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arm64: dts: marvell: mark the cp110 crypto engine as dma coherent
[linux-2.6/btrfs-unstable.git] / drivers / md / dm-mpath.c
blob0e8ab5bb3575fccf24a5734d1f5fe8149210b6aa
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(lockless_dereference(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 (lockless_dereference(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 = lockless_dereference(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 = lockless_dereference(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 DMERR_LIMIT("blk_get_request() returned %ld%s - requeuing",
503 PTR_ERR(clone), queue_dying ? " (path offline)" : "");
504 if (queue_dying) {
505 atomic_inc(&m->pg_init_in_progress);
506 activate_or_offline_path(pgpath);
507 return DM_MAPIO_REQUEUE;
508 }
509 return DM_MAPIO_DELAY_REQUEUE;
510 }
511 clone->bio = clone->biotail = NULL;
512 clone->rq_disk = bdev->bd_disk;
513 clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
514 *__clone = clone;
515
516 if (pgpath->pg->ps.type->start_io)
517 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
518 &pgpath->path,
519 nr_bytes);
520 return DM_MAPIO_REMAPPED;
521 }
522
523 static void multipath_release_clone(struct request *clone)
524 {
525 blk_put_request(clone);
526 }
527
528 /*
529 * Map cloned bios (bio-based multipath)
530 */
531 static int __multipath_map_bio(struct multipath *m, struct bio *bio, struct dm_mpath_io *mpio)
532 {
533 size_t nr_bytes = bio->bi_iter.bi_size;
534 struct pgpath *pgpath;
535 unsigned long flags;
536 bool queue_io;
537
538 /* Do we need to select a new pgpath? */
539 pgpath = lockless_dereference(m->current_pgpath);
540 queue_io = test_bit(MPATHF_QUEUE_IO, &m->flags);
541 if (!pgpath || !queue_io)
542 pgpath = choose_pgpath(m, nr_bytes);
543
544 if ((pgpath && queue_io) ||
545 (!pgpath && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))) {
546 /* Queue for the daemon to resubmit */
547 spin_lock_irqsave(&m->lock, flags);
548 bio_list_add(&m->queued_bios, bio);
549 spin_unlock_irqrestore(&m->lock, flags);
550 /* PG_INIT_REQUIRED cannot be set without QUEUE_IO */
551 if (queue_io || test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
552 pg_init_all_paths(m);
553 else if (!queue_io)
554 queue_work(kmultipathd, &m->process_queued_bios);
555 return DM_MAPIO_SUBMITTED;
556 }
557
558 if (!pgpath) {
559 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
560 return DM_MAPIO_REQUEUE;
561 dm_report_EIO(m);
562 return DM_MAPIO_KILL;
563 }
564
565 mpio->pgpath = pgpath;
566 mpio->nr_bytes = nr_bytes;
567
568 bio->bi_status = 0;
569 bio->bi_bdev = pgpath->path.dev->bdev;
570 bio->bi_opf |= REQ_FAILFAST_TRANSPORT;
571
572 if (pgpath->pg->ps.type->start_io)
573 pgpath->pg->ps.type->start_io(&pgpath->pg->ps,
574 &pgpath->path,
575 nr_bytes);
576 return DM_MAPIO_REMAPPED;
577 }
578
579 static int multipath_map_bio(struct dm_target *ti, struct bio *bio)
580 {
581 struct multipath *m = ti->private;
582 struct dm_mpath_io *mpio = NULL;
583
584 multipath_init_per_bio_data(bio, &mpio, NULL);
585
586 return __multipath_map_bio(m, bio, mpio);
587 }
588
589 static void process_queued_io_list(struct multipath *m)
590 {
591 if (m->queue_mode == DM_TYPE_MQ_REQUEST_BASED)
592 dm_mq_kick_requeue_list(dm_table_get_md(m->ti->table));
593 else if (m->queue_mode == DM_TYPE_BIO_BASED)
594 queue_work(kmultipathd, &m->process_queued_bios);
595 }
596
597 static void process_queued_bios(struct work_struct *work)
598 {
599 int r;
600 unsigned long flags;
601 struct bio *bio;
602 struct bio_list bios;
603 struct blk_plug plug;
604 struct multipath *m =
605 container_of(work, struct multipath, process_queued_bios);
606
607 bio_list_init(&bios);
608
609 spin_lock_irqsave(&m->lock, flags);
610
611 if (bio_list_empty(&m->queued_bios)) {
612 spin_unlock_irqrestore(&m->lock, flags);
613 return;
614 }
615
616 bio_list_merge(&bios, &m->queued_bios);
617 bio_list_init(&m->queued_bios);
618
619 spin_unlock_irqrestore(&m->lock, flags);
620
621 blk_start_plug(&plug);
622 while ((bio = bio_list_pop(&bios))) {
623 r = __multipath_map_bio(m, bio, get_mpio_from_bio(bio));
624 switch (r) {
625 case DM_MAPIO_KILL:
626 bio->bi_status = BLK_STS_IOERR;
627 bio_endio(bio);
628 break;
629 case DM_MAPIO_REQUEUE:
630 bio->bi_status = BLK_STS_DM_REQUEUE;
631 bio_endio(bio);
632 break;
633 case DM_MAPIO_REMAPPED:
634 generic_make_request(bio);
635 break;
636 }
637 }
638 blk_finish_plug(&plug);
639 }
640
641 static void assign_bit(bool value, long nr, unsigned long *addr)
642 {
643 if (value)
644 set_bit(nr, addr);
645 else
646 clear_bit(nr, addr);
647 }
648
649 /*
650 * If we run out of usable paths, should we queue I/O or error it?
651 */
652 static int queue_if_no_path(struct multipath *m, bool queue_if_no_path,
653 bool save_old_value)
654 {
655 unsigned long flags;
656
657 spin_lock_irqsave(&m->lock, flags);
658 assign_bit((save_old_value && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) ||
659 (!save_old_value && queue_if_no_path),
660 MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags);
661 assign_bit(queue_if_no_path || dm_noflush_suspending(m->ti),
662 MPATHF_QUEUE_IF_NO_PATH, &m->flags);
663 spin_unlock_irqrestore(&m->lock, flags);
664
665 if (!queue_if_no_path) {
666 dm_table_run_md_queue_async(m->ti->table);
667 process_queued_io_list(m);
668 }
669
670 return 0;
671 }
672
673 /*
674 * An event is triggered whenever a path is taken out of use.
