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