Moved, renamed, and deleted files

The original directory structure was scattered and unorganized.
Changes are basically to make it look like kernel structure.

1 files changed, 2780 insertions, 0 deletions

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
new file mode 100644
index 00000000..e24143cc
--- /dev/null
+++ b/drivers/md/dm.c
@@ -0,0 +1,2780 @@
+/*
+ * 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.h"
+#include "dm-uevent.h"
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/moduleparam.h>
+#include <linux/blkpg.h>
+#include <linux/bio.h>
+#include <linux/mempool.h>
+#include <linux/slab.h>
+#include <linux/idr.h>
+#include <linux/hdreg.h>
+#include <linux/delay.h>
+
+#include <trace/events/block.h>
+
+#define DM_MSG_PREFIX "core"
+
+#ifdef CONFIG_PRINTK
+/*
+ * ratelimit state to be used in DMXXX_LIMIT().
+ */
+DEFINE_RATELIMIT_STATE(dm_ratelimit_state,
+		       DEFAULT_RATELIMIT_INTERVAL,
+		       DEFAULT_RATELIMIT_BURST);
+EXPORT_SYMBOL(dm_ratelimit_state);
+#endif
+
+/*
+ * 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
+
+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);
+/*
+ * For bio-based dm.
+ * One of these is allocated per bio.
+ */
+struct dm_io {
+	struct mapped_device *md;
+	int error;
+	atomic_t io_count;
+	struct bio *bio;
+	unsigned long start_time;
+	spinlock_t endio_lock;
+};
+
+/*
+ * For bio-based dm.
+ * One of these is allocated per target within a bio.  Hopefully
+ * this will be simplified out one day.
+ */
+struct dm_target_io {
+	struct dm_io *io;
+	struct dm_target *ti;
+	union map_info info;
+};
+
+/*
+ * For request-based dm.
+ * One of these is allocated per request.
+ */
+struct dm_rq_target_io {
+	struct mapped_device *md;
+	struct dm_target *ti;
+	struct request *orig, clone;
+	int error;
+	union map_info info;
+};
+
+/*
+ * For request-based dm.
+ * One of these is allocated per bio.
+ */
+struct dm_rq_clone_bio_info {
+	struct bio *orig;
+	struct dm_rq_target_io *tio;
+};
+
+union map_info *dm_get_mapinfo(struct bio *bio)
+{
+	if (bio && bio->bi_private)
+		return &((struct dm_target_io *)bio->bi_private)->info;
+	return NULL;
+}
+
+union map_info *dm_get_rq_mapinfo(struct request *rq)
+{
+	if (rq && rq->end_io_data)
+		return &((struct dm_rq_target_io *)rq->end_io_data)->info;
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(dm_get_rq_mapinfo);
+
+#define MINOR_ALLOCED ((void *)-1)
+
+/*
+ * Bits for the md->flags field.
+ */
+#define DMF_BLOCK_IO_FOR_SUSPEND 0
+#define DMF_SUSPENDED 1
+#define DMF_FROZEN 2
+#define DMF_FREEING 3
+#define DMF_DELETING 4
+#define DMF_NOFLUSH_SUSPENDING 5
+#define DMF_MERGE_IS_OPTIONAL 6
+
+/*
+ * Work processed by per-device workqueue.
+ */
+struct mapped_device {
+	struct rw_semaphore io_lock;
+	struct mutex suspend_lock;
+	rwlock_t map_lock;
+	atomic_t holders;
+	atomic_t open_count;
+
+	unsigned long flags;
+
+	struct request_queue *queue;
+	unsigned type;
+	/* Protect queue and type against concurrent access. */
+	struct mutex type_lock;
+
+	struct target_type *immutable_target_type;
+
+	struct gendisk *disk;
+	char name[16];
+
+	void *interface_ptr;
+
+	/*
+	 * A list of ios that arrived while we were suspended.
+	 */
+	atomic_t pending[2];
+	wait_queue_head_t wait;
+	struct work_struct work;
+	struct bio_list deferred;
+	spinlock_t deferred_lock;
+
+	/*
+	 * Processing queue (flush)
+	 */
+	struct workqueue_struct *wq;
+
+	/*
+	 * The current mapping.
+	 */
+	struct dm_table *map;
+
+	/*
+	 * io objects are allocated from here.
+	 */
+	mempool_t *io_pool;
+	mempool_t *tio_pool;
+
+	struct bio_set *bs;
+
+	/*
+	 * Event handling.
+	 */
+	atomic_t event_nr;
+	wait_queue_head_t eventq;
+	atomic_t uevent_seq;
+	struct list_head uevent_list;
+	spinlock_t uevent_lock; /* Protect access to uevent_list */
+
+	/*
+	 * freeze/thaw support require holding onto a super block
+	 */
+	struct super_block *frozen_sb;
+	struct block_device *bdev;
+
+	/* forced geometry settings */
+	struct hd_geometry geometry;
+
+	/* sysfs handle */
+	struct kobject kobj;
+
+	/* zero-length flush that will be cloned and submitted to targets */
+	struct bio flush_bio;
+};
+
+/*
+ * For mempools pre-allocation at the table loading time.
+ */
+struct dm_md_mempools {
+	mempool_t *io_pool;
+	mempool_t *tio_pool;
+	struct bio_set *bs;
+};
+
+#define MIN_IOS 256
+static struct kmem_cache *_io_cache;
+static struct kmem_cache *_tio_cache;
+static struct kmem_cache *_rq_tio_cache;
+static struct kmem_cache *_rq_bio_info_cache;
+
+static int __init local_init(void)
+{
+	int r = -ENOMEM;
+
+	/* allocate a slab for the dm_ios */
+	_io_cache = KMEM_CACHE(dm_io, 0);
+	if (!_io_cache)
+		return r;
+
+	/* allocate a slab for the target ios */
+	_tio_cache = KMEM_CACHE(dm_target_io, 0);
+	if (!_tio_cache)
+		goto out_free_io_cache;
+
+	_rq_tio_cache = KMEM_CACHE(dm_rq_target_io, 0);
+	if (!_rq_tio_cache)
+		goto out_free_tio_cache;
+
+	_rq_bio_info_cache = KMEM_CACHE(dm_rq_clone_bio_info, 0);
+	if (!_rq_bio_info_cache)
+		goto out_free_rq_tio_cache;
+
+	r = dm_uevent_init();
+	if (r)
+		goto out_free_rq_bio_info_cache;
+
+	_major = major;
+	r = register_blkdev(_major, _name);
+	if (r < 0)
+		goto out_uevent_exit;
+
+	if (!_major)
+		_major = r;
+
+	return 0;
+
+out_uevent_exit:
+	dm_uevent_exit();
+out_free_rq_bio_info_cache:
+	kmem_cache_destroy(_rq_bio_info_cache);
+out_free_rq_tio_cache:
+	kmem_cache_destroy(_rq_tio_cache);
+out_free_tio_cache:
+	kmem_cache_destroy(_tio_cache);
+out_free_io_cache:
+	kmem_cache_destroy(_io_cache);
+
+	return r;
+}
+
+static void local_exit(void)
+{
+	kmem_cache_destroy(_rq_bio_info_cache);
+	kmem_cache_destroy(_rq_tio_cache);
+	kmem_cache_destroy(_tio_cache);
+	kmem_cache_destroy(_io_cache);
+	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,
+};
+
+static void (*_exits[])(void) = {
+	local_exit,
+	dm_target_exit,
+	dm_linear_exit,
+	dm_stripe_exit,
+	dm_io_exit,
+	dm_kcopyd_exit,
+	dm_interface_exit,
+};
+
+static int __init dm_init(void)
+{
+	const int count = ARRAY_SIZE(_inits);
+
+	int r, i;
+
+	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_remove_all(&_minor_idr);
+	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 int dm_blk_close(struct gendisk *disk, fmode_t mode)
+{
+	struct mapped_device *md = disk->private_data;
+
+	spin_lock(&_minor_lock);
+
+	atomic_dec(&md->open_count);
+	dm_put(md);
+
+	spin_unlock(&_minor_lock);
+
+	return 0;
+}
+
+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)
+{
+	int r = 0;
+
+	spin_lock(&_minor_lock);
+
+	if (dm_open_count(md))
+		r = -EBUSY;
+	else
+		set_bit(DMF_DELETING, &md->flags);
+
+	spin_unlock(&_minor_lock);
+
+	return r;
+}
+
+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_blk_ioctl(struct block_device *bdev, fmode_t mode,
+			unsigned int cmd, unsigned long arg)
+{
+	struct mapped_device *md = bdev->bd_disk->private_data;
+	struct dm_table *map = dm_get_live_table(md);
+	struct dm_target *tgt;
+	int r = -ENOTTY;
+
+	if (!map || !dm_table_get_size(map))
+		goto out;
+
+	/* We only support devices that have a single target */
