1 /* 2 * Copyright (C) 2003 Sistina Software Limited. 3 * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved. 4 * 5 * This file is released under the GPL. 6 */ 7 8 #include <linux/device-mapper.h> 9 10 #include "dm-path-selector.h" 11 #include "dm-bio-list.h" 12 #include "dm-bio-record.h" 13 #include "dm-uevent.h" 14 15 #include <linux/ctype.h> 16 #include <linux/init.h> 17 #include <linux/mempool.h> 18 #include <linux/module.h> 19 #include <linux/pagemap.h> 20 #include <linux/slab.h> 21 #include <linux/time.h> 22 #include <linux/workqueue.h> 23 #include <scsi/scsi_dh.h> 24 #include <asm/atomic.h> 25 26 #define DM_MSG_PREFIX "multipath" 27 #define MESG_STR(x) x, sizeof(x) 28 29 /* Path properties */ 30 struct pgpath { 31 struct list_head list; 32 33 struct priority_group *pg; /* Owning PG */ 34 unsigned is_active; /* Path status */ 35 unsigned fail_count; /* Cumulative failure count */ 36 37 struct dm_path path; 38 struct work_struct deactivate_path; 39 }; 40 41 #define path_to_pgpath(__pgp) container_of((__pgp), struct pgpath, path) 42 43 /* 44 * Paths are grouped into Priority Groups and numbered from 1 upwards. 45 * Each has a path selector which controls which path gets used. 46 */ 47 struct priority_group { 48 struct list_head list; 49 50 struct multipath *m; /* Owning multipath instance */ 51 struct path_selector ps; 52 53 unsigned pg_num; /* Reference number */ 54 unsigned bypassed; /* Temporarily bypass this PG? */ 55 56 unsigned nr_pgpaths; /* Number of paths in PG */ 57 struct list_head pgpaths; 58 }; 59 60 /* Multipath context */ 61 struct multipath { 62 struct list_head list; 63 struct dm_target *ti; 64 65 spinlock_t lock; 66 67 const char *hw_handler_name; 68 struct work_struct activate_path; 69 struct pgpath *pgpath_to_activate; 70 unsigned nr_priority_groups; 71 struct list_head priority_groups; 72 unsigned pg_init_required; /* pg_init needs calling? */ 73 unsigned pg_init_in_progress; /* Only one pg_init allowed at once */ 74 75 unsigned nr_valid_paths; /* Total number of usable paths */ 76 struct pgpath *current_pgpath; 77 struct priority_group *current_pg; 78 struct priority_group *next_pg; /* Switch to this PG if set */ 79 unsigned repeat_count; /* I/Os left before calling PS again */ 80 81 unsigned queue_io; /* Must we queue all I/O? */ 82 unsigned queue_if_no_path; /* Queue I/O if last path fails? */ 83 unsigned saved_queue_if_no_path;/* Saved state during suspension */ 84 unsigned pg_init_retries; /* Number of times to retry pg_init */ 85 unsigned pg_init_count; /* Number of times pg_init called */ 86 87 struct work_struct process_queued_ios; 88 struct bio_list queued_ios; 89 unsigned queue_size; 90 91 struct work_struct trigger_event; 92 93 /* 94 * We must use a mempool of dm_mpath_io structs so that we 95 * can resubmit bios on error. 96 */ 97 mempool_t *mpio_pool; 98 }; 99 100 /* 101 * Context information attached to each bio we process. 102 */ 103 struct dm_mpath_io { 104 struct pgpath *pgpath; 105 struct dm_bio_details details; 106 }; 107 108 typedef int (*action_fn) (struct pgpath *pgpath); 109 110 #define MIN_IOS 256 /* Mempool size */ 111 112 static struct kmem_cache *_mpio_cache; 113 114 static struct workqueue_struct *kmultipathd, *kmpath_handlerd; 115 static void process_queued_ios(struct work_struct *work); 116 static void trigger_event(struct work_struct *work); 117 static void activate_path(struct work_struct *work); 118 static void deactivate_path(struct work_struct *work); 119 120 121 /*----------------------------------------------- 122 * Allocation routines 123 *-----------------------------------------------*/ 124 125 static struct pgpath *alloc_pgpath(void) 126 { 127 struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL); 128 129 if (pgpath) { 130 pgpath->is_active = 1; 131 INIT_WORK(&pgpath->deactivate_path, deactivate_path); 132 } 133 134 return pgpath; 135 } 136 137 static void free_pgpath(struct pgpath *pgpath) 138 { 139 kfree(pgpath); 140 } 141 142 static void deactivate_path(struct work_struct *work) 143 { 144 struct pgpath *pgpath = 145 container_of(work, struct pgpath, deactivate_path); 146 147 blk_abort_queue(pgpath->path.dev->bdev->bd_disk->queue); 148 } 149 150 static struct priority_group *alloc_priority_group(void) 151 { 152 struct priority_group *pg; 153 154 pg = kzalloc(sizeof(*pg), GFP_KERNEL); 155 156 if (pg) 157 INIT_LIST_HEAD(&pg->pgpaths); 158 159 return pg; 160 } 161 162 static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti) 163 { 164 unsigned long flags; 165 struct pgpath *pgpath, *tmp; 166 struct multipath *m = ti->private; 167 168 list_for_each_entry_safe(pgpath, tmp, pgpaths, list) { 169 list_del(&pgpath->list); 170 if (m->hw_handler_name) 171 scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev)); 172 dm_put_device(ti, pgpath->path.dev); 173 