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 */ 28struct 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 */ 43struct 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 */ 57struct 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 */ 95struct mpath_io { 96 struct pgpath *pgpath; 97 struct dm_bio_details details; 98}; 99 100typedef int (*action_fn) (struct pgpath *pgpath); 101 102#define MIN_IOS 256 /* Mempool size */ 103 104static struct kmem_cache *_mpio_cache; 105 106struct workqueue_struct *kmultipathd; 107static void process_queued_ios(struct work_struct *work); 108static void trigger_event(struct work_struct *work); 109 110 111/*----------------------------------------------- 112 * Allocation routines 113 *-----------------------------------------------*/ 114 115static 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 125static inline void free_pgpath(struct pgpath *pgpath) 126{ 127 kfree(pgpath); 128} 129 130static 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 142static 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 153static 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 167static 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 190static 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 214static 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 230static 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 246static 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 280failed: 281 m->current_pgpath = NULL; 282 m->current_pg = NULL; 283} 284 285/* 286 * Check whether bios must be queued in the device-mapper core rather 287 * than here in the target. 288 * 289 * m->lock must be held on entry. 290 * 291 * If m->queue_if_no_path and m->saved_queue_if_no_path hold the 292 * same value then we are not between multipath_presuspend() 293 * and multipath_resume() calls and we have no need to check 294 * for the DMF_NOFLUSH_SUSPENDING flag. 295 */ 296static int __must_push_back(struct multipath *m) 297{ 298 return (m->queue_if_no_path != m->saved_queue_if_no_path && 299 dm_noflush_suspending(m->ti)); 300} 301 302static int map_io(struct multipath *m, struct bio *bio, struct mpath_io *mpio, 303 unsigned was_queued) 304{ 305 int r = DM_MAPIO_REMAPPED; 306 unsigned long flags; 307 struct pgpath *pgpath; 308 309 spin_lock_irqsave(&m->lock, flags); 310 311 /* Do we need to select a new pgpath? */ 312 if (!m->current_pgpath || 313 (!m->queue_io && (m->repeat_count && --m->repeat_count == 0))) 314 __choose_pgpath(m); 315 316 pgpath = m->current_pgpath; 317 318 if (was_queued) 319 m->queue_size--; 320 321 if ((pgpath && m->queue_io) || 322 (!pgpath && m->queue_if_no_path)) { 323 /* Queue for the daemon to resubmit */ 324 bio_list_add(&m->queued_ios, bio); 325 m->queue_size++; 326 if ((m->pg_init_required && !m->pg_init_in_progress) || 327 !m->queue_io) 328 queue_work(kmultipathd, &m->process_queued_ios); 329 pgpath = NULL; 330 r = DM_MAPIO_SUBMITTED; 331 } else if (pgpath) 332 bio->bi_bdev = pgpath->path.dev->bdev; 333 else if (__must_push_back(m)) 334 r = DM_MAPIO_REQUEUE; 335 else 336 r = -EIO; /* Failed */ 337 338 mpio->pgpath = pgpath; 339 340 spin_unlock_irqrestore(&m->lock, flags); 341 342 return r; 343} 344 345/* 346 * If we run out of usable paths, should we queue I/O or error it? 347 */ 348static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path, 349 unsigned save_old_value) 350{ 351 unsigned long flags; 352 353 spin_lock_irqsave(&m->lock, flags); 354 355 if (save_old_value) 356 m->saved_queue_if_no_path = m->queue_if_no_path; 357 else 358 m->saved_queue_if_no_path = queue_if_no_path; 359 m->queue_if_no_path = queue_if_no_path; 