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Date: Thu, 12 Sep 2024 17:10:38 +0200
From: Christoph Hellwig <hch@lst.de>
To: John Garry <john.g.garry@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>, axboe@kernel.dk, song@kernel.org,
	yukuai3@huawei.com, kbusch@kernel.org, sagi@grimberg.me,
	James.Bottomley@HansenPartnership.com, martin.petersen@oracle.com,
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	linux-raid@vger.kernel.org, linux-nvme@lists.infradead.org,
	linux-scsi@vger.kernel.org
Subject: Re: [PATCH RFC 4/4] md/raid0: Atomic write support
Message-ID: <20240912151038.GA5858@lst.de>
References: <20240903150748.2179966-1-john.g.garry@oracle.com> <20240903150748.2179966-5-john.g.garry@oracle.com> <20240912131803.GD29641@lst.de> <340e4306-4442-4276-b420-6fee8ed97a7e@oracle.com>
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On Thu, Sep 12, 2024 at 03:48:09PM +0100, John Garry wrote:
>
> I actually now think that I should change bio_split() to return NULL for 
> splitting a REQ_ATOMIC, like what do for ZONE_APPEND - calling bio_split() 
> like this is a common pattern in md RAID personalities. However, none of 
> the md RAID code check for a NULL split, which they really should, so I can 
> make that change also.

bio_split is a bit of a mess - even NULL isn't very good at returning
what caused it to fail.  Maybe a switch to ERR_PTR and an audit of
all callers might be a good idea.