675 * Includes path failure and PG bypass.
676 */
677 static void trigger_event(struct work_struct *work)
678 {
679 struct multipath *m =
680 container_of(work, struct multipath, trigger_event);
681
682 dm_table_event(m->ti->table);
683 }
684
685 /*-----------------------------------------------------------------
686 * Constructor/argument parsing:
687 * <#multipath feature args> [<arg>]*
688 * <#hw_handler args> [hw_handler [<arg>]*]
689 * <#priority groups>
690 * <initial priority group>
691 * [<selector> <#selector args> [<arg>]*
692 * <#paths> <#per-path selector args>
693 * [<path> [<arg>]* ]+ ]+
694 *---------------------------------------------------------------*/
695 static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg,
696 struct dm_target *ti)
697 {
698 int r;
699 struct path_selector_type *pst;
700 unsigned ps_argc;
701
702 static struct dm_arg _args[] = {
703 {0, 1024, "invalid number of path selector args"},
704 };
705
706 pst = dm_get_path_selector(dm_shift_arg(as));
707 if (!pst) {
708 ti->error = "unknown path selector type";
709 return -EINVAL;
710 }
711
712 r = dm_read_arg_group(_args, as, &ps_argc, &ti->error);
713 if (r) {
714 dm_put_path_selector(pst);
715 return -EINVAL;
716 }
717
718 r = pst->create(&pg->ps, ps_argc, as->argv);
719 if (r) {
720 dm_put_path_selector(pst);
721 ti->error = "path selector constructor failed";
722 return r;
723 }
724
725 pg->ps.type = pst;
726 dm_consume_args(as, ps_argc);
727
728 return 0;
729 }
730
731 static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps,
732 struct dm_target *ti)
733 {
734 int r;
735 struct pgpath *p;
736 struct multipath *m = ti->private;
737 struct request_queue *q = NULL;
738 const char *attached_handler_name;
739
740 /* we need at least a path arg */
741 if (as->argc < 1) {
742 ti->error = "no device given";
743 return ERR_PTR(-EINVAL);
744 }
745
746 p = alloc_pgpath();
747 if (!p)
748 return ERR_PTR(-ENOMEM);
749
750 r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table),
751 &p->path.dev);
752 if (r) {
753 ti->error = "error getting device";
754 goto bad;
755 }
756
757 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) || m->hw_handler_name)
758 q = bdev_get_queue(p->path.dev->bdev);
759
760 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags)) {
761 retain:
762 attached_handler_name = scsi_dh_attached_handler_name(q, GFP_KERNEL);
763 if (attached_handler_name) {
764 /*
765 * Clear any hw_handler_params associated with a
766 * handler that isn't already attached.
767 */
768 if (m->hw_handler_name && strcmp(attached_handler_name, m->hw_handler_name)) {
769 kfree(m->hw_handler_params);
770 m->hw_handler_params = NULL;
771 }
772
773 /*
774 * Reset hw_handler_name to match the attached handler
775 *
776 * NB. This modifies the table line to show the actual
777 * handler instead of the original table passed in.
778 */
779 kfree(m->hw_handler_name);
780 m->hw_handler_name = attached_handler_name;
781 }
782 }
783
784 if (m->hw_handler_name) {
785 r = scsi_dh_attach(q, m->hw_handler_name);
786 if (r == -EBUSY) {
787 char b[BDEVNAME_SIZE];
788
789 printk(KERN_INFO "dm-mpath: retaining handler on device %s\n",
790 bdevname(p->path.dev->bdev, b));
791 goto retain;
792 }
793 if (r < 0) {
794 ti->error = "error attaching hardware handler";
795 dm_put_device(ti, p->path.dev);
796 goto bad;
797 }
798
799 if (m->hw_handler_params) {
800 r = scsi_dh_set_params(q, m->hw_handler_params);
801 if (r < 0) {
802 ti->error = "unable to set hardware "
803 "handler parameters";
804 dm_put_device(ti, p->path.dev);
805 goto bad;
806 }
807 }
808 }
809
810 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error);
811 if (r) {
812 dm_put_device(ti, p->path.dev);
813 goto bad;
814 }
815
816 return p;
817
818 bad:
819 free_pgpath(p);
820 return ERR_PTR(r);
821 }
822
823 static struct priority_group *parse_priority_group(struct dm_arg_set *as,
824 struct multipath *m)
825 {
826 static struct dm_arg _args[] = {
827 {1, 1024, "invalid number of paths"},
828 {0, 1024, "invalid number of selector args"}
829 };
830
831 int r;
832 unsigned i, nr_selector_args, nr_args;
833 struct priority_group *pg;
834 struct dm_target *ti = m->ti;
835
836 if (as->argc < 2) {
837 as->argc = 0;
838 ti->error = "not enough priority group arguments";
839 return ERR_PTR(-EINVAL);
840 }
841
842 pg = alloc_priority_group();
843 if (!pg) {
844 ti->error = "couldn't allocate priority group";
845 return ERR_PTR(-ENOMEM);
846 }
847 pg->m = m;
848
849 r = parse_path_selector(as, pg, ti);
850 if (r)
851 goto bad;
852
853 /*
854 * read the paths
855 */
856 r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error);
857 if (r)
858 goto bad;
859
860 r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error);
861 if (r)
862 goto bad;
863
864 nr_args = 1 + nr_selector_args;
865 for (i = 0; i < pg->nr_pgpaths; i++) {
866 struct pgpath *pgpath;
867 struct dm_arg_set path_args;
868
869 if (as->argc < nr_args) {
870 ti->error = "not enough path parameters";
871 r = -EINVAL;
872 goto bad;
873 }
874
875 path_args.argc = nr_args;
876 path_args.argv = as->argv;
877
878 pgpath = parse_path(&path_args, &pg->ps, ti);
879 if (IS_ERR(pgpath)) {
880 r = PTR_ERR(pgpath);
881 goto bad;
882 }
883
884 pgpath->pg = pg;
885 list_add_tail(&pgpath->list, &pg->pgpaths);
886 dm_consume_args(as, nr_args);
887 }
888
889 return pg;
890
891 bad:
892 free_priority_group(pg, ti);
893 return ERR_PTR(r);
894 }
895
896 static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m)
897 {
898 unsigned hw_argc;
899 int ret;
900 struct dm_target *ti = m->ti;
901
902 static struct dm_arg _args[] = {
903 {0, 1024, "invalid number of hardware handler args"},
904 };
905
906 if (dm_read_arg_group(_args, as, &hw_argc, &ti->error))
907 return -EINVAL;
908
909 if (!hw_argc)
910 return 0;
911
912 if (m->queue_mode == DM_TYPE_BIO_BASED) {
913 dm_consume_args(as, hw_argc);