+	if (dm_table_get_num_targets(map) != 1)
+		goto out;
+
+	tgt = dm_table_get_target(map, 0);
+
+	if (dm_suspended_md(md)) {
+		r = -EAGAIN;
+		goto out;
+	}
+
+	if (tgt->type->ioctl)
+		r = tgt->type->ioctl(tgt, cmd, arg);
+
+out:
+	dm_table_put(map);
+
+	return r;
+}
+
+static struct dm_io *alloc_io(struct mapped_device *md)
+{
+	return mempool_alloc(md->io_pool, GFP_NOIO);
+}
+
+static void free_io(struct mapped_device *md, struct dm_io *io)
+{
+	mempool_free(io, md->io_pool);
+}
+
+static void free_tio(struct mapped_device *md, struct dm_target_io *tio)
+{
+	mempool_free(tio, md->tio_pool);
+}
+
+static struct dm_rq_target_io *alloc_rq_tio(struct mapped_device *md,
+					    gfp_t gfp_mask)
+{
+	return mempool_alloc(md->tio_pool, gfp_mask);
+}
+
+static void free_rq_tio(struct dm_rq_target_io *tio)
+{
+	mempool_free(tio, tio->md->tio_pool);
+}
+
+static struct dm_rq_clone_bio_info *alloc_bio_info(struct mapped_device *md)
+{
+	return mempool_alloc(md->io_pool, GFP_ATOMIC);
+}
+
+static void free_bio_info(struct dm_rq_clone_bio_info *info)
+{
+	mempool_free(info, info->tio->md->io_pool);
+}
+
+static int md_in_flight(struct mapped_device *md)
+{
+	return atomic_read(&md->pending[READ]) +
+	       atomic_read(&md->pending[WRITE]);
+}
+
+static void start_io_acct(struct dm_io *io)
+{
+	struct mapped_device *md = io->md;
+	int cpu;
+	int rw = bio_data_dir(io->bio);
+
+	io->start_time = jiffies;
+
+	cpu = part_stat_lock();
+	part_round_stats(cpu, &dm_disk(md)->part0);
+	part_stat_unlock();
+	atomic_set(&dm_disk(md)->part0.in_flight[rw],
+		atomic_inc_return(&md->pending[rw]));
+}
+
+static void end_io_acct(struct dm_io *io)
+{
+	struct mapped_device *md = io->md;
+	struct bio *bio = io->bio;
+	unsigned long duration = jiffies - io->start_time;
+	int pending, cpu;
+	int rw = bio_data_dir(bio);
+
+	cpu = part_stat_lock();
+	part_round_stats(cpu, &dm_disk(md)->part0);
+	part_stat_add(cpu, &dm_disk(md)->part0, ticks[rw], duration);
+	part_stat_unlock();
+
+	/*
+	 * After this is decremented the bio must not be touched if it is
+	 * a flush.
+	 */
+	pending = atomic_dec_return(&md->pending[rw]);
+	atomic_set(&dm_disk(md)->part0.in_flight[rw], pending);
+	pending += atomic_read(&md->pending[rw^0x1]);
+
+	/* nudge anyone waiting on suspend queue */
+	if (!pending)
+		wake_up(&md->wait);
+}
+
+/*
+ * 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_table_put() when finished.
+ */
+struct dm_table *dm_get_live_table(struct mapped_device *md)
+{
+	struct dm_table *t;
+	unsigned long flags;
+
+	read_lock_irqsave(&md->map_lock, flags);
+	t = md->map;
+	if (t)
+		dm_table_get(t);
+	read_unlock_irqrestore(&md->map_lock, flags);
+
+	return t;
+}
+
+/*
+ * 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) {
+		DMWARN("Start sector is beyond the geometry limits.");
+		return -EINVAL;
+	}
+
+	md->geometry = *geo;
+
+	return 0;
+}
+
+/*-----------------------------------------------------------------
+ * CRUD START:
+ *   A more elegant soln is in the works that uses the queue
+ *   merge fn, unfortunately there are a couple of changes to
+ *   the block layer that I want to make for this.  So in the
+ *   interests of getting something for people to use I give
+ *   you this clearly demarcated crap.
+ *---------------------------------------------------------------*/
+
+static int __noflush_suspending(struct mapped_device *md)
+{
+	return test_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
+}
+
+/*
+ * Decrements the number of outstanding ios that a bio has been
+ * cloned into, completing the original io if necc.
+ */
+static void dec_pending(struct dm_io *io, int error)
+{
+	unsigned long flags;
+	int io_error;
+	struct bio *bio;
+	struct mapped_device *md = io->md;
+
+	/* Push-back supersedes any I/O errors */
+	if (unlikely(error)) {
+		spin_lock_irqsave(&io->endio_lock, flags);
+		if (!(io->error > 0 && __noflush_suspending(md)))
+			io->error = error;
+		spin_unlock_irqrestore(&io->endio_lock, flags);
+	}
+
+	if (atomic_dec_and_test(&io->io_count)) {
+		if (io->error == DM_ENDIO_REQUEUE) {
+			/*
+			 * Target requested pushing back the I/O.
+			 */
+			spin_lock_irqsave(&md->deferred_lock, flags);
+			if (__noflush_suspending(md))
+				bio_list_add_head(&md->deferred, io->bio);
+			else
+				/* noflush suspend was interrupted. */
+				io->error = -EIO;
+			spin_unlock_irqrestore(&md->deferred_lock, flags);
+		}
+
+		io_error = io->error;
+		bio = io->bio;
+		end_io_acct(io);
+		free_io(md, io);
+
+		if (io_error == DM_ENDIO_REQUEUE)
+			return;
+
+		if ((bio->bi_rw & REQ_FLUSH) && bio->bi_size) {
+			/*
+			 * Preflush done for flush with data, reissue
+			 * without REQ_FLUSH.
+			 */
+			bio->bi_rw &= ~REQ_FLUSH;
+			queue_io(md, bio);
+		} else {
+			/* done with normal IO or empty flush */
+			trace_block_bio_complete(md->queue, bio, io_error);
+			bio_endio(bio, io_error);
+		}
+	}
+}
+
+static void clone_endio(struct bio *bio, int error)
+{
+	int r = 0;
+	struct dm_target_io *tio = bio->bi_private;
+	struct dm_io *io = tio->io;
+	struct mapped_device *md = tio->io->md;
+	dm_endio_fn endio = tio->ti->type->end_io;
+
+	if (!bio_flagged(bio, BIO_UPTODATE) && !error)
+		error = -EIO;
+
+	if (endio) {
+		r = endio(tio->ti, bio, error, &tio->info);
+		if (r < 0 || r == DM_ENDIO_REQUEUE)
+			/*
+			 * error and requeue request are handled
+			 * in dec_pending().
+			 */
+			error = r;
+		else if (r == DM_ENDIO_INCOMPLETE)
+			/* The target will handle the io */
+			return;
+		else if (r) {
+			DMWARN("unimplemented target endio return value: %d", r);
+			BUG();
+		}
+	}
+
+	/*
+	 * Store md for cleanup instead of tio which is about to get freed.
+	 */
+	bio->bi_private = md->bs;
+
+	free_tio(md, tio);
+	bio_put(bio);
+	dec_pending(io, error);
+}
+
+/*
+ * Partial completion handling for request-based dm
+ */
+static void end_clone_bio(struct bio *clone, int error)
+{
+	struct dm_rq_clone_bio_info *info = clone->bi_private;
+	struct dm_rq_target_io *tio = info->tio;
+	struct bio *bio = info->orig;
+	unsigned int nr_bytes = info->orig->bi_size;
+
+	bio_put(clone);
+
+	if (tio->error)
+		/*
+		 * An error has already been detected on the request.
+		 * Once error occurred, just let clone->end_io() handle
+		 * the remainder.
+		 */
+		return;
+	else if (error) {
+		/*
+		 * Don't notice the error to the upper layer yet.
+		 * The error handling decision is made by the target driver,
+		 * when the request is completed.
+		 */
+		tio->error = error;
+		return;
+	}
+
+	/*
+	 * I/O for the bio successfully completed.
+	 * Notice the data completion to the upper layer.
+	 */
+
+	/*
+	 * bios are processed from the head of the list.
+	 * So the completing bio should always be rq->bio.
+	 * If it's not, something wrong is happening.
+	 */
+	if (tio->orig->bio != bio)
+		DMERR("bio completion is going in the middle of the request");
+
+	/*
+	 * Update the original request.
+	 * Do not use blk_end_request() here, because it may complete
+	 * the original request before the clone, and break the ordering.
