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 dm_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 struct kmem_cache *_mpio_cache; 105 106 struct workqueue_struct *kmultipathd; 107 static void process_queued_ios(struct work_struct *work); 108 static void trigger_event(struct work_struct *work); 109 110 111 /*----------------------------------------------- 112 * Allocation routines 113 *-----------------------------------------------*/ 114 115 static struct pgpath *alloc_pgpath(void) 116 { 117 struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL); 118 119 if (pgpath) 120 pgpath->path.is_active = 1; 121 122 return pgpath; 123 } 124 125 static inline void free_pgpath(struct pgpath *pgpath) 126 { 127 kfree(pgpath); 128 } 129 130 static struct priority_group *alloc_priority_group(void) 131 { 132 struct priority_group *pg; 133 134 pg = kzalloc(sizeof(*pg), GFP_KERNEL); 135 136 if (pg) 137 INIT_LIST_HEAD(&pg->pgpaths); 138 139 return pg; 140 } 141 142 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti) 143 { 144 struct pgpath *pgpath, *tmp; 145 146 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) { 147 list_del(&pgpath->list); 148 dm_put_device(ti, pgpath->path.dev); 149 free_pgpath(pgpath); 150 } 151 } 152 153 static void free_priority_group(struct priority_group *pg, 154 struct dm_target *ti) 155 { 156 struct path_selector *ps = &pg->ps; 157 158 if (ps->type) { 159 ps->type->destroy(ps); 160 dm_put_path_selector(ps->type); 161 } 162 163 free_pgpaths(&pg->pgpaths, ti); 164 kfree(pg); 165 } 166 167 static struct multipath *alloc_multipath(struct dm_target *ti) 168 { 169 struct multipath *m; 170 171 m = kzalloc(sizeof(*m), GFP_KERNEL); 172 if (m) { 173 INIT_LIST_HEAD(&m->priority_groups); 174 spin_lock_init(&m->lock); 175 m->queue_io = 1; 176 INIT_WORK(&m->process_queued_ios, process_queued_ios); 177 INIT_WORK(&m->trigger_event, trigger_event); 178 m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache); 179 if (!m->mpio_pool) { 180 kfree(m); 181 return NULL; 182 } 183 m->ti = ti; 184 ti->private = m; 185 } 186 187 return m; 188 } 189 190 static void free_multipath(struct multipath *m) 191 { 192 struct priority_group *pg, *tmp; 193 struct hw_handler *hwh = &m->hw_handler; 194 195 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) { 196 list_del(&pg->list); 197 free_priority_group(pg, m->ti); 198 } 199 200 if (hwh->type) { 201 hwh->type->destroy(hwh); 202 dm_put_hw_handler(hwh->type); 203 } 204 205 mempool_destroy(m->mpio_pool); 206 kfree(m); 207 } 208 209 210 /*----------------------------------------------- 211 * Path selection 212 *-----------------------------------------------*/ 213 214 static void __switch_pg(struct multipath *m, struct pgpath *pgpath) 215 { 216 struct hw_handler *hwh = &m->hw_handler; 217 218 m->current_pg = pgpath->pg; 219 220 /* Must we initialise the PG first, and queue I/O till it's ready? */ 221 if (hwh->type && hwh->type->pg_init) { 222 m->pg_init_required = 1; 223 m->queue_io = 1; 224 } else { 225 m->pg_init_required = 0; 226 m->queue_io = 0; 227 } 228 } 229 230 static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg) 231 { 232 struct dm_path *path; 233 234 path = pg->ps.type->select_path(&pg->ps, &m->repeat_count); 235 if (!path) 236 return -ENXIO; 237 238 m->current_pgpath = path_to_pgpath(path); 239 240 if (m->current_pg != pg) 241 __switch_pg(m, m->current_pgpath); 242 243 return 0; 244 } 245 246 static void __choose_pgpath(struct multipath *m) 247 { 248 struct priority_group *pg; 249 unsigned bypassed = 1; 250 251 if (!m->nr_valid_paths) 252 goto failed; 253 254 /* Were we instructed to switch PG? */ 255 if (m->next_pg) { 256 pg = m->next_pg; 257 m->next_pg = NULL; 258 if (!__choose_path_in_pg(m, pg)) 259 return; 260 } 261 262 /* Don't change PG until it has no remaining paths */ 263 if (m->current_pg && !