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Date:   Tue, 25 Apr 2023 13:56:34 +0530
From:   Nitesh Shetty <nj.shetty@samsung.com>
To:     Chaitanya Kulkarni <chaitanyak@nvidia.com>
Cc:     Anuj Gupta <anuj20.g@samsung.com>, Jens Axboe <axboe@kernel.dk>,
        Alasdair Kergon <agk@redhat.com>,
        Mike Snitzer <snitzer@kernel.org>,
        "dm-devel@redhat.com" <dm-devel@redhat.com>,
        Keith Busch <kbusch@kernel.org>,
        Christoph Hellwig <hch@lst.de>,
        Sagi Grimberg <sagi@grimberg.me>,
        James Smart <james.smart@broadcom.com>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Christian Brauner <brauner@kernel.org>,
        "bvanassche@acm.org" <bvanassche@acm.org>,
        "hare@suse.de" <hare@suse.de>,
        "ming.lei@redhat.com" <ming.lei@redhat.com>,
        "dlemoal@kernel.org" <dlemoal@kernel.org>,
        "joshi.k@samsung.com" <joshi.k@samsung.com>,
        "nitheshshetty@gmail.com" <nitheshshetty@gmail.com>,
        "gost.dev@samsung.com" <gost.dev@samsung.com>,
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        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
        "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH v9 6/9] nvmet: add copy command support for bdev and
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On Tue, Apr 25, 2023 at 06:36:51AM +0000, Chaitanya Kulkarni wrote:
> On 4/11/23 01:10, Anuj Gupta wrote:
> > From: Nitesh Shetty <nj.shetty@samsung.com>
> >
> > Add support for handling target command on target.
> 
> what is target command ?
> 
> command that you have added is :nvme_cmd_copy
>

acked. It was supposed to be nvme_cmd_copy.

> > For bdev-ns we call into blkdev_issue_copy, which the block layer
> > completes by a offloaded copy request to backend bdev or by emulating the
> > request.
> >
> > For file-ns we call vfs_copy_file_range to service our request.
> >
> > Currently target always shows copy capability by setting
> > NVME_CTRL_ONCS_COPY in controller ONCS.
> 
> there is nothing mentioned about target/loop.c in commit log ?
>

acked, will add the description for loop device.

> > Signed-off-by: Nitesh Shetty <nj.shetty@samsung.com>
> > Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
> > ---
> >   drivers/nvme/target/admin-cmd.c   |  9 +++--
> >   drivers/nvme/target/io-cmd-bdev.c | 58 +++++++++++++++++++++++++++++++
> >   drivers/nvme/target/io-cmd-file.c | 52 +++++++++++++++++++++++++++
> >   drivers/nvme/target/loop.c        |  6 ++++
> >   drivers/nvme/target/nvmet.h       |  1 +
> >   5 files changed, 124 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
> > index 80099df37314..978786ec6a9e 100644
> > --- a/drivers/nvme/target/admin-cmd.c
> > +++ b/drivers/nvme/target/admin-cmd.c
> > @@ -433,8 +433,7 @@ static void nvmet_execute_identify_ctrl(struct nvmet_req *req)
> >   	id->nn = cpu_to_le32(NVMET_MAX_NAMESPACES);
> >   	id->mnan = cpu_to_le32(NVMET_MAX_NAMESPACES);
> >   	id->oncs = cpu_to_le16(NVME_CTRL_ONCS_DSM |
> > -			NVME_CTRL_ONCS_WRITE_ZEROES);
> > -
> > +			NVME_CTRL_ONCS_WRITE_ZEROES | NVME_CTRL_ONCS_COPY);
> >   	/* XXX: don't report vwc if the underlying device is write through */
> >   	id->vwc = NVME_CTRL_VWC_PRESENT;
> >   
> > @@ -536,6 +535,12 @@ static void nvmet_execute_identify_ns(struct nvmet_req *req)
> >   
> >   	if (req->ns->bdev)
> >   		nvmet_bdev_set_limits(req->ns->bdev, id);
> > +	else {
> > +		id->msrc = (u8)to0based(BIO_MAX_VECS - 1);
> > +		id->mssrl = cpu_to_le16(BIO_MAX_VECS <<
> > +				(PAGE_SHIFT - SECTOR_SHIFT));
> > +		id->mcl = cpu_to_le32(le16_to_cpu(id->mssrl));
> > +	}
> >   
> >   	/*
> >   	 * We just provide a single LBA format that matches what the
> > diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
> > index c2d6cea0236b..0af273097aa4 100644
> > --- a/drivers/nvme/target/io-cmd-bdev.c
> > +++ b/drivers/nvme/target/io-cmd-bdev.c
> > @@ -46,6 +46,19 @@ void nvmet_bdev_set_limits(struct block_device *bdev, struct nvme_id_ns *id)
> >   	id->npda = id->npdg;
> >   	/* NOWS = Namespace Optimal Write Size */
> >   	id->nows = to0based(bdev_io_opt(bdev) / bdev_logical_block_size(bdev));
> > +
> > +	/*Copy limits*/
> 
> above comment doesn't make any sense ...
>

