vfs: prefer ->dentry->d_sb to ->mnt->mnt_sb

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/lockd/svcsubs.c b/fs/lockd/svcsubs.c
index 1ca0679..2240d38 100644
--- a/fs/lockd/svcsubs.c
+++ b/fs/lockd/svcsubs.c
@@ -403,7 +403,7 @@
 {
 	struct super_block *sb = datap;
 
-	return sb == file->f_file->f_path.mnt->mnt_sb;
+	return sb == file->f_file->f_path.dentry->d_sb;
 }
 
 /**