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From: Christoph Hellwig <hch@lst.de>
To: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>,
	linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 2/2] fs: update atime before I/O in generic_file_read_iter
Date: Tue, 4 Oct 2016 13:48:30 +0200	[thread overview]
Message-ID: <20161004114830.GA2359@lst.de> (raw)
In-Reply-To: <20161004081324.GC17515@quack2.suse.cz>

On Tue, Oct 04, 2016 at 10:13:24AM +0200, Jan Kara wrote:
> But frankly it looks like a nasty catch that iocb->ki_filp can go away
> under you in the AIO case. Do I get it right that this means there must be
> some other thread closing your fd while the read is running, right?

Yes, that's what generic/323 tests.

> Also it seems that file_end_write(file) call in aio_run_iocb() is prone to
> the same race?

Indeed.  That's easy to fix by moving the file_end_write to aio_complete,
though.

> Won't we be better off to just to do additional get_file() / fput() pair in
> the AIO submission path so that whole AIO submission path is guaranteed to
> have struct file available? I understand this is very performance sensitive
> path but we'll be adding just two atomic ops...

I'd rather avoid those if we can.  But a big comment and some refactoring
in this area would be useful to make that easier to understand.

  reply	other threads:[~2016-10-04 11:48 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-30  8:46 fix struct file use after free in the AIO read path Christoph Hellwig
2016-09-30  8:46 ` [PATCH 1/2] xfs: update atime before I/O in xfs_file_dio_aio_read Christoph Hellwig
2016-09-30  8:46 ` [PATCH 2/2] fs: update atime before I/O in generic_file_read_iter Christoph Hellwig
2016-10-04  8:13   ` Jan Kara
2016-10-04 11:48     ` Christoph Hellwig [this message]
2016-10-05  8:29       ` Jan Kara

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