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