From: Christoph Hellwig <hch@infradead.org>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Jens Axboe <axboe@kernel.dk>, Mark Fasheh <mfasheh@suse.com>,
xfs@oss.sgi.com, Christoph Hellwig <hch@infradead.org>,
Joel Becker <jlbec@evilplan.org>,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 0/5] splice: locking changes and code refactoring
Date: Tue, 14 Jan 2014 05:22:07 -0800 [thread overview]
Message-ID: <20140114132207.GA25170@infradead.org> (raw)
In-Reply-To: <20140113235646.GR10323@ZenIV.linux.org.uk>
On Mon, Jan 13, 2014 at 11:56:46PM +0000, Al Viro wrote:
> On Mon, Jan 13, 2014 at 06:14:16AM -0800, Christoph Hellwig wrote:
> > ping? Would be nice to get this into 3.14
>
> Umm... The reason for pipe_lock outside of ->i_mutex is this:
> default_file_splice_write() calls splice_from_pipe() with
> write_pipe_buf for callback. splice_from_pipe() calls that
> callback under pipe_lock(pipe). And write_pipe_buf() calls
> __kernel_write(), which certainly might want to take ->i_mutex.
>
> Now, this codepath isn't taken for files that have non-NULL
> ->splice_write(), so that's not an issue for XFS and OCFS2,
> but having pipe_lock nest between the ->i_mutex for filesystems
> that do and do not have ->splice_write()... Ouch...
What would be the alternative? Duplicating the code in even more
filesystems to enforce an non-natural locking order for filesystems
actually implementing splice? There don't actually seem to be a whole
lot of real filesystems not implemting splice_write, the prime use
would be for device drivers or synthetic ones. I'm not even sure
how much that fallback gets used in practice.
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WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@infradead.org>
To: Al Viro <viro@ZenIV.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>,
Jens Axboe <axboe@kernel.dk>, Mark Fasheh <mfasheh@suse.com>,
Joel Becker <jlbec@evilplan.org>,
linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com
Subject: Re: [PATCH 0/5] splice: locking changes and code refactoring
Date: Tue, 14 Jan 2014 05:22:07 -0800 [thread overview]
Message-ID: <20140114132207.GA25170@infradead.org> (raw)
In-Reply-To: <20140113235646.GR10323@ZenIV.linux.org.uk>
On Mon, Jan 13, 2014 at 11:56:46PM +0000, Al Viro wrote:
> On Mon, Jan 13, 2014 at 06:14:16AM -0800, Christoph Hellwig wrote:
> > ping? Would be nice to get this into 3.14
>
> Umm... The reason for pipe_lock outside of ->i_mutex is this:
> default_file_splice_write() calls splice_from_pipe() with
> write_pipe_buf for callback. splice_from_pipe() calls that
> callback under pipe_lock(pipe). And write_pipe_buf() calls
> __kernel_write(), which certainly might want to take ->i_mutex.
>
> Now, this codepath isn't taken for files that have non-NULL
> ->splice_write(), so that's not an issue for XFS and OCFS2,
> but having pipe_lock nest between the ->i_mutex for filesystems
> that do and do not have ->splice_write()... Ouch...
What would be the alternative? Duplicating the code in even more
filesystems to enforce an non-natural locking order for filesystems
actually implementing splice? There don't actually seem to be a whole
lot of real filesystems not implemting splice_write, the prime use
would be for device drivers or synthetic ones. I'm not even sure
how much that fallback gets used in practice.
