linux-kernel - Re: 2.6.21-git10/11: files getting truncated on xfs? or maybe an nlink problem?

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Message-ID: <4645D594.4070801@goop.org>
Date:	Sat, 12 May 2007 07:56:20 -0700
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	David Chinner <dgc@....com>
CC:	Jan Engelhardt <jengelh@...ux01.gwdg.de>,
	Chuck Ebbert <cebbert@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Matt Mackall <mpm@...enic.com>, xfs@....sgi.com
Subject: Re: 2.6.21-git10/11: files getting truncated on xfs? or maybe an
 nlink problem?

David Chinner wrote:
> What I don't understand is that on unmount dirty xfs inodes get
> written out. Clearly this is not happening - either there's a hole
> in the writeback logic (unlikely - it was unchanged) or we've missed
> some case where we need to update the filesize and mark the inode
> dirty.
>
> Hmmmm - if the write was just a short append to the file, then the
> block that was written to should already be mapped. Then we'll just
> look up the extent by doing a BMAPI_READ lookup, set the type to
> IOMAP_READ and add the block to ioend we are building.
>   

Well, that result I mailed you showed that the difference was just over
16k, and that there was a 32 block difference in the final extent
length.  Does that fit with this theory?

> The type IOMAP_READ determines the I/O completion behaviour - in this case
> it is xfs_end_bio_read(), which fails to update the file size....
>
> Bingo.
>
> A patch for you to try, Jeremy. I've just started a test run on it...
>   

Thanks, I'll give it a spin.  Have you reproduced the bug yourself?


    J
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