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/psi.h> 41 #include <linux/part_stat.h> 42 #include <linux/sched/sysctl.h> 43 #include <linux/blk-crypto.h> 44 45 #define CREATE_TRACE_POINTS 46 #include <trace/events/block.h> 47 48 #include "blk.h" 49 #include "blk-mq-sched.h" 50 #include "blk-pm.h" 51 #include "blk-cgroup.h" 52 #include "blk-throttle.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 DEFINE_IDA(blk_queue_ida); 64 65 /* 66 * For queue allocation 67 */ 68 struct kmem_cache *blk_requestq_cachep; 69 struct kmem_cache *blk_requestq_srcu_cachep; 70 71 /* 72 * Controlling structure to kblockd 73 */ 74 static struct workqueue_struct *kblockd_workqueue; 75 76 /** 77 * blk_queue_flag_set - atomically set a queue flag 78 * @flag: flag to be set 79 * @q: request queue 80 */ 81 void blk_queue_flag_set(unsigned int flag, struct request_queue *q) 82 { 83 set_bit(flag, &q->queue_flags); 84 } 85 EXPORT_SYMBOL(blk_queue_flag_set); 86 87 /** 88 * blk_queue_flag_clear - atomically clear a queue flag 89 * @flag: flag to be cleared 90 * @q: request queue 91 */ 92 void blk_queue_flag_clear(unsigned int flag, struct request_queue *q) 93 { 94 clear_bit(flag, &q->queue_flags); 95 } 96 EXPORT_SYMBOL(blk_queue_flag_clear); 97 98 /** 99 * blk_queue_flag_test_and_set - atomically test and set a queue flag 100 * @flag: flag to be set 101 * @q: request queue 102 * 103 * Returns the previous value of @flag - 0 if the flag was not set and 1 if 104 * the flag was already set. 105 */ 106 bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q) 107 { 108 return test_and_set_bit(flag, &q->queue_flags); 109 } 110 EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set); 111 112 #define REQ_OP_NAME(name) [REQ_OP_##name] = #name 113 static const char *const blk_op_name[] = { 114 REQ_OP_NAME(READ), 115 REQ_OP_NAME(WRITE), 116 REQ_OP_NAME(FLUSH), 117 REQ_OP_NAME(DISCARD), 118 REQ_OP_NAME(SECURE_ERASE), 119 REQ_OP_NAME(ZONE_RESET), 120 REQ_OP_NAME(ZONE_RESET_ALL), 121 REQ_OP_NAME(ZONE_OPEN), 122 REQ_OP_NAME(ZONE_CLOSE), 123 REQ_OP_NAME(ZONE_FINISH), 124 REQ_OP_NAME(ZONE_APPEND), 125 REQ_OP_NAME(WRITE_ZEROES), 126 REQ_OP_NAME(DRV_IN), 127 REQ_OP_NAME(DRV_OUT), 128 }; 129 #undef REQ_OP_NAME 130 131 /** 132 * blk_op_str - Return string XXX in the REQ_OP_XXX. 133 * @op: REQ_OP_XXX. 134 * 135 * Description: Centralize block layer function to convert REQ_OP_XXX into 136 * string format. Useful in the debugging and tracing bio or request. For 137 * invalid REQ_OP_XXX it returns string "UNKNOWN". 138 */ 139 inline const char *blk_op_str(unsigned int op) 140 { 141 const char *op_str = "UNKNOWN"; 142 143 if (op < ARRAY_SIZE(blk_op_name) && blk_op_name[op]) 144 op_str = blk_op_name[op]; 145 146 return op_str; 147 } 148 EXPORT_SYMBOL_GPL(blk_op_str); 149 150 static const struct { 151 int errno; 152 const char *name; 153 } blk_errors[] = { 154 [BLK_STS_OK] = { 0, "" }, 155 [BLK_STS_NOTSUPP] = { -EOPNOTSUPP, "operation not supported" }, 156 [BLK_STS_TIMEOUT] = { -ETIMEDOUT, "timeout" }, 157 [BLK_STS_NOSPC] = { -ENOSPC, "critical space allocation" }, 158 [BLK_STS_TRANSPORT] = { -ENOLINK, "recoverable transport" }, 159 [BLK_STS_TARGET] = { -EREMOTEIO, "critical target" }, 160 [BLK_STS_NEXUS] = { -EBADE, "critical nexus" }, 161 [BLK_STS_MEDIUM] = { -ENODATA, "critical medium" }, 162 [BLK_STS_PROTECTION] = { -EILSEQ, "protection" }, 163 [BLK_STS_RESOURCE] = { -ENOMEM, "kernel resource" }, 164 [BLK_STS_DEV_RESOURCE] = { -EBUSY, "device resource" }, 165 [BLK_STS_AGAIN] = { -EAGAIN, "nonblocking retry" }, 166 [BLK_STS_OFFLINE] = { -ENODEV, "device offline" }, 167 168 /* device mapper special case, should not leak out: */ 169 [BLK_STS_DM_REQUEUE] = { -EREMCHG, "dm internal retry" }, 170 171 /* zone device specific errors */ 172 [BLK_STS_ZONE_OPEN_RESOURCE] = { -ETOOMANYREFS, "open zones exceeded" }, 173 [BLK_STS_ZONE_ACTIVE_RESOURCE] = { -EOVERFLOW, "active zones exceeded" }, 174 175 /* everything else not