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Date: Mon, 29 Sep 2008 09:36:04 -0500
From: Eric Sandeen <sandeen@sandeen.net>
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To: Christoph Hellwig <hch@infradead.org>
CC: Takashi Sato <t-sato@yk.jp.nec.com>, Ric Wheeler <rwheeler@redhat.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       Oleg Nesterov <oleg@tv-sign.ru>, linux-fsdevel@vger.kernel.org,
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       linux-ext4@vger.kernel.org, xfs@oss.sgi.com, axboe@kernel.dk,
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Subject: Re: [PATCH 3/3] Add timeout feature
References: <20080908205337t-sato@mail.jp.nec.com> <20080908171119.GB22521@infradead.org> <48DBFD42.6030307@redhat.com> <D0B0D91F884647D6808626CDFF81E532@nsl.ad.nec.co.jp> <20080929141326.GA31781@infradead.org>
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Christoph Hellwig wrote:
> On Fri, Sep 26, 2008 at 05:52:35PM +0900, Takashi Sato wrote:
>> 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.
> 
> What timeout should happen?  the freeze ioctl must not return until the
> filesystem is a clean state and all writes are blocked.

The suggestion was that *UN*freeze would return ETIMEDOUT if the
filesystem had already unfrozen itself, I think.  That way you know that
the snapshot you just took is worthless, at least.

I'm still not really sold on the timeout, but I think the above was the
intent.

-Eric