| 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-uevent.h" |
| 12 | |
| 13 | #include <linux/ctype.h> |
| 14 | #include <linux/init.h> |
| 15 | #include <linux/mempool.h> |
| 16 | #include <linux/module.h> |
| 17 | #include <linux/pagemap.h> |
| 18 | #include <linux/slab.h> |
| 19 | #include <linux/time.h> |
| 20 | #include <linux/workqueue.h> |
| 21 | #include <linux/delay.h> |
| 22 | #include <scsi/scsi_dh.h> |
| 23 | #include <linux/atomic.h> |
| 24 | |
| 25 | #define DM_MSG_PREFIX "multipath" |
| 26 | #define DM_PG_INIT_DELAY_MSECS 2000 |
| 27 | #define DM_PG_INIT_DELAY_DEFAULT ((unsigned) -1) |
| 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 delayed_work activate_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 | const char *hw_handler_name; |
| 66 | char *hw_handler_params; |
| 67 | |
| 68 | spinlock_t lock; |
| 69 | |
| 70 | unsigned nr_priority_groups; |
| 71 | struct list_head priority_groups; |
| 72 | |
| 73 | wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */ |
| 74 | |
| 75 | unsigned pg_init_required; /* pg_init needs calling? */ |
| 76 | unsigned pg_init_in_progress; /* Only one pg_init allowed at once */ |
| 77 | unsigned pg_init_delay_retry; /* Delay pg_init retry? */ |
| 78 | |
| 79 | unsigned nr_valid_paths; /* Total number of usable paths */ |
| 80 | struct pgpath *current_pgpath; |
| 81 | struct priority_group *current_pg; |
| 82 | struct priority_group *next_pg; /* Switch to this PG if set */ |
| 83 | unsigned repeat_count; /* I/Os left before calling PS again */ |
| 84 | |
| 85 | unsigned queue_io:1; /* Must we queue all I/O? */ |
| 86 | unsigned queue_if_no_path:1; /* Queue I/O if last path fails? */ |
| 87 | unsigned saved_queue_if_no_path:1; /* Saved state during suspension */ |
| 88 | |
| 89 | unsigned pg_init_retries; /* Number of times to retry pg_init */ |
| 90 | unsigned pg_init_count; /* Number of times pg_init called */ |
| 91 | unsigned pg_init_delay_msecs; /* Number of msecs before pg_init retry */ |
| 92 | |
| 93 | unsigned queue_size; |
| 94 | struct work_struct process_queued_ios; |
| 95 | struct list_head queued_ios; |
| 96 | |
| 97 | struct work_struct trigger_event; |
| 98 | |
| 99 | /* |
| 100 | * We must use a mempool of dm_mpath_io structs so that we |
| 101 | * can resubmit bios on error. |
| 102 | */ |
| 103 | mempool_t *mpio_pool; |
| 104 | |
| 105 | struct mutex work_mutex; |
| 106 | }; |
| 107 | |
| 108 | /* |
| 109 | * Context information attached to each bio we process. |
| 110 | */ |
| 111 | struct dm_mpath_io { |
| 112 | struct pgpath *pgpath; |
| 113 | size_t nr_bytes; |
| 114 | }; |
| 115 | |
| 116 | typedef int (*action_fn) (struct pgpath *pgpath); |
| 117 | |
| 118 | #define MIN_IOS 256 /* Mempool size */ |
| 119 | |
| 120 | static struct kmem_cache *_mpio_cache; |
| 121 | |
| 122 | static struct workqueue_struct *kmultipathd, *kmpath_handlerd; |
| 123 | static void process_queued_ios(struct work_struct *work); |
| 124 | static void trigger_event(struct work_struct *work); |
| 125 | static void activate_path(struct work_struct *work); |
| 126 | |
| 127 | |
| 128 | /*----------------------------------------------- |
| 129 | * Allocation routines |
| 130 | *-----------------------------------------------*/ |
| 131 | |
| 132 | static struct pgpath *alloc_pgpath(void) |
| 133 | { |
| 134 | struct pgpath *pgpath = kzalloc(sizeof(*pgpath), GFP_KERNEL); |
| 135 | |
| 136 | if (pgpath) { |
| 137 | pgpath->is_active = 1; |
| 138 | INIT_DELAYED_WORK(&pgpath->activate_path, activate_path); |
| 139 | } |
| 140 | |
| 141 | return pgpath; |
| 142 | } |
| 143 | |
| 144 | static void free_pgpath(struct pgpath *pgpath) |
| 145 | { |
| 146 | kfree(pgpath); |
| 147 | } |
| 148 | |
| 149 | static struct priority_group *alloc_priority_group(void) |
| 150 | { |
| 151 | struct priority_group *pg; |
| 152 | |
| 153 | pg = kzalloc(sizeof(*pg), GFP_KERNEL); |
| 154 | |
| 155 | if (pg) |
| 156 | INIT_LIST_HEAD(&pg->pgpaths); |
| 157 | |
| 158 | return pg; |
| 159 | } |
| 160 | |
| 161 | static void free_pgpaths(struct list_head *pgpaths, struct dm_target *ti) |
| 162 | { |
| 163 | struct pgpath *pgpath, *tmp; |
| 164 | struct multipath *m = ti->private; |
| 165 | |
| 166 | list_for_each_entry_safe(pgpath, tmp, pgpaths, list) { |
| 167 | list_del(&pgpath->list); |
| 168 | if (m->hw_handler_name) |
| 169 | scsi_dh_detach(bdev_get_queue(pgpath->path.dev->bdev)); |
| 170 | dm_put_device(ti, pgpath->path.dev); |
| 171 | free_pgpath(pgpath); |
| 172 | } |
| 173 | } |
| 174 | |
| 175 | static void free_priority_group(struct priority_group *pg, |
| 176 | struct dm_target *ti) |
| 177 | { |
| 178 | struct path_selector *ps = &pg->ps; |
| 179 | |
| 180 | if (ps->type) { |
| 181 | ps->type->destroy(ps); |
| 182 | dm_put_path_selector(ps->type); |
| 183 | } |
| 184 | |
| 185 | free_pgpaths(&pg->pgpaths, ti); |
| 186 | kfree(pg); |
| 187 | } |
| 188 | |
| 189 | static struct multipath *alloc_multipath(struct dm_target *ti) |
| 190 | { |
| 191 | struct multipath *m; |
| 192 | |
| 193 | m = kzalloc(sizeof(*m), GFP_KERNEL); |
| 194 | if (m) { |
| 195 | INIT_LIST_HEAD(&m->priority_groups); |
| 196 | INIT_LIST_HEAD(&m->queued_ios); |
| 197 | spin_lock_init(&m->lock); |
| 198 | m->queue_io = 1; |
| 199 | m->pg_init_delay_msecs = DM_PG_INIT_DELAY_DEFAULT; |
| 200 | INIT_WORK(&m->process_queued_ios, process_queued_ios); |
| 201 | INIT_WORK(&m->trigger_event, trigger_event); |
| 202 | init_waitqueue_head(&m->pg_init_wait); |
| 203 | mutex_init(&m->work_mutex); |
| 204 | m->mpio_pool = mempool_create_slab_pool(MIN_IOS, _mpio_cache); |
| 205 | if (!m->mpio_pool) { |
| 206 | kfree(m); |
| 207 | return NULL; |
| 208 | } |
| 209 | m->ti = ti; |
| 210 | ti->private = m; |
| 211 | } |
| 212 | |
| 213 | return m; |
| 214 | } |
| 215 | |
| 216 | static void free_multipath(struct multipath *m) |
| 217 | { |
| 218 | struct priority_group *pg, *tmp; |
| 219 | |
| 220 | list_for_each_entry_safe(pg, tmp, &m->priority_groups, list) { |
| 221 | list_del(&pg->list); |
| 222 | free_priority_group(pg, m->ti); |
| 223 | } |
| 224 | |
| 225 | kfree(m->hw_handler_name); |
| 226 | kfree(m->hw_handler_params); |
| 227 | mempool_destroy(m->mpio_pool); |
| 228 | kfree(m); |
| 229 | } |
| 230 | |
| 231 | static int set_mapinfo(struct multipath *m, union map_info *info) |
| 232 | { |
| 233 | struct dm_mpath_io *mpio; |
| 234 | |
| 235 | mpio = mempool_alloc(m->mpio_pool, GFP_ATOMIC); |
| 236 | if (!mpio) |
| 237 | return -ENOMEM; |
| 238 | |
| 239 | memset(mpio, 0, sizeof(*mpio)); |
| 240 | info->ptr = mpio; |
| 241 | |
| 242 | return 0; |
| 243 | } |
| 244 | |
| 245 | static void clear_mapinfo(struct multipath *m, union map_info *info) |
| 246 | { |
| 247 | struct dm_mpath_io *mpio = info->ptr; |
| 248 | |
| 249 | info->ptr = NULL; |
| 250 | mempool_free(mpio, m->mpio_pool); |
| 251 | } |
| 252 | |
