X-Git-Url: https://git.kernelconcepts.de/?a=blobdiff_plain;f=drivers%2Fmd%2Fdm-thin.c;h=b9d25026ab84ac55afd5df7d67bfc177219d7def;hb=ac4c3f34a9af63092b3fbfafe34c3e966fbd96c5;hp=4843801173fe11a99519b59dd808e46e02425ee4;hpb=f17a6f78595e52761b7b2dece8c11b04b65f19dd;p=karo-tx-linux.git

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index 4843801173fe..b9d25026ab84 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -11,11 +11,13 @@
 #include <linux/device-mapper.h>
 #include <linux/dm-io.h>
 #include <linux/dm-kcopyd.h>
+#include <linux/log2.h>
 #include <linux/list.h>
 #include <linux/rculist.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/slab.h>
+#include <linux/sort.h>
 #include <linux/rbtree.h>
 
 #define	DM_MSG_PREFIX	"thin"
@@ -25,7 +27,6 @@
  */
 #define ENDIO_HOOK_POOL_SIZE 1024
 #define MAPPING_POOL_SIZE 1024
-#define PRISON_CELLS 1024
 #define COMMIT_PERIOD HZ
 #define NO_SPACE_TIMEOUT_SECS 60
 
@@ -127,6 +128,53 @@ static void build_virtual_key(struct dm_thin_device *td, dm_block_t b,
 
 /*----------------------------------------------------------------*/
 
+#define THROTTLE_THRESHOLD (1 * HZ)
+
+struct throttle {
+	struct rw_semaphore lock;
+	unsigned long threshold;
+	bool throttle_applied;
+};
+
+static void throttle_init(struct throttle *t)
+{
+	init_rwsem(&t->lock);
+	t->throttle_applied = false;
+}
+
+static void throttle_work_start(struct throttle *t)
+{
+	t->threshold = jiffies + THROTTLE_THRESHOLD;
+}
+
+static void throttle_work_update(struct throttle *t)
+{
+	if (!t->throttle_applied && jiffies > t->threshold) {
+		down_write(&t->lock);
+		t->throttle_applied = true;
+	}
+}
+
+static void throttle_work_complete(struct throttle *t)
+{
+	if (t->throttle_applied) {
+		t->throttle_applied = false;
+		up_write(&t->lock);
+	}
+}
+
+static void throttle_lock(struct throttle *t)
+{
+	down_read(&t->lock);
+}
+
+static void throttle_unlock(struct throttle *t)
+{
+	up_read(&t->lock);
+}
+
+/*----------------------------------------------------------------*/
+
 /*
  * A pool device ties together a metadata device and a data device.  It
  * also provides the interface for creating and destroying internal
@@ -155,8 +203,11 @@ struct pool_features {
 
 struct thin_c;
 typedef void (*process_bio_fn)(struct thin_c *tc, struct bio *bio);
+typedef void (*process_cell_fn)(struct thin_c *tc, struct dm_bio_prison_cell *cell);
 typedef void (*process_mapping_fn)(struct dm_thin_new_mapping *m);
 
+#define CELL_SORT_ARRAY_SIZE 8192
+
 struct pool {
 	struct list_head list;
 	struct dm_target *ti;	/* Only set if a pool target is bound */
@@ -176,6 +227,7 @@ struct pool {
 	struct dm_kcopyd_client *copier;
 
 	struct workqueue_struct *wq;
+	struct throttle throttle;
 	struct work_struct worker;
 	struct delayed_work waker;
 	struct delayed_work no_space_timeout;
@@ -198,8 +250,13 @@ struct pool {
 	process_bio_fn process_bio;
 	process_bio_fn process_discard;
 
+	process_cell_fn process_cell;
+	process_cell_fn process_discard_cell;
+
 	process_mapping_fn process_prepared_mapping;
 	process_mapping_fn process_prepared_discard;
+
+	struct dm_bio_prison_cell *cell_sort_array[CELL_SORT_ARRAY_SIZE];
 };
 
 static enum pool_mode get_pool_mode(struct pool *pool);
@@ -234,6 +291,7 @@ struct thin_c {
 	struct dm_thin_device *td;
 	bool requeue_mode:1;
 	spinlock_t lock;
+	struct list_head deferred_cells;
 	struct bio_list deferred_bio_list;
 	struct bio_list retry_on_resume_list;
 	struct rb_root sort_bio_list; /* sorted list of deferred bios */
@@ -290,6 +348,15 @@ static void cell_release(struct pool *pool,
 	dm_bio_prison_free_cell(pool->prison, cell);
 }
 
+static void cell_visit_release(struct pool *pool,
+			       void (*fn)(void *, struct dm_bio_prison_cell *),
+			       void *context,
+			       struct dm_bio_prison_cell *cell)
+{
+	dm_cell_visit_release(pool->prison, fn, context, cell);
+	dm_bio_prison_free_cell(pool->prison, cell);
+}
+
 static void cell_release_no_holder(struct pool *pool,
 				   struct dm_bio_prison_cell *cell,
 				   struct bio_list *bios)
@@ -298,19 +365,6 @@ static void cell_release_no_holder(struct pool *pool,
 	dm_bio_prison_free_cell(pool->prison, cell);
 }
 
