Skip to content

Commit

Permalink
ublk_drv: add SET_PARAMS/GET_PARAMS control command
Browse files Browse the repository at this point in the history 
Add two commands to set/get parameters generically.

One important goal of ublk is to provide generic framework for making
block device by userspace flexibly.

As one generic block device, there are still lots of block parameters,
such as max_sectors, write_cache/fua, discard related limits,
zoned parameters, ...., so this patch starts to add generic mechanism
for set/get device parameters.

Both generic block parameters(all kinds of queue settings) and ublk
feature parameters can be covered with this way, then it becomes quite
easy to extend in future.

Add two parameter types are used so far: basic(covers basic queue setting
and misc settings which can't be grouped easily) and discard, basic type
must be set, and discard type becomes optional now

This way provides mechanism to simulate any kind of generic block device
from userspace easily, from both block queue setting viewpoint or ublk
feature viewpoint.

The style of putting all parameters together is suggested by Christoph.

Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20220730092750.1118167-4-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
  • Loading branch information
Ming Lei authored and Jens Axboe committed Aug 3, 2022
1 parent 93d71ec commit 0aa7317
Show file tree
Hide file tree
Showing 2 changed files with 234 additions and 18 deletions.
205 changes: 187 additions & 18 deletions drivers/block/ublk_drv.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,9 @@
/* All UBLK_F_* have to be included into UBLK_F_ALL */
#define UBLK_F_ALL (UBLK_F_SUPPORT_ZERO_COPY | UBLK_F_URING_CMD_COMP_IN_TASK)

/* All UBLK_PARAM_TYPE_* should be included here */
#define UBLK_PARAM_TYPE_ALL (UBLK_PARAM_TYPE_BASIC | UBLK_PARAM_TYPE_DISCARD)

struct ublk_rq_data {
struct callback_head work;
};
Expand Down Expand Up @@ -137,6 +140,8 @@ struct ublk_device {
spinlock_t mm_lock;
struct mm_struct *mm;

struct ublk_params params;

struct completion completion;
unsigned int nr_queues_ready;
atomic_t nr_aborted_queues;
Expand All @@ -149,6 +154,12 @@ struct ublk_device {
struct work_struct stop_work;
};

/* header of ublk_params */
struct ublk_params_header {
__u32 len;
__u32 types;
};

static dev_t ublk_chr_devt;
static struct class *ublk_chr_class;

Expand All @@ -160,6 +171,91 @@ static DEFINE_MUTEX(ublk_ctl_mutex);

static struct miscdevice ublk_misc;

static void 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;

blk_queue_logical_block_size(q, 1 << p->logical_bs_shift);
blk_queue_physical_block_size(q, 1 << p->physical_bs_shift);
blk_queue_io_min(q, 1 << p->io_min_shift);
blk_queue_io_opt(q, 1 << p->io_opt_shift);

blk_queue_write_cache(q, p->attrs & UBLK_ATTR_VOLATILE_CACHE,
p->attrs & UBLK_ATTR_FUA);
if (p->attrs & UBLK_ATTR_ROTATIONAL)
blk_queue_flag_clear(QUEUE_FLAG_NONROT, q);
else
blk_queue_flag_set(QUEUE_FLAG_NONROT, q);

blk_queue_max_hw_sectors(q, p->max_sectors);
blk_queue_chunk_sectors(q, p->chunk_sectors);
blk_queue_virt_boundary(q, p->virt_boundary_mask);

if (p->attrs & UBLK_ATTR_READ_ONLY)
set_disk_ro(ub->ub_disk, true);

set_capacity(ub->ub_disk, p->dev_sectors);
}

static void ublk_dev_param_discard_apply(struct ublk_device *ub)
{
struct request_queue *q = ub->ub_disk->queue;
const struct ublk_param_discard *p = &ub->params.discard;

q->limits.discard_alignment = p->discard_alignment;
q->limits.discard_granularity = p->discard_granularity;
blk_queue_max_discard_sectors(q, p->max_discard_sectors);
blk_queue_max_write_zeroes_sectors(q,
p->max_write_zeroes_sectors);
blk_queue_max_discard_segments(q, p->max_discard_segments);
}

static int ublk_validate_params(const struct ublk_device *ub)
{
/* basic param is the only one which must be set */
if (ub->params.types & UBLK_PARAM_TYPE_BASIC) {
const struct ublk_param_basic *p = &ub->params.basic;

if (p->logical_bs_shift > PAGE_SHIFT)
return -EINVAL;

if (p->logical_bs_shift > p->physical_bs_shift)
return -EINVAL;

if (p->max_sectors > (ub->dev_info.rq_max_blocks <<
(ub->bs_shift - 9)))
return -EINVAL;
} else
return -EINVAL;

if (ub->params.types & UBLK_PARAM_TYPE_DISCARD) {
const struct ublk_param_discard *p = &ub->params.discard;