covered above: */ 176 [BLK_STS_IOERR] = { -EIO, "I/O" }, 177 }; 178 179 blk_status_t errno_to_blk_status(int errno) 180 { 181 int i; 182 183 for (i = 0; i < ARRAY_SIZE(blk_errors); i++) { 184 if (blk_errors[i].errno == errno) 185 return (__force blk_status_t)i; 186 } 187 188 return BLK_STS_IOERR; 189 } 190 EXPORT_SYMBOL_GPL(errno_to_blk_status); 191 192 int blk_status_to_errno(blk_status_t status) 193 { 194 int idx = (__force int)status; 195 196 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 197 return -EIO; 198 return blk_errors[idx].errno; 199 } 200 EXPORT_SYMBOL_GPL(blk_status_to_errno); 201 202 const char *blk_status_to_str(blk_status_t status) 203 { 204 int idx = (__force int)status; 205 206 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 207 return "<null>"; 208 return blk_errors[idx].name; 209 } 210 211 /** 212 * blk_sync_queue - cancel any pending callbacks on a queue 213 * @q: the queue 214 * 215 * Description: 216 * The block layer may perform asynchronous callback activity 217 * on a queue, such as calling the unplug function after a timeout. 218 * A block device may call blk_sync_queue to ensure that any 219 * such activity is cancelled, thus allowing it to release resources 220 * that the callbacks might use. The caller must already have made sure 221 * that its ->submit_bio will not re-add plugging prior to calling 222 * this function. 223 * 224 * This function does not cancel any asynchronous activity arising 225 * out of elevator or throttling code. That would require elevator_exit() 226 * and blkcg_exit_queue() to be called with queue lock initialized. 227 * 228 */ 229 void blk_sync_queue(struct request_queue *q) 230 { 231 del_timer_sync(&q->timeout); 232 cancel_work_sync(&q->timeout_work); 233 } 234 EXPORT_SYMBOL(blk_sync_queue); 235 236 /** 237 * blk_set_pm_only - increment pm_only counter 238 * @q: request queue pointer 239 */ 240 void blk_set_pm_only(struct request_queue *q) 241 { 242 atomic_inc(&q->pm_only); 243 } 244 EXPORT_SYMBOL_GPL(blk_set_pm_only); 245 246 void blk_clear_pm_only(struct request_queue *q) 247 { 248 int pm_only; 249 250 pm_only = atomic_dec_return(&q->pm_only); 251 WARN_ON_ONCE(pm_only < 0); 252 if (pm_only == 0) 253 wake_up_all(&q->mq_freeze_wq); 254 } 255 EXPORT_SYMBOL_GPL(blk_clear_pm_only); 256 257 /** 258 * blk_put_queue - decrement the request_queue refcount 259 * @q: the request_queue structure to decrement the refcount for 260 * 261 * Decrements the refcount of the request_queue kobject. When this reaches 0 262 * we'll have blk_release_queue() called. 263 * 264 * Context: Any context, but the last reference must not be dropped from 265 * atomic context. 266 */ 267 void blk_put_queue(struct request_queue *q) 268 { 269 kobject_put(&q->kobj); 270 } 271 EXPORT_SYMBOL(blk_put_queue); 272 273 void blk_queue_start_drain(struct request_queue *q) 274 { 275 /* 276 * When queue DYING flag is set, we need to block new req 277 * entering queue, so we call blk_freeze_queue_start() to 278 * prevent I/O from crossing blk_queue_enter(). 279 */ 280 blk_freeze_queue_start(q); 281 if (queue_is_mq(q)) 282 blk_mq_wake_waiters(q); 283 /* Make blk_queue_enter() reexamine the DYING flag. */ 284 wake_up_all(&q->mq_freeze_wq); 285 } 286 287 /** 288 * blk_queue_enter() - try to increase q->q_usage_counter 289 * @q: request queue pointer 290 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PM 291 */ 292 int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) 293 { 294 const bool pm = flags & BLK_MQ_REQ_PM; 295 296 while (!blk_try_enter_queue(q, pm)) { 297 if (flags & BLK_MQ_REQ_NOWAIT) 298 return -EBUSY; 299 300 /* 301 * read pair of barrier in blk_freeze_queue_start(), we need to 302 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and 303 * reading .mq_freeze_depth or queue dying flag, otherwise the 304 * following wait may never return if the two reads are 305 * reordered. 