__choose_path_in_pg(m, m->current_pg)) 264 return; 265 266 /* 267 * Loop through priority groups until we find a valid path. 268 * First time we skip PGs marked 'bypassed'. 269 * Second time we only try the ones we skipped. 270 */ 271 do { 272 list_for_each_entry(pg, &m->priority_groups, list) { 273 if (pg->bypassed == bypassed) 274 continue; 275 if (!__choose_path_in_pg(m, pg)) 276 return; 277 } 278 } while (bypassed--); 279 280 failed: 281 m->current_pgpath = NULL; 282 m->current_pg = NULL; 283 } 284 285 static int map_io(struct multipath *m, struct bio *bio, struct mpath_io *mpio, 286 unsigned was_queued) 287 { 288 int r = 1; 289 unsigned long flags; 290 struct pgpath *pgpath; 291 292 spin_lock_irqsave(&m->lock, flags); 293 294 /* Do we need to select a new pgpath? */ 295 if (!m->current_pgpath || 296 (!m->queue_io && (m->repeat_count && --m->repeat_count == 0))) 297 __choose_pgpath(m); 298 299 pgpath = m->current_pgpath; 300 301 if (was_queued) 302 m->queue_size--; 303 304 if ((pgpath && m->queue_io) || 305 (!pgpath && m->queue_if_no_path)) { 306 /* Queue for the daemon to resubmit */ 307 bio_list_add(&m->queued_ios, bio); 308 m->queue_size++; 309 if ((m->pg_init_required && !m->pg_init_in_progress) || 310 !m->queue_io) 311 queue_work(kmultipathd, &m->process_queued_ios); 312 pgpath = NULL; 313 r = 0; 314 } else if (!pgpath) 315 r = -EIO; /* Failed */ 316 else 317 bio->bi_bdev = pgpath->path.dev->bdev; 318 319 mpio->pgpath = pgpath; 320 321 spin_unlock_irqrestore(&m->lock, flags); 322 323 return r; 324 } 325 326 /* 327 * If we run out of usable paths, should we queue I/O or error it? 328 */ 329 static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path, 330 unsigned save_old_value) 331 { 332 unsigned long flags; 333 334 spin_lock_irqsave(&m->lock, flags); 335 336 if (save_old_value) 337 m->saved_queue_if_no_path = m->queue_if_no_path; 338 else 339 m->saved_queue_if_no_path = queue_if_no_path; 340 m->queue_if_no_path = queue_if_no_path; 341 if (!m->queue_if_no_path && m->queue_size) 342 queue_work(kmultipathd, &m->process_queued_ios); 343 344 spin_unlock_irqrestore(&m->lock, flags); 345 346 return 0; 347 } 348 349 /*----------------------------------------------------------------- 350 * The multipath daemon is responsible for resubmitting queued ios. 351 *---------------------------------------------------------------*/ 352 353 static void dispatch_queued_ios(struct multipath *m) 354 { 355 int r; 356 unsigned long flags; 357 struct bio *bio = NULL, *next; 358 struct mpath_io *mpio; 359 union map_info *info; 360 361 spin_lock_irqsave(&m->lock, flags); 362 bio = bio_list_get(&m->queued_ios); 363 spin_unlock_irqrestore(&m->lock, flags); 364 365 while (bio) { 366 next = bio->bi_next; 367 bio->bi_next = NULL; 368 369 info = dm_get_mapinfo(bio); 370 mpio = info->ptr; 371 372 r = map_io(m, bio, mpio, 1); 373 if (r < 0) 374 bio_endio(bio, bio->bi_size, r); 375 else if (r == 1) 376 generic_make_request(bio); 377 378 bio = next; 379 } 380 } 381 382 static void process_queued_ios(struct work_struct *work) 383 { 384 struct multipath *m = 385 container_of(work, struct multipath, process_queued_ios); 386 struct hw_handler *hwh = &m->hw_handler; 387 struct pgpath *pgpath = NULL; 388 unsigned init_required = 0, must_queue = 1; 389 unsigned long flags; 390 391 spin_lock_irqsave(&m->lock, flags); 392 393 if (!m->queue_size) 394 goto out; 395 396 if (!m->current_pgpath) 397 __choose_pgpath(m); 398 399 pgpath = m->current_pgpath; 400 401 if ((pgpath && !m->queue_io) || 402 (!pgpath && !m->queue_if_no_path)) 403 must_queue = 0; 404 405 if (m->pg_init_required && !m->pg_init_in_progress) { 406 m->pg_init_required = 0; 407 m->pg_init_in_progress = 1; 408 init_required = 1; 409 } 410 411 out: 412 spin_unlock_irqrestore(&m->lock, flags); 413 414 if (init_required) 415 hwh->type->pg_init(hwh, pgpath->pg->bypassed, &pgpath->path); 416 417 if (!must_queue) 418 dispatch_queued_ios(m); 419 } 420 421 /* 422 * An event is triggered whenever a path is taken out of use. 423 * Includes path failure and PG bypass. 