VFS: Fix the remaining automounter semantics regressions

The concensus seems to be that system calls such as stat() etc should
not trigger an automount.  Neither should the l* versions.

This patch therefore adds a LOOKUP_AUTOMOUNT flag to tag those lookups
that _should_ trigger an automount on the last path element.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
[ Edited to leave out the cases that are already covered by LOOKUP_OPEN,
  LOOKUP_DIRECTORY and LOOKUP_CREATE - all of which also fundamentally
  force automounting for their own reasons   - Linus ]
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 9b7dd70..5b19b6a 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -2798,7 +2798,7 @@
 		goto out_put_mnt_ns;
 
 	ret = vfs_path_lookup(root_mnt->mnt_root, root_mnt,
-			export_path, LOOKUP_FOLLOW, &path);
+			export_path, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path);
 
 	nfs_referral_loop_unprotect();
 	put_mnt_ns(ns_private);