xref: /openbmc/linux/drivers/nvme/host/multipath.c (revision f97769fd)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (c) 2017-2018 Christoph Hellwig.
4  */
5 
6 #include <linux/backing-dev.h>
7 #include <linux/moduleparam.h>
8 #include <trace/events/block.h>
9 #include "nvme.h"
10 
11 static bool multipath = true;
12 module_param(multipath, bool, 0444);
13 MODULE_PARM_DESC(multipath,
14 	"turn on native support for multiple controllers per subsystem");
15 
16 void nvme_mpath_unfreeze(struct nvme_subsystem *subsys)
17 {
18 	struct nvme_ns_head *h;
19 
20 	lockdep_assert_held(&subsys->lock);
21 	list_for_each_entry(h, &subsys->nsheads, entry)
22 		if (h->disk)
23 			blk_mq_unfreeze_queue(h->disk->queue);
24 }
25 
26 void nvme_mpath_wait_freeze(struct nvme_subsystem *subsys)
27 {
28 	struct nvme_ns_head *h;
29 
30 	lockdep_assert_held(&subsys->lock);
31 	list_for_each_entry(h, &subsys->nsheads, entry)
32 		if (h->disk)
33 			blk_mq_freeze_queue_wait(h->disk->queue);
34 }
35 
36 void nvme_mpath_start_freeze(struct nvme_subsystem *subsys)
37 {
38 	struct nvme_ns_head *h;
39 
40 	lockdep_assert_held(&subsys->lock);
41 	list_for_each_entry(h, &subsys->nsheads, entry)
42 		if (h->disk)
43 			blk_freeze_queue_start(h->disk->queue);
44 }
45 
46 /*
47  * If multipathing is enabled we need to always use the subsystem instance
48  * number for numbering our devices to avoid conflicts between subsystems that
49  * have multiple controllers and thus use the multipath-aware subsystem node
50  * and those that have a single controller and use the controller node
51  * directly.
52  */
53 void nvme_set_disk_name(char *disk_name, struct nvme_ns *ns,
54 			struct nvme_ctrl *ctrl, int *flags)
55 {
56 	if (!multipath) {
57 		sprintf(disk_name, "nvme%dn%d", ctrl->instance, ns->head->instance);
58 	} else if (ns->head->disk) {
59 		sprintf(disk_name, "nvme%dc%dn%d", ctrl->subsys->instance,
60 				ctrl->instance, ns->head->instance);
61 		*flags = GENHD_FL_HIDDEN;
62 	} else {
63 		sprintf(disk_name, "nvme%dn%d", ctrl->subsys->instance,
64 				ns->head->instance);
65 	}
66 }
67 
68 void nvme_failover_req(struct request *req)
69 {
70 	struct nvme_ns *ns = req->q->queuedata;
71 	u16 status = nvme_req(req)->status & 0x7ff;
72 	unsigned long flags;
73 
74 	nvme_mpath_clear_current_path(ns);
75 
76 	/*
77 	 * If we got back an ANA error, we know the controller is alive but not
78 	 * ready to serve this namespace.  Kick of a re-read of the ANA
79 	 * information page, and just try any other available path for now.
