Re: [REGRESSION 4.6-rc1] NFS mounts (using autofs) failing

[Al Viro]

On Tue, Mar 29, 2016 at 01:11:55PM +0200, Arend Van Spriel wrote:
> Hi Al,
> 
> Moved to 4.6-rc1 and found NFS mounts were failing moving to the new
> kernel. The NFS mounts are done using autofs. Below is the bisect log
> and attached the kernel .config file. Let me know if you need any other
> information.

AFAICS, it's the same one that got reported yesterday by Junichi Nomura.
Folks, could you check if the delta below fixes it?

diff --git a/fs/namei.c b/fs/namei.c
index 3498d53..0d80c72 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1740,15 +1740,17 @@ static int walk_component(struct nameidata *nd, int 
flags)
                                          nd->flags);
                if (IS_ERR(path.dentry))
                        return PTR_ERR(path.dentry);
-               if (unlikely(d_is_negative(path.dentry))) {
-                       dput(path.dentry);
-                       return -ENOENT;
-               }
+
                path.mnt = nd->path.mnt;
                err = follow_managed(&path, nd);
                if (unlikely(err < 0))
                        return err;
 
+               if (unlikely(d_is_negative(path.dentry))) {
+                       path_to_nameidata(&path, nd);
+                       return -ENOENT;
+               }
+
                seq = 0;        /* we are already out of RCU mode */
                inode = d_backing_inode(path.dentry);
        }