Re: [PATCH v3] block: ublk: enable zoned storage support
From: Niklas Cassel
Date: Fri Mar 17 2023 - 05:50:00 EST
On Thu, Mar 16, 2023 at 03:55:38PM +0100, Andreas Hindborg wrote:
> From: Andreas Hindborg <a.hindborg@xxxxxxxxxxx>
Hello Andreas,
I think that this patch is starting to look very nice!
>
> 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
>
> This allows implementation of zoned storage devices in user space. An
> example user space implementation based on ubdsrv is available [1].
>
> [1] https://github.com/metaspace/ubdsrv/commit/2c60b9ffdfb7cb44c5cce0272bb52229ea6c95d4
>
> Signed-off-by: Andreas Hindborg <a.hindborg@xxxxxxxxxxx>
> ---
>
> Changes since v2:
> - Allow reporting of multiple zones in a single request
> - Move zoned functions to separate translation unit
> - Do not overload REQ_OP_DRV_IN for zone report
> - Reserve space in ublk_param_zoned for future parameters
> - Do not overload (struct request).__sector and .__data_len
> - Remove unnecessary conditional compilation
> - Remove goto statements in ublk_report_zones
>
> v1: https://lore.kernel.org/linux-block/20230224125950.214779-1-nmi@xxxxxxxxxxxx/
> v2: https://lore.kernel.org/all/20230224200502.391570-1-nmi@xxxxxxxxxxxx/
>
> drivers/block/Kconfig | 4 +
> drivers/block/Makefile | 1 +
> drivers/block/ublk_drv-zoned.c | 142 +++++++++++++++++++++++++++++++++
> drivers/block/ublk_drv.c | 113 ++++++++++++++------------
> drivers/block/ublk_drv.h | 69 ++++++++++++++++
> include/uapi/linux/ublk_cmd.h | 37 +++++++--
> 6 files changed, 308 insertions(+), 58 deletions(-)
> create mode 100644 drivers/block/ublk_drv-zoned.c
> create mode 100644 drivers/block/ublk_drv.h
>
> diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
> index f79f20430ef7..311e401eece5 100644
> --- a/drivers/block/Kconfig
> +++ b/drivers/block/Kconfig
> @@ -385,6 +385,10 @@ config BLK_DEV_UBLK
> can handle batch more effectively, but task_work_add() isn't exported
> for module, so ublk has to be built to kernel.
>
> +config BLK_DEV_UBLK_ZONED
> + def_bool y
> + depends on BLK_DEV_UBLK && BLK_DEV_ZONED
> +
> source "drivers/block/rnbd/Kconfig"
>
> endif # BLK_DEV
> diff --git a/drivers/block/Makefile b/drivers/block/Makefile
> index 101612cba303..0de9379ba9df 100644
> --- a/drivers/block/Makefile
> +++ b/drivers/block/Makefile
> @@ -38,5 +38,6 @@ obj-$(CONFIG_BLK_DEV_RNBD) += rnbd/
> obj-$(CONFIG_BLK_DEV_NULL_BLK) += null_blk/
>
> obj-$(CONFIG_BLK_DEV_UBLK) += ublk_drv.o
> +obj-$(CONFIG_BLK_DEV_UBLK_ZONED) += ublk_drv-zoned.o
>
> swim_mod-y := swim.o swim_asm.o
> diff --git a/drivers/block/ublk_drv-zoned.c b/drivers/block/ublk_drv-zoned.c
> new file mode 100644
> index 000000000000..fbcbe1bbf653
> --- /dev/null
> +++ b/drivers/block/ublk_drv-zoned.c
> @@ -0,0 +1,142 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright 2023 Andreas Hindborg <a.hindborg@xxxxxxxxxxx>
> + */
> +#include <linux/blkzoned.h>
> +#include <linux/ublk_cmd.h>
> +#include "ublk_drv.h"
> +
> +void ublk_set_nr_zones(struct ublk_device *ub)
> +{
> + const struct ublk_param_basic *p = &ub->params.basic;
> +
> + if (ub->dev_info.flags & UBLK_F_ZONED && p->chunk_sectors)
> + ub->ub_disk->nr_zones = p->dev_sectors / p->chunk_sectors;
> +}
> +
> +void ublk_dev_param_zoned_apply(struct ublk_device *ub)
> +{
> + const struct ublk_param_zoned *p = &ub->params.zoned;
> +
> + if (ub->dev_info.flags & UBLK_F_ZONED) {
> + disk_set_max_active_zones(ub->ub_disk, p->max_active_zones);
> + disk_set_max_open_zones(ub->ub_disk, p->max_open_zones);
> + }
> +}
> +
> +int ublk_revalidate_disk_zones(struct gendisk *disk)
> +{
> + return blk_revalidate_disk_zones(disk, NULL);
> +}
> +
> +// Based on virtblk_alloc_report_buffer
Change from C++ style to C style comment.
