Merge tag 'dm-3.7-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm

Pull device-mapper changes from Alasdair G Kergon:
 "Remove the power-of-2 block size constraint on discards in dm thin
  provisioning and factor the bio_prison code out into a separate module
  (for sharing with the forthcoming cache target).

  Use struct bio's front_pad to eliminate the use of one separate
  mempool by bio-based devices.

  A few other tiny clean-ups."

* tag 'dm-3.7-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/agk/linux-dm:
  dm: store dm_target_io in bio front_pad
  dm thin: move bio_prison code to separate module
  dm thin: prepare to separate bio_prison code
  dm thin: support discard with non power of two block size
  dm persistent data: convert to use le32_add_cpu
  dm: use ACCESS_ONCE for sysfs values
  dm bufio: use list_move
  dm mpath: fix check for null mpio in end_io fn

10 files changed, 636 insertions, 511 deletions

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index d949b781f6f..91a02eeeb31 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -216,6 +216,13 @@ config DM_BUFIO
 	 as a cache, holding recently-read blocks in memory and performing
 	 delayed writes.
 
+config DM_BIO_PRISON
+       tristate
+       depends on BLK_DEV_DM && EXPERIMENTAL
+       ---help---
+	 Some bio locking schemes used by other device-mapper targets
+	 including thin provisioning.
+
 source "drivers/md/persistent-data/Kconfig"
 
 config DM_CRYPT
@@ -247,6 +254,7 @@ config DM_THIN_PROVISIONING
        tristate "Thin provisioning target (EXPERIMENTAL)"
        depends on BLK_DEV_DM && EXPERIMENTAL
        select DM_PERSISTENT_DATA
+       select DM_BIO_PRISON
        ---help---
          Provides thin provisioning and snapshots that share a data store.
 
