1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 1991, 1992 Linus Torvalds 4 * Copyright (C) 1994, Karl Keyte: Added support for disk statistics 5 * Elevator latency, (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE 6 * Queue request tables / lock, selectable elevator, Jens Axboe <axboe@suse.de> 7 * kernel-doc documentation started by NeilBrown <neilb@cse.unsw.edu.au> 8 * - July2000 9 * bio rewrite, highmem i/o, etc, Jens Axboe <axboe@suse.de> - may 2001 10 */ 11 12 /* 13 * This handles all read/write requests to block devices 14 */ 15 #include <linux/kernel.h> 16 #include <linux/module.h> 17 #include <linux/bio.h> 18 #include <linux/blkdev.h> 19 #include <linux/blk-pm.h> 20 #include <linux/blk-integrity.h> 21 #include <linux/highmem.h> 22 #include <linux/mm.h> 23 #include <linux/pagemap.h> 24 #include <linux/kernel_stat.h> 25 #include <linux/string.h> 26 #include <linux/init.h> 27 #include <linux/completion.h> 28 #include <linux/slab.h> 29 #include <linux/swap.h> 30 #include <linux/writeback.h> 31 #include <linux/task_io_accounting_ops.h> 32 #include <linux/fault-inject.h> 33 #include <linux/list_sort.h> 34 #include <linux/delay.h> 35 #include <linux/ratelimit.h> 36 #include <linux/pm_runtime.h> 37 #include <linux/t10-pi.h> 38 #include <linux/debugfs.h> 39 #include <linux/bpf.h> 40 #include <linux/part_stat.h> 41 #include <linux/sched/sysctl.h> 42 #include <linux/blk-crypto.h> 43 44 #define CREATE_TRACE_POINTS 45 #include <trace/events/block.h> 46 47 #include "blk.h" 48 #include "blk-mq-sched.h" 49 #include "blk-pm.h" 50 #include "blk-cgroup.h" 51 #include "blk-throttle.h" 52 #include "blk-ioprio.h" 53 #include "error-injection.h" 54 55 struct dentry *blk_debugfs_root; 56 57 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap); 58 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); 59 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); 60 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split); 61 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug); 62 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_insert); 63 64 static DEFINE_IDA(blk_queue_ida); 65 66 /* 67 * For queue allocation 68 */ 69 static struct kmem_cache *blk_requestq_cachep; 70 71 /* 72 * Controlling structure to kblockd 73 */ 74 static struct workqueue_struct *kblockd_workqueue; 75 76 /** 77 * blk_queue_flag_set - atomically set a queue flag 78 * @flag: flag to be set 79 * @q: request queue 80 */ 81 void blk_queue_flag_set(unsigned int flag, struct request_queue *q) 82 { 83 set_bit(flag, &q->queue_flags); 84 } 85 EXPORT_SYMBOL(blk_queue_flag_set); 86 87 /** 88 * blk_queue_flag_clear - atomically clear a queue flag 89 * @flag: flag to be cleared 90 * @q: request queue 91 */ 92 void blk_queue_flag_clear(unsigned int flag, struct request_queue *q) 93 { 94 clear_bit(flag, &q->queue_flags); 95 } 96 EXPORT_SYMBOL(blk_queue_flag_clear); 97 98 #define REQ_OP_NAME(name) [REQ_OP_##name] = #name 99 static const char *const blk_op_name[] = { 100 REQ_OP_NAME(READ), 101 REQ_OP_NAME(WRITE), 102 REQ_OP_NAME(FLUSH), 103 REQ_OP_NAME(DISCARD), 104 REQ_OP_NAME(SECURE_ERASE), 105 REQ_OP_NAME(ZONE_RESET), 106 REQ_OP_NAME(ZONE_RESET_ALL), 107 REQ_OP_NAME(ZONE_OPEN), 108 REQ_OP_NAME(ZONE_CLOSE), 109 REQ_OP_NAME(ZONE_FINISH), 110 REQ_OP_NAME(ZONE_APPEND), 111 REQ_OP_NAME(WRITE_ZEROES), 112 REQ_OP_NAME(DRV_IN), 113 REQ_OP_NAME(DRV_OUT), 114 }; 115 #undef REQ_OP_NAME 116 117 /** 118 * blk_op_str - Return the string "name" for an operation REQ_OP_name. 119 * @op: a request operation. 120 * 121 * Convert a request operation REQ_OP_name into the string "name". Useful for 122 * debugging and tracing BIOs and requests. For an invalid request operation 123 * code, the string "UNKNOWN" is returned. 124 */ 125 inline const char *blk_op_str(enum req_op op) 126 { 127 const char *op_str = "UNKNOWN"; 128 129 if (op < ARRAY_SIZE(blk_op_name) && blk_op_name[op]) 130 op_str = blk_op_name[op]; 131 132 return op_str; 133 } 134 EXPORT_SYMBOL_GPL(blk_op_str); 135 136 enum req_op str_to_blk_op(const char *op) 137 { 138 int i; 139 140 for (i = 0; i < ARRAY_SIZE(blk_op_name); i++) 141 if (blk_op_name[i] && !strcmp(blk_op_name[i], op)) 142 return (enum req_op)i; 143 return REQ_OP_LAST; 144 } 145 146 #define ENT(_tag, _errno, _desc) \ 147 [BLK_STS_##_tag] = { \ 148 .errno = _errno, \ 149 .tag = __stringify(_tag), \ 150 .name = _desc, \ 151 } 152 static const struct { 153 int errno; 154 const char *tag; 155 const char *name; 156 } blk_errors[] = { 157 ENT(OK, 0, ""), 158 ENT(NOTSUPP, -EOPNOTSUPP, "operation not supported"), 159 ENT(TIMEOUT, -ETIMEDOUT, "timeout"), 160 ENT(NOSPC, -ENOSPC, "critical space allocation"), 161 ENT(TRANSPORT, -ENOLINK, "recoverable transport"), 162 ENT(TARGET, -EREMOTEIO, "critical target"), 163 ENT(RESV_CONFLICT, -EBADE, "reservation conflict"), 164 ENT(MEDIUM, -ENODATA, "critical medium"), 165 ENT(PROTECTION, -EILSEQ, "protection"), 166 ENT(RESOURCE, -ENOMEM, "kernel resource"), 167 ENT(DEV_RESOURCE, -EBUSY, "device resource"), 168 ENT(AGAIN, -EAGAIN, "nonblocking retry"), 169 