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(enum req_op 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 (unlikely(blk_queue_dying(q))) 465 return false; 466 kobject_get(&q->kobj); 467 return true; 468 } 469 EXPORT_SYMBOL(blk_get_queue); 470 471 #ifdef CONFIG_FAIL_MAKE_REQUEST 472 473 static DECLARE_FAULT_ATTR(fail_make_request); 474 475 static int __init setup_fail_make_request(char *str) 476 { 477 return setup_fault_attr(&fail_make_request, str); 478 } 479 __setup("fail_make_request=", setup_fail_make_request); 480 481 bool should_fail_request(struct block_device *part, unsigned int bytes) 482 { 483 return part->bd_make_it_fail && should_fail(&fail_make_request, bytes); 484 } 485 486 static int __init fail_make_request_debugfs(void) 487 { 488 struct dentry *dir = fault_create_debugfs_attr("fail_make_request", 489 NULL, &fail_make_request); 490 491 return PTR_ERR_OR_ZERO(dir); 492 } 493 494 late_initcall(fail_make_request_debugfs); 495 #endif /* CONFIG_FAIL_MAKE_REQUEST */ 496 497 static inline bool bio_check_ro(struct bio *bio) 498 { 499 if (op_is_write(bio_op(bio)) && bdev_read_only(bio->bi_bdev)) { 500 if (op_is_flush(bio->bi_opf) && !bio_sectors(bio)) 501 return false; 502 pr_warn("Trying to write to read-only block-device %pg\n", 503 bio->bi_bdev); 504 /* Older lvm-tools actually trigger this */ 505 return false; 506 } 507 508 return false; 509 } 510 511 static noinline int should_fail_bio(struct bio *bio) 512 { 513 if (should_fail_request(bdev_whole(bio->bi_bdev), bio->bi_iter.bi_size)) 514 return -EIO; 515 return 0; 516 } 517 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO); 518 519 /* 520 * Check whether this bio extends beyond the end of the device or partition. 521 * This may well happen - the kernel calls bread() without checking the size of 522 * the device, e.g., when mounting a file system. 523 */ 524 static inline int bio_check_eod(struct bio *bio) 525 { 526 sector_t maxsector = bdev_nr_sectors(bio->bi_bdev); 527 unsigned int nr_sectors = bio_sectors(bio); 528 529 if (nr_sectors && maxsector && 530 (nr_sectors > maxsector || 531 bio->bi_iter.bi_sector > maxsector - nr_sectors)) { 532 pr_info_ratelimited("%s: attempt to access beyond end of device\n" 533 "%pg: rw=%d, sector=%llu, nr_sectors = %u limit=%llu\n", 534 current->comm, bio->bi_bdev, bio->bi_opf, 535 bio->bi_iter.bi_sector, nr_sectors, maxsector); 536 return -EIO; 537 } 538 return 0; 539 } 540 541 /* 542 * Remap block n of partition p to block n+start(p) of the disk. 543 */ 544 static int blk_partition_remap(struct bio *bio) 545 { 546 struct block_device *p = bio->bi_bdev; 547 548 if (unlikely(should_fail_request(p, bio->bi_iter.bi_size))) 549 return -EIO; 550 if (bio_sectors(bio)) { 551 bio->bi_iter.bi_sector += p->bd_start_sect; 552 trace_block_bio_remap(bio, p->bd_dev, 553 bio->bi_iter.bi_sector - 554 p->bd_start_sect); 555 } 556 bio_set_flag(bio, BIO_REMAPPED); 557 return 0; 558 } 559 560 /* 561 * Check write append to a zoned block device. 562 */ 563 static inline blk_status_t blk_check_zone_append(struct request_queue *q, 564 struct bio *bio) 565 { 566 int nr_sectors = bio_sectors(bio); 567 568 /* Only applicable to zoned block devices */ 569 if (!bdev_is_zoned(bio->bi_bdev)) 570 return BLK_STS_NOTSUPP; 571 572 /* The bio sector must point to the start of a sequential zone */ 573 if (bio->bi_iter.bi_sector & (bdev_zone_sectors(bio->bi_bdev) - 1) || 574 !bio_zone_is_seq(bio)) 575 return BLK_STS_IOERR; 576 577 /* 578 * Not allowed to cross zone boundaries. Otherwise, the BIO will be 579 * split and could result in non-contiguous sectors being written in 580 * different zones. 