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_RESV_CONFLICT] = { -EBADE, "reservation conflict" }, 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 /* Command duration limit device-side timeout */ 174 [BLK_STS_DURATION_LIMIT] = { -ETIME, "duration limit exceeded" }, 175 176 /* everything else not covered above: */ 177 [BLK_STS_IOERR] = { -EIO, "I/O" }, 178 }; 179 180 blk_status_t errno_to_blk_status(int errno) 181 { 182 int i; 183 184 for (i = 0; i < ARRAY_SIZE(blk_errors); i++) { 185 if (blk_errors[i].errno == errno) 186 return (__force blk_status_t)i; 187 } 188 189 return BLK_STS_IOERR; 190 } 191 EXPORT_SYMBOL_GPL(errno_to_blk_status); 192 193 int blk_status_to_errno(blk_status_t status) 194 { 195 int idx = (__force int)status; 196 197 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 198 return -EIO; 199 return blk_errors[idx].errno; 200 } 201 EXPORT_SYMBOL_GPL(blk_status_to_errno); 202 203 const char *blk_status_to_str(blk_status_t status) 204 { 205 int idx = (__force int)status; 206 207 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 208 return "<null>"; 209 return blk_errors[idx].name; 210 } 211 212 /** 213 * blk_sync_queue - cancel any pending callbacks on a queue 214 * @q: the queue 215 * 216 * Description: 217 * The block layer may perform asynchronous callback activity 218 * on a queue, such as calling the unplug function after a timeout. 219 * A block device may call blk_sync_queue to ensure that any 220 * such activity is cancelled, thus allowing it to release resources 221 * that the callbacks might use. The caller must already have made sure 222 * that its ->submit_bio will not re-add plugging prior to calling 223 * this function. 224 * 225 * This function does not cancel any asynchronous activity arising 226 * out of elevator or throttling code. That would require elevator_exit() 227 * and blkcg_exit_queue() to be called with queue lock initialized. 228 * 229 */ 230 void blk_sync_queue(struct request_queue *q) 231 { 232 del_timer_sync(&q->timeout); 233 cancel_work_sync(&q->timeout_work); 234 } 235 EXPORT_SYMBOL(blk_sync_queue); 236 237 /** 238 * blk_set_pm_only - increment pm_only counter 239 * @q: request queue pointer 240 */ 241 void blk_set_pm_only(struct request_queue *q) 242 { 243 atomic_inc(&q->pm_only); 244 } 245 EXPORT_SYMBOL_GPL(blk_set_pm_only); 246 247 void blk_clear_pm_only(struct request_queue *q) 248 { 249 int pm_only; 250 251 pm_only = atomic_dec_return(&q->pm_only); 252 WARN_ON_ONCE(pm_only < 0); 253 if (pm_only == 0) 254 wake_up_all(&q->mq_freeze_wq); 255 } 256 EXPORT_SYMBOL_GPL(blk_clear_pm_only); 257 258 static void blk_free_queue_rcu(struct rcu_head *rcu_head) 259 { 260 struct request_queue *q = container_of(rcu_head, 261 struct request_queue, rcu_head); 262 263 percpu_ref_exit(&q->q_usage_counter); 264 kmem_cache_free(blk_requestq_cachep, q); 265 } 266 267 static void blk_free_queue(struct request_queue *q) 268 { 269 blk_free_queue_stats(q->stats); 270 if (queue_is_mq(q)) 271 blk_mq_release(q); 272 273 ida_free(&blk_queue_ida, q->id); 274 call_rcu(&q->rcu_head, blk_free_queue_rcu); 275 } 276 277 /** 278 * blk_put_queue - decrement the request_queue refcount 279 * @q: the request_queue structure to decrement the refcount for 280 * 281 * Decrements the refcount of the request_queue and free it when the refcount 282 * reaches 0. 283 */ 284 void blk_put_queue(struct request_queue *q) 285 { 286 if (refcount_dec_and_test(&q->refs)) 287 blk_free_queue(q); 288 } 289 EXPORT_SYMBOL(blk_put_queue); 290 291 void blk_queue_start_drain(struct request_queue *q) 292 { 293 /* 294 * When queue DYING flag is set, we need to block new req 295 * entering queue, so we call blk_freeze_queue_start() to 296 * prevent I/O from crossing blk_queue_enter(). 