[PATCH 2/2 v2] dm thin: elevate the bio_prison and deferred_set code to allow for re-use

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Allow other DM targets to make use of the bio_prison and deferred_set
infrastructure.  Code elevated to drivers/md/dm-bio-prison.[hc]

Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
---
 drivers/md/Makefile           |    2 
 drivers/md/dm-bio-prison.c    |  336 ++++++++++++++++++++++++++++++++
 drivers/md/dm-bio-prison.h    |  109 ++++++++++
 drivers/md/dm-thin-metadata.h |    6 
 drivers/md/dm-thin.c          |  438 +++---------------------------------------
 5 files changed, 483 insertions(+), 408 deletions(-)
 create mode 100644 drivers/md/dm-bio-prison.c
 create mode 100644 drivers/md/dm-bio-prison.h

Index: linux-2.6/drivers/md/Makefile
===================================================================
--- linux-2.6.orig/drivers/md/Makefile
+++ linux-2.6/drivers/md/Makefile
@@ -3,7 +3,7 @@
 #
 
 dm-mod-y	+= dm.o dm-table.o dm-target.o dm-linear.o dm-stripe.o \
-		   dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o
+		   dm-ioctl.o dm-io.o dm-kcopyd.o dm-sysfs.o dm-bio-prison.o
 dm-multipath-y	+= dm-path-selector.o dm-mpath.o
 dm-snapshot-y	+= dm-snap.o dm-exception-store.o dm-snap-transient.o \
 		    dm-snap-persistent.o
Index: linux-2.6/drivers/md/dm-bio-prison.c
===================================================================
--- /dev/null
+++ linux-2.6/drivers/md/dm-bio-prison.c
@@ -0,0 +1,336 @@
+/*
+ * Copyright (C) 2012 Red Hat.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-bio-prison.h"
+
+#include <linux/module.h>
+
+/*----------------------------------------------------------------*/
+
+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;
+}
+
+/*
+ * @nr_cells should be the number of cells you want in use _concurrently_.
+ * Don't confuse it with the number of distinct keys.
+ */
+struct bio_prison *dm_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_kmalloc_pool(nr_cells,
+							sizeof(struct cell));
+	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_prison_create);
+
+void dm_prison_destroy(struct bio_prison *prison)
+{
+	mempool_destroy(prison->cell_pool);
+	kfree(prison);
+}
+EXPORT_SYMBOL_GPL(dm_prison_destroy);
+
+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 cell *__search_bucket(struct hlist_head *bucket,
+				    struct cell_key *key)
+{
+	struct 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 bio_prison *prison, struct cell_key *key,
+		  struct bio *inmate, struct cell **ref)
+{
+	int r;
+	unsigned long flags;
+	uint32_t hash = hash_key(prison, key);
+	struct cell *uninitialized_var(cell), *cell2 = NULL;
+
+	BUG_ON(hash > prison->nr_buckets);
+
+	spin_lock_irqsave(&prison->lock, flags);
+	cell = __search_bucket(prison->cells + hash, key);
+
+	if (!cell) {
+		/*
+		 * 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) {
+			cell = cell2;
+			cell2 = NULL;
+
+			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;
+
+		} else {
+			mempool_free(cell2, prison->cell_pool);
+			cell2 = NULL;
+			r = 1;
+			bio_list_add(&cell->bios, inmate);
+		}
+
+	} else {
+		r = 1;
+		bio_list_add(&cell->bios, inmate);
+	}
+	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 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);
+}
+
+void dm_cell_release(struct 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);
+}
+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 cell *cell, struct bio *bio)
+{
+	hlist_del(&cell->list);
+	BUG_ON(cell->holder != bio);
+	BUG_ON(!bio_list_empty(&cell->bios));
