8 files changed, 30 insertions, 10 deletions

diff --git a/block/bio.c b/block/bio.c
index 84b313bd3ce8..2bd064906e06 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -363,6 +363,8 @@ static void punt_bios_to_rescuer(struct bio_set *bs)
         struct bio_list punt, nopunt;
         struct bio *bio;
 
+        if (WARN_ON_ONCE(!bs->rescue_workqueue))
+                return;
         /*
          * In order to guarantee forward progress we must punt only bios that
          * were allocated from this bio_set; otherwise, if there was a bio on
@@ -474,7 +476,8 @@ struct bio *bio_alloc_bioset(gfp_t gfp_mask, unsigned int nr_iovecs,
 
                 if (current->bio_list &&
                     (!bio_list_empty(&current->bio_list[0]) ||
-                     !bio_list_empty(&current->bio_list[1])))
+                     !bio_list_empty(&current->bio_list[1])) &&
+                    bs->rescue_workqueue)
                         gfp_mask &= ~__GFP_DIRECT_RECLAIM;
 
                 p = mempool_alloc(bs->bio_pool, gfp_mask);
@@ -1925,7 +1928,8 @@ EXPORT_SYMBOL(bioset_free);
  * bioset_create  - Create a bio_set
  * @pool_size:  Number of bio and bio_vecs to cache in the mempool
  * @front_pad:  Number of bytes to allocate in front of the returned bio
- * @flags:      Flags to modify behavior, currently only %BIOSET_NEED_BVECS
+ * @flags:      Flags to modify behavior, currently %BIOSET_NEED_BVECS
+ *              and %BIOSET_NEED_RESCUER
  *
  * Description:
  *    Set up a bio_set to be used with @bio_alloc_bioset. Allows the caller
@@ -1936,6 +1940,8 @@ EXPORT_SYMBOL(bioset_free);
  *    or things will break badly.
  *    If %BIOSET_NEED_BVECS is set in @flags, a separate pool will be allocated
  *    for allocating iovecs.  This pool is not needed e.g. for bio_clone_fast().
+ *    If %BIOSET_NEED_RESCUER is set, a workqueue is created which can be used to
+ *    dispatch queued requests when the mempool runs out of space.
  *
  */
 struct bio_set *bioset_create(unsigned int pool_size,
@@ -1971,6 +1977,9 @@ struct bio_set *bioset_create(unsigned int pool_size,
                         goto bad;
         }
 
+        if (!(flags & BIOSET_NEED_RESCUER))
+                return bs;
+
         bs->rescue_workqueue = alloc_workqueue("bioset", WQ_MEM_RECLAIM, 0);
         if (!bs->rescue_workqueue)
                 goto bad;
diff --git a/block/blk-core.c b/block/blk-core.c
index 62cf92550512..9bd10c46a538 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -790,7 +790,8 @@ struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
         if (q->id < 0)
                 goto fail_q;
 
-        q->bio_split = bioset_create(BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
+        q->bio_split = bioset_create(BIO_POOL_SIZE, 0, (BIOSET_NEED_BVECS |
+                                                        BIOSET_NEED_RESCUER));
         if (!q->bio_split)
                 goto fail_id;
 
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index b395fe391171..bdf51b6977cf 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -2165,7 +2165,9 @@ static int drbd_create_mempools(void)
                 goto Enomem;
 
         /* mempools */
-        drbd_md_io_bio_set = bioset_create(DRBD_MIN_POOL_PAGES, 0, BIOSET_NEED_BVECS);
+        drbd_md_io_bio_set = bioset_create(DRBD_MIN_POOL_PAGES, 0,
+                                           BIOSET_NEED_BVECS |
+                                           BIOSET_NEED_RESCUER);
         if (drbd_md_io_bio_set == NULL)
                 goto Enomem;
 
