Btrfs: do not defrag a file partially

xfstests 218 complains that btrfs defrags a file partially:
 After: 1
 Write backwards sync, but contiguous - should defrag to 1 extent
 Before: 10
-After: 1
+After: 2

To fix this, we need to set max_to_defrag count properly.

Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 6834be4c8709..0b06a5ca8afc 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1066,7 +1066,7 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
                 i = range->start >> PAGE_CACHE_SHIFT;
         }
         if (!max_to_defrag)
-                max_to_defrag = last_index;
+                max_to_defrag = last_index + 1;
 
         /*
          * make writeback starts from i, so the defrag range can be