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* [PATCH 1/3] dm bio prison: factor bio prison code out to standalone library
@ 2012-09-25 22:35 Mike Snitzer
  2012-09-25 22:35 ` [PATCH 2/3] dm thin: remove old bio prison code that now lives in dm-bio-prison.c Mike Snitzer
  2012-09-25 22:35 ` [PATCH 3/3] dm bio prison: add "dm_" prefix to bio prison and deferred set interfaces Mike Snitzer
  0 siblings, 2 replies; 3+ messages in thread
From: Mike Snitzer @ 2012-09-25 22:35 UTC (permalink / raw)
  To: dm-devel

The bio prison code will be useful to other future DM targets.  No
functional change, code was factored out to facilitate code re-use.

Old bio-prison code in dm-thin.c was commented out to avoid all the code
removal noise in favor of focusing on the non-removal changes needed to
separate the code out of dm-thin.c

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Joe Thornber <ejt@redhat.com>
---
 drivers/md/Kconfig         |    7 +
 drivers/md/Makefile        |    1 +
 drivers/md/dm-bio-prison.c |  429 ++++++++++++++++++++++++++++++++++++++++++++
 drivers/md/dm-bio-prison.h |   76 ++++++++
 drivers/md/dm-thin.c       |   40 +++--
 5 files changed, 537 insertions(+), 16 deletions(-)
 create mode 100644 drivers/md/dm-bio-prison.c
 create mode 100644 drivers/md/dm-bio-prison.h

diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index d949b78..78c70a8 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -216,6 +216,12 @@ 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 device-mapper targets.
+
 source "drivers/md/persistent-data/Kconfig"
 
 config DM_CRYPT
@@ -247,6 +253,7 @@ 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 8b2e0df..94dce8b 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 0000000..fdf9c19
--- /dev/null
+++ b/drivers/md/dm-bio-prison.c
@@ -0,0 +1,429 @@
+/*
+ * Copyright (C) 2012 Red Hat UK.
+ *
+ * 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 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.
+ */
+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;
+}
+EXPORT_SYMBOL_GPL(prison_create);
+
+void prison_destroy(struct bio_prison *prison)
+{
+	mempool_destroy(prison->cell_pool);
+	kfree(prison);
+}
+EXPORT_SYMBOL_GPL(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 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;
+}
+
+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;
+}
+EXPORT_SYMBOL_GPL(bio_detain);
+
+int bio_detain_if_occupied(struct bio_prison *prison, struct cell_key *key,
+			   struct bio *inmate)
+{
+	int r = 0;
+	unsigned long flags;
+	uint32_t hash = hash_key(prison, key);
+	struct dm_bio_prison_cell *cell;
+
+	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);
+		r = 1;
+	}
+
+	spin_unlock_irqrestore(&prison->lock, flags);
+	return r;
+}
+EXPORT_SYMBOL_GPL(bio_detain_if_occupied);
+
+/*
+ * @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);
+}
+
+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);
+}
+EXPORT_SYMBOL_GPL(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 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);
+}
+EXPORT_SYMBOL_GPL(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 bio_prison *prison = cell->prison;
+
+	hlist_del(&cell->list);
+	bio_list_merge(inmates, &cell->bios);
+
+	mempool_free(cell, prison->cell_pool);
+}
+
+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);
+}
+EXPORT_SYMBOL_GPL(cell_release_no_holder);
+
+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);
+}
+EXPORT_SYMBOL_GPL(cell_error);
+
+/*----------------------------------------------------------------*/
+
+#define DEFERRED_SET_SIZE 64
+
+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];
+};
+
+struct deferred_set *ds_create(void)
+{
+	int i;
+	struct deferred_set *ds;
+
+	ds = kmalloc(sizeof(*ds), GFP_KERNEL);
+
+	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(ds_create);
+
+void ds_destroy(struct deferred_set *ds)
+{
+	kfree(ds);
+}
+EXPORT_SYMBOL_GPL(ds_destroy);
+
+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;
+}
+EXPORT_SYMBOL_GPL(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 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(ds_dec);
+
+/*
+ * Returns 1 if deferred or 0 if no pending items to delay job.
+ */
+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;
+}
+EXPORT_SYMBOL_GPL(ds_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 0000000..0d9d270
--- /dev/null
+++ b/drivers/md/dm-bio-prison.h
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2012 Red Hat UK.  All rights reserved.
+ *
+ * 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>
+
+/*----------------------------------------------------------------*/
+
+/* FIXME: prefix everything */
+
+/*
+ * 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 dm_bio_prison_cell;
+
+/* FIXME: this needs to be more abstract */
+struct cell_key {
+	int virtual;
+	dm_thin_id dev;
+	dm_block_t block;
+};
+
+struct bio_prison *prison_create(unsigned nr_cells);
+void 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 bio_detain(struct bio_prison *prison, struct cell_key *key,
+	       struct bio *inmate, struct dm_bio_prison_cell **ref);
+int bio_detain_if_occupied(struct bio_prison *prison, struct cell_key *key,
+			   struct bio *inmate);
+
+void cell_release(struct dm_bio_prison_cell *cell, struct bio_list *bios);
+void cell_release_singleton(struct dm_bio_prison_cell *cell, struct bio *bio); // FIXME: bio arg not needed
+void cell_release_no_holder(struct dm_bio_prison_cell *cell, struct bio_list *inmates);
+void 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 deferred_set;
+struct deferred_entry;
+
+struct deferred_set *ds_create(void);
+void ds_destroy(struct deferred_set *ds);
+
+struct deferred_entry *ds_inc(struct deferred_set *ds);
+void ds_dec(struct deferred_entry *entry, struct list_head *head);
+int ds_add_work(struct deferred_set *ds, struct list_head *work);
+
+/*----------------------------------------------------------------*/
+
+#endif
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 8e73f43..39f4d40 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
@@ -98,6 +98,7 @@
 