306 */ 307 smp_rmb(); 308 wait_event(q->mq_freeze_wq, 309 (!q->mq_freeze_depth && 310 blk_pm_resume_queue(pm, q)) || 311 blk_queue_dying(q)); 312 if (blk_queue_dying(q)) 313 return -ENODEV; 314 } 315 316 return 0; 317 } 318 319 int __bio_queue_enter(struct request_queue *q, struct bio *bio) 320 { 321 while (!blk_try_enter_queue(q, false)) { 322 struct gendisk *disk = bio->bi_bdev->bd_disk; 323 324 if (bio->bi_opf & REQ_NOWAIT) { 325 if (test_bit(GD_DEAD, &disk->state)) 326 goto dead; 327 bio_wouldblock_error(bio); 328 return -EBUSY; 329 } 330 331 /* 332 * read pair of barrier in blk_freeze_queue_start(), we need to 333 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and 334 * reading .mq_freeze_depth or queue dying flag, otherwise the 335 * following wait may never return if the two reads are 336 * reordered. 337 */ 338 smp_rmb(); 339 wait_event(q->mq_freeze_wq, 340 (!q->mq_freeze_depth && 341 blk_pm_resume_queue(false, q)) || 342 test_bit(GD_DEAD, &disk->state)); 343 if (test_bit(GD_DEAD, &disk->state)) 344 goto dead; 345 } 346 347 return 0; 348 dead: 349 bio_io_error(bio); 350 return -ENODEV; 351 } 352 353 void blk_queue_exit(struct request_queue *q) 354 { 355 percpu_ref_put(&q->q_usage_counter); 356 } 357 358 static void blk_queue_usage_counter_release(struct percpu_ref *ref) 359 { 360 struct request_queue *q = 361 container_of(ref, struct request_queue, q_usage_counter); 362 363 wake_up_all(&q->mq_freeze_wq); 364 } 365 366 static void blk_rq_timed_out_timer(struct timer_list *t) 367 { 368 struct request_queue *q = from_timer(q, t, timeout); 369 370 kblockd_schedule_work(&q->timeout_work); 371 } 372 373 static void blk_timeout_work(struct work_struct *work) 374 { 375 } 376 377 struct request_queue *blk_alloc_queue(int node_id, bool alloc_srcu) 378 { 379 struct request_queue *q; 380 int ret; 381 382 q = kmem_cache_alloc_node(blk_get_queue_kmem_cache(alloc_srcu), 383 GFP_KERNEL | __GFP_ZERO, node_id); 384 if (!q) 385 return NULL; 386 387 if (alloc_srcu) { 388 blk_queue_flag_set(QUEUE_FLAG_HAS_SRCU, q); 389 if (init_srcu_struct(q->srcu) != 0) 390 goto fail_q; 391 } 392 393 q->last_merge = NULL; 394 395 q->id = ida_alloc(&blk_queue_ida, GFP_KERNEL); 396 if (q->id < 0) 397 goto fail_srcu; 398 399 ret = bioset_init(&q->bio_split, BIO_POOL_SIZE, 0, 0); 400 if (ret) 401 goto fail_id; 402 403 q->stats = blk_alloc_queue_stats(); 404 if (!q->stats) 405 goto fail_split; 406 407 q->node = node_id; 408 409 atomic_set(&q->nr_active_requests_shared_tags, 0); 410 411 timer_setup(&q->timeout, blk_rq_timed_out_timer, 0); 412 INIT_WORK(&q->timeout_work, blk_timeout_work); 413 INIT_LIST_HEAD(&q->icq_list); 414 415 kobject_init(&q->kobj, &blk_queue_ktype); 416 417 mutex_init(&q->debugfs_mutex); 418 mutex_init(&q->sysfs_lock); 419 mutex_init(&q->sysfs_dir_lock); 420 spin_lock_init(&q->queue_lock); 421 422 init_waitqueue_head(&q->mq_freeze_wq); 423 mutex_init(&q->mq_freeze_lock); 424 425 /* 426 * Init percpu_ref in atomic mode so that it's faster to shutdown. 427 * See blk_register_queue() for details. 428 */ 429 if (percpu_ref_init(&q->q_usage_counter, 430 blk_queue_usage_counter_release, 431 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL)) 432 goto fail_stats; 433 434 blk_queue_dma_alignment(q, 511); 435 blk_set_default_limits(&q->limits); 436 q->nr_requests = BLKDEV_DEFAULT_RQ; 437 438 return q; 439 440 fail_stats: 441 blk_free_queue_stats(q->stats); 442 fail_split: 443 bioset_exit(&q->bio_split); 444 fail_id: 445 ida_free(&blk_queue_ida, q->id); 446 fail_srcu: 447 if (alloc_srcu) 448 cleanup_srcu_struct(q->srcu); 449 fail_q: 450 kmem_cache_free(blk_get_queue_kmem_cache(alloc_srcu), q); 451 return NULL; 452 } 453 454 /** 455 * blk_get_queue - increment the request_queue refcount 456 * @q: the request_queue structure to increment the refcount for 457 * 458 * Increment the refcount of the request_queue kobject. 459 * 460 * Context: Any context. 