581 */ 582 if (nr_sectors > q->limits.chunk_sectors) 583 return BLK_STS_IOERR; 584 585 /* Make sure the BIO is small enough and will not get split */ 586 if (nr_sectors > q->limits.max_zone_append_sectors) 587 return BLK_STS_IOERR; 588 589 bio->bi_opf |= REQ_NOMERGE; 590 591 return BLK_STS_OK; 592 } 593 594 static void __submit_bio(struct bio *bio) 595 { 596 struct gendisk *disk = bio->bi_bdev->bd_disk; 597 598 if (unlikely(!blk_crypto_bio_prep(&bio))) 599 return; 600 601 if (!disk->fops->submit_bio) { 602 blk_mq_submit_bio(bio); 603 } else if (likely(bio_queue_enter(bio) == 0)) { 604 disk->fops->submit_bio(bio); 605 blk_queue_exit(disk->queue); 606 } 607 } 608 609 /* 610 * The loop in this function may be a bit non-obvious, and so deserves some 611 * explanation: 612 * 613 * - Before entering the loop, bio->bi_next is NULL (as all callers ensure 614 * that), so we have a list with a single bio. 615 * - We pretend that we have just taken it off a longer list, so we assign 616 * bio_list to a pointer to the bio_list_on_stack, thus initialising the 617 * bio_list of new bios to be added. ->submit_bio() may indeed add some more 618 * bios through a recursive call to submit_bio_noacct. If it did, we find a 619 * non-NULL value in bio_list and re-enter the loop from the top. 620 * - In this case we really did just take the bio of the top of the list (no 621 * pretending) and so remove it from bio_list, and call into ->submit_bio() 622 * again. 623 * 624 * bio_list_on_stack[0] contains bios submitted by the current ->submit_bio. 625 * bio_list_on_stack[1] contains bios that were submitted before the current 626 * ->submit_bio, but that haven't been processed yet. 627 */ 628 static void __submit_bio_noacct(struct bio *bio) 629 { 630 struct bio_list bio_list_on_stack[2]; 631 632 BUG_ON(bio->bi_next); 633 634 bio_list_init(&bio_list_on_stack[0]); 635 current->bio_list = bio_list_on_stack; 636 637 do { 638 struct request_queue *q = bdev_get_queue(bio->bi_bdev); 639 struct bio_list lower, same; 640 641 /* 642 * Create a fresh bio_list for all subordinate requests. 643 */ 644 bio_list_on_stack[1] = bio_list_on_stack[0]; 645 bio_list_init(&bio_list_on_stack[0]); 646 647 __submit_bio(bio); 648 649 /* 650 * Sort new bios into those for a lower level and those for the 651 * same level. 652 */ 653 bio_list_init(&lower); 654 bio_list_init(&same); 655 while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL) 656 if (q == bdev_get_queue(bio->bi_bdev)) 657 bio_list_add(&same, bio); 658 else 659 bio_list_add(&lower, bio); 660 661 /* 662 * Now assemble so we handle the lowest level first. 663 */ 664 bio_list_merge(&bio_list_on_stack[0], &lower); 665 bio_list_merge(&bio_list_on_stack[0], &same); 666 bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); 667 } while ((bio = bio_list_pop(&bio_list_on_stack[0]))); 668 669 current->bio_list = NULL; 670 } 671 672 static void __submit_bio_noacct_mq(struct bio *bio) 673 { 674 struct bio_list bio_list[2] = { }; 675 676 current->bio_list = bio_list; 677 678 do { 679 __submit_bio(bio); 680 } while ((bio = bio_list_pop(&bio_list[0]))); 681 682 current->bio_list = NULL; 683 } 684 685 void submit_bio_noacct_nocheck(struct bio *bio) 686 { 687 /* 688 * We only want one ->submit_bio to be active at a time, else stack 689 * usage with stacked devices could be a problem. Use current->bio_list 690 * to collect a list of requests submited by a ->submit_bio method while 691 * it is active, and then process them after it returned. 692 */ 693 if (current->bio_list) 694 bio_list_add(¤t->bio_list[0], bio); 695 else if (!bio->bi_bdev->bd_disk->fops->submit_bio) 696 __submit_bio_noacct_mq(bio); 697 else 698 __submit_bio_noacct(bio); 699 } 700 701 /** 702 * submit_bio_noacct - re-submit a bio to the block device layer for I/O 703 * @bio: The bio describing the location in memory and on the device. 