Message-ID: <MN2PR04MB622328EF8E1CEFC29A0D09B8F16A0@MN2PR04MB6223.namprd04.prod.outlook.com>
Date:   Fri, 3 Jul 2020 09:44:09 +0000
From:   Matias Bjorling <Matias.Bjorling@....com>
To:     Javier González <javier@...igon.com>,
        Damien Le Moal <Damien.LeMoal@....com>
CC:     "axboe@...nel.dk" <axboe@...nel.dk>,
        "kbusch@...nel.org" <kbusch@...nel.org>, "hch@....de" <hch@....de>,
        "sagi@...mberg.me" <sagi@...mberg.me>,
        "martin.petersen@...cle.com" <martin.petersen@...cle.com>,
        Niklas Cassel <Niklas.Cassel@....com>,
        Hans Holmberg <Hans.Holmberg@....com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
        "linux-nvme@...ts.infradead.org" <linux-nvme@...ts.infradead.org>
Subject: RE: [PATCH 2/2] block: add BLKSETDESCZONE ioctl for Zoned Block
 Devices

> -----Original Message-----
> From: Javier González <javier@...igon.com>
> Sent: Monday, 29 June 2020 21.39
> To: Damien Le Moal <Damien.LeMoal@....com>
> Cc: Matias Bjorling <Matias.Bjorling@....com>; axboe@...nel.dk;
> kbusch@...nel.org; hch@....de; sagi@...mberg.me;
> martin.petersen@...cle.com; Niklas Cassel <Niklas.Cassel@....com>; Hans
> Holmberg <Hans.Holmberg@....com>; linux-scsi@...r.kernel.org; linux-
> kernel@...r.kernel.org; linux-block@...r.kernel.org; linux-
> nvme@...ts.infradead.org
> Subject: Re: [PATCH 2/2] block: add BLKSETDESCZONE ioctl for Zoned Block
> Devices
> 
> On 29.06.2020 01:00, Damien Le Moal wrote:
> >On 2020/06/29 8:01, Matias Bjorling wrote:
> >> The NVMe Zoned Namespace Command Set adds support for associating
> >> data to a zone through the Zone Descriptor Extension feature.
> >>
> >> To allow user-space to associate data to a zone, add support through
> >> the BLKSETDESCZONE ioctl. The ioctl requires that it is issued to a
> >> zoned block device, and that it supports the Zone Descriptor
> >> Extension feature. Support is detected through the the
> >> zone_desc_ext_bytes sysfs queue entry for the specific block device.
> >> A value larger than zero communicates that the device supports the
> >> feature.
> 
> Have you considered the possibility of adding this an action to a IOCTL that
> looks like the zone management one we discussed last week? We would start
> saving IOCTLs already if we count the offline transition and this one.

Yes, I considered it. Damien and Christoph have asked for it to separate ioctls. 

