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