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 "dm.h" 9 #include "dm-path-selector.h" 10 #include "dm-hw-handler.h" 11 #include "dm-bio-list.h" 12 #include "dm-bio-record.h" 13 14 #include <linux/ctype.h> 15 #include <linux/init.h> 16 #include <linux/mempool.h> 17 #include <linux/module.h> 18 #include <linux/pagemap.h> 19 #include <linux/slab.h> 20 #include <linux/time.h> 21 #include <linux/workqueue.h> 22 #include <asm/atomic.h> 23 24 #define DM_MSG_PREFIX "multipath" 25 #define MESG_STR(x) x, sizeof(x) 26 27 /* Path properties */ 28 struct pgpath { 29 struct list_head list; 30 31 struct priority_group *pg; /* Owning PG */ 32 unsigned fail_count; /* Cumulative failure count */ 33 34 struct path path; 35 }; 36 37 #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path) 38 39 /* 40 * Paths are grouped into Priority Groups and numbered from 1 upwards. 41 * Each has a path selector which controls which path gets used. 42 */ 43 struct priority_group { 44 struct list_head list; 45 46 struct multipath *m; /* Owning multipath instance */ 47 struct path_selector ps; 48 49 unsigned pg_num; /* Reference number */ 50 unsigned bypassed; /* Temporarily bypass this PG? */ 51 52 unsigned nr_pgpaths; /* Number of paths in PG */ 53 struct list_head pgpaths; 54 }; 55 56 /* Multipath context */ 57 struct multipath { 58 struct list_head list; 59 struct dm_target *ti; 60 61 spinlock_t lock; 62 63 struct hw_handler hw_handler; 64 unsigned nr_priority_groups; 65 struct list_head priority_groups; 66 unsigned pg_init_required; /* pg_init needs calling? */ 67 unsigned pg_init_in_progress; /* Only one pg_init allowed at once */ 68 69 unsigned nr_valid_paths; /* Total number of usable paths */ 70 struct pgpath *current_pgpath; 71 struct priority_group *current_pg; 72 struct priority_group *next_pg; /* Switch to this PG if set */ 73 unsigned repeat_count; /* I/Os left before calling PS again */ 74 75 unsigned queue_io; /* Must we queue all I/O? */ 76 unsigned queue_if_no_path; /* Queue I/O if last path fails? */ 77 unsigned saved_queue_if_no_path;/* Saved state during suspension */ 78 79 struct work_struct process_queued_ios; 80 struct bio_list queued_ios; 81 unsigned queue_size; 82 83 struct work_struct trigger_event; 84 85 /* 86 * We must use a mempool of mpath_io structs so that we 87 * can resubmit bios on error. 88 */ 89 mempool_t *mpio_pool; 90 }; 91 92 /* 93 * Context information attached to each bio we process. 94 */ 95 struct mpath_io { 96 struct pgpath *pgpath; 97 struct dm_bio_details details; 98 }; 99 100 typedef int (*action_fn) (struct pgpath *pgpath); 101 102 #define MIN_IOS 256 /* Mempool size */ 103 104 static kmem_cache_t *_mpio_cache; 105 106 struct workqueue_struct *kmultipathd; 107 static void process_queued_ios(void *data); 108 static void trigger_event(void *data); 109 110 111 /*----------------------------------------------- 112 * Allocation routines 113 *-----------------------------------------------*/ 114 115 static struct pgpath *alloc_pgpath(void) 116 { 117 struct pgpath *pgpath = kmalloc(sizeof(*pgpath), GFP_KERNEL); 118 119 if (pgpath) { 120 memset(pgpath, 0, sizeof(*pgpath)); 121 pgpath->path.is_active = 1; 122 } 123 124 return pgpath; 125 } 126 127 static inline void free_pgpath(struct pgpath *pgpath) 128 { 129 kfree(pgpath); 130 } 131 132 static struct priority_group *alloc_priority_group(void) 133 { 134 struct priority_group *pg; 135 136 pg = kmalloc(sizeof(*pg), GFP_KERNEL); 137 if (!pg) 138 return NULL; 139 140 memset(pg, 0, sizeof(*pg)); 141 INIT_LIST_HEAD(&pg->pgpaths); 142 143 return pg; 144 } 145 146 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti) 147 { 148 struct pgpath *pgpath, *tmp; 149 150 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) { 151 list_del(&pgpath->list); 152 dm_put_device(ti, pgpath->path.dev); 153 free_pgpath(pgpath); 154 } 155 } 156 157 static void free_priority_group(struct priority_group *pg, 158 struct dm_target *ti) 159 { 160 struct path_selector *ps = &pg->ps; 161 162 if (ps->type) { 163 ps->type->destroy(ps); 164 dm_put_path_selector(ps->type); 165 } 166 167 