next prev parent reply other threads:[~2014-01-14 13:22 UTC|newest]
Thread overview: 82+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-12 18:14 [PATCH 0/5] splice: locking changes and code refactoring Christoph Hellwig
2013-12-12 18:14 ` Christoph Hellwig
2013-12-12 18:15 ` [PATCH 1/5] splice: move balance_dirty_pages_ratelimited into pipe_to_file Christoph Hellwig
2013-12-12 18:15 ` Christoph Hellwig
2013-12-12 18:15 ` [PATCH 2/5] splice: nest i_mutex outside pipe_lock Christoph Hellwig
2013-12-12 18:15 ` Christoph Hellwig
2013-12-12 18:15 ` [PATCH 3/5] splice: use splice_from_pipe in generic_file_splice_write Christoph Hellwig
2013-12-12 18:15 ` Christoph Hellwig
2013-12-12 18:15 ` [PATCH 4/5] xfs: fix splice_write locking Christoph Hellwig
2013-12-12 18:15 ` Christoph Hellwig
2013-12-12 18:15 ` [PATCH 5/5] splice: stop exporting splice_from_pipe implementation details Christoph Hellwig
2013-12-12 18:15 ` Christoph Hellwig
2014-01-13 14:14 ` [PATCH 0/5] splice: locking changes and code refactoring Christoph Hellwig
2014-01-13 14:14 ` Christoph Hellwig
2014-01-13 23:56 ` Al Viro
2014-01-13 23:56 ` Al Viro
2014-01-14 13:22 ` Christoph Hellwig [this message]
2014-01-14 13:22 ` Christoph Hellwig
2014-01-14 17:20 ` Al Viro
2014-01-14 17:20 ` Al Viro
2014-01-15 18:10 ` Al Viro
2014-01-15 18:10 ` Al Viro
2014-01-18 6:40 ` Al Viro
2014-01-18 7:22 ` Linus Torvalds
2014-01-18 7:22 ` Linus Torvalds
2014-01-18 7:46 ` Al Viro
2014-01-18 7:56 ` Al Viro
2014-01-18 7:56 ` Al Viro
2014-01-18 8:27 ` Al Viro
2014-01-18 8:44 ` David Miller
2014-01-18 8:44 ` David Miller
2014-02-07 17:10 ` Al Viro
2014-02-07 17:10 ` Al Viro
2014-01-18 19:59 ` Linus Torvalds
2014-01-18 20:10 ` Al Viro
2014-01-18 20:27 ` Al Viro
2014-01-18 20:27 ` Al Viro
2014-01-18 20:30 ` Al Viro
2014-01-18 20:30 ` Al Viro
2014-01-19 5:13 ` [RFC] unifying write variants for filesystems Al Viro
2014-01-19 5:13 ` Al Viro
2014-01-20 13:55 ` Christoph Hellwig
2014-01-20 13:55 ` Christoph Hellwig
2014-01-20 20:32 ` Linus Torvalds
2014-01-20 20:32 ` Linus Torvalds
2014-02-01 22:43 ` Al Viro
2014-02-01 22:43 ` Al Viro
2014-02-02 0:13 ` Linus Torvalds
2014-02-02 2:02 ` Al Viro
2014-02-02 2:02 ` Al Viro
2014-02-02 19:21 ` Al Viro
2014-02-02 19:21 ` Al Viro
2014-02-02 19:23 ` Al Viro
2014-02-02 19:23 ` Al Viro
2014-02-03 14:41 ` Miklos Szeredi
2014-02-03 14:41 ` Miklos Szeredi
2014-02-03 15:33 ` Al Viro
2014-02-03 15:33 ` Al Viro
2014-02-02 23:16 ` Anton Altaparmakov
2014-02-02 23:16 ` Anton Altaparmakov
2014-02-03 15:12 ` Christoph Hellwig
2014-02-03 16:24 ` Al Viro
2014-02-03 16:50 ` Dave Kleikamp
2014-02-03 16:23 ` Dave Kleikamp
2014-02-04 12:44 ` Al Viro
2014-02-04 12:44 ` Al Viro
2014-02-04 12:52 ` Kent Overstreet
2014-02-04 12:52 ` Kent Overstreet
2014-02-04 15:17 ` Al Viro
2014-02-04 15:17 ` Al Viro
2014-02-04 17:27 ` Zach Brown
2014-02-04 17:35 ` Kent Overstreet
2014-02-04 18:08 ` Al Viro
2014-02-04 18:08 ` Al Viro
2014-02-04 18:00 ` Al Viro
2014-02-04 18:00 ` Al Viro
2014-02-04 18:33 ` Zach Brown
2014-02-04 18:36 ` Al Viro
2014-02-04 18:36 ` Al Viro
2014-02-05 19:58 ` Al Viro
2014-02-05 20:42 ` Zach Brown
2014-02-06 9:08 ` Kent Overstreet
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