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index 8b2e0dffe82..94dce8b4932 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_MD_FAULTY)		+= faulty.o
 obj-$(CONFIG_BLK_DEV_MD)	+= md-mod.o
 obj-$(CONFIG_BLK_DEV_DM)	+= dm-mod.o
 obj-$(CONFIG_DM_BUFIO)		+= dm-bufio.o
+obj-$(CONFIG_DM_BIO_PRISON)	+= dm-bio-prison.o
 obj-$(CONFIG_DM_CRYPT)		+= dm-crypt.o
 obj-$(CONFIG_DM_DELAY)		+= dm-delay.o
 obj-$(CONFIG_DM_FLAKEY)		+= dm-flakey.o
diff --git a/drivers/md/dm-bio-prison.c b/drivers/md/dm-bio-prison.c
new file mode 100644
index 00000000000..e4e84156745
--- /dev/null
+++ b/drivers/md/dm-bio-prison.c
@@ -0,0 +1,415 @@
+/*
+ * Copyright (C) 2012 Red Hat, Inc.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm.h"
+#include "dm-bio-prison.h"
+
+#include <linux/spinlock.h>
+#include <linux/mempool.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+/*----------------------------------------------------------------*/
+
+struct dm_bio_prison_cell {
+	struct hlist_node list;
+	struct dm_bio_prison *prison;
+	struct dm_cell_key key;
+	struct bio *holder;
+	struct bio_list bios;
+};
+
+struct dm_bio_prison {
+	spinlock_t lock;
+	mempool_t *cell_pool;
+
+	unsigned nr_buckets;
+	unsigned hash_mask;
+	struct hlist_head *cells;
+};
+
+/*----------------------------------------------------------------*/
+
+static uint32_t calc_nr_buckets(unsigned nr_cells)
+{
+	uint32_t n = 128;
+
+	nr_cells /= 4;
+	nr_cells = min(nr_cells, 8192u);
+
+	while (n < nr_cells)
+		n <<= 1;
+
+	return n;
+}
+
+static struct kmem_cache *_cell_cache;
+
+/*
+ * @nr_cells should be the number of cells you want in use _concurrently_.
+ * Don't confuse it with the number of distinct keys.
+ */
+struct dm_bio_prison *dm_bio_prison_create(unsigned nr_cells)
+{
+	unsigned i;
+	uint32_t nr_buckets = calc_nr_buckets(nr_cells);
+	size_t len = sizeof(struct dm_bio_prison) +
+		(sizeof(struct hlist_head) * nr_buckets);
+	struct dm_bio_prison *prison = kmalloc(len, GFP_KERNEL);
+
+	if (!prison)
+		return NULL;
+
+	spin_lock_init(&prison->lock);
+	prison->cell_pool = mempool_create_slab_pool(nr_cells, _cell_cache);
+	if (!prison->cell_pool) {
+		kfree(prison);
+		return NULL;
+	}
+
+	prison->nr_buckets = nr_buckets;
+	prison->hash_mask = nr_buckets - 1;
+	prison->cells = (struct hlist_head *) (prison + 1);
+	for (i = 0; i < nr_buckets; i++)
+		INIT_HLIST_HEAD(prison->cells + i);
+
+	return prison;
+}
+EXPORT_SYMBOL_GPL(dm_bio_prison_create);
+
+void dm_bio_prison_destroy(struct dm_bio_prison *prison)
+{
+	mempool_destroy(prison->cell_pool);
+	kfree(prison);
+}
+EXPORT_SYMBOL_GPL(dm_bio_prison_destroy);
+
+static uint32_t hash_key(struct dm_bio_prison *prison, struct dm_cell_key *key)
+{
+	const unsigned long BIG_PRIME = 4294967291UL;
+	uint64_t hash = key->block * BIG_PRIME;
+
+	return (uint32_t) (hash & prison->hash_mask);
+}
+
+static int keys_equal(struct dm_cell_key *lhs, struct dm_cell_key *rhs)
+{
+	       return (lhs->virtual == rhs->virtual) &&
+		       (lhs->dev == rhs->dev) &&
+		       (lhs->block == rhs->block);
+}
+
+static struct dm_bio_prison_cell *__search_bucket(struct hlist_head *bucket,
+						  struct dm_cell_key *key)
+{
+	struct dm_bio_prison_cell *cell;
+	struct hlist_node *tmp;
+
+	hlist_for_each_entry(cell, tmp, bucket, list)
+		if (keys_equal(&cell->key, key))
+			return cell;
+
+	return NULL;
+}
+
+/*
+ * This may block if a new cell needs allocating.  You must ensure that
+ * cells will be unlocked even if the calling thread is blocked.
+ *
+ * Returns 1 if the cell was already held, 0 if @inmate is the new holder.
+ */
+int dm_bio_detain(struct dm_bio_prison *prison, struct dm_cell_key *key,
+		  struct bio *inmate, struct dm_bio_prison_cell **ref)
+{
+	int r = 1;
+	unsigned long flags;
+	uint32_t hash = hash_key(prison, key);
+	struct dm_bio_prison_cell *cell, *cell2;
+
+	BUG_ON(hash > prison->nr_buckets);
+
+	spin_lock_irqsave(&prison->lock, flags);
+
+	cell = __search_bucket(prison->cells + hash, key);
+	if (cell) {
+		bio_list_add(&cell->bios, inmate);
+		goto out;
+	}
+
+	/*
+	 * Allocate a new cell
+	 */
+	spin_unlock_irqrestore(&prison->lock, flags);
+	cell2 = mempool_alloc(prison->cell_pool, GFP_NOIO);
+	spin_lock_irqsave(&prison->lock, flags);
+
+	/*
+	 * We've been unlocked, so we have to double check that
+	 * nobody else has inserted this cell in the meantime.
+	 */
+	cell = __search_bucket(prison->cells + hash, key);
+	if (cell) {
+		mempool_free(cell2, prison->cell_pool);
+		bio_list_add(&cell->bios, inmate);
+		goto out;
+	}
+
+	/*
+	 * Use new cell.
+	 */
+	cell = cell2;
+
+	cell->prison = prison;