360 if (!m->queue_if_no_path && m->queue_size) 361 queue_work(kmultipathd, &m->process_queued_ios); 362 363 spin_unlock_irqrestore(&m->lock, flags); 364 365 return 0; 366} 367 368/*----------------------------------------------------------------- 369 * The multipath daemon is responsible for resubmitting queued ios. 370 *---------------------------------------------------------------*/ 371 372static void dispatch_queued_ios(struct multipath *m) 373{ 374 int r; 375 unsigned long flags; 376 struct bio *bio = NULL, *next; 377 struct mpath_io *mpio; 378 union map_info *info; 379 380 spin_lock_irqsave(&m->lock, flags); 381 bio = bio_list_get(&m->queued_ios); 382 spin_unlock_irqrestore(&m->lock, flags); 383 384 while (bio) { 385 next = bio->bi_next; 386 bio->bi_next = NULL; 387 388 info = dm_get_mapinfo(bio); 389 mpio = info->ptr; 390 391 r = map_io(m, bio, mpio, 1); 392 if (r < 0) 393 bio_endio(bio, bio->bi_size, r); 394 else if (r == DM_MAPIO_REMAPPED) 395 generic_make_request(bio); 396 else if (r == DM_MAPIO_REQUEUE) 397 bio_endio(bio, bio->bi_size, -EIO); 398 399 bio = next; 400 } 401} 402 403static void process_queued_ios(struct work_struct *work) 404{ 405 struct multipath *m = 406 container_of(work, struct multipath, process_queued_ios); 407 struct hw_handler *hwh = &m->hw_handler; 408 struct pgpath *pgpath = NULL; 409 unsigned init_required = 0, must_queue = 1; 410 unsigned long flags; 411 412 spin_lock_irqsave(&m->lock, flags); 413 414 if (!m->queue_size) 415 goto out; 416 417 if (!m->current_pgpath) 418 __choose_pgpath(m); 419 420 pgpath = m->current_pgpath; 421 422 if ((pgpath && !m->queue_io) || 423 (!pgpath && !m->queue_if_no_path)) 424 must_queue = 0; 425 426 if (m->pg_init_required && !m->pg_init_in_progress) { 427 m->pg_init_required = 0; 428 m->pg_init_in_progress = 1; 429 init_required = 1; 430 } 431 432out: 433 spin_unlock_irqrestore(&m->lock, flags); 434 435 if (init_required) 436 hwh->type->pg_init(hwh, pgpath->pg->bypassed, &pgpath->path); 437 438 if (!must_queue) 439 dispatch_queued_ios(m); 440} 441 442/* 443 * An event is triggered whenever a path is taken out of use. 444 * Includes path failure and PG bypass. 445 */ 446static void trigger_event(struct work_struct *work) 447{ 448 struct multipath *m = 449 container_of(work, struct multipath, trigger_event); 450 451 dm_table_event(m->ti->table); 452} 453 454/*----------------------------------------------------------------- 455 * Constructor/argument parsing: 456 * <#multipath feature args> [<arg>]* 457 * <#hw_handler args> [hw_handler [<arg>]*] 458 * <#priority groups> 459 * <initial priority group> 460 * [<selector> <#selector args> [<arg>]* 461 * <#paths> <#per-path selector args> 462 * [<path> [<arg>]* ]+ ]+ 463 *---------------------------------------------------------------*/ 464struct param { 465 unsigned min; 466 unsigned max; 467 char *error; 468}; 469 470static int read_param(struct param *param, char *str, unsigned *v, char **error) 471{ 472 if (!str || 473 (sscanf(str, "%u", v) != 1) || 474 (*v < param->min) || 475 (*v > param->max)) { 476 *error = param->error; 477 return -EINVAL; 478 } 479 480 return 0; 481} 482 483struct arg_set { 484 unsigned argc; 485 char **argv; 486}; 487 488static char *shift(struct arg_set *as) 489{ 490 char *r; 491 492 if (as->argc) { 493 as->argc--; 494 r = *as->argv; 495 as->argv++; 496 return r; 497 } 498 499 return NULL; 500} 501 502static void consume(struct arg_set *as, unsigned n) 503{ 504 BUG_ON (as->argc < n); 505 as->argc -= n; 506 as->argv += n; 507} 508 509static int parse_path_selector(struct arg_set *as, struct priority_group *pg, 510 struct dm_target *ti) 511{ 512 int r; 513 