80 	 */
81 	if (nvme_is_ana_error(status) && ns->ctrl->ana_log_buf) {
82 		set_bit(NVME_NS_ANA_PENDING, &ns->flags);
83 		queue_work(nvme_wq, &ns->ctrl->ana_work);
84 	}
85 
86 	spin_lock_irqsave(&ns->head->requeue_lock, flags);
87 	blk_steal_bios(&ns->head->requeue_list, req);
88 	spin_unlock_irqrestore(&ns->head->requeue_lock, flags);
89 
90 	blk_mq_end_request(req, 0);
91 	kblockd_schedule_work(&ns->head->requeue_work);
92 }
93 
94 void nvme_kick_requeue_lists(struct nvme_ctrl *ctrl)
95 {
96 	struct nvme_ns *ns;
97 
98 	down_read(&ctrl->namespaces_rwsem);
99 	list_for_each_entry(ns, &ctrl->namespaces, list) {
100 		if (ns->head->disk)
101 			kblockd_schedule_work(&ns->head->requeue_work);
102 	}
103 	up_read(&ctrl->namespaces_rwsem);
104 }
105 
106 static const char *nvme_ana_state_names[] = {
107 	[0]				= "invalid state",
108 	[NVME_ANA_OPTIMIZED]		= "optimized",
109 	[NVME_ANA_NONOPTIMIZED]		= "non-optimized",
110 	[NVME_ANA_INACCESSIBLE]		= "inaccessible",
111 	[NVME_ANA_PERSISTENT_LOSS]	= "persistent-loss",
112 	[NVME_ANA_CHANGE]		= "change",
113 };
114 
115 bool nvme_mpath_clear_current_path(struct nvme_ns *ns)
116 {
117 	struct nvme_ns_head *head = ns->head;
118 	bool changed = false;
119 	int node;
120 
121 	if (!head)
122 		goto out;
123 
124 	for_each_node(node) {
125 		if (ns == rcu_access_pointer(head->current_path[node])) {
126 			rcu_assign_pointer(head->current_path[node], NULL);
127 			changed = true;
128 		}
129 	}
130 out:
131 	return changed;
132 }
133 
134 void nvme_mpath_clear_ctrl_paths(struct nvme_ctrl *ctrl)
135 {
136 	struct nvme_ns *ns;
137 
138 	mutex_lock(&ctrl->scan_lock);
139 	down_read(&ctrl->namespaces_rwsem);
140 	list_for_each_entry(ns, &ctrl->namespaces, list)
141 		if (nvme_mpath_clear_current_path(ns))
142 			kblockd_schedule_work(&ns->head->requeue_work);
143 	up_read(&ctrl->namespaces_rwsem);
144 	mutex_unlock(&ctrl->scan_lock);
145 }
146 
147 static bool nvme_path_is_disabled(struct nvme_ns *ns)
148 {
149 	/*
150 	 * We don't treat NVME_CTRL_DELETING as a disabled path as I/O should
151 	 * still be able to complete assuming that the controller is connected.
152 	 * Otherwise it will fail immediately and return to the requeue list.
153 	 */
154 	if (ns->ctrl->state != NVME_CTRL_LIVE &&
155 	    ns->ctrl->state != NVME_CTRL_DELETING)
156 		return true;
157 	if (test_bit(NVME_NS_ANA_PENDING, &ns->flags) ||
158 	    test_bit(NVME_NS_REMOVING, &ns->flags))
159 		return true;
160 	return false;
161 }
162 
163 static struct nvme_ns *__nvme_find_path(struct nvme_ns_head *head, int node)
164 {
165 	int found_distance = INT_MAX, fallback_distance = INT_MAX, distance;
166 	struct nvme_ns *found = NULL, *fallback = NULL, *ns;
167 
168 	list_for_each_entry_rcu(ns, &head->list, siblings) {
169 		if (nvme_path_is_disabled(ns))
170 			continue;
171 
172 		if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_NUMA)
173 			distance = node_distance(node, ns->ctrl->numa_node);
174 		else
175 			distance = LOCAL_DISTANCE;
176 
177 		switch (ns->ana_state) {
178 		case NVME_ANA_OPTIMIZED:
179 			if (distance < found_distance) {
180 				found_distance = distance;
181 				found = ns;
182 			}
183 			break;
184 		case NVME_ANA_NONOPTIMIZED:
185 			if (distance < fallback_distance) {
186 				fallback_distance = distance;
187 				fallback = ns;
188 			}
189 			break;
190 		default:
191 			break;
192 		}
193 	}
194 
195 	if (!found)
196 		found = fallback;
197 	if (found)
198 		rcu_assign_pointer(head->current_path[node], found);
199 	return found;
200 }
201 
202 static struct nvme_ns *nvme_next_ns(struct nvme_ns_head *head,
203 		struct nvme_ns *ns)
204 {
205 	ns = list_next_or_null_rcu(&head->list, &ns->siblings, struct nvme_ns,
206 			siblings);
207 	if (ns)
208 		return ns;
209 	return list_first_or_null_rcu(&head->list, struct nvme_ns, siblings);
210 }
211 
212 static struct nvme_ns *nvme_round_robin_path(struct nvme_ns_head *head,
213 		int node, struct nvme_ns *old)
214 {
215 	struct nvme_ns *ns, *found = NULL;
216 
217 	if (list_is_singular(&head->list)) {
218 		if (nvme_path_is_disabled(old))
219 			return NULL;
220 		return old;
221 	}
222 
223 	for (ns = nvme_next_ns(head, old);
224 	     ns != old;
225 	     ns = nvme_next_ns(head, ns)) {
226 		if (nvme_path_is_disabled(ns))
227 			continue;
228 
229 		if (ns->ana_state == NVME_ANA_OPTIMIZED) {
230 			found = ns;
231 			goto out;
232 		}
233 		if (ns->ana_state == NVME_ANA_NONOPTIMIZED)
234 			found = ns;
235 	}
236 
237 	/*
238 	 * The loop above skips the current path for round-robin semantics.