free_pgpaths(&pg->pgpaths, ti); 168 kfree(pg); 169 } 170 171 static struct multipath *alloc_multipath(void) 172 { 173 struct multipath *m; 174 175 m = kmalloc(sizeof(*m), GFP_KERNEL); 176 if (m) { 177 memset(m, 0, sizeof(*m)); 178 INIT_LIST_HEAD(&m->priority_groups); 179 spin_lock_init(&m->lock); 180 m->queue_io = 1; 181 INIT_WORK(&m->process_queued_ios, process_queued_ios, m); 182 INIT_WORK(&m->trigger_event, trigger_event, m); 183 m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache); 184 if (!m->mpio_pool) { 185 kfree(m); 186 return NULL; 187 } 188 } 189 190 return m; 191 } 192 193 static void free_multipath(struct multipath *m) 194 { 195 struct priority_group *pg, *tmp; 196 struct hw_handler *hwh = &m->hw_handler; 197 198 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) { 199 list_del(&pg->list); 200 free_priority_group(pg, m->ti); 201 } 202 203 if (hwh->type) { 204 hwh->type->destroy(hwh); 205 dm_put_hw_handler(hwh->type); 206 } 207 208 mempool_destroy(m->mpio_pool); 209 kfree(m); 210 } 211 212 213 /*----------------------------------------------- 214 * Path selection 215 *-----------------------------------------------*/ 216 217 static void __switch_pg(struct multipath *m, struct pgpath *pgpath) 218 { 219 struct hw_handler *hwh = &m->hw_handler; 220 221 m->current_pg = pgpath->pg; 222 223 /* Must we initialise the PG first, and queue I/O till it's ready? */ 224 if (hwh->type && hwh->type->pg_init) { 225 m->pg_init_required = 1; 226 m->queue_io = 1; 227 } else { 228 m->pg_init_required = 0; 229 m->queue_io = 0; 230 } 231 } 232 233 static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg) 234 { 235 struct path *path; 236 237 path = pg->ps.type->select_path(&pg->ps, &m->repeat_count); 238 if (!path) 239 return -ENXIO; 240 241 m->current_pgpath = path_to_pgpath(path); 242 243 if (m->current_pg != pg) 244 __switch_pg(m, m->current_pgpath); 245 246 return 0; 247 } 248 249 static void __choose_pgpath(struct multipath *m) 250 { 251 struct priority_group *pg; 252 unsigned bypassed = 1; 253 254 if (!m->nr_valid_paths) 255 goto failed; 256 257 /* Were we instructed to switch PG? */ 258 if (m->next_pg) { 259 pg = m->next_pg; 260 m->next_pg = NULL; 261 if (!__choose_path_in_pg(m, pg)) 262 return; 263 } 264 265 /* Don't change PG until it has no remaining paths */ 266 if (m->current_pg && !__choose_path_in_pg(m, m->current_pg)) 267 return; 268 269 /* 270 * Loop through priority groups until we find a valid path. 271 * First time we skip PGs marked 'bypassed'. 272 * Second time we only try the ones we skipped. 273 */ 274 do { 275 list_for_each_entry(pg, &m->priority_groups, list) { 276 if (pg->bypassed == bypassed) 277 continue; 278 if (!__choose_path_in_pg(m, pg)) 279 return; 280 } 281 } while (bypassed--); 282 283 failed: 284 m->current_pgpath = NULL; 285 m->current_pg = NULL; 286 } 287 288 static int map_io(struct multipath *m, struct bio *bio, struct mpath_io *mpio, 289 unsigned was_queued) 290 { 291 int r = 1; 292 unsigned long flags; 293 struct pgpath *pgpath; 294 295 spin_lock_irqsave(&m->lock, flags); 296 297 /* Do we need to select a new pgpath? */ 298 if (!m->current_pgpath || 299 (!m->queue_io && (m->repeat_count && --m->repeat_count == 0))) 300 __choose_pgpath(m); 301 302 pgpath = m->current_pgpath; 303 304 if (was_queued) 305 m->queue_size--; 306 307 if ((pgpath && m->queue_io) || 308 (!pgpath && m->queue_if_no_path)) { 309 /* Queue for the daemon to resubmit */ 310 bio_list_add(&m->queued_ios, bio); 311 m->queue_size++; 312 if ((m->pg_init_required && !m->pg_init_in_progress) || 313 !m->queue_io) 314 queue_work(kmultipathd, &m->process_queued_ios); 315 pgpath = NULL; 316 r = 0; 317 } else if (!pgpath) 318 r = -EIO; /* Failed */ 319 else 320 bio->bi_bdev = pgpath->path.dev->bdev; 321 322 mpio->pgpath = pgpath; 323 324 spin_unlock_irqrestore(&m->lock, flags); 325 326 return r; 327 } 328 329 /* 330 * If we run out of usable paths, should we queue I/O or error it? 331 */ 332 static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path, 333 unsigned save_old_value) 334 { 335 unsigned long flags; 336 337 spin_lock_irqsave(&m->lock, flags); 