namei: teach lookup_slow() to skip revalidate
... and make mountpoint_last() use it. That makes all
candidates for lookup with parent locked shared go
through lookup_slow().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/include/linux/namei.h b/include/linux/namei.h
index d0f25d8..77d0170 100644
--- a/include/linux/namei.h
+++ b/include/linux/namei.h
@@ -31,6 +31,7 @@
#define LOOKUP_PARENT 0x0010
#define LOOKUP_REVAL 0x0020
#define LOOKUP_RCU 0x0040
+#define LOOKUP_NO_REVAL 0x0080
/*
* Intent data