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Date:   Wed, 27 Apr 2022 12:37:07 +0200
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To:     Nitesh Shetty <nj.shetty@samsung.com>
Cc:     chaitanyak@nvidia.com, linux-block@vger.kernel.org,
        linux-scsi@vger.kernel.org, dm-devel@redhat.com,
        linux-nvme@lists.infradead.org, linux-fsdevel@vger.kernel.org,
        axboe@kernel.dk, msnitzer@redhat.com, bvanassche@acm.org,
        martin.petersen@oracle.com, kbusch@kernel.org, hch@lst.de,
        Frederick.Knight@netapp.com, osandov@fb.com,
        lsf-pc@lists.linux-foundation.org, djwong@kernel.org,
        josef@toxicpanda.com, clm@fb.com, dsterba@suse.com, tytso@mit.edu,
        jack@suse.com, nitheshshetty@gmail.com, gost.dev@samsung.com,
        =?UTF-8?Q?Javier_Gonz=c3=a1lez?= <javier.gonz@samsung.com>,
        Arnav Dawn <arnav.dawn@samsung.com>,
        Alasdair Kergon <agk@redhat.com>,
        Mike Snitzer <snitzer@kernel.org>,
        Sagi Grimberg <sagi@grimberg.me>,
        James Smart <james.smart@broadcom.com>,
        Chaitanya Kulkarni <kch@nvidia.com>,
        Damien Le Moal <damien.lemoal@opensource.wdc.com>,
        Naohiro Aota <naohiro.aota@wdc.com>,
        Johannes Thumshirn <jth@kernel.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        linux-kernel@vger.kernel.org
References: <20220426101241.30100-1-nj.shetty@samsung.com>
 <CGME20220426101938epcas5p291690dd1f0e931cd9f8139daaf3f9296@epcas5p2.samsung.com>
 <20220426101241.30100-4-nj.shetty@samsung.com>
From:   Hannes Reinecke <hare@suse.de>
Subject: Re: [PATCH v4 03/10] block: Introduce a new ioctl for copy
In-Reply-To: <20220426101241.30100-4-nj.shetty@samsung.com>
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Precedence: bulk

On 4/26/22 12:12, Nitesh Shetty wrote:
> Add new BLKCOPY ioctl that offloads copying of one or more sources ranges
> to one or more destination in a device. COPY ioctl accepts a 'copy_range'
> structure that contains no of range, a reserved field , followed by an
> array of ranges. Each source range is represented by 'range_entry' that
> contains source start offset, destination start offset and length of
> source ranges (in bytes)
> 
> MAX_COPY_NR_RANGE, limits the number of entries for the IOCTL and
> MAX_COPY_TOTAL_LENGTH limits the total copy length, IOCTL can handle.
> 
> Example code, to issue BLKCOPY:
> /* Sample example to copy three entries with [dest,src,len],
> * [32768, 0, 4096] [36864, 4096, 4096] [40960,8192,4096] on same device */
> 
> int main(void)
> {
> 	int i, ret, fd;
> 	unsigned long src = 0, dst = 32768, len = 4096;
> 	struct copy_range *cr;
> 	cr = (struct copy_range *)malloc(sizeof(*cr)+
> 					(sizeof(struct range_entry)*3));
> 	cr->nr_range = 3;
> 	cr->reserved = 0;
> 	for (i = 0; i< cr->nr_range; i++, src += len, dst += len) {
> 		cr->range_list[i].dst = dst;
> 		cr->range_list[i].src = src;
> 		cr->range_list[i].len = len;
> 		cr->range_list[i].comp_len = 0;
> 	}
> 	fd = open("/dev/nvme0n1", O_RDWR);
> 	if (fd < 0) return 1;
> 	ret = ioctl(fd, BLKCOPY, cr);
> 	if (ret != 0)
> 	       printf("copy failed, ret= %d\n", ret);
> 	for (i=0; i< cr->nr_range; i++)
> 		if (cr->range_list[i].len != cr->range_list[i].comp_len)
> 			printf("Partial copy for entry %d: requested %llu, completed %llu\n",
> 								i, cr->range_list[i].len,
> 								cr->range_list[i].comp_len);
> 	close(fd);
> 	free(cr);
> 	return ret;
> }
> 
> Signed-off-by: Nitesh Shetty <nj.shetty@samsung.com>
> Signed-off-by: Javier González <javier.gonz@samsung.com>
> Signed-off-by: Arnav Dawn <arnav.dawn@samsung.com>
> ---
>   block/ioctl.c           | 32 ++++++++++++++++++++++++++++++++
>   include/uapi/linux/fs.h |  9 +++++++++
>   2 files changed, 41 insertions(+)
> 
Reviewed-by: Hannes Reinecke <hare@suse.de>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		           Kernel Storage Architect
hare@suse.de			                  +49 911 74053 688
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