+	 */
+	blk_update_request(tio->orig, 0, nr_bytes);
+}
+
+/*
+ * Don't touch any member of the md after calling this function because
+ * the md may be freed in dm_put() at the end of this function.
+ * Or do dm_get() before calling this function and dm_put() later.
+ */
+static void rq_completed(struct mapped_device *md, int rw, int run_queue)
+{
+	atomic_dec(&md->pending[rw]);
+
+	/* nudge anyone waiting on suspend queue */
+	if (!md_in_flight(md))
+		wake_up(&md->wait);
+
+	if (run_queue)
+		blk_run_queue(md->queue);
+
+	/*
+	 * dm_put() must be at the end of this function. See the comment above
+	 */
+	dm_put(md);
+}
+
+static void free_rq_clone(struct request *clone)
+{
+	struct dm_rq_target_io *tio = clone->end_io_data;
+
+	blk_rq_unprep_clone(clone);
+	free_rq_tio(tio);
+}
+
+/*
+ * Complete the clone and the original request.
+ * Must be called without queue lock.
+ */
+static void dm_end_request(struct request *clone, int error)
+{
+	int rw = rq_data_dir(clone);
+	struct dm_rq_target_io *tio = clone->end_io_data;
+	struct mapped_device *md = tio->md;
+	struct request *rq = tio->orig;
+
+	if (rq->cmd_type == REQ_TYPE_BLOCK_PC) {
+		rq->errors = clone->errors;
+		rq->resid_len = clone->resid_len;
+
+		if (rq->sense)
+			/*
+			 * We are using the sense buffer of the original
+			 * request.
+			 * So setting the length of the sense data is enough.
+			 */
+			rq->sense_len = clone->sense_len;
+	}
+
+	free_rq_clone(clone);
+	blk_end_request_all(rq, error);
+	rq_completed(md, rw, true);
+}
+
+static void dm_unprep_request(struct request *rq)
+{
+	struct request *clone = rq->special;
+
+	rq->special = NULL;
+	rq->cmd_flags &= ~REQ_DONTPREP;
+
+	free_rq_clone(clone);
+}
+
+/*
+ * Requeue the original request of a clone.
+ */
+void dm_requeue_unmapped_request(struct request *clone)
+{
+	int rw = rq_data_dir(clone);
+	struct dm_rq_target_io *tio = clone->end_io_data;
+	struct mapped_device *md = tio->md;
+	struct request *rq = tio->orig;
+	struct request_queue *q = rq->q;
+	unsigned long flags;
+
+	dm_unprep_request(rq);
+
+	spin_lock_irqsave(q->queue_lock, flags);
+	blk_requeue_request(q, rq);
+	spin_unlock_irqrestore(q->queue_lock, flags);
+
+	rq_completed(md, rw, 0);
+}
+EXPORT_SYMBOL_GPL(dm_requeue_unmapped_request);
+
+static void __stop_queue(struct request_queue *q)
+{
+	blk_stop_queue(q);
+}
+
+static void stop_queue(struct request_queue *q)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(q->queue_lock, flags);
+	__stop_queue(q);
+	spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+static void __start_queue(struct request_queue *q)
+{
+	if (blk_queue_stopped(q))
+		blk_start_queue(q);
+}
+
+static void start_queue(struct request_queue *q)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(q->queue_lock, flags);
+	__start_queue(q);
+	spin_unlock_irqrestore(q->queue_lock, flags);
+}
+
+static void dm_done(struct request *clone, int error, bool mapped)
+{
+	int r = error;
+	struct dm_rq_target_io *tio = clone->end_io_data;
+	dm_request_endio_fn rq_end_io = tio->ti->type->rq_end_io;
+
+	if (mapped && rq_end_io)
+		r = rq_end_io(tio->ti, clone, error, &tio->info);
+
+	if (r <= 0)
+		/* The target wants to complete the I/O */
+		dm_end_request(clone, r);
+	else if (r == DM_ENDIO_INCOMPLETE)
+		/* The target will handle the I/O */
+		return;
+	else if (r == DM_ENDIO_REQUEUE)
+		/* The target wants to requeue the I/O */
+		dm_requeue_unmapped_request(clone);
+	else {
+		DMWARN("unimplemented target endio return value: %d", r);
+		BUG();
+	}
+}
+
+/*
+ * Request completion handler for request-based dm
+ */
+static void dm_softirq_done(struct request *rq)
+{
+	bool mapped = true;
+	struct request *clone = rq->completion_data;
+	struct dm_rq_target_io *tio = clone->end_io_data;
+
+	if (rq->cmd_flags & REQ_FAILED)
+		mapped = false;
+
+	dm_done(clone, tio->error, mapped);
+}
+
+/*
+ * Complete the clone and the original request with the error status
+ * through softirq context.
+ */
+static void dm_complete_request(struct request *clone, int error)
+{
+	struct dm_rq_target_io *tio = clone->end_io_data;
+	struct request *rq = tio->orig;
+
+	tio->error = error;
+	rq->completion_data = clone;
+	blk_complete_request(rq);
+}
+
+/*
+ * Complete the not-mapped clone and the original request with the error status
+ * through softirq context.
+ * Target's rq_end_io() function isn't called.
+ * This may be used when the target's map_rq() function fails.
+ */
+void dm_kill_unmapped_request(struct request *clone, int error)
+{
+	struct dm_rq_target_io *tio = clone->end_io_data;
+	struct request *rq = tio->orig;
+
+	rq->cmd_flags |= REQ_FAILED;
+	dm_complete_request(clone, error);
+}
+EXPORT_SYMBOL_GPL(dm_kill_unmapped_request);
+
+/*
+ * Called with the queue lock held
+ */
+static void end_clone_request(struct request *clone, int error)
+{
+	/*
+	 * For just cleaning up the information of the queue in which
+	 * the clone was dispatched.
+	 * The clone is *NOT* freed actually here because it is alloced from
+	 * dm own mempool and REQ_ALLOCED isn't set in clone->cmd_flags.
+	 */
+	__blk_put_request(clone->q, clone);
+
+	/*
+	 * Actual request completion is done in a softirq context which doesn't
+	 * hold the queue lock.  Otherwise, deadlock could occur because:
+	 *     - another request may be submitted by the upper level driver
+	 *       of the stacking during the completion
+	 *     - the submission which requires queue lock may be done
+	 *       against this queue
+	 */
+	dm_complete_request(clone, error);
+}
+
+/*
+ * Return maximum size of I/O possible at the supplied sector up to the current
+ * target boundary.
+ */
+static sector_t max_io_len_target_boundary(sector_t sector, struct dm_target *ti)
+{
+	sector_t target_offset = dm_target_offset(ti, sector);
+
+	return ti->len - target_offset;
+}
+
+static sector_t max_io_len(sector_t sector, struct dm_target *ti)
+{
+	sector_t len = max_io_len_target_boundary(sector, ti);
+
+	/*
+	 * Does the target need to split even further ?
+	 */
+	if (ti->split_io) {
+		sector_t boundary;
+		sector_t offset = dm_target_offset(ti, sector);
+		boundary = ((offset + ti->split_io) & ~(ti->split_io - 1))
+			   - offset;
+		if (len > boundary)
+			len = boundary;
+	}
+
+	return len;
+}
+
+static void __map_bio(struct dm_target *ti, struct bio *clone,
+		      struct dm_target_io *tio)
+{
+	int r;
+	sector_t sector;
+	struct mapped_device *md;
+
+	clone->bi_end_io = clone_endio;
+	clone->bi_private = tio;
+
+	/*
+	 * Map the clone.  If r == 0 we don't need to do
+	 * anything, the target has assumed ownership of
+	 * this io.
+	 */
+	atomic_inc(&tio->io->io_count);
+	sector = clone->bi_sector;
+	r = ti->type->map(ti, clone, &tio->info);
+	if (r == DM_MAPIO_REMAPPED) {
+		/* the bio has been remapped so dispatch it */
+
+		trace_block_bio_remap(bdev_get_queue(clone->bi_bdev), clone,
+				      tio->io->bio->bi_bdev->bd_dev, sector);
+
+		generic_make_request(clone);
+	} else if (r < 0 || r == DM_MAPIO_REQUEUE) {
+		/* error the io and bail out, or requeue it if needed */
+		md = tio->io->md;
+		dec_pending(tio->io, r);
+		/*
+		 * Store bio_set for cleanup.