+}
+
+void dm_cell_release_singleton(struct 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);
+}
+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 cell *cell, struct bio_list *inmates)
+{
+	struct bio_prison *prison = cell->prison;
+
+	hlist_del(&cell->list);
+	if (inmates)
+		bio_list_merge(inmates, &cell->bios);
+
+	mempool_free(cell, prison->cell_pool);
+}
+
+void dm_cell_release_no_holder(struct 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);
+}
+EXPORT_SYMBOL_GPL(dm_cell_release_no_holder);
+
+void dm_cell_error(struct 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);
+}
+EXPORT_SYMBOL_GPL(dm_cell_error);
+
+/*----------------------------------------------------------------*/
+
+void dm_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);
+	}
+}
+EXPORT_SYMBOL_GPL(dm_ds_init);
+
+struct deferred_entry *dm_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;
+}
+EXPORT_SYMBOL_GPL(dm_ds_inc);
+
+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);
+}
+
+void dm_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);
+}
+EXPORT_SYMBOL_GPL(dm_ds_dec);
+
+/*
+ * Returns 1 if deferred or 0 if no pending items to delay job.
+ */
+int dm_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;
+}
+EXPORT_SYMBOL_GPL(dm_ds_add_work);
+
+/*----------------------------------------------------------------*/
Index: linux-2.6/drivers/md/dm-bio-prison.h
===================================================================
--- /dev/null
+++ linux-2.6/drivers/md/dm-bio-prison.h
@@ -0,0 +1,109 @@
+/*
+ * Copyright (C) 2012 Red Hat.
+ *
+ * This file is released under the GPL.
+ */
+
+#ifndef DM_BIO_PRISON_H
+#define DM_BIO_PRISON_H
+
+#include "persistent-data/dm-block-manager.h"
+
+#include <linux/list.h>
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Device identifier
+ */
+typedef uint64_t dm_dev_id;
+
+/*----------------------------------------------------------------*/
+
+/*
+ * 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_dev_id dev;
+	dm_block_t block;
+};
+
+struct 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;
+};
+
+/*
+ * @nr_cells should be the number of cells you want in use _concurrently_.
+ * Don't confuse it with the number of distinct keys.
+ */
+struct bio_prison *dm_prison_create(unsigned nr_cells);
+void dm_prison_destroy(struct 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 bio_prison *prison, struct cell_key *key,
+	       struct bio *inmate, struct cell **ref);
+void dm_cell_release(struct cell *cell, struct bio_list *bios);
+void dm_cell_release_singleton(struct cell *cell, struct bio *bio);
+void dm_cell_release_no_holder(struct cell *cell, struct bio_list *inmates);
+void dm_cell_error(struct 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.
+ */
+#define DEFERRED_SET_SIZE 64
+
+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];
+};
+
+void dm_ds_init(struct deferred_set *ds);
+struct deferred_entry *dm_ds_inc(struct deferred_set *ds);
+void dm_ds_dec(struct deferred_entry *entry, struct list_head *head);
+
+/*
+ * Returns 1 if deferred or 0 if no pending items to delay job.
+ */
+int dm_ds_add_work(struct deferred_set *ds, struct list_head *work);
+
+/*----------------------------------------------------------------*/
+
+#endif
Index: linux-2.6/drivers/md/dm-thin-metadata.h
===================================================================
--- linux-2.6.orig/drivers/md/dm-thin-metadata.h
+++ linux-2.6/drivers/md/dm-thin-metadata.h
@@ -7,6 +7,7 @@
 #ifndef DM_THIN_METADATA_H
 #define DM_THIN_METADATA_H
 