> 
> >>
> >> The ioctl associates data to a zone by issuing a Zone Management Send
> >> command with the Zone Send Action set as the Set Zone Descriptor
> >> Extension.
> >>
> >> For the command to complete successfully, the specified zone must be
> >> in the Empty state, and active resources must be available. On
> >> success, the specified zone is transioned to Closed state by the
> >> device. If less data is supplied by user-space then reported by the
> >> the Zone Descriptor Extension size, the rest is zero-filled. If more
> >> data or no data is supplied by user-space, the ioctl fails.
> >>
> >> To issue the ioctl, a new blk_zone_set_desc data structure is defined.
> >> It has following parameters:
> >>
> >>  * the sector of the specific zone.
> >>  * the length of the data to be associated to the zone.
> >>  * any flags be used by the ioctl. None is defined.
> >>  * data associated to the zone.
> >>
> >> The data is laid out after the flags parameter, and it is the
> >> caller's responsibility to allocate memory for the data that is
> >> specified in the length parameter.
> >>
> >> Signed-off-by: Matias Bjørling <matias.bjorling@....com>
> >> ---
> >>  block/blk-zoned.c             | 108 ++++++++++++++++++++++++++++++++++
> >>  block/ioctl.c                 |   2 +
> >>  drivers/nvme/host/core.c      |   3 +
> >>  drivers/nvme/host/nvme.h      |   9 +++
> >>  drivers/nvme/host/zns.c       |  11 ++++
> >>  include/linux/blk_types.h     |   2 +
> >>  include/linux/blkdev.h        |   9 ++-
> >>  include/uapi/linux/blkzoned.h |  20 ++++++-
> >>  8 files changed, 162 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/block/blk-zoned.c b/block/blk-zoned.c index
> >> 81152a260354..4dc40ec006a2 100644
> >> --- a/block/blk-zoned.c
> >> +++ b/block/blk-zoned.c
> >> @@ -259,6 +259,50 @@ int blkdev_zone_mgmt(struct block_device *bdev,
> >> enum req_opf op,  }  EXPORT_SYMBOL_GPL(blkdev_zone_mgmt);
> >>
> >> +/**
> >> + * blkdev_zone_set_desc - Execute a zone management set zone
> descriptor
> >> + *                        extension operation on a zone
> >> + * @bdev:	Target block device
> >> + * @sector:	Start sector of the zone to operate on
> >> + * @data:	Pointer to the data that is to be associated to the zone
> >> + * @gfp_mask:	Memory allocation flags (for bio_alloc)
> >> + *
> >> + * Description:
> >> + *    Associate zone descriptor extension data to a specified zone.
> >> + *    The block device must support zone descriptor extensions.
> >> + *    i.e., by exposing a positive zone descriptor extension size.
> >> + */
> >> +int blkdev_zone_set_desc(struct block_device *bdev, sector_t sector,
> >> +			 struct page *data, gfp_t gfp_mask)
> >
> >struct page for the data ? Why not just a "void *" to allow for
> >kmalloc/vmalloc data ? And no length for the data ? This is a bit odd.
> >
> >> +{
> >> +	struct request_queue *q = bdev_get_queue(bdev);
> >> +	sector_t zone_sectors = blk_queue_zone_sectors(q);
> >> +	struct bio_vec bio_vec;
> >> +	struct bio bio;
> >> +
> >> +	if (!blk_queue_is_zoned(q))
> >> +		return -EOPNOTSUPP;
> >> +
> >> +	if (bdev_read_only(bdev))
> >> +		return -EPERM;
> >
> >You are not checking the zone_desc_ext_bytes limit here. You should.
> >> +
> >> +	/* Check alignment (handle eventual smaller last zone) */
> >> +	if (sector & (zone_sectors - 1))
> >> +		return -EINVAL;
> >
> >The comment is incorrect. There is nothing special for handling the
> >last zone in this test.
> >
> >> +
> >> +	bio_init(&bio, &bio_vec, 1);
> >> +	bio.bi_opf = REQ_OP_ZONE_SET_DESC | REQ_SYNC;
> >> +	bio.bi_iter.bi_sector = sector;
> >> +	bio_set_dev(&bio, bdev);
> >> +	bio_add_page(&bio, data, queue_zone_desc_ext_bytes(q), 0);
> >> +
> >> +	/* This may take a while, so be nice to others */
> >> +	cond_resched();
> >
> >This is not a loop, so you do not need this.
> >
> >> +
> >> +	return submit_bio_wait(&bio);
> >> +}
> >> +EXPORT_SYMBOL_GPL(blkdev_zone_set_desc);