914 DMERR("bio-based multipath doesn't allow hardware handler args");
915 return 0;
916 }
917
918 m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
919 if (!m->hw_handler_name)
920 return -EINVAL;
921
922 if (hw_argc > 1) {
923 char *p;
924 int i, j, len = 4;
925
926 for (i = 0; i <= hw_argc - 2; i++)
927 len += strlen(as->argv[i]) + 1;
928 p = m->hw_handler_params = kzalloc(len, GFP_KERNEL);
929 if (!p) {
930 ti->error = "memory allocation failed";
931 ret = -ENOMEM;
932 goto fail;
933 }
934 j = sprintf(p, "%d", hw_argc - 1);
935 for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1)
936 j = sprintf(p, "%s", as->argv[i]);
937 }
938 dm_consume_args(as, hw_argc - 1);
939
940 return 0;
941 fail:
942 kfree(m->hw_handler_name);
943 m->hw_handler_name = NULL;
944 return ret;
945 }
946
947 static int parse_features(struct dm_arg_set *as, struct multipath *m)
948 {
949 int r;
950 unsigned argc;
951 struct dm_target *ti = m->ti;
952 const char *arg_name;
953
954 static struct dm_arg _args[] = {
955 {0, 8, "invalid number of feature args"},
956 {1, 50, "pg_init_retries must be between 1 and 50"},
957 {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"},
958 };
959
960 r = dm_read_arg_group(_args, as, &argc, &ti->error);
961 if (r)
962 return -EINVAL;
963
964 if (!argc)
965 return 0;
966
967 do {
968 arg_name = dm_shift_arg(as);
969 argc--;
970
971 if (!strcasecmp(arg_name, "queue_if_no_path")) {
972 r = queue_if_no_path(m, true, false);
973 continue;
974 }
975
976 if (!strcasecmp(arg_name, "retain_attached_hw_handler")) {
977 set_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags);
978 continue;
979 }
980
981 if (!strcasecmp(arg_name, "pg_init_retries") &&
982 (argc >= 1)) {
983 r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error);
984 argc--;
985 continue;
986 }
987
988 if (!strcasecmp(arg_name, "pg_init_delay_msecs") &&
989 (argc >= 1)) {
990 r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error);
991 argc--;
992 continue;
993 }
994
995 if (!strcasecmp(arg_name, "queue_mode") &&
996 (argc >= 1)) {
997 const char *queue_mode_name = dm_shift_arg(as);
998
999 if (!strcasecmp(queue_mode_name, "bio"))
1000 m->queue_mode = DM_TYPE_BIO_BASED;
1001 else if (!strcasecmp(queue_mode_name, "rq"))
1002 m->queue_mode = DM_TYPE_REQUEST_BASED;
1003 else if (!strcasecmp(queue_mode_name, "mq"))
1004 m->queue_mode = DM_TYPE_MQ_REQUEST_BASED;
1005 else {
1006 ti->error = "Unknown 'queue_mode' requested";
1007 r = -EINVAL;
1008 }
1009 argc--;
1010 continue;
1011 }
1012
1013 ti->error = "Unrecognised multipath feature request";
1014 r = -EINVAL;
1015 } while (argc && !r);
1016
1017 return r;
1018 }
1019
1020 static int multipath_ctr(struct dm_target *ti, unsigned argc, char **argv)
1021 {
1022 /* target arguments */
1023 static struct dm_arg _args[] = {
1024 {0, 1024, "invalid number of priority groups"},
1025 {0, 1024, "invalid initial priority group number"},
1026 };
1027
1028 int r;
1029 struct multipath *m;
1030 struct dm_arg_set as;
1031 unsigned pg_count = 0;
1032 unsigned next_pg_num;
1033
1034 as.argc = argc;
1035 as.argv = argv;
1036
1037 m = alloc_multipath(ti);
1038 if (!m) {
1039 ti->error = "can't allocate multipath";
1040 return -EINVAL;
1041 }
1042
1043 r = parse_features(&as, m);
1044 if (r)
1045 goto bad;
1046
1047 r = alloc_multipath_stage2(ti, m);
1048 if (r)
1049 goto bad;
1050
1051 r = parse_hw_handler(&as, m);
1052 if (r)
1053 goto bad;
1054
1055 r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error);
1056 if (r)
1057 goto bad;
1058
1059 r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error);
1060 if (r)
1061 goto bad;
1062
1063 if ((!m->nr_priority_groups && next_pg_num) ||
1064 (m->nr_priority_groups && !next_pg_num)) {
1065 ti->error = "invalid initial priority group";
1066 r = -EINVAL;
1067 goto bad;
1068 }
1069
1070 /* parse the priority groups */
1071 while (as.argc) {
1072 struct priority_group *pg;
1073 unsigned nr_valid_paths = atomic_read(&m->nr_valid_paths);
1074
1075 pg = parse_priority_group(&as, m);
1076 if (IS_ERR(pg)) {
1077 r = PTR_ERR(pg);
1078 goto bad;
1079 }
1080
1081 nr_valid_paths += pg->nr_pgpaths;
1082 atomic_set(&m->nr_valid_paths, nr_valid_paths);
1083
1084 list_add_tail(&pg->list, &m->priority_groups);
1085 pg_count++;
1086 pg->pg_num = pg_count;
1087 if (!--next_pg_num)
1088 m->next_pg = pg;
1089 }
1090
1091 if (pg_count != m->nr_priority_groups) {
1092 ti->error = "priority group count mismatch";
1093 r = -EINVAL;
1094 goto bad;
1095 }
1096
1097 ti->num_flush_bios = 1;
1098 ti->num_discard_bios = 1;
1099 ti->num_write_same_bios = 1;
1100 ti->num_write_zeroes_bios = 1;
1101 if (m->queue_mode == DM_TYPE_BIO_BASED)
1102 ti->per_io_data_size = multipath_per_bio_data_size();
1103 else
1104 ti->per_io_data_size = sizeof(struct dm_mpath_io);
1105
1106 return 0;
1107
1108 bad:
1109 free_multipath(m);
1110 return r;
1111 }
1112
1113 static void multipath_wait_for_pg_init_completion(struct multipath *m)
1114 {
1115 DEFINE_WAIT(wait);
1116
1117 while (1) {
1118 prepare_to_wait(&m->pg_init_wait, &wait, TASK_UNINTERRUPTIBLE);
1119
1120 if (!atomic_read(&m->pg_init_in_progress))
1121 break;
1122
1123 io_schedule();
1124 }
1125 finish_wait(&m->pg_init_wait, &wait);
1126 }
1127
1128 static void flush_multipath_work(struct multipath *m)
1129 {
1130 set_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
1131 smp_mb__after_atomic();
1132
1133 flush_workqueue(kmpath_handlerd);
1134 multipath_wait_for_pg_init_completion(m);
1135 flush_workqueue(kmultipathd);
1136 flush_work(&m->trigger_event);
1137
1138 clear_bit(MPATHF_PG_INIT_DISABLED, &m->flags);
1139 smp_mb__after_atomic();
1140 }
1141
1142 static void multipath_dtr(struct dm_target *ti)
1143 {
1144 struct multipath *m = ti->private;
1145
1146 flush_multipath_work(m);
1147 free_multipath(m);
1148 }
1149
1150 /*
1151 * Take a path out of use.
