linux-ext4 - Re: [URGENT PATCH] ext4: fix potential deadlock in ext4_evict

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Message-ID: <20110826202251.GD5176@thunk.org>
Date:	Fri, 26 Aug 2011 16:22:51 -0400
From:	Ted Ts'o <tytso@....edu>
To:	Jiaying Zhang <jiayingz@...gle.com>
Cc:	Tao Ma <tm@....ma>, Dave Chinner <david@...morbit.com>,
	linux-ext4@...r.kernel.org
Subject: Re: [URGENT PATCH] ext4: fix potential deadlock in
 ext4_evict_inode()

On Fri, Aug 26, 2011 at 09:58:45AM -0700, Jiaying Zhang wrote:
> Now thinking about an alternative approach to resolve the deadlock
> mentioned above, maybe we can use mutex_trylock() in
> ext4_end_io_work() and if we can't grab the mutex lock for an inode,
> just requeue the work to the end of workqueue?

Good idea!  That should speed up work queue processing in general, I
think.

The downside is that inodes that currently locked might take longer to
complete.  In the case of fsync() we'll just force the I/O completion
to happen in the context of the fsync'ing process, so I don't think it
should be a problem in practice I think.

					- Ted
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