297 */ 298 blk_freeze_queue_start(q); 299 if (queue_is_mq(q)) 300 blk_mq_wake_waiters(q); 301 /* Make blk_queue_enter() reexamine the DYING flag. */ 302 wake_up_all(&q->mq_freeze_wq); 303 } 304 305 /** 306 * blk_queue_enter() - try to increase q->q_usage_counter 307 * @q: request queue pointer 308 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PM 309 */ 310 int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) 311 { 312 const bool pm = flags & BLK_MQ_REQ_PM; 313 314 while (!blk_try_enter_queue(q, pm)) { 315 if (flags & BLK_MQ_REQ_NOWAIT) 316 return -EAGAIN; 317 318 /* 319 * read pair of barrier in blk_freeze_queue_start(), we need to 320 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and 321 * reading .mq_freeze_depth or queue dying flag, otherwise the 322 * following wait may never return if the two reads are 323 * reordered. 324 */ 325 smp_rmb(); 326 wait_event(q->mq_freeze_wq, 327 (!q->mq_freeze_depth && 328 blk_pm_resume_queue(pm, q)) || 329 blk_queue_dying(q)); 330 if (blk_queue_dying(q)) 331 return -ENODEV; 332 } 333 334 return 0; 335 } 336 337 int __bio_queue_enter(struct request_queue *q, struct bio *bio) 338 { 339 while (!blk_try_enter_queue(q, false)) { 340 struct gendisk *disk = bio->bi_bdev->bd_disk; 341 342 if (bio->bi_opf & REQ_NOWAIT) { 343 if (test_bit(GD_DEAD, &disk->state)) 344 goto dead; 345 bio_wouldblock_error(bio); 346 return -EAGAIN; 347 } 348 349 /* 350 * read pair of barrier in blk_freeze_queue_start(), we need to 351 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and 352 * reading .mq_freeze_depth or queue dying flag, otherwise the 353 * following wait may never return if the two reads are 354 * reordered. 355 */ 356 smp_rmb(); 357 wait_event(q->mq_freeze_wq, 358 (!q->mq_freeze_depth && 359 blk_pm_resume_queue(false, q)) || 360 test_bit(GD_DEAD, &disk->state)); 361 if (test_bit(GD_DEAD, &disk->state)) 362 goto dead; 363 } 364 365 return 0; 366 dead: 367 bio_io_error(bio); 368 return -ENODEV; 369 } 370 371 void blk_queue_exit(struct request_queue *q) 372 { 373 percpu_ref_put(&q->q_usage_counter); 374 } 375 376 static void blk_queue_usage_counter_release(struct percpu_ref *ref) 377 { 378 struct request_queue *q = 379 container_of(ref, struct request_queue, q_usage_counter); 380 381 wake_up_all(&q->mq_freeze_wq); 382 } 383 384 static void blk_rq_timed_out_timer(struct timer_list *t) 385 { 386 struct request_queue *q = from_timer(q, t, timeout); 387 388 kblockd_schedule_work(&q->timeout_work); 389 } 390 391 static void blk_timeout_work(struct work_struct *work) 392 { 393 } 394 395 struct request_queue *blk_alloc_queue(int node_id) 396 { 397 struct request_queue *q; 398 399 q = kmem_cache_alloc_node(blk_requestq_cachep, GFP_KERNEL | __GFP_ZERO, 400 node_id); 401 if (!q) 402 return NULL; 403 404 q->last_merge = NULL; 405 406 q->id = ida_alloc(&blk_queue_ida, GFP_KERNEL); 407 if (q->id < 0) 408 goto fail_q; 409 410 q->stats = blk_alloc_queue_stats(); 411 if (!q->stats) 412 goto fail_id; 413 414 q->node = node_id; 415 416 atomic_set(&q->nr_active_requests_shared_tags, 0); 417 418 timer_setup(&q->timeout, blk_rq_timed_out_timer, 0); 419 INIT_WORK(&q->timeout_work, blk_timeout_work); 420 INIT_LIST_HEAD(&q->icq_list); 421 422 refcount_set(&q->refs, 1); 423 mutex_init(&q->debugfs_mutex); 424 mutex_init(&q->sysfs_lock); 425 mutex_init(&q->sysfs_dir_lock); 426 mutex_init(&q->rq_qos_mutex); 427 spin_lock_init(&q->queue_lock); 428 429 init_waitqueue_head(&q->mq_freeze_wq); 430 mutex_init(&q->mq_freeze_lock); 431 432 /* 433 * Init percpu_ref in atomic mode so that it's faster to shutdown. 434 * See blk_register_queue() for details. 435 */ 436 if (percpu_ref_init(&q->q_usage_counter, 437 blk_queue_usage_counter_release, 438 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL)) 439 goto fail_stats; 440 441 blk_set_default_limits(&q->limits); 442 q->nr_requests = BLKDEV_DEFAULT_RQ; 443 444 return q; 445 446 fail_stats: 447 blk_free_queue_stats(q->stats); 448 fail_id: 449 ida_free(&blk_queue_ida, q->id); 450 fail_q: 451 kmem_cache_free(blk_requestq_cachep, q); 452 return NULL; 453 } 454 455 /** 456 * blk_get_queue - increment the request_queue refcount 457 * @q: the request_queue structure to increment the refcount for 458 * 459 * Increment the refcount of the request_queue kobject. 