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

[firefly-linux-kernel-4.4.55.git] / fs / btrfs / inode.c

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 4a238d676e5b3a5ce1c529ab792013a20db625d6..149c77fd1eb54d35346531cec5e021269f037f14 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -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)