From mboxrd@z Thu Jan  1 00:00:00 1970
From: Maxim Patlasov <mpatlasov@parallels.com>
Subject: Re: [PATCH 05/11] fuse: Trust kernel i_mtime only -v2
Date: Mon, 20 Jan 2014 15:33:37 +0400
Message-ID: <52DD0991.2000905@parallels.com>
References: <20131010130718.10089.6736.stgit@dhcp-10-30-17-2.sw.ru> <20131010131051.10089.62357.stgit@dhcp-10-30-17-2.sw.ru> <20131112165251.GA10813@tucsk.piliscsaba.szeredi.hu> <52BC4E35.8040503@parallels.com> <20140106162242.GE16230@tucsk.piliscsaba.szeredi.hu>
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Cc: <dev@parallels.com>, <xemul@parallels.com>,
	<fuse-devel@lists.sourceforge.net>, <bfoster@redhat.com>,
	<linux-kernel@vger.kernel.org>, <jbottomley@parallels.com>,
	<linux-fsdevel@vger.kernel.org>, <akpm@linux-foundation.org>,
	<fengguang.wu@intel.com>, <devel@openvz.org>
To: Miklos Szeredi <miklos@szeredi.hu>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <20140106162242.GE16230@tucsk.piliscsaba.szeredi.hu>
Sender: linux-kernel-owner@vger.kernel.org
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On 01/06/2014 08:22 PM, Miklos Szeredi wrote:
> On Thu, Dec 26, 2013 at 07:41:41PM +0400, Maxim Patlasov wrote:
>>>> +
>>>> +	if (!err)
>>>> +		clear_bit(FUSE_I_MTIME_DIRTY, &fi->state);
>>> Doing the test and the clear separately opens a huge race window when i_mtime
>>> modifications are bound to get lost.
>> No. Because the whole operation is protected by i_mutex (see
>> fuse_fsync_common()).
> fuse_release_common() doesn't have i_mutex.  It's probably safe to acquire it,
> but is that really needed?

No, that's not needed, I think. Because by the time of calling 
fuse_release(), file->f_count is already zero and no userspace activity 
is possible on the file.

Are you OK about -v3 version of the patch (sent 12/26/2013)?

Thanks,
Maxim

>
> Thanks,
> Miklos
>