-static void cell_defer_no_holder_no_free(struct thin_c *tc,
-					 struct dm_bio_prison_cell *cell)
-{
-	struct pool *pool = tc->pool;
-	unsigned long flags;
-
-	spin_lock_irqsave(&tc->lock, flags);
-	dm_cell_release_no_holder(pool->prison, cell, &tc->deferred_bio_list);
-	spin_unlock_irqrestore(&tc->lock, flags);
-
-	wake_worker(pool);
-}
-
 static void cell_error_with_code(struct pool *pool,
 				 struct dm_bio_prison_cell *cell, int error_code)
 {
@@ -323,6 +377,16 @@ static void cell_error(struct pool *pool, struct dm_bio_prison_cell *cell)
 	cell_error_with_code(pool, cell, -EIO);
 }
 
+static void cell_success(struct pool *pool, struct dm_bio_prison_cell *cell)
+{
+	cell_error_with_code(pool, cell, 0);
+}
+
+static void cell_requeue(struct pool *pool, struct dm_bio_prison_cell *cell)
+{
+	cell_error_with_code(pool, cell, DM_ENDIO_REQUEUE);
+}
+
 /*----------------------------------------------------------------*/
 
 /*
@@ -410,10 +474,28 @@ static void requeue_bio_list(struct thin_c *tc, struct bio_list *master)
 		bio_endio(bio, DM_ENDIO_REQUEUE);
 }
 
+static void requeue_deferred_cells(struct thin_c *tc)
+{
+	struct pool *pool = tc->pool;
+	unsigned long flags;
+	struct list_head cells;
+	struct dm_bio_prison_cell *cell, *tmp;
+
+	INIT_LIST_HEAD(&cells);
+
+	spin_lock_irqsave(&tc->lock, flags);
+	list_splice_init(&tc->deferred_cells, &cells);
+	spin_unlock_irqrestore(&tc->lock, flags);
+
+	list_for_each_entry_safe(cell, tmp, &cells, user_list)
+		cell_requeue(pool, cell);
+}
+
 static void requeue_io(struct thin_c *tc)
 {
 	requeue_bio_list(tc, &tc->deferred_bio_list);
 	requeue_bio_list(tc, &tc->retry_on_resume_list);
+	requeue_deferred_cells(tc);
 }
 
 static void error_thin_retry_list(struct thin_c *tc)
@@ -629,33 +711,75 @@ static void overwrite_endio(struct bio *bio, int err)
  */
 
 /*
- * This sends the bios in the cell back to the deferred_bios list.
+ * This sends the bios in the cell, except the original holder, back
+ * to the deferred_bios list.
  */
-static void cell_defer(struct thin_c *tc, struct dm_bio_prison_cell *cell)
+static void cell_defer_no_holder(struct thin_c *tc, struct dm_bio_prison_cell *cell)
 {
 	struct pool *pool = tc->pool;
 	unsigned long flags;
 
 	spin_lock_irqsave(&tc->lock, flags);
-	cell_release(pool, cell, &tc->deferred_bio_list);
+	cell_release_no_holder(pool, cell, &tc->deferred_bio_list);
 	spin_unlock_irqrestore(&tc->lock, flags);
 
 	wake_worker(pool);
 }
 
-/*
- * Same as cell_defer above, except it omits the original holder of the cell.
- */
-static void cell_defer_no_holder(struct thin_c *tc, struct dm_bio_prison_cell *cell)
+static void thin_defer_bio(struct thin_c *tc, struct bio *bio);
+
+struct remap_info {
+	struct thin_c *tc;
+	struct bio_list defer_bios;
+	struct bio_list issue_bios;
+};
+
+static void __inc_remap_and_issue_cell(void *context,
+				       struct dm_bio_prison_cell *cell)
 {
-	struct pool *pool = tc->pool;
-	unsigned long flags;
+	struct remap_info *info = context;
+	struct bio *bio;
 
-	spin_lock_irqsave(&tc->lock, flags);
-	cell_release_no_holder(pool, cell, &tc->deferred_bio_list);
-	spin_unlock_irqrestore(&tc->lock, flags);
+	while ((bio = bio_list_pop(&cell->bios))) {
+		if (bio->bi_rw & (REQ_DISCARD | REQ_FLUSH | REQ_FUA))
+			bio_list_add(&info->defer_bios, bio);
+		else {
+			inc_all_io_entry(info->tc->pool, bio);
 
-	wake_worker(pool);
+			/*
+			 * We can't issue the bios with the bio prison lock
+			 * held, so we add them to a list to issue on
+			 * return from this function.
+			 */
+			bio_list_add(&info->issue_bios, bio);
+		}
+	}
+}
+
+static void inc_remap_and_issue_cell(struct thin_c *tc,
+				     struct dm_bio_prison_cell *cell,
+				     dm_block_t block)
+{
+	struct bio *bio;
+	struct remap_info info;
+
+	info.tc = tc;
+	bio_list_init(&info.defer_bios);
+	bio_list_init(&info.issue_bios);
+
+	/*
+	 * We have to be careful to inc any bios we're about to issue
+	 * before the cell is released, and avoid a race with new bios
+	 * being added to the cell.
+	 */
+	cell_visit_release(tc->pool, __inc_remap_and_issue_cell,
+			   &info, cell);
+
+	while ((bio = bio_list_pop(&info.defer_bios)))
+		thin_defer_bio(tc, bio);
+
+	while ((bio = bio_list_pop(&info.issue_bios)))
+		remap_and_issue(info.tc, bio, block);
 }
 
