1	// SPDX-License-Identifier: GPL-2.0-only
2	/*
3	* Copyright (C) 2003 Sistina Software Limited.
4	* Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
5	*
6	* This file is released under the GPL.
7	*/
8
9	#include <linux/device-mapper.h>
10
11	#include "dm-rq.h"
12	#include "dm-bio-record.h"
13	#include "dm-path-selector.h"
14	#include "dm-uevent.h"
15
16	#include <linux/blkdev.h>
17	#include <linux/ctype.h>
18	#include <linux/init.h>
19	#include <linux/mempool.h>
20	#include <linux/module.h>
21	#include <linux/pagemap.h>
22	#include <linux/slab.h>
23	#include <linux/time.h>
24	#include <linux/timer.h>
25	#include <linux/workqueue.h>
26	#include <linux/delay.h>
27	#include <scsi/scsi_dh.h>
28	#include <linux/atomic.h>
29	#include <linux/blk-mq.h>
30
31	static struct workqueue_struct *dm_mpath_wq;
32
33	#define DM_MSG_PREFIX "multipath"
34	#define DM_PG_INIT_DELAY_MSECS 2000
35	#define DM_PG_INIT_DELAY_DEFAULT ((unsigned int) -1)
36	#define QUEUE_IF_NO_PATH_TIMEOUT_DEFAULT 0
37
38	static unsigned long queue_if_no_path_timeout_secs = QUEUE_IF_NO_PATH_TIMEOUT_DEFAULT;
39
40	/* Path properties */
41	struct pgpath {
42	struct list_head list;
43
44	struct priority_group *pg; /* Owning PG */
45	unsigned int fail_count; /* Cumulative failure count */
46
47	struct dm_path path;
48	struct delayed_work activate_path;
49
50	bool is_active:1; /* Path status */
51	};
52
53	#define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path)
54
55	/*
56	* Paths are grouped into Priority Groups and numbered from 1 upwards.
57	* Each has a path selector which controls which path gets used.
58	*/
59	struct priority_group {
60	struct list_head list;
61
62	struct multipath *m; /* Owning multipath instance */
63	struct path_selector ps;
64
65	unsigned int pg_num; /* Reference number */
66	unsigned int nr_pgpaths; /* Number of paths in PG */
67	struct list_head pgpaths;
68
69	bool bypassed:1; /* Temporarily bypass this PG? */
70	};
71
72	/* Multipath context */
73	struct multipath {
74	unsigned long flags; /* Multipath state flags */
75
76	spinlock_t lock;
77	enum dm_queue_mode queue_mode;
78
79	struct pgpath *current_pgpath;
80	struct priority_group *current_pg;
81	struct priority_group *next_pg; /* Switch to this PG if set */
82
83	atomic_t nr_valid_paths; /* Total number of usable paths */
84	unsigned int nr_priority_groups;
85	struct list_head priority_groups;
86
87	const char *hw_handler_name;
88	char *hw_handler_params;
89	wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
90	unsigned int pg_init_retries; /* Number of times to retry pg_init */
91	unsigned int pg_init_delay_msecs; /* Number of msecs before pg_init retry */
92	atomic_t pg_init_in_progress; /* Only one pg_init allowed at once */
93	atomic_t pg_init_count; /* Number of times pg_init called */
94
95	struct mutex work_mutex;
96	struct work_struct trigger_event;
97	struct dm_target *ti;
98
99	struct work_struct process_queued_bios;
100	struct bio_list queued_bios;
101
102	struct timer_list nopath_timer; /* Timeout for queue_if_no_path */
103	};
104
105	/*
106	* Context information attached to each io we process.
107	*/
108	struct dm_mpath_io {
109	struct pgpath *pgpath;
110	size_t nr_bytes;
111	u64 start_time_ns;
112	};
113
114	typedef int (*action_fn) (struct pgpath *pgpath);
115
116	static struct workqueue_struct *kmultipathd, *kmpath_handlerd;
117	static void trigger_event(struct work_struct *work);
118	static void activate_or_offline_path(struct pgpath *pgpath);
119	static void activate_path_work(struct work_struct *work);
120	static void process_queued_bios(struct work_struct *work);
121	static void queue_if_no_path_timeout_work(struct timer_list *t);
122
123	/*
124	*-----------------------------------------------
125	* Multipath state flags.
126	*-----------------------------------------------
127	*/
128	#define MPATHF_QUEUE_IO 0 /* Must we queue all I/O? */
129	#define MPATHF_QUEUE_IF_NO_PATH 1 /* Queue I/O if last path fails? */
130	#define MPATHF_SAVED_QUEUE_IF_NO_PATH 2 /* Saved state during suspension */
131	#define MPATHF_RETAIN_ATTACHED_HW_HANDLER 3 /* If there's already a hw_handler present, don't change it. */
132	#define MPATHF_PG_INIT_DISABLED 4 /* pg_init is not currently allowed */
133	#define MPATHF_PG_INIT_REQUIRED 5 /* pg_init needs calling? */
134	#define MPATHF_PG_INIT_DELAY_RETRY 6 /* Delay pg_init retry? */
135
136	static bool mpath_double_check_test_bit(int MPATHF_bit, struct multipath *m)
137	{
138	bool r = test_bit(MPATHF_bit, &m->flags);
139
140	if (r) {
141	unsigned long flags;
142
143	spin_lock_irqsave(&m->lock, flags);
144	r = test_bit(MPATHF_bit, &m->flags);
145	spin_unlock_irqrestore(lock: &m->lock, flags);
146	}
147
148	return r;
149	}
150
151	/*
152	*-----------------------------------------------
153	* Allocation routines
154	*-----------------------------------------------
155	*/
156	static struct pgpath *alloc_pgpath(void)
157	{
158	struct pgpath *pgpath = kzalloc(size: sizeof(*pgpath), GFP_KERNEL);
159
160	if (!pgpath)
161	return NULL;
162
163	pgpath->is_active = true;
164
165	return pgpath;
166	}
167
168	static void free_pgpath(struct pgpath *pgpath)
169	{
170	kfree(objp: pgpath);
171	}
172
173	static struct priority_group *alloc_priority_group(void)
174	{
175	struct priority_group *pg;
176
177	pg = kzalloc(size: sizeof(*pg), GFP_KERNEL);
178
179	if (pg)
180	INIT_LIST_HEAD(list: &pg->pgpaths);
181
182	return pg;
183	}
184
185	static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti)
186	{
187	struct pgpath *pgpath, *tmp;
188
189	list_for_each_entry_safe(pgpath, tmp, pgpaths, list) {
190	list_del(entry: &pgpath->list);
191	dm_put_device(ti, d: pgpath->path.dev);
192	free_pgpath(pgpath);
193	}
194	}
195
196	static void free_priority_group(struct priority_group *pg,
197	struct dm_target *ti)
198	{
199	struct path_selector *ps = &pg->ps;
200
201	if (ps->type) {
202	ps->type->destroy(ps);
203	dm_put_path_selector(pst: ps->type);
204	}
205
206	free_pgpaths(pgpaths: &pg->pgpaths, ti);
207	kfree(objp: pg);
208	}
209
210	static struct multipath *alloc_multipath(struct dm_target *ti)
211	{
212	struct multipath *m;
213
214	m = kzalloc(size: sizeof(*m), GFP_KERNEL);
215	if (m) {
216	INIT_LIST_HEAD(list: &m->priority_groups);
217	spin_lock_init(&m->lock);
218	atomic_set(v: &m->nr_valid_paths, i: 0);
219	INIT_WORK(&m->trigger_event, trigger_event);
220	mutex_init(&m->work_mutex);
221
222	m->queue_mode = DM_TYPE_NONE;
223
224	m->ti = ti;
225	ti->private = m;
226
227	timer_setup(&m->nopath_timer, queue_if_no_path_timeout_work, 0);
228	}
229
230	return m;
231	}
232
233	static int alloc_multipath_stage2(struct dm_target *ti, struct multipath *m)
234	{
235	if (m->queue_mode == DM_TYPE_NONE) {
236	m->queue_mode = DM_TYPE_REQUEST_BASED;
237	} else if (m->queue_mode == DM_TYPE_BIO_BASED) {
238	INIT_WORK(&m->process_queued_bios, process_queued_bios);
239	/*
240	* bio-based doesn't support any direct scsi_dh management;
241	* it just discovers if a scsi_dh is attached.
242	*/
243	set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, addr: &m->flags);
244	}
245
246	dm_table_set_type(t: ti->table, type: m->queue_mode);
247
248	/*
249	* Init fields that are only used when a scsi_dh is attached
250	* - must do this unconditionally (really doesn't hurt non-SCSI uses)
251	*/
252	set_bit(MPATHF_QUEUE_IO, addr: &m->flags);
253	atomic_set(v: &m->pg_init_in_progress, i: 0);
254	atomic_set(v: &m->pg_init_count, i: 0);
255	m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT;
256	init_waitqueue_head(&m->pg_init_wait);
257
258	return 0;
259	}
260
261	static void free_multipath(struct multipath *m)
262	{
263	struct priority_group *pg, *tmp;
264
265	list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) {
266	list_del(entry: &pg->list);
267	free_priority_group(pg, ti: m->ti);
268	}
269
270	kfree(objp: m->hw_handler_name);
271	kfree(objp: m->hw_handler_params);
272	mutex_destroy(lock: &m->work_mutex);
273	kfree(objp: m);
274	}
275
276	static struct dm_mpath_io *get_mpio(union map_info *info)
277	{
278	return info->ptr;
279	}
280
281	static size_t multipath_per_bio_data_size(void)
282	{
283	return sizeof(struct dm_mpath_io) + sizeof(struct dm_bio_details);
284	}
285
286	static struct dm_mpath_io *get_mpio_from_bio(struct bio *bio)
287	{
288	return dm_per_bio_data(bio, data_size: multipath_per_bio_data_size());
289	}
290
291	static struct dm_bio_details *get_bio_details_from_mpio(struct dm_mpath_io *mpio)
292	{
293	/* dm_bio_details is immediately after the dm_mpath_io in bio's per-bio-data */
294	void *bio_details = mpio + 1;
295	return bio_details;
296	}
297
298	static void multipath_init_per_bio_data(struct bio *bio, struct dm_mpath_io **mpio_p)
299	{
300	struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
301	struct dm_bio_details *bio_details = get_bio_details_from_mpio(mpio);
302
303	mpio->nr_bytes = bio->bi_iter.bi_size;
304	mpio->pgpath = NULL;
305	mpio->start_time_ns = 0;
306	*mpio_p = mpio;
307
308	dm_bio_record(bd: bio_details, bio);
309	}
310
311	/*
312	*-----------------------------------------------
313	* Path selection
314	*-----------------------------------------------
315	*/
316	static int __pg_init_all_paths(struct multipath *m)
317	{
318	struct pgpath *pgpath;
319	unsigned long pg_init_delay = 0;
320
321	lockdep_assert_held(&m->lock);
322
323	if (atomic_read(v: &m->pg_init_in_progress) || test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
324	return 0;
325
326	atomic_inc(v: &m->pg_init_count);
327	clear_bit(MPATHF_PG_INIT_REQUIRED, addr: &m->flags);
328
329	/* Check here to reset pg_init_required */
330	if (!m->current_pg)
331	return 0;
332
333	if (test_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags))
334	pg_init_delay = msecs_to_jiffies(m: m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ?