461 */ 462 bool blk_get_queue(struct request_queue *q) 463 { 464 if (likely(!blk_queue_dying(q))) { 465 __blk_get_queue(q); 466 return true; 467 } 468 469 return false; 470 } 471 EXPORT_SYMBOL(blk_get_queue); 472 473 #ifdef CONFIG_FAIL_MAKE_REQUEST 474 475 static DECLARE_FAULT_ATTR(fail_make_request); 476 477 static int __init setup_fail_make_request(char *str) 478 { 479 return setup_fault_attr(&fail_make_request, str); 480 } 481 __setup("fail_make_request=", setup_fail_make_request); 482 483 bool should_fail_request(struct block_device *part, unsigned int bytes) 484 { 485 return part->bd_make_it_fail && should_fail(&fail_make_request, bytes); 486 } 487 488 static int __init fail_make_request_debugfs(void) 489 { 490 struct dentry *dir = fault_create_debugfs_attr("fail_make_request", 491 NULL, &fail_make_request); 492 493 return PTR_ERR_OR_ZERO(dir); 494 } 495 496 late_initcall(fail_make_request_debugfs); 497 #endif /* CONFIG_FAIL_MAKE_REQUEST */ 498 499 static inline bool bio_check_ro(struct bio *bio) 500 { 501 if (op_is_write(bio_op(bio)) && bdev_read_only(bio->bi_bdev)) { 502 if (op_is_flush(bio->bi_opf) && !bio_sectors(bio)) 503 return false; 504 pr_warn("Trying to write to read-only block-device %pg\n", 505 bio->bi_bdev); 506 /* Older lvm-tools actually trigger this */ 507 return false; 508 } 509 510 return false; 511 } 512 513 static noinline int should_fail_bio(struct bio *bio) 514 { 515 if (should_fail_request(bdev_whole(bio->bi_bdev), bio->bi_iter.bi_size)) 516 return -EIO; 517 return 0; 518 } 519 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO); 520 521 /* 522 * Check whether this bio extends beyond the end of the device or partition. 523 * This may well happen - the kernel calls bread() without checking the size of 524 * the device, e.g., when mounting a file system. 525 */ 526 static inline int bio_check_eod(struct bio *bio) 527 { 528 sector_t maxsector = bdev_nr_sectors(bio->bi_bdev); 529 unsigned int nr_sectors = bio_sectors(bio); 530 531 if (nr_sectors && maxsector && 532 (nr_sectors > maxsector || 533 bio->bi_iter.bi_sector > maxsector - nr_sectors)) { 534 pr_info_ratelimited("%s: attempt to access beyond end of device\n" 535 "%pg: rw=%d, sector=%llu, nr_sectors = %u limit=%llu\n", 536 current->comm, bio->bi_bdev, bio->bi_opf, 537 bio->bi_iter.bi_sector, nr_sectors, maxsector); 538 return -EIO; 539 } 540 return 0; 541 } 542 543 /* 544 * Remap block n of partition p to block n+start(p) of the disk. 545 */ 546 static int blk_partition_remap(struct bio *bio) 547 { 548 struct block_device *p = bio->bi_bdev; 549 550 if (unlikely(should_fail_request(p, bio->bi_iter.bi_size))) 551 return -EIO; 552 if (bio_sectors(bio)) { 553 bio->bi_iter.bi_sector += p->bd_start_sect; 554 trace_block_bio_remap(bio, p->bd_dev, 555 bio->bi_iter.bi_sector - 556 p->bd_start_sect); 557 } 558 bio_set_flag(bio, BIO_REMAPPED); 559 return 0; 560 } 561 562 /* 563 * Check write append to a zoned block device. 564 */ 565 static inline blk_status_t blk_check_zone_append(struct request_queue *q, 566 struct bio *bio) 567 { 568 sector_t pos = bio->bi_iter.bi_sector; 569 int nr_sectors = bio_sectors(bio); 570 571 /* Only applicable to zoned block devices */ 572 if (!blk_queue_is_zoned(q)) 573 return BLK_STS_NOTSUPP; 574 575 /* The bio sector must point to the start of a sequential zone */ 576 if (pos & (blk_queue_zone_sectors(q) - 1) || 577 !blk_queue_zone_is_seq(q, pos)) 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(q, 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) && !blk_queue_nowait(q)) 731 goto not_supported; 732 733 if (should_fail_bio(bio)) 734 goto end_io; 735 if (unlikely(bio_check_ro(bio))) 736 goto end_io; 737 if (!bio_flagged(bio, BIO_REMAPPED)) { 738 if (unlikely(bio_check_eod(bio))) 739 goto end_io; 740 if (bdev->bd_partno && unlikely(blk_partition_remap(bio))) 741 goto end_io; 742 } 743 744 /* 745 * Filter flush bio's early so that bio based drivers without flush 746 * support don't have to worry about them. 747 */ 748 if (op_is_flush(bio->bi_opf) && 749 !