struct path_selector_type *pst; 514 unsigned ps_argc; 515 516 static struct param _params[] = { 517 {0, 1024, "invalid number of path selector args"}, 518 }; 519 520 pst = dm_get_path_selector(shift(as)); 521 if (!pst) { 522 ti->error = "unknown path selector type"; 523 return -EINVAL; 524 } 525 526 r = read_param(_params, shift(as), &ps_argc, &ti->error); 527 if (r) 528 return -EINVAL; 529 530 r = pst->create(&pg->ps, ps_argc, as->argv); 531 if (r) { 532 dm_put_path_selector(pst); 533 ti->error = "path selector constructor failed"; 534 return r; 535 } 536 537 pg->ps.type = pst; 538 consume(as, ps_argc); 539 540 return 0; 541} 542 543static struct pgpath *parse_path(struct arg_set *as, struct path_selector *ps, 544 struct dm_target *ti) 545{ 546 int r; 547 struct pgpath *p; 548 549 /* we need at least a path arg */ 550 if (as->argc < 1) { 551 ti->error = "no device given"; 552 return NULL; 553 } 554 555 p = alloc_pgpath(); 556 if (!p) 557 return NULL; 558 559 r = dm_get_device(ti, shift(as), ti->begin, ti->len, 560 dm_table_get_mode(ti->table), &p->path.dev); 561 if (r) { 562 ti->error = "error getting device"; 563 goto bad; 564 } 565 566 r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error); 567 if (r) { 568 dm_put_device(ti, p->path.dev); 569 goto bad; 570 } 571 572 return p; 573 574 bad: 575 free_pgpath(p); 576 return NULL; 577} 578 579static struct priority_group *parse_priority_group(struct arg_set *as, 580 struct multipath *m) 581{ 582 static struct param _params[] = { 583 {1, 1024, "invalid number of paths"}, 584 {0, 1024, "invalid number of selector args"} 585 }; 586 587 int r; 588 unsigned i, nr_selector_args, nr_params; 589 struct priority_group *pg; 590 struct dm_target *ti = m->ti; 591 592 if (as->argc < 2) { 593 as->argc = 0; 594 ti->error = "not enough priority group aruments"; 595 return NULL; 596 } 597 598 pg = alloc_priority_group(); 599 if (!pg) { 600 ti->error = "couldn't allocate priority group"; 601 return NULL; 602 } 603 pg->m = m; 604 605 r = parse_path_selector(as, pg, ti); 606 if (r) 607 goto bad; 608 609 /* 610 * read the paths 611 */ 612 r = read_param(_params, shift(as), &pg->nr_pgpaths, &ti->error); 613 if (r) 614 goto bad; 615 616 r = read_param(_params + 1, shift(as), &nr_selector_args, &ti->error); 617 if (r) 618 goto bad; 619 620 nr_params = 1 + nr_selector_args; 621 for (i = 0; i < pg->nr_pgpaths; i++) { 622 struct pgpath *pgpath; 623 struct arg_set path_args; 624 625 if (as->argc < nr_params) 626 goto bad; 627 628 path_args.argc = nr_params; 629 path_args.argv = as->argv; 630 631 pgpath = parse_path(&path_args, &pg->ps, ti); 632 if (!pgpath) 633 goto bad; 634 635 pgpath->pg = pg; 636 list_add_tail(&pgpath->list, &pg->pgpaths); 637 consume(as, nr_params); 638 } 639 640 return pg; 641 642 bad: 643 free_priority_group(pg, ti); 644 return NULL; 645} 646 647static int parse_hw_handler(struct arg_set *as, struct multipath *m) 648{ 649 int r; 650 struct hw_handler_type *hwht; 651 unsigned hw_argc; 652 struct dm_target *ti = m->ti; 653 654 static struct param _params[] = { 655 {0, 1024, "invalid number of hardware handler args"}, 656 }; 657 658 r = read_param(_params, shift(as), &hw_argc, &ti->error); 659 if (r) 660 return -EINVAL; 661 662 if (!hw_argc) 663 return 0; 664 665 hwht = dm_get_hw_handler(shift(as)); 666 if (!hwht) { 667 ti->error = "unknown hardware handler type"; 668 return -EINVAL; 669 } 670 671 m->hw_handler.md = dm_table_get_md(ti->table); 672 dm_put(m->hw_handler.md); 673 674 r = hwht->create(&m->hw_handler, hw_argc - 1, as->argv); 675 if (r) { 676 dm_put_hw_handler(hwht); 677 ti->error = "hardware handler constructor failed"; 678 return r; 679 } 