335	m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS);
336	list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) {
337	/* Skip failed paths */
338	if (!pgpath->is_active)
339	continue;
340	if (queue_delayed_work(wq: kmpath_handlerd, dwork: &pgpath->activate_path,
341	delay: pg_init_delay))
342	atomic_inc(v: &m->pg_init_in_progress);
343	}
344	return atomic_read(v: &m->pg_init_in_progress);
345	}
346
347	static int pg_init_all_paths(struct multipath *m)
348	{
349	int ret;
350	unsigned long flags;
351
352	spin_lock_irqsave(&m->lock, flags);
353	ret = __pg_init_all_paths(m);
354	spin_unlock_irqrestore(lock: &m->lock, flags);
355
356	return ret;
357	}
358
359	static void __switch_pg(struct multipath *m, struct priority_group *pg)
360	{
361	lockdep_assert_held(&m->lock);
362
363	m->current_pg = pg;
364
365	/* Must we initialise the PG first, and queue I/O till it's ready? */
366	if (m->hw_handler_name) {
367	set_bit(MPATHF_PG_INIT_REQUIRED, addr: &m->flags);
368	set_bit(MPATHF_QUEUE_IO, addr: &m->flags);
369	} else {
370	clear_bit(MPATHF_PG_INIT_REQUIRED, addr: &m->flags);
371	clear_bit(MPATHF_QUEUE_IO, addr: &m->flags);
372	}
373
374	atomic_set(v: &m->pg_init_count, i: 0);
375	}
376
377	static struct pgpath *choose_path_in_pg(struct multipath *m,
378	struct priority_group *pg,
379	size_t nr_bytes)
380	{
381	unsigned long flags;
382	struct dm_path *path;
383	struct pgpath *pgpath;
384
385	path = pg->ps.type->select_path(&pg->ps, nr_bytes);
386	if (!path)
387	return ERR_PTR(error: -ENXIO);
388
389	pgpath = path_to_pgpath(path);
390
391	if (unlikely(READ_ONCE(m->current_pg) != pg)) {
392	/* Only update current_pgpath if pg changed */
393	spin_lock_irqsave(&m->lock, flags);
394	m->current_pgpath = pgpath;
395	__switch_pg(m, pg);
396	spin_unlock_irqrestore(lock: &m->lock, flags);
397	}
398
399	return pgpath;
400	}
401
402	static struct pgpath *choose_pgpath(struct multipath *m, size_t nr_bytes)
403	{
404	unsigned long flags;
405	struct priority_group *pg;
406	struct pgpath *pgpath;
407	unsigned int bypassed = 1;
408
409	if (!atomic_read(v: &m->nr_valid_paths)) {
410	spin_lock_irqsave(&m->lock, flags);
411	clear_bit(MPATHF_QUEUE_IO, addr: &m->flags);
412	spin_unlock_irqrestore(lock: &m->lock, flags);
413	goto failed;
414	}
415
416	/* Were we instructed to switch PG? */
417	if (READ_ONCE(m->next_pg)) {
418	spin_lock_irqsave(&m->lock, flags);
419	pg = m->next_pg;
420	if (!pg) {
421	spin_unlock_irqrestore(lock: &m->lock, flags);
422	goto check_current_pg;
423	}
424	m->next_pg = NULL;
425	spin_unlock_irqrestore(lock: &m->lock, flags);
426	pgpath = choose_path_in_pg(m, pg, nr_bytes);
427	if (!IS_ERR_OR_NULL(ptr: pgpath))
428	return pgpath;
429	}
430
431	/* Don't change PG until it has no remaining paths */
432	check_current_pg:
433	pg = READ_ONCE(m->current_pg);
434	if (pg) {
435	pgpath = choose_path_in_pg(m, pg, nr_bytes);
436	if (!IS_ERR_OR_NULL(ptr: pgpath))
437	return pgpath;
438	}
439
440	/*
441	* Loop through priority groups until we find a valid path.
442	* First time we skip PGs marked 'bypassed'.
443	* Second time we only try the ones we skipped, but set
444	* pg_init_delay_retry so we do not hammer controllers.
445	*/
446	do {
447	list_for_each_entry(pg, &m->priority_groups, list) {
448	if (pg->bypassed == !!bypassed)
449	continue;
450	pgpath = choose_path_in_pg(m, pg, nr_bytes);
451	if (!IS_ERR_OR_NULL(ptr: pgpath)) {
452	if (!bypassed) {
453	spin_lock_irqsave(&m->lock, flags);
454	set_bit(MPATHF_PG_INIT_DELAY_RETRY, addr: &m->flags);
455	spin_unlock_irqrestore(lock: &m->lock, flags);
456	}
457	return pgpath;
458	}
459	}
460	} while (bypassed--);
461
462	failed:
463	spin_lock_irqsave(&m->lock, flags);
464	m->current_pgpath = NULL;
465	m->current_pg = NULL;
466	spin_unlock_irqrestore(lock: &m->lock, flags);
467
468	return NULL;
469	}
470
471	/*
472	* dm_report_EIO() is a macro instead of a function to make pr_debug_ratelimited()
473	* report the function name and line number of the function from which
474	* it has been invoked.
475	*/
476	#define dm_report_EIO(m) \
477	DMDEBUG_LIMIT("%s: returning EIO; QIFNP = %d; SQIFNP = %d; DNFS = %d", \
478	dm_table_device_name((m)->ti->table), \
479	test_bit(MPATHF_QUEUE_IF_NO_PATH, &(m)->flags), \
480	test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &(m)->flags), \
481	dm_noflush_suspending((m)->ti))
482
483	/*
484	* Check whether bios must be queued in the device-mapper core rather
485	* than here in the target.
486	*/
487	static bool __must_push_back(struct multipath *m)
488	{
489	return dm_noflush_suspending(ti: m->ti);
490	}
491
492	static bool must_push_back_rq(struct multipath *m)
493	{
494	unsigned long flags;
495	bool ret;
496
497	spin_lock_irqsave(&m->lock, flags);
498	ret = (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) || __must_push_back(m));
499	spin_unlock_irqrestore(lock: &m->lock, flags);
500
501	return ret;
502	}
503
504	/*
505	* Map cloned requests (request-based multipath)
506	*/
507	static int multipath_clone_and_map(struct dm_target *ti, struct request *rq,
508	union map_info *map_context,
509	struct request **__clone)
510	{
511	struct multipath *m = ti->private;
512	size_t nr_bytes = blk_rq_bytes(rq);
513	struct pgpath *pgpath;
514	struct block_device *bdev;
515	struct dm_mpath_io *mpio = get_mpio(info: map_context);
516	struct request_queue *q;
517	struct request *clone;
518
519	/* Do we need to select a new pgpath? */
520	pgpath = READ_ONCE(m->current_pgpath);
521	if (!pgpath || !mpath_double_check_test_bit(MPATHF_QUEUE_IO, m))
522	pgpath = choose_pgpath(m, nr_bytes);
523
524	if (!pgpath) {
525	if (must_push_back_rq(m))
526	return DM_MAPIO_DELAY_REQUEUE;
527	dm_report_EIO(m); /* Failed */
528	return DM_MAPIO_KILL;
529	} else if (mpath_double_check_test_bit(MPATHF_QUEUE_IO, m) ||
530	mpath_double_check_test_bit(MPATHF_PG_INIT_REQUIRED, m)) {
531	pg_init_all_paths(m);
532	return DM_MAPIO_DELAY_REQUEUE;
533	}
534
535	mpio->pgpath = pgpath;
536	mpio->nr_bytes = nr_bytes;
537
538	bdev = pgpath->path.dev->bdev;
539	q = bdev_get_queue(bdev);
540	clone = blk_mq_alloc_request(q, opf: rq->cmd_flags | REQ_NOMERGE,
541	flags: BLK_MQ_REQ_NOWAIT);
542	if (IS_ERR(ptr: clone)) {
543	/* EBUSY, ENODEV or EWOULDBLOCK: requeue */
544	if (blk_queue_dying(q)) {
545	atomic_inc(v: &m->pg_init_in_progress);
546	activate_or_offline_path(pgpath);
547	return DM_MAPIO_DELAY_REQUEUE;
548	}
549
550	/*
551	* blk-mq's SCHED_RESTART can cover this requeue, so we
552	* needn't deal with it by DELAY_REQUEUE. More importantly,
553	* we have to return DM_MAPIO_REQUEUE so that blk-mq can
554	* get the queue busy feedback (via BLK_STS_RESOURCE),
555	* otherwise I/O merging can suffer.