+#include "dm-bio-prison.h"
 #include "persistent-data/dm-block-manager.h"
 
 #define THIN_METADATA_BLOCK_SIZE 4096
@@ -32,11 +33,6 @@ struct dm_pool_metadata;
 struct dm_thin_device;
 
 /*
- * Device identifier
- */
-typedef uint64_t dm_dev_id;
-
-/*
  * Reopens or creates a new, empty metadata volume.
  */
 struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
Index: linux-2.6/drivers/md/dm-thin.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-thin.c
+++ linux-2.6/drivers/md/dm-thin.c
@@ -4,6 +4,7 @@
  * This file is released under the GPL.
  */
 
+#include "dm-bio-prison.h"
 #include "dm-thin-metadata.h"
 
 #include <linux/device-mapper.h>
@@ -20,7 +21,6 @@
  * Tunable constants
  */
 #define ENDIO_HOOK_POOL_SIZE 10240
-#define DEFERRED_SET_SIZE 64
 #define MAPPING_POOL_SIZE 1024
 #define PRISON_CELLS 1024
 #define COMMIT_PERIOD HZ
@@ -98,372 +98,6 @@
 /*----------------------------------------------------------------*/
 
 /*
- * 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_dev_id dev;
-	dm_block_t block;
-};
-
-struct 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;
-}
-
-/*
- * @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_kmalloc_pool(nr_cells,
-							sizeof(struct cell));
-	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 cell *__search_bucket(struct hlist_head *bucket,
-				    struct cell_key *key)
-{
-	struct 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 cell **ref)
-{
-	int r;
-	unsigned long flags;
-	uint32_t hash = hash_key(prison, key);
-	struct cell *uninitialized_var(cell), *cell2 = NULL;
-
-	BUG_ON(hash > prison->nr_buckets);
-
-	spin_lock_irqsave(&prison->lock, flags);
-	cell = __search_bucket(prison->cells + hash, key);
-
-	if (!cell) {
-		/*
-		 * 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) {
-			cell = cell2;
-			cell2 = NULL;
-
-			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;
-
-		} else {
-			mempool_free(cell2, prison->cell_pool);
-			cell2 = NULL;
-			r = 1;
-			bio_list_add(&cell->bios, inmate);
-		}
-
-	} else {
-		r = 1;
-		bio_list_add(&cell->bios, inmate);
-	}
-	spin_unlock_irqrestore(&prison->lock, flags);
-
-	*ref = cell;
-	return r;
-}
-
-/*
- * @inmates must have been initialised prior to this call
- */
-static void __cell_release(struct 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 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 cell *cell, struct bio *bio)
-{
-	hlist_del(&cell->list);
-	BUG_ON(cell->holder != bio);
-	BUG_ON(!bio_list_empty(&cell->bios));
-}
-
-static void cell_release_singleton(struct 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 cell *cell, struct bio_list *inmates)
-{
-	struct bio_prison *prison = cell->prison;
-
-	hlist_del(&cell->list);
-	if (inmates)
-		bio_list_merge(inmates, &cell->bios);
-
-	mempool_free(cell, prison->cell_pool);
-}
-
-static void cell_release_no_holder(struct 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 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,
@@ -816,7 +450,7 @@ static void cell_defer(struct thin_c *tc
 	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);
@@ -835,7 +469,7 @@ static void cell_defer_except(struct thi
 	bio_list_init(&bios);
 
 	spin_lock_irqsave(&pool->lock, flags);
-	cell_release_no_holder(cell, &pool->deferred_bios);
+	dm_cell_release_no_holder(cell, &pool->deferred_bios);
 	spin_unlock_irqrestore(&pool->lock, flags);
 
 	wake_worker(pool);
@@ -852,7 +486,7 @@ static void process_prepared_mapping(str
 		bio->bi_end_io = m->saved_bi_end_io;
 
 	if (m->err) {
-		cell_error(m->cell);
+		dm_cell_error(m->cell);
 		return;
 	}
 
@@ -864,7 +498,7 @@ static void process_prepared_mapping(str
 	r = dm_thin_insert_block(tc->td, m->virt_block, m->data_block);
 	if (r) {
 		DMERR("dm_thin_insert_block() failed");
-		cell_error(m->cell);
+		dm_cell_error(m->cell);
 		return;
 	}
 
@@ -983,7 +617,7 @@ static void schedule_copy(struct thin_c 
 	m->err = 0;
 	m->bio = NULL;
 
-	if (!ds_add_work(&pool->shared_read_ds, &m->list))
+	if (!dm_ds_add_work(&pool->shared_read_ds, &m->list))
 		m->quiesced = 1;
 
 	/*
@@ -1014,7 +648,7 @@ static void schedule_copy(struct thin_c 
 		if (r < 0) {
 			mempool_free(m, pool->mapping_pool);
 			DMERR("dm_kcopyd_copy() failed");
-			cell_error(cell);
+			dm_cell_error(cell);
 		}
 	}
 }
@@ -1079,7 +713,7 @@ static void schedule_zero(struct thin_c 
 		if (r < 0) {
 			mempool_free(m, pool->mapping_pool);
 			DMERR("dm_kcopyd_zero() failed");
-			cell_error(cell);
+			dm_cell_error(cell);
 		}
 	}
 }
@@ -1167,7 +801,7 @@ static void no_space(struct cell *cell)
 	struct bio_list bios;
 
 	bio_list_init(&bios);
-	cell_release(cell, &bios);
+	dm_cell_release(cell, &bios);
 
 	while ((bio = bio_list_pop(&bios)))
 		retry_on_resume(bio);
@@ -1184,7 +818,7 @@ static void process_discard(struct thin_
 	struct new_mapping *m;
 
 	build_virtual_key(tc->td, block, &key);
-	if (bio_detain(tc->pool->prison, &key, bio, &cell))
+	if (dm_bio_detain(tc->pool->prison, &key, bio, &cell))
 		return;
 
 	r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
@@ -1196,8 +830,8 @@ static void process_discard(struct thin_
 		 * on this block.
 		 */
 		build_data_key(tc->td, lookup_result.block, &key2);
-		if (bio_detain(tc->pool->prison, &key2, bio, &cell2)) {
-			cell_release_singleton(cell, bio);
+		if (dm_bio_detain(tc->pool->prison, &key2, bio, &cell2)) {
+			dm_cell_release_singleton(cell, bio);
 			break;
 		}
 