460 * 461 * Context: Any context. 462 */ 463 bool blk_get_queue(struct request_queue *q) 464 { 465 if (unlikely(blk_queue_dying(q))) 466 return false; 467 refcount_inc(&q->refs); 468 return true; 469 } 470 EXPORT_SYMBOL(blk_get_queue); 471 472 #ifdef CONFIG_FAIL_MAKE_REQUEST 473 474 static DECLARE_FAULT_ATTR(fail_make_request); 475 476 static int __init setup_fail_make_request(char *str) 477 { 478 return setup_fault_attr(&fail_make_request, str); 479 } 480 __setup("fail_make_request=", setup_fail_make_request); 481 482 bool should_fail_request(struct block_device *part, unsigned int bytes) 483 { 484 return part->bd_make_it_fail && should_fail(&fail_make_request, bytes); 485 } 486 487 static int __init fail_make_request_debugfs(void) 488 { 489 struct dentry *dir = fault_create_debugfs_attr("fail_make_request", 490 NULL, &fail_make_request); 491 492 return PTR_ERR_OR_ZERO(dir); 493 } 494 495 late_initcall(fail_make_request_debugfs); 496 #endif /* CONFIG_FAIL_MAKE_REQUEST */ 497 498 static inline void bio_check_ro(struct bio *bio) 499 { 500 if (op_is_write(bio_op(bio)) && bdev_read_only(bio->bi_bdev)) { 501 if (op_is_flush(bio->bi_opf) && !bio_sectors(bio)) 502 return; 503 pr_warn("Trying to write to read-only block-device %pg\n", 504 bio->bi_bdev); 505 /* Older lvm-tools actually trigger this */ 506 } 507 } 508 509 static noinline int should_fail_bio(struct bio *bio) 510 { 511 if (should_fail_request(bdev_whole(bio->bi_bdev), bio->bi_iter.bi_size)) 512 return -EIO; 513 return 0; 514 } 515 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO); 516 517 /* 518 * Check whether this bio extends beyond the end of the device or partition. 519 * This may well happen - the kernel calls bread() without checking the size of 520 * the device, e.g., when mounting a file system. 521 */ 522 static inline int bio_check_eod(struct bio *bio) 523 { 524 sector_t maxsector = bdev_nr_sectors(bio->bi_bdev); 525 unsigned int nr_sectors = bio_sectors(bio); 526 527 if (nr_sectors && 528 (nr_sectors > maxsector || 529 bio->bi_iter.bi_sector > maxsector - nr_sectors)) { 530 pr_info_ratelimited("%s: attempt to access beyond end of device\n" 531 "%pg: rw=%d, sector=%llu, nr_sectors = %u limit=%llu\n", 532 current->comm, bio->bi_bdev, bio->bi_opf, 533 bio->bi_iter.bi_sector, nr_sectors, maxsector); 534 return -EIO; 535 } 536 return 0; 537 } 538 539 /* 540 * Remap block n of partition p to block n+start(p) of the disk. 541 */ 542 static int blk_partition_remap(struct bio *bio) 543 { 544 struct block_device *p = bio->bi_bdev; 545 546 if (unlikely(should_fail_request(p, bio->bi_iter.bi_size))) 547 return -EIO; 548 if (bio_sectors(bio)) { 549 bio->bi_iter.bi_sector += p->bd_start_sect; 550 trace_block_bio_remap(bio, p->bd_dev, 551 bio->bi_iter.bi_sector - 552 p->bd_start_sect); 553 } 554 bio_set_flag(bio, BIO_REMAPPED); 555 return 0; 556 } 557 558 /* 559 * Check write append to a zoned block device. 560 */ 561 static inline blk_status_t blk_check_zone_append(struct request_queue *q, 562 struct bio *bio) 563 { 564 int nr_sectors = bio_sectors(bio); 565 566 /* Only applicable to zoned block devices */ 567 if (!bdev_is_zoned(bio->bi_bdev)) 568 return BLK_STS_NOTSUPP; 569 570 /* The bio sector must point to the start of a sequential zone */ 571 if (!bdev_is_zone_start(bio->bi_bdev, bio->bi_iter.bi_sector) || 572 !bio_zone_is_seq(bio)) 573 return BLK_STS_IOERR; 574 575 /* 576 * Not allowed to cross zone boundaries. Otherwise, the BIO will be 577 * split and could result in non-contiguous sectors being written in 578 * different zones. 