1	// SPDX-License-Identifier: GPL-2.0-or-later
2	/*
3	* Network block device - make block devices work over TCP
4	*
5	* Note that you can not swap over this thing, yet. Seems to work but
6	* deadlocks sometimes - you can not swap over TCP in general.
7	*
8	* Copyright 1997-2000, 2008 Pavel Machek <pavel@ucw.cz>
9	* Parts copyright 2001 Steven Whitehouse <steve@chygwyn.com>
10	*
11	* (part of code stolen from loop.c)
12	*/
13
14	#define pr_fmt(fmt) "nbd: " fmt
15
16	#include <linux/major.h>
17
18	#include <linux/blkdev.h>
19	#include <linux/module.h>
20	#include <linux/init.h>
21	#include <linux/sched.h>
22	#include <linux/sched/mm.h>
23	#include <linux/fs.h>
24	#include <linux/bio.h>
25	#include <linux/stat.h>
26	#include <linux/errno.h>
27	#include <linux/file.h>
28	#include <linux/ioctl.h>
29	#include <linux/mutex.h>
30	#include <linux/compiler.h>
31	#include <linux/completion.h>
32	#include <linux/err.h>
33	#include <linux/kernel.h>
34	#include <linux/slab.h>
35	#include <net/sock.h>
36	#include <linux/net.h>
37	#include <linux/kthread.h>
38	#include <linux/types.h>
39	#include <linux/debugfs.h>
40	#include <linux/blk-mq.h>
41
42	#include <linux/uaccess.h>
43	#include <asm/types.h>
44
45	#include <linux/nbd.h>
46	#include <linux/nbd-netlink.h>
47	#include <net/genetlink.h>
48
49	#define CREATE_TRACE_POINTS
50	#include <trace/events/nbd.h>
51
52	static DEFINE_IDR(nbd_index_idr);
53	static DEFINE_MUTEX(nbd_index_mutex);
54	static struct workqueue_struct *nbd_del_wq;
55	static int nbd_total_devices = 0;
56
57	struct nbd_sock {
58	struct socket *sock;
59	struct mutex tx_lock;
60	struct request *pending;
61	int sent;
62	bool dead;
63	int fallback_index;
64	int cookie;
65	struct work_struct work;
66	};
67
68	struct recv_thread_args {
69	struct work_struct work;
70	struct nbd_device *nbd;
71	struct nbd_sock *nsock;
72	int index;
73	};
74
75	struct link_dead_args {
76	struct work_struct work;
77	int index;
78	};
79
80	#define NBD_RT_TIMEDOUT 0
81	#define NBD_RT_DISCONNECT_REQUESTED 1
82	#define NBD_RT_DISCONNECTED 2
83	#define NBD_RT_HAS_PID_FILE 3
84	#define NBD_RT_HAS_CONFIG_REF 4
85	#define NBD_RT_BOUND 5
86	#define NBD_RT_DISCONNECT_ON_CLOSE 6
87	#define NBD_RT_HAS_BACKEND_FILE 7
88
89	#define NBD_DESTROY_ON_DISCONNECT 0
90	#define NBD_DISCONNECT_REQUESTED 1
91
92	struct nbd_config {
93	u32 flags;
94	unsigned long runtime_flags;
95	u64 dead_conn_timeout;
96
97	struct nbd_sock **socks;
98	int num_connections;
99	atomic_t live_connections;
100	wait_queue_head_t conn_wait;
101
102	atomic_t recv_threads;
103	wait_queue_head_t recv_wq;
104	unsigned int blksize_bits;
105	loff_t bytesize;
106	#if IS_ENABLED(CONFIG_DEBUG_FS)
107	struct dentry *dbg_dir;
108	#endif
109	};
110
111	static inline unsigned int nbd_blksize(struct nbd_config *config)
112	{
113	return 1u << config->blksize_bits;
114	}
115
116	struct nbd_device {
117	struct blk_mq_tag_set tag_set;
118
119	int index;
120	refcount_t config_refs;
121	refcount_t refs;
122	struct nbd_config *config;
123	struct mutex config_lock;
124	struct gendisk *disk;
125	struct workqueue_struct *recv_workq;
126	struct work_struct remove_work;
127
128	struct list_head list;
129	struct task_struct *task_setup;
130
131	unsigned long flags;
132	pid_t pid; /* pid of nbd-client, if attached */
133
134	char *backend;
135	};
136
137	#define NBD_CMD_REQUEUED 1
138	/*
139	* This flag will be set if nbd_queue_rq() succeed, and will be checked and
140	* cleared in completion. Both setting and clearing of the flag are protected
141	* by cmd->lock.
142	*/
143	#define NBD_CMD_INFLIGHT 2
144
145	/* Just part of request header or data payload is sent successfully */
146	#define NBD_CMD_PARTIAL_SEND 3
147
148	struct nbd_cmd {
149	struct nbd_device *nbd;
150	struct mutex lock;
151	int index;
152	int cookie;
153	int retries;
154	blk_status_t status;
155	unsigned long flags;
156	u32 cmd_cookie;
157	};
158
159	#if IS_ENABLED(CONFIG_DEBUG_FS)
160	static struct dentry *nbd_dbg_dir;
161	#endif
162
163	#define nbd_name(nbd) ((nbd)->disk->disk_name)
164
165	#define NBD_DEF_BLKSIZE_BITS 10
166
167	static unsigned int nbds_max = 16;
168	static int max_part = 16;
169	static int part_shift;
170
171	static int nbd_dev_dbg_init(struct nbd_device *nbd);
172	static void nbd_dev_dbg_close(struct nbd_device *nbd);
173	static void nbd_config_put(struct nbd_device *nbd);
174	static void nbd_connect_reply(struct genl_info *info, int index);
175	static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info);
176	static void nbd_dead_link_work(struct work_struct *work);
177	static void nbd_disconnect_and_put(struct nbd_device *nbd);
178
179	static inline struct device *nbd_to_dev(struct nbd_device *nbd)
180	{
181	return disk_to_dev(nbd->disk);
182	}
183
184	static void nbd_requeue_cmd(struct nbd_cmd *cmd)
185	{
186	struct request *req = blk_mq_rq_from_pdu(pdu: cmd);
187
188	lockdep_assert_held(&cmd->lock);
189
190	/*
191	* Clear INFLIGHT flag so that this cmd won't be completed in
192	* normal completion path
193	*
194	* INFLIGHT flag will be set when the cmd is queued to nbd next
195	* time.
196	*/
197	__clear_bit(NBD_CMD_INFLIGHT, &cmd->flags);
198
199	if (!test_and_set_bit(NBD_CMD_REQUEUED, addr: &cmd->flags))
200	blk_mq_requeue_request(rq: req, kick_requeue_list: true);
201	}
202
203	#define NBD_COOKIE_BITS 32
204
205	static u64 nbd_cmd_handle(struct nbd_cmd *cmd)
206	{
207	struct request *req = blk_mq_rq_from_pdu(pdu: cmd);
208	u32 tag = blk_mq_unique_tag(rq: req);
209	u64 cookie = cmd->cmd_cookie;
210
211	return (cookie << NBD_COOKIE_BITS) | tag;
212	}
213
214	static u32 nbd_handle_to_tag(u64 handle)
215	{
216	return (u32)handle;
217	}
218
219	static u32 nbd_handle_to_cookie(u64 handle)
220	{
221	return (u32)(handle >> NBD_COOKIE_BITS);
222	}
223
224	static const char *nbdcmd_to_ascii(int cmd)
225	{
226	switch (cmd) {
227	case NBD_CMD_READ: return "read";
228	case NBD_CMD_WRITE: return "write";
229	case NBD_CMD_DISC: return "disconnect";
230	case NBD_CMD_FLUSH: return "flush";
231	case NBD_CMD_TRIM: return "trim/discard";
232	}
233	return "invalid";
234	}
235
236	static ssize_t pid_show(struct device *dev,
237	struct device_attribute *attr, char *buf)
238	{
239	struct gendisk *disk = dev_to_disk(dev);
240	struct nbd_device *nbd = disk->private_data;
241
242	return sprintf(buf, fmt: "%d\n", nbd->pid);
243	}
244
245	static const struct device_attribute pid_attr = {
246	.attr = { .name = "pid", .mode = 0444},
247	.show = pid_show,
248	};
249
250	static ssize_t backend_show(struct device *dev,
251	struct device_attribute *attr, char *buf)
252	{
253	struct gendisk *disk = dev_to_disk(dev);
254	struct nbd_device *nbd = disk->private_data;
255
256	return sprintf(buf, fmt: "%s\n", nbd->backend ?: "");
257	}
258
259	static const struct device_attribute backend_attr = {
260	.attr = { .name = "backend", .mode = 0444},
261	.show = backend_show,
262	};
263
264	static void nbd_dev_remove(struct nbd_device *nbd)
265	{
266	struct gendisk *disk = nbd->disk;
267
268	del_gendisk(gp: disk);
269	blk_mq_free_tag_set(set: &nbd->tag_set);
270
271	/*
272	* Remove from idr after del_gendisk() completes, so if the same ID is
273	* reused, the following add_disk() will succeed.
274	*/
275	mutex_lock(&nbd_index_mutex);
276	idr_remove(&nbd_index_idr, id: nbd->index);
277	mutex_unlock(lock: &nbd_index_mutex);
278	destroy_workqueue(wq: nbd->recv_workq);
279	put_disk(disk);
280	}
281
282	static void nbd_dev_remove_work(struct work_struct *work)
283	{
284	nbd_dev_remove(container_of(work, struct nbd_device, remove_work));
285	}
286
287	static void nbd_put(struct nbd_device *nbd)
288	{
289	if (!refcount_dec_and_test(r: &nbd->refs))
290	return;
291
292	/* Call del_gendisk() asynchrounously to prevent deadlock */
293	if (test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags))
294	queue_work(wq: nbd_del_wq, work: &nbd->remove_work);
295	else
296	nbd_dev_remove(nbd);
297	}
298
299	static int nbd_disconnected(struct nbd_config *config)
300	{
301	return test_bit(NBD_RT_DISCONNECTED, &config->runtime_flags) ||
302	test_bit(NBD_RT_DISCONNECT_REQUESTED, &config->runtime_flags);
303	}
304
305	static void nbd_mark_nsock_dead(struct nbd_device *nbd, struct nbd_sock *nsock,
306	int notify)
307	{
308	if (!nsock->dead && notify && !nbd_disconnected(config: nbd->config)) {
309	struct link_dead_args *args;
310	args = kmalloc(sizeof(struct link_dead_args), GFP_NOIO);
311	if (args) {
312	INIT_WORK(&args->work, nbd_dead_link_work);
313	args->index = nbd->index;
314	queue_work(wq: system_percpu_wq, work: &args->work);
315	}
316	}
317	if (!nsock->dead) {
318	kernel_sock_shutdown(sock: nsock->sock, how: SHUT_RDWR);
319	if (atomic_dec_return(v: &nbd->config->live_connections) == 0) {
320	if (test_and_clear_bit(NBD_RT_DISCONNECT_REQUESTED,
321	addr: &nbd->config->runtime_flags)) {
322	set_bit(NBD_RT_DISCONNECTED,
323	addr: &nbd->config->runtime_flags);
324	dev_info(nbd_to_dev(nbd),
325	"Disconnected due to user request.\n");
326	}
327	}
328	}
329	nsock->dead = true;
330	nsock->pending = NULL;
331	nsock->sent = 0;
332	}
333
334	static int nbd_set_size(struct nbd_device *nbd, loff_t bytesize, loff_t blksize)
335	{
336	struct queue_limits lim;
337	int error;
338
339	if (!blksize)
340	blksize = 1u << NBD_DEF_BLKSIZE_BITS;
341
342	if (blk_validate_block_size(bsize: blksize))
343	return -EINVAL;
344
345	if (bytesize < 0)
346	return -EINVAL;
347
348	nbd->config->bytesize = bytesize;
349	nbd->config->blksize_bits = __ffs(blksize);
350
351	if (!nbd->pid)
352	return 0;
353
354	lim = queue_limits_start_update(q: nbd->disk->queue);
355	if (nbd->config->flags & NBD_FLAG_SEND_TRIM)
356	lim.max_hw_discard_sectors = UINT_MAX >> SECTOR_SHIFT;
357	else
358	lim.max_hw_discard_sectors = 0;
359	if (!(nbd->config->flags & NBD_FLAG_SEND_FLUSH)) {
360	lim.features &= ~(BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA);
361	} else if (nbd->config->flags & NBD_FLAG_SEND_FUA) {
362	lim.features |= BLK_FEAT_WRITE_CACHE | BLK_FEAT_FUA;
363	} else {
364	lim.features |= BLK_FEAT_WRITE_CACHE;
365	lim.features &= ~BLK_FEAT_FUA;
366	}
367	if (nbd->config->flags & NBD_FLAG_ROTATIONAL)
368	lim.features |= BLK_FEAT_ROTATIONAL;
369	if (nbd->config->flags & NBD_FLAG_SEND_WRITE_ZEROES)
370	lim.max_write_zeroes_sectors = UINT_MAX >> SECTOR_SHIFT;
371
372	lim.logical_block_size = blksize;
373	lim.physical_block_size = blksize;
374	error = queue_limits_commit_update_frozen(q: nbd->disk->queue, lim: &lim);
375	if (error)
376	return error;
377
378	if (max_part)
379	set_bit(GD_NEED_PART_SCAN, addr: &nbd->disk->state);
380	if (!set_capacity_and_notify(disk: nbd->disk, size: bytesize >> 9))
381	kobject_uevent(kobj: &nbd_to_dev(nbd)->kobj, action: KOBJ_CHANGE);
382	return 0;
383	}
384
385	static void nbd_complete_rq(struct request *req)
386	{
387	struct nbd_cmd *cmd = blk_mq_rq_to_pdu(rq: req);
388
389	dev_dbg(nbd_to_dev(cmd->nbd), "request %p: %s\n", req,
390	cmd->status ? "failed" : "done");
391
392	blk_mq_end_request(rq: req, error: cmd->status);
393	}
394
395	/*
396	* Forcibly shutdown the socket causing all listeners to error
397	*/
398	static void sock_shutdown(struct nbd_device *nbd)
399	{
400	struct nbd_config *config = nbd->config;
401	int i;
402
403	if (config->num_connections == 0)
404	return;
405	if (test_and_set_bit(NBD_RT_DISCONNECTED, addr: &config->runtime_flags))
406	return;
407
408	for (i = 0; i < config->num_connections; i++) {
409	struct nbd_sock *nsock = config->socks[i];
410	mutex_lock(&nsock->tx_lock);
411	nbd_mark_nsock_dead(nbd, nsock, notify: 0);
412	mutex_unlock(lock: &nsock->tx_lock);
413	}
414	dev_warn(disk_to_dev(nbd->disk), "shutting down sockets\n");
415	}
416
417	static u32 req_to_nbd_cmd_type(struct request *req)
418	{
419	switch (req_op(req)) {
420	case REQ_OP_DISCARD:
421	return NBD_CMD_TRIM;
422	case REQ_OP_FLUSH:
423	return NBD_CMD_FLUSH;
424	case REQ_OP_WRITE:
425	return NBD_CMD_WRITE;
426	case REQ_OP_READ:
427	return NBD_CMD_READ;
428	case REQ_OP_WRITE_ZEROES:
429	return NBD_CMD_WRITE_ZEROES;
430	default:
431	return U32_MAX;
432	}
433	}
434
435	static struct nbd_config *nbd_get_config_unlocked(struct nbd_device *nbd)
436	{
437	if (refcount_inc_not_zero(r: &nbd->config_refs)) {
438	/*
439	* Add smp_mb__after_atomic to ensure that reading nbd->config_refs
440	* and reading nbd->config is ordered. The pair is the barrier in
441	* nbd_alloc_and_init_config(), avoid nbd->config_refs is set
442	* before nbd->config.
443	*/
444	smp_mb__after_atomic();
445	return nbd->config;
446	}
447
448	return NULL;
449	}
450
451	static enum blk_eh_timer_return nbd_xmit_timeout(struct request *req)
452	{
453	struct nbd_cmd *cmd = blk_mq_rq_to_pdu(rq: req);
454	struct nbd_device *nbd = cmd->nbd;
455	struct nbd_config *config;
456
457	if (!mutex_trylock(&cmd->lock))
458	return BLK_EH_RESET_TIMER;
459
460	/* partial send is handled in nbd_sock's work function */
461	if (test_bit(NBD_CMD_PARTIAL_SEND, &cmd->flags)) {
462	mutex_unlock(lock: &cmd->lock);
463	return BLK_EH_RESET_TIMER;
464	}
465
466	if (!test_bit(NBD_CMD_INFLIGHT, &cmd->flags)) {
467	mutex_unlock(lock: &cmd->lock);
468	return BLK_EH_DONE;
469	}
470
471	config = nbd_get_config_unlocked(nbd);
472	if (!config) {
473	cmd->status = BLK_STS_TIMEOUT;
474	__clear_bit(NBD_CMD_INFLIGHT, &cmd->flags);
475	mutex_unlock(lock: &cmd->lock);
476	goto done;
477	}
478
479	if (config->num_connections > 1 ||
480	(config->num_connections == 1 && nbd->tag_set.timeout)) {
481	dev_err_ratelimited(nbd_to_dev(nbd),
482	"Connection timed out, retrying (%d/%d alive)\n",
483	atomic_read(&config->live_connections),
484	config->num_connections);
485	/*
486	* Hooray we have more connections, requeue this IO, the submit
487	* path will put it on a real connection. Or if only one
488	* connection is configured, the submit path will wait util
489	* a new connection is reconfigured or util dead timeout.
490	*/
491	if (config->socks) {
492	if (cmd->index < config->num_connections) {
493	struct nbd_sock *nsock =
494	config->socks[cmd->index];
495	mutex_lock(&nsock->tx_lock);
496	/* We can have multiple outstanding requests, so
497	* we don't want to mark the nsock dead if we've
498	* already reconnected with a new socket, so
499	* only mark it dead if its the same socket we
500	* were sent out on.
501	*/
502	if (cmd->cookie == nsock->cookie)
503	nbd_mark_nsock_dead(nbd, nsock, notify: 1);
504	mutex_unlock(lock: &nsock->tx_lock);
505	}
506	nbd_requeue_cmd(cmd);
507	mutex_unlock(lock: &cmd->lock);
508	nbd_config_put(nbd);
509	return BLK_EH_DONE;
510	}
511	}
512
513	if (!nbd->tag_set.timeout) {
514	/*
515	* Userspace sets timeout=0 to disable socket disconnection,
516	* so just warn and reset the timer.
517	*/
518	struct nbd_sock *nsock = config->socks[cmd->index];
519	cmd->retries++;
520	dev_info(nbd_to_dev(nbd), "Possible stuck request %p: control (%s@%llu,%uB). Runtime %u seconds\n",
521	req, nbdcmd_to_ascii(req_to_nbd_cmd_type(req)),
522	(unsigned long long)blk_rq_pos(req) << 9,
523	blk_rq_bytes(req), (req->timeout / HZ) * cmd->retries);
524
525	mutex_lock(&nsock->tx_lock);
526	if (cmd->cookie != nsock->cookie) {
527	nbd_requeue_cmd(cmd);
528	mutex_unlock(lock: &nsock->tx_lock);
529	mutex_unlock(lock: &cmd->lock);
530	nbd_config_put(nbd);
531	return BLK_EH_DONE;
532	}
533	mutex_unlock(lock: &nsock->tx_lock);
534	mutex_unlock(lock: &cmd->lock);
535	nbd_config_put(nbd);
536	return BLK_EH_RESET_TIMER;
537	}
538
539	dev_err_ratelimited(nbd_to_dev(nbd), "Connection timed out\n");
540	set_bit(NBD_RT_TIMEDOUT, addr: &config->runtime_flags);
541	cmd->status = BLK_STS_IOERR;
542	__clear_bit(NBD_CMD_INFLIGHT, &cmd->flags);
543	mutex_unlock(lock: &cmd->lock);
544	sock_shutdown(nbd);
545	nbd_config_put(nbd);
546	done:
547	blk_mq_complete_request(rq: req);
548	return BLK_EH_DONE;
549	}
550
551	static int __sock_xmit(struct nbd_device *nbd, struct socket *sock, int send,
552	struct iov_iter *iter, int msg_flags, int *sent)
553	{
554	int result;
555	struct msghdr msg = {} ;
556	unsigned int noreclaim_flag;
557
558	if (unlikely(!sock)) {
559	dev_err_ratelimited(disk_to_dev(nbd->disk),
560	"Attempted %s on closed socket in sock_xmit\n",
561	(send ? "send" : "recv"));
562	return -EINVAL;
563	}
564
565	msg.msg_iter = *iter;
566
567	noreclaim_flag = memalloc_noreclaim_save();
568
569	scoped_with_kernel_creds() {
570	do {
571	sock->sk->sk_allocation = GFP_NOIO | __GFP_MEMALLOC;
572	sock->sk->sk_use_task_frag = false;
573	msg.msg_flags = msg_flags | MSG_NOSIGNAL;
574
575	if (send)
576	result = sock_sendmsg(sock, msg: &msg);
577	else
578	result = sock_recvmsg(sock, msg: &msg, flags: msg.msg_flags);
579
580	if (result <= 0) {
581	if (result == 0)
582	result = -EPIPE; /* short read */
583	break;
584	}
585	if (sent)
586	*sent += result;
587	} while (msg_data_left(msg: &msg));
588	}
589
590	memalloc_noreclaim_restore(flags: noreclaim_flag);
591
592	return result;
593	}
594
595	/*
596	* Send or receive packet. Return a positive value on success and
597	* negtive value on failure, and never return 0.
598	*/
599	static int sock_xmit(struct nbd_device *nbd, int index, int send,
600	struct iov_iter *iter, int msg_flags, int *sent)
601	{
602	struct nbd_config *config = nbd->config;
603	struct socket *sock = config->socks[index]->sock;
604
605	return __sock_xmit(nbd, sock, send, iter, msg_flags, sent);
606	}
607
608	/*
609	* Different settings for sk->sk_sndtimeo can result in different return values
610	* if there is a signal pending when we enter sendmsg, because reasons?
611	*/
612	static inline int was_interrupted(int result)
613	{
614	return result == -ERESTARTSYS || result == -EINTR;
615	}
616
617	/*
618	* We've already sent header or part of data payload, have no choice but
619	* to set pending and schedule it in work.
620	*
621	* And we have to return BLK_STS_OK to block core, otherwise this same
622	* request may be re-dispatched with different tag, but our header has
623	* been sent out with old tag, and this way does confuse reply handling.
624	*/
625	static void nbd_sched_pending_work(struct nbd_device *nbd,
626	struct nbd_sock *nsock,
627	struct nbd_cmd *cmd, int sent)
628	{
629	struct request *req = blk_mq_rq_from_pdu(pdu: cmd);
630
631	/* pending work should be scheduled only once */
632	WARN_ON_ONCE(test_bit(NBD_CMD_PARTIAL_SEND, &cmd->flags));
633
634	nsock->pending = req;
635	nsock->sent = sent;
636	set_bit(NBD_CMD_PARTIAL_SEND, addr: &cmd->flags);
637	refcount_inc(r: &nbd->config_refs);
638	schedule_work(work: &nsock->work);
639	}
640
641	/*
642	* Returns BLK_STS_RESOURCE if the caller should retry after a delay.
643	* Returns BLK_STS_IOERR if sending failed.
644	*/
645	static blk_status_t nbd_send_cmd(struct nbd_device *nbd, struct nbd_cmd *cmd,
646	int index)
647	{
648	struct request *req = blk_mq_rq_from_pdu(pdu: cmd);
649	struct nbd_config *config = nbd->config;
650	struct nbd_sock *nsock = config->socks[index];
651	int result;
652	struct nbd_request request = {.magic = htonl(NBD_REQUEST_MAGIC)};
653	struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
654	struct iov_iter from;
655	struct bio *bio;
656	u64 handle;
657	u32 type;
658	u32 nbd_cmd_flags = 0;
659	int sent = nsock->sent, skip = 0;
660
661	lockdep_assert_held(&cmd->lock);
662	lockdep_assert_held(&nsock->tx_lock);
663
664	iov_iter_kvec(i: &from, ITER_SOURCE, kvec: &iov, nr_segs: 1, count: sizeof(request));
665
666	type = req_to_nbd_cmd_type(req);
667	if (type == U32_MAX)
668	return BLK_STS_IOERR;
669
670	if (rq_data_dir(req) == WRITE &&
671	(config->flags & NBD_FLAG_READ_ONLY)) {
672	dev_err_ratelimited(disk_to_dev(nbd->disk),
673	"Write on read-only\n");
674	return BLK_STS_IOERR;
675	}
676
677	if (req->cmd_flags & REQ_FUA)
678	nbd_cmd_flags |= NBD_CMD_FLAG_FUA;
679	if ((req->cmd_flags & REQ_NOUNMAP) && (type == NBD_CMD_WRITE_ZEROES))
680	nbd_cmd_flags |= NBD_CMD_FLAG_NO_HOLE;
681
682	/* We did a partial send previously, and we at least sent the whole
683	* request struct, so just go and send the rest of the pages in the
684	* request.
685	*/
686	if (sent) {
687	if (sent >= sizeof(request)) {
688	skip = sent - sizeof(request);
689
690	/* initialize handle for tracing purposes */
691	handle = nbd_cmd_handle(cmd);
692
693	goto send_pages;
694	}
695	iov_iter_advance(i: &from, bytes: sent);
696	} else {
697	cmd->cmd_cookie++;
698	}
699	cmd->index = index;
700	cmd->cookie = nsock->cookie;
701	cmd->retries = 0;
702	request.type = htonl(type | nbd_cmd_flags);
703	if (type != NBD_CMD_FLUSH) {
704	request.from = cpu_to_be64((u64)blk_rq_pos(req) << 9);
705	request.len = htonl(blk_rq_bytes(req));
706	}
707	handle = nbd_cmd_handle(cmd);
708	request.cookie = cpu_to_be64(handle);
709
710	trace_nbd_send_request(nbd_request: &request, index: nbd->index, rq: blk_mq_rq_from_pdu(pdu: cmd));
711
712	dev_dbg(nbd_to_dev(nbd), "request %p: sending control (%s@%llu,%uB)\n",
713	req, nbdcmd_to_ascii(type),
714	(unsigned long long)blk_rq_pos(req) << 9, blk_rq_bytes(req));
715	result = sock_xmit(nbd, index, send: 1, iter: &from,
716	msg_flags: (type == NBD_CMD_WRITE) ? MSG_MORE : 0, sent: &sent);
717	trace_nbd_header_sent(req, handle);
718	if (result < 0) {
719	if (was_interrupted(result)) {
720	/* If we haven't sent anything we can just return BUSY,
721	* however if we have sent something we need to make
722	* sure we only allow this req to be sent until we are
723	* completely done.
