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>

3 files changed, 3 insertions, 3 deletions

diff --git a/fs/namespace.c b/fs/namespace.c
index 22bfe8273c68..b4febb29d3bb 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -1757,7 +1757,7 @@ static int do_loopback(struct path *path, char *old_name,
                 return err;
         if (!old_name || !*old_name)
                 return -EINVAL;
-        err = kern_path(old_name, LOOKUP_FOLLOW, &old_path);
+        err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path);
         if (err)
                 return err;
 
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 9b7dd7013b15..5b19b6aabe18 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -2798,7 +2798,7 @@ static struct dentry *nfs_follow_remote_path(struct vfsmount *root_mnt,
                 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);
diff --git a/fs/quota/quota.c b/fs/quota/quota.c
index b34bdb25490c..10b6be3ca280 100644
--- a/fs/quota/quota.c
+++ b/fs/quota/quota.c
@@ -355,7 +355,7 @@ SYSCALL_DEFINE4(quotactl, unsigned int, cmd, const char __user *, special,
          * resolution (think about autofs) and thus deadlocks could arise.
          */
         if (cmds == Q_QUOTAON) {
-                ret = user_path_at(AT_FDCWD, addr, LOOKUP_FOLLOW, &path);
+                ret = user_path_at(AT_FDCWD, addr, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path);
                 if (ret)
                         pathp = ERR_PTR(ret);
                 else