[PATCH v8 0/2] ublk: enable zoned storage support

[PATCH v8 0/2] ublk: enable zoned storage support

[Andreas Hindborg]

From: Andreas Hindborg <a.hindborg@samsung.com>

Hi All,

This patch set adds zoned storage support to `ublk`. The first patch does some
house cleaning in preparation for the last patch. The last patch adds support
for report_zones and the following operations:

 - REQ_OP_ZONE_OPEN
 - REQ_OP_ZONE_CLOSE
 - REQ_OP_ZONE_FINISH
 - REQ_OP_ZONE_RESET
 - REQ_OP_ZONE_APPEND

A user space component based on ubdsrv is available for testing [1] with the
"loop" target.

Read/write and zone operations are tested with zenfs [2].

The zone append path is tested with fio -> zonefs -> ublk -> null_blk.

The implementation of zone append requires ublk user copy feature, and therefore
the series is based on branch for-next (6afa337a3789) of [3].

Changes for v8
 - Remove __UBLK_IO_OP_DRV_*
 - Move report zones command identifier (UBLK_IO_OP_REPORT_ZONES) next to other
   zone management operations

Changes for v7
 - Style fixes
 - Rework error handling for `ublk_ctrl_start_dev()`
 - Remove `BLK_DEV_UBLK_ZONED`
 - Add check for IO command support on command enqueue
 - Remove check from `ublk_report_zones()`
 - Hoist check out of `ublk_revalidate_disk_zones()`
 - Remove check from `ublk_dev_param_zoned_apply()` when !CONFIG_BLK_DEV_ZONED
 - Rename `get_nr_zones()` -> `ublk_get_nr_zones()`
 - Open code `set_nr_zones()` in `ublk_param_zoned_apply()`
 - Reorder fields of `struct ublk_rq_data` to pack better
 - Remove redundant checks for chunk_sectors
 - Hoist check for user not setting zoned parameters for zoned ublk device out
   of `ublk_param_zoned_validate()`
 - Remove helper `ublk_dev_params_zoned()`

[1] https://github.com/metaspace/ubdsrv/tree/acc072e077bceea390bae14b6ccb8087f6d0cf1a
[2] https://github.com/westerndigitalcorporation/zenfs
[3] https://git.kernel.dk/linux.git

Andreas Hindborg (2):
  ublk: add helper to check if device supports user copy
  ublk: enable zoned storage support

 drivers/block/ublk_drv.c      | 321 ++++++++++++++++++++++++++++++++--
 include/uapi/linux/ublk_cmd.h |  36 +++-
 2 files changed, 337 insertions(+), 20 deletions(-)


base-commit: 3261ea42710e9665c9151006049411bd23b5411f
-- 
2.41.0

[PATCH v8 1/2] ublk: add helper to check if device supports user copy

[Andreas Hindborg]

From: Andreas Hindborg <a.hindborg@samsung.com>

This will be used by ublk zoned storage support.

Signed-off-by: Andreas Hindborg <a.hindborg@samsung.com>
---
 drivers/block/ublk_drv.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 1c823750c95a..8d271901efac 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -185,6 +185,11 @@ struct ublk_params_header {
 	__u32	types;
 };
 
+static inline bool ublk_dev_is_user_copy(const struct ublk_device *ub)
+{
+	return ub->dev_info.flags & UBLK_F_USER_COPY;
+}
+
 static inline void __ublk_complete_rq(struct request *req);
 static void ublk_complete_rq(struct kref *ref);
 
@@ -2037,7 +2042,7 @@ static int ublk_ctrl_add_dev(struct io_uring_cmd *cmd)
 		UBLK_F_URING_CMD_COMP_IN_TASK;
 
 	/* GET_DATA isn't needed any more with USER_COPY */
-	if (ub->dev_info.flags & UBLK_F_USER_COPY)
+	if (ublk_dev_is_user_copy(ub))
 		ub->dev_info.flags &= ~UBLK_F_NEED_GET_DATA;
 
 	/* We are not ready to support zero copy */
-- 
2.41.0

Re: [PATCH v8 1/2] ublk: add helper to check if device supports user copy

[Ming Lei]

On Tue, Jul 11, 2023 at 09:23:52AM +0200, Andreas Hindborg wrote:
> From: Andreas Hindborg <a.hindborg@samsung.com>
> 
> This will be used by ublk zoned storage support.
> 
> Signed-off-by: Andreas Hindborg <a.hindborg@samsung.com>
> ---

Reviewed-by: Ming Lei <ming.lei@redhat.com>

BTW, both Damien and I have reviewed this one, and you can put the
reviewed-by tag in patch.

Thanks,
Ming

Re: [PATCH v8 1/2] ublk: add helper to check if device supports user copy

[Andreas Hindborg (Samsung)]

Ming Lei <ming.lei@redhat.com> writes:

> On Tue, Jul 11, 2023 at 09:23:52AM +0200, Andreas Hindborg wrote:
>> From: Andreas Hindborg <a.hindborg@samsung.com>
>> 
>> This will be used by ublk zoned storage support.
>> 
>> Signed-off-by: Andreas Hindborg <a.hindborg@samsung.com>
>> ---
>
> Reviewed-by: Ming Lei <ming.lei@redhat.com>
>
> BTW, both Damien and I have reviewed this one, and you can put the
> reviewed-by tag in patch.

Argh, I knew there was something I forgot for v9. Sorry.

BR Andreas

[PATCH v8 2/2] ublk: enable zoned storage support

[Andreas Hindborg]

From: Andreas Hindborg <a.hindborg@samsung.com>

Add zoned storage support to ublk: report_zones and operations:
 - REQ_OP_ZONE_OPEN
 - REQ_OP_ZONE_CLOSE
 - REQ_OP_ZONE_FINISH
 - REQ_OP_ZONE_RESET
 - REQ_OP_ZONE_APPEND

The zone append feature uses the `addr` field of `struct ublksrv_io_cmd` to
communicate ALBA back to the kernel. Therefore ublk must be used with the
user copy feature (UBLK_F_USER_COPY) for zoned storage support to be
available. Without this feature, ublk will not allow zoned storage support.

Signed-off-by: Andreas Hindborg <a.hindborg@samsung.com>
---
 drivers/block/ublk_drv.c      | 314 ++++++++++++++++++++++++++++++++--
 include/uapi/linux/ublk_cmd.h |  36 +++-
 2 files changed, 331 insertions(+), 19 deletions(-)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 8d271901efac..a57be961b708 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -56,16 +56,21 @@
 		| UBLK_F_USER_RECOVERY_REISSUE \
 		| UBLK_F_UNPRIVILEGED_DEV \
 		| UBLK_F_CMD_IOCTL_ENCODE \
-		| UBLK_F_USER_COPY)
+		| UBLK_F_USER_COPY \
+		| UBLK_F_ZONED)
 
 /* All UBLK_PARAM_TYPE_* should be included here */
-#define UBLK_PARAM_TYPE_ALL (UBLK_PARAM_TYPE_BASIC | \
-		UBLK_PARAM_TYPE_DISCARD | UBLK_PARAM_TYPE_DEVT)
+#define UBLK_PARAM_TYPE_ALL                                \
+	(UBLK_PARAM_TYPE_BASIC | UBLK_PARAM_TYPE_DISCARD | \
+	 UBLK_PARAM_TYPE_DEVT | UBLK_PARAM_TYPE_ZONED)
 
 struct ublk_rq_data {
 	struct llist_node node;
 
 	struct kref ref;
+	__u64 sector;
+	__u32 operation;
+	__u32 nr_sectors;
 };
 
 struct ublk_uring_cmd_pdu {
@@ -110,6 +115,11 @@ struct ublk_uring_cmd_pdu {
  */
 #define UBLK_IO_FLAG_NEED_GET_DATA 0x08
 
+/*
+ * Set when IO is Zone Append
+ */
+#define UBLK_IO_FLAG_ZONE_APPEND 0x10
+
 struct ublk_io {
 	/* userspace buffer address from io cmd */
 	__u64	addr;
@@ -190,6 +200,198 @@ static inline bool ublk_dev_is_user_copy(const struct ublk_device *ub)
 	return ub->dev_info.flags & UBLK_F_USER_COPY;
 }
 