239 	 * Fall back to the current path if either:
240 	 *  - no other optimized path found and current is optimized,
241 	 *  - no other usable path found and current is usable.
242 	 */
243 	if (!nvme_path_is_disabled(old) &&
244 	    (old->ana_state == NVME_ANA_OPTIMIZED ||
245 	     (!found && old->ana_state == NVME_ANA_NONOPTIMIZED)))
246 		return old;
247 
248 	if (!found)
249 		return NULL;
250 out:
251 	rcu_assign_pointer(head->current_path[node], found);
252 	return found;
253 }
254 
255 static inline bool nvme_path_is_optimized(struct nvme_ns *ns)
256 {
257 	return ns->ctrl->state == NVME_CTRL_LIVE &&
258 		ns->ana_state == NVME_ANA_OPTIMIZED;
259 }
260 
261 inline struct nvme_ns *nvme_find_path(struct nvme_ns_head *head)
262 {
263 	int node = numa_node_id();
264 	struct nvme_ns *ns;
265 
266 	ns = srcu_dereference(head->current_path[node], &head->srcu);
267 	if (unlikely(!ns))
268 		return __nvme_find_path(head, node);
269 
270 	if (READ_ONCE(head->subsys->iopolicy) == NVME_IOPOLICY_RR)
271 		return nvme_round_robin_path(head, node, ns);
272 	if (unlikely(!nvme_path_is_optimized(ns)))
273 		return __nvme_find_path(head, node);
274 	return ns;
275 }
276 
277 static bool nvme_available_path(struct nvme_ns_head *head)
278 {
279 	struct nvme_ns *ns;
280 
281 	list_for_each_entry_rcu(ns, &head->list, siblings) {
282 		switch (ns->ctrl->state) {
283 		case NVME_CTRL_LIVE:
284 		case NVME_CTRL_RESETTING:
285 		case NVME_CTRL_CONNECTING:
286 			/* fallthru */
287 			return true;
288 		default:
289 			break;
290 		}
291 	}
292 	return false;
293 }
294 
295 blk_qc_t nvme_ns_head_submit_bio(struct bio *bio)
296 {
297 	struct nvme_ns_head *head = bio->bi_disk->private_data;
298 	struct device *dev = disk_to_dev(head->disk);
299 	struct nvme_ns *ns;
300 	blk_qc_t ret = BLK_QC_T_NONE;
301 	int srcu_idx;
302 
303 	/*
304 	 * The namespace might be going away and the bio might be moved to a
305 	 * different queue via blk_steal_bios(), so we need to use the bio_split
306 	 * pool from the original queue to allocate the bvecs from.
307 	 */
308 	blk_queue_split(&bio);
309 
310 	srcu_idx = srcu_read_lock(&head->srcu);
311 	ns = nvme_find_path(head);
312 	if (likely(ns)) {
313 		bio->bi_disk = ns->disk;
314 		bio->bi_opf |= REQ_NVME_MPATH;
315 		trace_block_bio_remap(bio->bi_disk->queue, bio,
316 				      disk_devt(ns->head->disk),
317 				      bio->bi_iter.bi_sector);
318 		ret = submit_bio_noacct(bio);
319 	} else if (nvme_available_path(head)) {
320 		dev_warn_ratelimited(dev, "no usable path - requeuing I/O\n");
321 
322 		spin_lock_irq(&head->requeue_lock);
323 		bio_list_add(&head->requeue_list, bio);
324 		spin_unlock_irq(&head->requeue_lock);
325 	} else {
326 		dev_warn_ratelimited(dev, "no available path - failing I/O\n");
327 
328 		bio->bi_status = BLK_STS_IOERR;
329 		bio_endio(bio);
330 	}
331 
332 	srcu_read_unlock(&head->srcu, srcu_idx);
333 	return ret;
334 }
335 
336 static void nvme_requeue_work(struct work_struct *work)
337 {
338 	struct nvme_ns_head *head =
339 		container_of(work, struct nvme_ns_head, requeue_work);
340 	struct bio *bio, *next;
341 
342 	spin_lock_irq(&head->requeue_lock);
343 	next = bio_list_get(&head->requeue_list);
344 	spin_unlock_irq(&head->requeue_lock);
345 
346 	while ((bio = next) != NULL) {
347 		next = bio->bi_next;
348 		bio->bi_next = NULL;
349 
350 		/*
351 		 * Reset disk to the mpath node and resubmit to select a new
352 		 * path.