 static void process_prepared_mapping_fail(struct dm_thin_new_mapping *m)
@@ -706,10 +830,13 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m)
 	 * the bios in the cell.
 	 */
 	if (bio) {
-		cell_defer_no_holder(tc, m->cell);
+		inc_remap_and_issue_cell(tc, m->cell, m->data_block);
 		bio_endio(bio, 0);
-	} else
-		cell_defer(tc, m->cell);
+	} else {
+		inc_all_io_entry(tc->pool, m->cell->holder);
+		remap_and_issue(tc, m->cell->holder, m->data_block);
+		inc_remap_and_issue_cell(tc, m->cell, m->data_block);
+	}
 
 out:
 	list_del(&m->list);
@@ -842,6 +969,20 @@ static void ll_zero(struct thin_c *tc, struct dm_thin_new_mapping *m,
 	}
 }
 
+static void remap_and_issue_overwrite(struct thin_c *tc, struct bio *bio,
+				      dm_block_t data_block,
+				      struct dm_thin_new_mapping *m)
+{
+	struct pool *pool = tc->pool;
+	struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
+
+	h->overwrite_mapping = m;
+	m->bio = bio;
+	save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);
+	inc_all_io_entry(pool, bio);
+	remap_and_issue(tc, bio, data_block);
+}
+
 /*
  * A partial copy also needs to zero the uncopied region.
  */
@@ -876,15 +1017,9 @@ static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
 	 * If the whole block of data is being overwritten, we can issue the
 	 * bio immediately. Otherwise we use kcopyd to clone the data first.
 	 */
-	if (io_overwrites_block(pool, bio)) {
-		struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
-
-		h->overwrite_mapping = m;
-		m->bio = bio;
-		save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);
-		inc_all_io_entry(pool, bio);
-		remap_and_issue(tc, bio, data_dest);
-	} else {
+	if (io_overwrites_block(pool, bio))
+		remap_and_issue_overwrite(tc, bio, data_dest, m);
+	else {
 		struct dm_io_region from, to;
 
 		from.bdev = origin->bdev;
@@ -953,16 +1088,10 @@ static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
 	if (!pool->pf.zero_new_blocks)
 		process_prepared_mapping(m);
 
-	else if (io_overwrites_block(pool, bio)) {
-		struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
+	else if (io_overwrites_block(pool, bio))
+		remap_and_issue_overwrite(tc, bio, data_block, m);
 
-		h->overwrite_mapping = m;
-		m->bio = bio;
-		save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);
-		inc_all_io_entry(pool, bio);
-		remap_and_issue(tc, bio, data_block);
-
-	} else
+	else
 		ll_zero(tc, m,
 			data_block * pool->sectors_per_block,
 			(data_block + 1) * pool->sectors_per_block);
@@ -1143,20 +1272,21 @@ static void retry_bios_on_resume(struct pool *pool, struct dm_bio_prison_cell *c
 			retry_on_resume(bio);
 }
 
-static void process_discard(struct thin_c *tc, struct bio *bio)
+static void process_discard_cell(struct thin_c *tc, struct dm_bio_prison_cell *cell)
 {
 	int r;
-	unsigned long flags;
+	struct bio *bio = cell->holder;
 	struct pool *pool = tc->pool;
-	struct dm_bio_prison_cell *cell, *cell2;
-	struct dm_cell_key key, key2;
+	struct dm_bio_prison_cell *cell2;
+	struct dm_cell_key key2;
 	dm_block_t block = get_bio_block(tc, bio);
 	struct dm_thin_lookup_result lookup_result;
 	struct dm_thin_new_mapping *m;
 
-	build_virtual_key(tc->td, block, &key);
-	if (bio_detain(tc->pool, &key, bio, &cell))
+	if (tc->requeue_mode) {
+		cell_requeue(pool, cell);
 		return;
+	}
 
 	r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
 	switch (r) {
@@ -1187,12 +1317,9 @@ static void process_discard(struct thin_c *tc, struct bio *bio)
 			m->cell2 = cell2;
 			m->bio = bio;
 
-			if (!dm_deferred_set_add_work(pool->all_io_ds, &m->list)) {
-				spin_lock_irqsave(&pool->lock, flags);
-				list_add_tail(&m->list, &pool->prepared_discards);
-				spin_unlock_irqrestore(&pool->lock, flags);
-				wake_worker(pool);
-			}
+			if (!dm_deferred_set_add_work(pool->all_io_ds, &m->list))
+				pool->process_prepared_discard(m);
+
 		} else {
 			inc_all_io_entry(pool, bio);
 			cell_defer_no_holder(tc, cell);
@@ -1227,6 +1354,19 @@ static void process_discard(struct thin_c *tc, struct bio *bio)
 	}
 }
 