724	*/
725	if (sent) {
726	nbd_sched_pending_work(nbd, nsock, cmd, sent);
727	return BLK_STS_OK;
728	}
729	set_bit(NBD_CMD_REQUEUED, addr: &cmd->flags);
730	return BLK_STS_RESOURCE;
731	}
732	dev_err_ratelimited(disk_to_dev(nbd->disk),
733	"Send control failed (result %d)\n", result);
734	goto requeue;
735	}
736	send_pages:
737	if (type != NBD_CMD_WRITE)
738	goto out;
739
740	bio = req->bio;
741	while (bio) {
742	struct bio *next = bio->bi_next;
743	struct bvec_iter iter;
744	struct bio_vec bvec;
745
746	bio_for_each_segment(bvec, bio, iter) {
747	bool is_last = !next && bio_iter_last(bvec, iter);
748	int flags = is_last ? 0 : MSG_MORE;
749
750	dev_dbg(nbd_to_dev(nbd), "request %p: sending %d bytes data\n",
751	req, bvec.bv_len);
752	iov_iter_bvec(i: &from, ITER_SOURCE, bvec: &bvec, nr_segs: 1, count: bvec.bv_len);
753	if (skip) {
754	if (skip >= iov_iter_count(i: &from)) {
755	skip -= iov_iter_count(i: &from);
756	continue;
757	}
758	iov_iter_advance(i: &from, bytes: skip);
759	skip = 0;
760	}
761	result = sock_xmit(nbd, index, send: 1, iter: &from, msg_flags: flags, sent: &sent);
762	if (result < 0) {
763	if (was_interrupted(result)) {
764	nbd_sched_pending_work(nbd, nsock, cmd, sent);
765	return BLK_STS_OK;
766	}
767	dev_err(disk_to_dev(nbd->disk),
768	"Send data failed (result %d)\n",
769	result);
770	goto requeue;
771	}
772	/*
773	* The completion might already have come in,
774	* so break for the last one instead of letting
775	* the iterator do it. This prevents use-after-free
776	* of the bio.
777	*/
778	if (is_last)
779	break;
780	}
781	bio = next;
782	}
783	out:
784	trace_nbd_payload_sent(req, handle);
785	nsock->pending = NULL;
786	nsock->sent = 0;
787	__set_bit(NBD_CMD_INFLIGHT, &cmd->flags);
788	return BLK_STS_OK;
789
790	requeue:
791	/*
792	* Can't requeue in case we are dealing with partial send
793	*
794	* We must run from pending work function.
795	* */
796	if (test_bit(NBD_CMD_PARTIAL_SEND, &cmd->flags))
797	return BLK_STS_OK;
798
799	/* retry on a different socket */
800	dev_err_ratelimited(disk_to_dev(nbd->disk),
801	"Request send failed, requeueing\n");
802	nbd_mark_nsock_dead(nbd, nsock, notify: 1);
803	nbd_requeue_cmd(cmd);
804	return BLK_STS_OK;
805	}
806
807	/* handle partial sending */
808	static void nbd_pending_cmd_work(struct work_struct *work)
809	{
810	struct nbd_sock *nsock = container_of(work, struct nbd_sock, work);
811	struct request *req = nsock->pending;
812	struct nbd_cmd *cmd = blk_mq_rq_to_pdu(rq: req);
813	struct nbd_device *nbd = cmd->nbd;
814	unsigned long deadline = READ_ONCE(req->deadline);
815	unsigned int wait_ms = 2;
816
817	mutex_lock(&cmd->lock);
818
819	WARN_ON_ONCE(test_bit(NBD_CMD_REQUEUED, &cmd->flags));
820	if (WARN_ON_ONCE(!test_bit(NBD_CMD_PARTIAL_SEND, &cmd->flags)))
821	goto out;
822
823	mutex_lock(&nsock->tx_lock);
824	while (true) {
825	nbd_send_cmd(nbd, cmd, index: cmd->index);
826	if (!nsock->pending)
827	break;
828
829	/* don't bother timeout handler for partial sending */
830	if (READ_ONCE(jiffies) + msecs_to_jiffies(m: wait_ms) >= deadline) {
831	cmd->status = BLK_STS_IOERR;
832	blk_mq_complete_request(rq: req);
833	break;
834	}
835	msleep(msecs: wait_ms);
836	wait_ms *= 2;
837	}
838	mutex_unlock(lock: &nsock->tx_lock);
839	clear_bit(NBD_CMD_PARTIAL_SEND, addr: &cmd->flags);
840	out:
841	mutex_unlock(lock: &cmd->lock);
842	nbd_config_put(nbd);
843	}
844
845	static int nbd_read_reply(struct nbd_device *nbd, struct socket *sock,
846	struct nbd_reply *reply)
847	{
848	struct kvec iov = {.iov_base = reply, .iov_len = sizeof(*reply)};
849	struct iov_iter to;
850	int result;
851
852	reply->magic = 0;
853	iov_iter_kvec(i: &to, ITER_DEST, kvec: &iov, nr_segs: 1, count: sizeof(*reply));
854	result = __sock_xmit(nbd, sock, send: 0, iter: &to, MSG_WAITALL, NULL);
855	if (result < 0) {
856	if (!nbd_disconnected(config: nbd->config))
857	dev_err(disk_to_dev(nbd->disk),
858	"Receive control failed (result %d)\n", result);
859	return result;
860	}
861
862	if (ntohl(reply->magic) != NBD_REPLY_MAGIC) {
863	dev_err(disk_to_dev(nbd->disk), "Wrong magic (0x%lx)\n",
864	(unsigned long)ntohl(reply->magic));
865	return -EPROTO;
866	}
867
868	return 0;
869	}
870
871	/* NULL returned = something went wrong, inform userspace */
872	static struct nbd_cmd *nbd_handle_reply(struct nbd_device *nbd, int index,
873	struct nbd_reply *reply)
874	{
875	int result;
876	struct nbd_cmd *cmd;
877	struct request *req = NULL;
878	u64 handle;
879	u16 hwq;
880	u32 tag;
881	int ret = 0;
882
883	handle = be64_to_cpu(reply->cookie);
884	tag = nbd_handle_to_tag(handle);
885	hwq = blk_mq_unique_tag_to_hwq(unique_tag: tag);
886	if (hwq < nbd->tag_set.nr_hw_queues)
887	req = blk_mq_tag_to_rq(tags: nbd->tag_set.tags[hwq],
888	tag: blk_mq_unique_tag_to_tag(unique_tag: tag));
889	if (!req || !blk_mq_request_started(rq: req)) {
890	dev_err(disk_to_dev(nbd->disk), "Unexpected reply (%d) %p\n",
891	tag, req);
892	return ERR_PTR(error: -ENOENT);
893	}
894	trace_nbd_header_received(req, handle);
895	cmd = blk_mq_rq_to_pdu(rq: req);
896
897	mutex_lock(&cmd->lock);
898	if (!test_bit(NBD_CMD_INFLIGHT, &cmd->flags)) {
899	dev_err(disk_to_dev(nbd->disk), "Suspicious reply %d (status %u flags %lu)",
900	tag, cmd->status, cmd->flags);
901	ret = -ENOENT;
902	goto out;
903	}
904	if (cmd->index != index) {
905	dev_err(disk_to_dev(nbd->disk), "Unexpected reply %d from different sock %d (expected %d)",
906	tag, index, cmd->index);
907	ret = -ENOENT;
908	goto out;
909	}
910	if (cmd->cmd_cookie != nbd_handle_to_cookie(handle)) {
911	dev_err(disk_to_dev(nbd->disk), "Double reply on req %p, cmd_cookie %u, handle cookie %u\n",
912	req, cmd->cmd_cookie, nbd_handle_to_cookie(handle));
913	ret = -ENOENT;
914	goto out;
915	}
916	if (cmd->status != BLK_STS_OK) {
917	dev_err(disk_to_dev(nbd->disk), "Command already handled %p\n",
918	req);
919	ret = -ENOENT;
920	goto out;
921	}
922	if (test_bit(NBD_CMD_REQUEUED, &cmd->flags)) {
923	dev_err(disk_to_dev(nbd->disk), "Raced with timeout on req %p\n",
924	req);
925	ret = -ENOENT;
926	goto out;
927	}
928	if (ntohl(reply->error)) {
929	dev_err(disk_to_dev(nbd->disk), "Other side returned error (%d)\n",
930	ntohl(reply->error));
931	cmd->status = BLK_STS_IOERR;
932	goto out;
933	}
934
935	dev_dbg(nbd_to_dev(nbd), "request %p: got reply\n", req);
936	if (rq_data_dir(req) != WRITE) {
937	struct req_iterator iter;
938	struct bio_vec bvec;
939	struct iov_iter to;
940
941	rq_for_each_segment(bvec, req, iter) {
942	iov_iter_bvec(i: &to, ITER_DEST, bvec: &bvec, nr_segs: 1, count: bvec.bv_len);
943	result = sock_xmit(nbd, index, send: 0, iter: &to, MSG_WAITALL, NULL);
944	if (result < 0) {
945	dev_err(disk_to_dev(nbd->disk), "Receive data failed (result %d)\n",
946	result);
947	/*
948	* If we've disconnected, we need to make sure we
949	* complete this request, otherwise error out
950	* and let the timeout stuff handle resubmitting
951	* this request onto another connection.
952	*/
953	if (nbd_disconnected(config: nbd->config)) {
954	cmd->status = BLK_STS_IOERR;
955	goto out;
956	}
957	ret = -EIO;
958	goto out;
959	}
960	dev_dbg(nbd_to_dev(nbd), "request %p: got %d bytes data\n",
961	req, bvec.bv_len);
962	}
963	}
964	out:
965	trace_nbd_payload_received(req, handle);
966	mutex_unlock(lock: &cmd->lock);
967	return ret ? ERR_PTR(error: ret) : cmd;
968	}
969
970	static void recv_work(struct work_struct *work)
971	{
972	struct recv_thread_args *args = container_of(work,
973	struct recv_thread_args,
974	work);
975	struct nbd_device *nbd = args->nbd;
976	struct nbd_config *config = nbd->config;
977	struct request_queue *q = nbd->disk->queue;
978	struct nbd_sock *nsock = args->nsock;
979	struct nbd_cmd *cmd;
980	struct request *rq;
981
982	while (1) {
983	struct nbd_reply reply;
984
985	if (nbd_read_reply(nbd, sock: nsock->sock, reply: &reply))
986	break;
987
988	/*
989	* Grab .q_usage_counter so request pool won't go away, then no
990	* request use-after-free is possible during nbd_handle_reply().
991	* If queue is frozen, there won't be any inflight requests, we
992	* needn't to handle the incoming garbage message.