+		 */
+		clone->bi_end_io = NULL;
+		clone->bi_private = md->bs;
+		bio_put(clone);
+		free_tio(md, tio);
+	} else if (r) {
+		DMWARN("unimplemented target map return value: %d", r);
+		BUG();
+	}
+}
+
+struct clone_info {
+	struct mapped_device *md;
+	struct dm_table *map;
+	struct bio *bio;
+	struct dm_io *io;
+	sector_t sector;
+	sector_t sector_count;
+	unsigned short idx;
+};
+
+static void dm_bio_destructor(struct bio *bio)
+{
+	struct bio_set *bs = bio->bi_private;
+
+	bio_free(bio, bs);
+}
+
+/*
+ * Creates a little bio that just does part of a bvec.
+ */
+static struct bio *split_bvec(struct bio *bio, sector_t sector,
+			      unsigned short idx, unsigned int offset,
+			      unsigned int len, struct bio_set *bs)
+{
+	struct bio *clone;
+	struct bio_vec *bv = bio->bi_io_vec + idx;
+
+	clone = bio_alloc_bioset(GFP_NOIO, 1, bs);
+	clone->bi_destructor = dm_bio_destructor;
+	*clone->bi_io_vec = *bv;
+
+	clone->bi_sector = sector;
+	clone->bi_bdev = bio->bi_bdev;
+	clone->bi_rw = bio->bi_rw;
+	clone->bi_vcnt = 1;
+	clone->bi_size = to_bytes(len);
+	clone->bi_io_vec->bv_offset = offset;
+	clone->bi_io_vec->bv_len = clone->bi_size;
+	clone->bi_flags |= 1 << BIO_CLONED;
+
+	if (bio_integrity(bio)) {
+		bio_integrity_clone(clone, bio, GFP_NOIO, bs);
+		bio_integrity_trim(clone,
+				   bio_sector_offset(bio, idx, offset), len);
+	}
+
+	return clone;
+}
+
+/*
+ * Creates a bio that consists of range of complete bvecs.
+ */
+static struct bio *clone_bio(struct bio *bio, sector_t sector,
+			     unsigned short idx, unsigned short bv_count,
+			     unsigned int len, struct bio_set *bs)
+{
+	struct bio *clone;
+
+	clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs);
+	__bio_clone(clone, bio);
+	clone->bi_destructor = dm_bio_destructor;
+	clone->bi_sector = sector;
+	clone->bi_idx = idx;
+	clone->bi_vcnt = idx + bv_count;
+	clone->bi_size = to_bytes(len);
+	clone->bi_flags &= ~(1 << BIO_SEG_VALID);
+
+	if (bio_integrity(bio)) {
+		bio_integrity_clone(clone, bio, GFP_NOIO, bs);
+
+		if (idx != bio->bi_idx || clone->bi_size < bio->bi_size)
+			bio_integrity_trim(clone,
+					   bio_sector_offset(bio, idx, 0), len);
+	}
+
+	return clone;
+}
+
+static struct dm_target_io *alloc_tio(struct clone_info *ci,
+				      struct dm_target *ti)
+{
+	struct dm_target_io *tio = mempool_alloc(ci->md->tio_pool, GFP_NOIO);
+
+	tio->io = ci->io;
+	tio->ti = ti;
+	memset(&tio->info, 0, sizeof(tio->info));
+
+	return tio;
+}
+
+static void __issue_target_request(struct clone_info *ci, struct dm_target *ti,
+				   unsigned request_nr, sector_t len)
+{
+	struct dm_target_io *tio = alloc_tio(ci, ti);
+	struct bio *clone;
+
+	tio->info.target_request_nr = request_nr;
+
+	/*
+	 * Discard requests require the bio's inline iovecs be initialized.
+	 * ci->bio->bi_max_vecs is BIO_INLINE_VECS anyway, for both flush
+	 * and discard, so no need for concern about wasted bvec allocations.
+	 */
+	clone = bio_alloc_bioset(GFP_NOIO, ci->bio->bi_max_vecs, ci->md->bs);
+	__bio_clone(clone, ci->bio);
+	clone->bi_destructor = dm_bio_destructor;
+	if (len) {
+		clone->bi_sector = ci->sector;
+		clone->bi_size = to_bytes(len);
+	}
+
+	__map_bio(ti, clone, tio);
+}
+
+static void __issue_target_requests(struct clone_info *ci, struct dm_target *ti,
+				    unsigned num_requests, sector_t len)
+{
+	unsigned request_nr;
+
+	for (request_nr = 0; request_nr < num_requests; request_nr++)
+		__issue_target_request(ci, ti, request_nr, len);
+}
+
+static int __clone_and_map_empty_flush(struct clone_info *ci)
+{
+	unsigned target_nr = 0;
+	struct dm_target *ti;
+
+	BUG_ON(bio_has_data(ci->bio));
+	while ((ti = dm_table_get_target(ci->map, target_nr++)))
+		__issue_target_requests(ci, ti, ti->num_flush_requests, 0);
+
+	return 0;
+}
+
+/*
+ * Perform all io with a single clone.
+ */
+static void __clone_and_map_simple(struct clone_info *ci, struct dm_target *ti)
+{
+	struct bio *clone, *bio = ci->bio;
+	struct dm_target_io *tio;
+
+	tio = alloc_tio(ci, ti);
+	clone = clone_bio(bio, ci->sector, ci->idx,
+			  bio->bi_vcnt - ci->idx, ci->sector_count,
+			  ci->md->bs);
+	__map_bio(ti, clone, tio);
+	ci->sector_count = 0;
+}
+
+static int __clone_and_map_discard(struct clone_info *ci)
+{
+	struct dm_target *ti;
+	sector_t len;
+
+	do {
+		ti = dm_table_find_target(ci->map, ci->sector);
+		if (!dm_target_is_valid(ti))
+			return -EIO;
+
+		/*
+		 * Even though the device advertised discard support,
+		 * that does not mean every target supports it, and
+		 * reconfiguration might also have changed that since the
+		 * check was performed.
+		 */
+		if (!ti->num_discard_requests)
+			return -EOPNOTSUPP;
+
+		len = min(ci->sector_count, max_io_len_target_boundary(ci->sector, ti));
+
+		__issue_target_requests(ci, ti, ti->num_discard_requests, len);
+
+		ci->sector += len;
+	} while (ci->sector_count -= len);
+
+	return 0;
+}
+
+static int __clone_and_map(struct clone_info *ci)
+{
+	struct bio *clone, *bio = ci->bio;
+	struct dm_target *ti;
+	sector_t len = 0, max;
+	struct dm_target_io *tio;
+
+	if (unlikely(bio->bi_rw & REQ_DISCARD))
+		return __clone_and_map_discard(ci);
+
+	ti = dm_table_find_target(ci->map, ci->sector);
+	if (!dm_target_is_valid(ti))
+		return -EIO;
+
+	max = max_io_len(ci->sector, ti);
+
+	if (ci->sector_count <= max) {
+		/*
+		 * Optimise for the simple case where we can do all of
+		 * the remaining io with a single clone.
+		 */
+		__clone_and_map_simple(ci, ti);
+
+	} else if (to_sector(bio->bi_io_vec[ci->idx].bv_len) <= max) {
+		/*
+		 * There are some bvecs that don't span targets.
+		 * Do as many of these as possible.
+		 */
+		int i;
+		sector_t remaining = max;
+		sector_t bv_len;
+
+		for (i = ci->idx; remaining && (i < bio->bi_vcnt); i++) {
+			bv_len = to_sector(bio->bi_io_vec[i].bv_len);
+
+			if (bv_len > remaining)
+				break;
+
+			remaining -= bv_len;
+			len += bv_len;
+		}
+
+		tio = alloc_tio(ci, ti);
+		clone = clone_bio(bio, ci->sector, ci->idx, i - ci->idx, len,
+				  ci->md->bs);
+		__map_bio(ti, clone, tio);
+
+		ci->sector += len;
+		ci->sector_count -= len;
+		ci->idx = i;
+
+	} else {
+		/*
+		 * Handle a bvec that must be split between two or more targets.
+		 */
+		struct bio_vec *bv = bio->bi_io_vec + ci->idx;
+		sector_t remaining = to_sector(bv->bv_len);
+		unsigned int offset = 0;
+
+		do {
+			if (offset) {
+				ti = dm_table_find_target(ci->map, ci->sector);
+				if (!dm_target_is_valid(ti))
+					return -EIO;
+
+				max = max_io_len(ci->sector, ti);
+			}
+
+			len = min(remaining, max);
+
+			tio = alloc_tio(ci, ti);
+			clone = split_bvec(bio, ci->sector, ci->idx,
+					   bv->bv_offset + offset, len,
+					   ci->md->bs);
+
+			__map_bio(ti, clone, tio);
+
+			ci->sector += len;
+			ci->sector_count -= len;
+			offset += to_bytes(len);
+		} while (remaining -= len);
+
+		ci->idx++;
+	}
+
+	return 0;
+}
+
+/*
+ * Split the bio into several clones and submit it to targets.