1152 */
1153 static int fail_path(struct pgpath *pgpath)
1154 {
1155 unsigned long flags;
1156 struct multipath *m = pgpath->pg->m;
1157
1158 spin_lock_irqsave(&m->lock, flags);
1159
1160 if (!pgpath->is_active)
1161 goto out;
1162
1163 DMWARN("Failing path %s.", pgpath->path.dev->name);
1164
1165 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path);
1166 pgpath->is_active = false;
1167 pgpath->fail_count++;
1168
1169 atomic_dec(&m->nr_valid_paths);
1170
1171 if (pgpath == m->current_pgpath)
1172 m->current_pgpath = NULL;
1173
1174 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti,
1175 pgpath->path.dev->name, atomic_read(&m->nr_valid_paths));
1176
1177 schedule_work(&m->trigger_event);
1178
1179 out:
1180 spin_unlock_irqrestore(&m->lock, flags);
1181
1182 return 0;
1183 }
1184
1185 /*
1186 * Reinstate a previously-failed path
1187 */
1188 static int reinstate_path(struct pgpath *pgpath)
1189 {
1190 int r = 0, run_queue = 0;
1191 unsigned long flags;
1192 struct multipath *m = pgpath->pg->m;
1193 unsigned nr_valid_paths;
1194
1195 spin_lock_irqsave(&m->lock, flags);
1196
1197 if (pgpath->is_active)
1198 goto out;
1199
1200 DMWARN("Reinstating path %s.", pgpath->path.dev->name);
1201
1202 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path);
1203 if (r)
1204 goto out;
1205
1206 pgpath->is_active = true;
1207
1208 nr_valid_paths = atomic_inc_return(&m->nr_valid_paths);
1209 if (nr_valid_paths == 1) {
1210 m->current_pgpath = NULL;
1211 run_queue = 1;
1212 } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) {
1213 if (queue_work(kmpath_handlerd, &pgpath->activate_path.work))
1214 atomic_inc(&m->pg_init_in_progress);
1215 }
1216
1217 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti,
1218 pgpath->path.dev->name, nr_valid_paths);
1219
1220 schedule_work(&m->trigger_event);
1221
1222 out:
1223 spin_unlock_irqrestore(&m->lock, flags);
1224 if (run_queue) {
1225 dm_table_run_md_queue_async(m->ti->table);
1226 process_queued_io_list(m);
1227 }
1228
1229 return r;
1230 }
1231
1232 /*
1233 * Fail or reinstate all paths that match the provided struct dm_dev.
1234 */
1235 static int action_dev(struct multipath *m, struct dm_dev *dev,
1236 action_fn action)
1237 {
1238 int r = -EINVAL;
1239 struct pgpath *pgpath;
1240 struct priority_group *pg;
1241
1242 list_for_each_entry(pg, &m->priority_groups, list) {
1243 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1244 if (pgpath->path.dev == dev)
1245 r = action(pgpath);
1246 }
1247 }
1248
1249 return r;
1250 }
1251
1252 /*
1253 * Temporarily try to avoid having to use the specified PG
1254 */
1255 static void bypass_pg(struct multipath *m, struct priority_group *pg,
1256 bool bypassed)
1257 {
1258 unsigned long flags;
1259
1260 spin_lock_irqsave(&m->lock, flags);
1261
1262 pg->bypassed = bypassed;
1263 m->current_pgpath = NULL;
1264 m->current_pg = NULL;
1265
1266 spin_unlock_irqrestore(&m->lock, flags);
1267
1268 schedule_work(&m->trigger_event);
1269 }
1270
1271 /*
1272 * Switch to using the specified PG from the next I/O that gets mapped
1273 */
1274 static int switch_pg_num(struct multipath *m, const char *pgstr)
1275 {
1276 struct priority_group *pg;
1277 unsigned pgnum;
1278 unsigned long flags;
1279 char dummy;
1280
1281 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1282 !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
1283 DMWARN("invalid PG number supplied to switch_pg_num");
1284 return -EINVAL;
1285 }
1286
1287 spin_lock_irqsave(&m->lock, flags);
1288 list_for_each_entry(pg, &m->priority_groups, list) {
1289 pg->bypassed = false;
1290 if (--pgnum)
1291 continue;
1292
1293 m->current_pgpath = NULL;
1294 m->current_pg = NULL;
1295 m->next_pg = pg;
1296 }
1297 spin_unlock_irqrestore(&m->lock, flags);
1298
1299 schedule_work(&m->trigger_event);
1300 return 0;
1301 }
1302
1303 /*
1304 * Set/clear bypassed status of a PG.
