Adding upstream version 5.10.209.upstream/5.10.209upstream

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

1 files changed, 1709 insertions, 0 deletions

diff --git a/drivers/mtd/ubi/eba.c b/drivers/mtd/ubi/eba.c
new file mode 100644
index 000000000..b4cdf2351
--- /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;
+};
+
+/**
+ * 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->entries);
+	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 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
+ * @vid_hdr: VID header of the @from physical eraseblock
+ *
+ * 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
+ *
+ * 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;
+}