353 		 */
354 		bio->bi_disk = head->disk;
355 		submit_bio_noacct(bio);
356 	}
357 }
358 
359 int nvme_mpath_alloc_disk(struct nvme_ctrl *ctrl, struct nvme_ns_head *head)
360 {
361 	struct request_queue *q;
362 	bool vwc = false;
363 
364 	mutex_init(&head->lock);
365 	bio_list_init(&head->requeue_list);
366 	spin_lock_init(&head->requeue_lock);
367 	INIT_WORK(&head->requeue_work, nvme_requeue_work);
368 
369 	/*
370 	 * Add a multipath node if the subsystems supports multiple controllers.
371 	 * We also do this for private namespaces as the namespace sharing data could
372 	 * change after a rescan.
373 	 */
374 	if (!(ctrl->subsys->cmic & NVME_CTRL_CMIC_MULTI_CTRL) || !multipath)
375 		return 0;
376 
377 	q = blk_alloc_queue(ctrl->numa_node);
378 	if (!q)
379 		goto out;
380 	blk_queue_flag_set(QUEUE_FLAG_NONROT, q);
381 	/* set to a default value for 512 until disk is validated */
382 	blk_queue_logical_block_size(q, 512);
383 	blk_set_stacking_limits(&q->limits);
384 
385 	/* we need to propagate up the VMC settings */
386 	if (ctrl->vwc & NVME_CTRL_VWC_PRESENT)
387 		vwc = true;
388 	blk_queue_write_cache(q, vwc, vwc);
389 
390 	head->disk = alloc_disk(0);
391 	if (!head->disk)
392 		goto out_cleanup_queue;
393 	head->disk->fops = &nvme_ns_head_ops;
394 	head->disk->private_data = head;
395 	head->disk->queue = q;
396 	head->disk->flags = GENHD_FL_EXT_DEVT;
397 	sprintf(head->disk->disk_name, "nvme%dn%d",
398 			ctrl->subsys->instance, head->instance);
399 	return 0;
400 
401 out_cleanup_queue:
402 	blk_cleanup_queue(q);
403 out:
404 	return -ENOMEM;
405 }
406 
407 static void nvme_mpath_set_live(struct nvme_ns *ns)
408 {
409 	struct nvme_ns_head *head = ns->head;
410 
411 	if (!head->disk)
412 		return;
413 
414 	if (!test_and_set_bit(NVME_NSHEAD_DISK_LIVE, &head->flags))
415 		device_add_disk(&head->subsys->dev, head->disk,
416 				nvme_ns_id_attr_groups);
417 
418 	mutex_lock(&head->lock);
419 	if (nvme_path_is_optimized(ns)) {
420 		int node, srcu_idx;
421 
422 		srcu_idx = srcu_read_lock(&head->srcu);
423 		for_each_node(node)
424 			__nvme_find_path(head, node);
425 		srcu_read_unlock(&head->srcu, srcu_idx);
426 	}
427 	mutex_unlock(&head->lock);
428 
429 	synchronize_srcu(&head->srcu);
430 	kblockd_schedule_work(&head->requeue_work);
431 }
432 
433 static int nvme_parse_ana_log(struct nvme_ctrl *ctrl, void *data,
434 		int (*cb)(struct nvme_ctrl *ctrl, struct nvme_ana_group_desc *,
435 			void *))
436 {
437 	void *base = ctrl->ana_log_buf;
438 	size_t offset = sizeof(struct nvme_ana_rsp_hdr);
439 	int error, i;
440 
441 	lockdep_assert_held(&ctrl->ana_lock);
442 
443 	for (i = 0; i < le16_to_cpu(ctrl->ana_log_buf->ngrps); i++) {
444 		struct nvme_ana_group_desc *desc = base + offset;
445 		u32 nr_nsids;
446 		size_t nsid_buf_size;
447 
448 		if (WARN_ON_ONCE(offset > ctrl->ana_log_size - sizeof(*desc)))
449 			return -EINVAL;
450 
451 		nr_nsids = le32_to_cpu(desc->nnsids);
452 		nsid_buf_size = nr_nsids * sizeof(__le32);
453 
