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e9e006f5fc
linux/drivers/block/nbd.c
Mike Christie e9e006f5fc nbd: fix max number of supported devs 
This fixes a bug added in 4.10 with commit:

commit 9561a7ade0
Author: Josef Bacik <jbacik@fb.com>
Date:   Tue Nov 22 14:04:40 2016 -0500

    nbd: add multi-connection support

that limited the number of devices to 256. Before the patch we could
create 1000s of devices, but the patch switched us from using our
own thread to using a work queue which has a default limit of 256
active works.

The problem is that our recv_work function sits in a loop until
disconnection but only handles IO for one connection. The work is
started when the connection is started/restarted, but if we end up
creating 257 or more connections, the queue_work call just queues
connection257+'s recv_work and that waits for connection 1 - 256's
recv_work to be disconnected and that work instance completing.

Instead of reverting back to kthreads, this has us allocate a
workqueue_struct per device, so we can block in the work.

Cc: stable@vger.kernel.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-08-20 12:44:07 -06:00

2366 lines
58 KiB
C
Raw Blame History

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Network block device - make block devices work over TCP
*
* Note that you can not swap over this thing, yet. Seems to work but
* deadlocks sometimes - you can not swap over TCP in general.
*
* Copyright 1997-2000, 2008 Pavel Machek <pavel@ucw.cz>
* Parts copyright 2001 Steven Whitehouse <steve@chygwyn.com>
*
* (part of code stolen from loop.c)
*/
#include <linux/major.h>
#include <linux/blkdev.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/sched/mm.h>
#include <linux/fs.h>
#include <linux/bio.h>
#include <linux/stat.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/ioctl.h>
#include <linux/mutex.h>
#include <linux/compiler.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <net/sock.h>
#include <linux/net.h>
#include <linux/kthread.h>
#include <linux/types.h>
#include <linux/debugfs.h>
#include <linux/blk-mq.h>
#include <linux/uaccess.h>
#include <asm/types.h>
#include <linux/nbd.h>
#include <linux/nbd-netlink.h>
#include <net/genetlink.h>
#define CREATE_TRACE_POINTS
#include <trace/events/nbd.h>
static DEFINE_IDR(nbd_index_idr);
static DEFINE_MUTEX(nbd_index_mutex);
static int nbd_total_devices = 0;
struct nbd_sock {
struct socket *sock;
struct mutex tx_lock;
struct request *pending;
int sent;
bool dead;
int fallback_index;
int cookie;
};
struct recv_thread_args {
struct work_struct work;
struct nbd_device *nbd;
int index;
};
struct link_dead_args {
struct work_struct work;
int index;
};
#define NBD_TIMEDOUT 0
#define NBD_DISCONNECT_REQUESTED 1
#define NBD_DISCONNECTED 2
#define NBD_HAS_PID_FILE 3
#define NBD_HAS_CONFIG_REF 4
#define NBD_BOUND 5
#define NBD_DESTROY_ON_DISCONNECT 6
#define NBD_DISCONNECT_ON_CLOSE 7
struct nbd_config {
u32 flags;
unsigned long runtime_flags;
u64 dead_conn_timeout;
struct nbd_sock **socks;
int num_connections;
atomic_t live_connections;
wait_queue_head_t conn_wait;
atomic_t recv_threads;
wait_queue_head_t recv_wq;
loff_t blksize;
loff_t bytesize;
#if IS_ENABLED(CONFIG_DEBUG_FS)
struct dentry *dbg_dir;
#endif
};
struct nbd_device {
struct blk_mq_tag_set tag_set;
int index;
refcount_t config_refs;
refcount_t refs;
struct nbd_config *config;
struct mutex config_lock;
struct gendisk *disk;
struct workqueue_struct *recv_workq;
struct list_head list;
struct task_struct *task_recv;
struct task_struct *task_setup;
};
#define NBD_CMD_REQUEUED 1
struct nbd_cmd {
struct nbd_device *nbd;
struct mutex lock;
int index;
int cookie;
int retries;
blk_status_t status;
unsigned long flags;
u32 cmd_cookie;
};
#if IS_ENABLED(CONFIG_DEBUG_FS)
static struct dentry *nbd_dbg_dir;
#endif
#define nbd_name(nbd) ((nbd)->disk->disk_name)
#define NBD_MAGIC 0x68797548
#define NBD_DEF_BLKSIZE 1024
static unsigned int nbds_max = 16;
static int max_part = 16;
static int part_shift;
static int nbd_dev_dbg_init(struct nbd_device *nbd);
static void nbd_dev_dbg_close(struct nbd_device *nbd);
static void nbd_config_put(struct nbd_device *nbd);
static void nbd_connect_reply(struct genl_info *info, int index);
static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info);
static void nbd_dead_link_work(struct work_struct *work);
static void nbd_disconnect_and_put(struct nbd_device *nbd);
static inline struct device *nbd_to_dev(struct nbd_device *nbd)
{
return disk_to_dev(nbd->disk);
}
static void nbd_requeue_cmd(struct nbd_cmd *cmd)
{
struct request *req = blk_mq_rq_from_pdu(cmd);
if (!test_and_set_bit(NBD_CMD_REQUEUED, &cmd->flags))
blk_mq_requeue_request(req, true);
}
#define NBD_COOKIE_BITS 32
static u64 nbd_cmd_handle(struct nbd_cmd *cmd)
{
struct request *req = blk_mq_rq_from_pdu(cmd);
u32 tag = blk_mq_unique_tag(req);
u64 cookie = cmd->cmd_cookie;
return (cookie << NBD_COOKIE_BITS) | tag;
}
static u32 nbd_handle_to_tag(u64 handle)
{
return (u32)handle;
}
static u32 nbd_handle_to_cookie(u64 handle)
{
return (u32)(handle >> NBD_COOKIE_BITS);
}
static const char *nbdcmd_to_ascii(int cmd)
{
switch (cmd) {
case NBD_CMD_READ: return "read";
case NBD_CMD_WRITE: return "write";
case NBD_CMD_DISC: return "disconnect";
case NBD_CMD_FLUSH: return "flush";
case NBD_CMD_TRIM: return "trim/discard";
}
return "invalid";
}
static ssize_t pid_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
struct nbd_device *nbd = (struct nbd_device *)disk->private_data;
return sprintf(buf, "%d\n", task_pid_nr(nbd->task_recv));
}
static const struct device_attribute pid_attr = {
.attr = { .name = "pid", .mode = 0444},
.show = pid_show,
};
static void nbd_dev_remove(struct nbd_device *nbd)
{
struct gendisk *disk = nbd->disk;
struct request_queue *q;
if (disk) {
q = disk->queue;
del_gendisk(disk);
blk_cleanup_queue(q);
blk_mq_free_tag_set(&nbd->tag_set);
disk->private_data = NULL;
put_disk(disk);
}
kfree(nbd);
}
static void nbd_put(struct nbd_device *nbd)
{
if (refcount_dec_and_mutex_lock(&nbd->refs,
&nbd_index_mutex)) {
idr_remove(&nbd_index_idr, nbd->index);
mutex_unlock(&nbd_index_mutex);
nbd_dev_remove(nbd);
}
}
static int nbd_disconnected(struct nbd_config *config)
{
return test_bit(NBD_DISCONNECTED, &config->runtime_flags) ||
test_bit(NBD_DISCONNECT_REQUESTED, &config->runtime_flags);
}
static void nbd_mark_nsock_dead(struct nbd_device *nbd, struct nbd_sock *nsock,
int notify)
{
if (!nsock->dead && notify && !nbd_disconnected(nbd->config)) {
struct link_dead_args *args;
args = kmalloc(sizeof(struct link_dead_args), GFP_NOIO);
if (args) {
INIT_WORK(&args->work, nbd_dead_link_work);
args->index = nbd->index;
queue_work(system_wq, &args->work);
}
}
if (!nsock->dead) {
kernel_sock_shutdown(nsock->sock, SHUT_RDWR);
if (atomic_dec_return(&nbd->config->live_connections) == 0) {
if (test_and_clear_bit(NBD_DISCONNECT_REQUESTED,
&nbd->config->runtime_flags)) {
set_bit(NBD_DISCONNECTED,
&nbd->config->runtime_flags);
dev_info(nbd_to_dev(nbd),
"Disconnected due to user request.\n");
}
}
}
nsock->dead = true;
nsock->pending = NULL;
nsock->sent = 0;
}
static void nbd_size_clear(struct nbd_device *nbd)
{
if (nbd->config->bytesize) {
set_capacity(nbd->disk, 0);
kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
}
}
static void nbd_size_update(struct nbd_device *nbd)
{
struct nbd_config *config = nbd->config;
