Adding upstream version 6.1.76.upstream/6.1.76upstream

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

1 files changed, 3397 insertions, 0 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
new file mode 100644
index 000000000..0ec85d159
--- /dev/null
+++ b/drivers/md/dm.c
@@ -0,0 +1,3397 @@
+/*
+ * Copyright (C) 2001, 2002 Sistina Software (UK) Limited.
+ * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-core.h"
+#include "dm-rq.h"
+#include "dm-uevent.h"
+#include "dm-ima.h"
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/sched/mm.h>
+#include <linux/sched/signal.h>
+#include <linux/blkpg.h>
+#include <linux/bio.h>
+#include <linux/mempool.h>
+#include <linux/dax.h>
+#include <linux/slab.h>
+#include <linux/idr.h>
+#include <linux/uio.h>
+#include <linux/hdreg.h>
+#include <linux/delay.h>
+#include <linux/wait.h>
+#include <linux/pr.h>
+#include <linux/refcount.h>
+#include <linux/part_stat.h>
+#include <linux/blk-crypto.h>
+#include <linux/blk-crypto-profile.h>
+
+#define DM_MSG_PREFIX "core"
+
+/*
+ * Cookies are numeric values sent with CHANGE and REMOVE
+ * uevents while resuming, removing or renaming the device.
+ */
+#define DM_COOKIE_ENV_VAR_NAME "DM_COOKIE"
+#define DM_COOKIE_LENGTH 24
+
+/*
+ * For REQ_POLLED fs bio, this flag is set if we link mapped underlying
+ * dm_io into one list, and reuse bio->bi_private as the list head. Before
+ * ending this fs bio, we will recover its ->bi_private.
+ */
+#define REQ_DM_POLL_LIST	REQ_DRV
+
+static const char *_name = DM_NAME;
+
+static unsigned int major = 0;
+static unsigned int _major = 0;
+
+static DEFINE_IDR(_minor_idr);
+
+static DEFINE_SPINLOCK(_minor_lock);
+
+static void do_deferred_remove(struct work_struct *w);
+
+static DECLARE_WORK(deferred_remove_work, do_deferred_remove);
+
+static struct workqueue_struct *deferred_remove_workqueue;
+
+atomic_t dm_global_event_nr = ATOMIC_INIT(0);
+DECLARE_WAIT_QUEUE_HEAD(dm_global_eventq);
+
+void dm_issue_global_event(void)
+{
+	atomic_inc(&dm_global_event_nr);
+	wake_up(&dm_global_eventq);
+}
+
+DEFINE_STATIC_KEY_FALSE(stats_enabled);
+DEFINE_STATIC_KEY_FALSE(swap_bios_enabled);
+DEFINE_STATIC_KEY_FALSE(zoned_enabled);
+
+/*
+ * One of these is allocated (on-stack) per original bio.
+ */
+struct clone_info {
+	struct dm_table *map;
+	struct bio *bio;
+	struct dm_io *io;
+	sector_t sector;
+	unsigned int sector_count;
+	bool is_abnormal_io:1;
+	bool submit_as_polled:1;
+};
+
+static inline struct dm_target_io *clone_to_tio(struct bio *clone)
+{
+	return container_of(clone, struct dm_target_io, clone);
+}
+
+void *dm_per_bio_data(struct bio *bio, size_t data_size)
+{
+	if (!dm_tio_flagged(clone_to_tio(bio), DM_TIO_INSIDE_DM_IO))
+		return (char *)bio - DM_TARGET_IO_BIO_OFFSET - data_size;
+	return (char *)bio - DM_IO_BIO_OFFSET - data_size;
+}
+EXPORT_SYMBOL_GPL(dm_per_bio_data);
+
+struct bio *dm_bio_from_per_bio_data(void *data, size_t data_size)
+{
+	struct dm_io *io = (struct dm_io *)((char *)data + data_size);
+	if (io->magic == DM_IO_MAGIC)
+		return (struct bio *)((char *)io + DM_IO_BIO_OFFSET);
+	BUG_ON(io->magic != DM_TIO_MAGIC);
+	return (struct bio *)((char *)io + DM_TARGET_IO_BIO_OFFSET);
+}
+EXPORT_SYMBOL_GPL(dm_bio_from_per_bio_data);
+
+unsigned int dm_bio_get_target_bio_nr(const struct bio *bio)
+{
+	return container_of(bio, struct dm_target_io, clone)->target_bio_nr;
+}
+EXPORT_SYMBOL_GPL(dm_bio_get_target_bio_nr);
+
+#define MINOR_ALLOCED ((void *)-1)
+
+#define DM_NUMA_NODE NUMA_NO_NODE
+static int dm_numa_node = DM_NUMA_NODE;
+
+#define DEFAULT_SWAP_BIOS	(8 * 1048576 / PAGE_SIZE)
+static int swap_bios = DEFAULT_SWAP_BIOS;
+static int get_swap_bios(void)
+{
+	int latch = READ_ONCE(swap_bios);
+	if (unlikely(latch <= 0))
+		latch = DEFAULT_SWAP_BIOS;
+	return latch;
+}
+
+struct table_device {
+	struct list_head list;
+	refcount_t count;
+	struct dm_dev dm_dev;
+};
+
+/*
+ * Bio-based DM's mempools' reserved IOs set by the user.
+ */
+#define RESERVED_BIO_BASED_IOS		16
+static unsigned int reserved_bio_based_ios = RESERVED_BIO_BASED_IOS;
+
+static int __dm_get_module_param_int(int *module_param, int min, int max)
+{
+	int param = READ_ONCE(*module_param);
+	int modified_param = 0;
+	bool modified = true;
+
+	if (param < min)
+		modified_param = min;
+	else if (param > max)
+		modified_param = max;
+	else
+		modified = false;
+
+	if (modified) {
+		(void)cmpxchg(module_param, param, modified_param);
+		param = modified_param;
+	}
+
+	return param;
+}
+
+unsigned int __dm_get_module_param(unsigned int *module_param, unsigned int def, unsigned int max)
+{
+	unsigned int param = READ_ONCE(*module_param);
+	unsigned int modified_param = 0;
+
+	if (!param)
+		modified_param = def;
+	else if (param > max)
+		modified_param = max;
+
+	if (modified_param) {
+		(void)cmpxchg(module_param, param, modified_param);
+		param = modified_param;
+	}
+
+	return param;
+}
+
+unsigned int dm_get_reserved_bio_based_ios(void)
+{
+	return __dm_get_module_param(&reserved_bio_based_ios,
+				     RESERVED_BIO_BASED_IOS, DM_RESERVED_MAX_IOS);
+}
+EXPORT_SYMBOL_GPL(dm_get_reserved_bio_based_ios);
+
+static unsigned int dm_get_numa_node(void)
+{
+	return __dm_get_module_param_int(&dm_numa_node,
+					 DM_NUMA_NODE, num_online_nodes() - 1);
+}
+
+static int __init local_init(void)
+{
+	int r;
+
+	r = dm_uevent_init();
+	if (r)
+		return r;
+
+	deferred_remove_workqueue = alloc_workqueue("kdmremove", WQ_UNBOUND, 1);
+	if (!deferred_remove_workqueue) {
+		r = -ENOMEM;
+		goto out_uevent_exit;
+	}
+
+	_major = major;
+	r = register_blkdev(_major, _name);
+	if (r < 0)
+		goto out_free_workqueue;
+
+	if (!_major)
+		_major = r;
+
+	return 0;
+
+out_free_workqueue:
+	destroy_workqueue(deferred_remove_workqueue);
+out_uevent_exit:
+	dm_uevent_exit();
+
+	return r;
+}
+
+static void local_exit(void)
+{
+	destroy_workqueue(deferred_remove_workqueue);
+
+	unregister_blkdev(_major, _name);
+	dm_uevent_exit();
+
+	_major = 0;
+
+	DMINFO("cleaned up");
+}
+
+static int (*_inits[])(void) __initdata = {
+	local_init,
+	dm_target_init,
+	dm_linear_init,
+	dm_stripe_init,
+	dm_io_init,
+	dm_kcopyd_init,
+	dm_interface_init,
+	dm_statistics_init,
+};
+
+static void (*_exits[])(void) = {
+	local_exit,
+	dm_target_exit,
+	dm_linear_exit,
+	dm_stripe_exit,
+	dm_io_exit,
+	dm_kcopyd_exit,
+	dm_interface_exit,
+	dm_statistics_exit,
+};
+
+static int __init dm_init(void)
+{
+	const int count = ARRAY_SIZE(_inits);
+	int r, i;
+
+#if (IS_ENABLED(CONFIG_IMA) && !IS_ENABLED(CONFIG_IMA_DISABLE_HTABLE))
+	DMWARN("CONFIG_IMA_DISABLE_HTABLE is disabled."
+	       " Duplicate IMA measurements will not be recorded in the IMA log.");
+#endif
+
+	for (i = 0; i < count; i++) {
+		r = _inits[i]();
+		if (r)
+			goto bad;
+	}
+
+	return 0;
+bad:
+	while (i--)
+		_exits[i]();
+
+	return r;
+}
+
+static void __exit dm_exit(void)
+{
+	int i = ARRAY_SIZE(_exits);
+
+	while (i--)
+		_exits[i]();
+
+	/*
+	 * Should be empty by this point.
+	 */
+	idr_destroy(&_minor_idr);
+}
+
+/*
+ * Block device functions
+ */
+int dm_deleting_md(struct mapped_device *md)
+{
+	return test_bit(DMF_DELETING, &md->flags);
+}
+
+static int dm_blk_open(struct block_device *bdev, fmode_t mode)
+{
+	struct mapped_device *md;
+
+	spin_lock(&_minor_lock);
+
+	md = bdev->bd_disk->private_data;
+	if (!md)
+		goto out;
+
+	if (test_bit(DMF_FREEING, &md->flags) ||
+	    dm_deleting_md(md)) {
+		md = NULL;
+		goto out;
+	}
+
+	dm_get(md);
+	atomic_inc(&md->open_count);
+out:
+	spin_unlock(&_minor_lock);
+
+	return md ? 0 : -ENXIO;
+}
+
+static void dm_blk_close(struct gendisk *disk, fmode_t mode)
+{
+	struct mapped_device *md;
+
+	spin_lock(&_minor_lock);
+
+	md = disk->private_data;
+	if (WARN_ON(!md))
+		goto out;
+
+	if (atomic_dec_and_test(&md->open_count) &&
+	    (test_bit(DMF_DEFERRED_REMOVE, &md->flags)))
+		queue_work(deferred_remove_workqueue, &deferred_remove_work);
+
+	dm_put(md);
+out:
+	spin_unlock(&_minor_lock);
+}
+
+int dm_open_count(struct mapped_device *md)
+{
+	return atomic_read(&md->open_count);
+}
+
+/*
+ * Guarantees nothing is using the device before it's deleted.
+ */
+int dm_lock_for_deletion(struct mapped_device *md, bool mark_deferred, bool only_deferred)
+{
+	int r = 0;
+
+	spin_lock(&_minor_lock);
+
+	if (dm_open_count(md)) {
+		r = -EBUSY;
+		if (mark_deferred)
+			set_bit(DMF_DEFERRED_REMOVE, &md->flags);
+	} else if (only_deferred && !test_bit(DMF_DEFERRED_REMOVE, &md->flags))
+		r = -EEXIST;
+	else
+		set_bit(DMF_DELETING, &md->flags);
+
+	spin_unlock(&_minor_lock);
+
+	return r;
+}
+
+int dm_cancel_deferred_remove(struct mapped_device *md)
+{
+	int r = 0;
+
+	spin_lock(&_minor_lock);
+
+	if (test_bit(DMF_DELETING, &md->flags))
+		r = -EBUSY;
+	else
+		clear_bit(DMF_DEFERRED_REMOVE, &md->flags);
+
+	spin_unlock(&_minor_lock);
+
+	return r;
+}
+
+static void do_deferred_remove(struct work_struct *w)
+{
+	dm_deferred_remove();
+}
+
+static int dm_blk_getgeo(struct block_device *bdev, struct hd_geometry *geo)
+{
+	struct mapped_device *md = bdev->bd_disk->private_data;
+
+	return dm_get_geometry(md, geo);
+}
+
+static int dm_prepare_ioctl(struct mapped_device *md, int *srcu_idx,
+			    struct block_device **bdev)
+{
+	struct dm_target *ti;
+	struct dm_table *map;
+	int r;
+
+retry:
+	r = -ENOTTY;
+	map = dm_get_live_table(md, srcu_idx);
+	if (!map || !dm_table_get_size(map))
+		return r;
+
+	/* We only support devices that have a single target */
+	if (map->num_targets != 1)
+		return r;
+
+	ti = dm_table_get_target(map, 0);
+	if (!ti->type->prepare_ioctl)
+		return r;
+
+	if (dm_suspended_md(md))
+		return -EAGAIN;
+
+	r = ti->type->prepare_ioctl(ti, bdev);
+	if (r == -ENOTCONN && !fatal_signal_pending(current)) {
+		dm_put_live_table(md, *srcu_idx);
+		msleep(10);
+		goto retry;
+	}
+
+	return r;
+}
+
+static void dm_unprepare_ioctl(struct mapped_device *md, int srcu_idx)
+{
+	dm_put_live_table(md, srcu_idx);
+}
+
+static int dm_blk_ioctl(struct block_device *bdev, fmode_t mode,
+			unsigned int cmd, unsigned long arg)
+{
+	struct mapped_device *md = bdev->bd_disk->private_data;
+	int r, srcu_idx;
+
+	r = dm_prepare_ioctl(md, &srcu_idx, &bdev);
+	if (r < 0)
+		goto out;
+
+	if (r > 0) {
+		/*
+		 * Target determined this ioctl is being issued against a
+		 * subset of the parent bdev; require extra privileges.
