Btrfs: use flag EXTENT_DEFRAG for snapshot-aware defrag

We're going to use this flag EXTENT_DEFRAG to indicate which range
belongs to defragment so that we can implement snapshow-aware defrag:

We set the EXTENT_DEFRAG flag when dirtying the extents that need
defragmented, so later on writeback thread can differentiate between
normal writeback and writeback started by defragmentation.

Original-Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Liu Bo <bo.li.liu@oracle.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index 00279c9a7f35..0a4b03d8fcd6 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1203,8 +1203,8 @@ again:
 
                 clear_extent_bit(&BTRFS_I(inode)->io_tree, start_pos,
                                   last_pos - 1, EXTENT_DIRTY | EXTENT_DELALLOC |
-                                  EXTENT_DO_ACCOUNTING, 0, 0, &cached_state,
-                                  GFP_NOFS);
+                                  EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
+                                  0, 0, &cached_state, GFP_NOFS);
                 unlock_extent_cached(&BTRFS_I(inode)->io_tree,
                                      start_pos, last_pos - 1, &cached_state,
                                      GFP_NOFS);