@@ -1216,7 +850,7 @@ static void process_discard(struct thin_
 			m->err = 0;
 			m->bio = bio;
 
-			if (!ds_add_work(&pool->all_io_ds, &m->list)) {
+			if (!dm_ds_add_work(&pool->all_io_ds, &m->list)) {
 				list_add(&m->list, &pool->prepared_discards);
 				wake_worker(pool);
 			}
@@ -1231,8 +865,8 @@ static void process_discard(struct thin_
 			unsigned remaining = (pool->sectors_per_block - offset) << 9;
 			bio->bi_size = min(bio->bi_size, remaining);
 
-			cell_release_singleton(cell, bio);
-			cell_release_singleton(cell2, bio);
+			dm_cell_release_singleton(cell, bio);
+			dm_cell_release_singleton(cell2, bio);
 			remap_and_issue(tc, bio, lookup_result.block);
 		}
 		break;
@@ -1241,13 +875,13 @@ static void process_discard(struct thin_
 		/*
 		 * It isn't provisioned, just forget it.
 		 */
-		cell_release_singleton(cell, bio);
+		dm_cell_release_singleton(cell, bio);
 		bio_endio(bio, 0);
 		break;
 
 	default:
 		DMERR("discard: find block unexpectedly returned %d\n", r);
-		cell_release_singleton(cell, bio);
+		dm_cell_release_singleton(cell, bio);
 		bio_io_error(bio);
 		break;
 	}
@@ -1274,7 +908,7 @@ static void break_sharing(struct thin_c 
 
 	default:
 		DMERR("%s: alloc_data_block() failed, error = %d", __func__, r);
-		cell_error(cell);
+		dm_cell_error(cell);
 		break;
 	}
 }
@@ -1292,7 +926,7 @@ static void process_shared_bio(struct th
 	 * of being broken so we have nothing further to do here.
 	 */
 	build_data_key(tc->td, lookup_result->block, &key);
-	if (bio_detain(pool->prison, &key, bio, &cell))
+	if (dm_bio_detain(pool->prison, &key, bio, &cell))
 		return;
 
 	if (bio_data_dir(bio) == WRITE)
@@ -1300,9 +934,9 @@ static void process_shared_bio(struct th
 	else {
 		struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
 
-		h->shared_read_entry = ds_inc(&pool->shared_read_ds);
+		h->shared_read_entry = dm_ds_inc(&pool->shared_read_ds);
 
-		cell_release_singleton(cell, bio);
+		dm_cell_release_singleton(cell, bio);
 		remap_and_issue(tc, bio, lookup_result->block);
 	}
 }
@@ -1317,7 +951,7 @@ static void provision_block(struct thin_
 	 * Remap empty bios (flushes) immediately, without provisioning.
 	 */
 	if (!bio->bi_size) {
-		cell_release_singleton(cell, bio);
+		dm_cell_release_singleton(cell, bio);
 		remap_and_issue(tc, bio, 0);
 		return;
 	}
@@ -1327,7 +961,7 @@ static void provision_block(struct thin_
 	 */
 	if (bio_data_dir(bio) == READ) {
 		zero_fill_bio(bio);
-		cell_release_singleton(cell, bio);
+		dm_cell_release_singleton(cell, bio);
 		bio_endio(bio, 0);
 		return;
 	}
@@ -1347,7 +981,7 @@ static void provision_block(struct thin_
 
 	default:
 		DMERR("%s: alloc_data_block() failed, error = %d", __func__, r);
-		cell_error(cell);
+		dm_cell_error(cell);
 		break;
 	}
 }
@@ -1365,7 +999,7 @@ static void process_bio(struct thin_c *t
 	 * being provisioned so we have nothing further to do here.
 	 */
 	build_virtual_key(tc->td, block, &key);
-	if (bio_detain(tc->pool->prison, &key, bio, &cell))
+	if (dm_bio_detain(tc->pool->prison, &key, bio, &cell))
 		return;
 