ENT(OFFLINE, -ENODEV, "device offline"), 170 171 /* device mapper special case, should not leak out: */ 172 ENT(DM_REQUEUE, -EREMCHG, "dm internal retry"), 173 174 /* zone device specific errors */ 175 ENT(ZONE_OPEN_RESOURCE, -ETOOMANYREFS, "open zones exceeded"), 176 ENT(ZONE_ACTIVE_RESOURCE, -EOVERFLOW, "active zones exceeded"), 177 178 /* Command duration limit device-side timeout */ 179 ENT(DURATION_LIMIT, -ETIME, "duration limit exceeded"), 180 ENT(INVAL, -EINVAL, "invalid"), 181 182 /* everything else not covered above: */ 183 ENT(IOERR, -EIO, "I/O"), 184 }; 185 #undef ENT 186 187 blk_status_t errno_to_blk_status(int errno) 188 { 189 int i; 190 191 for (i = 0; i < ARRAY_SIZE(blk_errors); i++) { 192 if (blk_errors[i].errno == errno) 193 return (__force blk_status_t)i; 194 } 195 196 return BLK_STS_IOERR; 197 } 198 EXPORT_SYMBOL_GPL(errno_to_blk_status); 199 200 int blk_status_to_errno(blk_status_t status) 201 { 202 int idx = (__force int)status; 203 204 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 205 return -EIO; 206 return blk_errors[idx].errno; 207 } 208 EXPORT_SYMBOL_GPL(blk_status_to_errno); 209 210 const char *blk_status_to_str(blk_status_t status) 211 { 212 int idx = (__force int)status; 213 214 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 215 return "<null>"; 216 return blk_errors[idx].name; 217 } 218 219 const char *blk_status_to_tag(blk_status_t status) 220 { 221 int idx = (__force int)status; 222 223 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors) || !blk_errors[idx].tag)) 224 return "<null>"; 225 return blk_errors[idx].tag; 226 } 227 228 blk_status_t tag_to_blk_status(const char *tag) 229 { 230 int i; 231 232 for (i = 0; i < ARRAY_SIZE(blk_errors); i++) { 233 if (blk_errors[i].tag && 234 !strcmp(blk_errors[i].tag, tag)) 235 return (__force blk_status_t)i; 236 } 237 238 /* 239 * Return BLK_STS_OK for mismatches as this function is intended to 240 * parse error status values. 241 */ 242 return BLK_STS_OK; 243 } 244 245 /** 246 * blk_sync_queue - cancel any pending callbacks on a queue 247 * @q: the queue 248 * 249 * Description: 250 * The block layer may perform asynchronous callback activity 251 * on a queue, such as calling the unplug function after a timeout. 252 * A block device may call blk_sync_queue to ensure that any 253 * such activity is cancelled, thus allowing it to release resources 254 * that the callbacks might use. The caller must already have made sure 255 * that its ->submit_bio will not re-add plugging prior to calling 256 * this function. 257 * 258 * This function does not cancel any asynchronous activity arising 259 * out of elevator or throttling code. That would require elevator_exit() 260 * and blkcg_exit_queue() to be called with queue lock initialized. 261 * 262 */ 263 void blk_sync_queue(struct request_queue *q) 264 { 265 timer_delete_sync(&q->timeout); 266 cancel_work_sync(&q->timeout_work); 267 } 268 EXPORT_SYMBOL(blk_sync_queue); 269 270 /** 271 * blk_set_pm_only - increment pm_only counter 272 * @q: request queue pointer 273 */ 274 void blk_set_pm_only(struct request_queue *q) 275 { 276 atomic_inc(&q->pm_only); 277 } 278 EXPORT_SYMBOL_GPL(blk_set_pm_only); 279 280 void blk_clear_pm_only(struct request_queue *q) 281 { 282 int pm_only; 283 284 pm_only = atomic_dec_return(&q->pm_only); 285 WARN_ON_ONCE(pm_only < 0); 286 if (pm_only == 0) 287 wake_up_all(&q->mq_freeze_wq); 288 } 289 EXPORT_SYMBOL_GPL(blk_clear_pm_only); 290 291 static void blk_free_queue_rcu(struct rcu_head *rcu_head) 292 { 293 struct request_queue *q = container_of(rcu_head, 294 struct request_queue, rcu_head); 295 296 percpu_ref_exit(&q->q_usage_counter); 297 kmem_cache_free(blk_requestq_cachep, q); 298 } 299 300 static void blk_free_queue(struct request_queue *q) 301 { 302 blk_free_queue_stats(q->stats); 303 if (queue_is_mq(q)) 304 blk_mq_release(q); 305 306 ida_free(&blk_queue_ida, q->id); 307 lockdep_unregister_key(&q->io_lock_cls_key); 308 lockdep_unregister_key(&q->q_lock_cls_key); 309 call_rcu(&q->rcu_head, blk_free_queue_rcu); 310 } 311 312 /** 313 * blk_put_queue - decrement the request_queue refcount 314 * @q: the request_queue structure to decrement the refcount for 315 * 316 * Decrements the refcount of the request_queue and free it when the refcount 317 * reaches 0. 318 */ 319 void blk_put_queue(struct request_queue *q) 320 { 321 if (refcount_dec_and_test(&q->refs)) 322 blk_free_queue(q); 323 } 324 EXPORT_SYMBOL(blk_put_queue); 325 326 bool blk_queue_start_drain(struct request_queue *q) 327 { 328 /* 329 * When queue DYING flag is set, we need to block new req 330 * entering queue, so we call blk_freeze_queue_start() to 331 * prevent I/O from crossing blk_queue_enter(). 