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From: Christoph Hellwig <hch@lst.de>
To: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@lst.de>,
	"Darrick J . Wong" <darrick.wong@oracle.com>,
	Damien Le Moal <Damien.LeMoal@wdc.com>,
	Andreas Gruenbacher <agruenba@redhat.com>,
	linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 11/12] iomap: move the xfs writeback code to iomap.c
Date: Tue, 25 Jun 2019 12:10:20 +0200	[thread overview]
Message-ID: <20190625101020.GI1462@lst.de> (raw)
In-Reply-To: <20190624234304.GD7777@dread.disaster.area>

On Tue, Jun 25, 2019 at 09:43:04AM +1000, Dave Chinner wrote:
> I'm a little concerned this is going to limit what we can do
> with the XFS IO path because now we can't change this code without
> considering the direct impact on other filesystems. The QA burden of
> changing the XFS writeback code goes through the roof with this
> change (i.e. we can break multiple filesystems, not just XFS).

Going through the roof is a little exaggerated.  Yes, it will be more
testing overhead, but that is life in a world where we try to share
code rather than duplicating it, which is pretty much a general
kernel policy that has served us well.

> The writepage code is one of the areas that, historically speaking,
> has one of the highest rates of modification in XFS - we've
> substantially reworked this code from top to bottom 4 or 5 times in
> a bit over ten years, and each time it's been removing abstraction
> layers and getting the writeback code closer to the internal XFS
> extent mapping infrastructure.

I don't think we had all that much churn.  Yes, we've improved it a
lot, but much of that was in response to core changes, and pretty much
all of it benefits other users as well.  And the more users we have
for this infrastructure that more clout it has with core VM folks
when we have to push back odd design decisions.

  reply	other threads:[~2019-06-25 10:10 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-24  5:52 lift the xfs writepage code into iomap Christoph Hellwig
2019-06-24  5:52 ` [PATCH 01/12] list.h: add a list_pop helper Christoph Hellwig
2019-06-24 14:53   ` Darrick J. Wong
2019-06-24 15:51   ` Matthew Wilcox
2019-06-25 10:06     ` Christoph Hellwig
2019-06-24  5:52 ` [PATCH 02/12] xfs: simplify xfs_chain_bio Christoph Hellwig
2019-06-24 15:14   ` Darrick J. Wong
2019-06-24  5:52 ` [PATCH 03/12] xfs: fix a comment typo in xfs_submit_ioend Christoph Hellwig
2019-06-24 14:53   ` Darrick J. Wong
2019-06-24  5:52 ` [PATCH 04/12] xfs: initialize ioma->flags in xfs_bmbt_to_iomap Christoph Hellwig
2019-06-24 14:57   ` Darrick J. Wong
2019-06-25 10:07     ` Christoph Hellwig
2019-06-25 15:13       ` Darrick J. Wong
2019-06-25 15:21         ` Christoph Hellwig
2019-06-24  5:52 ` [PATCH 05/12] xfs: use a struct iomap in xfs_writepage_ctx Christoph Hellwig
2019-06-24 15:50   ` Darrick J. Wong
2019-06-24  5:52 ` [PATCH 06/12] xfs: remove XFS_TRANS_NOFS Christoph Hellwig
2019-06-24 15:58   ` Darrick J. Wong
2019-06-24 22:59   ` Dave Chinner
2019-06-25 10:12     ` Christoph Hellwig
2019-06-24  5:52 ` [PATCH 07/12] xfs: don't preallocate a transaction for file size updates Christoph Hellwig
2019-06-24 16:17   ` Darrick J. Wong
2019-06-24 23:15     ` Dave Chinner
2019-06-25 10:25       ` Christoph Hellwig
2019-06-27 22:23         ` Dave Chinner
2019-06-24  5:52 ` [PATCH 08/12] xfs: simplify xfs_ioend_can_merge Christoph Hellwig
2019-06-24 16:00   ` Darrick J. Wong
2019-06-24  5:52 ` [PATCH 09/12] xfs: refactor the ioend merging code Christoph Hellwig
2019-06-24 16:04   ` Darrick J. Wong
2019-06-24 16:06   ` Nikolay Borisov
2019-06-25 10:14     ` Christoph Hellwig
2019-06-25 12:42       ` Nikolay Borisov
2019-06-25 14:45         ` Darrick J. Wong
2019-06-24  5:52 ` [PATCH 10/12] xfs: remove the fork fields in the writepage_ctx and ioend Christoph Hellwig
2019-06-24 16:08   ` Darrick J. Wong
2019-06-24  5:52 ` [PATCH 11/12] iomap: move the xfs writeback code to iomap.c Christoph Hellwig
2019-06-24 15:46   ` Darrick J. Wong
2019-06-25 10:08     ` Christoph Hellwig
2019-06-24 23:43   ` Dave Chinner
2019-06-25 10:10     ` Christoph Hellwig [this message]
2019-06-28  0:45       ` Dave Chinner
2019-06-28  5:33         ` Christoph Hellwig
2019-07-01  0:08           ` Dave Chinner
2019-07-01  6:43             ` Christoph Hellwig
2019-07-01 23:09               ` Dave Chinner
2019-06-28 22:27         ` Luis Chamberlain
2019-07-11 21:31           ` Brendan Higgins
2019-06-24  5:52 ` [PATCH 12/12] iomap: add tracing for the address space operations Christoph Hellwig
2019-06-24 23:49   ` Dave Chinner
2019-06-25 10:15     ` Christoph Hellwig
2019-06-25 14:47       ` Darrick J. Wong
2019-06-27 22:35       ` Dave Chinner

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