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