struct block_device *bdev = bdget_disk(nbd->disk, 0);
if (config->flags & NBD_FLAG_SEND_TRIM) {
nbd->disk->queue->limits.discard_granularity = config->blksize;
nbd->disk->queue->limits.discard_alignment = config->blksize;
blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
}
blk_queue_logical_block_size(nbd->disk->queue, config->blksize);
blk_queue_physical_block_size(nbd->disk->queue, config->blksize);
set_capacity(nbd->disk, config->bytesize >> 9);
if (bdev) {
if (bdev->bd_disk) {
bd_set_size(bdev, config->bytesize);
set_blocksize(bdev, config->blksize);
} else
bdev->bd_invalidated = 1;
bdput(bdev);
}
kobject_uevent(&nbd_to_dev(nbd)->kobj, KOBJ_CHANGE);
}
static void nbd_size_set(struct nbd_device *nbd, loff_t blocksize,
loff_t nr_blocks)
{
struct nbd_config *config = nbd->config;
config->blksize = blocksize;
config->bytesize = blocksize * nr_blocks;
if (nbd->task_recv != NULL)
nbd_size_update(nbd);
}
static void nbd_complete_rq(struct request *req)
{
struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
dev_dbg(nbd_to_dev(cmd->nbd), "request %p: %s\n", req,
cmd->status ? "failed" : "done");
blk_mq_end_request(req, cmd->status);
}
/*
* Forcibly shutdown the socket causing all listeners to error
*/
static void sock_shutdown(struct nbd_device *nbd)
{
struct nbd_config *config = nbd->config;
int i;
if (config->num_connections == 0)
return;
if (test_and_set_bit(NBD_DISCONNECTED, &config->runtime_flags))
return;
for (i = 0; i < config->num_connections; i++) {
struct nbd_sock *nsock = config->socks[i];
mutex_lock(&nsock->tx_lock);
nbd_mark_nsock_dead(nbd, nsock, 0);
mutex_unlock(&nsock->tx_lock);
}
dev_warn(disk_to_dev(nbd->disk), "shutting down sockets\n");
}
static u32 req_to_nbd_cmd_type(struct request *req)
{
switch (req_op(req)) {
case REQ_OP_DISCARD:
return NBD_CMD_TRIM;
case REQ_OP_FLUSH:
return NBD_CMD_FLUSH;
case REQ_OP_WRITE:
return NBD_CMD_WRITE;
case REQ_OP_READ:
return NBD_CMD_READ;
default:
return U32_MAX;
}
}
static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req,
bool reserved)
{
struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
struct nbd_device *nbd = cmd->nbd;
struct nbd_config *config;
if (!refcount_inc_not_zero(&nbd->config_refs)) {
cmd->status = BLK_STS_TIMEOUT;
goto done;
}
config = nbd->config;
if (!mutex_trylock(&cmd->lock)) {
nbd_config_put(nbd);
return BLK_EH_RESET_TIMER;
}
if (config->num_connections > 1) {
dev_err_ratelimited(nbd_to_dev(nbd),
"Connection timed out, retrying (%d/%d alive)\n",
atomic_read(&config->live_connections),
config->num_connections);
/*
* Hooray we have more connections, requeue this IO, the submit
* path will put it on a real connection.
*/
if (config->socks && config->num_connections > 1) {
if (cmd->index < config->num_connections) {
struct nbd_sock *nsock =
config->socks[cmd->index];
mutex_lock(&nsock->tx_lock);
/* We can have multiple outstanding requests, so
* we don't want to mark the nsock dead if we've
* already reconnected with a new socket, so
* only mark it dead if its the same socket we
* were sent out on.
*/
if (cmd->cookie == nsock->cookie)
nbd_mark_nsock_dead(nbd, nsock, 1);
mutex_unlock(&nsock->tx_lock);
}
mutex_unlock(&cmd->lock);
nbd_requeue_cmd(cmd);
nbd_config_put(nbd);
return BLK_EH_DONE;
}
}
if (!nbd->tag_set.timeout) {
/*
* Userspace sets timeout=0 to disable socket disconnection,
* so just warn and reset the timer.
*/
cmd->retries++;
dev_info(nbd_to_dev(nbd), "Possible stuck request %p: control (%s@%llu,%uB). Runtime %u seconds\n",
req, nbdcmd_to_ascii(req_to_nbd_cmd_type(req)),
(unsigned long long)blk_rq_pos(req) << 9,
blk_rq_bytes(req), (req->timeout / HZ) * cmd->retries);
mutex_unlock(&cmd->lock);
nbd_config_put(nbd);
return BLK_EH_RESET_TIMER;
}
dev_err_ratelimited(nbd_to_dev(nbd), "Connection timed out\n");
set_bit(NBD_TIMEDOUT, &config->runtime_flags);
cmd->status = BLK_STS_IOERR;
mutex_unlock(&cmd->lock);
sock_shutdown(nbd);
nbd_config_put(nbd);
done:
blk_mq_complete_request(req);
return BLK_EH_DONE;
}
/*
* Send or receive packet.
*/
static int sock_xmit(struct nbd_device *nbd, int index, int send,
struct iov_iter *iter, int msg_flags, int *sent)
{
struct nbd_config *config = nbd->config;
struct socket *sock = config->socks[index]->sock;
int result;
struct msghdr msg;
unsigned int noreclaim_flag;
if (unlikely(!sock)) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Attempted %s on closed socket in sock_xmit\n",
(send ? "send" : "recv"));
return -EINVAL;
}
msg.msg_iter = *iter;
noreclaim_flag = memalloc_noreclaim_save();
do {
sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_control = NULL;
msg.msg_controllen = 0;
msg.msg_flags = msg_flags | MSG_NOSIGNAL;
if (send)
result = sock_sendmsg(sock, &msg);
else
result = sock_recvmsg(sock, &msg, msg.msg_flags);
if (result <= 0) {
if (result == 0)
result = -EPIPE; /* short read */
break;
}
if (sent)
*sent += result;
} while (msg_data_left(&msg));
memalloc_noreclaim_restore(noreclaim_flag);
return result;
}
/*
* Different settings for sk->sk_sndtimeo can result in different return values
* if there is a signal pending when we enter sendmsg, because reasons?
*/
static inline int was_interrupted(int result)
{
return result == -ERESTARTSYS || result == -EINTR;
}
/* always call with the tx_lock held */
static int nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd, int index)
{
struct request *req = blk_mq_rq_from_pdu(cmd);
struct nbd_config *config = nbd->config;
struct nbd_sock *nsock = config->socks[index];
int result;
struct nbd_request request = {.magic = htonl(NBD_REQUEST_MAGIC)};
struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
struct iov_iter from;
unsigned long size = blk_rq_bytes(req);
struct bio *bio;
u64 handle;
u32 type;
u32 nbd_cmd_flags = 0;
int sent = nsock->sent, skip = 0;
iov_iter_kvec(&from, WRITE, &iov, 1, sizeof(request));
type = req_to_nbd_cmd_type(req);
if (type == U32_MAX)
return -EIO;
if (rq_data_dir(req) == WRITE &&
(config->flags & NBD_FLAG_READ_ONLY)) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Write on read-only\n");
return -EIO;
}
if (req->cmd_flags & REQ_FUA)
nbd_cmd_flags |= NBD_CMD_FLAG_FUA;
/* We did a partial send previously, and we at least sent the whole
* request struct, so just go and send the rest of the pages in the
* request.
*/
if (sent) {
if (sent >= sizeof(request)) {
skip = sent - sizeof(request);
/* initialize handle for tracing purposes */
handle = nbd_cmd_handle(cmd);
goto send_pages;
}
iov_iter_advance(&from, sent);
} else {
cmd->cmd_cookie++;
}
cmd->index = index;
cmd->cookie = nsock->cookie;
cmd->retries = 0;
request.type = htonl(type | nbd_cmd_flags);
if (type != NBD_CMD_FLUSH) {
request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
request.len = htonl(size);
}
handle = nbd_cmd_handle(cmd);
memcpy(request.handle, &handle, sizeof(handle));
trace_nbd_send_request(&request, nbd->index, blk_mq_rq_from_pdu(cmd));
dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n",
req, nbdcmd_to_ascii(type),
(unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req));
result = sock_xmit(nbd, index, 1, &from,
(type == NBD_CMD_WRITE) ? MSG_MORE : 0, &sent);
trace_nbd_header_sent(req, handle);
if (result <= 0) {
if (was_interrupted(result)) {
/* If we havne't sent anything we can just return BUSY,
* however if we have sent something we need to make
* sure we only allow this req to be sent until we are
* completely done.