+		 */
+		if (!capable(CAP_SYS_RAWIO)) {
+			DMDEBUG_LIMIT(
+	"%s: sending ioctl %x to DM device without required privilege.",
+				current->comm, cmd);
+			r = -ENOIOCTLCMD;
+			goto out;
+		}
+	}
+
+	if (!bdev->bd_disk->fops->ioctl)
+		r = -ENOTTY;
+	else
+		r = bdev->bd_disk->fops->ioctl(bdev, mode, cmd, arg);
+out:
+	dm_unprepare_ioctl(md, srcu_idx);
+	return r;
+}
+
+u64 dm_start_time_ns_from_clone(struct bio *bio)
+{
+	return jiffies_to_nsecs(clone_to_tio(bio)->io->start_time);
+}
+EXPORT_SYMBOL_GPL(dm_start_time_ns_from_clone);
+
+static bool bio_is_flush_with_data(struct bio *bio)
+{
+	return ((bio->bi_opf & REQ_PREFLUSH) && bio->bi_iter.bi_size);
+}
+
+static void dm_io_acct(struct dm_io *io, bool end)
+{
+	struct dm_stats_aux *stats_aux = &io->stats_aux;
+	unsigned long start_time = io->start_time;
+	struct mapped_device *md = io->md;
+	struct bio *bio = io->orig_bio;
+	unsigned int sectors;
+
+	/*
+	 * If REQ_PREFLUSH set, don't account payload, it will be
+	 * submitted (and accounted) after this flush completes.
+	 */
+	if (bio_is_flush_with_data(bio))
+		sectors = 0;
+	else if (likely(!(dm_io_flagged(io, DM_IO_WAS_SPLIT))))
+		sectors = bio_sectors(bio);
+	else
+		sectors = io->sectors;
+
+	if (!end)
+		bdev_start_io_acct(bio->bi_bdev, sectors, bio_op(bio),
+				   start_time);
+	else
+		bdev_end_io_acct(bio->bi_bdev, bio_op(bio), start_time);
+
+	if (static_branch_unlikely(&stats_enabled) &&
+	    unlikely(dm_stats_used(&md->stats))) {
+		sector_t sector;
+
+		if (likely(!dm_io_flagged(io, DM_IO_WAS_SPLIT)))
+			sector = bio->bi_iter.bi_sector;
+		else
+			sector = bio_end_sector(bio) - io->sector_offset;
+
+		dm_stats_account_io(&md->stats, bio_data_dir(bio),
+				    sector, sectors,
+				    end, start_time, stats_aux);
+	}
+}
+
+static void __dm_start_io_acct(struct dm_io *io)
+{
+	dm_io_acct(io, false);
+}
+
+static void dm_start_io_acct(struct dm_io *io, struct bio *clone)
+{
+	/*
+	 * Ensure IO accounting is only ever started once.
+	 */
+	if (dm_io_flagged(io, DM_IO_ACCOUNTED))
+		return;
+
+	/* Expect no possibility for race unless DM_TIO_IS_DUPLICATE_BIO. */
+	if (!clone || likely(dm_tio_is_normal(clone_to_tio(clone)))) {
+		dm_io_set_flag(io, DM_IO_ACCOUNTED);
+	} else {
+		unsigned long flags;
+		/* Can afford locking given DM_TIO_IS_DUPLICATE_BIO */
+		spin_lock_irqsave(&io->lock, flags);
+		if (dm_io_flagged(io, DM_IO_ACCOUNTED)) {
+			spin_unlock_irqrestore(&io->lock, flags);
+			return;
+		}
+		dm_io_set_flag(io, DM_IO_ACCOUNTED);
+		spin_unlock_irqrestore(&io->lock, flags);
+	}
+
+	__dm_start_io_acct(io);
+}
+
+static void dm_end_io_acct(struct dm_io *io)
+{
+	dm_io_acct(io, true);
+}
+
+static struct dm_io *alloc_io(struct mapped_device *md, struct bio *bio)
+{
+	struct dm_io *io;
+	struct dm_target_io *tio;
+	struct bio *clone;
+
+	clone = bio_alloc_clone(NULL, bio, GFP_NOIO, &md->mempools->io_bs);
+	tio = clone_to_tio(clone);
+	tio->flags = 0;
+	dm_tio_set_flag(tio, DM_TIO_INSIDE_DM_IO);
+	tio->io = NULL;
+
+	io = container_of(tio, struct dm_io, tio);
+	io->magic = DM_IO_MAGIC;
+	io->status = BLK_STS_OK;
+
+	/* one ref is for submission, the other is for completion */
+	atomic_set(&io->io_count, 2);
+	this_cpu_inc(*md->pending_io);
+	io->orig_bio = bio;
+	io->md = md;
+	spin_lock_init(&io->lock);
+	io->start_time = jiffies;
+	io->flags = 0;
+
+	if (static_branch_unlikely(&stats_enabled))
+		dm_stats_record_start(&md->stats, &io->stats_aux);
+
+	return io;
+}
+
+static void free_io(struct dm_io *io)
+{
+	bio_put(&io->tio.clone);
+}
+
+static struct bio *alloc_tio(struct clone_info *ci, struct dm_target *ti,
+			     unsigned int target_bio_nr, unsigned int *len, gfp_t gfp_mask)
+{
+	struct mapped_device *md = ci->io->md;
+	struct dm_target_io *tio;
+	struct bio *clone;
+
+	if (!ci->io->tio.io) {
+		/* the dm_target_io embedded in ci->io is available */
+		tio = &ci->io->tio;
+		/* alloc_io() already initialized embedded clone */
+		clone = &tio->clone;
+	} else {
+		clone = bio_alloc_clone(NULL, ci->bio, gfp_mask,
+					&md->mempools->bs);
+		if (!clone)
+			return NULL;
+
+		/* REQ_DM_POLL_LIST shouldn't be inherited */
+		clone->bi_opf &= ~REQ_DM_POLL_LIST;
+
+		tio = clone_to_tio(clone);
+		tio->flags = 0; /* also clears DM_TIO_INSIDE_DM_IO */
+	}
+
+	tio->magic = DM_TIO_MAGIC;
+	tio->io = ci->io;
+	tio->ti = ti;
+	tio->target_bio_nr = target_bio_nr;
+	tio->len_ptr = len;
+	tio->old_sector = 0;
+
+	/* Set default bdev, but target must bio_set_dev() before issuing IO */
+	clone->bi_bdev = md->disk->part0;
+	if (unlikely(ti->needs_bio_set_dev))
+		bio_set_dev(clone, md->disk->part0);
+
+	if (len) {
+		clone->bi_iter.bi_size = to_bytes(*len);
+		if (bio_integrity(clone))
+			bio_integrity_trim(clone);
+	}
+
+	return clone;
+}
+
+static void free_tio(struct bio *clone)
+{
+	if (dm_tio_flagged(clone_to_tio(clone), DM_TIO_INSIDE_DM_IO))
+		return;
+	bio_put(clone);
+}
+
+/*
+ * Add the bio to the list of deferred io.
+ */
+static void queue_io(struct mapped_device *md, struct bio *bio)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&md->deferred_lock, flags);
+	bio_list_add(&md->deferred, bio);
+	spin_unlock_irqrestore(&md->deferred_lock, flags);
+	queue_work(md->wq, &md->work);
+}
+
+/*
+ * Everyone (including functions in this file), should use this
+ * function to access the md->map field, and make sure they call
+ * dm_put_live_table() when finished.
+ */
+struct dm_table *dm_get_live_table(struct mapped_device *md,
+				   int *srcu_idx) __acquires(md->io_barrier)
+{
+	*srcu_idx = srcu_read_lock(&md->io_barrier);
+
+	return srcu_dereference(md->map, &md->io_barrier);
+}
+
+void dm_put_live_table(struct mapped_device *md,
+		       int srcu_idx) __releases(md->io_barrier)
+{
+	srcu_read_unlock(&md->io_barrier, srcu_idx);
+}
+
+void dm_sync_table(struct mapped_device *md)
+{
+	synchronize_srcu(&md->io_barrier);
+	synchronize_rcu_expedited();
+}
+
+/*
+ * A fast alternative to dm_get_live_table/dm_put_live_table.
+ * The caller must not block between these two functions.
+ */
+static struct dm_table *dm_get_live_table_fast(struct mapped_device *md) __acquires(RCU)
+{
+	rcu_read_lock();
+	return rcu_dereference(md->map);
+}
+
+static void dm_put_live_table_fast(struct mapped_device *md) __releases(RCU)
+{
+	rcu_read_unlock();
+}
+
+static char *_dm_claim_ptr = "I belong to device-mapper";
+
+/*
+ * Open a table device so we can use it as a map destination.
+ */
+static struct table_device *open_table_device(struct mapped_device *md,
+		dev_t dev, fmode_t mode)
+{
+	struct table_device *td;
+	struct block_device *bdev;
+	u64 part_off;
+	int r;
+
+	td = kmalloc_node(sizeof(*td), GFP_KERNEL, md->numa_node_id);
+	if (!td)
+		return ERR_PTR(-ENOMEM);
+	refcount_set(&td->count, 1);
+
+	bdev = blkdev_get_by_dev(dev, mode | FMODE_EXCL, _dm_claim_ptr);
+	if (IS_ERR(bdev)) {
+		r = PTR_ERR(bdev);
+		goto out_free_td;
+	}
+
+	/*
+	 * We can be called before the dm disk is added.  In that case we can't
+	 * register the holder relation here.  It will be done once add_disk was
+	 * called.
+	 */
+	if (md->disk->slave_dir) {
+		r = bd_link_disk_holder(bdev, md->disk);
+		if (r)
+			goto out_blkdev_put;
+	}
+
+	td->dm_dev.mode = mode;
+	td->dm_dev.bdev = bdev;
+	td->dm_dev.dax_dev = fs_dax_get_by_bdev(bdev, &part_off, NULL, NULL);
+	format_dev_t(td->dm_dev.name, dev);
+	list_add(&td->list, &md->table_devices);
+	return td;
+
+out_blkdev_put:
+	blkdev_put(bdev, mode | FMODE_EXCL);
+out_free_td:
+	kfree(td);
+	return ERR_PTR(r);
+}
+
+/*
+ * Close a table device that we've been using.
+ */
+static void close_table_device(struct table_device *td, struct mapped_device *md)
+{
+	if (md->disk->slave_dir)
+		bd_unlink_disk_holder(td->dm_dev.bdev, md->disk);
+	blkdev_put(td->dm_dev.bdev, td->dm_dev.mode | FMODE_EXCL);
+	put_dax(td->dm_dev.dax_dev);
+	list_del(&td->list);
+	kfree(td);
+}
+
+static struct table_device *find_table_device(struct list_head *l, dev_t dev,
+					      fmode_t mode)
+{
+	struct table_device *td;
+
+	list_for_each_entry(td, l, list)
+		if (td->dm_dev.bdev->bd_dev == dev && td->dm_dev.mode == mode)
+			return td;
+
+	return NULL;
+}
+
+int dm_get_table_device(struct mapped_device *md, dev_t dev, fmode_t mode,
+			struct dm_dev **result)
+{
+	struct table_device *td;
+
+	mutex_lock(&md->table_devices_lock);
+	td = find_table_device(&md->table_devices, dev, mode);
+	if (!td) {
+		td = open_table_device(md, dev, mode);
+		if (IS_ERR(td)) {
+			mutex_unlock(&md->table_devices_lock);
+			return PTR_ERR(td);
+		}
+	} else {
+		refcount_inc(&td->count);
+	}
+	mutex_unlock(&md->table_devices_lock);
+
+	*result = &td->dm_dev;
+	return 0;
+}
+
+void dm_put_table_device(struct mapped_device *md, struct dm_dev *d)
+{
+	struct table_device *td = container_of(d, struct table_device, dm_dev);
+
+	mutex_lock(&md->table_devices_lock);
+	if (refcount_dec_and_test(&td->count))
+		close_table_device(td, md);
+	mutex_unlock(&md->table_devices_lock);
+}
+
+static void free_table_devices(struct list_head *devices)
+{
+	struct list_head *tmp, *next;
+
+	list_for_each_safe(tmp, next, devices) {
+		struct table_device *td = list_entry(tmp, struct table_device, list);
+
+		DMWARN("dm_destroy: %s still exists with %d references",
+		       td->dm_dev.name, refcount_read(&td->count));
+		kfree(td);
+	}
+}
+
+/*
+ * Get the geometry associated with a dm device
+ */
+int dm_get_geometry(struct mapped_device *md, struct hd_geometry *geo)
+{
+	*geo = md->geometry;
+
+	return 0;
+}
+
+/*
+ * Set the geometry of a device.
+ */
+int dm_set_geometry(struct mapped_device *md, struct hd_geometry *geo)
+{
+	sector_t sz = (sector_t)geo->cylinders * geo->heads * geo->sectors;
+
+	if (geo->start > sz) {
+		DMERR("Start sector is beyond the geometry limits.");
+		return -EINVAL;
+	}
+
+	md->geometry = *geo;
+
+	return 0;
+}
+
+static int __noflush_suspending(struct mapped_device *md)
+{
+	return test_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
+}
+
+static void dm_requeue_add_io(struct dm_io *io, bool first_stage)
+{
+	struct mapped_device *md = io->md;
+
+	if (first_stage) {
+		struct dm_io *next = md->requeue_list;
+
+		md->requeue_list = io;
+		io->next = next;
+	} else {
+		bio_list_add_head(&md->deferred, io->orig_bio);
+	}
+}
+
+static void dm_kick_requeue(struct mapped_device *md, bool first_stage)
+{
+	if (first_stage)
+		queue_work(md->wq, &md->requeue_work);
+	else
+		queue_work(md->wq, &md->work);
+}
+
+/*
+ * Return true if the dm_io's original bio is requeued.
