btrfs: remove bio splitting and merge_bvec_fn() calls

Btrfs has been doing bio splitting from btrfs_map_bio(), by checking
device limits as well as calling ->merge_bvec_fn() etc. That is not
necessary any more, because generic_make_request() is now able to
handle arbitrarily sized bios. So clean up unnecessary code paths.

Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: linux-btrfs@vger.kernel.org
Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
Signed-off-by: Chris Mason <clm@fb.com>
[dpark: add more description in commit message]
Signed-off-by: Dongsu Park <dpark@posteo.net>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 8f2ca18..762476f 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -5870,34 +5870,6 @@ static noinline void btrfs_schedule_bio(struct btrfs_root *root,
                                 &device->work);
 }
 
-static int bio_size_ok(struct block_device *bdev, struct bio *bio,
-                      sector_t sector)
-{
-       struct bio_vec *prev;
-       struct request_queue *q = bdev_get_queue(bdev);
-       unsigned int max_sectors = queue_max_sectors(q);
-       struct bvec_merge_data bvm = {
-               .bi_bdev = bdev,
-               .bi_sector = sector,
-               .bi_rw = bio->bi_rw,
-       };
-
-       if (WARN_ON(bio->bi_vcnt == 0))
-               return 1;
-
-       prev = &bio->bi_io_vec[bio->bi_vcnt - 1];
-       if (bio_sectors(bio) > max_sectors)
-               return 0;
-
-       if (!q->merge_bvec_fn)
-               return 1;
-
-       bvm.bi_size = bio->bi_iter.bi_size - prev->bv_len;
-       if (q->merge_bvec_fn(q, &bvm, prev) < prev->bv_len)
-               return 0;
-       return 1;
-}
-
 static void submit_stripe_bio(struct btrfs_root *root, struct btrfs_bio *bbio,
                              struct bio *bio, u64 physical, int dev_nr,
                              int rw, int async)
@@ -5931,38 +5903,6 @@ static void submit_stripe_bio(struct btrfs_root *root, struct btrfs_bio *bbio,
                btrfsic_submit_bio(rw, bio);
 }
 
-static int breakup_stripe_bio(struct btrfs_root *root, struct btrfs_bio *bbio,
-                             struct bio *first_bio, struct btrfs_device *dev,
-                             int dev_nr, int rw, int async)
-{
-       struct bio_vec *bvec = first_bio->bi_io_vec;
-       struct bio *bio;
-       int nr_vecs = bio_get_nr_vecs(dev->bdev);
-       u64 physical = bbio->stripes[dev_nr].physical;
-
-again:
-       bio = btrfs_bio_alloc(dev->bdev, physical >> 9, nr_vecs, GFP_NOFS);
-       if (!bio)
-               return -ENOMEM;
-
-       while (bvec <= (first_bio->bi_io_vec + first_bio->bi_vcnt - 1)) {
-               if (bio_add_page(bio, bvec->bv_page, bvec->bv_len,
-                                bvec->bv_offset) < bvec->bv_len) {
-                       u64 len = bio->bi_iter.bi_size;
-
-                       atomic_inc(&bbio->stripes_pending);
-                       submit_stripe_bio(root, bbio, bio, physical, dev_nr,
-                                         rw, async);
-                       physical += len;
-                       goto again;
-               }
-               bvec++;
-       }
-
-       submit_stripe_bio(root, bbio, bio, physical, dev_nr, rw, async);
-       return 0;
-}
-
 static void bbio_error(struct btrfs_bio *bbio, struct bio *bio, u64 logical)
 {
        atomic_inc(&bbio->error);
@@ -6035,18 +5975,6 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio,
                        continue;
                }
 
-               /*
-                * Check and see if we're ok with this bio based on it's size
-                * and offset with the given device.
-                */
-               if (!bio_size_ok(dev->bdev, first_bio,
-                                bbio->stripes[dev_nr].physical >> 9)) {
-                       ret = breakup_stripe_bio(root, bbio, first_bio, dev,
-                                                dev_nr, rw, async_submit);
-                       BUG_ON(ret);
-                       continue;
-               }
-
                if (dev_nr < total_devs - 1) {
                        bio = btrfs_bio_clone(first_bio, GFP_NOFS);
                        BUG_ON(!bio); /* -ENOMEM */