linux-kernel - Re: [PATCH 1/3] autofs - fix AT_NO

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Date:   Thu, 10 Aug 2017 10:16:02 +0800
From:   Ian Kent <raven@...maw.net>
To:     David Howells <dhowells@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        autofs mailing list <autofs@...r.kernel.org>,
        Ondrej Holy <oholy@...hat.com>,
        Colin Walters <walters@...hat.com>,
        Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>
Subject: Re: [PATCH 1/3] autofs - fix AT_NO_AUTOMOUNT not being honored

On 09/08/17 17:51, Ian Kent wrote:
> On 09/08/17 16:39, David Howells wrote:
>> Ian Kent <raven@...maw.net> wrote:
>>
>>> In order to handle the AT_NO_AUTOMOUNT for both system calls the
>>> negative dentry case in follow_automount() needs to be changed to
>>> return ENOENT when the LOOKUP_AUTOMOUNT flag is clear (and the other
>>> required flags are clear).
>>
>> Should the be EREMOTE instead of ENOENT?
> 
> I thought about that and ended up thinking ENOENT was more sensible
> but I'll look at it again.

I think EREMOTE and ENOENT both are inaccurate.

There's no way to know if the negative dentry corresponds to a valid map
key, and we've seen increasing lookups from userspace applications for
invalid directories, so I'm not sure.

I went with ENOENT but I guess we could use EREMOTE, what's your thinking
on why EREMOTE might be better than ENOENT?

Ian