*/
if (sent) {
nsock->pending = req;
nsock->sent = sent;
}
set_bit(NBD_CMD_REQUEUED, &cmd->flags);
return BLK_STS_RESOURCE;
}
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Send control failed (result %d)\n", result);
return -EAGAIN;
}
send_pages:
if (type != NBD_CMD_WRITE)
goto out;
bio = req->bio;
while (bio) {
struct bio *next = bio->bi_next;
struct bvec_iter iter;
struct bio_vec bvec;
bio_for_each_segment(bvec, bio, iter) {
bool is_last = !next && bio_iter_last(bvec, iter);
int flags = is_last ? 0 : MSG_MORE;
dev_dbg(nbd_to_dev(nbd), "request %p: sending %d bytes data\n",
req, bvec.bv_len);
iov_iter_bvec(&from, WRITE, &bvec, 1, bvec.bv_len);
if (skip) {
if (skip >= iov_iter_count(&from)) {
skip -= iov_iter_count(&from);
continue;
}
iov_iter_advance(&from, skip);
skip = 0;
}
result = sock_xmit(nbd, index, 1, &from, flags, &sent);
if (result <= 0) {
if (was_interrupted(result)) {
/* We've already sent the header, we
* have no choice but to set pending and
* return BUSY.
*/
nsock->pending = req;
nsock->sent = sent;
set_bit(NBD_CMD_REQUEUED, &cmd->flags);
return BLK_STS_RESOURCE;
}
dev_err(disk_to_dev(nbd->disk),
"Send data failed (result %d)\n",
result);
return -EAGAIN;
}
/*
* The completion might already have come in,
* so break for the last one instead of letting
* the iterator do it. This prevents use-after-free
* of the bio.
*/
if (is_last)
break;
}
bio = next;
}
out:
trace_nbd_payload_sent(req, handle);
nsock->pending = NULL;
nsock->sent = 0;
return 0;
}
/* NULL returned = something went wrong, inform userspace */
static struct nbd_cmd *nbd_read_stat(struct nbd_device *nbd, int index)
{
struct nbd_config *config = nbd->config;
int result;
struct nbd_reply reply;
struct nbd_cmd *cmd;
struct request *req = NULL;
u64 handle;
u16 hwq;
u32 tag;
struct kvec iov = {.iov_base = &reply, .iov_len = sizeof(reply)};
struct iov_iter to;
int ret = 0;
reply.magic = 0;
iov_iter_kvec(&to, READ, &iov, 1, sizeof(reply));
result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
if (result <= 0) {
if (!nbd_disconnected(config))
dev_err(disk_to_dev(nbd->disk),
"Receive control failed (result %d)\n", result);
return ERR_PTR(result);
}
if (ntohl(reply.magic) != NBD_REPLY_MAGIC) {
dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n",
(unsigned long)ntohl(reply.magic));
return ERR_PTR(-EPROTO);
}
memcpy(&handle, reply.handle, sizeof(handle));
tag = nbd_handle_to_tag(handle);
hwq = blk_mq_unique_tag_to_hwq(tag);
if (hwq < nbd->tag_set.nr_hw_queues)
req = blk_mq_tag_to_rq(nbd->tag_set.tags[hwq],
blk_mq_unique_tag_to_tag(tag));
if (!req || !blk_mq_request_started(req)) {
dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%d) %p\n",
tag, req);
return ERR_PTR(-ENOENT);
}
trace_nbd_header_received(req, handle);
cmd = blk_mq_rq_to_pdu(req);
mutex_lock(&cmd->lock);
if (cmd->cmd_cookie != nbd_handle_to_cookie(handle)) {
dev_err(disk_to_dev(nbd->disk), "Double reply on req %p, cmd_cookie %u, handle cookie %u\n",
req, cmd->cmd_cookie, nbd_handle_to_cookie(handle));
ret = -ENOENT;
goto out;
}
if (test_bit(NBD_CMD_REQUEUED, &cmd->flags)) {
dev_err(disk_to_dev(nbd->disk), "Raced with timeout on req %p\n",
req);
ret = -ENOENT;
goto out;
}
if (ntohl(reply.error)) {
dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n",
ntohl(reply.error));
cmd->status = BLK_STS_IOERR;
goto out;
}
dev_dbg(nbd_to_dev(nbd), "request %p: got reply\n", req);
if (rq_data_dir(req) != WRITE) {
struct req_iterator iter;
struct bio_vec bvec;
rq_for_each_segment(bvec, req, iter) {
iov_iter_bvec(&to, READ, &bvec, 1, bvec.bv_len);
result = sock_xmit(nbd, index, 0, &to, MSG_WAITALL, NULL);
if (result <= 0) {
dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
result);
/*
* If we've disconnected or we only have 1
* connection then we need to make sure we
* complete this request, otherwise error out
* and let the timeout stuff handle resubmitting
* this request onto another connection.
*/
if (nbd_disconnected(config) ||
config->num_connections <= 1) {
cmd->status = BLK_STS_IOERR;
goto out;
}
ret = -EIO;
goto out;
}
dev_dbg(nbd_to_dev(nbd), "request %p: got %d bytes data\n",
req, bvec.bv_len);
}
}
out:
trace_nbd_payload_received(req, handle);
mutex_unlock(&cmd->lock);
return ret ? ERR_PTR(ret) : cmd;
}
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_config *config = nbd->config;
struct nbd_cmd *cmd;
while (1) {
cmd = nbd_read_stat(nbd, args->index);
if (IS_ERR(cmd)) {
struct nbd_sock *nsock = config->socks[args->index];
mutex_lock(&nsock->tx_lock);
nbd_mark_nsock_dead(nbd, nsock, 1);
mutex_unlock(&nsock->tx_lock);
break;
}
blk_mq_complete_request(blk_mq_rq_from_pdu(cmd));
}
atomic_dec(&config->recv_threads);
wake_up(&config->recv_wq);
nbd_config_put(nbd);
kfree(args);
}
static bool nbd_clear_req(struct request *req, void *data, bool reserved)
{
struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);
cmd->status = BLK_STS_IOERR;
blk_mq_complete_request(req);
return true;
}
static void nbd_clear_que(struct nbd_device *nbd)
{
blk_mq_quiesce_queue(nbd->disk->queue);
blk_mq_tagset_busy_iter(&nbd->tag_set, nbd_clear_req, NULL);
blk_mq_unquiesce_queue(nbd->disk->queue);
dev_dbg(disk_to_dev(nbd->disk), "queue cleared\n");
}
static int find_fallback(struct nbd_device *nbd, int index)
{
struct nbd_config *config = nbd->config;
int new_index = -1;
struct nbd_sock *nsock = config->socks[index];
int fallback = nsock->fallback_index;
if (test_bit(NBD_DISCONNECTED, &config->runtime_flags))
return new_index;
if (config->num_connections <= 1) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Attempted send on invalid socket\n");
return new_index;
}
if (fallback >= 0 && fallback < config->num_connections &&
!config->socks[fallback]->dead)
return fallback;
if (nsock->fallback_index < 0 ||
nsock->fallback_index >= config->num_connections ||
config->socks[nsock->fallback_index]->dead) {
int i;
for (i = 0; i < config->num_connections; i++) {
if (i == index)
continue;
if (!config->socks[i]->dead) {
new_index = i;
break;
}
}
nsock->fallback_index = new_index;
if (new_index < 0) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Dead connection, failed to find a fallback\n");
return new_index;
}
}
new_index = nsock->fallback_index;
return new_index;
}
static int wait_for_reconnect(struct nbd_device *nbd)
{
struct nbd_config *config = nbd->config;
if (!config->dead_conn_timeout)
return 0;
if (test_bit(NBD_DISCONNECTED, &config->runtime_flags))
return 0;
return wait_event_timeout(config->conn_wait,
atomic_read(&config->live_connections) > 0,
config->dead_conn_timeout) > 0;
}
static int 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_config *config;
struct nbd_sock *nsock;
int ret;
if (!refcount_inc_not_zero(&nbd->config_refs)) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Socks array is empty\n");
blk_mq_start_request(req);
return -EINVAL;
}
config = nbd->config;
if (index >= config->num_connections) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Attempted send on invalid socket\n");
nbd_config_put(nbd);
blk_mq_start_request(req);
return -EINVAL;
}
cmd->status = BLK_STS_OK;
again:
nsock = config->socks[index];
mutex_lock(&nsock->tx_lock);
if (nsock->dead) {
int old_index = index;
index = find_fallback(nbd, index);
mutex_unlock(&nsock->tx_lock);
if (index < 0) {
if (wait_for_reconnect(nbd)) {
index = old_index;
goto again;
}
/* All the sockets should already be down at this point,
* we just want to make sure that DISCONNECTED is set so
* any requests that come in that were queue'ed waiting
* for the reconnect timer don't trigger the timer again
* and instead just error out.
*/
sock_shutdown(nbd);
nbd_config_put(nbd);
blk_mq_start_request(req);
return -EIO;
}
goto again;
}
/* Handle the case that we have a pending request that was partially
* transmitted that _has_ to be serviced first. We need to call requeue
* here so that it gets put _after_ the request that is already on the
* dispatch list.
*/
blk_mq_start_request(req);
if (unlikely(nsock->pending && nsock->pending != req)) {
nbd_requeue_cmd(cmd);
ret = 0;
goto out;
}
/*
* Some failures are related to the link going down, so anything that
* returns EAGAIN can be retried on a different socket.