454 		if (WARN_ON_ONCE(desc->grpid == 0))
455 			return -EINVAL;
456 		if (WARN_ON_ONCE(le32_to_cpu(desc->grpid) > ctrl->anagrpmax))
457 			return -EINVAL;
458 		if (WARN_ON_ONCE(desc->state == 0))
459 			return -EINVAL;
460 		if (WARN_ON_ONCE(desc->state > NVME_ANA_CHANGE))
461 			return -EINVAL;
462 
463 		offset += sizeof(*desc);
464 		if (WARN_ON_ONCE(offset > ctrl->ana_log_size - nsid_buf_size))
465 			return -EINVAL;
466 
467 		error = cb(ctrl, desc, data);
468 		if (error)
469 			return error;
470 
471 		offset += nsid_buf_size;
472 	}
473 
474 	return 0;
475 }
476 
477 static inline bool nvme_state_is_live(enum nvme_ana_state state)
478 {
479 	return state == NVME_ANA_OPTIMIZED || state == NVME_ANA_NONOPTIMIZED;
480 }
481 
482 static void nvme_update_ns_ana_state(struct nvme_ana_group_desc *desc,
483 		struct nvme_ns *ns)
484 {
485 	ns->ana_grpid = le32_to_cpu(desc->grpid);
486 	ns->ana_state = desc->state;
487 	clear_bit(NVME_NS_ANA_PENDING, &ns->flags);
488 
489 	if (nvme_state_is_live(ns->ana_state))
490 		nvme_mpath_set_live(ns);
491 }
492 
493 static int nvme_update_ana_state(struct nvme_ctrl *ctrl,
494 		struct nvme_ana_group_desc *desc, void *data)
495 {
496 	u32 nr_nsids = le32_to_cpu(desc->nnsids), n = 0;
497 	unsigned *nr_change_groups = data;
498 	struct nvme_ns *ns;
499 
500 	dev_dbg(ctrl->device, "ANA group %d: %s.\n",
501 			le32_to_cpu(desc->grpid),
502 			nvme_ana_state_names[desc->state]);
503 
504 	if (desc->state == NVME_ANA_CHANGE)
505 		(*nr_change_groups)++;
506 
507 	if (!nr_nsids)
508 		return 0;
509 
510 	down_read(&ctrl->namespaces_rwsem);
511 	list_for_each_entry(ns, &ctrl->namespaces, list) {
512 		unsigned nsid = le32_to_cpu(desc->nsids[n]);
513 
514 		if (ns->head->ns_id < nsid)
515 			continue;
516 		if (ns->head->ns_id == nsid)
517 			nvme_update_ns_ana_state(desc, ns);
518 		if (++n == nr_nsids)
519 			break;
520 	}
521 	up_read(&ctrl->namespaces_rwsem);
522 	return 0;
523 }
524 
525 static int nvme_read_ana_log(struct nvme_ctrl *ctrl)
526 {
527 	u32 nr_change_groups = 0;
528 	int error;
529 
530 	mutex_lock(&ctrl->ana_lock);
531 	error = nvme_get_log(ctrl, NVME_NSID_ALL, NVME_LOG_ANA, 0, NVME_CSI_NVM,
532 			ctrl->ana_log_buf, ctrl->ana_log_size, 0);
533 	if (error) {
534 		dev_warn(ctrl->device, "Failed to get ANA log: %d\n", error);
535 		goto out_unlock;
536 	}
537 
538 	error = nvme_parse_ana_log(ctrl, &nr_change_groups,
539 			nvme_update_ana_state);
540 	if (error)
541 		goto out_unlock;
542 
543 	/*
544 	 * In theory we should have an ANATT timer per group as they might enter
545 	 * the change state at different times.  But that is a lot of overhead
546 	 * just to protect against a target that keeps entering new changes
547 	 * states while never finishing previous ones.  But we'll still
548 	 * eventually time out once all groups are in change state, so this
549 	 * isn't a big deal.
550 	 *
551 	 * We also double the ANATT value to provide some slack for transports
552 	 * or AEN processing overhead.