| 253 | /*----------------------------------------------- |
| 254 | * Path selection |
| 255 | *-----------------------------------------------*/ |
| 256 | |
| 257 | static void __pg_init_all_paths(struct multipath *m) |
| 258 | { |
| 259 | struct pgpath *pgpath; |
| 260 | unsigned long pg_init_delay = 0; |
| 261 | |
| 262 | m->pg_init_count++; |
| 263 | m->pg_init_required = 0; |
| 264 | if (m->pg_init_delay_retry) |
| 265 | pg_init_delay = msecs_to_jiffies(m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT ? |
| 266 | m->pg_init_delay_msecs : DM_PG_INIT_DELAY_MSECS); |
| 267 | list_for_each_entry(pgpath, &m->current_pg->pgpaths, list) { |
| 268 | /* Skip failed paths */ |
| 269 | if (!pgpath->is_active) |
| 270 | continue; |
| 271 | if (queue_delayed_work(kmpath_handlerd, &pgpath->activate_path, |
| 272 | pg_init_delay)) |
| 273 | m->pg_init_in_progress++; |
| 274 | } |
| 275 | } |
| 276 | |
| 277 | static void __switch_pg(struct multipath *m, struct pgpath *pgpath) |
| 278 | { |
| 279 | m->current_pg = pgpath->pg; |
| 280 | |
| 281 | /* Must we initialise the PG first, and queue I/O till it's ready? */ |
| 282 | if (m->hw_handler_name) { |
| 283 | m->pg_init_required = 1; |
| 284 | m->queue_io = 1; |
| 285 | } else { |
| 286 | m->pg_init_required = 0; |
| 287 | m->queue_io = 0; |
| 288 | } |
| 289 | |
| 290 | m->pg_init_count = 0; |
| 291 | } |
| 292 | |
| 293 | static int __choose_path_in_pg(struct multipath *m, struct priority_group *pg, |
| 294 | size_t nr_bytes) |
| 295 | { |
| 296 | struct dm_path *path; |
| 297 | |
| 298 | path = pg->ps.type->select_path(&pg->ps, &m->repeat_count, nr_bytes); |
| 299 | if (!path) |
| 300 | return -ENXIO; |
| 301 | |
| 302 | m->current_pgpath = path_to_pgpath(path); |
| 303 | |
| 304 | if (m->current_pg != pg) |
| 305 | __switch_pg(m, m->current_pgpath); |
| 306 | |
| 307 | return 0; |
| 308 | } |
| 309 | |
| 310 | static void __choose_pgpath(struct multipath *m, size_t nr_bytes) |
| 311 | { |
| 312 | struct priority_group *pg; |
| 313 | unsigned bypassed = 1; |
| 314 | |
| 315 | if (!m->nr_valid_paths) |
| 316 | goto failed; |
| 317 | |
| 318 | /* Were we instructed to switch PG? */ |
| 319 | if (m->next_pg) { |
| 320 | pg = m->next_pg; |
| 321 | m->next_pg = NULL; |
| 322 | if (!__choose_path_in_pg(m, pg, nr_bytes)) |
| 323 | return; |
| 324 | } |
| 325 | |
| 326 | /* Don't change PG until it has no remaining paths */ |
| 327 | if (m->current_pg && !__choose_path_in_pg(m, m->current_pg, nr_bytes)) |
| 328 | return; |
| 329 | |
| 330 | /* |
| 331 | * Loop through priority groups until we find a valid path. |
| 332 | * First time we skip PGs marked 'bypassed'. |
| 333 | * Second time we only try the ones we skipped, but set |
| 334 | * pg_init_delay_retry so we do not hammer controllers. |
| 335 | */ |
| 336 | do { |
| 337 | list_for_each_entry(pg, &m->priority_groups, list) { |
| 338 | if (pg->bypassed == bypassed) |
| 339 | continue; |
| 340 | if (!__choose_path_in_pg(m, pg, nr_bytes)) { |
| 341 | if (!bypassed) |
| 342 | m->pg_init_delay_retry = 1; |
| 343 | return; |
| 344 | } |
| 345 | } |
| 346 | } while (bypassed--); |
| 347 | |
| 348 | failed: |
| 349 | m->current_pgpath = NULL; |
| 350 | m->current_pg = NULL; |
| 351 | } |
| 352 | |
| 353 | /* |
| 354 | * Check whether bios must be queued in the device-mapper core rather |
| 355 | * than here in the target. |
| 356 | * |
| 357 | * m->lock must be held on entry. |
| 358 | * |
| 359 | * If m->queue_if_no_path and m->saved_queue_if_no_path hold the |
| 360 | * same value then we are not between multipath_presuspend() |
| 361 | * and multipath_resume() calls and we have no need to check |
| 362 | * for the DMF_NOFLUSH_SUSPENDING flag. |
| 363 | */ |
| 364 | static int __must_push_back(struct multipath *m) |
| 365 | { |
| 366 | return (m->queue_if_no_path != m->saved_queue_if_no_path && |
| 367 | dm_noflush_suspending(m->ti)); |
| 368 | } |
| 369 | |
| 370 | static int map_io(struct multipath *m, struct request *clone, |
| 371 | union map_info *map_context, unsigned was_queued) |
| 372 | { |
| 373 | int r = DM_MAPIO_REMAPPED; |
| 374 | size_t nr_bytes = blk_rq_bytes(clone); |
| 375 | unsigned long flags; |
| 376 | struct pgpath *pgpath; |
| 377 | struct block_device *bdev; |
| 378 | struct dm_mpath_io *mpio = map_context->ptr; |
| 379 | |
| 380 | spin_lock_irqsave(&m->lock, flags); |
| 381 | |
| 382 | /* Do we need to select a new pgpath? */ |
| 383 | if (!m->current_pgpath || |
| 384 | (!m->queue_io && (m->repeat_count && --m->repeat_count == 0))) |
| 385 | __choose_pgpath(m, nr_bytes); |
| 386 | |
| 387 | pgpath = m->current_pgpath; |
| 388 | |
| 389 | if (was_queued) |
| 390 | m->queue_size--; |
| 391 | |
| 392 | if ((pgpath && m->queue_io) || |
| 393 | (!pgpath && m->queue_if_no_path)) { |
| 394 | /* Queue for the daemon to resubmit */ |
| 395 | list_add_tail(&clone->queuelist, &m->queued_ios); |
| 396 | m->queue_size++; |
| 397 | if ((m->pg_init_required && !m->pg_init_in_progress) || |
| 398 | !m->queue_io) |
| 399 | queue_work(kmultipathd, &m->process_queued_ios); |
| 400 | pgpath = NULL; |
| 401 | r = DM_MAPIO_SUBMITTED; |
| 402 | } else if (pgpath) { |
| 403 | bdev = pgpath->path.dev->bdev; |
| 404 | clone->q = bdev_get_queue(bdev); |
| 405 | clone->rq_disk = bdev->bd_disk; |
| 406 | } else if (__must_push_back(m)) |
| 407 | r = DM_MAPIO_REQUEUE; |
| 408 | else |
| 409 | r = -EIO; /* Failed */ |
| 410 | |
| 411 | mpio->pgpath = pgpath; |
| 412 | mpio->nr_bytes = nr_bytes; |
| 413 | |
| 414 | if (r == DM_MAPIO_REMAPPED && pgpath->pg->ps.type->start_io) |
| 415 | pgpath->pg->ps.type->start_io(&pgpath->pg->ps, &pgpath->path, |
| 416 | nr_bytes); |
| 417 | |
| 418 | spin_unlock_irqrestore(&m->lock, flags); |
| 419 | |
| 420 | return r; |
| 421 | } |
| 422 | |
| 423 | /* |
| 424 | * If we run out of usable paths, should we queue I/O or error it? |
| 425 | */ |
| 426 | static int queue_if_no_path(struct multipath *m, unsigned queue_if_no_path, |
| 427 | unsigned save_old_value) |
| 428 | { |
| 429 | unsigned long flags; |
| 430 | |
| 431 | spin_lock_irqsave(&m->lock, flags); |
| 432 | |
| 433 | if (save_old_value) |
| 434 | m->saved_queue_if_no_path = m->queue_if_no_path; |
| 435 | else |
| 436 | m->saved_queue_if_no_path = queue_if_no_path; |
| 437 | m->queue_if_no_path = queue_if_no_path; |
| 438 | if (!m->queue_if_no_path && m->queue_size) |
| 439 | queue_work(kmultipathd, &m->process_queued_ios); |
| 440 | |
| 441 | spin_unlock_irqrestore(&m->lock, flags); |
| 442 | |
| 443 | return 0; |
| 444 | } |
| 445 | |
| 446 | /*----------------------------------------------------------------- |
| 447 | * The multipath daemon is responsible for resubmitting queued ios. |
| 448 | *---------------------------------------------------------------*/ |
| 449 | |
| 450 | static void dispatch_queued_ios(struct multipath *m) |