579 */ 580 if (nr_sectors > q->limits.chunk_sectors) 581 return BLK_STS_IOERR; 582 583 /* Make sure the BIO is small enough and will not get split */ 584 if (nr_sectors > q->limits.max_zone_append_sectors) 585 return BLK_STS_IOERR; 586 587 bio->bi_opf |= REQ_NOMERGE; 588 589 return BLK_STS_OK; 590 } 591 592 static void __submit_bio(struct bio *bio) 593 { 594 if (unlikely(!blk_crypto_bio_prep(&bio))) 595 return; 596 597 if (!bio->bi_bdev->bd_has_submit_bio) { 598 blk_mq_submit_bio(bio); 599 } else if (likely(bio_queue_enter(bio) == 0)) { 600 struct gendisk *disk = bio->bi_bdev->bd_disk; 601 602 disk->fops->submit_bio(bio); 603 blk_queue_exit(disk->queue); 604 } 605 } 606 607 /* 608 * The loop in this function may be a bit non-obvious, and so deserves some 609 * explanation: 610 * 611 * - Before entering the loop, bio->bi_next is NULL (as all callers ensure 612 * that), so we have a list with a single bio. 613 * - We pretend that we have just taken it off a longer list, so we assign 614 * bio_list to a pointer to the bio_list_on_stack, thus initialising the 615 * bio_list of new bios to be added. ->submit_bio() may indeed add some more 616 * bios through a recursive call to submit_bio_noacct. If it did, we find a 617 * non-NULL value in bio_list and re-enter the loop from the top. 618 * - In this case we really did just take the bio of the top of the list (no 619 * pretending) and so remove it from bio_list, and call into ->submit_bio() 620 * again. 621 * 622 * bio_list_on_stack[0] contains bios submitted by the current ->submit_bio. 623 * bio_list_on_stack[1] contains bios that were submitted before the current 624 * ->submit_bio, but that haven't been processed yet. 625 */ 626 static void __submit_bio_noacct(struct bio *bio) 627 { 628 struct bio_list bio_list_on_stack[2]; 629 630 BUG_ON(bio->bi_next); 631 632 bio_list_init(&bio_list_on_stack[0]); 633 current->bio_list = bio_list_on_stack; 634 635 do { 636 struct request_queue *q = bdev_get_queue(bio->bi_bdev); 637 struct bio_list lower, same; 638 639 /* 640 * Create a fresh bio_list for all subordinate requests. 641 */ 642 bio_list_on_stack[1] = bio_list_on_stack[0]; 643 bio_list_init(&bio_list_on_stack[0]); 644 645 __submit_bio(bio); 646 647 /* 648 * Sort new bios into those for a lower level and those for the 649 * same level. 650 */ 651 bio_list_init(&lower); 652 bio_list_init(&same); 653 while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL) 654 if (q == bdev_get_queue(bio->bi_bdev)) 655 bio_list_add(&same, bio); 656 else 657 bio_list_add(&lower, bio); 658 659 /* 660 * Now assemble so we handle the lowest level first. 661 */ 662 bio_list_merge(&bio_list_on_stack[0], &lower); 663 bio_list_merge(&bio_list_on_stack[0], &same); 664 bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); 665 } while ((bio = bio_list_pop(&bio_list_on_stack[0]))); 666 667 current->bio_list = NULL; 668 } 669 670 static void __submit_bio_noacct_mq(struct bio *bio) 671 { 672 struct bio_list bio_list[2] = { }; 673 674 current->bio_list = bio_list; 675 676 do { 677 __submit_bio(bio); 678 } while ((bio = bio_list_pop(&bio_list[0]))); 679 680 current->bio_list = NULL; 681 } 682 683 void submit_bio_noacct_nocheck(struct bio *bio) 684 { 685 blk_cgroup_bio_start(bio); 686 blkcg_bio_issue_init(bio); 687 688 if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) { 689 trace_block_bio_queue(bio); 690 /* 691 * Now that enqueuing has been traced, we need to trace 692 * completion as well. 693 */ 694 bio_set_flag(bio, BIO_TRACE_COMPLETION); 695 } 696 697 /* 698 * We only want one ->submit_bio to be active at a time, else stack 699 * usage with stacked devices could be a problem. Use current->bio_list 700 * to collect a list of requests submited by a ->submit_bio method while 701 * it is active, and then process them after it returned. 