704 * 705 * This is a version of submit_bio() that shall only be used for I/O that is 706 * resubmitted to lower level drivers by stacking block drivers. All file 707 * systems and other upper level users of the block layer should use 708 * submit_bio() instead. 709 */ 710 void submit_bio_noacct(struct bio *bio) 711 { 712 struct block_device *bdev = bio->bi_bdev; 713 struct request_queue *q = bdev_get_queue(bdev); 714 blk_status_t status = BLK_STS_IOERR; 715 struct blk_plug *plug; 716 717 might_sleep(); 718 719 plug = blk_mq_plug(bio); 720 if (plug && plug->nowait) 721 bio->bi_opf |= REQ_NOWAIT; 722 723 /* 724 * For a REQ_NOWAIT based request, return -EOPNOTSUPP 725 * if queue does not support NOWAIT. 726 */ 727 if ((bio->bi_opf & REQ_NOWAIT) && !blk_queue_nowait(q)) 728 goto not_supported; 729 730 if (should_fail_bio(bio)) 731 goto end_io; 732 if (unlikely(bio_check_ro(bio))) 733 goto end_io; 734 if (!bio_flagged(bio, BIO_REMAPPED)) { 735 if (unlikely(bio_check_eod(bio))) 736 goto end_io; 737 if (bdev->bd_partno && unlikely(blk_partition_remap(bio))) 738 goto end_io; 739 } 740 741 /* 742 * Filter flush bio's early so that bio based drivers without flush 743 * support don't have to worry about them. 744 */ 745 if (op_is_flush(bio->bi_opf) && 746 !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) { 747 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA); 748 if (!bio_sectors(bio)) { 749 status = BLK_STS_OK; 750 goto end_io; 751 } 752 } 753 754 if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) 755 bio_clear_polled(bio); 756 757 switch (bio_op(bio)) { 758 case REQ_OP_DISCARD: 759 if (!bdev_max_discard_sectors(bdev)) 760 goto not_supported; 761 break; 762 case REQ_OP_SECURE_ERASE: 763 if (!bdev_max_secure_erase_sectors(bdev)) 764 goto not_supported; 765 break; 766 case REQ_OP_ZONE_APPEND: 767 status = blk_check_zone_append(q, bio); 768 if (status != BLK_STS_OK) 769 goto end_io; 770 break; 771 case REQ_OP_ZONE_RESET: 772 case REQ_OP_ZONE_OPEN: 773 case REQ_OP_ZONE_CLOSE: 774 case REQ_OP_ZONE_FINISH: 775 if (!bdev_is_zoned(bio->bi_bdev)) 776 goto not_supported; 777 break; 778 case REQ_OP_ZONE_RESET_ALL: 779 if (!bdev_is_zoned(bio->bi_bdev) || !blk_queue_zone_resetall(q)) 780 goto not_supported; 781 break; 782 case REQ_OP_WRITE_ZEROES: 783 if (!q->limits.max_write_zeroes_sectors) 784 goto not_supported; 785 break; 786 default: 787 break; 788 } 789 790 if (blk_throtl_bio(bio)) 791 return; 792 793 blk_cgroup_bio_start(bio); 794 blkcg_bio_issue_init(bio); 795 796 if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) { 797 trace_block_bio_queue(bio); 798 /* Now that enqueuing has been traced, we need to trace 799 * completion as well. 800 */ 801 bio_set_flag(bio, BIO_TRACE_COMPLETION); 802 } 803 submit_bio_noacct_nocheck(bio); 804 return; 805 806 not_supported: 807 status = BLK_STS_NOTSUPP; 808 end_io: 809 bio->bi_status = status; 810 bio_endio(bio); 811 } 812 EXPORT_SYMBOL(submit_bio_noacct); 813 814 /** 815 * submit_bio - submit a bio to the block device layer for I/O 816 * @bio: The &struct bio which describes the I/O 817 * 818 * submit_bio() is used to submit I/O requests to block devices. It is passed a 819 * fully set up &struct bio that describes the I/O that needs to be done. The 820 * bio will be send to the device described by the bi_bdev field. 821 * 822 * The success/failure status of the request, along with notification of 823 * completion, is delivered asynchronously through the ->bi_end_io() callback 824 * in @bio. The bio must NOT be touched by thecaller until ->bi_end_io() has 825 * been called. 