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) { 750 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA); 751 if (!bio_sectors(bio)) { 752 status = BLK_STS_OK; 753 goto end_io; 754 } 755 } 756 757 if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) 758 bio_clear_polled(bio); 759 760 switch (bio_op(bio)) { 761 case REQ_OP_DISCARD: 762 if (!bdev_max_discard_sectors(bdev)) 763 goto not_supported; 764 break; 765 case REQ_OP_SECURE_ERASE: 766 if (!bdev_max_secure_erase_sectors(bdev)) 767 goto not_supported; 768 break; 769 case REQ_OP_ZONE_APPEND: 770 status = blk_check_zone_append(q, bio); 771 if (status != BLK_STS_OK) 772 goto end_io; 773 break; 774 case REQ_OP_ZONE_RESET: 775 case REQ_OP_ZONE_OPEN: 776 case REQ_OP_ZONE_CLOSE: 777 case REQ_OP_ZONE_FINISH: 778 if (!blk_queue_is_zoned(q)) 779 goto not_supported; 780 break; 781 case REQ_OP_ZONE_RESET_ALL: 782 if (!blk_queue_is_zoned(q) || !blk_queue_zone_resetall(q)) 783 goto not_supported; 784 break; 785 case REQ_OP_WRITE_ZEROES: 786 if (!q->limits.max_write_zeroes_sectors) 787 goto not_supported; 788 break; 789 default: 790 break; 791 } 792 793 if (blk_throtl_bio(bio)) 794 return; 795 796 blk_cgroup_bio_start(bio); 797 blkcg_bio_issue_init(bio); 798 799 if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) { 800 trace_block_bio_queue(bio); 801 /* Now that enqueuing has been traced, we need to trace 802 * completion as well. 803 */ 804 bio_set_flag(bio, BIO_TRACE_COMPLETION); 805 } 806 submit_bio_noacct_nocheck(bio); 807 return; 808 809 not_supported: 810 status = BLK_STS_NOTSUPP; 811 end_io: 812 bio->bi_status = status; 813 bio_endio(bio); 814 } 815 EXPORT_SYMBOL(submit_bio_noacct); 816 817 /** 818 * submit_bio - submit a bio to the block device layer for I/O 819 * @bio: The &struct bio which describes the I/O 820 * 821 * submit_bio() is used to submit I/O requests to block devices. It is passed a 822 * fully set up &struct bio that describes the I/O that needs to be done. The 823 * bio will be send to the device described by the bi_bdev field. 824 * 825 * The success/failure status of the request, along with notification of 826 * completion, is delivered asynchronously through the ->bi_end_io() callback 827 * in @bio. The bio must NOT be touched by thecaller until ->bi_end_io() has 828 * been called. 829 */ 830 void submit_bio(struct bio *bio) 831 { 832 if (blkcg_punt_bio_submit(bio)) 833 return; 834 835 if (bio_op(bio) == REQ_OP_READ) { 836 task_io_account_read(bio->bi_iter.bi_size); 837 count_vm_events(PGPGIN, bio_sectors(bio)); 838 } else if (bio_op(bio) == REQ_OP_WRITE) { 839 count_vm_events(PGPGOUT, bio_sectors(bio)); 840 } 841 842 /* 843 * If we're reading data that is part of the userspace workingset, count 844 * submission time as memory stall. When the device is congested, or 845 * the submitting cgroup IO-throttled, submission can be a significant 846 * part of overall IO time. 847 */ 848 if (unlikely(bio_op(bio) == REQ_OP_READ && 849 bio_flagged(bio, BIO_WORKINGSET))) { 850 unsigned long pflags; 851 852 psi_memstall_enter(&pflags); 853 submit_bio_noacct(bio); 854 psi_memstall_leave(&pflags); 855 return; 856 } 857 858 submit_bio_noacct(bio); 859 } 860 EXPORT_SYMBOL(submit_bio); 861 862 /** 863 * bio_poll - poll for BIO completions 864 * @bio: bio to poll for 865 * @iob: batches of IO 866 * @flags: BLK_POLL_* flags that control the behavior 867 * 868 * Poll for completions on queue associated with the bio. Returns number of 869 * completed entries found. 