556	*/
557	return DM_MAPIO_REQUEUE;
558	}
559	clone->bio = clone->biotail = NULL;
560	clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
561	*__clone = clone;
562
563	if (pgpath->pg->ps.type->start_io)
564	pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
565	&pgpath->path,
566	nr_bytes);
567	return DM_MAPIO_REMAPPED;
568	}
569
570	static void multipath_release_clone(struct request *clone,
571	union map_info *map_context)
572	{
573	if (unlikely(map_context)) {
574	/*
575	* non-NULL map_context means caller is still map
576	* method; must undo multipath_clone_and_map()
577	*/
578	struct dm_mpath_io *mpio = get_mpio(info: map_context);
579	struct pgpath *pgpath = mpio->pgpath;
580
581	if (pgpath && pgpath->pg->ps.type->end_io)
582	pgpath->pg->ps.type->end_io(&pgpath->pg->ps,
583	&pgpath->path,
584	mpio->nr_bytes,
585	clone->io_start_time_ns);
586	}
587
588	blk_mq_free_request(rq: clone);
589	}
590
591	/*
592	* Map cloned bios (bio-based multipath)
593	*/
594
595	static void __multipath_queue_bio(struct multipath *m, struct bio *bio)
596	{
597	/* Queue for the daemon to resubmit */
598	bio_list_add(bl: &m->queued_bios, bio);
599	if (!test_bit(MPATHF_QUEUE_IO, &m->flags))
600	queue_work(wq: kmultipathd, work: &m->process_queued_bios);
601	}
602
603	static void multipath_queue_bio(struct multipath *m, struct bio *bio)
604	{
605	unsigned long flags;
606
607	spin_lock_irqsave(&m->lock, flags);
608	__multipath_queue_bio(m, bio);
609	spin_unlock_irqrestore(lock: &m->lock, flags);
610	}
611
612	static struct pgpath *__map_bio(struct multipath *m, struct bio *bio)
613	{
614	struct pgpath *pgpath;
615	unsigned long flags;
616
617	/* Do we need to select a new pgpath? */
618	pgpath = READ_ONCE(m->current_pgpath);
619	if (!pgpath || !mpath_double_check_test_bit(MPATHF_QUEUE_IO, m))
620	pgpath = choose_pgpath(m, nr_bytes: bio->bi_iter.bi_size);
621
622	if (!pgpath) {
623	spin_lock_irqsave(&m->lock, flags);
624	if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
625	__multipath_queue_bio(m, bio);
626	pgpath = ERR_PTR(error: -EAGAIN);
627	}
628	spin_unlock_irqrestore(lock: &m->lock, flags);
629
630	} else if (mpath_double_check_test_bit(MPATHF_QUEUE_IO, m) ||
631	mpath_double_check_test_bit(MPATHF_PG_INIT_REQUIRED, m)) {
632	multipath_queue_bio(m, bio);
633	pg_init_all_paths(m);
634	return ERR_PTR(error: -EAGAIN);
635	}
636
637	return pgpath;
638	}
639
640	static int __multipath_map_bio(struct multipath *m, struct bio *bio,
641	struct dm_mpath_io *mpio)
642	{
643	struct pgpath *pgpath = __map_bio(m, bio);
644
645	if (IS_ERR(ptr: pgpath))
646	return DM_MAPIO_SUBMITTED;
647
648	if (!pgpath) {
649	if (__must_push_back(m))
650	return DM_MAPIO_REQUEUE;
651	dm_report_EIO(m);
652	return DM_MAPIO_KILL;
653	}
654
655	mpio->pgpath = pgpath;
656
657	if (dm_ps_use_hr_timer(pgpath->pg->ps.type))
658	mpio->start_time_ns = ktime_get_ns();
659
660	bio->bi_status = 0;
661	bio_set_dev(bio, bdev: pgpath->path.dev->bdev);
662	bio->bi_opf |= REQ_FAILFAST_TRANSPORT;
663
664	if (pgpath->pg->ps.type->start_io)
665	pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
666	&pgpath->path,
667	mpio->nr_bytes);
668	return DM_MAPIO_REMAPPED;
669	}
670
671	static int multipath_map_bio(struct dm_target *ti, struct bio *bio)
672	{
673	struct multipath *m = ti->private;
674	struct dm_mpath_io *mpio = NULL;
675
676	multipath_init_per_bio_data(bio, mpio_p: &mpio);
677	return __multipath_map_bio(m, bio, mpio);
678	}
679
680	static void process_queued_io_list(struct multipath *m)
681	{
682	if (m->queue_mode == DM_TYPE_REQUEST_BASED)
683	dm_mq_kick_requeue_list(md: dm_table_get_md(t: m->ti->table));
684	else if (m->queue_mode == DM_TYPE_BIO_BASED)
685	queue_work(wq: kmultipathd, work: &m->process_queued_bios);
686	}
687
688	static void process_queued_bios(struct work_struct *work)
689	{
690	int r;
691	unsigned long flags;
692	struct bio *bio;
693	struct bio_list bios;
694	struct blk_plug plug;
695	struct multipath *m =
696	container_of(work, struct multipath, process_queued_bios);
697
698	bio_list_init(bl: &bios);
699
700	spin_lock_irqsave(&m->lock, flags);
701
702	if (bio_list_empty(bl: &m->queued_bios)) {
703	spin_unlock_irqrestore(lock: &m->lock, flags);
704	return;
705	}
706
707	bio_list_merge(bl: &bios, bl2: &m->queued_bios);
708	bio_list_init(bl: &m->queued_bios);
709
710	spin_unlock_irqrestore(lock: &m->lock, flags);
711
712	blk_start_plug(&plug);
713	while ((bio = bio_list_pop(bl: &bios))) {
714	struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
715
716	dm_bio_restore(bd: get_bio_details_from_mpio(mpio), bio);
717	r = __multipath_map_bio(m, bio, mpio);
718	switch (r) {
719	case DM_MAPIO_KILL:
720	bio->bi_status = BLK_STS_IOERR;
721	bio_endio(bio);
722	break;
723	case DM_MAPIO_REQUEUE:
724	bio->bi_status = BLK_STS_DM_REQUEUE;
725	bio_endio(bio);
726	break;
727	case DM_MAPIO_REMAPPED:
728	submit_bio_noacct(bio);
729	break;
730	case DM_MAPIO_SUBMITTED:
731	break;
732	default:
733	WARN_ONCE(true, "__multipath_map_bio() returned %d\n", r);
734	}
735	}
736	blk_finish_plug(&plug);
737	}
738
739	/*
740	* If we run out of usable paths, should we queue I/O or error it?
741	*/
742	static int queue_if_no_path(struct multipath *m, bool f_queue_if_no_path,
743	bool save_old_value, const char *caller)
744	{
745	unsigned long flags;
746	bool queue_if_no_path_bit, saved_queue_if_no_path_bit;
747	const char *dm_dev_name = dm_table_device_name(t: m->ti->table);
748
749	DMDEBUG("%s: %s caller=%s f_queue_if_no_path=%d save_old_value=%d",
750	dm_dev_name, __func__, caller, f_queue_if_no_path, save_old_value);
751
752	spin_lock_irqsave(&m->lock, flags);
753
754	queue_if_no_path_bit = test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags);
755	saved_queue_if_no_path_bit = test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
756
757	if (save_old_value) {
758	if (unlikely(!queue_if_no_path_bit && saved_queue_if_no_path_bit)) {
759	DMERR("%s: QIFNP disabled but saved as enabled, saving again loses state, not saving!",
760	dm_dev_name);
761	} else
762	assign_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, addr: &m->flags, value: queue_if_no_path_bit);
763	} else if (!f_queue_if_no_path && saved_queue_if_no_path_bit) {
764	/* due to "fail_if_no_path" message, need to honor it. */
765	clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, addr: &m->flags);
766	}
767	assign_bit(MPATHF_QUEUE_IF_NO_PATH, addr: &m->flags, value: f_queue_if_no_path);
768
769	DMDEBUG("%s: after %s changes; QIFNP = %d; SQIFNP = %d; DNFS = %d",
770	dm_dev_name, __func__,
771	test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags),
772	test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags),
773	dm_noflush_suspending(m->ti));
774
775	spin_unlock_irqrestore(lock: &m->lock, flags);
776
777	if (!f_queue_if_no_path) {
778	dm_table_run_md_queue_async(t: m->ti->table);
779	process_queued_io_list(m);
780	}
781
782	return 0;
783	}
784
785	/*
786	* If the queue_if_no_path timeout fires, turn off queue_if_no_path and
787	* process any queued I/O.
788	*/
789	static void queue_if_no_path_timeout_work(struct timer_list *t)
790	{
791	struct multipath *m = from_timer(m, t, nopath_timer);
792
793	DMWARN("queue_if_no_path timeout on %s, failing queued IO",
794	dm_table_device_name(m->ti->table));
795	queue_if_no_path(m, f_queue_if_no_path: false, save_old_value: false, caller: __func__);
796	}
797
798	/*
799	* Enable the queue_if_no_path timeout if necessary.
800	* Called with m->lock held.
801	*/
802	static void enable_nopath_timeout(struct multipath *m)
803	{
804	unsigned long queue_if_no_path_timeout =
805	READ_ONCE(queue_if_no_path_timeout_secs) * HZ;
806
807	lockdep_assert_held(&m->lock);
808
809	if (queue_if_no_path_timeout > 0 &&
810	atomic_read(v: &m->nr_valid_paths) == 0 &&
811	test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
812	mod_timer(timer: &m->nopath_timer,
813	expires: jiffies + queue_if_no_path_timeout);
814	}
815	}
816
817	static void disable_nopath_timeout(struct multipath *m)
818	{
819	del_timer_sync(timer: &m->nopath_timer);
820	}
821
822	/*
823	* An event is triggered whenever a path is taken out of use.
824	* Includes path failure and PG bypass.
