btrfs: use BTRFS_SUPER_INFO_SIZE macro at btrfs_read_dev_super()

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 8e2eee67c3a8..13564354c927 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2984,9 +2984,11 @@ struct buffer_head *btrfs_read_dev_super(struct block_device *bdev)
          */
         for (i = 0; i < 1; i++) {
                 bytenr = btrfs_sb_offset(i);
-                if (bytenr + 4096 >= i_size_read(bdev->bd_inode))
+                if (bytenr + BTRFS_SUPER_INFO_SIZE >=
+                                        i_size_read(bdev->bd_inode))
                         break;
-                bh = __bread(bdev, bytenr / 4096, 4096);
+                bh = __bread(bdev, bytenr / 4096,
+                                        BTRFS_SUPER_INFO_SIZE);
                 if (!bh)
                         continue;