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nbd: add multi-connection support

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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: Josef Bacik <jbacik@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Josef Bacik 2016-11-22 14:04:40 -05:00 committed by Jens Axboe
parent e00f4f4d0f
commit 9561a7ade0
2 changed files with 244 additions and 149 deletions
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378
drivers/block/nbd.c
View File

@ -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;
int i;
spin_lock(&nbd->sock_lock);
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;
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);
}
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);
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);
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");
set_bit(NBD_TIMEDOUT, &nbd->runtime_flags);
req->errors++;
/*
* 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 (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 (rq_data_dir(req) == WRITE &&
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);
}

1
include/uapi/linux/nbd.h
View File

@ -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 */