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Date: Wed, 22 May 2024 10:58:33 -0700
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Subject: Re: [PATCH v20 02/12] Add infrastructure for copy offload in block
 and request layer.
To: Nitesh Shetty <nj.shetty@samsung.com>
Cc: Jens Axboe <axboe@kernel.dk>, Jonathan Corbet <corbet@lwn.net>,
 Alasdair Kergon <agk@redhat.com>, Mike Snitzer <snitzer@kernel.org>,
 Mikulas Patocka <mpatocka@redhat.com>, Keith Busch <kbusch@kernel.org>,
 Christoph Hellwig <hch@lst.de>, Sagi Grimberg <sagi@grimberg.me>,
 Chaitanya Kulkarni <kch@nvidia.com>, Alexander Viro
 <viro@zeniv.linux.org.uk>, Christian Brauner <brauner@kernel.org>,
 Jan Kara <jack@suse.cz>, martin.petersen@oracle.com, david@fromorbit.com,
 hare@suse.de, damien.lemoal@opensource.wdc.com, anuj20.g@samsung.com,
 joshi.k@samsung.com, nitheshshetty@gmail.com, gost.dev@samsung.com,
 linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
 linux-doc@vger.kernel.org, dm-devel@lists.linux.dev,
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References: <20240520102033.9361-1-nj.shetty@samsung.com>
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From: Bart Van Assche <bvanassche@acm.org>
In-Reply-To: <20240521111756.w4xckwbecfyjtez7@green245>
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On 5/21/24 04:17, Nitesh Shetty wrote:
> On 20/05/24 04:00PM, Bart Van Assche wrote:
>> On 5/20/24 03:20, Nitesh Shetty wrote:
>>> +static inline bool blk_copy_offload_mergable(struct request *req,
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
 struct bio *bio)
>>> +{
>>> +=C2=A0=C2=A0=C2=A0 return (req_op(req) =3D=3D REQ_OP_COPY_DST &&
>>> +=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 bio_op(bio) =3D=3D REQ_OP=
_COPY_SRC);
>>> +}
>>
>> bios with different operation types must not be merged. Please rename =
this function.
>>
> As far as function renaming, we followed discard's naming. But open to
> any suggestion.

req_attempt_discard_merge() checks whether two REQ_OP_DISCARD bios can be=
 merged.
The above function checks something else, namely whether REQ_OP_COPY_DST =
and
REQ_OP_COPY_SRC can be combined into a copy offload operation. Hence my r=
equest
not to use the verb "merge" for combining REQ_OP_COPY_SRC and REQ_OP_COPY=
_DST
operations.

Thanks,

Bart.