> +static void *ublk_alloc_report_buffer(struct ublk_device *ublk,
> + unsigned int nr_zones,
> + unsigned int zone_sectors, size_t *buflen)
> +{
> + struct request_queue *q = ublk->ub_disk->queue;
> + size_t bufsize;
> + void *buf;
> +
> + nr_zones = min_t(unsigned int, nr_zones,
> + get_capacity(ublk->ub_disk) >> ilog2(zone_sectors));
> +
> + 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;
> + }
> +
> + bufsize = 0;
> + return NULL;
> +}
> +
> +int ublk_report_zones(struct gendisk *disk, sector_t sector,
> + unsigned int nr_zones, report_zones_cb cb, void *data)
> +{
> + unsigned int done_zones = 0;
> + 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);
> + struct blk_zone *buffer;
> + size_t buffer_length;
> + unsigned int max_zones_per_request;
Nit: I would sort the variables differently.
Perhaps:
> + 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;
> + struct blk_zone *buffer;
> + size_t buffer_length;
> +
> + if (!(ub->dev_info.flags & UBLK_F_ZONED))
> + return -EOPNOTSUPP;
> +
> + nr_zones = min_t(unsigned int, ub->ub_disk->nr_zones - first_zone,
> + nr_zones);
> +
> + buffer = ublk_alloc_report_buffer(ub, nr_zones, zone_size_sectors,
> + &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);
> + int err = 0;
> + 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))
> + return PTR_ERR(req);
> +
> + 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;
> +
> + err = blk_rq_map_kern(disk->queue, req, buffer, buffer_length,
> + GFP_KERNEL);
> + if (err) {
> + blk_mq_free_request(req);
> + kvfree(buffer);
> + return err;
> + }
> +
> + status = blk_execute_rq(req, 0);
> + err = blk_status_to_errno(status);
> + blk_mq_free_request(req);
> + if (err) {
> + kvfree(buffer);
> + return err;
> + }
> +
> + for (unsigned int i = 0; i < zones_in_request; i++) {
> + struct blk_zone *zone = buffer + i;
> +
> + err = cb(zone, i, data);
> + if (err)
> + return err;
> +
> + done_zones++;
> + sector += zone_size_sectors;
> +
> + /* A zero length zone means don't ask for more zones */
> + if (!zone->len) {
> + kvfree(buffer);
> + return done_zones;
> + }
> + }
> + }
> +
> + kvfree(buffer);
> + return done_zones;
> +}
> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
> index d1d1c8d606c8..69a3e7dedfc0 100644
> --- a/drivers/block/ublk_drv.c
> +++ b/drivers/block/ublk_drv.c
> @@ -44,6 +44,7 @@
> #include <linux/task_work.h>
> #include <linux/namei.h>
> #include <uapi/linux/ublk_cmd.h>
> +#include "ublk_drv.h"
>
> #define UBLK_MINORS (1U << MINORBITS)
>
> @@ -53,16 +54,13 @@
> | UBLK_F_NEED_GET_DATA \
> | UBLK_F_USER_RECOVERY \
> | UBLK_F_USER_RECOVERY_REISSUE \
> - | UBLK_F_UNPRIVILEGED_DEV)
> + | UBLK_F_UNPRIVILEGED_DEV \
> + | 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)
> -
> -struct ublk_rq_data {
> - struct llist_node node;
> - struct callback_head work;
> -};
> +#define UBLK_PARAM_TYPE_ALL \
> + (UBLK_PARAM_TYPE_BASIC | UBLK_PARAM_TYPE_DISCARD | \
> + UBLK_PARAM_TYPE_DEVT | UBLK_PARAM_TYPE_ZONED)
>
> struct ublk_uring_cmd_pdu {
> struct ublk_queue *ubq;
> @@ -135,45 +133,6 @@ struct ublk_queue {
>
> #define UBLK_DAEMON_MONITOR_PERIOD (5 * HZ)
>
> -struct ublk_device {
> - struct gendisk *ub_disk;
> -
> - char *__queues;
> -
> - unsigned int queue_size;
> - struct ublksrv_ctrl_dev_info dev_info;
> -
> - struct blk_mq_tag_set tag_set;
> -
> - struct cdev cdev;
> - struct device cdev_dev;
> -
> -#define UB_STATE_OPEN 0
> -#define UB_STATE_USED 1
> -#define UB_STATE_DELETED 2
> - unsigned long state;
> - int ub_number;
> -
> - struct mutex mutex;
> -
> - spinlock_t mm_lock;
> - struct mm_struct *mm;
> -
> - struct ublk_params params;
> -
> - struct completion completion;
> - unsigned int nr_queues_ready;
> - unsigned int nr_privileged_daemon;
> -
> - /*
> - * Our ubq->daemon may be killed without any notification, so
> - * monitor each queue's daemon periodically
> - */
> - struct delayed_work monitor_work;
> - struct work_struct quiesce_work;
> - struct work_struct stop_work;
> -};
> -
I think that this change should go into a patch 1/2 that is simply
create a driver internal header file and move appropriate code.
