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Re: PM / hibernate xfs lock up / xfs_reclaim_inodes_ag

To: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Subject: Re: PM / hibernate xfs lock up / xfs_reclaim_inodes_ag
From: Nigel Cunningham <nigel@xxxxxxxxxxxx>
Date: Wed, 27 Jul 2011 22:22:47 +1000
Cc: "Rafael J. Wysocki" <rjw@xxxxxxx>, Dave Chinner <david@xxxxxxxxxxxxx>, Christoph <cr2005@xxxxxxxxx>, Linux PM mailing list <linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx>, Pavel Machek <pavel@xxxxxx>, xfs@xxxxxxxxxxx
In-reply-to: <20110727103308.GA20805@xxxxxxxxxxxxx>
References: <4E1C70AD.1010101@xxxxxxxxx> <201107262228.12099.rjw@xxxxxxx> <20110727004543.GE8048@dastard> <201107271135.13297.rjw@xxxxxxx> <20110727103308.GA20805@xxxxxxxxxxxxx>
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Hi.

On 27/07/11 20:33, Christoph Hellwig wrote:
> On Wed, Jul 27, 2011 at 11:35:13AM +0200, Rafael J. Wysocki wrote:
>> The Pavel's objection, if I remember it correctly, was that some
>> (or the majority of?) filesystems didn't implement the freezing operation,
>> so they would be more vulnerable to data loss in case of a failing 
>> hibernation
>> after this change.  However, that's better than actively causing pain to XFS
>> users.
> 
> The objection never made sense and only means he never read the code.
> freeze_super (or freeze_bdev back then) always does a sync_filesystem
> before even checking if we have a freeze method, and sync_filesystem is
> what we iterate over for each superblock in sync().

I've had freezing supers in TOI for a couple of years now and it has
only ever helped. To be honest, if you have a ton of dirty pages, it
does result in a big delay, but that's the worst of it.

Regards,

Nigel
-- 
Evolution (n): A hypothetical process whereby improbable
events occur with alarming frequency, order arises from chaos, and
no one is given credit.

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