826 */ 827 void submit_bio(struct bio *bio) 828 { 829 if (blkcg_punt_bio_submit(bio)) 830 return; 831 832 if (bio_op(bio) == REQ_OP_READ) { 833 task_io_account_read(bio->bi_iter.bi_size); 834 count_vm_events(PGPGIN, bio_sectors(bio)); 835 } else if (bio_op(bio) == REQ_OP_WRITE) { 836 count_vm_events(PGPGOUT, bio_sectors(bio)); 837 } 838 839 /* 840 * If we're reading data that is part of the userspace workingset, count 841 * submission time as memory stall. When the device is congested, or 842 * the submitting cgroup IO-throttled, submission can be a significant 843 * part of overall IO time. 844 */ 845 if (unlikely(bio_op(bio) == REQ_OP_READ && 846 bio_flagged(bio, BIO_WORKINGSET))) { 847 unsigned long pflags; 848 849 psi_memstall_enter(&pflags); 850 submit_bio_noacct(bio); 851 psi_memstall_leave(&pflags); 852 return; 853 } 854 855 submit_bio_noacct(bio); 856 } 857 EXPORT_SYMBOL(submit_bio); 858 859 /** 860 * bio_poll - poll for BIO completions 861 * @bio: bio to poll for 862 * @iob: batches of IO 863 * @flags: BLK_POLL_* flags that control the behavior 864 * 865 * Poll for completions on queue associated with the bio. Returns number of 866 * completed entries found. 867 * 868 * Note: the caller must either be the context that submitted @bio, or 869 * be in a RCU critical section to prevent freeing of @bio. 870 */ 871 int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags) 872 { 873 struct request_queue *q = bdev_get_queue(bio->bi_bdev); 874 blk_qc_t cookie = READ_ONCE(bio->bi_cookie); 875 int ret = 0; 876 877 if (cookie == BLK_QC_T_NONE || 878 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) 879 return 0; 880 881 blk_flush_plug(current->plug, false); 882 883 if (bio_queue_enter(bio)) 884 return 0; 885 if (queue_is_mq(q)) { 886 ret = blk_mq_poll(q, cookie, iob, flags); 887 } else { 888 struct gendisk *disk = q->disk; 889 890 if (disk && disk->fops->poll_bio) 891 ret = disk->fops->poll_bio(bio, iob, flags); 892 } 893 blk_queue_exit(q); 894 return ret; 895 } 896 EXPORT_SYMBOL_GPL(bio_poll); 897 898 /* 899 * Helper to implement file_operations.iopoll. Requires the bio to be stored 900 * in iocb->private, and cleared before freeing the bio. 901 */ 902 int iocb_bio_iopoll(struct kiocb *kiocb, struct io_comp_batch *iob, 903 unsigned int flags) 904 { 905 struct bio *bio; 906 int ret = 0; 907 908 /* 909 * Note: the bio cache only uses SLAB_TYPESAFE_BY_RCU, so bio can 910 * point to a freshly allocated bio at this point. If that happens 911 * we have a few cases to consider: 912 * 913 * 1) the bio is beeing initialized and bi_bdev is NULL. We can just 914 * simply nothing in this case 915 * 2) the bio points to a not poll enabled device. bio_poll will catch 916 * this and return 0 917 * 3) the bio points to a poll capable device, including but not 918 * limited to the one that the original bio pointed to. In this 919 * case we will call into the actual poll method and poll for I/O, 920 * even if we don't need to, but it won't cause harm either. 921 * 922 * For cases 2) and 3) above the RCU grace period ensures that bi_bdev 923 * is still allocated. Because partitions hold a reference to the whole 924 * device bdev and thus disk, the disk is also still valid. Grabbing 925 * a reference to the queue in bio_poll() ensures the hctxs and requests 926 * are still valid as well. 927 */ 928 rcu_read_lock(); 929 bio = READ_ONCE(kiocb->private); 930 if (bio && bio->bi_bdev) 931 ret = bio_poll(bio, iob, flags); 932 rcu_read_unlock(); 933 934 return ret; 935 } 936 EXPORT_SYMBOL_GPL(iocb_bio_iopoll); 937 938 void update_io_ticks(struct block_device *part, unsigned long now, bool end) 939 { 940 unsigned long stamp; 941 again: 942 stamp = READ_ONCE(part->bd_stamp); 943 if (unlikely(time_after(now, stamp))) { 944 if (likely(try_cmpxchg(&part->bd_stamp, &stamp, now))) 945 __part_stat_add(part, io_ticks, end ? now - stamp : 1); 946 } 947 if (part->bd_partno) { 948 part = bdev_whole(part); 949 goto again; 950 } 951 } 