From: Ric Wheeler Subject: Re: [PATCH 3/3] Add timeout feature Date: Fri, 26 Sep 2008 06:58:11 -0400 Message-ID: <48DCC043.1020207@redhat.com> References: <20080908205337t-sato@mail.jp.nec.com> <20080908171119.GB22521@infradead.org> <48DBFD42.6030307@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Christoph Hellwig , Andrew Morton , Oleg Nesterov , linux-fsdevel@vger.kernel.org, dm-devel@redhat.com, viro@ZenIV.linux.org.uk, linux-ext4@vger.kernel.org, xfs@oss.sgi.com, axboe@kernel.dk, mtk.manpages@googlemail.com, linux-kernel@vger.kernel.org To: Takashi Sato Return-path: Received: from mx2.redhat.com ([66.187.237.31]:34197 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751506AbYIZK62 (ORCPT ); Fri, 26 Sep 2008 06:58:28 -0400 In-Reply-To: Sender: linux-ext4-owner@vger.kernel.org List-ID: Takashi Sato wrote: > Hi, > > Ric Wheeler wrote: >> Christoph Hellwig wrote: >>> On Mon, Sep 08, 2008 at 08:53:37PM +0900, Takashi Sato wrote: >>> >>>> The timeout feature is added to "freeze ioctl" to solve a deadlock >>>> when the freezer accesses a frozen filesystem. And new ioctl >>>> to reset the timeout period is added to extend the timeout period. >>>> For example, the freezer resets the timeout period to 10 seconds >>>> every 5 >>>> seconds. In this approach, even if the freezer causes a deadlock by >>>> accessing the frozen filesystem, it will be solved by the timeout >>>> in 10 seconds and the freezer will be able to recognize that >>>> at the next reset of timeout period. >>>> >>> >>> And as with all previous posting I still fundamentally disagree about >>> the need of this functionality. We don't need a timeout for freezing. >> >> I agree with Christoph here, I think that the timeout is unneeded. > > I think that your concern is that the freezer cannot recognize the > occurrence > of a timeout and it continues the backup process and the backup data is > corrupted finally. > If the freezer can recognize it by the unfreeze ioctl's errono, will > your concern > be solved? > If so, I will implement it. > > Cheers, Takashi > I think that is certainly part a big part of my concern. Also note that the timeout seems to be quite low relative to say the standard timeout for a SCSI device (30 seconds worst case). In general, I am quite supportive of the patch series and think that this is a great addition. Thanks! Ric