| 451 | { |
| 452 | int r; |
| 453 | unsigned long flags; |
| 454 | union map_info *info; |
| 455 | struct request *clone, *n; |
| 456 | LIST_HEAD(cl); |
| 457 | |
| 458 | spin_lock_irqsave(&m->lock, flags); |
| 459 | list_splice_init(&m->queued_ios, &cl); |
| 460 | spin_unlock_irqrestore(&m->lock, flags); |
| 461 | |
| 462 | list_for_each_entry_safe(clone, n, &cl, queuelist) { |
| 463 | list_del_init(&clone->queuelist); |
| 464 | |
| 465 | info = dm_get_rq_mapinfo(clone); |
| 466 | |
| 467 | r = map_io(m, clone, info, 1); |
| 468 | if (r < 0) { |
| 469 | clear_mapinfo(m, info); |
| 470 | dm_kill_unmapped_request(clone, r); |
| 471 | } else if (r == DM_MAPIO_REMAPPED) |
| 472 | dm_dispatch_request(clone); |
| 473 | else if (r == DM_MAPIO_REQUEUE) { |
| 474 | clear_mapinfo(m, info); |
| 475 | dm_requeue_unmapped_request(clone); |
| 476 | } |
| 477 | } |
| 478 | } |
| 479 | |
| 480 | static void process_queued_ios(struct work_struct *work) |
| 481 | { |
| 482 | struct multipath *m = |
| 483 | container_of(work, struct multipath, process_queued_ios); |
| 484 | struct pgpath *pgpath = NULL; |
| 485 | unsigned must_queue = 1; |
| 486 | unsigned long flags; |
| 487 | |
| 488 | spin_lock_irqsave(&m->lock, flags); |
| 489 | |
| 490 | if (!m->current_pgpath) |
| 491 | __choose_pgpath(m, 0); |
| 492 | |
| 493 | pgpath = m->current_pgpath; |
| 494 | |
| 495 | if ((pgpath && !m->queue_io) || |
| 496 | (!pgpath && !m->queue_if_no_path)) |
| 497 | must_queue = 0; |
| 498 | |
| 499 | if (m->pg_init_required && !m->pg_init_in_progress && pgpath) |
| 500 | __pg_init_all_paths(m); |
| 501 | |
| 502 | spin_unlock_irqrestore(&m->lock, flags); |
| 503 | if (!must_queue) |
| 504 | dispatch_queued_ios(m); |
| 505 | } |
| 506 | |
| 507 | /* |
| 508 | * An event is triggered whenever a path is taken out of use. |
| 509 | * Includes path failure and PG bypass. |
| 510 | */ |
| 511 | static void trigger_event(struct work_struct *work) |
| 512 | { |
| 513 | struct multipath *m = |
| 514 | container_of(work, struct multipath, trigger_event); |
| 515 | |
| 516 | dm_table_event(m->ti->table); |
| 517 | } |
| 518 | |
| 519 | /*----------------------------------------------------------------- |
| 520 | * Constructor/argument parsing: |
| 521 | * <#multipath feature args> [<arg>]* |
| 522 | * <#hw_handler args> [hw_handler [<arg>]*] |
| 523 | * <#priority groups> |
| 524 | * <initial priority group> |
| 525 | * [<selector> <#selector args> [<arg>]* |
| 526 | * <#paths> <#per-path selector args> |
| 527 | * [<path> [<arg>]* ]+ ]+ |
| 528 | *---------------------------------------------------------------*/ |
| 529 | static int parse_path_selector(struct dm_arg_set *as, struct priority_group *pg, |
| 530 | struct dm_target *ti) |
| 531 | { |
| 532 | int r; |
| 533 | struct path_selector_type *pst; |
| 534 | unsigned ps_argc; |
| 535 | |
| 536 | static struct dm_arg _args[] = { |
| 537 | {0, 1024, "invalid number of path selector args"}, |
| 538 | }; |
| 539 | |
| 540 | pst = dm_get_path_selector(dm_shift_arg(as)); |
| 541 | if (!pst) { |
| 542 | ti->error = "unknown path selector type"; |
| 543 | return -EINVAL; |
| 544 | } |
| 545 | |
| 546 | r = dm_read_arg_group(_args, as, &ps_argc, &ti->error); |
| 547 | if (r) { |
| 548 | dm_put_path_selector(pst); |
| 549 | return -EINVAL; |
| 550 | } |
| 551 | |
| 552 | r = pst->create(&pg->ps, ps_argc, as->argv); |
| 553 | if (r) { |
| 554 | dm_put_path_selector(pst); |
| 555 | ti->error = "path selector constructor failed"; |
| 556 | return r; |
| 557 | } |
| 558 | |
| 559 | pg->ps.type = pst; |
| 560 | dm_consume_args(as, ps_argc); |
| 561 | |
| 562 | return 0; |
| 563 | } |
| 564 | |
| 565 | static struct pgpath *parse_path(struct dm_arg_set *as, struct path_selector *ps, |
| 566 | struct dm_target *ti) |
| 567 | { |
| 568 | int r; |
| 569 | struct pgpath *p; |
| 570 | struct multipath *m = ti->private; |
| 571 | |
| 572 | /* we need at least a path arg */ |
| 573 | if (as->argc < 1) { |
| 574 | ti->error = "no device given"; |
| 575 | return ERR_PTR(-EINVAL); |
| 576 | } |
| 577 | |
| 578 | p = alloc_pgpath(); |
| 579 | if (!p) |
| 580 | return ERR_PTR(-ENOMEM); |
| 581 | |
| 582 | r = dm_get_device(ti, dm_shift_arg(as), dm_table_get_mode(ti->table), |
| 583 | &p->path.dev); |
| 584 | if (r) { |
| 585 | ti->error = "error getting device"; |
| 586 | goto bad; |
| 587 | } |
| 588 | |
| 589 | if (m->hw_handler_name) { |
| 590 | struct request_queue *q = bdev_get_queue(p->path.dev->bdev); |
| 591 | |
| 592 | r = scsi_dh_attach(q, m->hw_handler_name); |
| 593 | if (r == -EBUSY) { |
| 594 | /* |
| 595 | * Already attached to different hw_handler, |
| 596 | * try to reattach with correct one. |
| 597 | */ |
| 598 | scsi_dh_detach(q); |
| 599 | r = scsi_dh_attach(q, m->hw_handler_name); |
| 600 | } |
| 601 | |
| 602 | if (r < 0) { |
| 603 | ti->error = "error attaching hardware handler"; |
| 604 | dm_put_device(ti, p->path.dev); |
| 605 | goto bad; |
| 606 | } |
| 607 | |
| 608 | if (m->hw_handler_params) { |
| 609 | r = scsi_dh_set_params(q, m->hw_handler_params); |
| 610 | if (r < 0) { |
| 611 | ti->error = "unable to set hardware " |
| 612 | "handler parameters"; |
| 613 | scsi_dh_detach(q); |
| 614 | dm_put_device(ti, p->path.dev); |
| 615 | goto bad; |
| 616 | } |
| 617 | } |
| 618 | } |
| 619 | |
| 620 | r = ps->type->add_path(ps, &p->path, as->argc, as->argv, &ti->error); |
| 621 | if (r) { |
| 622 | dm_put_device(ti, p->path.dev); |
| 623 | goto bad; |
| 624 | } |
| 625 | |
| 626 | return p; |
| 627 | |
| 628 | bad: |
| 629 | free_pgpath(p); |
| 630 | return ERR_PTR(r); |
| 631 | } |
| 632 | |
| 633 | static struct priority_group *parse_priority_group(struct dm_arg_set *as, |
| 634 | struct multipath *m) |
| 635 | { |
| 636 | static struct dm_arg _args[] = { |
| 637 | {1, 1024, "invalid number of paths"}, |
| 638 | {0, 1024, "invalid number of selector args"} |
| 639 | }; |
| 640 | |
| 641 | int r; |
| 642 | unsigned i, nr_selector_args, nr_args; |
| 643 | struct priority_group *pg; |
| 644 | struct dm_target *ti = m->ti; |
| 645 | |
| 646 | if (as->argc < 2) { |
| 647 | as->argc = 0; |
| 648 | ti->error = "not enough priority group arguments"; |
| 649 | return ERR_PTR(-EINVAL); |
| 650 | } |
| 651 | |
| 652 | pg = alloc_priority_group(); |
| 653 | if (!pg) { |
| 654 | ti->error = "couldn't allocate priority group"; |
| 655 | return ERR_PTR(-ENOMEM); |
| 656 | } |
| 657 | pg->m = m; |
| 658 | |
| 659 | r = parse_path_selector(as, pg, ti); |
| 660 | if (r) |
| 661 | goto bad; |
| 662 | |
| 663 | /* |
| 664 | * read the paths |
| 665 | */ |
| 666 | r = dm_read_arg(_args, as, &pg->nr_pgpaths, &ti->error); |
| 667 | if (r) |
| 668 | goto bad; |
| 669 | |
| 670 | r = dm_read_arg(_args + 1, as, &nr_selector_args, &ti->error); |
| 671 | if (r) |
| 672 | goto bad; |
| 673 | |