+ * io->status is updated with error if requeue disallowed.
+ */
+static bool dm_handle_requeue(struct dm_io *io, bool first_stage)
+{
+	struct bio *bio = io->orig_bio;
+	bool handle_requeue = (io->status == BLK_STS_DM_REQUEUE);
+	bool handle_polled_eagain = ((io->status == BLK_STS_AGAIN) &&
+				     (bio->bi_opf & REQ_POLLED));
+	struct mapped_device *md = io->md;
+	bool requeued = false;
+
+	if (handle_requeue || handle_polled_eagain) {
+		unsigned long flags;
+
+		if (bio->bi_opf & REQ_POLLED) {
+			/*
+			 * Upper layer won't help us poll split bio
+			 * (io->orig_bio may only reflect a subset of the
+			 * pre-split original) so clear REQ_POLLED.
+			 */
+			bio_clear_polled(bio);
+		}
+
+		/*
+		 * Target requested pushing back the I/O or
+		 * polled IO hit BLK_STS_AGAIN.
+		 */
+		spin_lock_irqsave(&md->deferred_lock, flags);
+		if ((__noflush_suspending(md) &&
+		     !WARN_ON_ONCE(dm_is_zone_write(md, bio))) ||
+		    handle_polled_eagain || first_stage) {
+			dm_requeue_add_io(io, first_stage);
+			requeued = true;
+		} else {
+			/*
+			 * noflush suspend was interrupted or this is
+			 * a write to a zoned target.
+			 */
+			io->status = BLK_STS_IOERR;
+		}
+		spin_unlock_irqrestore(&md->deferred_lock, flags);
+	}
+
+	if (requeued)
+		dm_kick_requeue(md, first_stage);
+
+	return requeued;
+}
+
+static void __dm_io_complete(struct dm_io *io, bool first_stage)
+{
+	struct bio *bio = io->orig_bio;
+	struct mapped_device *md = io->md;
+	blk_status_t io_error;
+	bool requeued;
+
+	requeued = dm_handle_requeue(io, first_stage);
+	if (requeued && first_stage)
+		return;
+
+	io_error = io->status;
+	if (dm_io_flagged(io, DM_IO_ACCOUNTED))
+		dm_end_io_acct(io);
+	else if (!io_error) {
+		/*
+		 * Must handle target that DM_MAPIO_SUBMITTED only to
+		 * then bio_endio() rather than dm_submit_bio_remap()
+		 */
+		__dm_start_io_acct(io);
+		dm_end_io_acct(io);
+	}
+	free_io(io);
+	smp_wmb();
+	this_cpu_dec(*md->pending_io);
+
+	/* nudge anyone waiting on suspend queue */
+	if (unlikely(wq_has_sleeper(&md->wait)))
+		wake_up(&md->wait);
+
+	/* Return early if the original bio was requeued */
+	if (requeued)
+		return;
+
+	if (bio_is_flush_with_data(bio)) {
+		/*
+		 * Preflush done for flush with data, reissue
+		 * without REQ_PREFLUSH.
+		 */
+		bio->bi_opf &= ~REQ_PREFLUSH;
+		queue_io(md, bio);
+	} else {
+		/* done with normal IO or empty flush */
+		if (io_error)
+			bio->bi_status = io_error;
+		bio_endio(bio);
+	}
+}
+
+static void dm_wq_requeue_work(struct work_struct *work)
+{
+	struct mapped_device *md = container_of(work, struct mapped_device,
+						requeue_work);
+	unsigned long flags;
+	struct dm_io *io;
+
+	/* reuse deferred lock to simplify dm_handle_requeue */
+	spin_lock_irqsave(&md->deferred_lock, flags);
+	io = md->requeue_list;
+	md->requeue_list = NULL;
+	spin_unlock_irqrestore(&md->deferred_lock, flags);
+
+	while (io) {
+		struct dm_io *next = io->next;
+
+		dm_io_rewind(io, &md->disk->bio_split);
+
+		io->next = NULL;
+		__dm_io_complete(io, false);
+		io = next;
+		cond_resched();
+	}
+}
+
+/*
+ * Two staged requeue:
+ *
+ * 1) io->orig_bio points to the real original bio, and the part mapped to
+ *    this io must be requeued, instead of other parts of the original bio.
+ *
+ * 2) io->orig_bio points to new cloned bio which matches the requeued dm_io.
+ */
+static void dm_io_complete(struct dm_io *io)
+{
+	bool first_requeue;
+
+	/*
+	 * Only dm_io that has been split needs two stage requeue, otherwise
+	 * we may run into long bio clone chain during suspend and OOM could
+	 * be triggered.
+	 *
+	 * Also flush data dm_io won't be marked as DM_IO_WAS_SPLIT, so they
+	 * also aren't handled via the first stage requeue.
+	 */
+	if (dm_io_flagged(io, DM_IO_WAS_SPLIT))
+		first_requeue = true;
+	else
+		first_requeue = false;
+
+	__dm_io_complete(io, first_requeue);
+}
+
+/*
+ * Decrements the number of outstanding ios that a bio has been
+ * cloned into, completing the original io if necc.
+ */
+static inline void __dm_io_dec_pending(struct dm_io *io)
+{
+	if (atomic_dec_and_test(&io->io_count))
+		dm_io_complete(io);
+}
+
+static void dm_io_set_error(struct dm_io *io, blk_status_t error)
+{
+	unsigned long flags;
+
+	/* Push-back supersedes any I/O errors */
+	spin_lock_irqsave(&io->lock, flags);
+	if (!(io->status == BLK_STS_DM_REQUEUE &&
+	      __noflush_suspending(io->md))) {
+		io->status = error;
+	}
+	spin_unlock_irqrestore(&io->lock, flags);
+}
+
+static void dm_io_dec_pending(struct dm_io *io, blk_status_t error)
+{
+	if (unlikely(error))
+		dm_io_set_error(io, error);
+
+	__dm_io_dec_pending(io);
+}
+
+void disable_discard(struct mapped_device *md)
+{
+	struct queue_limits *limits = dm_get_queue_limits(md);
+
+	/* device doesn't really support DISCARD, disable it */
+	limits->max_discard_sectors = 0;
+}
+
+void disable_write_zeroes(struct mapped_device *md)
+{
+	struct queue_limits *limits = dm_get_queue_limits(md);
+
+	/* device doesn't really support WRITE ZEROES, disable it */
+	limits->max_write_zeroes_sectors = 0;
+}
+
+static bool swap_bios_limit(struct dm_target *ti, struct bio *bio)
+{
+	return unlikely((bio->bi_opf & REQ_SWAP) != 0) && unlikely(ti->limit_swap_bios);
+}
+
+static void clone_endio(struct bio *bio)
+{
+	blk_status_t error = bio->bi_status;
+	struct dm_target_io *tio = clone_to_tio(bio);
+	struct dm_target *ti = tio->ti;
+	dm_endio_fn endio = ti->type->end_io;
+	struct dm_io *io = tio->io;
+	struct mapped_device *md = io->md;
+
+	if (unlikely(error == BLK_STS_TARGET)) {
+		if (bio_op(bio) == REQ_OP_DISCARD &&
+		    !bdev_max_discard_sectors(bio->bi_bdev))
+			disable_discard(md);
+		else if (bio_op(bio) == REQ_OP_WRITE_ZEROES &&
+			 !bdev_write_zeroes_sectors(bio->bi_bdev))
+			disable_write_zeroes(md);
+	}
+
+	if (static_branch_unlikely(&zoned_enabled) &&
+	    unlikely(bdev_is_zoned(bio->bi_bdev)))
+		dm_zone_endio(io, bio);
+
+	if (endio) {
+		int r = endio(ti, bio, &error);
+		switch (r) {
+		case DM_ENDIO_REQUEUE:
+			if (static_branch_unlikely(&zoned_enabled)) {
+				/*
+				 * Requeuing writes to a sequential zone of a zoned
+				 * target will break the sequential write pattern:
+				 * fail such IO.
+				 */
+				if (WARN_ON_ONCE(dm_is_zone_write(md, bio)))
+					error = BLK_STS_IOERR;
+				else
+					error = BLK_STS_DM_REQUEUE;
+			} else
+				error = BLK_STS_DM_REQUEUE;
+			fallthrough;
+		case DM_ENDIO_DONE:
+			break;
+		case DM_ENDIO_INCOMPLETE:
+			/* The target will handle the io */
+			return;
+		default:
+			DMCRIT("unimplemented target endio return value: %d", r);
+			BUG();
+		}
+	}
+
+	if (static_branch_unlikely(&swap_bios_enabled) &&
+	    unlikely(swap_bios_limit(ti, bio)))
+		up(&md->swap_bios_semaphore);
+
+	free_tio(bio);
+	dm_io_dec_pending(io, error);
+}
+
+/*
+ * Return maximum size of I/O possible at the supplied sector up to the current
+ * target boundary.
+ */
+static inline sector_t max_io_len_target_boundary(struct dm_target *ti,
+						  sector_t target_offset)
+{
+	return ti->len - target_offset;
+}
+
+static sector_t max_io_len(struct dm_target *ti, sector_t sector)
+{
+	sector_t target_offset = dm_target_offset(ti, sector);
+	sector_t len = max_io_len_target_boundary(ti, target_offset);
+
+	/*
+	 * Does the target need to split IO even further?
+	 * - varied (per target) IO splitting is a tenet of DM; this
+	 *   explains why stacked chunk_sectors based splitting via
+	 *   bio_split_to_limits() isn't possible here.
+	 */
+	if (!ti->max_io_len)
+		return len;
+	return min_t(sector_t, len,
+		min(queue_max_sectors(ti->table->md->queue),
+		    blk_chunk_sectors_left(target_offset, ti->max_io_len)));
+}
+
+int dm_set_target_max_io_len(struct dm_target *ti, sector_t len)
+{
+	if (len > UINT_MAX) {
+		DMERR("Specified maximum size of target IO (%llu) exceeds limit (%u)",
+		      (unsigned long long)len, UINT_MAX);
+		ti->error = "Maximum size of target IO is too large";
+		return -EINVAL;
+	}
+
+	ti->max_io_len = (uint32_t) len;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(dm_set_target_max_io_len);
+
+static struct dm_target *dm_dax_get_live_target(struct mapped_device *md,
+						sector_t sector, int *srcu_idx)
+	__acquires(md->io_barrier)
+{
+	struct dm_table *map;
+	struct dm_target *ti;
+
+	map = dm_get_live_table(md, srcu_idx);
+	if (!map)
+		return NULL;
+
+	ti = dm_table_find_target(map, sector);
+	if (!ti)
+		return NULL;
+
+	return ti;
+}
+
+static long dm_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
+		long nr_pages, enum dax_access_mode mode, void **kaddr,
+		pfn_t *pfn)
+{
+	struct mapped_device *md = dax_get_private(dax_dev);
+	sector_t sector = pgoff * PAGE_SECTORS;
+	struct dm_target *ti;
+	long len, ret = -EIO;
+	int srcu_idx;
+
+	ti = dm_dax_get_live_target(md, sector, &srcu_idx);
+
+	if (!ti)
+		goto out;
+	if (!ti->type->direct_access)
+		goto out;
+	len = max_io_len(ti, sector) / PAGE_SECTORS;
+	if (len < 1)
+		goto out;
+	nr_pages = min(len, nr_pages);
+	ret = ti->type->direct_access(ti, pgoff, nr_pages, mode, kaddr, pfn);
+
+ out:
+	dm_put_live_table(md, srcu_idx);
+
+	return ret;
+}
+
+static int dm_dax_zero_page_range(struct dax_device *dax_dev, pgoff_t pgoff,
+				  size_t nr_pages)
+{
+	struct mapped_device *md = dax_get_private(dax_dev);
+	sector_t sector = pgoff * PAGE_SECTORS;
+	struct dm_target *ti;
+	int ret = -EIO;
+	int srcu_idx;
+
+	ti = dm_dax_get_live_target(md, sector, &srcu_idx);
+
+	if (!ti)
+		goto out;
+	if (WARN_ON(!ti->type->dax_zero_page_range)) {
+		/*
+		 * ->zero_page_range() is mandatory dax operation. If we are
+		 *  here, something is wrong.
+		 */
+		goto out;
+	}
+	ret = ti->type->dax_zero_page_range(ti, pgoff, nr_pages);
+ out:
+	dm_put_live_table(md, srcu_idx);
+
+	return ret;
+}
+
+static size_t dm_dax_recovery_write(struct dax_device *dax_dev, pgoff_t pgoff,
+		void *addr, size_t bytes, struct iov_iter *i)
+{
+	struct mapped_device *md = dax_get_private(dax_dev);
+	sector_t sector = pgoff * PAGE_SECTORS;
+	struct dm_target *ti;
+	int srcu_idx;
+	long ret = 0;
+
+	ti = dm_dax_get_live_target(md, sector, &srcu_idx);
+	if (!ti || !ti->type->dax_recovery_write)
+		goto out;
+
+	ret = ti->type->dax_recovery_write(ti, pgoff, addr, bytes, i);
+out:
+	dm_put_live_table(md, srcu_idx);
+	return ret;
+}
+
+/*
+ * A target may call dm_accept_partial_bio only from the map routine.  It is
+ * allowed for all bio types except REQ_PREFLUSH, REQ_OP_ZONE_* zone management
+ * operations, REQ_OP_ZONE_APPEND (zone append writes) and any bio serviced by
+ * __send_duplicate_bios().