> >> +
> >>  struct zone_report_args {
> >>  	struct blk_zone __user *zones;
> >>  };
> >> @@ -370,6 +414,70 @@ int blkdev_zone_mgmt_ioctl(struct block_device
> *bdev, fmode_t mode,
> >>  				GFP_KERNEL);
> >>  }
> >>
> >> +/*
> >> + * BLKSETDESCZONE ioctl processing.
> >> + * Called from blkdev_ioctl.
> >> + */
> >> +int blkdev_zone_set_desc_ioctl(struct block_device *bdev, fmode_t
> mode,
> >> +			       unsigned int cmd, unsigned long arg) {
> >> +	void __user *argp = (void __user *)arg;
> >> +	struct request_queue *q;
> >> +	struct blk_zone_set_desc zsd;
> >> +	void *zsd_data;
> >> +	int ret;
> >> +
> >> +	if (!argp)
> >> +		return -EINVAL;
> >> +
> >> +	q = bdev_get_queue(bdev);
> >> +	if (!q)
> >> +		return -ENXIO;
> >> +
> >> +	if (!blk_queue_is_zoned(q))
> >> +		return -ENOTTY;
> >> +
> >> +	if (!capable(CAP_SYS_ADMIN))
> >> +		return -EACCES;
> >> +
> >> +	if (!(mode & FMODE_WRITE))
> >> +		return -EBADF;
> >> +
> >> +	if (!queue_zone_desc_ext_bytes(q))
> >> +		return -EOPNOTSUPP;
> >> +
> >> +	if (copy_from_user(&zsd, argp, sizeof(struct blk_zone_set_desc)))
> >> +		return -EFAULT;
> >> +
> >> +	/* no flags is currently supported */
> >> +	if (zsd.flags)
> >> +		return -ENOTTY;
> >> +
> >> +	if (!zsd.len || zsd.len > queue_zone_desc_ext_bytes(q))
> >> +		return -ENOTTY;
> >
> >This should go into blkdev_zone_set_desc() as well so that in-kernel
> >users are checked. So there may be no need to check this here.
> >
> >> +
> >> +	/* allocate the size of the zone descriptor extension and fill
> >> +	 * with the data in the user data buffer. If the data size is less
> >> +	 * than the zone descriptor extension size, then the rest of the
> >> +	 * zone description extension data buffer is zero-filled.
> >> +	 */
> >> +	zsd_data = (void *) get_zeroed_page(GFP_KERNEL);
> >> +	if (!zsd_data)
> >> +		return -ENOMEM;
> >> +
> >> +	if (copy_from_user(zsd_data, argp + sizeof(struct blk_zone_set_desc),
> >> +			   zsd.len)) {
> >> +		ret = -EFAULT;
> >> +		goto free;
> >> +	}
> >> +
> >> +	ret = blkdev_zone_set_desc(bdev, zsd.sector, virt_to_page(zsd_data),
> >> +	      GFP_KERNEL);
> >> +free:
> >> +	free_page((unsigned long) zsd_data);
> >> +	return ret;
> >> +}
> >> +
> >>  static inline unsigned long *blk_alloc_zone_bitmap(int node,
> >>  						   unsigned int nr_zones)
> >>  {
> >> diff --git a/block/ioctl.c b/block/ioctl.c index
> >> bdb3bbb253d9..b9744705835b 100644
> >> --- a/block/ioctl.c
> >> +++ b/block/ioctl.c
> >> @@ -515,6 +515,8 @@ static int blkdev_common_ioctl(struct block_device
> *bdev, fmode_t mode,
> >>  	case BLKCLOSEZONE:
> >>  	case BLKFINISHZONE:
> >>  		return blkdev_zone_mgmt_ioctl(bdev, mode, cmd, arg);
> >> +	case BLKSETDESCZONE:
> >> +		return blkdev_zone_set_desc_ioctl(bdev, mode, cmd, arg);
> >>  	case BLKGETZONESZ:
> >>  		return put_uint(argp, bdev_zone_sectors(bdev));
> >>  	case BLKGETNRZONES:
> >> diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> >> index e961910da4ac..b8f25b0d00ad 100644
> >> --- a/drivers/nvme/host/core.c
> >> +++ b/drivers/nvme/host/core.c
> >> @@ -776,6 +776,9 @@ blk_status_t nvme_setup_cmd(struct nvme_ns *ns,
> struct request *req,
> >>  	case REQ_OP_ZONE_FINISH:
> >>  		ret = nvme_setup_zone_mgmt_send(ns, req, cmd,
> NVME_ZONE_FINISH);
> >>  		break;
> >> +	case REQ_OP_ZONE_SET_DESC:
> >> +		ret = nvme_setup_zone_set_desc(ns, req, cmd);
> >> +		break;
> >>  	case REQ_OP_WRITE_ZEROES:
> >>  		ret = nvme_setup_write_zeroes(ns, req, cmd);
> >>  		break;
> >> diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
> >> index 662f95fbd909..5bd5a437b038 100644
> >> --- a/drivers/nvme/host/nvme.h
> >> +++ b/drivers/nvme/host/nvme.h
> >> @@ -708,6 +708,9 @@ int nvme_report_zones(struct gendisk *disk,
> >> sector_t sector,  blk_status_t nvme_setup_zone_mgmt_send(struct
> nvme_ns *ns, struct request *req,
> >>  				       struct nvme_command *cmnd,
> >>  				       enum nvme_zone_mgmt_action action);
