Re: [PATCH V10 4/8] nvmet: add ZBD over ZNS backend support

From: Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>
To: Christoph Hellwig <hch@lst.de>
Cc: "linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
	"kbusch@kernel.org" <kbusch@kernel.org>,
	"sagi@grimberg.me" <sagi@grimberg.me>,
	Damien Le Moal <Damien.LeMoal@wdc.com>
Subject: Re: [PATCH V10 4/8] nvmet: add ZBD over ZNS backend support
Date: Tue, 9 Mar 2021 21:13:42 +0000	[thread overview]
Message-ID: <BYAPR04MB4965291573F34312249DA36B86929@BYAPR04MB4965.namprd04.prod.outlook.com> (raw)
In-Reply-To: 20210309114127.GD9520@lst.de

On 3/9/21 03:41, Christoph Hellwig wrote:
> On Mon, Mar 08, 2021 at 08:58:19PM -0800, Chaitanya Kulkarni wrote:
>> NVMe TP 4053 – Zoned Namespaces (ZNS) allows host software to
>> communicate with a non-volatile memory subsystem using zones for
>> NVMe protocol based controllers. NVMeOF already support the ZNS NVMe
>> Protocol compliant devices on the target in the passthru mode. There
>> are Generic zoned block devices like  Shingled Magnetic Recording (SMR)
>> HDDs that are not based on the NVMe protocol.
>>
>> This patch adds ZNS backend to support the ZBDs for NVMeOF target.
>>
>> This support includes implementing the new command set NVME_CSI_ZNS,
>> adding different command handlers for ZNS command set such as
>> NVMe Identify Controller, NVMe Identify Namespace, NVMe Zone Append,
>> NVMe Zone Management Send and NVMe Zone Management Receive.
>>
>> With new command set identifier we also update the target command effects
>> logs to reflect the ZNS compliant commands.
>>
>> Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
>> ---
>>  drivers/nvme/target/Makefile      |   1 +
>>  drivers/nvme/target/admin-cmd.c   |   8 +
>>  drivers/nvme/target/io-cmd-bdev.c |  33 +++-
>>  drivers/nvme/target/nvmet.h       |  38 ++++
>>  drivers/nvme/target/zns.c         | 308 ++++++++++++++++++++++++++++++
>>  5 files changed, 380 insertions(+), 8 deletions(-)
>>  create mode 100644 drivers/nvme/target/zns.c
>>
>> diff --git a/drivers/nvme/target/Makefile b/drivers/nvme/target/Makefile
>> index ebf91fc4c72e..9837e580fa7e 100644
>> --- a/drivers/nvme/target/Makefile
>> +++ b/drivers/nvme/target/Makefile
>> @@ -12,6 +12,7 @@ obj-$(CONFIG_NVME_TARGET_TCP)		+= nvmet-tcp.o
>>  nvmet-y		+= core.o configfs.o admin-cmd.o fabrics-cmd.o \
>>  			discovery.o io-cmd-file.o io-cmd-bdev.o
>>  nvmet-$(CONFIG_NVME_TARGET_PASSTHRU)	+= passthru.o
>> +nvmet-$(CONFIG_BLK_DEV_ZONED)		+= zns.o
>>  nvme-loop-y	+= loop.o
>>  nvmet-rdma-y	+= rdma.o
>>  nvmet-fc-y	+= fc.o
>> diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
>> index 76d9fc0f48c2..05ef362d70b7 100644
>> --- a/drivers/nvme/target/admin-cmd.c
>> +++ b/drivers/nvme/target/admin-cmd.c
>> @@ -719,8 +719,16 @@ static void nvmet_execute_identify(struct nvmet_req *req)
>>  	switch (req->cmd->identify.cns) {
>>  	case NVME_ID_CNS_NS:
>>  		return nvmet_execute_identify_ns(req);
>> +	case NVME_ID_CNS_CS_NS:
>> +		if (req->cmd->identify.csi == NVME_CSI_ZNS)
>> +			return nvmet_execute_identify_cns_cs_ns(req);
>> +		break;
>>  	case NVME_ID_CNS_CTRL:
>>  		return nvmet_execute_identify_ctrl(req);
>> +	case NVME_ID_CNS_CS_CTRL:
>> +		if (req->cmd->identify.csi == NVME_CSI_ZNS)
>> +			return nvmet_execute_identify_cns_cs_ctrl(req);
>> +		break;
> I still find the way how this mixes the CNS and CSI fields in a single
> switch weird.  I'd expect an outer switch for CNS and an inner one for
> the CSI value.

Well it just a sanitary check for csi, I think identify.csi checks
should be moved to nvmet_execute_identify_cns_cs_ns() and
nvmet_execute_identify_cns_cs_ctrl()to keep the code simple here.

I'll move that to respective callers, if you are not okay with that
please let me know.

>> +static u16 nvmet_bdev_zns_checks(struct nvmet_req *req)
>> +{
>> +	if (!bdev_is_zoned(req->ns->bdev))
>> +		return NVME_SC_INVALID_NS | NVME_SC_DNR;
>> +
>> +	if (req->cmd->zmr.zra != NVME_ZRA_ZONE_REPORT)
>> +		return NVME_SC_INVALID_FIELD;
>> +
>> +	if (req->cmd->zmr.zrasf != NVME_ZRASF_ZONE_REPORT_ALL)
>> +		return NVME_SC_INVALID_FIELD;
>> +
>> +	if (req->cmd->zmr.pr != NVME_REPORT_ZONE_PARTIAL)
>> +		return NVME_SC_INVALID_FIELD;
> error_loc information would be useful here.

Okay.

>> +static inline bool nvmet_zns_update_zasl(struct nvmet_ns *ns)
>> +{
>> +	struct request_queue *q = ns->bdev->bd_disk->queue;
>> +	u8 zasl = nvmet_zasl(queue_max_zone_append_sectors(q));
>> +
>> +	if (ns->subsys->zasl)
>> +		return ns->subsys->zasl < zasl ? false : true;
> No need for the tenary expression here, the comparism will autoconvert to
> bool.
>

Okay.

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