825	*/
826	static void trigger_event(struct work_struct *work)
827	{
828	struct multipath *m =
829	container_of(work, struct multipath, trigger_event);
830
831	dm_table_event(t: m->ti->table);
832	}
833
834	/*
835	*---------------------------------------------------------------
836	* Constructor/argument parsing:
837	* <#multipath feature args> [<arg>]*
838	* <#hw_handler args> [hw_handler [<arg>]*]
839	* <#priority groups>
840	* <initial priority group>
841	* [<selector> <#selector args> [<arg>]*
842	* <#paths> <#per-path selector args>
843	* [<path> [<arg>]* ]+ ]+
844	*---------------------------------------------------------------
845	*/
846	static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
847	struct dm_target *ti)
848	{
849	int r;
850	struct path_selector_type *pst;
851	unsigned int ps_argc;
852
853	static const struct dm_arg _args[] = {
854	{0, 1024, "invalid number of path selector args"},
855	};
856
857	pst = dm_get_path_selector(name: dm_shift_arg(as));
858	if (!pst) {
859	ti->error = "unknown path selector type";
860	return -EINVAL;
861	}
862
863	r = dm_read_arg_group(arg: _args, arg_set: as, num_args: &ps_argc, error: &ti->error);
864	if (r) {
865	dm_put_path_selector(pst);
866	return -EINVAL;
867	}
868
869	r = pst->create(&pg->ps, ps_argc, as->argv);
870	if (r) {
871	dm_put_path_selector(pst);
872	ti->error = "path selector constructor failed";
873	return r;
874	}
875
876	pg->ps.type = pst;
877	dm_consume_args(as, num_args: ps_argc);
878
879	return 0;
880	}
881
882	static int setup_scsi_dh(struct block_device *bdev, struct multipath *m,
883	const char **attached_handler_name, char **error)
884	{
885	struct request_queue *q = bdev_get_queue(bdev);
886	int r;
887
888	if (mpath_double_check_test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, m)) {
889	retain:
890	if (*attached_handler_name) {
891	/*
892	* Clear any hw_handler_params associated with a
893	* handler that isn't already attached.
894	*/
895	if (m->hw_handler_name && strcmp(*attached_handler_name, m->hw_handler_name)) {
896	kfree(objp: m->hw_handler_params);
897	m->hw_handler_params = NULL;
898	}
899
900	/*
901	* Reset hw_handler_name to match the attached handler
902	*
903	* NB. This modifies the table line to show the actual
904	* handler instead of the original table passed in.
905	*/
906	kfree(objp: m->hw_handler_name);
907	m->hw_handler_name = *attached_handler_name;
908	*attached_handler_name = NULL;
909	}
910	}
911
912	if (m->hw_handler_name) {
913	r = scsi_dh_attach(q, m->hw_handler_name);
914	if (r == -EBUSY) {
915	DMINFO("retaining handler on device %pg", bdev);
916	goto retain;
917	}
918	if (r < 0) {
919	*error = "error attaching hardware handler";
920	return r;
921	}
922
923	if (m->hw_handler_params) {
924	r = scsi_dh_set_params(q, m->hw_handler_params);
925	if (r < 0) {
926	*error = "unable to set hardware handler parameters";
927	return r;
928	}
929	}
930	}
931
932	return 0;
933	}
934
935	static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
936	struct dm_target *ti)
937	{
938	int r;
939	struct pgpath *p;
940	struct multipath *m = ti->private;
941	struct request_queue *q;
942	const char *attached_handler_name = NULL;
943
944	/* we need at least a path arg */
945	if (as->argc < 1) {
946	ti->error = "no device given";
947	return ERR_PTR(error: -EINVAL);
948	}
949
950	p = alloc_pgpath();
951	if (!p)
952	return ERR_PTR(error: -ENOMEM);
953
954	r = dm_get_device(ti, path: dm_shift_arg(as), mode: dm_table_get_mode(t: ti->table),
955	result: &p->path.dev);
956	if (r) {
957	ti->error = "error getting device";
958	goto bad;
959	}
960
961	q = bdev_get_queue(bdev: p->path.dev->bdev);
962	attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
963	if (attached_handler_name || m->hw_handler_name) {
964	INIT_DELAYED_WORK(&p->activate_path, activate_path_work);
965	r = setup_scsi_dh(bdev: p->path.dev->bdev, m, attached_handler_name: &attached_handler_name, error: &ti->error);
966	kfree(objp: attached_handler_name);
967	if (r) {
968	dm_put_device(ti, d: p->path.dev);
969	goto bad;
970	}
971	}
972
973	r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
974	if (r) {
975	dm_put_device(ti, d: p->path.dev);
976	goto bad;
977	}
978
979	return p;
980	bad:
981	free_pgpath(pgpath: p);
982	return ERR_PTR(error: r);
983	}
984
985	static struct priority_group *parse_priority_group(struct dm_arg_set *as,
986	struct multipath *m)
987	{
988	static const struct dm_arg _args[] = {
989	{1, 1024, "invalid number of paths"},
990	{0, 1024, "invalid number of selector args"}
991	};
992
993	int r;
994	unsigned int i, nr_selector_args, nr_args;
995	struct priority_group *pg;
996	struct dm_target *ti = m->ti;
997
998	if (as->argc < 2) {
999	as->argc = 0;
1000	ti->error = "not enough priority group arguments";
1001	return ERR_PTR(error: -EINVAL);
1002	}
1003
1004	pg = alloc_priority_group();
1005	if (!pg) {
1006	ti->error = "couldn't allocate priority group";
1007	return ERR_PTR(error: -ENOMEM);
1008	}
1009	pg->m = m;
1010
1011	r = parse_path_selector(as, pg, ti);
1012	if (r)
1013	goto bad;
1014
1015	/*
1016	* read the paths
1017	*/
1018	r = dm_read_arg(arg: _args, arg_set: as, value: &pg->nr_pgpaths, error: &ti->error);
1019	if (r)
1020	goto bad;
1021
1022	r = dm_read_arg(arg: _args + 1, arg_set: as, value: &nr_selector_args, error: &ti->error);
1023	if (r)
1024	goto bad;
1025
1026	nr_args = 1 + nr_selector_args;
1027	for (i = 0; i < pg->nr_pgpaths; i++) {
1028	struct pgpath *pgpath;
1029	struct dm_arg_set path_args;
1030
1031	if (as->argc < nr_args) {
1032	ti->error = "not enough path parameters";
1033	r = -EINVAL;
1034	goto bad;
1035	}
1036
1037	path_args.argc = nr_args;
1038	path_args.argv = as->argv;
1039
1040	pgpath = parse_path(as: &path_args, ps: &pg->ps, ti);
1041	if (IS_ERR(ptr: pgpath)) {
1042	r = PTR_ERR(ptr: pgpath);
1043	goto bad;
1044	}
1045
1046	pgpath->pg = pg;
1047	list_add_tail(new: &pgpath->list, head: &pg->pgpaths);
1048	dm_consume_args(as, num_args: nr_args);
1049	}
1050
1051	return pg;
1052
1053	bad:
1054	free_priority_group(pg, ti);
1055	return ERR_PTR(error: r);
1056	}
1057
1058	static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
1059	{
1060	unsigned int hw_argc;
1061	int ret;
1062	struct dm_target *ti = m->ti;
1063
1064	static const struct dm_arg _args[] = {
1065	{0, 1024, "invalid number of hardware handler args"},
1066	};
1067
1068	if (dm_read_arg_group(arg: _args, arg_set: as, num_args: &hw_argc, error: &ti->error))
1069	return -EINVAL;
1070
1071	if (!hw_argc)
1072	return 0;
1073
1074	if (m->queue_mode == DM_TYPE_BIO_BASED) {
1075	dm_consume_args(as, num_args: hw_argc);
1076	DMERR("bio-based multipath doesn't allow hardware handler args");
1077	return 0;
1078	}
1079
1080	m->hw_handler_name = kstrdup(s: dm_shift_arg(as), GFP_KERNEL);
1081	if (!m->hw_handler_name)
1082	return -EINVAL;
1083
1084	if (hw_argc > 1) {
1085	char *p;
1086	int i, j, len = 4;
1087
1088	for (i = 0; i <= hw_argc - 2; i++)
1089	len += strlen(as->argv[i]) + 1;
1090	p = m->hw_handler_params = kzalloc(size: len, GFP_KERNEL);
1091	if (!p) {
1092	ti->error = "memory allocation failed";
1093	ret = -ENOMEM;
1094	goto fail;
1095	}
1096	j = sprintf(buf: p, fmt: "%d", hw_argc - 1);
1097	for (i = 0, p += j + 1; i <= hw_argc - 2; i++, p += j + 1)
1098	j = sprintf(buf: p, fmt: "%s", as->argv[i]);
1099	}
1100	dm_consume_args(as, num_args: hw_argc - 1);
1101
1102	return 0;
1103	fail:
1104	kfree(objp: m->hw_handler_name);
1105	m->hw_handler_name = NULL;
1106	return ret;
1107	}
1108
1109	static int parse_features(struct dm_arg_set *as, struct multipath *m)
1110	{
1111	int r;
1112	unsigned int argc;
1113	struct dm_target *ti = m->ti;
1114	const char *arg_name;
1115
1116	static const struct dm_arg _args[] = {
1117	{0, 8, "invalid number of feature args"},
1118	{1, 50, "pg_init_retries must be between 1 and 50"},
1119	{0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
1120	};
1121
1122	r = dm_read_arg_group(arg: _args, arg_set: as, num_args: &argc, error: &ti->error);