+static inline bool ublk_dev_is_zoned(const struct ublk_device *ub)
+{
+	return ub->dev_info.flags & UBLK_F_ZONED;
+}
+
+static inline bool ublk_queue_is_zoned(struct ublk_queue *ubq)
+{
+	return ubq->flags & UBLK_F_ZONED;
+}
+
+#ifdef CONFIG_BLK_DEV_ZONED
+
+static int ublk_get_nr_zones(const struct ublk_device *ub)
+{
+	const struct ublk_param_basic *p = &ub->params.basic;
+
+	/* Zone size is a power of 2 */
+	return p->dev_sectors >> ilog2(p->chunk_sectors);
+}
+
+static int ublk_revalidate_disk_zones(struct ublk_device *ub)
+{
+	return blk_revalidate_disk_zones(ub->ub_disk, NULL);
+}
+
+static int ublk_dev_param_zoned_validate(const struct ublk_device *ub)
+{
+	const struct ublk_param_zoned *p = &ub->params.zoned;
+	int nr_zones;
+
+	if (!ublk_dev_is_zoned(ub))
+		return -EINVAL;
+
+	if (!p->max_zone_append_sectors)
+		return -EINVAL;
+
+	nr_zones = ublk_get_nr_zones(ub);
+
+	if (p->max_active_zones > nr_zones)
+		return -EINVAL;
+
+	if (p->max_open_zones > nr_zones)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int ublk_dev_param_zoned_apply(struct ublk_device *ub)
+{
+	const struct ublk_param_zoned *p = &ub->params.zoned;
+
+	disk_set_zoned(ub->ub_disk, BLK_ZONED_HM);
+	blk_queue_required_elevator_features(ub->ub_disk->queue,
+					     ELEVATOR_F_ZBD_SEQ_WRITE);
+	disk_set_max_active_zones(ub->ub_disk, p->max_active_zones);
+	disk_set_max_open_zones(ub->ub_disk, p->max_open_zones);
+	blk_queue_max_zone_append_sectors(ub->ub_disk->queue, p->max_zone_append_sectors);
+
+	ub->ub_disk->nr_zones = ublk_get_nr_zones(ub);
+
+	return 0;
+}
+
+/* Based on virtblk_alloc_report_buffer */
+static void *ublk_alloc_report_buffer(struct ublk_device *ublk,
+				      unsigned int nr_zones, size_t *buflen)
+{
+	struct request_queue *q = ublk->ub_disk->queue;
+	size_t bufsize;
+	void *buf;
+
+	nr_zones = min_t(unsigned int, nr_zones,
+			 ublk->ub_disk->nr_zones);
+
+	bufsize = nr_zones * sizeof(struct blk_zone);
+	bufsize =
+		min_t(size_t, bufsize, queue_max_hw_sectors(q) << SECTOR_SHIFT);
+	bufsize = min_t(size_t, bufsize, queue_max_segments(q) << PAGE_SHIFT);
+
+	while (bufsize >= sizeof(struct blk_zone)) {
+		buf = __vmalloc(bufsize, GFP_KERNEL | __GFP_NORETRY);
+		if (buf) {
+			*buflen = bufsize;
+			return buf;
+		}
+		bufsize >>= 1;
+	}
+
+	*buflen = 0;
+	return NULL;
+}
+
+static int ublk_report_zones(struct gendisk *disk, sector_t sector,
+		      unsigned int nr_zones, report_zones_cb cb, void *data)
+{
+	struct ublk_device *ub = disk->private_data;
+	unsigned int zone_size_sectors = disk->queue->limits.chunk_sectors;
+	unsigned int first_zone = sector >> ilog2(zone_size_sectors);
+	unsigned int done_zones = 0;
+	unsigned int max_zones_per_request;
+	int ret;
+	struct blk_zone *buffer;
+	size_t buffer_length;
+
+	nr_zones = min_t(unsigned int, ub->ub_disk->nr_zones - first_zone,
+			 nr_zones);
+
+	buffer = ublk_alloc_report_buffer(ub, nr_zones, &buffer_length);
+	if (!buffer)
+		return -ENOMEM;
+
+	max_zones_per_request = buffer_length / sizeof(struct blk_zone);
+
+	while (done_zones < nr_zones) {
+		unsigned int remaining_zones = nr_zones - done_zones;
+		unsigned int zones_in_request =
+			min_t(unsigned int, remaining_zones, max_zones_per_request);
+		struct request *req;
+		struct ublk_rq_data *pdu;
+		blk_status_t status;
+
+		memset(buffer, 0, buffer_length);
+
+		req = blk_mq_alloc_request(disk->queue, REQ_OP_DRV_IN, 0);
+		if (IS_ERR(req)) {
+			ret = PTR_ERR(req);
+			goto out;
+		}
+
+		pdu = blk_mq_rq_to_pdu(req);
+		pdu->operation = UBLK_IO_OP_REPORT_ZONES;
+		pdu->sector = sector;
+		pdu->nr_sectors = remaining_zones * zone_size_sectors;
+
+		ret = blk_rq_map_kern(disk->queue, req, buffer, buffer_length,
+					GFP_KERNEL);
+		if (ret) {
+			blk_mq_free_request(req);
+			goto out;
+		}
+
+		status = blk_execute_rq(req, 0);
+		ret = blk_status_to_errno(status);
+		blk_mq_free_request(req);
+		if (ret)
+			goto out;
+
+		for (unsigned int i = 0; i < zones_in_request; i++) {
+			struct blk_zone *zone = buffer + i;
+
+			/* A zero length zone means no more zones in this response */
+			if (!zone->len)
+				break;
+
+			ret = cb(zone, i, data);
+			if (ret)
+				goto out;
+
+			done_zones++;
+			sector += zone_size_sectors;
+
+		}
+	}
+
+	ret = done_zones;
+
+out:
+	kvfree(buffer);
+	return ret;
+}
+
+#else
+
+#define ublk_report_zones (NULL)
+
+static int ublk_dev_param_zoned_validate(const struct ublk_device *ub)
+{
+	return -EOPNOTSUPP;
+}
+
+static int ublk_dev_param_zoned_apply(struct ublk_device *ub)
+{
+	return -EOPNOTSUPP;
+}
+
+static int ublk_revalidate_disk_zones(struct ublk_device *ub)
+{
+	return 0;
+}
+
+#endif
+
 static inline void __ublk_complete_rq(struct request *req);
 static void ublk_complete_rq(struct kref *ref);
 
@@ -232,7 +434,7 @@ static inline unsigned ublk_pos_to_tag(loff_t pos)
 		UBLK_TAG_BITS_MASK;
 }
 
-static void ublk_dev_param_basic_apply(struct ublk_device *ub)
+static int ublk_dev_param_basic_apply(struct ublk_device *ub)
 {
 	struct request_queue *q = ub->ub_disk->queue;
 	const struct ublk_param_basic *p = &ub->params.basic;
@@ -257,6 +459,8 @@ static void ublk_dev_param_basic_apply(struct ublk_device *ub)
 		set_disk_ro(ub->ub_disk, true);
 
 	set_capacity(ub->ub_disk, p->dev_sectors);
+
+	return 0;
 }
 
 static void ublk_dev_param_discard_apply(struct ublk_device *ub)
@@ -286,6 +490,9 @@ static int ublk_validate_params(const struct ublk_device *ub)
 
 		if (p->max_sectors > (ub->dev_info.max_io_buf_bytes >> 9))
 			return -EINVAL;
+
+		if (ublk_dev_is_zoned(ub) && !p->chunk_sectors)
+			return -EINVAL;
 	} else
 		return -EINVAL;
 
@@ -304,19 +511,31 @@ static int ublk_validate_params(const struct ublk_device *ub)
 	if (ub->params.types & UBLK_PARAM_TYPE_DEVT)
 		return -EINVAL;
 