+static void process_discard_bio(struct thin_c *tc, struct bio *bio)
+{
+	struct dm_bio_prison_cell *cell;
+	struct dm_cell_key key;
+	dm_block_t block = get_bio_block(tc, bio);
+
+	build_virtual_key(tc->td, block, &key);
+	if (bio_detain(tc->pool, &key, bio, &cell))
+		return;
+
+	process_discard_cell(tc, cell);
+}
+
 static void break_sharing(struct thin_c *tc, struct bio *bio, dm_block_t block,
 			  struct dm_cell_key *key,
 			  struct dm_thin_lookup_result *lookup_result,
@@ -1255,11 +1395,53 @@ static void break_sharing(struct thin_c *tc, struct bio *bio, dm_block_t block,
 	}
 }
 
+static void __remap_and_issue_shared_cell(void *context,
+					  struct dm_bio_prison_cell *cell)
+{
+	struct remap_info *info = context;
+	struct bio *bio;
+
+	while ((bio = bio_list_pop(&cell->bios))) {
+		if ((bio_data_dir(bio) == WRITE) ||
+		    (bio->bi_rw & (REQ_DISCARD | REQ_FLUSH | REQ_FUA)))
+			bio_list_add(&info->defer_bios, bio);
+		else {
+			struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));;
+
+			h->shared_read_entry = dm_deferred_entry_inc(info->tc->pool->shared_read_ds);
+			inc_all_io_entry(info->tc->pool, bio);
+			bio_list_add(&info->issue_bios, bio);
+		}
+	}
+}
+
+static void remap_and_issue_shared_cell(struct thin_c *tc,
+					struct dm_bio_prison_cell *cell,
+					dm_block_t block)
+{
+	struct bio *bio;
+	struct remap_info info;
+
+	info.tc = tc;
+	bio_list_init(&info.defer_bios);
+	bio_list_init(&info.issue_bios);
+
+	cell_visit_release(tc->pool, __remap_and_issue_shared_cell,
+			   &info, cell);
+
+	while ((bio = bio_list_pop(&info.defer_bios)))
+		thin_defer_bio(tc, bio);
+
+	while ((bio = bio_list_pop(&info.issue_bios)))
+		remap_and_issue(tc, bio, block);
+}
+
 static void process_shared_bio(struct thin_c *tc, struct bio *bio,
 			       dm_block_t block,
-			       struct dm_thin_lookup_result *lookup_result)
+			       struct dm_thin_lookup_result *lookup_result,
+			       struct dm_bio_prison_cell *virt_cell)
 {
-	struct dm_bio_prison_cell *cell;
+	struct dm_bio_prison_cell *data_cell;
 	struct pool *pool = tc->pool;
 	struct dm_cell_key key;
 
@@ -1268,19 +1450,23 @@ static void process_shared_bio(struct thin_c *tc, struct bio *bio,
 	 * of being broken so we have nothing further to do here.
 	 */
 	build_data_key(tc->td, lookup_result->block, &key);
-	if (bio_detain(pool, &key, bio, &cell))
+	if (bio_detain(pool, &key, bio, &data_cell)) {
+		cell_defer_no_holder(tc, virt_cell);
 		return;
+	}
 
-	if (bio_data_dir(bio) == WRITE && bio->bi_iter.bi_size)
-		break_sharing(tc, bio, block, &key, lookup_result, cell);
-	else {
+	if (bio_data_dir(bio) == WRITE && bio->bi_iter.bi_size) {
+		break_sharing(tc, bio, block, &key, lookup_result, data_cell);
+		cell_defer_no_holder(tc, virt_cell);
+	} else {
 		struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
 
 		h->shared_read_entry = dm_deferred_entry_inc(pool->shared_read_ds);
 		inc_all_io_entry(pool, bio);
-		cell_defer_no_holder(tc, cell);
-
 		remap_and_issue(tc, bio, lookup_result->block);
+
+		remap_and_issue_shared_cell(tc, data_cell, lookup_result->block);
+		remap_and_issue_shared_cell(tc, virt_cell, lookup_result->block);
 	}
 }
 
@@ -1333,34 +1519,28 @@ static void provision_block(struct thin_c *tc, struct bio *bio, dm_block_t block
 	}
 }
 
-static void process_bio(struct thin_c *tc, struct bio *bio)
+static void process_cell(struct thin_c *tc, struct dm_bio_prison_cell *cell)
 {
 	int r;
 	struct pool *pool = tc->pool;
+	struct bio *bio = cell->holder;
 	dm_block_t block = get_bio_block(tc, bio);
-	struct dm_bio_prison_cell *cell;
-	struct dm_cell_key key;
 	struct dm_thin_lookup_result lookup_result;
 
-	/*
-	 * If cell is already occupied, then the block is already
-	 * being provisioned so we have nothing further to do here.
-	 */
-	build_virtual_key(tc->td, block, &key);
-	if (bio_detain(pool, &key, bio, &cell))
+	if (tc->requeue_mode) {
+		cell_requeue(pool, cell);
 		return;
+	}
 
 	r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
 	switch (r) {
 	case 0:
-		if (lookup_result.shared) {
-			process_shared_bio(tc, bio, block, &lookup_result);
-			cell_defer_no_holder(tc, cell); /* FIXME: pass this cell into process_shared? */
-		} else {
+		if (lookup_result.shared)
+			process_shared_bio(tc, bio, block, &lookup_result, cell);
+		else {
 			inc_all_io_entry(pool, bio);
-			cell_defer_no_holder(tc, cell);
-
 			remap_and_issue(tc, bio, lookup_result.block);
+			inc_remap_and_issue_cell(tc, cell, lookup_result.block);
 		}
 		break;
 
