Commit b256795b authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

ublk: handle UBLK_U_IO_PREP_IO_CMDS 



This commit implements the handling of the UBLK_U_IO_PREP_IO_CMDS command,
which allows userspace to prepare a batch of I/O requests.

The core of this change is the `ublk_walk_cmd_buf` function, which iterates
over the elements in the uring_cmd fixed buffer. For each element, it parses
the I/O details, finds the corresponding `ublk_io` structure, and prepares it
for future dispatch.

Add per-io lock for protecting concurrent delivery and committing.

Reviewed-by: default avatarCaleb Sander Mateos <csander@purestorage.com>
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent e86f89ab

drivers/block/ublk_drv.c

+190 −1
Original line number Diff line number Diff line
@@ -208,6 +208,7 @@ struct ublk_io { 
	unsigned task_registered_buffers;



	void *buf_ctx_handle;

	spinlock_t lock;

} ____cacheline_aligned_in_smp;



struct ublk_queue {
@@ -280,6 +281,16 @@ static inline bool ublk_dev_support_batch_io(const struct ublk_device *ub) 
	return false;

}



static inline void ublk_io_lock(struct ublk_io *io)

{

	spin_lock(&io->lock);

}



static inline void ublk_io_unlock(struct ublk_io *io)

{

	spin_unlock(&io->lock);

}



static inline struct ublksrv_io_desc *

ublk_get_iod(const struct ublk_queue *ubq, unsigned tag)

{
@@ -2699,6 +2710,171 @@ static int ublk_ch_uring_cmd(struct io_uring_cmd *cmd, unsigned int issue_flags) 
	return ublk_ch_uring_cmd_local(cmd, issue_flags);

}



static inline __u64 ublk_batch_buf_addr(const struct ublk_batch_io *uc,

					const struct ublk_elem_header *elem)

{

	const void *buf = elem;



	if (uc->flags & UBLK_BATCH_F_HAS_BUF_ADDR)

		return *(const __u64 *)(buf + sizeof(*elem));

	return 0;

}



static struct ublk_auto_buf_reg

ublk_batch_auto_buf_reg(const struct ublk_batch_io *uc,

			const struct ublk_elem_header *elem)

{

	struct ublk_auto_buf_reg reg = {

		.index = elem->buf_index,

		.flags = (uc->flags & UBLK_BATCH_F_AUTO_BUF_REG_FALLBACK) ?

			UBLK_AUTO_BUF_REG_FALLBACK : 0,

	};



	return reg;

}



/*

 * 48 can hold any type of buffer element(8, 16 and 24 bytes) because

 * it is the least common multiple(LCM) of 8, 16 and 24

 */

#define UBLK_CMD_BATCH_TMP_BUF_SZ  (48 * 10)

struct ublk_batch_io_iter {

	void __user *uaddr;

	unsigned done, total;

	unsigned char elem_bytes;

	/* copy to this buffer from user space */

	unsigned char buf[UBLK_CMD_BATCH_TMP_BUF_SZ];

};



static inline int

__ublk_walk_cmd_buf(struct ublk_queue *ubq,

		    struct ublk_batch_io_iter *iter,

		    const struct ublk_batch_io_data *data,

		    unsigned bytes,

		    int (*cb)(struct ublk_queue *q,

			    const struct ublk_batch_io_data *data,

			    const struct ublk_elem_header *elem))

{

	unsigned int i;

	int ret = 0;



	for (i = 0; i < bytes; i += iter->elem_bytes) {

		const struct ublk_elem_header *elem =

			(const struct ublk_elem_header *)&iter->buf[i];



		if (unlikely(elem->tag >= data->ub->dev_info.queue_depth)) {

			ret = -EINVAL;

			break;

		}



		ret = cb(ubq, data, elem);

		if (unlikely(ret))

			break;

	}



	iter->done += i;

	return ret;

}



static int ublk_walk_cmd_buf(struct ublk_batch_io_iter *iter,

			     const struct ublk_batch_io_data *data,

			     int (*cb)(struct ublk_queue *q,

				     const struct ublk_batch_io_data *data,

				     const struct ublk_elem_header *elem))

{

	struct ublk_queue *ubq = ublk_get_queue(data->ub, data->header.q_id);

	int ret = 0;



	while (iter->done < iter->total) {

		unsigned int len = min(sizeof(iter->buf), iter->total - iter->done);



		if (copy_from_user(iter->buf, iter->uaddr + iter->done, len)) {

			pr_warn("ublk%d: read batch cmd buffer failed\n",

					data->ub->dev_info.dev_id);

			return -EFAULT;

		}



		ret = __ublk_walk_cmd_buf(ubq, iter, data, len, cb);

		if (ret)

			return ret;

	}

	return 0;

}



static int ublk_batch_unprep_io(struct ublk_queue *ubq,

				const struct ublk_batch_io_data *data,

				const struct ublk_elem_header *elem)