1305 * PGs are numbered upwards from 1 in the order they were declared.
1306 */
1307 static int bypass_pg_num(struct multipath *m, const char *pgstr, bool bypassed)
1308 {
1309 struct priority_group *pg;
1310 unsigned pgnum;
1311 char dummy;
1312
1313 if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum ||
1314 !m->nr_priority_groups || (pgnum > m->nr_priority_groups)) {
1315 DMWARN("invalid PG number supplied to bypass_pg");
1316 return -EINVAL;
1317 }
1318
1319 list_for_each_entry(pg, &m->priority_groups, list) {
1320 if (!--pgnum)
1321 break;
1322 }
1323
1324 bypass_pg(m, pg, bypassed);
1325 return 0;
1326 }
1327
1328 /*
1329 * Should we retry pg_init immediately?
1330 */
1331 static bool pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath)
1332 {
1333 unsigned long flags;
1334 bool limit_reached = false;
1335
1336 spin_lock_irqsave(&m->lock, flags);
1337
1338 if (atomic_read(&m->pg_init_count) <= m->pg_init_retries &&
1339 !test_bit(MPATHF_PG_INIT_DISABLED, &m->flags))
1340 set_bit(MPATHF_PG_INIT_REQUIRED, &m->flags);
1341 else
1342 limit_reached = true;
1343
1344 spin_unlock_irqrestore(&m->lock, flags);
1345
1346 return limit_reached;
1347 }
1348
1349 static void pg_init_done(void *data, int errors)
1350 {
1351 struct pgpath *pgpath = data;
1352 struct priority_group *pg = pgpath->pg;
1353 struct multipath *m = pg->m;
1354 unsigned long flags;
1355 bool delay_retry = false;
1356
1357 /* device or driver problems */
1358 switch (errors) {
1359 case SCSI_DH_OK:
1360 break;
1361 case SCSI_DH_NOSYS:
1362 if (!m->hw_handler_name) {
1363 errors = 0;
1364 break;
1365 }
1366 DMERR("Could not failover the device: Handler scsi_dh_%s "
1367 "Error %d.", m->hw_handler_name, errors);
1368 /*
1369 * Fail path for now, so we do not ping pong
1370 */
1371 fail_path(pgpath);
1372 break;
1373 case SCSI_DH_DEV_TEMP_BUSY:
1374 /*
1375 * Probably doing something like FW upgrade on the
1376 * controller so try the other pg.
1377 */
1378 bypass_pg(m, pg, true);
1379 break;
1380 case SCSI_DH_RETRY:
1381 /* Wait before retrying. */
1382 delay_retry = 1;
1383 case SCSI_DH_IMM_RETRY:
1384 case SCSI_DH_RES_TEMP_UNAVAIL:
1385 if (pg_init_limit_reached(m, pgpath))
1386 fail_path(pgpath);
1387 errors = 0;
1388 break;
1389 case SCSI_DH_DEV_OFFLINED:
1390 default:
1391 /*
1392 * We probably do not want to fail the path for a device
1393 * error, but this is what the old dm did. In future
1394 * patches we can do more advanced handling.
1395 */
1396 fail_path(pgpath);
1397 }
1398
1399 spin_lock_irqsave(&m->lock, flags);
1400 if (errors) {
1401 if (pgpath == m->current_pgpath) {
1402 DMERR("Could not failover device. Error %d.", errors);
1403 m->current_pgpath = NULL;
1404 m->current_pg = NULL;
1405 }
1406 } else if (!test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1407 pg->bypassed = false;
1408
1409 if (atomic_dec_return(&m->pg_init_in_progress) > 0)
1410 /* Activations of other paths are still on going */
1411 goto out;
1412
1413 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags)) {
1414 if (delay_retry)
1415 set_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1416 else
1417 clear_bit(MPATHF_PG_INIT_DELAY_RETRY, &m->flags);
1418
1419 if (__pg_init_all_paths(m))
1420 goto out;
1421 }
1422 clear_bit(MPATHF_QUEUE_IO, &m->flags);
1423
1424 process_queued_io_list(m);
1425
1426 /*
1427 * Wake up any thread waiting to suspend.
1428 */
1429 wake_up(&m->pg_init_wait);
1430
1431 out:
1432 spin_unlock_irqrestore(&m->lock, flags);
1433 }
1434
1435 static void activate_or_offline_path(struct pgpath *pgpath)
1436 {
1437 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1438
1439 if (pgpath->is_active && !blk_queue_dying(q))
1440 scsi_dh_activate(q, pg_init_done, pgpath);
1441 else
1442 pg_init_done(pgpath, SCSI_DH_DEV_OFFLINED);
1443 }
1444
1445 static void activate_path_work(struct work_struct *work)
1446 {
1447 struct pgpath *pgpath =
1448 container_of(work, struct pgpath, activate_path.work);
1449
1450 activate_or_offline_path(pgpath);
1451 }
1452
1453 static int noretry_error(blk_status_t error)
1454 {
1455 switch (error) {
1456 case BLK_STS_NOTSUPP:
1457 case BLK_STS_NOSPC:
1458 case BLK_STS_TARGET:
1459 case BLK_STS_NEXUS:
1460 case BLK_STS_MEDIUM:
1461 case BLK_STS_RESOURCE:
1462 return 1;
1463 }
1464
1465 /* Anything else could be a path failure, so should be retried */
1466 return 0;
1467 }
1468
1469 static int multipath_end_io(struct dm_target *ti, struct request *clone,
1470 blk_status_t error, union map_info *map_context)
1471 {
1472 struct dm_mpath_io *mpio = get_mpio(map_context);
1473 struct pgpath *pgpath = mpio->pgpath;
1474 int r = DM_ENDIO_DONE;
1475
1476 /*
1477 * We don't queue any clone request inside the multipath target
1478 * during end I/O handling, since those clone requests don't have
1479 * bio clones. If we queue them inside the multipath target,
1480 * we need to make bio clones, that requires memory allocation.
1481 * (See drivers/md/dm-rq.c:end_clone_bio() about why the clone requests
1482 * don't have bio clones.)
1483 * Instead of queueing the clone request here, we queue the original
1484 * request into dm core, which will remake a clone request and
1485 * clone bios for it and resubmit it later.