*/
ret = nbd_send_cmd(nbd, cmd, index);
if (ret == -EAGAIN) {
dev_err_ratelimited(disk_to_dev(nbd->disk),
"Request send failed, requeueing\n");
nbd_mark_nsock_dead(nbd, nsock, 1);
nbd_requeue_cmd(cmd);
ret = 0;
}
out:
mutex_unlock(&nsock->tx_lock);
nbd_config_put(nbd);
return ret;
}
static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx,
const struct blk_mq_queue_data *bd)
{
struct nbd_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
int ret;
/*
* 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.
*/
mutex_lock(&cmd->lock);
clear_bit(NBD_CMD_REQUEUED, &cmd->flags);
/* We can be called directly from the user space process, which means we
* could possibly have signals pending so our sendmsg will fail. In
* this case we need to return that we are busy, otherwise error out as
* appropriate.
*/
ret = nbd_handle_cmd(cmd, hctx->queue_num);
if (ret < 0)
ret = BLK_STS_IOERR;
else if (!ret)
ret = BLK_STS_OK;
mutex_unlock(&cmd->lock);
return ret;
}
static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
bool netlink)
{
struct nbd_config *config = nbd->config;
struct socket *sock;
struct nbd_sock **socks;
struct nbd_sock *nsock;
int err;
sock = sockfd_lookup(arg, &err);
if (!sock)
return err;
if (!netlink && !nbd->task_setup &&
!test_bit(NBD_BOUND, &config->runtime_flags))
nbd->task_setup = current;
if (!netlink &&
(nbd->task_setup != current ||
test_bit(NBD_BOUND, &config->runtime_flags))) {
dev_err(disk_to_dev(nbd->disk),
"Device being setup by another task");
sockfd_put(sock);
return -EBUSY;
}
socks = krealloc(config->socks, (config->num_connections + 1) *
sizeof(struct nbd_sock *), GFP_KERNEL);
if (!socks) {
sockfd_put(sock);
return -ENOMEM;
}
nsock = kzalloc(sizeof(struct nbd_sock), GFP_KERNEL);
if (!nsock) {
sockfd_put(sock);
return -ENOMEM;
}
config->socks = socks;
nsock->fallback_index = -1;
nsock->dead = false;
mutex_init(&nsock->tx_lock);
nsock->sock = sock;
nsock->pending = NULL;
nsock->sent = 0;
nsock->cookie = 0;
socks[config->num_connections++] = nsock;
atomic_inc(&config->live_connections);
return 0;
}
static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg)
{
struct nbd_config *config = nbd->config;
struct socket *sock, *old;
struct recv_thread_args *args;
int i;
int err;
sock = sockfd_lookup(arg, &err);
if (!sock)
return err;
args = kzalloc(sizeof(*args), GFP_KERNEL);
if (!args) {
sockfd_put(sock);
return -ENOMEM;
}
for (i = 0; i < config->num_connections; i++) {
struct nbd_sock *nsock = config->socks[i];
if (!nsock->dead)
continue;
mutex_lock(&nsock->tx_lock);
if (!nsock->dead) {
mutex_unlock(&nsock->tx_lock);
continue;
}
sk_set_memalloc(sock->sk);
if (nbd->tag_set.timeout)
sock->sk->sk_sndtimeo = nbd->tag_set.timeout;
atomic_inc(&config->recv_threads);
refcount_inc(&nbd->config_refs);
old = nsock->sock;
nsock->fallback_index = -1;
nsock->sock = sock;
nsock->dead = false;
INIT_WORK(&args->work, recv_work);
args->index = i;
args->nbd = nbd;
nsock->cookie++;
mutex_unlock(&nsock->tx_lock);
sockfd_put(old);
clear_bit(NBD_DISCONNECTED, &config->runtime_flags);
/* We take the tx_mutex in an error path in the recv_work, so we
* need to queue_work outside of the tx_mutex.
*/
queue_work(nbd->recv_workq, &args->work);
atomic_inc(&config->live_connections);
wake_up(&config->conn_wait);
return 0;
}
sockfd_put(sock);
kfree(args);
return -ENOSPC;
}
static void nbd_bdev_reset(struct block_device *bdev)
{
if (bdev->bd_openers > 1)
return;
bd_set_size(bdev, 0);
}
static void nbd_parse_flags(struct nbd_device *nbd)
{
struct nbd_config *config = nbd->config;
if (config->flags & NBD_FLAG_READ_ONLY)
set_disk_ro(nbd->disk, true);
else
set_disk_ro(nbd->disk, false);
if (config->flags & NBD_FLAG_SEND_TRIM)
blk_queue_flag_set(QUEUE_FLAG_DISCARD, nbd->disk->queue);
if (config->flags & NBD_FLAG_SEND_FLUSH) {
if (config->flags & NBD_FLAG_SEND_FUA)
blk_queue_write_cache(nbd->disk->queue, true, true);
else
blk_queue_write_cache(nbd->disk->queue, true, false);
}
else
blk_queue_write_cache(nbd->disk->queue, false, false);
}
static void send_disconnects(struct nbd_device *nbd)
{
struct nbd_config *config = nbd->config;
struct nbd_request request = {
.magic = htonl(NBD_REQUEST_MAGIC),
.type = htonl(NBD_CMD_DISC),
};
struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
struct iov_iter from;
int i, ret;
for (i = 0; i < config->num_connections; i++) {
struct nbd_sock *nsock = config->socks[i];
iov_iter_kvec(&from, WRITE, &iov, 1, sizeof(request));
mutex_lock(&nsock->tx_lock);
ret = sock_xmit(nbd, i, 1, &from, 0, NULL);
if (ret <= 0)
dev_err(disk_to_dev(nbd->disk),
"Send disconnect failed %d\n", ret);
mutex_unlock(&nsock->tx_lock);
}
}
static int nbd_disconnect(struct nbd_device *nbd)
{
struct nbd_config *config = nbd->config;
dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n");
set_bit(NBD_DISCONNECT_REQUESTED, &config->runtime_flags);
send_disconnects(nbd);
return 0;
}
static void nbd_clear_sock(struct nbd_device *nbd)
{
sock_shutdown(nbd);
nbd_clear_que(nbd);
nbd->task_setup = NULL;
}
static void nbd_config_put(struct nbd_device *nbd)
{
if (refcount_dec_and_mutex_lock(&nbd->config_refs,
&nbd->config_lock)) {
struct nbd_config *config = nbd->config;
nbd_dev_dbg_close(nbd);
nbd_size_clear(nbd);
if (test_and_clear_bit(NBD_HAS_PID_FILE,
&config->runtime_flags))
device_remove_file(disk_to_dev(nbd->disk), &pid_attr);
nbd->task_recv = NULL;
nbd_clear_sock(nbd);
if (config->num_connections) {
int i;
for (i = 0; i < config->num_connections; i++) {
sockfd_put(config->socks[i]->sock);
kfree(config->socks[i]);
}
kfree(config->socks);
}
kfree(nbd->config);
nbd->config = NULL;
if (nbd->recv_workq)
destroy_workqueue(nbd->recv_workq);
nbd->recv_workq = NULL;
nbd->tag_set.timeout = 0;
nbd->disk->queue->limits.discard_granularity = 0;
nbd->disk->queue->limits.discard_alignment = 0;
blk_queue_max_discard_sectors(nbd->disk->queue, UINT_MAX);
blk_queue_flag_clear(QUEUE_FLAG_DISCARD, nbd->disk->queue);
mutex_unlock(&nbd->config_lock);
nbd_put(nbd);
module_put(THIS_MODULE);
}
}
static int nbd_start_device(struct nbd_device *nbd)
{
struct nbd_config *config = nbd->config;
int num_connections = config->num_connections;
