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Commit 9561a7ad authored by Josef Bacik's avatar Josef Bacik Committed by Jens Axboe
Browse files

nbd: add multi-connection support 



NBD can become contended on its single connection.  We have to serialize all
writes and we can only process one read response at a time.  Fix this by
allowing userspace to provide multiple connections to a single nbd device.  This
coupled with block-mq drastically increases performance in multi-process cases.
Thanks,

Signed-off-by: default avatarJosef Bacik <jbacik@fb.com>
Signed-off-by: default avatarJens Axboe <axboe@fb.com>
parent e00f4f4d

drivers/block/nbd.c

+238 −144
Original line number Diff line number Diff line
@@ -41,26 +41,34 @@ 


#include <linux/nbd.h>



struct nbd_sock {

	struct socket *sock;

	struct mutex tx_lock;

};



#define NBD_TIMEDOUT			0

#define NBD_DISCONNECT_REQUESTED	1

#define NBD_DISCONNECTED		2

#define NBD_RUNNING			3



struct nbd_device {

	u32 flags;

	unsigned long runtime_flags;

	struct socket * sock;	/* If == NULL, device is not ready, yet	*/

	struct nbd_sock **socks;

	int magic;



	struct blk_mq_tag_set tag_set;



	struct mutex tx_lock;

	struct mutex config_lock;

	struct gendisk *disk;

	int num_connections;

	atomic_t recv_threads;

	wait_queue_head_t recv_wq;

	int blksize;

	loff_t bytesize;



	/* protects initialization and shutdown of the socket */

	spinlock_t sock_lock;

	struct task_struct *task_recv;

	struct task_struct *task_send;

	struct task_struct *task_setup;



#if IS_ENABLED(CONFIG_DEBUG_FS)

	struct dentry *dbg_dir;
@@ -69,7 +77,7 @@ struct nbd_device { 


struct nbd_cmd {

	struct nbd_device *nbd;

	struct list_head list;

	struct completion send_complete;

};



#if IS_ENABLED(CONFIG_DEBUG_FS)
@@ -159,22 +167,20 @@ static void nbd_end_request(struct nbd_cmd *cmd) 
 */

static void sock_shutdown(struct nbd_device *nbd)

{

	struct socket *sock;



	spin_lock(&nbd->sock_lock);

	int i;



	if (!nbd->sock) {

		spin_unlock_irq(&nbd->sock_lock);

	if (nbd->num_connections == 0)

		return;

	if (test_and_set_bit(NBD_DISCONNECTED, &nbd->runtime_flags))

		return;

	}



	sock = nbd->sock;

	dev_warn(disk_to_dev(nbd->disk), "shutting down socket\n");

	nbd->sock = NULL;

	spin_unlock(&nbd->sock_lock);



	kernel_sock_shutdown(sock, SHUT_RDWR);

	sockfd_put(sock);

	for (i = 0; i < nbd->num_connections; i++) {

		struct nbd_sock *nsock = nbd->socks[i];

		mutex_lock(&nsock->tx_lock);

		kernel_sock_shutdown(nsock->sock, SHUT_RDWR);

		mutex_unlock(&nsock->tx_lock);

	}

	dev_warn(disk_to_dev(nbd->disk), "shutting down sockets\n");

}



static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
@@ -182,35 +188,31 @@ static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req, 
{

	struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);

	struct nbd_device *nbd = cmd->nbd;

	struct socket *sock = NULL;



	spin_lock(&nbd->sock_lock);



	dev_err(nbd_to_dev(nbd), "Connection timed out, shutting down connection\n");

	set_bit(NBD_TIMEDOUT, &nbd->runtime_flags);



	if (nbd->sock) {

		sock = nbd->sock;

		get_file(sock->file);

	}



	spin_unlock(&nbd->sock_lock);

	if (sock) {

		kernel_sock_shutdown(sock, SHUT_RDWR);

		sockfd_put(sock);

	}



	req->errors++;

	dev_err(nbd_to_dev(nbd), "Connection timed out, shutting down connection\n");



	/*

	 * If our disconnect packet times out then we're already holding the

	 * config_lock and could deadlock here, so just set an error and return,

	 * we'll handle shutting everything down later.

	 */

	if (req->cmd_type == REQ_TYPE_DRV_PRIV)

		return BLK_EH_HANDLED;

	mutex_lock(&nbd->config_lock);

	sock_shutdown(nbd);

	mutex_unlock(&nbd->config_lock);

	return BLK_EH_HANDLED;

}



/*

 *  Send or receive packet.

