reiserfs: Safely acquire i_mutex from xattr_rmdir

Relax the reiserfs lock before taking the inode mutex from
xattr_rmdir() to avoid the usual reiserfs lock <-> inode mutex
bad dependency.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Tested-by: Christian Kujau <lists@nerdbynature.de>
Cc: Alexander Beregalov <a.beregalov@gmail.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>

fs/reiserfs/xattr.c

@@ -98,7 +98,8 @@ static int xattr_rmdir(struct inode *dir, struct dentry *dentry)
 	BUG_ON(!mutex_is_locked(&dir->i_mutex));
 	vfs_dq_init(dir);
 
-	mutex_lock_nested(&dentry->d_inode->i_mutex, I_MUTEX_CHILD);
+	reiserfs_mutex_lock_nested_safe(&dentry->d_inode->i_mutex,
+					I_MUTEX_CHILD, dir->i_sb);
 	dentry_unhash(dentry);
 	error = dir->i_op->rmdir(dir, dentry);
 	if (!error)