1486 */
1487 if (error && !noretry_error(error)) {
1488 struct multipath *m = ti->private;
1489
1490 r = DM_ENDIO_REQUEUE;
1491
1492 if (pgpath)
1493 fail_path(pgpath);
1494
1495 if (atomic_read(&m->nr_valid_paths) == 0 &&
1496 !test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
1497 if (error == BLK_STS_IOERR)
1498 dm_report_EIO(m);
1499 /* complete with the original error */
1500 r = DM_ENDIO_DONE;
1501 }
1502 }
1503
1504 if (pgpath) {
1505 struct path_selector *ps = &pgpath->pg->ps;
1506
1507 if (ps->type->end_io)
1508 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1509 }
1510
1511 return r;
1512 }
1513
1514 static int multipath_end_io_bio(struct dm_target *ti, struct bio *clone,
1515 blk_status_t *error)
1516 {
1517 struct multipath *m = ti->private;
1518 struct dm_mpath_io *mpio = get_mpio_from_bio(clone);
1519 struct pgpath *pgpath = mpio->pgpath;
1520 unsigned long flags;
1521 int r = DM_ENDIO_DONE;
1522
1523 if (!*error || noretry_error(*error))
1524 goto done;
1525
1526 if (pgpath)
1527 fail_path(pgpath);
1528
1529 if (atomic_read(&m->nr_valid_paths) == 0 &&
1530 !test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags)) {
1531 dm_report_EIO(m);
1532 *error = BLK_STS_IOERR;
1533 goto done;
1534 }
1535
1536 /* Queue for the daemon to resubmit */
1537 dm_bio_restore(get_bio_details_from_bio(clone), clone);
1538
1539 spin_lock_irqsave(&m->lock, flags);
1540 bio_list_add(&m->queued_bios, clone);
1541 spin_unlock_irqrestore(&m->lock, flags);
1542 if (!test_bit(MPATHF_QUEUE_IO, &m->flags))
1543 queue_work(kmultipathd, &m->process_queued_bios);
1544
1545 r = DM_ENDIO_INCOMPLETE;
1546 done:
1547 if (pgpath) {
1548 struct path_selector *ps = &pgpath->pg->ps;
1549
1550 if (ps->type->end_io)
1551 ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes);
1552 }
1553
1554 return r;
1555 }
1556
1557 /*
1558 * Suspend can't complete until all the I/O is processed so if
1559 * the last path fails we must error any remaining I/O.
1560 * Note that if the freeze_bdev fails while suspending, the
1561 * queue_if_no_path state is lost - userspace should reset it.
1562 */
1563 static void multipath_presuspend(struct dm_target *ti)
1564 {
1565 struct multipath *m = ti->private;
1566
1567 queue_if_no_path(m, false, true);
1568 }
1569
1570 static void multipath_postsuspend(struct dm_target *ti)
1571 {
1572 struct multipath *m = ti->private;
1573
1574 mutex_lock(&m->work_mutex);
1575 flush_multipath_work(m);
1576 mutex_unlock(&m->work_mutex);
1577 }
1578
1579 /*
1580 * Restore the queue_if_no_path setting.
1581 */
1582 static void multipath_resume(struct dm_target *ti)
1583 {
1584 struct multipath *m = ti->private;
1585 unsigned long flags;
1586
1587 spin_lock_irqsave(&m->lock, flags);
1588 assign_bit(test_bit(MPATHF_SAVED_QUEUE_IF_NO_PATH, &m->flags),
1589 MPATHF_QUEUE_IF_NO_PATH, &m->flags);
1590 spin_unlock_irqrestore(&m->lock, flags);
1591 }
1592
1593 /*
1594 * Info output has the following format:
1595 * num_multipath_feature_args [multipath_feature_args]*
1596 * num_handler_status_args [handler_status_args]*
1597 * num_groups init_group_number
1598 * [A|D|E num_ps_status_args [ps_status_args]*
1599 * num_paths num_selector_args
1600 * [path_dev A|F fail_count [selector_args]* ]+ ]+
1601 *
1602 * Table output has the following format (identical to the constructor string):
1603 * num_feature_args [features_args]*
1604 * num_handler_args hw_handler [hw_handler_args]*
1605 * num_groups init_group_number
1606 * [priority selector-name num_ps_args [ps_args]*
1607 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+
1608 */
1609 static void multipath_status(struct dm_target *ti, status_type_t type,
1610 unsigned status_flags, char *result, unsigned maxlen)
1611 {
1612 int sz = 0;
1613 unsigned long flags;
1614 struct multipath *m = ti->private;
1615 struct priority_group *pg;
1616 struct pgpath *p;
1617 unsigned pg_num;
1618 char state;
1619
1620 spin_lock_irqsave(&m->lock, flags);
1621
1622 /* Features */
1623 if (type == STATUSTYPE_INFO)
1624 DMEMIT("2 %u %u ", test_bit(MPATHF_QUEUE_IO, &m->flags),
1625 atomic_read(&m->pg_init_count));
1626 else {
1627 DMEMIT("%u ", test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags) +
1628 (m->pg_init_retries > 0) * 2 +
1629 (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2 +
1630 test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags) +
1631 (m->queue_mode != DM_TYPE_REQUEST_BASED) * 2);
1632
1633 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1634 DMEMIT("queue_if_no_path ");
1635 if (m->pg_init_retries)
1636 DMEMIT("pg_init_retries %u ", m->pg_init_retries);
1637 if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT)
1638 DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs);
1639 if (test_bit(MPATHF_RETAIN_ATTACHED_HW_HANDLER, &m->flags))
1640 DMEMIT("retain_attached_hw_handler ");
1641 if (m->queue_mode != DM_TYPE_REQUEST_BASED) {
1642 switch(m->queue_mode) {
