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Re: [PATCH 3/3] Add timeout feature

To: "Ric Wheeler" <rwheeler@xxxxxxxxxx>, "Christoph Hellwig" <hch@xxxxxxxxxxxxx>
Subject: Re: [PATCH 3/3] Add timeout feature
From: "Takashi Sato" <t-sato@xxxxxxxxxxxxx>
Date: Fri, 26 Sep 2008 17:52:35 +0900
Cc: "Andrew Morton" <akpm@xxxxxxxxxxxxxxxxxxxx>, "Oleg Nesterov" <oleg@xxxxxxxxxx>, <linux-fsdevel@xxxxxxxxxxxxxxx>, <dm-devel@xxxxxxxxxx>, <viro@xxxxxxxxxxxxxxxxxx>, <linux-ext4@xxxxxxxxxxxxxxx>, <xfs@xxxxxxxxxxx>, <axboe@xxxxxxxxx>, <mtk.manpages@xxxxxxxxxxxxxx>, <linux-kernel@xxxxxxxxxxxxxxx>
In-reply-to: <48DBFD42.6030307@xxxxxxxxxx>
References: <20080908205337t-sato@xxxxxxxxxxxxxxx> <20080908171119.GB22521@xxxxxxxxxxxxx> <48DBFD42.6030307@xxxxxxxxxx>

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 
be solved?
If so, I will implement it.

Cheers, Takashi

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