993	*/
994	if (!percpu_ref_tryget(ref: &q->q_usage_counter)) {
995	dev_err(disk_to_dev(nbd->disk), "%s: no io inflight\n",
996	__func__);
997	break;
998	}
999
1000	cmd = nbd_handle_reply(nbd, index: args->index, reply: &reply);
1001	if (IS_ERR(ptr: cmd)) {
1002	percpu_ref_put(ref: &q->q_usage_counter);
1003	break;
1004	}
1005
1006	rq = blk_mq_rq_from_pdu(pdu: cmd);
1007	if (likely(!blk_should_fake_timeout(rq->q))) {
1008	bool complete;
1009
1010	mutex_lock(&cmd->lock);
1011	complete = __test_and_clear_bit(NBD_CMD_INFLIGHT,
1012	&cmd->flags);
1013	mutex_unlock(lock: &cmd->lock);
1014	if (complete)
1015	blk_mq_complete_request(rq);
1016	}
1017	percpu_ref_put(ref: &q->q_usage_counter);
1018	}
1019
1020	mutex_lock(&nsock->tx_lock);
1021	nbd_mark_nsock_dead(nbd, nsock, notify: 1);
1022	mutex_unlock(lock: &nsock->tx_lock);
1023
1024	atomic_dec(v: &config->recv_threads);
1025	wake_up(&config->recv_wq);
1026	nbd_config_put(nbd);
1027	kfree(objp: args);
1028	}
1029
1030	static bool nbd_clear_req(struct request *req, void *data)
1031	{
1032	struct nbd_cmd *cmd = blk_mq_rq_to_pdu(rq: req);
1033
1034	/* don't abort one completed request */
1035	if (blk_mq_request_completed(rq: req))
1036	return true;
1037
1038	mutex_lock(&cmd->lock);
1039	if (!__test_and_clear_bit(NBD_CMD_INFLIGHT, &cmd->flags)) {
1040	mutex_unlock(lock: &cmd->lock);
1041	return true;
1042	}
1043	cmd->status = BLK_STS_IOERR;
1044	mutex_unlock(lock: &cmd->lock);
1045
1046	blk_mq_complete_request(rq: req);
1047	return true;
1048	}
1049
1050	static void nbd_clear_que(struct nbd_device *nbd)
1051	{
1052	blk_mq_quiesce_queue(q: nbd->disk->queue);
1053	blk_mq_tagset_busy_iter(tagset: &nbd->tag_set, fn: nbd_clear_req, NULL);
1054	blk_mq_unquiesce_queue(q: nbd->disk->queue);
1055	dev_dbg(disk_to_dev(nbd->disk), "queue cleared\n");
1056	}
1057
1058	static int find_fallback(struct nbd_device *nbd, int index)
1059	{
1060	struct nbd_config *config = nbd->config;
1061	int new_index = -1;
1062	struct nbd_sock *nsock = config->socks[index];
1063	int fallback = nsock->fallback_index;
1064
1065	if (test_bit(NBD_RT_DISCONNECTED, &config->runtime_flags))
1066	return new_index;
1067
1068	if (config->num_connections <= 1) {
1069	dev_err_ratelimited(disk_to_dev(nbd->disk),
1070	"Dead connection, failed to find a fallback\n");
1071	return new_index;
1072	}
1073
1074	if (fallback >= 0 && fallback < config->num_connections &&
1075	!config->socks[fallback]->dead)
1076	return fallback;
1077
1078	if (nsock->fallback_index < 0 ||
1079	nsock->fallback_index >= config->num_connections ||
1080	config->socks[nsock->fallback_index]->dead) {
1081	int i;
1082	for (i = 0; i < config->num_connections; i++) {
1083	if (i == index)
1084	continue;
1085	if (!config->socks[i]->dead) {
1086	new_index = i;
1087	break;
1088	}
1089	}
1090	nsock->fallback_index = new_index;
1091	if (new_index < 0) {
1092	dev_err_ratelimited(disk_to_dev(nbd->disk),
1093	"Dead connection, failed to find a fallback\n");
1094	return new_index;
1095	}
1096	}
1097	new_index = nsock->fallback_index;
1098	return new_index;
1099	}
1100
1101	static int wait_for_reconnect(struct nbd_device *nbd)
1102	{
1103	struct nbd_config *config = nbd->config;
1104	if (!config->dead_conn_timeout)
1105	return 0;
1106
1107	if (!wait_event_timeout(config->conn_wait,
1108	test_bit(NBD_RT_DISCONNECTED,
1109	&config->runtime_flags) ||
1110	atomic_read(&config->live_connections) > 0,
1111	config->dead_conn_timeout))
1112	return 0;
1113
1114	return !test_bit(NBD_RT_DISCONNECTED, &config->runtime_flags);
1115	}
1116
1117	static blk_status_t nbd_handle_cmd(struct nbd_cmd *cmd, int index)
1118	{
1119	struct request *req = blk_mq_rq_from_pdu(pdu: cmd);
1120	struct nbd_device *nbd = cmd->nbd;
1121	struct nbd_config *config;
1122	struct nbd_sock *nsock;
1123	blk_status_t ret;
1124
1125	lockdep_assert_held(&cmd->lock);
1126
1127	config = nbd_get_config_unlocked(nbd);
1128	if (!config) {
1129	dev_err_ratelimited(disk_to_dev(nbd->disk),
1130	"Socks array is empty\n");
1131	return BLK_STS_IOERR;
1132	}
1133
1134	if (index >= config->num_connections) {
1135	dev_err_ratelimited(disk_to_dev(nbd->disk),
1136	"Attempted send on invalid socket\n");
1137	nbd_config_put(nbd);
1138	return BLK_STS_IOERR;
1139	}
1140	cmd->status = BLK_STS_OK;
1141	again:
1142	nsock = config->socks[index];
1143	mutex_lock(&nsock->tx_lock);
1144	if (nsock->dead) {
1145	int old_index = index;
1146	index = find_fallback(nbd, index);
1147	mutex_unlock(lock: &nsock->tx_lock);
1148	if (index < 0) {
1149	if (wait_for_reconnect(nbd)) {
1150	index = old_index;
1151	goto again;
1152	}
1153	/* All the sockets should already be down at this point,
1154	* we just want to make sure that DISCONNECTED is set so
1155	* any requests that come in that were queue'ed waiting
1156	* for the reconnect timer don't trigger the timer again
1157	* and instead just error out.
1158	*/
1159	sock_shutdown(nbd);
1160	nbd_config_put(nbd);
1161	return BLK_STS_IOERR;
1162	}
1163	goto again;
1164	}
1165
1166	/* Handle the case that we have a pending request that was partially
1167	* transmitted that _has_ to be serviced first. We need to call requeue
1168	* here so that it gets put _after_ the request that is already on the
1169	* dispatch list.
1170	*/
1171	blk_mq_start_request(rq: req);
1172	if (unlikely(nsock->pending && nsock->pending != req)) {
1173	nbd_requeue_cmd(cmd);
1174	ret = BLK_STS_OK;
1175	goto out;
1176	}
1177	ret = nbd_send_cmd(nbd, cmd, index);
1178	out:
1179	mutex_unlock(lock: &nsock->tx_lock);
1180	nbd_config_put(nbd);
1181	return ret;
1182	}
1183
1184	static blk_status_t nbd_queue_rq(struct blk_mq_hw_ctx *hctx,
1185	const struct blk_mq_queue_data *bd)
1186	{
1187	struct nbd_cmd *cmd = blk_mq_rq_to_pdu(rq: bd->rq);
1188	blk_status_t ret;
1189
1190	/*
1191	* Since we look at the bio's to send the request over the network we
1192	* need to make sure the completion work doesn't mark this request done
1193	* before we are done doing our send. This keeps us from dereferencing
1194	* freed data if we have particularly fast completions (ie we get the
1195	* completion before we exit sock_xmit on the last bvec) or in the case
1196	* that the server is misbehaving (or there was an error) before we're
1197	* done sending everything over the wire.
1198	*/
1199	mutex_lock(&cmd->lock);
1200	clear_bit(NBD_CMD_REQUEUED, addr: &cmd->flags);
1201
1202	/* We can be called directly from the user space process, which means we
1203	* could possibly have signals pending so our sendmsg will fail. In
1204	* this case we need to return that we are busy, otherwise error out as
1205	* appropriate.
1206	*/
1207	ret = nbd_handle_cmd(cmd, index: hctx->queue_num);
1208	mutex_unlock(lock: &cmd->lock);
1209
1210	return ret;
1211	}
1212
1213	static struct socket *nbd_get_socket(struct nbd_device *nbd, unsigned long fd,
1214	int *err)
1215	{
1216	struct socket *sock;
1217
1218	*err = 0;
1219	sock = sockfd_lookup(fd, err);
1220	if (!sock)
1221	return NULL;
1222
1223	if (!sk_is_tcp(sk: sock->sk) &&
1224	!sk_is_stream_unix(sk: sock->sk)) {
1225	dev_err(disk_to_dev(nbd->disk), "Unsupported socket: should be TCP or UNIX.\n");
1226	*err = -EINVAL;
1227	sockfd_put(sock);
1228	return NULL;
1229	}
1230
1231	if (sock->ops->shutdown == sock_no_shutdown) {
1232	dev_err(disk_to_dev(nbd->disk), "Unsupported socket: shutdown callout must be supported.\n");
1233	*err = -EINVAL;
1234	sockfd_put(sock);
1235	return NULL;
1236	}
1237
1238	return sock;
1239	}
1240
1241	static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
1242	bool netlink)
1243	{
1244	struct nbd_config *config = nbd->config;
1245	struct socket *sock;
1246	struct nbd_sock **socks;
1247	struct nbd_sock *nsock;
1248	unsigned int memflags;
1249	int err;
1250
1251	/* Arg will be cast to int, check it to avoid overflow */
1252	if (arg > INT_MAX)
1253	return -EINVAL;
1254	sock = nbd_get_socket(nbd, fd: arg, err: &err);
1255	if (!sock)
1256	return err;
1257
1258	/*
1259	* We need to make sure we don't get any errant requests while we're
1260	* reallocating the ->socks array.
1261	*/
1262	memflags = blk_mq_freeze_queue(q: nbd->disk->queue);
1263
1264	if (!netlink && !nbd->task_setup &&
1265	!test_bit(NBD_RT_BOUND, &config->runtime_flags))
1266	nbd->task_setup = current;
1267
1268	if (!netlink &&
1269	(nbd->task_setup != current ||
1270	test_bit(NBD_RT_BOUND, &config->runtime_flags))) {
1271	dev_err(disk_to_dev(nbd->disk),
1272	"Device being setup by another task");
1273	err = -EBUSY;
1274	goto put_socket;
1275	}
1276
1277	nsock = kzalloc(sizeof(*nsock), GFP_KERNEL);
1278	if (!nsock) {
1279	err = -ENOMEM;
1280	goto put_socket;
1281	}
1282
1283	socks = krealloc(config->socks, (config->num_connections + 1) *
1284	sizeof(struct nbd_sock *), GFP_KERNEL);
1285	if (!socks) {
1286	kfree(objp: nsock);
1287	err = -ENOMEM;
1288	goto put_socket;
1289	}
1290
1291	config->socks = socks;
1292
1293	nsock->fallback_index = -1;
1294	nsock->dead = false;
1295	mutex_init(&nsock->tx_lock);
1296	nsock->sock = sock;
1297	nsock->pending = NULL;
1298	nsock->sent = 0;
1299	nsock->cookie = 0;
1300	INIT_WORK(&nsock->work, nbd_pending_cmd_work);
1301	socks[config->num_connections++] = nsock;
1302	atomic_inc(v: &config->live_connections);
1303	blk_mq_unfreeze_queue(q: nbd->disk->queue, memflags);
1304
1305	return 0;
1306
1307	put_socket:
1308	blk_mq_unfreeze_queue(q: nbd->disk->queue, memflags);
1309	sockfd_put(sock);
1310	return err;
1311	}
1312
1313	static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg)
1314	{
1315	struct nbd_config *config = nbd->config;
1316	struct socket *sock, *old;
1317	struct recv_thread_args *args;
1318	int i;
1319	int err;
1320
1321	sock = nbd_get_socket(nbd, fd: arg, err: &err);
1322	if (!sock)
1323	return err;
1324
1325	args = kzalloc(sizeof(*args), GFP_KERNEL);
1326	if (!args) {
1327	sockfd_put(sock);
1328	return -ENOMEM;
1329	}
1330
1331	for (i = 0; i < config->num_connections; i++) {
1332	struct nbd_sock *nsock = config->socks[i];
1333
1334	if (!nsock->dead)
1335	continue;
1336
1337	mutex_lock(&nsock->tx_lock);
1338	if (!nsock->dead) {
1339	mutex_unlock(lock: &nsock->tx_lock);
1340	continue;
1341	}
1342	sk_set_memalloc(sk: sock->sk);
1343	if (nbd->tag_set.timeout)
1344	sock->sk->sk_sndtimeo = nbd->tag_set.timeout;
1345	atomic_inc(v: &config->recv_threads);
1346	refcount_inc(r: &nbd->config_refs);
1347	old = nsock->sock;
1348	nsock->fallback_index = -1;
1349	nsock->sock = sock;
1350	nsock->dead = false;
1351	INIT_WORK(&args->work, recv_work);
1352	args->index = i;
1353	args->nbd = nbd;
1354	args->nsock = nsock;
1355	nsock->cookie++;
1356	mutex_unlock(lock: &nsock->tx_lock);
1357	sockfd_put(old);
1358
1359	clear_bit(NBD_RT_DISCONNECTED, addr: &config->runtime_flags);
1360
1361	/* We take the tx_mutex in an error path in the recv_work, so we
1362	* need to queue_work outside of the tx_mutex.
