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