spin_lock_irqsave(&m->lock, flags); 174 if (m->pgpath_to_activate == pgpath) 175 m->pgpath_to_activate = NULL; 176 spin_unlock_irqrestore(&m->lock, flags); 177 free_pgpath(pgpath); 178 } 179 } 180 181 static void free_priority_group(struct priority_group *pg, 182 struct dm_target *ti) 183 { 184 struct path_selector *ps = &pg->ps; 185 186 if (ps->type) { 187 ps->type->destroy(ps); 188 dm_put_path_selector(ps->type); 189 } 190 191 free_pgpaths(&pg->pgpaths, ti); 192 kfree(pg); 193 } 194 195 static struct multipath *alloc_multipath(struct dm_target *ti) 196 { 197 struct multipath *m; 198 199 m = kzalloc(sizeof(*m), GFP_KERNEL); 200 if (m) { 201 INIT_LIST_HEAD(&m->priority_groups); 202 spin_lock_init(&m->lock); 203 m->queue_io = 1; 204 INIT_WORK(&m->process_queued_ios, process_queued_ios); 205 INIT_WORK(&m->trigger_event, trigger_event); 206 INIT_WORK(&m->activate_path, activate_path); 207 m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache); 208 if (!m->mpio_pool) { 209 kfree(m); 210 return NULL; 211 } 212 m->ti = ti; 213 ti->private = m; 214 } 215 216 return m; 217 } 218 219 static void free_multipath(struct multipath *m) 220 { 221 struct priority_group *pg, *tmp; 222 223 list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) { 224 list_del(&pg->list); 225 free_priority_group(pg, m->ti); 226 } 227 228 kfree(m->hw_handler_name); 229 mempool_destroy(m->mpio_pool); 230 kfree(m); 231 } 232 233 234 /*----------------------------------------------- 235 * Path selection 236 *-----------------------------------------------*/ 237 238 static void __switch_pg(struct multipath *m, struct pgpath *pgpath) 239 { 240 m->current_pg = pgpath->pg; 241 242 /* Must we initialise the PG first, and queue I/O till it's ready? */ 243 if (m->hw_handler_name) { 244 m->pg_init_required = 1; 245 m->queue_io = 1; 246 } else { 247 m->pg_init_required = 0; 248 m->queue_io = 0; 249 } 250 251 m->pg_init_count = 0; 252 } 253 254 static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg) 255 { 256 struct dm_path *path; 257 258 path = pg->ps.type->select_path(&pg->ps, &m->repeat_count); 259 if (!path) 260 return -ENXIO; 261 262 m->current_pgpath = path_to_pgpath(path); 263 264 if (m->current_pg != pg) 265 __switch_pg(m, m->current_pgpath); 266 267 return 0; 268 } 269 270 static void __choose_pgpath(struct multipath *m) 271 { 272 struct priority_group *pg; 273 unsigned bypassed = 1; 274 275 if (!m->nr_valid_paths) 276 goto failed; 277 278 /* Were we instructed to switch PG? */ 279 if (m->next_pg) { 280 pg = m->next_pg; 281 m->next_pg = NULL; 282 if (!__choose_path_in_pg(m, pg)) 283 return; 284 } 285 286 /* Don't change PG until it has no remaining paths */ 287 if (m->current_pg && !__choose_path_in_pg(m, m->current_pg)) 288 return; 289 290 /* 291 * Loop through priority groups until we find a valid path. 292 * First time we skip PGs marked 'bypassed'. 293 * Second time we only try the ones we skipped. 294 */ 295 do { 296 list_for_each_entry(pg, &m->priority_groups, list) { 297 if (pg->bypassed == bypassed) 298 continue; 299 if (!__choose_path_in_pg(m, pg)) 300 return; 301 } 302 } while (bypassed--); 303 304 failed: 305 m->current_pgpath = NULL; 306 m->current_pg = NULL; 307 } 308 309 /* 310 * Check whether bios must be queued in the device-mapper core rather 311 * than here in the target. 312 * 313 * m->lock must be held on entry. 314 * 315 * If m->queue_if_no_path and m->saved_queue_if_no_path hold the 316 * same value then we are not between multipath_presuspend() 317 * and multipath_resume() calls and we have no need to check 318 * for the DMF_NOFLUSH_SUSPENDING flag. 319 */ 320 static int __must_push_back(struct multipath *m) 321 { 322 return (m->queue_if_no_path != m->saved_queue_if_no_path && 323 dm_noflush_suspending(m->ti)); 324 } 325 326 static int map_io(struct multipath *m, struct bio *bio, 327 struct dm_mpath_io *mpio, unsigned was_queued) 328 { 329 int r = DM_MAPIO_REMAPPED; 330 unsigned long flags; 331 struct pgpath *pgpath; 332 333 spin_lock_irqsave(&m->lock, flags); 334 335 /* Do we need to select a new pgpath? */ 336 if (!m->current_pgpath || 337 (!m->queue_io && (m->repeat_count && --m->repeat_count == 0))) 338 __choose_pgpath(m); 339 340 pgpath = m->current_pgpath; 341 342 if (was_queued) 343 m->queue_size--; 344 345 if ((pgpath && m->queue_io) || 346 (!pgpath && m->queue_if_no_path)) { 347 /* Queue for the daemon to resubmit */ 348 bio_list_add(&m->queued_ios, bio); 349 m->queue_size++; 350 if ((m->pg_init_required && !m->pg_init_in_progress) || 351 !m->queue_io) 352 queue_work(kmultipathd, &m->process_queued_ios); 353 pgpath = NULL; 354 r = DM_MAPIO_SUBMITTED; 355 } else if (pgpath) 356 bio->bi_bdev = pgpath->path.dev->bdev; 357 else if (__must_push_back(m)) 358 r = DM_MAPIO_REQUEUE; 359 else 360 r = -EIO; /* Failed */ 361 362 mpio->pgpath = pgpath; 363 364 spin_unlock_irqrestore(&m->lock, flags); 365 366 return r; 367 } 368 369 /* 370 * If we run out of usable paths, should we queue I/O or error it? 371 */ 372 static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path, 373 unsigned save_old_value) 374 { 375 unsigned long flags; 376 377 spin_lock_irqsave(&m->lock, flags); 378 379 if (save_old_value) 380 m->saved_queue_if_no_path = m->queue_if_no_path; 381 else 382 m->saved_queue_if_no_path = queue_if_no_path; 383 m->queue_if_no_path = queue_if_no_path; 384 if (!m->queue_if_no_path && m->queue_size) 385 queue_work(kmultipathd, &m->process_queued_ios); 386 387 spin_unlock_irqrestore(&m->lock, flags); 388 389 return 0; 390 } 391 392 /*----------------------------------------------------------------- 393 * The multipath daemon is responsible for resubmitting queued ios. 394 *---------------------------------------------------------------*/ 395 396 static void dispatch_queued_ios(struct multipath *m) 397 { 398 int r; 399 unsigned long flags; 400 struct bio *bio = NULL, *next; 401 struct dm_mpath_io *mpio; 402 union map_info *info; 403 404 spin_lock_irqsave(&m->lock, flags); 405 bio = bio_list_get(&m->queued_ios); 406 spin_unlock_irqrestore(&m->lock, flags); 407 408 while (bio) { 409 next = bio->bi_next; 410 bio->bi_next = NULL; 411 412 info = dm_get_mapinfo(bio); 413 mpio = info->ptr; 414 415 r = map_io(m, bio, mpio, 1); 416 if (r < 0) 417 bio_endio(bio, r); 418 else if (r == DM_MAPIO_REMAPPED) 419 generic_make_request(bio); 420 else if (r == DM_MAPIO_REQUEUE) 421 bio_endio(bio, -EIO); 422 423 bio = next; 424 } 425 } 426 427 static void process_queued_ios(struct work_struct *work) 428 { 429 struct multipath *m = 430 container_of(work, struct multipath, process_queued_ios); 431 struct pgpath *pgpath = NULL; 432 unsigned init_required = 0, must_queue = 1; 433 unsigned long flags; 434 435 spin_lock_irqsave(&m->lock, flags); 436 437 if (!m->queue_size) 438 goto out; 439 440 if (!m->current_pgpath) 441 __choose_pgpath(m); 442 443 pgpath = m->current_pgpath; 444 445 if ((pgpath && !m->queue_io) || 446 (!pgpath && !m->queue_if_no_path)) 447 must_queue = 0; 448 449 if (m->pg_init_required && !m->pg_init_in_progress && pgpath) { 450 m->pgpath_to_activate = pgpath; 451 m->pg_init_count++; 452 m->pg_init_required = 0; 453 m->pg_init_in_progress = 1; 454 init_required = 1; 455 } 456 457 out: 458 spin_unlock_irqrestore(&m->lock, flags); 459 460 if (init_required) 461 queue_work(kmpath_handlerd, &m->activate_path); 462 463 if (!must_queue) 464 dispatch_queued_ios(m); 465 } 466 467 /* 468 * An event is triggered whenever a path is taken out of use. 469 * Includes path failure and PG bypass. 470 */ 471 static void trigger_event(struct work_struct *work) 472 { 473 struct multipath *m = 474 container_of(work, struct multipath, trigger_event); 475 476 dm_table_event(m->ti->table); 477 } 478 479 /*----------------------------------------------------------------- 480 * Constructor/argument parsing: 481 * <#multipath feature args> [<arg>]* 482 * <#hw_handler args> [hw_handler [<arg>]*] 483 * <#priority groups> 484 * <initial priority group> 485 * [<selector> <#selector args> [<arg>]* 486 * <#paths> <#per-path selector args> 487 * [<path> [<arg>]* ]+ ]+ 488 *---------------------------------------------------------------*/ 489 struct param { 490 unsigned min; 491 unsigned max; 492 char *error; 493 }; 494 495 static int read_param(struct param *param, char *str, unsigned *v, char **error) 496 { 497 if (!str || 498 (sscanf(str, "%u", v) != 1) || 499 (*v < param->min) || 500 (*v > param->max)) { 501 *error = param->error; 502 return -EINVAL; 503 } 504 505 return 0; 506 } 507 508 struct arg_set { 509 unsigned argc; 510 char **argv; 511 }; 512 513 static char *shift(struct arg_set *as) 514 { 515 char *r; 516 517 if (as->argc) { 518 as->argc--; 519 r = *as->argv; 520 as->argv++; 521 return r; 522 } 523 524 return NULL; 525 } 526 527 static void consume(struct arg_set *as, unsigned n) 528 { 529 BUG_ON (as->argc < n); 530 as->argc -= n; 531 as->argv += n; 532 } 533 534 static int parse_path_selector(struct arg_set *as, struct priority_group *pg, 535 struct dm_target *ti) 536 { 537 int r; 538 struct path_selector_type *pst; 539 unsigned ps_argc; 540 541 static struct param _params[] = { 542 {0, 1024, "invalid number of path selector args"}, 543 }; 544 545 pst = dm_get_path_selector(shift(as)); 546 if (!pst) { 547 ti->error = "unknown path selector type"; 548 return -EINVAL; 549 } 550 551 r = read_param(_params, shift(as), &ps_argc, &ti->error); 552 if (r) { 553 dm_put_path_selector(pst); 554 return -EINVAL; 555 } 556 557 r = pst->create(&pg->ps, ps_argc, as->argv); 558 if (r) { 559 dm_put_path_selector(pst); 560 ti->error = "path selector constructor failed"; 561 return r; 562 } 563 564 pg->ps.type = pst; 