680 681 m->hw_handler.type = hwht; 682 consume(as, hw_argc - 1); 683 684 return 0; 685} 686 687static int parse_features(struct arg_set *as, struct multipath *m) 688{ 689 int r; 690 unsigned argc; 691 struct dm_target *ti = m->ti; 692 693 static struct param _params[] = { 694 {0, 1, "invalid number of feature args"}, 695 }; 696 697 r = read_param(_params, shift(as), &argc, &ti->error); 698 if (r) 699 return -EINVAL; 700 701 if (!argc) 702 return 0; 703 704 if (!strnicmp(shift(as), MESG_STR("queue_if_no_path"))) 705 return queue_if_no_path(m, 1, 0); 706 else { 707 ti->error = "Unrecognised multipath feature request"; 708 return -EINVAL; 709 } 710} 711 712static int multipath_ctr(struct dm_target *ti, unsigned int argc, 713 char **argv) 714{ 715 /* target parameters */ 716 static struct param _params[] = { 717 {1, 1024, "invalid number of priority groups"}, 718 {1, 1024, "invalid initial priority group number"}, 719 }; 720 721 int r; 722 struct multipath *m; 723 struct arg_set as; 724 unsigned pg_count = 0; 725 unsigned next_pg_num; 726 727 as.argc = argc; 728 as.argv = argv; 729 730 m = alloc_multipath(ti); 731 if (!m) { 732 ti->error = "can't allocate multipath"; 733 return -EINVAL; 734 } 735 736 r = parse_features(&as, m); 737 if (r) 738 goto bad; 739 740 r = parse_hw_handler(&as, m); 741 if (r) 742 goto bad; 743 744 r = read_param(_params, shift(&as), &m->nr_priority_groups, &ti->error); 745 if (r) 746 goto bad; 747 748 r = read_param(_params + 1, shift(&as), &next_pg_num, &ti->error); 749 if (r) 750 goto bad; 751 752 /* parse the priority groups */ 753 while (as.argc) { 754 struct priority_group *pg; 755 756 pg = parse_priority_group(&as, m); 757 if (!pg) { 758 r = -EINVAL; 759 goto bad; 760 } 761 762 m->nr_valid_paths += pg->nr_pgpaths; 763 list_add_tail(&pg->list, &m->priority_groups); 764 pg_count++; 765 pg->pg_num = pg_count; 766 if (!--next_pg_num) 767 m->next_pg = pg; 768 } 769 770 if (pg_count != m->nr_priority_groups) { 771 ti->error = "priority group count mismatch"; 772 r = -EINVAL; 773 goto bad; 774 } 775 776 return 0; 777 778 bad: 779 free_multipath(m); 780 return r; 781} 782 783static void multipath_dtr(struct dm_target *ti) 784{ 785 struct multipath *m = (struct multipath *) ti->private; 786 787 flush_workqueue(kmultipathd); 788 free_multipath(m); 789} 790 791/* 792 * Map bios, recording original fields for later in case we have to resubmit 793 */ 794static int multipath_map(struct dm_target *ti, struct bio *bio, 795 union map_info *map_context) 796{ 797 int r; 798 struct mpath_io *mpio; 799 struct multipath *m = (struct multipath *) ti->private; 800 801 if (bio_barrier(bio)) 802 return -EOPNOTSUPP; 803 804 mpio = mempool_alloc(m->mpio_pool, GFP_NOIO); 805 dm_bio_record(&mpio->details, bio); 806 807 map_context->ptr = mpio; 808 bio->bi_rw |= (1 << BIO_RW_FAILFAST); 809 r = map_io(m, bio, mpio, 0); 810 if (r < 0 || r == DM_MAPIO_REQUEUE) 811 mempool_free(mpio, m->mpio_pool); 812 813 return r; 814} 815 816/* 817 * Take a path out of use. 818 */ 819static int fail_path(struct pgpath *pgpath) 820{ 821 unsigned long flags; 822 struct multipath *m = pgpath->pg->m; 823 824 spin_lock_irqsave(&m->lock, flags); 825 826 if (!pgpath->path.is_active) 827 goto out; 828 829 DMWARN("Failing path %s.", pgpath->path.dev->name); 830 831 pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path); 832 pgpath->path.is_active = 0; 833 pgpath->fail_count++; 834 835 m->nr_valid_paths--; 836 837 if (pgpath == m->current_pgpath) 838 m->current_pgpath = NULL; 839 840 queue_work(kmultipathd, &m->trigger_event); 841 842out: 843 spin_unlock_irqrestore(&m->lock, flags); 844 845 return 0; 846} 847 848/* 849 * Reinstate a previously-failed path 850 */ 851static int reinstate_path(struct pgpath *pgpath) 852{ 853 int r = 0; 854 unsigned long flags; 855 struct multipath *m = pgpath->pg->m; 856 857 spin_lock_irqsave(&m->lock, flags); 858 859 if (pgpath->path.is_active) 860 goto out; 861 862 if (!pgpath->pg->ps.type) { 863 DMWARN("Reinstate path not supported by path selector %s", 864 pgpath->pg->ps.type->name); 865 r = -EINVAL; 866 goto out; 867 } 868 869 r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path); 870 if (r) 871 goto out; 872 873 pgpath->path.is_active = 1; 874 875 m->current_pgpath = NULL; 876 if (!m->nr_valid_paths++ && m->queue_size) 877 queue_work(kmultipathd, &m->process_queued_ios); 878 879 queue_work(kmultipathd, &m->trigger_event); 880 881out: 882 spin_unlock_irqrestore(&m->lock, flags); 883 884 return r; 885} 886 887/* 888 * Fail or reinstate all paths that match the provided struct dm_dev. 889 */ 890static int action_dev(struct multipath *m, struct dm_dev *dev, 891 action_fn action) 892{ 893 int r = 0; 894 struct pgpath *pgpath; 895 struct priority_group *pg; 896 897 list_for_each_entry(pg, &m->priority_groups, list) { 898 list_for_each_entry(pgpath, &pg->pgpaths, list) { 899 if (pgpath->path.dev == dev) 900 r = action(pgpath); 901 } 902 } 903 904 return r; 905} 906 907/* 908 * Temporarily try to avoid having to use the specified PG 909 */ 910static void bypass_pg(struct multipath *m, struct priority_group *pg, 911 int bypassed) 912{ 913 unsigned long flags; 914 915 spin_lock_irqsave(&m->lock, flags); 916 917 pg->bypassed = bypassed; 918 m->current_pgpath = NULL; 919 m->current_pg = NULL; 920 921 spin_unlock_irqrestore(&m->lock, flags); 922 923 queue_work(kmultipathd, &m->trigger_event); 924} 925 926/* 927 * Switch to using the specified PG from the next I/O that gets mapped 928 */ 929static int switch_pg_num(struct multipath *m, const char *pgstr) 930{ 931 struct priority_group *pg; 932 unsigned pgnum; 933 unsigned long flags; 934 935 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum || 936 (pgnum > m->nr_priority_groups)) { 937 DMWARN("invalid PG number supplied to switch_pg_num"); 938 return -EINVAL; 939 } 940 941 spin_lock_irqsave(&m->lock, flags); 942 list_for_each_entry(pg, &m->priority_groups, list) { 943 pg->bypassed = 0; 944 if (--pgnum) 945 continue; 946 947 m->current_pgpath = NULL; 948 m->current_pg = NULL; 949 m->next_pg = pg; 950 } 951 spin_unlock_irqrestore(&m->lock, flags); 952 953 queue_work(kmultipathd, &m->trigger_event); 954 return 0; 955} 956 957/* 958 * Set/clear bypassed status of a PG. 959 * PGs are numbered upwards from 1 in the order they were declared. 960 */ 961static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed) 962{ 963 struct priority_group *pg; 964 unsigned pgnum; 965 966 if (!pgstr || (sscanf(pgstr, "%u", &pgnum) != 1) || !pgnum || 967 (pgnum > m->nr_priority_groups)) { 968 DMWARN("invalid PG number supplied to bypass_pg"); 969 return -EINVAL; 970 } 971 972 list_for_each_entry(pg, &m->priority_groups, list) { 973 if (!--pgnum) 974 break; 975 } 976 977 bypass_pg(m, pg, bypassed); 978 return 0; 979} 980 981/* 982 * pg_init must call this when it has completed its initialisation 983 */ 984void dm_pg_init_complete(struct dm_path *path, unsigned err_flags) 985{ 986 struct pgpath *pgpath = path_to_pgpath(path); 987 struct priority_group *pg = pgpath->pg; 988 struct multipath *m = pg->m; 989 unsigned long flags; 990 991 /* We insist on failing the path if the PG is already bypassed. */ 992 if (err_flags && pg->bypassed) 993 err_flags |= MP_FAIL_PATH; 994 995 if (err_flags & MP_FAIL_PATH) 996 fail_path(pgpath); 997 998 if (err_flags & MP_BYPASS_PG) 