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Re: [PATCH 0/2] splice: i_mutex vs splice write deadlock

To: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Subject: Re: [PATCH 0/2] splice: i_mutex vs splice write deadlock
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Tue, 19 Jul 2011 14:07:21 +1000
Cc: linux-fsdevel@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx
In-reply-to: <20110719031003.GA18166@xxxxxxxxxxxxx>
References: <1310961884-11634-1-git-send-email-david@xxxxxxxxxxxxx> <20110719031003.GA18166@xxxxxxxxxxxxx>
User-agent: Mutt/1.5.20 (2009-06-14)
On Mon, Jul 18, 2011 at 11:10:03PM -0400, Christoph Hellwig wrote:
> I don't really like this very much.  Not taking the i_mutex at all
> makes the splice_write method in XFS use different locking than
> everyone else, and different from the normal XFS write path.
> For example ocfs2 which has the same locking issues just has an
> own implementation of the splice_write method, which isn't
> too nice but at least marginally better.  I think the right
> fix for both xfs and ocfs2 would be to have a generic_file_splice_write
> variant that takes an "actor" function pointer, which defaults to
> a smaller wrapper around file_remove_suid, file_update_time and
> splice_from_pipe_feed, and then XFS and ocfs2 can provide their
> own actors that add the additional locking.

Yeah I thought about doing that, but wanted to try a simpler version
first. I'll code up the actor variant.


Dave Chinner

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