> >> +
> >> +blk_status_t nvme_setup_zone_set_desc(struct nvme_ns *ns, struct
> request *req,
> >> +				       struct nvme_command *cmnd);
> >>  #else
> >>  #define nvme_report_zones NULL
> >>
> >> @@ -718,6 +721,12 @@ static inline blk_status_t
> nvme_setup_zone_mgmt_send(struct nvme_ns *ns,
> >>  	return BLK_STS_NOTSUPP;
> >>  }
> >>
> >> +static inline blk_status_t nvme_setup_zone_set_desc(struct nvme_ns *ns,
> >> +		struct request *req, struct nvme_command *cmnd) {
> >> +	return BLK_STS_NOTSUPP;
> >> +}
> >> +
> >>  static inline int nvme_update_zone_info(struct gendisk *disk,
> >>  					struct nvme_ns *ns,
> >>  					unsigned lbaf)
> >> diff --git a/drivers/nvme/host/zns.c b/drivers/nvme/host/zns.c index
> >> 5792d953a8f3..bfa64cc685d3 100644
> >> --- a/drivers/nvme/host/zns.c
> >> +++ b/drivers/nvme/host/zns.c
> >> @@ -239,3 +239,14 @@ blk_status_t
> nvme_setup_zone_mgmt_send(struct
> >> nvme_ns *ns, struct request *req,
> >>
> >>  	return BLK_STS_OK;
> >>  }
> >> +
> >> +blk_status_t nvme_setup_zone_set_desc(struct nvme_ns *ns, struct
> request *req,
> >> +		struct nvme_command *c)
> >> +{
> >> +	c->zms.opcode = nvme_cmd_zone_mgmt_send;
> >> +	c->zms.nsid = cpu_to_le32(ns->head->ns_id);
> >> +	c->zms.slba = cpu_to_le64(nvme_sect_to_lba(ns, blk_rq_pos(req)));
> >> +	c->zms.action = NVME_ZONE_SET_DESC_EXT;
> >> +
> >> +	return BLK_STS_OK;
> >> +}
> >> diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
> >> index ccb895f911b1..53b7b05b0004 100644
> >> --- a/include/linux/blk_types.h
> >> +++ b/include/linux/blk_types.h
> >> @@ -316,6 +316,8 @@ enum req_opf {
> >>  	REQ_OP_ZONE_FINISH	= 12,
> >>  	/* write data at the current zone write pointer */
> >>  	REQ_OP_ZONE_APPEND	= 13,
> >> +	/* associate zone desc extension data to a zone */
> >> +	REQ_OP_ZONE_SET_DESC	= 14,
> >>
> >>  	/* SCSI passthrough using struct scsi_request */
> >>  	REQ_OP_SCSI_IN		= 32,
> >> diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index
> >> 2ed55055f68d..c5f092dd5aa3 100644
> >> --- a/include/linux/blkdev.h
> >> +++ b/include/linux/blkdev.h
> >> @@ -370,7 +370,8 @@ extern int blkdev_report_zones_ioctl(struct
> block_device *bdev, fmode_t mode,
> >>  				     unsigned int cmd, unsigned long arg);
> extern int
> >> blkdev_zone_mgmt_ioctl(struct block_device *bdev, fmode_t mode,
> >>  				  unsigned int cmd, unsigned long arg);
> >> -
> >> +extern int blkdev_zone_set_desc_ioctl(struct block_device *bdev,
> fmode_t mode,
> >> +				      unsigned int cmd, unsigned long arg);
> >>  #else /* CONFIG_BLK_DEV_ZONED */
> >>
> >>  static inline unsigned int blkdev_nr_zones(struct gendisk *disk) @@
> >> -392,6 +393,12 @@ static inline int blkdev_zone_mgmt_ioctl(struct
> block_device *bdev,
> >>  	return -ENOTTY;
> >>  }
> >>
> >> +static inline int blkdev_zone_set_desc_ioctl(struct block_device *bdev,
> >> +					     fmode_t mode, unsigned int cmd,
> >> +					     unsigned long arg)
> >> +{
> >> +	return -ENOTTY;
> >> +}
> >>  #endif /* CONFIG_BLK_DEV_ZONED */
> >>
> >>  struct request_queue {
> >> diff --git a/include/uapi/linux/blkzoned.h
> >> b/include/uapi/linux/blkzoned.h index 42c3366cc25f..68abda9abf33
> >> 100644
> >> --- a/include/uapi/linux/blkzoned.h
> >> +++ b/include/uapi/linux/blkzoned.h
> >> @@ -142,6 +142,20 @@ struct blk_zone_range {
> >>  	__u64		nr_sectors;
> >>  };
> >>
> >> +/**
> >> + * struct blk_zone_set_desc - BLKSETDESCZONE ioctl requests
> >> + * @sector: Starting sector of the zone to operate on.
> >> + * @flags: Feature flags.
> >> + * @len: size, in bytes, of the data to be associated to the zone.
> >> + * @data: data to be associated.
> >> + */
> >> +struct blk_zone_set_desc {
> >> +	__u64		sector;
> >> +	__u32		flags;
> >> +	__u32		len;
> >> +	__u8		data[0];
> >> +};
> 
> Would it make sense to add nr_sectors if the host wants to associate the same
> metadata to several zones. The use case would be the grouping of larger zones
> in software.

