xref: /openbmc/linux/drivers/md/dm-mpath.c (revision b362c733)
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 
mpath_double_check_test_bit(int MPATHF_bit,struct multipath * m)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(&m->lock, flags);
146 	}
147 
148 	return r;
149 }
150 
151 /*
152  *-----------------------------------------------
153  * Allocation routines
154  *-----------------------------------------------
155  */
alloc_pgpath(void)156 static struct pgpath *alloc_pgpath(void)
157 {
158 	struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL);
159 
160 	if (!pgpath)
161 		return NULL;
162 
163 	pgpath->is_active = true;
164 
165 	return pgpath;
166 }
167 
free_pgpath(struct pgpath * pgpath)168 static void free_pgpath(struct pgpath *pgpath)
169 {
170 	kfree(pgpath);
171 }
172 
alloc_priority_group(void)173 static struct priority_group *alloc_priority_group(void)
174 {
175 	struct priority_group *pg;
176 
177 	pg = kzalloc(sizeof(*pg), GFP_KERNEL);
178 
179 	if (pg)
180 		INIT_LIST_HEAD(&pg->pgpaths);
181 
182 	return pg;
183 }
184 
free_pgpaths(struct list_head * pgpaths,struct dm_target * ti)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(&pgpath->list);
191 		dm_put_device(ti, pgpath->path.dev);
192 		free_pgpath(pgpath);
193 	}
194 }
195 
free_priority_group(struct priority_group * pg,struct dm_target * ti)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(ps->type);
204 	}
205 
206 	free_pgpaths(&pg->pgpaths, ti);
207 	kfree(pg);
208 }
209 
alloc_multipath(struct dm_target * ti)210 static struct multipath *alloc_multipath(struct dm_target *ti)
211 {
212 	struct multipath *m;
213 
214 	m = kzalloc(sizeof(*m), GFP_KERNEL);
215 	if (m) {
216 		INIT_LIST_HEAD(&m->priority_groups);
217 		spin_lock_init(&m->lock);
218 		atomic_set(&m->nr_valid_paths, 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 
alloc_multipath_stage2(struct dm_target * ti,struct multipath * m)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, &m->flags);
244 	}
245 
246 	dm_table_set_type(ti->table, 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, &m->flags);
253 	atomic_set(&m->pg_init_in_progress, 0);
254 	atomic_set(&m->pg_init_count, 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 
free_multipath(struct multipath * m)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(&pg->list);
267 		free_priority_group(pg, m->ti);
268 	}
269 
270 	kfree(m->hw_handler_name);
271 	kfree(m->hw_handler_params);
272 	mutex_destroy(&m->work_mutex);
273 	kfree(m);
274 }
275 
get_mpio(union map_info * info)276 static struct dm_mpath_io *get_mpio(union map_info *info)
277 {
278 	return info->ptr;
279 }
280 
multipath_per_bio_data_size(void)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 
get_mpio_from_bio(struct bio * bio)286 static struct dm_mpath_io *get_mpio_from_bio(struct bio *bio)
287 {
288 	return dm_per_bio_data(bio, multipath_per_bio_data_size());
289 }
290 
get_bio_details_from_mpio(struct dm_mpath_io * mpio)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 
multipath_init_per_bio_data(struct bio * bio,struct dm_mpath_io ** mpio_p)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(bio_details, bio);
309 }
310 
311 /*
312  *-----------------------------------------------
313  * Path selection
314  *-----------------------------------------------
315  */
__pg_init_all_paths(struct multipath * m)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(&m->pg_init_in_progress) || test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
324 		return 0;
325 
326 	atomic_inc(&m->pg_init_count);
327 	clear_bit(MPATHF_PG_INIT_REQUIRED, &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->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(kmpath_handlerd, &pgpath->activate_path,
341 				       pg_init_delay))
342 			atomic_inc(&m->pg_init_in_progress);
343 	}
344 	return atomic_read(&m->pg_init_in_progress);
345 }
346 
pg_init_all_paths(struct multipath * m)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(&m->lock, flags);
355 
356 	return ret;
357 }
358 
__switch_pg(struct multipath * m,struct priority_group * pg)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, &m->flags);
368 		set_bit(MPATHF_QUEUE_IO, &m->flags);
369 	} else {
370 		clear_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
371 		clear_bit(MPATHF_QUEUE_IO, &m->flags);
372 	}
373 
374 	atomic_set(&m->pg_init_count, 0);
375 }
376 
choose_path_in_pg(struct multipath * m,struct priority_group * pg,size_t nr_bytes)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(-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(&m->lock, flags);
397 	}
398 
399 	return pgpath;
400 }
401 
choose_pgpath(struct multipath * m,size_t nr_bytes)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(&m->nr_valid_paths)) {
