+
+	dbg_gen("open device %d, volume %s, mode %d", ubi_num, name, mode);
+
+	if (!name)
+		return ERR_PTR(-EINVAL);
+
+	len = strnlen(name, UBI_VOL_NAME_MAX + 1);
+	if (len > UBI_VOL_NAME_MAX)
+		return ERR_PTR(-EINVAL);
+
+	if (ubi_num < 0 || ubi_num >= UBI_MAX_DEVICES)
+		return ERR_PTR(-EINVAL);
+
+	ubi = ubi_get_device(ubi_num);
+	if (!ubi)
+		return ERR_PTR(-ENODEV);
+
+	spin_lock(&ubi->volumes_lock);
+	/* Walk all volumes of this UBI device */
+	for (i = 0; i < ubi->vtbl_slots; i++) {
+		struct ubi_volume *vol = ubi->volumes[i];
+
+		if (vol && len == vol->name_len && !strcmp(name, vol->name)) {
+			vol_id = i;
+			break;
+		}
+	}
+	spin_unlock(&ubi->volumes_lock);
+
+	if (vol_id >= 0)
+		ret = ubi_open_volume(ubi_num, vol_id, mode);
+	else
+		ret = ERR_PTR(-ENODEV);
+
+	/*
+	 * We should put the UBI device even in case of success, because
+	 * 'ubi_open_volume()' took a reference as well.
+	 */
+	ubi_put_device(ubi);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(ubi_open_volume_nm);
+
+/**
+ * ubi_open_volume_path - open UBI volume by its character device node path.
+ * @pathname: volume character device node path
+ * @mode: open mode
+ *
+ * This function is similar to 'ubi_open_volume()', but opens a volume the path
+ * to its character device node.
+ */
+struct ubi_volume_desc *ubi_open_volume_path(const char *pathname, int mode)
+{
+	int error, ubi_num, vol_id;
+	struct path path;
+	struct kstat stat;
+
+	dbg_gen("open volume %s, mode %d", pathname, mode);
+
+	if (!pathname || !*pathname)
+		return ERR_PTR(-EINVAL);
+
+	error = kern_path(pathname, LOOKUP_FOLLOW, &path);
+	if (error)
+		return ERR_PTR(error);
+
+	error = vfs_getattr(&path, &stat, STATX_TYPE, AT_STATX_SYNC_AS_STAT);
+	path_put(&path);
+	if (error)
+		return ERR_PTR(error);
+
+	if (!S_ISCHR(stat.mode))
+		return ERR_PTR(-EINVAL);
+
+	ubi_num = ubi_major2num(MAJOR(stat.rdev));
+	vol_id = MINOR(stat.rdev) - 1;
+
+	if (vol_id >= 0 && ubi_num >= 0)
+		return ubi_open_volume(ubi_num, vol_id, mode);
+	return ERR_PTR(-ENODEV);
+}
+EXPORT_SYMBOL_GPL(ubi_open_volume_path);
+
+/**
+ * ubi_close_volume - close UBI volume.
+ * @desc: volume descriptor
+ */
+void ubi_close_volume(struct ubi_volume_desc *desc)
+{
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+
+	dbg_gen("close device %d, volume %d, mode %d",
+		ubi->ubi_num, vol->vol_id, desc->mode);
+
+	spin_lock(&ubi->volumes_lock);
+	switch (desc->mode) {
+	case UBI_READONLY:
+		vol->readers -= 1;
+		break;
+	case UBI_READWRITE:
+		vol->writers -= 1;
+		break;
+	case UBI_EXCLUSIVE:
+		vol->exclusive = 0;
+		break;
+	case UBI_METAONLY:
+		vol->metaonly = 0;
+		break;
+	}
+	vol->ref_count -= 1;
+	spin_unlock(&ubi->volumes_lock);
+
+	kfree(desc);
+	put_device(&vol->dev);
+	ubi_put_device(ubi);
+	module_put(THIS_MODULE);
+}
+EXPORT_SYMBOL_GPL(ubi_close_volume);
+
+/**
+ * leb_read_sanity_check - does sanity checks on read requests.
+ * @desc: volume descriptor
+ * @lnum: logical eraseblock number to read from
+ * @offset: offset within the logical eraseblock to read from
+ * @len: how many bytes to read
+ *
+ * This function is used by ubi_leb_read() and ubi_leb_read_sg()
+ * to perform sanity checks.
+ */
+static int leb_read_sanity_check(struct ubi_volume_desc *desc, int lnum,
+				 int offset, int len)
+{
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+	int vol_id = vol->vol_id;
+
+	if (vol_id < 0 || vol_id >= ubi->vtbl_slots || lnum < 0 ||
+	    lnum >= vol->used_ebs || offset < 0 || len < 0 ||
+	    offset + len > vol->usable_leb_size)
+		return -EINVAL;
+
+	if (vol->vol_type == UBI_STATIC_VOLUME) {
+		if (vol->used_ebs == 0)
+			/* Empty static UBI volume */
+			return 0;
+		if (lnum == vol->used_ebs - 1 &&
+		    offset + len > vol->last_eb_bytes)
+			return -EINVAL;
+	}
+
+	if (vol->upd_marker)
+		return -EBADF;
+
+	return 0;
+}
+
+/**
+ * ubi_leb_read - read data.
+ * @desc: volume descriptor
+ * @lnum: logical eraseblock number to read from
+ * @buf: buffer where to store the read data
+ * @offset: offset within the logical eraseblock to read from
+ * @len: how many bytes to read
+ * @check: whether UBI has to check the read data's CRC or not.
+ *
+ * This function reads data from offset @offset of logical eraseblock @lnum and
+ * stores the data at @buf. When reading from static volumes, @check specifies
+ * whether the data has to be checked or not. If yes, the whole logical
+ * eraseblock will be read and its CRC checksum will be checked (i.e., the CRC
+ * checksum is per-eraseblock). So checking may substantially slow down the
+ * read speed. The @check argument is ignored for dynamic volumes.
+ *
+ * In case of success, this function returns zero. In case of failure, this
+ * function returns a negative error code.
+ *
+ * %-EBADMSG error code is returned:
+ * o for both static and dynamic volumes if MTD driver has detected a data
+ *   integrity problem (unrecoverable ECC checksum mismatch in case of NAND);
+ * o for static volumes in case of data CRC mismatch.
+ *
+ * If the volume is damaged because of an interrupted update this function just
+ * returns immediately with %-EBADF error code.
+ */
+int ubi_leb_read(struct ubi_volume_desc *desc, int lnum, char *buf, int offset,
+		 int len, int check)
+{
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+	int err, vol_id = vol->vol_id;
+
+	dbg_gen("read %d bytes from LEB %d:%d:%d", len, vol_id, lnum, offset);
+
+	err = leb_read_sanity_check(desc, lnum, offset, len);
+	if (err < 0)
+		return err;
+
+	if (len == 0)
+		return 0;
+
+	err = ubi_eba_read_leb(ubi, vol, lnum, buf, offset, len, check);
+	if (err && mtd_is_eccerr(err) && vol->vol_type == UBI_STATIC_VOLUME) {
+		ubi_warn(ubi, "mark volume %d as corrupted", vol_id);
+		vol->corrupted = 1;
+	}
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(ubi_leb_read);
+
+
+/**
+ * ubi_leb_read_sg - read data into a scatter gather list.
+ * @desc: volume descriptor
+ * @lnum: logical eraseblock number to read from
+ * @sgl: UBI scatter gather list to store the read data
+ * @offset: offset within the logical eraseblock to read from
+ * @len: how many bytes to read
+ * @check: whether UBI has to check the read data's CRC or not.
+ *
+ * This function works exactly like ubi_leb_read_sg(). But instead of
+ * storing the read data into a buffer it writes to an UBI scatter gather
+ * list.
+ */
+int ubi_leb_read_sg(struct ubi_volume_desc *desc, int lnum, struct ubi_sgl *sgl,
+		    int offset, int len, int check)
+{
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+	int err, vol_id = vol->vol_id;
+
+	dbg_gen("read %d bytes from LEB %d:%d:%d", len, vol_id, lnum, offset);
+
+	err = leb_read_sanity_check(desc, lnum, offset, len);
+	if (err < 0)
+		return err;
+
+	if (len == 0)
+		return 0;
+
+	err = ubi_eba_read_leb_sg(ubi, vol, sgl, lnum, offset, len, check);
+	if (err && mtd_is_eccerr(err) && vol->vol_type == UBI_STATIC_VOLUME) {
+		ubi_warn(ubi, "mark volume %d as corrupted", vol_id);
+		vol->corrupted = 1;
+	}
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(ubi_leb_read_sg);
+
+/**
+ * ubi_leb_write - write data.
+ * @desc: volume descriptor
+ * @lnum: logical eraseblock number to write to
+ * @buf: data to write
+ * @offset: offset within the logical eraseblock where to write
+ * @len: how many bytes to write
+ *
+ * This function writes @len bytes of data from @buf to offset @offset of
+ * logical eraseblock @lnum.
+ *
+ * This function takes care of physical eraseblock write failures. If write to
+ * the physical eraseblock write operation fails, the logical eraseblock is
+ * re-mapped to another physical eraseblock, the data is recovered, and the
+ * write finishes. UBI has a pool of reserved physical eraseblocks for this.
+ *
+ * If all the data were successfully written, zero is returned. If an error
+ * occurred and UBI has not been able to recover from it, this function returns
+ * a negative error code. Note, in case of an error, it is possible that
+ * something was still written to the flash media, but that may be some
+ * garbage.
+ *
+ * If the volume is damaged because of an interrupted update this function just
+ * returns immediately with %-EBADF code.
+ */
+int ubi_leb_write(struct ubi_volume_desc *desc, int lnum, const void *buf,
+		  int offset, int len)
+{
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+	int vol_id = vol->vol_id;
+
+	dbg_gen("write %d bytes to LEB %d:%d:%d", len, vol_id, lnum, offset);
+
+	if (vol_id < 0 || vol_id >= ubi->vtbl_slots)
+		return -EINVAL;
+
+	if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
+		return -EROFS;
+
+	if (!ubi_leb_valid(vol, lnum) || offset < 0 || len < 0 ||
+	    offset + len > vol->usable_leb_size ||
+	    offset & (ubi->min_io_size - 1) || len & (ubi->min_io_size - 1))
+		return -EINVAL;
+
+	if (vol->upd_marker)
+		return -EBADF;
+
+	if (len == 0)
+		return 0;
+
+	return ubi_eba_write_leb(ubi, vol, lnum, buf, offset, len);
+}
+EXPORT_SYMBOL_GPL(ubi_leb_write);
+
+/*
+ * ubi_leb_change - change logical eraseblock atomically.
+ * @desc: volume descriptor
+ * @lnum: logical eraseblock number to change
+ * @buf: data to write
+ * @len: how many bytes to write
+ *
+ * This function changes the contents of a logical eraseblock atomically. @buf
+ * has to contain new logical eraseblock data, and @len - the length of the
+ * data, which has to be aligned. The length may be shorter than the logical
+ * eraseblock size, ant the logical eraseblock may be appended to more times
+ * later on. This function guarantees that in case of an unclean reboot the old
+ * contents is preserved. Returns zero in case of success and a negative error
+ * code in case of failure.
+ */
+int ubi_leb_change(struct ubi_volume_desc *desc, int lnum, const void *buf,
+		   int len)
+{
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+	int vol_id = vol->vol_id;
+
+	dbg_gen("atomically write %d bytes to LEB %d:%d", len, vol_id, lnum);
+
+	if (vol_id < 0 || vol_id >= ubi->vtbl_slots)
+		return -EINVAL;
+
+	if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
+		return -EROFS;
+
+	if (!ubi_leb_valid(vol, lnum) || len < 0 ||
+	    len > vol->usable_leb_size || len & (ubi->min_io_size - 1))
+		return -EINVAL;
+
+	if (vol->upd_marker)
+		return -EBADF;
+
+	if (len == 0)
+		return 0;
+
+	return ubi_eba_atomic_leb_change(ubi, vol, lnum, buf, len);
+}
+EXPORT_SYMBOL_GPL(ubi_leb_change);
+
+/**
+ * ubi_leb_erase - erase logical eraseblock.
+ * @desc: volume descriptor
+ * @lnum: logical eraseblock number
+ *
+ * This function un-maps logical eraseblock @lnum and synchronously erases the
+ * correspondent physical eraseblock. Returns zero in case of success and a
+ * negative error code in case of failure.
+ *
+ * If the volume is damaged because of an interrupted update this function just
+ * returns immediately with %-EBADF code.
+ */
+int ubi_leb_erase(struct ubi_volume_desc *desc, int lnum)
+{
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+	int err;
+
+	dbg_gen("erase LEB %d:%d", vol->vol_id, lnum);
+
+	if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
+		return -EROFS;
+
+	if (!ubi_leb_valid(vol, lnum))
+		return -EINVAL;
+
+	if (vol->upd_marker)
+		return -EBADF;
+
+	err = ubi_eba_unmap_leb(ubi, vol, lnum);
+	if (err)
+		return err;
+
+	return ubi_wl_flush(ubi, vol->vol_id, lnum);
+}
+EXPORT_SYMBOL_GPL(ubi_leb_erase);
+
+/**
+ * ubi_leb_unmap - un-map logical eraseblock.
+ * @desc: volume descriptor
+ * @lnum: logical eraseblock number
+ *
+ * This function un-maps logical eraseblock @lnum and schedules the
+ * corresponding physical eraseblock for erasure, so that it will eventually be
+ * physically erased in background. This operation is much faster than the
+ * erase operation.
+ *
+ * Unlike erase, the un-map operation does not guarantee that the logical
+ * eraseblock will contain all 0xFF bytes when UBI is initialized again. For
+ * example, if several logical eraseblocks are un-mapped, and an unclean reboot
+ * happens after this, the logical eraseblocks will not necessarily be
+ * un-mapped again when this MTD device is attached. They may actually be
+ * mapped to the same physical eraseblocks again. So, this function has to be
+ * used with care.
+ *
+ * In other words, when un-mapping a logical eraseblock, UBI does not store
+ * any information about this on the flash media, it just marks the logical
+ * eraseblock as "un-mapped" in RAM. If UBI is detached before the physical
+ * eraseblock is physically erased, it will be mapped again to the same logical
+ * eraseblock when the MTD device is attached again.
+ *
+ * The main and obvious use-case of this function is when the contents of a
+ * logical eraseblock has to be re-written. Then it is much more efficient to
+ * first un-map it, then write new data, rather than first erase it, then write
+ * new data. Note, once new data has been written to the logical eraseblock,
+ * UBI guarantees that the old contents has gone forever. In other words, if an
+ * unclean reboot happens after the logical eraseblock has been un-mapped and
+ * then written to, it will contain the last written data.
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure. If the volume is damaged because of an interrupted update
+ * this function just returns immediately with %-EBADF code.
+ */
+int ubi_leb_unmap(struct ubi_volume_desc *desc, int lnum)
+{
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+
+	dbg_gen("unmap LEB %d:%d", vol->vol_id, lnum);
+
+	if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
+		return -EROFS;
+
+	if (!ubi_leb_valid(vol, lnum))
+		return -EINVAL;
+
+	if (vol->upd_marker)
+		return -EBADF;
+
+	return ubi_eba_unmap_leb(ubi, vol, lnum);
+}
+EXPORT_SYMBOL_GPL(ubi_leb_unmap);
+
+/**
+ * ubi_leb_map - map logical eraseblock to a physical eraseblock.
+ * @desc: volume descriptor
+ * @lnum: logical eraseblock number
+ *
+ * This function maps an un-mapped logical eraseblock @lnum to a physical
+ * eraseblock. This means, that after a successful invocation of this
+ * function the logical eraseblock @lnum will be empty (contain only %0xFF
+ * bytes) and be mapped to a physical eraseblock, even if an unclean reboot
+ * happens.
+ *
+ * This function returns zero in case of success, %-EBADF if the volume is
+ * damaged because of an interrupted update, %-EBADMSG if the logical
+ * eraseblock is already mapped, and other negative error codes in case of
+ * other failures.
+ */
+int ubi_leb_map(struct ubi_volume_desc *desc, int lnum)
+{
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+
+	dbg_gen("map LEB %d:%d", vol->vol_id, lnum);
+
+	if (desc->mode == UBI_READONLY || vol->vol_type == UBI_STATIC_VOLUME)
+		return -EROFS;
+
+	if (!ubi_leb_valid(vol, lnum))
+		return -EINVAL;
+
+	if (vol->upd_marker)
+		return -EBADF;
+
+	if (ubi_eba_is_mapped(vol, lnum))
+		return -EBADMSG;
+
+	return ubi_eba_write_leb(ubi, vol, lnum, NULL, 0, 0);
+}
+EXPORT_SYMBOL_GPL(ubi_leb_map);
+
+/**
+ * ubi_is_mapped - check if logical eraseblock is mapped.
+ * @desc: volume descriptor
+ * @lnum: logical eraseblock number
+ *
+ * This function checks if logical eraseblock @lnum is mapped to a physical
+ * eraseblock. If a logical eraseblock is un-mapped, this does not necessarily
+ * mean it will still be un-mapped after the UBI device is re-attached. The
+ * logical eraseblock may become mapped to the physical eraseblock it was last
+ * mapped to.
+ *
+ * This function returns %1 if the LEB is mapped, %0 if not, and a negative
+ * error code in case of failure. If the volume is damaged because of an
+ * interrupted update this function just returns immediately with %-EBADF error
+ * code.
+ */
+int ubi_is_mapped(struct ubi_volume_desc *desc, int lnum)
+{
+	struct ubi_volume *vol = desc->vol;
+
+	dbg_gen("test LEB %d:%d", vol->vol_id, lnum);
+
+	if (!ubi_leb_valid(vol, lnum))
+		return -EINVAL;
+
+	if (vol->upd_marker)
+		return -EBADF;
+
+	return ubi_eba_is_mapped(vol, lnum);
+}
+EXPORT_SYMBOL_GPL(ubi_is_mapped);
+
+/**
+ * ubi_sync - synchronize UBI device buffers.
+ * @ubi_num: UBI device to synchronize
+ *
+ * The underlying MTD device may cache data in hardware or in software. This
+ * function ensures the caches are flushed. Returns zero in case of success and
+ * a negative error code in case of failure.
+ */
+int ubi_sync(int ubi_num)
+{
+	struct ubi_device *ubi;
+
+	ubi = ubi_get_device(ubi_num);
+	if (!ubi)
+		return -ENODEV;
+
+	mtd_sync(ubi->mtd);
+	ubi_put_device(ubi);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ubi_sync);
+
+/**
+ * ubi_flush - flush UBI work queue.
+ * @ubi_num: UBI device to flush work queue
+ * @vol_id: volume id to flush for
+ * @lnum: logical eraseblock number to flush for
+ *
+ * This function executes all pending works for a particular volume id / logical
+ * eraseblock number pair. If either value is set to %UBI_ALL, then it acts as
+ * a wildcard for all of the corresponding volume numbers or logical
+ * eraseblock numbers. It returns zero in case of success and a negative error
+ * code in case of failure.
+ */
+int ubi_flush(int ubi_num, int vol_id, int lnum)
+{
+	struct ubi_device *ubi;
+	int err = 0;
+
+	ubi = ubi_get_device(ubi_num);
+	if (!ubi)
+		return -ENODEV;
+
+	err = ubi_wl_flush(ubi, vol_id, lnum);
+	ubi_put_device(ubi);
+	return err;
+}
+EXPORT_SYMBOL_GPL(ubi_flush);
+
+BLOCKING_NOTIFIER_HEAD(ubi_notifiers);
+
+/**
+ * ubi_register_volume_notifier - register a volume notifier.
+ * @nb: the notifier description object
+ * @ignore_existing: if non-zero, do not send "added" notification for all
+ *                   already existing volumes
+ *
+ * This function registers a volume notifier, which means that
+ * 'nb->notifier_call()' will be invoked when an UBI  volume is created,
+ * removed, re-sized, re-named, or updated. The first argument of the function
+ * is the notification type. The second argument is pointer to a
+ * &struct ubi_notification object which describes the notification event.
+ * Using UBI API from the volume notifier is prohibited.
+ *
+ * This function returns zero in case of success and a negative error code
+ * in case of failure.
+ */
+int ubi_register_volume_notifier(struct notifier_block *nb,
+				 int ignore_existing)
+{
+	int err;
+
+	err = blocking_notifier_chain_register(&ubi_notifiers, nb);
+	if (err != 0)
+		return err;
+	if (ignore_existing)
+		return 0;
+
+	/*
+	 * We are going to walk all UBI devices and all volumes, and
+	 * notify the user about existing volumes by the %UBI_VOLUME_ADDED
+	 * event. We have to lock the @ubi_devices_mutex to make sure UBI
+	 * devices do not disappear.
+	 */
+	mutex_lock(&ubi_devices_mutex);
+	ubi_enumerate_volumes(nb);
+	mutex_unlock(&ubi_devices_mutex);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(ubi_register_volume_notifier);
+
+/**
+ * ubi_unregister_volume_notifier - unregister the volume notifier.
+ * @nb: the notifier description object
+ *
+ * This function unregisters volume notifier @nm and returns zero in case of
+ * success and a negative error code in case of failure.
+ */
+int ubi_unregister_volume_notifier(struct notifier_block *nb)
+{
+	return blocking_notifier_chain_unregister(&ubi_notifiers, nb);
+}
+EXPORT_SYMBOL_GPL(ubi_unregister_volume_notifier);
diff --git a/drivers/mtd/ubi/misc.c b/drivers/mtd/ubi/misc.c
new file mode 100644
index 0000000000..1794d66b6e
--- /dev/null
+++ b/drivers/mtd/ubi/misc.c
@@ -0,0 +1,191 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+/* Here we keep miscellaneous functions which are used all over the UBI code */
+
+#include "ubi.h"
+
+/**
+ * ubi_calc_data_len - calculate how much real data is stored in a buffer.
+ * @ubi: UBI device description object
+ * @buf: a buffer with the contents of the physical eraseblock
+ * @length: the buffer length
+ *
+ * This function calculates how much "real data" is stored in @buf and returnes
+ * the length. Continuous 0xFF bytes at the end of the buffer are not
+ * considered as "real data".
+ */
+int ubi_calc_data_len(const struct ubi_device *ubi, const void *buf,
+		      int length)
+{
+	int i;
+
+	ubi_assert(!(length & (ubi->min_io_size - 1)));
+
+	for (i = length - 1; i >= 0; i--)
+		if (((const uint8_t *)buf)[i] != 0xFF)
+			break;
+
+	/* The resulting length must be aligned to the minimum flash I/O size */
+	length = ALIGN(i + 1, ubi->min_io_size);
+	return length;
+}
+
+/**
+ * ubi_check_volume - check the contents of a static volume.
+ * @ubi: UBI device description object
+ * @vol_id: ID of the volume to check
+ *
+ * This function checks if static volume @vol_id is corrupted by fully reading
+ * it and checking data CRC. This function returns %0 if the volume is not
+ * corrupted, %1 if it is corrupted and a negative error code in case of
+ * failure. Dynamic volumes are not checked and zero is returned immediately.
+ */
+int ubi_check_volume(struct ubi_device *ubi, int vol_id)
+{
+	void *buf;
+	int err = 0, i;
+	struct ubi_volume *vol = ubi->volumes[vol_id];
+
+	if (vol->vol_type != UBI_STATIC_VOLUME)
+		return 0;
+
+	buf = vmalloc(vol->usable_leb_size);
+	if (!buf)
+		return -ENOMEM;
+
+	for (i = 0; i < vol->used_ebs; i++) {
+		int size;
+
+		cond_resched();
+
+		if (i == vol->used_ebs - 1)
+			size = vol->last_eb_bytes;
+		else
+			size = vol->usable_leb_size;
+
+		err = ubi_eba_read_leb(ubi, vol, i, buf, 0, size, 1);
+		if (err) {
+			if (mtd_is_eccerr(err))
+				err = 1;
+			break;
+		}
+	}
+
+	vfree(buf);
+	return err;
+}
+
+/**
+ * ubi_update_reserved - update bad eraseblock handling accounting data.
+ * @ubi: UBI device description object
+ *
+ * This function calculates the gap between current number of PEBs reserved for
+ * bad eraseblock handling and the required level of PEBs that must be
+ * reserved, and if necessary, reserves more PEBs to fill that gap, according
+ * to availability. Should be called with ubi->volumes_lock held.
+ */
+void ubi_update_reserved(struct ubi_device *ubi)
+{
+	int need = ubi->beb_rsvd_level - ubi->beb_rsvd_pebs;
+
+	if (need <= 0 || ubi->avail_pebs == 0)
+		return;
+
+	need = min_t(int, need, ubi->avail_pebs);
+	ubi->avail_pebs -= need;
+	ubi->rsvd_pebs += need;
+	ubi->beb_rsvd_pebs += need;
+	ubi_msg(ubi, "reserved more %d PEBs for bad PEB handling", need);
+}
+
+/**
+ * ubi_calculate_reserved - calculate how many PEBs must be reserved for bad
+ * eraseblock handling.
+ * @ubi: UBI device description object
+ */
+void ubi_calculate_reserved(struct ubi_device *ubi)
+{
+	/*
+	 * Calculate the actual number of PEBs currently needed to be reserved
+	 * for future bad eraseblock handling.
+	 */
+	ubi->beb_rsvd_level = ubi->bad_peb_limit - ubi->bad_peb_count;
+	if (ubi->beb_rsvd_level < 0) {
+		ubi->beb_rsvd_level = 0;
+		ubi_warn(ubi, "number of bad PEBs (%d) is above the expected limit (%d), not reserving any PEBs for bad PEB handling, will use available PEBs (if any)",
+			 ubi->bad_peb_count, ubi->bad_peb_limit);
+	}
+}
+
+/**
+ * ubi_check_pattern - check if buffer contains only a certain byte pattern.
+ * @buf: buffer to check
+ * @patt: the pattern to check
+ * @size: buffer size in bytes
+ *
+ * This function returns %1 in there are only @patt bytes in @buf, and %0 if
+ * something else was also found.
+ */
+int ubi_check_pattern(const void *buf, uint8_t patt, int size)
+{
+	int i;
+
+	for (i = 0; i < size; i++)
+		if (((const uint8_t *)buf)[i] != patt)
+			return 0;
+	return 1;
+}
+
+/* Normal UBI messages */
+void ubi_msg(const struct ubi_device *ubi, const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	pr_notice(UBI_NAME_STR "%d: %pV\n", ubi->ubi_num, &vaf);
+
+	va_end(args);
+}
+
+/* UBI warning messages */
+void ubi_warn(const struct ubi_device *ubi, const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	pr_warn(UBI_NAME_STR "%d warning: %ps: %pV\n",
+		ubi->ubi_num, __builtin_return_address(0), &vaf);
+
+	va_end(args);
+}
+
+/* UBI error messages */
+void ubi_err(const struct ubi_device *ubi, const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	pr_err(UBI_NAME_STR "%d error: %ps: %pV\n",
+	       ubi->ubi_num, __builtin_return_address(0), &vaf);
+	va_end(args);
+}
diff --git a/drivers/mtd/ubi/ubi-media.h b/drivers/mtd/ubi/ubi-media.h
new file mode 100644
index 0000000000..2c9cd3b643
--- /dev/null
+++ b/drivers/mtd/ubi/ubi-media.h
@@ -0,0 +1,503 @@
+/* SPDX-License-Identifier: (GPL-2.0+ OR BSD-3-Clause) */
+/*
+ * Copyright (C) International Business Machines Corp., 2006
+ * Authors: Artem Bityutskiy (Битюцкий Артём)
+ *          Thomas Gleixner
+ *          Frank Haverkamp
+ *          Oliver Lohmann
+ *          Andreas Arnez
+ *
+ * This file defines the layout of UBI headers and all the other UBI on-flash
+ * data structures.
+ */
+
+#ifndef __UBI_MEDIA_H__
+#define __UBI_MEDIA_H__
+
+#include <asm/byteorder.h>
+
+/* The version of UBI images supported by this implementation */
+#define UBI_VERSION 1
+
+/* The highest erase counter value supported by this implementation */
+#define UBI_MAX_ERASECOUNTER 0x7FFFFFFF
+
+/* The initial CRC32 value used when calculating CRC checksums */
+#define UBI_CRC32_INIT 0xFFFFFFFFU
+
+/* Erase counter header magic number (ASCII "UBI#") */
+#define UBI_EC_HDR_MAGIC  0x55424923
+/* Volume identifier header magic number (ASCII "UBI!") */
+#define UBI_VID_HDR_MAGIC 0x55424921
+
+/*
+ * Volume type constants used in the volume identifier header.
+ *
+ * @UBI_VID_DYNAMIC: dynamic volume
+ * @UBI_VID_STATIC: static volume
+ */
+enum {
+	UBI_VID_DYNAMIC = 1,
+	UBI_VID_STATIC  = 2
+};
+
+/*
+ * Volume flags used in the volume table record.
+ *
+ * @UBI_VTBL_AUTORESIZE_FLG: auto-resize this volume
+ * @UBI_VTBL_SKIP_CRC_CHECK_FLG: skip the CRC check done on a static volume at
+ *				 open time. Should only be set on volumes that
+ *				 are used by upper layers doing this kind of
+ *				 check. Main use-case for this flag is
+ *				 boot-time reduction
+ *
+ * %UBI_VTBL_AUTORESIZE_FLG flag can be set only for one volume in the volume
+ * table. UBI automatically re-sizes the volume which has this flag and makes
+ * the volume to be of largest possible size. This means that if after the
+ * initialization UBI finds out that there are available physical eraseblocks
+ * present on the device, it automatically appends all of them to the volume
+ * (the physical eraseblocks reserved for bad eraseblocks handling and other
+ * reserved physical eraseblocks are not taken). So, if there is a volume with
+ * the %UBI_VTBL_AUTORESIZE_FLG flag set, the amount of available logical
+ * eraseblocks will be zero after UBI is loaded, because all of them will be
+ * reserved for this volume. Note, the %UBI_VTBL_AUTORESIZE_FLG bit is cleared
+ * after the volume had been initialized.
+ *
+ * The auto-resize feature is useful for device production purposes. For
+ * example, different NAND flash chips may have different amount of initial bad
+ * eraseblocks, depending of particular chip instance. Manufacturers of NAND
+ * chips usually guarantee that the amount of initial bad eraseblocks does not
+ * exceed certain percent, e.g. 2%. When one creates an UBI image which will be
+ * flashed to the end devices in production, he does not know the exact amount
+ * of good physical eraseblocks the NAND chip on the device will have, but this
+ * number is required to calculate the volume sized and put them to the volume
+ * table of the UBI image. In this case, one of the volumes (e.g., the one
+ * which will store the root file system) is marked as "auto-resizable", and
+ * UBI will adjust its size on the first boot if needed.
+ *
+ * Note, first UBI reserves some amount of physical eraseblocks for bad
+ * eraseblock handling, and then re-sizes the volume, not vice-versa. This
+ * means that the pool of reserved physical eraseblocks will always be present.
+ */
+enum {
+	UBI_VTBL_AUTORESIZE_FLG = 0x01,
+	UBI_VTBL_SKIP_CRC_CHECK_FLG = 0x02,
+};
+
+/*
+ * Compatibility constants used by internal volumes.