 */

static int sock_xmit(struct nbd_device *nbd, int send, void *buf, int size,

		int msg_flags)

static int sock_xmit(struct nbd_device *nbd, int index, int send, void *buf,

		     int size, int msg_flags)

{

	struct socket *sock = nbd->sock;

	struct socket *sock = nbd->socks[index]->sock;

	int result;

	struct msghdr msg;

	struct kvec iov;
@@ -254,19 +256,19 @@ static int sock_xmit(struct nbd_device *nbd, int send, void *buf, int size, 
	return result;

}



static inline int sock_send_bvec(struct nbd_device *nbd, struct bio_vec *bvec,

		int flags)

static inline int sock_send_bvec(struct nbd_device *nbd, int index,

				 struct bio_vec *bvec, int flags)

{

	int result;

	void *kaddr = kmap(bvec->bv_page);

	result = sock_xmit(nbd, 1, kaddr + bvec->bv_offset,

	result = sock_xmit(nbd, index, 1, kaddr + bvec->bv_offset,

			   bvec->bv_len, flags);

	kunmap(bvec->bv_page);

	return result;

}



/* always call with the tx_lock held */

static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd)

static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)

{

	struct request *req = blk_mq_rq_from_pdu(cmd);

	int result, flags;
@@ -274,10 +276,9 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd) 
	unsigned long size = blk_rq_bytes(req);

	struct bio *bio;

	u32 type;

	u32 tag = blk_mq_unique_tag(req);



	if (req->cmd_type == REQ_TYPE_DRV_PRIV)

		type = NBD_CMD_DISC;

	else if (req_op(req) == REQ_OP_DISCARD)

	if (req_op(req) == REQ_OP_DISCARD)

		type = NBD_CMD_TRIM;

	else if (req_op(req) == REQ_OP_FLUSH)

		type = NBD_CMD_FLUSH;
@@ -289,16 +290,16 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd) 
	memset(&request, 0, sizeof(request));

	request.magic = htonl(NBD_REQUEST_MAGIC);

	request.type = htonl(type);

	if (type != NBD_CMD_FLUSH && type != NBD_CMD_DISC) {

	if (type != NBD_CMD_FLUSH) {

		request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);

		request.len = htonl(size);

	}

	memcpy(request.handle, &req->tag, sizeof(req->tag));

	memcpy(request.handle, &tag, sizeof(tag));



	dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n",

		cmd, nbdcmd_to_ascii(type),

		(unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req));

	result = sock_xmit(nbd, 1, &request, sizeof(request),

	result = sock_xmit(nbd, index, 1, &request, sizeof(request),

			(type == NBD_CMD_WRITE) ? MSG_MORE : 0);

	if (result <= 0) {

		dev_err(disk_to_dev(nbd->disk),
@@ -323,7 +324,7 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd) 
				flags = MSG_MORE;

			dev_dbg(nbd_to_dev(nbd), "request %p: sending %d bytes data\n",

				cmd, bvec.bv_len);

			result = sock_send_bvec(nbd, &bvec, flags);

			result = sock_send_bvec(nbd, index, &bvec, flags);

			if (result <= 0) {

				dev_err(disk_to_dev(nbd->disk),

					"Send data failed (result %d)\n",
@@ -344,29 +345,32 @@ static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd) 
	return 0;

}



static inline int sock_recv_bvec(struct nbd_device *nbd, struct bio_vec *bvec)

static inline int sock_recv_bvec(struct nbd_device *nbd, int index,

				 struct bio_vec *bvec)

{

	int result;

	void *kaddr = kmap(bvec->bv_page);

	result = sock_xmit(nbd, 0, kaddr + bvec->bv_offset, bvec->bv_len,

			MSG_WAITALL);

	result = sock_xmit(nbd, index, 0, kaddr + bvec->bv_offset,

			   bvec->bv_len, MSG_WAITALL);

	kunmap(bvec->bv_page);

	return result;

}



/* NULL returned = something went wrong, inform userspace */

static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd)

static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)