acked, will remove it next version.

> > +	if (bdev_max_copy_sectors(bdev)) {
> > +		id->msrc = id->msrc;
> > +		id->mssrl = cpu_to_le16((bdev_max_copy_sectors(bdev) <<
> > +				SECTOR_SHIFT) / bdev_logical_block_size(bdev));
> > +		id->mcl = cpu_to_le32(id->mssrl);
> > +	} else {
> > +		id->msrc = (u8)to0based(BIO_MAX_VECS - 1);
> > +		id->mssrl = cpu_to_le16((BIO_MAX_VECS << PAGE_SHIFT) /
> > +				bdev_logical_block_size(bdev));
> > +		id->mcl = cpu_to_le32(id->mssrl);
> > +	}
> >   }
> >   
> >   void nvmet_bdev_ns_disable(struct nvmet_ns *ns)
> > @@ -184,6 +197,19 @@ static void nvmet_bio_done(struct bio *bio)
> >   	nvmet_req_bio_put(req, bio);
> >   }
> >   
> > +static void nvmet_bdev_copy_end_io(void *private, int comp_len)
> > +{
> > +	struct nvmet_req *req = (struct nvmet_req *)private;
> > +
> > +	if (comp_len == req->copy_len) {
> > +		req->cqe->result.u32 = cpu_to_le32(1);
> > +		nvmet_req_complete(req, errno_to_nvme_status(req, 0));
> > +	} else {
> > +		req->cqe->result.u32 = cpu_to_le32(0);
> > +		nvmet_req_complete(req, blk_to_nvme_status(req, BLK_STS_IOERR));
> > +	}
> > +}
> > +
> 
> please reduce calls for nvmet_req_complete().
> 
> +static void nvmet_bdev_copy_end_io(void *private, int comp_len)
> +{
> +	struct nvmet_req *req = (struct nvmet_req *)private;
> +	u16 status;
> +
> +	if (comp_len == req->copy_len) {
> +		req->cqe->result.u32 = cpu_to_le32(1);
> +		status = errno_to_nvme_status(req, 0));
> +	} else {
> +		req->cqe->result.u32 = cpu_to_le32(0);
> +		status = blk_to_nvme_status(req, BLK_STS_IOERR));
> +	}
> +	nvmet_req_complete(req, status);
> +}
> +
>

makes sense, will modify this snippet.

> >   #ifdef CONFIG_BLK_DEV_INTEGRITY
> >   static int nvmet_bdev_alloc_bip(struct nvmet_req *req, struct bio *bio,
> >   				struct sg_mapping_iter *miter)
> > @@ -450,6 +476,34 @@ static void nvmet_bdev_execute_write_zeroes(struct nvmet_req *req)
> >   	}
> >   }
> >   
> > +/* At present we handle only one range entry */
> 
> please add explanation why ...
>
Because we aligned copy offload similar to copy_file_range in out recent
revisions, discarding multi range support.
Sure we will update comments to reflect the same.