I believe we get into atomicity concerns if we do ranges, and action only supports a single zone. I like to align with the ZNS API as much as possible, and let the user-space application track errors per set desc ext action.

> 
> >> +
> >>  /**
> >>   * Zoned block device ioctl's:
> >>   *
> >> @@ -158,6 +172,10 @@ struct blk_zone_range {
> >>   *                The 512 B sector range must be zone aligned.
> >>   * @BLKFINISHZONE: Mark the zones as full in the specified sector range.
> >>   *                 The 512 B sector range must be zone aligned.
> >> + * @BLKSETDESCZONE: Set zone description extension data for the zone
> >> + *                  in the specified sector. On success, the zone
> >> + *                  will transition to the closed zone state.
> >> + *                  The 512B sector must be zone aligned.
> >>   */
> >>  #define BLKREPORTZONE	_IOWR(0x12, 130, struct blk_zone_report)
> >>  #define BLKRESETZONE	_IOW(0x12, 131, struct blk_zone_range)
> >> @@ -166,5 +184,5 @@ struct blk_zone_range {
> >>  #define BLKOPENZONE	_IOW(0x12, 134, struct blk_zone_range)
> >>  #define BLKCLOSEZONE	_IOW(0x12, 135, struct blk_zone_range)
> >>  #define BLKFINISHZONE	_IOW(0x12, 136, struct blk_zone_range)
> >> -
> >> +#define BLKSETDESCZONE	_IOW(0x12, 137, struct blk_zone_set_desc)
> >>  #endif /* _UAPI_BLKZONED_H */
> >>
> >
> >How to you retreive an extended descriptor that was set ? I do not see
> >any code doing that. Report zones is not changed, but I would leave
> >that one as is and implement a BLKGETDESCZONE ioctl & in-kernel API.
> >
> 
> In any case, this is needed. I also could not find a way to read the extended
> descriptor back.

Thanks for the feedback.

Besides the users I have in mind, do you have users for which you need the ability for user-space to access zone descriptor extensions data? Is this a need to have or nice to have feature from your point of view?

> 
> Javier

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