Btrfs: tweak the inode-map and free extent search starts on cold mount

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

1 files changed, 19 insertions, 2 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index cd40a08dd8a6..688aa861a928 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -339,13 +339,30 @@ static int find_free_extent(struct btrfs_trans_handle *trans, struct btrfs_root
         int total_needed = num_blocks;
         int level;
 
+        path = btrfs_alloc_path();
+        ins->flags = 0;
+        btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
+
         level = btrfs_header_level(btrfs_buffer_header(root->node));
         total_needed += (level + 1) * 3;
+        if (root->fs_info->last_insert.objectid == 0 && search_end == (u64)-1) {
+                struct btrfs_disk_key *last_key;
+                btrfs_init_path(path);
+                ins->objectid = (u64)-1;
+                ins->offset = (u64)-1;
+                ret = btrfs_search_slot(trans, root, ins, path, 0, 0);
+                if (ret < 0)
+                        goto error;
+                BUG_ON(ret == 0);
+                if (path->slots[0] > 0)
+                        path->slots[0]--;
+                l = btrfs_buffer_leaf(path->nodes[0]);
+                last_key = &l->items[path->slots[0]].key;
+                search_start = btrfs_disk_key_objectid(last_key);
+        }
         if (root->fs_info->last_insert.objectid > search_start)
                 search_start = root->fs_info->last_insert.objectid;
 
-        ins->flags = 0;
-        btrfs_set_key_type(ins, BTRFS_EXTENT_ITEM_KEY);
         path = btrfs_alloc_path();
 
 check_failed: