From abb864d380854b5427b6b070beb2ebc291ce4d1e Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Fri, 6 Jan 2023 12:17:09 +0800 Subject: [PATCH] ublk_drv: add device parameter UBLK_PARAM_TYPE_DEVT Userspace side only knows device ID, but the associated path of ublkc* and ublkb* could be changed by udev, and that depends on userspace's policy, so add parameter of UBLK_PARAM_TYPE_DEVT for retrieving major/minor of the ublkc* and ublkb*, then user may figure out major/minor of the ublk disks he/she owns. With major/minor, it is easy to find the device node path. Signed-off-by: Ming Lei Link: https://lore.kernel.org/r/20230106041711.914434-5-ming.lei@redhat.com Signed-off-by: Jens Axboe --- drivers/block/ublk_drv.c | 24 +++++++++++++++++++++++- include/uapi/linux/ublk_cmd.h | 13 +++++++++++++ 2 files changed, 36 insertions(+), 1 deletion(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index b015e46b59bb..75033304b900 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -54,7 +54,8 @@ | UBLK_F_USER_RECOVERY_REISSUE) /* 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_DEVT) struct ublk_rq_data { struct llist_node node; @@ -255,6 +256,10 @@ static int ublk_validate_params(const struct ublk_device *ub) return -EINVAL; } + /* dev_t is read-only */ + if (ub->params.types & UBLK_PARAM_TYPE_DEVT) + return -EINVAL; + return 0; } @@ -1777,6 +1782,22 @@ static int ublk_ctrl_get_dev_info(struct ublk_device *ub, return 0; } +/* TYPE_DEVT is readonly, so fill it up before returning to userspace */ +static void ublk_ctrl_fill_params_devt(struct ublk_device *ub) +{ + ub->params.devt.char_major = MAJOR(ub->cdev_dev.devt); + ub->params.devt.char_minor = MINOR(ub->cdev_dev.devt); + + if (ub->ub_disk) { + ub->params.devt.disk_major = MAJOR(disk_devt(ub->ub_disk)); + ub->params.devt.disk_minor = MINOR(disk_devt(ub->ub_disk)); + } else { + ub->params.devt.disk_major = 0; + ub->params.devt.disk_minor = 0; + } + ub->params.types |= UBLK_PARAM_TYPE_DEVT; +} + static int ublk_ctrl_get_params(struct ublk_device *ub, struct io_uring_cmd *cmd) { @@ -1798,6 +1819,7 @@ static int ublk_ctrl_get_params(struct ublk_device *ub, ph.len = sizeof(struct ublk_params); mutex_lock(&ub->mutex); + ublk_ctrl_fill_params_devt(ub); if (copy_to_user(argp, &ub->params, ph.len)) ret = -EFAULT; else diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h index 8f88e3a29998..4e38b9aa0293 100644 --- a/include/uapi/linux/ublk_cmd.h +++ b/include/uapi/linux/ublk_cmd.h @@ -214,6 +214,17 @@ struct ublk_param_discard { __u16 reserved0; }; +/* + * read-only, can't set via UBLK_CMD_SET_PARAMS, disk_devt is available + * after device is started + */ +struct ublk_param_devt { + __u32 char_major; + __u32 char_minor; + __u32 disk_major; + __u32 disk_minor; +}; + struct ublk_params { /* * Total length of parameters, userspace has to set 'len' for both @@ -224,10 +235,12 @@ struct ublk_params { __u32 len; #define UBLK_PARAM_TYPE_BASIC (1 << 0) #define UBLK_PARAM_TYPE_DISCARD (1 << 1) +#define UBLK_PARAM_TYPE_DEVT (1 << 2) __u32 types; /* types of parameter included */ struct ublk_param_basic basic; struct ublk_param_discard discard; + struct ublk_param_devt devt; }; #endif