332 */ 333 bool freeze = __blk_freeze_queue_start(q, current); 334 if (queue_is_mq(q)) 335 blk_mq_wake_waiters(q); 336 /* Make blk_queue_enter() reexamine the DYING flag. */ 337 wake_up_all(&q->mq_freeze_wq); 338 339 return freeze; 340 } 341 342 /** 343 * blk_queue_enter() - try to increase q->q_usage_counter 344 * @q: request queue pointer 345 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PM 346 */ 347 int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) 348 { 349 const bool pm = flags & BLK_MQ_REQ_PM; 350 351 while (!blk_try_enter_queue(q, pm)) { 352 if (flags & BLK_MQ_REQ_NOWAIT) 353 return -EAGAIN; 354 355 /* 356 * read pair of barrier in blk_freeze_queue_start(), we need to 357 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and 358 * reading .mq_freeze_depth or queue dying flag, otherwise the 359 * following wait may never return if the two reads are 360 * reordered. 361 */ 362 smp_rmb(); 363 wait_event(q->mq_freeze_wq, 364 (!q->mq_freeze_depth && 365 blk_pm_resume_queue(pm, q)) || 366 blk_queue_dying(q)); 367 if (blk_queue_dying(q)) 368 return -ENODEV; 369 } 370 371 rwsem_acquire_read(&q->q_lockdep_map, 0, 0, _RET_IP_); 372 rwsem_release(&q->q_lockdep_map, _RET_IP_); 373 return 0; 374 } 375 376 int __bio_queue_enter(struct request_queue *q, struct bio *bio) 377 { 378 while (!blk_try_enter_queue(q, false)) { 379 struct gendisk *disk = bio->bi_bdev->bd_disk; 380 381 if (bio->bi_opf & REQ_NOWAIT) { 382 if (test_bit(GD_DEAD, &disk->state)) 383 goto dead; 384 bio_wouldblock_error(bio); 385 return -EAGAIN; 386 } 387 388 /* 389 * read pair of barrier in blk_freeze_queue_start(), we need to 390 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and 391 * reading .mq_freeze_depth or queue dying flag, otherwise the 392 * following wait may never return if the two reads are 393 * reordered. 394 */ 395 smp_rmb(); 396 wait_event(q->mq_freeze_wq, 397 (!q->mq_freeze_depth && 398 blk_pm_resume_queue(false, q)) || 399 test_bit(GD_DEAD, &disk->state)); 400 if (test_bit(GD_DEAD, &disk->state)) 401 goto dead; 402 } 403 404 rwsem_acquire_read(&q->io_lockdep_map, 0, 0, _RET_IP_); 405 rwsem_release(&q->io_lockdep_map, _RET_IP_); 406 return 0; 407 dead: 408 bio_io_error(bio); 409 return -ENODEV; 410 } 411 412 void blk_queue_exit(struct request_queue *q) 413 { 414 percpu_ref_put(&q->q_usage_counter); 415 } 416 417 static void blk_queue_usage_counter_release(struct percpu_ref *ref) 418 { 419 struct request_queue *q = 420 container_of(ref, struct request_queue, q_usage_counter); 421 422 wake_up_all(&q->mq_freeze_wq); 423 } 424 425 static void blk_rq_timed_out_timer(struct timer_list *t) 426 { 427 struct request_queue *q = timer_container_of(q, t, timeout); 428 429 kblockd_schedule_work(&q->timeout_work); 430 } 431 432 static void blk_timeout_work(struct work_struct *work) 433 { 434 } 435 436 struct request_queue *blk_alloc_queue(struct queue_limits *lim, int node_id) 437 { 438 struct request_queue *q; 439 int error; 440 441 q = kmem_cache_alloc_node(blk_requestq_cachep, GFP_KERNEL | __GFP_ZERO, 442 node_id); 443 if (!q) 444 return ERR_PTR(-ENOMEM); 445 446 q->last_merge = NULL; 447 448 q->id = ida_alloc(&blk_queue_ida, GFP_KERNEL); 449 if (q->id < 0) { 450 error = q->id; 451 goto fail_q; 452 } 453 454 q->stats = blk_alloc_queue_stats(); 455 if (!q->stats) { 456 error = -ENOMEM; 457 goto fail_id; 458 } 459 460 error = blk_set_default_limits(lim); 461 if (error) 462 goto fail_stats; 463 q->limits = *lim; 464 465 q->node = node_id; 466 467 atomic_set(&q->nr_active_requests_shared_tags, 0); 468 469 timer_setup(&q->timeout, blk_rq_timed_out_timer, 0); 470 INIT_WORK(&q->timeout_work, blk_timeout_work); 471 INIT_LIST_HEAD(&q->icq_list); 472 473 refcount_set(&q->refs, 1); 474 mutex_init(&q->debugfs_mutex); 475 mutex_init(&q->elevator_lock); 476 mutex_init(&q->sysfs_lock); 477 mutex_init(&q->limits_lock); 478 mutex_init(&q->rq_qos_mutex); 479 spin_lock_init(&q->queue_lock); 480 481 init_waitqueue_head(&q->mq_freeze_wq); 482 mutex_init(&q->mq_freeze_lock); 483 484 blkg_init_queue(q); 485 486 /* 487 * Init percpu_ref in atomic mode so that it's faster to shutdown. 488 * See blk_register_queue() for details. 489 */ 490 error = percpu_ref_init(&q->q_usage_counter, 491 blk_queue_usage_counter_release, 492 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL); 493 if (error) 494 goto fail_stats; 495 lockdep_register_key(&q->io_lock_cls_key); 496 lockdep_register_key(&q->q_lock_cls_key); 497 lockdep_init_map(&q->io_lockdep_map, "&q->q_usage_counter(io)", 498 &q->io_lock_cls_key, 0); 499 lockdep_init_map(&q->q_lockdep_map, "&q->q_usage_counter(queue)", 500 &q->q_lock_cls_key, 0); 501 502 /* Teach lockdep about lock ordering (reclaim WRT queue freeze lock). */ 503 fs_reclaim_acquire(GFP_KERNEL); 504 rwsem_acquire_read(&q->io_lockdep_map, 0, 0, _RET_IP_); 505 rwsem_release(&q->io_lockdep_map, _RET_IP_); 506 fs_reclaim_release(GFP_KERNEL); 507 508 q->nr_requests = BLKDEV_DEFAULT_RQ; 509 q->async_depth = BLKDEV_DEFAULT_RQ; 510 511 return q; 512 513 fail_stats: 514 blk_free_queue_stats(q->stats); 515 fail_id: 516 ida_free(&blk_queue_ida, q->id); 517 fail_q: 518 kmem_cache_free(blk_requestq_cachep, q); 519 return ERR_PTR(error); 520 } 521 522 /** 523 * blk_get_queue - increment the request_queue refcount 524 * @q: the request_queue structure to increment the refcount for 525 * 526 * Increment the refcount of the request_queue kobject. 