870 * 871 * Note: the caller must either be the context that submitted @bio, or 872 * be in a RCU critical section to prevent freeing of @bio. 873 */ 874 int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags) 875 { 876 struct request_queue *q = bdev_get_queue(bio->bi_bdev); 877 blk_qc_t cookie = READ_ONCE(bio->bi_cookie); 878 int ret = 0; 879 880 if (cookie == BLK_QC_T_NONE || 881 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) 882 return 0; 883 884 blk_flush_plug(current->plug, false); 885 886 if (bio_queue_enter(bio)) 887 return 0; 888 if (queue_is_mq(q)) { 889 ret = blk_mq_poll(q, cookie, iob, flags); 890 } else { 891 struct gendisk *disk = q->disk; 892 893 if (disk && disk->fops->poll_bio) 894 ret = disk->fops->poll_bio(bio, iob, flags); 895 } 896 blk_queue_exit(q); 897 return ret; 898 } 899 EXPORT_SYMBOL_GPL(bio_poll); 900 901 /* 902 * Helper to implement file_operations.iopoll. Requires the bio to be stored 903 * in iocb->private, and cleared before freeing the bio. 904 */ 905 int iocb_bio_iopoll(struct kiocb *kiocb, struct io_comp_batch *iob, 906 unsigned int flags) 907 { 908 struct bio *bio; 909 int ret = 0; 910 911 /* 912 * Note: the bio cache only uses SLAB_TYPESAFE_BY_RCU, so bio can 913 * point to a freshly allocated bio at this point. If that happens 914 * we have a few cases to consider: 915 * 916 * 1) the bio is beeing initialized and bi_bdev is NULL. We can just 917 * simply nothing in this case 918 * 2) the bio points to a not poll enabled device. bio_poll will catch 919 * this and return 0 920 * 3) the bio points to a poll capable device, including but not 921 * limited to the one that the original bio pointed to. In this 922 * case we will call into the actual poll method and poll for I/O, 923 * even if we don't need to, but it won't cause harm either. 924 * 925 * For cases 2) and 3) above the RCU grace period ensures that bi_bdev 926 * is still allocated. Because partitions hold a reference to the whole 927 * device bdev and thus disk, the disk is also still valid. Grabbing 928 * a reference to the queue in bio_poll() ensures the hctxs and requests 929 * are still valid as well. 930 */ 931 rcu_read_lock(); 932 bio = READ_ONCE(kiocb->private); 933 if (bio && bio->bi_bdev) 934 ret = bio_poll(bio, iob, flags); 935 rcu_read_unlock(); 936 937 return ret; 938 } 939 EXPORT_SYMBOL_GPL(iocb_bio_iopoll); 940 941 void update_io_ticks(struct block_device *part, unsigned long now, bool end) 942 { 943 unsigned long stamp; 944 again: 945 stamp = READ_ONCE(part->bd_stamp); 946 if (unlikely(time_after(now, stamp))) { 947 if (likely(cmpxchg(&part->bd_stamp, stamp, now) == stamp)) 948 __part_stat_add(part, io_ticks, end ? now - stamp : 1); 949 } 950 if (part->bd_partno) { 951 part = bdev_whole(part); 952 goto again; 953 } 954 } 955 956 unsigned long bdev_start_io_acct(struct block_device *bdev, 957 unsigned int sectors, unsigned int op, 958 unsigned long start_time) 959 { 960 const int sgrp = op_stat_group(op); 961 962 part_stat_lock(); 963 update_io_ticks(bdev, start_time, false); 964 part_stat_inc(bdev, ios[sgrp]); 965 part_stat_add(bdev, sectors[sgrp], sectors); 966 part_stat_local_inc(bdev, in_flight[op_is_write(op)]); 967 part_stat_unlock(); 968 969 return start_time; 970 } 971 EXPORT_SYMBOL(bdev_start_io_acct); 972 973 /** 974 * bio_start_io_acct_time - start I/O accounting for bio based drivers 975 * @bio: bio to start account for 976 * @start_time: start time that should be passed back to bio_end_io_acct(). 977 */ 978 void bio_start_io_acct_time(struct bio *bio, unsigned long start_time) 979 { 980 bdev_start_io_acct(bio->bi_bdev, bio_sectors(bio), 981 bio_op(bio), start_time); 982 } 983 EXPORT_SYMBOL_GPL(bio_start_io_acct_time); 984 985 /** 986 * bio_start_io_acct - start I/O accounting for bio based drivers 987 * @bio: bio to start account for 988 * 989 * Returns the start time that should be passed back to bio_end_io_acct(). 