1123	if (r)
1124	return -EINVAL;
1125
1126	if (!argc)
1127	return 0;
1128
1129	do {
1130	arg_name = dm_shift_arg(as);
1131	argc--;
1132
1133	if (!strcasecmp(s1: arg_name, s2: "queue_if_no_path")) {
1134	r = queue_if_no_path(m, f_queue_if_no_path: true, save_old_value: false, caller: __func__);
1135	continue;
1136	}
1137
1138	if (!strcasecmp(s1: arg_name, s2: "retain_attached_hw_handler")) {
1139	set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, addr: &m->flags);
1140	continue;
1141	}
1142
1143	if (!strcasecmp(s1: arg_name, s2: "pg_init_retries") &&
1144	(argc >= 1)) {
1145	r = dm_read_arg(arg: _args + 1, arg_set: as, value: &m->pg_init_retries, error: &ti->error);
1146	argc--;
1147	continue;
1148	}
1149
1150	if (!strcasecmp(s1: arg_name, s2: "pg_init_delay_msecs") &&
1151	(argc >= 1)) {
1152	r = dm_read_arg(arg: _args + 2, arg_set: as, value: &m->pg_init_delay_msecs, error: &ti->error);
1153	argc--;
1154	continue;
1155	}
1156
1157	if (!strcasecmp(s1: arg_name, s2: "queue_mode") &&
1158	(argc >= 1)) {
1159	const char *queue_mode_name = dm_shift_arg(as);
1160
1161	if (!strcasecmp(s1: queue_mode_name, s2: "bio"))
1162	m->queue_mode = DM_TYPE_BIO_BASED;
1163	else if (!strcasecmp(s1: queue_mode_name, s2: "rq") ||
1164	!strcasecmp(s1: queue_mode_name, s2: "mq"))
1165	m->queue_mode = DM_TYPE_REQUEST_BASED;
1166	else {
1167	ti->error = "Unknown 'queue_mode' requested";
1168	r = -EINVAL;
1169	}
1170	argc--;
1171	continue;
1172	}
1173
1174	ti->error = "Unrecognised multipath feature request";
1175	r = -EINVAL;
1176	} while (argc && !r);
1177
1178	return r;
1179	}
1180
1181	static int multipath_ctr(struct dm_target *ti, unsigned int argc, char **argv)
1182	{
1183	/* target arguments */
1184	static const struct dm_arg _args[] = {
1185	{0, 1024, "invalid number of priority groups"},
1186	{0, 1024, "invalid initial priority group number"},
1187	};
1188
1189	int r;
1190	struct multipath *m;
1191	struct dm_arg_set as;
1192	unsigned int pg_count = 0;
1193	unsigned int next_pg_num;
1194	unsigned long flags;
1195
1196	as.argc = argc;
1197	as.argv = argv;
1198
1199	m = alloc_multipath(ti);
1200	if (!m) {
1201	ti->error = "can't allocate multipath";
1202	return -EINVAL;
1203	}
1204
1205	r = parse_features(as: &as, m);
1206	if (r)
1207	goto bad;
1208
1209	r = alloc_multipath_stage2(ti, m);
1210	if (r)
1211	goto bad;
1212
1213	r = parse_hw_handler(as: &as, m);
1214	if (r)
1215	goto bad;
1216
1217	r = dm_read_arg(arg: _args, arg_set: &as, value: &m->nr_priority_groups, error: &ti->error);
1218	if (r)
1219	goto bad;
1220
1221	r = dm_read_arg(arg: _args + 1, arg_set: &as, value: &next_pg_num, error: &ti->error);
1222	if (r)
1223	goto bad;
1224
1225	if ((!m->nr_priority_groups && next_pg_num) ||
1226	(m->nr_priority_groups && !next_pg_num)) {
1227	ti->error = "invalid initial priority group";
1228	r = -EINVAL;
1229	goto bad;
1230	}
1231
1232	/* parse the priority groups */
1233	while (as.argc) {
1234	struct priority_group *pg;
1235	unsigned int nr_valid_paths = atomic_read(v: &m->nr_valid_paths);
1236
1237	pg = parse_priority_group(as: &as, m);
1238	if (IS_ERR(ptr: pg)) {
1239	r = PTR_ERR(ptr: pg);
1240	goto bad;
1241	}
1242
1243	nr_valid_paths += pg->nr_pgpaths;
1244	atomic_set(v: &m->nr_valid_paths, i: nr_valid_paths);
1245
1246	list_add_tail(new: &pg->list, head: &m->priority_groups);
1247	pg_count++;
1248	pg->pg_num = pg_count;
1249	if (!--next_pg_num)
1250	m->next_pg = pg;
1251	}
1252
1253	if (pg_count != m->nr_priority_groups) {
1254	ti->error = "priority group count mismatch";
1255	r = -EINVAL;
1256	goto bad;
1257	}
1258
1259	spin_lock_irqsave(&m->lock, flags);
1260	enable_nopath_timeout(m);
1261	spin_unlock_irqrestore(lock: &m->lock, flags);
1262
1263	ti->num_flush_bios = 1;
1264	ti->num_discard_bios = 1;
1265	ti->num_write_zeroes_bios = 1;
1266	if (m->queue_mode == DM_TYPE_BIO_BASED)
1267	ti->per_io_data_size = multipath_per_bio_data_size();
1268	else
1269	ti->per_io_data_size = sizeof(struct dm_mpath_io);
1270
1271	return 0;
1272
1273	bad:
1274	free_multipath(m);
1275	return r;
1276	}
1277
1278	static void multipath_wait_for_pg_init_completion(struct multipath *m)
1279	{
1280	DEFINE_WAIT(wait);
1281
1282	while (1) {
1283	prepare_to_wait(wq_head: &m->pg_init_wait, wq_entry: &wait, TASK_UNINTERRUPTIBLE);
1284
1285	if (!atomic_read(v: &m->pg_init_in_progress))
1286	break;
1287
1288	io_schedule();
1289	}
1290	finish_wait(wq_head: &m->pg_init_wait, wq_entry: &wait);
1291	}
1292
1293	static void flush_multipath_work(struct multipath *m)
1294	{
1295	if (m->hw_handler_name) {
1296	unsigned long flags;
1297
1298	if (!atomic_read(v: &m->pg_init_in_progress))
1299	goto skip;
1300
1301	spin_lock_irqsave(&m->lock, flags);
1302	if (atomic_read(v: &m->pg_init_in_progress) &&
1303	!test_and_set_bit(MPATHF_PG_INIT_DISABLED, addr: &m->flags)) {
1304	spin_unlock_irqrestore(lock: &m->lock, flags);
1305
1306	flush_workqueue(kmpath_handlerd);
1307	multipath_wait_for_pg_init_completion(m);
1308
1309	spin_lock_irqsave(&m->lock, flags);
1310	clear_bit(MPATHF_PG_INIT_DISABLED, addr: &m->flags);
1311	}
1312	spin_unlock_irqrestore(lock: &m->lock, flags);
1313	}
1314	skip:
1315	if (m->queue_mode == DM_TYPE_BIO_BASED)
1316	flush_work(work: &m->process_queued_bios);
1317	flush_work(work: &m->trigger_event);
1318	}
1319
1320	static void multipath_dtr(struct dm_target *ti)
1321	{
1322	struct multipath *m = ti->private;
1323
1324	disable_nopath_timeout(m);
1325	flush_multipath_work(m);
1326	free_multipath(m);
1327	}
1328
1329	/*
1330	* Take a path out of use.
1331	*/
1332	static int fail_path(struct pgpath *pgpath)
1333	{
1334	unsigned long flags;
1335	struct multipath *m = pgpath->pg->m;
1336
1337	spin_lock_irqsave(&m->lock, flags);
1338
1339	if (!pgpath->is_active)
1340	goto out;
1341
1342	DMWARN("%s: Failing path %s.",
1343	dm_table_device_name(m->ti->table),
1344	pgpath->path.dev->name);
1345
1346	pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
1347	pgpath->is_active = false;
1348	pgpath->fail_count++;
1349
1350	atomic_dec(v: &m->nr_valid_paths);
1351
1352	if (pgpath == m->current_pgpath)
1353	m->current_pgpath = NULL;
1354
1355	dm_path_uevent(event_type: DM_UEVENT_PATH_FAILED, ti: m->ti,
1356	path: pgpath->path.dev->name, nr_valid_paths: atomic_read(v: &m->nr_valid_paths));
1357
1358	queue_work(wq: dm_mpath_wq, work: &m->trigger_event);
1359
1360	enable_nopath_timeout(m);
1361
1362	out:
1363	spin_unlock_irqrestore(lock: &m->lock, flags);
1364
1365	return 0;
1366	}
1367
1368	/*
1369	* Reinstate a previously-failed path
1370	*/
1371	static int reinstate_path(struct pgpath *pgpath)
1372	{
1373	int r = 0, run_queue = 0;
1374	unsigned long flags;
1375	struct multipath *m = pgpath->pg->m;
1376	unsigned int nr_valid_paths;
1377
1378	spin_lock_irqsave(&m->lock, flags);
1379
1380	if (pgpath->is_active)
1381	goto out;
1382
1383	DMWARN("%s: Reinstating path %s.",
1384	dm_table_device_name(m->ti->table),
1385	pgpath->path.dev->name);
1386
1387	r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1388	if (r)
1389	goto out;
1390
1391	pgpath->is_active = true;
1392
1393	nr_valid_paths = atomic_inc_return(v: &m->nr_valid_paths);
1394	if (nr_valid_paths == 1) {
1395	m->current_pgpath = NULL;
1396	run_queue = 1;
1397	} else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1398	if (queue_work(wq: kmpath_handlerd, work: &pgpath->activate_path.work))
1399	atomic_inc(v: &m->pg_init_in_progress);
1400	}
1401
1402	dm_path_uevent(event_type: DM_UEVENT_PATH_REINSTATED, ti: m->ti,
1403	path: pgpath->path.dev->name, nr_valid_paths);
1404
1405	schedule_work(work: &m->trigger_event);
1406
1407	out:
1408	spin_unlock_irqrestore(lock: &m->lock, flags);
1409	if (run_queue) {
1410	dm_table_run_md_queue_async(t: m->ti->table);
1411	process_queued_io_list(m);
1412	}
1413
1414	if (pgpath->is_active)
1415	disable_nopath_timeout(m);
1416
1417	return r;
1418	}
1419
1420	/*
1421	* Fail or reinstate all paths that match the provided struct dm_dev.