527 * 528 * Context: Any context. 529 */ 530 bool blk_get_queue(struct request_queue *q) 531 { 532 if (unlikely(blk_queue_dying(q))) 533 return false; 534 refcount_inc(&q->refs); 535 return true; 536 } 537 EXPORT_SYMBOL(blk_get_queue); 538 539 #ifdef CONFIG_FAIL_MAKE_REQUEST 540 541 static DECLARE_FAULT_ATTR(fail_make_request); 542 543 static int __init setup_fail_make_request(char *str) 544 { 545 return setup_fault_attr(&fail_make_request, str); 546 } 547 __setup("fail_make_request=", setup_fail_make_request); 548 549 bool should_fail_request(struct block_device *part, unsigned int bytes) 550 { 551 return bdev_test_flag(part, BD_MAKE_IT_FAIL) && 552 should_fail(&fail_make_request, bytes); 553 } 554 555 static int __init fail_make_request_debugfs(void) 556 { 557 struct dentry *dir = fault_create_debugfs_attr("fail_make_request", 558 NULL, &fail_make_request); 559 560 return PTR_ERR_OR_ZERO(dir); 561 } 562 563 late_initcall(fail_make_request_debugfs); 564 #endif /* CONFIG_FAIL_MAKE_REQUEST */ 565 566 static inline void bio_check_ro(struct bio *bio) 567 { 568 if (op_is_write(bio_op(bio)) && bdev_read_only(bio->bi_bdev)) { 569 if (op_is_flush(bio->bi_opf) && !bio_sectors(bio)) 570 return; 571 572 if (bdev_test_flag(bio->bi_bdev, BD_RO_WARNED)) 573 return; 574 575 bdev_set_flag(bio->bi_bdev, BD_RO_WARNED); 576 577 /* 578 * Use ioctl to set underlying disk of raid/dm to read-only 579 * will trigger this. 580 */ 581 pr_warn("Trying to write to read-only block-device %pg\n", 582 bio->bi_bdev); 583 } 584 } 585 586 int should_fail_bio(struct bio *bio) 587 { 588 if (should_fail_request(bdev_whole(bio->bi_bdev), bio->bi_iter.bi_size)) 589 return -EIO; 590 return 0; 591 } 592 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO); 593 594 /* 595 * Check whether this bio extends beyond the end of the device or partition. 596 * This may well happen - the kernel calls bread() without checking the size of 597 * the device, e.g., when mounting a file system. 598 */ 599 static inline int bio_check_eod(struct bio *bio) 600 { 601 sector_t maxsector = bdev_nr_sectors(bio->bi_bdev); 602 unsigned int nr_sectors = bio_sectors(bio); 603 604 if (nr_sectors && 605 (nr_sectors > maxsector || 606 bio->bi_iter.bi_sector > maxsector - nr_sectors)) { 607 if (!maxsector) 608 return -EIO; 609 pr_info_ratelimited("%s: attempt to access beyond end of device\n" 610 "%pg: rw=%d, sector=%llu, nr_sectors = %u limit=%llu\n", 611 current->comm, bio->bi_bdev, bio->bi_opf, 612 bio->bi_iter.bi_sector, nr_sectors, maxsector); 613 return -EIO; 614 } 615 return 0; 616 } 617 618 /* 619 * Remap block n of partition p to block n+start(p) of the disk. 620 */ 621 static int blk_partition_remap(struct bio *bio) 622 { 623 struct block_device *p = bio->bi_bdev; 624 625 if (unlikely(should_fail_request(p, bio->bi_iter.bi_size))) 626 return -EIO; 627 if (bio_sectors(bio)) { 628 bio->bi_iter.bi_sector += p->bd_start_sect; 629 trace_block_bio_remap(bio, p->bd_dev, 630 bio->bi_iter.bi_sector - 631 p->bd_start_sect); 632 } 633 bio_set_flag(bio, BIO_REMAPPED); 634 return 0; 635 } 636 637 /* 638 * Check write append to a zoned block device. 639 */ 640 static inline blk_status_t blk_check_zone_append(struct request_queue *q, 641 struct bio *bio) 642 { 643 int nr_sectors = bio_sectors(bio); 644 645 /* Only applicable to zoned block devices */ 646 if (!bdev_is_zoned(bio->bi_bdev)) 647 return BLK_STS_NOTSUPP; 648 649 /* The bio sector must point to the start of a sequential zone */ 650 if (!bdev_is_zone_start(bio->bi_bdev, bio->bi_iter.bi_sector)) 651 return BLK_STS_IOERR; 652 653 /* 654 * Not allowed to cross zone boundaries. Otherwise, the BIO will be 655 * split and could result in non-contiguous sectors being written in 656 * different zones. 657 */ 658 if (nr_sectors > q->limits.chunk_sectors) 659 return BLK_STS_IOERR; 660 661 /* Make sure the BIO is small enough and will not get split */ 662 if (nr_sectors > q->limits.max_zone_append_sectors) 663 return BLK_STS_IOERR; 664 665 bio->bi_opf |= REQ_NOMERGE; 666 667 return BLK_STS_OK; 668 } 669 670 static void __submit_bio(struct bio *bio) 671 { 672 if (!bdev_test_flag(bio->bi_bdev, BD_HAS_SUBMIT_BIO)) { 673 blk_mq_submit_bio(bio); 674 } else if (likely(bio_queue_enter(bio) == 0)) { 675 struct gendisk *disk = bio->bi_bdev->bd_disk; 676 677 if ((bio->bi_opf & REQ_POLLED) && 678 !(disk->queue->limits.features & BLK_FEAT_POLL)) 679 bio_endio_status(bio, BLK_STS_NOTSUPP); 680 else 681 disk->fops->submit_bio(bio); 682 blk_queue_exit(disk->queue); 683 } 684 } 685 686 /* 687 * The loop in this function may be a bit non-obvious, and so deserves some 688 * explanation: 689 * 690 * - Before entering the loop, bio->bi_next is NULL (as all callers ensure 691 * that), so we have a list with a single bio. 692 * - We pretend that we have just taken it off a longer list, so we assign 693 * bio_list to a pointer to the bio_list_on_stack, thus initialising the 694 * bio_list of new bios to be added. ->submit_bio() may indeed add some more 695 * bios through a recursive call to submit_bio_noacct. If it did, we find a 696 * non-NULL value in bio_list and re-enter the loop from the top. 697 * - In this case we really did just take the bio off the top of the list (no 698 * pretending) and so remove it from bio_list, and call into ->submit_bio() 699 * again. 