702 */ 703 if (current->bio_list) 704 bio_list_add(¤t->bio_list[0], bio); 705 else if (!bio->bi_bdev->bd_has_submit_bio) 706 __submit_bio_noacct_mq(bio); 707 else 708 __submit_bio_noacct(bio); 709 } 710 711 /** 712 * submit_bio_noacct - re-submit a bio to the block device layer for I/O 713 * @bio: The bio describing the location in memory and on the device. 714 * 715 * This is a version of submit_bio() that shall only be used for I/O that is 716 * resubmitted to lower level drivers by stacking block drivers. All file 717 * systems and other upper level users of the block layer should use 718 * submit_bio() instead. 719 */ 720 void submit_bio_noacct(struct bio *bio) 721 { 722 struct block_device *bdev = bio->bi_bdev; 723 struct request_queue *q = bdev_get_queue(bdev); 724 blk_status_t status = BLK_STS_IOERR; 725 struct blk_plug *plug; 726 727 might_sleep(); 728 729 plug = blk_mq_plug(bio); 730 if (plug && plug->nowait) 731 bio->bi_opf |= REQ_NOWAIT; 732 733 /* 734 * For a REQ_NOWAIT based request, return -EOPNOTSUPP 735 * if queue does not support NOWAIT. 736 */ 737 if ((bio->bi_opf & REQ_NOWAIT) && !bdev_nowait(bdev)) 738 goto not_supported; 739 740 if (should_fail_bio(bio)) 741 goto end_io; 742 bio_check_ro(bio); 743 if (!bio_flagged(bio, BIO_REMAPPED)) { 744 if (unlikely(bio_check_eod(bio))) 745 goto end_io; 746 if (bdev->bd_partno && unlikely(blk_partition_remap(bio))) 747 goto end_io; 748 } 749 750 /* 751 * Filter flush bio's early so that bio based drivers without flush 752 * support don't have to worry about them. 753 */ 754 if (op_is_flush(bio->bi_opf)) { 755 if (WARN_ON_ONCE(bio_op(bio) != REQ_OP_WRITE && 756 bio_op(bio) != REQ_OP_ZONE_APPEND)) 757 goto end_io; 758 if (!test_bit(QUEUE_FLAG_WC, &q->queue_flags)) { 759 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA); 760 if (!bio_sectors(bio)) { 761 status = BLK_STS_OK; 762 goto end_io; 763 } 764 } 765 } 766 767 if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) 768 bio_clear_polled(bio); 769 770 switch (bio_op(bio)) { 771 case REQ_OP_DISCARD: 772 if (!bdev_max_discard_sectors(bdev)) 773 goto not_supported; 774 break; 775 case REQ_OP_SECURE_ERASE: 776 if (!bdev_max_secure_erase_sectors(bdev)) 777 goto not_supported; 778 break; 779 case REQ_OP_ZONE_APPEND: 780 status = blk_check_zone_append(q, bio); 781 if (status != BLK_STS_OK) 782 goto end_io; 783 break; 784 case REQ_OP_ZONE_RESET: 785 case REQ_OP_ZONE_OPEN: 786 case REQ_OP_ZONE_CLOSE: 787 case REQ_OP_ZONE_FINISH: 788 if (!bdev_is_zoned(bio->bi_bdev)) 789 goto not_supported; 790 break; 791 case REQ_OP_ZONE_RESET_ALL: 792 if (!bdev_is_zoned(bio->bi_bdev) || !blk_queue_zone_resetall(q)) 793 goto not_supported; 794 break; 795 case REQ_OP_WRITE_ZEROES: 796 if (!q->limits.max_write_zeroes_sectors) 797 goto not_supported; 798 break; 799 default: 800 break; 801 } 802 803 if (blk_throtl_bio(bio)) 804 return; 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 (bio_op(bio) == REQ_OP_READ) { 832 task_io_account_read(bio->bi_iter.bi_size); 833 count_vm_events(PGPGIN, bio_sectors(bio)); 834 } else if (bio_op(bio) == REQ_OP_WRITE) { 835 count_vm_events(PGPGOUT, bio_sectors(bio)); 836 } 837 838 submit_bio_noacct(bio); 839 } 840 EXPORT_SYMBOL(submit_bio); 841 842 /** 843 * bio_poll - poll for BIO completions 844 * @bio: bio to poll for 845 * @iob: batches of IO 846 * @flags: BLK_POLL_* flags that control the behavior 847 * 848 * Poll for completions on queue associated with the bio. Returns number of 849 * completed entries found. 850 * 851 * Note: the caller must either be the context that submitted @bio, or 852 * be in a RCU critical section to prevent freeing of @bio. 853 */ 854 int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags) 855 { 856 blk_qc_t cookie = READ_ONCE(bio->bi_cookie); 857 struct block_device *bdev; 858 struct request_queue *q; 859 int ret = 0; 860 861 bdev = READ_ONCE(bio->bi_bdev); 862 if (!bdev) 863 return 0; 864 865 q = bdev_get_queue(bdev); 866 if (cookie == BLK_QC_T_NONE || 867 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) 868 return 0; 869 870 /* 871 * As the requests that require a zone lock are not plugged in the 872 * first place, directly accessing the plug instead of using 873 * blk_mq_plug() should not have any consequences during flushing for 874 * zoned devices. 