410 		spin_lock_irqsave(&m->lock, flags);
411 		clear_bit(MPATHF_QUEUE_IO, &m->flags);
412 		spin_unlock_irqrestore(&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(&m->lock, flags);
422 			goto check_current_pg;
423 		}
424 		m->next_pg = NULL;
425 		spin_unlock_irqrestore(&m->lock, flags);
426 		pgpath = choose_path_in_pg(m, pg, nr_bytes);
427 		if (!IS_ERR_OR_NULL(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(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(pgpath)) {
452 				if (!bypassed) {
453 					spin_lock_irqsave(&m->lock, flags);
454 					set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
455 					spin_unlock_irqrestore(&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(&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  */
__must_push_back(struct multipath * m)487 static bool __must_push_back(struct multipath *m)
488 {
489 	return dm_noflush_suspending(m->ti);
490 }
491 
must_push_back_rq(struct multipath * m)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(&m->lock, flags);
500 
501 	return ret;
502 }
503 
504 /*
505  * Map cloned requests (request-based multipath)
506  */
multipath_clone_and_map(struct dm_target * ti,struct request * rq,union map_info * map_context,struct request ** __clone)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(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, rq->cmd_flags | REQ_NOMERGE,
541 			BLK_MQ_REQ_NOWAIT);
542 	if (IS_ERR(clone)) {
543 		/* EBUSY, ENODEV or EWOULDBLOCK: requeue */
544 		if (blk_queue_dying(q)) {
545 			atomic_inc(&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 
multipath_release_clone(struct request * clone,union map_info * map_context)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(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(clone);
589 }
590 
591 /*
592  * Map cloned bios (bio-based multipath)
593  */
594 
__multipath_queue_bio(struct multipath * m,struct bio * bio)595 static void __multipath_queue_bio(struct multipath *m, struct bio *bio)
596 {
597 	/* Queue for the daemon to resubmit */
598 	bio_list_add(&m->queued_bios, bio);
599 	if (!test_bit(MPATHF_QUEUE_IO, &m->flags))
600 		queue_work(kmultipathd, &m->process_queued_bios);
601 }
602 
multipath_queue_bio(struct multipath * m,struct bio * bio)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(&m->lock, flags);
610 }
611 
__map_bio(struct multipath * m,struct bio * bio)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, 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(-EAGAIN);
627 		}
628 		spin_unlock_irqrestore(&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(-EAGAIN);
635 	}
636 
637 	return pgpath;
638 }
639 
__multipath_map_bio(struct multipath * m,struct bio * bio,struct dm_mpath_io * mpio)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(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, 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 
multipath_map_bio(struct dm_target * ti,struct bio * bio)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);
677 	return __multipath_map_bio(m, bio, mpio);
678 }
679 
process_queued_io_list(struct multipath * m)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(dm_table_get_md(m->ti->table));
684 	else if (m->queue_mode == DM_TYPE_BIO_BASED)
685 		queue_work(kmultipathd, &m->process_queued_bios);
686 }
687 
process_queued_bios(struct work_struct * work)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(&bios);
699 
700 	spin_lock_irqsave(&m->lock, flags);
701 
702 	if (bio_list_empty(&m->queued_bios)) {
703 		spin_unlock_irqrestore(&m->lock, flags);
704 		return;
705 	}
706 
707 	bio_list_merge(&bios, &m->queued_bios);
708 	bio_list_init(&m->queued_bios);
709 
710 	spin_unlock_irqrestore(&m->lock, flags);
711 
712 	blk_start_plug(&plug);
713 	while ((bio = bio_list_pop(&bios))) {
714 		struct dm_mpath_io *mpio = get_mpio_from_bio(bio);
715 
716 		dm_bio_restore(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  */
queue_if_no_path(struct multipath * m,bool f_queue_if_no_path,bool save_old_value,const char * caller)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(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, &m->flags, 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, &m->flags);
766 	}
767 	assign_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags, 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(&m->lock, flags);
776 
777 	if (!f_queue_if_no_path) {
778 		dm_table_run_md_queue_async(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  */
queue_if_no_path_timeout_work(struct timer_list * t)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, false, false, __func__);
796 }
797 
798 /*
799  * Enable the queue_if_no_path timeout if necessary.
800  * Called with m->lock held.