+ *
+ * @UBI_COMPAT_DELETE: delete this internal volume before anything is written
+ *                     to the flash
+ * @UBI_COMPAT_RO: attach this device in read-only mode
+ * @UBI_COMPAT_PRESERVE: preserve this internal volume - do not touch its
+ *                       physical eraseblocks, don't allow the wear-leveling
+ *                       sub-system to move them
+ * @UBI_COMPAT_REJECT: reject this UBI image
+ */
+enum {
+	UBI_COMPAT_DELETE   = 1,
+	UBI_COMPAT_RO       = 2,
+	UBI_COMPAT_PRESERVE = 4,
+	UBI_COMPAT_REJECT   = 5
+};
+
+/* Sizes of UBI headers */
+#define UBI_EC_HDR_SIZE  sizeof(struct ubi_ec_hdr)
+#define UBI_VID_HDR_SIZE sizeof(struct ubi_vid_hdr)
+
+/* Sizes of UBI headers without the ending CRC */
+#define UBI_EC_HDR_SIZE_CRC  (UBI_EC_HDR_SIZE  - sizeof(__be32))
+#define UBI_VID_HDR_SIZE_CRC (UBI_VID_HDR_SIZE - sizeof(__be32))
+
+/**
+ * struct ubi_ec_hdr - UBI erase counter header.
+ * @magic: erase counter header magic number (%UBI_EC_HDR_MAGIC)
+ * @version: version of UBI implementation which is supposed to accept this
+ *           UBI image
+ * @padding1: reserved for future, zeroes
+ * @ec: the erase counter
+ * @vid_hdr_offset: where the VID header starts
+ * @data_offset: where the user data start
+ * @image_seq: image sequence number
+ * @padding2: reserved for future, zeroes
+ * @hdr_crc: erase counter header CRC checksum
+ *
+ * The erase counter header takes 64 bytes and has a plenty of unused space for
+ * future usage. The unused fields are zeroed. The @version field is used to
+ * indicate the version of UBI implementation which is supposed to be able to
+ * work with this UBI image. If @version is greater than the current UBI
+ * version, the image is rejected. This may be useful in future if something
+ * is changed radically. This field is duplicated in the volume identifier
+ * header.
+ *
+ * The @vid_hdr_offset and @data_offset fields contain the offset of the
+ * volume identifier header and user data, relative to the beginning of the
+ * physical eraseblock. These values have to be the same for all physical
+ * eraseblocks.
+ *
+ * The @image_seq field is used to validate a UBI image that has been prepared
+ * for a UBI device. The @image_seq value can be any value, but it must be the
+ * same on all eraseblocks. UBI will ensure that all new erase counter headers
+ * also contain this value, and will check the value when attaching the flash.
+ * One way to make use of @image_seq is to increase its value by one every time
+ * an image is flashed over an existing image, then, if the flashing does not
+ * complete, UBI will detect the error when attaching the media.
+ */
+struct ubi_ec_hdr {
+	__be32  magic;
+	__u8    version;
+	__u8    padding1[3];
+	__be64  ec; /* Warning: the current limit is 31-bit anyway! */
+	__be32  vid_hdr_offset;
+	__be32  data_offset;
+	__be32  image_seq;
+	__u8    padding2[32];
+	__be32  hdr_crc;
+} __packed;
+
+/**
+ * struct ubi_vid_hdr - on-flash UBI volume identifier header.
+ * @magic: volume identifier header magic number (%UBI_VID_HDR_MAGIC)
+ * @version: UBI implementation version which is supposed to accept this UBI
+ *           image (%UBI_VERSION)
+ * @vol_type: volume type (%UBI_VID_DYNAMIC or %UBI_VID_STATIC)
+ * @copy_flag: if this logical eraseblock was copied from another physical
+ *             eraseblock (for wear-leveling reasons)
+ * @compat: compatibility of this volume (%0, %UBI_COMPAT_DELETE,
+ *          %UBI_COMPAT_IGNORE, %UBI_COMPAT_PRESERVE, or %UBI_COMPAT_REJECT)
+ * @vol_id: ID of this volume
+ * @lnum: logical eraseblock number
+ * @padding1: reserved for future, zeroes
+ * @data_size: how many bytes of data this logical eraseblock contains
+ * @used_ebs: total number of used logical eraseblocks in this volume
+ * @data_pad: how many bytes at the end of this physical eraseblock are not
+ *            used
+ * @data_crc: CRC checksum of the data stored in this logical eraseblock
+ * @padding2: reserved for future, zeroes
+ * @sqnum: sequence number
+ * @padding3: reserved for future, zeroes
+ * @hdr_crc: volume identifier header CRC checksum
+ *
+ * The @sqnum is the value of the global sequence counter at the time when this
+ * VID header was created. The global sequence counter is incremented each time
+ * UBI writes a new VID header to the flash, i.e. when it maps a logical
+ * eraseblock to a new physical eraseblock. The global sequence counter is an
+ * unsigned 64-bit integer and we assume it never overflows. The @sqnum
+ * (sequence number) is used to distinguish between older and newer versions of
+ * logical eraseblocks.
+ *
+ * There are 2 situations when there may be more than one physical eraseblock
+ * corresponding to the same logical eraseblock, i.e., having the same @vol_id
+ * and @lnum values in the volume identifier header. Suppose we have a logical
+ * eraseblock L and it is mapped to the physical eraseblock P.
+ *
+ * 1. Because UBI may erase physical eraseblocks asynchronously, the following
+ * situation is possible: L is asynchronously erased, so P is scheduled for
+ * erasure, then L is written to,i.e. mapped to another physical eraseblock P1,
+ * so P1 is written to, then an unclean reboot happens. Result - there are 2
+ * physical eraseblocks P and P1 corresponding to the same logical eraseblock
+ * L. But P1 has greater sequence number, so UBI picks P1 when it attaches the
+ * flash.
+ *
+ * 2. From time to time UBI moves logical eraseblocks to other physical
+ * eraseblocks for wear-leveling reasons. If, for example, UBI moves L from P
+ * to P1, and an unclean reboot happens before P is physically erased, there
+ * are two physical eraseblocks P and P1 corresponding to L and UBI has to
+ * select one of them when the flash is attached. The @sqnum field says which
+ * PEB is the original (obviously P will have lower @sqnum) and the copy. But
+ * it is not enough to select the physical eraseblock with the higher sequence
+ * number, because the unclean reboot could have happen in the middle of the
+ * copying process, so the data in P is corrupted. It is also not enough to
+ * just select the physical eraseblock with lower sequence number, because the
+ * data there may be old (consider a case if more data was added to P1 after
+ * the copying). Moreover, the unclean reboot may happen when the erasure of P
+ * was just started, so it result in unstable P, which is "mostly" OK, but
+ * still has unstable bits.
+ *
+ * UBI uses the @copy_flag field to indicate that this logical eraseblock is a
+ * copy. UBI also calculates data CRC when the data is moved and stores it at
+ * the @data_crc field of the copy (P1). So when UBI needs to pick one physical
+ * eraseblock of two (P or P1), the @copy_flag of the newer one (P1) is
+ * examined. If it is cleared, the situation is simple and the newer one is
+ * picked. If it is set, the data CRC of the copy (P1) is examined. If the CRC
+ * checksum is correct, this physical eraseblock is selected (P1). Otherwise
+ * the older one (P) is selected.
+ *
+ * There are 2 sorts of volumes in UBI: user volumes and internal volumes.
+ * Internal volumes are not seen from outside and are used for various internal
+ * UBI purposes. In this implementation there is only one internal volume - the
+ * layout volume. Internal volumes are the main mechanism of UBI extensions.
+ * For example, in future one may introduce a journal internal volume. Internal
+ * volumes have their own reserved range of IDs.
+ *
+ * The @compat field is only used for internal volumes and contains the "degree
+ * of their compatibility". It is always zero for user volumes. This field
+ * provides a mechanism to introduce UBI extensions and to be still compatible
+ * with older UBI binaries. For example, if someone introduced a journal in
+ * future, he would probably use %UBI_COMPAT_DELETE compatibility for the
+ * journal volume.  And in this case, older UBI binaries, which know nothing
+ * about the journal volume, would just delete this volume and work perfectly
+ * fine. This is similar to what Ext2fs does when it is fed by an Ext3fs image
+ * - it just ignores the Ext3fs journal.
+ *
+ * The @data_crc field contains the CRC checksum of the contents of the logical
+ * eraseblock if this is a static volume. In case of dynamic volumes, it does
+ * not contain the CRC checksum as a rule. The only exception is when the
+ * data of the physical eraseblock was moved by the wear-leveling sub-system,
+ * then the wear-leveling sub-system calculates the data CRC and stores it in
+ * the @data_crc field. And of course, the @copy_flag is %in this case.
+ *
+ * The @data_size field is used only for static volumes because UBI has to know
+ * how many bytes of data are stored in this eraseblock. For dynamic volumes,
+ * this field usually contains zero. The only exception is when the data of the
+ * physical eraseblock was moved to another physical eraseblock for
+ * wear-leveling reasons. In this case, UBI calculates CRC checksum of the
+ * contents and uses both @data_crc and @data_size fields. In this case, the
+ * @data_size field contains data size.
+ *
+ * The @used_ebs field is used only for static volumes and indicates how many
+ * eraseblocks the data of the volume takes. For dynamic volumes this field is
+ * not used and always contains zero.
+ *
+ * The @data_pad is calculated when volumes are created using the alignment
+ * parameter. So, effectively, the @data_pad field reduces the size of logical
+ * eraseblocks of this volume. This is very handy when one uses block-oriented
+ * software (say, cramfs) on top of the UBI volume.
+ */
+struct ubi_vid_hdr {
+	__be32  magic;
+	__u8    version;
+	__u8    vol_type;
+	__u8    copy_flag;
+	__u8    compat;
+	__be32  vol_id;
+	__be32  lnum;
+	__u8    padding1[4];
+	__be32  data_size;
+	__be32  used_ebs;
+	__be32  data_pad;
+	__be32  data_crc;
+	__u8    padding2[4];
+	__be64  sqnum;
+	__u8    padding3[12];
+	__be32  hdr_crc;
+} __packed;
+
+/* Internal UBI volumes count */
+#define UBI_INT_VOL_COUNT 1
+
+/*
+ * Starting ID of internal volumes: 0x7fffefff.
+ * There is reserved room for 4096 internal volumes.
+ */
+#define UBI_INTERNAL_VOL_START (0x7FFFFFFF - 4096)
+
+/* The layout volume contains the volume table */
+
+#define UBI_LAYOUT_VOLUME_ID     UBI_INTERNAL_VOL_START
+#define UBI_LAYOUT_VOLUME_TYPE   UBI_VID_DYNAMIC
+#define UBI_LAYOUT_VOLUME_ALIGN  1
+#define UBI_LAYOUT_VOLUME_EBS    2
+#define UBI_LAYOUT_VOLUME_NAME   "layout volume"
+#define UBI_LAYOUT_VOLUME_COMPAT UBI_COMPAT_REJECT
+
+/* The maximum number of volumes per one UBI device */
+#define UBI_MAX_VOLUMES 128
+
+/* The maximum volume name length */
+#define UBI_VOL_NAME_MAX 127
+
+/* Size of the volume table record */
+#define UBI_VTBL_RECORD_SIZE sizeof(struct ubi_vtbl_record)
+
+/* Size of the volume table record without the ending CRC */
+#define UBI_VTBL_RECORD_SIZE_CRC (UBI_VTBL_RECORD_SIZE - sizeof(__be32))
+
+/**
+ * struct ubi_vtbl_record - a record in the volume table.
+ * @reserved_pebs: how many physical eraseblocks are reserved for this volume
+ * @alignment: volume alignment
+ * @data_pad: how many bytes are unused at the end of the each physical
+ * eraseblock to satisfy the requested alignment
+ * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
+ * @upd_marker: if volume update was started but not finished
+ * @name_len: volume name length
+ * @name: the volume name
+ * @flags: volume flags (%UBI_VTBL_AUTORESIZE_FLG)
+ * @padding: reserved, zeroes
+ * @crc: a CRC32 checksum of the record
+ *
+ * The volume table records are stored in the volume table, which is stored in
+ * the layout volume. The layout volume consists of 2 logical eraseblock, each
+ * of which contains a copy of the volume table (i.e., the volume table is
+ * duplicated). The volume table is an array of &struct ubi_vtbl_record
+ * objects indexed by the volume ID.
+ *
+ * If the size of the logical eraseblock is large enough to fit
+ * %UBI_MAX_VOLUMES records, the volume table contains %UBI_MAX_VOLUMES
+ * records. Otherwise, it contains as many records as it can fit (i.e., size of
+ * logical eraseblock divided by sizeof(struct ubi_vtbl_record)).
+ *
+ * The @upd_marker flag is used to implement volume update. It is set to %1
+ * before update and set to %0 after the update. So if the update operation was
+ * interrupted, UBI knows that the volume is corrupted.
+ *
+ * The @alignment field is specified when the volume is created and cannot be
+ * later changed. It may be useful, for example, when a block-oriented file
+ * system works on top of UBI. The @data_pad field is calculated using the
+ * logical eraseblock size and @alignment. The alignment must be multiple to the
+ * minimal flash I/O unit. If @alignment is 1, all the available space of
+ * the physical eraseblocks is used.
+ *
+ * Empty records contain all zeroes and the CRC checksum of those zeroes.
+ */
+struct ubi_vtbl_record {
+	__be32  reserved_pebs;
+	__be32  alignment;
+	__be32  data_pad;
+	__u8    vol_type;
+	__u8    upd_marker;
+	__be16  name_len;
+	__u8    name[UBI_VOL_NAME_MAX+1];
+	__u8    flags;
+	__u8    padding[23];
+	__be32  crc;
+} __packed;
+
+/* UBI fastmap on-flash data structures */
+
+#define UBI_FM_SB_VOLUME_ID	(UBI_LAYOUT_VOLUME_ID + 1)
+#define UBI_FM_DATA_VOLUME_ID	(UBI_LAYOUT_VOLUME_ID + 2)
+
+/* fastmap on-flash data structure format version */
+#define UBI_FM_FMT_VERSION	1
+
+#define UBI_FM_SB_MAGIC		0x7B11D69F
+#define UBI_FM_HDR_MAGIC	0xD4B82EF7
+#define UBI_FM_VHDR_MAGIC	0xFA370ED1
+#define UBI_FM_POOL_MAGIC	0x67AF4D08
+#define UBI_FM_EBA_MAGIC	0xf0c040a8
+
+/* A fastmap super block can be located between PEB 0 and
+ * UBI_FM_MAX_START */
+#define UBI_FM_MAX_START	64
+
+/* A fastmap can use up to UBI_FM_MAX_BLOCKS PEBs */
+#define UBI_FM_MAX_BLOCKS	32
+
+/* 5% of the total number of PEBs have to be scanned while attaching
+ * from a fastmap.
+ * But the size of this pool is limited to be between UBI_FM_MIN_POOL_SIZE and
+ * UBI_FM_MAX_POOL_SIZE */
+#define UBI_FM_MIN_POOL_SIZE	8
+#define UBI_FM_MAX_POOL_SIZE	256
+
+/**
+ * struct ubi_fm_sb - UBI fastmap super block
+ * @magic: fastmap super block magic number (%UBI_FM_SB_MAGIC)
+ * @version: format version of this fastmap
+ * @data_crc: CRC over the fastmap data
+ * @used_blocks: number of PEBs used by this fastmap
+ * @block_loc: an array containing the location of all PEBs of the fastmap
+ * @block_ec: the erase counter of each used PEB
+ * @sqnum: highest sequence number value at the time while taking the fastmap
+ *
+ */
+struct ubi_fm_sb {
+	__be32 magic;
+	__u8 version;
+	__u8 padding1[3];
+	__be32 data_crc;
+	__be32 used_blocks;
+	__be32 block_loc[UBI_FM_MAX_BLOCKS];
+	__be32 block_ec[UBI_FM_MAX_BLOCKS];
+	__be64 sqnum;
+	__u8 padding2[32];
+} __packed;
+
+/**
+ * struct ubi_fm_hdr - header of the fastmap data set
+ * @magic: fastmap header magic number (%UBI_FM_HDR_MAGIC)
+ * @free_peb_count: number of free PEBs known by this fastmap
+ * @used_peb_count: number of used PEBs known by this fastmap
+ * @scrub_peb_count: number of to be scrubbed PEBs known by this fastmap
+ * @bad_peb_count: number of bad PEBs known by this fastmap
+ * @erase_peb_count: number of bad PEBs which have to be erased
+ * @vol_count: number of UBI volumes known by this fastmap
+ */
+struct ubi_fm_hdr {
+	__be32 magic;
+	__be32 free_peb_count;
+	__be32 used_peb_count;
+	__be32 scrub_peb_count;
+	__be32 bad_peb_count;
+	__be32 erase_peb_count;
+	__be32 vol_count;
+	__u8 padding[4];
+} __packed;
+
+/* struct ubi_fm_hdr is followed by two struct ubi_fm_scan_pool */
+
+/**
+ * struct ubi_fm_scan_pool - Fastmap pool PEBs to be scanned while attaching
+ * @magic: pool magic numer (%UBI_FM_POOL_MAGIC)
+ * @size: current pool size
+ * @max_size: maximal pool size
+ * @pebs: an array containing the location of all PEBs in this pool
+ */
+struct ubi_fm_scan_pool {
+	__be32 magic;
+	__be16 size;
+	__be16 max_size;
+	__be32 pebs[UBI_FM_MAX_POOL_SIZE];
+	__be32 padding[4];
+} __packed;
+
+/* ubi_fm_scan_pool is followed by nfree+nused struct ubi_fm_ec records */
+
+/**
+ * struct ubi_fm_ec - stores the erase counter of a PEB
+ * @pnum: PEB number
+ * @ec: ec of this PEB
+ */
+struct ubi_fm_ec {
+	__be32 pnum;
+	__be32 ec;
+} __packed;
+
+/**
+ * struct ubi_fm_volhdr - Fastmap volume header
+ * it identifies the start of an eba table
+ * @magic: Fastmap volume header magic number (%UBI_FM_VHDR_MAGIC)
+ * @vol_id: volume id of the fastmapped volume
+ * @vol_type: type of the fastmapped volume
+ * @data_pad: data_pad value of the fastmapped volume
+ * @used_ebs: number of used LEBs within this volume
+ * @last_eb_bytes: number of bytes used in the last LEB
+ */
+struct ubi_fm_volhdr {
+	__be32 magic;
+	__be32 vol_id;
+	__u8 vol_type;
+	__u8 padding1[3];
+	__be32 data_pad;
+	__be32 used_ebs;
+	__be32 last_eb_bytes;
+	__u8 padding2[8];
+} __packed;
+
+/* struct ubi_fm_volhdr is followed by one struct ubi_fm_eba records */
+
+/**
+ * struct ubi_fm_eba - denotes an association between a PEB and LEB
+ * @magic: EBA table magic number
+ * @reserved_pebs: number of table entries
+ * @pnum: PEB number of LEB (LEB is the index)
+ */
+struct ubi_fm_eba {
+	__be32 magic;
+	__be32 reserved_pebs;
+	__be32 pnum[];
+} __packed;
+#endif /* !__UBI_MEDIA_H__ */
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
new file mode 100644
index 0000000000..c8f1bd4fa1
--- /dev/null
+++ b/drivers/mtd/ubi/ubi.h
@@ -0,0 +1,1228 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ * Copyright (c) Nokia Corporation, 2006, 2007
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+#ifndef __UBI_UBI_H__
+#define __UBI_UBI_H__
+
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/rbtree.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/mutex.h>
+#include <linux/rwsem.h>
+#include <linux/spinlock.h>
+#include <linux/fs.h>
+#include <linux/cdev.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/vmalloc.h>
+#include <linux/notifier.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/ubi.h>
+#include <linux/pgtable.h>
+
+#include "ubi-media.h"
+
+/* Maximum number of supported UBI devices */
+#define UBI_MAX_DEVICES 32
+
+/* UBI name used for character devices, sysfs, etc */
+#define UBI_NAME_STR "ubi"
+
+struct ubi_device;
+
+/* Normal UBI messages */
+__printf(2, 3)
+void ubi_msg(const struct ubi_device *ubi, const char *fmt, ...);
+
+/* UBI warning messages */
+__printf(2, 3)
+void ubi_warn(const struct ubi_device *ubi, const char *fmt, ...);
+
+/* UBI error messages */
+__printf(2, 3)
+void ubi_err(const struct ubi_device *ubi, const char *fmt, ...);
+
+/* Background thread name pattern */
+#define UBI_BGT_NAME_PATTERN "ubi_bgt%dd"
+
+/*
+ * This marker in the EBA table means that the LEB is um-mapped.
+ * NOTE! It has to have the same value as %UBI_ALL.
+ */
+#define UBI_LEB_UNMAPPED -1
+
+/*
+ * In case of errors, UBI tries to repeat the operation several times before
+ * returning error. The below constant defines how many times UBI re-tries.
+ */
+#define UBI_IO_RETRIES 3
+
+/*
+ * Length of the protection queue. The length is effectively equivalent to the
+ * number of (global) erase cycles PEBs are protected from the wear-leveling
+ * worker.
+ */
+#define UBI_PROT_QUEUE_LEN 10
+
+/* The volume ID/LEB number/erase counter is unknown */
+#define UBI_UNKNOWN -1
+
+/*
+ * The UBI debugfs directory name pattern and maximum name length (3 for "ubi"
+ * + 2 for the number plus 1 for the trailing zero byte.
+ */
+#define UBI_DFS_DIR_NAME "ubi%d"
+#define UBI_DFS_DIR_LEN  (3 + 2 + 1)
+
+/*
+ * Error codes returned by the I/O sub-system.
+ *
+ * UBI_IO_FF: the read region of flash contains only 0xFFs
+ * UBI_IO_FF_BITFLIPS: the same as %UBI_IO_FF, but also there was a data
+ *                     integrity error reported by the MTD driver
+ *                     (uncorrectable ECC error in case of NAND)
+ * UBI_IO_BAD_HDR: the EC or VID header is corrupted (bad magic or CRC)
+ * UBI_IO_BAD_HDR_EBADMSG: the same as %UBI_IO_BAD_HDR, but also there was a
+ *                         data integrity error reported by the MTD driver
+ *                         (uncorrectable ECC error in case of NAND)
+ * UBI_IO_BITFLIPS: bit-flips were detected and corrected
+ *
+ * Note, it is probably better to have bit-flip and ebadmsg as flags which can
+ * be or'ed with other error code. But this is a big change because there are
+ * may callers, so it does not worth the risk of introducing a bug
+ */
+enum {
+	UBI_IO_FF = 1,
+	UBI_IO_FF_BITFLIPS,
+	UBI_IO_BAD_HDR,
+	UBI_IO_BAD_HDR_EBADMSG,
+	UBI_IO_BITFLIPS,
+};
+
+/*
+ * Return codes of the 'ubi_eba_copy_leb()' function.
+ *
+ * MOVE_CANCEL_RACE: canceled because the volume is being deleted, the source
+ *                   PEB was put meanwhile, or there is I/O on the source PEB
+ * MOVE_SOURCE_RD_ERR: canceled because there was a read error from the source
+ *                     PEB
+ * MOVE_TARGET_RD_ERR: canceled because there was a read error from the target
+ *                     PEB
+ * MOVE_TARGET_WR_ERR: canceled because there was a write error to the target
+ *                     PEB
+ * MOVE_TARGET_BITFLIPS: canceled because a bit-flip was detected in the
+ *                       target PEB
+ * MOVE_RETRY: retry scrubbing the PEB
+ */
+enum {
+	MOVE_CANCEL_RACE = 1,
+	MOVE_SOURCE_RD_ERR,
+	MOVE_TARGET_RD_ERR,
+	MOVE_TARGET_WR_ERR,
+	MOVE_TARGET_BITFLIPS,
+	MOVE_RETRY,
+};
+
+/*
+ * Return codes of the fastmap sub-system
+ *
+ * UBI_NO_FASTMAP: No fastmap super block was found
+ * UBI_BAD_FASTMAP: A fastmap was found but it's unusable
+ */
+enum {
+	UBI_NO_FASTMAP = 1,
+	UBI_BAD_FASTMAP,
+};
+
+/*
+ * Flags for emulate_power_cut in ubi_debug_info
+ *
+ * POWER_CUT_EC_WRITE: Emulate a power cut when writing an EC header
+ * POWER_CUT_VID_WRITE: Emulate a power cut when writing a VID header
+ */
+enum {
+	POWER_CUT_EC_WRITE = 0x01,
+	POWER_CUT_VID_WRITE = 0x02,
+};
+
+/**
+ * struct ubi_vid_io_buf - VID buffer used to read/write VID info to/from the
+ *			   flash.
+ * @hdr: a pointer to the VID header stored in buffer
+ * @buffer: underlying buffer
+ */
+struct ubi_vid_io_buf {
+	struct ubi_vid_hdr *hdr;
+	void *buffer;
+};
+
+/**
+ * struct ubi_wl_entry - wear-leveling entry.
+ * @u.rb: link in the corresponding (free/used) RB-tree
+ * @u.list: link in the protection queue
+ * @ec: erase counter
+ * @pnum: physical eraseblock number
+ *
+ * This data structure is used in the WL sub-system. Each physical eraseblock
+ * has a corresponding &struct wl_entry object which may be kept in different
+ * RB-trees. See WL sub-system for details.
+ */
+struct ubi_wl_entry {
+	union {
+		struct rb_node rb;
+		struct list_head list;
+	} u;
+	int ec;
+	int pnum;
+};
+
+/**
+ * struct ubi_ltree_entry - an entry in the lock tree.
+ * @rb: links RB-tree nodes
+ * @vol_id: volume ID of the locked logical eraseblock
+ * @lnum: locked logical eraseblock number
+ * @users: how many tasks are using this logical eraseblock or wait for it
+ * @mutex: read/write mutex to implement read/write access serialization to
+ *         the (@vol_id, @lnum) logical eraseblock
+ *
+ * This data structure is used in the EBA sub-system to implement per-LEB
+ * locking. When a logical eraseblock is being locked - corresponding
+ * &struct ubi_ltree_entry object is inserted to the lock tree (@ubi->ltree).
+ * See EBA sub-system for details.
+ */
+struct ubi_ltree_entry {
+	struct rb_node rb;
+	int vol_id;
+	int lnum;
+	int users;
+	struct rw_semaphore mutex;
+};
+
+/**
+ * struct ubi_rename_entry - volume re-name description data structure.
+ * @new_name_len: new volume name length
+ * @new_name: new volume name
+ * @remove: if not zero, this volume should be removed, not re-named
+ * @desc: descriptor of the volume
+ * @list: links re-name entries into a list
+ *
+ * This data structure is utilized in the multiple volume re-name code. Namely,
+ * UBI first creates a list of &struct ubi_rename_entry objects from the
+ * &struct ubi_rnvol_req request object, and then utilizes this list to do all
+ * the job.
+ */
+struct ubi_rename_entry {
+	int new_name_len;
+	char new_name[UBI_VOL_NAME_MAX + 1];
+	int remove;
+	struct ubi_volume_desc *desc;
+	struct list_head list;
+};
+
+struct ubi_volume_desc;
+
+/**
+ * struct ubi_fastmap_layout - in-memory fastmap data structure.
+ * @e: PEBs used by the current fastmap
+ * @to_be_tortured: if non-zero tortured this PEB
+ * @used_blocks: number of used PEBs
+ * @max_pool_size: maximal size of the user pool
+ * @max_wl_pool_size: maximal size of the pool used by the WL sub-system
+ */
+struct ubi_fastmap_layout {
+	struct ubi_wl_entry *e[UBI_FM_MAX_BLOCKS];
+	int to_be_tortured[UBI_FM_MAX_BLOCKS];
+	int used_blocks;
+	int max_pool_size;
+	int max_wl_pool_size;
+};
+
+/**
+ * struct ubi_fm_pool - in-memory fastmap pool
+ * @pebs: PEBs in this pool
+ * @used: number of used PEBs
+ * @size: total number of PEBs in this pool
+ * @max_size: maximal size of the pool
+ *
+ * A pool gets filled with up to max_size.
+ * If all PEBs within the pool are used a new fastmap will be written
+ * to the flash and the pool gets refilled with empty PEBs.
+ *
+ */
+struct ubi_fm_pool {
+	int pebs[UBI_FM_MAX_POOL_SIZE];
+	int used;
+	int size;
+	int max_size;
+};
+
+/**
+ * struct ubi_eba_leb_desc - EBA logical eraseblock descriptor
+ * @lnum: the logical eraseblock number
+ * @pnum: the physical eraseblock where the LEB can be found
+ *
+ * This structure is here to hide EBA's internal from other part of the
+ * UBI implementation.
+ *
+ * One can query the position of a LEB by calling ubi_eba_get_ldesc().
+ */
+struct ubi_eba_leb_desc {
+	int lnum;
+	int pnum;
+};
+
+/**
+ * struct ubi_volume - UBI volume description data structure.
+ * @dev: device object to make use of the Linux device model
+ * @cdev: character device object to create character device
+ * @ubi: reference to the UBI device description object
+ * @vol_id: volume ID
+ * @ref_count: volume reference count
+ * @readers: number of users holding this volume in read-only mode
+ * @writers: number of users holding this volume in read-write mode
+ * @exclusive: whether somebody holds this volume in exclusive mode
+ * @metaonly: whether somebody is altering only meta data of this volume
+ *
+ * @reserved_pebs: how many physical eraseblocks are reserved for this volume
+ * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
+ * @usable_leb_size: logical eraseblock size without padding
+ * @used_ebs: how many logical eraseblocks in this volume contain data
+ * @last_eb_bytes: how many bytes are stored in the last logical eraseblock
+ * @used_bytes: how many bytes of data this volume contains
+ * @alignment: volume alignment
+ * @data_pad: how many bytes are not used at the end of physical eraseblocks to
+ *            satisfy the requested alignment
+ * @name_len: volume name length
+ * @name: volume name
+ *
+ * @upd_ebs: how many eraseblocks are expected to be updated
+ * @ch_lnum: LEB number which is being changing by the atomic LEB change
+ *           operation
+ * @upd_bytes: how many bytes are expected to be received for volume update or
+ *             atomic LEB change
+ * @upd_received: how many bytes were already received for volume update or
+ *                atomic LEB change
+ * @upd_buf: update buffer which is used to collect update data or data for
+ *           atomic LEB change
+ *
+ * @eba_tbl: EBA table of this volume (LEB->PEB mapping)
+ * @skip_check: %1 if CRC check of this static volume should be skipped.
+ *		Directly reflects the presence of the
+ *		%UBI_VTBL_SKIP_CRC_CHECK_FLG flag in the vtbl entry
+ * @checked: %1 if this static volume was checked
+ * @corrupted: %1 if the volume is corrupted (static volumes only)
+ * @upd_marker: %1 if the update marker is set for this volume
+ * @updating: %1 if the volume is being updated
+ * @changing_leb: %1 if the atomic LEB change ioctl command is in progress
+ * @direct_writes: %1 if direct writes are enabled for this volume
+ *
+ * @checkmap: bitmap to remember which PEB->LEB mappings got checked,
+ *            protected by UBI LEB lock tree.
+ *
+ * The @corrupted field indicates that the volume's contents is corrupted.
+ * Since UBI protects only static volumes, this field is not relevant to
+ * dynamic volumes - it is user's responsibility to assure their data
+ * integrity.
+ *
+ * The @upd_marker flag indicates that this volume is either being updated at
+ * the moment or is damaged because of an unclean reboot.