424 */ 425 static void trigger_event(struct work_struct *work) 426 { 427 struct multipath *m = 428 container_of(work, struct multipath, trigger_event); 429 430 dm_table_event(m->ti->table); 431 } 432 433 /*----------------------------------------------------------------- 434 * Constructor/argument parsing: 435 * <#multipath feature args> [<arg>]* 436 * <#hw_handler args> [hw_handler [<arg>]*] 437 * <#priority groups> 438 * <initial priority group> 439 * [<selector> <#selector args> [<arg>]* 440 * <#paths> <#per-path selector args> 441 * [<path> [<arg>]* ]+ ]+ 442 *---------------------------------------------------------------*/ 443 struct param { 444 unsigned min; 445 unsigned max; 446 char *error; 447 }; 448 449 static int read_param(struct param *param, char *str, unsigned *v, char **error) 450 { 451 if (!str || 452 (sscanf(str, "%u", v) != 1) || 453 (*v < param->min) || 454 (*v > param->max)) { 455 *error = param->error; 456 return -EINVAL; 457 } 458 459 return 0; 460 } 461 462 struct arg_set { 463 unsigned argc; 464 char **argv; 465 }; 466 467 static char *shift(struct arg_set *as) 468 { 469 char *r; 470 471 if (as->argc) { 472 as->argc--; 473 r = *as->argv; 474 as->argv++; 475 return r; 476 } 477 478 return NULL; 479 } 480 481 static void consume(struct arg_set *as, unsigned n) 482 { 483 BUG_ON (as->argc < n); 484 as->argc -= n; 485 as->argv += n; 486 } 487 488 static int parse_path_selector(struct arg_set *as, struct priority_group *pg, 489 struct dm_target *ti) 490 { 491 int r; 492 struct path_selector_type *pst; 493 unsigned ps_argc; 494 495 static struct param _params[] = { 496 {0, 1024, "invalid number of path selector args"}, 497 }; 498 499 pst = dm_get_path_selector(shift(as)); 500 if (!pst) { 501 ti->error = "unknown path selector type"; 502 return -EINVAL; 503 } 504 505 r = read_param(_params, shift(as), &ps_argc, &ti->error); 506 if (r) 507 return -EINVAL; 508 509 r = pst->create(&pg->ps, ps_argc, as->argv); 510 if (r) { 511 dm_put_path_selector(pst); 512 ti->error = "path selector constructor failed"; 513 return r; 514 } 515 516 pg->ps.type = pst; 517 consume(as, ps_argc); 518 519 return 0; 520 } 521 522 static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps, 523 struct dm_target *ti) 524 { 525 int r; 526 struct pgpath *p; 527 528 /* we need at least a path arg */ 529 if (as->argc < 1) { 530 ti->error = "no device given"; 531 return NULL; 532 } 533 534 p = alloc_pgpath(); 535 if (!p) 536 return NULL; 537 538 r = dm_get_device(ti, shift(as), ti->begin, ti->len, 539 dm_table_get_mode(ti->table), &p->path.dev); 540 if (r) { 541 ti->error = "error getting device"; 542 goto bad; 543 } 544 545 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error); 546 if (r) { 547 dm_put_device(ti, p->path.dev); 548 goto bad; 549 } 550 551 return p; 552 553 bad: 554 free_pgpath(p); 555 return NULL; 556 } 557 558 static struct priority_group *parse_priority_group(struct arg_set *as, 559 struct multipath *m) 560 { 561 static struct param _params[] = { 562 {1, 1024, "invalid number of paths"}, 563 {0, 1024, "invalid number of selector args"} 564 }; 565 566 int r; 567 unsigned i, nr_selector_args, nr_params; 568 struct priority_group *pg; 569 struct dm_target *ti = m->ti; 570 571 if (as->argc < 2) { 572 as->argc = 0; 573 ti->error = "not enough priority group aruments"; 574 return NULL; 575 } 576 577 pg = alloc_priority_group(); 578 if (!pg) { 579 ti->error = "couldn't allocate priority group"; 580 return NULL; 581 } 582 pg->m = m; 583 584 r = parse_path_selector(as, pg, ti); 585 if (r) 586 goto bad; 587 588 /* 589 * read the paths 590 */ 591 r = read_param(_params, shift(as), &pg->nr_pgpaths, &ti->error); 592 if (r) 593 goto bad; 594 595 r = read_param(_params + 1, shift(as), &nr_selector_args, &ti->error); 596 if (r) 597 goto bad; 598 599 nr_params = 1 + nr_selector_args; 