700 * 701 * bio_list_on_stack[0] contains bios submitted by the current ->submit_bio. 702 * bio_list_on_stack[1] contains bios that were submitted before the current 703 * ->submit_bio(), but that haven't been processed yet. 704 */ 705 static void __submit_bio_noacct(struct bio *bio) 706 { 707 struct bio_list bio_list_on_stack[2]; 708 709 BUG_ON(bio->bi_next); 710 711 bio_list_init(&bio_list_on_stack[0]); 712 current->bio_list = bio_list_on_stack; 713 714 do { 715 struct request_queue *q = bdev_get_queue(bio->bi_bdev); 716 struct bio_list lower, same; 717 718 /* 719 * Create a fresh bio_list for all subordinate requests. 720 */ 721 bio_list_on_stack[1] = bio_list_on_stack[0]; 722 bio_list_init(&bio_list_on_stack[0]); 723 724 __submit_bio(bio); 725 726 /* 727 * Sort new bios into those for a lower level and those for the 728 * same level. 729 */ 730 bio_list_init(&lower); 731 bio_list_init(&same); 732 while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL) 733 if (q == bdev_get_queue(bio->bi_bdev)) 734 bio_list_add(&same, bio); 735 else 736 bio_list_add(&lower, bio); 737 738 /* 739 * Now assemble so we handle the lowest level first. 740 */ 741 bio_list_merge(&bio_list_on_stack[0], &lower); 742 bio_list_merge(&bio_list_on_stack[0], &same); 743 bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); 744 } while ((bio = bio_list_pop(&bio_list_on_stack[0]))); 745 746 current->bio_list = NULL; 747 } 748 749 static void __submit_bio_noacct_mq(struct bio *bio) 750 { 751 struct bio_list bio_list[2] = { }; 752 753 current->bio_list = bio_list; 754 755 do { 756 __submit_bio(bio); 757 } while ((bio = bio_list_pop(&bio_list[0]))); 758 759 current->bio_list = NULL; 760 } 761 762 void submit_bio_noacct_nocheck(struct bio *bio, bool split) 763 { 764 if (unlikely(blk_error_inject(bio))) 765 return; 766 767 blk_cgroup_bio_start(bio); 768 769 if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) { 770 trace_block_bio_queue(bio); 771 /* 772 * Now that enqueuing has been traced, we need to trace 773 * completion as well. 774 */ 775 bio_set_flag(bio, BIO_TRACE_COMPLETION); 776 } 777 778 /* 779 * We only want one ->submit_bio to be active at a time, else stack 780 * usage with stacked devices could be a problem. Use current->bio_list 781 * to collect a list of requests submitted by a ->submit_bio method 782 * while it is active, and then process them after it returned. 783 */ 784 if (current->bio_list) { 785 if (split) 786 bio_list_add_head(¤t->bio_list[0], bio); 787 else 788 bio_list_add(¤t->bio_list[0], bio); 789 } else if (!bdev_test_flag(bio->bi_bdev, BD_HAS_SUBMIT_BIO)) { 790 __submit_bio_noacct_mq(bio); 791 } else { 792 __submit_bio_noacct(bio); 793 } 794 } 795 796 static blk_status_t blk_validate_atomic_write_op_size(struct request_queue *q, 797 struct bio *bio) 798 { 799 if (bio->bi_iter.bi_size > queue_atomic_write_unit_max_bytes(q)) 800 return BLK_STS_INVAL; 801 802 if (bio->bi_iter.bi_size % queue_atomic_write_unit_min_bytes(q)) 803 return BLK_STS_INVAL; 804 805 return BLK_STS_OK; 806 } 807 808 /** 809 * submit_bio_noacct - re-submit a bio to the block device layer for I/O 810 * @bio: The bio describing the location in memory and on the device. 811 * 812 * This is a version of submit_bio() that shall only be used for I/O that is 813 * resubmitted to lower level drivers by stacking block drivers. All file 814 * systems and other upper level users of the block layer should use 815 * submit_bio() instead. 816 */ 817 void submit_bio_noacct(struct bio *bio) 818 { 819 struct block_device *bdev = bio->bi_bdev; 820 struct request_queue *q = bdev_get_queue(bdev); 821 blk_status_t status = BLK_STS_IOERR; 822 823 might_sleep(); 824 825 /* 826 * For a REQ_NOWAIT based request, return -EOPNOTSUPP 827 * if queue does not support NOWAIT. 828 */ 829 if ((bio->bi_opf & REQ_NOWAIT) && !bdev_nowait(bdev)) 830 goto not_supported; 831 832 if (bio_has_crypt_ctx(bio)) { 833 if (WARN_ON_ONCE(!bio_has_data(bio))) 834 goto end_io; 835 if (!blk_crypto_supported(bio)) 836 goto not_supported; 837 } 838 839 if (should_fail_bio(bio)) 840 goto end_io; 841 bio_check_ro(bio); 842 if (!bio_flagged(bio, BIO_REMAPPED)) { 843 if (unlikely(bio_check_eod(bio))) 844 goto end_io; 845 if (bdev_is_partition(bdev) && 846 unlikely(blk_partition_remap(bio))) 847 goto end_io; 848 } 849 850 /* 851 * Filter flush bio's early so that bio based drivers without flush 852 * support don't have to worry about them. 853 */ 854 if (op_is_flush(bio->bi_opf)) { 855 if (WARN_ON_ONCE(bio_op(bio) != REQ_OP_WRITE && 856 bio_op(bio) != REQ_OP_ZONE_APPEND)) 857 goto end_io; 858 if (!bdev_write_cache(bdev)) { 859 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA); 860 if (!bio_sectors(bio)) { 861 status = BLK_STS_OK; 862 goto end_io; 863 } 864 } 865 } 866 867 switch (bio_op(bio)) { 868 case REQ_OP_READ: 869 break; 870 case REQ_OP_WRITE: 871 if (bio->bi_opf & REQ_ATOMIC) { 872 status = blk_validate_atomic_write_op_size(q, bio); 873 if (status != BLK_STS_OK) 874 goto end_io; 875 } 876 break; 877 case REQ_OP_FLUSH: 878 /* 879 * REQ_OP_FLUSH can't be submitted through bios, it is only 880 * synthetized in struct request by the flush state machine. 