+	memcpy(&cell->key, key, sizeof(cell->key));
+	cell->holder = inmate;
+	bio_list_init(&cell->bios);
+	hlist_add_head(&cell->list, prison->cells + hash);
+
+	r = 0;
+
+out:
+	spin_unlock_irqrestore(&prison->lock, flags);
+
+	*ref = cell;
+
+	return r;
+}
+EXPORT_SYMBOL_GPL(dm_bio_detain);
+
+/*
+ * @inmates must have been initialised prior to this call
+ */
+static void __cell_release(struct dm_bio_prison_cell *cell, struct bio_list *inmates)
+{
+	struct dm_bio_prison *prison = cell->prison;
+
+	hlist_del(&cell->list);
+
+	if (inmates) {
+		bio_list_add(inmates, cell->holder);
+		bio_list_merge(inmates, &cell->bios);
+	}
+
+	mempool_free(cell, prison->cell_pool);
+}
+
+void dm_cell_release(struct dm_bio_prison_cell *cell, struct bio_list *bios)
+{
+	unsigned long flags;
+	struct dm_bio_prison *prison = cell->prison;
+
+	spin_lock_irqsave(&prison->lock, flags);
+	__cell_release(cell, bios);
+	spin_unlock_irqrestore(&prison->lock, flags);
+}
+EXPORT_SYMBOL_GPL(dm_cell_release);
+
+/*
+ * There are a couple of places where we put a bio into a cell briefly
+ * before taking it out again.  In these situations we know that no other
+ * bio may be in the cell.  This function releases the cell, and also does
+ * a sanity check.
+ */
+static void __cell_release_singleton(struct dm_bio_prison_cell *cell, struct bio *bio)
+{
+	BUG_ON(cell->holder != bio);
+	BUG_ON(!bio_list_empty(&cell->bios));
+
+	__cell_release(cell, NULL);
+}
+
+void dm_cell_release_singleton(struct dm_bio_prison_cell *cell, struct bio *bio)
+{
+	unsigned long flags;
+	struct dm_bio_prison *prison = cell->prison;
+
+	spin_lock_irqsave(&prison->lock, flags);
+	__cell_release_singleton(cell, bio);
+	spin_unlock_irqrestore(&prison->lock, flags);
+}
+EXPORT_SYMBOL_GPL(dm_cell_release_singleton);
+
+/*
+ * Sometimes we don't want the holder, just the additional bios.
+ */
+static void __cell_release_no_holder(struct dm_bio_prison_cell *cell, struct bio_list *inmates)
+{
+	struct dm_bio_prison *prison = cell->prison;
+
+	hlist_del(&cell->list);
+	bio_list_merge(inmates, &cell->bios);
+
+	mempool_free(cell, prison->cell_pool);
+}
+
+void dm_cell_release_no_holder(struct dm_bio_prison_cell *cell, struct bio_list *inmates)
+{
+	unsigned long flags;
+	struct dm_bio_prison *prison = cell->prison;
+
+	spin_lock_irqsave(&prison->lock, flags);
+	__cell_release_no_holder(cell, inmates);
+	spin_unlock_irqrestore(&prison->lock, flags);
+}
+EXPORT_SYMBOL_GPL(dm_cell_release_no_holder);
+
+void dm_cell_error(struct dm_bio_prison_cell *cell)
+{
+	struct dm_bio_prison *prison = cell->prison;
+	struct bio_list bios;
+	struct bio *bio;
+	unsigned long flags;
+
+	bio_list_init(&bios);
+
+	spin_lock_irqsave(&prison->lock, flags);
+	__cell_release(cell, &bios);
+	spin_unlock_irqrestore(&prison->lock, flags);
+
+	while ((bio = bio_list_pop(&bios)))
+		bio_io_error(bio);
+}
+EXPORT_SYMBOL_GPL(dm_cell_error);
+
+/*----------------------------------------------------------------*/
+
+#define DEFERRED_SET_SIZE 64
+
+struct dm_deferred_entry {
+	struct dm_deferred_set *ds;
+	unsigned count;
+	struct list_head work_items;
+};
+
+struct dm_deferred_set {
+	spinlock_t lock;
+	unsigned current_entry;
+	unsigned sweeper;
+	struct dm_deferred_entry entries[DEFERRED_SET_SIZE];
+};
+
+struct dm_deferred_set *dm_deferred_set_create(void)
+{
+	int i;
+	struct dm_deferred_set *ds;
+
+	ds = kmalloc(sizeof(*ds), GFP_KERNEL);
+	if (!ds)
+		return NULL;
+
+	spin_lock_init(&ds->lock);
+	ds->current_entry = 0;
+	ds->sweeper = 0;
+	for (i = 0; i < DEFERRED_SET_SIZE; i++) {
+		ds->entries[i].ds = ds;
+		ds->entries[i].count = 0;
+		INIT_LIST_HEAD(&ds->entries[i].work_items);
+	}
+
+	return ds;
+}
+EXPORT_SYMBOL_GPL(dm_deferred_set_create);
+
+void dm_deferred_set_destroy(struct dm_deferred_set *ds)
+{
+	kfree(ds);
+}
+EXPORT_SYMBOL_GPL(dm_deferred_set_destroy);
+
+struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds)
+{
+	unsigned long flags;
+	struct dm_deferred_entry *entry;
+
+	spin_lock_irqsave(&ds->lock, flags);
+	entry = ds->entries + ds->current_entry;
+	entry->count++;
+	spin_unlock_irqrestore(&ds->lock, flags);
+
+	return entry;
+}
+EXPORT_SYMBOL_GPL(dm_deferred_entry_inc);
+
+static unsigned ds_next(unsigned index)
+{
+	return (index + 1) % DEFERRED_SET_SIZE;
+}
+
+static void __sweep(struct dm_deferred_set *ds, struct list_head *head)
+{
+	while ((ds->sweeper != ds->current_entry) &&
+	       !ds->entries[ds->sweeper].count) {
+		list_splice_init(&ds->entries[ds->sweeper].work_items, head);
+		ds->sweeper = ds_next(ds->sweeper);
+	}
+
+	if ((ds->sweeper == ds->current_entry) && !ds->entries[ds->sweeper].count)