1363	*/
1364	queue_work(wq: nbd->recv_workq, work: &args->work);
1365
1366	atomic_inc(v: &config->live_connections);
1367	wake_up(&config->conn_wait);
1368	return 0;
1369	}
1370	sockfd_put(sock);
1371	kfree(objp: args);
1372	return -ENOSPC;
1373	}
1374
1375	static void nbd_bdev_reset(struct nbd_device *nbd)
1376	{
1377	if (disk_openers(disk: nbd->disk) > 1)
1378	return;
1379	set_capacity(disk: nbd->disk, size: 0);
1380	}
1381
1382	static void nbd_parse_flags(struct nbd_device *nbd)
1383	{
1384	if (nbd->config->flags & NBD_FLAG_READ_ONLY)
1385	set_disk_ro(disk: nbd->disk, read_only: true);
1386	else
1387	set_disk_ro(disk: nbd->disk, read_only: false);
1388	}
1389
1390	static void send_disconnects(struct nbd_device *nbd)
1391	{
1392	struct nbd_config *config = nbd->config;
1393	struct nbd_request request = {
1394	.magic = htonl(NBD_REQUEST_MAGIC),
1395	.type = htonl(NBD_CMD_DISC),
1396	};
1397	struct kvec iov = {.iov_base = &request, .iov_len = sizeof(request)};
1398	struct iov_iter from;
1399	int i, ret;
1400
1401	for (i = 0; i < config->num_connections; i++) {
1402	struct nbd_sock *nsock = config->socks[i];
1403
1404	iov_iter_kvec(i: &from, ITER_SOURCE, kvec: &iov, nr_segs: 1, count: sizeof(request));
1405	mutex_lock(&nsock->tx_lock);
1406	ret = sock_xmit(nbd, index: i, send: 1, iter: &from, msg_flags: 0, NULL);
1407	if (ret < 0)
1408	dev_err(disk_to_dev(nbd->disk),
1409	"Send disconnect failed %d\n", ret);
1410	mutex_unlock(lock: &nsock->tx_lock);
1411	}
1412	}
1413
1414	static int nbd_disconnect(struct nbd_device *nbd)
1415	{
1416	struct nbd_config *config = nbd->config;
1417
1418	dev_info(disk_to_dev(nbd->disk), "NBD_DISCONNECT\n");
1419	set_bit(NBD_RT_DISCONNECT_REQUESTED, addr: &config->runtime_flags);
1420	set_bit(NBD_DISCONNECT_REQUESTED, addr: &nbd->flags);
1421	send_disconnects(nbd);
1422	return 0;
1423	}
1424
1425	static void nbd_clear_sock(struct nbd_device *nbd)
1426	{
1427	sock_shutdown(nbd);
1428	nbd_clear_que(nbd);
1429	nbd->task_setup = NULL;
1430	}
1431
1432	static void nbd_config_put(struct nbd_device *nbd)
1433	{
1434	if (refcount_dec_and_mutex_lock(r: &nbd->config_refs,
1435	lock: &nbd->config_lock)) {
1436	struct nbd_config *config = nbd->config;
1437	nbd_dev_dbg_close(nbd);
1438	invalidate_disk(disk: nbd->disk);
1439	if (nbd->config->bytesize)
1440	kobject_uevent(kobj: &nbd_to_dev(nbd)->kobj, action: KOBJ_CHANGE);
1441	if (test_and_clear_bit(NBD_RT_HAS_PID_FILE,
1442	addr: &config->runtime_flags))
1443	device_remove_file(disk_to_dev(nbd->disk), attr: &pid_attr);
1444	nbd->pid = 0;
1445	if (test_and_clear_bit(NBD_RT_HAS_BACKEND_FILE,
1446	addr: &config->runtime_flags)) {
1447	device_remove_file(disk_to_dev(nbd->disk), attr: &backend_attr);
1448	kfree(objp: nbd->backend);
1449	nbd->backend = NULL;
1450	}
1451	nbd_clear_sock(nbd);
1452	if (config->num_connections) {
1453	int i;
1454	for (i = 0; i < config->num_connections; i++) {
1455	sockfd_put(config->socks[i]->sock);
1456	kfree(objp: config->socks[i]);
1457	}
1458	kfree(objp: config->socks);
1459	}
1460	kfree(objp: nbd->config);
1461	nbd->config = NULL;
1462
1463	nbd->tag_set.timeout = 0;
1464
1465	mutex_unlock(lock: &nbd->config_lock);
1466	nbd_put(nbd);
1467	module_put(THIS_MODULE);
1468	}
1469	}
1470
1471	static int nbd_start_device(struct nbd_device *nbd)
1472	{
1473	struct nbd_config *config = nbd->config;
1474	int num_connections = config->num_connections;
1475	int error = 0, i;
1476
1477	if (nbd->pid)
1478	return -EBUSY;
1479	if (!config->socks)
1480	return -EINVAL;
1481	if (num_connections > 1 &&
1482	!(config->flags & NBD_FLAG_CAN_MULTI_CONN)) {
1483	dev_err(disk_to_dev(nbd->disk), "server does not support multiple connections per device.\n");
1484	return -EINVAL;
1485	}
1486
1487	retry:
1488	mutex_unlock(lock: &nbd->config_lock);
1489	blk_mq_update_nr_hw_queues(set: &nbd->tag_set, nr_hw_queues: num_connections);
1490	mutex_lock(&nbd->config_lock);
1491
1492	/* if another code path updated nr_hw_queues, retry until succeed */
1493	if (num_connections != config->num_connections) {
1494	num_connections = config->num_connections;
1495	goto retry;
1496	}
1497
1498	nbd->pid = task_pid_nr(current);
1499
1500	nbd_parse_flags(nbd);
1501
1502	error = device_create_file(disk_to_dev(nbd->disk), entry: &pid_attr);
1503	if (error) {
1504	dev_err(disk_to_dev(nbd->disk), "device_create_file failed for pid!\n");
1505	return error;
1506	}
1507	set_bit(NBD_RT_HAS_PID_FILE, addr: &config->runtime_flags);
1508
1509	nbd_dev_dbg_init(nbd);
1510	for (i = 0; i < num_connections; i++) {
1511	struct recv_thread_args *args;
1512
1513	args = kzalloc(sizeof(*args), GFP_KERNEL);
1514	if (!args) {
1515	sock_shutdown(nbd);
1516	/*
1517	* If num_connections is m (2 < m),
1518	* and NO.1 ~ NO.n(1 < n < m) kzallocs are successful.
1519	* But NO.(n + 1) failed. We still have n recv threads.
1520	* So, add flush_workqueue here to prevent recv threads
1521	* dropping the last config_refs and trying to destroy
1522	* the workqueue from inside the workqueue.
1523	*/
1524	if (i)
1525	flush_workqueue(nbd->recv_workq);
1526	return -ENOMEM;
1527	}
1528	sk_set_memalloc(sk: config->socks[i]->sock->sk);
1529	if (nbd->tag_set.timeout)
1530	config->socks[i]->sock->sk->sk_sndtimeo =
1531	nbd->tag_set.timeout;
1532	atomic_inc(v: &config->recv_threads);
1533	refcount_inc(r: &nbd->config_refs);
1534	INIT_WORK(&args->work, recv_work);
1535	args->nbd = nbd;
1536	args->nsock = config->socks[i];
1537	args->index = i;
1538	queue_work(wq: nbd->recv_workq, work: &args->work);
1539	}
1540	return nbd_set_size(nbd, bytesize: config->bytesize, blksize: nbd_blksize(config));
1541	}
1542
1543	static int nbd_start_device_ioctl(struct nbd_device *nbd)
1544	{
1545	struct nbd_config *config = nbd->config;
1546	int ret;
1547
1548	ret = nbd_start_device(nbd);
1549	if (ret)
1550	return ret;
1551
1552	if (max_part)
1553	set_bit(GD_NEED_PART_SCAN, addr: &nbd->disk->state);
1554	mutex_unlock(lock: &nbd->config_lock);
1555	ret = wait_event_interruptible(config->recv_wq,
1556	atomic_read(&config->recv_threads) == 0);
1557	if (ret) {
1558	sock_shutdown(nbd);
1559	nbd_clear_que(nbd);
1560	}
1561
1562	flush_workqueue(nbd->recv_workq);
1563	mutex_lock(&nbd->config_lock);
1564	nbd_bdev_reset(nbd);
1565	/* user requested, ignore socket errors */
1566	if (test_bit(NBD_RT_DISCONNECT_REQUESTED, &config->runtime_flags))
1567	ret = 0;
1568	if (test_bit(NBD_RT_TIMEDOUT, &config->runtime_flags))
1569	ret = -ETIMEDOUT;
1570	return ret;
1571	}
1572
1573	static void nbd_clear_sock_ioctl(struct nbd_device *nbd)
1574	{
1575	nbd_clear_sock(nbd);
1576	disk_force_media_change(disk: nbd->disk);
1577	nbd_bdev_reset(nbd);
1578	if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF,
1579	addr: &nbd->config->runtime_flags))
1580	nbd_config_put(nbd);
1581	}
1582
1583	static void nbd_set_cmd_timeout(struct nbd_device *nbd, u64 timeout)
1584	{
1585	nbd->tag_set.timeout = timeout * HZ;
1586	if (timeout)
1587	blk_queue_rq_timeout(nbd->disk->queue, timeout * HZ);
1588	else
1589	blk_queue_rq_timeout(nbd->disk->queue, 30 * HZ);
1590	}
1591
1592	/* Must be called with config_lock held */
1593	static int __nbd_ioctl(struct block_device *bdev, struct nbd_device *nbd,
1594	unsigned int cmd, unsigned long arg)
1595	{
1596	struct nbd_config *config = nbd->config;
1597	loff_t bytesize;
1598
1599	switch (cmd) {
1600	case NBD_DISCONNECT:
1601	return nbd_disconnect(nbd);
1602	case NBD_CLEAR_SOCK:
1603	nbd_clear_sock_ioctl(nbd);
1604	return 0;
1605	case NBD_SET_SOCK:
1606	return nbd_add_socket(nbd, arg, netlink: false);
1607	case NBD_SET_BLKSIZE:
1608	return nbd_set_size(nbd, bytesize: config->bytesize, blksize: arg);
1609	case NBD_SET_SIZE:
1610	return nbd_set_size(nbd, bytesize: arg, blksize: nbd_blksize(config));
1611	case NBD_SET_SIZE_BLOCKS:
1612	if (check_shl_overflow(arg, config->blksize_bits, &bytesize))
1613	return -EINVAL;
1614	return nbd_set_size(nbd, bytesize, blksize: nbd_blksize(config));
1615	case NBD_SET_TIMEOUT:
1616	nbd_set_cmd_timeout(nbd, timeout: arg);
1617	return 0;
1618
1619	case NBD_SET_FLAGS:
1620	config->flags = arg;
1621	return 0;
1622	case NBD_DO_IT:
1623	return nbd_start_device_ioctl(nbd);
1624	case NBD_CLEAR_QUE:
1625	/*
1626	* This is for compatibility only. The queue is always cleared
1627	* by NBD_DO_IT or NBD_CLEAR_SOCK.
1628	*/
1629	return 0;
1630	case NBD_PRINT_DEBUG:
1631	/*
1632	* For compatibility only, we no longer keep a list of
1633	* outstanding requests.
1634	*/
1635	return 0;
1636	}
1637	return -ENOTTY;
1638	}
1639
1640	static int nbd_ioctl(struct block_device *bdev, blk_mode_t mode,
1641	unsigned int cmd, unsigned long arg)
1642	{
1643	struct nbd_device *nbd = bdev->bd_disk->private_data;
1644	struct nbd_config *config = nbd->config;
1645	int error = -EINVAL;
1646
1647	if (!capable(CAP_SYS_ADMIN))
1648	return -EPERM;
1649
1650	/* The block layer will pass back some non-nbd ioctls in case we have
1651	* special handling for them, but we don't so just return an error.
1652	*/
1653	if (_IOC_TYPE(cmd) != 0xab)
1654	return -EINVAL;
1655
1656	mutex_lock(&nbd->config_lock);
1657
1658	/* Don't allow ioctl operations on a nbd device that was created with
1659	* netlink, unless it's DISCONNECT or CLEAR_SOCK, which are fine.
1660	*/
1661	if (!test_bit(NBD_RT_BOUND, &config->runtime_flags) ||
1662	(cmd == NBD_DISCONNECT || cmd == NBD_CLEAR_SOCK))
1663	error = __nbd_ioctl(bdev, nbd, cmd, arg);
1664	else
1665	dev_err(nbd_to_dev(nbd), "Cannot use ioctl interface on a netlink controlled device.\n");
1666	mutex_unlock(lock: &nbd->config_lock);
1667	return error;
1668	}
1669
1670	static int nbd_alloc_and_init_config(struct nbd_device *nbd)
1671	{
1672	struct nbd_config *config;
1673
1674	if (WARN_ON(nbd->config))
1675	return -EINVAL;
1676
1677	if (!try_module_get(THIS_MODULE))
1678	return -ENODEV;
1679
1680	config = kzalloc(sizeof(struct nbd_config), GFP_NOFS);
1681	if (!config) {
1682	module_put(THIS_MODULE);
1683	return -ENOMEM;
1684	}
1685
1686	atomic_set(v: &config->recv_threads, i: 0);
1687	init_waitqueue_head(&config->recv_wq);
1688	init_waitqueue_head(&config->conn_wait);
1689	config->blksize_bits = NBD_DEF_BLKSIZE_BITS;
1690	atomic_set(v: &config->live_connections, i: 0);
1691
1692	nbd->config = config;
1693	/*
1694	* Order refcount_set(&nbd->config_refs, 1) and nbd->config assignment,
1695	* its pair is the barrier in nbd_get_config_unlocked().
1696	* So nbd_get_config_unlocked() won't see nbd->config as null after
1697	* refcount_inc_not_zero() succeed.