881 */ 882 goto not_supported; 883 case REQ_OP_DISCARD: 884 if (!bdev_max_discard_sectors(bdev)) 885 goto not_supported; 886 break; 887 case REQ_OP_SECURE_ERASE: 888 if (!bdev_max_secure_erase_sectors(bdev)) 889 goto not_supported; 890 break; 891 case REQ_OP_ZONE_APPEND: 892 status = blk_check_zone_append(q, bio); 893 if (status != BLK_STS_OK) 894 goto end_io; 895 break; 896 case REQ_OP_WRITE_ZEROES: 897 if (!q->limits.max_write_zeroes_sectors) 898 goto not_supported; 899 break; 900 case REQ_OP_ZONE_RESET: 901 case REQ_OP_ZONE_OPEN: 902 case REQ_OP_ZONE_CLOSE: 903 case REQ_OP_ZONE_FINISH: 904 case REQ_OP_ZONE_RESET_ALL: 905 if (!bdev_is_zoned(bio->bi_bdev)) 906 goto not_supported; 907 break; 908 case REQ_OP_DRV_IN: 909 case REQ_OP_DRV_OUT: 910 /* 911 * Driver private operations are only used with passthrough 912 * requests. 913 */ 914 fallthrough; 915 default: 916 goto not_supported; 917 } 918 919 if (blk_throtl_bio(bio)) 920 return; 921 submit_bio_noacct_nocheck(bio, false); 922 return; 923 924 not_supported: 925 status = BLK_STS_NOTSUPP; 926 end_io: 927 bio_endio_status(bio, status); 928 } 929 EXPORT_SYMBOL(submit_bio_noacct); 930 931 static void bio_set_ioprio(struct bio *bio) 932 { 933 /* Nobody set ioprio so far? Initialize it based on task's nice value */ 934 if (IOPRIO_PRIO_CLASS(bio->bi_ioprio) == IOPRIO_CLASS_NONE) 935 bio->bi_ioprio = get_current_ioprio(); 936 blkcg_set_ioprio(bio); 937 } 938 939 /** 940 * submit_bio - submit a bio to the block device layer for I/O 941 * @bio: The &struct bio which describes the I/O 942 * 943 * submit_bio() is used to submit I/O requests to block devices. It is passed a 944 * fully set up &struct bio that describes the I/O that needs to be done. The 945 * bio will be sent to the device described by the bi_bdev field. 946 * 947 * The success/failure status of the request, along with notification of 948 * completion, is delivered asynchronously through the ->bi_end_io() callback 949 * in @bio. The bio must NOT be touched by the caller until ->bi_end_io() has 950 * been called. 951 */ 952 void submit_bio(struct bio *bio) 953 { 954 if (bio_op(bio) == REQ_OP_READ) { 955 task_io_account_read(bio->bi_iter.bi_size); 956 count_vm_events(PGPGIN, bio_sectors(bio)); 957 } else if (bio_op(bio) == REQ_OP_WRITE) { 958 count_vm_events(PGPGOUT, bio_sectors(bio)); 959 } 960 961 bio_set_ioprio(bio); 962 submit_bio_noacct(bio); 963 } 964 EXPORT_SYMBOL(submit_bio); 965 966 /** 967 * bio_poll - poll for BIO completions 968 * @bio: bio to poll for 969 * @iob: batches of IO 970 * @flags: BLK_POLL_* flags that control the behavior 971 * 972 * Poll for completions on queue associated with the bio. Returns number of 973 * completed entries found. 974 * 975 * Note: the caller must either be the context that submitted @bio, or 976 * be in a RCU critical section to prevent freeing of @bio. 977 */ 978 int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags) 979 { 980 blk_qc_t cookie = READ_ONCE(bio->bi_cookie); 981 struct block_device *bdev; 982 struct request_queue *q; 983 int ret = 0; 984 985 bdev = READ_ONCE(bio->bi_bdev); 986 if (!bdev) 987 return 0; 988 989 q = bdev_get_queue(bdev); 990 if (cookie == BLK_QC_T_NONE) 991 return 0; 992 993 blk_flush_plug(current->plug, false); 994 995 /* 996 * We need to be able to enter a frozen queue, similar to how 997 * timeouts also need to do that. If that is blocked, then we can 998 * have pending IO when a queue freeze is started, and then the 999 * wait for the freeze to finish will wait for polled requests to 1000 * timeout as the poller is preventer from entering the queue and 1001 * completing them. As long as we prevent new IO from being queued, 1002 * that should be all that matters. 1003 */ 1004 if (!percpu_ref_tryget(&q->q_usage_counter)) 1005 return 0; 1006 if (queue_is_mq(q)) { 1007 ret = blk_mq_poll(q, cookie, iob, flags); 1008 } else { 1009 struct gendisk *disk = q->disk; 1010 1011 if ((q->limits.features & BLK_FEAT_POLL) && disk && 1012 disk->fops->poll_bio) 1013 ret = disk->fops->poll_bio(bio, iob, flags); 1014 } 1015 blk_queue_exit(q); 1016 return ret; 1017 } 1018 EXPORT_SYMBOL_GPL(bio_poll); 1019 1020 /* 1021 * Helper to implement file_operations.iopoll. Requires the bio to be stored 1022 * in iocb->private, and cleared before freeing the bio. 1023 */ 1024 int iocb_bio_iopoll(struct kiocb *kiocb, struct io_comp_batch *iob, 1025 unsigned int flags) 1026 { 1027 struct bio *bio; 1028 int ret = 0; 1029 1030 /* 1031 * Note: the bio cache only uses SLAB_TYPESAFE_BY_RCU, so bio can 1032 * point to a freshly allocated bio at this point. If that happens 1033 * we have a few cases to consider: 1034 * 1035 * 1) the bio is being initialized and bi_bdev is NULL. We can just 1036 * simply nothing in this case 1037 * 2) the bio points to a not poll enabled device. bio_poll will catch 1038 * this and return 0 1039 * 3) the bio points to a poll capable device, including but not 1040 * limited to the one that the original bio pointed to. In this 1041 * case we will call into the actual poll method and poll for I/O, 1042 * even if we don't need to, but it won't cause harm either. 