875 */ 876 blk_flush_plug(current->plug, false); 877 878 /* 879 * We need to be able to enter a frozen queue, similar to how 880 * timeouts also need to do that. If that is blocked, then we can 881 * have pending IO when a queue freeze is started, and then the 882 * wait for the freeze to finish will wait for polled requests to 883 * timeout as the poller is preventer from entering the queue and 884 * completing them. As long as we prevent new IO from being queued, 885 * that should be all that matters. 886 */ 887 if (!percpu_ref_tryget(&q->q_usage_counter)) 888 return 0; 889 if (queue_is_mq(q)) { 890 ret = blk_mq_poll(q, cookie, iob, flags); 891 } else { 892 struct gendisk *disk = q->disk; 893 894 if (disk && disk->fops->poll_bio) 895 ret = disk->fops->poll_bio(bio, iob, flags); 896 } 897 blk_queue_exit(q); 898 return ret; 899 } 900 EXPORT_SYMBOL_GPL(bio_poll); 901 902 /* 903 * Helper to implement file_operations.iopoll. Requires the bio to be stored 904 * in iocb->private, and cleared before freeing the bio. 905 */ 906 int iocb_bio_iopoll(struct kiocb *kiocb, struct io_comp_batch *iob, 907 unsigned int flags) 908 { 909 struct bio *bio; 910 int ret = 0; 911 912 /* 913 * Note: the bio cache only uses SLAB_TYPESAFE_BY_RCU, so bio can 914 * point to a freshly allocated bio at this point. If that happens 915 * we have a few cases to consider: 916 * 917 * 1) the bio is beeing initialized and bi_bdev is NULL. We can just 918 * simply nothing in this case 919 * 2) the bio points to a not poll enabled device. bio_poll will catch 920 * this and return 0 921 * 3) the bio points to a poll capable device, including but not 922 * limited to the one that the original bio pointed to. In this 923 * case we will call into the actual poll method and poll for I/O, 924 * even if we don't need to, but it won't cause harm either. 925 * 926 * For cases 2) and 3) above the RCU grace period ensures that bi_bdev 927 * is still allocated. Because partitions hold a reference to the whole 928 * device bdev and thus disk, the disk is also still valid. Grabbing 929 * a reference to the queue in bio_poll() ensures the hctxs and requests 930 * are still valid as well. 931 */ 932 rcu_read_lock(); 933 bio = READ_ONCE(kiocb->private); 934 if (bio) 935 ret = bio_poll(bio, iob, flags); 936 rcu_read_unlock(); 937 938 return ret; 939 } 940 EXPORT_SYMBOL_GPL(iocb_bio_iopoll); 941 942 void update_io_ticks(struct block_device *part, unsigned long now, bool end) 943 { 944 unsigned long stamp; 945 again: 946 stamp = READ_ONCE(part->bd_stamp); 947 if (unlikely(time_after(now, stamp))) { 948 if (likely(try_cmpxchg(&part->bd_stamp, &stamp, now))) 949 __part_stat_add(part, io_ticks, end ? now - stamp : 1); 950 } 951 if (part->bd_partno) { 952 part = bdev_whole(part); 953 goto again; 954 } 955 } 956 957 unsigned long bdev_start_io_acct(struct block_device *bdev, enum req_op op, 958 unsigned long start_time) 959 { 960 part_stat_lock(); 961 update_io_ticks(bdev, start_time, false); 962 part_stat_local_inc(bdev, in_flight[op_is_write(op)]); 963 part_stat_unlock(); 964 965 return start_time; 966 } 967 EXPORT_SYMBOL(bdev_start_io_acct); 968 969 /** 970 * bio_start_io_acct - start I/O accounting for bio based drivers 971 * @bio: bio to start account for 972 * 973 * Returns the start time that should be passed back to bio_end_io_acct(). 