338 339 if (save_old_value) 340 m->saved_queue_if_no_path = m->queue_if_no_path; 341 else 342 m->saved_queue_if_no_path = queue_if_no_path; 343 m->queue_if_no_path = queue_if_no_path; 344 if (!m->queue_if_no_path && m->queue_size) 345 queue_work(kmultipathd, &m->process_queued_ios); 346 347 spin_unlock_irqrestore(&m->lock, flags); 348 349 return 0; 350 } 351 352 /*----------------------------------------------------------------- 353 * The multipath daemon is responsible for resubmitting queued ios. 354 *---------------------------------------------------------------*/ 355 356 static void dispatch_queued_ios(struct multipath *m) 357 { 358 int r; 359 unsigned long flags; 360 struct bio *bio = NULL, *next; 361 struct mpath_io *mpio; 362 union map_info *info; 363 364 spin_lock_irqsave(&m->lock, flags); 365 bio = bio_list_get(&m->queued_ios); 366 spin_unlock_irqrestore(&m->lock, flags); 367 368 while (bio) { 369 next = bio->bi_next; 370 bio->bi_next = NULL; 371 372 info = dm_get_mapinfo(bio); 373 mpio = info->ptr; 374 375 r = map_io(m, bio, mpio, 1); 376 if (r < 0) 377 bio_endio(bio, bio->bi_size, r); 378 else if (r == 1) 379 generic_make_request(bio); 380 381 bio = next; 382 } 383 } 384 385 static void process_queued_ios(void *data) 386 { 387 struct multipath *m = (struct multipath *) data; 388 struct hw_handler *hwh = &m->hw_handler; 389 struct pgpath *pgpath = NULL; 390 unsigned init_required = 0, must_queue = 1; 391 unsigned long flags; 392 393 spin_lock_irqsave(&m->lock, flags); 394 395 if (!m->queue_size) 396 goto out; 397 398 if (!m->current_pgpath) 399 __choose_pgpath(m); 400 401 pgpath = m->current_pgpath; 402 403 if ((pgpath && !m->queue_io) || 404 (!pgpath && !m->queue_if_no_path)) 405 must_queue = 0; 406 407 if (m->pg_init_required && !m->pg_init_in_progress) { 408 m->pg_init_required = 0; 409 m->pg_init_in_progress = 1; 410 init_required = 1; 411 } 412 413 out: 414 spin_unlock_irqrestore(&m->lock, flags); 415 416 if (init_required) 417 hwh->type->pg_init(hwh, pgpath->pg->bypassed, &pgpath->path); 418 419 if (!must_queue) 420 dispatch_queued_ios(m); 421 } 422 423 /* 424 * An event is triggered whenever a path is taken out of use. 425 * Includes path failure and PG bypass. 426 */ 427 static void trigger_event(void *data) 428 { 429 struct multipath *m = (struct multipath *) data; 430 431 dm_table_event(m->ti->table); 432 } 433 434 /*----------------------------------------------------------------- 435 * Constructor/argument parsing: 436 * <#multipath feature args> [<arg>]* 437 * <#hw_handler args> [hw_handler [<arg>]*] 438 * <#priority groups> 439 * <initial priority group> 440 * [<selector> <#selector args> [<arg>]* 441 * <#paths> <#per-path selector args> 442 * [<path> [<arg>]* ]+ ]+ 443 *---------------------------------------------------------------*/ 444 struct param { 445 unsigned min; 446 unsigned max; 447 char *error; 448 }; 449 450 static int read_param(struct param *param, char *str, unsigned *v, char **error) 451 { 452 if (!str || 453 (sscanf(str, "%u", v) != 1) || 454 (*v < param->min) || 455 (*v > param->max)) { 456 *error = param->error; 457 return -EINVAL; 458 } 459 460 return 0; 461 } 462 463 struct arg_set { 464 unsigned argc; 465 char **argv; 466 }; 467 468 static char *shift(struct arg_set *as) 469 { 470 char *r; 471 472 if (as->argc) { 473 as->argc--; 474 r = *as->argv; 475 as->argv++; 476 return r; 477 } 478 479 return NULL; 480 } 481 482 static void consume(struct arg_set *as, unsigned n) 483 { 484 BUG_ON (as->argc < n); 485 as->argc -= n; 486 as->argv += n; 487 } 488 489 static int parse_path_selector(struct arg_set *as, struct priority_group *pg, 490 struct dm_target *ti) 491 { 492 int r; 493 struct path_selector_type *pst; 494 unsigned ps_argc; 495 496 static struct param _params[] = { 497 {0, 1024, "invalid number of path selector args"}, 498 }; 499 500 pst = dm_get_path_selector(shift(as)); 501 if (!pst) { 502 ti->error = "unknown path selector type"; 503 return -EINVAL; 504 } 505 506 r = read_param(_params, shift(as), &ps_argc, &ti->error); 507 if (r) 508 return -EINVAL; 509 510 r = pst->create(&pg->ps, ps_argc, as->argv); 511 if (r) { 512 dm_put_path_selector(pst); 513 ti->error = "path selector constructor failed"; 514 return r; 515 } 516 517 pg->ps.type = pst; 518 consume(as, ps_argc); 519 520 return 0; 521 } 522 523 static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps, 524 struct dm_target *ti) 525 { 526 int r; 527 struct pgpath *p; 528 529 /* we need at least a path arg */ 530 if (as->argc < 1) { 531 ti->error = "no device given"; 532 return NULL; 533 } 534 535 p = alloc_pgpath(); 536 if (!p) 537 return NULL; 538 539 r = dm_get_device(ti, shift(as), ti->begin, ti->len, 540 dm_table_get_mode(ti->table), &p->path.dev); 541 if (r) { 542 ti->error = "error getting device"; 543 goto bad; 544 } 545 546 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error); 547 if (r) { 548 dm_put_device(ti, p->path.dev); 549 goto bad; 550 } 551 552 return p; 553 554 bad: 555 free_pgpath(p); 556 return NULL; 557 } 558 559 static struct priority_group *parse_priority_group(struct arg_set *as, 560 struct multipath *m, 561 struct dm_target *ti) 562 { 563 static struct param _params[] = { 564 {1, 1024, "invalid number of paths"}, 565 {0, 1024, "invalid number of selector args"} 566 }; 567 568 int r; 569 unsigned i, nr_selector_args, nr_params; 570 struct priority_group *pg; 571 572 if (as->argc < 2) { 573 as->argc = 0; 574 ti->error = "not enough priority group aruments"; 575 return NULL; 576 } 577 578 pg = alloc_priority_group(); 579 if (!pg) { 580 ti->error = "couldn't allocate priority group"; 581 return NULL; 582 } 583 pg->m = m; 584 585 r = parse_path_selector(as, pg, ti); 586 if (r) 587 goto bad; 588 589 /* 590 * read the paths 591 */ 592 r = read_param(_params, shift(as), &pg->nr_pgpaths, &ti->error); 593 if (r) 594 goto bad; 595 596 r = read_param(_params + 1, shift(as), &nr_selector_args, &ti->error); 597 if (r) 598 goto bad; 599 600 nr_params = 1 + nr_selector_args; 601 for (i = 0; i < pg->nr_pgpaths; i++) { 602 struct pgpath *pgpath; 603 struct arg_set path_args; 604 605 if (as->argc < nr_params) 606 goto bad; 607 608 path_args.argc = nr_params; 609 path_args.argv = as->argv; 610 611 pgpath = parse_path(&path_args, &pg->ps, ti); 612 if (!pgpath) 613 goto bad; 614 615 pgpath->pg = pg; 616 list_add_tail(&pgpath->list, &pg->pgpaths); 617 consume(as, nr_params); 618 } 619 620 return pg; 621 622 bad: 623 free_priority_group(pg, ti); 624 return NULL; 625 } 626 627 static int parse_hw_handler(struct arg_set *as, struct multipath *m, 628 struct dm_target *ti) 629 { 630 int r; 631 struct hw_handler_type *hwht; 632 unsigned hw_argc; 633 634 static struct param _params[] = { 635 {0, 1024, "invalid number of hardware handler args"}, 636 }; 637 638 r = read_param(_params, shift(as), &hw_argc, &ti->error); 639 if (r) 640 return -EINVAL; 641 642 if (!hw_argc) 643 return 0; 644 645 hwht = dm_get_hw_handler(shift(as)); 646 if (!hwht) { 647 ti->error = "unknown hardware handler type"; 648 return -EINVAL; 649 } 650 651 r = hwht->create(&m->hw_handler, hw_argc - 1, as->argv); 652 if (r) { 653 dm_put_hw_handler(hwht); 654 ti->error = "hardware handler constructor failed"; 655 return r; 656 } 657 658 m->hw_handler.type = hwht; 659 consume(as, hw_argc - 1); 660 661 return 0; 662 } 663 664 static int parse_features(struct arg_set *as, struct multipath *m, 665 struct dm_target *ti) 666 { 667 int r; 668 unsigned argc; 669 670 static struct param _params[] = { 671 {0, 1, "invalid number of feature args"}, 672 }; 673 674 r = read_param(_params, shift(as), &argc, &ti->error); 675 if (r) 676 return -EINVAL; 677 678 if (!argc) 679 return 0; 680 681 if (!strnicmp(shift(as), MESG_STR("queue_if_no_path"))) 682 return queue_if_no_path(m, 1, 0); 683 else { 684 ti->error = "Unrecognised multipath feature request"; 685 return -EINVAL; 686 } 687 } 688 689 static int multipath_ctr(struct dm_target *ti, unsigned int argc, 690 char **argv) 691 { 692 /* target parameters */ 693 static struct param _params[] = { 694 {1, 1024, "invalid number of priority groups"}, 695 {1, 1024, "invalid initial priority group number"}, 696 }; 697 698 int r; 699 struct multipath *m; 700 