@@ -1394,7 +1574,26 @@ static void process_bio(struct thin_c *tc, struct bio *bio)
 	}
 }
 
-static void process_bio_read_only(struct thin_c *tc, struct bio *bio)
+static void process_bio(struct thin_c *tc, struct bio *bio)
+{
+	struct pool *pool = tc->pool;
+	dm_block_t block = get_bio_block(tc, bio);
+	struct dm_bio_prison_cell *cell;
+	struct dm_cell_key key;
+
+	/*
+	 * If cell is already occupied, then the block is already
+	 * being provisioned so we have nothing further to do here.
+	 */
+	build_virtual_key(tc->td, block, &key);
+	if (bio_detain(pool, &key, bio, &cell))
+		return;
+
+	process_cell(tc, cell);
+}
+
+static void __process_bio_read_only(struct thin_c *tc, struct bio *bio,
+				    struct dm_bio_prison_cell *cell)
 {
 	int r;
 	int rw = bio_data_dir(bio);
@@ -1404,15 +1603,21 @@ static void process_bio_read_only(struct thin_c *tc, struct bio *bio)
 	r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
 	switch (r) {
 	case 0:
-		if (lookup_result.shared && (rw == WRITE) && bio->bi_iter.bi_size)
+		if (lookup_result.shared && (rw == WRITE) && bio->bi_iter.bi_size) {
 			handle_unserviceable_bio(tc->pool, bio);
-		else {
+			if (cell)
+				cell_defer_no_holder(tc, cell);
+		} else {
 			inc_all_io_entry(tc->pool, bio);
 			remap_and_issue(tc, bio, lookup_result.block);
+			if (cell)
+				inc_remap_and_issue_cell(tc, cell, lookup_result.block);
 		}
 		break;
 
 	case -ENODATA:
+		if (cell)
+			cell_defer_no_holder(tc, cell);
 		if (rw != READ) {
 			handle_unserviceable_bio(tc->pool, bio);
 			break;
@@ -1431,11 +1636,23 @@ static void process_bio_read_only(struct thin_c *tc, struct bio *bio)
 	default:
 		DMERR_LIMIT("%s: dm_thin_find_block() failed: error = %d",
 			    __func__, r);
+		if (cell)
+			cell_defer_no_holder(tc, cell);
 		bio_io_error(bio);
 		break;
 	}
 }
 
+static void process_bio_read_only(struct thin_c *tc, struct bio *bio)
+{
+	__process_bio_read_only(tc, bio, NULL);
+}
+
+static void process_cell_read_only(struct thin_c *tc, struct dm_bio_prison_cell *cell)
+{
+	__process_bio_read_only(tc, cell->holder, cell);
+}
+
 static void process_bio_success(struct thin_c *tc, struct bio *bio)
 {
 	bio_endio(bio, 0);
@@ -1446,6 +1663,16 @@ static void process_bio_fail(struct thin_c *tc, struct bio *bio)
 	bio_io_error(bio);
 }
 
+static void process_cell_success(struct thin_c *tc, struct dm_bio_prison_cell *cell)
+{
+	cell_success(tc->pool, cell);
+}
+
+static void process_cell_fail(struct thin_c *tc, struct dm_bio_prison_cell *cell)
+{
+	cell_error(tc->pool, cell);
+}
+
 /*
  * FIXME: should we also commit due to size of transaction, measured in
  * metadata blocks?
@@ -1527,6 +1754,7 @@ static void process_thin_deferred_bios(struct thin_c *tc)
 	struct bio *bio;
 	struct bio_list bios;
 	struct blk_plug plug;
+	unsigned count = 0;
 
 	if (tc->requeue_mode) {
 		requeue_bio_list(tc, &tc->deferred_bio_list);
@@ -1568,10 +1796,97 @@ static void process_thin_deferred_bios(struct thin_c *tc)
 			pool->process_discard(tc, bio);
 		else
 			pool->process_bio(tc, bio);
+
+		if ((count++ & 127) == 0) {
+			throttle_work_update(&pool->throttle);
+			dm_pool_issue_prefetches(pool->pmd);
+		}
 	}
 	blk_finish_plug(&plug);
 }
 
