From: Andrew Morton <akpm@linux-foundation.org>
To: Ian Kent <raven@themaw.net>
Cc: autofs mailing list <autofs@linux.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] autofs4 - remove hashed check in validate_wait()
Date: Sun, 7 Jun 2009 22:08:14 -0700 [thread overview]
Message-ID: <20090607220814.cc7519f6.akpm@linux-foundation.org> (raw)
In-Reply-To: <20090608032537.7088.1870.stgit@zeus.themaw.net>
On Mon, 08 Jun 2009 11:25:37 +0800 Ian Kent <raven@themaw.net> wrote:
> The recent ->lookup() deadlock correction required the directory
> inode mutex to be dropped while waiting for expire completion. We
> were concerned about side effects from this change and one has
> been identified.
>
> When checking if a mount has already completed prior to adding a
> new mount request to the wait queue we check if the dentry is hashed
> and, if so, if it is a mount point. But, if a mount successfully
> completed while we slept on the wait queue mutex the dentry must
> exist for the mount to have completed so the test is not really
> needed.
>
> Mounts can also be done on top of a global root dentry, so for the
> above case, where a mount request completes and the wait queue entry
> has already been removed, the hashed test returning false can cause
> an incorrect callback to the daemon. Also, d_mountpoint() is not
> sufficient to check if a mount has completed for the multi-mount
> case when we don't have a real mount at the base of the tree.
>
I've been scratching my head trying to work out if this is a
needed-in-2.6.30 fix, but all I got was a bald spot. Help?
next prev parent reply other threads:[~2009-06-08 5:10 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-08 3:25 [PATCH] autofs4 - remove hashed check in validate_wait() Ian Kent
2009-06-08 5:08 ` Andrew Morton [this message]
2009-06-08 5:23 ` Ian Kent
2009-06-08 5:41 ` Andrew Morton
2009-06-08 5:53 ` Ian Kent
2009-06-08 5:59 ` Ian Kent
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