Btrfs: Add BH_Defrag to mark buffers that are in need of defragging

This allows the tree walking code to defrag only the newly allocated
buffers, it seems to be a good balance between perfect defragging and the
performance hit of repeatedly reallocating blocks.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/fs/btrfs/tree-defrag.c b/fs/btrfs/tree-defrag.c
index a09064a9a41c..35fd20d24645 100644
--- a/fs/btrfs/tree-defrag.c
+++ b/fs/btrfs/tree-defrag.c
@@ -86,7 +86,7 @@ static int defrag_walk_down(struct btrfs_trans_handle *trans,
                 if (cache_only) {
                         next = btrfs_find_tree_block(root, blocknr);
                         if (!next || !buffer_uptodate(next) ||
-                           buffer_locked(next)) {
+                           buffer_locked(next) || !buffer_defrag(next)) {
                                 brelse(next);
                                 path->slots[*level]++;
                                 continue;
@@ -142,6 +142,7 @@ static int defrag_walk_up(struct btrfs_trans_handle *trans,
                         root->defrag_level = i;
                         return 0;
                 } else {
+                        clear_buffer_defrag(path->nodes[*level]);
                         btrfs_block_release(root, path->nodes[*level]);
                         path->nodes[*level] = NULL;
                         *level = i + 1;