1 files changed, 13 insertions, 7 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 4a238d676e5b..149c77fd1eb5 100644
--- 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)