+static int cmp_cells(const void *lhs, const void *rhs)
+{
+	struct dm_bio_prison_cell *lhs_cell = *((struct dm_bio_prison_cell **) lhs);
+	struct dm_bio_prison_cell *rhs_cell = *((struct dm_bio_prison_cell **) rhs);
+
+	BUG_ON(!lhs_cell->holder);
+	BUG_ON(!rhs_cell->holder);
+
+	if (lhs_cell->holder->bi_iter.bi_sector < rhs_cell->holder->bi_iter.bi_sector)
+		return -1;
+
+	if (lhs_cell->holder->bi_iter.bi_sector > rhs_cell->holder->bi_iter.bi_sector)
+		return 1;
+
+	return 0;
+}
+
+static unsigned sort_cells(struct pool *pool, struct list_head *cells)
+{
+	unsigned count = 0;
+	struct dm_bio_prison_cell *cell, *tmp;
+
+	list_for_each_entry_safe(cell, tmp, cells, user_list) {
+		if (count >= CELL_SORT_ARRAY_SIZE)
+			break;
+
+		pool->cell_sort_array[count++] = cell;
+		list_del(&cell->user_list);
+	}
+
+	sort(pool->cell_sort_array, count, sizeof(cell), cmp_cells, NULL);
+
+	return count;
+}
+
+static void process_thin_deferred_cells(struct thin_c *tc)
+{
+	struct pool *pool = tc->pool;
+	unsigned long flags;
+	struct list_head cells;
+	struct dm_bio_prison_cell *cell;
+	unsigned i, j, count;
+
+	INIT_LIST_HEAD(&cells);
+
+	spin_lock_irqsave(&tc->lock, flags);
+	list_splice_init(&tc->deferred_cells, &cells);
+	spin_unlock_irqrestore(&tc->lock, flags);
+
+	if (list_empty(&cells))
+		return;
+
+	do {
+		count = sort_cells(tc->pool, &cells);
+
+		for (i = 0; i < count; i++) {
+			cell = pool->cell_sort_array[i];
+			BUG_ON(!cell->holder);
+
+			/*
+			 * If we've got no free new_mapping structs, and processing
+			 * this bio might require one, we pause until there are some
+			 * prepared mappings to process.
+			 */
+			if (ensure_next_mapping(pool)) {
+				for (j = i; j < count; j++)
+					list_add(&pool->cell_sort_array[j]->user_list, &cells);
+
+				spin_lock_irqsave(&tc->lock, flags);
+				list_splice(&cells, &tc->deferred_cells);
+				spin_unlock_irqrestore(&tc->lock, flags);
+				return;
+			}
+
+			if (cell->holder->bi_rw & REQ_DISCARD)
+				pool->process_discard_cell(tc, cell);
+			else
+				pool->process_cell(tc, cell);
+		}
+	} while (!list_empty(&cells));
+}
+
 static void thin_get(struct thin_c *tc);
 static void thin_put(struct thin_c *tc);
 
@@ -1620,6 +1935,7 @@ static void process_deferred_bios(struct pool *pool)
 
 	tc = get_first_thin(pool);
 	while (tc) {
+		process_thin_deferred_cells(tc);
 		process_thin_deferred_bios(tc);
 		tc = get_next_thin(pool, tc);
 	}
@@ -1653,9 +1969,15 @@ static void do_worker(struct work_struct *ws)
 {
 	struct pool *pool = container_of(ws, struct pool, worker);
 
+	throttle_work_start(&pool->throttle);
+	dm_pool_issue_prefetches(pool->pmd);
+	throttle_work_update(&pool->throttle);
 	process_prepared(pool, &pool->prepared_mappings, &pool->process_prepared_mapping);
+	throttle_work_update(&pool->throttle);
 	process_prepared(pool, &pool->prepared_discards, &pool->process_prepared_discard);
+	throttle_work_update(&pool->throttle);
 	process_deferred_bios(pool);
+	throttle_work_complete(&pool->throttle);
 }
 
 /*
@@ -1792,6 +2114,8 @@ static void set_pool_mode(struct pool *pool, enum pool_mode new_mode)
 		dm_pool_metadata_read_only(pool->pmd);
 		pool->process_bio = process_bio_fail;
 		pool->process_discard = process_bio_fail;
+		pool->process_cell = process_cell_fail;
+		pool->process_discard_cell = process_cell_fail;
 		pool->process_prepared_mapping = process_prepared_mapping_fail;
 		pool->process_prepared_discard = process_prepared_discard_fail;
 
@@ -1804,6 +2128,8 @@ static void set_pool_mode(struct pool *pool, enum pool_mode new_mode)
 		dm_pool_metadata_read_only(pool->pmd);
 		pool->process_bio = process_bio_read_only;
 		pool->process_discard = process_bio_success;
+		pool->process_cell = process_cell_read_only;
+		pool->process_discard_cell = process_cell_success;
 		pool->process_prepared_mapping = process_prepared_mapping_fail;
 		pool->process_prepared_discard = process_prepared_discard_passdown;
 
@@ -1822,7 +2148,9 @@ static void set_pool_mode(struct pool *pool, enum pool_mode new_mode)
 		if (old_mode != new_mode)
 			notify_of_pool_mode_change(pool, "out-of-data-space");
 		pool->process_bio = process_bio_read_only;
-		pool->process_discard = process_discard;
+		pool->process_discard = process_discard_bio;
+		pool->process_cell = process_cell_read_only;
+		pool->process_discard_cell = process_discard_cell;
 		pool->process_prepared_mapping = process_prepared_mapping;
 		pool->process_prepared_discard = process_prepared_discard_passdown;
 