+ *
+ * dm_accept_partial_bio informs the dm that the target only wants to process
+ * additional n_sectors sectors of the bio and the rest of the data should be
+ * sent in a next bio.
+ *
+ * A diagram that explains the arithmetics:
+ * +--------------------+---------------+-------+
+ * |         1          |       2       |   3   |
+ * +--------------------+---------------+-------+
+ *
+ * <-------------- *tio->len_ptr --------------->
+ *                      <----- bio_sectors ----->
+ *                      <-- n_sectors -->
+ *
+ * Region 1 was already iterated over with bio_advance or similar function.
+ *	(it may be empty if the target doesn't use bio_advance)
+ * Region 2 is the remaining bio size that the target wants to process.
+ *	(it may be empty if region 1 is non-empty, although there is no reason
+ *	 to make it empty)
+ * The target requires that region 3 is to be sent in the next bio.
+ *
+ * If the target wants to receive multiple copies of the bio (via num_*bios, etc),
+ * the partially processed part (the sum of regions 1+2) must be the same for all
+ * copies of the bio.
+ */
+void dm_accept_partial_bio(struct bio *bio, unsigned int n_sectors)
+{
+	struct dm_target_io *tio = clone_to_tio(bio);
+	struct dm_io *io = tio->io;
+	unsigned int bio_sectors = bio_sectors(bio);
+
+	BUG_ON(dm_tio_flagged(tio, DM_TIO_IS_DUPLICATE_BIO));
+	BUG_ON(op_is_zone_mgmt(bio_op(bio)));
+	BUG_ON(bio_op(bio) == REQ_OP_ZONE_APPEND);
+	BUG_ON(bio_sectors > *tio->len_ptr);
+	BUG_ON(n_sectors > bio_sectors);
+
+	*tio->len_ptr -= bio_sectors - n_sectors;
+	bio->bi_iter.bi_size = n_sectors << SECTOR_SHIFT;
+
+	/*
+	 * __split_and_process_bio() may have already saved mapped part
+	 * for accounting but it is being reduced so update accordingly.
+	 */
+	dm_io_set_flag(io, DM_IO_WAS_SPLIT);
+	io->sectors = n_sectors;
+	io->sector_offset = bio_sectors(io->orig_bio);
+}
+EXPORT_SYMBOL_GPL(dm_accept_partial_bio);
+
+/*
+ * @clone: clone bio that DM core passed to target's .map function
+ * @tgt_clone: clone of @clone bio that target needs submitted
+ *
+ * Targets should use this interface to submit bios they take
+ * ownership of when returning DM_MAPIO_SUBMITTED.
+ *
+ * Target should also enable ti->accounts_remapped_io
+ */
+void dm_submit_bio_remap(struct bio *clone, struct bio *tgt_clone)
+{
+	struct dm_target_io *tio = clone_to_tio(clone);
+	struct dm_io *io = tio->io;
+
+	/* establish bio that will get submitted */
+	if (!tgt_clone)
+		tgt_clone = clone;
+
+	/*
+	 * Account io->origin_bio to DM dev on behalf of target
+	 * that took ownership of IO with DM_MAPIO_SUBMITTED.
+	 */
+	dm_start_io_acct(io, clone);
+
+	trace_block_bio_remap(tgt_clone, disk_devt(io->md->disk),
+			      tio->old_sector);
+	submit_bio_noacct(tgt_clone);
+}
+EXPORT_SYMBOL_GPL(dm_submit_bio_remap);
+
+static noinline void __set_swap_bios_limit(struct mapped_device *md, int latch)
+{
+	mutex_lock(&md->swap_bios_lock);
+	while (latch < md->swap_bios) {
+		cond_resched();
+		down(&md->swap_bios_semaphore);
+		md->swap_bios--;
+	}
+	while (latch > md->swap_bios) {
+		cond_resched();
+		up(&md->swap_bios_semaphore);
+		md->swap_bios++;
+	}
+	mutex_unlock(&md->swap_bios_lock);
+}
+
+static void __map_bio(struct bio *clone)
+{
+	struct dm_target_io *tio = clone_to_tio(clone);
+	struct dm_target *ti = tio->ti;
+	struct dm_io *io = tio->io;
+	struct mapped_device *md = io->md;
+	int r;
+
+	clone->bi_end_io = clone_endio;
+
+	/*
+	 * Map the clone.
+	 */
+	tio->old_sector = clone->bi_iter.bi_sector;
+
+	if (static_branch_unlikely(&swap_bios_enabled) &&
+	    unlikely(swap_bios_limit(ti, clone))) {
+		int latch = get_swap_bios();
+		if (unlikely(latch != md->swap_bios))
+			__set_swap_bios_limit(md, latch);
+		down(&md->swap_bios_semaphore);
+	}
+
+	if (static_branch_unlikely(&zoned_enabled)) {
+		/*
+		 * Check if the IO needs a special mapping due to zone append
+		 * emulation on zoned target. In this case, dm_zone_map_bio()
+		 * calls the target map operation.
+		 */
+		if (unlikely(dm_emulate_zone_append(md)))
+			r = dm_zone_map_bio(tio);
+		else
+			r = ti->type->map(ti, clone);
+	} else
+		r = ti->type->map(ti, clone);
+
+	switch (r) {
+	case DM_MAPIO_SUBMITTED:
+		/* target has assumed ownership of this io */
+		if (!ti->accounts_remapped_io)
+			dm_start_io_acct(io, clone);
+		break;
+	case DM_MAPIO_REMAPPED:
+		dm_submit_bio_remap(clone, NULL);
+		break;
+	case DM_MAPIO_KILL:
+	case DM_MAPIO_REQUEUE:
+		if (static_branch_unlikely(&swap_bios_enabled) &&
+		    unlikely(swap_bios_limit(ti, clone)))
+			up(&md->swap_bios_semaphore);
+		free_tio(clone);
+		if (r == DM_MAPIO_KILL)
+			dm_io_dec_pending(io, BLK_STS_IOERR);
+		else
+			dm_io_dec_pending(io, BLK_STS_DM_REQUEUE);
+		break;
+	default:
+		DMCRIT("unimplemented target map return value: %d", r);
+		BUG();
+	}
+}
+
+static void setup_split_accounting(struct clone_info *ci, unsigned int len)
+{
+	struct dm_io *io = ci->io;
+
+	if (ci->sector_count > len) {
+		/*
+		 * Split needed, save the mapped part for accounting.
+		 * NOTE: dm_accept_partial_bio() will update accordingly.
+		 */
+		dm_io_set_flag(io, DM_IO_WAS_SPLIT);
+		io->sectors = len;
+		io->sector_offset = bio_sectors(ci->bio);
+	}
+}
+
+static void alloc_multiple_bios(struct bio_list *blist, struct clone_info *ci,
+				struct dm_target *ti, unsigned int num_bios,
+				unsigned *len)
+{
+	struct bio *bio;
+	int try;
+
+	for (try = 0; try < 2; try++) {
+		int bio_nr;
+
+		if (try)
+			mutex_lock(&ci->io->md->table_devices_lock);
+		for (bio_nr = 0; bio_nr < num_bios; bio_nr++) {
+			bio = alloc_tio(ci, ti, bio_nr, len,
+					try ? GFP_NOIO : GFP_NOWAIT);
+			if (!bio)
+				break;
+
+			bio_list_add(blist, bio);
+		}
+		if (try)
+			mutex_unlock(&ci->io->md->table_devices_lock);
+		if (bio_nr == num_bios)
+			return;
+
+		while ((bio = bio_list_pop(blist)))
+			free_tio(bio);
+	}
+}
+
+static int __send_duplicate_bios(struct clone_info *ci, struct dm_target *ti,
+				 unsigned int num_bios, unsigned int *len)
+{
+	struct bio_list blist = BIO_EMPTY_LIST;
+	struct bio *clone;
+	unsigned int ret = 0;
+
+	switch (num_bios) {
+	case 0:
+		break;
+	case 1:
+		if (len)
+			setup_split_accounting(ci, *len);
+		clone = alloc_tio(ci, ti, 0, len, GFP_NOIO);
+		__map_bio(clone);
+		ret = 1;
+		break;
+	default:
+		if (len)
+			setup_split_accounting(ci, *len);
+		/* dm_accept_partial_bio() is not supported with shared tio->len_ptr */
+		alloc_multiple_bios(&blist, ci, ti, num_bios, len);
+		while ((clone = bio_list_pop(&blist))) {
+			dm_tio_set_flag(clone_to_tio(clone), DM_TIO_IS_DUPLICATE_BIO);
+			__map_bio(clone);
+			ret += 1;
+		}
+		break;
+	}
+
+	return ret;
+}
+
+static void __send_empty_flush(struct clone_info *ci)
+{
+	struct dm_table *t = ci->map;
+	struct bio flush_bio;
+
+	/*
+	 * Use an on-stack bio for this, it's safe since we don't
+	 * need to reference it after submit. It's just used as
+	 * the basis for the clone(s).
+	 */
+	bio_init(&flush_bio, ci->io->md->disk->part0, NULL, 0,
+		 REQ_OP_WRITE | REQ_PREFLUSH | REQ_SYNC);
+
+	ci->bio = &flush_bio;
+	ci->sector_count = 0;
+	ci->io->tio.clone.bi_iter.bi_size = 0;
+
+	for (unsigned int i = 0; i < t->num_targets; i++) {
+		unsigned int bios;
+		struct dm_target *ti = dm_table_get_target(t, i);
+
+		atomic_add(ti->num_flush_bios, &ci->io->io_count);
+		bios = __send_duplicate_bios(ci, ti, ti->num_flush_bios, NULL);
+		atomic_sub(ti->num_flush_bios - bios, &ci->io->io_count);
+	}
+
+	/*
+	 * alloc_io() takes one extra reference for submission, so the
+	 * reference won't reach 0 without the following subtraction
+	 */
+	atomic_sub(1, &ci->io->io_count);
+
+	bio_uninit(ci->bio);
+}
+
+static void __send_changing_extent_only(struct clone_info *ci, struct dm_target *ti,
+					unsigned int num_bios)
+{
+	unsigned int len, bios;
+
+	len = min_t(sector_t, ci->sector_count,
+		    max_io_len_target_boundary(ti, dm_target_offset(ti, ci->sector)));
+
+	atomic_add(num_bios, &ci->io->io_count);
+	bios = __send_duplicate_bios(ci, ti, num_bios, &len);
+	/*
+	 * alloc_io() takes one extra reference for submission, so the
+	 * reference won't reach 0 without the following (+1) subtraction
+	 */
+	atomic_sub(num_bios - bios + 1, &ci->io->io_count);
+
+	ci->sector += len;
+	ci->sector_count -= len;
+}
+
+static bool is_abnormal_io(struct bio *bio)
+{
+	enum req_op op = bio_op(bio);
+
+	if (op != REQ_OP_READ && op != REQ_OP_WRITE && op != REQ_OP_FLUSH) {
+		switch (op) {
+		case REQ_OP_DISCARD:
+		case REQ_OP_SECURE_ERASE:
+		case REQ_OP_WRITE_ZEROES:
+			return true;
+		default:
+			break;
+		}
+	}
+
+	return false;
+}
+
+static blk_status_t __process_abnormal_io(struct clone_info *ci,
+					  struct dm_target *ti)
+{
+	unsigned int num_bios = 0;
+
+	switch (bio_op(ci->bio)) {
+	case REQ_OP_DISCARD:
+		num_bios = ti->num_discard_bios;
+		break;
+	case REQ_OP_SECURE_ERASE:
+		num_bios = ti->num_secure_erase_bios;
+		break;
+	case REQ_OP_WRITE_ZEROES:
+		num_bios = ti->num_write_zeroes_bios;
+		break;
+	default:
+		break;
+	}
+
+	/*
+	 * Even though the device advertised support for this type of
+	 * request, that does not mean every target supports it, and
+	 * reconfiguration might also have changed that since the
+	 * check was performed.
+	 */
+	if (unlikely(!num_bios))
+		return BLK_STS_NOTSUPP;
+
+	__send_changing_extent_only(ci, ti, num_bios);
+	return BLK_STS_OK;
+}
+
+/*
+ * Reuse ->bi_private as dm_io list head for storing all dm_io instances
+ * associated with this bio, and this bio's bi_private needs to be
+ * stored in dm_io->data before the reuse.
+ *
+ * bio->bi_private is owned by fs or upper layer, so block layer won't
+ * touch it after splitting. Meantime it won't be changed by anyone after
+ * bio is submitted. So this reuse is safe.
+ */
+static inline struct dm_io **dm_poll_list_head(struct bio *bio)
+{
+	return (struct dm_io **)&bio->bi_private;
+}
+
+static void dm_queue_poll_io(struct bio *bio, struct dm_io *io)
+{
+	struct dm_io **head = dm_poll_list_head(bio);
+
+	if (!(bio->bi_opf & REQ_DM_POLL_LIST)) {
+		bio->bi_opf |= REQ_DM_POLL_LIST;
+		/*
+		 * Save .bi_private into dm_io, so that we can reuse
+		 * .bi_private as dm_io list head for storing dm_io list
+		 */
+		io->data = bio->bi_private;
+
+		/* tell block layer to poll for completion */
+		bio->bi_cookie = ~BLK_QC_T_NONE;
+
+		io->next = NULL;
+	} else {
+		/*
+		 * bio recursed due to split, reuse original poll list,
+		 * and save bio->bi_private too.
