Btrfs: reada while dropping snapshots

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

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 47e91184fff3e5dad892f44e9e5cb1451c46a606..b38c3e92f0c80270a9eed1dacca21cebf618e559 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -940,7 +940,6 @@ static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
        int wrapped = 0;
        u64 limit;
 
-       path = btrfs_alloc_path();
        ins->flags = 0;
        btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
 
@@ -974,6 +973,8 @@ static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
                                                     data, 1);
        }
 
+       path = btrfs_alloc_path();
+
 check_failed:
        if (!block_group->data)
                search_start = find_search_start(root, &block_group,
@@ -1355,6 +1356,28 @@ static int drop_leaf_ref(struct btrfs_trans_handle *trans,
        return 0;
 }
 
+static void reada_walk_down(struct btrfs_root *root,
+                           struct btrfs_node *node)
+{
+       int i;
+       u32 nritems;
+       u64 blocknr;
+       int ret;
+       u32 refs;
+
+       nritems = btrfs_header_nritems(&node->header);
+       for (i = 0; i < nritems; i++) {
+               blocknr = btrfs_node_blockptr(node, i);
+               ret = lookup_extent_ref(NULL, root, blocknr, 1, &refs);
+               BUG_ON(ret);
+               if (refs != 1)
+                       continue;
+               ret = readahead_tree_block(root, blocknr);
+               if (ret)
+                       break;
+       }
+}
+
 /*
  * helper function for drop_snapshot, this walks down the tree dropping ref
  * counts as it goes.
@@ -1375,6 +1398,7 @@ static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
        BUG_ON(ret);
        if (refs > 1)
                goto out;
+
        /*
         * walk down to the last node level and free all the leaves
         */
@@ -1382,8 +1406,13 @@ static int walk_down_tree(struct btrfs_trans_handle *trans, struct btrfs_root
                WARN_ON(*level < 0);
                WARN_ON(*level >= BTRFS_MAX_LEVEL);
                cur = path->nodes[*level];
+
+               if (*level > 0 && path->slots[*level] == 0)
+                       reada_walk_down(root, btrfs_buffer_node(cur));
+
                if (btrfs_header_level(btrfs_buffer_header(cur)) != *level)
                        WARN_ON(1);
+
                if (path->slots[*level] >=
                    btrfs_header_nritems(btrfs_buffer_header(cur)))
                        break;