+ */
+static void __split_and_process_bio(struct mapped_device *md, struct bio *bio)
+{
+	struct clone_info ci;
+	int error = 0;
+
+	ci.map = dm_get_live_table(md);
+	if (unlikely(!ci.map)) {
+		bio_io_error(bio);
+		return;
+	}
+
+	ci.md = md;
+	ci.io = alloc_io(md);
+	ci.io->error = 0;
+	atomic_set(&ci.io->io_count, 1);
+	ci.io->bio = bio;
+	ci.io->md = md;
+	spin_lock_init(&ci.io->endio_lock);
+	ci.sector = bio->bi_sector;
+	ci.idx = bio->bi_idx;
+
+	start_io_acct(ci.io);
+	if (bio->bi_rw & REQ_FLUSH) {
+		ci.bio = &ci.md->flush_bio;
+		ci.sector_count = 0;
+		error = __clone_and_map_empty_flush(&ci);
+		/* dec_pending submits any data associated with flush */
+	} else {
+		ci.bio = bio;
+		ci.sector_count = bio_sectors(bio);
+		while (ci.sector_count && !error)
+			error = __clone_and_map(&ci);
+	}
+
+	/* drop the extra reference count */
+	dec_pending(ci.io, error);
+	dm_table_put(ci.map);
+}
+/*-----------------------------------------------------------------
+ * CRUD END
+ *---------------------------------------------------------------*/
+
+static int dm_merge_bvec(struct request_queue *q,
+			 struct bvec_merge_data *bvm,
+			 struct bio_vec *biovec)
+{
+	struct mapped_device *md = q->queuedata;
+	struct dm_table *map = dm_get_live_table(md);
+	struct dm_target *ti;
+	sector_t max_sectors;
+	int max_size = 0;
+
+	if (unlikely(!map))
+		goto out;
+
+	ti = dm_table_find_target(map, bvm->bi_sector);
+	if (!dm_target_is_valid(ti))
+		goto out_table;
+
+	/*
+	 * Find maximum amount of I/O that won't need splitting
+	 */
+	max_sectors = min(max_io_len(bvm->bi_sector, ti),
+			  (sector_t) BIO_MAX_SECTORS);
+	max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size;
+	if (max_size < 0)
+		max_size = 0;
+
+	/*
+	 * merge_bvec_fn() returns number of bytes
+	 * it can accept at this offset
+	 * max is precomputed maximal io size
+	 */
+	if (max_size && ti->type->merge)
+		max_size = ti->type->merge(ti, bvm, biovec, max_size);
+	/*
+	 * If the target doesn't support merge method and some of the devices
+	 * provided their merge_bvec method (we know this by looking at
+	 * queue_max_hw_sectors), then we can't allow bios with multiple vector
+	 * entries.  So always set max_size to 0, and the code below allows
+	 * just one page.
+	 */
+	else if (queue_max_hw_sectors(q) <= PAGE_SIZE >> 9)
+
+		max_size = 0;
+
+out_table:
+	dm_table_put(map);
+
+out:
+	/*
+	 * Always allow an entire first page
+	 */
+	if (max_size <= biovec->bv_len && !(bvm->bi_size >> SECTOR_SHIFT))
+		max_size = biovec->bv_len;
+
+	return max_size;
+}
+
+/*
+ * The request function that just remaps the bio built up by
+ * dm_merge_bvec.
+ */
+static void _dm_request(struct request_queue *q, struct bio *bio)
+{
+	int rw = bio_data_dir(bio);
+	struct mapped_device *md = q->queuedata;
+	int cpu;
+
+	down_read(&md->io_lock);
+
+	cpu = part_stat_lock();
+	part_stat_inc(cpu, &dm_disk(md)->part0, ios[rw]);
+	part_stat_add(cpu, &dm_disk(md)->part0, sectors[rw], bio_sectors(bio));
+	part_stat_unlock();
+
+	/* if we're suspended, we have to queue this io for later */
+	if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))) {
+		up_read(&md->io_lock);
+
+		if (bio_rw(bio) != READA)
+			queue_io(md, bio);
+		else
+			bio_io_error(bio);
+		return;
+	}
+
+	__split_and_process_bio(md, bio);
+	up_read(&md->io_lock);
+	return;
+}
+
+static int dm_request_based(struct mapped_device *md)
+{
+	return blk_queue_stackable(md->queue);
+}
+
+static void dm_request(struct request_queue *q, struct bio *bio)
+{
+	struct mapped_device *md = q->queuedata;
+
+	if (dm_request_based(md))
+		blk_queue_bio(q, bio);
+	else
+		_dm_request(q, bio);
+}
+
+void dm_dispatch_request(struct request *rq)
+{
+	int r;
+
+	if (blk_queue_io_stat(rq->q))
+		rq->cmd_flags |= REQ_IO_STAT;
+
+	rq->start_time = jiffies;
+	r = blk_insert_cloned_request(rq->q, rq);
+	if (r)
+		dm_complete_request(rq, r);
+}
+EXPORT_SYMBOL_GPL(dm_dispatch_request);
+
+static void dm_rq_bio_destructor(struct bio *bio)
+{
+	struct dm_rq_clone_bio_info *info = bio->bi_private;
+	struct mapped_device *md = info->tio->md;
+
+	free_bio_info(info);
+	bio_free(bio, md->bs);
+}
+
+static int dm_rq_bio_constructor(struct bio *bio, struct bio *bio_orig,
+				 void *data)
+{
+	struct dm_rq_target_io *tio = data;
+	struct mapped_device *md = tio->md;
+	struct dm_rq_clone_bio_info *info = alloc_bio_info(md);
+
+	if (!info)
+		return -ENOMEM;
+
+	info->orig = bio_orig;
+	info->tio = tio;
+	bio->bi_end_io = end_clone_bio;
+	bio->bi_private = info;
+	bio->bi_destructor = dm_rq_bio_destructor;
+
+	return 0;
+}
+
+static int setup_clone(struct request *clone, struct request *rq,
+		       struct dm_rq_target_io *tio)
+{
+	int r;
+
+	r = blk_rq_prep_clone(clone, rq, tio->md->bs, GFP_ATOMIC,
+			      dm_rq_bio_constructor, tio);
+	if (r)
+		return r;
+
+	clone->cmd = rq->cmd;
+	clone->cmd_len = rq->cmd_len;
+	clone->sense = rq->sense;
+	clone->buffer = rq->buffer;
+	clone->end_io = end_clone_request;
+	clone->end_io_data = tio;
+
+	return 0;
+}
+
+static struct request *clone_rq(struct request *rq, struct mapped_device *md,
+				gfp_t gfp_mask)
+{
+	struct request *clone;
+	struct dm_rq_target_io *tio;
+
+	tio = alloc_rq_tio(md, gfp_mask);
+	if (!tio)
+		return NULL;
+
+	tio->md = md;
+	tio->ti = NULL;
+	tio->orig = rq;
+	tio->error = 0;
+	memset(&tio->info, 0, sizeof(tio->info));
+
+	clone = &tio->clone;
+	if (setup_clone(clone, rq, tio)) {
+		/* -ENOMEM */
+		free_rq_tio(tio);
+		return NULL;
+	}
+
+	return clone;
+}
+
+/*
+ * Called with the queue lock held.
+ */
+static int dm_prep_fn(struct request_queue *q, struct request *rq)
+{
+	struct mapped_device *md = q->queuedata;
+	struct request *clone;
+
+	if (unlikely(rq->special)) {
+		DMWARN("Already has something in rq->special.");
+		return BLKPREP_KILL;
+	}
+
+	clone = clone_rq(rq, md, GFP_ATOMIC);
+	if (!clone)
+		return BLKPREP_DEFER;
+
+	rq->special = clone;
+	rq->cmd_flags |= REQ_DONTPREP;
+
+	return BLKPREP_OK;
+}
+
+/*
+ * Returns:
+ * 0  : the request has been processed (not requeued)
+ * !0 : the request has been requeued
+ */
+static int map_request(struct dm_target *ti, struct request *clone,
+		       struct mapped_device *md)
+{
+	int r, requeued = 0;
+	struct dm_rq_target_io *tio = clone->end_io_data;
+
+	/*
+	 * Hold the md reference here for the in-flight I/O.
+	 * We can't rely on the reference count by device opener,
+	 * because the device may be closed during the request completion
+	 * when all bios are completed.
+	 * See the comment in rq_completed() too.
