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, 12 insertions, 8 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index d34eb329720d..9b21cf97cdd5 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -3549,7 +3549,8 @@ again:
         }
 
         clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start, page_end,
-                          EXTENT_DIRTY | EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING,
+                          EXTENT_DIRTY | EXTENT_DELALLOC |
+                          EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
                           0, 0, &cached_state, GFP_NOFS);
 
         ret = btrfs_set_extent_delalloc(inode, page_start, page_end,
@@ -6061,7 +6062,8 @@ unlock:
         if (lockstart < lockend) {
                 if (create && len < lockend - lockstart) {
                         clear_extent_bit(&BTRFS_I(inode)->io_tree, lockstart,
-                                         lockstart + len - 1, unlock_bits, 1, 0,
+                                         lockstart + len - 1,
+                                         unlock_bits | EXTENT_DEFRAG, 1, 0,
                                          &cached_state, GFP_NOFS);
                         /*
                          * Beside unlock, we also need to cleanup reserved space
@@ -6069,8 +6071,8 @@ unlock:
                          */
                         clear_extent_bit(&BTRFS_I(inode)->io_tree,
                                          lockstart + len, lockend,
-                                         unlock_bits | EXTENT_DO_ACCOUNTING,
-                                         1, 0, NULL, GFP_NOFS);
+                                         unlock_bits | EXTENT_DO_ACCOUNTING |
+                                         EXTENT_DEFRAG, 1, 0, NULL, GFP_NOFS);
                 } else {
                         clear_extent_bit(&BTRFS_I(inode)->io_tree, lockstart,
                                          lockend, unlock_bits, 1, 0,
@@ -6635,8 +6637,8 @@ static void btrfs_invalidatepage(struct page *page, unsigned long offset)
                  */
                 clear_extent_bit(tree, page_start, page_end,
                                  EXTENT_DIRTY | EXTENT_DELALLOC |
-                                 EXTENT_LOCKED | EXTENT_DO_ACCOUNTING, 1, 0,
-                                 &cached_state, GFP_NOFS);
+                                 EXTENT_LOCKED | EXTENT_DO_ACCOUNTING |
+                                 EXTENT_DEFRAG, 1, 0, &cached_state, GFP_NOFS);
                 /*
                  * whoever cleared the private bit is responsible
                  * for the finish_ordered_io
@@ -6652,7 +6654,8 @@ static void btrfs_invalidatepage(struct page *page, unsigned long offset)
         }
         clear_extent_bit(tree, page_start, page_end,
                  EXTENT_LOCKED | EXTENT_DIRTY | EXTENT_DELALLOC |
-                 EXTENT_DO_ACCOUNTING, 1, 1, &cached_state, GFP_NOFS);
+                 EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG, 1, 1,
+                 &cached_state, GFP_NOFS);
         __btrfs_releasepage(page, GFP_NOFS);
 
         ClearPageChecked(page);
@@ -6749,7 +6752,8 @@ again:
          * prepare_pages in the normal write path.
          */
         clear_extent_bit(&BTRFS_I(inode)->io_tree, page_start, page_end,
-                          EXTENT_DIRTY | EXTENT_DELALLOC | EXTENT_DO_ACCOUNTING,
+                          EXTENT_DIRTY | EXTENT_DELALLOC |
+                          EXTENT_DO_ACCOUNTING | EXTENT_DEFRAG,
                           0, 0, &cached_state, GFP_NOFS);
 
         ret = btrfs_set_extent_delalloc(inode, page_start, page_end,