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From: Ming Lei <ming.lei@redhat.com>
To: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
	Coly Li <colyli@suse.de>,
	linux-bcache@vger.kernel.org, linux-block@vger.kernel.org
Subject: Re: [RFC] cleanup bcache bio handling
Date: Wed, 13 Jun 2018 19:06:41 +0800	[thread overview]
Message-ID: <20180613110640.GA9712@ming.t460p> (raw)
In-Reply-To: <20180613095801.GB15100@kmo-pixel>

On Wed, Jun 13, 2018 at 05:58:01AM -0400, Kent Overstreet wrote:
> On Mon, Jun 11, 2018 at 09:48:00PM +0200, Christoph Hellwig wrote:
> > Hi all,
> > 
> > this series cleans up various places where bcache is way too intimate
> > with bio internals.  This is intended as a baseline for the multi-page
> > biovec work, which requires some nasty workarounds for the existing
> > code.
> > 
> > Note that I do not have a bcache test setup, so this will require
> > some careful actual testing with whatever test cases are used for
> > bcache.
> > 
> > Also the new bio_reused helper should be useful at least for MD raid,
> > but that work is left for later.
> 
> Strong nak on the patch series (except for the patch to not clone in
> bch_data_verify, that patch looks fine).
> 
> Unless something has seriously changed with how multi-page bvecs work since I
> started that code nothing in bcache should be broken by it - Ming, can you
> confirm or deny if that's still correct?

Yes, the multi-page bvecs implementation didn't have big change, and
previously I run xfstests on bcache0, and no regression was observed.

> 
> It is true that bch_bio_map() will be suboptimal when multi page bvecs go in,
> but it won't be broken. The way it's used now is really conflating two different
> things, but where it's used for mapping a bio to a single buffer (i.e. not
> before bio_alloc_pages) that can be switched to something that just creates a
> single bvec.

Yes, multipage bvec shouldn't break any driver or fs.

Thanks,
Ming

  reply	other threads:[~2018-06-13 11:06 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-11 19:48 [RFC] cleanup bcache bio handling Christoph Hellwig
2018-06-11 19:48 ` [PATCH 1/6] block: add a bio_reuse helper Christoph Hellwig
2018-06-12  6:16   ` Kent Overstreet
2018-06-13  7:32     ` Christoph Hellwig
2018-06-13  8:54       ` Kent Overstreet
2018-06-13 13:59         ` Christoph Hellwig
2018-06-13 14:49           ` Kent Overstreet
2018-06-11 19:48 ` [PATCH 2/6] bcache: use bio_reuse instead of bio_reinit where applicable Christoph Hellwig
2018-06-11 19:48 ` [PATCH 3/6] bcache: clean up bio reuse for struct moving_io Christoph Hellwig
2018-06-11 19:48 ` [PATCH 4/6] bcache: clean up bio reuse for struct dirty_io Christoph Hellwig
2018-06-11 19:48 ` [PATCH 5/6] bcache: don't clone bio in bch_data_verify Christoph Hellwig
2018-06-11 19:48 ` [PATCH 6/6] bcache: use bio_add_page instead of open coded bio manipulation Christoph Hellwig
2018-06-12  4:40 ` [RFC] cleanup bcache bio handling Coly Li
2018-06-13  9:58 ` Kent Overstreet
2018-06-13 11:06   ` Ming Lei [this message]
2018-06-13 13:56     ` Christoph Hellwig
2018-06-13 14:54       ` Kent Overstreet
2018-06-14  1:55         ` Ming Lei
2018-06-14  7:20           ` Christoph Hellwig

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