struct arg_set as; 701 unsigned pg_count = 0; 702 unsigned next_pg_num; 703 704 as.argc = argc; 705 as.argv = argv; 706 707 m = alloc_multipath(); 708 if (!m) { 709 ti->error = "can't allocate multipath"; 710 return -EINVAL; 711 } 712 713 m->ti = ti; 714 715 r = parse_features(&as, m, ti); 716 if (r) 717 goto bad; 718 719 r = parse_hw_handler(&as, m, ti); 720 if (r) 721 goto bad; 722 723 r = read_param(_params, shift(&as), &m->nr_priority_groups, &ti->error); 724 if (r) 725 goto bad; 726 727 r = read_param(_params + 1, shift(&as), &next_pg_num, &ti->error); 728 if (r) 729 goto bad; 730 731 /* parse the priority groups */ 732 while (as.argc) { 733 struct priority_group *pg; 734 735 pg = parse_priority_group(&as, m, ti); 736 if (!pg) { 737 r = -EINVAL; 738 goto bad; 739 } 740 741 m->nr_valid_paths += pg->nr_pgpaths; 742 list_add_tail(&pg->list, &m->priority_groups); 743 pg_count++; 744 pg->pg_num = pg_count; 745 if (!--next_pg_num) 746 m->next_pg = pg; 747 } 748 749 if (pg_count != m->nr_priority_groups) { 750 ti->error = "priority group count mismatch"; 751 r = -EINVAL; 752 goto bad; 753 } 754 755 ti->private = m; 756 757 return 0; 758 759 bad: 760 free_multipath(m); 761 return r; 762 } 763 764 static void multipath_dtr(struct dm_target *ti) 765 { 766 struct multipath *m = (struct multipath *) ti->private; 767 768 flush_workqueue(kmultipathd); 769 free_multipath(m); 770 } 771 772 /* 773 * Map bios, recording original fields for later in case we have to resubmit 774 */ 775 static int multipath_map(struct dm_target *ti, struct bio *bio, 776 union map_info *map_context) 777 { 778 int r; 779 struct mpath_io *mpio; 780 struct multipath *m = (struct multipath *) ti->private; 781 782 if (bio_barrier(bio)) 783 return -EOPNOTSUPP; 784 785 mpio = mempool_alloc(m->mpio_pool, GFP_NOIO); 786 dm_bio_record(&mpio->details, bio); 787 788 map_context->ptr = mpio; 789 bio->bi_rw |= (1 << BIO_RW_FAILFAST); 790 r = map_io(m, bio, mpio, 0); 791 if (r < 0) 792 mempool_free(mpio, m->mpio_pool); 793 794 return r; 795 } 796 797 /* 798 * Take a path out of use. 799 */ 800 static int fail_path(struct pgpath *pgpath) 801 { 802 unsigned long flags; 803 struct multipath *m = pgpath->pg->m; 804 805 spin_lock_irqsave(&m->lock, flags); 806 807 if (!pgpath->path.is_active) 808 goto out; 809 810 DMWARN("Failing path %s.", pgpath->path.dev->name); 811 812 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path); 813 pgpath->path.is_active = 0; 814 pgpath->fail_count++; 815 816 m->nr_valid_paths--; 817 818 if (pgpath == m->current_pgpath) 819 m->current_pgpath = NULL; 820 821 queue_work(kmultipathd, &m->trigger_event); 822 823 out: 824 spin_unlock_irqrestore(&m->lock, flags); 825 826 return 0; 827 } 828 829 /* 830 * Reinstate a previously-failed path 831 */ 832 static int reinstate_path(struct pgpath *pgpath) 833 { 834 int r = 0; 835 unsigned long flags; 836 struct multipath *m = pgpath->pg->m; 837 838 spin_lock_irqsave(&m->lock, flags); 839 840 if (pgpath->path.is_active) 841 goto out; 842 843 if (!pgpath->pg->ps.type) { 844 DMWARN("Reinstate path not supported by path selector %s", 845 pgpath->pg->ps.type->name); 846 r = -EINVAL; 847 goto out; 848 } 849 850 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path); 851 if (r) 852 goto out; 853 854 pgpath->path.is_active = 1; 855 856 m->current_pgpath = NULL; 857 if (!m->nr_valid_paths++ && m->queue_size) 858 queue_work(kmultipathd, &m->process_queued_ios); 859 860 queue_work(kmultipathd, &m->trigger_event); 861 862 out: 863 spin_unlock_irqrestore(&m->lock, flags); 864 865 return r; 866 } 867 868 /* 869 * Fail or reinstate all paths that match the provided struct dm_dev. 870 */ 871 static int action_dev(struct multipath *m, struct dm_dev *dev, 872 action_fn action) 873 { 874 int r = 0; 875 struct pgpath *pgpath; 876 struct priority_group *pg; 877 878 list_for_each_entry(pg, &m->priority_groups, list) { 879 list_for_each_entry(pgpath, &pg->pgpaths, list) { 880 if (pgpath->path.dev == dev) 881 r = action(pgpath); 882 } 883 } 884 885 return r; 886 } 887 888 /* 889 * Temporarily try to avoid having to use the specified PG 