1698	*/
1699	smp_mb__before_atomic();
1700	refcount_set(r: &nbd->config_refs, n: 1);
1701
1702	return 0;
1703	}
1704
1705	static int nbd_open(struct gendisk *disk, blk_mode_t mode)
1706	{
1707	struct nbd_device *nbd;
1708	struct nbd_config *config;
1709	int ret = 0;
1710
1711	mutex_lock(&nbd_index_mutex);
1712	nbd = disk->private_data;
1713	if (!nbd) {
1714	ret = -ENXIO;
1715	goto out;
1716	}
1717	if (!refcount_inc_not_zero(r: &nbd->refs)) {
1718	ret = -ENXIO;
1719	goto out;
1720	}
1721
1722	config = nbd_get_config_unlocked(nbd);
1723	if (!config) {
1724	mutex_lock(&nbd->config_lock);
1725	if (refcount_inc_not_zero(r: &nbd->config_refs)) {
1726	mutex_unlock(lock: &nbd->config_lock);
1727	goto out;
1728	}
1729	ret = nbd_alloc_and_init_config(nbd);
1730	if (ret) {
1731	mutex_unlock(lock: &nbd->config_lock);
1732	goto out;
1733	}
1734
1735	refcount_inc(r: &nbd->refs);
1736	mutex_unlock(lock: &nbd->config_lock);
1737	if (max_part)
1738	set_bit(GD_NEED_PART_SCAN, addr: &disk->state);
1739	} else if (nbd_disconnected(config)) {
1740	if (max_part)
1741	set_bit(GD_NEED_PART_SCAN, addr: &disk->state);
1742	}
1743	out:
1744	mutex_unlock(lock: &nbd_index_mutex);
1745	return ret;
1746	}
1747
1748	static void nbd_release(struct gendisk *disk)
1749	{
1750	struct nbd_device *nbd = disk->private_data;
1751
1752	if (test_bit(NBD_RT_DISCONNECT_ON_CLOSE, &nbd->config->runtime_flags) &&
1753	disk_openers(disk) == 0)
1754	nbd_disconnect_and_put(nbd);
1755
1756	nbd_config_put(nbd);
1757	nbd_put(nbd);
1758	}
1759
1760	static void nbd_free_disk(struct gendisk *disk)
1761	{
1762	struct nbd_device *nbd = disk->private_data;
1763
1764	kfree(objp: nbd);
1765	}
1766
1767	static const struct block_device_operations nbd_fops =
1768	{
1769	.owner = THIS_MODULE,
1770	.open = nbd_open,
1771	.release = nbd_release,
1772	.ioctl = nbd_ioctl,
1773	.compat_ioctl = nbd_ioctl,
1774	.free_disk = nbd_free_disk,
1775	};
1776
1777	#if IS_ENABLED(CONFIG_DEBUG_FS)
1778
1779	static int nbd_dbg_tasks_show(struct seq_file *s, void *unused)
1780	{
1781	struct nbd_device *nbd = s->private;
1782
1783	if (nbd->pid)
1784	seq_printf(m: s, fmt: "recv: %d\n", nbd->pid);
1785
1786	return 0;
1787	}
1788
1789	DEFINE_SHOW_ATTRIBUTE(nbd_dbg_tasks);
1790
1791	static int nbd_dbg_flags_show(struct seq_file *s, void *unused)
1792	{
1793	struct nbd_device *nbd = s->private;
1794	u32 flags = nbd->config->flags;
1795
1796	seq_printf(m: s, fmt: "Hex: 0x%08x\n\n", flags);
1797
1798	seq_puts(m: s, s: "Known flags:\n");
1799
1800	if (flags & NBD_FLAG_HAS_FLAGS)
1801	seq_puts(m: s, s: "NBD_FLAG_HAS_FLAGS\n");
1802	if (flags & NBD_FLAG_READ_ONLY)
1803	seq_puts(m: s, s: "NBD_FLAG_READ_ONLY\n");
1804	if (flags & NBD_FLAG_SEND_FLUSH)
1805	seq_puts(m: s, s: "NBD_FLAG_SEND_FLUSH\n");
1806	if (flags & NBD_FLAG_SEND_FUA)
1807	seq_puts(m: s, s: "NBD_FLAG_SEND_FUA\n");
1808	if (flags & NBD_FLAG_SEND_TRIM)
1809	seq_puts(m: s, s: "NBD_FLAG_SEND_TRIM\n");
1810	if (flags & NBD_FLAG_SEND_WRITE_ZEROES)
1811	seq_puts(m: s, s: "NBD_FLAG_SEND_WRITE_ZEROES\n");
1812	if (flags & NBD_FLAG_ROTATIONAL)
1813	seq_puts(m: s, s: "NBD_FLAG_ROTATIONAL\n");
1814
1815	return 0;
1816	}
1817
1818	DEFINE_SHOW_ATTRIBUTE(nbd_dbg_flags);
1819
1820	static int nbd_dev_dbg_init(struct nbd_device *nbd)
1821	{
1822	struct dentry *dir;
1823	struct nbd_config *config = nbd->config;
1824
1825	if (!nbd_dbg_dir)
1826	return -EIO;
1827
1828	dir = debugfs_create_dir(nbd_name(nbd), parent: nbd_dbg_dir);
1829	if (IS_ERR(ptr: dir)) {
1830	dev_err(nbd_to_dev(nbd), "Failed to create debugfs dir for '%s'\n",
1831	nbd_name(nbd));
1832	return -EIO;
1833	}
1834	config->dbg_dir = dir;
1835
1836	debugfs_create_file("tasks", 0444, dir, nbd, &nbd_dbg_tasks_fops);
1837	debugfs_create_u64(name: "size_bytes", mode: 0444, parent: dir, value: &config->bytesize);
1838	debugfs_create_u32(name: "timeout", mode: 0444, parent: dir, value: &nbd->tag_set.timeout);
1839	debugfs_create_u32(name: "blocksize_bits", mode: 0444, parent: dir, value: &config->blksize_bits);
1840	debugfs_create_file("flags", 0444, dir, nbd, &nbd_dbg_flags_fops);
1841
1842	return 0;
1843	}
1844
1845	static void nbd_dev_dbg_close(struct nbd_device *nbd)
1846	{
1847	debugfs_remove_recursive(dentry: nbd->config->dbg_dir);
1848	}
1849
1850	static int nbd_dbg_init(void)
1851	{
1852	struct dentry *dbg_dir;
1853
1854	dbg_dir = debugfs_create_dir(name: "nbd", NULL);
1855	if (IS_ERR(ptr: dbg_dir))
1856	return -EIO;
1857
1858	nbd_dbg_dir = dbg_dir;
1859
1860	return 0;
1861	}
1862
1863	static void nbd_dbg_close(void)
1864	{
1865	debugfs_remove_recursive(dentry: nbd_dbg_dir);
1866	}
1867
1868	#else /* IS_ENABLED(CONFIG_DEBUG_FS) */
1869
1870	static int nbd_dev_dbg_init(struct nbd_device *nbd)
1871	{
1872	return 0;
1873	}
1874
1875	static void nbd_dev_dbg_close(struct nbd_device *nbd)
1876	{
1877	}
1878
1879	static int nbd_dbg_init(void)
1880	{
1881	return 0;
1882	}
1883
1884	static void nbd_dbg_close(void)
1885	{
1886	}
1887
1888	#endif
1889
1890	static int nbd_init_request(struct blk_mq_tag_set *set, struct request *rq,
1891	unsigned int hctx_idx, unsigned int numa_node)
1892	{
1893	struct nbd_cmd *cmd = blk_mq_rq_to_pdu(rq);
1894	cmd->nbd = set->driver_data;
1895	cmd->flags = 0;
1896	mutex_init(&cmd->lock);
1897	return 0;
1898	}
1899
1900	static const struct blk_mq_ops nbd_mq_ops = {
1901	.queue_rq = nbd_queue_rq,
1902	.complete = nbd_complete_rq,
1903	.init_request = nbd_init_request,
1904	.timeout = nbd_xmit_timeout,
1905	};
1906
1907	static struct nbd_device *nbd_dev_add(int index, unsigned int refs)
1908	{
1909	struct queue_limits lim = {
1910	.max_hw_sectors = 65536,
1911	.io_opt = 256 << SECTOR_SHIFT,
1912	.max_segments = USHRT_MAX,
1913	.max_segment_size = UINT_MAX,
1914	};
1915	struct nbd_device *nbd;
1916	struct gendisk *disk;
1917	int err = -ENOMEM;
1918
1919	nbd = kzalloc(sizeof(struct nbd_device), GFP_KERNEL);
1920	if (!nbd)
1921	goto out;
1922
1923	nbd->tag_set.ops = &nbd_mq_ops;
1924	nbd->tag_set.nr_hw_queues = 1;
1925	nbd->tag_set.queue_depth = 128;
1926	nbd->tag_set.numa_node = NUMA_NO_NODE;
1927	nbd->tag_set.cmd_size = sizeof(struct nbd_cmd);
1928	nbd->tag_set.flags = BLK_MQ_F_BLOCKING;
1929	nbd->tag_set.driver_data = nbd;
1930	INIT_WORK(&nbd->remove_work, nbd_dev_remove_work);
1931	nbd->backend = NULL;
1932
1933	err = blk_mq_alloc_tag_set(set: &nbd->tag_set);
1934	if (err)
1935	goto out_free_nbd;
1936
1937	mutex_lock(&nbd_index_mutex);
1938	if (index >= 0) {
1939	err = idr_alloc(&nbd_index_idr, ptr: nbd, start: index, end: index + 1,
1940	GFP_KERNEL);
1941	if (err == -ENOSPC)
1942	err = -EEXIST;
1943	} else {
1944	err = idr_alloc(&nbd_index_idr, ptr: nbd, start: 0,
1945	end: (MINORMASK >> part_shift) + 1, GFP_KERNEL);
1946	if (err >= 0)
1947	index = err;
1948	}
1949	nbd->index = index;
1950	mutex_unlock(lock: &nbd_index_mutex);
1951	if (err < 0)
1952	goto out_free_tags;
1953
1954	disk = blk_mq_alloc_disk(&nbd->tag_set, &lim, NULL);
1955	if (IS_ERR(ptr: disk)) {
1956	err = PTR_ERR(ptr: disk);
1957	goto out_free_idr;
1958	}
1959	nbd->disk = disk;
1960
1961	nbd->recv_workq = alloc_workqueue("nbd%d-recv",
1962	WQ_MEM_RECLAIM | WQ_HIGHPRI |
1963	WQ_UNBOUND, 0, nbd->index);
1964	if (!nbd->recv_workq) {
1965	dev_err(disk_to_dev(nbd->disk), "Could not allocate knbd recv work queue.\n");
1966	err = -ENOMEM;
1967	goto out_err_disk;
1968	}
1969
1970	mutex_init(&nbd->config_lock);
1971	refcount_set(r: &nbd->config_refs, n: 0);
1972	/*
1973	* Start out with a zero references to keep other threads from using
1974	* this device until it is fully initialized.
1975	*/
1976	refcount_set(r: &nbd->refs, n: 0);
1977	INIT_LIST_HEAD(list: &nbd->list);
1978	disk->major = NBD_MAJOR;
1979	disk->first_minor = index << part_shift;
1980	disk->minors = 1 << part_shift;
1981	disk->fops = &nbd_fops;
1982	disk->private_data = nbd;
1983	sprintf(buf: disk->disk_name, fmt: "nbd%d", index);
1984	err = add_disk(disk);
1985	if (err)
1986	goto out_free_work;
1987
1988	/*
1989	* Now publish the device.
1990	*/
1991	refcount_set(r: &nbd->refs, n: refs);
1992	nbd_total_devices++;
1993	return nbd;
1994
1995	out_free_work:
1996	destroy_workqueue(wq: nbd->recv_workq);
1997	out_err_disk:
1998	put_disk(disk);
1999	out_free_idr:
2000	mutex_lock(&nbd_index_mutex);
2001	idr_remove(&nbd_index_idr, id: index);
2002	mutex_unlock(lock: &nbd_index_mutex);
2003	out_free_tags:
2004	blk_mq_free_tag_set(set: &nbd->tag_set);
2005	out_free_nbd:
2006	kfree(objp: nbd);
2007	out:
2008	return ERR_PTR(error: err);
2009	}
2010
2011	static struct nbd_device *nbd_find_get_unused(void)
2012	{
2013	struct nbd_device *nbd;
2014	int id;
2015
2016	lockdep_assert_held(&nbd_index_mutex);
2017
2018	idr_for_each_entry(&nbd_index_idr, nbd, id) {
2019	if (refcount_read(r: &nbd->config_refs) ||
2020	test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags))
2021	continue;
2022	if (refcount_inc_not_zero(r: &nbd->refs))
2023	return nbd;
2024	}
2025
2026	return NULL;
2027	}
2028
2029	/* Netlink interface. */
2030	static const struct nla_policy nbd_attr_policy[NBD_ATTR_MAX + 1] = {
2031	[NBD_ATTR_INDEX] = { .type = NLA_U32 },
2032	[NBD_ATTR_SIZE_BYTES] = { .type = NLA_U64 },
2033	[NBD_ATTR_BLOCK_SIZE_BYTES] = { .type = NLA_U64 },
2034	[NBD_ATTR_TIMEOUT] = { .type = NLA_U64 },
2035	[NBD_ATTR_SERVER_FLAGS] = { .type = NLA_U64 },
2036	[NBD_ATTR_CLIENT_FLAGS] = { .type = NLA_U64 },
2037	[NBD_ATTR_SOCKETS] = { .type = NLA_NESTED},
2038	[NBD_ATTR_DEAD_CONN_TIMEOUT] = { .type = NLA_U64 },
2039	[NBD_ATTR_DEVICE_LIST] = { .type = NLA_NESTED},
2040	[NBD_ATTR_BACKEND_IDENTIFIER] = { .type = NLA_STRING},
2041	};
2042
2043	static const struct nla_policy nbd_sock_policy[NBD_SOCK_MAX + 1] = {
2044	[NBD_SOCK_FD] = { .type = NLA_U32 },
2045	};
2046
2047	/* We don't use this right now since we don't parse the incoming list, but we
2048	* still want it here so userspace knows what to expect.
2049	*/
2050	static const struct nla_policy __attribute__((unused))
2051	nbd_device_policy[NBD_DEVICE_ATTR_MAX + 1] = {
2052	[NBD_DEVICE_INDEX] = { .type = NLA_U32 },
2053	[NBD_DEVICE_CONNECTED] = { .type = NLA_U8 },
2054	};
2055
2056	static int nbd_genl_size_set(struct genl_info *info, struct nbd_device *nbd)
2057	{
2058	struct nbd_config *config = nbd->config;
2059	u64 bsize = nbd_blksize(config);
2060	u64 bytes = config->bytesize;
2061
2062	if (info->attrs[NBD_ATTR_SIZE_BYTES])
2063	bytes = nla_get_u64(nla: info->attrs[NBD_ATTR_SIZE_BYTES]);
2064
2065	if (info->attrs[NBD_ATTR_BLOCK_SIZE_BYTES])
2066	bsize = nla_get_u64(nla: info->attrs[NBD_ATTR_BLOCK_SIZE_BYTES]);
2067
2068	if (bytes != config->bytesize || bsize != nbd_blksize(config))
2069	return nbd_set_size(nbd, bytesize: bytes, blksize: bsize);
2070	return 0;
2071	}
2072
2073	static int nbd_genl_connect(struct sk_buff *skb, struct genl_info *info)
2074	{
2075	struct nbd_device *nbd;
2076	struct nbd_config *config;
2077	int index = -1;
2078	int ret;
2079	bool put_dev = false;
2080
2081	if (!netlink_capable(skb, CAP_SYS_ADMIN))
2082	return -EPERM;
2083
2084	if (info->attrs[NBD_ATTR_INDEX]) {
2085	index = nla_get_u32(nla: info->attrs[NBD_ATTR_INDEX]);
2086
2087	/*
2088	* Too big first_minor can cause duplicate creation of
2089	* sysfs files/links, since index << part_shift might overflow, or
2090	* MKDEV() expect that the max bits of first_minor is 20.