/* So far, only support single segment discard */
if (p->max_discard_sectors && p->max_discard_segments != 1)
return -EINVAL;

if (!p->discard_granularity)
return -EINVAL;
}

return 0;
}

static int ublk_apply_params(struct ublk_device *ub)
{
if (!(ub->params.types & UBLK_PARAM_TYPE_BASIC))
return -EINVAL;

ublk_dev_param_basic_apply(ub);

if (ub->params.types & UBLK_PARAM_TYPE_DISCARD)
ublk_dev_param_discard_apply(ub);

return 0;
}

static inline bool ublk_can_use_task_work(const struct ublk_queue *ubq)
{
if (IS_BUILTIN(CONFIG_BLK_DEV_UBLK) &&
Expand Down Expand Up @@ -1138,7 +1234,6 @@ static int ublk_ctrl_start_dev(struct io_uring_cmd *cmd)
{
struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
int ublksrv_pid = (int)header->data[0];
unsigned long dev_blocks = header->data[1];
struct ublk_device *ub;
struct gendisk *disk;
int ret = -EINVAL;
Expand All @@ -1161,10 +1256,6 @@ static int ublk_ctrl_start_dev(struct io_uring_cmd *cmd)
goto out_unlock;
}

/* We may get disk size updated */
if (dev_blocks)
ub->dev_info.dev_blocks = dev_blocks;

disk = blk_mq_alloc_disk(&ub->tag_set, ub);
if (IS_ERR(disk)) {
ret = PTR_ERR(disk);
Expand All @@ -1174,19 +1265,13 @@ static int ublk_ctrl_start_dev(struct io_uring_cmd *cmd)
disk->fops = &ub_fops;
disk->private_data = ub;

blk_queue_logical_block_size(disk->queue, ub->dev_info.block_size);
blk_queue_physical_block_size(disk->queue, ub->dev_info.block_size);
blk_queue_io_min(disk->queue, ub->dev_info.block_size);
blk_queue_max_hw_sectors(disk->queue,
ub->dev_info.rq_max_blocks << (ub->bs_shift - 9));
disk->queue->limits.discard_granularity = PAGE_SIZE;
blk_queue_max_discard_sectors(disk->queue, UINT_MAX >> 9);
blk_queue_max_write_zeroes_sectors(disk->queue, UINT_MAX >> 9);

set_capacity(disk, ub->dev_info.dev_blocks << (ub->bs_shift - 9));

ub->dev_info.ublksrv_pid = ublksrv_pid;
ub->ub_disk = disk;

ret = ublk_apply_params(ub);
if (ret)
goto out_put_disk;

get_device(&ub->cdev_dev);
ret = add_disk(disk);
if (ret) {
Expand All @@ -1195,11 +1280,13 @@ static int ublk_ctrl_start_dev(struct io_uring_cmd *cmd)
* called in case of add_disk failure.
*/
ublk_put_device(ub);
put_disk(disk);
goto out_unlock;
goto out_put_disk;
}
set_bit(UB_STATE_USED, &ub->state);
ub->dev_info.state = UBLK_S_DEV_LIVE;
out_put_disk:
if (ret)
put_disk(disk);
out_unlock:
mutex_unlock(&ub->mutex);
ublk_put_device(ub);
Expand Down Expand Up @@ -1447,6 +1534,82 @@ static int ublk_ctrl_get_dev_info(struct io_uring_cmd *cmd)
return ret;
}

static int ublk_ctrl_get_params(struct io_uring_cmd *cmd)
{
struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
void __user *argp = (void __user *)(unsigned long)header->addr;
struct ublk_params_header ph;
struct ublk_device *ub;
int ret;

if (header->len <= sizeof(ph) || !header->addr)
return -EINVAL;

