From: Al Viro <viro@ZenIV.linux.org.uk>
To: Ian Kent <raven@themaw.net>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>,
David Howells <dhowells@redhat.com>,
Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
npiggin@gmail.com
Subject: Re: [PATCH 0/3] Fixes for vfs-scale and vfs-automount
Date: Thu, 24 Feb 2011 14:59:47 +0000 [thread overview]
Message-ID: <20110224145947.GA22723@ZenIV.linux.org.uk> (raw)
In-Reply-To: <1298542053.3058.56.camel@perseus>
On Thu, Feb 24, 2011 at 06:07:33PM +0800, Ian Kent wrote:
> > I really don't like the look of autofs4_tree_busy(), BTW - you don't need
> > RCU to get races here; just a plain chdir("../../.."); done by a process
> > that sits deep enough in subtree you are checking can very well race with
> > your check, so that your iterator gets through the new cwd before chdir()
> > and through the old one after it...
>
> Yes, that's a problem.
>
> Previously the dcache_lock would have blocked on the dput() ... mmm, I'd
> missed that so far, although Nick didn't talk with me about his changes
> very much at all and I didn't pay enough attention to his patch series
> along the way, oops!
Well... In principle, you could mark all mountpoints in a tree as managed,
have an "expiry search in progress" flag to stop everything in there while
the expiry happens, then wait out all RCU walks in progress, then go ahead
with your expiry checks. Would that work for you?
next prev parent reply other threads:[~2011-02-24 14:59 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-18 4:05 [PATCH 0/3] Fixes for vfs-scale and vfs-automount Ian Kent
2011-01-18 4:06 ` [PATCH 1/3] autofs4 - fix get_next_positive_dentry() Ian Kent
2011-01-18 4:06 ` [PATCH 2/3] vfs - fix dentry ref count in do_lookup() Ian Kent
2011-01-18 4:44 ` Al Viro
2011-01-18 4:06 ` [PATCH 3/3] autofs4 - fix debug print in autofs4_lookup() Ian Kent
2011-01-19 7:06 ` [PATCH 0/3] Fixes for vfs-scale and vfs-automount Ian Kent
2011-02-15 14:25 ` Ian Kent
2011-02-23 7:22 ` Ian Kent
2011-02-23 16:37 ` Linus Torvalds
2011-02-24 1:58 ` Al Viro
2011-02-24 3:03 ` Ian Kent
2011-02-24 3:14 ` Al Viro
[not found] ` <20110224031439.GR22723-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2011-02-24 3:28 ` Ian Kent
2011-02-24 3:58 ` Al Viro
2011-02-24 5:47 ` Al Viro
2011-02-24 7:23 ` Ian Kent
[not found] ` <20110224035836.GS22723-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2011-02-24 6:34 ` Ian Kent
2011-02-24 7:07 ` Al Viro
[not found] ` <20110224070724.GW22723-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
2011-02-24 10:07 ` Ian Kent
2011-02-24 14:59 ` Al Viro [this message]
2011-02-24 15:18 ` Al Viro
2011-02-25 3:07 ` Ian Kent
2011-02-24 19:10 ` Al Viro
2011-02-24 10:21 ` Ian Kent
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