+ */
+struct ubi_volume {
+	struct device dev;
+	struct cdev cdev;
+	struct ubi_device *ubi;
+	int vol_id;
+	int ref_count;
+	int readers;
+	int writers;
+	int exclusive;
+	int metaonly;
+
+	int reserved_pebs;
+	int vol_type;
+	int usable_leb_size;
+	int used_ebs;
+	int last_eb_bytes;
+	long long used_bytes;
+	int alignment;
+	int data_pad;
+	int name_len;
+	char name[UBI_VOL_NAME_MAX + 1];
+
+	int upd_ebs;
+	int ch_lnum;
+	long long upd_bytes;
+	long long upd_received;
+	void *upd_buf;
+
+	struct ubi_eba_table *eba_tbl;
+	unsigned int skip_check:1;
+	unsigned int checked:1;
+	unsigned int corrupted:1;
+	unsigned int upd_marker:1;
+	unsigned int updating:1;
+	unsigned int changing_leb:1;
+	unsigned int direct_writes:1;
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+	unsigned long *checkmap;
+#endif
+};
+
+/**
+ * struct ubi_volume_desc - UBI volume descriptor returned when it is opened.
+ * @vol: reference to the corresponding volume description object
+ * @mode: open mode (%UBI_READONLY, %UBI_READWRITE, %UBI_EXCLUSIVE
+ * or %UBI_METAONLY)
+ */
+struct ubi_volume_desc {
+	struct ubi_volume *vol;
+	int mode;
+};
+
+/**
+ * struct ubi_debug_info - debugging information for an UBI device.
+ *
+ * @chk_gen: if UBI general extra checks are enabled
+ * @chk_io: if UBI I/O extra checks are enabled
+ * @chk_fastmap: if UBI fastmap extra checks are enabled
+ * @disable_bgt: disable the background task for testing purposes
+ * @emulate_bitflips: emulate bit-flips for testing purposes
+ * @emulate_io_failures: emulate write/erase failures for testing purposes
+ * @emulate_power_cut: emulate power cut for testing purposes
+ * @power_cut_counter: count down for writes left until emulated power cut
+ * @power_cut_min: minimum number of writes before emulating a power cut
+ * @power_cut_max: maximum number of writes until emulating a power cut
+ * @dfs_dir_name: name of debugfs directory containing files of this UBI device
+ * @dfs_dir: direntry object of the UBI device debugfs directory
+ * @dfs_chk_gen: debugfs knob to enable UBI general extra checks
+ * @dfs_chk_io: debugfs knob to enable UBI I/O extra checks
+ * @dfs_chk_fastmap: debugfs knob to enable UBI fastmap extra checks
+ * @dfs_disable_bgt: debugfs knob to disable the background task
+ * @dfs_emulate_bitflips: debugfs knob to emulate bit-flips
+ * @dfs_emulate_io_failures: debugfs knob to emulate write/erase failures
+ * @dfs_emulate_power_cut: debugfs knob to emulate power cuts
+ * @dfs_power_cut_min: debugfs knob for minimum writes before power cut
+ * @dfs_power_cut_max: debugfs knob for maximum writes until power cut
+ */
+struct ubi_debug_info {
+	unsigned int chk_gen:1;
+	unsigned int chk_io:1;
+	unsigned int chk_fastmap:1;
+	unsigned int disable_bgt:1;
+	unsigned int emulate_bitflips:1;
+	unsigned int emulate_io_failures:1;
+	unsigned int emulate_power_cut:2;
+	unsigned int power_cut_counter;
+	unsigned int power_cut_min;
+	unsigned int power_cut_max;
+	char dfs_dir_name[UBI_DFS_DIR_LEN + 1];
+	struct dentry *dfs_dir;
+	struct dentry *dfs_chk_gen;
+	struct dentry *dfs_chk_io;
+	struct dentry *dfs_chk_fastmap;
+	struct dentry *dfs_disable_bgt;
+	struct dentry *dfs_emulate_bitflips;
+	struct dentry *dfs_emulate_io_failures;
+	struct dentry *dfs_emulate_power_cut;
+	struct dentry *dfs_power_cut_min;
+	struct dentry *dfs_power_cut_max;
+};
+
+/**
+ * struct ubi_device - UBI device description structure
+ * @dev: UBI device object to use the Linux device model
+ * @cdev: character device object to create character device
+ * @ubi_num: UBI device number
+ * @ubi_name: UBI device name
+ * @vol_count: number of volumes in this UBI device
+ * @volumes: volumes of this UBI device
+ * @volumes_lock: protects @volumes, @rsvd_pebs, @avail_pebs, beb_rsvd_pebs,
+ *                @beb_rsvd_level, @bad_peb_count, @good_peb_count, @vol_count,
+ *                @vol->readers, @vol->writers, @vol->exclusive,
+ *                @vol->metaonly, @vol->ref_count, @vol->mapping and
+ *                @vol->eba_tbl.
+ * @ref_count: count of references on the UBI device
+ * @image_seq: image sequence number recorded on EC headers
+ *
+ * @rsvd_pebs: count of reserved physical eraseblocks
+ * @avail_pebs: count of available physical eraseblocks
+ * @beb_rsvd_pebs: how many physical eraseblocks are reserved for bad PEB
+ *                 handling
+ * @beb_rsvd_level: normal level of PEBs reserved for bad PEB handling
+ *
+ * @autoresize_vol_id: ID of the volume which has to be auto-resized at the end
+ *                     of UBI initialization
+ * @vtbl_slots: how many slots are available in the volume table
+ * @vtbl_size: size of the volume table in bytes
+ * @vtbl: in-RAM volume table copy
+ * @device_mutex: protects on-flash volume table and serializes volume
+ *                creation, deletion, update, re-size, re-name and set
+ *                property
+ *
+ * @max_ec: current highest erase counter value
+ * @mean_ec: current mean erase counter value
+ *
+ * @global_sqnum: global sequence number
+ * @ltree_lock: protects the lock tree and @global_sqnum
+ * @ltree: the lock tree
+ * @alc_mutex: serializes "atomic LEB change" operations
+ *
+ * @fm_disabled: non-zero if fastmap is disabled (default)
+ * @fm: in-memory data structure of the currently used fastmap
+ * @fm_pool: in-memory data structure of the fastmap pool
+ * @fm_wl_pool: in-memory data structure of the fastmap pool used by the WL
+ *		sub-system
+ * @fm_protect: serializes ubi_update_fastmap(), protects @fm_buf and makes sure
+ * that critical sections cannot be interrupted by ubi_update_fastmap()
+ * @fm_buf: vmalloc()'d buffer which holds the raw fastmap
+ * @fm_size: fastmap size in bytes
+ * @fm_eba_sem: allows ubi_update_fastmap() to block EBA table changes
+ * @fm_work: fastmap work queue
+ * @fm_work_scheduled: non-zero if fastmap work was scheduled
+ * @fast_attach: non-zero if UBI was attached by fastmap
+ * @fm_anchor: The next anchor PEB to use for fastmap
+ * @fm_do_produce_anchor: If true produce an anchor PEB in wl
+ *
+ * @used: RB-tree of used physical eraseblocks
+ * @erroneous: RB-tree of erroneous used physical eraseblocks
+ * @free: RB-tree of free physical eraseblocks
+ * @free_count: Contains the number of elements in @free
+ * @scrub: RB-tree of physical eraseblocks which need scrubbing
+ * @pq: protection queue (contain physical eraseblocks which are temporarily
+ *      protected from the wear-leveling worker)
+ * @pq_head: protection queue head
+ * @wl_lock: protects the @used, @free, @pq, @pq_head, @lookuptbl, @move_from,
+ *	     @move_to, @move_to_put @erase_pending, @wl_scheduled, @works,
+ *	     @erroneous, @erroneous_peb_count, @fm_work_scheduled, @fm_pool,
+ *	     and @fm_wl_pool fields
+ * @move_mutex: serializes eraseblock moves
+ * @work_sem: used to wait for all the scheduled works to finish and prevent
+ * new works from being submitted
+ * @wl_scheduled: non-zero if the wear-leveling was scheduled
+ * @lookuptbl: a table to quickly find a &struct ubi_wl_entry object for any
+ *             physical eraseblock
+ * @move_from: physical eraseblock from where the data is being moved
+ * @move_to: physical eraseblock where the data is being moved to
+ * @move_to_put: if the "to" PEB was put
+ * @works: list of pending works
+ * @works_count: count of pending works
+ * @bgt_thread: background thread description object
+ * @thread_enabled: if the background thread is enabled
+ * @bgt_name: background thread name
+ *
+ * @flash_size: underlying MTD device size (in bytes)
+ * @peb_count: count of physical eraseblocks on the MTD device
+ * @peb_size: physical eraseblock size
+ * @bad_peb_limit: top limit of expected bad physical eraseblocks
+ * @bad_peb_count: count of bad physical eraseblocks
+ * @good_peb_count: count of good physical eraseblocks
+ * @corr_peb_count: count of corrupted physical eraseblocks (preserved and not
+ *                  used by UBI)
+ * @erroneous_peb_count: count of erroneous physical eraseblocks in @erroneous
+ * @max_erroneous: maximum allowed amount of erroneous physical eraseblocks
+ * @min_io_size: minimal input/output unit size of the underlying MTD device
+ * @hdrs_min_io_size: minimal I/O unit size used for VID and EC headers
+ * @ro_mode: if the UBI device is in read-only mode
+ * @leb_size: logical eraseblock size
+ * @leb_start: starting offset of logical eraseblocks within physical
+ *             eraseblocks
+ * @ec_hdr_alsize: size of the EC header aligned to @hdrs_min_io_size
+ * @vid_hdr_alsize: size of the VID header aligned to @hdrs_min_io_size
+ * @vid_hdr_offset: starting offset of the volume identifier header (might be
+ *                  unaligned)
+ * @vid_hdr_aloffset: starting offset of the VID header aligned to
+ *                    @hdrs_min_io_size
+ * @vid_hdr_shift: contains @vid_hdr_offset - @vid_hdr_aloffset
+ * @bad_allowed: whether the MTD device admits bad physical eraseblocks or not
+ * @nor_flash: non-zero if working on top of NOR flash
+ * @max_write_size: maximum amount of bytes the underlying flash can write at a
+ *                  time (MTD write buffer size)
+ * @mtd: MTD device descriptor
+ *
+ * @peb_buf: a buffer of PEB size used for different purposes
+ * @buf_mutex: protects @peb_buf
+ * @ckvol_mutex: serializes static volume checking when opening
+ *
+ * @dbg: debugging information for this UBI device
+ */
+struct ubi_device {
+	struct cdev cdev;
+	struct device dev;
+	int ubi_num;
+	char ubi_name[sizeof(UBI_NAME_STR)+5];
+	int vol_count;
+	struct ubi_volume *volumes[UBI_MAX_VOLUMES+UBI_INT_VOL_COUNT];
+	spinlock_t volumes_lock;
+	int ref_count;
+	int image_seq;
+
+	int rsvd_pebs;
+	int avail_pebs;
+	int beb_rsvd_pebs;
+	int beb_rsvd_level;
+	int bad_peb_limit;
+
+	int autoresize_vol_id;
+	int vtbl_slots;
+	int vtbl_size;
+	struct ubi_vtbl_record *vtbl;
+	struct mutex device_mutex;
+
+	int max_ec;
+	/* Note, mean_ec is not updated run-time - should be fixed */
+	int mean_ec;
+
+	/* EBA sub-system's stuff */
+	unsigned long long global_sqnum;
+	spinlock_t ltree_lock;
+	struct rb_root ltree;
+	struct mutex alc_mutex;
+
+	/* Fastmap stuff */
+	int fm_disabled;
+	struct ubi_fastmap_layout *fm;
+	struct ubi_fm_pool fm_pool;
+	struct ubi_fm_pool fm_wl_pool;
+	struct rw_semaphore fm_eba_sem;
+	struct rw_semaphore fm_protect;
+	void *fm_buf;
+	size_t fm_size;
+	struct work_struct fm_work;
+	int fm_work_scheduled;
+	int fast_attach;
+	struct ubi_wl_entry *fm_anchor;
+	int fm_do_produce_anchor;
+
+	/* Wear-leveling sub-system's stuff */
+	struct rb_root used;
+	struct rb_root erroneous;
+	struct rb_root free;
+	int free_count;
+	struct rb_root scrub;
+	struct list_head pq[UBI_PROT_QUEUE_LEN];
+	int pq_head;
+	spinlock_t wl_lock;
+	struct mutex move_mutex;
+	struct rw_semaphore work_sem;
+	int wl_scheduled;
+	struct ubi_wl_entry **lookuptbl;
+	struct ubi_wl_entry *move_from;
+	struct ubi_wl_entry *move_to;
+	int move_to_put;
+	struct list_head works;
+	int works_count;
+	struct task_struct *bgt_thread;
+	int thread_enabled;
+	char bgt_name[sizeof(UBI_BGT_NAME_PATTERN)+2];
+
+	/* I/O sub-system's stuff */
+	long long flash_size;
+	int peb_count;
+	int peb_size;
+	int bad_peb_count;
+	int good_peb_count;
+	int corr_peb_count;
+	int erroneous_peb_count;
+	int max_erroneous;
+	int min_io_size;
+	int hdrs_min_io_size;
+	int ro_mode;
+	int leb_size;
+	int leb_start;
+	int ec_hdr_alsize;
+	int vid_hdr_alsize;
+	int vid_hdr_offset;
+	int vid_hdr_aloffset;
+	int vid_hdr_shift;
+	unsigned int bad_allowed:1;
+	unsigned int nor_flash:1;
+	int max_write_size;
+	struct mtd_info *mtd;
+
+	void *peb_buf;
+	struct mutex buf_mutex;
+	struct mutex ckvol_mutex;
+
+	struct ubi_debug_info dbg;
+};
+
+/**
+ * struct ubi_ainf_peb - attach information about a physical eraseblock.
+ * @ec: erase counter (%UBI_UNKNOWN if it is unknown)
+ * @pnum: physical eraseblock number
+ * @vol_id: ID of the volume this LEB belongs to
+ * @lnum: logical eraseblock number
+ * @scrub: if this physical eraseblock needs scrubbing
+ * @copy_flag: this LEB is a copy (@copy_flag is set in VID header of this LEB)
+ * @sqnum: sequence number
+ * @u: unions RB-tree or @list links
+ * @u.rb: link in the per-volume RB-tree of &struct ubi_ainf_peb objects
+ * @u.list: link in one of the eraseblock lists
+ *
+ * One object of this type is allocated for each physical eraseblock when
+ * attaching an MTD device. Note, if this PEB does not belong to any LEB /
+ * volume, the @vol_id and @lnum fields are initialized to %UBI_UNKNOWN.
+ */
+struct ubi_ainf_peb {
+	int ec;
+	int pnum;
+	int vol_id;
+	int lnum;
+	unsigned int scrub:1;
+	unsigned int copy_flag:1;
+	unsigned long long sqnum;
+	union {
+		struct rb_node rb;
+		struct list_head list;
+	} u;
+};
+
+/**
+ * struct ubi_ainf_volume - attaching information about a volume.
+ * @vol_id: volume ID
+ * @highest_lnum: highest logical eraseblock number in this volume
+ * @leb_count: number of logical eraseblocks in this volume
+ * @vol_type: volume type
+ * @used_ebs: number of used logical eraseblocks in this volume (only for
+ *            static volumes)
+ * @last_data_size: amount of data in the last logical eraseblock of this
+ *                  volume (always equivalent to the usable logical eraseblock
+ *                  size in case of dynamic volumes)
+ * @data_pad: how many bytes at the end of logical eraseblocks of this volume
+ *            are not used (due to volume alignment)
+ * @compat: compatibility flags of this volume
+ * @rb: link in the volume RB-tree
+ * @root: root of the RB-tree containing all the eraseblock belonging to this
+ *        volume (&struct ubi_ainf_peb objects)
+ *
+ * One object of this type is allocated for each volume when attaching an MTD
+ * device.
+ */
+struct ubi_ainf_volume {
+	int vol_id;
+	int highest_lnum;
+	int leb_count;
+	int vol_type;
+	int used_ebs;
+	int last_data_size;
+	int data_pad;
+	int compat;
+	struct rb_node rb;
+	struct rb_root root;
+};
+
+/**
+ * struct ubi_attach_info - MTD device attaching information.
+ * @volumes: root of the volume RB-tree
+ * @corr: list of corrupted physical eraseblocks
+ * @free: list of free physical eraseblocks
+ * @erase: list of physical eraseblocks which have to be erased
+ * @alien: list of physical eraseblocks which should not be used by UBI (e.g.,
+ *         those belonging to "preserve"-compatible internal volumes)
+ * @fastmap: list of physical eraseblocks which relate to fastmap (e.g.,
+ *           eraseblocks of the current and not yet erased old fastmap blocks)
+ * @corr_peb_count: count of PEBs in the @corr list
+ * @empty_peb_count: count of PEBs which are presumably empty (contain only
+ *                   0xFF bytes)
+ * @alien_peb_count: count of PEBs in the @alien list
+ * @bad_peb_count: count of bad physical eraseblocks
+ * @maybe_bad_peb_count: count of bad physical eraseblocks which are not marked
+ *                       as bad yet, but which look like bad
+ * @vols_found: number of volumes found
+ * @highest_vol_id: highest volume ID
+ * @is_empty: flag indicating whether the MTD device is empty or not
+ * @force_full_scan: flag indicating whether we need to do a full scan and drop
+		     all existing Fastmap data structures
+ * @min_ec: lowest erase counter value
+ * @max_ec: highest erase counter value
+ * @max_sqnum: highest sequence number value
+ * @mean_ec: mean erase counter value
+ * @ec_sum: a temporary variable used when calculating @mean_ec
+ * @ec_count: a temporary variable used when calculating @mean_ec
+ * @aeb_slab_cache: slab cache for &struct ubi_ainf_peb objects
+ * @ech: temporary EC header. Only available during scan
+ * @vidh: temporary VID buffer. Only available during scan
+ *
+ * This data structure contains the result of attaching an MTD device and may
+ * be used by other UBI sub-systems to build final UBI data structures, further
+ * error-recovery and so on.
+ */
+struct ubi_attach_info {
+	struct rb_root volumes;
+	struct list_head corr;
+	struct list_head free;
+	struct list_head erase;
+	struct list_head alien;
+	struct list_head fastmap;
+	int corr_peb_count;
+	int empty_peb_count;
+	int alien_peb_count;
+	int bad_peb_count;
+	int maybe_bad_peb_count;
+	int vols_found;
+	int highest_vol_id;
+	int is_empty;
+	int force_full_scan;
+	int min_ec;
+	int max_ec;
+	unsigned long long max_sqnum;
+	int mean_ec;
+	uint64_t ec_sum;
+	int ec_count;
+	struct kmem_cache *aeb_slab_cache;
+	struct ubi_ec_hdr *ech;
+	struct ubi_vid_io_buf *vidb;
+};
+
+/**
+ * struct ubi_work - UBI work description data structure.
+ * @list: a link in the list of pending works
+ * @func: worker function
+ * @e: physical eraseblock to erase
+ * @vol_id: the volume ID on which this erasure is being performed
+ * @lnum: the logical eraseblock number
+ * @torture: if the physical eraseblock has to be tortured
+ *
+ * The @func pointer points to the worker function. If the @shutdown argument is
+ * not zero, the worker has to free the resources and exit immediately as the
+ * WL sub-system is shutting down.
+ * The worker has to return zero in case of success and a negative error code in
+ * case of failure.
+ */
+struct ubi_work {
+	struct list_head list;
+	int (*func)(struct ubi_device *ubi, struct ubi_work *wrk, int shutdown);
+	/* The below fields are only relevant to erasure works */
+	struct ubi_wl_entry *e;
+	int vol_id;
+	int lnum;
+	int torture;
+};
+
+#include "debug.h"
+
+extern struct kmem_cache *ubi_wl_entry_slab;
+extern const struct file_operations ubi_ctrl_cdev_operations;
+extern const struct file_operations ubi_cdev_operations;
+extern const struct file_operations ubi_vol_cdev_operations;
+extern struct class ubi_class;
+extern struct mutex ubi_devices_mutex;
+extern struct blocking_notifier_head ubi_notifiers;
+
+/* attach.c */
+struct ubi_ainf_peb *ubi_alloc_aeb(struct ubi_attach_info *ai, int pnum,
+				   int ec);
+void ubi_free_aeb(struct ubi_attach_info *ai, struct ubi_ainf_peb *aeb);
+int ubi_add_to_av(struct ubi_device *ubi, struct ubi_attach_info *ai, int pnum,
+		  int ec, const struct ubi_vid_hdr *vid_hdr, int bitflips);
+struct ubi_ainf_volume *ubi_add_av(struct ubi_attach_info *ai, int vol_id);
+struct ubi_ainf_volume *ubi_find_av(const struct ubi_attach_info *ai,
+				    int vol_id);
+void ubi_remove_av(struct ubi_attach_info *ai, struct ubi_ainf_volume *av);
+struct ubi_ainf_peb *ubi_early_get_peb(struct ubi_device *ubi,
+				       struct ubi_attach_info *ai);
+int ubi_attach(struct ubi_device *ubi, int force_scan);
+void ubi_destroy_ai(struct ubi_attach_info *ai);
+
+/* vtbl.c */
+int ubi_change_vtbl_record(struct ubi_device *ubi, int idx,
+			   struct ubi_vtbl_record *vtbl_rec);
+int ubi_vtbl_rename_volumes(struct ubi_device *ubi,
+			    struct list_head *rename_list);
+int ubi_read_volume_table(struct ubi_device *ubi, struct ubi_attach_info *ai);
+
+/* vmt.c */
+int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req);
+int ubi_remove_volume(struct ubi_volume_desc *desc, int no_vtbl);
+int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs);
+int ubi_rename_volumes(struct ubi_device *ubi, struct list_head *rename_list);
+int ubi_add_volume(struct ubi_device *ubi, struct ubi_volume *vol);
+void ubi_free_volume(struct ubi_device *ubi, struct ubi_volume *vol);
+
+/* upd.c */
+int ubi_start_update(struct ubi_device *ubi, struct ubi_volume *vol,
+		     long long bytes);
+int ubi_more_update_data(struct ubi_device *ubi, struct ubi_volume *vol,
+			 const void __user *buf, int count);
+int ubi_start_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
+			 const struct ubi_leb_change_req *req);
+int ubi_more_leb_change_data(struct ubi_device *ubi, struct ubi_volume *vol,
+			     const void __user *buf, int count);
+
+/* misc.c */
+int ubi_calc_data_len(const struct ubi_device *ubi, const void *buf,
+		      int length);
+int ubi_check_volume(struct ubi_device *ubi, int vol_id);
+void ubi_update_reserved(struct ubi_device *ubi);
+void ubi_calculate_reserved(struct ubi_device *ubi);
+int ubi_check_pattern(const void *buf, uint8_t patt, int size);
+
+static inline bool ubi_leb_valid(struct ubi_volume *vol, int lnum)
+{
+	return lnum >= 0 && lnum < vol->reserved_pebs;
+}
+
+/* eba.c */
+struct ubi_eba_table *ubi_eba_create_table(struct ubi_volume *vol,
+					   int nentries);
+void ubi_eba_destroy_table(struct ubi_eba_table *tbl);
+void ubi_eba_copy_table(struct ubi_volume *vol, struct ubi_eba_table *dst,
+			int nentries);
+void ubi_eba_replace_table(struct ubi_volume *vol, struct ubi_eba_table *tbl);
+void ubi_eba_get_ldesc(struct ubi_volume *vol, int lnum,
+		       struct ubi_eba_leb_desc *ldesc);
+bool ubi_eba_is_mapped(struct ubi_volume *vol, int lnum);
+int ubi_eba_unmap_leb(struct ubi_device *ubi, struct ubi_volume *vol,
+		      int lnum);
+int ubi_eba_read_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
+		     void *buf, int offset, int len, int check);
+int ubi_eba_read_leb_sg(struct ubi_device *ubi, struct ubi_volume *vol,
+			struct ubi_sgl *sgl, int lnum, int offset, int len,
+			int check);
+int ubi_eba_write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
+		      const void *buf, int offset, int len);
+int ubi_eba_write_leb_st(struct ubi_device *ubi, struct ubi_volume *vol,
+			 int lnum, const void *buf, int len, int used_ebs);
+int ubi_eba_atomic_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
+			      int lnum, const void *buf, int len);
+int ubi_eba_copy_leb(struct ubi_device *ubi, int from, int to,
+		     struct ubi_vid_io_buf *vidb);
+int ubi_eba_init(struct ubi_device *ubi, struct ubi_attach_info *ai);
+unsigned long long ubi_next_sqnum(struct ubi_device *ubi);
+int self_check_eba(struct ubi_device *ubi, struct ubi_attach_info *ai_fastmap,
+		   struct ubi_attach_info *ai_scan);
+
+/* wl.c */
+int ubi_wl_get_peb(struct ubi_device *ubi);
+int ubi_wl_put_peb(struct ubi_device *ubi, int vol_id, int lnum,
+		   int pnum, int torture);
+int ubi_wl_flush(struct ubi_device *ubi, int vol_id, int lnum);
+int ubi_wl_scrub_peb(struct ubi_device *ubi, int pnum);
+int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai);
+void ubi_wl_close(struct ubi_device *ubi);
+int ubi_thread(void *u);
+struct ubi_wl_entry *ubi_wl_get_fm_peb(struct ubi_device *ubi, int anchor);
+int ubi_wl_put_fm_peb(struct ubi_device *ubi, struct ubi_wl_entry *used_e,
+		      int lnum, int torture);
+int ubi_is_erase_work(struct ubi_work *wrk);
+void ubi_refill_pools(struct ubi_device *ubi);
+int ubi_ensure_anchor_pebs(struct ubi_device *ubi);
+int ubi_bitflip_check(struct ubi_device *ubi, int pnum, int force_scrub);
+
+/* io.c */
+int ubi_io_read(const struct ubi_device *ubi, void *buf, int pnum, int offset,
+		int len);
+int ubi_io_write(struct ubi_device *ubi, const void *buf, int pnum, int offset,
+		 int len);
+int ubi_io_sync_erase(struct ubi_device *ubi, int pnum, int torture);
+int ubi_io_is_bad(const struct ubi_device *ubi, int pnum);
+int ubi_io_mark_bad(const struct ubi_device *ubi, int pnum);
+int ubi_io_read_ec_hdr(struct ubi_device *ubi, int pnum,
+		       struct ubi_ec_hdr *ec_hdr, int verbose);
+int ubi_io_write_ec_hdr(struct ubi_device *ubi, int pnum,
+			struct ubi_ec_hdr *ec_hdr);
+int ubi_io_read_vid_hdr(struct ubi_device *ubi, int pnum,
+			struct ubi_vid_io_buf *vidb, int verbose);
+int ubi_io_write_vid_hdr(struct ubi_device *ubi, int pnum,
+			 struct ubi_vid_io_buf *vidb);
+
+/* build.c */
+int ubi_attach_mtd_dev(struct mtd_info *mtd, int ubi_num,
+		       int vid_hdr_offset, int max_beb_per1024,
+		       bool disable_fm);
+int ubi_detach_mtd_dev(int ubi_num, int anyway);
+struct ubi_device *ubi_get_device(int ubi_num);
+void ubi_put_device(struct ubi_device *ubi);
+struct ubi_device *ubi_get_by_major(int major);
+int ubi_major2num(int major);
+int ubi_volume_notify(struct ubi_device *ubi, struct ubi_volume *vol,
+		      int ntype);
+int ubi_notify_all(struct ubi_device *ubi, int ntype,
+		   struct notifier_block *nb);
+int ubi_enumerate_volumes(struct notifier_block *nb);
+void ubi_free_all_volumes(struct ubi_device *ubi);
+void ubi_free_internal_volumes(struct ubi_device *ubi);
+
+/* kapi.c */
+void ubi_do_get_device_info(struct ubi_device *ubi, struct ubi_device_info *di);
+void ubi_do_get_volume_info(struct ubi_device *ubi, struct ubi_volume *vol,
+			    struct ubi_volume_info *vi);
+/* scan.c */
+int ubi_compare_lebs(struct ubi_device *ubi, const struct ubi_ainf_peb *aeb,
+		      int pnum, const struct ubi_vid_hdr *vid_hdr);
+
+/* fastmap.c */
+#ifdef CONFIG_MTD_UBI_FASTMAP
+size_t ubi_calc_fm_size(struct ubi_device *ubi);
+int ubi_update_fastmap(struct ubi_device *ubi);
+int ubi_scan_fastmap(struct ubi_device *ubi, struct ubi_attach_info *ai,
+		     struct ubi_attach_info *scan_ai);
+int ubi_fastmap_init_checkmap(struct ubi_volume *vol, int leb_count);
+void ubi_fastmap_destroy_checkmap(struct ubi_volume *vol);
+#else
+static inline int ubi_update_fastmap(struct ubi_device *ubi) { return 0; }
+static inline int ubi_fastmap_init_checkmap(struct ubi_volume *vol, int leb_count) { return 0; }
+static inline void ubi_fastmap_destroy_checkmap(struct ubi_volume *vol) {}
+#endif
+
+/* block.c */
+#ifdef CONFIG_MTD_UBI_BLOCK
+int ubiblock_init(void);
+void ubiblock_exit(void);
+int ubiblock_create(struct ubi_volume_info *vi);
+int ubiblock_remove(struct ubi_volume_info *vi);
+#else
+static inline int ubiblock_init(void) { return 0; }
+static inline void ubiblock_exit(void) {}
+static inline int ubiblock_create(struct ubi_volume_info *vi)
+{
+	return -ENOSYS;
+}
+static inline int ubiblock_remove(struct ubi_volume_info *vi)
+{
+	return -ENOSYS;
+}
+#endif
+
+/*
+ * ubi_for_each_free_peb - walk the UBI free RB tree.
+ * @ubi: UBI device description object
+ * @e: a pointer to a ubi_wl_entry to use as cursor
+ * @pos: a pointer to RB-tree entry type to use as a loop counter
+ */
+#define ubi_for_each_free_peb(ubi, e, tmp_rb)	\
+	ubi_rb_for_each_entry((tmp_rb), (e), &(ubi)->free, u.rb)
+
+/*
+ * ubi_for_each_used_peb - walk the UBI used RB tree.
+ * @ubi: UBI device description object
+ * @e: a pointer to a ubi_wl_entry to use as cursor
+ * @pos: a pointer to RB-tree entry type to use as a loop counter
+ */
+#define ubi_for_each_used_peb(ubi, e, tmp_rb)	\
+	ubi_rb_for_each_entry((tmp_rb), (e), &(ubi)->used, u.rb)
+
+/*
+ * ubi_for_each_scub_peb - walk the UBI scub RB tree.
+ * @ubi: UBI device description object
+ * @e: a pointer to a ubi_wl_entry to use as cursor
+ * @pos: a pointer to RB-tree entry type to use as a loop counter
+ */
+#define ubi_for_each_scrub_peb(ubi, e, tmp_rb)	\
+	ubi_rb_for_each_entry((tmp_rb), (e), &(ubi)->scrub, u.rb)
+
+/*
+ * ubi_for_each_protected_peb - walk the UBI protection queue.
+ * @ubi: UBI device description object
+ * @i: a integer used as counter
+ * @e: a pointer to a ubi_wl_entry to use as cursor
+ */
+#define ubi_for_each_protected_peb(ubi, i, e)	\
+	for ((i) = 0; (i) < UBI_PROT_QUEUE_LEN; (i)++)	\
+		list_for_each_entry((e), &(ubi->pq[(i)]), u.list)
+
+/*
+ * ubi_rb_for_each_entry - walk an RB-tree.
+ * @rb: a pointer to type 'struct rb_node' to use as a loop counter
+ * @pos: a pointer to RB-tree entry type to use as a loop counter
+ * @root: RB-tree's root
+ * @member: the name of the 'struct rb_node' within the RB-tree entry
+ */
+#define ubi_rb_for_each_entry(rb, pos, root, member)                         \
+	for (rb = rb_first(root),                                            \
+	     pos = (rb ? container_of(rb, typeof(*pos), member) : NULL);     \
+	     rb;                                                             \
+	     rb = rb_next(rb),                                               \
+	     pos = (rb ? container_of(rb, typeof(*pos), member) : NULL))
+
+/*
+ * ubi_move_aeb_to_list - move a PEB from the volume tree to a list.
