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