| 674 | nr_args = 1 + nr_selector_args; |
| 675 | for (i = 0; i < pg->nr_pgpaths; i++) { |
| 676 | struct pgpath *pgpath; |
| 677 | struct dm_arg_set path_args; |
| 678 | |
| 679 | if (as->argc < nr_args) { |
| 680 | ti->error = "not enough path parameters"; |
| 681 | r = -EINVAL; |
| 682 | goto bad; |
| 683 | } |
| 684 | |
| 685 | path_args.argc = nr_args; |
| 686 | path_args.argv = as->argv; |
| 687 | |
| 688 | pgpath = parse_path(&path_args, &pg->ps, ti); |
| 689 | if (IS_ERR(pgpath)) { |
| 690 | r = PTR_ERR(pgpath); |
| 691 | goto bad; |
| 692 | } |
| 693 | |
| 694 | pgpath->pg = pg; |
| 695 | list_add_tail(&pgpath->list, &pg->pgpaths); |
| 696 | dm_consume_args(as, nr_args); |
| 697 | } |
| 698 | |
| 699 | return pg; |
| 700 | |
| 701 | bad: |
| 702 | free_priority_group(pg, ti); |
| 703 | return ERR_PTR(r); |
| 704 | } |
| 705 | |
| 706 | static int parse_hw_handler(struct dm_arg_set *as, struct multipath *m) |
| 707 | { |
| 708 | unsigned hw_argc; |
| 709 | int ret; |
| 710 | struct dm_target *ti = m->ti; |
| 711 | |
| 712 | static struct dm_arg _args[] = { |
| 713 | {0, 1024, "invalid number of hardware handler args"}, |
| 714 | }; |
| 715 | |
| 716 | if (dm_read_arg_group(_args, as, &hw_argc, &ti->error)) |
| 717 | return -EINVAL; |
| 718 | |
| 719 | if (!hw_argc) |
| 720 | return 0; |
| 721 | |
| 722 | m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL); |
| 723 | if (!try_then_request_module(scsi_dh_handler_exist(m->hw_handler_name), |
| 724 | "scsi_dh_%s", m->hw_handler_name)) { |
| 725 | ti->error = "unknown hardware handler type"; |
| 726 | ret = -EINVAL; |
| 727 | goto fail; |
| 728 | } |
| 729 | |
| 730 | if (hw_argc > 1) { |
| 731 | char *p; |
| 732 | int i, j, len = 4; |
| 733 | |
| 734 | for (i = 0; i <= hw_argc - 2; i++) |
| 735 | len += strlen(as->argv[i]) + 1; |
| 736 | p = m->hw_handler_params = kzalloc(len, GFP_KERNEL); |
| 737 | if (!p) { |
| 738 | ti->error = "memory allocation failed"; |
| 739 | ret = -ENOMEM; |
| 740 | goto fail; |
| 741 | } |
| 742 | j = sprintf(p, "%d", hw_argc - 1); |
| 743 | for (i = 0, p+=j+1; i <= hw_argc - 2; i++, p+=j+1) |
| 744 | j = sprintf(p, "%s", as->argv[i]); |
| 745 | } |
| 746 | dm_consume_args(as, hw_argc - 1); |
| 747 | |
| 748 | return 0; |
| 749 | fail: |
| 750 | kfree(m->hw_handler_name); |
| 751 | m->hw_handler_name = NULL; |
| 752 | return ret; |
| 753 | } |
| 754 | |
| 755 | static int parse_features(struct dm_arg_set *as, struct multipath *m) |
| 756 | { |
| 757 | int r; |
| 758 | unsigned argc; |
| 759 | struct dm_target *ti = m->ti; |
| 760 | const char *arg_name; |
| 761 | |
| 762 | static struct dm_arg _args[] = { |
| 763 | {0, 5, "invalid number of feature args"}, |
| 764 | {1, 50, "pg_init_retries must be between 1 and 50"}, |
| 765 | {0, 60000, "pg_init_delay_msecs must be between 0 and 60000"}, |
| 766 | }; |
| 767 | |
| 768 | r = dm_read_arg_group(_args, as, &argc, &ti->error); |
| 769 | if (r) |
| 770 | return -EINVAL; |
| 771 | |
| 772 | if (!argc) |
| 773 | return 0; |
| 774 | |
| 775 | do { |
| 776 | arg_name = dm_shift_arg(as); |
| 777 | argc--; |
| 778 | |
| 779 | if (!strcasecmp(arg_name, "queue_if_no_path")) { |
| 780 | r = queue_if_no_path(m, 1, 0); |
| 781 | continue; |
| 782 | } |
| 783 | |
| 784 | if (!strcasecmp(arg_name, "pg_init_retries") && |
| 785 | (argc >= 1)) { |
| 786 | r = dm_read_arg(_args + 1, as, &m->pg_init_retries, &ti->error); |
| 787 | argc--; |
| 788 | continue; |
| 789 | } |
| 790 | |
| 791 | if (!strcasecmp(arg_name, "pg_init_delay_msecs") && |
| 792 | (argc >= 1)) { |
| 793 | r = dm_read_arg(_args + 2, as, &m->pg_init_delay_msecs, &ti->error); |
| 794 | argc--; |
| 795 | continue; |
| 796 | } |
| 797 | |
| 798 | ti->error = "Unrecognised multipath feature request"; |
| 799 | r = -EINVAL; |
| 800 | } while (argc && !r); |
| 801 | |
| 802 | return r; |
| 803 | } |
| 804 | |
| 805 | static int multipath_ctr(struct dm_target *ti, unsigned int argc, |
| 806 | char **argv) |
| 807 | { |
| 808 | /* target arguments */ |
| 809 | static struct dm_arg _args[] = { |
| 810 | {0, 1024, "invalid number of priority groups"}, |
| 811 | {0, 1024, "invalid initial priority group number"}, |
| 812 | }; |
| 813 | |
| 814 | int r; |
| 815 | struct multipath *m; |
| 816 | struct dm_arg_set as; |
| 817 | unsigned pg_count = 0; |
| 818 | unsigned next_pg_num; |
| 819 | |
| 820 | as.argc = argc; |
| 821 | as.argv = argv; |
| 822 | |
| 823 | m = alloc_multipath(ti); |
| 824 | if (!m) { |
| 825 | ti->error = "can't allocate multipath"; |
| 826 | return -EINVAL; |
| 827 | } |
| 828 | |
| 829 | r = parse_features(&as, m); |
| 830 | if (r) |
| 831 | goto bad; |
| 832 | |
| 833 | r = parse_hw_handler(&as, m); |
| 834 | if (r) |
| 835 | goto bad; |
| 836 | |
| 837 | r = dm_read_arg(_args, &as, &m->nr_priority_groups, &ti->error); |
| 838 | if (r) |
| 839 | goto bad; |
| 840 | |
| 841 | r = dm_read_arg(_args + 1, &as, &next_pg_num, &ti->error); |
| 842 | if (r) |
| 843 | goto bad; |
| 844 | |
| 845 | if ((!m->nr_priority_groups && next_pg_num) || |
| 846 | (m->nr_priority_groups && !next_pg_num)) { |
| 847 | ti->error = "invalid initial priority group"; |
| 848 | r = -EINVAL; |
| 849 | goto bad; |
| 850 | } |
| 851 | |
| 852 | /* parse the priority groups */ |
| 853 | while (as.argc) { |
| 854 | struct priority_group *pg; |
| 855 | |
| 856 | pg = parse_priority_group(&as, m); |
| 857 | if (IS_ERR(pg)) { |
| 858 | r = PTR_ERR(pg); |
| 859 | goto bad; |
| 860 | } |
| 861 | |
| 862 | m->nr_valid_paths += pg->nr_pgpaths; |
| 863 | list_add_tail(&pg->list, &m->priority_groups); |
| 864 | pg_count++; |
| 865 | pg->pg_num = pg_count; |
| 866 | if (!--next_pg_num) |
| 867 | m->next_pg = pg; |
| 868 | } |
| 869 | |
| 870 | if (pg_count != m->nr_priority_groups) { |
| 871 | ti->error = "priority group count mismatch"; |
| 872 | r = -EINVAL; |
| 873 | goto bad; |
| 874 | } |
| 875 | |
| 876 | ti->num_flush_requests = 1; |
| 877 | ti->num_discard_requests = 1; |
| 878 | |
| 879 | return 0; |
| 880 | |
| 881 | bad: |
| 882 | free_multipath(m); |
| 883 | return r; |
| 884 | } |
| 885 | |
| 886 | static void multipath_wait_for_pg_init_completion(struct multipath *m) |
| 887 | { |
| 888 | DECLARE_WAITQUEUE(wait, current); |
| 889 | unsigned long flags; |
| 890 | |
| 891 | add_wait_queue(&m->pg_init_wait, &wait); |
| 892 | |
| 893 | while (1) { |
| 894 | set_current_state(TASK_UNINTERRUPTIBLE); |
| 895 | |
| 896 | spin_lock_irqsave(&m->lock, flags); |
| 897 | if (!m->pg_init_in_progress) { |
| 898 | spin_unlock_irqrestore(&m->lock, flags); |
| 899 | break; |
| 900 | } |
| 901 | spin_unlock_irqrestore(&m->lock, flags); |
| 902 | |
| 903 | io_schedule(); |
| 904 | } |
| 905 | set_current_state(TASK_RUNNING); |
| 906 | |
| 907 | remove_wait_queue(&m->pg_init_wait, &wait); |
| 908 | } |
| 909 | |
| 910 | static void flush_multipath_work(struct multipath *m) |