2091	*/
2092	if (index < 0 || index > MINORMASK >> part_shift) {
2093	pr_err("illegal input index %d\n", index);
2094	return -EINVAL;
2095	}
2096	}
2097	if (GENL_REQ_ATTR_CHECK(info, NBD_ATTR_SOCKETS)) {
2098	pr_err("must specify at least one socket\n");
2099	return -EINVAL;
2100	}
2101	if (GENL_REQ_ATTR_CHECK(info, NBD_ATTR_SIZE_BYTES)) {
2102	pr_err("must specify a size in bytes for the device\n");
2103	return -EINVAL;
2104	}
2105	again:
2106	mutex_lock(&nbd_index_mutex);
2107	if (index == -1) {
2108	nbd = nbd_find_get_unused();
2109	} else {
2110	nbd = idr_find(&nbd_index_idr, id: index);
2111	if (nbd) {
2112	if ((test_bit(NBD_DESTROY_ON_DISCONNECT, &nbd->flags) &&
2113	test_bit(NBD_DISCONNECT_REQUESTED, &nbd->flags)) ||
2114	!refcount_inc_not_zero(r: &nbd->refs)) {
2115	mutex_unlock(lock: &nbd_index_mutex);
2116	pr_err("device at index %d is going down\n",
2117	index);
2118	return -EINVAL;
2119	}
2120	}
2121	}
2122	mutex_unlock(lock: &nbd_index_mutex);
2123
2124	if (!nbd) {
2125	nbd = nbd_dev_add(index, refs: 2);
2126	if (IS_ERR(ptr: nbd)) {
2127	pr_err("failed to add new device\n");
2128	return PTR_ERR(ptr: nbd);
2129	}
2130	}
2131
2132	mutex_lock(&nbd->config_lock);
2133	if (refcount_read(r: &nbd->config_refs)) {
2134	mutex_unlock(lock: &nbd->config_lock);
2135	nbd_put(nbd);
2136	if (index == -1)
2137	goto again;
2138	pr_err("nbd%d already in use\n", index);
2139	return -EBUSY;
2140	}
2141
2142	ret = nbd_alloc_and_init_config(nbd);
2143	if (ret) {
2144	mutex_unlock(lock: &nbd->config_lock);
2145	nbd_put(nbd);
2146	pr_err("couldn't allocate config\n");
2147	return ret;
2148	}
2149
2150	config = nbd->config;
2151	set_bit(NBD_RT_BOUND, addr: &config->runtime_flags);
2152	ret = nbd_genl_size_set(info, nbd);
2153	if (ret)
2154	goto out;
2155
2156	if (info->attrs[NBD_ATTR_TIMEOUT])
2157	nbd_set_cmd_timeout(nbd,
2158	timeout: nla_get_u64(nla: info->attrs[NBD_ATTR_TIMEOUT]));
2159	if (info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]) {
2160	config->dead_conn_timeout =
2161	nla_get_u64(nla: info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]);
2162	config->dead_conn_timeout *= HZ;
2163	}
2164	if (info->attrs[NBD_ATTR_SERVER_FLAGS])
2165	config->flags =
2166	nla_get_u64(nla: info->attrs[NBD_ATTR_SERVER_FLAGS]);
2167	if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {
2168	u64 flags = nla_get_u64(nla: info->attrs[NBD_ATTR_CLIENT_FLAGS]);
2169	if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {
2170	/*
2171	* We have 1 ref to keep the device around, and then 1
2172	* ref for our current operation here, which will be
2173	* inherited by the config. If we already have
2174	* DESTROY_ON_DISCONNECT set then we know we don't have
2175	* that extra ref already held so we don't need the
2176	* put_dev.
2177	*/
2178	if (!test_and_set_bit(NBD_DESTROY_ON_DISCONNECT,
2179	addr: &nbd->flags))
2180	put_dev = true;
2181	} else {
2182	if (test_and_clear_bit(NBD_DESTROY_ON_DISCONNECT,
2183	addr: &nbd->flags))
2184	refcount_inc(r: &nbd->refs);
2185	}
2186	if (flags & NBD_CFLAG_DISCONNECT_ON_CLOSE) {
2187	set_bit(NBD_RT_DISCONNECT_ON_CLOSE,
2188	addr: &config->runtime_flags);
2189	}
2190	}
2191
2192	if (info->attrs[NBD_ATTR_SOCKETS]) {
2193	struct nlattr *attr;
2194	int rem, fd;
2195
2196	nla_for_each_nested(attr, info->attrs[NBD_ATTR_SOCKETS],
2197	rem) {
2198	struct nlattr *socks[NBD_SOCK_MAX+1];
2199
2200	if (nla_type(nla: attr) != NBD_SOCK_ITEM) {
2201	pr_err("socks must be embedded in a SOCK_ITEM attr\n");
2202	ret = -EINVAL;
2203	goto out;
2204	}
2205	ret = nla_parse_nested_deprecated(tb: socks, NBD_SOCK_MAX,
2206	nla: attr,
2207	policy: nbd_sock_policy,
2208	extack: info->extack);
2209	if (ret != 0) {
2210	pr_err("error processing sock list\n");
2211	ret = -EINVAL;
2212	goto out;
2213	}
2214	if (!socks[NBD_SOCK_FD])
2215	continue;
2216	fd = (int)nla_get_u32(nla: socks[NBD_SOCK_FD]);
2217	ret = nbd_add_socket(nbd, arg: fd, netlink: true);
2218	if (ret)
2219	goto out;
2220	}
2221	}
2222
2223	if (info->attrs[NBD_ATTR_BACKEND_IDENTIFIER]) {
2224	nbd->backend = nla_strdup(nla: info->attrs[NBD_ATTR_BACKEND_IDENTIFIER],
2225	GFP_KERNEL);
2226	if (!nbd->backend) {
2227	ret = -ENOMEM;
2228	goto out;
2229	}
2230	}
2231	ret = device_create_file(disk_to_dev(nbd->disk), entry: &backend_attr);
2232	if (ret) {
2233	dev_err(disk_to_dev(nbd->disk),
2234	"device_create_file failed for backend!\n");
2235	goto out;
2236	}
2237	set_bit(NBD_RT_HAS_BACKEND_FILE, addr: &config->runtime_flags);
2238
2239	ret = nbd_start_device(nbd);
2240	out:
2241	if (!ret) {
2242	set_bit(NBD_RT_HAS_CONFIG_REF, addr: &config->runtime_flags);
2243	refcount_inc(r: &nbd->config_refs);
2244	nbd_connect_reply(info, index: nbd->index);
2245	}
2246	mutex_unlock(lock: &nbd->config_lock);
2247
2248	nbd_config_put(nbd);
2249	if (put_dev)
2250	nbd_put(nbd);
2251	return ret;
2252	}
2253
2254	static void nbd_disconnect_and_put(struct nbd_device *nbd)
2255	{
2256	mutex_lock(&nbd->config_lock);
2257	nbd_disconnect(nbd);
2258	sock_shutdown(nbd);
2259	wake_up(&nbd->config->conn_wait);
2260	/*
2261	* Make sure recv thread has finished, we can safely call nbd_clear_que()
2262	* to cancel the inflight I/Os.
2263	*/
2264	flush_workqueue(nbd->recv_workq);
2265	nbd_clear_que(nbd);
2266	nbd->task_setup = NULL;
2267	clear_bit(NBD_RT_BOUND, addr: &nbd->config->runtime_flags);
2268	mutex_unlock(lock: &nbd->config_lock);
2269
2270	if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF,
2271	addr: &nbd->config->runtime_flags))
2272	nbd_config_put(nbd);
2273	}
2274
2275	static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
2276	{
2277	struct nbd_device *nbd;
2278	int index;
2279
2280	if (!netlink_capable(skb, CAP_SYS_ADMIN))
2281	return -EPERM;
2282
2283	if (GENL_REQ_ATTR_CHECK(info, NBD_ATTR_INDEX)) {
2284	pr_err("must specify an index to disconnect\n");
2285	return -EINVAL;
2286	}
2287	index = nla_get_u32(nla: info->attrs[NBD_ATTR_INDEX]);
2288	mutex_lock(&nbd_index_mutex);
2289	nbd = idr_find(&nbd_index_idr, id: index);
2290	if (!nbd) {
2291	mutex_unlock(lock: &nbd_index_mutex);
2292	pr_err("couldn't find device at index %d\n", index);
2293	return -EINVAL;
2294	}
2295	if (!refcount_inc_not_zero(r: &nbd->refs)) {
2296	mutex_unlock(lock: &nbd_index_mutex);
2297	pr_err("device at index %d is going down\n", index);
2298	return -EINVAL;
2299	}
2300	mutex_unlock(lock: &nbd_index_mutex);
2301	if (!refcount_inc_not_zero(r: &nbd->config_refs))
2302	goto put_nbd;
2303	nbd_disconnect_and_put(nbd);
2304	nbd_config_put(nbd);
2305	put_nbd:
2306	nbd_put(nbd);
2307	return 0;
2308	}
2309
2310	static int nbd_genl_reconfigure(struct sk_buff *skb, struct genl_info *info)
2311	{
2312	struct nbd_device *nbd = NULL;
2313	struct nbd_config *config;
2314	int index;
2315	int ret = 0;
2316	bool put_dev = false;
2317
2318	if (!netlink_capable(skb, CAP_SYS_ADMIN))
2319	return -EPERM;
2320
2321	if (GENL_REQ_ATTR_CHECK(info, NBD_ATTR_INDEX)) {
2322	pr_err("must specify a device to reconfigure\n");
2323	return -EINVAL;
2324	}
2325	index = nla_get_u32(nla: info->attrs[NBD_ATTR_INDEX]);
2326	mutex_lock(&nbd_index_mutex);
2327	nbd = idr_find(&nbd_index_idr, id: index);
2328	if (!nbd) {
2329	mutex_unlock(lock: &nbd_index_mutex);
2330	pr_err("couldn't find a device at index %d\n", index);
2331	return -EINVAL;
2332	}
2333	if (nbd->backend) {
2334	if (info->attrs[NBD_ATTR_BACKEND_IDENTIFIER]) {
2335	if (nla_strcmp(nla: info->attrs[NBD_ATTR_BACKEND_IDENTIFIER],
2336	str: nbd->backend)) {
2337	mutex_unlock(lock: &nbd_index_mutex);
2338	dev_err(nbd_to_dev(nbd),
2339	"backend image doesn't match with %s\n",
2340	nbd->backend);
2341	return -EINVAL;
2342	}
2343	} else {
2344	mutex_unlock(lock: &nbd_index_mutex);
2345	dev_err(nbd_to_dev(nbd), "must specify backend\n");
2346	return -EINVAL;
2347	}
2348	}
2349	if (!refcount_inc_not_zero(r: &nbd->refs)) {
2350	mutex_unlock(lock: &nbd_index_mutex);
2351	pr_err("device at index %d is going down\n", index);
2352	return -EINVAL;
2353	}
2354	mutex_unlock(lock: &nbd_index_mutex);
2355
2356	config = nbd_get_config_unlocked(nbd);
2357	if (!config) {
2358	dev_err(nbd_to_dev(nbd),
2359	"not configured, cannot reconfigure\n");
2360	nbd_put(nbd);
2361	return -EINVAL;
2362	}
2363
2364	mutex_lock(&nbd->config_lock);
2365	if (!test_bit(NBD_RT_BOUND, &config->runtime_flags) ||
2366	!nbd->pid) {
2367	dev_err(nbd_to_dev(nbd),
2368	"not configured, cannot reconfigure\n");
2369	ret = -EINVAL;
2370	goto out;
2371	}
2372
2373	ret = nbd_genl_size_set(info, nbd);
2374	if (ret)
2375	goto out;
2376
2377	if (info->attrs[NBD_ATTR_TIMEOUT])
2378	nbd_set_cmd_timeout(nbd,
2379	timeout: nla_get_u64(nla: info->attrs[NBD_ATTR_TIMEOUT]));
2380	if (info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]) {
2381	config->dead_conn_timeout =
2382	nla_get_u64(nla: info->attrs[NBD_ATTR_DEAD_CONN_TIMEOUT]);
2383	config->dead_conn_timeout *= HZ;
2384	}
2385	if (info->attrs[NBD_ATTR_CLIENT_FLAGS]) {
2386	u64 flags = nla_get_u64(nla: info->attrs[NBD_ATTR_CLIENT_FLAGS]);
2387	if (flags & NBD_CFLAG_DESTROY_ON_DISCONNECT) {
2388	if (!test_and_set_bit(NBD_DESTROY_ON_DISCONNECT,
2389	addr: &nbd->flags))
2390	put_dev = true;
2391	} else {
2392	if (test_and_clear_bit(NBD_DESTROY_ON_DISCONNECT,
2393	addr: &nbd->flags))
2394	refcount_inc(r: &nbd->refs);
2395	}
2396
2397	if (flags & NBD_CFLAG_DISCONNECT_ON_CLOSE) {
2398	set_bit(NBD_RT_DISCONNECT_ON_CLOSE,
2399	addr: &config->runtime_flags);
2400	} else {
2401	clear_bit(NBD_RT_DISCONNECT_ON_CLOSE,
2402	addr: &config->runtime_flags);
2403	}
2404	}
2405
2406	if (info->attrs[NBD_ATTR_SOCKETS]) {
2407	struct nlattr *attr;
2408	int rem, fd;
2409
2410	nla_for_each_nested(attr, info->attrs[NBD_ATTR_SOCKETS],
2411	rem) {
2412	struct nlattr *socks[NBD_SOCK_MAX+1];
2413
2414	if (nla_type(nla: attr) != NBD_SOCK_ITEM) {
2415	pr_err("socks must be embedded in a SOCK_ITEM attr\n");
2416	ret = -EINVAL;
2417	goto out;
2418	}
2419	ret = nla_parse_nested_deprecated(tb: socks, NBD_SOCK_MAX,
2420	nla: attr,
2421	policy: nbd_sock_policy,
2422	extack: info->extack);
2423	if (ret != 0) {
2424	pr_err("error processing sock list\n");
2425	ret = -EINVAL;
2426	goto out;
2427	}
2428	if (!socks[NBD_SOCK_FD])
2429	continue;
2430	fd = (int)nla_get_u32(nla: socks[NBD_SOCK_FD]);
2431	ret = nbd_reconnect_socket(nbd, arg: fd);
2432	if (ret) {
2433	if (ret == -ENOSPC)
2434	ret = 0;
2435	goto out;
2436	}
2437	dev_info(nbd_to_dev(nbd), "reconnected socket\n");
2438	}
2439	}
2440	out:
2441	mutex_unlock(lock: &nbd->config_lock);
2442	nbd_config_put(nbd);
2443	nbd_put(nbd);
2444	if (put_dev)
2445	nbd_put(nbd);
2446	return ret;
2447	}
2448
2449	static const struct genl_small_ops nbd_connect_genl_ops[] = {
2450	{
2451	.cmd = NBD_CMD_CONNECT,
2452	.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2453	.doit = nbd_genl_connect,
2454	},
2455	{
2456	.cmd = NBD_CMD_DISCONNECT,
2457	.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2458	.doit = nbd_genl_disconnect,
2459	},
2460	{
2461	.cmd = NBD_CMD_RECONFIGURE,
2462	.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2463	.doit = nbd_genl_reconfigure,
2464	},
2465	{
2466	.cmd = NBD_CMD_STATUS,
2467	.validate = GENL_DONT_VALIDATE_STRICT | GENL_DONT_VALIDATE_DUMP,
2468	.doit = nbd_genl_status,
2469	},
2470	};
2471
2472	static const struct genl_multicast_group nbd_mcast_grps[] = {
2473	{ .name = NBD_GENL_MCAST_GROUP_NAME, },
2474	};
2475
2476	static struct genl_family nbd_genl_family __ro_after_init = {
2477	.hdrsize = 0,
2478	.name = NBD_GENL_FAMILY_NAME,
2479	.version = NBD_GENL_VERSION,
2480	.module = THIS_MODULE,
2481	.small_ops = nbd_connect_genl_ops,
2482	.n_small_ops = ARRAY_SIZE(nbd_connect_genl_ops),
2483	.resv_start_op = NBD_CMD_STATUS + 1,
2484	.maxattr = NBD_ATTR_MAX,
2485	.netnsok = 1,
2486	.policy = nbd_attr_policy,
2487	.mcgrps = nbd_mcast_grps,
2488	.n_mcgrps = ARRAY_SIZE(nbd_mcast_grps),
2489	};
2490	MODULE_ALIAS_GENL_FAMILY(NBD_GENL_FAMILY_NAME);
2491
2492	static int populate_nbd_status(struct nbd_device *nbd, struct sk_buff *reply)
2493	{
2494	struct nlattr *dev_opt;
2495	u8 connected = 0;
2496	int ret;
2497
2498	/* This is a little racey, but for status it's ok. The
2499	* reason we don't take a ref here is because we can't
2500	* take a ref in the index == -1 case as we would need
2501	* to put under the nbd_index_mutex, which could
2502	* deadlock if we are configured to remove ourselves
2503	* once we're disconnected.