+	if (ub->params.types & UBLK_PARAM_TYPE_ZONED)
+		return ublk_dev_param_zoned_validate(ub);
+	else if (ublk_dev_is_zoned(ub))
+		return -EINVAL;
+
 	return 0;
 }
 
 static int ublk_apply_params(struct ublk_device *ub)
 {
+	int ret;
+
 	if (!(ub->params.types & UBLK_PARAM_TYPE_BASIC))
 		return -EINVAL;
 
-	ublk_dev_param_basic_apply(ub);
+	ret = ublk_dev_param_basic_apply(ub);
+	if (ret)
+		return ret;
 
 	if (ub->params.types & UBLK_PARAM_TYPE_DISCARD)
 		ublk_dev_param_discard_apply(ub);
 
+	if (ub->params.types & UBLK_PARAM_TYPE_ZONED)
+		return ublk_dev_param_zoned_apply(ub);
+
 	return 0;
 }
 
@@ -487,6 +706,7 @@ static const struct block_device_operations ub_fops = {
 	.owner =	THIS_MODULE,
 	.open =		ublk_open,
 	.free_disk =	ublk_free_disk,
+	.report_zones =	ublk_report_zones,
 };
 
 #define UBLK_MAX_PIN_PAGES	32
@@ -601,7 +821,8 @@ static inline bool ublk_need_map_req(const struct request *req)
 
 static inline bool ublk_need_unmap_req(const struct request *req)
 {
-	return ublk_rq_has_data(req) && req_op(req) == REQ_OP_READ;
+	return ublk_rq_has_data(req) &&
+	       (req_op(req) == REQ_OP_READ || req_op(req) == REQ_OP_DRV_IN);
 }
 
 static int ublk_map_io(const struct ublk_queue *ubq, const struct request *req,
@@ -685,8 +906,14 @@ static blk_status_t ublk_setup_iod(struct ublk_queue *ubq, struct request *req)
 {
 	struct ublksrv_io_desc *iod = ublk_get_iod(ubq, req->tag);
 	struct ublk_io *io = &ubq->ios[req->tag];
+	struct ublk_rq_data *pdu = blk_mq_rq_to_pdu(req);
+	enum req_op op = req_op(req);
 	u32 ublk_op;
 
+	if (!ublk_queue_is_zoned(ubq) &&
+	    (op_is_zone_mgmt(op) || op == REQ_OP_ZONE_APPEND))
+		return -EIO;
+
 	switch (req_op(req)) {
 	case REQ_OP_READ:
 		ublk_op = UBLK_IO_OP_READ;
@@ -703,6 +930,37 @@ static blk_status_t ublk_setup_iod(struct ublk_queue *ubq, struct request *req)
 	case REQ_OP_WRITE_ZEROES:
 		ublk_op = UBLK_IO_OP_WRITE_ZEROES;
 		break;
+	case REQ_OP_ZONE_OPEN:
+		ublk_op = UBLK_IO_OP_ZONE_OPEN;
+		break;
+	case REQ_OP_ZONE_CLOSE:
+		ublk_op = UBLK_IO_OP_ZONE_CLOSE;
+		break;
+	case REQ_OP_ZONE_FINISH:
+		ublk_op = UBLK_IO_OP_ZONE_FINISH;
+		break;
+	case REQ_OP_ZONE_RESET:
+		ublk_op = UBLK_IO_OP_ZONE_RESET;
+		break;
+	case REQ_OP_DRV_IN:
+		ublk_op = pdu->operation;
+		switch (ublk_op) {
+		case UBLK_IO_OP_REPORT_ZONES:
+			iod->op_flags = ublk_op | ublk_req_build_flags(req);
+			iod->nr_sectors = pdu->nr_sectors;
+			iod->start_sector = pdu->sector;
+			return BLK_STS_OK;
+		default:
+			return BLK_STS_IOERR;
+		}
+	case REQ_OP_ZONE_APPEND:
+		ublk_op = UBLK_IO_OP_ZONE_APPEND;
+		io->flags |= UBLK_IO_FLAG_ZONE_APPEND;
+		break;
+	case REQ_OP_ZONE_RESET_ALL:
+	case REQ_OP_DRV_OUT:
+		/* We do not support reset_all and drv_out */
+		return BLK_STS_NOTSUPP;
 	default:
 		return BLK_STS_IOERR;
 	}
@@ -756,7 +1014,8 @@ static inline void __ublk_complete_rq(struct request *req)
 	 *
 	 * Both the two needn't unmap.
 	 */
-	if (req_op(req) != REQ_OP_READ && req_op(req) != REQ_OP_WRITE)
+	if (req_op(req) != REQ_OP_READ && req_op(req) != REQ_OP_WRITE &&
+	    req_op(req) != REQ_OP_DRV_IN)
 		goto exit;
 
 	/* for READ request, writing data in iod->addr to rq buffers */
@@ -1120,6 +1379,11 @@ static void ublk_commit_completion(struct ublk_device *ub,
 	/* find the io request and complete */
 	req = blk_mq_tag_to_rq(ub->tag_set.tags[qid], tag);
 
+	if (io->flags & UBLK_IO_FLAG_ZONE_APPEND) {
+		req->__sector = ub_cmd->addr;
+		io->flags &= ~UBLK_IO_FLAG_ZONE_APPEND;
+	}
+
 	if (req && likely(!blk_should_fake_timeout(req->q)))
 		ublk_put_req_ref(ubq, req);
 }
@@ -1419,7 +1683,8 @@ static int __ublk_ch_uring_cmd(struct io_uring_cmd *cmd,
 			^ (_IOC_NR(cmd_op) == UBLK_IO_NEED_GET_DATA))
 		goto out;
 
-	if (ublk_support_user_copy(ubq) && ub_cmd->addr) {
+	if (ublk_support_user_copy(ubq) &&
+	    !(io->flags & UBLK_IO_FLAG_ZONE_APPEND) && ub_cmd->addr) {
 		ret = -EINVAL;
 		goto out;
 	}
@@ -1542,11 +1807,14 @@ static inline bool ublk_check_ubuf_dir(const struct request *req,
 		int ubuf_dir)
 {
 	/* copy ubuf to request pages */
-	if (req_op(req) == REQ_OP_READ && ubuf_dir == ITER_SOURCE)
+	if ((req_op(req) == REQ_OP_READ || req_op(req) == REQ_OP_DRV_IN) &&
+	    ubuf_dir == ITER_SOURCE)
 		return true;
 
 	/* copy request pages to ubuf */
-	if (req_op(req) == REQ_OP_WRITE && ubuf_dir == ITER_DEST)
+	if ((req_op(req) == REQ_OP_WRITE ||
+	     req_op(req) == REQ_OP_ZONE_APPEND) &&
+	    ubuf_dir == ITER_DEST)
 		return true;
 
 	return false;
@@ -1885,17 +2153,24 @@ static int ublk_ctrl_start_dev(struct ublk_device *ub, struct io_uring_cmd *cmd)
 
 	get_device(&ub->cdev_dev);
 	ub->dev_info.state = UBLK_S_DEV_LIVE;
+
+	if (ublk_dev_is_zoned(ub)) {
+		ret = ublk_revalidate_disk_zones(ub);
+		if (ret)
+			goto out_put_cdev;
+	}
+
 	ret = add_disk(disk);
+	if (ret)
+		goto out_put_cdev;
+
+	set_bit(UB_STATE_USED, &ub->state);
+
+out_put_cdev:
 	if (ret) {
-		/*
-		 * Has to drop the reference since ->free_disk won't be
-		 * called in case of add_disk failure.
-		 */
 		ub->dev_info.state = UBLK_S_DEV_DEAD;
 		ublk_put_device(ub);
-		goto out_put_disk;
 	}
-	set_bit(UB_STATE_USED, &ub->state);
 out_put_disk:
 	if (ret)
 		put_disk(disk);
@@ -2045,6 +2320,13 @@ static int ublk_ctrl_add_dev(struct io_uring_cmd *cmd)
 	if (ublk_dev_is_user_copy(ub))
 		ub->dev_info.flags &= ~UBLK_F_NEED_GET_DATA;
 
