1 files changed, 50 insertions, 5 deletions

diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c
index ca8af21bf644..e83b63608262 100644
--- a/drivers/md/dm-thin.c
+++ b/drivers/md/dm-thin.c
@@ -257,6 +257,7 @@ struct pool {
 
 	spinlock_t lock;
 	struct bio_list deferred_flush_bios;
+	struct bio_list deferred_flush_completions;
 	struct list_head prepared_mappings;
 	struct list_head prepared_discards;
 	struct list_head prepared_discards_pt2;
@@ -956,6 +957,39 @@ static void process_prepared_mapping_fail(struct dm_thin_new_mapping *m)
 	mempool_free(m, &m->tc->pool->mapping_pool);
 }
 
+static void complete_overwrite_bio(struct thin_c *tc, struct bio *bio)
+{
+	struct pool *pool = tc->pool;
+	unsigned long flags;
+
+	/*
+	 * If the bio has the REQ_FUA flag set we must commit the metadata
+	 * before signaling its completion.
+	 */
+	if (!bio_triggers_commit(tc, bio)) {
+		bio_endio(bio);
+		return;
+	}
+
+	/*
+	 * Complete bio with an error if earlier I/O caused changes to the
+	 * metadata that can't be committed, e.g, due to I/O errors on the
+	 * metadata device.
+	 */
+	if (dm_thin_aborted_changes(tc->td)) {
+		bio_io_error(bio);
+		return;
+	}
+
+	/*
+	 * Batch together any bios that trigger commits and then issue a
+	 * single commit for them in process_deferred_bios().
+	 */
+	spin_lock_irqsave(&pool->lock, flags);
+	bio_list_add(&pool->deferred_flush_completions, bio);
+	spin_unlock_irqrestore(&pool->lock, flags);
+}
+
 static void process_prepared_mapping(struct dm_thin_new_mapping *m)
 {
 	struct thin_c *tc = m->tc;
@@ -988,7 +1022,7 @@ static void process_prepared_mapping(struct dm_thin_new_mapping *m)
 	 */
 	if (bio) {
 		inc_remap_and_issue_cell(tc, m->cell, m->data_block);
-		bio_endio(bio);
+		complete_overwrite_bio(tc, bio);
 	} else {
 		inc_all_io_entry(tc->pool, m->cell->holder);
 		remap_and_issue(tc, m->cell->holder, m->data_block);
@@ -2317,7 +2351,7 @@ static void process_deferred_bios(struct pool *pool)
 {
 	unsigned long flags;
 	struct bio *bio;
-	struct bio_list bios;
+	struct bio_list bios, bio_completions;
 	struct thin_c *tc;
 
 	tc = get_first_thin(pool);
@@ -2328,26 +2362,36 @@ static void process_deferred_bios(struct pool *pool)
 	}
 
 	/*
-	 * If there are any deferred flush bios, we must commit
-	 * the metadata before issuing them.
+	 * If there are any deferred flush bios, we must commit the metadata
+	 * before issuing them or signaling their completion.
 	 */
 	bio_list_init(&bios);
+	bio_list_init(&bio_completions);
+
 	spin_lock_irqsave(&pool->lock, flags);
 	bio_list_merge(&bios, &pool->deferred_flush_bios);
 	bio_list_init(&pool->deferred_flush_bios);
+
+	bio_list_merge(&bio_completions, &pool->deferred_flush_completions);
+	bio_list_init(&pool->deferred_flush_completions);
 	spin_unlock_irqrestore(&pool->lock, flags);
 
-	if (bio_list_empty(&bios) &&
+	if (bio_list_empty(&bios) && bio_list_empty(&bio_completions) &&
 	    !(dm_pool_changed_this_transaction(pool->pmd) && need_commit_due_to_time(pool)))
 		return;
 
 	if (commit(pool)) {
+		bio_list_merge(&bios, &bio_completions);
+
 		while ((bio = bio_list_pop(&bios)))
 			bio_io_error(bio);
 		return;
 	}
 	pool->last_commit_jiffies = jiffies;
 
+	while ((bio = bio_list_pop(&bio_completions)))
+		bio_endio(bio);
+
 	while ((bio = bio_list_pop(&bios)))
 		generic_make_request(bio);
 }
@@ -2954,6 +2998,7 @@ static struct pool *pool_create(struct mapped_device *pool_md,
 	INIT_DELAYED_WORK(&pool->no_space_timeout, do_no_space_timeout);
 	spin_lock_init(&pool->lock);
 	bio_list_init(&pool->deferred_flush_bios);
+	bio_list_init(&pool->deferred_flush_completions);
 	INIT_LIST_HEAD(&pool->prepared_mappings);
 	INIT_LIST_HEAD(&pool->prepared_discards);
 	INIT_LIST_HEAD(&pool->prepared_discards_pt2);