990 */ 991 unsigned long bio_start_io_acct(struct bio *bio) 992 { 993 return bdev_start_io_acct(bio->bi_bdev, bio_sectors(bio), 994 bio_op(bio), jiffies); 995 } 996 EXPORT_SYMBOL_GPL(bio_start_io_acct); 997 998 void bdev_end_io_acct(struct block_device *bdev, unsigned int op, 999 unsigned long start_time) 1000 { 1001 const int sgrp = op_stat_group(op); 1002 unsigned long now = READ_ONCE(jiffies); 1003 unsigned long duration = now - start_time; 1004 1005 part_stat_lock(); 1006 update_io_ticks(bdev, now, true); 1007 part_stat_add(bdev, nsecs[sgrp], jiffies_to_nsecs(duration)); 1008 part_stat_local_dec(bdev, in_flight[op_is_write(op)]); 1009 part_stat_unlock(); 1010 } 1011 EXPORT_SYMBOL(bdev_end_io_acct); 1012 1013 void bio_end_io_acct_remapped(struct bio *bio, unsigned long start_time, 1014 struct block_device *orig_bdev) 1015 { 1016 bdev_end_io_acct(orig_bdev, bio_op(bio), start_time); 1017 } 1018 EXPORT_SYMBOL_GPL(bio_end_io_acct_remapped); 1019 1020 /** 1021 * blk_lld_busy - Check if underlying low-level drivers of a device are busy 1022 * @q : the queue of the device being checked 1023 * 1024 * Description: 1025 * Check if underlying low-level drivers of a device are busy. 1026 * If the drivers want to export their busy state, they must set own 1027 * exporting function using blk_queue_lld_busy() first. 1028 * 1029 * Basically, this function is used only by request stacking drivers 1030 * to stop dispatching requests to underlying devices when underlying 1031 * devices are busy. This behavior helps more I/O merging on the queue 1032 * of the request stacking driver and prevents I/O throughput regression 1033 * on burst I/O load. 1034 * 1035 * Return: 1036 * 0 - Not busy (The request stacking driver should dispatch request) 1037 * 1 - Busy (The request stacking driver should stop dispatching request) 1038 */ 1039 int blk_lld_busy(struct request_queue *q) 1040 { 1041 if (queue_is_mq(q) && q->mq_ops->busy) 1042 return q->mq_ops->busy(q); 1043 1044 return 0; 1045 } 1046 EXPORT_SYMBOL_GPL(blk_lld_busy); 1047 1048 int kblockd_schedule_work(struct work_struct *work) 1049 { 1050 return queue_work(kblockd_workqueue, work); 1051 } 1052 EXPORT_SYMBOL(kblockd_schedule_work); 1053 1054 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, 1055 unsigned long delay) 1056 { 1057 return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay); 1058 } 1059 EXPORT_SYMBOL(kblockd_mod_delayed_work_on); 1060 1061 void blk_start_plug_nr_ios(struct blk_plug *plug, unsigned short nr_ios) 1062 { 1063 struct task_struct *tsk = current; 1064 1065 /* 1066 * If this is a nested plug, don't actually assign it. 1067 */ 1068 if (tsk->plug) 1069 return; 1070 1071 plug->mq_list = NULL; 1072 plug->cached_rq = NULL; 1073 plug->nr_ios = min_t(unsigned short, nr_ios, BLK_MAX_REQUEST_COUNT); 1074 plug->rq_count = 0; 1075 plug->multiple_queues = false; 1076 plug->has_elevator = false; 1077 plug->nowait = false; 1078 INIT_LIST_HEAD(&plug->cb_list); 1079 1080 /* 1081 * Store ordering should not be needed here, since a potential 1082 * preempt will imply a full memory barrier 1083 */ 1084 tsk->plug = plug; 1085 } 1086 1087 /** 1088 * blk_start_plug - initialize blk_plug and track it inside the task_struct 1089 * @plug: The &struct blk_plug that needs to be initialized 1090 * 1091 * Description: 1092 * blk_start_plug() indicates to the block layer an intent by the caller 1093 * to submit multiple I/O requests in a batch. The block layer may use 1094 * this hint to defer submitting I/Os from the caller until blk_finish_plug() 1095 * is called. However, the block layer may choose to submit requests 1096 * before a call to blk_finish_plug() if the number of queued I/Os 1097 * exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than 1098 * %BLK_PLUG_FLUSH_SIZE. The queued I/Os may also be submitted early if 1099 * the task schedules (see below). 1100 * 1101 * Tracking blk_plug inside the task_struct will help with auto-flushing the 1102 * pending I/O should the task end up blocking between blk_start_plug() and 1103 * blk_finish_plug(). This is important from a performance perspective, but 1104 * also ensures that we don't deadlock. For instance, if the task is blocking 1105 * for a memory allocation, memory reclaim could end up wanting to free a 1106 * page belonging to that request that is currently residing in our private 1107 * plug. By flushing the pending I/O when the process goes to sleep, we avoid 1108 * this kind of deadlock. 