linux-kernel - Re: [PATCH v20 02/12] Add infrastructure for copy offload in block and request layer.

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Date: Wed, 22 May 2024 10:58:33 -0700
From: Bart Van Assche <bvanassche@....org>
To: Nitesh Shetty <nj.shetty@...sung.com>
Cc: Jens Axboe <axboe@...nel.dk>, Jonathan Corbet <corbet@....net>,
 Alasdair Kergon <agk@...hat.com>, Mike Snitzer <snitzer@...nel.org>,
 Mikulas Patocka <mpatocka@...hat.com>, Keith Busch <kbusch@...nel.org>,
 Christoph Hellwig <hch@....de>, Sagi Grimberg <sagi@...mberg.me>,
 Chaitanya Kulkarni <kch@...dia.com>, Alexander Viro
 <viro@...iv.linux.org.uk>, Christian Brauner <brauner@...nel.org>,
 Jan Kara <jack@...e.cz>, martin.petersen@...cle.com, david@...morbit.com,
 hare@...e.de, damien.lemoal@...nsource.wdc.com, anuj20.g@...sung.com,
 joshi.k@...sung.com, nitheshshetty@...il.com, gost.dev@...sung.com,
 linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-doc@...r.kernel.org, dm-devel@...ts.linux.dev,
 linux-nvme@...ts.infradead.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v20 02/12] Add infrastructure for copy offload in block
 and request layer.

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,
>>> +                         struct bio *bio)
>>> +{
>>> +    return (req_op(req) == REQ_OP_COPY_DST &&
>>> +        bio_op(bio) == 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 request
not to use the verb "merge" for combining REQ_OP_COPY_SRC and REQ_OP_COPY_DST
operations.

Thanks,

Bart.