+ *
+ * @av: volume attaching information
+ * @aeb: attaching eraseblock information
+ * @list: the list to move to
+ */
+static inline void ubi_move_aeb_to_list(struct ubi_ainf_volume *av,
+					 struct ubi_ainf_peb *aeb,
+					 struct list_head *list)
+{
+		rb_erase(&aeb->u.rb, &av->root);
+		list_add_tail(&aeb->u.list, list);
+}
+
+/**
+ * ubi_init_vid_buf - Initialize a VID buffer
+ * @ubi: the UBI device
+ * @vidb: the VID buffer to initialize
+ * @buf: the underlying buffer
+ */
+static inline void ubi_init_vid_buf(const struct ubi_device *ubi,
+				    struct ubi_vid_io_buf *vidb,
+				    void *buf)
+{
+	if (buf)
+		memset(buf, 0, ubi->vid_hdr_alsize);
+
+	vidb->buffer = buf;
+	vidb->hdr = buf + ubi->vid_hdr_shift;
+}
+
+/**
+ * ubi_init_vid_buf - Allocate a VID buffer
+ * @ubi: the UBI device
+ * @gfp_flags: GFP flags to use for the allocation
+ */
+static inline struct ubi_vid_io_buf *
+ubi_alloc_vid_buf(const struct ubi_device *ubi, gfp_t gfp_flags)
+{
+	struct ubi_vid_io_buf *vidb;
+	void *buf;
+
+	vidb = kzalloc(sizeof(*vidb), gfp_flags);
+	if (!vidb)
+		return NULL;
+
+	buf = kmalloc(ubi->vid_hdr_alsize, gfp_flags);
+	if (!buf) {
+		kfree(vidb);
+		return NULL;
+	}
+
+	ubi_init_vid_buf(ubi, vidb, buf);
+
+	return vidb;
+}
+
+/**
+ * ubi_free_vid_buf - Free a VID buffer
+ * @vidb: the VID buffer to free
+ */
+static inline void ubi_free_vid_buf(struct ubi_vid_io_buf *vidb)
+{
+	if (!vidb)
+		return;
+
+	kfree(vidb->buffer);
+	kfree(vidb);
+}
+
+/**
+ * ubi_get_vid_hdr - Get the VID header attached to a VID buffer
+ * @vidb: VID buffer
+ */
+static inline struct ubi_vid_hdr *ubi_get_vid_hdr(struct ubi_vid_io_buf *vidb)
+{
+	return vidb->hdr;
+}
+
+/*
+ * This function is equivalent to 'ubi_io_read()', but @offset is relative to
+ * the beginning of the logical eraseblock, not to the beginning of the
+ * physical eraseblock.
+ */
+static inline int ubi_io_read_data(const struct ubi_device *ubi, void *buf,
+				   int pnum, int offset, int len)
+{
+	ubi_assert(offset >= 0);
+	return ubi_io_read(ubi, buf, pnum, offset + ubi->leb_start, len);
+}
+
+/*
+ * This function is equivalent to 'ubi_io_write()', but @offset is relative to
+ * the beginning of the logical eraseblock, not to the beginning of the
+ * physical eraseblock.
+ */
+static inline int ubi_io_write_data(struct ubi_device *ubi, const void *buf,
+				    int pnum, int offset, int len)
+{
+	ubi_assert(offset >= 0);
+	return ubi_io_write(ubi, buf, pnum, offset + ubi->leb_start, len);
+}
+
+/**
+ * ubi_ro_mode - switch to read-only mode.
+ * @ubi: UBI device description object
+ */
+static inline void ubi_ro_mode(struct ubi_device *ubi)
+{
+	if (!ubi->ro_mode) {
+		ubi->ro_mode = 1;
+		ubi_warn(ubi, "switch to read-only mode");
+		dump_stack();
+	}
+}
+
+/**
+ * vol_id2idx - get table index by volume ID.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ */
+static inline int vol_id2idx(const struct ubi_device *ubi, int vol_id)
+{
+	if (vol_id >= UBI_INTERNAL_VOL_START)
+		return vol_id - UBI_INTERNAL_VOL_START + ubi->vtbl_slots;
+	else
+		return vol_id;
+}
+
+/**
+ * idx2vol_id - get volume ID by table index.
+ * @ubi: UBI device description object
+ * @idx: table index
+ */
+static inline int idx2vol_id(const struct ubi_device *ubi, int idx)
+{
+	if (idx >= ubi->vtbl_slots)
+		return idx - ubi->vtbl_slots + UBI_INTERNAL_VOL_START;
+	else
+		return idx;
+}
+
+/**
+ * ubi_is_fm_vol - check whether a volume ID is a Fastmap volume.
+ * @vol_id: volume ID
+ */
+static inline bool ubi_is_fm_vol(int vol_id)
+{
+	switch (vol_id) {
+		case UBI_FM_SB_VOLUME_ID:
+		case UBI_FM_DATA_VOLUME_ID:
+		return true;
+	}
+
+	return false;
+}
+
+/**
+ * ubi_find_fm_block - check whether a PEB is part of the current Fastmap.
+ * @ubi: UBI device description object
+ * @pnum: physical eraseblock to look for
+ *
+ * This function returns a wear leveling object if @pnum relates to the current
+ * fastmap, @NULL otherwise.
+ */
+static inline struct ubi_wl_entry *ubi_find_fm_block(const struct ubi_device *ubi,
+						     int pnum)
+{
+	int i;
+
+	if (ubi->fm) {
+		for (i = 0; i < ubi->fm->used_blocks; i++) {
+			if (ubi->fm->e[i]->pnum == pnum)
+				return ubi->fm->e[i];
+		}
+	}
+
+	return NULL;
+}
+
+#endif /* !__UBI_UBI_H__ */
diff --git a/drivers/mtd/ubi/upd.c b/drivers/mtd/ubi/upd.c
new file mode 100644
index 0000000000..962f693cf8
--- /dev/null
+++ b/drivers/mtd/ubi/upd.c
@@ -0,0 +1,420 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ * Copyright (c) Nokia Corporation, 2006
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ *
+ * Jan 2007: Alexander Schmidt, hacked per-volume update.
+ */
+
+/*
+ * This file contains implementation of the volume update and atomic LEB change
+ * functionality.
+ *
+ * The update operation is based on the per-volume update marker which is
+ * stored in the volume table. The update marker is set before the update
+ * starts, and removed after the update has been finished. So if the update was
+ * interrupted by an unclean re-boot or due to some other reasons, the update
+ * marker stays on the flash media and UBI finds it when it attaches the MTD
+ * device next time. If the update marker is set for a volume, the volume is
+ * treated as damaged and most I/O operations are prohibited. Only a new update
+ * operation is allowed.
+ *
+ * Note, in general it is possible to implement the update operation as a
+ * transaction with a roll-back capability.
+ */
+
+#include <linux/err.h>
+#include <linux/uaccess.h>
+#include <linux/math64.h>
+#include "ubi.h"
+
+/**
+ * set_update_marker - set update marker.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ *
+ * This function sets the update marker flag for volume @vol. Returns zero
+ * in case of success and a negative error code in case of failure.
+ */
+static int set_update_marker(struct ubi_device *ubi, struct ubi_volume *vol)
+{
+	int err;
+	struct ubi_vtbl_record vtbl_rec;
+
+	dbg_gen("set update marker for volume %d", vol->vol_id);
+
+	if (vol->upd_marker) {
+		ubi_assert(ubi->vtbl[vol->vol_id].upd_marker);
+		dbg_gen("already set");
+		return 0;
+	}
+
+	vtbl_rec = ubi->vtbl[vol->vol_id];
+	vtbl_rec.upd_marker = 1;
+
+	mutex_lock(&ubi->device_mutex);
+	err = ubi_change_vtbl_record(ubi, vol->vol_id, &vtbl_rec);
+	vol->upd_marker = 1;
+	mutex_unlock(&ubi->device_mutex);
+	return err;
+}
+
+/**
+ * clear_update_marker - clear update marker.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ * @bytes: new data size in bytes
+ *
+ * This function clears the update marker for volume @vol, sets new volume
+ * data size and clears the "corrupted" flag (static volumes only). Returns
+ * zero in case of success and a negative error code in case of failure.
+ */
+static int clear_update_marker(struct ubi_device *ubi, struct ubi_volume *vol,
+			       long long bytes)
+{
+	int err;
+	struct ubi_vtbl_record vtbl_rec;
+
+	dbg_gen("clear update marker for volume %d", vol->vol_id);
+
+	vtbl_rec = ubi->vtbl[vol->vol_id];
+	ubi_assert(vol->upd_marker && vtbl_rec.upd_marker);
+	vtbl_rec.upd_marker = 0;
+
+	if (vol->vol_type == UBI_STATIC_VOLUME) {
+		vol->corrupted = 0;
+		vol->used_bytes = bytes;
+		vol->used_ebs = div_u64_rem(bytes, vol->usable_leb_size,
+					    &vol->last_eb_bytes);
+		if (vol->last_eb_bytes)
+			vol->used_ebs += 1;
+		else
+			vol->last_eb_bytes = vol->usable_leb_size;
+	}
+
+	mutex_lock(&ubi->device_mutex);
+	err = ubi_change_vtbl_record(ubi, vol->vol_id, &vtbl_rec);
+	vol->upd_marker = 0;
+	mutex_unlock(&ubi->device_mutex);
+	return err;
+}
+
+/**
+ * ubi_start_update - start volume update.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ * @bytes: update bytes
+ *
+ * This function starts volume update operation. If @bytes is zero, the volume
+ * is just wiped out. Returns zero in case of success and a negative error code
+ * in case of failure.
+ */
+int ubi_start_update(struct ubi_device *ubi, struct ubi_volume *vol,
+		     long long bytes)
+{
+	int i, err;
+
+	dbg_gen("start update of volume %d, %llu bytes", vol->vol_id, bytes);
+	ubi_assert(!vol->updating && !vol->changing_leb);
+	vol->updating = 1;
+
+	vol->upd_buf = vmalloc(ubi->leb_size);
+	if (!vol->upd_buf)
+		return -ENOMEM;
+
+	err = set_update_marker(ubi, vol);
+	if (err)
+		return err;
+
+	/* Before updating - wipe out the volume */
+	for (i = 0; i < vol->reserved_pebs; i++) {
+		err = ubi_eba_unmap_leb(ubi, vol, i);
+		if (err)
+			return err;
+	}
+
+	err = ubi_wl_flush(ubi, UBI_ALL, UBI_ALL);
+	if (err)
+		return err;
+
+	if (bytes == 0) {
+		err = clear_update_marker(ubi, vol, 0);
+		if (err)
+			return err;
+
+		vfree(vol->upd_buf);
+		vol->updating = 0;
+		return 0;
+	}
+
+	vol->upd_ebs = div_u64(bytes + vol->usable_leb_size - 1,
+			       vol->usable_leb_size);
+	vol->upd_bytes = bytes;
+	vol->upd_received = 0;
+	return 0;
+}
+
+/**
+ * ubi_start_leb_change - start atomic LEB change.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ * @req: operation request
+ *
+ * This function starts atomic LEB change operation. Returns zero in case of
+ * success and a negative error code in case of failure.
+ */
+int ubi_start_leb_change(struct ubi_device *ubi, struct ubi_volume *vol,
+			 const struct ubi_leb_change_req *req)
+{
+	ubi_assert(!vol->updating && !vol->changing_leb);
+
+	dbg_gen("start changing LEB %d:%d, %u bytes",
+		vol->vol_id, req->lnum, req->bytes);
+	if (req->bytes == 0)
+		return ubi_eba_atomic_leb_change(ubi, vol, req->lnum, NULL, 0);
+
+	vol->upd_bytes = req->bytes;
+	vol->upd_received = 0;
+	vol->changing_leb = 1;
+	vol->ch_lnum = req->lnum;
+
+	vol->upd_buf = vmalloc(ALIGN((int)req->bytes, ubi->min_io_size));
+	if (!vol->upd_buf)
+		return -ENOMEM;
+
+	return 0;
+}
+
+/**
+ * write_leb - write update data.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ * @lnum: logical eraseblock number
+ * @buf: data to write
+ * @len: data size
+ * @used_ebs: how many logical eraseblocks will this volume contain (static
+ * volumes only)
+ *
+ * This function writes update data to corresponding logical eraseblock. In
+ * case of dynamic volume, this function checks if the data contains 0xFF bytes
+ * at the end. If yes, the 0xFF bytes are cut and not written. So if the whole
+ * buffer contains only 0xFF bytes, the LEB is left unmapped.
+ *
+ * The reason why we skip the trailing 0xFF bytes in case of dynamic volume is
+ * that we want to make sure that more data may be appended to the logical
+ * eraseblock in future. Indeed, writing 0xFF bytes may have side effects and
+ * this PEB won't be writable anymore. So if one writes the file-system image
+ * to the UBI volume where 0xFFs mean free space - UBI makes sure this free
+ * space is writable after the update.
+ *
+ * We do not do this for static volumes because they are read-only. But this
+ * also cannot be done because we have to store per-LEB CRC and the correct
+ * data length.
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int write_leb(struct ubi_device *ubi, struct ubi_volume *vol, int lnum,
+		     void *buf, int len, int used_ebs)
+{
+	int err;
+
+	if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
+		int l = ALIGN(len, ubi->min_io_size);
+
+		memset(buf + len, 0xFF, l - len);
+		len = ubi_calc_data_len(ubi, buf, l);
+		if (len == 0) {
+			dbg_gen("all %d bytes contain 0xFF - skip", len);
+			return 0;
+		}
+
+		err = ubi_eba_write_leb(ubi, vol, lnum, buf, 0, len);
+	} else {
+		/*
+		 * When writing static volume, and this is the last logical
+		 * eraseblock, the length (@len) does not have to be aligned to
+		 * the minimal flash I/O unit. The 'ubi_eba_write_leb_st()'
+		 * function accepts exact (unaligned) length and stores it in
+		 * the VID header. And it takes care of proper alignment by
+		 * padding the buffer. Here we just make sure the padding will
+		 * contain zeros, not random trash.
+		 */
+		memset(buf + len, 0, vol->usable_leb_size - len);
+		err = ubi_eba_write_leb_st(ubi, vol, lnum, buf, len, used_ebs);
+	}
+
+	return err;
+}
+
+/**
+ * ubi_more_update_data - write more update data.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ * @buf: write data (user-space memory buffer)
+ * @count: how much bytes to write
+ *
+ * This function writes more data to the volume which is being updated. It may
+ * be called arbitrary number of times until all the update data arriveis. This
+ * function returns %0 in case of success, number of bytes written during the
+ * last call if the whole volume update has been successfully finished, and a
+ * negative error code in case of failure.
+ */
+int ubi_more_update_data(struct ubi_device *ubi, struct ubi_volume *vol,
+			 const void __user *buf, int count)
+{
+	int lnum, offs, err = 0, len, to_write = count;
+
+	dbg_gen("write %d of %lld bytes, %lld already passed",
+		count, vol->upd_bytes, vol->upd_received);
+
+	if (ubi->ro_mode)
+		return -EROFS;
+
+	lnum = div_u64_rem(vol->upd_received,  vol->usable_leb_size, &offs);
+	if (vol->upd_received + count > vol->upd_bytes)
+		to_write = count = vol->upd_bytes - vol->upd_received;
+
+	/*
+	 * When updating volumes, we accumulate whole logical eraseblock of
+	 * data and write it at once.
+	 */
+	if (offs != 0) {
+		/*
+		 * This is a write to the middle of the logical eraseblock. We
+		 * copy the data to our update buffer and wait for more data or
+		 * flush it if the whole eraseblock is written or the update
+		 * is finished.
+		 */
+
+		len = vol->usable_leb_size - offs;
+		if (len > count)
+			len = count;
+
+		err = copy_from_user(vol->upd_buf + offs, buf, len);
+		if (err)
+			return -EFAULT;
+
+		if (offs + len == vol->usable_leb_size ||
+		    vol->upd_received + len == vol->upd_bytes) {
+			int flush_len = offs + len;
+
+			/*
+			 * OK, we gathered either the whole eraseblock or this
+			 * is the last chunk, it's time to flush the buffer.
+			 */
+			ubi_assert(flush_len <= vol->usable_leb_size);
+			err = write_leb(ubi, vol, lnum, vol->upd_buf, flush_len,
+					vol->upd_ebs);
+			if (err)
+				return err;
+		}
+
+		vol->upd_received += len;
+		count -= len;
+		buf += len;
+		lnum += 1;
+	}
+
+	/*
+	 * If we've got more to write, let's continue. At this point we know we
+	 * are starting from the beginning of an eraseblock.
+	 */
+	while (count) {
+		if (count > vol->usable_leb_size)
+			len = vol->usable_leb_size;
+		else
+			len = count;
+
+		err = copy_from_user(vol->upd_buf, buf, len);
+		if (err)
+			return -EFAULT;
+
+		if (len == vol->usable_leb_size ||
+		    vol->upd_received + len == vol->upd_bytes) {
+			err = write_leb(ubi, vol, lnum, vol->upd_buf,
+					len, vol->upd_ebs);
+			if (err)
+				break;
+		}
+
+		vol->upd_received += len;
+		count -= len;
+		lnum += 1;
+		buf += len;
+	}
+
+	ubi_assert(vol->upd_received <= vol->upd_bytes);
+	if (vol->upd_received == vol->upd_bytes) {
+		err = ubi_wl_flush(ubi, UBI_ALL, UBI_ALL);
+		if (err)
+			return err;
+		/* The update is finished, clear the update marker */
+		err = clear_update_marker(ubi, vol, vol->upd_bytes);
+		if (err)
+			return err;
+		vol->updating = 0;
+		err = to_write;
+		vfree(vol->upd_buf);
+	}
+
+	return err;
+}
+
+/**
+ * ubi_more_leb_change_data - accept more data for atomic LEB change.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ * @buf: write data (user-space memory buffer)
+ * @count: how much bytes to write
+ *
+ * This function accepts more data to the volume which is being under the
+ * "atomic LEB change" operation. It may be called arbitrary number of times
+ * until all data arrives. This function returns %0 in case of success, number
+ * of bytes written during the last call if the whole "atomic LEB change"
+ * operation has been successfully finished, and a negative error code in case
+ * of failure.
+ */
+int ubi_more_leb_change_data(struct ubi_device *ubi, struct ubi_volume *vol,
+			     const void __user *buf, int count)
+{
+	int err;
+
+	dbg_gen("write %d of %lld bytes, %lld already passed",
+		count, vol->upd_bytes, vol->upd_received);
+
+	if (ubi->ro_mode)
+		return -EROFS;
+
+	if (vol->upd_received + count > vol->upd_bytes)
+		count = vol->upd_bytes - vol->upd_received;
+
+	err = copy_from_user(vol->upd_buf + vol->upd_received, buf, count);
+	if (err)
+		return -EFAULT;
+
+	vol->upd_received += count;
+
+	if (vol->upd_received == vol->upd_bytes) {
+		int len = ALIGN((int)vol->upd_bytes, ubi->min_io_size);
+
+		memset(vol->upd_buf + vol->upd_bytes, 0xFF,
+		       len - vol->upd_bytes);
+		len = ubi_calc_data_len(ubi, vol->upd_buf, len);
+		err = ubi_eba_atomic_leb_change(ubi, vol, vol->ch_lnum,
+						vol->upd_buf, len);
+		if (err)
+			return err;
+	}
+
+	ubi_assert(vol->upd_received <= vol->upd_bytes);
+	if (vol->upd_received == vol->upd_bytes) {
+		vol->changing_leb = 0;
+		err = count;
+		vfree(vol->upd_buf);
+	}
+
+	return err;
+}
diff --git a/drivers/mtd/ubi/vmt.c b/drivers/mtd/ubi/vmt.c
new file mode 100644
index 0000000000..2c867d16f8
--- /dev/null
+++ b/drivers/mtd/ubi/vmt.c
@@ -0,0 +1,797 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+/*
+ * This file contains implementation of volume creation, deletion, updating and
+ * resizing.
+ */
+
+#include <linux/err.h>
+#include <linux/math64.h>
+#include <linux/slab.h>
+#include <linux/export.h>
+#include "ubi.h"
+
+static int self_check_volumes(struct ubi_device *ubi);
+
+static ssize_t vol_attribute_show(struct device *dev,
+				  struct device_attribute *attr, char *buf);
+
+/* Device attributes corresponding to files in '/<sysfs>/class/ubi/ubiX_Y' */
+static struct device_attribute attr_vol_reserved_ebs =
+	__ATTR(reserved_ebs, S_IRUGO, vol_attribute_show, NULL);
+static struct device_attribute attr_vol_type =
+	__ATTR(type, S_IRUGO, vol_attribute_show, NULL);
+static struct device_attribute attr_vol_name =
+	__ATTR(name, S_IRUGO, vol_attribute_show, NULL);
+static struct device_attribute attr_vol_corrupted =
+	__ATTR(corrupted, S_IRUGO, vol_attribute_show, NULL);
+static struct device_attribute attr_vol_alignment =
+	__ATTR(alignment, S_IRUGO, vol_attribute_show, NULL);
+static struct device_attribute attr_vol_usable_eb_size =
+	__ATTR(usable_eb_size, S_IRUGO, vol_attribute_show, NULL);
+static struct device_attribute attr_vol_data_bytes =
+	__ATTR(data_bytes, S_IRUGO, vol_attribute_show, NULL);
+static struct device_attribute attr_vol_upd_marker =
+	__ATTR(upd_marker, S_IRUGO, vol_attribute_show, NULL);
+
+/*
+ * "Show" method for files in '/<sysfs>/class/ubi/ubiX_Y/'.
+ *
+ * Consider a situation:
+ * A. process 1 opens a sysfs file related to volume Y, say
+ *    /<sysfs>/class/ubi/ubiX_Y/reserved_ebs;
+ * B. process 2 removes volume Y;
+ * C. process 1 starts reading the /<sysfs>/class/ubi/ubiX_Y/reserved_ebs file;
+ *
+ * In this situation, this function will return %-ENODEV because it will find
+ * out that the volume was removed from the @ubi->volumes array.
+ */
+static ssize_t vol_attribute_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	int ret;
+	struct ubi_volume *vol = container_of(dev, struct ubi_volume, dev);
+	struct ubi_device *ubi = vol->ubi;
+
+	spin_lock(&ubi->volumes_lock);
+	if (!ubi->volumes[vol->vol_id]) {
+		spin_unlock(&ubi->volumes_lock);
+		return -ENODEV;
+	}
+	/* Take a reference to prevent volume removal */
+	vol->ref_count += 1;
+	spin_unlock(&ubi->volumes_lock);
+
+	if (attr == &attr_vol_reserved_ebs)
+		ret = sprintf(buf, "%d\n", vol->reserved_pebs);
+	else if (attr == &attr_vol_type) {
+		const char *tp;
+
+		if (vol->vol_type == UBI_DYNAMIC_VOLUME)
+			tp = "dynamic";
+		else
+			tp = "static";
+		ret = sprintf(buf, "%s\n", tp);
+	} else if (attr == &attr_vol_name)
+		ret = sprintf(buf, "%s\n", vol->name);
+	else if (attr == &attr_vol_corrupted)
+		ret = sprintf(buf, "%d\n", vol->corrupted);
+	else if (attr == &attr_vol_alignment)
+		ret = sprintf(buf, "%d\n", vol->alignment);
+	else if (attr == &attr_vol_usable_eb_size)
+		ret = sprintf(buf, "%d\n", vol->usable_leb_size);
+	else if (attr == &attr_vol_data_bytes)
+		ret = sprintf(buf, "%lld\n", vol->used_bytes);
+	else if (attr == &attr_vol_upd_marker)
+		ret = sprintf(buf, "%d\n", vol->upd_marker);
+	else
+		/* This must be a bug */
+		ret = -EINVAL;
+
+	/* We've done the operation, drop volume and UBI device references */
+	spin_lock(&ubi->volumes_lock);
+	vol->ref_count -= 1;
+	ubi_assert(vol->ref_count >= 0);
+	spin_unlock(&ubi->volumes_lock);
+	return ret;
+}
+
+static struct attribute *volume_dev_attrs[] = {
+	&attr_vol_reserved_ebs.attr,
+	&attr_vol_type.attr,
+	&attr_vol_name.attr,
+	&attr_vol_corrupted.attr,
+	&attr_vol_alignment.attr,
+	&attr_vol_usable_eb_size.attr,
+	&attr_vol_data_bytes.attr,
+	&attr_vol_upd_marker.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(volume_dev);
+
+/* Release method for volume devices */
+static void vol_release(struct device *dev)
+{
+	struct ubi_volume *vol = container_of(dev, struct ubi_volume, dev);
+
+	ubi_eba_replace_table(vol, NULL);
+	ubi_fastmap_destroy_checkmap(vol);
+	kfree(vol);
+}
+
+/**
+ * ubi_create_volume - create volume.
+ * @ubi: UBI device description object
+ * @req: volume creation request
+ *
+ * This function creates volume described by @req. If @req->vol_id id
+ * %UBI_VOL_NUM_AUTO, this function automatically assign ID to the new volume
+ * and saves it in @req->vol_id. Returns zero in case of success and a negative
+ * error code in case of failure. Note, the caller has to have the
+ * @ubi->device_mutex locked.
+ */
+int ubi_create_volume(struct ubi_device *ubi, struct ubi_mkvol_req *req)
+{
+	int i, err, vol_id = req->vol_id;
+	struct ubi_volume *vol;
+	struct ubi_vtbl_record vtbl_rec;
+	struct ubi_eba_table *eba_tbl = NULL;
+
+	if (ubi->ro_mode)
+		return -EROFS;
+
+	vol = kzalloc(sizeof(struct ubi_volume), GFP_KERNEL);
+	if (!vol)
+		return -ENOMEM;
+
+	device_initialize(&vol->dev);
+	vol->dev.release = vol_release;
+	vol->dev.parent = &ubi->dev;
+	vol->dev.class = &ubi_class;
+	vol->dev.groups = volume_dev_groups;
+
+	if (req->flags & UBI_VOL_SKIP_CRC_CHECK_FLG)
+		vol->skip_check = 1;
+
+	spin_lock(&ubi->volumes_lock);
+	if (vol_id == UBI_VOL_NUM_AUTO) {
+		/* Find unused volume ID */
+		dbg_gen("search for vacant volume ID");
+		for (i = 0; i < ubi->vtbl_slots; i++)
+			if (!ubi->volumes[i]) {
+				vol_id = i;
+				break;
+			}
+
+		if (vol_id == UBI_VOL_NUM_AUTO) {
+			ubi_err(ubi, "out of volume IDs");
+			err = -ENFILE;
+			goto out_unlock;
+		}
+		req->vol_id = vol_id;
+	}
+
+	dbg_gen("create device %d, volume %d, %llu bytes, type %d, name %s",
+		ubi->ubi_num, vol_id, (unsigned long long)req->bytes,
+		(int)req->vol_type, req->name);
+
+	/* Ensure that this volume does not exist */
+	err = -EEXIST;
+	if (ubi->volumes[vol_id]) {
+		ubi_err(ubi, "volume %d already exists", vol_id);
+		goto out_unlock;
+	}
+
+	/* Ensure that the name is unique */
+	for (i = 0; i < ubi->vtbl_slots; i++)
+		if (ubi->volumes[i] &&
+		    ubi->volumes[i]->name_len == req->name_len &&
+		    !strcmp(ubi->volumes[i]->name, req->name)) {
+			ubi_err(ubi, "volume \"%s\" exists (ID %d)",
+				req->name, i);
+			goto out_unlock;
+		}
+
+	/* Calculate how many eraseblocks are requested */
+	vol->usable_leb_size = ubi->leb_size - ubi->leb_size % req->alignment;
+	vol->reserved_pebs = div_u64(req->bytes + vol->usable_leb_size - 1,
+				     vol->usable_leb_size);
+
+	/* Reserve physical eraseblocks */
+	if (vol->reserved_pebs > ubi->avail_pebs) {
+		ubi_err(ubi, "not enough PEBs, only %d available",
+			ubi->avail_pebs);
+		if (ubi->corr_peb_count)
+			ubi_err(ubi, "%d PEBs are corrupted and not used",
+				ubi->corr_peb_count);
+		err = -ENOSPC;
+		goto out_unlock;
+	}
+	ubi->avail_pebs -= vol->reserved_pebs;
+	ubi->rsvd_pebs += vol->reserved_pebs;
+	spin_unlock(&ubi->volumes_lock);
+
+	vol->vol_id    = vol_id;
+	vol->alignment = req->alignment;
+	vol->data_pad  = ubi->leb_size % vol->alignment;
+	vol->vol_type  = req->vol_type;
+	vol->name_len  = req->name_len;
+	memcpy(vol->name, req->name, vol->name_len);
+	vol->ubi = ubi;
+
+	/*
+	 * Finish all pending erases because there may be some LEBs belonging
+	 * to the same volume ID.
+	 */
+	err = ubi_wl_flush(ubi, vol_id, UBI_ALL);
+	if (err)
+		goto out_acc;
+
+	eba_tbl = ubi_eba_create_table(vol, vol->reserved_pebs);
+	if (IS_ERR(eba_tbl)) {
+		err = PTR_ERR(eba_tbl);
+		goto out_acc;
+	}
+
+	ubi_eba_replace_table(vol, eba_tbl);
+
+	if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
+		vol->used_ebs = vol->reserved_pebs;
+		vol->last_eb_bytes = vol->usable_leb_size;
+		vol->used_bytes =
+			(long long)vol->used_ebs * vol->usable_leb_size;
+	} else {
+		vol->used_ebs = div_u64_rem(vol->used_bytes,
+					    vol->usable_leb_size,
+					    &vol->last_eb_bytes);
+		if (vol->last_eb_bytes != 0)
+			vol->used_ebs += 1;
+		else
+			vol->last_eb_bytes = vol->usable_leb_size;
+	}
+
+	/* Make volume "available" before it becomes accessible via sysfs */
+	spin_lock(&ubi->volumes_lock);
+	ubi->volumes[vol_id] = vol;
+	ubi->vol_count += 1;
+	spin_unlock(&ubi->volumes_lock);
+
+	/* Register character device for the volume */
+	cdev_init(&vol->cdev, &ubi_vol_cdev_operations);
+	vol->cdev.owner = THIS_MODULE;
+
+	vol->dev.devt = MKDEV(MAJOR(ubi->cdev.dev), vol_id + 1);
+	dev_set_name(&vol->dev, "%s_%d", ubi->ubi_name, vol->vol_id);
+	err = cdev_device_add(&vol->cdev, &vol->dev);
+	if (err) {
+		ubi_err(ubi, "cannot add device");
+		goto out_mapping;
+	}
+
+	/* Fill volume table record */
+	memset(&vtbl_rec, 0, sizeof(struct ubi_vtbl_record));
+	vtbl_rec.reserved_pebs = cpu_to_be32(vol->reserved_pebs);
+	vtbl_rec.alignment     = cpu_to_be32(vol->alignment);
+	vtbl_rec.data_pad      = cpu_to_be32(vol->data_pad);
+	vtbl_rec.name_len      = cpu_to_be16(vol->name_len);
+	if (vol->vol_type == UBI_DYNAMIC_VOLUME)
+		vtbl_rec.vol_type = UBI_VID_DYNAMIC;
+	else
+		vtbl_rec.vol_type = UBI_VID_STATIC;
+
+	if (vol->skip_check)
+		vtbl_rec.flags |= UBI_VTBL_SKIP_CRC_CHECK_FLG;
+
+	memcpy(vtbl_rec.name, vol->name, vol->name_len);
+
+	err = ubi_change_vtbl_record(ubi, vol_id, &vtbl_rec);
+	if (err)
+		goto out_sysfs;
+
+	ubi_volume_notify(ubi, vol, UBI_VOLUME_ADDED);
+	self_check_volumes(ubi);
+	return err;
+
+out_sysfs:
+	/*
+	 * We have registered our device, we should not free the volume
+	 * description object in this function in case of an error - it is
+	 * freed by the release function.