> > +static void nvmet_bdev_execute_copy(struct nvmet_req *req)
> > +{
> > +	struct nvme_copy_range range;
> > +	struct nvme_command *cmnd = req->cmd;
> 
> don't use cmnd, cmd is used everywhere and matches req->cmd,
> applies to everywhere in this patch...
> 

acked

> > +	int ret;
> 
> wrong return type is should be u16 since nvmet_copy_from_sgl()
> returns u16 if I remember correctly.
> 
> > +
> > +
> 

acked

> no extra white line between declaration and body of functions
>

acked

> > +	ret = nvmet_copy_from_sgl(req, 0, &range, sizeof(range));
> > +	if (ret)
> > +		goto out;
> > +
> > +	ret = blkdev_issue_copy(req->ns->bdev,
> > +		le64_to_cpu(cmnd->copy.sdlba) << req->ns->blksize_shift,
> > +		req->ns->bdev,
> > +		le64_to_cpu(range.slba) << req->ns->blksize_shift,
> > +		(le16_to_cpu(range.nlb) + 1) << req->ns->blksize_shift,
> > +		nvmet_bdev_copy_end_io, (void *)req, GFP_KERNEL);
> > +	if (ret) {
> > +		req->cqe->result.u32 = cpu_to_le32(0);
> > +		nvmet_req_complete(req, blk_to_nvme_status(req, BLK_STS_IOERR));
> > +	}
> > +
> > +	return;
> > +out:
> > +	nvmet_req_complete(req, errno_to_nvme_status(req, ret));
> > +}
> > +
> 
> again one call to nvmet_req_complete() can do the same job.
> consider following totally untested? :-
> /* TODO: add detailed comment here why you support one range ? */
> static void nvmet_bdev_execute_copy(struct nvmet_req *req)
> {
>  ??????? u32 blkshift = req->ns->blksize_shift;
>  ??????? struct nvme_command *cmnd = req->cmd;
>  ??????? struct nvme_copy_range range;
>  ??????? u16 status;
> 
>  ??????? status = nvmet_copy_from_sgl(req, 0, &range, sizeof(range));
>  ??????? if (status) {
>  ??????????????? goto out;
>  ??????? }
> 
>  ??????? ret = blkdev_issue_copy(req->ns->bdev,
>  ??????????????????????????????? le64_to_cpu(cmnd->copy.sdlba) << blkshift,
>  ??????????????????????????????? req->ns->bdev,
>  ??????????????????????????????? le64_to_cpu(range.slba) << blksize_shift,
>  ??????????????????????????????? (le16_to_cpu(range.nlb) + 1) << 
> blksize_shift,
>  ??????????????????????????????? nvmet_bdev_copy_end_io, (void *)req, 
> GFP_KERNEL);
>  ??????? if (ret) {
>  ??????????????? req->cqe->result.u32 = cpu_to_le32(0);
>  ??????????????? status = blk_to_nvme_status(req, BLK_STS_IOERR);
> out:
>  ??????????????? nvmet_req_complete(req, status);
>  ??????? }
> }
> 

acked, thanks for sharing the snippet

> >   u16 nvmet_bdev_parse_io_cmd(struct nvmet_req *req)
> >   {
> >   	switch (req->cmd->common.opcode) {
> > @@ -468,6 +522,10 @@ u16 nvmet_bdev_parse_io_cmd(struct nvmet_req *req)
> >   	case nvme_cmd_write_zeroes:
> >   		req->execute = nvmet_bdev_execute_write_zeroes;
> >   		return 0;
> > +	case nvme_cmd_copy:
> > +		req->execute = nvmet_bdev_execute_copy;
> > +		return 0;
> > +
> >   	default:
> >   		return nvmet_report_invalid_opcode(req);
> >   	}
> > diff --git a/drivers/nvme/target/io-cmd-file.c b/drivers/nvme/target/io-cmd-file.c
> > index 2d068439b129..69f198ecec77 100644
> > --- a/drivers/nvme/target/io-cmd-file.c
> > +++ b/drivers/nvme/target/io-cmd-file.c
> > @@ -322,6 +322,49 @@ static void nvmet_file_dsm_work(struct work_struct *w)
> >   	}
> >   }
> >   
> > +static void nvmet_file_copy_work(struct work_struct *w)
> > +{
> > +	struct nvmet_req *req = container_of(w, struct nvmet_req, f.work);
> > +	int nr_range;
> > +	loff_t pos;
> > +	struct nvme_command *cmnd = req->cmd;
> > +	int ret = 0, len = 0, src, id;
> 
> reverse tree style for declaration ...
> 