565 consume(as, ps_argc); 566 567 return 0; 568 } 569 570 static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps, 571 struct dm_target *ti) 572 { 573 int r; 574 struct pgpath *p; 575 struct multipath *m = ti->private; 576 577 /* we need at least a path arg */ 578 if (as->argc < 1) { 579 ti->error = "no device given"; 580 return ERR_PTR(-EINVAL); 581 } 582 583 p = alloc_pgpath(); 584 if (!p) 585 return ERR_PTR(-ENOMEM); 586 587 r = dm_get_device(ti, shift(as), ti->begin, ti->len, 588 dm_table_get_mode(ti->table), &p->path.dev); 589 if (r) { 590 ti->error = "error getting device"; 591 goto bad; 592 } 593 594 if (m->hw_handler_name) { 595 r = scsi_dh_attach(bdev_get_queue(p->path.dev->bdev), 596 m->hw_handler_name); 597 if (r < 0) { 598 dm_put_device(ti, p->path.dev); 599 goto bad; 600 } 601 } 602 603 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error); 604 if (r) { 605 dm_put_device(ti, p->path.dev); 606 goto bad; 607 } 608 609 return p; 610 611 bad: 612 free_pgpath(p); 613 return ERR_PTR(r); 614 } 615 616 static struct priority_group *parse_priority_group(struct arg_set *as, 617 struct multipath *m) 618 { 619 static struct param _params[] = { 620 {1, 1024, "invalid number of paths"}, 621 {0, 1024, "invalid number of selector args"} 622 }; 623 624 int r; 625 unsigned i, nr_selector_args, nr_params; 626 struct priority_group *pg; 627 struct dm_target *ti = m->ti; 628 629 if (as->argc < 2) { 630 as->argc = 0; 631 ti->error = "not enough priority group arguments"; 632 return ERR_PTR(-EINVAL); 633 } 634 635 pg = alloc_priority_group(); 636 if (!pg) { 637 ti->error = "couldn't allocate priority group"; 638 return ERR_PTR(-ENOMEM); 639 } 640 pg->m = m; 641 642 r = parse_path_selector(as, pg, ti); 643 if (r) 644 goto bad; 645 646 /* 647 * read the paths 648 */ 649 r = read_param(_params, shift(as), &pg->nr_pgpaths, &ti->error); 650 if (r) 651 goto bad; 652 653 r = read_param(_params + 1, shift(as), &nr_selector_args, &ti->error); 654 if (r) 655 goto bad; 656 657 nr_params = 1 + nr_selector_args; 658 for (i = 0; i < pg->nr_pgpaths; i++) { 659 struct pgpath *pgpath; 660 struct arg_set path_args; 661 662 if (as->argc < nr_params) { 663 ti->error = "not enough path parameters"; 664 goto bad; 665 } 666 667 path_args.argc = nr_params; 668 path_args.argv = as->argv; 669 670 pgpath = parse_path(&path_args, &pg->ps, ti); 671 if (IS_ERR(pgpath)) { 672 r = PTR_ERR(pgpath); 673 goto bad; 674 } 675 676 pgpath->pg = pg; 677 list_add_tail(&pgpath->list, &pg->pgpaths); 678 consume(as, nr_params); 679 } 680 681 return pg; 682 683 bad: 684 free_priority_group(pg, ti); 685 return ERR_PTR(r); 686 } 687 688 static int parse_hw_handler(struct arg_set *as, struct multipath *m) 689 { 690 unsigned hw_argc; 691 struct dm_target *ti = m->ti; 692 693 static struct param _params[] = { 694 {0, 1024, "invalid number of hardware handler args"}, 695 }; 696 697 if (read_param(_params, shift(as), &hw_argc, &ti->error)) 698 return -EINVAL; 699 700 if (!hw_argc) 701 return 0; 702 703 m->hw_handler_name = kstrdup(shift(as), GFP_KERNEL); 704 request_module("scsi_dh_%s", m->hw_handler_name); 705 if (scsi_dh_handler_exist(m->hw_handler_name) == 0) { 706 ti->error = "unknown hardware handler type"; 707 kfree(m->hw_handler_name); 708 m->hw_handler_name = NULL; 709 return -EINVAL; 710 } 711 712 if (hw_argc > 1) 713 DMWARN("Ignoring user-specified arguments for " 714 "hardware handler \"%s\"", m->hw_handler_name); 715 consume(as, hw_argc - 1); 716 717 return 0; 718 } 719 720 static int parse_features(struct arg_set *as, struct multipath *m) 721 { 722 int r; 723 unsigned argc; 724 struct dm_target *ti = m->ti; 725 const char *param_name; 726 727 static struct param _params[] = { 728 {0, 3, "invalid number of feature args"}, 729 {1, 50, "pg_init_retries must be between 1 and 50"}, 730 }; 731 732 r = read_param(_params, shift(as), &argc, &ti->error); 733 if (r) 734 return -EINVAL; 735 736 if (!argc) 737 return 0; 738 739 do { 740 param_name = shift(as); 741 argc--; 742 743 if (!strnicmp(param_name, MESG_STR("queue_if_no_path"))) { 744 r = queue_if_no_path(m, 1, 0); 745 continue; 746 } 747 748 if (!strnicmp(param_name, MESG_STR("pg_init_retries")) && 749 (argc >= 1)) { 750 r = read_param(_params + 1, shift(as), 751 &m->pg_init_retries, &ti->error); 752 argc--; 753 continue; 754 } 755 756 ti->error = "Unrecognised multipath feature request"; 757 r = -EINVAL; 758 } while (argc && !r); 759 760 return r; 761 } 762 763 static int multipath_ctr(struct dm_target *ti, unsigned int argc, 764 char **argv) 765 { 766 /* target parameters */ 767 static struct param _params[] = { 768 {1, 1024, "invalid number of priority groups"}, 769 {1, 1024, "invalid initial priority group number"}, 770 }; 771 772 int r; 773 struct multipath *m; 774 struct arg_set as; 775 unsigned pg_count = 0; 776 unsigned