+	 */
+	cdev_device_del(&vol->cdev, &vol->dev);
+out_mapping:
+	spin_lock(&ubi->volumes_lock);
+	ubi->volumes[vol_id] = NULL;
+	ubi->vol_count -= 1;
+	spin_unlock(&ubi->volumes_lock);
+out_acc:
+	spin_lock(&ubi->volumes_lock);
+	ubi->rsvd_pebs -= vol->reserved_pebs;
+	ubi->avail_pebs += vol->reserved_pebs;
+out_unlock:
+	spin_unlock(&ubi->volumes_lock);
+	put_device(&vol->dev);
+	ubi_err(ubi, "cannot create volume %d, error %d", vol_id, err);
+	return err;
+}
+
+/**
+ * ubi_remove_volume - remove volume.
+ * @desc: volume descriptor
+ * @no_vtbl: do not change volume table if not zero
+ *
+ * This function removes volume described by @desc. The volume has to be opened
+ * in "exclusive" mode. Returns zero in case of success and a negative error
+ * code in case of failure. The caller has to have the @ubi->device_mutex
+ * locked.
+ */
+int ubi_remove_volume(struct ubi_volume_desc *desc, int no_vtbl)
+{
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+	int i, err, vol_id = vol->vol_id, reserved_pebs = vol->reserved_pebs;
+
+	dbg_gen("remove device %d, volume %d", ubi->ubi_num, vol_id);
+	ubi_assert(desc->mode == UBI_EXCLUSIVE);
+	ubi_assert(vol == ubi->volumes[vol_id]);
+
+	if (ubi->ro_mode)
+		return -EROFS;
+
+	spin_lock(&ubi->volumes_lock);
+	if (vol->ref_count > 1) {
+		/*
+		 * The volume is busy, probably someone is reading one of its
+		 * sysfs files.
+		 */
+		err = -EBUSY;
+		goto out_unlock;
+	}
+	ubi->volumes[vol_id] = NULL;
+	spin_unlock(&ubi->volumes_lock);
+
+	if (!no_vtbl) {
+		err = ubi_change_vtbl_record(ubi, vol_id, NULL);
+		if (err)
+			goto out_err;
+	}
+
+	for (i = 0; i < vol->reserved_pebs; i++) {
+		err = ubi_eba_unmap_leb(ubi, vol, i);
+		if (err)
+			goto out_err;
+	}
+
+	cdev_device_del(&vol->cdev, &vol->dev);
+	put_device(&vol->dev);
+
+	spin_lock(&ubi->volumes_lock);
+	ubi->rsvd_pebs -= reserved_pebs;
+	ubi->avail_pebs += reserved_pebs;
+	ubi_update_reserved(ubi);
+	ubi->vol_count -= 1;
+	spin_unlock(&ubi->volumes_lock);
+
+	ubi_volume_notify(ubi, vol, UBI_VOLUME_REMOVED);
+	if (!no_vtbl)
+		self_check_volumes(ubi);
+
+	return 0;
+
+out_err:
+	ubi_err(ubi, "cannot remove volume %d, error %d", vol_id, err);
+	spin_lock(&ubi->volumes_lock);
+	ubi->volumes[vol_id] = vol;
+out_unlock:
+	spin_unlock(&ubi->volumes_lock);
+	return err;
+}
+
+/**
+ * ubi_resize_volume - re-size volume.
+ * @desc: volume descriptor
+ * @reserved_pebs: new size in physical eraseblocks
+ *
+ * This function re-sizes the volume and returns zero in case of success, and a
+ * negative error code in case of failure. The caller has to have the
+ * @ubi->device_mutex locked.
+ */
+int ubi_resize_volume(struct ubi_volume_desc *desc, int reserved_pebs)
+{
+	int i, err, pebs;
+	struct ubi_volume *vol = desc->vol;
+	struct ubi_device *ubi = vol->ubi;
+	struct ubi_vtbl_record vtbl_rec;
+	struct ubi_eba_table *new_eba_tbl = NULL;
+	int vol_id = vol->vol_id;
+
+	if (ubi->ro_mode)
+		return -EROFS;
+
+	dbg_gen("re-size device %d, volume %d to from %d to %d PEBs",
+		ubi->ubi_num, vol_id, vol->reserved_pebs, reserved_pebs);
+
+	if (vol->vol_type == UBI_STATIC_VOLUME &&
+	    reserved_pebs < vol->used_ebs) {
+		ubi_err(ubi, "too small size %d, %d LEBs contain data",
+			reserved_pebs, vol->used_ebs);
+		return -EINVAL;
+	}
+
+	/* If the size is the same, we have nothing to do */
+	if (reserved_pebs == vol->reserved_pebs)
+		return 0;
+
+	new_eba_tbl = ubi_eba_create_table(vol, reserved_pebs);
+	if (IS_ERR(new_eba_tbl))
+		return PTR_ERR(new_eba_tbl);
+
+	spin_lock(&ubi->volumes_lock);
+	if (vol->ref_count > 1) {
+		spin_unlock(&ubi->volumes_lock);
+		err = -EBUSY;
+		goto out_free;
+	}
+	spin_unlock(&ubi->volumes_lock);
+
+	/* Reserve physical eraseblocks */
+	pebs = reserved_pebs - vol->reserved_pebs;
+	if (pebs > 0) {
+		spin_lock(&ubi->volumes_lock);
+		if (pebs > ubi->avail_pebs) {
+			ubi_err(ubi, "not enough PEBs: requested %d, available %d",
+				pebs, ubi->avail_pebs);
+			if (ubi->corr_peb_count)
+				ubi_err(ubi, "%d PEBs are corrupted and not used",
+					ubi->corr_peb_count);
+			spin_unlock(&ubi->volumes_lock);
+			err = -ENOSPC;
+			goto out_free;
+		}
+		ubi->avail_pebs -= pebs;
+		ubi->rsvd_pebs += pebs;
+		ubi_eba_copy_table(vol, new_eba_tbl, vol->reserved_pebs);
+		ubi_eba_replace_table(vol, new_eba_tbl);
+		spin_unlock(&ubi->volumes_lock);
+	}
+
+	if (pebs < 0) {
+		for (i = 0; i < -pebs; i++) {
+			err = ubi_eba_unmap_leb(ubi, vol, reserved_pebs + i);
+			if (err)
+				goto out_free;
+		}
+		spin_lock(&ubi->volumes_lock);
+		ubi->rsvd_pebs += pebs;
+		ubi->avail_pebs -= pebs;
+		ubi_update_reserved(ubi);
+		ubi_eba_copy_table(vol, new_eba_tbl, reserved_pebs);
+		ubi_eba_replace_table(vol, new_eba_tbl);
+		spin_unlock(&ubi->volumes_lock);
+	}
+
+	/*
+	 * When we shrink a volume we have to flush all pending (erase) work.
+	 * Otherwise it can happen that upon next attach UBI finds a LEB with
+	 * lnum > highest_lnum and refuses to attach.
+	 */
+	if (pebs < 0) {
+		err = ubi_wl_flush(ubi, vol_id, UBI_ALL);
+		if (err)
+			goto out_acc;
+	}
+
+	/* Change volume table record */
+	vtbl_rec = ubi->vtbl[vol_id];
+	vtbl_rec.reserved_pebs = cpu_to_be32(reserved_pebs);
+	err = ubi_change_vtbl_record(ubi, vol_id, &vtbl_rec);
+	if (err)
+		goto out_acc;
+
+	vol->reserved_pebs = reserved_pebs;
+	if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
+		vol->used_ebs = reserved_pebs;
+		vol->last_eb_bytes = vol->usable_leb_size;
+		vol->used_bytes =
+			(long long)vol->used_ebs * vol->usable_leb_size;
+	}
+
+	ubi_volume_notify(ubi, vol, UBI_VOLUME_RESIZED);
+	self_check_volumes(ubi);
+	return err;
+
+out_acc:
+	if (pebs > 0) {
+		spin_lock(&ubi->volumes_lock);
+		ubi->rsvd_pebs -= pebs;
+		ubi->avail_pebs += pebs;
+		spin_unlock(&ubi->volumes_lock);
+	}
+	return err;
+
+out_free:
+	ubi_eba_destroy_table(new_eba_tbl);
+	return err;
+}
+
+/**
+ * ubi_rename_volumes - re-name UBI volumes.
+ * @ubi: UBI device description object
+ * @rename_list: list of &struct ubi_rename_entry objects
+ *
+ * This function re-names or removes volumes specified in the re-name list.
+ * Returns zero in case of success and a negative error code in case of
+ * failure.
+ */
+int ubi_rename_volumes(struct ubi_device *ubi, struct list_head *rename_list)
+{
+	int err;
+	struct ubi_rename_entry *re;
+
+	err = ubi_vtbl_rename_volumes(ubi, rename_list);
+	if (err)
+		return err;
+
+	list_for_each_entry(re, rename_list, list) {
+		if (re->remove) {
+			err = ubi_remove_volume(re->desc, 1);
+			if (err)
+				break;
+		} else {
+			struct ubi_volume *vol = re->desc->vol;
+
+			spin_lock(&ubi->volumes_lock);
+			vol->name_len = re->new_name_len;
+			memcpy(vol->name, re->new_name, re->new_name_len + 1);
+			spin_unlock(&ubi->volumes_lock);
+			ubi_volume_notify(ubi, vol, UBI_VOLUME_RENAMED);
+		}
+	}
+
+	if (!err)
+		self_check_volumes(ubi);
+	return err;
+}
+
+/**
+ * ubi_add_volume - add volume.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ *
+ * This function adds an existing volume and initializes all its data
+ * structures. Returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+int ubi_add_volume(struct ubi_device *ubi, struct ubi_volume *vol)
+{
+	int err, vol_id = vol->vol_id;
+	dev_t dev;
+
+	dbg_gen("add volume %d", vol_id);
+
+	/* Register character device for the volume */
+	cdev_init(&vol->cdev, &ubi_vol_cdev_operations);
+	vol->cdev.owner = THIS_MODULE;
+	dev = MKDEV(MAJOR(ubi->cdev.dev), vol->vol_id + 1);
+	err = cdev_add(&vol->cdev, dev, 1);
+	if (err) {
+		ubi_err(ubi, "cannot add character device for volume %d, error %d",
+			vol_id, err);
+		vol_release(&vol->dev);
+		return err;
+	}
+
+	vol->dev.release = vol_release;
+	vol->dev.parent = &ubi->dev;
+	vol->dev.devt = dev;
+	vol->dev.class = &ubi_class;
+	vol->dev.groups = volume_dev_groups;
+	dev_set_name(&vol->dev, "%s_%d", ubi->ubi_name, vol->vol_id);
+	err = device_register(&vol->dev);
+	if (err) {
+		cdev_del(&vol->cdev);
+		put_device(&vol->dev);
+		return err;
+	}
+
+	self_check_volumes(ubi);
+	return err;
+}
+
+/**
+ * ubi_free_volume - free volume.
+ * @ubi: UBI device description object
+ * @vol: volume description object
+ *
+ * This function frees all resources for volume @vol but does not remove it.
+ * Used only when the UBI device is detached.
+ */
+void ubi_free_volume(struct ubi_device *ubi, struct ubi_volume *vol)
+{
+	dbg_gen("free volume %d", vol->vol_id);
+
+	ubi->volumes[vol->vol_id] = NULL;
+	cdev_del(&vol->cdev);
+	device_unregister(&vol->dev);
+}
+
+/**
+ * self_check_volume - check volume information.
+ * @ubi: UBI device description object
+ * @vol_id: volume ID
+ *
+ * Returns zero if volume is all right and a negative error code if not.
+ */
+static int self_check_volume(struct ubi_device *ubi, int vol_id)
+{
+	int idx = vol_id2idx(ubi, vol_id);
+	int reserved_pebs, alignment, data_pad, vol_type, name_len, upd_marker;
+	const struct ubi_volume *vol;
+	long long n;
+	const char *name;
+
+	spin_lock(&ubi->volumes_lock);
+	reserved_pebs = be32_to_cpu(ubi->vtbl[vol_id].reserved_pebs);
+	vol = ubi->volumes[idx];
+
+	if (!vol) {
+		if (reserved_pebs) {
+			ubi_err(ubi, "no volume info, but volume exists");
+			goto fail;
+		}
+		spin_unlock(&ubi->volumes_lock);
+		return 0;
+	}
+
+	if (vol->reserved_pebs < 0 || vol->alignment < 0 || vol->data_pad < 0 ||
+	    vol->name_len < 0) {
+		ubi_err(ubi, "negative values");
+		goto fail;
+	}
+	if (vol->alignment > ubi->leb_size || vol->alignment == 0) {
+		ubi_err(ubi, "bad alignment");
+		goto fail;
+	}
+
+	n = vol->alignment & (ubi->min_io_size - 1);
+	if (vol->alignment != 1 && n) {
+		ubi_err(ubi, "alignment is not multiple of min I/O unit");
+		goto fail;
+	}
+
+	n = ubi->leb_size % vol->alignment;
+	if (vol->data_pad != n) {
+		ubi_err(ubi, "bad data_pad, has to be %lld", n);
+		goto fail;
+	}
+
+	if (vol->vol_type != UBI_DYNAMIC_VOLUME &&
+	    vol->vol_type != UBI_STATIC_VOLUME) {
+		ubi_err(ubi, "bad vol_type");
+		goto fail;
+	}
+
+	if (vol->upd_marker && vol->corrupted) {
+		ubi_err(ubi, "update marker and corrupted simultaneously");
+		goto fail;
+	}
+
+	if (vol->reserved_pebs > ubi->good_peb_count) {
+		ubi_err(ubi, "too large reserved_pebs");
+		goto fail;
+	}
+
+	n = ubi->leb_size - vol->data_pad;
+	if (vol->usable_leb_size != ubi->leb_size - vol->data_pad) {
+		ubi_err(ubi, "bad usable_leb_size, has to be %lld", n);
+		goto fail;
+	}
+
+	if (vol->name_len > UBI_VOL_NAME_MAX) {
+		ubi_err(ubi, "too long volume name, max is %d",
+			UBI_VOL_NAME_MAX);
+		goto fail;
+	}
+
+	n = strnlen(vol->name, vol->name_len + 1);
+	if (n != vol->name_len) {
+		ubi_err(ubi, "bad name_len %lld", n);
+		goto fail;
+	}
+
+	n = (long long)vol->used_ebs * vol->usable_leb_size;
+	if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
+		if (vol->corrupted) {
+			ubi_err(ubi, "corrupted dynamic volume");
+			goto fail;
+		}
+		if (vol->used_ebs != vol->reserved_pebs) {
+			ubi_err(ubi, "bad used_ebs");
+			goto fail;
+		}
+		if (vol->last_eb_bytes != vol->usable_leb_size) {
+			ubi_err(ubi, "bad last_eb_bytes");
+			goto fail;
+		}
+		if (vol->used_bytes != n) {
+			ubi_err(ubi, "bad used_bytes");
+			goto fail;
+		}
+
+		if (vol->skip_check) {
+			ubi_err(ubi, "bad skip_check");
+			goto fail;
+		}
+	} else {
+		if (vol->used_ebs < 0 || vol->used_ebs > vol->reserved_pebs) {
+			ubi_err(ubi, "bad used_ebs");
+			goto fail;
+		}
+		if (vol->last_eb_bytes < 0 ||
+		    vol->last_eb_bytes > vol->usable_leb_size) {
+			ubi_err(ubi, "bad last_eb_bytes");
+			goto fail;
+		}
+		if (vol->used_bytes < 0 || vol->used_bytes > n ||
+		    vol->used_bytes < n - vol->usable_leb_size) {
+			ubi_err(ubi, "bad used_bytes");
+			goto fail;
+		}
+	}
+
+	alignment  = be32_to_cpu(ubi->vtbl[vol_id].alignment);
+	data_pad   = be32_to_cpu(ubi->vtbl[vol_id].data_pad);
+	name_len   = be16_to_cpu(ubi->vtbl[vol_id].name_len);
+	upd_marker = ubi->vtbl[vol_id].upd_marker;
+	name       = &ubi->vtbl[vol_id].name[0];
+	if (ubi->vtbl[vol_id].vol_type == UBI_VID_DYNAMIC)
+		vol_type = UBI_DYNAMIC_VOLUME;
+	else
+		vol_type = UBI_STATIC_VOLUME;
+
+	if (alignment != vol->alignment || data_pad != vol->data_pad ||
+	    upd_marker != vol->upd_marker || vol_type != vol->vol_type ||
+	    name_len != vol->name_len || strncmp(name, vol->name, name_len)) {
+		ubi_err(ubi, "volume info is different");
+		goto fail;
+	}
+
+	spin_unlock(&ubi->volumes_lock);
+	return 0;
+
+fail:
+	ubi_err(ubi, "self-check failed for volume %d", vol_id);
+	if (vol)
+		ubi_dump_vol_info(vol);
+	ubi_dump_vtbl_record(&ubi->vtbl[vol_id], vol_id);
+	dump_stack();
+	spin_unlock(&ubi->volumes_lock);
+	return -EINVAL;
+}
+
+/**
+ * self_check_volumes - check information about all volumes.
+ * @ubi: UBI device description object
+ *
+ * Returns zero if volumes are all right and a negative error code if not.
+ */
+static int self_check_volumes(struct ubi_device *ubi)
+{
+	int i, err = 0;
+
+	if (!ubi_dbg_chk_gen(ubi))
+		return 0;
+
+	for (i = 0; i < ubi->vtbl_slots; i++) {
+		err = self_check_volume(ubi, i);
+		if (err)
+			break;
+	}
+
+	return err;
+}
diff --git a/drivers/mtd/ubi/vtbl.c b/drivers/mtd/ubi/vtbl.c
new file mode 100644
index 0000000000..f700f0e4f2
--- /dev/null
+++ b/drivers/mtd/ubi/vtbl.c
@@ -0,0 +1,871 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ * Copyright (c) Nokia Corporation, 2006, 2007
+ *
+ * Author: Artem Bityutskiy (Битюцкий Артём)
+ */
+
+/*
+ * This file includes volume table manipulation code. The volume table is an
+ * on-flash table containing volume meta-data like name, number of reserved
+ * physical eraseblocks, type, etc. The volume table is stored in the so-called
+ * "layout volume".
+ *
+ * The layout volume is an internal volume which is organized as follows. It
+ * consists of two logical eraseblocks - LEB 0 and LEB 1. Each logical
+ * eraseblock stores one volume table copy, i.e. LEB 0 and LEB 1 duplicate each
+ * other. This redundancy guarantees robustness to unclean reboots. The volume
+ * table is basically an array of volume table records. Each record contains
+ * full information about the volume and protected by a CRC checksum. Note,
+ * nowadays we use the atomic LEB change operation when updating the volume
+ * table, so we do not really need 2 LEBs anymore, but we preserve the older
+ * design for the backward compatibility reasons.
+ *
+ * When the volume table is changed, it is first changed in RAM. Then LEB 0 is
+ * erased, and the updated volume table is written back to LEB 0. Then same for
+ * LEB 1. This scheme guarantees recoverability from unclean reboots.
+ *
+ * In this UBI implementation the on-flash volume table does not contain any
+ * information about how much data static volumes contain.
+ *
+ * But it would still be beneficial to store this information in the volume
+ * table. For example, suppose we have a static volume X, and all its physical
+ * eraseblocks became bad for some reasons. Suppose we are attaching the
+ * corresponding MTD device, for some reason we find no logical eraseblocks
+ * corresponding to the volume X. According to the volume table volume X does
+ * exist. So we don't know whether it is just empty or all its physical
+ * eraseblocks went bad. So we cannot alarm the user properly.
+ *
+ * The volume table also stores so-called "update marker", which is used for
+ * volume updates. Before updating the volume, the update marker is set, and
+ * after the update operation is finished, the update marker is cleared. So if
+ * the update operation was interrupted (e.g. by an unclean reboot) - the
+ * update marker is still there and we know that the volume's contents is
+ * damaged.
+ */
+
+#include <linux/crc32.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <asm/div64.h>
+#include "ubi.h"
+
+static void self_vtbl_check(const struct ubi_device *ubi);
+
+/* Empty volume table record */
+static struct ubi_vtbl_record empty_vtbl_record;
+
+/**
+ * ubi_update_layout_vol - helper for updatting layout volumes on flash
+ * @ubi: UBI device description object
+ */
+static int ubi_update_layout_vol(struct ubi_device *ubi)
+{
+	struct ubi_volume *layout_vol;
+	int i, err;
+
+	layout_vol = ubi->volumes[vol_id2idx(ubi, UBI_LAYOUT_VOLUME_ID)];
+	for (i = 0; i < UBI_LAYOUT_VOLUME_EBS; i++) {
+		err = ubi_eba_atomic_leb_change(ubi, layout_vol, i, ubi->vtbl,
+						ubi->vtbl_size);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+/**
+ * ubi_change_vtbl_record - change volume table record.
+ * @ubi: UBI device description object
+ * @idx: table index to change
+ * @vtbl_rec: new volume table record
+ *
+ * This function changes volume table record @idx. If @vtbl_rec is %NULL, empty
+ * volume table record is written. The caller does not have to calculate CRC of
+ * the record as it is done by this function. Returns zero in case of success
+ * and a negative error code in case of failure.
+ */
+int ubi_change_vtbl_record(struct ubi_device *ubi, int idx,
+			   struct ubi_vtbl_record *vtbl_rec)
+{
+	int err;
+	uint32_t crc;
+
+	ubi_assert(idx >= 0 && idx < ubi->vtbl_slots);
+
+	if (!vtbl_rec)
+		vtbl_rec = &empty_vtbl_record;
+	else {
+		crc = crc32(UBI_CRC32_INIT, vtbl_rec, UBI_VTBL_RECORD_SIZE_CRC);
+		vtbl_rec->crc = cpu_to_be32(crc);
+	}
+
+	memcpy(&ubi->vtbl[idx], vtbl_rec, sizeof(struct ubi_vtbl_record));
+	err = ubi_update_layout_vol(ubi);
+
+	self_vtbl_check(ubi);
+	return err ? err : 0;
+}
+
+/**
+ * ubi_vtbl_rename_volumes - rename UBI volumes in the volume table.
+ * @ubi: UBI device description object
+ * @rename_list: list of &struct ubi_rename_entry objects
+ *
+ * This function re-names multiple volumes specified in @req in the volume
+ * table. Returns zero in case of success and a negative error code in case of
+ * failure.
+ */
+int ubi_vtbl_rename_volumes(struct ubi_device *ubi,
+			    struct list_head *rename_list)
+{
+	struct ubi_rename_entry *re;
+
+	list_for_each_entry(re, rename_list, list) {
+		uint32_t crc;
+		struct ubi_volume *vol = re->desc->vol;
+		struct ubi_vtbl_record *vtbl_rec = &ubi->vtbl[vol->vol_id];
+
+		if (re->remove) {
+			memcpy(vtbl_rec, &empty_vtbl_record,
+			       sizeof(struct ubi_vtbl_record));
+			continue;
+		}
+
+		vtbl_rec->name_len = cpu_to_be16(re->new_name_len);
+		memcpy(vtbl_rec->name, re->new_name, re->new_name_len);
+		memset(vtbl_rec->name + re->new_name_len, 0,
+		       UBI_VOL_NAME_MAX + 1 - re->new_name_len);
+		crc = crc32(UBI_CRC32_INIT, vtbl_rec,
+			    UBI_VTBL_RECORD_SIZE_CRC);
+		vtbl_rec->crc = cpu_to_be32(crc);
+	}
+
+	return ubi_update_layout_vol(ubi);
+}
+
+/**
+ * vtbl_check - check if volume table is not corrupted and sensible.
+ * @ubi: UBI device description object
+ * @vtbl: volume table
+ *
+ * This function returns zero if @vtbl is all right, %1 if CRC is incorrect,
+ * and %-EINVAL if it contains inconsistent data.
+ */
+static int vtbl_check(const struct ubi_device *ubi,
+		      const struct ubi_vtbl_record *vtbl)
+{
+	int i, n, reserved_pebs, alignment, data_pad, vol_type, name_len;
+	int upd_marker, err;
+	uint32_t crc;
+	const char *name;
+
+	for (i = 0; i < ubi->vtbl_slots; i++) {
+		cond_resched();
+
+		reserved_pebs = be32_to_cpu(vtbl[i].reserved_pebs);
+		alignment = be32_to_cpu(vtbl[i].alignment);
+		data_pad = be32_to_cpu(vtbl[i].data_pad);
+		upd_marker = vtbl[i].upd_marker;
+		vol_type = vtbl[i].vol_type;
+		name_len = be16_to_cpu(vtbl[i].name_len);
+		name = &vtbl[i].name[0];
+
+		crc = crc32(UBI_CRC32_INIT, &vtbl[i], UBI_VTBL_RECORD_SIZE_CRC);
+		if (be32_to_cpu(vtbl[i].crc) != crc) {
+			ubi_err(ubi, "bad CRC at record %u: %#08x, not %#08x",
+				 i, crc, be32_to_cpu(vtbl[i].crc));
+			ubi_dump_vtbl_record(&vtbl[i], i);
+			return 1;
+		}
+
+		if (reserved_pebs == 0) {
+			if (memcmp(&vtbl[i], &empty_vtbl_record,
+						UBI_VTBL_RECORD_SIZE)) {
+				err = 2;
+				goto bad;
+			}
+			continue;
+		}
+
+		if (reserved_pebs < 0 || alignment < 0 || data_pad < 0 ||
+		    name_len < 0) {
+			err = 3;
+			goto bad;
+		}
+
+		if (alignment > ubi->leb_size || alignment == 0) {
+			err = 4;
+			goto bad;
+		}
+
+		n = alignment & (ubi->min_io_size - 1);
+		if (alignment != 1 && n) {
+			err = 5;
+			goto bad;
+		}
+
+		n = ubi->leb_size % alignment;
+		if (data_pad != n) {
+			ubi_err(ubi, "bad data_pad, has to be %d", n);
+			err = 6;
+			goto bad;
+		}
+
+		if (vol_type != UBI_VID_DYNAMIC && vol_type != UBI_VID_STATIC) {
+			err = 7;
+			goto bad;
+		}
+
+		if (upd_marker != 0 && upd_marker != 1) {
+			err = 8;
+			goto bad;
+		}
+
+		if (reserved_pebs > ubi->good_peb_count) {
+			ubi_err(ubi, "too large reserved_pebs %d, good PEBs %d",
+				reserved_pebs, ubi->good_peb_count);
+			err = 9;
+			goto bad;
+		}
+
+		if (name_len > UBI_VOL_NAME_MAX) {
+			err = 10;
+			goto bad;
+		}
+
+		if (name[0] == '\0') {
+			err = 11;
+			goto bad;
+		}
+
+		if (name_len != strnlen(name, name_len + 1)) {
+			err = 12;
+			goto bad;
+		}
+	}
+
+	/* Checks that all names are unique */
+	for (i = 0; i < ubi->vtbl_slots - 1; i++) {
+		for (n = i + 1; n < ubi->vtbl_slots; n++) {
+			int len1 = be16_to_cpu(vtbl[i].name_len);
+			int len2 = be16_to_cpu(vtbl[n].name_len);
+
+			if (len1 > 0 && len1 == len2 &&
+			    !strncmp(vtbl[i].name, vtbl[n].name, len1)) {
+				ubi_err(ubi, "volumes %d and %d have the same name \"%s\"",
+					i, n, vtbl[i].name);
+				ubi_dump_vtbl_record(&vtbl[i], i);
+				ubi_dump_vtbl_record(&vtbl[n], n);
+				return -EINVAL;
+			}
+		}
+	}
+
+	return 0;
+
+bad:
+	ubi_err(ubi, "volume table check failed: record %d, error %d", i, err);
+	ubi_dump_vtbl_record(&vtbl[i], i);
+	return -EINVAL;
+}
+
+/**
+ * create_vtbl - create a copy of volume table.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ * @copy: number of the volume table copy
+ * @vtbl: contents of the volume table
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int create_vtbl(struct ubi_device *ubi, struct ubi_attach_info *ai,
+		       int copy, void *vtbl)
+{
+	int err, tries = 0;
+	struct ubi_vid_io_buf *vidb;
+	struct ubi_vid_hdr *vid_hdr;
+	struct ubi_ainf_peb *new_aeb;
+
+	dbg_gen("create volume table (copy #%d)", copy + 1);
+
+	vidb = ubi_alloc_vid_buf(ubi, GFP_KERNEL);
+	if (!vidb)
+		return -ENOMEM;
+
+	vid_hdr = ubi_get_vid_hdr(vidb);
+
+retry:
+	new_aeb = ubi_early_get_peb(ubi, ai);
+	if (IS_ERR(new_aeb)) {
+		err = PTR_ERR(new_aeb);
+		goto out_free;
+	}
+
+	vid_hdr->vol_type = UBI_LAYOUT_VOLUME_TYPE;
+	vid_hdr->vol_id = cpu_to_be32(UBI_LAYOUT_VOLUME_ID);
+	vid_hdr->compat = UBI_LAYOUT_VOLUME_COMPAT;
+	vid_hdr->data_size = vid_hdr->used_ebs =
+			     vid_hdr->data_pad = cpu_to_be32(0);
+	vid_hdr->lnum = cpu_to_be32(copy);
+	vid_hdr->sqnum = cpu_to_be64(++ai->max_sqnum);
+
+	/* The EC header is already there, write the VID header */
+	err = ubi_io_write_vid_hdr(ubi, new_aeb->pnum, vidb);
+	if (err)
+		goto write_error;
+
+	/* Write the layout volume contents */
+	err = ubi_io_write_data(ubi, vtbl, new_aeb->pnum, 0, ubi->vtbl_size);
+	if (err)
+		goto write_error;
+
+	/*
+	 * And add it to the attaching information. Don't delete the old version
+	 * of this LEB as it will be deleted and freed in 'ubi_add_to_av()'.
+	 */
+	err = ubi_add_to_av(ubi, ai, new_aeb->pnum, new_aeb->ec, vid_hdr, 0);
+	ubi_free_aeb(ai, new_aeb);
+	ubi_free_vid_buf(vidb);
+	return err;
+
+write_error:
+	if (err == -EIO && ++tries <= 5) {
+		/*
+		 * Probably this physical eraseblock went bad, try to pick
+		 * another one.
+		 */
+		list_add(&new_aeb->u.list, &ai->erase);
+		goto retry;
+	}
+	ubi_free_aeb(ai, new_aeb);
+out_free:
+	ubi_free_vid_buf(vidb);
+	return err;
+
+}
+
+/**
+ * process_lvol - process the layout volume.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ * @av: layout volume attaching information
+ *
+ * This function is responsible for reading the layout volume, ensuring it is
+ * not corrupted, and recovering from corruptions if needed. Returns volume
+ * table in case of success and a negative error code in case of failure.