1422	*/
1423	static int action_dev(struct multipath *m, struct dm_dev *dev,
1424	action_fn action)
1425	{
1426	int r = -EINVAL;
1427	struct pgpath *pgpath;
1428	struct priority_group *pg;
1429
1430	list_for_each_entry(pg, &m->priority_groups, list) {
1431	list_for_each_entry(pgpath, &pg->pgpaths, list) {
1432	if (pgpath->path.dev == dev)
1433	r = action(pgpath);
1434	}
1435	}
1436
1437	return r;
1438	}
1439
1440	/*
1441	* Temporarily try to avoid having to use the specified PG
1442	*/
1443	static void bypass_pg(struct multipath *m, struct priority_group *pg,
1444	bool bypassed)
1445	{
1446	unsigned long flags;
1447
1448	spin_lock_irqsave(&m->lock, flags);
1449
1450	pg->bypassed = bypassed;
1451	m->current_pgpath = NULL;
1452	m->current_pg = NULL;
1453
1454	spin_unlock_irqrestore(lock: &m->lock, flags);
1455
1456	schedule_work(work: &m->trigger_event);
1457	}
1458
1459	/*
1460	* Switch to using the specified PG from the next I/O that gets mapped
1461	*/
1462	static int switch_pg_num(struct multipath *m, const char *pgstr)
1463	{
1464	struct priority_group *pg;
1465	unsigned int pgnum;
1466	unsigned long flags;
1467	char dummy;
1468
1469	if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1470	!m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
1471	DMWARN("invalid PG number supplied to %s", __func__);
1472	return -EINVAL;
1473	}
1474
1475	spin_lock_irqsave(&m->lock, flags);
1476	list_for_each_entry(pg, &m->priority_groups, list) {
1477	pg->bypassed = false;
1478	if (--pgnum)
1479	continue;
1480
1481	m->current_pgpath = NULL;
1482	m->current_pg = NULL;
1483	m->next_pg = pg;
1484	}
1485	spin_unlock_irqrestore(lock: &m->lock, flags);
1486
1487	schedule_work(work: &m->trigger_event);
1488	return 0;
1489	}
1490
1491	/*
1492	* Set/clear bypassed status of a PG.
1493	* PGs are numbered upwards from 1 in the order they were declared.
1494	*/
1495	static int bypass_pg_num(struct multipath *m, const char *pgstr, bool bypassed)
1496	{
1497	struct priority_group *pg;
1498	unsigned int pgnum;
1499	char dummy;
1500
1501	if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1502	!m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
1503	DMWARN("invalid PG number supplied to bypass_pg");
1504	return -EINVAL;
1505	}
1506
1507	list_for_each_entry(pg, &m->priority_groups, list) {
1508	if (!--pgnum)
1509	break;
1510	}
1511
1512	bypass_pg(m, pg, bypassed);
1513	return 0;
1514	}
1515
1516	/*
1517	* Should we retry pg_init immediately?
1518	*/
1519	static bool pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1520	{
1521	unsigned long flags;
1522	bool limit_reached = false;
1523
1524	spin_lock_irqsave(&m->lock, flags);
1525
1526	if (atomic_read(v: &m->pg_init_count) <= m->pg_init_retries &&
1527	!test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
1528	set_bit(MPATHF_PG_INIT_REQUIRED, addr: &m->flags);
1529	else
1530	limit_reached = true;
1531
1532	spin_unlock_irqrestore(lock: &m->lock, flags);
1533
1534	return limit_reached;
1535	}
1536
1537	static void pg_init_done(void *data, int errors)
1538	{
1539	struct pgpath *pgpath = data;
1540	struct priority_group *pg = pgpath->pg;
1541	struct multipath *m = pg->m;
1542	unsigned long flags;
1543	bool delay_retry = false;
1544
1545	/* device or driver problems */
1546	switch (errors) {
1547	case SCSI_DH_OK:
1548	break;
1549	case SCSI_DH_NOSYS:
1550	if (!m->hw_handler_name) {
1551	errors = 0;
1552	break;
1553	}
1554	DMERR("Could not failover the device: Handler scsi_dh_%s "
1555	"Error %d.", m->hw_handler_name, errors);
1556	/*
1557	* Fail path for now, so we do not ping pong
1558	*/
1559	fail_path(pgpath);
1560	break;
1561	case SCSI_DH_DEV_TEMP_BUSY:
1562	/*
1563	* Probably doing something like FW upgrade on the
1564	* controller so try the other pg.
1565	*/
1566	bypass_pg(m, pg, bypassed: true);
1567	break;
1568	case SCSI_DH_RETRY:
1569	/* Wait before retrying. */
1570	delay_retry = true;
1571	fallthrough;
1572	case SCSI_DH_IMM_RETRY:
1573	case SCSI_DH_RES_TEMP_UNAVAIL:
1574	if (pg_init_limit_reached(m, pgpath))
1575	fail_path(pgpath);
1576	errors = 0;
1577	break;
1578	case SCSI_DH_DEV_OFFLINED:
1579	default:
1580	/*
1581	* We probably do not want to fail the path for a device
1582	* error, but this is what the old dm did. In future
1583	* patches we can do more advanced handling.
1584	*/
1585	fail_path(pgpath);
1586	}
1587
1588	spin_lock_irqsave(&m->lock, flags);
1589	if (errors) {
1590	if (pgpath == m->current_pgpath) {
1591	DMERR("Could not failover device. Error %d.", errors);
1592	m->current_pgpath = NULL;
1593	m->current_pg = NULL;
1594	}
1595	} else if (!test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1596	pg->bypassed = false;
1597
1598	if (atomic_dec_return(v: &m->pg_init_in_progress) > 0)
1599	/* Activations of other paths are still on going */
1600	goto out;
1601
1602	if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
1603	if (delay_retry)
1604	set_bit(MPATHF_PG_INIT_DELAY_RETRY, addr: &m->flags);
1605	else
1606	clear_bit(MPATHF_PG_INIT_DELAY_RETRY, addr: &m->flags);
1607
1608	if (__pg_init_all_paths(m))
1609	goto out;
1610	}
1611	clear_bit(MPATHF_QUEUE_IO, addr: &m->flags);
1612
1613	process_queued_io_list(m);
1614
1615	/*
1616	* Wake up any thread waiting to suspend.
1617	*/
1618	wake_up(&m->pg_init_wait);
1619
1620	out:
1621	spin_unlock_irqrestore(lock: &m->lock, flags);
1622	}
1623
1624	static void activate_or_offline_path(struct pgpath *pgpath)
1625	{
1626	struct request_queue *q = bdev_get_queue(bdev: pgpath->path.dev->bdev);
1627
1628	if (pgpath->is_active && !blk_queue_dying(q))
1629	scsi_dh_activate(q, pg_init_done, pgpath);
1630	else
1631	pg_init_done(data: pgpath, errors: SCSI_DH_DEV_OFFLINED);
1632	}
1633
1634	static void activate_path_work(struct work_struct *work)
1635	{
1636	struct pgpath *pgpath =
1637	container_of(work, struct pgpath, activate_path.work);
1638
1639	activate_or_offline_path(pgpath);
1640	}
1641
1642	static int multipath_end_io(struct dm_target *ti, struct request *clone,
1643	blk_status_t error, union map_info *map_context)
1644	{
1645	struct dm_mpath_io *mpio = get_mpio(info: map_context);
1646	struct pgpath *pgpath = mpio->pgpath;
1647	int r = DM_ENDIO_DONE;
1648
1649	/*
1650	* We don't queue any clone request inside the multipath target
1651	* during end I/O handling, since those clone requests don't have
1652	* bio clones. If we queue them inside the multipath target,
1653	* we need to make bio clones, that requires memory allocation.
1654	* (See drivers/md/dm-rq.c:end_clone_bio() about why the clone requests
1655	* don't have bio clones.)
1656	* Instead of queueing the clone request here, we queue the original
1657	* request into dm core, which will remake a clone request and
1658	* clone bios for it and resubmit it later.
1659	*/
1660	if (error && blk_path_error(error)) {
1661	struct multipath *m = ti->private;
1662
1663	if (error == BLK_STS_RESOURCE)
1664	r = DM_ENDIO_DELAY_REQUEUE;
1665	else
1666	r = DM_ENDIO_REQUEUE;
1667
1668	if (pgpath)
1669	fail_path(pgpath);
1670
1671	if (!atomic_read(v: &m->nr_valid_paths) &&
1672	!must_push_back_rq(m)) {
1673	if (error == BLK_STS_IOERR)
1674	dm_report_EIO(m);
1675	/* complete with the original error */
1676	r = DM_ENDIO_DONE;
1677	}
1678	}
1679
1680	if (pgpath) {
1681	struct path_selector *ps = &pgpath->pg->ps;
1682
1683	if (ps->type->end_io)
1684	ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes,
1685	clone->io_start_time_ns);
1686	}
1687
1688	return r;
1689	}
1690
1691	static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
1692	blk_status_t *error)
1693	{
1694	struct multipath *m = ti->private;
1695	struct dm_mpath_io *mpio = get_mpio_from_bio(bio: clone);
1696	struct pgpath *pgpath = mpio->pgpath;
1697	unsigned long flags;
1698	int r = DM_ENDIO_DONE;
1699
1700	if (!*error || !blk_path_error(error: *error))
1701	goto done;
1702
1703	if (pgpath)
1704	fail_path(pgpath);
1705
1706	if (!atomic_read(v: &m->nr_valid_paths)) {
1707	spin_lock_irqsave(&m->lock, flags);
1708	if (!test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
1709	if (__must_push_back(m)) {
1710	r = DM_ENDIO_REQUEUE;
1711	} else {
1712	dm_report_EIO(m);
1713	*error = BLK_STS_IOERR;
1714	}
1715	spin_unlock_irqrestore(lock: &m->lock, flags);
1716	goto done;
1717	}
1718	spin_unlock_irqrestore(lock: &m->lock, flags);
1719	}
1720
1721	multipath_queue_bio(m, bio: clone);
1722	r = DM_ENDIO_INCOMPLETE;
1723	done:
1724	if (pgpath) {
1725	struct path_selector *ps = &pgpath->pg->ps;
1726
1727	if (ps->type->end_io)
1728	ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes,
1729	(mpio->start_time_ns ?:
1730	dm_start_time_ns_from_clone(bio: clone)));
1731	}
1732
1733	return r;
1734	}
1735
1736	/*
1737	* Suspend with flush can't complete until all the I/O is processed
1738	* so if the last path fails we must error any remaining I/O.