+	/* Zoned storage support requires user copy feature */
+	if (ublk_dev_is_zoned(ub) &&
+	    (!IS_ENABLED(CONFIG_BLK_DEV_ZONED) || !ublk_dev_is_user_copy(ub))) {
+		ret = -EINVAL;
+		goto out_free_dev_number;
+	}
+
 	/* We are not ready to support zero copy */
 	ub->dev_info.flags &= ~UBLK_F_SUPPORT_ZERO_COPY;
 
diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h
index 4b8558db90e1..4d97eb0f7d13 100644
--- a/include/uapi/linux/ublk_cmd.h
+++ b/include/uapi/linux/ublk_cmd.h
@@ -176,6 +176,12 @@
 /* Copy between request and user buffer by pread()/pwrite() */
 #define UBLK_F_USER_COPY	(1UL << 7)
 
+/*
+ * User space sets this flag when setting up the device to request zoned storage support. Kernel may
+ * deny the request by returning an error.
+ */
+#define UBLK_F_ZONED (1ULL << 8)
+
 /* device state */
 #define UBLK_S_DEV_DEAD	0
 #define UBLK_S_DEV_LIVE	1
@@ -232,9 +238,24 @@ struct ublksrv_ctrl_dev_info {
 #define		UBLK_IO_OP_READ		0
 #define		UBLK_IO_OP_WRITE		1
 #define		UBLK_IO_OP_FLUSH		2
-#define		UBLK_IO_OP_DISCARD	3
-#define		UBLK_IO_OP_WRITE_SAME	4
-#define		UBLK_IO_OP_WRITE_ZEROES	5
+#define		UBLK_IO_OP_DISCARD		3
+#define		UBLK_IO_OP_WRITE_SAME		4
+#define		UBLK_IO_OP_WRITE_ZEROES		5
+#define		UBLK_IO_OP_ZONE_OPEN		10
+#define		UBLK_IO_OP_ZONE_CLOSE		11
+#define		UBLK_IO_OP_ZONE_FINISH		12
+#define		UBLK_IO_OP_ZONE_APPEND		13
+#define		UBLK_IO_OP_ZONE_RESET		15
+/*
+ * Construct a zone report. The report request is carried in `struct
+ * ublksrv_io_desc`. The `start_sector` field must be the first sector of a zone
+ * and shall indicate the first zone of the report. The `nr_sectors` shall
+ * indicate how many zones should be reported (divide by zone size to get number
+ * of zones in the report) and must be an integer multiple of the zone size. The
+ * report shall be delivered as a `struct blk_zone` array. To report fewer zones
+ * than requested, zero the last entry of the returned array.
+ */
+#define		UBLK_IO_OP_REPORT_ZONES		18
 
 #define		UBLK_IO_F_FAILFAST_DEV		(1U << 8)
 #define		UBLK_IO_F_FAILFAST_TRANSPORT	(1U << 9)
@@ -331,6 +352,13 @@ struct ublk_param_devt {
 	__u32   disk_minor;
 };
 
+struct ublk_param_zoned {
+	__u32	max_open_zones;
+	__u32	max_active_zones;
+	__u32	max_zone_append_sectors;
+	__u8	reserved[20];
+};
+
 struct ublk_params {
 	/*
 	 * Total length of parameters, userspace has to set 'len' for both
@@ -342,11 +370,13 @@ struct ublk_params {
 #define UBLK_PARAM_TYPE_BASIC           (1 << 0)
 #define UBLK_PARAM_TYPE_DISCARD         (1 << 1)
 #define UBLK_PARAM_TYPE_DEVT            (1 << 2)
+#define UBLK_PARAM_TYPE_ZONED           (1 << 3)
 	__u32	types;			/* types of parameter included */
 
 	struct ublk_param_basic		basic;
 	struct ublk_param_discard	discard;
 	struct ublk_param_devt		devt;
+	struct ublk_param_zoned	zoned;
 };
 
 #endif
-- 
2.41.0

Re: [PATCH v8 2/2] ublk: enable zoned storage support

[Ming Lei]

On Tue, Jul 11, 2023 at 09:23:53AM +0200, Andreas Hindborg wrote:
> From: Andreas Hindborg <a.hindborg@samsung.com>
> 
> Add zoned storage support to ublk: report_zones and operations:
>  - REQ_OP_ZONE_OPEN
>  - REQ_OP_ZONE_CLOSE
>  - REQ_OP_ZONE_FINISH
>  - REQ_OP_ZONE_RESET
>  - REQ_OP_ZONE_APPEND
> 
> The zone append feature uses the `addr` field of `struct ublksrv_io_cmd` to
> communicate ALBA back to the kernel. Therefore ublk must be used with the
> user copy feature (UBLK_F_USER_COPY) for zoned storage support to be
> available. Without this feature, ublk will not allow zoned storage support.

Without one userspace implementation, it is hard to verify the kernel
change, so I write one zoned target example based on libublk-rs by
taking one day.

https://github.com/ming1/libublk-rs.git [1]

It is one zoned-ramdisk example, and should be easy to
add persistence zoned. All zoned commands are covered, except for
REQ_OP_ZONE_RESET_ALL.

How to create ublk-zoned:

	cargo run --example zoned -- add -1 1024   #1024MB

So far it passes all blktests/zbd tests for external zoned device.

'mkfs.btrfs -O zoned' & mount & git clone linux_kernel in this btrfs
works.

So this patchset gets verified now, so far so good.