acked

> > +
> > +	nr_range = cmnd->copy.nr_range + 1;
> > +	pos = le64_to_cpu(req->cmd->copy.sdlba) << req->ns->blksize_shift;
> 
> you have a cmd variable above and you are still using req->cmd ?
> why create a variable on stack then ? u don't need that variable
> anyways...
>

acked

> > +	if (unlikely(pos + req->transfer_len > req->ns->size)) {
> > +		nvmet_req_complete(req, errno_to_nvme_status(req, -ENOSPC));
> > +		return;
> > +	}
> > +
> > +	for (id = 0 ; id < nr_range; id++) {
> > +		struct nvme_copy_range range;
> > +
> > +		ret = nvmet_copy_from_sgl(req, id * sizeof(range), &range,
> > +					sizeof(range));
> > +		if (ret)
> > +			goto out;
> > +
> > +		len = (le16_to_cpu(range.nlb) + 1) << (req->ns->blksize_shift);
> > +		src = (le64_to_cpu(range.slba) << (req->ns->blksize_shift));
> > +		ret = vfs_copy_file_range(req->ns->file, src, req->ns->file,
> > +					pos, len, 0);
> 
> 5th paramaeter to vfs_copy_file_range() is size_t you have used int
> for len ? also
> vfs_copy_file_range() returns ssize_t you are catching it in int ?
>

acked, will change it to ssize_t.

> > +out:
> > +		if (ret != len) {
> > +			pos += ret;
> > +			req->cqe->result.u32 = cpu_to_le32(id);
> > +			nvmet_req_complete(req, ret < 0 ?
> > +					errno_to_nvme_status(req, ret) :
> > +					errno_to_nvme_status(req, -EIO));
> 
> again plz don't add multiple nvmet_req_complete() calls
>

acked

> > +			return;
> > +
> > +		} else
> > +			pos += len;
> > +	}
> > +
> > +	nvmet_req_complete(req, 0);
> > +
> > +}
> 
> wrt above comments consider following totally untested :-
> 
> static void nvmet_file_copy_work(struct work_struct *w)
> {
>  ??????? struct nvmet_req *req = container_of(w, struct nvmet_req, f.work);
>  ??????? int nr_range = req->cmd->copy.nr_range + 1;
>  ??????? u16 status = 0;
>  ??????? int src, id;
>  ??????? ssize_t ret;
>  ??????? size_t len;
>  ??????? loff_t pos;
> 
>  ??????? pos = le64_to_cpu(req->cmd->copy.sdlba) << req->ns->blksize_shift;
>  ??????? if (unlikely(pos + req->transfer_len > req->ns->size)) {
>  ??????????????? nvmet_req_complete(req, errno_to_nvme_status(req, 
> -ENOSPC));
>  ??????????????? return;
>  ??????? }
> 
>  ??????? for (id = 0 ; id < nr_range; id++) {
>  ??????????????? struct nvme_copy_range range;
> 
>  ??????????????? status = nvmet_copy_from_sgl(req, id * sizeof(range), 
> &range,
>  ??????????????????????????????????????? sizeof(range));
>  ??????????????? if (status)
>  ??????????????????????? goto out;
> 
>  ??????????????? src = (le64_to_cpu(range.slba) << 
> (req->ns->blksize_shift));
>  ??????????????? len = (le16_to_cpu(range.nlb) + 1) << 
> (req->ns->blksize_shift);
> 
>  ??????????????? ret = vfs_copy_file_range(req->ns->file, src, 
> req->ns->file,
>  ??????????????????????????????????????? pos, len, 0);
> 
>  ??????????????? if (ret != len) {
>  ??????????????????????? req->cqe->result.u32 = cpu_to_le32(id);
>  ??????????????????????? if (ret < 0)
>  ??????????????????????????????? status = errno_to_nvme_status(req, ret);
>  ??????????????????????? else
>  ??????????????????????????????? status = errno_to_nvme_status(req, -EIO);
>  ??????????????????????? goto out;
>  ??????????????? }
>  ??????????????? pos += ret;
>  ??????? }
> out:
>  ??????? nvmet_req_complete(req, status);
> }
> 
>

Thanks for snippet will update this in next version.
--
Nitesh Shetty

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