+		 */
+		io->data = (*head)->data;
+		io->next = *head;
+	}
+
+	*head = io;
+}
+
+/*
+ * Select the correct strategy for processing a non-flush bio.
+ */
+static blk_status_t __split_and_process_bio(struct clone_info *ci)
+{
+	struct bio *clone;
+	struct dm_target *ti;
+	unsigned int len;
+
+	ti = dm_table_find_target(ci->map, ci->sector);
+	if (unlikely(!ti))
+		return BLK_STS_IOERR;
+
+	if (unlikely((ci->bio->bi_opf & REQ_NOWAIT) != 0) &&
+	    unlikely(!dm_target_supports_nowait(ti->type)))
+		return BLK_STS_NOTSUPP;
+
+	if (unlikely(ci->is_abnormal_io))
+		return __process_abnormal_io(ci, ti);
+
+	/*
+	 * Only support bio polling for normal IO, and the target io is
+	 * exactly inside the dm_io instance (verified in dm_poll_dm_io)
+	 */
+	ci->submit_as_polled = !!(ci->bio->bi_opf & REQ_POLLED);
+
+	len = min_t(sector_t, max_io_len(ti, ci->sector), ci->sector_count);
+	setup_split_accounting(ci, len);
+	clone = alloc_tio(ci, ti, 0, &len, GFP_NOIO);
+	__map_bio(clone);
+
+	ci->sector += len;
+	ci->sector_count -= len;
+
+	return BLK_STS_OK;
+}
+
+static void init_clone_info(struct clone_info *ci, struct mapped_device *md,
+			    struct dm_table *map, struct bio *bio, bool is_abnormal)
+{
+	ci->map = map;
+	ci->io = alloc_io(md, bio);
+	ci->bio = bio;
+	ci->is_abnormal_io = is_abnormal;
+	ci->submit_as_polled = false;
+	ci->sector = bio->bi_iter.bi_sector;
+	ci->sector_count = bio_sectors(bio);
+
+	/* Shouldn't happen but sector_count was being set to 0 so... */
+	if (static_branch_unlikely(&zoned_enabled) &&
+	    WARN_ON_ONCE(op_is_zone_mgmt(bio_op(bio)) && ci->sector_count))
+		ci->sector_count = 0;
+}
+
+/*
+ * Entry point to split a bio into clones and submit them to the targets.
+ */
+static void dm_split_and_process_bio(struct mapped_device *md,
+				     struct dm_table *map, struct bio *bio)
+{
+	struct clone_info ci;
+	struct dm_io *io;
+	blk_status_t error = BLK_STS_OK;
+	bool is_abnormal;
+
+	is_abnormal = is_abnormal_io(bio);
+	if (unlikely(is_abnormal)) {
+		/*
+		 * Use bio_split_to_limits() for abnormal IO (e.g. discard, etc)
+		 * otherwise associated queue_limits won't be imposed.
+		 */
+		bio = bio_split_to_limits(bio);
+		if (!bio)
+			return;
+	}
+
+	init_clone_info(&ci, md, map, bio, is_abnormal);
+	io = ci.io;
+
+	if (bio->bi_opf & REQ_PREFLUSH) {
+		__send_empty_flush(&ci);
+		/* dm_io_complete submits any data associated with flush */
+		goto out;
+	}
+
+	error = __split_and_process_bio(&ci);
+	if (error || !ci.sector_count)
+		goto out;
+	/*
+	 * Remainder must be passed to submit_bio_noacct() so it gets handled
+	 * *after* bios already submitted have been completely processed.
+	 */
+	bio_trim(bio, io->sectors, ci.sector_count);
+	trace_block_split(bio, bio->bi_iter.bi_sector);
+	bio_inc_remaining(bio);
+	submit_bio_noacct(bio);
+out:
+	/*
+	 * Drop the extra reference count for non-POLLED bio, and hold one
+	 * reference for POLLED bio, which will be released in dm_poll_bio
+	 *
+	 * Add every dm_io instance into the dm_io list head which is stored
+	 * in bio->bi_private, so that dm_poll_bio can poll them all.
+	 */
+	if (error || !ci.submit_as_polled) {
+		/*
+		 * In case of submission failure, the extra reference for
+		 * submitting io isn't consumed yet
+		 */
+		if (error)
+			atomic_dec(&io->io_count);
+		dm_io_dec_pending(io, error);
+	} else
+		dm_queue_poll_io(bio, io);
+}
+
+static void dm_submit_bio(struct bio *bio)
+{
+	struct mapped_device *md = bio->bi_bdev->bd_disk->private_data;
+	int srcu_idx;
+	struct dm_table *map;
+
+	map = dm_get_live_table(md, &srcu_idx);
+
+	/* If suspended, or map not yet available, queue this IO for later */
+	if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) ||
+	    unlikely(!map)) {
+		if (bio->bi_opf & REQ_NOWAIT)
+			bio_wouldblock_error(bio);
+		else if (bio->bi_opf & REQ_RAHEAD)
+			bio_io_error(bio);
+		else
+			queue_io(md, bio);
+		goto out;
+	}
+
+	dm_split_and_process_bio(md, map, bio);
+out:
+	dm_put_live_table(md, srcu_idx);
+}
+
+static bool dm_poll_dm_io(struct dm_io *io, struct io_comp_batch *iob,
+			  unsigned int flags)
+{
+	WARN_ON_ONCE(!dm_tio_is_normal(&io->tio));
+
+	/* don't poll if the mapped io is done */
+	if (atomic_read(&io->io_count) > 1)
+		bio_poll(&io->tio.clone, iob, flags);
+
+	/* bio_poll holds the last reference */
+	return atomic_read(&io->io_count) == 1;
+}
+
+static int dm_poll_bio(struct bio *bio, struct io_comp_batch *iob,
+		       unsigned int flags)
+{
+	struct dm_io **head = dm_poll_list_head(bio);
+	struct dm_io *list = *head;
+	struct dm_io *tmp = NULL;
+	struct dm_io *curr, *next;
+
+	/* Only poll normal bio which was marked as REQ_DM_POLL_LIST */
+	if (!(bio->bi_opf & REQ_DM_POLL_LIST))
+		return 0;
+
+	WARN_ON_ONCE(!list);
+
+	/*
+	 * Restore .bi_private before possibly completing dm_io.
+	 *
+	 * bio_poll() is only possible once @bio has been completely
+	 * submitted via submit_bio_noacct()'s depth-first submission.
+	 * So there is no dm_queue_poll_io() race associated with
+	 * clearing REQ_DM_POLL_LIST here.
+	 */
+	bio->bi_opf &= ~REQ_DM_POLL_LIST;
+	bio->bi_private = list->data;
+
+	for (curr = list, next = curr->next; curr; curr = next, next =
+			curr ? curr->next : NULL) {
+		if (dm_poll_dm_io(curr, iob, flags)) {
+			/*
+			 * clone_endio() has already occurred, so no
+			 * error handling is needed here.
+			 */
+			__dm_io_dec_pending(curr);
+		} else {
+			curr->next = tmp;
+			tmp = curr;
+		}
+	}
+
+	/* Not done? */
+	if (tmp) {
+		bio->bi_opf |= REQ_DM_POLL_LIST;
+		/* Reset bio->bi_private to dm_io list head */
+		*head = tmp;
+		return 0;
+	}
+	return 1;
+}
+
+/*-----------------------------------------------------------------
+ * An IDR is used to keep track of allocated minor numbers.
+ *---------------------------------------------------------------*/
+static void free_minor(int minor)
+{
+	spin_lock(&_minor_lock);
+	idr_remove(&_minor_idr, minor);
+	spin_unlock(&_minor_lock);
+}
+
+/*
+ * See if the device with a specific minor # is free.
+ */
+static int specific_minor(int minor)
+{
+	int r;
+
+	if (minor >= (1 << MINORBITS))
+		return -EINVAL;
+
+	idr_preload(GFP_KERNEL);
+	spin_lock(&_minor_lock);
+
+	r = idr_alloc(&_minor_idr, MINOR_ALLOCED, minor, minor + 1, GFP_NOWAIT);
+
+	spin_unlock(&_minor_lock);
+	idr_preload_end();
+	if (r < 0)
+		return r == -ENOSPC ? -EBUSY : r;
+	return 0;
+}
+
+static int next_free_minor(int *minor)
+{
+	int r;
+
+	idr_preload(GFP_KERNEL);
+	spin_lock(&_minor_lock);
+
+	r = idr_alloc(&_minor_idr, MINOR_ALLOCED, 0, 1 << MINORBITS, GFP_NOWAIT);
+
+	spin_unlock(&_minor_lock);
+	idr_preload_end();
+	if (r < 0)
+		return r;
+	*minor = r;
+	return 0;
+}
+
+static const struct block_device_operations dm_blk_dops;
+static const struct block_device_operations dm_rq_blk_dops;
+static const struct dax_operations dm_dax_ops;
+
+static void dm_wq_work(struct work_struct *work);
+
+#ifdef CONFIG_BLK_INLINE_ENCRYPTION
+static void dm_queue_destroy_crypto_profile(struct request_queue *q)
+{
+	dm_destroy_crypto_profile(q->crypto_profile);
+}
+
+#else /* CONFIG_BLK_INLINE_ENCRYPTION */
+
+static inline void dm_queue_destroy_crypto_profile(struct request_queue *q)
+{
+}
+#endif /* !CONFIG_BLK_INLINE_ENCRYPTION */
+
+static void cleanup_mapped_device(struct mapped_device *md)
+{
+	if (md->wq)
+		destroy_workqueue(md->wq);
+	dm_free_md_mempools(md->mempools);
+
+	if (md->dax_dev) {
+		dax_remove_host(md->disk);
+		kill_dax(md->dax_dev);
+		put_dax(md->dax_dev);
+		md->dax_dev = NULL;
+	}
+
+	dm_cleanup_zoned_dev(md);
+	if (md->disk) {
+		spin_lock(&_minor_lock);
+		md->disk->private_data = NULL;
+		spin_unlock(&_minor_lock);
+		if (dm_get_md_type(md) != DM_TYPE_NONE) {
+			struct table_device *td;
+
+			dm_sysfs_exit(md);
+			list_for_each_entry(td, &md->table_devices, list) {
+				bd_unlink_disk_holder(td->dm_dev.bdev,
+						      md->disk);
+			}
+
+			/*
+			 * Hold lock to make sure del_gendisk() won't concurrent
+			 * with open/close_table_device().
+			 */
+			mutex_lock(&md->table_devices_lock);
+			del_gendisk(md->disk);
+			mutex_unlock(&md->table_devices_lock);
+		}
+		dm_queue_destroy_crypto_profile(md->queue);
+		put_disk(md->disk);
+	}
+
+	if (md->pending_io) {
+		free_percpu(md->pending_io);
+		md->pending_io = NULL;
+	}
+
+	cleanup_srcu_struct(&md->io_barrier);
+
+	mutex_destroy(&md->suspend_lock);
+	mutex_destroy(&md->type_lock);
+	mutex_destroy(&md->table_devices_lock);
+	mutex_destroy(&md->swap_bios_lock);
+
+	dm_mq_cleanup_mapped_device(md);
+}
+
+/*
+ * Allocate and initialise a blank device with a given minor.
+ */
+static struct mapped_device *alloc_dev(int minor)
+{
+	int r, numa_node_id = dm_get_numa_node();
+	struct mapped_device *md;
+	void *old_md;
+
+	md = kvzalloc_node(sizeof(*md), GFP_KERNEL, numa_node_id);
+	if (!md) {
+		DMERR("unable to allocate device, out of memory.");
+		return NULL;
+	}
+
+	if (!try_module_get(THIS_MODULE))
+		goto bad_module_get;
+
+	/* get a minor number for the dev */
+	if (minor == DM_ANY_MINOR)
+		r = next_free_minor(&minor);
+	else
+		r = specific_minor(minor);
+	if (r < 0)
+		goto bad_minor;
+
+	r = init_srcu_struct(&md->io_barrier);
+	if (r < 0)
+		goto bad_io_barrier;
+
+	md->numa_node_id = numa_node_id;
+	md->init_tio_pdu = false;
+	md->type = DM_TYPE_NONE;
+	mutex_init(&md->suspend_lock);
+	mutex_init(&md->type_lock);
+	mutex_init(&md->table_devices_lock);
+	spin_lock_init(&md->deferred_lock);
+	atomic_set(&md->holders, 1);
+	atomic_set(&md->open_count, 0);
+	atomic_set(&md->event_nr, 0);
+	atomic_set(&md->uevent_seq, 0);
+	INIT_LIST_HEAD(&md->uevent_list);
+	INIT_LIST_HEAD(&md->table_devices);
+	spin_lock_init(&md->uevent_lock);
+
+	/*
+	 * default to bio-based until DM table is loaded and md->type
+	 * established. If request-based table is loaded: blk-mq will
+	 * override accordingly.
