Btrfs: fix lockdep warning on clone ioctl

I'm no lockdep expert, but this appears to make the lockdep warning go
away for the i_mutex locking in the clone ioctl.

Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 3fe15e4..93d69b3 100644 (file)
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -1492,11 +1492,11 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd,
        path->reada = 2;
 
        if (inode < src) {
-               mutex_lock(&inode->i_mutex);
-               mutex_lock(&src->i_mutex);
+               mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT);
+               mutex_lock_nested(&src->i_mutex, I_MUTEX_CHILD);
        } else {
-               mutex_lock(&src->i_mutex);
-               mutex_lock(&inode->i_mutex);
+               mutex_lock_nested(&src->i_mutex, I_MUTEX_PARENT);
+               mutex_lock_nested(&inode->i_mutex, I_MUTEX_CHILD);
        }
 
        /* determine range to clone */