+ */
+static struct ubi_vtbl_record *process_lvol(struct ubi_device *ubi,
+					    struct ubi_attach_info *ai,
+					    struct ubi_ainf_volume *av)
+{
+	int err;
+	struct rb_node *rb;
+	struct ubi_ainf_peb *aeb;
+	struct ubi_vtbl_record *leb[UBI_LAYOUT_VOLUME_EBS] = { NULL, NULL };
+	int leb_corrupted[UBI_LAYOUT_VOLUME_EBS] = {1, 1};
+
+	/*
+	 * UBI goes through the following steps when it changes the layout
+	 * volume:
+	 * a. erase LEB 0;
+	 * b. write new data to LEB 0;
+	 * c. erase LEB 1;
+	 * d. write new data to LEB 1.
+	 *
+	 * Before the change, both LEBs contain the same data.
+	 *
+	 * Due to unclean reboots, the contents of LEB 0 may be lost, but there
+	 * should LEB 1. So it is OK if LEB 0 is corrupted while LEB 1 is not.
+	 * Similarly, LEB 1 may be lost, but there should be LEB 0. And
+	 * finally, unclean reboots may result in a situation when neither LEB
+	 * 0 nor LEB 1 are corrupted, but they are different. In this case, LEB
+	 * 0 contains more recent information.
+	 *
+	 * So the plan is to first check LEB 0. Then
+	 * a. if LEB 0 is OK, it must be containing the most recent data; then
+	 *    we compare it with LEB 1, and if they are different, we copy LEB
+	 *    0 to LEB 1;
+	 * b. if LEB 0 is corrupted, but LEB 1 has to be OK, and we copy LEB 1
+	 *    to LEB 0.
+	 */
+
+	dbg_gen("check layout volume");
+
+	/* Read both LEB 0 and LEB 1 into memory */
+	ubi_rb_for_each_entry(rb, aeb, &av->root, u.rb) {
+		leb[aeb->lnum] = vzalloc(ubi->vtbl_size);
+		if (!leb[aeb->lnum]) {
+			err = -ENOMEM;
+			goto out_free;
+		}
+
+		err = ubi_io_read_data(ubi, leb[aeb->lnum], aeb->pnum, 0,
+				       ubi->vtbl_size);
+		if (err == UBI_IO_BITFLIPS || mtd_is_eccerr(err))
+			/*
+			 * Scrub the PEB later. Note, -EBADMSG indicates an
+			 * uncorrectable ECC error, but we have our own CRC and
+			 * the data will be checked later. If the data is OK,
+			 * the PEB will be scrubbed (because we set
+			 * aeb->scrub). If the data is not OK, the contents of
+			 * the PEB will be recovered from the second copy, and
+			 * aeb->scrub will be cleared in
+			 * 'ubi_add_to_av()'.
+			 */
+			aeb->scrub = 1;
+		else if (err)
+			goto out_free;
+	}
+
+	err = -EINVAL;
+	if (leb[0]) {
+		leb_corrupted[0] = vtbl_check(ubi, leb[0]);
+		if (leb_corrupted[0] < 0)
+			goto out_free;
+	}
+
+	if (!leb_corrupted[0]) {
+		/* LEB 0 is OK */
+		if (leb[1])
+			leb_corrupted[1] = memcmp(leb[0], leb[1],
+						  ubi->vtbl_size);
+		if (leb_corrupted[1]) {
+			ubi_warn(ubi, "volume table copy #2 is corrupted");
+			err = create_vtbl(ubi, ai, 1, leb[0]);
+			if (err)
+				goto out_free;
+			ubi_msg(ubi, "volume table was restored");
+		}
+
+		/* Both LEB 1 and LEB 2 are OK and consistent */
+		vfree(leb[1]);
+		return leb[0];
+	} else {
+		/* LEB 0 is corrupted or does not exist */
+		if (leb[1]) {
+			leb_corrupted[1] = vtbl_check(ubi, leb[1]);
+			if (leb_corrupted[1] < 0)
+				goto out_free;
+		}
+		if (leb_corrupted[1]) {
+			/* Both LEB 0 and LEB 1 are corrupted */
+			ubi_err(ubi, "both volume tables are corrupted");
+			goto out_free;
+		}
+
+		ubi_warn(ubi, "volume table copy #1 is corrupted");
+		err = create_vtbl(ubi, ai, 0, leb[1]);
+		if (err)
+			goto out_free;
+		ubi_msg(ubi, "volume table was restored");
+
+		vfree(leb[0]);
+		return leb[1];
+	}
+
+out_free:
+	vfree(leb[0]);
+	vfree(leb[1]);
+	return ERR_PTR(err);
+}
+
+/**
+ * create_empty_lvol - create empty layout volume.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ *
+ * This function returns volume table contents in case of success and a
+ * negative error code in case of failure.
+ */
+static struct ubi_vtbl_record *create_empty_lvol(struct ubi_device *ubi,
+						 struct ubi_attach_info *ai)
+{
+	int i;
+	struct ubi_vtbl_record *vtbl;
+
+	vtbl = vzalloc(ubi->vtbl_size);
+	if (!vtbl)
+		return ERR_PTR(-ENOMEM);
+
+	for (i = 0; i < ubi->vtbl_slots; i++)
+		memcpy(&vtbl[i], &empty_vtbl_record, UBI_VTBL_RECORD_SIZE);
+
+	for (i = 0; i < UBI_LAYOUT_VOLUME_EBS; i++) {
+		int err;
+
+		err = create_vtbl(ubi, ai, i, vtbl);
+		if (err) {
+			vfree(vtbl);
+			return ERR_PTR(err);
+		}
+	}
+
+	return vtbl;
+}
+
+/**
+ * init_volumes - initialize volume information for existing volumes.
+ * @ubi: UBI device description object
+ * @ai: scanning information
+ * @vtbl: volume table
+ *
+ * This function allocates volume description objects for existing volumes.
+ * Returns zero in case of success and a negative error code in case of
+ * failure.
+ */
+static int init_volumes(struct ubi_device *ubi,
+			const struct ubi_attach_info *ai,
+			const struct ubi_vtbl_record *vtbl)
+{
+	int i, err, reserved_pebs = 0;
+	struct ubi_ainf_volume *av;
+	struct ubi_volume *vol;
+
+	for (i = 0; i < ubi->vtbl_slots; i++) {
+		cond_resched();
+
+		if (be32_to_cpu(vtbl[i].reserved_pebs) == 0)
+			continue; /* Empty record */
+
+		vol = kzalloc(sizeof(struct ubi_volume), GFP_KERNEL);
+		if (!vol)
+			return -ENOMEM;
+
+		vol->reserved_pebs = be32_to_cpu(vtbl[i].reserved_pebs);
+		vol->alignment = be32_to_cpu(vtbl[i].alignment);
+		vol->data_pad = be32_to_cpu(vtbl[i].data_pad);
+		vol->upd_marker = vtbl[i].upd_marker;
+		vol->vol_type = vtbl[i].vol_type == UBI_VID_DYNAMIC ?
+					UBI_DYNAMIC_VOLUME : UBI_STATIC_VOLUME;
+		vol->name_len = be16_to_cpu(vtbl[i].name_len);
+		vol->usable_leb_size = ubi->leb_size - vol->data_pad;
+		memcpy(vol->name, vtbl[i].name, vol->name_len);
+		vol->name[vol->name_len] = '\0';
+		vol->vol_id = i;
+
+		if (vtbl[i].flags & UBI_VTBL_SKIP_CRC_CHECK_FLG)
+			vol->skip_check = 1;
+
+		if (vtbl[i].flags & UBI_VTBL_AUTORESIZE_FLG) {
+			/* Auto re-size flag may be set only for one volume */
+			if (ubi->autoresize_vol_id != -1) {
+				ubi_err(ubi, "more than one auto-resize volume (%d and %d)",
+					ubi->autoresize_vol_id, i);
+				kfree(vol);
+				return -EINVAL;
+			}
+
+			ubi->autoresize_vol_id = i;
+		}
+
+		ubi_assert(!ubi->volumes[i]);
+		ubi->volumes[i] = vol;
+		ubi->vol_count += 1;
+		vol->ubi = ubi;
+		reserved_pebs += vol->reserved_pebs;
+
+		/*
+		 * We use ubi->peb_count and not vol->reserved_pebs because
+		 * we want to keep the code simple. Otherwise we'd have to
+		 * resize/check the bitmap upon volume resize too.
+		 * Allocating a few bytes more does not hurt.
+		 */
+		err = ubi_fastmap_init_checkmap(vol, ubi->peb_count);
+		if (err)
+			return err;
+
+		/*
+		 * In case of dynamic volume UBI knows nothing about how many
+		 * data is stored there. So assume the whole volume is used.
+		 */
+		if (vol->vol_type == UBI_DYNAMIC_VOLUME) {
+			vol->used_ebs = vol->reserved_pebs;
+			vol->last_eb_bytes = vol->usable_leb_size;
+			vol->used_bytes =
+				(long long)vol->used_ebs * vol->usable_leb_size;
+			continue;
+		}
+
+		/* Static volumes only */
+		av = ubi_find_av(ai, i);
+		if (!av || !av->leb_count) {
+			/*
+			 * No eraseblocks belonging to this volume found. We
+			 * don't actually know whether this static volume is
+			 * completely corrupted or just contains no data. And
+			 * we cannot know this as long as data size is not
+			 * stored on flash. So we just assume the volume is
+			 * empty. FIXME: this should be handled.
+			 */
+			continue;
+		}
+
+		if (av->leb_count != av->used_ebs) {
+			/*
+			 * We found a static volume which misses several
+			 * eraseblocks. Treat it as corrupted.
+			 */
+			ubi_warn(ubi, "static volume %d misses %d LEBs - corrupted",
+				 av->vol_id, av->used_ebs - av->leb_count);
+			vol->corrupted = 1;
+			continue;
+		}
+
+		vol->used_ebs = av->used_ebs;
+		vol->used_bytes =
+			(long long)(vol->used_ebs - 1) * vol->usable_leb_size;
+		vol->used_bytes += av->last_data_size;
+		vol->last_eb_bytes = av->last_data_size;
+	}
+
+	/* And add the layout volume */
+	vol = kzalloc(sizeof(struct ubi_volume), GFP_KERNEL);
+	if (!vol)
+		return -ENOMEM;
+
+	vol->reserved_pebs = UBI_LAYOUT_VOLUME_EBS;
+	vol->alignment = UBI_LAYOUT_VOLUME_ALIGN;
+	vol->vol_type = UBI_DYNAMIC_VOLUME;
+	vol->name_len = sizeof(UBI_LAYOUT_VOLUME_NAME) - 1;
+	memcpy(vol->name, UBI_LAYOUT_VOLUME_NAME, vol->name_len + 1);
+	vol->usable_leb_size = ubi->leb_size;
+	vol->used_ebs = vol->reserved_pebs;
+	vol->last_eb_bytes = vol->reserved_pebs;
+	vol->used_bytes =
+		(long long)vol->used_ebs * (ubi->leb_size - vol->data_pad);
+	vol->vol_id = UBI_LAYOUT_VOLUME_ID;
+	vol->ref_count = 1;
+
+	ubi_assert(!ubi->volumes[i]);
+	ubi->volumes[vol_id2idx(ubi, vol->vol_id)] = vol;
+	reserved_pebs += vol->reserved_pebs;
+	ubi->vol_count += 1;
+	vol->ubi = ubi;
+	err = ubi_fastmap_init_checkmap(vol, UBI_LAYOUT_VOLUME_EBS);
+	if (err)
+		return err;
+
+	if (reserved_pebs > ubi->avail_pebs) {
+		ubi_err(ubi, "not enough PEBs, required %d, available %d",
+			reserved_pebs, ubi->avail_pebs);
+		if (ubi->corr_peb_count)
+			ubi_err(ubi, "%d PEBs are corrupted and not used",
+				ubi->corr_peb_count);
+		return -ENOSPC;
+	}
+	ubi->rsvd_pebs += reserved_pebs;
+	ubi->avail_pebs -= reserved_pebs;
+
+	return 0;
+}
+
+/**
+ * check_av - check volume attaching information.
+ * @vol: UBI volume description object
+ * @av: volume attaching information
+ *
+ * This function returns zero if the volume attaching information is consistent
+ * to the data read from the volume tabla, and %-EINVAL if not.
+ */
+static int check_av(const struct ubi_volume *vol,
+		    const struct ubi_ainf_volume *av)
+{
+	int err;
+
+	if (av->highest_lnum >= vol->reserved_pebs) {
+		err = 1;
+		goto bad;
+	}
+	if (av->leb_count > vol->reserved_pebs) {
+		err = 2;
+		goto bad;
+	}
+	if (av->vol_type != vol->vol_type) {
+		err = 3;
+		goto bad;
+	}
+	if (av->used_ebs > vol->reserved_pebs) {
+		err = 4;
+		goto bad;
+	}
+	if (av->data_pad != vol->data_pad) {
+		err = 5;
+		goto bad;
+	}
+	return 0;
+
+bad:
+	ubi_err(vol->ubi, "bad attaching information, error %d", err);
+	ubi_dump_av(av);
+	ubi_dump_vol_info(vol);
+	return -EINVAL;
+}
+
+/**
+ * check_attaching_info - check that attaching information.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ *
+ * Even though we protect on-flash data by CRC checksums, we still don't trust
+ * the media. This function ensures that attaching information is consistent to
+ * the information read from the volume table. Returns zero if the attaching
+ * information is OK and %-EINVAL if it is not.
+ */
+static int check_attaching_info(const struct ubi_device *ubi,
+			       struct ubi_attach_info *ai)
+{
+	int err, i;
+	struct ubi_ainf_volume *av;
+	struct ubi_volume *vol;
+
+	if (ai->vols_found > UBI_INT_VOL_COUNT + ubi->vtbl_slots) {
+		ubi_err(ubi, "found %d volumes while attaching, maximum is %d + %d",
+			ai->vols_found, UBI_INT_VOL_COUNT, ubi->vtbl_slots);
+		return -EINVAL;
+	}
+
+	if (ai->highest_vol_id >= ubi->vtbl_slots + UBI_INT_VOL_COUNT &&
+	    ai->highest_vol_id < UBI_INTERNAL_VOL_START) {
+		ubi_err(ubi, "too large volume ID %d found",
+			ai->highest_vol_id);
+		return -EINVAL;
+	}
+
+	for (i = 0; i < ubi->vtbl_slots + UBI_INT_VOL_COUNT; i++) {
+		cond_resched();
+
+		av = ubi_find_av(ai, i);
+		vol = ubi->volumes[i];
+		if (!vol) {
+			if (av)
+				ubi_remove_av(ai, av);
+			continue;
+		}
+
+		if (vol->reserved_pebs == 0) {
+			ubi_assert(i < ubi->vtbl_slots);
+
+			if (!av)
+				continue;
+
+			/*
+			 * During attaching we found a volume which does not
+			 * exist according to the information in the volume
+			 * table. This must have happened due to an unclean
+			 * reboot while the volume was being removed. Discard
+			 * these eraseblocks.
+			 */
+			ubi_msg(ubi, "finish volume %d removal", av->vol_id);
+			ubi_remove_av(ai, av);
+		} else if (av) {
+			err = check_av(vol, av);
+			if (err)
+				return err;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * ubi_read_volume_table - read the volume table.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ *
+ * This function reads volume table, checks it, recover from errors if needed,
+ * or creates it if needed. Returns zero in case of success and a negative
+ * error code in case of failure.
+ */
+int ubi_read_volume_table(struct ubi_device *ubi, struct ubi_attach_info *ai)
+{
+	int err;
+	struct ubi_ainf_volume *av;
+
+	empty_vtbl_record.crc = cpu_to_be32(0xf116c36b);
+
+	/*
+	 * The number of supported volumes is limited by the eraseblock size
+	 * and by the UBI_MAX_VOLUMES constant.
+	 */
+	ubi->vtbl_slots = ubi->leb_size / UBI_VTBL_RECORD_SIZE;
+	if (ubi->vtbl_slots > UBI_MAX_VOLUMES)
+		ubi->vtbl_slots = UBI_MAX_VOLUMES;
+
+	ubi->vtbl_size = ubi->vtbl_slots * UBI_VTBL_RECORD_SIZE;
+	ubi->vtbl_size = ALIGN(ubi->vtbl_size, ubi->min_io_size);
+
+	av = ubi_find_av(ai, UBI_LAYOUT_VOLUME_ID);
+	if (!av) {
+		/*
+		 * No logical eraseblocks belonging to the layout volume were
+		 * found. This could mean that the flash is just empty. In
+		 * this case we create empty layout volume.
+		 *
+		 * But if flash is not empty this must be a corruption or the
+		 * MTD device just contains garbage.
+		 */
+		if (ai->is_empty) {
+			ubi->vtbl = create_empty_lvol(ubi, ai);
+			if (IS_ERR(ubi->vtbl))
+				return PTR_ERR(ubi->vtbl);
+		} else {
+			ubi_err(ubi, "the layout volume was not found");
+			return -EINVAL;
+		}
+	} else {
+		if (av->leb_count > UBI_LAYOUT_VOLUME_EBS) {
+			/* This must not happen with proper UBI images */
+			ubi_err(ubi, "too many LEBs (%d) in layout volume",
+				av->leb_count);
+			return -EINVAL;
+		}
+
+		ubi->vtbl = process_lvol(ubi, ai, av);
+		if (IS_ERR(ubi->vtbl))
+			return PTR_ERR(ubi->vtbl);
+	}
+
+	ubi->avail_pebs = ubi->good_peb_count - ubi->corr_peb_count;
+
+	/*
+	 * The layout volume is OK, initialize the corresponding in-RAM data
+	 * structures.
+	 */
+	err = init_volumes(ubi, ai, ubi->vtbl);
+	if (err)
+		goto out_free;
+
+	/*
+	 * Make sure that the attaching information is consistent to the
+	 * information stored in the volume table.
+	 */
+	err = check_attaching_info(ubi, ai);
+	if (err)
+		goto out_free;
+
+	return 0;
+
+out_free:
+	vfree(ubi->vtbl);
+	ubi_free_all_volumes(ubi);
+	return err;
+}
+
+/**
+ * self_vtbl_check - check volume table.
+ * @ubi: UBI device description object
+ */
+static void self_vtbl_check(const struct ubi_device *ubi)
+{
+	if (!ubi_dbg_chk_gen(ubi))
+		return;
+
+	if (vtbl_check(ubi, ubi->vtbl)) {
+		ubi_err(ubi, "self-check failed");
+		BUG();
+	}
+}
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c
new file mode 100644
index 0000000000..26a214f016
--- /dev/null
+++ b/drivers/mtd/ubi/wl.c
@@ -0,0 +1,2159 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) International Business Machines Corp., 2006
+ *
+ * Authors: Artem Bityutskiy (Битюцкий Артём), Thomas Gleixner
+ */
+
+/*
+ * UBI wear-leveling sub-system.
+ *
+ * This sub-system is responsible for wear-leveling. It works in terms of
+ * physical eraseblocks and erase counters and knows nothing about logical
+ * eraseblocks, volumes, etc. From this sub-system's perspective all physical
+ * eraseblocks are of two types - used and free. Used physical eraseblocks are
+ * those that were "get" by the 'ubi_wl_get_peb()' function, and free physical
+ * eraseblocks are those that were put by the 'ubi_wl_put_peb()' function.
+ *
+ * Physical eraseblocks returned by 'ubi_wl_get_peb()' have only erase counter
+ * header. The rest of the physical eraseblock contains only %0xFF bytes.
+ *
+ * When physical eraseblocks are returned to the WL sub-system by means of the
+ * 'ubi_wl_put_peb()' function, they are scheduled for erasure. The erasure is
+ * done asynchronously in context of the per-UBI device background thread,
+ * which is also managed by the WL sub-system.
+ *
+ * The wear-leveling is ensured by means of moving the contents of used
+ * physical eraseblocks with low erase counter to free physical eraseblocks
+ * with high erase counter.
+ *
+ * If the WL sub-system fails to erase a physical eraseblock, it marks it as
+ * bad.
+ *
+ * This sub-system is also responsible for scrubbing. If a bit-flip is detected
+ * in a physical eraseblock, it has to be moved. Technically this is the same
+ * as moving it for wear-leveling reasons.
+ *
+ * As it was said, for the UBI sub-system all physical eraseblocks are either
+ * "free" or "used". Free eraseblock are kept in the @wl->free RB-tree, while
+ * used eraseblocks are kept in @wl->used, @wl->erroneous, or @wl->scrub
+ * RB-trees, as well as (temporarily) in the @wl->pq queue.
+ *
+ * When the WL sub-system returns a physical eraseblock, the physical
+ * eraseblock is protected from being moved for some "time". For this reason,
+ * the physical eraseblock is not directly moved from the @wl->free tree to the
+ * @wl->used tree. There is a protection queue in between where this
+ * physical eraseblock is temporarily stored (@wl->pq).
+ *
+ * All this protection stuff is needed because:
+ *  o we don't want to move physical eraseblocks just after we have given them
+ *    to the user; instead, we first want to let users fill them up with data;
+ *
+ *  o there is a chance that the user will put the physical eraseblock very
+ *    soon, so it makes sense not to move it for some time, but wait.
+ *
+ * Physical eraseblocks stay protected only for limited time. But the "time" is
+ * measured in erase cycles in this case. This is implemented with help of the
+ * protection queue. Eraseblocks are put to the tail of this queue when they
+ * are returned by the 'ubi_wl_get_peb()', and eraseblocks are removed from the
+ * head of the queue on each erase operation (for any eraseblock). So the
+ * length of the queue defines how may (global) erase cycles PEBs are protected.
+ *
+ * To put it differently, each physical eraseblock has 2 main states: free and
+ * used. The former state corresponds to the @wl->free tree. The latter state
+ * is split up on several sub-states:
+ * o the WL movement is allowed (@wl->used tree);
+ * o the WL movement is disallowed (@wl->erroneous) because the PEB is
+ *   erroneous - e.g., there was a read error;
+ * o the WL movement is temporarily prohibited (@wl->pq queue);
+ * o scrubbing is needed (@wl->scrub tree).
+ *
+ * Depending on the sub-state, wear-leveling entries of the used physical
+ * eraseblocks may be kept in one of those structures.
+ *
+ * Note, in this implementation, we keep a small in-RAM object for each physical
+ * eraseblock. This is surely not a scalable solution. But it appears to be good
+ * enough for moderately large flashes and it is simple. In future, one may
+ * re-work this sub-system and make it more scalable.
+ *
+ * At the moment this sub-system does not utilize the sequence number, which
+ * was introduced relatively recently. But it would be wise to do this because
+ * the sequence number of a logical eraseblock characterizes how old is it. For
+ * example, when we move a PEB with low erase counter, and we need to pick the
+ * target PEB, we pick a PEB with the highest EC if our PEB is "old" and we
+ * pick target PEB with an average EC if our PEB is not very "old". This is a
+ * room for future re-works of the WL sub-system.
+ */
+
+#include <linux/slab.h>
+#include <linux/crc32.h>
+#include <linux/freezer.h>
+#include <linux/kthread.h>
+#include "ubi.h"
+#include "wl.h"
+
+/* Number of physical eraseblocks reserved for wear-leveling purposes */
+#define WL_RESERVED_PEBS 1
+
+/*
+ * Maximum difference between two erase counters. If this threshold is
+ * exceeded, the WL sub-system starts moving data from used physical
+ * eraseblocks with low erase counter to free physical eraseblocks with high
+ * erase counter.
+ */
+#define UBI_WL_THRESHOLD CONFIG_MTD_UBI_WL_THRESHOLD
+
+/*
+ * When a physical eraseblock is moved, the WL sub-system has to pick the target
+ * physical eraseblock to move to. The simplest way would be just to pick the
+ * one with the highest erase counter. But in certain workloads this could lead
+ * to an unlimited wear of one or few physical eraseblock. Indeed, imagine a
+ * situation when the picked physical eraseblock is constantly erased after the
+ * data is written to it. So, we have a constant which limits the highest erase
+ * counter of the free physical eraseblock to pick. Namely, the WL sub-system
+ * does not pick eraseblocks with erase counter greater than the lowest erase
+ * counter plus %WL_FREE_MAX_DIFF.
+ */
+#define WL_FREE_MAX_DIFF (2*UBI_WL_THRESHOLD)
+
+/*
+ * Maximum number of consecutive background thread failures which is enough to
+ * switch to read-only mode.
+ */
+#define WL_MAX_FAILURES 32
+
+static int self_check_ec(struct ubi_device *ubi, int pnum, int ec);
+static int self_check_in_wl_tree(const struct ubi_device *ubi,
+				 struct ubi_wl_entry *e, struct rb_root *root);
+static int self_check_in_pq(const struct ubi_device *ubi,
+			    struct ubi_wl_entry *e);
+
+/**
+ * wl_tree_add - add a wear-leveling entry to a WL RB-tree.
+ * @e: the wear-leveling entry to add
+ * @root: the root of the tree
+ *
+ * Note, we use (erase counter, physical eraseblock number) pairs as keys in
+ * the @ubi->used and @ubi->free RB-trees.
+ */
+static void wl_tree_add(struct ubi_wl_entry *e, struct rb_root *root)
+{
+	struct rb_node **p, *parent = NULL;
+
+	p = &root->rb_node;
+	while (*p) {
+		struct ubi_wl_entry *e1;
+
+		parent = *p;
+		e1 = rb_entry(parent, struct ubi_wl_entry, u.rb);
+
+		if (e->ec < e1->ec)
+			p = &(*p)->rb_left;
+		else if (e->ec > e1->ec)
+			p = &(*p)->rb_right;
+		else {
+			ubi_assert(e->pnum != e1->pnum);
+			if (e->pnum < e1->pnum)
+				p = &(*p)->rb_left;
+			else
+				p = &(*p)->rb_right;
+		}
+	}
+
+	rb_link_node(&e->u.rb, parent, p);
+	rb_insert_color(&e->u.rb, root);
+}
+
+/**
+ * wl_entry_destroy - destroy a wear-leveling entry.
+ * @ubi: UBI device description object
+ * @e: the wear-leveling entry to add
+ *
+ * This function destroys a wear leveling entry and removes
+ * the reference from the lookup table.
+ */
+static void wl_entry_destroy(struct ubi_device *ubi, struct ubi_wl_entry *e)
+{
+	ubi->lookuptbl[e->pnum] = NULL;
+	kmem_cache_free(ubi_wl_entry_slab, e);
+}
+
+/**
+ * do_work - do one pending work.
+ * @ubi: UBI device description object
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int do_work(struct ubi_device *ubi)
+{
+	int err;
+	struct ubi_work *wrk;
+
+	cond_resched();
+
+	/*
+	 * @ubi->work_sem is used to synchronize with the workers. Workers take
+	 * it in read mode, so many of them may be doing works at a time. But
+	 * the queue flush code has to be sure the whole queue of works is
+	 * done, and it takes the mutex in write mode.
+	 */
+	down_read(&ubi->work_sem);
+	spin_lock(&ubi->wl_lock);
+	if (list_empty(&ubi->works)) {
+		spin_unlock(&ubi->wl_lock);
+		up_read(&ubi->work_sem);
+		return 0;
+	}
+
+	wrk = list_entry(ubi->works.next, struct ubi_work, list);
+	list_del(&wrk->list);
+	ubi->works_count -= 1;
+	ubi_assert(ubi->works_count >= 0);
+	spin_unlock(&ubi->wl_lock);
+
+	/*
+	 * Call the worker function. Do not touch the work structure
+	 * after this call as it will have been freed or reused by that
+	 * time by the worker function.
+	 */
+	err = wrk->func(ubi, wrk, 0);
+	if (err)
+		ubi_err(ubi, "work failed with error code %d", err);
+	up_read(&ubi->work_sem);
+
+	return err;
+}
+
+/**
+ * in_wl_tree - check if wear-leveling entry is present in a WL RB-tree.
+ * @e: the wear-leveling entry to check
+ * @root: the root of the tree
+ *
+ * This function returns non-zero if @e is in the @root RB-tree and zero if it
+ * is not.
+ */
+static int in_wl_tree(struct ubi_wl_entry *e, struct rb_root *root)
+{
+	struct rb_node *p;
+
+	p = root->rb_node;
+	while (p) {
+		struct ubi_wl_entry *e1;
+
+		e1 = rb_entry(p, struct ubi_wl_entry, u.rb);
+
+		if (e->pnum == e1->pnum) {
+			ubi_assert(e == e1);
+			return 1;
+		}
+
+		if (e->ec < e1->ec)
+			p = p->rb_left;
+		else if (e->ec > e1->ec)
+			p = p->rb_right;
+		else {
+			ubi_assert(e->pnum != e1->pnum);
+			if (e->pnum < e1->pnum)
+				p = p->rb_left;
+			else
+				p = p->rb_right;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * in_pq - check if a wear-leveling entry is present in the protection queue.
+ * @ubi: UBI device description object
+ * @e: the wear-leveling entry to check
+ *
+ * This function returns non-zero if @e is in the protection queue and zero
+ * if it is not.
+ */
+static inline int in_pq(const struct ubi_device *ubi, struct ubi_wl_entry *e)
+{
+	struct ubi_wl_entry *p;
+	int i;
+
+	for (i = 0; i < UBI_PROT_QUEUE_LEN; ++i)
+		list_for_each_entry(p, &ubi->pq[i], u.list)
+			if (p == e)
+				return 1;
+
+	return 0;
+}
+
+/**
+ * prot_queue_add - add physical eraseblock to the protection queue.
+ * @ubi: UBI device description object
+ * @e: the physical eraseblock to add
+ *
+ * This function adds @e to the tail of the protection queue @ubi->pq, where
+ * @e will stay for %UBI_PROT_QUEUE_LEN erase operations and will be
+ * temporarily protected from the wear-leveling worker. Note, @wl->lock has to
+ * be locked.
+ */
+static void prot_queue_add(struct ubi_device *ubi, struct ubi_wl_entry *e)
+{
+	int pq_tail = ubi->pq_head - 1;
+
+	if (pq_tail < 0)
+		pq_tail = UBI_PROT_QUEUE_LEN - 1;
+	ubi_assert(pq_tail >= 0 && pq_tail < UBI_PROT_QUEUE_LEN);
+	list_add_tail(&e->u.list, &ubi->pq[pq_tail]);
+	dbg_wl("added PEB %d EC %d to the protection queue", e->pnum, e->ec);
+}
+
+/**
+ * find_wl_entry - find wear-leveling entry closest to certain erase counter.
+ * @ubi: UBI device description object
+ * @root: the RB-tree where to look for
+ * @diff: maximum possible difference from the smallest erase counter
+ *
+ * This function looks for a wear leveling entry with erase counter closest to
+ * min + @diff, where min is the smallest erase counter.
+ */
+static struct ubi_wl_entry *find_wl_entry(struct ubi_device *ubi,
+					  struct rb_root *root, int diff)
+{
+	struct rb_node *p;
+	struct ubi_wl_entry *e;
+	int max;
+
+	e = rb_entry(rb_first(root), struct ubi_wl_entry, u.rb);
+	max = e->ec + diff;
+
+	p = root->rb_node;
+	while (p) {
+		struct ubi_wl_entry *e1;
+
+		e1 = rb_entry(p, struct ubi_wl_entry, u.rb);
+		if (e1->ec >= max)
+			p = p->rb_left;
+		else {
+			p = p->rb_right;
+			e = e1;
+		}
+	}
+
+	return e;
+}
+
+/**
+ * find_mean_wl_entry - find wear-leveling entry with medium erase counter.
+ * @ubi: UBI device description object
+ * @root: the RB-tree where to look for
+ *
+ * This function looks for a wear leveling entry with medium erase counter,
+ * but not greater or equivalent than the lowest erase counter plus
+ * %WL_FREE_MAX_DIFF/2.