[1] not publish to crates.io yet, still need some cleanup

> 
> Signed-off-by: Andreas Hindborg <a.hindborg@samsung.com>
> ---
>  drivers/block/ublk_drv.c      | 314 ++++++++++++++++++++++++++++++++--
>  include/uapi/linux/ublk_cmd.h |  36 +++-
>  2 files changed, 331 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> index 8d271901efac..a57be961b708 100644
> --- a/drivers/block/ublk_drv.c
> +++ b/drivers/block/ublk_drv.c
> @@ -56,16 +56,21 @@
>  		| UBLK_F_USER_RECOVERY_REISSUE \
>  		| UBLK_F_UNPRIVILEGED_DEV \
>  		| UBLK_F_CMD_IOCTL_ENCODE \
> -		| UBLK_F_USER_COPY)
> +		| UBLK_F_USER_COPY \
> +		| UBLK_F_ZONED)
>  
>  /* All UBLK_PARAM_TYPE_* should be included here */
> -#define UBLK_PARAM_TYPE_ALL (UBLK_PARAM_TYPE_BASIC | \
> -		UBLK_PARAM_TYPE_DISCARD | UBLK_PARAM_TYPE_DEVT)
> +#define UBLK_PARAM_TYPE_ALL                                \
> +	(UBLK_PARAM_TYPE_BASIC | UBLK_PARAM_TYPE_DISCARD | \
> +	 UBLK_PARAM_TYPE_DEVT | UBLK_PARAM_TYPE_ZONED)
>  
>  struct ublk_rq_data {
>  	struct llist_node node;
>  
>  	struct kref ref;
> +	__u64 sector;
> +	__u32 operation;
> +	__u32 nr_sectors;
>  };
>  
>  struct ublk_uring_cmd_pdu {
> @@ -110,6 +115,11 @@ struct ublk_uring_cmd_pdu {
>   */
>  #define UBLK_IO_FLAG_NEED_GET_DATA 0x08
>  
> +/*
> + * Set when IO is Zone Append
> + */
> +#define UBLK_IO_FLAG_ZONE_APPEND 0x10
> +
>  struct ublk_io {
>  	/* userspace buffer address from io cmd */
>  	__u64	addr;
> @@ -190,6 +200,198 @@ static inline bool ublk_dev_is_user_copy(const struct ublk_device *ub)
>  	return ub->dev_info.flags & UBLK_F_USER_COPY;
>  }
>  
> +static inline bool ublk_dev_is_zoned(const struct ublk_device *ub)
> +{
> +	return ub->dev_info.flags & UBLK_F_ZONED;
> +}
> +
> +static inline bool ublk_queue_is_zoned(struct ublk_queue *ubq)
> +{
> +	return ubq->flags & UBLK_F_ZONED;
> +}
> +
> +#ifdef CONFIG_BLK_DEV_ZONED
> +
> +static int ublk_get_nr_zones(const struct ublk_device *ub)
> +{
> +	const struct ublk_param_basic *p = &ub->params.basic;
> +
> +	/* Zone size is a power of 2 */
> +	return p->dev_sectors >> ilog2(p->chunk_sectors);
> +}
> +
> +static int ublk_revalidate_disk_zones(struct ublk_device *ub)
> +{
> +	return blk_revalidate_disk_zones(ub->ub_disk, NULL);
> +}
> +
> +static int ublk_dev_param_zoned_validate(const struct ublk_device *ub)
> +{
> +	const struct ublk_param_zoned *p = &ub->params.zoned;
> +	int nr_zones;
> +
> +	if (!ublk_dev_is_zoned(ub))
> +		return -EINVAL;
> +
> +	if (!p->max_zone_append_sectors)
> +		return -EINVAL;
> +
> +	nr_zones = ublk_get_nr_zones(ub);
> +
> +	if (p->max_active_zones > nr_zones)
> +		return -EINVAL;
> +
> +	if (p->max_open_zones > nr_zones)
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static int ublk_dev_param_zoned_apply(struct ublk_device *ub)
> +{
> +	const struct ublk_param_zoned *p = &ub->params.zoned;
> +
> +	disk_set_zoned(ub->ub_disk, BLK_ZONED_HM);
> +	blk_queue_required_elevator_features(ub->ub_disk->queue,
> +					     ELEVATOR_F_ZBD_SEQ_WRITE);
> +	disk_set_max_active_zones(ub->ub_disk, p->max_active_zones);
> +	disk_set_max_open_zones(ub->ub_disk, p->max_open_zones);
> +	blk_queue_max_zone_append_sectors(ub->ub_disk->queue, p->max_zone_append_sectors);
> +
> +	ub->ub_disk->nr_zones = ublk_get_nr_zones(ub);
> +
> +	return 0;
> +}
> +
> +/* Based on virtblk_alloc_report_buffer */
> +static void *ublk_alloc_report_buffer(struct ublk_device *ublk,
> +				      unsigned int nr_zones, size_t *buflen)
> +{
> +	struct request_queue *q = ublk->ub_disk->queue;
> +	size_t bufsize;
> +	void *buf;
> +
> +	nr_zones = min_t(unsigned int, nr_zones,
> +			 ublk->ub_disk->nr_zones);
> +
> +	bufsize = nr_zones * sizeof(struct blk_zone);
> +	bufsize =
> +		min_t(size_t, bufsize, queue_max_hw_sectors(q) << SECTOR_SHIFT);
> +	bufsize = min_t(size_t, bufsize, queue_max_segments(q) << PAGE_SHIFT);

'bufsize' shouldn't related with queue_max_segments() given we don't
enable segment limit yet.

> +
> +	while (bufsize >= sizeof(struct blk_zone)) {
> +		buf = __vmalloc(bufsize, GFP_KERNEL | __GFP_NORETRY);
> +		if (buf) {
> +			*buflen = bufsize;
> +			return buf;
> +		}
> +		bufsize >>= 1;
> +	}
> +
> +	*buflen = 0;
> +	return NULL;
> +}
> +
> +static int ublk_report_zones(struct gendisk *disk, sector_t sector,
> +		      unsigned int nr_zones, report_zones_cb cb, void *data)
> +{
> +	struct ublk_device *ub = disk->private_data;
> +	unsigned int zone_size_sectors = disk->queue->limits.chunk_sectors;
> +	unsigned int first_zone = sector >> ilog2(zone_size_sectors);
> +	unsigned int done_zones = 0;
> +	unsigned int max_zones_per_request;
> +	int ret;
> +	struct blk_zone *buffer;
> +	size_t buffer_length;
> +
> +	nr_zones = min_t(unsigned int, ub->ub_disk->nr_zones - first_zone,
> +			 nr_zones);
> +
> +	buffer = ublk_alloc_report_buffer(ub, nr_zones, &buffer_length);
> +	if (!buffer)
> +		return -ENOMEM;
> +
> +	max_zones_per_request = buffer_length / sizeof(struct blk_zone);
> +
> +	while (done_zones < nr_zones) {
> +		unsigned int remaining_zones = nr_zones - done_zones;
> +		unsigned int zones_in_request =
> +			min_t(unsigned int, remaining_zones, max_zones_per_request);
> +		struct request *req;
> +		struct ublk_rq_data *pdu;
> +		blk_status_t status;
> +
> +		memset(buffer, 0, buffer_length);
> +
> +		req = blk_mq_alloc_request(disk->queue, REQ_OP_DRV_IN, 0);
> +		if (IS_ERR(req)) {
> +			ret = PTR_ERR(req);
> +			goto out;
> +		}
> +
> +		pdu = blk_mq_rq_to_pdu(req);
> +		pdu->operation = UBLK_IO_OP_REPORT_ZONES;
> +		pdu->sector = sector;
> +		pdu->nr_sectors = remaining_zones * zone_size_sectors;

pdu->nr_sectors will be set to ublksrv_io_desc->nr_sectors as part of
UAPI, I feel it is hard to understand to pass 'remaining_zones * zone_size_sectors',
probably it is fine to re-define as buffer size or requested
nr_blk_zone, or other ideas?