{

	int result;

	struct nbd_reply reply;

	struct nbd_cmd *cmd;

	struct request *req = NULL;

	u16 hwq;

	int tag;

	u32 tag;



	reply.magic = 0;

	result = sock_xmit(nbd, 0, &reply, sizeof(reply), MSG_WAITALL);

	result = sock_xmit(nbd, index, 0, &reply, sizeof(reply), MSG_WAITALL);

	if (result <= 0) {

		if (!test_bit(NBD_DISCONNECTED, &nbd->runtime_flags) &&

		    !test_bit(NBD_DISCONNECT_REQUESTED, &nbd->runtime_flags))

			dev_err(disk_to_dev(nbd->disk),

				"Receive control failed (result %d)\n", result);

		return ERR_PTR(result);
@@ -378,7 +382,7 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd) 
		return ERR_PTR(-EPROTO);

	}



	memcpy(&tag, reply.handle, sizeof(int));

	memcpy(&tag, reply.handle, sizeof(u32));



	hwq = blk_mq_unique_tag_to_hwq(tag);

	if (hwq < nbd->tag_set.nr_hw_queues)
@@ -390,7 +394,6 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd) 
		return ERR_PTR(-ENOENT);

	}

	cmd = blk_mq_rq_to_pdu(req);



	if (ntohl(reply.error)) {

		dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n",

			ntohl(reply.error));
@@ -404,7 +407,7 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd) 
		struct bio_vec bvec;



		rq_for_each_segment(bvec, req, iter) {

			result = sock_recv_bvec(nbd, &bvec);

			result = sock_recv_bvec(nbd, index, &bvec);

			if (result <= 0) {

				dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",

					result);
@@ -414,6 +417,9 @@ static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd) 
			dev_dbg(nbd_to_dev(nbd), "request %p: got %d bytes data\n",

				cmd, bvec.bv_len);

		}

	} else {

		/* See the comment in nbd_queue_rq. */

		wait_for_completion(&cmd->send_complete);

	}

	return cmd;

}
@@ -432,25 +438,24 @@ static struct device_attribute pid_attr = { 
	.show = pid_show,

};



static int nbd_thread_recv(struct nbd_device *nbd, struct block_device *bdev)

struct recv_thread_args {

	struct work_struct work;

	struct nbd_device *nbd;

	int index;

};



static void recv_work(struct work_struct *work)

{

	struct recv_thread_args *args = container_of(work,

						     struct recv_thread_args,

						     work);

	struct nbd_device *nbd = args->nbd;

	struct nbd_cmd *cmd;

	int ret;

	int ret = 0;



	BUG_ON(nbd->magic != NBD_MAGIC);



	sk_set_memalloc(nbd->sock->sk);



	ret = device_create_file(disk_to_dev(nbd->disk), &pid_attr);

	if (ret) {

		dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n");

		return ret;

	}



	nbd_size_update(nbd, bdev);



	while (1) {

		cmd = nbd_read_stat(nbd);

		cmd = nbd_read_stat(nbd, args->index);

		if (IS_ERR(cmd)) {

			ret = PTR_ERR(cmd);

			break;
@@ -459,10 +464,14 @@ static int nbd_thread_recv(struct nbd_device *nbd, struct block_device *bdev) 
		nbd_end_request(cmd);

	}



	nbd_size_clear(nbd, bdev);



	device_remove_file(disk_to_dev(nbd->disk), &pid_attr);

	return ret;

	/*

	 * We got an error, shut everybody down if this wasn't the result of a

	 * disconnect request.

	 */

	if (ret && !test_bit(NBD_DISCONNECT_REQUESTED, &nbd->runtime_flags))

		sock_shutdown(nbd);

	atomic_dec(&nbd->recv_threads);

	wake_up(&nbd->recv_wq);

}



static void nbd_clear_req(struct request *req, void *data, bool reserved)
@@ -480,26 +489,35 @@ static void nbd_clear_que(struct nbd_device *nbd) 
{

	BUG_ON(nbd->magic != NBD_MAGIC);



	/*

	 * Because we have set nbd->sock to NULL under the tx_lock, all

	 * modifications to the list must have completed by now.