next_pg_num; 777 778 as.argc = argc; 779 as.argv = argv; 780 781 m = alloc_multipath(ti); 782 if (!m) { 783 ti->error = "can't allocate multipath"; 784 return -EINVAL; 785 } 786 787 r = parse_features(&as, m); 788 if (r) 789 goto bad; 790 791 r = parse_hw_handler(&as, m); 792 if (r) 793 goto bad; 794 795 r = read_param(_params, shift(&as), &m->nr_priority_groups, &ti->error); 796 if (r) 797 goto bad; 798 799 r = read_param(_params + 1, shift(&as), &next_pg_num, &ti->error); 800 if (r) 801 goto bad; 802 803 /* parse the priority groups */ 804 while (as.argc) { 805 struct priority_group *pg; 806 807 pg = parse_priority_group(&as, m); 808 if (IS_ERR(pg)) { 809 r = PTR_ERR(pg); 810 goto bad; 811 } 812 813 m->nr_valid_paths += pg->nr_pgpaths; 814 list_add_tail(&pg->list, &m->priority_groups); 815 pg_count++; 816 pg->pg_num = pg_count; 817 if (!--next_pg_num) 818 m->next_pg = pg; 819 } 820 821 if (pg_count != m->nr_priority_groups) { 822 ti->error = "priority group count mismatch"; 823 r = -EINVAL; 824 goto bad; 825 } 826 827 return 0; 828 829 bad: 830 free_multipath(m); 831 return r; 832 } 833 834 static void multipath_dtr(struct dm_target *ti) 835 { 836 struct multipath *m = (struct multipath *) ti->private; 837 838 flush_workqueue(kmpath_handlerd); 839 flush_workqueue(kmultipathd); 840 free_multipath(m); 841 } 842 843 /* 844 * Map bios, recording original fields for later in case we have to resubmit 845 */ 846 static int multipath_map(struct dm_target *ti, struct bio *bio, 847 union map_info *map_context) 848 { 849 int r; 850 struct dm_mpath_io *mpio; 851 struct multipath *m = (struct multipath *) ti->private; 852 853 mpio = mempool_alloc(m->mpio_pool, GFP_NOIO); 854 dm_bio_record(&mpio->details, bio); 855 856 map_context->ptr = mpio; 857 bio->bi_rw |= (1 << BIO_RW_FAILFAST_TRANSPORT); 858 r = map_io(m, bio, mpio, 0); 859 if (r < 0 || r == DM_MAPIO_REQUEUE) 860 mempool_free(mpio, m->mpio_pool); 861 862 return r; 863 } 864 865 /* 866 * Take a path out of use. 867 */ 868 static int fail_path(struct pgpath *pgpath) 869 { 870 unsigned long flags; 871 struct multipath *m = pgpath->pg->m; 872 873 spin_lock_irqsave(&m->lock, flags); 874 875 if (!pgpath->is_active) 876 goto out; 877 878 DMWARN("Failing path %s.", pgpath->path.dev->name); 879 880 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path); 881 pgpath->is_active = 0; 882 pgpath->fail_count++; 883 884 m->nr_valid_paths--; 885 886 if (pgpath == m->current_pgpath) 887 m->current_pgpath = NULL; 888 889 dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti, 890 pgpath->path.dev->name, m->nr_valid_paths); 891 892 schedule_work(&m->trigger_event); 893 queue_work(kmultipathd, &pgpath->deactivate_path); 894 895 out: 896 spin_unlock_irqrestore(&m->lock, flags); 897 898 return 0; 899 } 900 901 /* 902 * Reinstate a previously-failed path 903 */ 904 static int reinstate_path(struct pgpath *pgpath) 905 { 906 int r = 0; 907 unsigned long flags; 908 struct multipath *m = pgpath->pg->m; 909 910 spin_lock_irqsave(&m->lock, flags); 911 912 if (pgpath->is_active) 913 goto out; 914 915 if (!pgpath->pg->ps.type->reinstate_path) { 916 DMWARN("Reinstate path not supported by path selector %s", 917 pgpath->pg->ps.type->name); 918 r = -EINVAL; 919 goto out; 920 } 921 922 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path); 923 if (r) 924 goto out; 925 926 pgpath->is_active = 1; 927 928 m->current_pgpath = NULL; 929 if (!m->nr_valid_paths++ && m->queue_size) 930 queue_work(kmultipathd, &m->process_queued_ios); 931 932 dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti, 933 pgpath->path.dev->name, m->nr_valid_paths); 934 935 schedule_work(&m->trigger_event); 936 937 out: 938 spin_unlock_irqrestore(&m->lock, flags); 939 940 return r; 941 } 942 943 /* 944 * Fail or reinstate all paths that match the provided struct dm_dev. 945 */ 946 static int action_dev(struct multipath *m, struct dm_dev *dev, 947 action_fn action) 948 { 949 int r = 0; 950 struct pgpath *pgpath; 951 struct priority_group *pg; 952 953 list_for_each_entry(pg, &m->priority_groups, list) { 954 list_for_each_entry(pgpath, &pg->pgpaths, list) { 955 if (pgpath->path.dev == dev) 956 r = action(pgpath); 957 } 958 } 959 960 return r; 961 } 962 963 /* 964 * Temporarily try to avoid having to use the specified PG 965 */ 966 static void bypass_pg(struct multipath *m, struct priority_group *pg, 967 int bypassed) 968 { 969 unsigned long flags; 970 971 spin_lock_irqsave(&m->lock, flags); 972 973 pg->bypassed = bypassed; 974 m->current_pgpath = NULL; 975 m->current_pg = NULL; 976 977 spin_unlock_irqrestore(&m->lock, flags); 978 979 schedule_work(&m->trigger_event); 980 } 981 982 /* 983 * Switch to using the specified PG from the next I/O that gets mapped 984 */ 985 static int switch_pg_num(struct multipath *m, const char *pgstr) 986 { 987 struct