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