int error = 0, i;
if (nbd->task_recv)
return -EBUSY;
if (!config->socks)
return -EINVAL;
if (num_connections > 1 &&
!(config->flags & NBD_FLAG_CAN_MULTI_CONN)) {
dev_err(disk_to_dev(nbd->disk), "server does not support multiple connections per device.\n");
return -EINVAL;
}
nbd->recv_workq = alloc_workqueue("knbd%d-recv",
WQ_MEM_RECLAIM | WQ_HIGHPRI |
WQ_UNBOUND, 0, nbd->index);
if (!nbd->recv_workq) {
dev_err(disk_to_dev(nbd->disk), "Could not allocate knbd recv work queue.\n");
return -ENOMEM;
}
blk_mq_update_nr_hw_queues(&nbd->tag_set, config->num_connections);
nbd->task_recv = current;
nbd_parse_flags(nbd);
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");
return error;
}
set_bit(NBD_HAS_PID_FILE, &config->runtime_flags);
nbd_dev_dbg_init(nbd);
for (i = 0; i < num_connections; i++) {
struct recv_thread_args *args;
args = kzalloc(sizeof(*args), GFP_KERNEL);
if (!args) {
sock_shutdown(nbd);
return -ENOMEM;
}
sk_set_memalloc(config->socks[i]->sock->sk);
if (nbd->tag_set.timeout)
config->socks[i]->sock->sk->sk_sndtimeo =
nbd->tag_set.timeout;
atomic_inc(&config->recv_threads);
refcount_inc(&nbd->config_refs);
INIT_WORK(&args->work, recv_work);
args->nbd = nbd;
args->index = i;
queue_work(nbd->recv_workq, &args->work);
}
nbd_size_update(nbd);
return error;
}
static int nbd_start_device_ioctl(struct nbd_device *nbd, struct block_device *bdev)
{
struct nbd_config *config = nbd->config;
int ret;
ret = nbd_start_device(nbd);
if (ret)
return ret;
if (max_part)
bdev->bd_invalidated = 1;
mutex_unlock(&nbd->config_lock);
ret = wait_event_interruptible(config->recv_wq,
atomic_read(&config->recv_threads) == 0);
if (ret) {
sock_shutdown(nbd);
flush_workqueue(nbd->recv_workq);
}
mutex_lock(&nbd->config_lock);
nbd_bdev_reset(bdev);
/* user requested, ignore socket errors */
if (test_bit(NBD_DISCONNECT_REQUESTED, &config->runtime_flags))
ret = 0;
if (test_bit(NBD_TIMEDOUT, &config->runtime_flags))
ret = -ETIMEDOUT;
return ret;
}
static void nbd_clear_sock_ioctl(struct nbd_device *nbd,
struct block_device *bdev)
{
sock_shutdown(nbd);
__invalidate_device(bdev, true);
nbd_bdev_reset(bdev);
if (test_and_clear_bit(NBD_HAS_CONFIG_REF,
&nbd->config->runtime_flags))
nbd_config_put(nbd);
}
static bool nbd_is_valid_blksize(unsigned long blksize)
{
if (!blksize || !is_power_of_2(blksize) || blksize < 512 ||
blksize > PAGE_SIZE)
return false;
return true;
}
static void nbd_set_cmd_timeout(struct nbd_device *nbd, u64 timeout)
{
nbd->tag_set.timeout = timeout * HZ;
if (timeout)
blk_queue_rq_timeout(nbd->disk->queue, timeout * HZ);
}
/* 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)
{
struct nbd_config *config = nbd->config;
switch (cmd) {
case NBD_DISCONNECT:
return nbd_disconnect(nbd);
case NBD_CLEAR_SOCK:
nbd_clear_sock_ioctl(nbd, bdev);
return 0;
case NBD_SET_SOCK:
return nbd_add_socket(nbd, arg, false);
case NBD_SET_BLKSIZE:
if (!arg)
arg = NBD_DEF_BLKSIZE;
if (!nbd_is_valid_blksize(arg))
return -EINVAL;
nbd_size_set(nbd, arg,
div_s64(config->bytesize, arg));
return 0;
case NBD_SET_SIZE:
nbd_size_set(nbd, config->blksize,
div_s64(arg, config->blksize));
return 0;
case NBD_SET_SIZE_BLOCKS:
nbd_size_set(nbd, config->blksize, arg);
return 0;
case NBD_SET_TIMEOUT:
nbd_set_cmd_timeout(nbd, arg);
return 0;
case NBD_SET_FLAGS:
config->flags = arg;
return 0;
case NBD_DO_IT:
return nbd_start_device_ioctl(nbd, bdev);
case NBD_CLEAR_QUE:
/*
* This is for compatibility only. The queue is always cleared
* by NBD_DO_IT or NBD_CLEAR_SOCK.
*/
return 0;
case NBD_PRINT_DEBUG:
/*
* For compatibility only, we no longer keep a list of
* outstanding requests.
*/
return 0;
}
return -ENOTTY;
}
static int nbd_ioctl(struct block_device *bdev, fmode_t mode,
unsigned int cmd, unsigned long arg)
{
struct nbd_device *nbd = bdev->bd_disk->private_data;
struct nbd_config *config = nbd->config;
int error = -EINVAL;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
/* The block layer will pass back some non-nbd ioctls in case we have
* special handling for them, but we don't so just return an error.
*/
if (_IOC_TYPE(cmd) != 0xab)
return -EINVAL;
mutex_lock(&nbd->config_lock);
/* Don't allow ioctl operations on a nbd device that was created with
* netlink, unless it's DISCONNECT or CLEAR_SOCK, which are fine.
*/
if (!test_bit(NBD_BOUND, &config->runtime_flags) ||
(cmd == NBD_DISCONNECT || cmd == NBD_CLEAR_SOCK))
error = __nbd_ioctl(bdev, nbd, cmd, arg);
else
dev_err(nbd_to_dev(nbd), "Cannot use ioctl interface on a netlink controlled device.\n");
mutex_unlock(&nbd->config_lock);
return error;
}
static struct nbd_config *nbd_alloc_config(void)
{
struct nbd_config *config;
config = kzalloc(sizeof(struct nbd_config), GFP_NOFS);
if (!config)
return NULL;
atomic_set(&config->recv_threads, 0);
init_waitqueue_head(&config->recv_wq);
init_waitqueue_head(&config->conn_wait);
config->blksize = NBD_DEF_BLKSIZE;
atomic_set(&config->live_connections, 0);
try_module_get(THIS_MODULE);
return config;
}
static int nbd_open(struct block_device *bdev, fmode_t mode)
{
struct nbd_device *nbd;
int ret = 0;
mutex_lock(&nbd_index_mutex);
nbd = bdev->bd_disk->private_data;
if (!nbd) {
ret = -ENXIO;
goto out;
}
if (!refcount_inc_not_zero(&nbd->refs)) {
ret = -ENXIO;
goto out;
}
if (!refcount_inc_not_zero(&nbd->config_refs)) {
struct nbd_config *config;
mutex_lock(&nbd->config_lock);
if (refcount_inc_not_zero(&nbd->config_refs)) {
mutex_unlock(&nbd->config_lock);
goto out;
}
config = nbd->config = nbd_alloc_config();
if (!config) {
ret = -ENOMEM;
mutex_unlock(&nbd->config_lock);
goto out;
}
refcount_set(&nbd->config_refs, 1);
refcount_inc(&nbd->refs);
mutex_unlock(&nbd->config_lock);
bdev->bd_invalidated = 1;
} else if (nbd_disconnected(nbd->config)) {
bdev->bd_invalidated = 1;
}
out:
mutex_unlock(&nbd_index_mutex);
return ret;
}
static void nbd_release(struct gendisk *disk, fmode_t mode)
{
struct nbd_device *nbd = disk->private_data;
struct block_device *bdev = bdget_disk(disk, 0);
if (test_bit(NBD_DISCONNECT_ON_CLOSE, &nbd->config->runtime_flags) &&
bdev->bd_openers == 0)
nbd_disconnect_and_put(nbd);
nbd_config_put(nbd);
nbd_put(nbd);
}
static const struct block_device_operations nbd_fops =