+		list_splice_init(&ds->entries[ds->sweeper].work_items, head);
+}
+
+void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&entry->ds->lock, flags);
+	BUG_ON(!entry->count);
+	--entry->count;
+	__sweep(entry->ds, head);
+	spin_unlock_irqrestore(&entry->ds->lock, flags);
+}
+EXPORT_SYMBOL_GPL(dm_deferred_entry_dec);
+
+/*
+ * Returns 1 if deferred or 0 if no pending items to delay job.
+ */
+int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work)
+{
+	int r = 1;
+	unsigned long flags;
+	unsigned next_entry;
+
+	spin_lock_irqsave(&ds->lock, flags);
+	if ((ds->sweeper == ds->current_entry) &&
+	    !ds->entries[ds->current_entry].count)
+		r = 0;
+	else {
+		list_add(work, &ds->entries[ds->current_entry].work_items);
+		next_entry = ds_next(ds->current_entry);
+		if (!ds->entries[next_entry].count)
+			ds->current_entry = next_entry;
+	}
+	spin_unlock_irqrestore(&ds->lock, flags);
+
+	return r;
+}
+EXPORT_SYMBOL_GPL(dm_deferred_set_add_work);
+
+/*----------------------------------------------------------------*/
+
+static int __init dm_bio_prison_init(void)
+{
+	_cell_cache = KMEM_CACHE(dm_bio_prison_cell, 0);
+	if (!_cell_cache)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void __exit dm_bio_prison_exit(void)
+{
+	kmem_cache_destroy(_cell_cache);
+	_cell_cache = NULL;
+}
+
+/*
+ * module hooks
+ */
+module_init(dm_bio_prison_init);
+module_exit(dm_bio_prison_exit);
+
+MODULE_DESCRIPTION(DM_NAME " bio prison");
+MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
+MODULE_LICENSE("GPL");
diff --git a/drivers/md/dm-bio-prison.h b/drivers/md/dm-bio-prison.h
new file mode 100644
index 00000000000..4e0ac376700
--- /dev/null
+++ b/drivers/md/dm-bio-prison.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2011-2012 Red Hat, Inc.
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef DM_BIO_PRISON_H
+#define DM_BIO_PRISON_H
+
+#include "persistent-data/dm-block-manager.h" /* FIXME: for dm_block_t */
+#include "dm-thin-metadata.h" /* FIXME: for dm_thin_id */
+
+#include <linux/list.h>
+#include <linux/bio.h>
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Sometimes we can't deal with a bio straight away.  We put them in prison
+ * where they can't cause any mischief.  Bios are put in a cell identified
+ * by a key, multiple bios can be in the same cell.  When the cell is
+ * subsequently unlocked the bios become available.
+ */
+struct dm_bio_prison;
+struct dm_bio_prison_cell;
+
+/* FIXME: this needs to be more abstract */
+struct dm_cell_key {
+	int virtual;
+	dm_thin_id dev;
+	dm_block_t block;
+};
+
+struct dm_bio_prison *dm_bio_prison_create(unsigned nr_cells);
+void dm_bio_prison_destroy(struct dm_bio_prison *prison);
+
+/*
+ * This may block if a new cell needs allocating.  You must ensure that
+ * cells will be unlocked even if the calling thread is blocked.
+ *
+ * Returns 1 if the cell was already held, 0 if @inmate is the new holder.
+ */
+int dm_bio_detain(struct dm_bio_prison *prison, struct dm_cell_key *key,
+		  struct bio *inmate, struct dm_bio_prison_cell **ref);
+
+void dm_cell_release(struct dm_bio_prison_cell *cell, struct bio_list *bios);
+void dm_cell_release_singleton(struct dm_bio_prison_cell *cell, struct bio *bio); // FIXME: bio arg not needed
+void dm_cell_release_no_holder(struct dm_bio_prison_cell *cell, struct bio_list *inmates);
+void dm_cell_error(struct dm_bio_prison_cell *cell);
+
+/*----------------------------------------------------------------*/
+
+/*
+ * We use the deferred set to keep track of pending reads to shared blocks.
+ * We do this to ensure the new mapping caused by a write isn't performed
+ * until these prior reads have completed.  Otherwise the insertion of the
+ * new mapping could free the old block that the read bios are mapped to.
+ */
+
+struct dm_deferred_set;
+struct dm_deferred_entry;
+
+struct dm_deferred_set *dm_deferred_set_create(void);
+void dm_deferred_set_destroy(struct dm_deferred_set *ds);
+
+struct dm_deferred_entry *dm_deferred_entry_inc(struct dm_deferred_set *ds);
+void dm_deferred_entry_dec(struct dm_deferred_entry *entry, struct list_head *head);
+int dm_deferred_set_add_work(struct dm_deferred_set *ds, struct list_head *work);
+
+/*----------------------------------------------------------------*/
+
+#endif
diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index cc06a1e5242..651ca79881d 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -280,9 +280,7 @@ static void __cache_size_refresh(void)
 	BUG_ON(!mutex_is_locked(&dm_bufio_clients_lock));
 	BUG_ON(dm_bufio_client_count < 0);
 