801  */
enable_nopath_timeout(struct multipath * m)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(&m->nr_valid_paths) == 0 &&
811 	    test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
812 		mod_timer(&m->nopath_timer,
813 			  jiffies + queue_if_no_path_timeout);
814 	}
815 }
816 
disable_nopath_timeout(struct multipath * m)817 static void disable_nopath_timeout(struct multipath *m)
818 {
819 	del_timer_sync(&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  */
trigger_event(struct work_struct * work)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(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  */
parse_path_selector(struct dm_arg_set * as,struct priority_group * pg,struct dm_target * ti)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(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(_args, as, &ps_argc, &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, ps_argc);
878 
879 	return 0;
880 }
881 
setup_scsi_dh(struct block_device * bdev,struct multipath * m,const char ** attached_handler_name,char ** error)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(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(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 
parse_path(struct dm_arg_set * as,struct path_selector * ps,struct dm_target * ti)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(-EINVAL);
948 	}
949 
950 	p = alloc_pgpath();
951 	if (!p)
952 		return ERR_PTR(-ENOMEM);
953 
954 	r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
955 			  &p->path.dev);
956 	if (r) {
957 		ti->error = "error getting device";
958 		goto bad;
959 	}
960 
961 	q = bdev_get_queue(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(p->path.dev->bdev, m, &attached_handler_name, &ti->error);
966 		kfree(attached_handler_name);
967 		if (r) {
968 			dm_put_device(ti, 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, p->path.dev);
976 		goto bad;
977 	}
978 
979 	return p;
980  bad:
981 	free_pgpath(p);
982 	return ERR_PTR(r);
983 }
984 
parse_priority_group(struct dm_arg_set * as,struct multipath * m)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(-EINVAL);
1002 	}
1003 
1004 	pg = alloc_priority_group();
1005 	if (!pg) {
1006 		ti->error = "couldn't allocate priority group";
1007 		return ERR_PTR(-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(_args, as, &pg->nr_pgpaths, &ti->error);
1019 	if (r)
1020 		goto bad;
1021 
1022 	r = dm_read_arg(_args + 1, as, &nr_selector_args, &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(&path_args, &pg->ps, ti);
1041 		if (IS_ERR(pgpath)) {
1042 			r = PTR_ERR(pgpath);
1043 			goto bad;
1044 		}
1045 
1046 		pgpath->pg = pg;
1047 		list_add_tail(&pgpath->list, &pg->pgpaths);
1048 		dm_consume_args(as, nr_args);
1049 	}
1050 
1051 	return pg;
1052 
1053  bad:
1054 	free_priority_group(pg, ti);
1055 	return ERR_PTR(r);
1056 }
1057 
parse_hw_handler(struct dm_arg_set * as,struct multipath * m)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(_args, as, &hw_argc, &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, hw_argc);
1076 		DMERR("bio-based multipath doesn't allow hardware handler args");
1077 		return 0;
1078 	}
1079 
1080 	m->hw_handler_name = kstrdup(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(len, GFP_KERNEL);
1091 		if (!p) {
1092 			ti->error = "memory allocation failed";
1093 			ret = -ENOMEM;
1094 			goto fail;
1095 		}
1096 		j = sprintf(p, "%d", hw_argc - 1);
1097 		for (i = 0, p += j + 1; i <= hw_argc - 2; i++, p += j + 1)
1098 			j = sprintf(p, "%s", as->argv[i]);
1099 	}
1100 	dm_consume_args(as, hw_argc - 1);
1101 
1102 	return 0;
1103 fail:
1104 	kfree(m->hw_handler_name);
1105 	m->hw_handler_name = NULL;
1106 	return ret;
1107 }
1108 
parse_features(struct dm_arg_set * as,struct multipath * m)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(_args, as, &argc, &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(arg_name, "queue_if_no_path")) {
1134 			r = queue_if_no_path(m, true, false, __func__);
1135 			continue;
1136 		}
1137 
1138 		if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
1139 			set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
1140 			continue;
1141 		}
1142 
1143 		if (!strcasecmp(arg_name, "pg_init_retries") &&
1144 		    (argc >= 1)) {
1145 			r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
1146 			argc--;
1147 			continue;
1148 		}
1149 
1150 		if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
1151 		    (argc >= 1)) {
1152 			r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
1153 			argc--;
1154 			continue;
1155 		}
1156 
1157 		if (!strcasecmp(arg_name, "queue_mode") &&
1158 		    (argc >= 1)) {
1159 			const char *queue_mode_name = dm_shift_arg(as);
1160 
1161 			if (!strcasecmp(queue_mode_name, "bio"))
1162 				m->queue_mode = DM_TYPE_BIO_BASED;
1163 			else if (!strcasecmp(queue_mode_name, "rq") ||
1164 				 !strcasecmp(queue_mode_name, "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 
multipath_ctr(struct dm_target * ti,unsigned int argc,char ** argv)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, 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, m);
1214 	if (r)
1215 		goto bad;
1216 
1217 	r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
1218 	if (r)
1219 		goto bad;
1220 
1221 	r = dm_read_arg(_args + 1, &as, &next_pg_num, &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(&m->nr_valid_paths);
1236 
1237 		pg = parse_priority_group(&as, m);
1238 		if (IS_ERR(pg)) {
1239 			r = PTR_ERR(pg);
1240 			goto bad;
1241 		}
1242 
1243 		nr_valid_paths += pg->nr_pgpaths;
1244 		atomic_set(&m->nr_valid_paths, nr_valid_paths);
