linux-kernel - RE: [RFC PATCH v5 0/4] add simple copy support

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Date:   Sat, 20 Feb 2021 18:01:56 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'SelvaKumar S' <selvakuma.s1@...sung.com>,
        "linux-nvme@...ts.infradead.org" <linux-nvme@...ts.infradead.org>
CC:     "kbusch@...nel.org" <kbusch@...nel.org>,
        "axboe@...nel.dk" <axboe@...nel.dk>,
        "damien.lemoal@....com" <damien.lemoal@....com>,
        "hch@....de" <hch@....de>, "sagi@...mberg.me" <sagi@...mberg.me>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "dm-devel@...hat.com" <dm-devel@...hat.com>,
        "snitzer@...hat.com" <snitzer@...hat.com>,
        "selvajove@...il.com" <selvajove@...il.com>,
        "joshiiitr@...il.com" <joshiiitr@...il.com>,
        "nj.shetty@...sung.com" <nj.shetty@...sung.com>,
        "joshi.k@...sung.com" <joshi.k@...sung.com>,
        "javier.gonz@...sung.com" <javier.gonz@...sung.com>,
        "kch@...nel.org" <kch@...nel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>
Subject: RE: [RFC PATCH v5 0/4] add simple copy support

From: SelvaKumar S
> Sent: 19 February 2021 12:45
> 
> This patchset tries to add support for TP4065a ("Simple Copy Command"),
> v2020.05.04 ("Ratified")
> 
> The Specification can be found in following link.
> https://nvmexpress.org/wp-content/uploads/NVM-Express-1.4-Ratified-TPs-1.zip
> 
> Simple copy command is a copy offloading operation and is  used to copy
> multiple contiguous ranges (source_ranges) of LBA's to a single destination
> LBA within the device reducing traffic between host and device.

Sounds to me like the real reason is that the copy just ends up changing
some indirect block pointers rather than having to actually copy the data.

	David

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