-	dm_bufio_cache_size_latch = dm_bufio_cache_size;
-
-	barrier();
+	dm_bufio_cache_size_latch = ACCESS_ONCE(dm_bufio_cache_size);
 
 	/*
 	 * Use default if set to 0 and report the actual cache size used.
@@ -441,8 +439,7 @@ static void __relink_lru(struct dm_buffer *b, int dirty)
 	c->n_buffers[b->list_mode]--;
 	c->n_buffers[dirty]++;
 	b->list_mode = dirty;
-	list_del(&b->lru_list);
-	list_add(&b->lru_list, &c->lru[dirty]);
+	list_move(&b->lru_list, &c->lru[dirty]);
 }
 
 /*----------------------------------------------------------------
@@ -813,7 +810,7 @@ static void __get_memory_limit(struct dm_bufio_client *c,
 {
 	unsigned long buffers;
 
-	if (dm_bufio_cache_size != dm_bufio_cache_size_latch) {
+	if (ACCESS_ONCE(dm_bufio_cache_size) != dm_bufio_cache_size_latch) {
 		mutex_lock(&dm_bufio_clients_lock);
 		__cache_size_refresh();
 		mutex_unlock(&dm_bufio_clients_lock);
@@ -1591,11 +1588,9 @@ EXPORT_SYMBOL_GPL(dm_bufio_client_destroy);
 
 static void cleanup_old_buffers(void)
 {
-	unsigned long max_age = dm_bufio_max_age;
+	unsigned long max_age = ACCESS_ONCE(dm_bufio_max_age);
 	struct dm_bufio_client *c;
 
-	barrier();
-
 	if (max_age > ULONG_MAX / HZ)
 		max_age = ULONG_MAX / HZ;
 
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index d778563a4ff..573bd04591b 100644
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1309,13 +1309,14 @@ static int multipath_end_io(struct dm_target *ti, struct request *clone,
 {
 	struct multipath *m = ti->private;
 	struct dm_mpath_io *mpio = map_context->ptr;
-	struct pgpath *pgpath = mpio->pgpath;
+	struct pgpath *pgpath;
 	struct path_selector *ps;
 	int r;
 
 	BUG_ON(!mpio);
 
 	r  = do_end_io(m, clone, error, mpio);
+	pgpath = mpio->pgpath;
 	if (pgpath) {
 		ps = &pgpath->pg->ps;
 		if (ps->type->end_io)
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index c29410af1e2..058acf3a5ba 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -5,6 +5,7 @@
  */
 
 #include "dm-thin-metadata.h"
+#include "dm-bio-prison.h"
 #include "dm.h"
 
 #include <linux/device-mapper.h>
@@ -21,7 +22,6 @@
  * Tunable constants
  */
 #define ENDIO_HOOK_POOL_SIZE 1024
-#define DEFERRED_SET_SIZE 64
 #define MAPPING_POOL_SIZE 1024
 #define PRISON_CELLS 1024
 #define COMMIT_PERIOD HZ
@@ -58,7 +58,7 @@
  * i) plug io further to this physical block. (see bio_prison code).
  *
  * ii) quiesce any read io to that shared data block.  Obviously
- * including all devices that share this block.  (see deferred_set code)
+ * including all devices that share this block.  (see dm_deferred_set code)
  *
  * iii) copy the data block to a newly allocate block.  This step can be
  * missed out if the io covers the block. (schedule_copy).
@@ -99,381 +99,10 @@
 /*----------------------------------------------------------------*/
 
