Btrfs: optimize extent item search in run_delayed_extent_op

Instead of doing another extent tree search if the first search failed
to find a metadata item, check if the previous item in the leaf is an
extent item and use it if it is, otherwise do the second tree search
for an extent item.

Signed-off-by: Filipe David Borba Manana <fdmanana@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index a807acc9a63eb7f0928c2ed2f79fa5e1aef6fed1..4595a65db7293ee3569cf00e31d258626b2f2b3e 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -2130,15 +2130,28 @@ again:
        }
        if (ret > 0) {
                if (metadata) {
-                       btrfs_release_path(path);
-                       metadata = 0;
+                       if (path->slots[0] > 0) {
+                               path->slots[0]--;
+                               btrfs_item_key_to_cpu(path->nodes[0], &key,
+                                                     path->slots[0]);
+                               if (key.objectid == node->bytenr &&
+                                   key.type == BTRFS_EXTENT_ITEM_KEY &&
+                                   key.offset == node->num_bytes)
+                                       ret = 0;
+                       }
+                       if (ret > 0) {
+                               btrfs_release_path(path);
+                               metadata = 0;
 
-                       key.offset = node->num_bytes;
-                       key.type = BTRFS_EXTENT_ITEM_KEY;
-                       goto again;
+                               key.objectid = node->bytenr;
+                               key.offset = node->num_bytes;
+                               key.type = BTRFS_EXTENT_ITEM_KEY;
+                               goto again;
+                       }
+               } else {
+                       err = -EIO;
+                       goto out;
                }
-               err = -EIO;
-               goto out;
        }
 
        leaf = path->nodes[0];