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>

1 files changed, 4 insertions, 4 deletions

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 3fe15e435b5c..93d69b32028e 100644
--- 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 */