| 911 | { |
| 912 | flush_workqueue(kmpath_handlerd); |
| 913 | multipath_wait_for_pg_init_completion(m); |
| 914 | flush_workqueue(kmultipathd); |
| 915 | flush_work_sync(&m->trigger_event); |
| 916 | } |
| 917 | |
| 918 | static void multipath_dtr(struct dm_target *ti) |
| 919 | { |
| 920 | struct multipath *m = ti->private; |
| 921 | |
| 922 | flush_multipath_work(m); |
| 923 | free_multipath(m); |
| 924 | } |
| 925 | |
| 926 | /* |
| 927 | * Map cloned requests |
| 928 | */ |
| 929 | static int multipath_map(struct dm_target *ti, struct request *clone, |
| 930 | union map_info *map_context) |
| 931 | { |
| 932 | int r; |
| 933 | struct multipath *m = (struct multipath *) ti->private; |
| 934 | |
| 935 | if (set_mapinfo(m, map_context) < 0) |
| 936 | /* ENOMEM, requeue */ |
| 937 | return DM_MAPIO_REQUEUE; |
| 938 | |
| 939 | clone->cmd_flags |= REQ_FAILFAST_TRANSPORT; |
| 940 | r = map_io(m, clone, map_context, 0); |
| 941 | if (r < 0 || r == DM_MAPIO_REQUEUE) |
| 942 | clear_mapinfo(m, map_context); |
| 943 | |
| 944 | return r; |
| 945 | } |
| 946 | |
| 947 | /* |
| 948 | * Take a path out of use. |
| 949 | */ |
| 950 | static int fail_path(struct pgpath *pgpath) |
| 951 | { |
| 952 | unsigned long flags; |
| 953 | struct multipath *m = pgpath->pg->m; |
| 954 | |
| 955 | spin_lock_irqsave(&m->lock, flags); |
| 956 | |
| 957 | if (!pgpath->is_active) |
| 958 | goto out; |
| 959 | |
| 960 | DMWARN("Failing path %s.", pgpath->path.dev->name); |
| 961 | |
| 962 | pgpath->pg->ps.type->fail_path(&pgpath->pg->ps, &pgpath->path); |
| 963 | pgpath->is_active = 0; |
| 964 | pgpath->fail_count++; |
| 965 | |
| 966 | m->nr_valid_paths--; |
| 967 | |
| 968 | if (pgpath == m->current_pgpath) |
| 969 | m->current_pgpath = NULL; |
| 970 | |
| 971 | dm_path_uevent(DM_UEVENT_PATH_FAILED, m->ti, |
| 972 | pgpath->path.dev->name, m->nr_valid_paths); |
| 973 | |
| 974 | schedule_work(&m->trigger_event); |
| 975 | |
| 976 | out: |
| 977 | spin_unlock_irqrestore(&m->lock, flags); |
| 978 | |
| 979 | return 0; |
| 980 | } |
| 981 | |
| 982 | /* |
| 983 | * Reinstate a previously-failed path |
| 984 | */ |
| 985 | static int reinstate_path(struct pgpath *pgpath) |
| 986 | { |
| 987 | int r = 0; |
| 988 | unsigned long flags; |
| 989 | struct multipath *m = pgpath->pg->m; |
| 990 | |
| 991 | spin_lock_irqsave(&m->lock, flags); |
| 992 | |
| 993 | if (pgpath->is_active) |
| 994 | goto out; |
| 995 | |
| 996 | if (!pgpath->pg->ps.type->reinstate_path) { |
| 997 | DMWARN("Reinstate path not supported by path selector %s", |
| 998 | pgpath->pg->ps.type->name); |
| 999 | r = -EINVAL; |
| 1000 | goto out; |
| 1001 | } |
| 1002 | |
| 1003 | r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path); |
| 1004 | if (r) |
| 1005 | goto out; |
| 1006 | |
| 1007 | pgpath->is_active = 1; |
| 1008 | |
| 1009 | if (!m->nr_valid_paths++ && m->queue_size) { |
| 1010 | m->current_pgpath = NULL; |
| 1011 | queue_work(kmultipathd, &m->process_queued_ios); |
| 1012 | } else if (m->hw_handler_name && (m->current_pg == pgpath->pg)) { |
| 1013 | if (queue_work(kmpath_handlerd, &pgpath->activate_path.work)) |
| 1014 | m->pg_init_in_progress++; |
| 1015 | } |
| 1016 | |
| 1017 | dm_path_uevent(DM_UEVENT_PATH_REINSTATED, m->ti, |
| 1018 | pgpath->path.dev->name, m->nr_valid_paths); |
| 1019 | |
| 1020 | schedule_work(&m->trigger_event); |
| 1021 | |
| 1022 | out: |
| 1023 | spin_unlock_irqrestore(&m->lock, flags); |
| 1024 | |
| 1025 | return r; |
| 1026 | } |
| 1027 | |
| 1028 | /* |
| 1029 | * Fail or reinstate all paths that match the provided struct dm_dev. |
| 1030 | */ |
| 1031 | static int action_dev(struct multipath *m, struct dm_dev *dev, |
| 1032 | action_fn action) |
| 1033 | { |
| 1034 | int r = -EINVAL; |
| 1035 | struct pgpath *pgpath; |
| 1036 | struct priority_group *pg; |
| 1037 | |
| 1038 | list_for_each_entry(pg, &m->priority_groups, list) { |
| 1039 | list_for_each_entry(pgpath, &pg->pgpaths, list) { |
| 1040 | if (pgpath->path.dev == dev) |
| 1041 | r = action(pgpath); |
| 1042 | } |
| 1043 | } |
| 1044 | |
| 1045 | return r; |
| 1046 | } |
| 1047 | |
| 1048 | /* |
| 1049 | * Temporarily try to avoid having to use the specified PG |
| 1050 | */ |
| 1051 | static void bypass_pg(struct multipath *m, struct priority_group *pg, |
| 1052 | int bypassed) |
| 1053 | { |
| 1054 | unsigned long flags; |
| 1055 | |
| 1056 | spin_lock_irqsave(&m->lock, flags); |
| 1057 | |
| 1058 | pg->bypassed = bypassed; |
| 1059 | m->current_pgpath = NULL; |
| 1060 | m->current_pg = NULL; |
| 1061 | |
| 1062 | spin_unlock_irqrestore(&m->lock, flags); |
| 1063 | |
| 1064 | schedule_work(&m->trigger_event); |
| 1065 | } |
| 1066 | |
| 1067 | /* |
| 1068 | * Switch to using the specified PG from the next I/O that gets mapped |
| 1069 | */ |
| 1070 | static int switch_pg_num(struct multipath *m, const char *pgstr) |
| 1071 | { |
| 1072 | struct priority_group *pg; |
| 1073 | unsigned pgnum; |
| 1074 | unsigned long flags; |
| 1075 | char dummy; |
| 1076 | |
| 1077 | if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum || |
| 1078 | (pgnum > m->nr_priority_groups)) { |
| 1079 | DMWARN("invalid PG number supplied to switch_pg_num"); |
| 1080 | return -EINVAL; |
| 1081 | } |
| 1082 | |
| 1083 | spin_lock_irqsave(&m->lock, flags); |
| 1084 | list_for_each_entry(pg, &m->priority_groups, list) { |
| 1085 | pg->bypassed = 0; |
| 1086 | if (--pgnum) |
| 1087 | continue; |
| 1088 | |
| 1089 | m->current_pgpath = NULL; |
| 1090 | m->current_pg = NULL; |
| 1091 | m->next_pg = pg; |
| 1092 | } |
| 1093 | spin_unlock_irqrestore(&m->lock, flags); |
| 1094 | |
| 1095 | schedule_work(&m->trigger_event); |
| 1096 | return 0; |
| 1097 | } |
| 1098 | |
| 1099 | /* |
| 1100 | * Set/clear bypassed status of a PG. |
| 1101 | * PGs are numbered upwards from 1 in the order they were declared. |
| 1102 | */ |
| 1103 | static int bypass_pg_num(struct multipath *m, const char *pgstr, int bypassed) |
| 1104 | { |
| 1105 | struct priority_group *pg; |
| 1106 | unsigned pgnum; |
| 1107 | char dummy; |
| 1108 | |
| 1109 | if (!pgstr || (sscanf(pgstr, "%u%c", &pgnum, &dummy) != 1) || !pgnum || |
| 1110 | (pgnum > m->nr_priority_groups)) { |
| 1111 | DMWARN("invalid PG number supplied to bypass_pg"); |
| 1112 | return -EINVAL; |
| 1113 | } |
| 1114 | |
| 1115 | list_for_each_entry(pg, &m->priority_groups, list) { |
| 1116 | if (!--pgnum) |
| 1117 | break; |
| 1118 | } |
| 1119 | |
| 1120 | bypass_pg(m, pg, bypassed); |
| 1121 | return 0; |
| 1122 | } |
| 1123 | |
| 1124 | /* |
| 1125 | * Should we retry pg_init immediately? |
| 1126 | */ |
| 1127 | static int pg_init_limit_reached(struct multipath *m, struct pgpath *pgpath) |
| 1128 | { |
| 1129 | unsigned long flags; |
| 1130 | int limit_reached = 0; |
| 1131 | |
| 1132 | spin_lock_irqsave(&m->lock, flags); |