1643 case DM_TYPE_BIO_BASED:
1644 DMEMIT("queue_mode bio ");
1645 break;
1646 case DM_TYPE_MQ_REQUEST_BASED:
1647 DMEMIT("queue_mode mq ");
1648 break;
1649 default:
1650 WARN_ON_ONCE(true);
1651 break;
1652 }
1653 }
1654 }
1655
1656 if (!m->hw_handler_name || type == STATUSTYPE_INFO)
1657 DMEMIT("0 ");
1658 else
1659 DMEMIT("1 %s ", m->hw_handler_name);
1660
1661 DMEMIT("%u ", m->nr_priority_groups);
1662
1663 if (m->next_pg)
1664 pg_num = m->next_pg->pg_num;
1665 else if (m->current_pg)
1666 pg_num = m->current_pg->pg_num;
1667 else
1668 pg_num = (m->nr_priority_groups ? 1 : 0);
1669
1670 DMEMIT("%u ", pg_num);
1671
1672 switch (type) {
1673 case STATUSTYPE_INFO:
1674 list_for_each_entry(pg, &m->priority_groups, list) {
1675 if (pg->bypassed)
1676 state = 'D'; /* Disabled */
1677 else if (pg == m->current_pg)
1678 state = 'A'; /* Currently Active */
1679 else
1680 state = 'E'; /* Enabled */
1681
1682 DMEMIT("%c ", state);
1683
1684 if (pg->ps.type->status)
1685 sz += pg->ps.type->status(&pg->ps, NULL, type,
1686 result + sz,
1687 maxlen - sz);
1688 else
1689 DMEMIT("0 ");
1690
1691 DMEMIT("%u %u ", pg->nr_pgpaths,
1692 pg->ps.type->info_args);
1693
1694 list_for_each_entry(p, &pg->pgpaths, list) {
1695 DMEMIT("%s %s %u ", p->path.dev->name,
1696 p->is_active ? "A" : "F",
1697 p->fail_count);
1698 if (pg->ps.type->status)
1699 sz += pg->ps.type->status(&pg->ps,
1700 &p->path, type, result + sz,
1701 maxlen - sz);
1702 }
1703 }
1704 break;
1705
1706 case STATUSTYPE_TABLE:
1707 list_for_each_entry(pg, &m->priority_groups, list) {
1708 DMEMIT("%s ", pg->ps.type->name);
1709
1710 if (pg->ps.type->status)
1711 sz += pg->ps.type->status(&pg->ps, NULL, type,
1712 result + sz,
1713 maxlen - sz);
1714 else
1715 DMEMIT("0 ");
1716
1717 DMEMIT("%u %u ", pg->nr_pgpaths,
1718 pg->ps.type->table_args);
1719
1720 list_for_each_entry(p, &pg->pgpaths, list) {
1721 DMEMIT("%s ", p->path.dev->name);
1722 if (pg->ps.type->status)
1723 sz += pg->ps.type->status(&pg->ps,
1724 &p->path, type, result + sz,
1725 maxlen - sz);
1726 }
1727 }
1728 break;
1729 }
1730
1731 spin_unlock_irqrestore(&m->lock, flags);
1732 }
1733
1734 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv)
1735 {
1736 int r = -EINVAL;
1737 struct dm_dev *dev;
1738 struct multipath *m = ti->private;
1739 action_fn action;
1740
1741 mutex_lock(&m->work_mutex);
1742
1743 if (dm_suspended(ti)) {
1744 r = -EBUSY;
1745 goto out;
1746 }
1747
1748 if (argc == 1) {
1749 if (!strcasecmp(argv[0], "queue_if_no_path")) {
1750 r = queue_if_no_path(m, true, false);
1751 goto out;
1752 } else if (!strcasecmp(argv[0], "fail_if_no_path")) {
1753 r = queue_if_no_path(m, false, false);
1754 goto out;
1755 }
1756 }
1757
1758 if (argc != 2) {
1759 DMWARN("Invalid multipath message arguments. Expected 2 arguments, got %d.", argc);
1760 goto out;
1761 }
1762
1763 if (!strcasecmp(argv[0], "disable_group")) {
1764 r = bypass_pg_num(m, argv[1], true);
1765 goto out;
1766 } else if (!strcasecmp(argv[0], "enable_group")) {
1767 r = bypass_pg_num(m, argv[1], false);
1768 goto out;
1769 } else if (!strcasecmp(argv[0], "switch_group")) {
1770 r = switch_pg_num(m, argv[1]);
1771 goto out;
1772 } else if (!strcasecmp(argv[0], "reinstate_path"))
1773 action = reinstate_path;
1774 else if (!strcasecmp(argv[0], "fail_path"))
1775 action = fail_path;
1776 else {
1777 DMWARN("Unrecognised multipath message received: %s", argv[0]);
1778 goto out;
1779 }
1780
1781 r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev);
1782 if (r) {
1783 DMWARN("message: error getting device %s",
1784 argv[1]);
1785 goto out;
1786 }
1787
1788 r = action_dev(m, dev, action);
1789
1790 dm_put_device(ti, dev);
1791
1792 out:
1793 mutex_unlock(&m->work_mutex);
1794 return r;
1795 }
1796
1797 static int multipath_prepare_ioctl(struct dm_target *ti,
1798 struct block_device **bdev, fmode_t *mode)
1799 {
1800 struct multipath *m = ti->private;
1801 struct pgpath *current_pgpath;
1802 int r;
1803
1804 current_pgpath = lockless_dereference(m->current_pgpath);
1805 if (!current_pgpath)
1806 current_pgpath = choose_pgpath(m, 0);
1807
1808 if (current_pgpath) {
1809 if (!test_bit(MPATHF_QUEUE_IO, &m->flags)) {
1810 *bdev = current_pgpath->path.dev->bdev;
1811 *mode = current_pgpath->path.dev->mode;
1812 r = 0;
1813 } else {
1814 /* pg_init has not started or completed */
1815 r = -ENOTCONN;
1816 }
1817 } else {
1818 /* No path is available */
1819 if (test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1820 r = -ENOTCONN;
1821 else
1822 r = -EIO;
1823 }
1824
1825 if (r == -ENOTCONN) {
1826 if (!lockless_dereference(m->current_pg)) {
1827 /* Path status changed, redo selection */
1828 (void) choose_pgpath(m, 0);
1829 }
1830 if (test_bit(MPATHF_PG_INIT_REQUIRED, &m->flags))
1831 pg_init_all_paths(m);
1832 dm_table_run_md_queue_async(m->ti->table);
1833 process_queued_io_list(m);
1834 }
1835
1836 /*
1837 * Only pass ioctls through if the device sizes match exactly.
