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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 <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230106041711.914434-5-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Ming Lei 2023-01-06 12:17:09 +08:00 committed by Jens Axboe
parent bfbcef0363
commit abb864d380
2 changed files with 36 additions and 1 deletions
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24
drivers/block/ublk_drv.c
View File

@ -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

13
include/uapi/linux/ublk_cmd.h
View File

@ -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