2504	*/
2505	if (refcount_read(r: &nbd->config_refs))
2506	connected = 1;
2507	dev_opt = nla_nest_start_noflag(skb: reply, attrtype: NBD_DEVICE_ITEM);
2508	if (!dev_opt)
2509	return -EMSGSIZE;
2510	ret = nla_put_u32(skb: reply, attrtype: NBD_DEVICE_INDEX, value: nbd->index);
2511	if (ret)
2512	return -EMSGSIZE;
2513	ret = nla_put_u8(skb: reply, attrtype: NBD_DEVICE_CONNECTED,
2514	value: connected);
2515	if (ret)
2516	return -EMSGSIZE;
2517	nla_nest_end(skb: reply, start: dev_opt);
2518	return 0;
2519	}
2520
2521	static int status_cb(int id, void *ptr, void *data)
2522	{
2523	struct nbd_device *nbd = ptr;
2524	return populate_nbd_status(nbd, reply: (struct sk_buff *)data);
2525	}
2526
2527	static int nbd_genl_status(struct sk_buff *skb, struct genl_info *info)
2528	{
2529	struct nlattr *dev_list;
2530	struct sk_buff *reply;
2531	void *reply_head;
2532	size_t msg_size;
2533	int index = -1;
2534	int ret = -ENOMEM;
2535
2536	if (info->attrs[NBD_ATTR_INDEX])
2537	index = nla_get_u32(nla: info->attrs[NBD_ATTR_INDEX]);
2538
2539	mutex_lock(&nbd_index_mutex);
2540
2541	msg_size = nla_total_size(payload: nla_attr_size(payload: sizeof(u32)) +
2542	nla_attr_size(payload: sizeof(u8)));
2543	msg_size *= (index == -1) ? nbd_total_devices : 1;
2544
2545	reply = genlmsg_new(payload: msg_size, GFP_KERNEL);
2546	if (!reply)
2547	goto out;
2548	reply_head = genlmsg_put_reply(skb: reply, info, family: &nbd_genl_family, flags: 0,
2549	cmd: NBD_CMD_STATUS);
2550	if (!reply_head) {
2551	nlmsg_free(skb: reply);
2552	goto out;
2553	}
2554
2555	dev_list = nla_nest_start_noflag(skb: reply, attrtype: NBD_ATTR_DEVICE_LIST);
2556	if (!dev_list) {
2557	nlmsg_free(skb: reply);
2558	ret = -EMSGSIZE;
2559	goto out;
2560	}
2561
2562	if (index == -1) {
2563	ret = idr_for_each(&nbd_index_idr, fn: &status_cb, data: reply);
2564	if (ret) {
2565	nlmsg_free(skb: reply);
2566	goto out;
2567	}
2568	} else {
2569	struct nbd_device *nbd;
2570	nbd = idr_find(&nbd_index_idr, id: index);
2571	if (nbd) {
2572	ret = populate_nbd_status(nbd, reply);
2573	if (ret) {
2574	nlmsg_free(skb: reply);
2575	goto out;
2576	}
2577	}
2578	}
2579	nla_nest_end(skb: reply, start: dev_list);
2580	genlmsg_end(skb: reply, hdr: reply_head);
2581	ret = genlmsg_reply(skb: reply, info);
2582	out:
2583	mutex_unlock(lock: &nbd_index_mutex);
2584	return ret;
2585	}
2586
2587	static void nbd_connect_reply(struct genl_info *info, int index)
2588	{
2589	struct sk_buff *skb;
2590	void *msg_head;
2591	int ret;
2592
2593	skb = genlmsg_new(payload: nla_total_size(payload: sizeof(u32)), GFP_KERNEL);
2594	if (!skb)
2595	return;
2596	msg_head = genlmsg_put_reply(skb, info, family: &nbd_genl_family, flags: 0,
2597	cmd: NBD_CMD_CONNECT);
2598	if (!msg_head) {
2599	nlmsg_free(skb);
2600	return;
2601	}
2602	ret = nla_put_u32(skb, attrtype: NBD_ATTR_INDEX, value: index);
2603	if (ret) {
2604	nlmsg_free(skb);
2605	return;
2606	}
2607	genlmsg_end(skb, hdr: msg_head);
2608	genlmsg_reply(skb, info);
2609	}
2610
2611	static void nbd_mcast_index(int index)
2612	{
2613	struct sk_buff *skb;
2614	void *msg_head;
2615	int ret;
2616
2617	skb = genlmsg_new(payload: nla_total_size(payload: sizeof(u32)), GFP_KERNEL);
2618	if (!skb)
2619	return;
2620	msg_head = genlmsg_put(skb, portid: 0, seq: 0, family: &nbd_genl_family, flags: 0,
2621	cmd: NBD_CMD_LINK_DEAD);
2622	if (!msg_head) {
2623	nlmsg_free(skb);
2624	return;
2625	}
2626	ret = nla_put_u32(skb, attrtype: NBD_ATTR_INDEX, value: index);
2627	if (ret) {
2628	nlmsg_free(skb);
2629	return;
2630	}
2631	genlmsg_end(skb, hdr: msg_head);
2632	genlmsg_multicast(family: &nbd_genl_family, skb, portid: 0, group: 0, GFP_KERNEL);
2633	}
2634
2635	static void nbd_dead_link_work(struct work_struct *work)
2636	{
2637	struct link_dead_args *args = container_of(work, struct link_dead_args,
2638	work);
2639	nbd_mcast_index(index: args->index);
2640	kfree(objp: args);
2641	}
2642
2643	static int __init nbd_init(void)
2644	{
2645	int i;
2646
2647	BUILD_BUG_ON(sizeof(struct nbd_request) != 28);
2648
2649	if (max_part < 0) {
2650	pr_err("max_part must be >= 0\n");
2651	return -EINVAL;
2652	}
2653
2654	part_shift = 0;
2655	if (max_part > 0) {
2656	part_shift = fls(x: max_part);
2657
2658	/*
2659	* Adjust max_part according to part_shift as it is exported
2660	* to user space so that user can know the max number of
2661	* partition kernel should be able to manage.
2662	*
2663	* Note that -1 is required because partition 0 is reserved
2664	* for the whole disk.
2665	*/
2666	max_part = (1UL << part_shift) - 1;
2667	}
2668
2669	if ((1UL << part_shift) > DISK_MAX_PARTS)
2670	return -EINVAL;
2671
2672	if (nbds_max > 1UL << (MINORBITS - part_shift))
2673	return -EINVAL;
2674
2675	if (register_blkdev(NBD_MAJOR, "nbd"))
2676	return -EIO;
2677
2678	nbd_del_wq = alloc_workqueue("nbd-del", WQ_UNBOUND, 0);
2679	if (!nbd_del_wq) {
2680	unregister_blkdev(NBD_MAJOR, name: "nbd");
2681	return -ENOMEM;
2682	}
2683
2684	if (genl_register_family(family: &nbd_genl_family)) {
2685	destroy_workqueue(wq: nbd_del_wq);
2686	unregister_blkdev(NBD_MAJOR, name: "nbd");
2687	return -EINVAL;
2688	}
2689	nbd_dbg_init();
2690
2691	for (i = 0; i < nbds_max; i++)
2692	nbd_dev_add(index: i, refs: 1);
2693	return 0;
2694	}
2695
2696	static int nbd_exit_cb(int id, void *ptr, void *data)
2697	{
2698	struct list_head *list = (struct list_head *)data;
2699	struct nbd_device *nbd = ptr;
2700
2701	/* Skip nbd that is being removed asynchronously */
2702	if (refcount_read(r: &nbd->refs))
2703	list_add_tail(new: &nbd->list, head: list);
2704
2705	return 0;
2706	}
2707
2708	static void __exit nbd_cleanup(void)
2709	{
2710	struct nbd_device *nbd;
2711	LIST_HEAD(del_list);
2712
2713	/*
2714	* Unregister netlink interface prior to waiting
2715	* for the completion of netlink commands.
2716	*/
2717	genl_unregister_family(family: &nbd_genl_family);
2718
2719	nbd_dbg_close();
2720
2721	mutex_lock(&nbd_index_mutex);
2722	idr_for_each(&nbd_index_idr, fn: &nbd_exit_cb, data: &del_list);
2723	mutex_unlock(lock: &nbd_index_mutex);
2724
2725	while (!list_empty(head: &del_list)) {
2726	nbd = list_first_entry(&del_list, struct nbd_device, list);
2727	list_del_init(entry: &nbd->list);
2728	if (refcount_read(r: &nbd->config_refs))
2729	pr_err("possibly leaking nbd_config (ref %d)\n",
2730	refcount_read(&nbd->config_refs));
2731	if (refcount_read(r: &nbd->refs) != 1)
2732	pr_err("possibly leaking a device\n");
2733	nbd_put(nbd);
2734	}
2735
2736	/* Also wait for nbd_dev_remove_work() completes */
2737	destroy_workqueue(wq: nbd_del_wq);
2738
2739	idr_destroy(&nbd_index_idr);
2740	unregister_blkdev(NBD_MAJOR, name: "nbd");
2741	}
2742
2743	module_init(nbd_init);
2744	module_exit(nbd_cleanup);
2745
2746	MODULE_DESCRIPTION("Network Block Device");
2747	MODULE_LICENSE("GPL");
2748
2749	module_param(nbds_max, int, 0444);
2750	MODULE_PARM_DESC(nbds_max, "number of network block devices to initialize (default: 16)");
2751	module_param(max_part, int, 0444);
2752	MODULE_PARM_DESC(max_part, "number of partitions per device (default: 16)");
2753