{

	struct ublk_io *io = &ubq->ios[elem->tag];



	data->ub->nr_io_ready--;

	ublk_io_lock(io);

	io->flags = 0;

	ublk_io_unlock(io);

	return 0;

}



static void ublk_batch_revert_prep_cmd(struct ublk_batch_io_iter *iter,

				       const struct ublk_batch_io_data *data)

{

	int ret;



	/* Re-process only what we've already processed, starting from beginning */

	iter->total = iter->done;

	iter->done = 0;



	ret = ublk_walk_cmd_buf(iter, data, ublk_batch_unprep_io);

	WARN_ON_ONCE(ret);

}



static int ublk_batch_prep_io(struct ublk_queue *ubq,

			      const struct ublk_batch_io_data *data,

			      const struct ublk_elem_header *elem)

{

	struct ublk_io *io = &ubq->ios[elem->tag];

	const struct ublk_batch_io *uc = &data->header;

	union ublk_io_buf buf = { 0 };

	int ret;



	if (ublk_dev_support_auto_buf_reg(data->ub))

		buf.auto_reg = ublk_batch_auto_buf_reg(uc, elem);

	else if (ublk_dev_need_map_io(data->ub)) {

		buf.addr = ublk_batch_buf_addr(uc, elem);



		ret = ublk_check_fetch_buf(data->ub, buf.addr);

		if (ret)

			return ret;

	}



	ublk_io_lock(io);

	ret = __ublk_fetch(data->cmd, data->ub, io);

	if (!ret)

		io->buf = buf;

	ublk_io_unlock(io);



	return ret;

}



static int ublk_handle_batch_prep_cmd(const struct ublk_batch_io_data *data)

{

	const struct ublk_batch_io *uc = &data->header;

	struct io_uring_cmd *cmd = data->cmd;

	struct ublk_batch_io_iter iter = {

		.uaddr = u64_to_user_ptr(READ_ONCE(cmd->sqe->addr)),

		.total = uc->nr_elem * uc->elem_bytes,

		.elem_bytes = uc->elem_bytes,

	};

	int ret;



	mutex_lock(&data->ub->mutex);

	ret = ublk_walk_cmd_buf(&iter, data, ublk_batch_prep_io);



	if (ret && iter.done)

		ublk_batch_revert_prep_cmd(&iter, data);

	mutex_unlock(&data->ub->mutex);

	return ret;

}



static int ublk_check_batch_cmd_flags(const struct ublk_batch_io *uc)

{

	unsigned elem_bytes = sizeof(struct ublk_elem_header);
@@ -2765,6 +2941,11 @@ static int ublk_ch_batch_io_uring_cmd(struct io_uring_cmd *cmd, 


	switch (cmd_op) {

	case UBLK_U_IO_PREP_IO_CMDS:

		ret = ublk_check_batch_cmd(&data);

		if (ret)

			goto out;

		ret = ublk_handle_batch_prep_cmd(&data);

		break;

	case UBLK_U_IO_COMMIT_IO_CMDS:

		ret = ublk_check_batch_cmd(&data);

		if (ret)
@@ -2952,7 +3133,7 @@ static int ublk_init_queue(struct ublk_device *ub, int q_id) 
	struct ublk_queue *ubq;

	struct page *page;

	int numa_node;

	int size;

	int size, i;



	/* Determine NUMA node based on queue's CPU affinity */

	numa_node = ublk_get_queue_numa_node(ub, q_id);
@@ -2977,6 +3158,9 @@ static int ublk_init_queue(struct ublk_device *ub, int q_id) 
	}

	ubq->io_cmd_buf = page_address(page);



	for (i = 0; i < ubq->q_depth; i++)

		spin_lock_init(&ubq->ios[i].lock);



	ub->queues[q_id] = ubq;

	ubq->dev = ub;

	return 0;
@@ -3220,6 +3404,11 @@ static int ublk_ctrl_start_dev(struct ublk_device *ub, 
		return -EINVAL;



	mutex_lock(&ub->mutex);

	/* device may become not ready in case of F_BATCH */

	if (!ublk_dev_ready(ub)) {

		ret = -EINVAL;

		goto out_unlock;

	}

	if (ub->dev_info.state == UBLK_S_DEV_LIVE ||

	    test_bit(UB_STATE_USED, &ub->state)) {

		ret = -EEXIST;

include/uapi/linux/ublk_cmd.h

+5 −0
Original line number Diff line number Diff line
@@ -103,6 +103,11 @@ 
	_IOWR('u', 0x23, struct ublksrv_io_cmd)

#define	UBLK_U_IO_UNREGISTER_IO_BUF	\

	_IOWR('u', 0x24, struct ublksrv_io_cmd)



/*

 * return 0 if the command is run successfully, otherwise failure code

 * is returned

 */

#define	UBLK_U_IO_PREP_IO_CMDS	\

	_IOWR('u', 0x25, struct ublk_batch_io)

#define	UBLK_U_IO_COMMIT_IO_CMDS	\