974 */ 975 unsigned long bio_start_io_acct(struct bio *bio) 976 { 977 return bdev_start_io_acct(bio->bi_bdev, bio_op(bio), jiffies); 978 } 979 EXPORT_SYMBOL_GPL(bio_start_io_acct); 980 981 void bdev_end_io_acct(struct block_device *bdev, enum req_op op, 982 unsigned int sectors, unsigned long start_time) 983 { 984 const int sgrp = op_stat_group(op); 985 unsigned long now = READ_ONCE(jiffies); 986 unsigned long duration = now - start_time; 987 988 part_stat_lock(); 989 update_io_ticks(bdev, now, true); 990 part_stat_inc(bdev, ios[sgrp]); 991 part_stat_add(bdev, sectors[sgrp], sectors); 992 part_stat_add(bdev, nsecs[sgrp], jiffies_to_nsecs(duration)); 993 part_stat_local_dec(bdev, in_flight[op_is_write(op)]); 994 part_stat_unlock(); 995 } 996 EXPORT_SYMBOL(bdev_end_io_acct); 997 998 void bio_end_io_acct_remapped(struct bio *bio, unsigned long start_time, 999 struct block_device *orig_bdev) 1000 { 1001 bdev_end_io_acct(orig_bdev, bio_op(bio), bio_sectors(bio), start_time); 1002 } 1003 EXPORT_SYMBOL_GPL(bio_end_io_acct_remapped); 1004 1005 /** 1006 * blk_lld_busy - Check if underlying low-level drivers of a device are busy 1007 * @q : the queue of the device being checked 1008 * 1009 * Description: 1010 * Check if underlying low-level drivers of a device are busy. 1011 * If the drivers want to export their busy state, they must set own 1012 * exporting function using blk_queue_lld_busy() first. 1013 * 1014 * Basically, this function is used only by request stacking drivers 1015 * to stop dispatching requests to underlying devices when underlying 1016 * devices are busy. This behavior helps more I/O merging on the queue 1017 * of the request stacking driver and prevents I/O throughput regression 1018 * on burst I/O load. 1019 * 1020 * Return: 1021 * 0 - Not busy (The request stacking driver should dispatch request) 1022 * 1 - Busy (The request stacking driver should stop dispatching request) 1023 */ 1024 int blk_lld_busy(struct request_queue *q) 1025 { 1026 if (queue_is_mq(q) && q->mq_ops->busy) 1027 return q->mq_ops->busy(q); 1028 1029 return 0; 1030 } 1031 EXPORT_SYMBOL_GPL(blk_lld_busy); 1032 1033 int kblockd_schedule_work(struct work_struct *work) 1034 { 1035 return queue_work(kblockd_workqueue, work); 1036 } 1037 EXPORT_SYMBOL(kblockd_schedule_work); 1038 1039 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, 1040 unsigned long delay) 1041 { 1042 return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay); 1043 } 1044 EXPORT_SYMBOL(kblockd_mod_delayed_work_on); 1045 1046 void blk_start_plug_nr_ios(struct blk_plug *plug, unsigned short nr_ios) 1047 { 1048 struct task_struct *tsk = current; 1049 1050 /* 1051 * If this is a nested plug, don't actually assign it. 1052 */ 1053 if (tsk->plug) 1054 return; 1055 1056 plug->mq_list = NULL; 1057 plug->cached_rq = NULL; 1058 plug->nr_ios = min_t(unsigned short, nr_ios, BLK_MAX_REQUEST_COUNT); 1059 plug->rq_count = 0; 1060 plug->multiple_queues = false; 1061 plug->has_elevator = false; 1062 plug->nowait = false; 1063 INIT_LIST_HEAD(&plug->cb_list); 1064 1065 /* 1066 * Store ordering should not be needed here, since a potential 1067 * preempt will imply a full memory barrier 1068 */ 1069 tsk->plug = plug; 1070 } 1071 1072 /** 1073 * blk_start_plug - initialize blk_plug and track it inside the task_struct 1074 * @plug: The &struct blk_plug that needs to be initialized 1075 * 1076 * Description: 1077 * blk_start_plug() indicates to the block layer an intent by the caller 1078 * to submit multiple I/O requests in a batch. The block layer may use 1079 * this hint to defer submitting I/Os from the caller until blk_finish_plug() 1080 * is called. However, the block layer may choose to submit requests 1081 * before a call to blk_finish_plug() if the number of queued I/Os 1082 * exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than 1083 * %BLK_PLUG_FLUSH_SIZE. The queued I/Os may also be submitted early if 1084 * the task schedules (see below). 