553 	 */
554 	if (nr_change_groups)
555 		mod_timer(&ctrl->anatt_timer, ctrl->anatt * HZ * 2 + jiffies);
556 	else
557 		del_timer_sync(&ctrl->anatt_timer);
558 out_unlock:
559 	mutex_unlock(&ctrl->ana_lock);
560 	return error;
561 }
562 
563 static void nvme_ana_work(struct work_struct *work)
564 {
565 	struct nvme_ctrl *ctrl = container_of(work, struct nvme_ctrl, ana_work);
566 
567 	if (ctrl->state != NVME_CTRL_LIVE)
568 		return;
569 
570 	nvme_read_ana_log(ctrl);
571 }
572 
573 static void nvme_anatt_timeout(struct timer_list *t)
574 {
575 	struct nvme_ctrl *ctrl = from_timer(ctrl, t, anatt_timer);
576 
577 	dev_info(ctrl->device, "ANATT timeout, resetting controller.\n");
578 	nvme_reset_ctrl(ctrl);
579 }
580 
581 void nvme_mpath_stop(struct nvme_ctrl *ctrl)
582 {
583 	if (!nvme_ctrl_use_ana(ctrl))
584 		return;
585 	del_timer_sync(&ctrl->anatt_timer);
586 	cancel_work_sync(&ctrl->ana_work);
587 }
588 
589 #define SUBSYS_ATTR_RW(_name, _mode, _show, _store)  \
590 	struct device_attribute subsys_attr_##_name =	\
591 		__ATTR(_name, _mode, _show, _store)
592 
593 static const char *nvme_iopolicy_names[] = {
594 	[NVME_IOPOLICY_NUMA]	= "numa",
595 	[NVME_IOPOLICY_RR]	= "round-robin",
596 };
597 
598 static ssize_t nvme_subsys_iopolicy_show(struct device *dev,
599 		struct device_attribute *attr, char *buf)
600 {
601 	struct nvme_subsystem *subsys =
602 		container_of(dev, struct nvme_subsystem, dev);
603 
604 	return sprintf(buf, "%s\n",
605 			nvme_iopolicy_names[READ_ONCE(subsys->iopolicy)]);
606 }
607 
608 static ssize_t nvme_subsys_iopolicy_store(struct device *dev,
609 		struct device_attribute *attr, const char *buf, size_t count)
610 {
611 	struct nvme_subsystem *subsys =
612 		container_of(dev, struct nvme_subsystem, dev);
613 	int i;
614 
615 	for (i = 0; i < ARRAY_SIZE(nvme_iopolicy_names); i++) {
616 		if (sysfs_streq(buf, nvme_iopolicy_names[i])) {
617 			WRITE_ONCE(subsys->iopolicy, i);
618 			return count;
619 		}
620 	}
621 
622 	return -EINVAL;
623 }
624 SUBSYS_ATTR_RW(iopolicy, S_IRUGO | S_IWUSR,
625 		      nvme_subsys_iopolicy_show, nvme_subsys_iopolicy_store);
626 
627 static ssize_t ana_grpid_show(struct device *dev, struct device_attribute *attr,
628 		char *buf)
629 {
630 	return sprintf(buf, "%d\n", nvme_get_ns_from_dev(dev)->ana_grpid);
631 }
632 DEVICE_ATTR_RO(ana_grpid);
633 
634 static ssize_t ana_state_show(struct device *dev, struct device_attribute *attr,
635 		char *buf)
636 {
637 	struct nvme_ns *ns = nvme_get_ns_from_dev(dev);
638 
639 	return sprintf(buf, "%s\n", nvme_ana_state_names[ns->ana_state]);
640 }
641 DEVICE_ATTR_RO(ana_state);
642 
643 static int nvme_lookup_ana_group_desc(struct nvme_ctrl *ctrl,
644 		struct nvme_ana_group_desc *desc, void *data)
645 {
646 	struct nvme_ana_group_desc *dst = data;
647 
648 	if (desc->grpid != dst->grpid)
649 		return 0;
650 
651 	*dst = *desc;
652 	return -ENXIO; /* just break out of the loop */
653 }
654 
655 void nvme_mpath_add_disk(struct nvme_ns *ns, struct nvme_id_ns *id)
656 {
657 	if (nvme_ctrl_use_ana(ns->ctrl)) {