1043 * 1044 * For cases 2) and 3) above the RCU grace period ensures that bi_bdev 1045 * is still allocated. Because partitions hold a reference to the whole 1046 * device bdev and thus disk, the disk is also still valid. Grabbing 1047 * a reference to the queue in bio_poll() ensures the hctxs and requests 1048 * are still valid as well. 1049 */ 1050 rcu_read_lock(); 1051 bio = READ_ONCE(kiocb->private); 1052 if (bio) 1053 ret = bio_poll(bio, iob, flags); 1054 rcu_read_unlock(); 1055 1056 return ret; 1057 } 1058 EXPORT_SYMBOL_GPL(iocb_bio_iopoll); 1059 1060 void update_io_ticks(struct block_device *part, unsigned long now, bool end) 1061 { 1062 unsigned long stamp; 1063 again: 1064 stamp = READ_ONCE(part->bd_stamp); 1065 if (unlikely(time_after(now, stamp)) && 1066 likely(try_cmpxchg(&part->bd_stamp, &stamp, now)) && 1067 (end || bdev_count_inflight(part))) 1068 __part_stat_add(part, io_ticks, now - stamp); 1069 1070 if (bdev_is_partition(part)) { 1071 part = bdev_whole(part); 1072 goto again; 1073 } 1074 } 1075 1076 unsigned long bdev_start_io_acct(struct block_device *bdev, enum req_op op, 1077 unsigned long start_time) 1078 { 1079 part_stat_lock(); 1080 update_io_ticks(bdev, start_time, false); 1081 bdev_inc_in_flight(bdev, op); 1082 part_stat_unlock(); 1083 1084 return start_time; 1085 } 1086 EXPORT_SYMBOL(bdev_start_io_acct); 1087 1088 /** 1089 * bio_start_io_acct - start I/O accounting for bio based drivers 1090 * @bio: bio to start account for 1091 * 1092 * Returns the start time that should be passed back to bio_end_io_acct(). 1093 */ 1094 unsigned long bio_start_io_acct(struct bio *bio) 1095 { 1096 return bdev_start_io_acct(bio->bi_bdev, bio_op(bio), jiffies); 1097 } 1098 EXPORT_SYMBOL_GPL(bio_start_io_acct); 1099 1100 void bdev_end_io_acct(struct block_device *bdev, enum req_op op, 1101 unsigned int sectors, unsigned long start_time) 1102 { 1103 const int sgrp = op_stat_group(op); 1104 unsigned long now = READ_ONCE(jiffies); 1105 unsigned long duration = now - start_time; 1106 1107 part_stat_lock(); 1108 update_io_ticks(bdev, now, true); 1109 part_stat_inc(bdev, ios[sgrp]); 1110 part_stat_add(bdev, sectors[sgrp], sectors); 1111 part_stat_add(bdev, nsecs[sgrp], jiffies_to_nsecs(duration)); 1112 bdev_dec_in_flight(bdev, op); 1113 part_stat_unlock(); 1114 } 1115 EXPORT_SYMBOL(bdev_end_io_acct); 1116 1117 void bio_end_io_acct_remapped(struct bio *bio, unsigned long start_time, 1118 struct block_device *orig_bdev) 1119 { 1120 bdev_end_io_acct(orig_bdev, bio_op(bio), bio_sectors(bio), start_time); 1121 } 1122 EXPORT_SYMBOL_GPL(bio_end_io_acct_remapped); 1123 1124 /** 1125 * blk_lld_busy - Check if underlying low-level drivers of a device are busy 1126 * @q : the queue of the device being checked 1127 * 1128 * Description: 1129 * Check if underlying low-level drivers of a device are busy. 1130 * If the drivers want to export their busy state, they must set own 1131 * exporting function using blk_queue_lld_busy() first. 1132 * 1133 * Basically, this function is used only by request stacking drivers 1134 * to stop dispatching requests to underlying devices when underlying 1135 * devices are busy. This behavior helps more I/O merging on the queue 1136 * of the request stacking driver and prevents I/O throughput regression 1137 * on burst I/O load. 1138 * 1139 * Return: 1140 * 0 - Not busy (The request stacking driver should dispatch request) 1141 * 1 - Busy (The request stacking driver should stop dispatching request) 1142 */ 1143 int blk_lld_busy(struct request_queue *q) 1144 { 1145 if (queue_is_mq(q) && q->mq_ops->busy) 1146 return q->mq_ops->busy(q); 1147 1148 return 0; 1149 } 1150 EXPORT_SYMBOL_GPL(blk_lld_busy); 1151 1152 int kblockd_schedule_work(struct work_struct *work) 1153 { 1154 return queue_work(kblockd_workqueue, work); 1155 } 1156 EXPORT_SYMBOL(kblockd_schedule_work); 1157 1158 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, 1159 unsigned long delay) 1160 { 1161 return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay); 1162 } 1163 EXPORT_SYMBOL(kblockd_mod_delayed_work_on); 1164 1165 void blk_start_plug_nr_ios(struct blk_plug *plug, unsigned short nr_ios) 1166 { 1167 struct task_struct *tsk = current; 1168 1169 /* 1170 * If this is a nested plug, don't actually assign it. 1171 */ 1172 if (tsk->plug) 1173 return; 1174 1175 plug->cur_ktime = 0; 1176 rq_list_init(&plug->mq_list); 1177 rq_list_init(&plug->cached_rqs); 1178 plug->nr_ios = min_t(unsigned short, nr_ios, BLK_MAX_REQUEST_COUNT); 1179 plug->rq_count = 0; 1180 plug->multiple_queues = false; 1181 plug->has_elevator = false; 1182 INIT_LIST_HEAD(&plug->cb_list); 