890 */ 891 static void bypass_pg(struct multipath *m, struct priority_group *pg, 892 int bypassed) 893 { 894 unsigned long flags; 895 896 spin_lock_irqsave(&m->lock, flags); 897 898 pg->bypassed = bypassed; 899 m->current_pgpath = NULL; 900 m->current_pg = NULL; 901 902 spin_unlock_irqrestore(&m->lock, flags); 903 904 queue_work(kmultipathd, &m->trigger_event); 905 } 906 907 /* 908 * Switch to using the specified PG from the next I/O that gets mapped 909 */ 910 static int switch_pg_num(struct multipath *m, const char *pgstr) 911 { 912 struct priority_group *pg; 913 unsigned pgnum; 914 unsigned long flags; 915 916 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum || 917 (pgnum > m->nr_priority_groups)) { 918 DMWARN("invalid PG number supplied to switch_pg_num"); 919 return -EINVAL; 920 } 921 922 spin_lock_irqsave(&m->lock, flags); 923 list_for_each_entry(pg, &m->priority_groups, list) { 924 pg->bypassed = 0; 925 if (--pgnum) 926 continue; 927 928 m->current_pgpath = NULL; 929 m->current_pg = NULL; 930 m->next_pg = pg; 931 } 932 spin_unlock_irqrestore(&m->lock, flags); 933 934 queue_work(kmultipathd, &m->trigger_event); 935 return 0; 936 } 937 938 /* 939 * Set/clear bypassed status of a PG. 940 * PGs are numbered upwards from 1 in the order they were declared. 941 */ 942 static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed) 943 { 944 struct priority_group *pg; 945 unsigned pgnum; 946 947 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum || 948 (pgnum > m->nr_priority_groups)) { 949 DMWARN("invalid PG number supplied to bypass_pg"); 950 return -EINVAL; 951 } 952 953 list_for_each_entry(pg, &m->priority_groups, list) { 954 if (!--pgnum) 955 break; 956 } 957 958 bypass_pg(m, pg, bypassed); 959 return 0; 960 } 961 962 /* 963 * pg_init must call this when it has completed its initialisation 964 */ 965 void dm_pg_init_complete(struct path *path, unsigned err_flags) 966 { 967 struct pgpath *pgpath = path_to_pgpath(path); 968 struct priority_group *pg = pgpath->pg; 969 struct multipath *m = pg->m; 970 unsigned long flags; 971 972 /* We insist on failing the path if the PG is already bypassed. */ 973 if (err_flags && pg->bypassed) 974 err_flags |= MP_FAIL_PATH; 975 976 if (err_flags & MP_FAIL_PATH) 977 fail_path(pgpath); 978 979 if (err_flags & MP_BYPASS_PG) 980 bypass_pg(m, pg, 1); 981 982 spin_lock_irqsave(&m->lock, flags); 983 if (err_flags) { 984 m->current_pgpath = NULL; 985 m->current_pg = NULL; 986 } else if (!m->pg_init_required) 987 m->queue_io = 0; 988 989 m->pg_init_in_progress = 0; 990 queue_work(kmultipathd, &m->process_queued_ios); 991 spin_unlock_irqrestore(&m->lock, flags); 992 } 993 994 /* 995 * end_io handling 996 */ 997 static int do_end_io(struct multipath *m, struct bio *bio, 998 int error, struct mpath_io *mpio) 999 { 1000 struct hw_handler *hwh = &m->hw_handler; 1001 unsigned err_flags = MP_FAIL_PATH; /* Default behavior */ 1002 unsigned long flags; 1003 1004 if (!error) 1005 return 0; /* I/O complete */ 1006 1007 if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio)) 1008 return error; 1009 1010 if (error == -EOPNOTSUPP) 1011 return error; 1012 1013 spin_lock_irqsave(&m->lock, flags); 1014 if (!m->nr_valid_paths) { 1015 if (!m->queue_if_no_path) { 1016 spin_unlock_irqrestore(&m->lock, flags); 1017 return -EIO; 1018 } else { 1019 spin_unlock_irqrestore(&m->lock, flags); 1020 goto requeue; 1021 } 1022 } 1023 spin_unlock_irqrestore(&m->lock, flags); 1024 1025 if (hwh->type && hwh->type->error) 1026 err_flags = hwh->type->error(hwh, bio); 1027 1028 if (mpio->pgpath) { 1029 if (err_flags & MP_FAIL_PATH) 1030 fail_path(mpio->pgpath); 1031 1032 if (err_flags & MP_BYPASS_PG) 1033 bypass_pg(m, mpio->pgpath->pg, 1); 1034 } 1035 1036 if (err_flags & MP_ERROR_IO) 1037 return -EIO; 1038 1039 requeue: 1040 dm_bio_restore(&mpio->details, bio); 1041 1042 /* queue for the daemon to resubmit or fail */ 1043 spin_lock_irqsave(&m->lock, flags); 1044 bio_list_add(&m->queued_ios, bio); 1045 m->queue_size++; 1046 if (!m->queue_io) 1047 queue_work(kmultipathd, &m->process_queued_ios); 1048 spin_unlock_irqrestore(&m->lock, flags); 