> /* header of ublk_params */
> struct ublk_params_header {
> __u32 len;
> @@ -225,6 +184,9 @@ 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);
> +
> + if (IS_ENABLED(CONFIG_BLK_DEV_ZONED))
> + ublk_set_nr_zones(ub);
> }
>
> static void ublk_dev_param_discard_apply(struct ublk_device *ub)
> @@ -285,6 +247,9 @@ static int ublk_apply_params(struct ublk_device *ub)
> if (ub->params.types & UBLK_PARAM_TYPE_DISCARD)
> ublk_dev_param_discard_apply(ub);
>
> + if (IS_ENABLED(CONFIG_BLK_DEV_ZONED) && (ub->params.types & UBLK_PARAM_TYPE_ZONED))
> + ublk_dev_param_zoned_apply(ub);
> +
> return 0;
> }
>
> @@ -420,9 +385,10 @@ static int ublk_open(struct block_device *bdev, fmode_t mode)
> }
>
> static const struct block_device_operations ub_fops = {
> - .owner = THIS_MODULE,
> - .open = ublk_open,
> - .free_disk = ublk_free_disk,
> + .owner = THIS_MODULE,
> + .open = ublk_open,
> + .free_disk = ublk_free_disk,
> + .report_zones = ublk_report_zones,
> };
>
> #define UBLK_MAX_PIN_PAGES 32
> @@ -558,7 +524,7 @@ static int ublk_unmap_io(const struct ublk_queue *ubq,
> {
> const unsigned int rq_bytes = blk_rq_bytes(req);
>
> - if (req_op(req) == REQ_OP_READ && ublk_rq_has_data(req)) {
> + if ((req_op(req) == REQ_OP_READ || req_op(req) == REQ_OP_DRV_IN) && ublk_rq_has_data(req)) {
> struct ublk_map_data data = {
> .ubq = ubq,
> .rq = req,
> @@ -607,6 +573,7 @@ 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);
> u32 ublk_op;
>
> switch (req_op(req)) {
> @@ -625,6 +592,35 @@ 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:
> + case REQ_OP_DRV_OUT:
> + 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;
> + iod->addr = io->addr;
> + return BLK_STS_OK;
> + default:
> + return BLK_STS_IOERR;
> + }
> + case REQ_OP_ZONE_APPEND:
> + case REQ_OP_ZONE_RESET_ALL:
> + /* We do not support zone append or reset_all yet */
> + fallthrough;
> default:
> return BLK_STS_IOERR;
> }
> @@ -671,7 +667,8 @@ static 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) {
> blk_mq_end_request(req, BLK_STS_OK);
> return;
> }
> @@ -1601,6 +1598,15 @@ static int ublk_ctrl_start_dev(struct ublk_device *ub, struct io_uring_cmd *cmd)
> if (ub->nr_privileged_daemon != ub->nr_queues_ready)
> set_bit(GD_SUPPRESS_PART_SCAN, &disk->state);
>
> + if (IS_ENABLED(CONFIG_BLK_DEV_ZONED) &&
> + ub->dev_info.flags & UBLK_F_ZONED) {
> + disk_set_zoned(disk, BLK_ZONED_HM);
> + blk_queue_required_elevator_features(disk->queue, ELEVATOR_F_ZBD_SEQ_WRITE);
> + ret = ublk_revalidate_disk_zones(disk);
> + if (ret)
> + goto out_put_disk;
> + }
> +
> get_device(&ub->cdev_dev);
> ret = add_disk(disk);
> if (ret) {
> @@ -1746,6 +1752,9 @@ static int ublk_ctrl_add_dev(struct io_uring_cmd *cmd)
> if (!IS_BUILTIN(CONFIG_BLK_DEV_UBLK))
> ub->dev_info.flags |= UBLK_F_URING_CMD_COMP_IN_TASK;
>
> + if (!IS_ENABLED(CONFIG_BLK_DEV_ZONED))
> + ub->dev_info.flags &= ~UBLK_F_ZONED;
> +
> /* We are not ready to support zero copy */
> ub->dev_info.flags &= ~UBLK_F_SUPPORT_ZERO_COPY;
>
> diff --git a/drivers/block/ublk_drv.h b/drivers/block/ublk_drv.h
> new file mode 100644
> index 000000000000..7b21235d7673
> --- /dev/null
> +++ b/drivers/block/ublk_drv.h
> @@ -0,0 +1,69 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +#ifndef _UBLK_DRV_H
> +#define _UBLK_DRV_H
> +