1245 
1246 		list_add_tail(&pg->list, &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(&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 
multipath_wait_for_pg_init_completion(struct multipath * m)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(&m->pg_init_wait, &wait, TASK_UNINTERRUPTIBLE);
1284 
1285 		if (!atomic_read(&m->pg_init_in_progress))
1286 			break;
1287 
1288 		io_schedule();
1289 	}
1290 	finish_wait(&m->pg_init_wait, &wait);
1291 }
1292 
flush_multipath_work(struct multipath * m)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(&m->pg_init_in_progress))
1299 			goto skip;
1300 
1301 		spin_lock_irqsave(&m->lock, flags);
1302 		if (atomic_read(&m->pg_init_in_progress) &&
1303 		    !test_and_set_bit(MPATHF_PG_INIT_DISABLED, &m->flags)) {
1304 			spin_unlock_irqrestore(&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, &m->flags);
1311 		}
1312 		spin_unlock_irqrestore(&m->lock, flags);
1313 	}
1314 skip:
1315 	if (m->queue_mode == DM_TYPE_BIO_BASED)
1316 		flush_work(&m->process_queued_bios);
1317 	flush_work(&m->trigger_event);
1318 }
1319 
multipath_dtr(struct dm_target * ti)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  */
fail_path(struct pgpath * pgpath)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(&m->nr_valid_paths);
1351 
1352 	if (pgpath == m->current_pgpath)
1353 		m->current_pgpath = NULL;
1354 
1355 	dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
1356 		       pgpath->path.dev->name, atomic_read(&m->nr_valid_paths));
1357 
1358 	queue_work(dm_mpath_wq, &m->trigger_event);
1359 
1360 	enable_nopath_timeout(m);
1361 
1362 out:
1363 	spin_unlock_irqrestore(&m->lock, flags);
1364 
1365 	return 0;
1366 }
1367 
1368 /*
1369  * Reinstate a previously-failed path
1370  */
reinstate_path(struct pgpath * pgpath)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(&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(kmpath_handlerd, &pgpath->activate_path.work))
1399 			atomic_inc(&m->pg_init_in_progress);
1400 	}
1401 
1402 	dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1403 		       pgpath->path.dev->name, nr_valid_paths);
1404 
1405 	schedule_work(&m->trigger_event);
1406 
1407 out:
1408 	spin_unlock_irqrestore(&m->lock, flags);
1409 	if (run_queue) {
1410 		dm_table_run_md_queue_async(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  */
action_dev(struct multipath * m,struct dm_dev * dev,action_fn action)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  */
bypass_pg(struct multipath * m,struct priority_group * pg,bool bypassed)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(&m->lock, flags);
1455 
1456 	schedule_work(&m->trigger_event);
1457 }
1458 
1459 /*
1460  * Switch to using the specified PG from the next I/O that gets mapped
1461  */
switch_pg_num(struct multipath * m,const char * pgstr)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(&m->lock, flags);
1486 
1487 	schedule_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  */
bypass_pg_num(struct multipath * m,const char * pgstr,bool bypassed)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  */
pg_init_limit_reached(struct multipath * m,struct pgpath * pgpath)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(&m->pg_init_count) <= m->pg_init_retries &&
1527 	    !test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
1528 		set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
1529 	else
1530 		limit_reached = true;
1531 
1532 	spin_unlock_irqrestore(&m->lock, flags);
1533 
1534 	return limit_reached;
1535 }
1536 
pg_init_done(void * data,int errors)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, 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(&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, &m->flags);
1605 		else
1606 			clear_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1607 
1608 		if (__pg_init_all_paths(m))
1609 			goto out;
1610 	}
1611 	clear_bit(MPATHF_QUEUE_IO, &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(&m->lock, flags);
1622 }
1623 
activate_or_offline_path(struct pgpath * pgpath)1624 static void activate_or_offline_path(struct pgpath *pgpath)
1625 {
1626 	struct request_queue *q = bdev_get_queue(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(pgpath, SCSI_DH_DEV_OFFLINED);
1632 }
1633 
activate_path_work(struct work_struct * work)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 
multipath_end_io(struct dm_target * ti,struct request * clone,blk_status_t error,union map_info * map_context)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(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(&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 
multipath_end_io_bio(struct dm_target * ti,struct bio * clone,blk_status_t * error)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(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))
1701 		goto done;
1702 
1703 	if (pgpath)
1704 		fail_path(pgpath);
1705 
1706 	if (!atomic_read(&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(&m->lock, flags);
1716 			goto done;
1717 		}
1718 		spin_unlock_irqrestore(&m->lock, flags);
1719 	}
1720 
1721 	multipath_queue_bio(m, 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(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  */
multipath_presuspend(struct dm_target * ti)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(m->ti))
1749 		queue_if_no_path(m, false, true, __func__);
1750 }
1751 
multipath_postsuspend(struct dm_target * ti)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(&m->work_mutex);
1759 }
1760 
1761 /*
1762  * Restore the queue_if_no_path setting.
1763  */
multipath_resume(struct dm_target * ti)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, &m->flags);
1772 		clear_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &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(&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  */
multipath_status(struct dm_target * ti,status_type_t type,unsigned int status_flags,char * result,unsigned int maxlen)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(&m->lock, flags);
1957 }
1958 
multipath_message(struct dm_target * ti,unsigned int argc,char ** argv,char * result,unsigned int maxlen)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(argv[0], "queue_if_no_path")) {
1977 			r = queue_if_no_path(m, true, false, __func__);
1978 			spin_lock_irqsave(&m->lock, flags);
1979 			enable_nopath_timeout(m);
1980 			spin_unlock_irqrestore(&m->lock, flags);
1981 			goto out;
1982 		} else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1983 			r = queue_if_no_path(m, false, false, __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(argv[0], "disable_group")) {
1995 		r = bypass_pg_num(m, argv[1], true);
1996 		goto out;
1997 	} else if (!strcasecmp(argv[0], "enable_group")) {
1998 		r = bypass_pg_num(m, argv[1], false);
1999 		goto out;
2000 	} else if (!strcasecmp(argv[0], "switch_group")) {
2001 		r = switch_pg_num(m, argv[1]);
2002 		goto out;
2003 	} else if (!strcasecmp(argv[0], "reinstate_path"))
2004 		action = reinstate_path;
2005 	else if (!strcasecmp(argv[0], "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, argv[1], dm_table_get_mode(ti->table), &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, dev);
2022 
2023 out:
2024 	mutex_unlock(&m->work_mutex);
2025 	return r;
2026 }
2027 
multipath_prepare_ioctl(struct dm_target * ti,struct block_device ** bdev)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, 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(&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, 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(&m->lock, flags);
2066 		dm_table_run_md_queue_async(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)))
2074 		return 1;
2075 	return r;
2076 }
2077 
multipath_iterate_devices(struct dm_target * ti,iterate_devices_callout_fn fn,void * data)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 
pgpath_busy(struct pgpath * pgpath)2098 static int pgpath_busy(struct pgpath *pgpath)
2099 {
2100 	struct request_queue *q = bdev_get_queue(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  */
multipath_busy(struct dm_target * ti)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(&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(&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(&m->lock, flags);
2131 			return (m->queue_mode != DM_TYPE_REQUEST_BASED);
2132 		}
2133 		spin_unlock_irqrestore(&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 
dm_multipath_init(void)2208 static int __init dm_multipath_init(void)
2209 {
2210 	int r = -ENOMEM;
2211 
2212 	kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 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("dm_mpath_wq", 0, 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(&multipath_target);
2238 	if (r < 0)
2239 		goto bad_register_target;
2240 
2241 	return 0;
2242 
2243 bad_register_target:
2244 	destroy_workqueue(dm_mpath_wq);
2245 bad_alloc_dm_mpath_wq:
2246 	destroy_workqueue(kmpath_handlerd);
2247 bad_alloc_kmpath_handlerd:
2248 	destroy_workqueue(kmultipathd);
2249 bad_alloc_kmultipathd:
2250 	return r;
2251 }
2252 
dm_multipath_exit(void)2253 static void __exit dm_multipath_exit(void)
2254 {
2255 	destroy_workqueue(dm_mpath_wq);
2256 	destroy_workqueue(kmpath_handlerd);
2257 	destroy_workqueue(kmultipathd);
2258 
2259 	dm_unregister_target(&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