1049 1050 return 1; /* io not complete */ 1051 } 1052 1053 static int multipath_end_io(struct dm_target *ti, struct bio *bio, 1054 int error, union map_info *map_context) 1055 { 1056 struct multipath *m = (struct multipath *) ti->private; 1057 struct mpath_io *mpio = (struct mpath_io *) map_context->ptr; 1058 struct pgpath *pgpath = mpio->pgpath; 1059 struct path_selector *ps; 1060 int r; 1061 1062 r = do_end_io(m, bio, error, mpio); 1063 if (pgpath) { 1064 ps = &pgpath->pg->ps; 1065 if (ps->type->end_io) 1066 ps->type->end_io(ps, &pgpath->path); 1067 } 1068 if (r <= 0) 1069 mempool_free(mpio, m->mpio_pool); 1070 1071 return r; 1072 } 1073 1074 /* 1075 * Suspend can't complete until all the I/O is processed so if 1076 * the last path fails we must error any remaining I/O. 1077 * Note that if the freeze_bdev fails while suspending, the 1078 * queue_if_no_path state is lost - userspace should reset it. 1079 */ 1080 static void multipath_presuspend(struct dm_target *ti) 1081 { 1082 struct multipath *m = (struct multipath *) ti->private; 1083 1084 queue_if_no_path(m, 0, 1); 1085 } 1086 1087 /* 1088 * Restore the queue_if_no_path setting. 1089 */ 1090 static void multipath_resume(struct dm_target *ti) 1091 { 1092 struct multipath *m = (struct multipath *) ti->private; 1093 unsigned long flags; 1094 1095 spin_lock_irqsave(&m->lock, flags); 1096 m->queue_if_no_path = m->saved_queue_if_no_path; 1097 spin_unlock_irqrestore(&m->lock, flags); 1098 } 1099 1100 /* 1101 * Info output has the following format: 1102 * num_multipath_feature_args [multipath_feature_args]* 1103 * num_handler_status_args [handler_status_args]* 1104 * num_groups init_group_number 1105 * [A|D|E num_ps_status_args [ps_status_args]* 1106 * num_paths num_selector_args 1107 * [path_dev A|F fail_count [selector_args]* ]+ ]+ 1108 * 1109 * Table output has the following format (identical to the constructor string): 1110 * num_feature_args [features_args]* 1111 * num_handler_args hw_handler [hw_handler_args]* 1112 * num_groups init_group_number 1113 * [priority selector-name num_ps_args [ps_args]* 1114 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+ 1115 */ 1116 static int multipath_status(struct dm_target *ti, status_type_t type, 1117 char *result, unsigned int maxlen) 1118 { 1119 int sz = 0; 1120 unsigned long flags; 1121 struct multipath *m = (struct multipath *) ti->private; 1122 struct hw_handler *hwh = &m->hw_handler; 1123 struct priority_group *pg; 1124 struct pgpath *p; 1125 unsigned pg_num; 1126 char state; 1127 1128 spin_lock_irqsave(&m->lock, flags); 1129 1130 /* Features */ 1131 if (type == STATUSTYPE_INFO) 1132 DMEMIT("1 %u ", m->queue_size); 1133 else if (m->queue_if_no_path) 1134 DMEMIT("1 queue_if_no_path "); 1135 else 1136 DMEMIT("0 "); 1137 1138 if (hwh->type && hwh->type->status) 1139 sz += hwh->type->status(hwh, type, result + sz, maxlen - sz); 1140 else if (!hwh->type || type == STATUSTYPE_INFO) 1141 DMEMIT("0 "); 1142 else 1143 DMEMIT("1 %s ", hwh->type->name); 1144 1145 DMEMIT("%u ", m->nr_priority_groups); 1146 1147 if (m->next_pg) 1148 pg_num = m->next_pg->pg_num; 1149 else if (m->current_pg) 1150 pg_num = m->current_pg->pg_num; 1151 else 1152 pg_num = 1; 1153 1154 DMEMIT("%u ", pg_num); 1155 1156 switch (type) { 1157 case STATUSTYPE_INFO: 1158 list_for_each_entry(pg, &m->priority_groups, list) { 1159 if (pg->bypassed) 1160 state = 'D'; /* Disabled */ 1161 else if (pg == m->current_pg) 1162 state = 'A'; /* Currently Active */ 1163 else 1164 state = 'E'; /* Enabled */ 1165 1166 DMEMIT("%c ", state); 1167 1168 if (pg->ps.type->status) 1169 sz += pg->ps.type->status(&pg->ps, NULL, type, 1170 result + sz, 1171 maxlen - sz); 1172 else 1173 DMEMIT("0 "); 1174 1175 DMEMIT("%u %u ", pg->nr_pgpaths, 1176 pg->ps.type->info_args); 1177 1178 list_for_each_entry(p, &pg->pgpaths, list) { 1179 DMEMIT("%s %s %u ", p->path.dev->name, 1180 p->path.is_active ? "A" : "F", 1181 p->fail_count); 1182 if (pg->ps.type->status) 1183 sz += pg->ps.type->status(&pg->ps, 1184 &p->path, type, result + sz, 1185 maxlen - sz); 1186 } 1187 } 1188 break; 1189 1190 case