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index abd6e825b39b..8352fad765f6 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -782,7 +782,9 @@ static int bcache_device_init(struct bcache_device *d, unsigned block_size,
 
         minor *= BCACHE_MINORS;
 
-        if (!(d->bio_split = bioset_create(4, offsetof(struct bbio, bio), BIOSET_NEED_BVECS)) ||
+        if (!(d->bio_split = bioset_create(4, offsetof(struct bbio, bio),
+                                           BIOSET_NEED_BVECS |
+                                           BIOSET_NEED_RESCUER)) ||
             !(d->disk = alloc_disk(BCACHE_MINORS))) {
                 ida_simple_remove(&bcache_minor, minor);
                 return -ENOMEM;
@@ -1516,7 +1518,9 @@ struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)
                                 sizeof(struct bbio) + sizeof(struct bio_vec) *
                                 bucket_pages(c))) ||
             !(c->fill_iter = mempool_create_kmalloc_pool(1, iter_size)) ||
-            !(c->bio_split = bioset_create(4, offsetof(struct bbio, bio), BIOSET_NEED_BVECS)) ||
+            !(c->bio_split = bioset_create(4, offsetof(struct bbio, bio),
+                                           BIOSET_NEED_BVECS |
+                                           BIOSET_NEED_RESCUER)) ||
             !(c->uuids = alloc_bucket_pages(GFP_KERNEL, c)) ||
             !(c->moving_gc_wq = alloc_workqueue("bcache_gc",
                                                 WQ_MEM_RECLAIM, 0)) ||
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index 237ff8e9752a..9e1b72e8f7ef 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -2677,7 +2677,8 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
                 goto bad;
         }
 
-        cc->bs = bioset_create(MIN_IOS, 0, BIOSET_NEED_BVECS);
+        cc->bs = bioset_create(MIN_IOS, 0, (BIOSET_NEED_BVECS |
+                                            BIOSET_NEED_RESCUER));
         if (!cc->bs) {
                 ti->error = "Cannot allocate crypt bioset";
                 goto bad;
diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index 5c4121024d92..81248a8a8b57 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -58,7 +58,8 @@ struct dm_io_client *dm_io_client_create(void)
         if (!client->pool)
                 goto bad;
 
-        client->bios = bioset_create(min_ios, 0, BIOSET_NEED_BVECS);
+        client->bios = bioset_create(min_ios, 0, (BIOSET_NEED_BVECS |
+                                                  BIOSET_NEED_RESCUER));
         if (!client->bios)
                 goto bad;
 
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 3394a311de3d..fbd06b9f9467 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1036,7 +1036,8 @@ static void flush_current_bio_list(struct blk_plug_cb *cb, bool from_schedule)
 
                 while ((bio = bio_list_pop(&list))) {
                         struct bio_set *bs = bio->bi_pool;
-                        if (unlikely(!bs) || bs == fs_bio_set) {
+                        if (unlikely(!bs) || bs == fs_bio_set ||
+                            !bs->rescue_workqueue) {
                                 bio_list_add(&current->bio_list[i], bio);
                                 continue;
                         }
@@ -2660,7 +2661,7 @@ struct dm_md_mempools *dm_alloc_md_mempools(struct mapped_device *md, enum dm_qu
                 BUG();
         }
 
-        pools->bs = bioset_create(pool_size, front_pad, 0);
+        pools->bs = bioset_create(pool_size, front_pad, BIOSET_NEED_RESCUER);
         if (!pools->bs)
                 goto out;
 
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 985dc645637e..32c786baa10a 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -376,6 +376,7 @@ static inline struct bio *bio_next_split(struct bio *bio, int sectors,
 extern struct bio_set *bioset_create(unsigned int, unsigned int, int flags);
 enum {
         BIOSET_NEED_BVECS = BIT(0),
+        BIOSET_NEED_RESCUER = BIT(1),
 };
 extern void bioset_free(struct bio_set *);
 extern mempool_t *biovec_create_pool(int pool_entries);