+	 */
+	md->disk = blk_alloc_disk(md->numa_node_id);
+	if (!md->disk)
+		goto bad;
+	md->queue = md->disk->queue;
+
+	init_waitqueue_head(&md->wait);
+	INIT_WORK(&md->work, dm_wq_work);
+	INIT_WORK(&md->requeue_work, dm_wq_requeue_work);
+	init_waitqueue_head(&md->eventq);
+	init_completion(&md->kobj_holder.completion);
+
+	md->requeue_list = NULL;
+	md->swap_bios = get_swap_bios();
+	sema_init(&md->swap_bios_semaphore, md->swap_bios);
+	mutex_init(&md->swap_bios_lock);
+
+	md->disk->major = _major;
+	md->disk->first_minor = minor;
+	md->disk->minors = 1;
+	md->disk->flags |= GENHD_FL_NO_PART;
+	md->disk->fops = &dm_blk_dops;
+	md->disk->private_data = md;
+	sprintf(md->disk->disk_name, "dm-%d", minor);
+
+	if (IS_ENABLED(CONFIG_FS_DAX)) {
+		md->dax_dev = alloc_dax(md, &dm_dax_ops);
+		if (IS_ERR(md->dax_dev)) {
+			md->dax_dev = NULL;
+			goto bad;
+		}
+		set_dax_nocache(md->dax_dev);
+		set_dax_nomc(md->dax_dev);
+		if (dax_add_host(md->dax_dev, md->disk))
+			goto bad;
+	}
+
+	format_dev_t(md->name, MKDEV(_major, minor));
+
+	md->wq = alloc_workqueue("kdmflush/%s", WQ_MEM_RECLAIM, 0, md->name);
+	if (!md->wq)
+		goto bad;
+
+	md->pending_io = alloc_percpu(unsigned long);
+	if (!md->pending_io)
+		goto bad;
+
+	r = dm_stats_init(&md->stats);
+	if (r < 0)
+		goto bad;
+
+	/* Populate the mapping, nobody knows we exist yet */
+	spin_lock(&_minor_lock);
+	old_md = idr_replace(&_minor_idr, md, minor);
+	spin_unlock(&_minor_lock);
+
+	BUG_ON(old_md != MINOR_ALLOCED);
+
+	return md;
+
+bad:
+	cleanup_mapped_device(md);
+bad_io_barrier:
+	free_minor(minor);
+bad_minor:
+	module_put(THIS_MODULE);
+bad_module_get:
+	kvfree(md);
+	return NULL;
+}
+
+static void unlock_fs(struct mapped_device *md);
+
+static void free_dev(struct mapped_device *md)
+{
+	int minor = MINOR(disk_devt(md->disk));
+
+	unlock_fs(md);
+
+	cleanup_mapped_device(md);
+
+	free_table_devices(&md->table_devices);
+	dm_stats_cleanup(&md->stats);
+	free_minor(minor);
+
+	module_put(THIS_MODULE);
+	kvfree(md);
+}
+
+/*
+ * Bind a table to the device.
+ */
+static void event_callback(void *context)
+{
+	unsigned long flags;
+	LIST_HEAD(uevents);
+	struct mapped_device *md = (struct mapped_device *) context;
+
+	spin_lock_irqsave(&md->uevent_lock, flags);
+	list_splice_init(&md->uevent_list, &uevents);
+	spin_unlock_irqrestore(&md->uevent_lock, flags);
+
+	dm_send_uevents(&uevents, &disk_to_dev(md->disk)->kobj);
+
+	atomic_inc(&md->event_nr);
+	wake_up(&md->eventq);
+	dm_issue_global_event();
+}
+
+/*
+ * Returns old map, which caller must destroy.
+ */
+static struct dm_table *__bind(struct mapped_device *md, struct dm_table *t,
+			       struct queue_limits *limits)
+{
+	struct dm_table *old_map;
+	sector_t size;
+	int ret;
+
+	lockdep_assert_held(&md->suspend_lock);
+
+	size = dm_table_get_size(t);
+
+	/*
+	 * Wipe any geometry if the size of the table changed.
+	 */
+	if (size != dm_get_size(md))
+		memset(&md->geometry, 0, sizeof(md->geometry));
+
+	set_capacity(md->disk, size);
+
+	dm_table_event_callback(t, event_callback, md);
+
+	if (dm_table_request_based(t)) {
+		/*
+		 * Leverage the fact that request-based DM targets are
+		 * immutable singletons - used to optimize dm_mq_queue_rq.
+		 */
+		md->immutable_target = dm_table_get_immutable_target(t);
+
+		/*
+		 * There is no need to reload with request-based dm because the
+		 * size of front_pad doesn't change.
+		 *
+		 * Note for future: If you are to reload bioset, prep-ed
+		 * requests in the queue may refer to bio from the old bioset,
+		 * so you must walk through the queue to unprep.
+		 */
+		if (!md->mempools) {
+			md->mempools = t->mempools;
+			t->mempools = NULL;
+		}
+	} else {
+		/*
+		 * The md may already have mempools that need changing.
+		 * If so, reload bioset because front_pad may have changed
+		 * because a different table was loaded.
+		 */
+		dm_free_md_mempools(md->mempools);
+		md->mempools = t->mempools;
+		t->mempools = NULL;
+	}
+
+	ret = dm_table_set_restrictions(t, md->queue, limits);
+	if (ret) {
+		old_map = ERR_PTR(ret);
+		goto out;
+	}
+
+	old_map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock));
+	rcu_assign_pointer(md->map, (void *)t);
+	md->immutable_target_type = dm_table_get_immutable_target_type(t);
+
+	if (old_map)
+		dm_sync_table(md);
+out:
+	return old_map;
+}
+
+/*
+ * Returns unbound table for the caller to free.
+ */
+static struct dm_table *__unbind(struct mapped_device *md)
+{
+	struct dm_table *map = rcu_dereference_protected(md->map, 1);
+
+	if (!map)
+		return NULL;
+
+	dm_table_event_callback(map, NULL, NULL);
+	RCU_INIT_POINTER(md->map, NULL);
+	dm_sync_table(md);
+
+	return map;
+}
+
+/*
+ * Constructor for a new device.
+ */
+int dm_create(int minor, struct mapped_device **result)
+{
+	struct mapped_device *md;
+
+	md = alloc_dev(minor);
+	if (!md)
+		return -ENXIO;
+
+	dm_ima_reset_data(md);
+
+	*result = md;
+	return 0;
+}
+
+/*
+ * Functions to manage md->type.
+ * All are required to hold md->type_lock.
+ */
+void dm_lock_md_type(struct mapped_device *md)
+{
+	mutex_lock(&md->type_lock);
+}
+
+void dm_unlock_md_type(struct mapped_device *md)
+{
+	mutex_unlock(&md->type_lock);
+}
+
+void dm_set_md_type(struct mapped_device *md, enum dm_queue_mode type)
+{
+	BUG_ON(!mutex_is_locked(&md->type_lock));
+	md->type = type;
+}
+
+enum dm_queue_mode dm_get_md_type(struct mapped_device *md)
+{
+	return md->type;
+}
+
+struct target_type *dm_get_immutable_target_type(struct mapped_device *md)
+{
+	return md->immutable_target_type;
+}
+
+/*
+ * The queue_limits are only valid as long as you have a reference
+ * count on 'md'.
+ */
+struct queue_limits *dm_get_queue_limits(struct mapped_device *md)
+{
+	BUG_ON(!atomic_read(&md->holders));
+	return &md->queue->limits;
+}
+EXPORT_SYMBOL_GPL(dm_get_queue_limits);
+
+/*
+ * Setup the DM device's queue based on md's type
+ */
+int dm_setup_md_queue(struct mapped_device *md, struct dm_table *t)
+{
+	enum dm_queue_mode type = dm_table_get_type(t);
+	struct queue_limits limits;
+	struct table_device *td;
+	int r;
+
+	switch (type) {
+	case DM_TYPE_REQUEST_BASED:
+		md->disk->fops = &dm_rq_blk_dops;
+		r = dm_mq_init_request_queue(md, t);
+		if (r) {
+			DMERR("Cannot initialize queue for request-based dm mapped device");
+			return r;
+		}
+		break;
+	case DM_TYPE_BIO_BASED:
+	case DM_TYPE_DAX_BIO_BASED:
+		break;
+	case DM_TYPE_NONE:
+		WARN_ON_ONCE(true);
+		break;
+	}
+
+	r = dm_calculate_queue_limits(t, &limits);
+	if (r) {
+		DMERR("Cannot calculate initial queue limits");
+		return r;
+	}
+	r = dm_table_set_restrictions(t, md->queue, &limits);
+	if (r)
+		return r;
+
+	/*
+	 * Hold lock to make sure add_disk() and del_gendisk() won't concurrent
+	 * with open_table_device() and close_table_device().
+	 */
+	mutex_lock(&md->table_devices_lock);
+	r = add_disk(md->disk);
+	mutex_unlock(&md->table_devices_lock);
+	if (r)
+		return r;
+
+	/*
+	 * Register the holder relationship for devices added before the disk
+	 * was live.
+	 */
+	list_for_each_entry(td, &md->table_devices, list) {
+		r = bd_link_disk_holder(td->dm_dev.bdev, md->disk);
+		if (r)
+			goto out_undo_holders;
+	}
+
+	r = dm_sysfs_init(md);
+	if (r)
+		goto out_undo_holders;
+
+	md->type = type;
+	return 0;
+
+out_undo_holders:
+	list_for_each_entry_continue_reverse(td, &md->table_devices, list)
+		bd_unlink_disk_holder(td->dm_dev.bdev, md->disk);
+	mutex_lock(&md->table_devices_lock);
+	del_gendisk(md->disk);
+	mutex_unlock(&md->table_devices_lock);
+	return r;
+}
+
+struct mapped_device *dm_get_md(dev_t dev)
+{
+	struct mapped_device *md;
+	unsigned int minor = MINOR(dev);
+
+	if (MAJOR(dev) != _major || minor >= (1 << MINORBITS))
+		return NULL;
+
+	spin_lock(&_minor_lock);
+
+	md = idr_find(&_minor_idr, minor);
+	if (!md || md == MINOR_ALLOCED || (MINOR(disk_devt(dm_disk(md))) != minor) ||
+	    test_bit(DMF_FREEING, &md->flags) || dm_deleting_md(md)) {
+		md = NULL;
+		goto out;
+	}
+	dm_get(md);
+out:
+	spin_unlock(&_minor_lock);
+
+	return md;
+}
+EXPORT_SYMBOL_GPL(dm_get_md);
+
+void *dm_get_mdptr(struct mapped_device *md)
+{
+	return md->interface_ptr;
+}
+
+void dm_set_mdptr(struct mapped_device *md, void *ptr)
+{
+	md->interface_ptr = ptr;
+}
+
+void dm_get(struct mapped_device *md)
+{
+	atomic_inc(&md->holders);
+	BUG_ON(test_bit(DMF_FREEING, &md->flags));
+}
+
+int dm_hold(struct mapped_device *md)
+{
+	spin_lock(&_minor_lock);
+	if (test_bit(DMF_FREEING, &md->flags)) {
+		spin_unlock(&_minor_lock);
+		return -EBUSY;
+	}
+	dm_get(md);
+	spin_unlock(&_minor_lock);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(dm_hold);
+
+const char *dm_device_name(struct mapped_device *md)
+{
+	return md->name;
+}
+EXPORT_SYMBOL_GPL(dm_device_name);
+
+static void __dm_destroy(struct mapped_device *md, bool wait)
+{
+	struct dm_table *map;
+	int srcu_idx;
+
+	might_sleep();
+
+	spin_lock(&_minor_lock);
+	idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md))));
+	set_bit(DMF_FREEING, &md->flags);
+	spin_unlock(&_minor_lock);
+
+	blk_mark_disk_dead(md->disk);
+
+	/*
+	 * Take suspend_lock so that presuspend and postsuspend methods
+	 * do not race with internal suspend.
+	 */
+	mutex_lock(&md->suspend_lock);
+	map = dm_get_live_table(md, &srcu_idx);
+	if (!dm_suspended_md(md)) {
+		dm_table_presuspend_targets(map);
+		set_bit(DMF_SUSPENDED, &md->flags);
+		set_bit(DMF_POST_SUSPENDING, &md->flags);
+		dm_table_postsuspend_targets(map);
+	}
+	/* dm_put_live_table must be before msleep, otherwise deadlock is possible */
+	dm_put_live_table(md, srcu_idx);
+	mutex_unlock(&md->suspend_lock);
+
+	/*
+	 * Rare, but there may be I/O requests still going to complete,
+	 * for example.  Wait for all references to disappear.
+	 * No one should increment the reference count of the mapped_device,
+	 * after the mapped_device state becomes DMF_FREEING.