@@ -1835,7 +2163,9 @@ static void set_pool_mode(struct pool *pool, enum pool_mode new_mode)
 			notify_of_pool_mode_change(pool, "write");
 		dm_pool_metadata_read_write(pool->pmd);
 		pool->process_bio = process_bio;
-		pool->process_discard = process_discard;
+		pool->process_discard = process_discard_bio;
+		pool->process_cell = process_cell;
+		pool->process_discard_cell = process_discard_cell;
 		pool->process_prepared_mapping = process_prepared_mapping;
 		pool->process_prepared_discard = process_prepared_discard;
 		break;
@@ -1895,6 +2225,29 @@ static void thin_defer_bio(struct thin_c *tc, struct bio *bio)
 	wake_worker(pool);
 }
 
+static void thin_defer_bio_with_throttle(struct thin_c *tc, struct bio *bio)
+{
+	struct pool *pool = tc->pool;
+
+	throttle_lock(&pool->throttle);
+	thin_defer_bio(tc, bio);
+	throttle_unlock(&pool->throttle);
+}
+
+static void thin_defer_cell(struct thin_c *tc, struct dm_bio_prison_cell *cell)
+{
+	unsigned long flags;
+	struct pool *pool = tc->pool;
+
+	throttle_lock(&pool->throttle);
+	spin_lock_irqsave(&tc->lock, flags);
+	list_add_tail(&cell->user_list, &tc->deferred_cells);
+	spin_unlock_irqrestore(&tc->lock, flags);
+	throttle_unlock(&pool->throttle);
+
+	wake_worker(pool);
+}
+
 static void thin_hook_bio(struct thin_c *tc, struct bio *bio)
 {
 	struct dm_thin_endio_hook *h = dm_per_bio_data(bio, sizeof(struct dm_thin_endio_hook));
@@ -1915,8 +2268,7 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
 	dm_block_t block = get_bio_block(tc, bio);
 	struct dm_thin_device *td = tc->td;
 	struct dm_thin_lookup_result result;
-	struct dm_bio_prison_cell cell1, cell2;
-	struct dm_bio_prison_cell *cell_result;
+	struct dm_bio_prison_cell *virt_cell, *data_cell;
 	struct dm_cell_key key;
 
 	thin_hook_bio(tc, bio);
@@ -1932,10 +2284,18 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
 	}
 
 	if (bio->bi_rw & (REQ_DISCARD | REQ_FLUSH | REQ_FUA)) {
-		thin_defer_bio(tc, bio);
+		thin_defer_bio_with_throttle(tc, bio);
 		return DM_MAPIO_SUBMITTED;
 	}
 
+	/*
+	 * We must hold the virtual cell before doing the lookup, otherwise
+	 * there's a race with discard.
+	 */
+	build_virtual_key(tc->td, block, &key);
+	if (bio_detain(tc->pool, &key, bio, &virt_cell))
+		return DM_MAPIO_SUBMITTED;
+
 	r = dm_thin_find_block(td, block, 0, &result);
 
 	/*
@@ -1958,23 +2318,19 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
 			 * More distant ancestors are irrelevant. The
 			 * shared flag will be set in their case.
 			 */
-			thin_defer_bio(tc, bio);
+			thin_defer_cell(tc, virt_cell);
 			return DM_MAPIO_SUBMITTED;
 		}
 
-		build_virtual_key(tc->td, block, &key);
-		if (dm_bio_detain(tc->pool->prison, &key, bio, &cell1, &cell_result))
-			return DM_MAPIO_SUBMITTED;
-
 		build_data_key(tc->td, result.block, &key);
-		if (dm_bio_detain(tc->pool->prison, &key, bio, &cell2, &cell_result)) {
-			cell_defer_no_holder_no_free(tc, &cell1);
+		if (bio_detain(tc->pool, &key, bio, &data_cell)) {
+			cell_defer_no_holder(tc, virt_cell);
 			return DM_MAPIO_SUBMITTED;
 		}
 
 		inc_all_io_entry(tc->pool, bio);
-		cell_defer_no_holder_no_free(tc, &cell2);
-		cell_defer_no_holder_no_free(tc, &cell1);
+		cell_defer_no_holder(tc, data_cell);
+		cell_defer_no_holder(tc, virt_cell);
 
 		remap(tc, bio, result.block);
 		return DM_MAPIO_REMAPPED;
@@ -1986,16 +2342,13 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
 			 * of doing so.
 			 */
 			handle_unserviceable_bio(tc->pool, bio);
+			cell_defer_no_holder(tc, virt_cell);
 			return DM_MAPIO_SUBMITTED;
 		}
 		/* fall through */
 
 	case -EWOULDBLOCK:
-		/*
-		 * In future, the failed dm_thin_find_block above could
-		 * provide the hint to load the metadata into cache.
-		 */
-		thin_defer_bio(tc, bio);
+		thin_defer_cell(tc, virt_cell);
 		return DM_MAPIO_SUBMITTED;
 
 	default:
@@ -2005,6 +2358,7 @@ static int thin_bio_map(struct dm_target *ti, struct bio *bio)
 		 * pool is switched to fail-io mode.
 		 */
 		bio_io_error(bio);
+		cell_defer_no_holder(tc, virt_cell);
 		return DM_MAPIO_SUBMITTED;
 	}
 }
@@ -2185,7 +2539,7 @@ static struct pool *pool_create(struct mapped_device *pool_md,
 		pool->sectors_per_block_shift = __ffs(block_size);
 	pool->low_water_blocks = 0;
 	pool_features_init(&pool->pf);
-	pool->prison = dm_bio_prison_create(PRISON_CELLS);
+	pool->prison = dm_bio_prison_create();
 	if (!pool->prison) {
 		*error = "Error creating pool's bio prison";
 		err_p = ERR_PTR(-ENOMEM);
@@ -2211,6 +2565,7 @@ static struct pool *pool_create(struct mapped_device *pool_md,
 		goto bad_wq;
 	}
 