priority_group *pg; 988 unsigned pgnum; 989 unsigned long flags; 990 991 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum || 992 (pgnum > m->nr_priority_groups)) { 993 DMWARN("invalid PG number supplied to switch_pg_num"); 994 return -EINVAL; 995 } 996 997 spin_lock_irqsave(&m->lock, flags); 998 list_for_each_entry(pg, &m->priority_groups, list) { 999 pg->bypassed = 0; 1000 if (--pgnum) 1001 continue; 1002 1003 m->current_pgpath = NULL; 1004 m->current_pg = NULL; 1005 m->next_pg = pg; 1006 } 1007 spin_unlock_irqrestore(&m->lock, flags); 1008 1009 schedule_work(&m->trigger_event); 1010 return 0; 1011 } 1012 1013 /* 1014 * Set/clear bypassed status of a PG. 1015 * PGs are numbered upwards from 1 in the order they were declared. 1016 */ 1017 static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed) 1018 { 1019 struct priority_group *pg; 1020 unsigned pgnum; 1021 1022 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum || 1023 (pgnum > m->nr_priority_groups)) { 1024 DMWARN("invalid PG number supplied to bypass_pg"); 1025 return -EINVAL; 1026 } 1027 1028 list_for_each_entry(pg, &m->priority_groups, list) { 1029 if (!--pgnum) 1030 break; 1031 } 1032 1033 bypass_pg(m, pg, bypassed); 1034 return 0; 1035 } 1036 1037 /* 1038 * Should we retry pg_init immediately? 1039 */ 1040 static int pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath) 1041 { 1042 unsigned long flags; 1043 int limit_reached = 0; 1044 1045 spin_lock_irqsave(&m->lock, flags); 1046 1047 if (m->pg_init_count <= m->pg_init_retries) 1048 m->pg_init_required = 1; 1049 else 1050 limit_reached = 1; 1051 1052 spin_unlock_irqrestore(&m->lock, flags); 1053 1054 return limit_reached; 1055 } 1056 1057 static void pg_init_done(struct dm_path *path, int errors) 1058 { 1059 struct pgpath *pgpath = path_to_pgpath(path); 1060 struct priority_group *pg = pgpath->pg; 1061 struct multipath *m = pg->m; 1062 unsigned long flags; 1063 1064 /* device or driver problems */ 1065 switch (errors) { 1066 case SCSI_DH_OK: 1067 break; 1068 case SCSI_DH_NOSYS: 1069 if (!m->hw_handler_name) { 1070 errors = 0; 1071 break; 1072 } 1073 DMERR("Cannot failover device because scsi_dh_%s was not " 1074 "loaded.", m->hw_handler_name); 1075 /* 1076 * Fail path for now, so we do not ping pong 1077 */ 1078 fail_path(pgpath); 1079 break; 1080 case SCSI_DH_DEV_TEMP_BUSY: 1081 /* 1082 * Probably doing something like FW upgrade on the 1083 * controller so try the other pg. 1084 */ 1085 bypass_pg(m, pg, 1); 1086 break; 1087 /* TODO: For SCSI_DH_RETRY we should wait a couple seconds */ 1088 case SCSI_DH_RETRY: 1089 case SCSI_DH_IMM_RETRY: 1090 case SCSI_DH_RES_TEMP_UNAVAIL: 1091 if (pg_init_limit_reached(m, pgpath)) 1092 fail_path(pgpath); 1093 errors = 0; 1094 break; 1095 default: 1096 /* 1097 * We probably do not want to fail the path for a device 1098 * error, but this is what the old dm did. In future 1099 * patches we can do more advanced handling. 1100 */ 1101 fail_path(pgpath); 1102 } 1103 1104 spin_lock_irqsave(&m->lock, flags); 1105 if (errors) { 1106 DMERR("Could not failover device. Error %d.", errors); 1107 m->current_pgpath = NULL; 1108 m->current_pg = NULL; 1109 } else if (!m->pg_init_required) { 1110 m->queue_io = 0; 1111 pg->bypassed = 0; 1112 } 1113 1114 m->pg_init_in_progress = 0; 1115 queue_work(kmultipathd, &m->process_queued_ios); 1116 spin_unlock_irqrestore(&m->lock, flags); 1117 } 1118 1119 static void activate_path(struct work_struct *work) 1120 { 1121 int ret; 1122 struct multipath *m = 1123 container_of(work, struct multipath, activate_path); 1124 struct dm_path *path; 1125 unsigned long flags; 1126 1127 spin_lock_irqsave(&m->lock, flags); 1128 path = &m->pgpath_to_activate->path; 1129 m->pgpath_to_activate = NULL; 1130 spin_unlock_irqrestore(&m->lock, flags); 1131 if (!path) 1132 return; 1133 ret = scsi_dh_activate(bdev_get_queue(path->dev->bdev)); 1134 pg_init_done(path, ret); 1135 } 1136 1137 /* 1138 * end_io handling 1139 */ 1140 static int do_end_io(struct multipath *m, struct bio *bio, 1141 int error, struct dm_mpath_io *mpio) 1142 { 1143 unsigned long flags; 1144 1145 if (!error) 1146 return 0; /* I/O complete */ 1147 1148 if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio)) 1149 return error; 1150 1151 if (error == -EOPNOTSUPP) 1152 return error; 1153 1154 spin_lock_irqsave(&m->lock, flags); 1155 if (!m->nr_valid_paths) { 1156 if (__must_push_back(m)) { 1157 spin_unlock_irqrestore(&m->lock, flags); 1158 return DM_ENDIO_REQUEUE; 1159 } else if (!m->queue_if_no_path) { 1160 spin_unlock_irqrestore(&m->lock, flags); 1161 return -EIO; 1162 } else { 1163 spin_unlock_irqrestore(&m->lock, flags); 1164 goto requeue; 1165 } 1166 } 1167 spin_unlock_irqrestore(&m->lock, flags); 1168 1169 if (mpio->pgpath) 1170 fail_path(mpio->pgpath); 1171 1172 requeue: 1173 