+	 */
+	if (wait)
+		while (atomic_read(&md->holders))
+			msleep(1);
+	else if (atomic_read(&md->holders))
+		DMWARN("%s: Forcibly removing mapped_device still in use! (%d users)",
+		       dm_device_name(md), atomic_read(&md->holders));
+
+	dm_table_destroy(__unbind(md));
+	free_dev(md);
+}
+
+void dm_destroy(struct mapped_device *md)
+{
+	__dm_destroy(md, true);
+}
+
+void dm_destroy_immediate(struct mapped_device *md)
+{
+	__dm_destroy(md, false);
+}
+
+void dm_put(struct mapped_device *md)
+{
+	atomic_dec(&md->holders);
+}
+EXPORT_SYMBOL_GPL(dm_put);
+
+static bool dm_in_flight_bios(struct mapped_device *md)
+{
+	int cpu;
+	unsigned long sum = 0;
+
+	for_each_possible_cpu(cpu)
+		sum += *per_cpu_ptr(md->pending_io, cpu);
+
+	return sum != 0;
+}
+
+static int dm_wait_for_bios_completion(struct mapped_device *md, unsigned int task_state)
+{
+	int r = 0;
+	DEFINE_WAIT(wait);
+
+	while (true) {
+		prepare_to_wait(&md->wait, &wait, task_state);
+
+		if (!dm_in_flight_bios(md))
+			break;
+
+		if (signal_pending_state(task_state, current)) {
+			r = -EINTR;
+			break;
+		}
+
+		io_schedule();
+	}
+	finish_wait(&md->wait, &wait);
+
+	smp_rmb();
+
+	return r;
+}
+
+static int dm_wait_for_completion(struct mapped_device *md, unsigned int task_state)
+{
+	int r = 0;
+
+	if (!queue_is_mq(md->queue))
+		return dm_wait_for_bios_completion(md, task_state);
+
+	while (true) {
+		if (!blk_mq_queue_inflight(md->queue))
+			break;
+
+		if (signal_pending_state(task_state, current)) {
+			r = -EINTR;
+			break;
+		}
+
+		msleep(5);
+	}
+
+	return r;
+}
+
+/*
+ * Process the deferred bios
+ */
+static void dm_wq_work(struct work_struct *work)
+{
+	struct mapped_device *md = container_of(work, struct mapped_device, work);
+	struct bio *bio;
+
+	while (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
+		spin_lock_irq(&md->deferred_lock);
+		bio = bio_list_pop(&md->deferred);
+		spin_unlock_irq(&md->deferred_lock);
+
+		if (!bio)
+			break;
+
+		submit_bio_noacct(bio);
+		cond_resched();
+	}
+}
+
+static void dm_queue_flush(struct mapped_device *md)
+{
+	clear_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
+	smp_mb__after_atomic();
+	queue_work(md->wq, &md->work);
+}
+
+/*
+ * Swap in a new table, returning the old one for the caller to destroy.
+ */
+struct dm_table *dm_swap_table(struct mapped_device *md, struct dm_table *table)
+{
+	struct dm_table *live_map = NULL, *map = ERR_PTR(-EINVAL);
+	struct queue_limits limits;
+	int r;
+
+	mutex_lock(&md->suspend_lock);
+
+	/* device must be suspended */
+	if (!dm_suspended_md(md))
+		goto out;
+
+	/*
+	 * If the new table has no data devices, retain the existing limits.
+	 * This helps multipath with queue_if_no_path if all paths disappear,
+	 * then new I/O is queued based on these limits, and then some paths
+	 * reappear.
+	 */
+	if (dm_table_has_no_data_devices(table)) {
+		live_map = dm_get_live_table_fast(md);
+		if (live_map)
+			limits = md->queue->limits;
+		dm_put_live_table_fast(md);
+	}
+
+	if (!live_map) {
+		r = dm_calculate_queue_limits(table, &limits);
+		if (r) {
+			map = ERR_PTR(r);
+			goto out;
+		}
+	}
+
+	map = __bind(md, table, &limits);
+	dm_issue_global_event();
+
+out:
+	mutex_unlock(&md->suspend_lock);
+	return map;
+}
+
+/*
+ * Functions to lock and unlock any filesystem running on the
+ * device.
+ */
+static int lock_fs(struct mapped_device *md)
+{
+	int r;
+
+	WARN_ON(test_bit(DMF_FROZEN, &md->flags));
+
+	r = freeze_bdev(md->disk->part0);
+	if (!r)
+		set_bit(DMF_FROZEN, &md->flags);
+	return r;
+}
+
+static void unlock_fs(struct mapped_device *md)
+{
+	if (!test_bit(DMF_FROZEN, &md->flags))
+		return;
+	thaw_bdev(md->disk->part0);
+	clear_bit(DMF_FROZEN, &md->flags);
+}
+
+/*
+ * @suspend_flags: DM_SUSPEND_LOCKFS_FLAG and/or DM_SUSPEND_NOFLUSH_FLAG
+ * @task_state: e.g. TASK_INTERRUPTIBLE or TASK_UNINTERRUPTIBLE
+ * @dmf_suspended_flag: DMF_SUSPENDED or DMF_SUSPENDED_INTERNALLY
+ *
+ * If __dm_suspend returns 0, the device is completely quiescent
+ * now. There is no request-processing activity. All new requests
+ * are being added to md->deferred list.
+ */
+static int __dm_suspend(struct mapped_device *md, struct dm_table *map,
+			unsigned int suspend_flags, unsigned int task_state,
+			int dmf_suspended_flag)
+{
+	bool do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG;
+	bool noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG;
+	int r;
+
+	lockdep_assert_held(&md->suspend_lock);
+
+	/*
+	 * DMF_NOFLUSH_SUSPENDING must be set before presuspend.
+	 * This flag is cleared before dm_suspend returns.
+	 */
+	if (noflush)
+		set_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
+	else
+		DMDEBUG("%s: suspending with flush", dm_device_name(md));
+
+	/*
+	 * This gets reverted if there's an error later and the targets
+	 * provide the .presuspend_undo hook.
+	 */
+	dm_table_presuspend_targets(map);
+
+	/*
+	 * Flush I/O to the device.
+	 * Any I/O submitted after lock_fs() may not be flushed.
+	 * noflush takes precedence over do_lockfs.
+	 * (lock_fs() flushes I/Os and waits for them to complete.)
+	 */
+	if (!noflush && do_lockfs) {
+		r = lock_fs(md);
+		if (r) {
+			dm_table_presuspend_undo_targets(map);
+			return r;
+		}
+	}
+
+	/*
+	 * Here we must make sure that no processes are submitting requests
+	 * to target drivers i.e. no one may be executing
+	 * dm_split_and_process_bio from dm_submit_bio.
+	 *
+	 * To get all processes out of dm_split_and_process_bio in dm_submit_bio,
+	 * we take the write lock. To prevent any process from reentering
+	 * dm_split_and_process_bio from dm_submit_bio and quiesce the thread
+	 * (dm_wq_work), we set DMF_BLOCK_IO_FOR_SUSPEND and call
+	 * flush_workqueue(md->wq).
+	 */
+	set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
+	if (map)
+		synchronize_srcu(&md->io_barrier);
+
+	/*
+	 * Stop md->queue before flushing md->wq in case request-based
+	 * dm defers requests to md->wq from md->queue.
+	 */
+	if (dm_request_based(md))
+		dm_stop_queue(md->queue);
+
+	flush_workqueue(md->wq);
+
+	/*
+	 * At this point no more requests are entering target request routines.
+	 * We call dm_wait_for_completion to wait for all existing requests
+	 * to finish.
+	 */
+	r = dm_wait_for_completion(md, task_state);
+	if (!r)
+		set_bit(dmf_suspended_flag, &md->flags);
+
+	if (noflush)
+		clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
+	if (map)
+		synchronize_srcu(&md->io_barrier);
+
+	/* were we interrupted ? */
+	if (r < 0) {
+		dm_queue_flush(md);
+
+		if (dm_request_based(md))
+			dm_start_queue(md->queue);
+
+		unlock_fs(md);
+		dm_table_presuspend_undo_targets(map);
+		/* pushback list is already flushed, so skip flush */
+	}
+
+	return r;
+}
+
+/*
+ * We need to be able to change a mapping table under a mounted
+ * filesystem.  For example we might want to move some data in
+ * the background.  Before the table can be swapped with
+ * dm_bind_table, dm_suspend must be called to flush any in
+ * flight bios and ensure that any further io gets deferred.
+ */
+/*
+ * Suspend mechanism in request-based dm.
+ *
+ * 1. Flush all I/Os by lock_fs() if needed.
+ * 2. Stop dispatching any I/O by stopping the request_queue.
+ * 3. Wait for all in-flight I/Os to be completed or requeued.
+ *
+ * To abort suspend, start the request_queue.
+ */
+int dm_suspend(struct mapped_device *md, unsigned int suspend_flags)
+{
+	struct dm_table *map = NULL;
+	int r = 0;
+
+retry:
+	mutex_lock_nested(&md->suspend_lock, SINGLE_DEPTH_NESTING);
+
+	if (dm_suspended_md(md)) {
+		r = -EINVAL;
+		goto out_unlock;
+	}
+
+	if (dm_suspended_internally_md(md)) {
+		/* already internally suspended, wait for internal resume */
+		mutex_unlock(&md->suspend_lock);
+		r = wait_on_bit(&md->flags, DMF_SUSPENDED_INTERNALLY, TASK_INTERRUPTIBLE);
+		if (r)
+			return r;
+		goto retry;
+	}
+
+	map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock));
+	if (!map) {
+		/* avoid deadlock with fs/namespace.c:do_mount() */
+		suspend_flags &= ~DM_SUSPEND_LOCKFS_FLAG;
+	}
+
+	r = __dm_suspend(md, map, suspend_flags, TASK_INTERRUPTIBLE, DMF_SUSPENDED);
+	if (r)
+		goto out_unlock;
+
+	set_bit(DMF_POST_SUSPENDING, &md->flags);
+	dm_table_postsuspend_targets(map);
+	clear_bit(DMF_POST_SUSPENDING, &md->flags);
+
+out_unlock:
+	mutex_unlock(&md->suspend_lock);
+	return r;
+}
+
+static int __dm_resume(struct mapped_device *md, struct dm_table *map)
+{
+	if (map) {
+		int r = dm_table_resume_targets(map);
+		if (r)
+			return r;
+	}
+
+	dm_queue_flush(md);
+
+	/*
+	 * Flushing deferred I/Os must be done after targets are resumed
+	 * so that mapping of targets can work correctly.
+	 * Request-based dm is queueing the deferred I/Os in its request_queue.
+	 */
+	if (dm_request_based(md))
+		dm_start_queue(md->queue);
+
+	unlock_fs(md);
+
+	return 0;
+}
+
+int dm_resume(struct mapped_device *md)
+{
+	int r;
+	struct dm_table *map = NULL;
+
+retry:
+	r = -EINVAL;
+	mutex_lock_nested(&md->suspend_lock, SINGLE_DEPTH_NESTING);
+
+	if (!dm_suspended_md(md))
+		goto out;
+
+	if (dm_suspended_internally_md(md)) {
+		/* already internally suspended, wait for internal resume */
+		mutex_unlock(&md->suspend_lock);
+		r = wait_on_bit(&md->flags, DMF_SUSPENDED_INTERNALLY, TASK_INTERRUPTIBLE);
+		if (r)
+			return r;
+		goto retry;
+	}
+
+	map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock));
+	if (!map || !dm_table_get_size(map))
+		goto out;
+
+	r = __dm_resume(md, map);
+	if (r)
+		goto out;
+
+	clear_bit(DMF_SUSPENDED, &md->flags);
+out:
+	mutex_unlock(&md->suspend_lock);
+
+	return r;
+}
+
+/*
+ * Internal suspend/resume works like userspace-driven suspend. It waits
+ * until all bios finish and prevents issuing new bios to the target drivers.
+ * It may be used only from the kernel.
+ */
+
+static void __dm_internal_suspend(struct mapped_device *md, unsigned int suspend_flags)
+{
+	struct dm_table *map = NULL;
+
+	lockdep_assert_held(&md->suspend_lock);
+
+	if (md->internal_suspend_count++)
+		return; /* nested internal suspend */
+
+	if (dm_suspended_md(md)) {
+		set_bit(DMF_SUSPENDED_INTERNALLY, &md->flags);
+		return; /* nest suspend */
+	}
+
+	map = rcu_dereference_protected(md->map, lockdep_is_held(&md->suspend_lock));
+
+	/*
+	 * Using TASK_UNINTERRUPTIBLE because only NOFLUSH internal suspend is
+	 * supported.  Properly supporting a TASK_INTERRUPTIBLE internal suspend
+	 * would require changing .presuspend to return an error -- avoid this
+	 * until there is a need for more elaborate variants of internal suspend.
+	 */
+	(void) __dm_suspend(md, map, suspend_flags, TASK_UNINTERRUPTIBLE,
+			    DMF_SUSPENDED_INTERNALLY);
+
+	set_bit(DMF_POST_SUSPENDING, &md->flags);
+	dm_table_postsuspend_targets(map);
+	clear_bit(DMF_POST_SUSPENDING, &md->flags);
+}
+
+static void __dm_internal_resume(struct mapped_device *md)
+{
+	BUG_ON(!md->internal_suspend_count);
+
+	if (--md->internal_suspend_count)
+		return; /* resume from nested internal suspend */
+
+	if (dm_suspended_md(md))
+		goto done; /* resume from nested suspend */
+
+	/*
+	 * NOTE: existing callers don't need to call dm_table_resume_targets
+	 * (which may fail -- so best to avoid it for now by passing NULL map)
+	 */
+	(void) __dm_resume(md, NULL);
+
+done:
+	clear_bit(DMF_SUSPENDED_INTERNALLY, &md->flags);
+	smp_mb__after_atomic();
+	wake_up_bit(&md->flags, DMF_SUSPENDED_INTERNALLY);
+}
+
+void dm_internal_suspend_noflush(struct mapped_device *md)
+{
+	mutex_lock(&md->suspend_lock);
+	__dm_internal_suspend(md, DM_SUSPEND_NOFLUSH_FLAG);
+	mutex_unlock(&md->suspend_lock);
+}
+EXPORT_SYMBOL_GPL(dm_internal_suspend_noflush);
+
+void dm_internal_resume(struct mapped_device *md)
+{
+	mutex_lock(&md->suspend_lock);
+	__dm_internal_resume(md);
+	mutex_unlock(&md->suspend_lock);
+}
+EXPORT_SYMBOL_GPL(dm_internal_resume);
+
+/*
+ * Fast variants of internal suspend/resume hold md->suspend_lock,
+ * which prevents interaction with userspace-driven suspend.