+ */
+static struct ubi_wl_entry *find_mean_wl_entry(struct ubi_device *ubi,
+					       struct rb_root *root)
+{
+	struct ubi_wl_entry *e, *first, *last;
+
+	first = rb_entry(rb_first(root), struct ubi_wl_entry, u.rb);
+	last = rb_entry(rb_last(root), struct ubi_wl_entry, u.rb);
+
+	if (last->ec - first->ec < WL_FREE_MAX_DIFF) {
+		e = rb_entry(root->rb_node, struct ubi_wl_entry, u.rb);
+
+		/* If no fastmap has been written and this WL entry can be used
+		 * as anchor PEB, hold it back and return the second best
+		 * WL entry such that fastmap can use the anchor PEB later. */
+		e = may_reserve_for_fm(ubi, e, root);
+	} else
+		e = find_wl_entry(ubi, root, WL_FREE_MAX_DIFF/2);
+
+	return e;
+}
+
+/**
+ * wl_get_wle - get a mean wl entry to be used by ubi_wl_get_peb() or
+ * refill_wl_user_pool().
+ * @ubi: UBI device description object
+ *
+ * This function returns a wear leveling entry in case of success and
+ * NULL in case of failure.
+ */
+static struct ubi_wl_entry *wl_get_wle(struct ubi_device *ubi)
+{
+	struct ubi_wl_entry *e;
+
+	e = find_mean_wl_entry(ubi, &ubi->free);
+	if (!e) {
+		ubi_err(ubi, "no free eraseblocks");
+		return NULL;
+	}
+
+	self_check_in_wl_tree(ubi, e, &ubi->free);
+
+	/*
+	 * Move the physical eraseblock to the protection queue where it will
+	 * be protected from being moved for some time.
+	 */
+	rb_erase(&e->u.rb, &ubi->free);
+	ubi->free_count--;
+	dbg_wl("PEB %d EC %d", e->pnum, e->ec);
+
+	return e;
+}
+
+/**
+ * prot_queue_del - remove a physical eraseblock from the protection queue.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock to remove
+ *
+ * This function deletes PEB @pnum from the protection queue and returns zero
+ * in case of success and %-ENODEV if the PEB was not found.
+ */
+static int prot_queue_del(struct ubi_device *ubi, int pnum)
+{
+	struct ubi_wl_entry *e;
+
+	e = ubi->lookuptbl[pnum];
+	if (!e)
+		return -ENODEV;
+
+	if (self_check_in_pq(ubi, e))
+		return -ENODEV;
+
+	list_del(&e->u.list);
+	dbg_wl("deleted PEB %d from the protection queue", e->pnum);
+	return 0;
+}
+
+/**
+ * sync_erase - synchronously erase a physical eraseblock.
+ * @ubi: UBI device description object
+ * @e: the physical eraseblock to erase
+ * @torture: if the physical eraseblock has to be tortured
+ *
+ * This function returns zero in case of success and a negative error code in
+ * case of failure.
+ */
+static int sync_erase(struct ubi_device *ubi, struct ubi_wl_entry *e,
+		      int torture)
+{
+	int err;
+	struct ubi_ec_hdr *ec_hdr;
+	unsigned long long ec = e->ec;
+
+	dbg_wl("erase PEB %d, old EC %llu", e->pnum, ec);
+
+	err = self_check_ec(ubi, e->pnum, e->ec);
+	if (err)
+		return -EINVAL;
+
+	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_NOFS);
+	if (!ec_hdr)
+		return -ENOMEM;
+
+	err = ubi_io_sync_erase(ubi, e->pnum, torture);
+	if (err < 0)
+		goto out_free;
+
+	ec += err;
+	if (ec > UBI_MAX_ERASECOUNTER) {
+		/*
+		 * Erase counter overflow. Upgrade UBI and use 64-bit
+		 * erase counters internally.
+		 */
+		ubi_err(ubi, "erase counter overflow at PEB %d, EC %llu",
+			e->pnum, ec);
+		err = -EINVAL;
+		goto out_free;
+	}
+
+	dbg_wl("erased PEB %d, new EC %llu", e->pnum, ec);
+
+	ec_hdr->ec = cpu_to_be64(ec);
+
+	err = ubi_io_write_ec_hdr(ubi, e->pnum, ec_hdr);
+	if (err)
+		goto out_free;
+
+	e->ec = ec;
+	spin_lock(&ubi->wl_lock);
+	if (e->ec > ubi->max_ec)
+		ubi->max_ec = e->ec;
+	spin_unlock(&ubi->wl_lock);
+
+out_free:
+	kfree(ec_hdr);
+	return err;
+}
+
+/**
+ * serve_prot_queue - check if it is time to stop protecting PEBs.
+ * @ubi: UBI device description object
+ *
+ * This function is called after each erase operation and removes PEBs from the
+ * tail of the protection queue. These PEBs have been protected for long enough
+ * and should be moved to the used tree.
+ */
+static void serve_prot_queue(struct ubi_device *ubi)
+{
+	struct ubi_wl_entry *e, *tmp;
+	int count;
+
+	/*
+	 * There may be several protected physical eraseblock to remove,
+	 * process them all.
+	 */
+repeat:
+	count = 0;
+	spin_lock(&ubi->wl_lock);
+	list_for_each_entry_safe(e, tmp, &ubi->pq[ubi->pq_head], u.list) {
+		dbg_wl("PEB %d EC %d protection over, move to used tree",
+			e->pnum, e->ec);
+
+		list_del(&e->u.list);
+		wl_tree_add(e, &ubi->used);
+		if (count++ > 32) {
+			/*
+			 * Let's be nice and avoid holding the spinlock for
+			 * too long.
+			 */
+			spin_unlock(&ubi->wl_lock);
+			cond_resched();
+			goto repeat;
+		}
+	}
+
+	ubi->pq_head += 1;
+	if (ubi->pq_head == UBI_PROT_QUEUE_LEN)
+		ubi->pq_head = 0;
+	ubi_assert(ubi->pq_head >= 0 && ubi->pq_head < UBI_PROT_QUEUE_LEN);
+	spin_unlock(&ubi->wl_lock);
+}
+
+/**
+ * __schedule_ubi_work - schedule a work.
+ * @ubi: UBI device description object
+ * @wrk: the work to schedule
+ *
+ * This function adds a work defined by @wrk to the tail of the pending works
+ * list. Can only be used if ubi->work_sem is already held in read mode!
+ */
+static void __schedule_ubi_work(struct ubi_device *ubi, struct ubi_work *wrk)
+{
+	spin_lock(&ubi->wl_lock);
+	list_add_tail(&wrk->list, &ubi->works);
+	ubi_assert(ubi->works_count >= 0);
+	ubi->works_count += 1;
+	if (ubi->thread_enabled && !ubi_dbg_is_bgt_disabled(ubi))
+		wake_up_process(ubi->bgt_thread);
+	spin_unlock(&ubi->wl_lock);
+}
+
+/**
+ * schedule_ubi_work - schedule a work.
+ * @ubi: UBI device description object
+ * @wrk: the work to schedule
+ *
+ * This function adds a work defined by @wrk to the tail of the pending works
+ * list.
+ */
+static void schedule_ubi_work(struct ubi_device *ubi, struct ubi_work *wrk)
+{
+	down_read(&ubi->work_sem);
+	__schedule_ubi_work(ubi, wrk);
+	up_read(&ubi->work_sem);
+}
+
+static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
+			int shutdown);
+
+/**
+ * schedule_erase - schedule an erase work.
+ * @ubi: UBI device description object
+ * @e: the WL entry of the physical eraseblock to erase
+ * @vol_id: the volume ID that last used this PEB
+ * @lnum: the last used logical eraseblock number for the PEB
+ * @torture: if the physical eraseblock has to be tortured
+ * @nested: denotes whether the work_sem is already held
+ *
+ * This function returns zero in case of success and a %-ENOMEM in case of
+ * failure.
+ */
+static int schedule_erase(struct ubi_device *ubi, struct ubi_wl_entry *e,
+			  int vol_id, int lnum, int torture, bool nested)
+{
+	struct ubi_work *wl_wrk;
+
+	ubi_assert(e);
+
+	dbg_wl("schedule erasure of PEB %d, EC %d, torture %d",
+	       e->pnum, e->ec, torture);
+
+	wl_wrk = kmalloc(sizeof(struct ubi_work), GFP_NOFS);
+	if (!wl_wrk)
+		return -ENOMEM;
+
+	wl_wrk->func = &erase_worker;
+	wl_wrk->e = e;
+	wl_wrk->vol_id = vol_id;
+	wl_wrk->lnum = lnum;
+	wl_wrk->torture = torture;
+
+	if (nested)
+		__schedule_ubi_work(ubi, wl_wrk);
+	else
+		schedule_ubi_work(ubi, wl_wrk);
+	return 0;
+}
+
+static int __erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk);
+/**
+ * do_sync_erase - run the erase worker synchronously.
+ * @ubi: UBI device description object
+ * @e: the WL entry of the physical eraseblock to erase
+ * @vol_id: the volume ID that last used this PEB
+ * @lnum: the last used logical eraseblock number for the PEB
+ * @torture: if the physical eraseblock has to be tortured
+ *
+ */
+static int do_sync_erase(struct ubi_device *ubi, struct ubi_wl_entry *e,
+			 int vol_id, int lnum, int torture)
+{
+	struct ubi_work wl_wrk;
+
+	dbg_wl("sync erase of PEB %i", e->pnum);
+
+	wl_wrk.e = e;
+	wl_wrk.vol_id = vol_id;
+	wl_wrk.lnum = lnum;
+	wl_wrk.torture = torture;
+
+	return __erase_worker(ubi, &wl_wrk);
+}
+
+static int ensure_wear_leveling(struct ubi_device *ubi, int nested);
+/**
+ * wear_leveling_worker - wear-leveling worker function.
+ * @ubi: UBI device description object
+ * @wrk: the work object
+ * @shutdown: non-zero if the worker has to free memory and exit
+ * because the WL-subsystem is shutting down
+ *
+ * This function copies a more worn out physical eraseblock to a less worn out
+ * one. Returns zero in case of success and a negative error code in case of
+ * failure.
+ */
+static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
+				int shutdown)
+{
+	int err, scrubbing = 0, torture = 0, protect = 0, erroneous = 0;
+	int erase = 0, keep = 0, vol_id = -1, lnum = -1;
+	struct ubi_wl_entry *e1, *e2;
+	struct ubi_vid_io_buf *vidb;
+	struct ubi_vid_hdr *vid_hdr;
+	int dst_leb_clean = 0;
+
+	kfree(wrk);
+	if (shutdown)
+		return 0;
+
+	vidb = ubi_alloc_vid_buf(ubi, GFP_NOFS);
+	if (!vidb)
+		return -ENOMEM;
+
+	vid_hdr = ubi_get_vid_hdr(vidb);
+
+	down_read(&ubi->fm_eba_sem);
+	mutex_lock(&ubi->move_mutex);
+	spin_lock(&ubi->wl_lock);
+	ubi_assert(!ubi->move_from && !ubi->move_to);
+	ubi_assert(!ubi->move_to_put);
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+	if (!next_peb_for_wl(ubi) ||
+#else
+	if (!ubi->free.rb_node ||
+#endif
+	    (!ubi->used.rb_node && !ubi->scrub.rb_node)) {
+		/*
+		 * No free physical eraseblocks? Well, they must be waiting in
+		 * the queue to be erased. Cancel movement - it will be
+		 * triggered again when a free physical eraseblock appears.
+		 *
+		 * No used physical eraseblocks? They must be temporarily
+		 * protected from being moved. They will be moved to the
+		 * @ubi->used tree later and the wear-leveling will be
+		 * triggered again.
+		 */
+		dbg_wl("cancel WL, a list is empty: free %d, used %d",
+		       !ubi->free.rb_node, !ubi->used.rb_node);
+		goto out_cancel;
+	}
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+	e1 = find_anchor_wl_entry(&ubi->used);
+	if (e1 && ubi->fm_anchor &&
+	    (ubi->fm_anchor->ec - e1->ec >= UBI_WL_THRESHOLD)) {
+		ubi->fm_do_produce_anchor = 1;
+		/*
+		 * fm_anchor is no longer considered a good anchor.
+		 * NULL assignment also prevents multiple wear level checks
+		 * of this PEB.
+		 */
+		wl_tree_add(ubi->fm_anchor, &ubi->free);
+		ubi->fm_anchor = NULL;
+		ubi->free_count++;
+	}
+
+	if (ubi->fm_do_produce_anchor) {
+		if (!e1)
+			goto out_cancel;
+		e2 = get_peb_for_wl(ubi);
+		if (!e2)
+			goto out_cancel;
+
+		self_check_in_wl_tree(ubi, e1, &ubi->used);
+		rb_erase(&e1->u.rb, &ubi->used);
+		dbg_wl("anchor-move PEB %d to PEB %d", e1->pnum, e2->pnum);
+		ubi->fm_do_produce_anchor = 0;
+	} else if (!ubi->scrub.rb_node) {
+#else
+	if (!ubi->scrub.rb_node) {
+#endif
+		/*
+		 * Now pick the least worn-out used physical eraseblock and a
+		 * highly worn-out free physical eraseblock. If the erase
+		 * counters differ much enough, start wear-leveling.
+		 */
+		e1 = rb_entry(rb_first(&ubi->used), struct ubi_wl_entry, u.rb);
+		e2 = get_peb_for_wl(ubi);
+		if (!e2)
+			goto out_cancel;
+
+		if (!(e2->ec - e1->ec >= UBI_WL_THRESHOLD)) {
+			dbg_wl("no WL needed: min used EC %d, max free EC %d",
+			       e1->ec, e2->ec);
+
+			/* Give the unused PEB back */
+			wl_tree_add(e2, &ubi->free);
+			ubi->free_count++;
+			goto out_cancel;
+		}
+		self_check_in_wl_tree(ubi, e1, &ubi->used);
+		rb_erase(&e1->u.rb, &ubi->used);
+		dbg_wl("move PEB %d EC %d to PEB %d EC %d",
+		       e1->pnum, e1->ec, e2->pnum, e2->ec);
+	} else {
+		/* Perform scrubbing */
+		scrubbing = 1;
+		e1 = rb_entry(rb_first(&ubi->scrub), struct ubi_wl_entry, u.rb);
+		e2 = get_peb_for_wl(ubi);
+		if (!e2)
+			goto out_cancel;
+
+		self_check_in_wl_tree(ubi, e1, &ubi->scrub);
+		rb_erase(&e1->u.rb, &ubi->scrub);
+		dbg_wl("scrub PEB %d to PEB %d", e1->pnum, e2->pnum);
+	}
+
+	ubi->move_from = e1;
+	ubi->move_to = e2;
+	spin_unlock(&ubi->wl_lock);
+
+	/*
+	 * Now we are going to copy physical eraseblock @e1->pnum to @e2->pnum.
+	 * We so far do not know which logical eraseblock our physical
+	 * eraseblock (@e1) belongs to. We have to read the volume identifier
+	 * header first.
+	 *
+	 * Note, we are protected from this PEB being unmapped and erased. The
+	 * 'ubi_wl_put_peb()' would wait for moving to be finished if the PEB
+	 * which is being moved was unmapped.
+	 */
+
+	err = ubi_io_read_vid_hdr(ubi, e1->pnum, vidb, 0);
+	if (err && err != UBI_IO_BITFLIPS) {
+		dst_leb_clean = 1;
+		if (err == UBI_IO_FF) {
+			/*
+			 * We are trying to move PEB without a VID header. UBI
+			 * always write VID headers shortly after the PEB was
+			 * given, so we have a situation when it has not yet
+			 * had a chance to write it, because it was preempted.
+			 * So add this PEB to the protection queue so far,
+			 * because presumably more data will be written there
+			 * (including the missing VID header), and then we'll
+			 * move it.
+			 */
+			dbg_wl("PEB %d has no VID header", e1->pnum);
+			protect = 1;
+			goto out_not_moved;
+		} else if (err == UBI_IO_FF_BITFLIPS) {
+			/*
+			 * The same situation as %UBI_IO_FF, but bit-flips were
+			 * detected. It is better to schedule this PEB for
+			 * scrubbing.
+			 */
+			dbg_wl("PEB %d has no VID header but has bit-flips",
+			       e1->pnum);
+			scrubbing = 1;
+			goto out_not_moved;
+		} else if (ubi->fast_attach && err == UBI_IO_BAD_HDR_EBADMSG) {
+			/*
+			 * While a full scan would detect interrupted erasures
+			 * at attach time we can face them here when attached from
+			 * Fastmap.
+			 */
+			dbg_wl("PEB %d has ECC errors, maybe from an interrupted erasure",
+			       e1->pnum);
+			erase = 1;
+			goto out_not_moved;
+		}
+
+		ubi_err(ubi, "error %d while reading VID header from PEB %d",
+			err, e1->pnum);
+		goto out_error;
+	}
+
+	vol_id = be32_to_cpu(vid_hdr->vol_id);
+	lnum = be32_to_cpu(vid_hdr->lnum);
+
+	err = ubi_eba_copy_leb(ubi, e1->pnum, e2->pnum, vidb);
+	if (err) {
+		if (err == MOVE_CANCEL_RACE) {
+			/*
+			 * The LEB has not been moved because the volume is
+			 * being deleted or the PEB has been put meanwhile. We
+			 * should prevent this PEB from being selected for
+			 * wear-leveling movement again, so put it to the
+			 * protection queue.
+			 */
+			protect = 1;
+			dst_leb_clean = 1;
+			goto out_not_moved;
+		}
+		if (err == MOVE_RETRY) {
+			scrubbing = 1;
+			dst_leb_clean = 1;
+			goto out_not_moved;
+		}
+		if (err == MOVE_TARGET_BITFLIPS || err == MOVE_TARGET_WR_ERR ||
+		    err == MOVE_TARGET_RD_ERR) {
+			/*
+			 * Target PEB had bit-flips or write error - torture it.
+			 */
+			torture = 1;
+			keep = 1;
+			goto out_not_moved;
+		}
+
+		if (err == MOVE_SOURCE_RD_ERR) {
+			/*
+			 * An error happened while reading the source PEB. Do
+			 * not switch to R/O mode in this case, and give the
+			 * upper layers a possibility to recover from this,
+			 * e.g. by unmapping corresponding LEB. Instead, just
+			 * put this PEB to the @ubi->erroneous list to prevent
+			 * UBI from trying to move it over and over again.
+			 */
+			if (ubi->erroneous_peb_count > ubi->max_erroneous) {
+				ubi_err(ubi, "too many erroneous eraseblocks (%d)",
+					ubi->erroneous_peb_count);
+				goto out_error;
+			}
+			dst_leb_clean = 1;
+			erroneous = 1;
+			goto out_not_moved;
+		}
+
+		if (err < 0)
+			goto out_error;
+
+		ubi_assert(0);
+	}
+
+	/* The PEB has been successfully moved */
+	if (scrubbing)
+		ubi_msg(ubi, "scrubbed PEB %d (LEB %d:%d), data moved to PEB %d",
+			e1->pnum, vol_id, lnum, e2->pnum);
+	ubi_free_vid_buf(vidb);
+
+	spin_lock(&ubi->wl_lock);
+	if (!ubi->move_to_put) {
+		wl_tree_add(e2, &ubi->used);
+		e2 = NULL;
+	}
+	ubi->move_from = ubi->move_to = NULL;
+	ubi->move_to_put = ubi->wl_scheduled = 0;
+	spin_unlock(&ubi->wl_lock);
+
+	err = do_sync_erase(ubi, e1, vol_id, lnum, 0);
+	if (err) {
+		if (e2) {
+			spin_lock(&ubi->wl_lock);
+			wl_entry_destroy(ubi, e2);
+			spin_unlock(&ubi->wl_lock);
+		}
+		goto out_ro;
+	}
+
+	if (e2) {
+		/*
+		 * Well, the target PEB was put meanwhile, schedule it for
+		 * erasure.
+		 */
+		dbg_wl("PEB %d (LEB %d:%d) was put meanwhile, erase",
+		       e2->pnum, vol_id, lnum);
+		err = do_sync_erase(ubi, e2, vol_id, lnum, 0);
+		if (err)
+			goto out_ro;
+	}
+
+	dbg_wl("done");
+	mutex_unlock(&ubi->move_mutex);
+	up_read(&ubi->fm_eba_sem);
+	return 0;
+
+	/*
+	 * For some reasons the LEB was not moved, might be an error, might be
+	 * something else. @e1 was not changed, so return it back. @e2 might
+	 * have been changed, schedule it for erasure.
+	 */
+out_not_moved:
+	if (vol_id != -1)
+		dbg_wl("cancel moving PEB %d (LEB %d:%d) to PEB %d (%d)",
+		       e1->pnum, vol_id, lnum, e2->pnum, err);
+	else
+		dbg_wl("cancel moving PEB %d to PEB %d (%d)",
+		       e1->pnum, e2->pnum, err);
+	spin_lock(&ubi->wl_lock);
+	if (protect)
+		prot_queue_add(ubi, e1);
+	else if (erroneous) {
+		wl_tree_add(e1, &ubi->erroneous);
+		ubi->erroneous_peb_count += 1;
+	} else if (scrubbing)
+		wl_tree_add(e1, &ubi->scrub);
+	else if (keep)
+		wl_tree_add(e1, &ubi->used);
+	if (dst_leb_clean) {
+		wl_tree_add(e2, &ubi->free);
+		ubi->free_count++;
+	}
+
+	ubi_assert(!ubi->move_to_put);
+	ubi->move_from = ubi->move_to = NULL;
+	ubi->wl_scheduled = 0;
+	spin_unlock(&ubi->wl_lock);
+
+	ubi_free_vid_buf(vidb);
+	if (dst_leb_clean) {
+		ensure_wear_leveling(ubi, 1);
+	} else {
+		err = do_sync_erase(ubi, e2, vol_id, lnum, torture);
+		if (err)
+			goto out_ro;
+	}
+
+	if (erase) {
+		err = do_sync_erase(ubi, e1, vol_id, lnum, 1);
+		if (err)
+			goto out_ro;
+	}
+
+	mutex_unlock(&ubi->move_mutex);
+	up_read(&ubi->fm_eba_sem);
+	return 0;
+
+out_error:
+	if (vol_id != -1)
+		ubi_err(ubi, "error %d while moving PEB %d to PEB %d",
+			err, e1->pnum, e2->pnum);
+	else
+		ubi_err(ubi, "error %d while moving PEB %d (LEB %d:%d) to PEB %d",
+			err, e1->pnum, vol_id, lnum, e2->pnum);
+	spin_lock(&ubi->wl_lock);
+	ubi->move_from = ubi->move_to = NULL;
+	ubi->move_to_put = ubi->wl_scheduled = 0;
+	wl_entry_destroy(ubi, e1);
+	wl_entry_destroy(ubi, e2);
+	spin_unlock(&ubi->wl_lock);
+
+	ubi_free_vid_buf(vidb);
+
+out_ro:
+	ubi_ro_mode(ubi);
+	mutex_unlock(&ubi->move_mutex);
+	up_read(&ubi->fm_eba_sem);
+	ubi_assert(err != 0);
+	return err < 0 ? err : -EIO;
+
+out_cancel:
+	ubi->wl_scheduled = 0;
+	spin_unlock(&ubi->wl_lock);
+	mutex_unlock(&ubi->move_mutex);
+	up_read(&ubi->fm_eba_sem);
+	ubi_free_vid_buf(vidb);
+	return 0;
+}
+
+/**
+ * ensure_wear_leveling - schedule wear-leveling if it is needed.
+ * @ubi: UBI device description object
+ * @nested: set to non-zero if this function is called from UBI worker
+ *
+ * This function checks if it is time to start wear-leveling and schedules it
+ * if yes. This function returns zero in case of success and a negative error
+ * code in case of failure.
+ */
+static int ensure_wear_leveling(struct ubi_device *ubi, int nested)
+{
+	int err = 0;
+	struct ubi_work *wrk;
+
+	spin_lock(&ubi->wl_lock);
+	if (ubi->wl_scheduled)
+		/* Wear-leveling is already in the work queue */
+		goto out_unlock;
+
+	/*
+	 * If the ubi->scrub tree is not empty, scrubbing is needed, and the
+	 * WL worker has to be scheduled anyway.
+	 */
+	if (!ubi->scrub.rb_node) {
+#ifdef CONFIG_MTD_UBI_FASTMAP
+		if (!need_wear_leveling(ubi))
+			goto out_unlock;
+#else
+		struct ubi_wl_entry *e1;
+		struct ubi_wl_entry *e2;
+
+		if (!ubi->used.rb_node || !ubi->free.rb_node)
+			/* No physical eraseblocks - no deal */
+			goto out_unlock;
+
+		/*
+		 * We schedule wear-leveling only if the difference between the
+		 * lowest erase counter of used physical eraseblocks and a high
+		 * erase counter of free physical eraseblocks is greater than
+		 * %UBI_WL_THRESHOLD.
+		 */
+		e1 = rb_entry(rb_first(&ubi->used), struct ubi_wl_entry, u.rb);
+		e2 = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF);
+
+		if (!(e2->ec - e1->ec >= UBI_WL_THRESHOLD))
+			goto out_unlock;
+#endif
+		dbg_wl("schedule wear-leveling");
+	} else
+		dbg_wl("schedule scrubbing");
+
+	ubi->wl_scheduled = 1;
+	spin_unlock(&ubi->wl_lock);
+
+	wrk = kmalloc(sizeof(struct ubi_work), GFP_NOFS);
+	if (!wrk) {
+		err = -ENOMEM;
+		goto out_cancel;
+	}
+
+	wrk->func = &wear_leveling_worker;
+	if (nested)
+		__schedule_ubi_work(ubi, wrk);
+	else
+		schedule_ubi_work(ubi, wrk);
+	return err;
+
+out_cancel:
+	spin_lock(&ubi->wl_lock);
+	ubi->wl_scheduled = 0;
+out_unlock:
+	spin_unlock(&ubi->wl_lock);
+	return err;
+}
+
+/**
+ * __erase_worker - physical eraseblock erase worker function.
+ * @ubi: UBI device description object
+ * @wl_wrk: the work object
+ *
+ * This function erases a physical eraseblock and perform torture testing if
+ * needed. It also takes care about marking the physical eraseblock bad if
+ * needed. Returns zero in case of success and a negative error code in case of
+ * failure.
+ */
+static int __erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk)
+{
+	struct ubi_wl_entry *e = wl_wrk->e;
+	int pnum = e->pnum;
+	int vol_id = wl_wrk->vol_id;
+	int lnum = wl_wrk->lnum;
+	int err, available_consumed = 0;
+
+	dbg_wl("erase PEB %d EC %d LEB %d:%d",
+	       pnum, e->ec, wl_wrk->vol_id, wl_wrk->lnum);
+
+	err = sync_erase(ubi, e, wl_wrk->torture);
+	if (!err) {
+		spin_lock(&ubi->wl_lock);
+
+		if (!ubi->fm_disabled && !ubi->fm_anchor &&
+		    e->pnum < UBI_FM_MAX_START) {
+			/*
+			 * Abort anchor production, if needed it will be
+			 * enabled again in the wear leveling started below.
+			 */
+			ubi->fm_anchor = e;
+			ubi->fm_do_produce_anchor = 0;
+		} else {
+			wl_tree_add(e, &ubi->free);
+			ubi->free_count++;
+		}
+
+		spin_unlock(&ubi->wl_lock);
+
+		/*
+		 * One more erase operation has happened, take care about
+		 * protected physical eraseblocks.
+		 */
+		serve_prot_queue(ubi);
+
+		/* And take care about wear-leveling */
+		err = ensure_wear_leveling(ubi, 1);
+		return err;
+	}
+
+	ubi_err(ubi, "failed to erase PEB %d, error %d", pnum, err);
+
+	if (err == -EINTR || err == -ENOMEM || err == -EAGAIN ||
+	    err == -EBUSY) {
+		int err1;
+
+		/* Re-schedule the LEB for erasure */
+		err1 = schedule_erase(ubi, e, vol_id, lnum, 0, true);
+		if (err1) {
+			spin_lock(&ubi->wl_lock);
+			wl_entry_destroy(ubi, e);
+			spin_unlock(&ubi->wl_lock);
+			err = err1;
+			goto out_ro;
+		}
+		return err;
+	}
+
+	spin_lock(&ubi->wl_lock);
+	wl_entry_destroy(ubi, e);
+	spin_unlock(&ubi->wl_lock);
+	if (err != -EIO)
+		/*
+		 * If this is not %-EIO, we have no idea what to do. Scheduling
+		 * this physical eraseblock for erasure again would cause
+		 * errors again and again. Well, lets switch to R/O mode.
+		 */
+		goto out_ro;
+
+	/* It is %-EIO, the PEB went bad */
+
+	if (!ubi->bad_allowed) {
+		ubi_err(ubi, "bad physical eraseblock %d detected", pnum);
+		goto out_ro;
+	}
+
+	spin_lock(&ubi->volumes_lock);
+	if (ubi->beb_rsvd_pebs == 0) {
+		if (ubi->avail_pebs == 0) {
+			spin_unlock(&ubi->volumes_lock);
+			ubi_err(ubi, "no reserved/available physical eraseblocks");
+			goto out_ro;
+		}
+		ubi->avail_pebs -= 1;
+		available_consumed = 1;
+	}
+	spin_unlock(&ubi->volumes_lock);
+
+	ubi_msg(ubi, "mark PEB %d as bad", pnum);
+	err = ubi_io_mark_bad(ubi, pnum);
+	if (err)
+		goto out_ro;
+
+	spin_lock(&ubi->volumes_lock);
+	if (ubi->beb_rsvd_pebs > 0) {
+		if (available_consumed) {
+			/*
+			 * The amount of reserved PEBs increased since we last
+			 * checked.
+			 */
+			ubi->avail_pebs += 1;
+			available_consumed = 0;
+		}
+		ubi->beb_rsvd_pebs -= 1;
+	}
+	ubi->bad_peb_count += 1;
+	ubi->good_peb_count -= 1;
+	ubi_calculate_reserved(ubi);
+	if (available_consumed)
+		ubi_warn(ubi, "no PEBs in the reserved pool, used an available PEB");
+	else if (ubi->beb_rsvd_pebs)
+		ubi_msg(ubi, "%d PEBs left in the reserve",
+			ubi->beb_rsvd_pebs);
+	else
+		ubi_warn(ubi, "last PEB from the reserve was used");
+	spin_unlock(&ubi->volumes_lock);
+
+	return err;
+
+out_ro:
+	if (available_consumed) {
+		spin_lock(&ubi->volumes_lock);
+		ubi->avail_pebs += 1;
+		spin_unlock(&ubi->volumes_lock);
+	}
+	ubi_ro_mode(ubi);
+	return err;
+}
+
+static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
+			  int shutdown)
+{
+	int ret;
+
+	if (shutdown) {
+		struct ubi_wl_entry *e = wl_wrk->e;
+
+		dbg_wl("cancel erasure of PEB %d EC %d", e->pnum, e->ec);
+		kfree(wl_wrk);
+		wl_entry_destroy(ubi, e);
+		return 0;
+	}
+
+	ret = __erase_worker(ubi, wl_wrk);
+	kfree(wl_wrk);
+	return ret;
+}
+
+/**
+ * ubi_wl_put_peb - return a PEB to the wear-leveling sub-system.
+ * @ubi: UBI device description object
+ * @vol_id: the volume ID that last used this PEB
+ * @lnum: the last used logical eraseblock number for the PEB
+ * @pnum: physical eraseblock to return
+ * @torture: if this physical eraseblock has to be tortured
+ *
+ * This function is called to return physical eraseblock @pnum to the pool of
+ * free physical eraseblocks. The @torture flag has to be set if an I/O error
+ * occurred to this @pnum and it has to be tested. This function returns zero
+ * in case of success, and a negative error code in case of failure.