1739	* - Note that if the freeze_bdev fails while suspending, the
1740	* queue_if_no_path state is lost - userspace should reset it.
1741	* Otherwise, during noflush suspend, queue_if_no_path will not change.
1742	*/
1743	static void multipath_presuspend(struct dm_target *ti)
1744	{
1745	struct multipath *m = ti->private;
1746
1747	/* FIXME: bio-based shouldn't need to always disable queue_if_no_path */
1748	if (m->queue_mode == DM_TYPE_BIO_BASED || !dm_noflush_suspending(ti: m->ti))
1749	queue_if_no_path(m, f_queue_if_no_path: false, save_old_value: true, caller: __func__);
1750	}
1751
1752	static void multipath_postsuspend(struct dm_target *ti)
1753	{
1754	struct multipath *m = ti->private;
1755
1756	mutex_lock(&m->work_mutex);
1757	flush_multipath_work(m);
1758	mutex_unlock(lock: &m->work_mutex);
1759	}
1760
1761	/*
1762	* Restore the queue_if_no_path setting.
1763	*/
1764	static void multipath_resume(struct dm_target *ti)
1765	{
1766	struct multipath *m = ti->private;
1767	unsigned long flags;
1768
1769	spin_lock_irqsave(&m->lock, flags);
1770	if (test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags)) {
1771	set_bit(MPATHF_QUEUE_IF_NO_PATH, addr: &m->flags);
1772	clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, addr: &m->flags);
1773	}
1774
1775	DMDEBUG("%s: %s finished; QIFNP = %d; SQIFNP = %d",
1776	dm_table_device_name(m->ti->table), __func__,
1777	test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags),
1778	test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags));
1779
1780	spin_unlock_irqrestore(lock: &m->lock, flags);
1781	}
1782
1783	/*
1784	* Info output has the following format:
1785	* num_multipath_feature_args [multipath_feature_args]*
1786	* num_handler_status_args [handler_status_args]*
1787	* num_groups init_group_number
1788	* [A|D|E num_ps_status_args [ps_status_args]*
1789	* num_paths num_selector_args
1790	* [path_dev A|F fail_count [selector_args]* ]+ ]+
1791	*
1792	* Table output has the following format (identical to the constructor string):
1793	* num_feature_args [features_args]*
1794	* num_handler_args hw_handler [hw_handler_args]*
1795	* num_groups init_group_number
1796	* [priority selector-name num_ps_args [ps_args]*
1797	* num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1798	*/
1799	static void multipath_status(struct dm_target *ti, status_type_t type,
1800	unsigned int status_flags, char *result, unsigned int maxlen)
1801	{
1802	int sz = 0, pg_counter, pgpath_counter;
1803	unsigned long flags;
1804	struct multipath *m = ti->private;
1805	struct priority_group *pg;
1806	struct pgpath *p;
1807	unsigned int pg_num;
1808	char state;
1809
1810	spin_lock_irqsave(&m->lock, flags);
1811
1812	/* Features */
1813	if (type == STATUSTYPE_INFO)
1814	DMEMIT("2 %u %u ", test_bit(MPATHF_QUEUE_IO, &m->flags),
1815	atomic_read(&m->pg_init_count));
1816	else {
1817	DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) +
1818	(m->pg_init_retries > 0) * 2 +
1819	(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
1820	test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) +
1821	(m->queue_mode != DM_TYPE_REQUEST_BASED) * 2);
1822
1823	if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1824	DMEMIT("queue_if_no_path ");
1825	if (m->pg_init_retries)
1826	DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1827	if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1828	DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1829	if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags))
1830	DMEMIT("retain_attached_hw_handler ");
1831	if (m->queue_mode != DM_TYPE_REQUEST_BASED) {
1832	switch (m->queue_mode) {
1833	case DM_TYPE_BIO_BASED:
1834	DMEMIT("queue_mode bio ");
1835	break;
1836	default:
1837	WARN_ON_ONCE(true);
1838	break;
1839	}
1840	}
1841	}
1842
1843	if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1844	DMEMIT("0 ");
1845	else
1846	DMEMIT("1 %s ", m->hw_handler_name);
1847
1848	DMEMIT("%u ", m->nr_priority_groups);
1849
1850	if (m->next_pg)
1851	pg_num = m->next_pg->pg_num;
1852	else if (m->current_pg)
1853	pg_num = m->current_pg->pg_num;
1854	else
1855	pg_num = (m->nr_priority_groups ? 1 : 0);
1856
1857	DMEMIT("%u ", pg_num);
1858
1859	switch (type) {
1860	case STATUSTYPE_INFO:
1861	list_for_each_entry(pg, &m->priority_groups, list) {
1862	if (pg->bypassed)
1863	state = 'D'; /* Disabled */
1864	else if (pg == m->current_pg)
1865	state = 'A'; /* Currently Active */
1866	else
1867	state = 'E'; /* Enabled */
1868
1869	DMEMIT("%c ", state);
1870
1871	if (pg->ps.type->status)
1872	sz += pg->ps.type->status(&pg->ps, NULL, type,
1873	result + sz,
1874	maxlen - sz);
1875	else
1876	DMEMIT("0 ");
1877
1878	DMEMIT("%u %u ", pg->nr_pgpaths,
1879	pg->ps.type->info_args);
1880
1881	list_for_each_entry(p, &pg->pgpaths, list) {
1882	DMEMIT("%s %s %u ", p->path.dev->name,
1883	p->is_active ? "A" : "F",
1884	p->fail_count);
1885	if (pg->ps.type->status)
1886	sz += pg->ps.type->status(&pg->ps,
1887	&p->path, type, result + sz,
1888	maxlen - sz);
1889	}
1890	}
1891	break;
1892
1893	case STATUSTYPE_TABLE:
1894	list_for_each_entry(pg, &m->priority_groups, list) {
1895	DMEMIT("%s ", pg->ps.type->name);
1896
1897	if (pg->ps.type->status)
1898	sz += pg->ps.type->status(&pg->ps, NULL, type,
1899	result + sz,
1900	maxlen - sz);
1901	else
1902	DMEMIT("0 ");
1903
1904	DMEMIT("%u %u ", pg->nr_pgpaths,
1905	pg->ps.type->table_args);
1906
1907	list_for_each_entry(p, &pg->pgpaths, list) {
1908	DMEMIT("%s ", p->path.dev->name);
1909	if (pg->ps.type->status)
1910	sz += pg->ps.type->status(&pg->ps,
1911	&p->path, type, result + sz,
1912	maxlen - sz);
1913	}
1914	}
1915	break;
1916
1917	case STATUSTYPE_IMA:
1918	sz = 0; /*reset the result pointer*/
1919
1920	DMEMIT_TARGET_NAME_VERSION(ti->type);
1921	DMEMIT(",nr_priority_groups=%u", m->nr_priority_groups);
1922
1923	pg_counter = 0;
1924	list_for_each_entry(pg, &m->priority_groups, list) {
1925	if (pg->bypassed)
1926	state = 'D'; /* Disabled */
1927	else if (pg == m->current_pg)
1928	state = 'A'; /* Currently Active */
1929	else
1930	state = 'E'; /* Enabled */
1931	DMEMIT(",pg_state_%d=%c", pg_counter, state);
1932	DMEMIT(",nr_pgpaths_%d=%u", pg_counter, pg->nr_pgpaths);
1933	DMEMIT(",path_selector_name_%d=%s", pg_counter, pg->ps.type->name);
1934
1935	pgpath_counter = 0;
1936	list_for_each_entry(p, &pg->pgpaths, list) {
1937	DMEMIT(",path_name_%d_%d=%s,is_active_%d_%d=%c,fail_count_%d_%d=%u",
1938	pg_counter, pgpath_counter, p->path.dev->name,
1939	pg_counter, pgpath_counter, p->is_active ? 'A' : 'F',
1940	pg_counter, pgpath_counter, p->fail_count);
1941	if (pg->ps.type->status) {
1942	DMEMIT(",path_selector_status_%d_%d=",
1943	pg_counter, pgpath_counter);
1944	sz += pg->ps.type->status(&pg->ps, &p->path,
1945	type, result + sz,
1946	maxlen - sz);
1947	}
1948	pgpath_counter++;
1949	}
1950	pg_counter++;
1951	}
1952	DMEMIT(";");
1953	break;
1954	}
1955
1956	spin_unlock_irqrestore(lock: &m->lock, flags);
1957	}
1958
1959	static int multipath_message(struct dm_target *ti, unsigned int argc, char **argv,
1960	char *result, unsigned int maxlen)
1961	{
1962	int r = -EINVAL;
1963	struct dm_dev *dev;
1964	struct multipath *m = ti->private;
1965	action_fn action;
1966	unsigned long flags;
1967
1968	mutex_lock(&m->work_mutex);
1969
1970	if (dm_suspended(ti)) {
1971	r = -EBUSY;
1972	goto out;
1973	}
1974
1975	if (argc == 1) {
1976	if (!strcasecmp(s1: argv[0], s2: "queue_if_no_path")) {
1977	r = queue_if_no_path(m, f_queue_if_no_path: true, save_old_value: false, caller: __func__);
1978	spin_lock_irqsave(&m->lock, flags);
1979	enable_nopath_timeout(m);
1980	spin_unlock_irqrestore(lock: &m->lock, flags);
1981	goto out;
1982	} else if (!strcasecmp(s1: argv[0], s2: "fail_if_no_path")) {
1983	r = queue_if_no_path(m, f_queue_if_no_path: false, save_old_value: false, caller: __func__);
1984	disable_nopath_timeout(m);
1985	goto out;
1986	}
1987	}
1988
1989	if (argc != 2) {
1990	DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc);
1991	goto out;
1992	}
1993
1994	if (!strcasecmp(s1: argv[0], s2: "disable_group")) {
1995	r = bypass_pg_num(m, pgstr: argv[1], bypassed: true);
1996	goto out;
1997	} else if (!strcasecmp(s1: argv[0], s2: "enable_group")) {
1998	r = bypass_pg_num(m, pgstr: argv[1], bypassed: false);
1999	goto out;
2000	} else if (!strcasecmp(s1: argv[0], s2: "switch_group")) {
2001	r = switch_pg_num(m, pgstr: argv[1]);
2002	goto out;
2003	} else if (!strcasecmp(s1: argv[0], s2: "reinstate_path"))
2004	action = reinstate_path;
2005	else if (!strcasecmp(s1: argv[0], s2: "fail_path"))
2006	action = fail_path;
2007	else {
2008	DMWARN("Unrecognised multipath message received: %s", argv[0]);
2009	goto out;
2010	}
2011
2012	r = dm_get_device(ti, path: argv[1], mode: dm_table_get_mode(t: ti->table), result: &dev);
2013	if (r) {
2014	DMWARN("message: error getting device %s",
2015	argv[1]);
2016	goto out;
2017	}
2018
2019	r = action_dev(m, dev, action);
2020
2021	dm_put_device(ti, d: dev);
2022
2023	out:
2024	mutex_unlock(lock: &m->work_mutex);
2025	return r;
2026	}
2027
2028	static int multipath_prepare_ioctl(struct dm_target *ti,
2029	struct block_device **bdev)
2030	{
2031	struct multipath *m = ti->private;
2032	struct pgpath *pgpath;
2033	unsigned long flags;
2034	int r;
2035
2036	pgpath = READ_ONCE(m->current_pgpath);
2037	if (!pgpath || !mpath_double_check_test_bit(MPATHF_QUEUE_IO, m))
2038	pgpath = choose_pgpath(m, nr_bytes: 0);
2039
2040	if (pgpath) {
2041	if (!mpath_double_check_test_bit(MPATHF_QUEUE_IO, m)) {
2042	*bdev = pgpath->path.dev->bdev;
2043	r = 0;
2044	} else {
2045	/* pg_init has not started or completed */
2046	r = -ENOTCONN;
2047	}
2048	} else {
2049	/* No path is available */
2050	r = -EIO;
2051	spin_lock_irqsave(&m->lock, flags);
2052	if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
2053	r = -ENOTCONN;
2054	spin_unlock_irqrestore(lock: &m->lock, flags);
2055	}
2056
2057	if (r == -ENOTCONN) {
2058	if (!READ_ONCE(m->current_pg)) {
2059	/* Path status changed, redo selection */
2060	(void) choose_pgpath(m, nr_bytes: 0);
2061	}
2062	spin_lock_irqsave(&m->lock, flags);
2063	if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
2064	(void) __pg_init_all_paths(m);
2065	spin_unlock_irqrestore(lock: &m->lock, flags);
2066	dm_table_run_md_queue_async(t: m->ti->table);
2067	process_queued_io_list(m);
2068	}
2069
2070	/*
2071	* Only pass ioctls through if the device sizes match exactly.
