Niklas Cassel <Niklas.Cassel@xxxxxxx> writes: > On Fri, Feb 24, 2023 at 09:05:01PM +0100, Andreas Hindborg wrote: >> 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/14a2b708f74f70cfecb076d92e680dc718cc1f6d >> >> Signed-off-by: Andreas Hindborg <a.hindborg@xxxxxxxxxxx> >> --- >> Changes since v1: >> - Fixed conditional compilation bug >> - Refactored to collect conditional code additions together >> - Fixed style errors >> - Zero stack allocated value used for zone report >> >> Reported-by: Niklas Cassel <Niklas.Cassel@xxxxxxx> >> Reported-by: kernel test robot <lkp@xxxxxxxxx> >> Link: https://lore.kernel.org/oe-kbuild-all/202302250222.XOrw9j6z-lkp@xxxxxxxxx/ >> v1: https://lore.kernel.org/linux-block/20230224125950.214779-1-nmi@xxxxxxxxxxxx/ >> >> drivers/block/ublk_drv.c | 150 ++++++++++++++++++++++++++++++++-- >> include/uapi/linux/ublk_cmd.h | 18 ++++ >> 2 files changed, 162 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c >> index 6368b56eacf1..37e516903867 100644 >> --- a/drivers/block/ublk_drv.c >> +++ b/drivers/block/ublk_drv.c >> @@ -20,6 +20,7 @@ >> #include <linux/major.h> >> #include <linux/wait.h> >> #include <linux/blkdev.h> >> +#include <linux/blkzoned.h> >> #include <linux/init.h> >> #include <linux/swap.h> >> #include <linux/slab.h> >> @@ -51,10 +52,12 @@ >> | UBLK_F_URING_CMD_COMP_IN_TASK \ >> | UBLK_F_NEED_GET_DATA \ >> | UBLK_F_USER_RECOVERY \ >> - | UBLK_F_USER_RECOVERY_REISSUE) >> + | UBLK_F_USER_RECOVERY_REISSUE \ >> + | UBLK_F_ZONED) >> >> /* All UBLK_PARAM_TYPE_* should be included here */ >> -#define UBLK_PARAM_TYPE_ALL (UBLK_PARAM_TYPE_BASIC | UBLK_PARAM_TYPE_DISCARD) >> +#define UBLK_PARAM_TYPE_ALL (UBLK_PARAM_TYPE_BASIC | UBLK_PARAM_TYPE_DISCARD \ >> + | UBLK_PARAM_TYPE_ZONED) >> >> struct ublk_rq_data { >> struct llist_node node; >> @@ -187,6 +190,98 @@ static DEFINE_MUTEX(ublk_ctl_mutex); >> >> static struct miscdevice ublk_misc; >> >> +#ifdef CONFIG_BLK_DEV_ZONED >> +static 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; >> +} >> + >> +static 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); >> + } >> +} >> + >> +static int ublk_revalidate_disk_zones(struct gendisk *disk) >> +{ >> + return blk_revalidate_disk_zones(disk, 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; >> + unsigned int zone_size; >> + unsigned int first_zone; >> + int ret = 0; >> + >> + ub = disk->private_data; >> + >> + if (!(ub->dev_info.flags & UBLK_F_ZONED)) >> + return -EINVAL; >> + >> + zone_size = disk->queue->limits.chunk_sectors; >> + first_zone = sector >> ilog2(zone_size); >> + nr_zones = min(ub->ub_disk->nr_zones - first_zone, nr_zones); >> + >> + for (unsigned int i = 0; i < nr_zones; i++) { >> + struct request *req; >> + blk_status_t status; >> + struct blk_zone info = {0}; >> + >> + req = blk_mq_alloc_request(disk->queue, REQ_OP_DRV_IN, 0); >> + >> + if (IS_ERR(req)) { >> + ret = PTR_ERR(req); >> + goto out; >> + } >> + >> + req->__sector = sector; >> + >> + ret = blk_rq_map_kern(disk->queue, req, &info, sizeof(info), >> + GFP_KERNEL); >> + >> + if (ret) >> + goto out; >> + >> + status = blk_execute_rq(req, 0); >> + ret = blk_status_to_errno(status); >> + if (ret) >> + goto out; >> + >> + blk_mq_free_request(req); >> + >> + ret = cb(&info, i, data); >> + if (ret) >> + goto out; >> + >> + /* A zero length zone means don't ask for more zones */ >> + if (!info.len) { >> + nr_zones = i; >> + break; >> + } >> + >> + sector += zone_size; >> + } >> + ret = nr_zones; >> + >> + out: >> + return ret; >> +} >> +#else >> +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); > > These are declarations, shouldn't they be dummy definitions instead? I looked at how nvme host defines nvme_revalidate_zones() when I did this. The functions become undefined symbols but because the call sites are optimized out they go away. > > e.g. > static int ublk_revalidate_disk_zones(struct gendisk *disk) { return -EOPNOTSUPP; }; Not sure how this is better? > > > It would be nice if they could be avoided altogether. > > Looking how e.g. null-blk and btrfs has solved this: > https://github.com/torvalds/linux/blob/v6.2/fs/btrfs/Makefile#L39 > https://github.com/torvalds/linux/blob/v6.2/drivers/block/null_blk/Makefile#L11 > > They have put the zoned stuff in a separate C file that is only compiled > when CONFIG_BLK_DEV_ZONED is set. > > I'm not sure if a similar design is desired for ublk or not. > > However, if a similar design pattern was used, it could probably avoid > some of these unpleasant dummy definitions altogether. This is the same as I do here, except I put the declarations in the c file instead of a header. I did this for two reasons 1) there is no ublk header besides the uapi header (I would add a header just for this), 2) the declarations need only exist inside ublk_drv.c. For btrfs, null_blk, nvme, the declarations go in a header file and the functions in question do not have static linkage. I could move the function declarations out of the #else block, but then they would need to be declared static and that gives a compiler warning when the implementation is not present. BR Andreas
