linux-kernel - Re: [PATCH 0/9] [RFC v2] safely drop directory dentry on failed revalidate

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Date:	Sun, 01 Sep 2013 08:56:25 +0800
From:	Ian Kent <raven@...maw.net>
To:	Miklos Szeredi <miklos@...redi.hu>
Cc:	Miklos Szeredi <mszeredi@...e.cz>,
	Al Viro <viro@...iv.linux.org.uk>,
	Ric Wheeler <rwheeler@...hat.com>,
	Anand Avati <avati@...hat.com>,
	Brian Foster <bfoster@...hat.com>,
	David Howells <dhowells@...hat.com>,
	Eric Paris <eparis@...hat.com>,
	Linux-Fsdevel <linux-fsdevel@...r.kernel.org>,
	Kernel Mailing List <linux-kernel@...r.kernel.org>,
	KONISHI Ryusuke <konishi.ryusuke@....ntt.co.jp>
Subject: Re: [PATCH 0/9] [RFC v2] safely drop directory dentry on failed
 revalidate

On Fri, 2013-08-30 at 10:59 +0200, Miklos Szeredi wrote:
> On Fri, Aug 30, 2013 at 1:44 AM, Ian Kent <raven@...maw.net> wrote:
> 
> >> The check in waitq.c above "is" used to validate the need to callback to
> >> the daemon to request a mount.
> 
> Okay.  But then shouldn't the check be  "if (d_mountpoint(dentry)) valid = 0;" ?

I don't think so.

But again, may_umount() might do what's needed here too.

I don't think this is enough because it doesn't cover the case where the
dentry is not simple_empty() but has no mounts below. That's not a
normal use case but could happen if the daemon crashed at just the wrong
time, encountered an error condition that didn't allow it to cleanup
directories, or a user umounted triggers within the tree before starting
the daemon.

> 
> Thanks,
> Miklos


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