{
.owner = THIS_MODULE,
.open = nbd_open,
.release = nbd_release,
.ioctl = nbd_ioctl,
.compat_ioctl = nbd_ioctl,
};
#if IS_ENABLED(CONFIG_DEBUG_FS)
static int nbd_dbg_tasks_show(struct seq_file *s, void *unused)
{
struct nbd_device *nbd = s->private;
if (nbd->task_recv)
seq_printf(s, "recv: %d\n", task_pid_nr(nbd->task_recv));
return 0;
}
static int nbd_dbg_tasks_open(struct inode *inode, struct file *file)
{
return single_open(file, nbd_dbg_tasks_show, inode->i_private);
}
static const struct file_operations nbd_dbg_tasks_ops = {
.open = nbd_dbg_tasks_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static int nbd_dbg_flags_show(struct seq_file *s, void *unused)
{
struct nbd_device *nbd = s->private;
u32 flags = nbd->config->flags;
seq_printf(s, "Hex: 0x%08x\n\n", flags);
seq_puts(s, "Known flags:\n");
if (flags & NBD_FLAG_HAS_FLAGS)
seq_puts(s, "NBD_FLAG_HAS_FLAGS\n");
if (flags & NBD_FLAG_READ_ONLY)
seq_puts(s, "NBD_FLAG_READ_ONLY\n");
if (flags & NBD_FLAG_SEND_FLUSH)
seq_puts(s, "NBD_FLAG_SEND_FLUSH\n");
if (flags & NBD_FLAG_SEND_FUA)
seq_puts(s, "NBD_FLAG_SEND_FUA\n");
if (flags & NBD_FLAG_SEND_TRIM)
seq_puts(s, "NBD_FLAG_SEND_TRIM\n");
return 0;
}
static int nbd_dbg_flags_open(struct inode *inode, struct file *file)
{
return single_open(file, nbd_dbg_flags_show, inode->i_private);
}
static const struct file_operations nbd_dbg_flags_ops = {
.open = nbd_dbg_flags_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static int nbd_dev_dbg_init(struct nbd_device *nbd)
{
struct dentry *dir;
struct nbd_config *config = nbd->config;
if (!nbd_dbg_dir)
return -EIO;
dir = debugfs_create_dir(nbd_name(nbd), nbd_dbg_dir);
if (!dir) {
dev_err(nbd_to_dev(nbd), "Failed to create debugfs dir for '%s'\n",
nbd_name(nbd));
return -EIO;
}
config->dbg_dir = dir;
debugfs_create_file("tasks", 0444, dir, nbd, &nbd_dbg_tasks_ops);
debugfs_create_u64("size_bytes", 0444, dir, &config->bytesize);
debugfs_create_u32("timeout", 0444, dir, &nbd->tag_set.timeout);
debugfs_create_u64("blocksize", 0444, dir, &config->blksize);
debugfs_create_file("flags", 0444, dir, nbd, &nbd_dbg_flags_ops);
return 0;
}
static void nbd_dev_dbg_close(struct nbd_device *nbd)
{
debugfs_remove_recursive(nbd->config->dbg_dir);
}
static int nbd_dbg_init(void)
{
struct dentry *dbg_dir;
dbg_dir = debugfs_create_dir("nbd", NULL);
if (!dbg_dir)
return -EIO;
nbd_dbg_dir = dbg_dir;
return 0;
}
static void nbd_dbg_close(void)
{
debugfs_remove_recursive(nbd_dbg_dir);
}
#else /* IS_ENABLED(CONFIG_DEBUG_FS) */
static int nbd_dev_dbg_init(struct nbd_device *nbd)
{
return 0;
}
static void nbd_dev_dbg_close(struct nbd_device *nbd)
{
}
static int nbd_dbg_init(void)
{
return 0;
}
static void nbd_dbg_close(void)
{
}
#endif
static int nbd_init_request(struct blk_mq_tag_set *set, struct request *rq,
unsigned int hctx_idx, unsigned int numa_node)
{
struct nbd_cmd *cmd = blk_mq_rq_to_pdu(rq);
cmd->nbd = set->driver_data;
cmd->flags = 0;
mutex_init(&cmd->lock);
return 0;
}
static const struct blk_mq_ops nbd_mq_ops = {
.queue_rq = nbd_queue_rq,
.complete = nbd_complete_rq,
.init_request = nbd_init_request,
.timeout = nbd_xmit_timeout,
};
static int nbd_dev_add(int index)
{
struct nbd_device *nbd;
struct gendisk *disk;
struct request_queue *q;
int err = -ENOMEM;
nbd = kzalloc(sizeof(struct nbd_device), GFP_KERNEL);
if (!nbd)
goto out;
disk = alloc_disk(1 << part_shift);
if (!disk)
goto out_free_nbd;
if (index >= 0) {
err = idr_alloc(&nbd_index_idr, nbd, index, index + 1,
GFP_KERNEL);
if (err == -ENOSPC)
err = -EEXIST;
} else {
err = idr_alloc(&nbd_index_idr, nbd, 0, 0, GFP_KERNEL);
if (err >= 0)
index = err;
}
if (err < 0)
goto out_free_disk;
nbd->index = index;
nbd->disk = disk;
nbd->tag_set.ops = &nbd_mq_ops;
nbd->tag_set.nr_hw_queues = 1;
nbd->tag_set.queue_depth = 128;
nbd->tag_set.numa_node = NUMA_NO_NODE;
nbd->tag_set.cmd_size = sizeof(struct nbd_cmd);
nbd->tag_set.flags = BLK_MQ_F_SHOULD_MERGE |
BLK_MQ_F_BLOCKING;
nbd->tag_set.driver_data = nbd;
err = blk_mq_alloc_tag_set(&nbd->tag_set);
if (err)
goto out_free_idr;
q = blk_mq_init_queue(&nbd->tag_set);
if (IS_ERR(q)) {
err = PTR_ERR(q);
goto out_free_tags;
}
disk->queue = q;
/*
* Tell the block layer that we are not a rotational device
*/
blk_queue_flag_set(QUEUE_FLAG_NONROT, disk->queue);
blk_queue_flag_clear(QUEUE_FLAG_ADD_RANDOM, disk->queue);
disk->queue->limits.discard_granularity = 0;
disk->queue->limits.discard_alignment = 0;
blk_queue_max_discard_sectors(disk->queue, 0);
blk_queue_max_segment_size(disk->queue, UINT_MAX);
blk_queue_max_segments(disk->queue, USHRT_MAX);
blk_queue_max_hw_sectors(disk->queue, 65536);
disk->queue->limits.max_sectors = 256;
mutex_init(&nbd->config_lock);
refcount_set(&nbd->config_refs, 0);
refcount_set(&nbd->refs, 1);
INIT_LIST_HEAD(&nbd->list);
disk->major = NBD_MAJOR;
disk->first_minor = index << part_shift;
disk->fops = &nbd_fops;
disk->private_data = nbd;
sprintf(disk->disk_name, "nbd%d", index);
add_disk(disk);
nbd_total_devices++;
return index;
out_free_tags:
blk_mq_free_tag_set(&nbd->tag_set);
out_free_idr:
idr_remove(&nbd_index_idr, index);
out_free_disk:
put_disk(disk);
out_free_nbd:
kfree(nbd);
out:
return err;
}
static int find_free_cb(int id, void *ptr, void *data)
{
struct nbd_device *nbd = ptr;
struct nbd_device **found = data;
if (!refcount_read(&nbd->config_refs)) {
*found = nbd;
return 1;
}
return 0;
}
/* Netlink interface. */
static const struct nla_policy nbd_attr_policy[NBD_ATTR_MAX + 1] = {
[NBD_ATTR_INDEX] = { .type = NLA_U32 },
[NBD_ATTR_SIZE_BYTES] = { .type = NLA_U64 },
[NBD_ATTR_BLOCK_SIZE_BYTES] = { .type = NLA_U64 },
[NBD_ATTR_TIMEOUT] = { .type = NLA_U64 },
[NBD_ATTR_SERVER_FLAGS] = { .type = NLA_U64 },
[NBD_ATTR_CLIENT_FLAGS] = { .type = NLA_U64 },
[NBD_ATTR_SOCKETS] = { .type = NLA_NESTED},
[NBD_ATTR_DEAD_CONN_TIMEOUT] = { .type = NLA_U64 },
[NBD_ATTR_DEVICE_LIST] = { .type = NLA_NESTED},
};
static const struct nla_policy nbd_sock_policy[NBD_SOCK_MAX + 1] = {
[NBD_SOCK_FD] = { .type = NLA_U32 },
};
/* We don't use this right now since we don't parse the incoming list, but we
* still want it here so userspace knows what to expect.