+	 */
+	dm_get(md);
+
+	tio->ti = ti;
+	r = ti->type->map_rq(ti, clone, &tio->info);
+	switch (r) {
+	case DM_MAPIO_SUBMITTED:
+		/* The target has taken the I/O to submit by itself later */
+		break;
+	case DM_MAPIO_REMAPPED:
+		/* The target has remapped the I/O so dispatch it */
+		trace_block_rq_remap(clone->q, clone, disk_devt(dm_disk(md)),
+				     blk_rq_pos(tio->orig));
+		dm_dispatch_request(clone);
+		break;
+	case DM_MAPIO_REQUEUE:
+		/* The target wants to requeue the I/O */
+		dm_requeue_unmapped_request(clone);
+		requeued = 1;
+		break;
+	default:
+		if (r > 0) {
+			DMWARN("unimplemented target map return value: %d", r);
+			BUG();
+		}
+
+		/* The target wants to complete the I/O */
+		dm_kill_unmapped_request(clone, r);
+		break;
+	}
+
+	return requeued;
+}
+
+/*
+ * q->request_fn for request-based dm.
+ * Called with the queue lock held.
+ */
+static void dm_request_fn(struct request_queue *q)
+{
+	struct mapped_device *md = q->queuedata;
+	struct dm_table *map = dm_get_live_table(md);
+	struct dm_target *ti;
+	struct request *rq, *clone;
+	sector_t pos;
+
+	/*
+	 * For suspend, check blk_queue_stopped() and increment
+	 * ->pending within a single queue_lock not to increment the
+	 * number of in-flight I/Os after the queue is stopped in
+	 * dm_suspend().
+	 */
+	while (!blk_queue_stopped(q)) {
+		rq = blk_peek_request(q);
+		if (!rq)
+			goto delay_and_out;
+
+		/* always use block 0 to find the target for flushes for now */
+		pos = 0;
+		if (!(rq->cmd_flags & REQ_FLUSH))
+			pos = blk_rq_pos(rq);
+
+		ti = dm_table_find_target(map, pos);
+		BUG_ON(!dm_target_is_valid(ti));
+
+		if (ti->type->busy && ti->type->busy(ti))
+			goto delay_and_out;
+
+		blk_start_request(rq);
+		clone = rq->special;
+		atomic_inc(&md->pending[rq_data_dir(clone)]);
+
+		spin_unlock(q->queue_lock);
+		if (map_request(ti, clone, md))
+			goto requeued;
+
+		BUG_ON(!irqs_disabled());
+		spin_lock(q->queue_lock);
+	}
+
+	goto out;
+
+requeued:
+	BUG_ON(!irqs_disabled());
+	spin_lock(q->queue_lock);
+
+delay_and_out:
+	blk_delay_queue(q, HZ / 10);
+out:
+	dm_table_put(map);
+
+	return;
+}
+
+int dm_underlying_device_busy(struct request_queue *q)
+{
+	return blk_lld_busy(q);
+}
+EXPORT_SYMBOL_GPL(dm_underlying_device_busy);
+
+static int dm_lld_busy(struct request_queue *q)
+{
+	int r;
+	struct mapped_device *md = q->queuedata;
+	struct dm_table *map = dm_get_live_table(md);
+
+	if (!map || test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags))
+		r = 1;
+	else
+		r = dm_table_any_busy_target(map);
+
+	dm_table_put(map);
+
+	return r;
+}
+
+static int dm_any_congested(void *congested_data, int bdi_bits)
+{
+	int r = bdi_bits;
+	struct mapped_device *md = congested_data;
+	struct dm_table *map;
+
+	if (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
+		map = dm_get_live_table(md);
+		if (map) {
+			/*
+			 * Request-based dm cares about only own queue for
+			 * the query about congestion status of request_queue
+			 */
+			if (dm_request_based(md))
+				r = md->queue->backing_dev_info.state &
+				    bdi_bits;
+			else
+				r = dm_table_any_congested(map, bdi_bits);
+
+			dm_table_put(map);
+		}
+	}
+
+	return r;
+}
+
+/*-----------------------------------------------------------------
+ * 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, m;
+
+	if (minor >= (1 << MINORBITS))
+		return -EINVAL;
+
+	r = idr_pre_get(&_minor_idr, GFP_KERNEL);
+	if (!r)
+		return -ENOMEM;
+
+	spin_lock(&_minor_lock);
+
+	if (idr_find(&_minor_idr, minor)) {
+		r = -EBUSY;
+		goto out;
+	}
+
+	r = idr_get_new_above(&_minor_idr, MINOR_ALLOCED, minor, &m);
+	if (r)
+		goto out;
+
+	if (m != minor) {
+		idr_remove(&_minor_idr, m);
+		r = -EBUSY;
+		goto out;
+	}
+
+out:
+	spin_unlock(&_minor_lock);
+	return r;
+}
+
+static int next_free_minor(int *minor)
+{
+	int r, m;
+
+	r = idr_pre_get(&_minor_idr, GFP_KERNEL);
+	if (!r)
+		return -ENOMEM;
+
+	spin_lock(&_minor_lock);
+
+	r = idr_get_new(&_minor_idr, MINOR_ALLOCED, &m);
+	if (r)
+		goto out;
+
+	if (m >= (1 << MINORBITS)) {
+		idr_remove(&_minor_idr, m);
+		r = -ENOSPC;
+		goto out;
+	}
+
+	*minor = m;
+
+out:
+	spin_unlock(&_minor_lock);
+	return r;
+}
+
+static const struct block_device_operations dm_blk_dops;
+
+static void dm_wq_work(struct work_struct *work);
+
+static void dm_init_md_queue(struct mapped_device *md)
+{
+	/*
+	 * Request-based dm devices cannot be stacked on top of bio-based dm
+	 * devices.  The type of this dm device has not been decided yet.
+	 * The type is decided at the first table loading time.
+	 * To prevent problematic device stacking, clear the queue flag
+	 * for request stacking support until then.
+	 *
+	 * This queue is new, so no concurrency on the queue_flags.
+	 */
+	queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue);
+
+	md->queue->queuedata = md;
+	md->queue->backing_dev_info.congested_fn = dm_any_congested;
+	md->queue->backing_dev_info.congested_data = md;
+	blk_queue_make_request(md->queue, dm_request);
+	blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
+	blk_queue_merge_bvec(md->queue, dm_merge_bvec);
+}
+
+/*
+ * Allocate and initialise a blank device with a given minor.
+ */
+static struct mapped_device *alloc_dev(int minor)
+{
+	int r;
+	struct mapped_device *md = kzalloc(sizeof(*md), GFP_KERNEL);
+	void *old_md;
+
+	if (!md) {
+		DMWARN("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;
+
+	md->type = DM_TYPE_NONE;
+	init_rwsem(&md->io_lock);
+	mutex_init(&md->suspend_lock);
+	mutex_init(&md->type_lock);
+	spin_lock_init(&md->deferred_lock);
+	rwlock_init(&md->map_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);
+	spin_lock_init(&md->uevent_lock);
+
+	md->queue = blk_alloc_queue(GFP_KERNEL);
+	if (!md->queue)
+		goto bad_queue;
+
+	dm_init_md_queue(md);
+
+	md->disk = alloc_disk(1);
+	if (!md->disk)
+		goto bad_disk;
+
+	atomic_set(&md->pending[0], 0);
+	atomic_set(&md->pending[1], 0);
+	init_waitqueue_head(&md->wait);
+	INIT_WORK(&md->work, dm_wq_work);
+	init_waitqueue_head(&md->eventq);
+
+	md->disk->major = _major;
+	md->disk->first_minor = minor;
+	md->disk->fops = &dm_blk_dops;
+	md->disk->queue = md->queue;
+	md->disk->private_data = md;
+	sprintf(md->disk->disk_name, "dm-%d", minor);
+	add_disk(md->disk);
+	format_dev_t(md->name, MKDEV(_major, minor));
+
+	md->wq = alloc_workqueue("kdmflush",
+				 WQ_NON_REENTRANT | WQ_MEM_RECLAIM, 0);
+	if (!md->wq)
+		goto bad_thread;
+
+	md->bdev = bdget_disk(md->disk, 0);
+	if (!md->bdev)
+		goto bad_bdev;
+
+	bio_init(&md->flush_bio);
+	md->flush_bio.bi_bdev = md->bdev;
+	md->flush_bio.bi_rw = WRITE_FLUSH;
+
+	/* 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_bdev:
+	destroy_workqueue(md->wq);
+bad_thread:
+	del_gendisk(md->disk);
+	put_disk(md->disk);
+bad_disk:
+	blk_cleanup_queue(md->queue);
+bad_queue:
+	free_minor(minor);
+bad_minor:
+	module_put(THIS_MODULE);
+bad_module_get:
+	kfree(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);
+	bdput(md->bdev);
+	destroy_workqueue(md->wq);
+	if (md->tio_pool)
+		mempool_destroy(md->tio_pool);
+	if (md->io_pool)
+		mempool_destroy(md->io_pool);
+	if (md->bs)
+		bioset_free(md->bs);
+	blk_integrity_unregister(md->disk);
+	del_gendisk(md->disk);
+	free_minor(minor);
+
+	spin_lock(&_minor_lock);
+	md->disk->private_data = NULL;
+	spin_unlock(&_minor_lock);
+
+	put_disk(md->disk);
+	blk_cleanup_queue(md->queue);
+	module_put(THIS_MODULE);
+	kfree(md);
+}
+
+static void __bind_mempools(struct mapped_device *md, struct dm_table *t)
+{
+	struct dm_md_mempools *p;
+
+	if (md->io_pool && md->tio_pool && md->bs)
+		/* the md already has necessary mempools */
+		goto out;
+
+	p = dm_table_get_md_mempools(t);
+	BUG_ON(!p || md->io_pool || md->tio_pool || md->bs);
+
+	md->io_pool = p->io_pool;
+	p->io_pool = NULL;
+	md->tio_pool = p->tio_pool;
+	p->tio_pool = NULL;
+	md->bs = p->bs;
+	p->bs = NULL;
+
+out:
+	/* mempool bind completed, now no need any mempools in the table */
+	dm_table_free_md_mempools(t);
+}
+
+/*
+ * 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);
+}
+
+/*
+ * Protected by md->suspend_lock obtained by dm_swap_table().