+	throttle_init(&pool->throttle);
 	INIT_WORK(&pool->worker, do_worker);
 	INIT_DELAYED_WORK(&pool->waker, do_waker);
 	INIT_DELAYED_WORK(&pool->no_space_timeout, do_no_space_timeout);
@@ -3169,15 +3524,42 @@ static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
 {
 	struct pool_c *pt = ti->private;
 	struct pool *pool = pt->pool;
-	uint64_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
+	sector_t io_opt_sectors = limits->io_opt >> SECTOR_SHIFT;
+
+	/*
+	 * Adjust max_sectors_kb to highest possible power-of-2
+	 * factor of pool->sectors_per_block.
+	 */
+	if (limits->max_hw_sectors & (limits->max_hw_sectors - 1))
+		limits->max_sectors = rounddown_pow_of_two(limits->max_hw_sectors);
+	else
+		limits->max_sectors = limits->max_hw_sectors;
+
+	if (limits->max_sectors < pool->sectors_per_block) {
+		while (!is_factor(pool->sectors_per_block, limits->max_sectors)) {
+			if ((limits->max_sectors & (limits->max_sectors - 1)) == 0)
+				limits->max_sectors--;
+			limits->max_sectors = rounddown_pow_of_two(limits->max_sectors);
+		}
+	} else if (block_size_is_power_of_two(pool)) {
+		/* max_sectors_kb is >= power-of-2 thinp blocksize */
+		while (!is_factor(limits->max_sectors, pool->sectors_per_block)) {
+			if ((limits->max_sectors & (limits->max_sectors - 1)) == 0)
+				limits->max_sectors--;
+			limits->max_sectors = rounddown_pow_of_two(limits->max_sectors);
+		}
+	}
 
 	/*
 	 * If the system-determined stacked limits are compatible with the
 	 * pool's blocksize (io_opt is a factor) do not override them.
 	 */
 	if (io_opt_sectors < pool->sectors_per_block ||
-	    do_div(io_opt_sectors, pool->sectors_per_block)) {
-		blk_limits_io_min(limits, pool->sectors_per_block << SECTOR_SHIFT);
+	    !is_factor(io_opt_sectors, pool->sectors_per_block)) {
+		if (is_factor(pool->sectors_per_block, limits->max_sectors))
+			blk_limits_io_min(limits, limits->max_sectors << SECTOR_SHIFT);
+		else
+			blk_limits_io_min(limits, pool->sectors_per_block << SECTOR_SHIFT);
 		blk_limits_io_opt(limits, pool->sectors_per_block << SECTOR_SHIFT);
 	}
 
@@ -3206,7 +3588,7 @@ static struct target_type pool_target = {
 	.name = "thin-pool",
 	.features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE |
 		    DM_TARGET_IMMUTABLE,
-	.version = {1, 13, 0},
+	.version = {1, 14, 0},
 	.module = THIS_MODULE,
 	.ctr = pool_ctr,
 	.dtr = pool_dtr,
@@ -3295,6 +3677,7 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
 		goto out_unlock;
 	}
 	spin_lock_init(&tc->lock);
+	INIT_LIST_HEAD(&tc->deferred_cells);
 	bio_list_init(&tc->deferred_bio_list);
 	bio_list_init(&tc->retry_on_resume_list);
 	tc->sort_bio_list = RB_ROOT;
@@ -3533,6 +3916,21 @@ err:
 	DMEMIT("Error");
 }
 
+static int thin_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
+		      struct bio_vec *biovec, int max_size)
+{
+	struct thin_c *tc = ti->private;
+	struct request_queue *q = bdev_get_queue(tc->pool_dev->bdev);
+
+	if (!q->merge_bvec_fn)
+		return max_size;
+
+	bvm->bi_bdev = tc->pool_dev->bdev;
+	bvm->bi_sector = dm_target_offset(ti, bvm->bi_sector);
+
+	return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
+}
+
 static int thin_iterate_devices(struct dm_target *ti,
 				iterate_devices_callout_fn fn, void *data)
 {
@@ -3557,7 +3955,7 @@ static int thin_iterate_devices(struct dm_target *ti,
 
 static struct target_type thin_target = {
 	.name = "thin",
-	.version = {1, 13, 0},
+	.version = {1, 14, 0},
 	.module	= THIS_MODULE,
 	.ctr = thin_ctr,
 	.dtr = thin_dtr,
@@ -3567,6 +3965,7 @@ static struct target_type thin_target = {
 	.presuspend = thin_presuspend,
 	.postsuspend = thin_postsuspend,
 	.status = thin_status,
+	.merge = thin_merge,
 	.iterate_devices = thin_iterate_devices,
 };