1085 * 1086 * Tracking blk_plug inside the task_struct will help with auto-flushing the 1087 * pending I/O should the task end up blocking between blk_start_plug() and 1088 * blk_finish_plug(). This is important from a performance perspective, but 1089 * also ensures that we don't deadlock. For instance, if the task is blocking 1090 * for a memory allocation, memory reclaim could end up wanting to free a 1091 * page belonging to that request that is currently residing in our private 1092 * plug. By flushing the pending I/O when the process goes to sleep, we avoid 1093 * this kind of deadlock. 1094 */ 1095 void blk_start_plug(struct blk_plug *plug) 1096 { 1097 blk_start_plug_nr_ios(plug, 1); 1098 } 1099 EXPORT_SYMBOL(blk_start_plug); 1100 1101 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) 1102 { 1103 LIST_HEAD(callbacks); 1104 1105 while (!list_empty(&plug->cb_list)) { 1106 list_splice_init(&plug->cb_list, &callbacks); 1107 1108 while (!list_empty(&callbacks)) { 1109 struct blk_plug_cb *cb = list_first_entry(&callbacks, 1110 struct blk_plug_cb, 1111 list); 1112 list_del(&cb->list); 1113 cb->callback(cb, from_schedule); 1114 } 1115 } 1116 } 1117 1118 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, 1119 int size) 1120 { 1121 struct blk_plug *plug = current->plug; 1122 struct blk_plug_cb *cb; 1123 1124 if (!plug) 1125 return NULL; 1126 1127 list_for_each_entry(cb, &plug->cb_list, list) 1128 if (cb->callback == unplug && cb->data == data) 1129 return cb; 1130 1131 /* Not currently on the callback list */ 1132 BUG_ON(size < sizeof(*cb)); 1133 cb = kzalloc(size, GFP_ATOMIC); 1134 if (cb) { 1135 cb->data = data; 1136 cb->callback = unplug; 1137 list_add(&cb->list, &plug->cb_list); 1138 } 1139 return cb; 1140 } 1141 EXPORT_SYMBOL(blk_check_plugged); 1142 1143 void __blk_flush_plug(struct blk_plug *plug, bool from_schedule) 1144 { 1145 if (!list_empty(&plug->cb_list)) 1146 flush_plug_callbacks(plug, from_schedule); 1147 if (!rq_list_empty(plug->mq_list)) 1148 blk_mq_flush_plug_list(plug, from_schedule); 1149 /* 1150 * Unconditionally flush out cached requests, even if the unplug 1151 * event came from schedule. Since we know hold references to the 1152 * queue for cached requests, we don't want a blocked task holding 1153 * up a queue freeze/quiesce event. 1154 */ 1155 if (unlikely(!rq_list_empty(plug->cached_rq))) 1156 blk_mq_free_plug_rqs(plug); 1157 } 1158 1159 /** 1160 * blk_finish_plug - mark the end of a batch of submitted I/O 1161 * @plug: The &struct blk_plug passed to blk_start_plug() 1162 * 1163 * Description: 1164 * Indicate that a batch of I/O submissions is complete. This function 1165 * must be paired with an initial call to blk_start_plug(). The intent 1166 * is to allow the block layer to optimize I/O submission. See the 1167 * documentation for blk_start_plug() for more information. 1168 */ 1169 void blk_finish_plug(struct blk_plug *plug) 1170 { 1171 if (plug == current->plug) { 1172 __blk_flush_plug(plug, false); 1173 current->plug = NULL; 1174 } 1175 } 1176 EXPORT_SYMBOL(blk_finish_plug); 1177 1178 void blk_io_schedule(void) 1179 { 1180 /* Prevent hang_check timer from firing at us during very long I/O */ 1181 unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2; 1182 1183 if (timeout) 1184 io_schedule_timeout(timeout); 1185 else 1186 io_schedule(); 1187 } 1188 EXPORT_SYMBOL_GPL(blk_io_schedule); 1189 1190 int __init blk_dev_init(void) 1191 { 1192 BUILD_BUG_ON((__force u32)REQ_OP_LAST >= (1 << REQ_OP_BITS)); 1193 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1194 sizeof_field(struct request, cmd_flags)); 1195 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1196 sizeof_field(struct bio, bi_opf)); 1197 1198 /* used for unplugging and affects IO latency/throughput - HIGHPRI */ 1199 kblockd_workqueue = alloc_workqueue("kblockd", 1200 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1201 if (!kblockd_workqueue) 1202 panic("Failed to create kblockd\n"); 1203 1204 blk_requestq_cachep = kmem_cache_create("request_queue", 1205 sizeof(struct request_queue), 0, SLAB_PANIC, NULL); 1206 1207 blk_debugfs_root = debugfs_create_dir("block", NULL); 1208 1209 return 0; 1210 } 1211