> +
> +		ret = blk_rq_map_kern(disk->queue, req, buffer, buffer_length,
> +					GFP_KERNEL);
> +		if (ret) {
> +			blk_mq_free_request(req);
> +			goto out;
> +		}
> +
> +		status = blk_execute_rq(req, 0);
> +		ret = blk_status_to_errno(status);
> +		blk_mq_free_request(req);
> +		if (ret)
> +			goto out;
> +
> +		for (unsigned int i = 0; i < zones_in_request; i++) {
> +			struct blk_zone *zone = buffer + i;
> +
> +			/* A zero length zone means no more zones in this response */
> +			if (!zone->len)
> +				break;
> +
> +			ret = cb(zone, i, data);
> +			if (ret)
> +				goto out;
> +
> +			done_zones++;
> +			sector += zone_size_sectors;
> +
> +		}
> +	}
> +
> +	ret = done_zones;
> +
> +out:
> +	kvfree(buffer);
> +	return ret;
> +}
> +
> +#else
> +
> +#define ublk_report_zones (NULL)
> +
> +static int ublk_dev_param_zoned_validate(const struct ublk_device *ub)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +static int ublk_dev_param_zoned_apply(struct ublk_device *ub)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +static int ublk_revalidate_disk_zones(struct ublk_device *ub)
> +{
> +	return 0;
> +}
> +
> +#endif
> +
>  static inline void __ublk_complete_rq(struct request *req);
>  static void ublk_complete_rq(struct kref *ref);
>  
> @@ -232,7 +434,7 @@ static inline unsigned ublk_pos_to_tag(loff_t pos)
>  		UBLK_TAG_BITS_MASK;
>  }
>  
> -static void ublk_dev_param_basic_apply(struct ublk_device *ub)
> +static int ublk_dev_param_basic_apply(struct ublk_device *ub)
>  {
>  	struct request_queue *q = ub->ub_disk->queue;
>  	const struct ublk_param_basic *p = &ub->params.basic;
> @@ -257,6 +459,8 @@ static void ublk_dev_param_basic_apply(struct ublk_device *ub)
>  		set_disk_ro(ub->ub_disk, true);
>  
>  	set_capacity(ub->ub_disk, p->dev_sectors);
> +
> +	return 0;
>  }
>  
>  static void ublk_dev_param_discard_apply(struct ublk_device *ub)
> @@ -286,6 +490,9 @@ static int ublk_validate_params(const struct ublk_device *ub)
>  
>  		if (p->max_sectors > (ub->dev_info.max_io_buf_bytes >> 9))
>  			return -EINVAL;
> +
> +		if (ublk_dev_is_zoned(ub) && !p->chunk_sectors)
> +			return -EINVAL;
>  	} else
>  		return -EINVAL;
>  
> @@ -304,19 +511,31 @@ static int ublk_validate_params(const struct ublk_device *ub)
>  	if (ub->params.types & UBLK_PARAM_TYPE_DEVT)
>  		return -EINVAL;
>  
> +	if (ub->params.types & UBLK_PARAM_TYPE_ZONED)
> +		return ublk_dev_param_zoned_validate(ub);
> +	else if (ublk_dev_is_zoned(ub))
> +		return -EINVAL;
> +
>  	return 0;
>  }
>  
>  static int ublk_apply_params(struct ublk_device *ub)
>  {
> +	int ret;
> +
>  	if (!(ub->params.types & UBLK_PARAM_TYPE_BASIC))
>  		return -EINVAL;
>  
> -	ublk_dev_param_basic_apply(ub);
> +	ret = ublk_dev_param_basic_apply(ub);
> +	if (ret)
> +		return ret;
>  
>  	if (ub->params.types & UBLK_PARAM_TYPE_DISCARD)
>  		ublk_dev_param_discard_apply(ub);
>  
> +	if (ub->params.types & UBLK_PARAM_TYPE_ZONED)
> +		return ublk_dev_param_zoned_apply(ub);
> +
>  	return 0;
>  }
>  
> @@ -487,6 +706,7 @@ static const struct block_device_operations ub_fops = {
>  	.owner =	THIS_MODULE,
>  	.open =		ublk_open,
>  	.free_disk =	ublk_free_disk,
> +	.report_zones =	ublk_report_zones,
>  };
>  
>  #define UBLK_MAX_PIN_PAGES	32
> @@ -601,7 +821,8 @@ static inline bool ublk_need_map_req(const struct request *req)
>  
>  static inline bool ublk_need_unmap_req(const struct request *req)
>  {
> -	return ublk_rq_has_data(req) && req_op(req) == REQ_OP_READ;
> +	return ublk_rq_has_data(req) &&
> +	       (req_op(req) == REQ_OP_READ || req_op(req) == REQ_OP_DRV_IN);
>  }
>  
>  static int ublk_map_io(const struct ublk_queue *ubq, const struct request *req,
> @@ -685,8 +906,14 @@ static blk_status_t ublk_setup_iod(struct ublk_queue *ubq, struct request *req)
>  {
>  	struct ublksrv_io_desc *iod = ublk_get_iod(ubq, req->tag);
>  	struct ublk_io *io = &ubq->ios[req->tag];
> +	struct ublk_rq_data *pdu = blk_mq_rq_to_pdu(req);
> +	enum req_op op = req_op(req);
>  	u32 ublk_op;
>  
> +	if (!ublk_queue_is_zoned(ubq) &&
> +	    (op_is_zone_mgmt(op) || op == REQ_OP_ZONE_APPEND))
> +		return -EIO;
> +
>  	switch (req_op(req)) {
>  	case REQ_OP_READ:
>  		ublk_op = UBLK_IO_OP_READ;
> @@ -703,6 +930,37 @@ static blk_status_t ublk_setup_iod(struct ublk_queue *ubq, struct request *req)
>  	case REQ_OP_WRITE_ZEROES:
>  		ublk_op = UBLK_IO_OP_WRITE_ZEROES;
>  		break;
> +	case REQ_OP_ZONE_OPEN:
> +		ublk_op = UBLK_IO_OP_ZONE_OPEN;
> +		break;
> +	case REQ_OP_ZONE_CLOSE:
> +		ublk_op = UBLK_IO_OP_ZONE_CLOSE;
> +		break;
> +	case REQ_OP_ZONE_FINISH:
> +		ublk_op = UBLK_IO_OP_ZONE_FINISH;
> +		break;
> +	case REQ_OP_ZONE_RESET:
> +		ublk_op = UBLK_IO_OP_ZONE_RESET;
> +		break;
> +	case REQ_OP_DRV_IN:
> +		ublk_op = pdu->operation;
> +		switch (ublk_op) {
> +		case UBLK_IO_OP_REPORT_ZONES:
> +			iod->op_flags = ublk_op | ublk_req_build_flags(req);
> +			iod->nr_sectors = pdu->nr_sectors;
> +			iod->start_sector = pdu->sector;
> +			return BLK_STS_OK;
> +		default:
> +			return BLK_STS_IOERR;
> +		}
> +	case REQ_OP_ZONE_APPEND:
> +		ublk_op = UBLK_IO_OP_ZONE_APPEND;
> +		io->flags |= UBLK_IO_FLAG_ZONE_APPEND;
> +		break;
> +	case REQ_OP_ZONE_RESET_ALL:
> +	case REQ_OP_DRV_OUT:
> +		/* We do not support reset_all and drv_out */
> +		return BLK_STS_NOTSUPP;

I'd suggest to move all zoned handling & the above check into one helper,
such as:

	default:
		if (ublk_queue_is_zoned())
			return ublk_zoned_setup_iod();

Then zoned check can be avoided for other generic OPs, and zoned patch
conflict could be avoided usually.

Anyway, this version looks much better, and I think we are close to
go.

Thanks,
Ming

Re: [PATCH v8 2/2] ublk: enable zoned storage support

[Andreas Hindborg (Samsung)]

Ming Lei <ming.lei@redhat.com> writes:

> On Tue, Jul 11, 2023 at 09:23:53AM +0200, Andreas Hindborg wrote:
>> From: Andreas Hindborg <a.hindborg@samsung.com>
>> 
>> Add zoned storage support to ublk: report_zones and operations:
>>  - REQ_OP_ZONE_OPEN
>>  - REQ_OP_ZONE_CLOSE
>>  - REQ_OP_ZONE_FINISH
>>  - REQ_OP_ZONE_RESET
>>  - REQ_OP_ZONE_APPEND
>> 
>> The zone append feature uses the `addr` field of `struct ublksrv_io_cmd` to
>> communicate ALBA back to the kernel. Therefore ublk must be used with the
>> user copy feature (UBLK_F_USER_COPY) for zoned storage support to be
>> available. Without this feature, ublk will not allow zoned storage support.
>
> Without one userspace implementation, it is hard to verify the kernel
> change, so I write one zoned target example based on libublk-rs by
> taking one day.
>
> https://github.com/ming1/libublk-rs.git [1]
>
> It is one zoned-ramdisk example, and should be easy to
> add persistence zoned. All zoned commands are covered, except for
> REQ_OP_ZONE_RESET_ALL.
>
> How to create ublk-zoned:
>
> 	cargo run --example zoned -- add -1 1024   #1024MB
>
> So far it passes all blktests/zbd tests for external zoned device.
>
> 'mkfs.btrfs -O zoned' & mount & git clone linux_kernel in this btrfs
> works.
>
> So this patchset gets verified now, so far so good.

Thanks, that is really awesome! I have been testing with a patched
version of ubdsrv. It's nice to get some more test coverage options.