 /*----------------------------------------------------------------*/
 
+#if 0
 /*
  * 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
@@ -467,6 +468,8 @@ static int ds_add_work(struct deferred_set *ds, struct list_head *work)
 	return r;
 }
 
+#endif
+
 /*----------------------------------------------------------------*/
 
 /*
@@ -552,8 +555,8 @@ struct pool {
 
 	struct bio_list retry_on_resume_list;
 
-	struct deferred_set shared_read_ds;
-	struct deferred_set all_io_ds;
+	struct deferred_set *shared_read_ds;
+	struct deferred_set *all_io_ds;
 
 	struct dm_thin_new_mapping *next_mapping;
 	mempool_t *mapping_pool;
@@ -1067,7 +1070,7 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
 	m->err = 0;
 	m->bio = NULL;
 
-	if (!ds_add_work(&pool->shared_read_ds, &m->list))
+	if (!ds_add_work(pool->shared_read_ds, &m->list))
 		m->quiesced = 1;
 
 	/*
@@ -1326,7 +1329,7 @@ static void process_discard(struct thin_c *tc, struct bio *bio)
 			m->err = 0;
 			m->bio = bio;
 
-			if (!ds_add_work(&pool->all_io_ds, &m->list)) {
+			if (!ds_add_work(pool->all_io_ds, &m->list)) {
 				spin_lock_irqsave(&pool->lock, flags);
 				list_add(&m->list, &pool->prepared_discards);
 				spin_unlock_irqrestore(&pool->lock, flags);
@@ -1410,7 +1413,7 @@ static void process_shared_bio(struct thin_c *tc, struct bio *bio,
 	else {
 		struct dm_thin_endio_hook *h = dm_get_mapinfo(bio)->ptr;
 
-		h->shared_read_entry = ds_inc(&pool->shared_read_ds);
+		h->shared_read_entry = ds_inc(pool->shared_read_ds);
 
 		cell_release_singleton(cell, bio);
 		remap_and_issue(tc, bio, lookup_result->block);
@@ -1718,7 +1721,7 @@ static struct dm_thin_endio_hook *thin_hook_bio(struct thin_c *tc, struct bio *b
 
 	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 : ds_inc(pool->all_io_ds);
 	h->overwrite_mapping = NULL;
 
 	return h;
@@ -1938,6 +1941,8 @@ static void __pool_destroy(struct pool *pool)
 		mempool_free(pool->next_mapping, pool->mapping_pool);
 	mempool_destroy(pool->mapping_pool);
 	mempool_destroy(pool->endio_hook_pool);
+	ds_destroy(pool->shared_read_ds);
+	ds_destroy(pool->all_io_ds);
 	kfree(pool);
 }
 
@@ -2012,8 +2017,14 @@ static struct pool *pool_create(struct mapped_device *pool_md,
 	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);
+
+	pool->shared_read_ds = ds_create();
+	if (!pool->shared_read_ds)
+		goto bad_shared_ds;
+
+	pool->all_io_ds = ds_create();
+	if (!pool->all_io_ds)
+		goto bad_all_io_ds;
 
 	pool->next_mapping = NULL;
 	pool->mapping_pool = mempool_create_slab_pool(MAPPING_POOL_SIZE,
@@ -2042,6 +2053,10 @@ static struct pool *pool_create(struct mapped_device *pool_md,
 bad_endio_hook_pool:
 	mempool_destroy(pool->mapping_pool);
 bad_mapping_pool:
+	ds_destroy(pool->all_io_ds);
+bad_all_io_ds:
+	ds_destroy(pool->shared_read_ds);
+bad_shared_ds:
 	destroy_workqueue(pool->wq);
 bad_wq:
 	dm_kcopyd_client_destroy(pool->copier);
@@ -3129,10 +3144,6 @@ static int __init dm_thin_init(void)
 
 	r = -ENOMEM;
 
-	_cell_cache = KMEM_CACHE(dm_bio_prison_cell, 0);
-	if (!_cell_cache)
-		goto bad_cell_cache;
-
 	_new_mapping_cache = KMEM_CACHE(dm_thin_new_mapping, 0);
 	if (!_new_mapping_cache)
 		goto bad_new_mapping_cache;
@@ -3146,8 +3157,6 @@ static int __init dm_thin_init(void)
 bad_endio_hook_cache:
 	kmem_cache_destroy(_new_mapping_cache);
 bad_new_mapping_cache:
-	kmem_cache_destroy(_cell_cache);
-bad_cell_cache:
 	dm_unregister_target(&pool_target);
 bad_pool_target:
 	dm_unregister_target(&thin_target);
@@ -3160,7 +3169,6 @@ static void dm_thin_exit(void)
 	dm_unregister_target(&thin_target);
 	dm_unregister_target(&pool_target);
 
-	kmem_cache_destroy(_cell_cache);
 	kmem_cache_destroy(_new_mapping_cache);
 	kmem_cache_destroy(_endio_hook_cache);
 }
-- 
1.7.1

^ permalink raw reply related	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2012-09-25 22:35 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2012-09-25 22:35 [PATCH 1/3] dm bio prison: factor bio prison code out to standalone library Mike Snitzer
2012-09-25 22:35 ` [PATCH 2/3] dm thin: remove old bio prison code that now lives in dm-bio-prison.c Mike Snitzer
2012-09-25 22:35 ` [PATCH 3/3] dm bio prison: add "dm_" prefix to bio prison and deferred set interfaces Mike Snitzer

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