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

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 4def4d9..57546cf 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2507,7 +2507,7 @@
 	const struct cred *cred = current_cred();
 
 	if (flags & MS_REMOUNT)
-		return superblock_has_perm(cred, path->mnt->mnt_sb,
+		return superblock_has_perm(cred, path->dentry->d_sb,
 					   FILESYSTEM__REMOUNT, NULL);
 	else
 		return path_has_perm(cred, path, FILE__MOUNTON);