dm_bio_restore(&mpio->details, bio); 1174 1175 /* queue for the daemon to resubmit or fail */ 1176 spin_lock_irqsave(&m->lock, flags); 1177 bio_list_add(&m->queued_ios, bio); 1178 m->queue_size++; 1179 if (!m->queue_io) 1180 queue_work(kmultipathd, &m->process_queued_ios); 1181 spin_unlock_irqrestore(&m->lock, flags); 1182 1183 return DM_ENDIO_INCOMPLETE; /* io not complete */ 1184 } 1185 1186 static int multipath_end_io(struct dm_target *ti, struct bio *bio, 1187 int error, union map_info *map_context) 1188 { 1189 struct multipath *m = ti->private; 1190 struct dm_mpath_io *mpio = map_context->ptr; 1191 struct pgpath *pgpath = mpio->pgpath; 1192 struct path_selector *ps; 1193 int r; 1194 1195 r = do_end_io(m, bio, error, mpio); 1196 if (pgpath) { 1197 ps = &pgpath->pg->ps; 1198 if (ps->type->end_io) 1199 ps->type->end_io(ps, &pgpath->path); 1200 } 1201 if (r != DM_ENDIO_INCOMPLETE) 1202 mempool_free(mpio, m->mpio_pool); 1203 1204 return r; 1205 } 1206 1207 /* 1208 * Suspend can't complete until all the I/O is processed so if 1209 * the last path fails we must error any remaining I/O. 1210 * Note that if the freeze_bdev fails while suspending, the 1211 * queue_if_no_path state is lost - userspace should reset it. 1212 */ 1213 static void multipath_presuspend(struct dm_target *ti) 1214 { 1215 struct multipath *m = (struct multipath *) ti->private; 1216 1217 queue_if_no_path(m, 0, 1); 1218 } 1219 1220 /* 1221 * Restore the queue_if_no_path setting. 1222 */ 1223 static void multipath_resume(struct dm_target *ti) 1224 { 1225 struct multipath *m = (struct multipath *) ti->private; 1226 unsigned long flags; 1227 1228 spin_lock_irqsave(&m->lock, flags); 1229 m->queue_if_no_path = m->saved_queue_if_no_path; 1230 spin_unlock_irqrestore(&m->lock, flags); 1231 } 1232 1233 /* 1234 * Info output has the following format: 1235 * num_multipath_feature_args [multipath_feature_args]* 1236 * num_handler_status_args [handler_status_args]* 1237 * num_groups init_group_number 1238 * [A|D|E num_ps_status_args [ps_status_args]* 1239 * num_paths num_selector_args 1240 * [path_dev A|F fail_count [selector_args]* ]+ ]+ 1241 * 1242 * Table output has the following format (identical to the constructor string): 1243 * num_feature_args [features_args]* 1244 * num_handler_args hw_handler [hw_handler_args]* 1245 * num_groups init_group_number 1246 * [priority selector-name num_ps_args [ps_args]* 1247 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+ 1248 */ 1249 static int multipath_status(struct dm_target *ti, status_type_t type, 1250 char *result, unsigned int maxlen) 1251 { 1252 int sz = 0; 1253 unsigned long flags; 1254 struct multipath *m = (struct multipath *) ti->private; 1255 struct priority_group *pg; 1256 struct pgpath *p; 1257 unsigned pg_num; 1258 char state; 1259 1260 spin_lock_irqsave(&m->lock, flags); 1261 1262 /* Features */ 1263 if (type == STATUSTYPE_INFO) 1264 DMEMIT("2 %u %u ", m->queue_size, m->pg_init_count); 1265 else { 1266 DMEMIT("%u ", m->queue_if_no_path + 1267 (m->pg_init_retries > 0) * 2); 1268 if (m->queue_if_no_path) 1269 DMEMIT("queue_if_no_path "); 1270 if (m->pg_init_retries) 1271 DMEMIT("pg_init_retries %u ", m->pg_init_retries); 1272 } 1273 1274 if (!m->hw_handler_name || type == STATUSTYPE_INFO) 1275 DMEMIT("0 "); 1276 else 1277 DMEMIT("1 %s ", m->hw_handler_name); 1278 1279 DMEMIT("%u ", m->nr_priority_groups); 1280 1281 if (m->next_pg) 1282 pg_num = m->next_pg->pg_num; 1283 else if (m->current_pg) 1284 pg_num = m->current_pg->pg_num; 1285 else 1286 pg_num = 1; 1287 1288 DMEMIT("%u ", pg_num); 1289 1290 switch (type) { 1291 case STATUSTYPE_INFO: 1292 list_for_each_entry(pg, &m->priority_groups, list) { 1293 if (pg->bypassed) 1294 state = 'D'; /* Disabled */ 1295 else if (pg == m->current_pg) 1296 state = 'A'; /* Currently Active */ 1297 else 1298 state = 'E'; /* Enabled */ 1299 1300 DMEMIT("%c ", state); 1301 1302 if (pg->ps.type->status) 1303 sz += pg->ps.type->status(&pg->ps, NULL, type, 1304 result + sz, 1305 maxlen - sz); 1306 else 1307 DMEMIT("0 "); 1308 1309 DMEMIT("%u %u ", pg->nr_pgpaths, 1310 pg->ps.type->info_args); 1311 1312 list_for_each_entry(p, &pg->pgpaths, list) { 1313 DMEMIT("%s %s %u ", p->path.dev->name, 1314 p->is_active ? "A" : "F", 1315 p->fail_count); 1316 if (pg->ps.type->status) 1317 sz += pg->ps.type->status(&pg->ps, 1318 &p->path, type, result + sz, 1319 maxlen - sz); 1320 } 1321 } 1322 break; 1323 1324 case STATUSTYPE_TABLE: 1325 list_for_each_entry(pg, &m->priority_groups, list) { 1326 DMEMIT("%s ", pg->ps.type->name); 1327 1328 if (pg->ps.type->status) 1329 sz += pg->ps.type->status(&pg->ps, NULL, type, 1330 result + sz, 1331 maxlen - sz); 1332 else 1333 DMEMIT("0 "); 1334 1335 DMEMIT("%u %u ", pg->nr_pgpaths, 1336 pg->ps.type->table_args); 1337 1338 list_for_each_entry(p, &pg->pgpaths, list) { 1339 DMEMIT("%s ", p->path.dev->name); 1340 if (pg->ps.type->status) 1341 sz += pg->ps.type->status(&pg->ps, 1342 &p->path, type, result + sz, 1343 maxlen - sz); 1344 } 1345 } 1346 break; 1347 } 1348 1349 spin_unlock_irqrestore(&m->lock, flags); 1350 1351 return 0; 1352 } 1353 1354 static int multipath_message(struct dm_target *ti, unsigned argc, char **argv) 1355 { 1356 int r; 1357 struct dm_dev *dev; 1358 struct multipath *m = (struct multipath *) ti->private; 1359 action_fn action; 1360 1361 if (argc == 1) { 1362 if (!strnicmp(argv[0], MESG_STR("queue_if_no_path"))) 1363 return queue_if_no_path(m, 1, 0); 1364 else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path"))) 1365 return queue_if_no_path(m, 0, 0); 1366 } 1367 1368 if (argc != 2) 1369 goto error; 1370 1371 if (!strnicmp(argv[0], MESG_STR("disable_group"))) 1372 return bypass_pg_num(m, argv[1], 1); 1373 else if (!strnicmp(argv[0], MESG_STR("enable_group"))) 1374 return bypass_pg_num(m, argv[1], 0); 1375 else if (!strnicmp(argv[0], MESG_STR("switch_group"))) 1376 return switch_pg_num(m, argv[1]); 1377 else if (!strnicmp(argv[0], MESG_STR("reinstate_path"))) 1378 action = reinstate_path; 1379 else if (!strnicmp(argv[0], MESG_STR("fail_path"))) 1380 action = fail_path; 1381 else 1382 goto error; 1383 1384 r = dm_get_device(ti, argv[1], ti->begin, ti->len, 1385 dm_table_get_mode(ti->table), &dev); 1386 if (r) { 1387 DMWARN("message: error getting device %s", 1388 argv[1]); 1389 return -EINVAL; 1390 } 1391 1392 r = action_dev(m, dev, action); 1393 1394 dm_put_device(ti, dev); 1395 1396 return r; 1397 1398 error: 1399 DMWARN("Unrecognised multipath message received."); 1400 return -EINVAL; 1401 } 1402 1403 static int multipath_ioctl(struct dm_target *ti, unsigned int cmd, 1404 unsigned long arg) 1405 { 1406 struct multipath *m = (struct multipath *) ti->private; 1407 struct block_device *bdev = NULL; 1408 fmode_t mode = 0; 1409 unsigned long flags; 1410 int r = 0; 1411 1412 spin_lock_irqsave(&m->lock, flags); 1413 1414 if (!m->current_pgpath) 1415 __choose_pgpath(m); 1416 1417 if (m->current_pgpath) { 1418 bdev = m->current_pgpath->path.dev->bdev; 1419 mode = m->current_pgpath->path.dev->mode; 1420 } 1421 1422 if (m->queue_io) 1423 r = -EAGAIN; 1424 else if (!bdev) 1425 r = -EIO; 1426 1427 spin_unlock_irqrestore(&m->lock, flags); 1428 1429 return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg); 1430 } 1431 1432 /*----------------------------------------------------------------- 1433 * Module setup 1434 *---------------------------------------------------------------*/ 1435 static struct target_type multipath_target = { 1436 .name = "multipath", 1437 .version = {1, 0, 5}, 1438 .module = THIS_MODULE, 1439 .ctr = multipath_ctr, 1440 .dtr = multipath_dtr, 1441 .map = multipath_map, 1442 .end_io = multipath_end_io, 1443 .presuspend = multipath_presuspend, 1444 .resume = multipath_resume, 1445 .status = multipath_status, 1446 .message = multipath_message, 1447 .ioctl = multipath_ioctl, 1448 }; 1449 1450 static int __init dm_multipath_init(void) 1451 { 1452 int r; 1453 1454 /* allocate a slab for the dm_ios */ 1455 _mpio_cache = KMEM_CACHE(dm_mpath_io, 0); 1456 if (!_mpio_cache) 1457 return -ENOMEM; 1458 1459 r = dm_register_target(&multipath_target); 1460 if (r < 0) { 1461 DMERR("register failed %d", r); 1462 kmem_cache_destroy(_mpio_cache); 1463 return -EINVAL; 1464 } 1465 1466 kmultipathd = create_workqueue("kmpathd"); 1467 if (!kmultipathd) { 1468 DMERR("failed to create workqueue kmpathd"); 1469 dm_unregister_target(&multipath_target); 1470 kmem_cache_destroy(_mpio_cache); 1471 return -ENOMEM; 1472 } 1473 1474 /* 1475 * A separate workqueue is used to handle the device handlers 1476 * to avoid overloading existing workqueue. Overloading the 1477 * old workqueue would also create a bottleneck in the 1478 * path of the storage hardware device activation. 1479 */ 1480 kmpath_handlerd = create_singlethread_workqueue("kmpath_handlerd"); 1481 if (!kmpath_handlerd) { 1482 DMERR("failed to create workqueue kmpath_handlerd"); 1483 destroy_workqueue(kmultipathd); 1484 dm_unregister_target(&multipath_target); 1485 kmem_cache_destroy(_mpio_cache); 1486 return -ENOMEM; 1487 } 1488 1489 DMINFO("version %u.%u.%u loaded", 1490 multipath_target.version[0], multipath_target.version[1], 1491 multipath_target.version[2]); 1492 1493 return r; 1494 } 1495 1496 static void __exit dm_multipath_exit(void) 1497 { 1498 destroy_workqueue(kmpath_handlerd); 1499 destroy_workqueue(kmultipathd); 1500 1501 dm_unregister_target(&multipath_target); 1502 kmem_cache_destroy(_mpio_cache); 1503 } 1504 1505 module_init(dm_multipath_init); 1506 module_exit(dm_multipath_exit); 1507 1508 MODULE_DESCRIPTION(DM_NAME " multipath target"); 1509 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>"); 1510 MODULE_LICENSE("GPL"); 1511