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

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Message-ID: <20160329140244.GV17997@ZenIV.linux.org.uk>
Date:	Tue, 29 Mar 2016 15:02:44 +0100
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Arend Van Spriel <arend.vanspriel@...adcom.com>
Cc:	Junichi Nomura <j-nomura@...jp.nec.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Linux NFS Mailing List <linux-nfs@...r.kernel.org>
Subject: Re: [REGRESSION 4.6-rc1] NFS mounts (using autofs) failing

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);
 	}