	 */

	BUG_ON(nbd->sock);



	blk_mq_tagset_busy_iter(&nbd->tag_set, nbd_clear_req, NULL);

	dev_dbg(disk_to_dev(nbd->disk), "queue cleared\n");

}





static void nbd_handle_cmd(struct nbd_cmd *cmd)

static void nbd_handle_cmd(struct nbd_cmd *cmd, int index)

{

	struct request *req = blk_mq_rq_from_pdu(cmd);

	struct nbd_device *nbd = cmd->nbd;

	struct nbd_sock *nsock;



	if (req->cmd_type != REQ_TYPE_FS)

	if (index >= nbd->num_connections) {

		dev_err(disk_to_dev(nbd->disk),

			"Attempted send on invalid socket\n");

		goto error_out;

	}



	if (rq_data_dir(req) == WRITE &&

	if (test_bit(NBD_DISCONNECTED, &nbd->runtime_flags)) {

		dev_err(disk_to_dev(nbd->disk),

			"Attempted send on closed socket\n");

		goto error_out;

	}



	if (req->cmd_type != REQ_TYPE_FS &&

	    req->cmd_type != REQ_TYPE_DRV_PRIV)

		goto error_out;



	if (req->cmd_type == REQ_TYPE_FS &&

	    rq_data_dir(req) == WRITE &&

	    (nbd->flags & NBD_FLAG_READ_ONLY)) {

		dev_err(disk_to_dev(nbd->disk),

			"Write on read-only\n");
@@ -508,23 +526,22 @@ static void nbd_handle_cmd(struct nbd_cmd *cmd) 


	req->errors = 0;



	mutex_lock(&nbd->tx_lock);

	nbd->task_send = current;

	if (unlikely(!nbd->sock)) {

		mutex_unlock(&nbd->tx_lock);

	nsock = nbd->socks[index];

	mutex_lock(&nsock->tx_lock);

	if (unlikely(!nsock->sock)) {

		mutex_unlock(&nsock->tx_lock);

		dev_err(disk_to_dev(nbd->disk),

			"Attempted send on closed socket\n");

		goto error_out;

	}



	if (nbd_send_cmd(nbd, cmd) != 0) {

	if (nbd_send_cmd(nbd, cmd, index) != 0) {

		dev_err(disk_to_dev(nbd->disk), "Request send failed\n");

		req->errors++;

		nbd_end_request(cmd);

	}



	nbd->task_send = NULL;

	mutex_unlock(&nbd->tx_lock);

	mutex_unlock(&nsock->tx_lock);



	return;
@@ -538,39 +555,70 @@ static int nbd_queue_rq(struct blk_mq_hw_ctx *hctx, 
{

	struct nbd_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);



	/*

	 * Since we look at the bio's to send the request over the network we

	 * need to make sure the completion work doesn't mark this request done

	 * before we are done doing our send.  This keeps us from dereferencing

	 * freed data if we have particularly fast completions (ie we get the

	 * completion before we exit sock_xmit on the last bvec) or in the case

	 * that the server is misbehaving (or there was an error) before we're

	 * done sending everything over the wire.

	 */

	init_completion(&cmd->send_complete);

	blk_mq_start_request(bd->rq);

	nbd_handle_cmd(cmd);

	nbd_handle_cmd(cmd, hctx->queue_num);

	complete(&cmd->send_complete);



	return BLK_MQ_RQ_QUEUE_OK;

}



static int nbd_set_socket(struct nbd_device *nbd, struct socket *sock)

static int nbd_add_socket(struct nbd_device *nbd, struct socket *sock)

{

	int ret = 0;

	struct nbd_sock **socks;

	struct nbd_sock *nsock;



	spin_lock_irq(&nbd->sock_lock);



	if (nbd->sock) {

		ret = -EBUSY;

		goto out;

	if (!nbd->task_setup)

		nbd->task_setup = current;

	if (nbd->task_setup != current) {

		dev_err(disk_to_dev(nbd->disk),

			"Device being setup by another task");

		return -EINVAL;

	}



	nbd->sock = sock;

	socks = krealloc(nbd->socks, (nbd->num_connections + 1) *

			 sizeof(struct nbd_sock *), GFP_KERNEL);

	if (!socks)

		return -ENOMEM;

	nsock = kzalloc(sizeof(struct nbd_sock), GFP_KERNEL);

	if (!nsock)

		return -ENOMEM;



out:

	spin_unlock_irq(&nbd->sock_lock);

	nbd->socks = socks;



	return ret;

	mutex_init(&nsock->tx_lock);

	nsock->sock = sock;

	socks[nbd->num_connections++] = nsock;



	return 0;

}



/* Reset all properties of an NBD device */

static void nbd_reset(struct nbd_device *nbd)