1183 1184 /* 1185 * Store ordering should not be needed here, since a potential 1186 * preempt will imply a full memory barrier 1187 */ 1188 tsk->plug = plug; 1189 } 1190 1191 /** 1192 * blk_start_plug - initialize blk_plug and track it inside the task_struct 1193 * @plug: The &struct blk_plug that needs to be initialized 1194 * 1195 * Description: 1196 * blk_start_plug() indicates to the block layer an intent by the caller 1197 * to submit multiple I/O requests in a batch. The block layer may use 1198 * this hint to defer submitting I/Os from the caller until blk_finish_plug() 1199 * is called. However, the block layer may choose to submit requests 1200 * before a call to blk_finish_plug() if the number of queued I/Os 1201 * exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than 1202 * %BLK_PLUG_FLUSH_SIZE. The queued I/Os may also be submitted early if 1203 * the task schedules (see below). 1204 * 1205 * Tracking blk_plug inside the task_struct will help with auto-flushing the 1206 * pending I/O should the task end up blocking between blk_start_plug() and 1207 * blk_finish_plug(). This is important from a performance perspective, but 1208 * also ensures that we don't deadlock. For instance, if the task is blocking 1209 * for a memory allocation, memory reclaim could end up wanting to free a 1210 * page belonging to that request that is currently residing in our private 1211 * plug. By flushing the pending I/O when the process goes to sleep, we avoid 1212 * this kind of deadlock. 1213 */ 1214 void blk_start_plug(struct blk_plug *plug) 1215 { 1216 blk_start_plug_nr_ios(plug, 1); 1217 } 1218 EXPORT_SYMBOL(blk_start_plug); 1219 1220 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) 1221 { 1222 LIST_HEAD(callbacks); 1223 1224 while (!list_empty(&plug->cb_list)) { 1225 list_splice_init(&plug->cb_list, &callbacks); 1226 1227 while (!list_empty(&callbacks)) { 1228 struct blk_plug_cb *cb = list_first_entry(&callbacks, 1229 struct blk_plug_cb, 1230 list); 1231 list_del(&cb->list); 1232 cb->callback(cb, from_schedule); 1233 } 1234 } 1235 } 1236 1237 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, 1238 int size) 1239 { 1240 struct blk_plug *plug = current->plug; 1241 struct blk_plug_cb *cb; 1242 1243 if (!plug) 1244 return NULL; 1245 1246 list_for_each_entry(cb, &plug->cb_list, list) 1247 if (cb->callback == unplug && cb->data == data) 1248 return cb; 1249 1250 /* Not currently on the callback list */ 1251 BUG_ON(size < sizeof(*cb)); 1252 cb = kzalloc(size, GFP_ATOMIC); 1253 if (cb) { 1254 cb->data = data; 1255 cb->callback = unplug; 1256 list_add(&cb->list, &plug->cb_list); 1257 } 1258 return cb; 1259 } 1260 EXPORT_SYMBOL(blk_check_plugged); 1261 1262 void __blk_flush_plug(struct blk_plug *plug, bool from_schedule) 1263 { 1264 if (!list_empty(&plug->cb_list)) 1265 flush_plug_callbacks(plug, from_schedule); 1266 blk_mq_flush_plug_list(plug, from_schedule); 1267 /* 1268 * Unconditionally flush out cached requests, even if the unplug 1269 * event came from schedule. Since we know hold references to the 1270 * queue for cached requests, we don't want a blocked task holding 1271 * up a queue freeze/quiesce event. 1272 */ 1273 if (unlikely(!rq_list_empty(&plug->cached_rqs))) 1274 blk_mq_free_plug_rqs(plug); 1275 1276 plug->cur_ktime = 0; 1277 current->flags &= ~PF_BLOCK_TS; 1278 } 1279 1280 /** 1281 * blk_finish_plug - mark the end of a batch of submitted I/O 1282 * @plug: The &struct blk_plug passed to blk_start_plug() 1283 * 1284 * Description: 1285 * Indicate that a batch of I/O submissions is complete. This function 1286 * must be paired with an initial call to blk_start_plug(). The intent 1287 * is to allow the block layer to optimize I/O submission. See the 1288 * documentation for blk_start_plug() for more information. 1289 */ 1290 void blk_finish_plug(struct blk_plug *plug) 1291 { 1292 if (plug == current->plug) { 1293 __blk_flush_plug(plug, false); 1294 current->plug = NULL; 1295 } 1296 } 1297 EXPORT_SYMBOL(blk_finish_plug); 1298 1299 void blk_io_schedule(void) 1300 { 1301 /* Prevent hang_check timer from firing at us during very long I/O */ 1302 unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2; 1303 1304 if (timeout) 1305 io_schedule_timeout(timeout); 1306 else 1307 io_schedule(); 1308 } 1309 1310 int __init blk_dev_init(void) 1311 { 1312 BUILD_BUG_ON((__force u32)REQ_OP_LAST >= (1 << REQ_OP_BITS)); 1313 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1314 sizeof_field(struct request, cmd_flags)); 1315 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1316 sizeof_field(struct bio, bi_opf)); 1317 1318 /* used for unplugging and affects IO latency/throughput - HIGHPRI */ 1319 kblockd_workqueue = alloc_workqueue("kblockd", 1320 WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_PERCPU, 0); 1321 if (!kblockd_workqueue) 1322 panic("Failed to create kblockd\n"); 1323 1324 blk_requestq_cachep = KMEM_CACHE(request_queue, SLAB_PANIC); 1325 1326 blk_debugfs_root = debugfs_create_dir("block", NULL); 1327 1328 return 0; 1329 } 1330