999 bypass_pg(m, pg, 1); 1000 1001 spin_lock_irqsave(&m->lock, flags); 1002 if (err_flags) { 1003 m->current_pgpath = NULL; 1004 m->current_pg = NULL; 1005 } else if (!m->pg_init_required) 1006 m->queue_io = 0; 1007 1008 m->pg_init_in_progress = 0; 1009 queue_work(kmultipathd, &m->process_queued_ios); 1010 spin_unlock_irqrestore(&m->lock, flags); 1011} 1012 1013/* 1014 * end_io handling 1015 */ 1016static int do_end_io(struct multipath *m, struct bio *bio, 1017 int error, struct mpath_io *mpio) 1018{ 1019 struct hw_handler *hwh = &m->hw_handler; 1020 unsigned err_flags = MP_FAIL_PATH; /* Default behavior */ 1021 unsigned long flags; 1022 1023 if (!error) 1024 return 0; /* I/O complete */ 1025 1026 if ((error == -EWOULDBLOCK) && bio_rw_ahead(bio)) 1027 return error; 1028 1029 if (error == -EOPNOTSUPP) 1030 return error; 1031 1032 spin_lock_irqsave(&m->lock, flags); 1033 if (!m->nr_valid_paths) { 1034 if (__must_push_back(m)) { 1035 spin_unlock_irqrestore(&m->lock, flags); 1036 return DM_ENDIO_REQUEUE; 1037 } else if (!m->queue_if_no_path) { 1038 spin_unlock_irqrestore(&m->lock, flags); 1039 return -EIO; 1040 } else { 1041 spin_unlock_irqrestore(&m->lock, flags); 1042 goto requeue; 1043 } 1044 } 1045 spin_unlock_irqrestore(&m->lock, flags); 1046 1047 if (hwh->type && hwh->type->error) 1048 err_flags = hwh->type->error(hwh, bio); 1049 1050 if (mpio->pgpath) { 1051 if (err_flags & MP_FAIL_PATH) 1052 fail_path(mpio->pgpath); 1053 1054 if (err_flags & MP_BYPASS_PG) 1055 bypass_pg(m, mpio->pgpath->pg, 1); 1056 } 1057 1058 if (err_flags & MP_ERROR_IO) 1059 return -EIO; 1060 1061 requeue: 1062 dm_bio_restore(&mpio->details, bio); 1063 1064 /* queue for the daemon to resubmit or fail */ 1065 spin_lock_irqsave(&m->lock, flags); 1066 bio_list_add(&m->queued_ios, bio); 1067 m->queue_size++; 1068 if (!m->queue_io) 1069 queue_work(kmultipathd, &m->process_queued_ios); 1070 spin_unlock_irqrestore(&m->lock, flags); 1071 1072 return DM_ENDIO_INCOMPLETE; /* io not complete */ 1073} 1074 1075static int multipath_end_io(struct dm_target *ti, struct bio *bio, 1076 int error, union map_info *map_context) 1077{ 1078 struct multipath *m = (struct multipath *) ti->private; 1079 struct mpath_io *mpio = (struct mpath_io *) map_context->ptr; 1080 struct pgpath *pgpath = mpio->pgpath; 1081 struct path_selector *ps; 1082 int r; 1083 1084 r = do_end_io(m, bio, error, mpio); 1085 if (pgpath) { 1086 ps = &pgpath->pg->ps; 1087 if (ps->type->end_io) 1088 ps->type->end_io(ps, &pgpath->path); 1089 } 1090 if (r != DM_ENDIO_INCOMPLETE) 1091 mempool_free(mpio, m->mpio_pool); 1092 1093 return r; 1094} 1095 1096/* 1097 * Suspend can't complete until all the I/O is processed so if 1098 * the last path fails we must error any remaining I/O. 1099 * Note that if the freeze_bdev fails while suspending, the 1100 * queue_if_no_path state is lost - userspace should reset it. 1101 */ 1102static void multipath_presuspend(struct dm_target *ti) 1103{ 1104 struct multipath *m = (struct multipath *) ti->private; 1105 1106 queue_if_no_path(m, 0, 1); 1107} 1108 1109/* 1110 * Restore the queue_if_no_path setting. 