+ */
+int ubi_wl_put_peb(struct ubi_device *ubi, int vol_id, int lnum,
+		   int pnum, int torture)
+{
+	int err;
+	struct ubi_wl_entry *e;
+
+	dbg_wl("PEB %d", pnum);
+	ubi_assert(pnum >= 0);
+	ubi_assert(pnum < ubi->peb_count);
+
+	down_read(&ubi->fm_protect);
+
+retry:
+	spin_lock(&ubi->wl_lock);
+	e = ubi->lookuptbl[pnum];
+	if (!e) {
+		/*
+		 * This wl entry has been removed for some errors by other
+		 * process (eg. wear leveling worker), corresponding process
+		 * (except __erase_worker, which cannot concurrent with
+		 * ubi_wl_put_peb) will set ubi ro_mode at the same time,
+		 * just ignore this wl entry.
+		 */
+		spin_unlock(&ubi->wl_lock);
+		up_read(&ubi->fm_protect);
+		return 0;
+	}
+	if (e == ubi->move_from) {
+		/*
+		 * User is putting the physical eraseblock which was selected to
+		 * be moved. It will be scheduled for erasure in the
+		 * wear-leveling worker.
+		 */
+		dbg_wl("PEB %d is being moved, wait", pnum);
+		spin_unlock(&ubi->wl_lock);
+
+		/* Wait for the WL worker by taking the @ubi->move_mutex */
+		mutex_lock(&ubi->move_mutex);
+		mutex_unlock(&ubi->move_mutex);
+		goto retry;
+	} else if (e == ubi->move_to) {
+		/*
+		 * User is putting the physical eraseblock which was selected
+		 * as the target the data is moved to. It may happen if the EBA
+		 * sub-system already re-mapped the LEB in 'ubi_eba_copy_leb()'
+		 * but the WL sub-system has not put the PEB to the "used" tree
+		 * yet, but it is about to do this. So we just set a flag which
+		 * will tell the WL worker that the PEB is not needed anymore
+		 * and should be scheduled for erasure.
+		 */
+		dbg_wl("PEB %d is the target of data moving", pnum);
+		ubi_assert(!ubi->move_to_put);
+		ubi->move_to_put = 1;
+		spin_unlock(&ubi->wl_lock);
+		up_read(&ubi->fm_protect);
+		return 0;
+	} else {
+		if (in_wl_tree(e, &ubi->used)) {
+			self_check_in_wl_tree(ubi, e, &ubi->used);
+			rb_erase(&e->u.rb, &ubi->used);
+		} else if (in_wl_tree(e, &ubi->scrub)) {
+			self_check_in_wl_tree(ubi, e, &ubi->scrub);
+			rb_erase(&e->u.rb, &ubi->scrub);
+		} else if (in_wl_tree(e, &ubi->erroneous)) {
+			self_check_in_wl_tree(ubi, e, &ubi->erroneous);
+			rb_erase(&e->u.rb, &ubi->erroneous);
+			ubi->erroneous_peb_count -= 1;
+			ubi_assert(ubi->erroneous_peb_count >= 0);
+			/* Erroneous PEBs should be tortured */
+			torture = 1;
+		} else {
+			err = prot_queue_del(ubi, e->pnum);
+			if (err) {
+				ubi_err(ubi, "PEB %d not found", pnum);
+				ubi_ro_mode(ubi);
+				spin_unlock(&ubi->wl_lock);
+				up_read(&ubi->fm_protect);
+				return err;
+			}
+		}
+	}
+	spin_unlock(&ubi->wl_lock);
+
+	err = schedule_erase(ubi, e, vol_id, lnum, torture, false);
+	if (err) {
+		spin_lock(&ubi->wl_lock);
+		wl_tree_add(e, &ubi->used);
+		spin_unlock(&ubi->wl_lock);
+	}
+
+	up_read(&ubi->fm_protect);
+	return err;
+}
+
+/**
+ * ubi_wl_scrub_peb - schedule a physical eraseblock for scrubbing.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock to schedule
+ *
+ * If a bit-flip in a physical eraseblock is detected, this physical eraseblock
+ * needs scrubbing. This function schedules a physical eraseblock for
+ * scrubbing which is done in background. This function returns zero in case of
+ * success and a negative error code in case of failure.
+ */
+int ubi_wl_scrub_peb(struct ubi_device *ubi, int pnum)
+{
+	struct ubi_wl_entry *e;
+
+	ubi_msg(ubi, "schedule PEB %d for scrubbing", pnum);
+
+retry:
+	spin_lock(&ubi->wl_lock);
+	e = ubi->lookuptbl[pnum];
+	if (e == ubi->move_from || in_wl_tree(e, &ubi->scrub) ||
+				   in_wl_tree(e, &ubi->erroneous)) {
+		spin_unlock(&ubi->wl_lock);
+		return 0;
+	}
+
+	if (e == ubi->move_to) {
+		/*
+		 * This physical eraseblock was used to move data to. The data
+		 * was moved but the PEB was not yet inserted to the proper
+		 * tree. We should just wait a little and let the WL worker
+		 * proceed.
+		 */
+		spin_unlock(&ubi->wl_lock);
+		dbg_wl("the PEB %d is not in proper tree, retry", pnum);
+		yield();
+		goto retry;
+	}
+
+	if (in_wl_tree(e, &ubi->used)) {
+		self_check_in_wl_tree(ubi, e, &ubi->used);
+		rb_erase(&e->u.rb, &ubi->used);
+	} else {
+		int err;
+
+		err = prot_queue_del(ubi, e->pnum);
+		if (err) {
+			ubi_err(ubi, "PEB %d not found", pnum);
+			ubi_ro_mode(ubi);
+			spin_unlock(&ubi->wl_lock);
+			return err;
+		}
+	}
+
+	wl_tree_add(e, &ubi->scrub);
+	spin_unlock(&ubi->wl_lock);
+
+	/*
+	 * Technically scrubbing is the same as wear-leveling, so it is done
+	 * by the WL worker.
+	 */
+	return ensure_wear_leveling(ubi, 0);
+}
+
+/**
+ * ubi_wl_flush - flush all pending works.
+ * @ubi: UBI device description object
+ * @vol_id: the volume id to flush for
+ * @lnum: the logical eraseblock number to flush for
+ *
+ * This function executes all pending works for a particular volume id /
+ * logical eraseblock number pair. If either value is set to %UBI_ALL, then it
+ * acts as a wildcard for all of the corresponding volume numbers or logical
+ * eraseblock numbers. It returns zero in case of success and a negative error
+ * code in case of failure.
+ */
+int ubi_wl_flush(struct ubi_device *ubi, int vol_id, int lnum)
+{
+	int err = 0;
+	int found = 1;
+
+	/*
+	 * Erase while the pending works queue is not empty, but not more than
+	 * the number of currently pending works.
+	 */
+	dbg_wl("flush pending work for LEB %d:%d (%d pending works)",
+	       vol_id, lnum, ubi->works_count);
+
+	while (found) {
+		struct ubi_work *wrk, *tmp;
+		found = 0;
+
+		down_read(&ubi->work_sem);
+		spin_lock(&ubi->wl_lock);
+		list_for_each_entry_safe(wrk, tmp, &ubi->works, list) {
+			if ((vol_id == UBI_ALL || wrk->vol_id == vol_id) &&
+			    (lnum == UBI_ALL || wrk->lnum == lnum)) {
+				list_del(&wrk->list);
+				ubi->works_count -= 1;
+				ubi_assert(ubi->works_count >= 0);
+				spin_unlock(&ubi->wl_lock);
+
+				err = wrk->func(ubi, wrk, 0);
+				if (err) {
+					up_read(&ubi->work_sem);
+					return err;
+				}
+
+				spin_lock(&ubi->wl_lock);
+				found = 1;
+				break;
+			}
+		}
+		spin_unlock(&ubi->wl_lock);
+		up_read(&ubi->work_sem);
+	}
+
+	/*
+	 * Make sure all the works which have been done in parallel are
+	 * finished.
+	 */
+	down_write(&ubi->work_sem);
+	up_write(&ubi->work_sem);
+
+	return err;
+}
+
+static bool scrub_possible(struct ubi_device *ubi, struct ubi_wl_entry *e)
+{
+	if (in_wl_tree(e, &ubi->scrub))
+		return false;
+	else if (in_wl_tree(e, &ubi->erroneous))
+		return false;
+	else if (ubi->move_from == e)
+		return false;
+	else if (ubi->move_to == e)
+		return false;
+
+	return true;
+}
+
+/**
+ * ubi_bitflip_check - Check an eraseblock for bitflips and scrub it if needed.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock to schedule
+ * @force: don't read the block, assume bitflips happened and take action.
+ *
+ * This function reads the given eraseblock and checks if bitflips occured.
+ * In case of bitflips, the eraseblock is scheduled for scrubbing.
+ * If scrubbing is forced with @force, the eraseblock is not read,
+ * but scheduled for scrubbing right away.
+ *
+ * Returns:
+ * %EINVAL, PEB is out of range
+ * %ENOENT, PEB is no longer used by UBI
+ * %EBUSY, PEB cannot be checked now or a check is currently running on it
+ * %EAGAIN, bit flips happened but scrubbing is currently not possible
+ * %EUCLEAN, bit flips happened and PEB is scheduled for scrubbing
+ * %0, no bit flips detected
+ */
+int ubi_bitflip_check(struct ubi_device *ubi, int pnum, int force)
+{
+	int err = 0;
+	struct ubi_wl_entry *e;
+
+	if (pnum < 0 || pnum >= ubi->peb_count) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	/*
+	 * Pause all parallel work, otherwise it can happen that the
+	 * erase worker frees a wl entry under us.
+	 */
+	down_write(&ubi->work_sem);
+
+	/*
+	 * Make sure that the wl entry does not change state while
+	 * inspecting it.
+	 */
+	spin_lock(&ubi->wl_lock);
+	e = ubi->lookuptbl[pnum];
+	if (!e) {
+		spin_unlock(&ubi->wl_lock);
+		err = -ENOENT;
+		goto out_resume;
+	}
+
+	/*
+	 * Does it make sense to check this PEB?
+	 */
+	if (!scrub_possible(ubi, e)) {
+		spin_unlock(&ubi->wl_lock);
+		err = -EBUSY;
+		goto out_resume;
+	}
+	spin_unlock(&ubi->wl_lock);
+
+	if (!force) {
+		mutex_lock(&ubi->buf_mutex);
+		err = ubi_io_read(ubi, ubi->peb_buf, pnum, 0, ubi->peb_size);
+		mutex_unlock(&ubi->buf_mutex);
+	}
+
+	if (force || err == UBI_IO_BITFLIPS) {
+		/*
+		 * Okay, bit flip happened, let's figure out what we can do.
+		 */
+		spin_lock(&ubi->wl_lock);
+
+		/*
+		 * Recheck. We released wl_lock, UBI might have killed the
+		 * wl entry under us.
+		 */
+		e = ubi->lookuptbl[pnum];
+		if (!e) {
+			spin_unlock(&ubi->wl_lock);
+			err = -ENOENT;
+			goto out_resume;
+		}
+
+		/*
+		 * Need to re-check state
+		 */
+		if (!scrub_possible(ubi, e)) {
+			spin_unlock(&ubi->wl_lock);
+			err = -EBUSY;
+			goto out_resume;
+		}
+
+		if (in_pq(ubi, e)) {
+			prot_queue_del(ubi, e->pnum);
+			wl_tree_add(e, &ubi->scrub);
+			spin_unlock(&ubi->wl_lock);
+
+			err = ensure_wear_leveling(ubi, 1);
+		} else if (in_wl_tree(e, &ubi->used)) {
+			rb_erase(&e->u.rb, &ubi->used);
+			wl_tree_add(e, &ubi->scrub);
+			spin_unlock(&ubi->wl_lock);
+
+			err = ensure_wear_leveling(ubi, 1);
+		} else if (in_wl_tree(e, &ubi->free)) {
+			rb_erase(&e->u.rb, &ubi->free);
+			ubi->free_count--;
+			spin_unlock(&ubi->wl_lock);
+
+			/*
+			 * This PEB is empty we can schedule it for
+			 * erasure right away. No wear leveling needed.
+			 */
+			err = schedule_erase(ubi, e, UBI_UNKNOWN, UBI_UNKNOWN,
+					     force ? 0 : 1, true);
+		} else {
+			spin_unlock(&ubi->wl_lock);
+			err = -EAGAIN;
+		}
+
+		if (!err && !force)
+			err = -EUCLEAN;
+	} else {
+		err = 0;
+	}
+
+out_resume:
+	up_write(&ubi->work_sem);
+out:
+
+	return err;
+}
+
+/**
+ * tree_destroy - destroy an RB-tree.
+ * @ubi: UBI device description object
+ * @root: the root of the tree to destroy
+ */
+static void tree_destroy(struct ubi_device *ubi, struct rb_root *root)
+{
+	struct rb_node *rb;
+	struct ubi_wl_entry *e;
+
+	rb = root->rb_node;
+	while (rb) {
+		if (rb->rb_left)
+			rb = rb->rb_left;
+		else if (rb->rb_right)
+			rb = rb->rb_right;
+		else {
+			e = rb_entry(rb, struct ubi_wl_entry, u.rb);
+
+			rb = rb_parent(rb);
+			if (rb) {
+				if (rb->rb_left == &e->u.rb)
+					rb->rb_left = NULL;
+				else
+					rb->rb_right = NULL;
+			}
+
+			wl_entry_destroy(ubi, e);
+		}
+	}
+}
+
+/**
+ * ubi_thread - UBI background thread.
+ * @u: the UBI device description object pointer
+ */
+int ubi_thread(void *u)
+{
+	int failures = 0;
+	struct ubi_device *ubi = u;
+
+	ubi_msg(ubi, "background thread \"%s\" started, PID %d",
+		ubi->bgt_name, task_pid_nr(current));
+
+	set_freezable();
+	for (;;) {
+		int err;
+
+		if (kthread_should_stop())
+			break;
+
+		if (try_to_freeze())
+			continue;
+
+		spin_lock(&ubi->wl_lock);
+		if (list_empty(&ubi->works) || ubi->ro_mode ||
+		    !ubi->thread_enabled || ubi_dbg_is_bgt_disabled(ubi)) {
+			set_current_state(TASK_INTERRUPTIBLE);
+			spin_unlock(&ubi->wl_lock);
+
+			/*
+			 * Check kthread_should_stop() after we set the task
+			 * state to guarantee that we either see the stop bit
+			 * and exit or the task state is reset to runnable such
+			 * that it's not scheduled out indefinitely and detects
+			 * the stop bit at kthread_should_stop().
+			 */
+			if (kthread_should_stop()) {
+				set_current_state(TASK_RUNNING);
+				break;
+			}
+
+			schedule();
+			continue;
+		}
+		spin_unlock(&ubi->wl_lock);
+
+		err = do_work(ubi);
+		if (err) {
+			ubi_err(ubi, "%s: work failed with error code %d",
+				ubi->bgt_name, err);
+			if (failures++ > WL_MAX_FAILURES) {
+				/*
+				 * Too many failures, disable the thread and
+				 * switch to read-only mode.
+				 */
+				ubi_msg(ubi, "%s: %d consecutive failures",
+					ubi->bgt_name, WL_MAX_FAILURES);
+				ubi_ro_mode(ubi);
+				ubi->thread_enabled = 0;
+				continue;
+			}
+		} else
+			failures = 0;
+
+		cond_resched();
+	}
+
+	dbg_wl("background thread \"%s\" is killed", ubi->bgt_name);
+	ubi->thread_enabled = 0;
+	return 0;
+}
+
+/**
+ * shutdown_work - shutdown all pending works.
+ * @ubi: UBI device description object
+ */
+static void shutdown_work(struct ubi_device *ubi)
+{
+	while (!list_empty(&ubi->works)) {
+		struct ubi_work *wrk;
+
+		wrk = list_entry(ubi->works.next, struct ubi_work, list);
+		list_del(&wrk->list);
+		wrk->func(ubi, wrk, 1);
+		ubi->works_count -= 1;
+		ubi_assert(ubi->works_count >= 0);
+	}
+}
+
+/**
+ * erase_aeb - erase a PEB given in UBI attach info PEB
+ * @ubi: UBI device description object
+ * @aeb: UBI attach info PEB
+ * @sync: If true, erase synchronously. Otherwise schedule for erasure
+ */
+static int erase_aeb(struct ubi_device *ubi, struct ubi_ainf_peb *aeb, bool sync)
+{
+	struct ubi_wl_entry *e;
+	int err;
+
+	e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
+	if (!e)
+		return -ENOMEM;
+
+	e->pnum = aeb->pnum;
+	e->ec = aeb->ec;
+	ubi->lookuptbl[e->pnum] = e;
+
+	if (sync) {
+		err = sync_erase(ubi, e, false);
+		if (err)
+			goto out_free;
+
+		wl_tree_add(e, &ubi->free);
+		ubi->free_count++;
+	} else {
+		err = schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0, false);
+		if (err)
+			goto out_free;
+	}
+
+	return 0;
+
+out_free:
+	wl_entry_destroy(ubi, e);
+
+	return err;
+}
+
+/**
+ * ubi_wl_init - initialize the WL sub-system using attaching information.
+ * @ubi: UBI device description object
+ * @ai: attaching information
+ *
+ * This function returns zero in case of success, and a negative error code in
+ * case of failure.
+ */
+int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
+{
+	int err, i, reserved_pebs, found_pebs = 0;
+	struct rb_node *rb1, *rb2;
+	struct ubi_ainf_volume *av;
+	struct ubi_ainf_peb *aeb, *tmp;
+	struct ubi_wl_entry *e;
+
+	ubi->used = ubi->erroneous = ubi->free = ubi->scrub = RB_ROOT;
+	spin_lock_init(&ubi->wl_lock);
+	mutex_init(&ubi->move_mutex);
+	init_rwsem(&ubi->work_sem);
+	ubi->max_ec = ai->max_ec;
+	INIT_LIST_HEAD(&ubi->works);
+
+	sprintf(ubi->bgt_name, UBI_BGT_NAME_PATTERN, ubi->ubi_num);
+
+	err = -ENOMEM;
+	ubi->lookuptbl = kcalloc(ubi->peb_count, sizeof(void *), GFP_KERNEL);
+	if (!ubi->lookuptbl)
+		return err;
+
+	for (i = 0; i < UBI_PROT_QUEUE_LEN; i++)
+		INIT_LIST_HEAD(&ubi->pq[i]);
+	ubi->pq_head = 0;
+
+	ubi->free_count = 0;
+	list_for_each_entry_safe(aeb, tmp, &ai->erase, u.list) {
+		cond_resched();
+
+		err = erase_aeb(ubi, aeb, false);
+		if (err)
+			goto out_free;
+
+		found_pebs++;
+	}
+
+	list_for_each_entry(aeb, &ai->free, u.list) {
+		cond_resched();
+
+		e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
+		if (!e) {
+			err = -ENOMEM;
+			goto out_free;
+		}
+
+		e->pnum = aeb->pnum;
+		e->ec = aeb->ec;
+		ubi_assert(e->ec >= 0);
+
+		wl_tree_add(e, &ubi->free);
+		ubi->free_count++;
+
+		ubi->lookuptbl[e->pnum] = e;
+
+		found_pebs++;
+	}
+
+	ubi_rb_for_each_entry(rb1, av, &ai->volumes, rb) {
+		ubi_rb_for_each_entry(rb2, aeb, &av->root, u.rb) {
+			cond_resched();
+
+			e = kmem_cache_alloc(ubi_wl_entry_slab, GFP_KERNEL);
+			if (!e) {
+				err = -ENOMEM;
+				goto out_free;
+			}
+
+			e->pnum = aeb->pnum;
+			e->ec = aeb->ec;
+			ubi->lookuptbl[e->pnum] = e;
+
+			if (!aeb->scrub) {
+				dbg_wl("add PEB %d EC %d to the used tree",
+				       e->pnum, e->ec);
+				wl_tree_add(e, &ubi->used);
+			} else {
+				dbg_wl("add PEB %d EC %d to the scrub tree",
+				       e->pnum, e->ec);
+				wl_tree_add(e, &ubi->scrub);
+			}
+
+			found_pebs++;
+		}
+	}
+
+	list_for_each_entry(aeb, &ai->fastmap, u.list) {
+		cond_resched();
+
+		e = ubi_find_fm_block(ubi, aeb->pnum);
+
+		if (e) {
+			ubi_assert(!ubi->lookuptbl[e->pnum]);
+			ubi->lookuptbl[e->pnum] = e;
+		} else {
+			bool sync = false;
+
+			/*
+			 * Usually old Fastmap PEBs are scheduled for erasure
+			 * and we don't have to care about them but if we face
+			 * an power cut before scheduling them we need to
+			 * take care of them here.
+			 */
+			if (ubi->lookuptbl[aeb->pnum])
+				continue;
+
+			/*
+			 * The fastmap update code might not find a free PEB for
+			 * writing the fastmap anchor to and then reuses the
+			 * current fastmap anchor PEB. When this PEB gets erased
+			 * and a power cut happens before it is written again we
+			 * must make sure that the fastmap attach code doesn't
+			 * find any outdated fastmap anchors, hence we erase the
+			 * outdated fastmap anchor PEBs synchronously here.
+			 */
+			if (aeb->vol_id == UBI_FM_SB_VOLUME_ID)
+				sync = true;
+
+			err = erase_aeb(ubi, aeb, sync);
+			if (err)
+				goto out_free;
+		}
+
+		found_pebs++;
+	}
+
+	dbg_wl("found %i PEBs", found_pebs);
+
+	ubi_assert(ubi->good_peb_count == found_pebs);
+
+	reserved_pebs = WL_RESERVED_PEBS;
+	ubi_fastmap_init(ubi, &reserved_pebs);
+
+	if (ubi->avail_pebs < reserved_pebs) {
+		ubi_err(ubi, "no enough physical eraseblocks (%d, need %d)",
+			ubi->avail_pebs, reserved_pebs);
+		if (ubi->corr_peb_count)
+			ubi_err(ubi, "%d PEBs are corrupted and not used",
+				ubi->corr_peb_count);
+		err = -ENOSPC;
+		goto out_free;
+	}
+	ubi->avail_pebs -= reserved_pebs;
+	ubi->rsvd_pebs += reserved_pebs;
+
+	/* Schedule wear-leveling if needed */
+	err = ensure_wear_leveling(ubi, 0);
+	if (err)
+		goto out_free;
+
+#ifdef CONFIG_MTD_UBI_FASTMAP
+	if (!ubi->ro_mode && !ubi->fm_disabled)
+		ubi_ensure_anchor_pebs(ubi);
+#endif
+	return 0;
+
+out_free:
+	shutdown_work(ubi);
+	tree_destroy(ubi, &ubi->used);
+	tree_destroy(ubi, &ubi->free);
+	tree_destroy(ubi, &ubi->scrub);
+	kfree(ubi->lookuptbl);
+	return err;
+}
+
+/**
+ * protection_queue_destroy - destroy the protection queue.
+ * @ubi: UBI device description object
+ */
+static void protection_queue_destroy(struct ubi_device *ubi)
+{
+	int i;
+	struct ubi_wl_entry *e, *tmp;
+
+	for (i = 0; i < UBI_PROT_QUEUE_LEN; ++i) {
+		list_for_each_entry_safe(e, tmp, &ubi->pq[i], u.list) {
+			list_del(&e->u.list);
+			wl_entry_destroy(ubi, e);
+		}
+	}
+}
+
+/**
+ * ubi_wl_close - close the wear-leveling sub-system.
+ * @ubi: UBI device description object
+ */
+void ubi_wl_close(struct ubi_device *ubi)
+{
+	dbg_wl("close the WL sub-system");
+	ubi_fastmap_close(ubi);
+	shutdown_work(ubi);
+	protection_queue_destroy(ubi);
+	tree_destroy(ubi, &ubi->used);
+	tree_destroy(ubi, &ubi->erroneous);
+	tree_destroy(ubi, &ubi->free);
+	tree_destroy(ubi, &ubi->scrub);
+	kfree(ubi->lookuptbl);
+}
+
+/**
+ * self_check_ec - make sure that the erase counter of a PEB is correct.
+ * @ubi: UBI device description object
+ * @pnum: the physical eraseblock number to check
+ * @ec: the erase counter to check
+ *
+ * This function returns zero if the erase counter of physical eraseblock @pnum
+ * is equivalent to @ec, and a negative error code if not or if an error
+ * occurred.
+ */
+static int self_check_ec(struct ubi_device *ubi, int pnum, int ec)
+{
+	int err;
+	long long read_ec;
+	struct ubi_ec_hdr *ec_hdr;
+
+	if (!ubi_dbg_chk_gen(ubi))
+		return 0;
+
+	ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_NOFS);
+	if (!ec_hdr)
+		return -ENOMEM;
+
+	err = ubi_io_read_ec_hdr(ubi, pnum, ec_hdr, 0);
+	if (err && err != UBI_IO_BITFLIPS) {
+		/* The header does not have to exist */
+		err = 0;
+		goto out_free;
+	}
+
+	read_ec = be64_to_cpu(ec_hdr->ec);
+	if (ec != read_ec && read_ec - ec > 1) {
+		ubi_err(ubi, "self-check failed for PEB %d", pnum);
+		ubi_err(ubi, "read EC is %lld, should be %d", read_ec, ec);
+		dump_stack();
+		err = 1;
+	} else
+		err = 0;
+
+out_free:
+	kfree(ec_hdr);
+	return err;
+}
+
+/**
+ * self_check_in_wl_tree - check that wear-leveling entry is in WL RB-tree.
+ * @ubi: UBI device description object
+ * @e: the wear-leveling entry to check
+ * @root: the root of the tree
+ *
+ * This function returns zero if @e is in the @root RB-tree and %-EINVAL if it
+ * is not.
+ */
+static int self_check_in_wl_tree(const struct ubi_device *ubi,
+				 struct ubi_wl_entry *e, struct rb_root *root)
+{
+	if (!ubi_dbg_chk_gen(ubi))
+		return 0;
+
+	if (in_wl_tree(e, root))
+		return 0;
+
+	ubi_err(ubi, "self-check failed for PEB %d, EC %d, RB-tree %p ",
+		e->pnum, e->ec, root);
+	dump_stack();
+	return -EINVAL;
+}
+
+/**
+ * self_check_in_pq - check if wear-leveling entry is in the protection
+ *                        queue.
+ * @ubi: UBI device description object
+ * @e: the wear-leveling entry to check
+ *
+ * This function returns zero if @e is in @ubi->pq and %-EINVAL if it is not.
+ */
+static int self_check_in_pq(const struct ubi_device *ubi,
+			    struct ubi_wl_entry *e)
+{
+	if (!ubi_dbg_chk_gen(ubi))
+		return 0;
+
+	if (in_pq(ubi, e))
+		return 0;
+
+	ubi_err(ubi, "self-check failed for PEB %d, EC %d, Protect queue",
+		e->pnum, e->ec);
+	dump_stack();
+	return -EINVAL;
+}
+#ifndef CONFIG_MTD_UBI_FASTMAP
+static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi)
+{
+	struct ubi_wl_entry *e;
+
+	e = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF);
+	self_check_in_wl_tree(ubi, e, &ubi->free);
+	ubi->free_count--;
+	ubi_assert(ubi->free_count >= 0);
+	rb_erase(&e->u.rb, &ubi->free);
+
+	return e;
+}
+
+/**
+ * produce_free_peb - produce a free physical eraseblock.
+ * @ubi: UBI device description object
+ *
+ * This function tries to make a free PEB by means of synchronous execution of
+ * pending works. This may be needed if, for example the background thread is
+ * disabled. Returns zero in case of success and a negative error code in case
+ * of failure.
+ */
+static int produce_free_peb(struct ubi_device *ubi)
+{
+	int err;
+
+	while (!ubi->free.rb_node && ubi->works_count) {
+		spin_unlock(&ubi->wl_lock);
+
+		dbg_wl("do one work synchronously");
+		err = do_work(ubi);
+
+		spin_lock(&ubi->wl_lock);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+/**
+ * ubi_wl_get_peb - get a physical eraseblock.
+ * @ubi: UBI device description object
+ *
+ * This function returns a physical eraseblock in case of success and a
+ * negative error code in case of failure.
+ * Returns with ubi->fm_eba_sem held in read mode!
+ */
+int ubi_wl_get_peb(struct ubi_device *ubi)
+{
+	int err;
+	struct ubi_wl_entry *e;
+
+retry:
+	down_read(&ubi->fm_eba_sem);
+	spin_lock(&ubi->wl_lock);
+	if (!ubi->free.rb_node) {
+		if (ubi->works_count == 0) {
+			ubi_err(ubi, "no free eraseblocks");
+			ubi_assert(list_empty(&ubi->works));
+			spin_unlock(&ubi->wl_lock);
+			return -ENOSPC;
+		}
+
+		err = produce_free_peb(ubi);
+		if (err < 0) {
+			spin_unlock(&ubi->wl_lock);
+			return err;
+		}
+		spin_unlock(&ubi->wl_lock);
+		up_read(&ubi->fm_eba_sem);
+		goto retry;
+
+	}
+	e = wl_get_wle(ubi);
+	prot_queue_add(ubi, e);
+	spin_unlock(&ubi->wl_lock);
+
+	err = ubi_self_check_all_ff(ubi, e->pnum, ubi->vid_hdr_aloffset,
+				    ubi->peb_size - ubi->vid_hdr_aloffset);
+	if (err) {
+		ubi_err(ubi, "new PEB %d does not contain all 0xFF bytes", e->pnum);
+		return err;
+	}
+
+	return e->pnum;
+}
+#else
+#include "fastmap-wl.c"
+#endif
diff --git a/drivers/mtd/ubi/wl.h b/drivers/mtd/ubi/wl.h
new file mode 100644
index 0000000000..5ebe374a08
--- /dev/null
+++ b/drivers/mtd/ubi/wl.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef UBI_WL_H
+#define UBI_WL_H
+#ifdef CONFIG_MTD_UBI_FASTMAP
+static void update_fastmap_work_fn(struct work_struct *wrk);
+static struct ubi_wl_entry *find_anchor_wl_entry(struct rb_root *root);
+static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi);
+static struct ubi_wl_entry *next_peb_for_wl(struct ubi_device *ubi);
+static bool need_wear_leveling(struct ubi_device *ubi);
+static void ubi_fastmap_close(struct ubi_device *ubi);
+static inline void ubi_fastmap_init(struct ubi_device *ubi, int *count)
+{
+	/* Reserve enough LEBs to store two fastmaps. */
+	*count += (ubi->fm_size / ubi->leb_size) * 2;
+	INIT_WORK(&ubi->fm_work, update_fastmap_work_fn);
+}
+static struct ubi_wl_entry *may_reserve_for_fm(struct ubi_device *ubi,
+					       struct ubi_wl_entry *e,
+					       struct rb_root *root);
+#else /* !CONFIG_MTD_UBI_FASTMAP */
+static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi);
+static inline void ubi_fastmap_close(struct ubi_device *ubi) { }
+static inline void ubi_fastmap_init(struct ubi_device *ubi, int *count) { }
+static struct ubi_wl_entry *may_reserve_for_fm(struct ubi_device *ubi,
+					       struct ubi_wl_entry *e,
+					       struct rb_root *root) {
+	return e;
+}
+#endif /* CONFIG_MTD_UBI_FASTMAP */
+#endif /* UBI_WL_H */