From: Christoph Hellwig <hch@infradead.org>
To: Josef Bacik <josef@toxicpanda.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Goldwyn Rodrigues <rgoldwyn@suse.de>,
linux-fsdevel@vger.kernel.org, riteshh@linux.ibm.com,
linux-ext4@vger.kernel.org, darrick.wong@oracle.com,
willy@infradead.org, linux-btrfs@vger.kernel.org
Subject: Re: [PATCH v2] iomap: return partial I/O count on error in iomap_dio_bio_actor
Date: Fri, 20 Mar 2020 07:35:00 -0700 [thread overview]
Message-ID: <20200320143500.GA16143@infradead.org> (raw)
In-Reply-To: <02209ec3-62b4-595f-b84e-2cd8838ac41b@toxicpanda.com>
On Fri, Mar 20, 2020 at 10:23:43AM -0400, Josef Bacik wrote:
> I'm not sure what you're looking at specifically wrt error handling, but I
> can explain __endio_write_update_ordered.
>
> Btrfs has ordered extents to keep track of an extent that currently has IO
> being done on it. Generally that IO takes multiple bio's, so we keep track
> of the outstanding size of the IO being done, and each bio completes and
> thus removes its size from the pending size. If any one of those bios has
> an error we need to make sure we discard the whole ordered extent, as part
> of it won't be valid. Just a cursory look at the current code I assume
> that's what's confusing you, we call this when we have an error in the
> O_DIRECT code. This is just so we get the proper cleanup for the ordered
> extent. People will wait on the ordered extent to be completed, so if we've
> started an ordered extent and aren't able to complete the range we need to
> do __endio_write_update_ordered() so that the ordered extent is finished and
> we wakeup any waiters.
>
> Does this help? If I need to I can context switch into whatever you're
> looking at, but I'm going to avoid looking and hope I can just shout useful
> information in your direction ;). Thanks,
Yes, this helps a lot. This is about the patches from Goldwyn to
convert btrfs to use the iomap direct I/O code. And in that series
he currently calls __endio_write_update_ordered from the ->iomap_end
method, which for direct I/O is called after all bios are submitted
to complete ordered extents for a range after an I/O error, that
is one that no I/O has been submitted to, and the accounting for that
is a little complicated..
next prev parent reply other threads:[~2020-03-20 14:35 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-19 15:08 [PATCH v2] iomap: return partial I/O count on error in iomap_dio_bio_actor Goldwyn Rodrigues
2020-03-20 14:05 ` Christoph Hellwig
2020-03-20 14:23 ` Josef Bacik
2020-03-20 14:35 ` Christoph Hellwig [this message]
2020-03-20 15:35 ` Goldwyn Rodrigues
-- strict thread matches above, loose matches on Subject: below --
2020-02-20 15:24 Goldwyn Rodrigues
2020-02-20 15:23 Goldwyn Rodrigues
2020-02-20 17:42 ` Matthew Wilcox
2020-02-21 2:06 ` Goldwyn Rodrigues
2020-02-21 4:51 ` Ritesh Harjani
2020-02-21 12:48 ` Goldwyn Rodrigues
2020-02-25 20:53 ` Christoph Hellwig
2020-02-26 2:12 ` Damien Le Moal
2020-02-26 2:55 ` Goldwyn Rodrigues
2020-02-28 19:44 ` Goldwyn Rodrigues
2020-02-28 19:59 ` Matthew Wilcox
2020-02-28 20:35 ` Goldwyn Rodrigues
2020-03-02 13:31 ` Christoph Hellwig
2020-02-21 13:14 ` David Sterba
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