Commit abb864d3 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

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: default avatarMing Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20230106041711.914434-5-ming.lei@redhat.com


Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent bfbcef03

drivers/block/ublk_drv.c

+23 −1
Original line number Diff line number Diff line
@@ -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

include/uapi/linux/ublk_cmd.h

+13 −0
Original line number Diff line number Diff line
@@ -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