> +#include <uapi/linux/ublk_cmd.h>
> +#include <linux/blk-mq.h>
> +#include <linux/cdev.h>
> +
> +struct ublk_device {
> + struct gendisk *ub_disk;
> +
> + char *__queues;
> +
> + unsigned int queue_size;
> + struct ublksrv_ctrl_dev_info dev_info;
> +
> + struct blk_mq_tag_set tag_set;
> +
> + struct cdev cdev;
> + struct device cdev_dev;
> +
> +#define UB_STATE_OPEN 0
> +#define UB_STATE_USED 1
> +#define UB_STATE_DELETED 2
> + unsigned long state;
> + int ub_number;
> +
> + struct mutex mutex;
> +
> + spinlock_t mm_lock;
> + struct mm_struct *mm;
> +
> + struct ublk_params params;
> +
> + struct completion completion;
> + unsigned int nr_queues_ready;
> + unsigned int nr_privileged_daemon;
> +
> + /*
> + * Our ubq->daemon may be killed without any notification, so
> + * monitor each queue's daemon periodically
> + */
> + struct delayed_work monitor_work;
> + struct work_struct quiesce_work;
> + struct work_struct stop_work;
> +};
> +
> +struct ublk_rq_data {
> + struct llist_node node;
> + struct callback_head work;
> + enum ublk_op operation;
> + __u64 sector;
> + __u32 nr_sectors;
> +};
> +
> +void ublk_set_nr_zones(struct ublk_device *ub);
> +void ublk_dev_param_zoned_apply(struct ublk_device *ub);
> +int ublk_revalidate_disk_zones(struct gendisk *disk);
> +
> +#ifdef CONFIG_BLK_DEV_UBLK_ZONED
> +int ublk_report_zones(struct gendisk *disk, sector_t sector,
> + unsigned int nr_zones, report_zones_cb cb,
> + void *data);
> +#else
> +#define ublk_report_zones NULL
> +#endif
> +
> +#endif
> diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h
> index f6238ccc7800..a9c3e71b0756 100644
> --- a/include/uapi/linux/ublk_cmd.h
> +++ b/include/uapi/linux/ublk_cmd.h
> @@ -102,6 +102,11 @@
> */
> #define UBLK_F_UNPRIVILEGED_DEV (1UL << 5)
>
> +/*
> + * Enable zoned device support
> + */
> +#define UBLK_F_ZONED (1ULL << 6)
> +
> /* device state */
> #define UBLK_S_DEV_DEAD 0
> #define UBLK_S_DEV_LIVE 1
> @@ -155,12 +160,24 @@ struct ublksrv_ctrl_dev_info {
> __u64 reserved2;
> };
>
> -#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
> +enum ublk_op {
> + UBLK_IO_OP_READ = 0,
> + UBLK_IO_OP_WRITE = 1,
> + UBLK_IO_OP_FLUSH = 2,
> + UBLK_IO_OP_DISCARD = 3,
> + UBLK_IO_OP_WRITE_SAME = 4,
> + UBLK_IO_OP_WRITE_ZEROES = 5,
> + UBLK_IO_OP_ZONE_OPEN = 10,
> + UBLK_IO_OP_ZONE_CLOSE = 11,
> + UBLK_IO_OP_ZONE_FINISH = 12,
> + UBLK_IO_OP_ZONE_APPEND = 13,
> + UBLK_IO_OP_ZONE_RESET = 15,
> + __UBLK_IO_OP_DRV_IN_START = 32,
> + UBLK_IO_OP_REPORT_ZONES = __UBLK_IO_OP_DRV_IN_START,
> + __UBLK_IO_OP_DRV_IN_END = 96,
> + __UBLK_IO_OP_DRV_OUT_START = __UBLK_IO_OP_DRV_IN_END,
> + __UBLK_IO_OP_DRV_OUT_END = 160,
> +};
This also looks like a separate change.
I would put it into a patch 2/3.
Have a nice weekend!
Kind regards,
Niklas
>
> #define UBLK_IO_F_FAILFAST_DEV (1U << 8)
> #define UBLK_IO_F_FAILFAST_TRANSPORT (1U << 9)
> @@ -257,6 +274,12 @@ struct ublk_param_devt {
> __u32 disk_minor;
> };
>
> +struct ublk_param_zoned {
> + __u32 max_open_zones;
> + __u32 max_active_zones;
> + __u8 reserved[24];
> +};
> +
> struct ublk_params {
> /*
> * Total length of parameters, userspace has to set 'len' for both
> @@ -268,11 +291,13 @@ 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
>
> base-commit: eeac8ede17557680855031c6f305ece2378af326
> --
> 2.39.2
>