*/
static const struct nla_policy __attribute__((unused))
nbd_device_policy[NBD_DEVICE_ATTR_MAX + 1] = {
[NBD_DEVICE_INDEX] = { .type = NLA_U32 },
[NBD_DEVICE_CONNECTED] = { .type = NLA_U8 },
};
static int nbd_genl_size_set(struct genl_info *info, struct nbd_device *nbd)
{
struct nbd_config *config = nbd->config;
u64 bsize = config->blksize;
u64 bytes = config->bytesize;
if (info->attrs[NBD_ATTR_SIZE_BYTES])
bytes = nla_get_u64(info->attrs[NBD_ATTR_SIZE_BYTES]);
if (info->attrs[NBD_ATTR_BLOCK_SIZE_BYTES]) {
bsize = nla_get_u64(info->attrs[NBD_ATTR_BLOCK_SIZE_BYTES]);
if (!bsize)
bsize = NBD_DEF_BLKSIZE;
if (!nbd_is_valid_blksize(bsize)) {
printk(KERN_ERR "Invalid block size %llu\n", bsize);
return -EINVAL;
}
}
if (bytes != config->bytesize || bsize != config->blksize)
nbd_size_set(nbd, bsize, div64_u64(bytes, bsize));
return 0;
}
static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info)
{
struct nbd_device *nbd = NULL;
struct nbd_config *config;
int index = -1;
int ret;
bool put_dev = false;
if (!netlink_capable(skb, CAP_SYS_ADMIN))
return -EPERM;
if (info->attrs[NBD_ATTR_INDEX])
index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
if (!info->attrs[NBD_ATTR_SOCKETS]) {
printk(KERN_ERR "nbd: must specify at least one socket\n");
return -EINVAL;
}
if (!info->attrs[NBD_ATTR_SIZE_BYTES]) {
printk(KERN_ERR "nbd: must specify a size in bytes for the device\n");
return -EINVAL;
}
again:
mutex_lock(&nbd_index_mutex);
if (index == -1) {
ret = idr_for_each(&nbd_index_idr, &find_free_cb, &nbd);
if (ret == 0) {
int new_index;
new_index = nbd_dev_add(-1);
if (new_index < 0) {
mutex_unlock(&nbd_index_mutex);
printk(KERN_ERR "nbd: failed to add new device\n");
return new_index;
}
nbd = idr_find(&nbd_index_idr, new_index);
}
} else {
nbd = idr_find(&nbd_index_idr, index);
if (!nbd) {
ret = nbd_dev_add(index);
if (ret < 0) {
mutex_unlock(&nbd_index_mutex);
printk(KERN_ERR "nbd: failed to add new device\n");
return ret;
}
nbd = idr_find(&nbd_index_idr, index);
}
}
if (!nbd) {
printk(KERN_ERR "nbd: couldn't find device at index %d\n",
index);
mutex_unlock(&nbd_index_mutex);
return -EINVAL;
}
if (!refcount_inc_not_zero(&nbd->refs)) {
mutex_unlock(&nbd_index_mutex);
if (index == -1)
goto again;
printk(KERN_ERR "nbd: device at index %d is going down\n",
index);
return -EINVAL;
}
mutex_unlock(&nbd_index_mutex);
mutex_lock(&nbd->config_lock);
if (refcount_read(&nbd->config_refs)) {
mutex_unlock(&nbd->config_lock);
nbd_put(nbd);
if (index == -1)
goto again;
printk(KERN_ERR "nbd: nbd%d already in use\n", index);
return -EBUSY;
}
if (WARN_ON(nbd->config)) {
mutex_unlock(&nbd->config_lock);
nbd_put(nbd);
return -EINVAL;
}
config = nbd->config = nbd_alloc_config();
if (!nbd->config) {
mutex_unlock(&nbd->config_lock);
nbd_put(nbd);
printk(KERN_ERR "nbd: couldn't allocate config\n");
return -ENOMEM;
}
refcount_set(&nbd->config_refs, 1);
set_bit(NBD_BOUND, &config->runtime_flags);
ret = nbd_genl_size_set(info, nbd);
if (ret)
goto out;
if (info->attrs[NBD_ATTR_TIMEOUT])
nbd_set_cmd_timeout(nbd,
nla_get_u64(info->attrs[NBD_ATTR_TIMEOUT]));
if (info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]) {
config->dead_conn_timeout =
nla_get_u64(info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]);
config->dead_conn_timeout *= HZ;
}
if (info->attrs[NBD_ATTR_SERVER_FLAGS])
config->flags =
nla_get_u64(info->attrs[NBD_ATTR_SERVER_FLAGS]);
if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {
u64 flags = nla_get_u64(info->attrs[NBD_ATTR_CLIENT_FLAGS]);
if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {
set_bit(NBD_DESTROY_ON_DISCONNECT,
&config->runtime_flags);
put_dev = true;
}
if (flags & NBD_CFLAG_DISCONNECT_ON_CLOSE) {
set_bit(NBD_DISCONNECT_ON_CLOSE,
&config->runtime_flags);
}
}
if (info->attrs[NBD_ATTR_SOCKETS]) {
struct nlattr *attr;
int rem, fd;
nla_for_each_nested(attr, info->attrs[NBD_ATTR_SOCKETS],
rem) {
struct nlattr *socks[NBD_SOCK_MAX+1];
if (nla_type(attr) != NBD_SOCK_ITEM) {
printk(KERN_ERR "nbd: socks must be embedded in a SOCK_ITEM attr\n");
ret = -EINVAL;
goto out;
}
ret = nla_parse_nested_deprecated(socks, NBD_SOCK_MAX,
attr,
nbd_sock_policy,
info->extack);
if (ret != 0) {
printk(KERN_ERR "nbd: error processing sock list\n");
ret = -EINVAL;
goto out;
}
if (!socks[NBD_SOCK_FD])
continue;
fd = (int)nla_get_u32(socks[NBD_SOCK_FD]);
ret = nbd_add_socket(nbd, fd, true);
if (ret)
goto out;
}
}
ret = nbd_start_device(nbd);
out:
mutex_unlock(&nbd->config_lock);
if (!ret) {
set_bit(NBD_HAS_CONFIG_REF, &config->runtime_flags);
refcount_inc(&nbd->config_refs);
nbd_connect_reply(info, nbd->index);
}
nbd_config_put(nbd);
if (put_dev)
nbd_put(nbd);
return ret;
}
static void nbd_disconnect_and_put(struct nbd_device *nbd)
{
mutex_lock(&nbd->config_lock);
nbd_disconnect(nbd);
nbd_clear_sock(nbd);
mutex_unlock(&nbd->config_lock);
/*
* Make sure recv thread has finished, so it does not drop the last
* config ref and try to destroy the workqueue from inside the work
* queue.
*/
flush_workqueue(nbd->recv_workq);
if (test_and_clear_bit(NBD_HAS_CONFIG_REF,
&nbd->config->runtime_flags))
nbd_config_put(nbd);
}
static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
{
struct nbd_device *nbd;
int index;
if (!netlink_capable(skb, CAP_SYS_ADMIN))
return -EPERM;
if (!info->attrs[NBD_ATTR_INDEX]) {
printk(KERN_ERR "nbd: must specify an index to disconnect\n");
return -EINVAL;
}
index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
mutex_lock(&nbd_index_mutex);
nbd = idr_find(&nbd_index_idr, index);
if (!nbd) {
mutex_unlock(&nbd_index_mutex);
printk(KERN_ERR "nbd: couldn't find device at index %d\n",
index);
return -EINVAL;
}
if (!refcount_inc_not_zero(&nbd->refs)) {
mutex_unlock(&nbd_index_mutex);
printk(KERN_ERR "nbd: device at index %d is going down\n",
index);
return -EINVAL;
}
mutex_unlock(&nbd_index_mutex);
if (!refcount_inc_not_zero(&nbd->config_refs)) {
nbd_put(nbd);
return 0;
}
nbd_disconnect_and_put(nbd);
nbd_config_put(nbd);
nbd_put(nbd);
return 0;
}
static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
{
struct nbd_device *nbd = NULL;
struct nbd_config *config;
int index;
int ret = 0;
bool put_dev = false;
if (!netlink_capable(skb, CAP_SYS_ADMIN))
return -EPERM;
if (!info->attrs[NBD_ATTR_INDEX]) {
printk(KERN_ERR "nbd: must specify a device to reconfigure\n");
return -EINVAL;
}
index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
mutex_lock(&nbd_index_mutex);
nbd = idr_find(&nbd_index_idr, index);
if (!nbd) {
mutex_unlock(&nbd_index_mutex);
printk(KERN_ERR "nbd: couldn't find a device at index %d\n",
index);
return -EINVAL;
}
if (!refcount_inc_not_zero(&nbd->refs)) {
mutex_unlock(&nbd_index_mutex);
printk(KERN_ERR "nbd: device at index %d is going down\n",
index);
return -EINVAL;
}
mutex_unlock(&nbd_index_mutex);
if (!refcount_inc_not_zero(&nbd->config_refs)) {
dev_err(nbd_to_dev(nbd),
"not configured, cannot reconfigure\n");
nbd_put(nbd);
return -EINVAL;
}
mutex_lock(&nbd->config_lock);
config = nbd->config;
if (!test_bit(NBD_BOUND, &config->runtime_flags) ||
!nbd->task_recv) {
dev_err(nbd_to_dev(nbd),
"not configured, cannot reconfigure\n");
ret = -EINVAL;
goto out;
}
ret = nbd_genl_size_set(info, nbd);
if (ret)
goto out;
if (info->attrs[NBD_ATTR_TIMEOUT])
nbd_set_cmd_timeout(nbd,
nla_get_u64(info->attrs[NBD_ATTR_TIMEOUT]));
if (info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]) {
config->dead_conn_timeout =
nla_get_u64(info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]);
config->dead_conn_timeout *= HZ;
}
if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {
u64 flags = nla_get_u64(info->attrs[NBD_ATTR_CLIENT_FLAGS]);
if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {
if (!test_and_set_bit(NBD_DESTROY_ON_DISCONNECT,
&config->runtime_flags))
put_dev = true;
} else {
if (test_and_clear_bit(NBD_DESTROY_ON_DISCONNECT,
&config->runtime_flags))
refcount_inc(&nbd->refs);
}
if (flags & NBD_CFLAG_DISCONNECT_ON_CLOSE) {
set_bit(NBD_DISCONNECT_ON_CLOSE,
&config->runtime_flags);
} else {
clear_bit(NBD_DISCONNECT_ON_CLOSE,
&config->runtime_flags);
}
}
if (info->attrs[NBD_ATTR_SOCKETS]) {
struct nlattr *attr;
int rem, fd;
nla_for_each_nested(attr, info->attrs[NBD_ATTR_SOCKETS],
rem) {
struct nlattr *socks[NBD_SOCK_MAX+1];
if (nla_type(attr) != NBD_SOCK_ITEM) {
printk(KERN_ERR "nbd: socks must be embedded in a SOCK_ITEM attr\n");
ret = -EINVAL;
goto out;
}
ret = nla_parse_nested_deprecated(socks, NBD_SOCK_MAX,
attr,
nbd_sock_policy,
info->extack);
if (ret != 0) {
printk(KERN_ERR "nbd: error processing sock list\n");
ret = -EINVAL;
goto out;
}
if (!socks[NBD_SOCK_FD])
continue;
fd = (int)nla_get_u32(socks[NBD_SOCK_FD]);
ret = nbd_reconnect_socket(nbd, fd);
if (ret) {
if (ret == -ENOSPC)
ret = 0;
goto out;
}
dev_info(nbd_to_dev(nbd), "reconnected socket\n");
}
}
out:
mutex_unlock(&nbd->config_lock);
nbd_config_put(nbd);
nbd_put(nbd);
if (put_dev)
nbd_put(nbd);
return ret;
}
static const struct genl_ops nbd_connect_genl_ops[] = {
{
.cmd = NBD_CMD_CONNECT,
.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
.doit = nbd_genl_connect,
},
{
.cmd = NBD_CMD_DISCONNECT,
.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
.doit = nbd_genl_disconnect,
},
{
.cmd = NBD_CMD_RECONFIGURE,
.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
.doit = nbd_genl_reconfigure,
},
{
.cmd = NBD_CMD_STATUS,
.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
.doit = nbd_genl_status,
},
};
static const struct genl_multicast_group nbd_mcast_grps[] = {
{ .name = NBD_GENL_MCAST_GROUP_NAME, },
};
static struct genl_family nbd_genl_family __ro_after_init = {
.hdrsize = 0,
.name = NBD_GENL_FAMILY_NAME,
.version = NBD_GENL_VERSION,
.module = THIS_MODULE,
.ops = nbd_connect_genl_ops,
.n_ops = ARRAY_SIZE(nbd_connect_genl_ops),
.maxattr = NBD_ATTR_MAX,
.policy = nbd_attr_policy,
.mcgrps = nbd_mcast_grps,
.n_mcgrps = ARRAY_SIZE(nbd_mcast_grps),
};
static int populate_nbd_status(struct nbd_device *nbd, struct sk_buff *reply)
{
struct nlattr *dev_opt;
u8 connected = 0;
int ret;
/* This is a little racey, but for status it's ok. The
* reason we don't take a ref here is because we can't
* take a ref in the index == -1 case as we would need
* to put under the nbd_index_mutex, which could
* deadlock if we are configured to remove ourselves
* once we're disconnected.
