fix LOOKUP_FOLLOW on automount "symlinks"

Make sure that automount "symlinks" are followed regardless of LOOKUP_FOLLOW;
it should have no effect on them.

Cc: stable@kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/namei.c

@@ -822,6 +822,17 @@ fail:
 	return PTR_ERR(dentry);
 }
 
+/*
+ * This is a temporary kludge to deal with "automount" symlinks; proper
+ * solution is to trigger them on follow_mount(), so that do_lookup()
+ * would DTRT.  To be killed before 2.6.34-final.
+ */
+static inline int follow_on_final(struct inode *inode, unsigned lookup_flags)
+{
+	return inode && unlikely(inode->i_op->follow_link) &&
+		((lookup_flags & LOOKUP_FOLLOW) || S_ISDIR(inode->i_mode));
+}
+
 /*
  * Name resolution.
  * This is the basic name resolution function, turning a pathname into
@@ -942,8 +953,7 @@ last_component:
 		if (err)
 			break;
 		inode = next.dentry->d_inode;
-		if ((lookup_flags & LOOKUP_FOLLOW)
+		if (follow_on_final(inode, lookup_flags)) {
-		    && inode && inode->i_op->follow_link) {
 			err = do_follow_link(&next, nd);
 			if (err)
 				goto return_err;