if (copy_from_user(&ph, argp, sizeof(ph)))
return -EFAULT;

if (ph.len > header->len || !ph.len)
return -EINVAL;

if (ph.len > sizeof(struct ublk_params))
ph.len = sizeof(struct ublk_params);

ub = ublk_get_device_from_id(header->dev_id);
if (!ub)
return -EINVAL;

mutex_lock(&ub->mutex);
if (copy_to_user(argp, &ub->params, ph.len))
ret = -EFAULT;
else
ret = 0;
mutex_unlock(&ub->mutex);

ublk_put_device(ub);
return ret;
}

static int ublk_ctrl_set_params(struct io_uring_cmd *cmd)
{
struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
void __user *argp = (void __user *)(unsigned long)header->addr;
struct ublk_params_header ph;
struct ublk_device *ub;
int ret = -EFAULT;

if (header->len <= sizeof(ph) || !header->addr)
return -EINVAL;

if (copy_from_user(&ph, argp, sizeof(ph)))
return -EFAULT;

if (ph.len > header->len || !ph.len || !ph.types)
return -EINVAL;

if (ph.len > sizeof(struct ublk_params))
ph.len = sizeof(struct ublk_params);

ub = ublk_get_device_from_id(header->dev_id);
if (!ub)
return -EINVAL;

/* parameters can only be changed when device isn't live */
mutex_lock(&ub->mutex);
if (ub->dev_info.state == UBLK_S_DEV_LIVE) {
ret = -EACCES;
} else if (copy_from_user(&ub->params, argp, ph.len)) {
ret = -EFAULT;
} else {
/* clear all we don't support yet */
ub->params.types &= UBLK_PARAM_TYPE_ALL;
ret = ublk_validate_params(ub);
}
mutex_unlock(&ub->mutex);
ublk_put_device(ub);

return ret;
}

static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
unsigned int issue_flags)
{
Expand Down Expand Up @@ -1482,6 +1645,12 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
case UBLK_CMD_GET_QUEUE_AFFINITY:
ret = ublk_ctrl_get_queue_affinity(cmd);
break;
case UBLK_CMD_GET_PARAMS:
ret = ublk_ctrl_get_params(cmd);
break;
case UBLK_CMD_SET_PARAMS:
ret = ublk_ctrl_set_params(cmd);
break;
default:
break;
}
Expand Down
47 changes: 47 additions & 0 deletions include/uapi/linux/ublk_cmd.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,8 @@
#define UBLK_CMD_DEL_DEV 0x05
#define UBLK_CMD_START_DEV 0x06
#define UBLK_CMD_STOP_DEV 0x07
#define UBLK_CMD_SET_PARAMS 0x08
#define UBLK_CMD_GET_PARAMS 0x09

/*
* IO commands, issued by ublk server, and handled by ublk driver.
Expand Down Expand Up @@ -158,4 +160,49 @@ struct ublksrv_io_cmd {
__u64 addr;
};

struct ublk_param_basic {
#define UBLK_ATTR_READ_ONLY (1 << 0)
#define UBLK_ATTR_ROTATIONAL (1 << 1)
#define UBLK_ATTR_VOLATILE_CACHE (1 << 2)
#define UBLK_ATTR_FUA (1 << 3)
__u32 attrs;
__u8 logical_bs_shift;
__u8 physical_bs_shift;
__u8 io_opt_shift;
__u8 io_min_shift;

__u32 max_sectors;
__u32 chunk_sectors;

__u64 dev_sectors;
__u64 virt_boundary_mask;
};

struct ublk_param_discard {
__u32 discard_alignment;

__u32 discard_granularity;
__u32 max_discard_sectors;

__u32 max_write_zeroes_sectors;
__u16 max_discard_segments;
__u16 reserved0;
};

struct ublk_params {
/*
* Total length of parameters, userspace has to set 'len' for both
* SET_PARAMS and GET_PARAMS command, and driver may update len
* if two sides use different version of 'ublk_params', same with
* 'types' fields.
*/
__u32 len;
#define UBLK_PARAM_TYPE_BASIC (1 << 0)
#define UBLK_PARAM_TYPE_DISCARD (1 << 1)
__u32 types; /* types of parameter included */

struct ublk_param_basic basic;
struct ublk_param_discard discard;
};

#endif

0 comments on commit 0aa7317

Please sign in to comment.