600 for (i = 0; i < pg->nr_pgpaths; i++) { 601 struct pgpath *pgpath; 602 struct arg_set path_args; 603 604 if (as->argc < nr_params) 605 goto bad; 606 607 path_args.argc = nr_params; 608 path_args.argv = as->argv; 609 610 pgpath = parse_path(&path_args, &pg->ps, ti); 611 if (!pgpath) 612 goto bad; 613 614 pgpath->pg = pg; 615 list_add_tail(&pgpath->list, &pg->pgpaths); 616 consume(as, nr_params); 617 } 618 619 return pg; 620 621 bad: 622 free_priority_group(pg, ti); 623 return NULL; 624 } 625 626 static int parse_hw_handler(struct arg_set *as, struct multipath *m) 627 { 628 int r; 629 struct hw_handler_type *hwht; 630 unsigned hw_argc; 631 struct dm_target *ti = m->ti; 632 633 static struct param _params[] = { 634 {0, 1024, "invalid number of hardware handler args"}, 635 }; 636 637 r = read_param(_params, shift(as), &hw_argc, &ti->error); 638 if (r) 639 return -EINVAL; 640 641 if (!hw_argc) 642 return 0; 643 644 hwht = dm_get_hw_handler(shift(as)); 645 if (!hwht) { 646 ti->error = "unknown hardware handler type"; 647 return -EINVAL; 648 } 649 650 r = hwht->create(&m->hw_handler, hw_argc - 1, as->argv); 651 if (r) { 652 dm_put_hw_handler(hwht); 653 ti->error = "hardware handler constructor failed"; 654 return r; 655 } 656 657 m->hw_handler.type = hwht; 658 consume(as, hw_argc - 1); 659 660 return 0; 661 } 662 663 static int parse_features(struct arg_set *as, struct multipath *m) 664 { 665 int r; 666 unsigned argc; 667 struct dm_target *ti = m->ti; 668 669 static struct param _params[] = { 670 {0, 1, "invalid number of feature args"}, 671 }; 672 673 r = read_param(_params, shift(as), &argc, &ti->error); 674 if (r) 675 return -EINVAL; 676 677 if (!argc) 678 return 0; 679 680 if (!strnicmp(shift(as), MESG_STR("queue_if_no_path"))) 681 return queue_if_no_path(m, 1, 0); 682 else { 683 ti->error = "Unrecognised multipath feature request"; 684 return -EINVAL; 685 } 686 } 687 688 static int multipath_ctr(struct dm_target *ti, unsigned int argc, 689 char **argv) 690 { 691 /* target parameters */ 692 static struct param _params[] = { 693 {1, 1024, "invalid number of priority groups"}, 694 {1, 1024, "invalid initial priority group number"}, 695 }; 696 697 int r; 698 struct multipath *m; 699 struct arg_set as; 700 unsigned pg_count = 0; 701 unsigned next_pg_num; 702 703 as.argc = argc; 704 as.argv = argv; 705 706 m = alloc_multipath(ti); 707 if (!m) { 708 ti->error = "can't allocate multipath"; 709 return -EINVAL; 710 } 711 712 r = parse_features(&as, m); 713 if (r) 714 goto bad; 715 716 r = parse_hw_handler(&as, m); 717 if (r) 718 goto bad; 719 720 r = read_param(_params, shift(&as), &m->nr_priority_groups, &ti->error); 721 if (r) 722 goto bad; 723 724 r = read_param(_params + 1, shift(&as), &next_pg_num, &ti->error); 725 if (r) 726 goto bad; 727 728 /* parse the priority groups */ 729 while (as.argc) { 730 struct priority_group *pg; 731 732 pg = parse_priority_group(&as, m); 733 if (!pg) { 734 r = -EINVAL; 735 goto bad; 736 } 737 738 m->nr_valid_paths += pg->nr_pgpaths; 739 list_add_tail(&pg->list, &m->priority_groups); 740 pg_count++; 741 pg->pg_num = pg_count; 742 if (!--next_pg_num) 743 m->next_pg = pg; 744 } 745 746 if (pg_count != m->nr_priority_groups) { 747 ti->error = "priority group count mismatch"; 748 r = -EINVAL; 749 goto bad; 750 } 751 752 return 0; 753 754 bad: 755 free_multipath(m); 756 return r; 757 } 758 759 static void multipath_dtr(struct dm_target *ti) 760 { 761 struct multipath *m = (struct multipath *) ti->private; 762 763 flush_workqueue(kmultipathd); 764 free_multipath(m); 765 } 766 767 /* 768 * Map bios, recording original fields for later in case we have to resubmit 769 */ 770 static int multipath_map(struct dm_target *ti, struct bio *bio, 771 union map_info *map_context) 772 { 773 int r; 774 struct mpath_io *mpio; 775 struct multipath *m = (struct multipath *) ti->private; 776 777 if (bio_barrier(bio)) 778 return -EOPNOTSUPP; 