1109 */ 1110 void blk_start_plug(struct blk_plug *plug) 1111 { 1112 blk_start_plug_nr_ios(plug, 1); 1113 } 1114 EXPORT_SYMBOL(blk_start_plug); 1115 1116 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) 1117 { 1118 LIST_HEAD(callbacks); 1119 1120 while (!list_empty(&plug->cb_list)) { 1121 list_splice_init(&plug->cb_list, &callbacks); 1122 1123 while (!list_empty(&callbacks)) { 1124 struct blk_plug_cb *cb = list_first_entry(&callbacks, 1125 struct blk_plug_cb, 1126 list); 1127 list_del(&cb->list); 1128 cb->callback(cb, from_schedule); 1129 } 1130 } 1131 } 1132 1133 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, 1134 int size) 1135 { 1136 struct blk_plug *plug = current->plug; 1137 struct blk_plug_cb *cb; 1138 1139 if (!plug) 1140 return NULL; 1141 1142 list_for_each_entry(cb, &plug->cb_list, list) 1143 if (cb->callback == unplug && cb->data == data) 1144 return cb; 1145 1146 /* Not currently on the callback list */ 1147 BUG_ON(size < sizeof(*cb)); 1148 cb = kzalloc(size, GFP_ATOMIC); 1149 if (cb) { 1150 cb->data = data; 1151 cb->callback = unplug; 1152 list_add(&cb->list, &plug->cb_list); 1153 } 1154 return cb; 1155 } 1156 EXPORT_SYMBOL(blk_check_plugged); 1157 1158 void __blk_flush_plug(struct blk_plug *plug, bool from_schedule) 1159 { 1160 if (!list_empty(&plug->cb_list)) 1161 flush_plug_callbacks(plug, from_schedule); 1162 if (!rq_list_empty(plug->mq_list)) 1163 blk_mq_flush_plug_list(plug, from_schedule); 1164 /* 1165 * Unconditionally flush out cached requests, even if the unplug 1166 * event came from schedule. Since we know hold references to the 1167 * queue for cached requests, we don't want a blocked task holding 1168 * up a queue freeze/quiesce event. 1169 */ 1170 if (unlikely(!rq_list_empty(plug->cached_rq))) 1171 blk_mq_free_plug_rqs(plug); 1172 } 1173 1174 /** 1175 * blk_finish_plug - mark the end of a batch of submitted I/O 1176 * @plug: The &struct blk_plug passed to blk_start_plug() 1177 * 1178 * Description: 1179 * Indicate that a batch of I/O submissions is complete. This function 1180 * must be paired with an initial call to blk_start_plug(). The intent 1181 * is to allow the block layer to optimize I/O submission. See the 1182 * documentation for blk_start_plug() for more information. 1183 */ 1184 void blk_finish_plug(struct blk_plug *plug) 1185 { 1186 if (plug == current->plug) { 1187 __blk_flush_plug(plug, false); 1188 current->plug = NULL; 1189 } 1190 } 1191 EXPORT_SYMBOL(blk_finish_plug); 1192 1193 void blk_io_schedule(void) 1194 { 1195 /* Prevent hang_check timer from firing at us during very long I/O */ 1196 unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2; 1197 1198 if (timeout) 1199 io_schedule_timeout(timeout); 1200 else 1201 io_schedule(); 1202 } 1203 EXPORT_SYMBOL_GPL(blk_io_schedule); 1204 1205 int __init blk_dev_init(void) 1206 { 1207 BUILD_BUG_ON(REQ_OP_LAST >= (1 << REQ_OP_BITS)); 1208 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1209 sizeof_field(struct request, cmd_flags)); 1210 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1211 sizeof_field(struct bio, bi_opf)); 1212 BUILD_BUG_ON(ALIGN(offsetof(struct request_queue, srcu), 1213 __alignof__(struct request_queue)) != 1214 sizeof(struct request_queue)); 1215 1216 /* used for unplugging and affects IO latency/throughput - HIGHPRI */ 1217 kblockd_workqueue = alloc_workqueue("kblockd", 1218 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1219 if (!kblockd_workqueue) 1220 panic("Failed to create kblockd\n"); 1221 1222 blk_requestq_cachep = kmem_cache_create("request_queue", 1223 sizeof(struct request_queue), 0, SLAB_PANIC, NULL); 1224 1225 blk_requestq_srcu_cachep = kmem_cache_create("request_queue_srcu", 1226 sizeof(struct request_queue) + 1227 sizeof(struct srcu_struct), 0, SLAB_PANIC, NULL); 1228 1229 blk_debugfs_root = debugfs_create_dir("block", NULL); 1230 1231 return 0; 1232 } 1233