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From: "Takashi Sato" <t-sato@yk.jp.nec.com>
To: "David Chinner" <dgc@sgi.com>
Cc: <linux-kernel@vger.kernel.org>, <linux-fsdevel@vger.kernel.org>,
	<linux-ext4@vger.kernel.org>
Subject: Re: [RFC] ext3 freeze feature
Date: Mon, 28 Jan 2008 22:07:38 +0900	[thread overview]
Message-ID: <01c801c861ae$c2349990$41a8400a@bsd.tnes.nec.co.jp> (raw)
In-Reply-To: <20080126053526.GN155407@sgi.com>

Hi,

Thank you for your comments.

> That's inherently unsafe - you can have multiple unfreezes
> running in parallel which seriously screws with the bdev semaphore
> count that is used to lock the device due to doing multiple up()s
> for every down.
> 
> Your timeout thingy guarantee that at some point you will get
> multiple up()s occuring due to the timer firing racing with
> a thaw ioctl. 
> 
> If this interface is to be more widely exported, then it needs
> a complete revamp of the bdev is locked while it is frozen so
> that there is no chance of a double up() ever occuring on the
> bd_mount_sem due to racing thaws.....

My patch has the race condition as you said.
I will fix it.

Cheers, Takashi 


      parent reply	other threads:[~2008-01-28 13:08 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-01-25 10:59 Takashi Sato
2008-01-25 11:17 ` Pekka Enberg
2008-01-25 12:42   ` Takashi Sato
2008-01-26  5:17     ` David Chinner
2008-01-26 19:10     ` Christoph Hellwig
2008-01-25 12:18 ` Dmitri Monakhov
2008-01-25 13:33   ` Theodore Tso
2008-01-25 16:34     ` Eric Sandeen
2008-01-25 16:42       ` Theodore Tso
2008-02-02 13:52         ` Pavel Machek
2008-01-28 13:13     ` Takashi Sato
2008-02-01  3:03       ` Kazuto Miyoshi
2008-01-31  8:53     ` Daniel Phillips
2008-02-07  1:05     ` Takashi Sato
2008-02-08 10:48     ` Takashi Sato
2008-02-08 13:26       ` Andreas Dilger
2008-02-08 14:59         ` Christoph Hellwig
2008-02-15 11:51           ` Takashi Sato
2008-02-15 14:24             ` Eric Sandeen
2008-02-19 11:27               ` t-sato
2008-02-26  8:20                 ` [RFC] ext3 freeze feature ver 0.2 Takashi Sato
2008-02-26 16:39                   ` Eric Sandeen
2008-02-26 17:08                     ` Andreas Dilger
2008-02-27  8:31                       ` Takashi Sato
2008-03-07  9:13                 ` [RFC] freeze feature ver 1.0 Takashi Sato
2008-02-16 13:25             ` [RFC] ext3 freeze feature Christoph Hellwig
2008-02-13  8:23     ` Takashi Sato
2008-01-26  5:35 ` David Chinner
2008-01-26  5:39   ` David Chinner
2008-01-28 13:07   ` Takashi Sato [this message]

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