779 780 mpio = mempool_alloc(m->mpio_pool, GFP_NOIO); 781 dm_bio_record(&mpio->details, bio); 782 783 map_context->ptr = mpio; 784 bio->bi_rw |= (1 << BIO_RW_FAILFAST); 785 r = map_io(m, bio, mpio, 0); 786 if (r < 0) 787 mempool_free(mpio, m->mpio_pool); 788 789 return r; 790 } 791 792 /* 793 * Take a path out of use. 794 */ 795 static int fail_path(struct pgpath *pgpath) 796 { 797 unsigned long flags; 798 struct multipath *m = pgpath->pg->m; 799 800 spin_lock_irqsave(&m->lock, flags); 801 802 if (!pgpath->path.is_active) 803 goto out; 804 805 DMWARN("Failing path %s.", pgpath->path.dev->name); 806 807 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path); 808 pgpath->path.is_active = 0; 809 pgpath->fail_count++; 810 811 m->nr_valid_paths--; 812 813 if (pgpath == m->current_pgpath) 814 m->current_pgpath = NULL; 815 816 queue_work(kmultipathd, &m->trigger_event); 817 818 out: 819 spin_unlock_irqrestore(&m->lock, flags); 820 821 return 0; 822 } 823 824 /* 825 * Reinstate a previously-failed path 826 */ 827 static int reinstate_path(struct pgpath *pgpath) 828 { 829 int r = 0; 830 unsigned long flags; 831 struct multipath *m = pgpath->pg->m; 832 833 spin_lock_irqsave(&m->lock, flags); 834 835 if (pgpath->path.is_active) 836 goto out; 837 838 if (!pgpath->pg->ps.type) { 839 DMWARN("Reinstate path not supported by path selector %s", 840 pgpath->pg->ps.type->name); 841 r = -EINVAL; 842 goto out; 843 } 844 845 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path); 846 if (r) 847 goto out; 848 849 pgpath->path.is_active = 1; 850 851 m->current_pgpath = NULL; 852 if (!m->nr_valid_paths++ && m->queue_size) 853 queue_work(kmultipathd, &m->process_queued_ios); 854 855 queue_work(kmultipathd, &m->trigger_event); 856 857 out: 858 spin_unlock_irqrestore(&m->lock, flags); 859 860 return r; 861 } 862 863 /* 864 * Fail or reinstate all paths that match the provided struct dm_dev. 865 */ 866 static int action_dev(struct multipath *m, struct dm_dev *dev, 867 action_fn action) 868 { 869 int r = 0; 870 struct pgpath *pgpath; 871 struct priority_group *pg; 872 873 list_for_each_entry(pg, &m->priority_groups, list) { 874 list_for_each_entry(pgpath, &pg->pgpaths, list) { 875 if (pgpath->path.dev == dev) 876 r = action(pgpath); 877 } 878 } 879 880 return r; 881 } 882 883 /* 884 * Temporarily try to avoid having to use the specified PG 885 */ 886 static void bypass_pg(struct multipath *m, struct priority_group *pg, 887 int bypassed) 888 { 889 unsigned long flags; 890 891 spin_lock_irqsave(&m->lock, flags); 892 893 pg->bypassed = bypassed; 894 m->current_pgpath = NULL; 895 m->current_pg = NULL; 896 897 spin_unlock_irqrestore(&m->lock, flags); 898 899 queue_work(kmultipathd, &m->trigger_event); 900 } 901 902 /* 903 * Switch to using the specified PG from the next I/O that gets mapped 904 */ 905 static int switch_pg_num(struct multipath *m, const char *pgstr) 906 { 907 struct priority_group *pg; 908 unsigned pgnum; 909 unsigned long flags; 910 911 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum || 912 (pgnum > m->nr_priority_groups)) { 913 DMWARN("invalid PG number supplied to switch_pg_num"); 914 return -EINVAL; 915 } 916 917 spin_lock_irqsave(&m->lock, flags); 918 list_for_each_entry(pg, &m->priority_groups, list) { 919 pg->bypassed = 0; 920 if (--pgnum) 921 continue; 922 923 m->current_pgpath = NULL; 924 m->current_pg = NULL; 925 m->next_pg = pg; 926 } 927 spin_unlock_irqrestore(&m->lock, flags); 928 929 queue_work(kmultipathd, &m->trigger_event); 930 return 0; 931 } 932 933 /* 934 * Set/clear bypassed status of a PG. 935 * PGs are numbered upwards from 1 in the order they were declared. 936 */ 937 static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed) 938 { 939 struct priority_group *pg; 940 unsigned pgnum; 941 942 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum || 943 (pgnum > m->nr_priority_groups)) { 944 DMWARN("invalid PG number supplied to bypass_pg"); 945 return -EINVAL; 946 } 947 948 list_for_each_entry(pg, &m->priority_groups, list) { 949 if (!