| 1133 | |
| 1134 | if (m->pg_init_count <= m->pg_init_retries) |
| 1135 | m->pg_init_required = 1; |
| 1136 | else |
| 1137 | limit_reached = 1; |
| 1138 | |
| 1139 | spin_unlock_irqrestore(&m->lock, flags); |
| 1140 | |
| 1141 | return limit_reached; |
| 1142 | } |
| 1143 | |
| 1144 | static void pg_init_done(void *data, int errors) |
| 1145 | { |
| 1146 | struct pgpath *pgpath = data; |
| 1147 | struct priority_group *pg = pgpath->pg; |
| 1148 | struct multipath *m = pg->m; |
| 1149 | unsigned long flags; |
| 1150 | unsigned delay_retry = 0; |
| 1151 | |
| 1152 | /* device or driver problems */ |
| 1153 | switch (errors) { |
| 1154 | case SCSI_DH_OK: |
| 1155 | break; |
| 1156 | case SCSI_DH_NOSYS: |
| 1157 | if (!m->hw_handler_name) { |
| 1158 | errors = 0; |
| 1159 | break; |
| 1160 | } |
| 1161 | DMERR("Could not failover the device: Handler scsi_dh_%s " |
| 1162 | "Error %d.", m->hw_handler_name, errors); |
| 1163 | /* |
| 1164 | * Fail path for now, so we do not ping pong |
| 1165 | */ |
| 1166 | fail_path(pgpath); |
| 1167 | break; |
| 1168 | case SCSI_DH_DEV_TEMP_BUSY: |
| 1169 | /* |
| 1170 | * Probably doing something like FW upgrade on the |
| 1171 | * controller so try the other pg. |
| 1172 | */ |
| 1173 | bypass_pg(m, pg, 1); |
| 1174 | break; |
| 1175 | case SCSI_DH_RETRY: |
| 1176 | /* Wait before retrying. */ |
| 1177 | delay_retry = 1; |
| 1178 | case SCSI_DH_IMM_RETRY: |
| 1179 | case SCSI_DH_RES_TEMP_UNAVAIL: |
| 1180 | if (pg_init_limit_reached(m, pgpath)) |
| 1181 | fail_path(pgpath); |
| 1182 | errors = 0; |
| 1183 | break; |
| 1184 | default: |
| 1185 | /* |
| 1186 | * We probably do not want to fail the path for a device |
| 1187 | * error, but this is what the old dm did. In future |
| 1188 | * patches we can do more advanced handling. |
| 1189 | */ |
| 1190 | fail_path(pgpath); |
| 1191 | } |
| 1192 | |
| 1193 | spin_lock_irqsave(&m->lock, flags); |
| 1194 | if (errors) { |
| 1195 | if (pgpath == m->current_pgpath) { |
| 1196 | DMERR("Could not failover device. Error %d.", errors); |
| 1197 | m->current_pgpath = NULL; |
| 1198 | m->current_pg = NULL; |
| 1199 | } |
| 1200 | } else if (!m->pg_init_required) |
| 1201 | pg->bypassed = 0; |
| 1202 | |
| 1203 | if (--m->pg_init_in_progress) |
| 1204 | /* Activations of other paths are still on going */ |
| 1205 | goto out; |
| 1206 | |
| 1207 | if (!m->pg_init_required) |
| 1208 | m->queue_io = 0; |
| 1209 | |
| 1210 | m->pg_init_delay_retry = delay_retry; |
| 1211 | queue_work(kmultipathd, &m->process_queued_ios); |
| 1212 | |
| 1213 | /* |
| 1214 | * Wake up any thread waiting to suspend. |
| 1215 | */ |
| 1216 | wake_up(&m->pg_init_wait); |
| 1217 | |
| 1218 | out: |
| 1219 | spin_unlock_irqrestore(&m->lock, flags); |
| 1220 | } |
| 1221 | |
| 1222 | static void activate_path(struct work_struct *work) |
| 1223 | { |
| 1224 | struct pgpath *pgpath = |
| 1225 | container_of(work, struct pgpath, activate_path.work); |
| 1226 | |
| 1227 | scsi_dh_activate(bdev_get_queue(pgpath->path.dev->bdev), |
| 1228 | pg_init_done, pgpath); |
| 1229 | } |
| 1230 | |
| 1231 | /* |
| 1232 | * end_io handling |
| 1233 | */ |
| 1234 | static int do_end_io(struct multipath *m, struct request *clone, |
| 1235 | int error, struct dm_mpath_io *mpio) |
| 1236 | { |
| 1237 | /* |
| 1238 | * We don't queue any clone request inside the multipath target |
| 1239 | * during end I/O handling, since those clone requests don't have |
| 1240 | * bio clones. If we queue them inside the multipath target, |
| 1241 | * we need to make bio clones, that requires memory allocation. |
| 1242 | * (See drivers/md/dm.c:end_clone_bio() about why the clone requests |
| 1243 | * don't have bio clones.) |
| 1244 | * Instead of queueing the clone request here, we queue the original |
| 1245 | * request into dm core, which will remake a clone request and |
| 1246 | * clone bios for it and resubmit it later. |
| 1247 | */ |
| 1248 | int r = DM_ENDIO_REQUEUE; |
| 1249 | unsigned long flags; |
| 1250 | |
| 1251 | if (!error && !clone->errors) |
| 1252 | return 0; /* I/O complete */ |
| 1253 | |
| 1254 | if (error == -EOPNOTSUPP || error == -EREMOTEIO || error == -EILSEQ) |
| 1255 | return error; |
| 1256 | |
| 1257 | if (mpio->pgpath) |
| 1258 | fail_path(mpio->pgpath); |
| 1259 | |
| 1260 | spin_lock_irqsave(&m->lock, flags); |
| 1261 | if (!m->nr_valid_paths) { |
| 1262 | if (!m->queue_if_no_path) { |
| 1263 | if (!__must_push_back(m)) |
| 1264 | r = -EIO; |
| 1265 | } else { |
| 1266 | if (error == -EBADE) |
| 1267 | r = error; |
| 1268 | } |
| 1269 | } |
| 1270 | spin_unlock_irqrestore(&m->lock, flags); |
| 1271 | |
| 1272 | return r; |
| 1273 | } |
| 1274 | |
| 1275 | static int multipath_end_io(struct dm_target *ti, struct request *clone, |
| 1276 | int error, union map_info *map_context) |
| 1277 | { |
| 1278 | struct multipath *m = ti->private; |
| 1279 | struct dm_mpath_io *mpio = map_context->ptr; |
| 1280 | struct pgpath *pgpath = mpio->pgpath; |
| 1281 | struct path_selector *ps; |
| 1282 | int r; |
| 1283 | |
| 1284 | BUG_ON(!mpio); |
| 1285 | |
| 1286 | r = do_end_io(m, clone, error, mpio); |
| 1287 | if (pgpath) { |
| 1288 | ps = &pgpath->pg->ps; |
| 1289 | if (ps->type->end_io) |
| 1290 | ps->type->end_io(ps, &pgpath->path, mpio->nr_bytes); |
| 1291 | } |
| 1292 | clear_mapinfo(m, map_context); |
| 1293 | |
| 1294 | return r; |
| 1295 | } |
| 1296 | |
| 1297 | /* |
| 1298 | * Suspend can't complete until all the I/O is processed so if |
| 1299 | * the last path fails we must error any remaining I/O. |
| 1300 | * Note that if the freeze_bdev fails while suspending, the |
| 1301 | * queue_if_no_path state is lost - userspace should reset it. |
| 1302 | */ |
| 1303 | static void multipath_presuspend(struct dm_target *ti) |
| 1304 | { |
| 1305 | struct multipath *m = (struct multipath *) ti->private; |
| 1306 | |
| 1307 | queue_if_no_path(m, 0, 1); |
| 1308 | } |
| 1309 | |
| 1310 | static void multipath_postsuspend(struct dm_target *ti) |
| 1311 | { |
| 1312 | struct multipath *m = ti->private; |
| 1313 | |
| 1314 | mutex_lock(&m->work_mutex); |
| 1315 | flush_multipath_work(m); |
| 1316 | mutex_unlock(&m->work_mutex); |
| 1317 | } |
| 1318 | |
| 1319 | /* |
| 1320 | * Restore the queue_if_no_path setting. |
| 1321 | */ |
| 1322 | static void multipath_resume(struct dm_target *ti) |
| 1323 | { |
| 1324 | struct multipath *m = (struct multipath *) ti->private; |
| 1325 | unsigned long flags; |
| 1326 | |
| 1327 | spin_lock_irqsave(&m->lock, flags); |
| 1328 | m->queue_if_no_path = m->saved_queue_if_no_path; |
| 1329 | spin_unlock_irqrestore(&m->lock, flags); |
| 1330 | } |
| 1331 | |
| 1332 | /* |
| 1333 | * Info output has the following format: |
| 1334 | * num_multipath_feature_args [multipath_feature_args]* |
| 1335 | * num_handler_status_args [handler_status_args]* |