2072	*/
2073	if (!r && ti->len != bdev_nr_sectors(bdev: (*bdev)))
2074	return 1;
2075	return r;
2076	}
2077
2078	static int multipath_iterate_devices(struct dm_target *ti,
2079	iterate_devices_callout_fn fn, void *data)
2080	{
2081	struct multipath *m = ti->private;
2082	struct priority_group *pg;
2083	struct pgpath *p;
2084	int ret = 0;
2085
2086	list_for_each_entry(pg, &m->priority_groups, list) {
2087	list_for_each_entry(p, &pg->pgpaths, list) {
2088	ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
2089	if (ret)
2090	goto out;
2091	}
2092	}
2093
2094	out:
2095	return ret;
2096	}
2097
2098	static int pgpath_busy(struct pgpath *pgpath)
2099	{
2100	struct request_queue *q = bdev_get_queue(bdev: pgpath->path.dev->bdev);
2101
2102	return blk_lld_busy(q);
2103	}
2104
2105	/*
2106	* We return "busy", only when we can map I/Os but underlying devices
2107	* are busy (so even if we map I/Os now, the I/Os will wait on
2108	* the underlying queue).
2109	* In other words, if we want to kill I/Os or queue them inside us
2110	* due to map unavailability, we don't return "busy". Otherwise,
2111	* dm core won't give us the I/Os and we can't do what we want.
2112	*/
2113	static int multipath_busy(struct dm_target *ti)
2114	{
2115	bool busy = false, has_active = false;
2116	struct multipath *m = ti->private;
2117	struct priority_group *pg, *next_pg;
2118	struct pgpath *pgpath;
2119
2120	/* pg_init in progress */
2121	if (atomic_read(v: &m->pg_init_in_progress))
2122	return true;
2123
2124	/* no paths available, for blk-mq: rely on IO mapping to delay requeue */
2125	if (!atomic_read(v: &m->nr_valid_paths)) {
2126	unsigned long flags;
2127
2128	spin_lock_irqsave(&m->lock, flags);
2129	if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
2130	spin_unlock_irqrestore(lock: &m->lock, flags);
2131	return (m->queue_mode != DM_TYPE_REQUEST_BASED);
2132	}
2133	spin_unlock_irqrestore(lock: &m->lock, flags);
2134	}
2135
2136	/* Guess which priority_group will be used at next mapping time */
2137	pg = READ_ONCE(m->current_pg);
2138	next_pg = READ_ONCE(m->next_pg);
2139	if (unlikely(!READ_ONCE(m->current_pgpath) && next_pg))
2140	pg = next_pg;
2141
2142	if (!pg) {
2143	/*
2144	* We don't know which pg will be used at next mapping time.
2145	* We don't call choose_pgpath() here to avoid to trigger
2146	* pg_init just by busy checking.
2147	* So we don't know whether underlying devices we will be using
2148	* at next mapping time are busy or not. Just try mapping.
2149	*/
2150	return busy;
2151	}
2152
2153	/*
2154	* If there is one non-busy active path at least, the path selector
2155	* will be able to select it. So we consider such a pg as not busy.
2156	*/
2157	busy = true;
2158	list_for_each_entry(pgpath, &pg->pgpaths, list) {
2159	if (pgpath->is_active) {
2160	has_active = true;
2161	if (!pgpath_busy(pgpath)) {
2162	busy = false;
2163	break;
2164	}
2165	}
2166	}
2167
2168	if (!has_active) {
2169	/*
2170	* No active path in this pg, so this pg won't be used and
2171	* the current_pg will be changed at next mapping time.
2172	* We need to try mapping to determine it.
2173	*/
2174	busy = false;
2175	}
2176
2177	return busy;
2178	}
2179
2180	/*
2181	*---------------------------------------------------------------
2182	* Module setup
2183	*---------------------------------------------------------------
2184	*/
2185	static struct target_type multipath_target = {
2186	.name = "multipath",
2187	.version = {1, 14, 0},
2188	.features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE |
2189	DM_TARGET_PASSES_INTEGRITY,
2190	.module = THIS_MODULE,
2191	.ctr = multipath_ctr,
2192	.dtr = multipath_dtr,
2193	.clone_and_map_rq = multipath_clone_and_map,
2194	.release_clone_rq = multipath_release_clone,
2195	.rq_end_io = multipath_end_io,
2196	.map = multipath_map_bio,
2197	.end_io = multipath_end_io_bio,
2198	.presuspend = multipath_presuspend,
2199	.postsuspend = multipath_postsuspend,
2200	.resume = multipath_resume,
2201	.status = multipath_status,
2202	.message = multipath_message,
2203	.prepare_ioctl = multipath_prepare_ioctl,
2204	.iterate_devices = multipath_iterate_devices,
2205	.busy = multipath_busy,
2206	};
2207
2208	static int __init dm_multipath_init(void)
2209	{
2210	int r = -ENOMEM;
2211
2212	kmultipathd = alloc_workqueue(fmt: "kmpathd", flags: WQ_MEM_RECLAIM, max_active: 0);
2213	if (!kmultipathd) {
2214	DMERR("failed to create workqueue kmpathd");
2215	goto bad_alloc_kmultipathd;
2216	}
2217
2218	/*
2219	* A separate workqueue is used to handle the device handlers
2220	* to avoid overloading existing workqueue. Overloading the
2221	* old workqueue would also create a bottleneck in the
2222	* path of the storage hardware device activation.
2223	*/
2224	kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
2225	WQ_MEM_RECLAIM);
2226	if (!kmpath_handlerd) {
2227	DMERR("failed to create workqueue kmpath_handlerd");
2228	goto bad_alloc_kmpath_handlerd;
2229	}
2230
2231	dm_mpath_wq = alloc_workqueue(fmt: "dm_mpath_wq", flags: 0, max_active: 0);
2232	if (!dm_mpath_wq) {
2233	DMERR("failed to create workqueue dm_mpath_wq");
2234	goto bad_alloc_dm_mpath_wq;
2235	}
2236
2237	r = dm_register_target(t: &multipath_target);
2238	if (r < 0)
2239	goto bad_register_target;
2240
2241	return 0;
2242
2243	bad_register_target:
2244	destroy_workqueue(wq: dm_mpath_wq);
2245	bad_alloc_dm_mpath_wq:
2246	destroy_workqueue(wq: kmpath_handlerd);
2247	bad_alloc_kmpath_handlerd:
2248	destroy_workqueue(wq: kmultipathd);
2249	bad_alloc_kmultipathd:
2250	return r;
2251	}
2252
2253	static void __exit dm_multipath_exit(void)
2254	{
2255	destroy_workqueue(wq: dm_mpath_wq);
2256	destroy_workqueue(wq: kmpath_handlerd);
2257	destroy_workqueue(wq: kmultipathd);
2258
2259	dm_unregister_target(t: &multipath_target);
2260	}
2261
2262	module_init(dm_multipath_init);
2263	module_exit(dm_multipath_exit);
2264
2265	module_param_named(queue_if_no_path_timeout_secs, queue_if_no_path_timeout_secs, ulong, 0644);
2266	MODULE_PARM_DESC(queue_if_no_path_timeout_secs, "No available paths queue IO timeout in seconds");
2267
2268	MODULE_DESCRIPTION(DM_NAME " multipath target");
2269	MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
2270	MODULE_LICENSE("GPL");
2271