drbd: use bio_clone_fast() instead of bio_clone()

drbd does not modify the bi_io_vec of the cloned bio,
so there is no need to clone that part.  So bio_clone_fast()
is the better choice.
For bio_clone_fast() we need to specify a bio_set.
We could use fs_bio_set, which bio_clone() uses, or
drbd_md_io_bio_set, which drbd uses for metadata, but it is
generally best to avoid sharing bio_sets unless you can
be certain that there are no interdependencies.

So create a new bio_set, drbd_io_bio_set, and use bio_clone_fast().

Also remove a "XXX cannot fail ???" comment because it definitely
cannot fail - bio_clone_fast() doesn't fail if the GFP flags allow for
sleeping.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/drivers/block/drbd/drbd_int.h b/drivers/block/drbd/drbd_int.h
index 76761b4ca13ebd24845d144d72623498df58dc5e..d17b6e6393c785fbaafd1b6c564aecda1b594d46 100644 (file)
--- a/drivers/block/drbd/drbd_int.h
+++ b/drivers/block/drbd/drbd_int.h
@@ -1441,6 +1441,9 @@ extern struct bio_set *drbd_md_io_bio_set;
 /* to allocate from that set */
 extern struct bio *bio_alloc_drbd(gfp_t gfp_mask);
 
+/* And a bio_set for cloning */
+extern struct bio_set *drbd_io_bio_set;
+
 extern struct mutex resources_mutex;
 
 extern int conn_lowest_minor(struct drbd_connection *connection);

diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
index bdf51b6977cf58efe82aa19c4de73cfa92bb35ab..90680034ef57f94d56d4a4fa533cc3be9e0cd596 100644 (file)
--- a/drivers/block/drbd/drbd_main.c
+++ b/drivers/block/drbd/drbd_main.c
@@ -128,6 +128,7 @@ 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;
+struct bio_set *drbd_io_bio_set;
 
 /* I do not use a standard mempool, because:
    1) I want to hand out the pre-allocated objects first.
@@ -2098,6 +2099,8 @@ static void drbd_destroy_mempools(void)
 
        /* D_ASSERT(device, atomic_read(&drbd_pp_vacant)==0); */
 
+       if (drbd_io_bio_set)
+               bioset_free(drbd_io_bio_set);
        if (drbd_md_io_bio_set)
                bioset_free(drbd_md_io_bio_set);
        if (drbd_md_io_page_pool)
@@ -2115,6 +2118,7 @@ static void drbd_destroy_mempools(void)
        if (drbd_al_ext_cache)
                kmem_cache_destroy(drbd_al_ext_cache);
 
+       drbd_io_bio_set      = NULL;
        drbd_md_io_bio_set   = NULL;
        drbd_md_io_page_pool = NULL;
        drbd_ee_mempool      = NULL;
@@ -2142,6 +2146,7 @@ static int drbd_create_mempools(void)
        drbd_pp_pool         = NULL;
        drbd_md_io_page_pool = NULL;
        drbd_md_io_bio_set   = NULL;
+       drbd_io_bio_set      = NULL;
 
        /* caches */
        drbd_request_cache = kmem_cache_create(
@@ -2165,6 +2170,10 @@ static int drbd_create_mempools(void)
                goto Enomem;
 
        /* mempools */
+       drbd_io_bio_set = bioset_create(BIO_POOL_SIZE, 0, BIOSET_NEED_RESCUER);
+       if (drbd_io_bio_set == NULL)
+               goto Enomem;
+
        drbd_md_io_bio_set = bioset_create(DRBD_MIN_POOL_PAGES, 0,
                                           BIOSET_NEED_BVECS |
                                           BIOSET_NEED_RESCUER);

diff --git a/drivers/block/drbd/drbd_req.h b/drivers/block/drbd/drbd_req.h
index eb49e7f2da9111eb0fc529e5939b4f22c43f84f2..9e1866ab238fc8e56c3a95f6bf0f9b4acf229da3 100644 (file)
--- a/drivers/block/drbd/drbd_req.h
+++ b/drivers/block/drbd/drbd_req.h
@@ -263,7 +263,7 @@ enum drbd_req_state_bits {
 static inline void drbd_req_make_private_bio(struct drbd_request *req, struct bio *bio_src)
 {
        struct bio *bio;
-       bio = bio_clone(bio_src, GFP_NOIO); /* XXX cannot fail?? */
+       bio = bio_clone_fast(bio_src, GFP_NOIO, drbd_io_bio_set);
 
        req->private_bio = bio;