| 1336 | * num_groups init_group_number |
| 1337 | * [A|D|E num_ps_status_args [ps_status_args]* |
| 1338 | * num_paths num_selector_args |
| 1339 | * [path_dev A|F fail_count [selector_args]* ]+ ]+ |
| 1340 | * |
| 1341 | * Table output has the following format (identical to the constructor string): |
| 1342 | * num_feature_args [features_args]* |
| 1343 | * num_handler_args hw_handler [hw_handler_args]* |
| 1344 | * num_groups init_group_number |
| 1345 | * [priority selector-name num_ps_args [ps_args]* |
| 1346 | * num_paths num_selector_args [path_dev [selector_args]* ]+ ]+ |
| 1347 | */ |
| 1348 | static int multipath_status(struct dm_target *ti, status_type_t type, |
| 1349 | char *result, unsigned int maxlen) |
| 1350 | { |
| 1351 | int sz = 0; |
| 1352 | unsigned long flags; |
| 1353 | struct multipath *m = (struct multipath *) ti->private; |
| 1354 | struct priority_group *pg; |
| 1355 | struct pgpath *p; |
| 1356 | unsigned pg_num; |
| 1357 | char state; |
| 1358 | |
| 1359 | spin_lock_irqsave(&m->lock, flags); |
| 1360 | |
| 1361 | /* Features */ |
| 1362 | if (type == STATUSTYPE_INFO) |
| 1363 | DMEMIT("2 %u %u ", m->queue_size, m->pg_init_count); |
| 1364 | else { |
| 1365 | DMEMIT("%u ", m->queue_if_no_path + |
| 1366 | (m->pg_init_retries > 0) * 2 + |
| 1367 | (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) * 2); |
| 1368 | if (m->queue_if_no_path) |
| 1369 | DMEMIT("queue_if_no_path "); |
| 1370 | if (m->pg_init_retries) |
| 1371 | DMEMIT("pg_init_retries %u ", m->pg_init_retries); |
| 1372 | if (m->pg_init_delay_msecs != DM_PG_INIT_DELAY_DEFAULT) |
| 1373 | DMEMIT("pg_init_delay_msecs %u ", m->pg_init_delay_msecs); |
| 1374 | } |
| 1375 | |
| 1376 | if (!m->hw_handler_name || type == STATUSTYPE_INFO) |
| 1377 | DMEMIT("0 "); |
| 1378 | else |
| 1379 | DMEMIT("1 %s ", m->hw_handler_name); |
| 1380 | |
| 1381 | DMEMIT("%u ", m->nr_priority_groups); |
| 1382 | |
| 1383 | if (m->next_pg) |
| 1384 | pg_num = m->next_pg->pg_num; |
| 1385 | else if (m->current_pg) |
| 1386 | pg_num = m->current_pg->pg_num; |
| 1387 | else |
| 1388 | pg_num = (m->nr_priority_groups ? 1 : 0); |
| 1389 | |
| 1390 | DMEMIT("%u ", pg_num); |
| 1391 | |
| 1392 | switch (type) { |
| 1393 | case STATUSTYPE_INFO: |
| 1394 | list_for_each_entry(pg, &m->priority_groups, list) { |
| 1395 | if (pg->bypassed) |
| 1396 | state = 'D'; /* Disabled */ |
| 1397 | else if (pg == m->current_pg) |
| 1398 | state = 'A'; /* Currently Active */ |
| 1399 | else |
| 1400 | state = 'E'; /* Enabled */ |
| 1401 | |
| 1402 | DMEMIT("%c ", state); |
| 1403 | |
| 1404 | if (pg->ps.type->status) |
| 1405 | sz += pg->ps.type->status(&pg->ps, NULL, type, |
| 1406 | result + sz, |
| 1407 | maxlen - sz); |
| 1408 | else |
| 1409 | DMEMIT("0 "); |
| 1410 | |
| 1411 | DMEMIT("%u %u ", pg->nr_pgpaths, |
| 1412 | pg->ps.type->info_args); |
| 1413 | |
| 1414 | list_for_each_entry(p, &pg->pgpaths, list) { |
| 1415 | DMEMIT("%s %s %u ", p->path.dev->name, |
| 1416 | p->is_active ? "A" : "F", |
| 1417 | p->fail_count); |
| 1418 | if (pg->ps.type->status) |
| 1419 | sz += pg->ps.type->status(&pg->ps, |
| 1420 | &p->path, type, result + sz, |
| 1421 | maxlen - sz); |
| 1422 | } |
| 1423 | } |
| 1424 | break; |
| 1425 | |
| 1426 | case STATUSTYPE_TABLE: |
| 1427 | list_for_each_entry(pg, &m->priority_groups, list) { |
| 1428 | DMEMIT("%s ", pg->ps.type->name); |
| 1429 | |
| 1430 | if (pg->ps.type->status) |
| 1431 | sz += pg->ps.type->status(&pg->ps, NULL, type, |
| 1432 | result + sz, |
| 1433 | maxlen - sz); |
| 1434 | else |
| 1435 | DMEMIT("0 "); |
| 1436 | |
| 1437 | DMEMIT("%u %u ", pg->nr_pgpaths, |
| 1438 | pg->ps.type->table_args); |
| 1439 | |
| 1440 | list_for_each_entry(p, &pg->pgpaths, list) { |
| 1441 | DMEMIT("%s ", p->path.dev->name); |
| 1442 | if (pg->ps.type->status) |
| 1443 | sz += pg->ps.type->status(&pg->ps, |
| 1444 | &p->path, type, result + sz, |
| 1445 | maxlen - sz); |
| 1446 | } |
| 1447 | } |
| 1448 | break; |
| 1449 | } |
| 1450 | |
| 1451 | spin_unlock_irqrestore(&m->lock, flags); |
| 1452 | |
| 1453 | return 0; |
| 1454 | } |
| 1455 | |
| 1456 | static int multipath_message(struct dm_target *ti, unsigned argc, char **argv) |
| 1457 | { |
| 1458 | int r = -EINVAL; |
| 1459 | struct dm_dev *dev; |
| 1460 | struct multipath *m = (struct multipath *) ti->private; |
| 1461 | action_fn action; |
| 1462 | |
| 1463 | mutex_lock(&m->work_mutex); |
| 1464 | |
| 1465 | if (dm_suspended(ti)) { |
| 1466 | r = -EBUSY; |
| 1467 | goto out; |
| 1468 | } |
| 1469 | |
| 1470 | if (argc == 1) { |
| 1471 | if (!strcasecmp(argv[0], "queue_if_no_path")) { |
| 1472 | r = queue_if_no_path(m, 1, 0); |
| 1473 | goto out; |
| 1474 | } else if (!strcasecmp(argv[0], "fail_if_no_path")) { |
| 1475 | r = queue_if_no_path(m, 0, 0); |
| 1476 | goto out; |
| 1477 | } |
| 1478 | } |
| 1479 | |
| 1480 | if (argc != 2) { |
| 1481 | DMWARN("Unrecognised multipath message received."); |
| 1482 | goto out; |
| 1483 | } |
| 1484 | |
| 1485 | if (!strcasecmp(argv[0], "disable_group")) { |
| 1486 | r = bypass_pg_num(m, argv[1], 1); |
| 1487 | goto out; |
| 1488 | } else if (!strcasecmp(argv[0], "enable_group")) { |
| 1489 | r = bypass_pg_num(m, argv[1], 0); |
| 1490 | goto out; |
| 1491 | } else if (!strcasecmp(argv[0], "switch_group")) { |
| 1492 | r = switch_pg_num(m, argv[1]); |
| 1493 | goto out; |
| 1494 | } else if (!strcasecmp(argv[0], "reinstate_path")) |
| 1495 | action = reinstate_path; |
| 1496 | else if (!strcasecmp(argv[0], "fail_path")) |
| 1497 | action = fail_path; |
| 1498 | else { |
| 1499 | DMWARN("Unrecognised multipath message received."); |
| 1500 | goto out; |
| 1501 | } |
| 1502 | |
| 1503 | r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev); |
| 1504 | if (r) { |
| 1505 | DMWARN("message: error getting device %s", |
| 1506 | argv[1]); |
| 1507 | goto out; |
| 1508 | } |
| 1509 | |
| 1510 | r = action_dev(m, dev, action); |
| 1511 | |
| 1512 | dm_put_device(ti, dev); |
| 1513 | |
| 1514 | out: |
| 1515 | mutex_unlock(&m->work_mutex); |
| 1516 | return r; |
| 1517 | } |
| 1518 | |
| 1519 | static int multipath_ioctl(struct dm_target *ti, unsigned int cmd, |
| 1520 | unsigned long arg) |
| 1521 | { |
| 1522 | struct multipath *m = ti->private; |
| 1523 | struct block_device *bdev; |
| 1524 | fmode_t mode; |
| 1525 | unsigned long flags; |
| 1526 | int r; |
| 1527 | |
| 1528 | again: |
| 1529 | bdev = NULL; |
| 1530 | mode = 0; |
| 1531 | r = 0; |
| 1532 | |
| 1533 | spin_lock_irqsave(&m->lock, flags); |
| 1534 | |
| 1535 | if (!m->current_pgpath) |
| 1536 | __choose_pgpath(m, 0); |
| 1537 | |
| 1538 | if (m->current_pgpath) { |
| 1539 | bdev = m->current_pgpath->path.dev->bdev; |
| 1540 | mode = m->current_pgpath->path.dev->mode; |
| 1541 | } |
| 1542 | |
| 1543 | if (m->queue_io) |
| 1544 | r = -EAGAIN; |
| 1545 | else if (!bdev) |
