drbd: introduce a bio_set to allocate housekeeping bios from

Don't rely on availability of bios from the global fs_bio_set,
we should use our own bio_set for meta data IO.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

5 files changed, 43 insertions, 4 deletions

diff --git a/drivers/block/drbd/drbd_actlog.c b/drivers/block/drbd/drbd_actlog.c
index 0a35f82f1222..e54e31b02b88 100644
--- a/drivers/block/drbd/drbd_actlog.c
+++ b/drivers/block/drbd/drbd_actlog.c
@@ -115,7 +115,7 @@ static int _drbd_md_sync_page_io(struct drbd_conf *mdev,
                 rw |= REQ_FUA | REQ_FLUSH;
         rw |= REQ_SYNC;
 
-        bio = bio_alloc(GFP_NOIO, 1);
+        bio = bio_alloc_drbd(GFP_NOIO);
         bio->bi_bdev = bdev->md_bdev;
         bio->bi_sector = sector;
         ok = (bio_add_page(bio, page, size, 0) == size);
diff --git a/drivers/block/drbd/drbd_bitmap.c b/drivers/block/drbd/drbd_bitmap.c
index a24eb787a7a1..b5c5ff53cb57 100644
--- a/drivers/block/drbd/drbd_bitmap.c
+++ b/drivers/block/drbd/drbd_bitmap.c
@@ -953,8 +953,7 @@ static void bm_async_io_complete(struct bio *bio, int error)
 
 static void bm_page_io_async(struct bm_aio_ctx *ctx, int page_nr, int rw) __must_hold(local)
 {
-        /* we are process context. we always get a bio */
-        struct bio *bio = bio_alloc(GFP_NOIO, 1);
+        struct bio *bio = bio_alloc_drbd(GFP_NOIO);
         struct drbd_conf *mdev = ctx->mdev;
         struct drbd_bitmap *b = mdev->bitmap;
         struct page *page;
diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 685ed4cca173..02f013a073a7 100644
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -1522,6 +1522,12 @@ extern wait_queue_head_t drbd_pp_wait;
 #define DRBD_MIN_POOL_PAGES     128
 extern mempool_t *drbd_md_io_page_pool;
 
+/* We also need to make sure we get a bio
+ * when we need it for housekeeping purposes */
+extern struct bio_set *drbd_md_io_bio_set;
+/* to allocate from that set */
+extern struct bio *bio_alloc_drbd(gfp_t gfp_mask);
+
 extern rwlock_t global_state_lock;
 
 extern struct drbd_conf *drbd_new_device(unsigned int minor);
diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index c03e87f19e86..bd380b94fd08 100644
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -140,6 +140,7 @@ struct kmem_cache *drbd_al_ext_cache;	/* activity log extents */
 mempool_t *drbd_request_mempool;
 mempool_t *drbd_ee_mempool;
 mempool_t *drbd_md_io_page_pool;
+struct bio_set *drbd_md_io_bio_set;
 
 /* I do not use a standard mempool, because:
    1) I want to hand out the pre-allocated objects first.
@@ -160,6 +161,25 @@ static const struct block_device_operations drbd_ops = {
         .release = drbd_release,
 };
 
+static void bio_destructor_drbd(struct bio *bio)
+{
+        bio_free(bio, drbd_md_io_bio_set);
+}
+
+struct bio *bio_alloc_drbd(gfp_t gfp_mask)
+{
+        struct bio *bio;
+
+        if (!drbd_md_io_bio_set)
+                return bio_alloc(gfp_mask, 1);
+
+        bio = bio_alloc_bioset(gfp_mask, 1, drbd_md_io_bio_set);
+        if (!bio)
+                return NULL;
+        bio->bi_destructor = bio_destructor_drbd;
+        return bio;
+}
+
 #ifdef __CHECKER__
 /* When checking with sparse, and this is an inline function, sparse will
    give tons of false positives. When this is a real functions sparse works.
@@ -3263,6 +3283,8 @@ static void drbd_destroy_mempools(void)
 
         /* D_ASSERT(atomic_read(&drbd_pp_vacant)==0); */
 
+        if (drbd_md_io_bio_set)
+                bioset_free(drbd_md_io_bio_set);
         if (drbd_md_io_page_pool)
                 mempool_destroy(drbd_md_io_page_pool);
         if (drbd_ee_mempool)
@@ -3278,6 +3300,7 @@ static void drbd_destroy_mempools(void)
         if (drbd_al_ext_cache)
                 kmem_cache_destroy(drbd_al_ext_cache);
 
+        drbd_md_io_bio_set   = NULL;
         drbd_md_io_page_pool = NULL;
         drbd_ee_mempool      = NULL;
         drbd_request_mempool = NULL;
@@ -3303,6 +3326,7 @@ static int drbd_create_mempools(void)
         drbd_al_ext_cache    = NULL;
         drbd_pp_pool         = NULL;
         drbd_md_io_page_pool = NULL;
+        drbd_md_io_bio_set   = NULL;
 
         /* caches */
         drbd_request_cache = kmem_cache_create(
@@ -3326,6 +3350,12 @@ static int drbd_create_mempools(void)
                 goto Enomem;
 
         /* mempools */
+#ifdef COMPAT_HAVE_BIOSET_CREATE
+        drbd_md_io_bio_set = bioset_create(DRBD_MIN_POOL_PAGES, 0);
+        if (drbd_md_io_bio_set == NULL)
+                goto Enomem;
+#endif
+
         drbd_md_io_page_pool = mempool_create_page_pool(DRBD_MIN_POOL_PAGES, 0);
         if (drbd_md_io_page_pool == NULL)
                 goto Enomem;
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c
index 017eeb745ed9..247a79aec895 100644
--- a/drivers/block/drbd/drbd_receiver.c
+++ b/drivers/block/drbd/drbd_receiver.c
@@ -1106,7 +1106,11 @@ int drbd_submit_ee(struct drbd_conf *mdev, struct drbd_epoch_entry *e,
         /* In most cases, we will only need one bio.  But in case the lower
          * level restrictions happen to be different at this offset on this
          * side than those of the sending peer, we may need to submit the
-         * request in more than one bio. */
+         * request in more than one bio.
+         *
+         * Plain bio_alloc is good enough here, this is no DRBD internally
+         * generated bio, but a bio allocated on behalf of the peer.
+         */
 next_bio:
         bio = bio_alloc(GFP_NOIO, nr_pages);
         if (!bio) {