*/
if (refcount_read(&nbd->config_refs))
connected = 1;
dev_opt = nla_nest_start_noflag(reply, NBD_DEVICE_ITEM);
if (!dev_opt)
return -EMSGSIZE;
ret = nla_put_u32(reply, NBD_DEVICE_INDEX, nbd->index);
if (ret)
return -EMSGSIZE;
ret = nla_put_u8(reply, NBD_DEVICE_CONNECTED,
connected);
if (ret)
return -EMSGSIZE;
nla_nest_end(reply, dev_opt);
return 0;
}
static int status_cb(int id, void *ptr, void *data)
{
struct nbd_device *nbd = ptr;
return populate_nbd_status(nbd, (struct sk_buff *)data);
}
static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info)
{
struct nlattr *dev_list;
struct sk_buff *reply;
void *reply_head;
size_t msg_size;
int index = -1;
int ret = -ENOMEM;
if (info->attrs[NBD_ATTR_INDEX])
index = nla_get_u32(info->attrs[NBD_ATTR_INDEX]);
mutex_lock(&nbd_index_mutex);
msg_size = nla_total_size(nla_attr_size(sizeof(u32)) +
nla_attr_size(sizeof(u8)));
msg_size *= (index == -1) ? nbd_total_devices : 1;
reply = genlmsg_new(msg_size, GFP_KERNEL);
if (!reply)
goto out;
reply_head = genlmsg_put_reply(reply, info, &nbd_genl_family, 0,
NBD_CMD_STATUS);
if (!reply_head) {
nlmsg_free(reply);
goto out;
}
dev_list = nla_nest_start_noflag(reply, NBD_ATTR_DEVICE_LIST);
if (index == -1) {
ret = idr_for_each(&nbd_index_idr, &status_cb, reply);
if (ret) {
nlmsg_free(reply);
goto out;
}
} else {
struct nbd_device *nbd;
nbd = idr_find(&nbd_index_idr, index);
if (nbd) {
ret = populate_nbd_status(nbd, reply);
if (ret) {
nlmsg_free(reply);
goto out;
}
}
}
nla_nest_end(reply, dev_list);
genlmsg_end(reply, reply_head);
ret = genlmsg_reply(reply, info);
out:
mutex_unlock(&nbd_index_mutex);
return ret;
}
static void nbd_connect_reply(struct genl_info *info, int index)
{
struct sk_buff *skb;
void *msg_head;
int ret;
skb = genlmsg_new(nla_total_size(sizeof(u32)), GFP_KERNEL);
if (!skb)
return;
msg_head = genlmsg_put_reply(skb, info, &nbd_genl_family, 0,
NBD_CMD_CONNECT);
if (!msg_head) {
nlmsg_free(skb);
return;
}
ret = nla_put_u32(skb, NBD_ATTR_INDEX, index);
if (ret) {
nlmsg_free(skb);
return;
}
genlmsg_end(skb, msg_head);
genlmsg_reply(skb, info);
}
static void nbd_mcast_index(int index)
{
struct sk_buff *skb;
void *msg_head;
int ret;
skb = genlmsg_new(nla_total_size(sizeof(u32)), GFP_KERNEL);
if (!skb)
return;
msg_head = genlmsg_put(skb, 0, 0, &nbd_genl_family, 0,
NBD_CMD_LINK_DEAD);
if (!msg_head) {
nlmsg_free(skb);
return;
}
ret = nla_put_u32(skb, NBD_ATTR_INDEX, index);
if (ret) {
nlmsg_free(skb);
return;
}
genlmsg_end(skb, msg_head);
genlmsg_multicast(&nbd_genl_family, skb, 0, 0, GFP_KERNEL);
}
static void nbd_dead_link_work(struct work_struct *work)
{
struct link_dead_args *args = container_of(work, struct link_dead_args,
work);
nbd_mcast_index(args->index);
kfree(args);
}
static int __init nbd_init(void)
{
int i;
BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
if (max_part < 0) {
printk(KERN_ERR "nbd: max_part must be >= 0\n");
return -EINVAL;
}
part_shift = 0;
if (max_part > 0) {
part_shift = fls(max_part);
/*
* Adjust max_part according to part_shift as it is exported
* to user space so that user can know the max number of
* partition kernel should be able to manage.
*
* Note that -1 is required because partition 0 is reserved
* for the whole disk.
*/
max_part = (1UL << part_shift) - 1;
}
if ((1UL << part_shift) > DISK_MAX_PARTS)
return -EINVAL;
if (nbds_max > 1UL << (MINORBITS - part_shift))
return -EINVAL;
if (register_blkdev(NBD_MAJOR, "nbd"))
return -EIO;
if (genl_register_family(&nbd_genl_family)) {
unregister_blkdev(NBD_MAJOR, "nbd");
return -EINVAL;
}
nbd_dbg_init();
mutex_lock(&nbd_index_mutex);
for (i = 0; i < nbds_max; i++)
nbd_dev_add(i);
mutex_unlock(&nbd_index_mutex);
return 0;
}
static int nbd_exit_cb(int id, void *ptr, void *data)
{
struct list_head *list = (struct list_head *)data;
struct nbd_device *nbd = ptr;
list_add_tail(&nbd->list, list);
return 0;
}
static void __exit nbd_cleanup(void)
{
struct nbd_device *nbd;
LIST_HEAD(del_list);
nbd_dbg_close();
mutex_lock(&nbd_index_mutex);
idr_for_each(&nbd_index_idr, &nbd_exit_cb, &del_list);
mutex_unlock(&nbd_index_mutex);
while (!list_empty(&del_list)) {
nbd = list_first_entry(&del_list, struct nbd_device, list);
list_del_init(&nbd->list);
if (refcount_read(&nbd->refs) != 1)
printk(KERN_ERR "nbd: possibly leaking a device\n");
nbd_put(nbd);
}
idr_destroy(&nbd_index_idr);
genl_unregister_family(&nbd_genl_family);
unregister_blkdev(NBD_MAJOR, "nbd");
}
module_init(nbd_init);
module_exit(nbd_cleanup);
MODULE_DESCRIPTION("Network Block Device");
MODULE_LICENSE("GPL");
module_param(nbds_max, int, 0444);
MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
module_param(max_part, int, 0444);
MODULE_PARM_DESC(max_part, "number of partitions per device (default: 16)");
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