 /*
- * Sometimes we can't deal with a bio straight away.  We put them in prison
- * where they can't cause any mischief.  Bios are put in a cell identified
- * by a key, multiple bios can be in the same cell.  When the cell is
- * subsequently unlocked the bios become available.
- */
-struct bio_prison;
-
-struct cell_key {
-	int virtual;
-	dm_thin_id dev;
-	dm_block_t block;
-};
-
-struct dm_bio_prison_cell {
-	struct hlist_node list;
-	struct bio_prison *prison;
-	struct cell_key key;
-	struct bio *holder;
-	struct bio_list bios;
-};
-
-struct bio_prison {
-	spinlock_t lock;
-	mempool_t *cell_pool;
-
-	unsigned nr_buckets;
-	unsigned hash_mask;
-	struct hlist_head *cells;
-};
-
-static uint32_t calc_nr_buckets(unsigned nr_cells)
-{
-	uint32_t n = 128;
-
-	nr_cells /= 4;
-	nr_cells = min(nr_cells, 8192u);
-
-	while (n < nr_cells)
-		n <<= 1;
-
-	return n;
-}
-
-static struct kmem_cache *_cell_cache;
-
-/*
- * @nr_cells should be the number of cells you want in use _concurrently_.
- * Don't confuse it with the number of distinct keys.
- */
-static struct bio_prison *prison_create(unsigned nr_cells)
-{
-	unsigned i;
-	uint32_t nr_buckets = calc_nr_buckets(nr_cells);
-	size_t len = sizeof(struct bio_prison) +
-		(sizeof(struct hlist_head) * nr_buckets);
-	struct bio_prison *prison = kmalloc(len, GFP_KERNEL);
-
-	if (!prison)
-		return NULL;
-
-	spin_lock_init(&prison->lock);
-	prison->cell_pool = mempool_create_slab_pool(nr_cells, _cell_cache);
-	if (!prison->cell_pool) {
-		kfree(prison);
-		return NULL;
-	}
-
-	prison->nr_buckets = nr_buckets;
-	prison->hash_mask = nr_buckets - 1;
-	prison->cells = (struct hlist_head *) (prison + 1);
-	for (i = 0; i < nr_buckets; i++)
-		INIT_HLIST_HEAD(prison->cells + i);
-
-	return prison;
-}
-
-static void prison_destroy(struct bio_prison *prison)
-{
-	mempool_destroy(prison->cell_pool);
-	kfree(prison);
-}
-
-static uint32_t hash_key(struct bio_prison *prison, struct cell_key *key)
-{
-	const unsigned long BIG_PRIME = 4294967291UL;
-	uint64_t hash = key->block * BIG_PRIME;
-
-	return (uint32_t) (hash & prison->hash_mask);
-}
-
-static int keys_equal(struct cell_key *lhs, struct cell_key *rhs)
-{
-	       return (lhs->virtual == rhs->virtual) &&
-		       (lhs->dev == rhs->dev) &&
-		       (lhs->block == rhs->block);
-}
-
-static struct dm_bio_prison_cell *__search_bucket(struct hlist_head *bucket,
-						  struct cell_key *key)
-{
-	struct dm_bio_prison_cell *cell;
-	struct hlist_node *tmp;
-
-	hlist_for_each_entry(cell, tmp, bucket, list)
-		if (keys_equal(&cell->key, key))
-			return cell;
-
-	return NULL;
-}
-
-/*
- * This may block if a new cell needs allocating.  You must ensure that
- * cells will be unlocked even if the calling thread is blocked.
- *
- * Returns 1 if the cell was already held, 0 if @inmate is the new holder.
- */
-static int bio_detain(struct bio_prison *prison, struct cell_key *key,
-		      struct bio *inmate, struct dm_bio_prison_cell **ref)
-{
-	int r = 1;
-	unsigned long flags;
-	uint32_t hash = hash_key(prison, key);
-	struct dm_bio_prison_cell *cell, *cell2;
-
-	BUG_ON(hash > prison->nr_buckets);
-
-	spin_lock_irqsave(&prison->lock, flags);
-
-	cell = __search_bucket(prison->cells + hash, key);
-	if (cell) {
-		bio_list_add(&cell->bios, inmate);
-		goto out;
-	}
-
-	/*
-	 * Allocate a new cell
-	 */
-	spin_unlock_irqrestore(&prison->lock, flags);
-	cell2 = mempool_alloc(prison->cell_pool, GFP_NOIO);
-	spin_lock_irqsave(&prison->lock, flags);
-
-	/*
-	 * We've been unlocked, so we have to double check that
-	 * nobody else has inserted this cell in the meantime.
-	 */
-	cell = __search_bucket(prison->cells + hash, key);
-	if (cell) {
-		mempool_free(cell2, prison->cell_pool);
-		bio_list_add(&cell->bios, inmate);
-		goto out;
-	}
-
-	/*
-	 * Use new cell.
-	 */
-	cell = cell2;
-
-	cell->prison = prison;
-	memcpy(&cell->key, key, sizeof(cell->key));
-	cell->holder = inmate;
-	bio_list_init(&cell->bios);
-	hlist_add_head(&cell->list, prison->cells + hash);
-
-	r = 0;
-
-out:
-	spin_unlock_irqrestore(&prison->lock, flags);
-
-	*ref = cell;
-
-	return r;
-}
-
-/*
- * @inmates must have been initialised prior to this call
- */
-static void __cell_release(struct dm_bio_prison_cell *cell, struct bio_list *inmates)
-{
-	struct bio_prison *prison = cell->prison;
-
-	hlist_del(&cell->list);
-
-	if (inmates) {
-		bio_list_add(inmates, cell->holder);
-		bio_list_merge(inmates, &cell->bios);
-	}
-
-	mempool_free(cell, prison->cell_pool);
-}
-
-static void cell_release(struct dm_bio_prison_cell *cell, struct bio_list *bios)
-{
-	unsigned long flags;
-	struct bio_prison *prison = cell->prison;
-
-	spin_lock_irqsave(&prison->lock, flags);
-	__cell_release(cell, bios);
-	spin_unlock_irqrestore(&prison->lock, flags);
-}
-
-/*