{

	int i;



	for (i = 0; i < nbd->num_connections; i++)

		kfree(nbd->socks[i]);

	kfree(nbd->socks);

	nbd->socks = NULL;

	nbd->runtime_flags = 0;

	nbd->blksize = 1024;

	nbd->bytesize = 0;

	set_capacity(nbd->disk, 0);

	nbd->flags = 0;

	nbd->tag_set.timeout = 0;

	nbd->num_connections = 0;

	nbd->task_setup = NULL;

	queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD, nbd->disk->queue);

}
@@ -596,41 +644,46 @@ static void nbd_parse_flags(struct nbd_device *nbd, struct block_device *bdev) 
		blk_queue_write_cache(nbd->disk->queue, false, false);

}



static void send_disconnects(struct nbd_device *nbd)

{

	struct nbd_request request = {};

	int i, ret;



	request.magic = htonl(NBD_REQUEST_MAGIC);

	request.type = htonl(NBD_CMD_DISC);



	for (i = 0; i < nbd->num_connections; i++) {

		ret = sock_xmit(nbd, i, 1, &request, sizeof(request), 0);

		if (ret <= 0)

			dev_err(disk_to_dev(nbd->disk),

				"Send disconnect failed %d\n", ret);

	}

}



static int nbd_dev_dbg_init(struct nbd_device *nbd);

static void nbd_dev_dbg_close(struct nbd_device *nbd);



/* Must be called with tx_lock held */



/* Must be called with config_lock held */

static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,

		       unsigned int cmd, unsigned long arg)

{

	switch (cmd) {

	case NBD_DISCONNECT: {

		struct request *sreq;



		dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n");

		if (!nbd->sock)

		if (!nbd->socks)

			return -EINVAL;



		sreq = blk_mq_alloc_request(bdev_get_queue(bdev), WRITE, 0);

		if (!sreq)

			return -ENOMEM;



		mutex_unlock(&nbd->tx_lock);

		mutex_unlock(&nbd->config_lock);

		fsync_bdev(bdev);

		mutex_lock(&nbd->tx_lock);

		sreq->cmd_type = REQ_TYPE_DRV_PRIV;

		mutex_lock(&nbd->config_lock);



		/* Check again after getting mutex back.  */

		if (!nbd->sock) {

			blk_mq_free_request(sreq);

		if (!nbd->socks)

			return -EINVAL;

		}



		set_bit(NBD_DISCONNECT_REQUESTED, &nbd->runtime_flags);



		nbd_send_cmd(nbd, blk_mq_rq_to_pdu(sreq));

		blk_mq_free_request(sreq);

		if (!test_and_set_bit(NBD_DISCONNECT_REQUESTED,

				      &nbd->runtime_flags))

			send_disconnects(nbd);

		return 0;

	}
@@ -638,6 +691,20 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd, 
		sock_shutdown(nbd);

		nbd_clear_que(nbd);

		kill_bdev(bdev);

		nbd_bdev_reset(bdev);

		/*

		 * We want to give the run thread a chance to wait for everybody

		 * to clean up and then do it's own cleanup.

		 */

		if (!test_bit(NBD_RUNNING, &nbd->runtime_flags)) {

			int i;



			for (i = 0; i < nbd->num_connections; i++)

				kfree(nbd->socks[i]);

			kfree(nbd->socks);

			nbd->socks = NULL;

			nbd->num_connections = 0;

		}

		return 0;



	case NBD_SET_SOCK: {
@@ -647,7 +714,7 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd, 
		if (!sock)

			return err;



		err = nbd_set_socket(nbd, sock);

		err = nbd_add_socket(nbd, sock);

		if (!err && max_part)

			bdev->bd_invalidated = 1;
@@ -676,26 +743,58 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd, 
		return 0;



	case NBD_DO_IT: {

		int error;

		struct recv_thread_args *args;

		int num_connections = nbd->num_connections;

		int error, i;



		if (nbd->task_recv)

			return -EBUSY;

		if (!nbd->sock)

		if (!nbd->socks)

			return -EINVAL;

		if (num_connections > 1 &&

		    !(nbd->flags & NBD_FLAG_CAN_MULTI_CONN)) {

			dev_err(disk_to_dev(nbd->disk), "server does not support multiple connections per device.\n");

			goto out_err;

