From: Christoph Hellwig <hch@lst.de>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>, Chris Mason <clm@fb.com>,
Josef Bacik <josef@toxicpanda.com>,
David Sterba <dsterba@suse.com>,
linux-btrfs@vger.kernel.org, linux-xfs@vger.kernel.org,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 2/5] iomap: add per-iomap_iter private data
Date: Thu, 5 May 2022 20:15:43 +0200 [thread overview]
Message-ID: <20220505181543.GA814@lst.de> (raw)
In-Reply-To: <20220505163219.GJ27195@magnolia>
On Thu, May 05, 2022 at 09:32:19AM -0700, Darrick J. Wong wrote:
> > No need to transfer it back. It ist just a creative way to pass private
> > data in. Initially I just added yet another argument to iomap_dio_rw,
> > and maybe I should just go back to that to make the things easier to
> > follow.
>
> Hmm. Who owns iocb->private? AFAICT there are two users of it -- the
> directio code uses it to store bios for polling; and then there's ocfs2,
> which apparently uses it for iocb lock state(!) flags.
Yeah.
> Getting back to iomap, I think the comment before __iomap_dio_rw should
> state that iocb->private will be transferred to iter->private to make
> that relationship more obvious, in case ocfs2 ever stumbles into iomap
> and explodes on impact.
I think I'll just look into passing an extra argument instead. It
is pretty clear that using iocb->private was a little too clever and
takes experienced file system developers way too much time to understand.
next prev parent reply other threads:[~2022-05-05 18:16 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-04 16:23 reduce memory allocation in the btrfs direct I/O path Christoph Hellwig
2022-05-04 16:23 ` [PATCH 1/5] iomap: allow the file system to provide a bio_set for direct I/O Christoph Hellwig
2022-05-05 15:38 ` Darrick J. Wong
2022-05-04 16:23 ` [PATCH 2/5] iomap: add per-iomap_iter private data Christoph Hellwig
2022-05-05 8:06 ` Nikolay Borisov
2022-05-05 15:06 ` Christoph Hellwig
2022-05-05 15:41 ` Darrick J. Wong
2022-05-05 15:45 ` Christoph Hellwig
2022-05-05 16:32 ` Darrick J. Wong
2022-05-05 18:15 ` Christoph Hellwig [this message]
2022-05-05 18:18 ` Darrick J. Wong
2022-05-04 16:23 ` [PATCH 3/5] btrfs: add a btrfs_dio_rw wrapper Christoph Hellwig
2022-05-04 16:23 ` [PATCH 4/5] btrfs: allocate dio_data on stack Christoph Hellwig
2022-05-04 16:23 ` [PATCH 5/5] btrfs: allocate the btrfs_dio_private as part of the iomap dio bio Christoph Hellwig
2022-05-05 8:12 ` Nikolay Borisov
2022-05-05 15:07 ` Christoph Hellwig
2022-05-05 15:20 ` David Sterba
2022-05-05 15:52 ` David Sterba
2022-05-05 8:33 ` reduce memory allocation in the btrfs direct I/O path Nikolay Borisov
2022-05-05 15:55 ` David Sterba
2022-05-06 17:18 ` Darrick J. Wong
2022-05-07 5:26 ` Christoph Hellwig
2022-05-09 18:46 ` David Sterba
2022-05-10 3:33 ` Darrick J. Wong
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