- * There are a couple of places where we put a bio into a cell briefly
- * before taking it out again.  In these situations we know that no other
- * bio may be in the cell.  This function releases the cell, and also does
- * a sanity check.
- */
-static void __cell_release_singleton(struct dm_bio_prison_cell *cell, struct bio *bio)
-{
-	BUG_ON(cell->holder != bio);
-	BUG_ON(!bio_list_empty(&cell->bios));
-
-	__cell_release(cell, NULL);
-}
-
-static void cell_release_singleton(struct dm_bio_prison_cell *cell, struct bio *bio)
-{
-	unsigned long flags;
-	struct bio_prison *prison = cell->prison;
-
-	spin_lock_irqsave(&prison->lock, flags);
-	__cell_release_singleton(cell, bio);
-	spin_unlock_irqrestore(&prison->lock, flags);
-}
-
-/*
- * Sometimes we don't want the holder, just the additional bios.
- */
-static void __cell_release_no_holder(struct dm_bio_prison_cell *cell,
-				     struct bio_list *inmates)
-{
-	struct bio_prison *prison = cell->prison;
-
-	hlist_del(&cell->list);
-	bio_list_merge(inmates, &cell->bios);
-
-	mempool_free(cell, prison->cell_pool);
-}
-
-static void cell_release_no_holder(struct dm_bio_prison_cell *cell,
-				   struct bio_list *inmates)
-{
-	unsigned long flags;
-	struct bio_prison *prison = cell->prison;
-
-	spin_lock_irqsave(&prison->lock, flags);
-	__cell_release_no_holder(cell, inmates);
-	spin_unlock_irqrestore(&prison->lock, flags);
-}
-
-static void cell_error(struct dm_bio_prison_cell *cell)
-{
-	struct bio_prison *prison = cell->prison;
-	struct bio_list bios;
-	struct bio *bio;
-	unsigned long flags;
-
-	bio_list_init(&bios);
-
-	spin_lock_irqsave(&prison->lock, flags);
-	__cell_release(cell, &bios);
-	spin_unlock_irqrestore(&prison->lock, flags);
-
-	while ((bio = bio_list_pop(&bios)))
-		bio_io_error(bio);
-}
-
-/*----------------------------------------------------------------*/
-
-/*
- * We use the deferred set to keep track of pending reads to shared blocks.
- * We do this to ensure the new mapping caused by a write isn't performed
- * until these prior reads have completed.  Otherwise the insertion of the
- * new mapping could free the old block that the read bios are mapped to.
- */
-
-struct deferred_set;
-struct deferred_entry {
-	struct deferred_set *ds;
-	unsigned count;
-	struct list_head work_items;
-};
-
-struct deferred_set {
-	spinlock_t lock;
-	unsigned current_entry;
-	unsigned sweeper;
-	struct deferred_entry entries[DEFERRED_SET_SIZE];
-};
-
-static void ds_init(struct deferred_set *ds)
-{
-	int i;
-
-	spin_lock_init(&ds->lock);
-	ds->current_entry = 0;
-	ds->sweeper = 0;
-	for (i = 0; i < DEFERRED_SET_SIZE; i++) {
-		ds->entries[i].ds = ds;
-		ds->entries[i].count = 0;
-		INIT_LIST_HEAD(&ds->entries[i].work_items);
-	}
-}
-
-static struct deferred_entry *ds_inc(struct deferred_set *ds)
-{
-	unsigned long flags;
-	struct deferred_entry *entry;
-
-	spin_lock_irqsave(&ds->lock, flags);
-	entry = ds->entries + ds->current_entry;
-	entry->count++;
-	spin_unlock_irqrestore(&ds->lock, flags);
-
-	return entry;
-}
-
-static unsigned ds_next(unsigned index)
-{
-	return (index + 1) % DEFERRED_SET_SIZE;
-}
-
-static void __sweep(struct deferred_set *ds, struct list_head *head)
-{
-	while ((ds->sweeper != ds->current_entry) &&
-	       !ds->entries[ds->sweeper].count) {
-		list_splice_init(&ds->entries[ds->sweeper].work_items, head);
-		ds->sweeper = ds_next(ds->sweeper);
-	}
-
-	if ((ds->sweeper == ds->current_entry) && !ds->entries[ds->sweeper].count)
-		list_splice_init(&ds->entries[ds->sweeper].work_items, head);
-}
-
-static void ds_dec(struct deferred_entry *entry, struct list_head *head)
-{
-	unsigned long flags;
-
-	spin_lock_irqsave(&entry->ds->lock, flags);
-	BUG_ON(!entry->count);
-	--entry->count;
-	__sweep(entry->ds, head);
-	spin_unlock_irqrestore(&entry->ds->lock, flags);
-}
-
-/*
- * Returns 1 if deferred or 0 if no pending items to delay job.
- */
-static int ds_add_work(struct deferred_set *ds, struct list_head *work)
-{
-	int r = 1;
-	unsigned long flags;
-	unsigned next_entry;
-
-	spin_lock_irqsave(&ds->lock, flags);
-	if ((ds->sweeper == ds->current_entry) &&
-	    !ds->entries[ds->current_entry].count)
-		r = 0;
-	else {
-		list_add(work, &ds->entries[ds->current_entry].work_items);
-		next_entry = ds_next(ds->current_entry);
-		if (!ds->entries[next_entry].count)
-			ds->current_entry = next_entry;
-	}
-	spin_unlock_irqrestore(&ds->lock, flags);
-
-	return r;
-}
-
-/*----------------------------------------------------------------*/
-
-/*
  * Key building.
  */
 static void build_data_key(struct dm_thin_device *td,
-			   dm_block_t b, struct cell_key *key)
+			   dm_block_t b, struct dm_cell_key *key)
 {
 	key->virtual = 0;
 	key->dev = dm_thin_dev_id(td);
@@ -481,7 +110,7 @@ static void build_data_key(struct dm_thin_device *td,
 }
 