+ */
+static void __set_size(struct mapped_device *md, sector_t size)
+{
+	set_capacity(md->disk, size);
+
+	i_size_write(md->bdev->bd_inode, (loff_t)size << SECTOR_SHIFT);
+}
+
+/*
+ * Return 1 if the queue has a compulsory merge_bvec_fn function.
+ *
+ * If this function returns 0, then the device is either a non-dm
+ * device without a merge_bvec_fn, or it is a dm device that is
+ * able to split any bios it receives that are too big.
+ */
+int dm_queue_merge_is_compulsory(struct request_queue *q)
+{
+	struct mapped_device *dev_md;
+
+	if (!q->merge_bvec_fn)
+		return 0;
+
+	if (q->make_request_fn == dm_request) {
+		dev_md = q->queuedata;
+		if (test_bit(DMF_MERGE_IS_OPTIONAL, &dev_md->flags))
+			return 0;
+	}
+
+	return 1;
+}
+
+static int dm_device_merge_is_compulsory(struct dm_target *ti,
+					 struct dm_dev *dev, sector_t start,
+					 sector_t len, void *data)
+{
+	struct block_device *bdev = dev->bdev;
+	struct request_queue *q = bdev_get_queue(bdev);
+
+	return dm_queue_merge_is_compulsory(q);
+}
+
+/*
+ * Return 1 if it is acceptable to ignore merge_bvec_fn based
+ * on the properties of the underlying devices.
+ */
+static int dm_table_merge_is_optional(struct dm_table *table)
+{
+	unsigned i = 0;
+	struct dm_target *ti;
+
+	while (i < dm_table_get_num_targets(table)) {
+		ti = dm_table_get_target(table, i++);
+
+		if (ti->type->iterate_devices &&
+		    ti->type->iterate_devices(ti, dm_device_merge_is_compulsory, NULL))
+			return 0;
+	}
+
+	return 1;
+}
+
+/*
+ * 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;
+	struct request_queue *q = md->queue;
+	sector_t size;
+	unsigned long flags;
+	int merge_is_optional;
+
+	size = dm_table_get_size(t);
+
+	/*
+	 * Wipe any geometry if the size of the table changed.
+	 */
+	if (size != get_capacity(md->disk))
+		memset(&md->geometry, 0, sizeof(md->geometry));
+
+	__set_size(md, size);
+
+	dm_table_event_callback(t, event_callback, md);
+
+	/*
+	 * The queue hasn't been stopped yet, if the old table type wasn't
+	 * for request-based during suspension.  So stop it to prevent
+	 * I/O mapping before resume.
+	 * This must be done before setting the queue restrictions,
+	 * because request-based dm may be run just after the setting.
+	 */
+	if (dm_table_request_based(t) && !blk_queue_stopped(q))
+		stop_queue(q);
+
+	__bind_mempools(md, t);
+
+	merge_is_optional = dm_table_merge_is_optional(t);
+
+	write_lock_irqsave(&md->map_lock, flags);
+	old_map = md->map;
+	md->map = t;
+	md->immutable_target_type = dm_table_get_immutable_target_type(t);
+
+	dm_table_set_restrictions(t, q, limits);
+	if (merge_is_optional)
+		set_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
+	else
+		clear_bit(DMF_MERGE_IS_OPTIONAL, &md->flags);
+	write_unlock_irqrestore(&md->map_lock, flags);
+
+	return old_map;
+}
+
+/*
+ * Returns unbound table for the caller to free.
+ */
+static struct dm_table *__unbind(struct mapped_device *md)
+{
+	struct dm_table *map = md->map;
+	unsigned long flags;
+
+	if (!map)
+		return NULL;
+
+	dm_table_event_callback(map, NULL, NULL);
+	write_lock_irqsave(&md->map_lock, flags);
+	md->map = NULL;
+	write_unlock_irqrestore(&md->map_lock, flags);
+
+	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_sysfs_init(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, unsigned type)
+{
+	md->type = type;
+}
+
+unsigned 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;
+}
+
+/*
+ * Fully initialize a request-based queue (->elevator, ->request_fn, etc).
+ */
+static int dm_init_request_based_queue(struct mapped_device *md)
+{
+	struct request_queue *q = NULL;
+
+	if (md->queue->elevator)
+		return 1;
+
+	/* Fully initialize the queue */
+	q = blk_init_allocated_queue(md->queue, dm_request_fn, NULL);
+	if (!q)
+		return 0;
+
+	md->queue = q;
+	dm_init_md_queue(md);
+	blk_queue_softirq_done(md->queue, dm_softirq_done);
+	blk_queue_prep_rq(md->queue, dm_prep_fn);
+	blk_queue_lld_busy(md->queue, dm_lld_busy);
+
+	elv_register_queue(md->queue);
+
+	return 1;
+}
+
+/*
+ * Setup the DM device's queue based on md's type
+ */
+int dm_setup_md_queue(struct mapped_device *md)
+{
+	if ((dm_get_md_type(md) == DM_TYPE_REQUEST_BASED) &&
+	    !dm_init_request_based_queue(md)) {
+		DMWARN("Cannot initialize queue for request-based mapped device");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static struct mapped_device *dm_find_md(dev_t dev)
+{
+	struct mapped_device *md;
+	unsigned 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) ||
+		   dm_deleting_md(md) ||
+		   test_bit(DMF_FREEING, &md->flags))) {
+		md = NULL;
+		goto out;
+	}
+
+out:
+	spin_unlock(&_minor_lock);
+
+	return md;
+}
+
+struct mapped_device *dm_get_md(dev_t dev)
+{
+	struct mapped_device *md = dm_find_md(dev);
+
+	if (md)
+		dm_get(md);
+
+	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));
+}
+
+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;
+
+	might_sleep();
+
+	spin_lock(&_minor_lock);
+	map = dm_get_live_table(md);
+	idr_replace(&_minor_idr, MINOR_ALLOCED, MINOR(disk_devt(dm_disk(md))));
+	set_bit(DMF_FREEING, &md->flags);
+	spin_unlock(&_minor_lock);
+
+	if (!dm_suspended_md(md)) {
+		dm_table_presuspend_targets(map);
+		dm_table_postsuspend_targets(map);
+	}
+
+	/*
+	 * 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_sysfs_exit(md);
+	dm_table_put(map);
+	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 int dm_wait_for_completion(struct mapped_device *md, int interruptible)
+{
+	int r = 0;
+	DECLARE_WAITQUEUE(wait, current);
+
+	add_wait_queue(&md->wait, &wait);
+
+	while (1) {
+		set_current_state(interruptible);
+
+		if (!md_in_flight(md))
+			break;
+
+		if (interruptible == TASK_INTERRUPTIBLE &&
+		    signal_pending(current)) {
+			r = -EINTR;
+			break;
+		}
+
+		io_schedule();
+	}
+	set_current_state(TASK_RUNNING);
+
+	remove_wait_queue(&md->wait, &wait);
+
+	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 *c;
+
+	down_read(&md->io_lock);
+
+	while (!test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)) {
+		spin_lock_irq(&md->deferred_lock);
+		c = bio_list_pop(&md->deferred);
+		spin_unlock_irq(&md->deferred_lock);
+
+		if (!c)
+			break;
+
+		up_read(&md->io_lock);
+
+		if (dm_request_based(md))
+			generic_make_request(c);
+		else
+			__split_and_process_bio(md, c);
+
+		down_read(&md->io_lock);
+	}
+
+	up_read(&md->io_lock);
+}
+
+static void dm_queue_flush(struct mapped_device *md)
+{
+	clear_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
+	smp_mb__after_clear_bit();
+	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 *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;
+
+	r = dm_calculate_queue_limits(table, &limits);
+	if (r) {
+		map = ERR_PTR(r);
+		goto out;
+	}
+
+	map = __bind(md, table, &limits);
+
+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(md->frozen_sb);
+
+	md->frozen_sb = freeze_bdev(md->bdev);
+	if (IS_ERR(md->frozen_sb)) {
+		r = PTR_ERR(md->frozen_sb);
+		md->frozen_sb = NULL;
+		return r;
+	}
+
+	set_bit(DMF_FROZEN, &md->flags);
+
+	return 0;
+}
+
+static void unlock_fs(struct mapped_device *md)
+{
+	if (!test_bit(DMF_FROZEN, &md->flags))
+		return;
+
+	thaw_bdev(md->bdev, md->frozen_sb);
+	md->frozen_sb = NULL;
+	clear_bit(DMF_FROZEN, &md->flags);
+}
+
+/*
+ * 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 suspend_flags)
+{
+	struct dm_table *map = NULL;
+	int r = 0;
+	int do_lockfs = suspend_flags & DM_SUSPEND_LOCKFS_FLAG ? 1 : 0;
+	int noflush = suspend_flags & DM_SUSPEND_NOFLUSH_FLAG ? 1 : 0;
+
+	mutex_lock(&md->suspend_lock);
+
+	if (dm_suspended_md(md)) {
+		r = -EINVAL;
+		goto out_unlock;
+	}
+
+	map = dm_get_live_table(md);
+
+	/*
+	 * 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);
+
+	/* This does not get reverted if there's an error later. */
+	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)
+			goto out;
+	}
+
+	/*
+	 * Here we must make sure that no processes are submitting requests
+	 * to target drivers i.e. no one may be executing
+	 * __split_and_process_bio. This is called from dm_request and
+	 * dm_wq_work.