1838 */
1839 if (!r && ti->len != i_size_read((*bdev)->bd_inode) >> SECTOR_SHIFT)
1840 return 1;
1841 return r;
1842 }
1843
1844 static int multipath_iterate_devices(struct dm_target *ti,
1845 iterate_devices_callout_fn fn, void *data)
1846 {
1847 struct multipath *m = ti->private;
1848 struct priority_group *pg;
1849 struct pgpath *p;
1850 int ret = 0;
1851
1852 list_for_each_entry(pg, &m->priority_groups, list) {
1853 list_for_each_entry(p, &pg->pgpaths, list) {
1854 ret = fn(ti, p->path.dev, ti->begin, ti->len, data);
1855 if (ret)
1856 goto out;
1857 }
1858 }
1859
1860 out:
1861 return ret;
1862 }
1863
1864 static int pgpath_busy(struct pgpath *pgpath)
1865 {
1866 struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev);
1867
1868 return blk_lld_busy(q);
1869 }
1870
1871 /*
1872 * We return "busy", only when we can map I/Os but underlying devices
1873 * are busy (so even if we map I/Os now, the I/Os will wait on
1874 * the underlying queue).
1875 * In other words, if we want to kill I/Os or queue them inside us
1876 * due to map unavailability, we don't return "busy". Otherwise,
1877 * dm core won't give us the I/Os and we can't do what we want.
1878 */
1879 static int multipath_busy(struct dm_target *ti)
1880 {
1881 bool busy = false, has_active = false;
1882 struct multipath *m = ti->private;
1883 struct priority_group *pg, *next_pg;
1884 struct pgpath *pgpath;
1885
1886 /* pg_init in progress */
1887 if (atomic_read(&m->pg_init_in_progress))
1888 return true;
1889
1890 /* no paths available, for blk-mq: rely on IO mapping to delay requeue */
1891 if (!atomic_read(&m->nr_valid_paths) && test_bit(MPATHF_QUEUE_IF_NO_PATH, &m->flags))
1892 return (m->queue_mode != DM_TYPE_MQ_REQUEST_BASED);
1893
1894 /* Guess which priority_group will be used at next mapping time */
1895 pg = lockless_dereference(m->current_pg);
1896 next_pg = lockless_dereference(m->next_pg);
1897 if (unlikely(!lockless_dereference(m->current_pgpath) && next_pg))
1898 pg = next_pg;
1899
1900 if (!pg) {
1901 /*
1902 * We don't know which pg will be used at next mapping time.
1903 * We don't call choose_pgpath() here to avoid to trigger
1904 * pg_init just by busy checking.
1905 * So we don't know whether underlying devices we will be using
1906 * at next mapping time are busy or not. Just try mapping.
1907 */
1908 return busy;
1909 }
1910
1911 /*
1912 * If there is one non-busy active path at least, the path selector
1913 * will be able to select it. So we consider such a pg as not busy.
1914 */
1915 busy = true;
1916 list_for_each_entry(pgpath, &pg->pgpaths, list) {
1917 if (pgpath->is_active) {
1918 has_active = true;
1919 if (!pgpath_busy(pgpath)) {
1920 busy = false;
1921 break;
1922 }
1923 }
1924 }
1925
1926 if (!has_active) {
1927 /*
1928 * No active path in this pg, so this pg won't be used and
1929 * the current_pg will be changed at next mapping time.
1930 * We need to try mapping to determine it.
1931 */
1932 busy = false;
1933 }
1934
1935 return busy;
1936 }
1937
1938 /*-----------------------------------------------------------------
1939 * Module setup
1940 *---------------------------------------------------------------*/
1941 static struct target_type multipath_target = {
1942 .name = "multipath",
1943 .version = {1, 12, 0},
1944 .features = DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
1945 .module = THIS_MODULE,
1946 .ctr = multipath_ctr,
1947 .dtr = multipath_dtr,
1948 .clone_and_map_rq = multipath_clone_and_map,
1949 .release_clone_rq = multipath_release_clone,
1950 .rq_end_io = multipath_end_io,
1951 .map = multipath_map_bio,
1952 .end_io = multipath_end_io_bio,
1953 .presuspend = multipath_presuspend,
1954 .postsuspend = multipath_postsuspend,
1955 .resume = multipath_resume,
1956 .status = multipath_status,
1957 .message = multipath_message,
1958 .prepare_ioctl = multipath_prepare_ioctl,
1959 .iterate_devices = multipath_iterate_devices,
1960 .busy = multipath_busy,
1961 };
1962
1963 static int __init dm_multipath_init(void)
1964 {
1965 int r;
1966
1967 r = dm_register_target(&multipath_target);
1968 if (r < 0) {
1969 DMERR("request-based register failed %d", r);
1970 r = -EINVAL;
1971 goto bad_register_target;
1972 }
1973
1974 kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0);
1975 if (!kmultipathd) {
1976 DMERR("failed to create workqueue kmpathd");
1977 r = -ENOMEM;
1978 goto bad_alloc_kmultipathd;
1979 }
1980
1981 /*
1982 * A separate workqueue is used to handle the device handlers
1983 * to avoid overloading existing workqueue. Overloading the
1984 * old workqueue would also create a bottleneck in the
1985 * path of the storage hardware device activation.
1986 */
1987 kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd",
1988 WQ_MEM_RECLAIM);
1989 if (!kmpath_handlerd) {
1990 DMERR("failed to create workqueue kmpath_handlerd");
1991 r = -ENOMEM;
1992 goto bad_alloc_kmpath_handlerd;
1993 }
1994
1995 return 0;
1996
1997 bad_alloc_kmpath_handlerd:
1998 destroy_workqueue(kmultipathd);
1999 bad_alloc_kmultipathd:
2000 dm_unregister_target(&multipath_target);
2001 bad_register_target:
2002 return r;
2003 }
2004
2005 static void __exit dm_multipath_exit(void)
2006 {
2007 destroy_workqueue(kmpath_handlerd);
2008 destroy_workqueue(kmultipathd);
2009
2010 dm_unregister_target(&multipath_target);
2011 }
2012
2013 module_init(dm_multipath_init);
2014 module_exit(dm_multipath_exit);
2015
2016 MODULE_DESCRIPTION(DM_NAME " multipath target");
2017 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");
2018 MODULE_LICENSE("GPL");
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