1111 */ 1112static void multipath_resume(struct dm_target *ti) 1113{ 1114 struct multipath *m = (struct multipath *) ti->private; 1115 unsigned long flags; 1116 1117 spin_lock_irqsave(&m->lock, flags); 1118 m->queue_if_no_path = m->saved_queue_if_no_path; 1119 spin_unlock_irqrestore(&m->lock, flags); 1120} 1121 1122/* 1123 * Info output has the following format: 1124 * num_multipath_feature_args [multipath_feature_args]* 1125 * num_handler_status_args [handler_status_args]* 1126 * num_groups init_group_number 1127 * [A|D|E num_ps_status_args [ps_status_args]* 1128 * num_paths num_selector_args 1129 * [path_dev A|F fail_count [selector_args]* ]+ ]+ 1130 * 1131 * Table output has the following format (identical to the constructor string): 1132 * num_feature_args [features_args]* 1133 * num_handler_args hw_handler [hw_handler_args]* 1134 * num_groups init_group_number 1135 * [priority selector-name num_ps_args [ps_args]* 1136 * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+ 1137 */ 1138static int multipath_status(struct dm_target *ti, status_type_t type, 1139 char *result, unsigned int maxlen) 1140{ 1141 int sz = 0; 1142 unsigned long flags; 1143 struct multipath *m = (struct multipath *) ti->private; 1144 struct hw_handler *hwh = &m->hw_handler; 1145 struct priority_group *pg; 1146 struct pgpath *p; 1147 unsigned pg_num; 1148 char state; 1149 1150 spin_lock_irqsave(&m->lock, flags); 1151 1152 /* Features */ 1153 if (type == STATUSTYPE_INFO) 1154 DMEMIT("1 %u ", m->queue_size); 1155 else if (m->queue_if_no_path) 1156 DMEMIT("1 queue_if_no_path "); 1157 else 1158 DMEMIT("0 "); 1159 1160 if (hwh->type && hwh->type->status) 1161 sz += hwh->type->status(hwh, type, result + sz, maxlen - sz); 1162 else if (!hwh->type || type == STATUSTYPE_INFO) 1163 DMEMIT("0 "); 1164 else 1165 DMEMIT("1 %s ", hwh->type->name); 1166 1167 DMEMIT("%u ", m->nr_priority_groups); 1168 1169 if (m->next_pg) 1170 pg_num = m->next_pg->pg_num; 1171 else if (m->current_pg) 1172 pg_num = m->current_pg->pg_num; 1173 else 1174 pg_num = 1; 1175 1176 DMEMIT("%u ", pg_num); 1177 1178 switch (type) { 1179 case STATUSTYPE_INFO: 1180 list_for_each_entry(pg, &m->priority_groups, list) { 1181 if (pg->bypassed) 1182 state = 'D'; /* Disabled */ 1183 else if (pg == m->current_pg) 1184 state = 'A'; /* Currently Active */ 1185 else 1186 state = 'E'; /* Enabled */ 1187 1188 DMEMIT("%c ", state); 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->info_args); 1199 1200 list_for_each_entry(p, &pg->pgpaths, list) { 1201 DMEMIT("%s %s %u ", p->path.dev->name, 1202 p->path.is_active ? "A" : "F", 1203 p->fail_count); 1204 if (pg->ps.type->status) 1205 sz += pg->ps.type->status(&pg->ps, 1206 &p->path, type, result + sz, 1207 maxlen - sz); 1208 } 1209 } 1210 break; 1211 1212 case STATUSTYPE_TABLE: 1213 list_for_each_entry(pg, &m->priority_groups, list) { 1214 DMEMIT("%s ", pg->ps.type->name); 1215 1216 if (pg->ps.type->status) 1217 sz += pg->ps.type->status(&pg->ps, NULL, type, 1218 result + sz, 1219 maxlen - sz); 1220 else 1221 DMEMIT("0 "); 1222 1223 DMEMIT("%u %u ", pg->nr_pgpaths, 1224 pg->ps.type->table_args); 1225 1226 list_for_each_entry(p, &pg->pgpaths, list) { 1227 DMEMIT("%s ", p->path.dev->name); 1228 if (pg->ps.type->status) 1229 sz += pg->ps.type->status(&pg->ps, 1230 &p->path, type, result + sz, 1231 maxlen - sz); 1232 } 1233 } 1234 break; 1235 } 1236 1237 spin_unlock_irqrestore(&m->lock, flags); 1238 1239 return 0; 1240} 1241 1242static int multipath_message(struct dm_target *ti, unsigned argc, char **argv) 1243{ 1244 int r; 1245 struct dm_dev *dev; 1246 struct multipath *m = (struct multipath *) ti->private; 1247 action_fn action; 1248 1249 if (argc == 1) { 1250 if (!strnicmp(argv[0], MESG_STR("queue_if_no_path"))) 1251 return queue_if_no_path(m, 1, 0); 1252 else if (!strnicmp(argv[0], MESG_STR("fail_if_no_path"))) 1253 return queue_if_no_path(m, 0, 0); 1254 } 1255 1256 if (argc != 2) 1257 goto error; 1258 1259 if (!strnicmp(argv[0], MESG_STR("disable_group"))) 1260 return bypass_pg_num(m, argv[1], 1); 1261 else if (!strnicmp(argv[0], MESG_STR("enable_group"))) 1262 return bypass_pg_num(m, argv[1], 0); 1263 else if (!strnicmp(argv[0], MESG_STR("switch_group"))) 1264 