+	 *
+	 * To get all processes out of __split_and_process_bio in dm_request,
+	 * we take the write lock. To prevent any process from reentering
+	 * __split_and_process_bio from dm_request and quiesce the thread
+	 * (dm_wq_work), we set BMF_BLOCK_IO_FOR_SUSPEND and call
+	 * flush_workqueue(md->wq).
+	 */
+	down_write(&md->io_lock);
+	set_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags);
+	up_write(&md->io_lock);
+
+	/*
+	 * 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))
+		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_INTERRUPTIBLE);
+
+	down_write(&md->io_lock);
+	if (noflush)
+		clear_bit(DMF_NOFLUSH_SUSPENDING, &md->flags);
+	up_write(&md->io_lock);
+
+	/* were we interrupted ? */
+	if (r < 0) {
+		dm_queue_flush(md);
+
+		if (dm_request_based(md))
+			start_queue(md->queue);
+
+		unlock_fs(md);
+		goto out; /* pushback list is already flushed, so skip flush */
+	}
+
+	/*
+	 * If dm_wait_for_completion returned 0, the device is completely
+	 * quiescent now. There is no request-processing activity. All new
+	 * requests are being added to md->deferred list.
+	 */
+
+	set_bit(DMF_SUSPENDED, &md->flags);
+
+	dm_table_postsuspend_targets(map);
+
+out:
+	dm_table_put(map);
+
+out_unlock:
+	mutex_unlock(&md->suspend_lock);
+	return r;
+}
+
+int dm_resume(struct mapped_device *md)
+{
+	int r = -EINVAL;
+	struct dm_table *map = NULL;
+
+	mutex_lock(&md->suspend_lock);
+	if (!dm_suspended_md(md))
+		goto out;
+
+	map = dm_get_live_table(md);
+	if (!map || !dm_table_get_size(map))
+		goto out;
+
+	r = dm_table_resume_targets(map);
+	if (r)
+		goto out;
+
+	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))
+		start_queue(md->queue);
+
+	unlock_fs(md);
+
+	clear_bit(DMF_SUSPENDED, &md->flags);
+
+	r = 0;
+out:
+	dm_table_put(map);
+	mutex_unlock(&md->suspend_lock);
+
+	return r;
+}
+
+/*-----------------------------------------------------------------
+ * Event notification.
+ *---------------------------------------------------------------*/
+int dm_kobject_uevent(struct mapped_device *md, enum kobject_action action,
+		       unsigned cookie)
+{
+	char udev_cookie[DM_COOKIE_LENGTH];
+	char *envp[] = { udev_cookie, NULL };
+
+	if (!cookie)
+		return kobject_uevent(&disk_to_dev(md->disk)->kobj, action);
+	else {
+		snprintf(udev_cookie, DM_COOKIE_LENGTH, "%s=%u",
+			 DM_COOKIE_ENV_VAR_NAME, cookie);
+		return kobject_uevent_env(&disk_to_dev(md->disk)->kobj,
+					  action, envp);
+	}
+}
+
+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;
+}
+
+struct kobject *dm_kobject(struct mapped_device *md)
+{
+	return &md->kobj;
+}
+
+/*
+ * struct mapped_device should not be exported outside of dm.c
+ * so use this check to verify that kobj is part of md structure
+ */
+struct mapped_device *dm_get_from_kobject(struct kobject *kobj)
+{
+	struct mapped_device *md;
+
+	md = container_of(kobj, struct mapped_device, kobj);
+	if (&md->kobj != kobj)
+		return NULL;
+
+	if (test_bit(DMF_FREEING, &md->flags) ||
+	    dm_deleting_md(md))
+		return NULL;
+
+	dm_get(md);
+	return md;
+}
+
+int dm_suspended_md(struct mapped_device *md)
+{
+	return test_bit(DMF_SUSPENDED, &md->flags);
+}
+
+int dm_suspended(struct dm_target *ti)
+{
+	return dm_suspended_md(dm_table_get_md(ti->table));
+}
+EXPORT_SYMBOL_GPL(dm_suspended);
+
+int dm_noflush_suspending(struct dm_target *ti)
+{
+	return __noflush_suspending(dm_table_get_md(ti->table));
+}
+EXPORT_SYMBOL_GPL(dm_noflush_suspending);
+
+struct dm_md_mempools *dm_alloc_md_mempools(unsigned type, unsigned integrity)
+{
+	struct dm_md_mempools *pools = kmalloc(sizeof(*pools), GFP_KERNEL);
+	unsigned int pool_size = (type == DM_TYPE_BIO_BASED) ? 16 : MIN_IOS;
+
+	if (!pools)
+		return NULL;
+
+	pools->io_pool = (type == DM_TYPE_BIO_BASED) ?
+			 mempool_create_slab_pool(MIN_IOS, _io_cache) :
+			 mempool_create_slab_pool(MIN_IOS, _rq_bio_info_cache);
+	if (!pools->io_pool)
+		goto free_pools_and_out;
+
+	pools->tio_pool = (type == DM_TYPE_BIO_BASED) ?
+			  mempool_create_slab_pool(MIN_IOS, _tio_cache) :
+			  mempool_create_slab_pool(MIN_IOS, _rq_tio_cache);
+	if (!pools->tio_pool)
+		goto free_io_pool_and_out;
+
+	pools->bs = bioset_create(pool_size, 0);
+	if (!pools->bs)
+		goto free_tio_pool_and_out;
+
+	if (integrity && bioset_integrity_create(pools->bs, pool_size))
+		goto free_bioset_and_out;
+
+	return pools;
+
+free_bioset_and_out:
+	bioset_free(pools->bs);
+
+free_tio_pool_and_out:
+	mempool_destroy(pools->tio_pool);
+
+free_io_pool_and_out:
+	mempool_destroy(pools->io_pool);
+
+free_pools_and_out:
+	kfree(pools);
+
+	return NULL;
+}
+
+void dm_free_md_mempools(struct dm_md_mempools *pools)
+{
+	if (!pools)
+		return;
+
+	if (pools->io_pool)
+		mempool_destroy(pools->io_pool);
+
+	if (pools->tio_pool)
+		mempool_destroy(pools->tio_pool);
+
+	if (pools->bs)
+		bioset_free(pools->bs);
+
+	kfree(pools);
+}
+
+static const struct block_device_operations dm_blk_dops = {
+	.open = dm_blk_open,
+	.release = dm_blk_close,
+	.ioctl = dm_blk_ioctl,
+	.getgeo = dm_blk_getgeo,
+	.owner = THIS_MODULE
+};
+
+EXPORT_SYMBOL(dm_get_mapinfo);
+
+/*
+ * 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_DESCRIPTION(DM_NAME " driver");
+MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
+MODULE_LICENSE("GPL");