Btrfs: fix memory leak when cloning root's node

After cloning root's node, we forgot to dec the src's ref
which can lead to a memory leak.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index eba44b0768295975864b679282f69d4bcf2fd5d6..cdfb4c49a806ad4ba0ebe83b5569a4121a10a220 100644 (file)
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -1241,6 +1241,7 @@ get_old_root(struct btrfs_root *root, u64 time_seq)
 {
        struct tree_mod_elem *tm;
        struct extent_buffer *eb;
+       struct extent_buffer *old;
        struct tree_mod_root *old_root = NULL;
        u64 old_generation = 0;
        u64 logical;
@@ -1264,13 +1265,14 @@ get_old_root(struct btrfs_root *root, u64 time_seq)
                btrfs_tree_read_unlock(root->node);
                free_extent_buffer(root->node);
                blocksize = btrfs_level_size(root, old_root->level);
-               eb = read_tree_block(root, logical, blocksize, 0);
-               if (!eb) {
+               old = read_tree_block(root, logical, blocksize, 0);
+               if (!old) {
                        pr_warn("btrfs: failed to read tree block %llu from get_old_root\n",
                                logical);
                        WARN_ON(1);
                } else {
-                       eb = btrfs_clone_extent_buffer(eb);
+                       eb = btrfs_clone_extent_buffer(old);
+                       free_extent_buffer(old);
                }
        } else if (old_root) {
                btrfs_tree_read_unlock(root->node);