--pgnum) 950 break; 951 } 952 953 bypass_pg(m, pg, bypassed); 954 return 0; 955 } 956 957 /* 958 * pg_init must call this when it has completed its initialisation 959 */ 960 void dm_pg_init_complete(struct dm_path *path, unsigned err_flags) 961 { 962 struct pgpath *pgpath = path_to_pgpath(path); 963 struct priority_group *pg = pgpath->pg; 964 struct multipath *m = pg->m; 965 unsigned long flags; 966 967 /* We insist on failing the path if the PG is already bypassed. */ 968 if (err_flags && pg->bypassed) 969 err_flags |= MP_FAIL_PATH; 970 971 if (err_flags & MP_FAIL_PATH) 972 fail_path(pgpath); 973 974 if (err_flags & MP_BYPASS_PG) 975 bypass_pg(m, pg, 1); 976 977 spin_lock_irqsave(&m->lock, flags); 978 if (err_flags) { 979 m->current_pgpath = NULL; 980 m->current_pg = NULL; 981 } else if (!m->pg_init_required) 982 m->queue_io = 0; 983 984 m->pg_init_in_progress = 0; 985 queue_work(kmultipathd, &m->process_queued_ios); 986 spin_unlock_irqrestore(&m->lock, flags); 987 } 988 989 /* 990 * end_io handling 991 */ 992 static int do_end_io(struct multipath *m, struct bio *bio, 993 int error, struct mpath_io *mpio) 994 { 995 struct hw_handler *hwh = &m->hw_handler; 996 unsigned err_flags = MP_FAIL_PATH; /* Default behavior */ 997 unsigned long flags; 998 999 if (!error) 1000 return 0; /* I/O complete */ 1001 1002 if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio)) 1003 return error; 1004 1005 if (error == -EOPNOTSUPP) 1006 return error; 1007 1008 spin_lock_irqsave(&m->lock, flags); 1009 if (!m->nr_valid_paths) { 1010 if (!m->queue_if_no_path) { 1011 spin_unlock_irqrestore(&m->lock, flags); 1012 return -EIO; 1013 } else { 1014 spin_unlock_irqrestore(&m->lock, flags); 1015 goto requeue; 1016 } 1017 } 1018 spin_unlock_irqrestore(&m->lock, flags); 1019 1020 if (hwh->type && hwh->type->error) 1021 err_flags = hwh->type->error(hwh, bio); 1022 1023 if (mpio->pgpath) { 1024 if (err_flags & MP_FAIL_PATH) 1025 fail_path(mpio->pgpath); 1026 1027 if (err_flags & MP_BYPASS_PG) 1028 bypass_pg(m, mpio->pgpath->pg, 1); 1029 } 1030 1031 if (err_flags & MP_ERROR_IO) 1032 return -EIO; 1033 1034 requeue: 1035 dm_bio_restore(&mpio->details, bio); 1036 1037 /* queue for the daemon to resubmit or fail */ 1038 spin_lock_irqsave(&m->lock, flags); 1039 bio_list_add(&m->queued_ios, bio); 1040 m->queue_size++; 1041 if (!m->queue_io) 1042 queue_work(kmultipathd, &m->process_queued_ios); 1043 spin_unlock_irqrestore(&m->lock, flags); 1044 1045 return 1; /* io not complete */ 1046 } 1047 1048 static int multipath_end_io(struct dm_target *ti, struct bio *bio, 1049 int error, union map_info *map_context) 1050 { 1051 struct multipath *m = (struct multipath *) ti->private; 1052 struct mpath_io *mpio = (struct mpath_io *) map_context->ptr; 1053 struct pgpath *pgpath = mpio->pgpath; 1054 struct path_selector *ps; 1055 int r; 1056 1057 r = do_end_io(m, bio, error, mpio); 1058 if (pgpath) { 1059 ps = &pgpath->pg->ps; 1060 if (ps->type->end_io) 1061 ps->type->end_io(ps, &pgpath->path); 1062 } 1063 if (r <= 0) 1064 mempool_free(mpio, m->mpio_pool); 1065 1066 return r; 1067 } 1068 1069 /* 1070 * Suspend can't complete until all the I/O is processed so if 1071 * the last path fails we must error any remaining I/O. 1072 * Note that if the freeze_bdev fails while suspending, the 1073 * queue_if_no_path state is lost - userspace should reset it. 1074 */ 1075 static void multipath_presuspend(struct dm_target *ti) 1076 { 1077 struct multipath *m = (struct multipath *) ti->private; 1078 1079 queue_if_no_path(m, 0, 1); 1080 } 1081 1082 /* 1083 * Restore the queue_if_no_path setting. 