STATUSTYPE_TABLE: 1191 list_for_each_entry(pg, &m->priority_groups, list) { 1192 DMEMIT("%s ", pg->ps.type->name); 1193 1194 if (pg->ps.type->status) 1195 sz += pg->ps.type->status(&pg->ps, NULL, type, 1196 result + sz, 1197 maxlen - sz); 1198 else 1199 DMEMIT("0 "); 1200 1201 DMEMIT("%u %u ", pg->nr_pgpaths, 1202 pg->ps.type->table_args); 1203 1204 list_for_each_entry(p, &pg->pgpaths, list) { 1205 DMEMIT("%s ", p->path.dev->name); 1206 if (pg->ps.type->status) 1207 sz += pg->ps.type->status(&pg->ps, 1208 &p->path, type, result + sz, 1209 maxlen - sz); 1210 } 1211 } 1212 break; 1213 } 1214 1215 spin_unlock_irqrestore(&m->lock, flags); 1216 1217 return 0; 1218 } 1219 1220 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv) 1221 { 1222 int r; 1223 struct dm_dev *dev; 1224 struct multipath *m = (struct multipath *) ti->private; 1225 action_fn action; 1226 1227 if (argc == 1) { 1228 if (!strnicmp(argv[0], MESG_STR("queue_if_no_path"))) 1229 return queue_if_no_path(m, 1, 0); 1230 else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path"))) 1231 return queue_if_no_path(m, 0, 0); 1232 } 1233 1234 if (argc != 2) 1235 goto error; 1236 1237 if (!strnicmp(argv[0], MESG_STR("disable_group"))) 1238 return bypass_pg_num(m, argv[1], 1); 1239 else if (!strnicmp(argv[0], MESG_STR("enable_group"))) 1240 return bypass_pg_num(m, argv[1], 0); 1241 else if (!strnicmp(argv[0], MESG_STR("switch_group"))) 1242 return switch_pg_num(m, argv[1]); 1243 else if (!strnicmp(argv[0], MESG_STR("reinstate_path"))) 1244 action = reinstate_path; 1245 else if (!strnicmp(argv[0], MESG_STR("fail_path"))) 1246 action = fail_path; 1247 else 1248 goto error; 1249 1250 r = dm_get_device(ti, argv[1], ti->begin, ti->len, 1251 dm_table_get_mode(ti->table), &dev); 1252 if (r) { 1253 DMWARN("message: error getting device %s", 1254 argv[1]); 1255 return -EINVAL; 1256 } 1257 1258 r = action_dev(m, dev, action); 1259 1260 dm_put_device(ti, dev); 1261 1262 return r; 1263 1264 error: 1265 DMWARN("Unrecognised multipath message received."); 1266 return -EINVAL; 1267 } 1268 1269 /*----------------------------------------------------------------- 1270 * Module setup 1271 *---------------------------------------------------------------*/ 1272 static struct target_type multipath_target = { 1273 .name = "multipath", 1274 .version = {1, 0, 4}, 1275 .module = THIS_MODULE, 1276 .ctr = multipath_ctr, 1277 .dtr = multipath_dtr, 1278 .map = multipath_map, 1279 .end_io = multipath_end_io, 1280 .presuspend = multipath_presuspend, 1281 .resume = multipath_resume, 1282 .status = multipath_status, 1283 .message = multipath_message, 1284 }; 1285 1286 static int __init dm_multipath_init(void) 1287 { 1288 int r; 1289 1290 /* allocate a slab for the dm_ios */ 1291 _mpio_cache = kmem_cache_create("dm_mpath", sizeof(struct mpath_io), 1292 0, 0, NULL, NULL); 1293 if (!_mpio_cache) 1294 return -ENOMEM; 1295 1296 r = dm_register_target(&multipath_target); 1297 if (r < 0) { 1298 DMERR("%s: register failed %d", multipath_target.name, r); 1299 kmem_cache_destroy(_mpio_cache); 1300 return -EINVAL; 1301 } 1302 1303 kmultipathd = create_workqueue("kmpathd"); 1304 if (!kmultipathd) { 1305 DMERR("%s: failed to create workqueue kmpathd", 1306 multipath_target.name); 1307 dm_unregister_target(&multipath_target); 1308 kmem_cache_destroy(_mpio_cache); 1309 return -ENOMEM; 1310 } 1311 1312 DMINFO("version %u.%u.%u loaded", 1313 multipath_target.version[0], multipath_target.version[1], 1314 multipath_target.version[2]); 1315 1316 return r; 1317 } 1318 1319 static void __exit dm_multipath_exit(void) 1320 { 1321 int r; 1322 1323 destroy_workqueue(kmultipathd); 1324 1325 r = dm_unregister_target(&multipath_target); 1326 if (r < 0) 1327 DMERR("%s: target unregister failed %d", 1328 multipath_target.name, r); 1329 kmem_cache_destroy(_mpio_cache); 1330 } 1331 1332 EXPORT_SYMBOL_GPL(dm_pg_init_complete); 1333 1334 module_init(dm_multipath_init); 1335 module_exit(dm_multipath_exit); 1336 1337 MODULE_DESCRIPTION(DM_NAME " multipath target"); 1338 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>"); 1339 MODULE_LICENSE("GPL"); 1340