Btrfs: Prevent root_list corruption

I was seeing root_list corruption on unmount during fs resize in 3.4-rc4; add
correct locking to address this.

Signed-off-by: Daniel J Blueman <daniel@quora.org>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index 017281dbb2a71f6a0c51f4f8cc52cf9e651f2fd0..5a105a086acfea61bcb3b326335b8371dda00bfd 100644 (file)
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -1279,7 +1279,9 @@ static int __update_reloc_root(struct btrfs_root *root, int del)
                if (rb_node)
                        backref_tree_panic(rb_node, -EEXIST, node->bytenr);
        } else {
+               spin_lock(&root->fs_info->trans_lock);
                list_del_init(&root->root_list);
+               spin_unlock(&root->fs_info->trans_lock);
                kfree(node);
        }
        return 0;