Commit 02f57c7a authored by Josef Bacik's avatar Josef Bacik
Browse files

Btrfs: don't split dio bios if we don't have to 



We have been unconditionally allocating a new bio and re-adding all pages from
our original bio to the new bio.  This is needed if our original bio is larger
than our stripe size, but if it is smaller than the stripe size then there is no
need to do this.  So check the map length and if we are under that then go ahead
and submit the original bio.  Thanks,

Signed-off-by: default avatarJosef Bacik <josef@redhat.com>
parent 1ef30be1

fs/btrfs/inode.c

+13 −7
Original line number Diff line number Diff line
@@ -6006,13 +6006,6 @@ static int btrfs_submit_direct_hook(int rw, struct btrfs_dio_private *dip, 
	int ret = 0;

	int write = rw & REQ_WRITE;



	bio = btrfs_dio_bio_alloc(orig_bio->bi_bdev, start_sector, GFP_NOFS);

	if (!bio)

		return -ENOMEM;

	bio->bi_private = dip;

	bio->bi_end_io = btrfs_end_dio_bio;

	atomic_inc(&dip->pending_bios);



	map_length = orig_bio->bi_size;

	ret = btrfs_map_block(map_tree, READ, start_sector << 9,

			      &map_length, NULL, 0);
@@ -6021,6 +6014,18 @@ static int btrfs_submit_direct_hook(int rw, struct btrfs_dio_private *dip, 
		return -EIO;

	}



	if (map_length >= orig_bio->bi_size) {

		bio = orig_bio;

		goto submit;

	}



	bio = btrfs_dio_bio_alloc(orig_bio->bi_bdev, start_sector, GFP_NOFS);

	if (!bio)

		return -ENOMEM;

	bio->bi_private = dip;

	bio->bi_end_io = btrfs_end_dio_bio;

	atomic_inc(&dip->pending_bios);



	while (bvec <= (orig_bio->bi_io_vec + orig_bio->bi_vcnt - 1)) {

		if (unlikely(map_length < submit_len + bvec->bv_len ||

		    bio_add_page(bio, bvec->bv_page, bvec->bv_len,
@@ -6071,6 +6076,7 @@ static int btrfs_submit_direct_hook(int rw, struct btrfs_dio_private *dip, 
		}

	}



submit:

	ret = __btrfs_submit_dio_bio(bio, inode, rw, file_offset, skip_sum,

				     csums);

	if (!ret)

CRA Git | Maintained and supported by SUSTech CRA and CCSE