return switch_pg_num(m, argv[1]); 1265 else if (!strnicmp(argv[0], MESG_STR("reinstate_path"))) 1266 action = reinstate_path; 1267 else if (!strnicmp(argv[0], MESG_STR("fail_path"))) 1268 action = fail_path; 1269 else 1270 goto error; 1271 1272 r = dm_get_device(ti, argv[1], ti->begin, ti->len, 1273 dm_table_get_mode(ti->table), &dev); 1274 if (r) { 1275 DMWARN("message: error getting device %s", 1276 argv[1]); 1277 return -EINVAL; 1278 } 1279 1280 r = action_dev(m, dev, action); 1281 1282 dm_put_device(ti, dev); 1283 1284 return r; 1285 1286error: 1287 DMWARN("Unrecognised multipath message received."); 1288 return -EINVAL; 1289} 1290 1291static int multipath_ioctl(struct dm_target *ti, struct inode *inode, 1292 struct file *filp, unsigned int cmd, 1293 unsigned long arg) 1294{ 1295 struct multipath *m = (struct multipath *) ti->private; 1296 struct block_device *bdev = NULL; 1297 unsigned long flags; 1298 struct file fake_file = {}; 1299 struct dentry fake_dentry = {}; 1300 int r = 0; 1301 1302 fake_file.f_path.dentry = &fake_dentry; 1303 1304 spin_lock_irqsave(&m->lock, flags); 1305 1306 if (!m->current_pgpath) 1307 __choose_pgpath(m); 1308 1309 if (m->current_pgpath) { 1310 bdev = m->current_pgpath->path.dev->bdev; 1311 fake_dentry.d_inode = bdev->bd_inode; 1312 fake_file.f_mode = m->current_pgpath->path.dev->mode; 1313 } 1314 1315 if (m->queue_io) 1316 r = -EAGAIN; 1317 else if (!bdev) 1318 r = -EIO; 1319 1320 spin_unlock_irqrestore(&m->lock, flags); 1321 1322 return r ? : blkdev_driver_ioctl(bdev->bd_inode, &fake_file, 1323 bdev->bd_disk, cmd, arg); 1324} 1325 1326/*----------------------------------------------------------------- 1327 * Module setup 1328 *---------------------------------------------------------------*/ 1329static struct target_type multipath_target = { 1330 .name = "multipath", 1331 .version = {1, 0, 5}, 1332 .module = THIS_MODULE, 1333 .ctr = multipath_ctr, 1334 .dtr = multipath_dtr, 1335 .map = multipath_map, 1336 .end_io = multipath_end_io, 1337 .presuspend = multipath_presuspend, 1338 .resume = multipath_resume, 1339 .status = multipath_status, 1340 .message = multipath_message, 1341 .ioctl = multipath_ioctl, 1342}; 1343 1344static int __init dm_multipath_init(void) 1345{ 1346 int r; 1347 1348 /* allocate a slab for the dm_ios */ 1349 _mpio_cache = kmem_cache_create("dm_mpath", sizeof(struct mpath_io), 1350 0, 0, NULL, NULL); 1351 if (!_mpio_cache) 1352 return -ENOMEM; 1353 1354 r = dm_register_target(&multipath_target); 1355 if (r < 0) { 1356 DMERR("%s: register failed %d", multipath_target.name, r); 1357 kmem_cache_destroy(_mpio_cache); 1358 return -EINVAL; 1359 } 1360 1361 kmultipathd = create_workqueue("kmpathd"); 1362 if (!kmultipathd) { 1363 DMERR("%s: failed to create workqueue kmpathd", 1364 multipath_target.name); 1365 dm_unregister_target(&multipath_target); 1366 kmem_cache_destroy(_mpio_cache); 1367 return -ENOMEM; 1368 } 1369 1370 DMINFO("version %u.%u.%u loaded", 1371 multipath_target.version[0], multipath_target.version[1], 1372 multipath_target.version[2]); 1373 1374 return r; 1375} 1376 1377static void __exit dm_multipath_exit(void) 1378{ 1379 int r; 1380 1381 destroy_workqueue(kmultipathd); 1382 1383 r = dm_unregister_target(&multipath_target); 1384 if (r < 0) 1385 DMERR("%s: target unregister failed %d", 1386 multipath_target.name, r); 1387 kmem_cache_destroy(_mpio_cache); 1388} 1389 1390EXPORT_SYMBOL_GPL(dm_pg_init_complete); 1391 1392module_init(dm_multipath_init); 1393module_exit(dm_multipath_exit); 1394 1395MODULE_DESCRIPTION(DM_NAME " multipath target"); 1396MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>"); 1397MODULE_LICENSE("GPL"); 1398