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From: Christoph Hellwig <hch@lst.de>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org, Jan Kara <jack@suse.cz>,
	Joel Becker <joel.becker@oracle.com>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [WTFoTW] ->quota_on() deadlocks
Date: Fri, 2 Jul 2010 12:25:04 +0200	[thread overview]
Message-ID: <20100702102504.GA24016@lst.de> (raw)
In-Reply-To: <20100701223822.GA495@lst.de>

On Fri, Jul 02, 2010 at 12:38:22AM +0200, Christoph Hellwig wrote:
> I have patches in my queue that should fix this as a side effect.
> 
> First thing is splitting the set_xstate method currently only
> used by XFS into ->quota_enable, ->quota_disable and ->quota_remove,
> second is using merging ->quota_disable and ->quota_off, third
> is switching ocfs2 to ->quota_disable and fourth is taking the
> path lookup from ->quota_on into the caller.
> 
> I'll try to get them out to the list in a couple of days.

Shouldn't have replied in the middle of the night.  The above doesn't
fix the deadlock yet, but by allowing different methods would allow to
fix it in hacky ways.

Now the real questions is: do we need to support quota files on
different filesystems?  For ext3/4 and reiserfs with journaled quota
we already reject that.  If we always reject it or even further restrict
quota files to sit in the root of the filesystem we can replace the
kernel_path with a relative lookup that doesn't cross mountpoints.
In the idea case of restricting it to the root that would be just a
lookup_one_len, just as we do in dquot_quota_on_mount, otherwise
something hand crafted.

  reply	other threads:[~2010-07-02 10:26 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-07-01 18:56 [WTFoTW] ->quota_on() deadlocks Al Viro
2010-07-01 22:38 ` Christoph Hellwig
2010-07-02 10:25   ` Christoph Hellwig [this message]
2010-07-02 20:13 ` Jan Kara

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