Btrfs: update to the right index of defragment

When we use autodefrag, we forget to update the index which indicates
the last page we've dirty.  And we'll set dirty flags on a same set of
pages again and again.

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

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index afde837644e..18cc23d164a 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1186,6 +1186,9 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
                         if (newer_off == (u64)-1)
                                 break;
 
+                        if (ret > 0)
+                                i += ret;
+
                         newer_off = max(newer_off + 1,
                                         (u64)i << PAGE_CACHE_SHIFT);