 static void build_virtual_key(struct dm_thin_device *td, dm_block_t b,
-			      struct cell_key *key)
+			      struct dm_cell_key *key)
 {
 	key->virtual = 1;
 	key->dev = dm_thin_dev_id(td);
@@ -534,7 +163,7 @@ struct pool {
 	unsigned low_water_triggered:1;	/* A dm event has been sent */
 	unsigned no_free_space:1;	/* A -ENOSPC warning has been issued */
 
-	struct bio_prison *prison;
+	struct dm_bio_prison *prison;
 	struct dm_kcopyd_client *copier;
 
 	struct workqueue_struct *wq;
@@ -552,8 +181,8 @@ struct pool {
 
 	struct bio_list retry_on_resume_list;
 
-	struct deferred_set shared_read_ds;
-	struct deferred_set all_io_ds;
+	struct dm_deferred_set *shared_read_ds;
+	struct dm_deferred_set *all_io_ds;
 
 	struct dm_thin_new_mapping *next_mapping;
 	mempool_t *mapping_pool;
@@ -660,8 +289,8 @@ static struct pool *__pool_table_lookup_metadata_dev(struct block_device *md_dev
 
 struct dm_thin_endio_hook {
 	struct thin_c *tc;
-	struct deferred_entry *shared_read_entry;
-	struct deferred_entry *all_io_entry;
+	struct dm_deferred_entry *shared_read_entry;
+	struct dm_deferred_entry *all_io_entry;
 	struct dm_thin_new_mapping *overwrite_mapping;
 };
 
@@ -877,7 +506,7 @@ static void cell_defer(struct thin_c *tc, struct dm_bio_prison_cell *cell,
 	unsigned long flags;
 
 	spin_lock_irqsave(&pool->lock, flags);
-	cell_release(cell, &pool->deferred_bios);
+	dm_cell_release(cell, &pool->deferred_bios);
 	spin_unlock_irqrestore(&tc->pool->lock, flags);
 
 	wake_worker(pool);
@@ -896,7 +525,7 @@ static void cell_defer_except(struct thin_c *tc, struct dm_bio_prison_cell *cell
 	bio_list_init(&bios);
 
 	spin_lock_irqsave(&pool-&g