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From: Christoph Hellwig <hch@infradead.org>
To: Takashi Sato <t-sato@yk.jp.nec.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	Andreas Dilger <adilger@sun.com>, Theodore Tso <tytso@MIT.EDU>,
	linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [RFC] ext3 freeze feature
Date: Sat, 16 Feb 2008 08:25:02 -0500	[thread overview]
Message-ID: <20080216132502.GB1344@infradead.org> (raw)
In-Reply-To: <79B050214DA541F9A8B193C7AACC3C7B@nsl.ad.nec.co.jp>

On Fri, Feb 15, 2008 at 08:51:15PM +0900, Takashi Sato wrote:
> So XFS_IOC_FREEZE and XFS_IOC_THAW cannot be lifted to generic code simply.
> I think we should create new generic numbers for freeze and thaw

Actually we've lifted specific ioctls to the generic layer before all
the time in drivers.  That's the only way to make functionality that was
specific to a single driver (or in this case filesystem) generic.  If
the numbering issues confuses you make sure to add a big comment
describing it

> And xfs_freeze calls XFS_IOC_FREEZE with a magic number 1, but what is 1?

As Eric said it's ignored.

> Instead, I'd like the sec to timeout on freeze API in order to thaw
> the filesystem automatically.  It can prevent a filesystem from staying
> frozen forever.
> (Because a freezer may cause a deadlock by accessing the frozen filesystem.)

Timeout based locking is generally a horrible idea, there's a reason
we don't have any primitives for that in the kernel :)

  parent reply	other threads:[~2008-02-16 13:25 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             ` Christoph Hellwig [this message]
2008-02-13  8:23     ` [RFC] ext3 freeze feature Takashi Sato
2008-01-26  5:35 ` David Chinner
2008-01-26  5:39   ` David Chinner
2008-01-28 13:07   ` Takashi Sato

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