>
> [1] not publish to crates.io yet, still need some cleanup
>
>> 
>> Signed-off-by: Andreas Hindborg <a.hindborg@samsung.com>
>> ---
>>  drivers/block/ublk_drv.c      | 314 ++++++++++++++++++++++++++++++++--
>>  include/uapi/linux/ublk_cmd.h |  36 +++-
>>  2 files changed, 331 insertions(+), 19 deletions(-)
>> 
>> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
>> index 8d271901efac..a57be961b708 100644
>> --- a/drivers/block/ublk_drv.c
>> +++ b/drivers/block/ublk_drv.c
>> @@ -56,16 +56,21 @@
>>  		| UBLK_F_USER_RECOVERY_REISSUE \
>>  		| UBLK_F_UNPRIVILEGED_DEV \
>>  		| UBLK_F_CMD_IOCTL_ENCODE \
>> -		| UBLK_F_USER_COPY)
>> +		| UBLK_F_USER_COPY \
>> +		| UBLK_F_ZONED)
>>  
>>  /* All UBLK_PARAM_TYPE_* should be included here */
>> -#define UBLK_PARAM_TYPE_ALL (UBLK_PARAM_TYPE_BASIC | \
>> -		UBLK_PARAM_TYPE_DISCARD | UBLK_PARAM_TYPE_DEVT)
>> +#define UBLK_PARAM_TYPE_ALL                                \
>> +	(UBLK_PARAM_TYPE_BASIC | UBLK_PARAM_TYPE_DISCARD | \
>> +	 UBLK_PARAM_TYPE_DEVT | UBLK_PARAM_TYPE_ZONED)
>>  
>>  struct ublk_rq_data {
>>  	struct llist_node node;
>>  
>>  	struct kref ref;
>> +	__u64 sector;
>> +	__u32 operation;
>> +	__u32 nr_sectors;
>>  };
>>  
>>  struct ublk_uring_cmd_pdu {
>> @@ -110,6 +115,11 @@ struct ublk_uring_cmd_pdu {
>>   */
>>  #define UBLK_IO_FLAG_NEED_GET_DATA 0x08
>>  
>> +/*
>> + * Set when IO is Zone Append
>> + */
>> +#define UBLK_IO_FLAG_ZONE_APPEND 0x10
>> +
>>  struct ublk_io {
>>  	/* userspace buffer address from io cmd */
>>  	__u64	addr;
>> @@ -190,6 +200,198 @@ static inline bool ublk_dev_is_user_copy(const struct ublk_device *ub)
>>  	return ub->dev_info.flags & UBLK_F_USER_COPY;
>>  }
>>  
>> +static inline bool ublk_dev_is_zoned(const struct ublk_device *ub)
>> +{
>> +	return ub->dev_info.flags & UBLK_F_ZONED;
>> +}
>> +
>> +static inline bool ublk_queue_is_zoned(struct ublk_queue *ubq)
>> +{
>> +	return ubq->flags & UBLK_F_ZONED;
>> +}
>> +
>> +#ifdef CONFIG_BLK_DEV_ZONED
>> +
>> +static int ublk_get_nr_zones(const struct ublk_device *ub)
>> +{
>> +	const struct ublk_param_basic *p = &ub->params.basic;
>> +
>> +	/* Zone size is a power of 2 */
>> +	return p->dev_sectors >> ilog2(p->chunk_sectors);
>> +}
>> +
>> +static int ublk_revalidate_disk_zones(struct ublk_device *ub)
>> +{
>> +	return blk_revalidate_disk_zones(ub->ub_disk, NULL);
>> +}
>> +
>> +static int ublk_dev_param_zoned_validate(const struct ublk_device *ub)
>> +{
>> +	const struct ublk_param_zoned *p = &ub->params.zoned;
>> +	int nr_zones;
>> +
>> +	if (!ublk_dev_is_zoned(ub))
>> +		return -EINVAL;
>> +
>> +	if (!p->max_zone_append_sectors)
>> +		return -EINVAL;
>> +
>> +	nr_zones = ublk_get_nr_zones(ub);
>> +
>> +	if (p->max_active_zones > nr_zones)
>> +		return -EINVAL;
>> +
>> +	if (p->max_open_zones > nr_zones)
>> +		return -EINVAL;
>> +
>> +	return 0;
>> +}
>> +
>> +static int ublk_dev_param_zoned_apply(struct ublk_device *ub)
>> +{
>> +	const struct ublk_param_zoned *p = &ub->params.zoned;
>> +
>> +	disk_set_zoned(ub->ub_disk, BLK_ZONED_HM);
>> +	blk_queue_required_elevator_features(ub->ub_disk->queue,
>> +					     ELEVATOR_F_ZBD_SEQ_WRITE);
>> +	disk_set_max_active_zones(ub->ub_disk, p->max_active_zones);
>> +	disk_set_max_open_zones(ub->ub_disk, p->max_open_zones);
>> +	blk_queue_max_zone_append_sectors(ub->ub_disk->queue, p->max_zone_append_sectors);
>> +
>> +	ub->ub_disk->nr_zones = ublk_get_nr_zones(ub);
>> +
>> +	return 0;
>> +}
>> +
>> +/* Based on virtblk_alloc_report_buffer */
>> +static void *ublk_alloc_report_buffer(struct ublk_device *ublk,
>> +				      unsigned int nr_zones, size_t *buflen)
>> +{
>> +	struct request_queue *q = ublk->ub_disk->queue;
>> +	size_t bufsize;
>> +	void *buf;
>> +
>> +	nr_zones = min_t(unsigned int, nr_zones,
>> +			 ublk->ub_disk->nr_zones);
>> +
>> +	bufsize = nr_zones * sizeof(struct blk_zone);
>> +	bufsize =
>> +		min_t(size_t, bufsize, queue_max_hw_sectors(q) << SECTOR_SHIFT);
>> +	bufsize = min_t(size_t, bufsize, queue_max_segments(q) << PAGE_SHIFT);
>
> 'bufsize' shouldn't related with queue_max_segments() given we don't
> enable segment limit yet.

Ok 👍

>
>> +
>> +	while (bufsize >= sizeof(struct blk_zone)) {
>> +		buf = __vmalloc(bufsize, GFP_KERNEL | __GFP_NORETRY);
>> +		if (buf) {
>> +			*buflen = bufsize;
>> +			return buf;
>> +		}
>> +		bufsize >>= 1;
>> +	}
>> +
>> +	*buflen = 0;
>> +	return NULL;
>> +}
>> +
>> +static int ublk_report_zones(struct gendisk *disk, sector_t sector,
>> +		      unsigned int nr_zones, report_zones_cb cb, void *data)
>> +{
>> +	struct ublk_device *ub = disk->private_data;
>> +	unsigned int zone_size_sectors = disk->queue->limits.chunk_sectors;
>> +	unsigned int first_zone = sector >> ilog2(zone_size_sectors);
>> +	unsigned int done_zones = 0;
>> +	unsigned int max_zones_per_request;
>> +	int ret;
>> +	struct blk_zone *buffer;
>> +	size_t buffer_length;
>> +
>> +	nr_zones = min_t(unsigned int, ub->ub_disk->nr_zones - first_zone,
>> +			 nr_zones);
>> +
>> +	buffer = ublk_alloc_report_buffer(ub, nr_zones, &buffer_length);
>> +	if (!buffer)
>> +		return -ENOMEM;
>> +
>> +	max_zones_per_request = buffer_length / sizeof(struct blk_zone);
>> +
>> +	while (done_zones < nr_zones) {
>> +		unsigned int remaining_zones = nr_zones - done_zones;
>> +		unsigned int zones_in_request =
>> +			min_t(unsigned int, remaining_zones, max_zones_per_request);
>> +		struct request *req;
>> +		struct ublk_rq_data *pdu;
>> +		blk_status_t status;
>> +
>> +		memset(buffer, 0, buffer_length);
>> +
>> +		req = blk_mq_alloc_request(disk->queue, REQ_OP_DRV_IN, 0);
>> +		if (IS_ERR(req)) {
>> +			ret = PTR_ERR(req);
>> +			goto out;
>> +		}
>> +
>> +		pdu = blk_mq_rq_to_pdu(req);
>> +		pdu->operation = UBLK_IO_OP_REPORT_ZONES;
>> +		pdu->sector = sector;
>> +		pdu->nr_sectors = remaining_zones * zone_size_sectors;
>
> pdu->nr_sectors will be set to ublksrv_io_desc->nr_sectors as part of
> UAPI, I feel it is hard to understand to pass 'remaining_zones * zone_size_sectors',
> probably it is fine to re-define as buffer size or requested
> nr_blk_zone, or other ideas?

This is the only place `pdu->nr_sectors` is assigned. We copy the value
to `iod->nr_sectors` when we process the request. So I think that part
is OK.

However, it should be set to `zones_in_request`, not `remaining_zones`.
Otherwise user space might try to write too much to the buffer and get
confused when the write fails.