+ */
+
+void dm_internal_suspend_fast(struct mapped_device *md)
+{
+	mutex_lock(&md->suspend_lock);
+	if (dm_suspended_md(md) || dm_suspended_internally_md(md))
+		return;
+
+	set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
+	synchronize_srcu(&md->io_barrier);
+	flush_workqueue(md->wq);
+	dm_wait_for_completion(md, TASK_UNINTERRUPTIBLE);
+}
+EXPORT_SYMBOL_GPL(dm_internal_suspend_fast);
+
+void dm_internal_resume_fast(struct mapped_device *md)
+{
+	if (dm_suspended_md(md) || dm_suspended_internally_md(md))
+		goto done;
+
+	dm_queue_flush(md);
+
+done:
+	mutex_unlock(&md->suspend_lock);
+}
+EXPORT_SYMBOL_GPL(dm_internal_resume_fast);
+
+/*-----------------------------------------------------------------
+ * Event notification.
+ *---------------------------------------------------------------*/
+int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
+		      unsigned int cookie, bool need_resize_uevent)
+{
+	int r;
+	unsigned int noio_flag;
+	char udev_cookie[DM_COOKIE_LENGTH];
+	char *envp[3] = { NULL, NULL, NULL };
+	char **envpp = envp;
+	if (cookie) {
+		snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u",
+			 DM_COOKIE_ENV_VAR_NAME, cookie);
+		*envpp++ = udev_cookie;
+	}
+	if (need_resize_uevent) {
+		*envpp++ = "RESIZE=1";
+	}
+
+	noio_flag = memalloc_noio_save();
+
+	r = kobject_uevent_env(&disk_to_dev(md->disk)->kobj, action, envp);
+
+	memalloc_noio_restore(noio_flag);
+
+	return r;
+}
+
+uint32_t dm_next_uevent_seq(struct mapped_device *md)
+{
+	return atomic_add_return(1, &md->uevent_seq);
+}
+
+uint32_t dm_get_event_nr(struct mapped_device *md)
+{
+	return atomic_read(&md->event_nr);
+}
+
+int dm_wait_event(struct mapped_device *md, int event_nr)
+{
+	return wait_event_interruptible(md->eventq,
+			(event_nr != atomic_read(&md->event_nr)));
+}
+
+void dm_uevent_add(struct mapped_device *md, struct list_head *elist)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&md->uevent_lock, flags);
+	list_add(elist, &md->uevent_list);
+	spin_unlock_irqrestore(&md->uevent_lock, flags);
+}
+
+/*
+ * The gendisk is only valid as long as you have a reference
+ * count on 'md'.
+ */
+struct gendisk *dm_disk(struct mapped_device *md)
+{
+	return md->disk;
+}
+EXPORT_SYMBOL_GPL(dm_disk);
+
+struct kobject *dm_kobject(struct mapped_device *md)
+{
+	return &md->kobj_holder.kobj;
+}
+
+struct mapped_device *dm_get_from_kobject(struct kobject *kobj)
+{
+	struct mapped_device *md;
+
+	md = container_of(kobj, struct mapped_device, kobj_holder.kobj);
+
+	spin_lock(&_minor_lock);
+	if (test_bit(DMF_FREEING, &md->flags) || dm_deleting_md(md)) {
+		md = NULL;
+		goto out;
+	}
+	dm_get(md);
+out:
+	spin_unlock(&_minor_lock);
+
+	return md;
+}
+
+int dm_suspended_md(struct mapped_device *md)
+{
+	return test_bit(DMF_SUSPENDED, &md->flags);
+}
+
+static int dm_post_suspending_md(struct mapped_device *md)
+{
+	return test_bit(DMF_POST_SUSPENDING, &md->flags);
+}
+
+int dm_suspended_internally_md(struct mapped_device *md)
+{
+	return test_bit(DMF_SUSPENDED_INTERNALLY, &md->flags);
+}
+
+int dm_test_deferred_remove_flag(struct mapped_device *md)
+{
+	return test_bit(DMF_DEFERRED_REMOVE, &md->flags);
+}
+
+int dm_suspended(struct dm_target *ti)
+{
+	return dm_suspended_md(ti->table->md);
+}
+EXPORT_SYMBOL_GPL(dm_suspended);
+
+int dm_post_suspending(struct dm_target *ti)
+{
+	return dm_post_suspending_md(ti->table->md);
+}
+EXPORT_SYMBOL_GPL(dm_post_suspending);
+
+int dm_noflush_suspending(struct dm_target *ti)
+{
+	return __noflush_suspending(ti->table->md);
+}
+EXPORT_SYMBOL_GPL(dm_noflush_suspending);
+
+void dm_free_md_mempools(struct dm_md_mempools *pools)
+{
+	if (!pools)
+		return;
+
+	bioset_exit(&pools->bs);
+	bioset_exit(&pools->io_bs);
+
+	kfree(pools);
+}
+
+struct dm_pr {
+	u64	old_key;
+	u64	new_key;
+	u32	flags;
+	bool	abort;
+	bool	fail_early;
+	int	ret;
+	enum pr_type type;
+};
+
+static int dm_call_pr(struct block_device *bdev, iterate_devices_callout_fn fn,
+		      struct dm_pr *pr)
+{
+	struct mapped_device *md = bdev->bd_disk->private_data;
+	struct dm_table *table;
+	struct dm_target *ti;
+	int ret = -ENOTTY, srcu_idx;
+
+	table = dm_get_live_table(md, &srcu_idx);
+	if (!table || !dm_table_get_size(table))
+		goto out;
+
+	/* We only support devices that have a single target */
+	if (table->num_targets != 1)
+		goto out;
+	ti = dm_table_get_target(table, 0);
+
+	if (dm_suspended_md(md)) {
+		ret = -EAGAIN;
+		goto out;
+	}
+
+	ret = -EINVAL;
+	if (!ti->type->iterate_devices)
+		goto out;
+
+	ti->type->iterate_devices(ti, fn, pr);
+	ret = 0;
+out:
+	dm_put_live_table(md, srcu_idx);
+	return ret;
+}
+
+/*
+ * For register / unregister we need to manually call out to every path.
+ */
+static int __dm_pr_register(struct dm_target *ti, struct dm_dev *dev,
+			    sector_t start, sector_t len, void *data)
+{
+	struct dm_pr *pr = data;
+	const struct pr_ops *ops = dev->bdev->bd_disk->fops->pr_ops;
+	int ret;
+
+	if (!ops || !ops->pr_register) {
+		pr->ret = -EOPNOTSUPP;
+		return -1;
+	}
+
+	ret = ops->pr_register(dev->bdev, pr->old_key, pr->new_key, pr->flags);
+	if (!ret)
+		return 0;
+
+	if (!pr->ret)
+		pr->ret = ret;
+
+	if (pr->fail_early)
+		return -1;
+
+	return 0;
+}
+
+static int dm_pr_register(struct block_device *bdev, u64 old_key, u64 new_key,
+			  u32 flags)
+{
+	struct dm_pr pr = {
+		.old_key	= old_key,
+		.new_key	= new_key,
+		.flags		= flags,
+		.fail_early	= true,
+		.ret		= 0,
+	};
+	int ret;
+
+	ret = dm_call_pr(bdev, __dm_pr_register, &pr);
+	if (ret) {
+		/* Didn't even get to register a path */
+		return ret;
+	}
+
+	if (!pr.ret)
+		return 0;
+	ret = pr.ret;
+
+	if (!new_key)
+		return ret;
+
+	/* unregister all paths if we failed to register any path */
+	pr.old_key = new_key;
+	pr.new_key = 0;
+	pr.flags = 0;
+	pr.fail_early = false;
+	(void) dm_call_pr(bdev, __dm_pr_register, &pr);
+	return ret;
+}
+
+
+static int __dm_pr_reserve(struct dm_target *ti, struct dm_dev *dev,
+			   sector_t start, sector_t len, void *data)
+{
+	struct dm_pr *pr = data;
+	const struct pr_ops *ops = dev->bdev->bd_disk->fops->pr_ops;
+
+	if (!ops || !ops->pr_reserve) {
+		pr->ret = -EOPNOTSUPP;
+		return -1;
+	}
+
+	pr->ret = ops->pr_reserve(dev->bdev, pr->old_key, pr->type, pr->flags);
+	if (!pr->ret)
+		return -1;
+
+	return 0;
+}
+
+static int dm_pr_reserve(struct block_device *bdev, u64 key, enum pr_type type,
+			 u32 flags)
+{
+	struct dm_pr pr = {
+		.old_key	= key,
+		.flags		= flags,
+		.type		= type,
+		.fail_early	= false,
+		.ret		= 0,
+	};
+	int ret;
+
+	ret = dm_call_pr(bdev, __dm_pr_reserve, &pr);
+	if (ret)
+		return ret;
+
+	return pr.ret;
+}
+
+/*
+ * If there is a non-All Registrants type of reservation, the release must be
+ * sent down the holding path. For the cases where there is no reservation or
+ * the path is not the holder the device will also return success, so we must
+ * try each path to make sure we got the correct path.
+ */
+static int __dm_pr_release(struct dm_target *ti, struct dm_dev *dev,
+			   sector_t start, sector_t len, void *data)
+{
+	struct dm_pr *pr = data;
+	const struct pr_ops *ops = dev->bdev->bd_disk->fops->pr_ops;
+
+	if (!ops || !ops->pr_release) {
+		pr->ret = -EOPNOTSUPP;
+		return -1;
+	}
+
+	pr->ret = ops->pr_release(dev->bdev, pr->old_key, pr->type);
+	if (pr->ret)
+		return -1;
+
+	return 0;
+}
+
+static int dm_pr_release(struct block_device *bdev, u64 key, enum pr_type type)
+{
+	struct dm_pr pr = {
+		.old_key	= key,
+		.type		= type,
+		.fail_early	= false,
+	};
+	int ret;
+
+	ret = dm_call_pr(bdev, __dm_pr_release, &pr);
+	if (ret)
+		return ret;
+
+	return pr.ret;
+}
+
+static int __dm_pr_preempt(struct dm_target *ti, struct dm_dev *dev,
+			   sector_t start, sector_t len, void *data)
+{
+	struct dm_pr *pr = data;
+	const struct pr_ops *ops = dev->bdev->bd_disk->fops->pr_ops;
+
+	if (!ops || !ops->pr_preempt) {
+		pr->ret = -EOPNOTSUPP;
+		return -1;
+	}
+
+	pr->ret = ops->pr_preempt(dev->bdev, pr->old_key, pr->new_key, pr->type,
+				  pr->abort);
+	if (!pr->ret)
+		return -1;
+
+	return 0;
+}
+
+static int dm_pr_preempt(struct block_device *bdev, u64 old_key, u64 new_key,
+			 enum pr_type type, bool abort)
+{
+	struct dm_pr pr = {
+		.new_key	= new_key,
+		.old_key	= old_key,
+		.type		= type,
+		.fail_early	= false,
+	};
+	int ret;
+
+	ret = dm_call_pr(bdev, __dm_pr_preempt, &pr);
+	if (ret)
+		return ret;
+
+	return pr.ret;
+}
+
+static int dm_pr_clear(struct block_device *bdev, u64 key)
+{
+	struct mapped_device *md = bdev->bd_disk->private_data;
+	const struct pr_ops *ops;
+	int r, srcu_idx;
+
+	r = dm_prepare_ioctl(md, &srcu_idx, &bdev);
+	if (r < 0)
+		goto out;
+
+	ops = bdev->bd_disk->fops->pr_ops;
+	if (ops && ops->pr_clear)
+		r = ops->pr_clear(bdev, key);
+	else
+		r = -EOPNOTSUPP;
+out:
+	dm_unprepare_ioctl(md, srcu_idx);
+	return r;
+}
+
+static const struct pr_ops dm_pr_ops = {
+	.pr_register	= dm_pr_register,
+	.pr_reserve	= dm_pr_reserve,
+	.pr_release	= dm_pr_release,
+	.pr_preempt	= dm_pr_preempt,
+	.pr_clear	= dm_pr_clear,
+};
+
+static const struct block_device_operations dm_blk_dops = {
+	.submit_bio = dm_submit_bio,
+	.poll_bio = dm_poll_bio,
+	.open = dm_blk_open,
+	.release = dm_blk_close,
+	.ioctl = dm_blk_ioctl,
+	.getgeo = dm_blk_getgeo,
+	.report_zones = dm_blk_report_zones,
+	.pr_ops = &dm_pr_ops,
+	.owner = THIS_MODULE
+};
+
+static const struct block_device_operations dm_rq_blk_dops = {
+	.open = dm_blk_open,
+	.release = dm_blk_close,
+	.ioctl = dm_blk_ioctl,
+	.getgeo = dm_blk_getgeo,
+	.pr_ops = &dm_pr_ops,
+	.owner = THIS_MODULE
+};
+
+static const struct dax_operations dm_dax_ops = {
+	.direct_access = dm_dax_direct_access,
+	.zero_page_range = dm_dax_zero_page_range,
+	.recovery_write = dm_dax_recovery_write,
+};
+
+/*
+ * module hooks
+ */
+module_init(dm_init);
+module_exit(dm_exit);
+
+module_param(major, uint, 0);
+MODULE_PARM_DESC(major, "The major number of the device mapper");
+
+module_param(reserved_bio_based_ios, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(reserved_bio_based_ios, "Reserved IOs in bio-based mempools");
+
+module_param(dm_numa_node, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(dm_numa_node, "NUMA node for DM device memory allocations");
+
+module_param(swap_bios, int, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(swap_bios, "Maximum allowed inflight swap IOs");
+
+MODULE_DESCRIPTION(DM_NAME " driver");
+MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
+MODULE_LICENSE("GPL");