| 1546 | r = -EIO; |
| 1547 | |
| 1548 | spin_unlock_irqrestore(&m->lock, flags); |
| 1549 | |
| 1550 | /* |
| 1551 | * Only pass ioctls through if the device sizes match exactly. |
| 1552 | */ |
| 1553 | if (!r && ti->len != i_size_read(bdev->bd_inode) >> SECTOR_SHIFT) |
| 1554 | r = scsi_verify_blk_ioctl(NULL, cmd); |
| 1555 | |
| 1556 | if (r == -EAGAIN && !fatal_signal_pending(current)) { |
| 1557 | queue_work(kmultipathd, &m->process_queued_ios); |
| 1558 | msleep(10); |
| 1559 | goto again; |
| 1560 | } |
| 1561 | |
| 1562 | return r ? : __blkdev_driver_ioctl(bdev, mode, cmd, arg); |
| 1563 | } |
| 1564 | |
| 1565 | static int multipath_iterate_devices(struct dm_target *ti, |
| 1566 | iterate_devices_callout_fn fn, void *data) |
| 1567 | { |
| 1568 | struct multipath *m = ti->private; |
| 1569 | struct priority_group *pg; |
| 1570 | struct pgpath *p; |
| 1571 | int ret = 0; |
| 1572 | |
| 1573 | list_for_each_entry(pg, &m->priority_groups, list) { |
| 1574 | list_for_each_entry(p, &pg->pgpaths, list) { |
| 1575 | ret = fn(ti, p->path.dev, ti->begin, ti->len, data); |
| 1576 | if (ret) |
| 1577 | goto out; |
| 1578 | } |
| 1579 | } |
| 1580 | |
| 1581 | out: |
| 1582 | return ret; |
| 1583 | } |
| 1584 | |
| 1585 | static int __pgpath_busy(struct pgpath *pgpath) |
| 1586 | { |
| 1587 | struct request_queue *q = bdev_get_queue(pgpath->path.dev->bdev); |
| 1588 | |
| 1589 | return dm_underlying_device_busy(q); |
| 1590 | } |
| 1591 | |
| 1592 | /* |
| 1593 | * We return "busy", only when we can map I/Os but underlying devices |
| 1594 | * are busy (so even if we map I/Os now, the I/Os will wait on |
| 1595 | * the underlying queue). |
| 1596 | * In other words, if we want to kill I/Os or queue them inside us |
| 1597 | * due to map unavailability, we don't return "busy". Otherwise, |
| 1598 | * dm core won't give us the I/Os and we can't do what we want. |
| 1599 | */ |
| 1600 | static int multipath_busy(struct dm_target *ti) |
| 1601 | { |
| 1602 | int busy = 0, has_active = 0; |
| 1603 | struct multipath *m = ti->private; |
| 1604 | struct priority_group *pg; |
| 1605 | struct pgpath *pgpath; |
| 1606 | unsigned long flags; |
| 1607 | |
| 1608 | spin_lock_irqsave(&m->lock, flags); |
| 1609 | |
| 1610 | /* Guess which priority_group will be used at next mapping time */ |
| 1611 | if (unlikely(!m->current_pgpath && m->next_pg)) |
| 1612 | pg = m->next_pg; |
| 1613 | else if (likely(m->current_pg)) |
| 1614 | pg = m->current_pg; |
| 1615 | else |
| 1616 | /* |
| 1617 | * We don't know which pg will be used at next mapping time. |
| 1618 | * We don't call __choose_pgpath() here to avoid to trigger |
| 1619 | * pg_init just by busy checking. |
| 1620 | * So we don't know whether underlying devices we will be using |
| 1621 | * at next mapping time are busy or not. Just try mapping. |
| 1622 | */ |
| 1623 | goto out; |
| 1624 | |
| 1625 | /* |
| 1626 | * If there is one non-busy active path at least, the path selector |
| 1627 | * will be able to select it. So we consider such a pg as not busy. |
| 1628 | */ |
| 1629 | busy = 1; |
| 1630 | list_for_each_entry(pgpath, &pg->pgpaths, list) |
| 1631 | if (pgpath->is_active) { |
| 1632 | has_active = 1; |
| 1633 | |
| 1634 | if (!__pgpath_busy(pgpath)) { |
| 1635 | busy = 0; |
| 1636 | break; |
| 1637 | } |
| 1638 | } |
| 1639 | |
| 1640 | if (!has_active) |
| 1641 | /* |
| 1642 | * No active path in this pg, so this pg won't be used and |
| 1643 | * the current_pg will be changed at next mapping time. |
| 1644 | * We need to try mapping to determine it. |
| 1645 | */ |
| 1646 | busy = 0; |
| 1647 | |
| 1648 | out: |
| 1649 | spin_unlock_irqrestore(&m->lock, flags); |
| 1650 | |
| 1651 | return busy; |
| 1652 | } |
| 1653 | |
| 1654 | /*----------------------------------------------------------------- |
| 1655 | * Module setup |
| 1656 | *---------------------------------------------------------------*/ |
| 1657 | static struct target_type multipath_target = { |
| 1658 | .name = "multipath", |
| 1659 | .version = {1, 4, 0}, |
| 1660 | .module = THIS_MODULE, |
| 1661 | .ctr = multipath_ctr, |
| 1662 | .dtr = multipath_dtr, |
| 1663 | .map_rq = multipath_map, |
| 1664 | .rq_end_io = multipath_end_io, |
| 1665 | .presuspend = multipath_presuspend, |
| 1666 | .postsuspend = multipath_postsuspend, |
| 1667 | .resume = multipath_resume, |
| 1668 | .status = multipath_status, |
| 1669 | .message = multipath_message, |
| 1670 | .ioctl = multipath_ioctl, |
| 1671 | .iterate_devices = multipath_iterate_devices, |
| 1672 | .busy = multipath_busy, |
| 1673 | }; |
| 1674 | |
| 1675 | static int __init dm_multipath_init(void) |
| 1676 | { |
| 1677 | int r; |
| 1678 | |
| 1679 | /* allocate a slab for the dm_ios */ |
| 1680 | _mpio_cache = KMEM_CACHE(dm_mpath_io, 0); |
| 1681 | if (!_mpio_cache) |
| 1682 | return -ENOMEM; |
| 1683 | |
| 1684 | r = dm_register_target(&multipath_target); |
| 1685 | if (r < 0) { |
| 1686 | DMERR("register failed %d", r); |
| 1687 | kmem_cache_destroy(_mpio_cache); |
| 1688 | return -EINVAL; |
| 1689 | } |
| 1690 | |
| 1691 | kmultipathd = alloc_workqueue("kmpathd", WQ_MEM_RECLAIM, 0); |
| 1692 | if (!kmultipathd) { |
| 1693 | DMERR("failed to create workqueue kmpathd"); |
| 1694 | dm_unregister_target(&multipath_target); |
| 1695 | kmem_cache_destroy(_mpio_cache); |
| 1696 | return -ENOMEM; |
| 1697 | } |
| 1698 | |
| 1699 | /* |
| 1700 | * A separate workqueue is used to handle the device handlers |
| 1701 | * to avoid overloading existing workqueue. Overloading the |
| 1702 | * old workqueue would also create a bottleneck in the |
| 1703 | * path of the storage hardware device activation. |
| 1704 | */ |
| 1705 | kmpath_handlerd = alloc_ordered_workqueue("kmpath_handlerd", |
| 1706 | WQ_MEM_RECLAIM); |
| 1707 | if (!kmpath_handlerd) { |
| 1708 | DMERR("failed to create workqueue kmpath_handlerd"); |
| 1709 | destroy_workqueue(kmultipathd); |
| 1710 | dm_unregister_target(&multipath_target); |
| 1711 | kmem_cache_destroy(_mpio_cache); |
| 1712 | return -ENOMEM; |
| 1713 | } |
| 1714 | |
| 1715 | DMINFO("version %u.%u.%u loaded", |
| 1716 | multipath_target.version[0], multipath_target.version[1], |
| 1717 | multipath_target.version[2]); |
| 1718 | |
| 1719 | return r; |
| 1720 | } |
| 1721 | |
| 1722 | static void __exit dm_multipath_exit(void) |
| 1723 | { |
| 1724 | destroy_workqueue(kmpath_handlerd); |
| 1725 | destroy_workqueue(kmultipathd); |
| 1726 | |
| 1727 | dm_unregister_target(&multipath_target); |
| 1728 | kmem_cache_destroy(_mpio_cache); |
| 1729 | } |
| 1730 | |
| 1731 | module_init(dm_multipath_init); |
| 1732 | module_exit(dm_multipath_exit); |
| 1733 | |
| 1734 | MODULE_DESCRIPTION(DM_NAME " multipath target"); |
| 1735 | MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>"); |
| 1736 | MODULE_LICENSE("GPL"); |