658 		struct nvme_ana_group_desc desc = {
659 			.grpid = id->anagrpid,
660 			.state = 0,
661 		};
662 
663 		mutex_lock(&ns->ctrl->ana_lock);
664 		ns->ana_grpid = le32_to_cpu(id->anagrpid);
665 		nvme_parse_ana_log(ns->ctrl, &desc, nvme_lookup_ana_group_desc);
666 		mutex_unlock(&ns->ctrl->ana_lock);
667 		if (desc.state) {
668 			/* found the group desc: update */
669 			nvme_update_ns_ana_state(&desc, ns);
670 		}
671 	} else {
672 		ns->ana_state = NVME_ANA_OPTIMIZED;
673 		nvme_mpath_set_live(ns);
674 	}
675 
676 	if (bdi_cap_stable_pages_required(ns->queue->backing_dev_info)) {
677 		struct gendisk *disk = ns->head->disk;
678 
679 		if (disk)
680 			disk->queue->backing_dev_info->capabilities |=
681 					BDI_CAP_STABLE_WRITES;
682 	}
683 }
684 
685 void nvme_mpath_remove_disk(struct nvme_ns_head *head)
686 {
687 	if (!head->disk)
688 		return;
689 	if (head->disk->flags & GENHD_FL_UP)
690 		del_gendisk(head->disk);
691 	blk_set_queue_dying(head->disk->queue);
692 	/* make sure all pending bios are cleaned up */
693 	kblockd_schedule_work(&head->requeue_work);
694 	flush_work(&head->requeue_work);
695 	blk_cleanup_queue(head->disk->queue);
696 	if (!test_bit(NVME_NSHEAD_DISK_LIVE, &head->flags)) {
697 		/*
698 		 * if device_add_disk wasn't called, prevent
699 		 * disk release to put a bogus reference on the
700 		 * request queue
701 		 */
702 		head->disk->queue = NULL;
703 	}
704 	put_disk(head->disk);
705 }
706 
707 int nvme_mpath_init(struct nvme_ctrl *ctrl, struct nvme_id_ctrl *id)
708 {
709 	int error;
710 
711 	/* check if multipath is enabled and we have the capability */
712 	if (!multipath || !ctrl->subsys ||
713 	    !(ctrl->subsys->cmic & NVME_CTRL_CMIC_ANA))
714 		return 0;
715 
716 	ctrl->anacap = id->anacap;
717 	ctrl->anatt = id->anatt;
718 	ctrl->nanagrpid = le32_to_cpu(id->nanagrpid);
719 	ctrl->anagrpmax = le32_to_cpu(id->anagrpmax);
720 
721 	mutex_init(&ctrl->ana_lock);
722 	timer_setup(&ctrl->anatt_timer, nvme_anatt_timeout, 0);
723 	ctrl->ana_log_size = sizeof(struct nvme_ana_rsp_hdr) +
724 		ctrl->nanagrpid * sizeof(struct nvme_ana_group_desc);
725 	ctrl->ana_log_size += ctrl->max_namespaces * sizeof(__le32);
726 
727 	if (ctrl->ana_log_size > ctrl->max_hw_sectors << SECTOR_SHIFT) {
728 		dev_err(ctrl->device,
729 			"ANA log page size (%zd) larger than MDTS (%d).\n",
730 			ctrl->ana_log_size,
731 			ctrl->max_hw_sectors << SECTOR_SHIFT);
732 		dev_err(ctrl->device, "disabling ANA support.\n");
733 		return 0;
734 	}
735 
736 	INIT_WORK(&ctrl->ana_work, nvme_ana_work);
737 	kfree(ctrl->ana_log_buf);
738 	ctrl->ana_log_buf = kmalloc(ctrl->ana_log_size, GFP_KERNEL);
739 	if (!ctrl->ana_log_buf) {
740 		error = -ENOMEM;
741 		goto out;
742 	}
743 
744 	error = nvme_read_ana_log(ctrl);
745 	if (error)
746 		goto out_free_ana_log_buf;
747 	return 0;
748 out_free_ana_log_buf:
749 	kfree(ctrl->ana_log_buf);
750 	ctrl->ana_log_buf = NULL;
751 out:
752 	return error;
753 }
754 
755 void nvme_mpath_uninit(struct nvme_ctrl *ctrl)
756 {
757 	kfree(ctrl->ana_log_buf);
758 	ctrl->ana_log_buf = NULL;
759 }
760 
761