1084 */ 1085 static void multipath_resume(struct dm_target *ti) 1086 { 1087 struct multipath *m = (struct multipath *) ti->private; 1088 unsigned long flags; 1089 1090 spin_lock_irqsave(&m->lock, flags); 1091 m->queue_if_no_path = m->saved_queue_if_no_path; 1092 spin_unlock_irqrestore(&m->lock, flags); 1093 } 1094 1095 /* 1096 * Info output has the following format: 1097 * num_multipath_feature_args [multipath_feature_args]* 1098 * num_handler_status_args [handler_status_args]* 1099 * num_groups init_group_number 1100 * [A|D|E num_ps_status_args [ps_status_args]* 1101 * num_paths num_selector_args 1102 * [path_dev A|F fail_count [selector_args]* ]+ ]+ 1103 * 1104 * Table output has the following format (identical to the constructor string): 1105 * num_feature_args [features_args]* 1106 * num_handler_args hw_handler [hw_handler_args]* 1107 * num_groups init_group_number 1108 * [priority selector-name num_ps_args [ps_args]* 1109 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+ 1110 */ 1111 static int multipath_status(struct dm_target *ti, status_type_t type, 1112 char *result, unsigned int maxlen) 1113 { 1114 int sz = 0; 1115 unsigned long flags; 1116 struct multipath *m = (struct multipath *) ti->private; 1117 struct hw_handler *hwh = &m->hw_handler; 1118 struct priority_group *pg; 1119 struct pgpath *p; 1120 unsigned pg_num; 1121 char state; 1122 1123 spin_lock_irqsave(&m->lock, flags); 1124 1125 /* Features */ 1126 if (type == STATUSTYPE_INFO) 1127 DMEMIT("1 %u ", m->queue_size); 1128 else if (m->queue_if_no_path) 1129 DMEMIT("1 queue_if_no_path "); 1130 else 1131 DMEMIT("0 "); 1132 1133 if (hwh->type && hwh->type->status) 1134 sz += hwh->type->status(hwh, type, result + sz, maxlen - sz); 1135 else if (!hwh->type || type == STATUSTYPE_INFO) 1136 DMEMIT("0 "); 1137 else 1138 DMEMIT("1 %s ", hwh->type->name); 1139 1140 DMEMIT("%u ", m->nr_priority_groups); 1141 1142 if (m->next_pg) 1143 pg_num = m->next_pg->pg_num; 1144 else if (m->current_pg) 1145 pg_num = m->current_pg->pg_num; 1146 else 1147 pg_num = 1; 1148 1149 DMEMIT("%u ", pg_num); 1150 1151 switch (type) { 1152 case STATUSTYPE_INFO: 1153 list_for_each_entry(pg, &m->priority_groups, list) { 1154 if (pg->bypassed) 1155 state = 'D'; /* Disabled */ 1156 else if (pg == m->current_pg) 1157 state = 'A'; /* Currently Active */ 1158 else 1159 state = 'E'; /* Enabled */ 1160 1161 DMEMIT("%c ", state); 1162 1163 if (pg->ps.type->status) 1164 sz += pg->ps.type->status(&pg->ps, NULL, type, 1165 result + sz, 1166 maxlen - sz); 1167 else 1168 DMEMIT("0 "); 1169 1170 DMEMIT("%u %u ", pg->nr_pgpaths, 1171 pg->ps.type->info_args); 1172 1173 list_for_each_entry(p, &pg->pgpaths, list) { 1174 DMEMIT("%s %s %u ", p->path.dev->name, 1175 p->path.is_active ? "A" : "F", 1176 p->fail_count); 1177 if (pg->ps.type->status) 1178 sz += pg->ps.type->status(&pg->ps, 1179 &p->path, type, result + sz, 1180 maxlen - sz); 1181 } 1182 } 1183 break; 1184 1185 case STATUSTYPE_TABLE: 1186 list_for_each_entry(pg, &m->priority_groups, list) { 1187 DMEMIT("%s ", pg->ps.type->name); 1188 1189 if (pg->ps.type->status) 1190 sz += pg->ps.type->status(&pg->ps, NULL, type, 1191 result + sz, 1192 maxlen - sz); 1193 else 1194 DMEMIT("0 "); 1195 1196 DMEMIT("%u %u ", pg->nr_pgpaths, 1197 pg->ps.type->table_args); 1198 1199 list_for_each_entry(p, &pg->pgpaths, list) { 1200 DMEMIT("%s ", p->path.dev->name); 1201 if (pg->ps.type->status) 1202 sz += pg->ps.type->status(&pg->ps, 1203 &p->path, type, result + sz, 1204 maxlen - sz); 1205 } 1206 } 1207 break; 1208 } 1209 1210 spin_unlock_irqrestore(&m->lock, flags); 1211 1212 return 0; 1213 } 1214 1215 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv) 1216 { 1217 int r; 1218 struct dm_dev *dev; 1219 struct multipath *m = (struct multipath *) ti->private; 1220 action_fn action; 1221 1222 if (argc == 1) { 1223 if (!strnicmp(argv[0], MESG_STR("queue_if_no_path"))) 1224 return queue_if_no_path(m, 1, 0); 1225 else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path"))) 1226 return queue_if_no_path(m, 0, 0); 1227 } 1228 1229 if (argc != 2) 1230 goto error; 1231 1232 if (!strnicmp(argv[0], MESG_STR("disable_group"))) 1233 return bypass_pg_num(m, argv[1], 1); 1234 else if (!strnicmp(argv[0], MESG_STR("enable_group"))) 1235 return bypass_pg_num(m, argv[1], 0); 1236 else if (!strnicmp(argv[0], MESG_STR("switch_group"))) 1237 return switch_pg_num(m, argv[1]); 1238 else if (!strnicmp(argv[0], MESG_STR("reinstate_path"))) 1239 action = reinstate_path; 1240 else if (!strnicmp(argv[0], MESG_STR("fail_path"))) 1241 action = fail_path; 1242 else 1243 goto error; 1244 1245 r = dm_get_device(ti, argv[1], ti->begin, ti->len, 1246 dm_table_get_mode(ti->table), &dev); 1247 if (r) { 1248 DMWARN("message: error getting device %s", 1249 argv[1]); 1250 return -EINVAL; 1251 } 1252 1253 r = action_dev(m, dev, action); 1254 1255 dm_put_device(ti, dev); 1256 1257 return r; 1258 1259 error: 1260 DMWARN("Unrecognised multipath message received."); 1261 return -EINVAL; 1262 } 1263 1264 static int multipath_ioctl(struct dm_target *ti, struct inode *inode, 1265 struct file *filp, unsigned int cmd, 1266 unsigned long arg) 1267 { 1268 struct multipath *m = (struct multipath *) ti->private; 1269 struct block_device *bdev = NULL; 1270 unsigned long flags; 1271 struct file fake_file = {}; 1272 struct dentry fake_dentry = {}; 1273 int r = 0; 1274 1275 fake_file.f_dentry = &fake_dentry; 1276 1277 spin_lock_irqsave(&m->lock, flags); 1278 1279 if (!m->current_pgpath) 1280 __choose_pgpath(m); 1281 1282 if (m->current_pgpath) { 1283 bdev = m->current_pgpath->path.dev->bdev; 1284 fake_dentry.d_inode = bdev->bd_inode; 1285 fake_file.f_mode = m->current_pgpath->path.dev->mode; 1286 } 1287 1288 if (m->queue_io) 1289 r = -EAGAIN; 1290 else if (!bdev) 1291 r = -EIO; 1292 1293 spin_unlock_irqrestore(&m->lock, flags); 1294 1295 return r ? : blkdev_driver_ioctl(bdev->bd_inode, &fake_file, 1296 bdev->bd_disk, cmd, arg); 1297 } 1298 1299 /*----------------------------------------------------------------- 1300 * Module setup 1301 *---------------------------------------------------------------*/ 1302 static struct target_type multipath_target = { 1303 .name = "multipath", 1304 .version = {1, 0, 5}, 1305 .module = THIS_MODULE, 1306 .ctr = multipath_ctr, 1307 .dtr = multipath_dtr, 1308 .map = multipath_map, 1309 .end_io = multipath_end_io, 1310 .presuspend = multipath_presuspend, 1311 .resume = multipath_resume, 1312 .status = multipath_status, 1313 .message = multipath_message, 1314 .ioctl = multipath_ioctl, 1315 }; 1316 1317 static int __init dm_multipath_init(void) 1318 { 1319 int r; 1320 1321 /* allocate a slab for the dm_ios */ 1322 _mpio_cache = kmem_cache_create("dm_mpath", sizeof(struct mpath_io), 1323 0, 0, NULL, NULL); 1324 if (!_mpio_cache) 1325 return -ENOMEM; 1326 1327 r = dm_register_target(&multipath_target); 1328 if (r < 0) { 1329 DMERR("%s: register failed %d", multipath_target.name, r); 1330 kmem_cache_destroy(_mpio_cache); 1331 return -EINVAL; 1332 } 1333 1334 kmultipathd = create_workqueue("kmpathd"); 1335 if (!kmultipathd) { 1336 DMERR("%s: failed to create workqueue kmpathd", 1337 multipath_target.name); 1338 dm_unregister_target(&multipath_target); 1339 kmem_cache_destroy(_mpio_cache); 1340 return -ENOMEM; 1341 } 1342 1343 DMINFO("version %u.%u.%u loaded", 1344 multipath_target.version[0], multipath_target.version[1], 1345 multipath_target.version[2]); 1346 1347 return r; 1348 } 1349 1350 static void __exit dm_multipath_exit(void) 1351 { 1352 int r; 1353 1354 destroy_workqueue(kmultipathd); 1355 1356 r = dm_unregister_target(&multipath_target); 1357 if (r < 0) 1358 DMERR("%s: target unregister failed %d", 1359 multipath_target.name, r); 1360 kmem_cache_destroy(_mpio_cache); 1361 } 1362 1363 EXPORT_SYMBOL_GPL(dm_pg_init_complete); 1364 1365 module_init(dm_multipath_init); 1366 module_exit(dm_multipath_exit); 1367 1368 MODULE_DESCRIPTION(DM_NAME " multipath target"); 1369 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>"); 1370 MODULE_LICENSE("GPL"); 1371