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

From: Andreas Hindborg (Samsung)
Date: Fri Jul 14 2023 - 02:50:07 EST

Next message: syzbot: "Re: [syzbot] [usb?] memory leak in raw_open"
Previous message: Sam Ravnborg: "Re: [PATCH] floppy:ERROR: missing put_device; call of_find_device_by_node on line 589, but without a corresponding object release within this function. Add the put_device function before return to release memory"
In reply to: Ming Lei: "Re: [PATCH v8 2/2] ublk: enable zoned storage support"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

Ming Lei <ming.lei@xxxxxxxxxx> writes:

> On Tue, Jul 11, 2023 at 09:23:53AM +0200, Andreas Hindborg wrote:
>> From: Andreas Hindborg <a.hindborg@xxxxxxxxxxx>
>>
>> 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@xxxxxxxxxxx>
>> ---
>> 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

Next message: syzbot: "Re: [syzbot] [usb?] memory leak in raw_open"
Previous message: Sam Ravnborg: "Re: [PATCH] floppy:ERROR: missing put_device; call of_find_device_by_node on line 589, but without a corresponding object release within this function. Add the put_device function before return to release memory"
In reply to: Ming Lei: "Re: [PATCH v8 2/2] ublk: enable zoned storage support"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]