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Date: Wed, 16 Jul 2025 14:17:45 +0200
From: Christoph Hellwig <hch@lst.de>
To: Coly Li <i@coly.li>
Cc: Christoph Hellwig <hch@lst.de>, Coly Li <colyli@kernel.org>,
	linux-raid@vger.kernel.org, linux-block@vger.kernel.org,
	Yu Kuai <yukuai3@huawei.com>, Xiao Ni <xni@redhat.com>,
	Hannes Reinecke <hare@suse.de>, Martin Wilck <mwilck@suse.com>,
	Keith Busch <kbusch@kernel.org>
Subject: Re: [RFC PATCH] md: split bio by io_opt size in md_submit_bio()
Message-ID: <20250716121745.GA2700@lst.de>
References: <20250715180241.29731-1-colyli@kernel.org> <20250716113737.GA31369@lst.de> <437E98DD-7D64-49BF-9F2C-04CB0A142A88@coly.li> <20250716114121.GA32207@lst.de> <D12A8BDA-5C2B-4FA7-9C92-731BD321A611@coly.li> <20250716114533.GA32631@lst.de> <danlsghtalte7sku3vlfxkgngujgwzspanfayaxy4jfnk54jbf@yfvmr5plavmp> <20250716121449.GB2043@lst.de> <DE36C995-4014-44DC-A998-1C4FF9AFD7F9@coly.li>
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On Wed, Jul 16, 2025 at 08:16:34PM +0800, Coly Li wrote:
> 
> 
> > 2025年7月16日 20:14，Christoph Hellwig <hch@lst.de> 写道：
> > 
> > On Wed, Jul 16, 2025 at 08:10:33PM +0800, Coly Li wrote:
> >> Just like hanlding discard requests, handling raid5 read/write bios should
> >> try to split the large bio into opt_io_size aligned both *offset* and
> >> *length*. If I understand correctly, bio_split_to_limits() doesn't handle
> >> offset alignment for read5 read/write bios.
> > 
> > Well, if you want offset alignment, set chunk_sectors.
> > 
> 
> Do you mean setting max_hw_sectors as chunk_sectors?

Setting both to the desired value (full stipe width).