>
>> +
>> +		ret = blk_rq_map_kern(disk->queue, req, buffer, buffer_length,
>> +					GFP_KERNEL);
>> +		if (ret) {
>> +			blk_mq_free_request(req);
>> +			goto out;
>> +		}
>> +
>> +		status = blk_execute_rq(req, 0);
>> +		ret = blk_status_to_errno(status);
>> +		blk_mq_free_request(req);
>> +		if (ret)
>> +			goto out;
>> +
>> +		for (unsigned int i = 0; i < zones_in_request; i++) {
>> +			struct blk_zone *zone = buffer + i;
>> +
>> +			/* A zero length zone means no more zones in this response */
>> +			if (!zone->len)
>> +				break;
>> +
>> +			ret = cb(zone, i, data);
>> +			if (ret)
>> +				goto out;
>> +
>> +			done_zones++;
>> +			sector += zone_size_sectors;
>> +
>> +		}
>> +	}
>> +
>> +	ret = done_zones;
>> +
>> +out:
>> +	kvfree(buffer);
>> +	return ret;
>> +}
>> +
>> +#else
>> +
>> +#define ublk_report_zones (NULL)
>> +
>> +static int ublk_dev_param_zoned_validate(const struct ublk_device *ub)
>> +{
>> +	return -EOPNOTSUPP;
>> +}
>> +
>> +static int ublk_dev_param_zoned_apply(struct ublk_device *ub)
>> +{
>> +	return -EOPNOTSUPP;
>> +}
>> +
>> +static int ublk_revalidate_disk_zones(struct ublk_device *ub)
>> +{
>> +	return 0;
>> +}
>> +
>> +#endif
>> +
>>  static inline void __ublk_complete_rq(struct request *req);
>>  static void ublk_complete_rq(struct kref *ref);
>>  
>> @@ -232,7 +434,7 @@ static inline unsigned ublk_pos_to_tag(loff_t pos)
>>  		UBLK_TAG_BITS_MASK;
>>  }
>>  
>> -static void ublk_dev_param_basic_apply(struct ublk_device *ub)
>> +static int ublk_dev_param_basic_apply(struct ublk_device *ub)
>>  {
>>  	struct request_queue *q = ub->ub_disk->queue;
>>  	const struct ublk_param_basic *p = &ub->params.basic;
>> @@ -257,6 +459,8 @@ static void ublk_dev_param_basic_apply(struct ublk_device *ub)
>>  		set_disk_ro(ub->ub_disk, true);
>>  
>>  	set_capacity(ub->ub_disk, p->dev_sectors);
>> +
>> +	return 0;
>>  }
>>  
>>  static void ublk_dev_param_discard_apply(struct ublk_device *ub)
>> @@ -286,6 +490,9 @@ static int ublk_validate_params(const struct ublk_device *ub)
>>  
>>  		if (p->max_sectors > (ub->dev_info.max_io_buf_bytes >> 9))
>>  			return -EINVAL;
>> +
>> +		if (ublk_dev_is_zoned(ub) && !p->chunk_sectors)
>> +			return -EINVAL;
>>  	} else
>>  		return -EINVAL;
>>  
>> @@ -304,19 +511,31 @@ static int ublk_validate_params(const struct ublk_device *ub)
>>  	if (ub->params.types & UBLK_PARAM_TYPE_DEVT)
>>  		return -EINVAL;
>>  
>> +	if (ub->params.types & UBLK_PARAM_TYPE_ZONED)
>> +		return ublk_dev_param_zoned_validate(ub);
>> +	else if (ublk_dev_is_zoned(ub))
>> +		return -EINVAL;
>> +
>>  	return 0;
>>  }
>>  
>>  static int ublk_apply_params(struct ublk_device *ub)
>>  {
>> +	int ret;
>> +
>>  	if (!(ub->params.types & UBLK_PARAM_TYPE_BASIC))
>>  		return -EINVAL;
>>  
>> -	ublk_dev_param_basic_apply(ub);
>> +	ret = ublk_dev_param_basic_apply(ub);
>> +	if (ret)
>> +		return ret;
>>  
>>  	if (ub->params.types & UBLK_PARAM_TYPE_DISCARD)
>>  		ublk_dev_param_discard_apply(ub);
>>  
>> +	if (ub->params.types & UBLK_PARAM_TYPE_ZONED)
>> +		return ublk_dev_param_zoned_apply(ub);
>> +
>>  	return 0;
>>  }
>>  
>> @@ -487,6 +706,7 @@ static const struct block_device_operations ub_fops = {
>>  	.owner =	THIS_MODULE,
>>  	.open =		ublk_open,
>>  	.free_disk =	ublk_free_disk,
>> +	.report_zones =	ublk_report_zones,
>>  };
>>  
>>  #define UBLK_MAX_PIN_PAGES	32
>> @@ -601,7 +821,8 @@ static inline bool ublk_need_map_req(const struct request *req)
>>  
>>  static inline bool ublk_need_unmap_req(const struct request *req)
>>  {
>> -	return ublk_rq_has_data(req) && req_op(req) == REQ_OP_READ;
>> +	return ublk_rq_has_data(req) &&
>> +	       (req_op(req) == REQ_OP_READ || req_op(req) == REQ_OP_DRV_IN);
>>  }
>>  
>>  static int ublk_map_io(const struct ublk_queue *ubq, const struct request *req,
>> @@ -685,8 +906,14 @@ static blk_status_t ublk_setup_iod(struct ublk_queue *ubq, struct request *req)
>>  {
>>  	struct ublksrv_io_desc *iod = ublk_get_iod(ubq, req->tag);
>>  	struct ublk_io *io = &ubq->ios[req->tag];
>> +	struct ublk_rq_data *pdu = blk_mq_rq_to_pdu(req);
>> +	enum req_op op = req_op(req);
>>  	u32 ublk_op;
>>  
>> +	if (!ublk_queue_is_zoned(ubq) &&
>> +	    (op_is_zone_mgmt(op) || op == REQ_OP_ZONE_APPEND))
>> +		return -EIO;
>> +
>>  	switch (req_op(req)) {
>>  	case REQ_OP_READ:
>>  		ublk_op = UBLK_IO_OP_READ;
>> @@ -703,6 +930,37 @@ static blk_status_t ublk_setup_iod(struct ublk_queue *ubq, struct request *req)
>>  	case REQ_OP_WRITE_ZEROES:
>>  		ublk_op = UBLK_IO_OP_WRITE_ZEROES;
>>  		break;
>> +	case REQ_OP_ZONE_OPEN:
>> +		ublk_op = UBLK_IO_OP_ZONE_OPEN;
>> +		break;
>> +	case REQ_OP_ZONE_CLOSE:
>> +		ublk_op = UBLK_IO_OP_ZONE_CLOSE;
>> +		break;
>> +	case REQ_OP_ZONE_FINISH:
>> +		ublk_op = UBLK_IO_OP_ZONE_FINISH;
>> +		break;
>> +	case REQ_OP_ZONE_RESET:
>> +		ublk_op = UBLK_IO_OP_ZONE_RESET;
>> +		break;
>> +	case REQ_OP_DRV_IN:
>> +		ublk_op = pdu->operation;
>> +		switch (ublk_op) {
>> +		case UBLK_IO_OP_REPORT_ZONES:
>> +			iod->op_flags = ublk_op | ublk_req_build_flags(req);
>> +			iod->nr_sectors = pdu->nr_sectors;
>> +			iod->start_sector = pdu->sector;
>> +			return BLK_STS_OK;
>> +		default:
>> +			return BLK_STS_IOERR;
>> +		}
>> +	case REQ_OP_ZONE_APPEND:
>> +		ublk_op = UBLK_IO_OP_ZONE_APPEND;
>> +		io->flags |= UBLK_IO_FLAG_ZONE_APPEND;
>> +		break;
>> +	case REQ_OP_ZONE_RESET_ALL:
>> +	case REQ_OP_DRV_OUT:
>> +		/* We do not support reset_all and drv_out */
>> +		return BLK_STS_NOTSUPP;
>
> I'd suggest to move all zoned handling & the above check into one helper,
> such as:
>
> 	default:
> 		if (ublk_queue_is_zoned())
> 			return ublk_zoned_setup_iod();
>
> Then zoned check can be avoided for other generic OPs, and zoned patch
> conflict could be avoided usually.

Alright 👍

Best regards,
Andreas