 	r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
@@ -1380,7 +1014,7 @@ static void process_bio(struct thin_c *t
 		 * TODO: this will probably have to change when discard goes
 		 * back in.
 		 */
-		cell_release_singleton(cell, bio);
+		dm_cell_release_singleton(cell, bio);
 
 		if (lookup_result.shared)
 			process_shared_bio(tc, bio, block, &lookup_result);
@@ -1390,7 +1024,7 @@ static void process_bio(struct thin_c *t
 
 	case -ENODATA:
 		if (bio_data_dir(bio) == READ && tc->origin_dev) {
-			cell_release_singleton(cell, bio);
+			dm_cell_release_singleton(cell, bio);
 			remap_to_origin_and_issue(tc, bio);
 		} else
 			provision_block(tc, bio, block, cell);
@@ -1398,7 +1032,7 @@ static void process_bio(struct thin_c *t
 
 	default:
 		DMERR("dm_thin_find_block() failed, error = %d", r);
-		cell_release_singleton(cell, bio);
+		dm_cell_release_singleton(cell, bio);
 		bio_io_error(bio);
 		break;
 	}
@@ -1522,7 +1156,7 @@ static struct endio_hook *thin_hook_bio(
 
 	h->tc = tc;
 	h->shared_read_entry = NULL;
-	h->all_io_entry = bio->bi_rw & REQ_DISCARD ? NULL : ds_inc(&pool->all_io_ds);
+	h->all_io_entry = bio->bi_rw & REQ_DISCARD ? NULL : dm_ds_inc(&pool->all_io_ds);
 	h->overwrite_mapping = NULL;
 
 	return h;
@@ -1652,7 +1286,7 @@ static void __pool_destroy(struct pool *
 	if (dm_pool_metadata_close(pool->pmd) < 0)
 		DMWARN("%s: dm_pool_metadata_close() failed.", __func__);
 
-	prison_destroy(pool->prison);
+	dm_prison_destroy(pool->prison);
 	dm_kcopyd_client_destroy(pool->copier);
 
 	if (pool->wq)
@@ -1693,7 +1327,7 @@ static struct pool *pool_create(struct m
 	pool->offset_mask = block_size - 1;
 	pool->low_water_blocks = 0;
 	pool_features_init(&pool->pf);
-	pool->prison = prison_create(PRISON_CELLS);
+	pool->prison = dm_prison_create(PRISON_CELLS);
 	if (!pool->prison) {
 		*error = "Error creating pool's bio prison";
 		err_p = ERR_PTR(-ENOMEM);
@@ -1729,8 +1363,8 @@ static struct pool *pool_create(struct m
 	pool->low_water_triggered = 0;
 	pool->no_free_space = 0;
 	bio_list_init(&pool->retry_on_resume_list);
-	ds_init(&pool->shared_read_ds);
-	ds_init(&pool->all_io_ds);
+	dm_ds_init(&pool->shared_read_ds);
+	dm_ds_init(&pool->all_io_ds);
 
 	pool->next_mapping = NULL;
 	pool->mapping_pool =
@@ -1763,7 +1397,7 @@ bad_mapping_pool:
 bad_wq:
 	dm_kcopyd_client_destroy(pool->copier);
 bad_kcopyd_client:
-	prison_destroy(pool->prison);
+	dm_prison_destroy(pool->prison);
 bad_prison:
 	kfree(pool);
 bad_pool:
@@ -2614,7 +2248,7 @@ static int thin_endio(struct dm_target *
 
 	if (h->shared_read_entry) {
 		INIT_LIST_HEAD(&work);
-		ds_dec(h->shared_read_entry, &work);
+		dm_ds_dec(h->shared_read_entry, &work);
 
 		spin_lock_irqsave(&pool->lock, flags);
 		list_for_each_entry_safe(m, tmp, &work, list) {
@@ -2627,7 +2261,7 @@ static int thin_endio(struct dm_target *
 
 	if (h->all_io_entry) {
 		INIT_LIST_HEAD(&work);
-		ds_dec(h->all_io_entry, &work);
+		dm_ds_dec(h->all_io_entry, &work);
 		list_for_each_entry_safe(m, tmp, &work, list)
 			list_add(&m->list, &pool->prepared_discards);
 	}

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