		}



		/* We have to claim the device under the lock */

		set_bit(NBD_RUNNING, &nbd->runtime_flags);

		blk_mq_update_nr_hw_queues(&nbd->tag_set, nbd->num_connections);

		args = kcalloc(num_connections, sizeof(*args), GFP_KERNEL);

		if (!args)

			goto out_err;

		nbd->task_recv = current;

		mutex_unlock(&nbd->tx_lock);

		mutex_unlock(&nbd->config_lock);



		nbd_parse_flags(nbd, bdev);



		error = device_create_file(disk_to_dev(nbd->disk), &pid_attr);

		if (error) {

			dev_err(disk_to_dev(nbd->disk), "device_create_file failed!\n");

			goto out_recv;

		}



		nbd_size_update(nbd, bdev);



		nbd_dev_dbg_init(nbd);

		error = nbd_thread_recv(nbd, bdev);

		for (i = 0; i < num_connections; i++) {

			sk_set_memalloc(nbd->socks[i]->sock->sk);

			atomic_inc(&nbd->recv_threads);

			INIT_WORK(&args[i].work, recv_work);

			args[i].nbd = nbd;

			args[i].index = i;

			queue_work(system_long_wq, &args[i].work);

		}

		wait_event_interruptible(nbd->recv_wq,

					 atomic_read(&nbd->recv_threads) == 0);

		for (i = 0; i < num_connections; i++)

			flush_work(&args[i].work);

		nbd_dev_dbg_close(nbd);



		mutex_lock(&nbd->tx_lock);

		nbd_size_clear(nbd, bdev);

		device_remove_file(disk_to_dev(nbd->disk), &pid_attr);

out_recv:

		mutex_lock(&nbd->config_lock);

		nbd->task_recv = NULL;



out_err:

		sock_shutdown(nbd);

		nbd_clear_que(nbd);

		kill_bdev(bdev);
@@ -708,7 +807,6 @@ static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd, 
			error = -ETIMEDOUT;



		nbd_reset(nbd);



		return error;

	}
@@ -740,9 +838,9 @@ static int nbd_ioctl(struct block_device *bdev, fmode_t mode, 


	BUG_ON(nbd->magic != NBD_MAGIC);



	mutex_lock(&nbd->tx_lock);

	mutex_lock(&nbd->config_lock);

	error = __nbd_ioctl(bdev, nbd, cmd, arg);

	mutex_unlock(&nbd->tx_lock);

	mutex_unlock(&nbd->config_lock);



	return error;

}
@@ -762,8 +860,6 @@ static int nbd_dbg_tasks_show(struct seq_file *s, void *unused) 


	if (nbd->task_recv)

		seq_printf(s, "recv: %d\n", task_pid_nr(nbd->task_recv));

	if (nbd->task_send)

		seq_printf(s, "send: %d\n", task_pid_nr(nbd->task_send));



	return 0;

}
@@ -887,9 +983,7 @@ static int nbd_init_request(void *data, struct request *rq, 
			    unsigned int numa_node)

{

	struct nbd_cmd *cmd = blk_mq_rq_to_pdu(rq);



	cmd->nbd = data;

	INIT_LIST_HEAD(&cmd->list);

	return 0;

}
@@ -999,13 +1093,13 @@ static int __init nbd_init(void) 
	for (i = 0; i < nbds_max; i++) {

		struct gendisk *disk = nbd_dev[i].disk;

		nbd_dev[i].magic = NBD_MAGIC;

		spin_lock_init(&nbd_dev[i].sock_lock);

		mutex_init(&nbd_dev[i].tx_lock);

		mutex_init(&nbd_dev[i].config_lock);

		disk->major = NBD_MAJOR;

		disk->first_minor = i << part_shift;

		disk->fops = &nbd_fops;

		disk->private_data = &nbd_dev[i];

		sprintf(disk->disk_name, "nbd%d", i);

		init_waitqueue_head(&nbd_dev[i].recv_wq);

		nbd_reset(&nbd_dev[i]);

		add_disk(disk);

	}

include/uapi/linux/nbd.h

+5 −4
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ enum { 
#define NBD_FLAG_SEND_FLUSH	(1 << 2) /* can flush writeback cache */

/* there is a gap here to match userspace */

#define NBD_FLAG_SEND_TRIM	(1 << 5) /* send trim/discard */

#define NBD_FLAG_CAN_MULTI_CONN	(1 << 7)	/* Server supports multiple connections per export. */



/* userspace doesn't need the nbd_device structure */