952 953 unsigned long bdev_start_io_acct(struct block_device *bdev, 954 unsigned int sectors, enum req_op op, 955 unsigned long start_time) 956 { 957 const int sgrp = op_stat_group(op); 958 959 part_stat_lock(); 960 update_io_ticks(bdev, start_time, false); 961 part_stat_inc(bdev, ios[sgrp]); 962 part_stat_add(bdev, sectors[sgrp], sectors); 963 part_stat_local_inc(bdev, in_flight[op_is_write(op)]); 964 part_stat_unlock(); 965 966 return start_time; 967 } 968 EXPORT_SYMBOL(bdev_start_io_acct); 969 970 /** 971 * bio_start_io_acct_time - start I/O accounting for bio based drivers 972 * @bio: bio to start account for 973 * @start_time: start time that should be passed back to bio_end_io_acct(). 974 */ 975 void bio_start_io_acct_time(struct bio *bio, unsigned long start_time) 976 { 977 bdev_start_io_acct(bio->bi_bdev, bio_sectors(bio), 978 bio_op(bio), start_time); 979 } 980 EXPORT_SYMBOL_GPL(bio_start_io_acct_time); 981 982 /** 983 * bio_start_io_acct - start I/O accounting for bio based drivers 984 * @bio: bio to start account for 985 * 986 * Returns the start time that should be passed back to bio_end_io_acct(). 987 */ 988 unsigned long bio_start_io_acct(struct bio *bio) 989 { 990 return bdev_start_io_acct(bio->bi_bdev, bio_sectors(bio), 991 bio_op(bio), jiffies); 992 } 993 EXPORT_SYMBOL_GPL(bio_start_io_acct); 994 995 void bdev_end_io_acct(struct block_device *bdev, enum req_op op, 996 unsigned long start_time) 997 { 998 const int sgrp = op_stat_group(op); 999 unsigned long now = READ_ONCE(jiffies); 1000 unsigned long duration = now - start_time; 1001 1002 part_stat_lock(); 1003 update_io_ticks(bdev, now, true); 1004 part_stat_add(bdev, nsecs[sgrp], jiffies_to_nsecs(duration)); 1005 part_stat_local_dec(bdev, in_flight[op_is_write(op)]); 1006 part_stat_unlock(); 1007 } 1008 EXPORT_SYMBOL(bdev_end_io_acct); 1009 1010 void bio_end_io_acct_remapped(struct bio *bio, unsigned long start_time, 1011 struct block_device *orig_bdev) 1012 { 1013 bdev_end_io_acct(orig_bdev, bio_op(bio), start_time); 1014 } 1015 EXPORT_SYMBOL_GPL(bio_end_io_acct_remapped); 1016 1017 /** 1018 * blk_lld_busy - Check if underlying low-level drivers of a device are busy 1019 * @q : the queue of the device being checked 1020 * 1021 * Description: 1022 * Check if underlying low-level drivers of a device are busy. 1023 * If the drivers want to export their busy state, they must set own 1024 * exporting function using blk_queue_lld_busy() first. 1025 * 1026 * Basically, this function is used only by request stacking drivers 1027 * to stop dispatching requests to underlying devices when underlying 1028 * devices are busy. This behavior helps more I/O merging on the queue 1029 * of the request stacking driver and prevents I/O throughput regression 1030 * on burst I/O load. 1031 * 1032 * Return: 1033 * 0 - Not busy (The request stacking driver should dispatch request) 1034 * 1 - Busy (The request stacking driver should stop dispatching request) 1035 */ 1036 int blk_lld_busy(struct request_queue *q) 1037 { 1038 if (queue_is_mq(q) && q->mq_ops->busy) 1039 return q->mq_ops->busy(q); 1040 1041 return 0; 1042 } 1043 EXPORT_SYMBOL_GPL(blk_lld_busy); 1044 1045 int kblockd_schedule_work(struct work_struct *work) 1046 { 1047 return queue_work(kblockd_workqueue, work); 1048 } 1049 EXPORT_SYMBOL(kblockd_schedule_work); 1050 1051 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, 1052 unsigned long delay) 1053 { 1054 return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay); 1055 } 1056 EXPORT_SYMBOL(kblockd_mod_delayed_work_on); 1057 1058 void blk_start_plug_nr_ios(struct blk_plug *plug, unsigned short nr_ios) 1059 { 1060 struct task_struct *tsk = current; 1061 1062 /* 1063 * If this is a nested plug, don't actually assign it. 1064 */ 1065 if (tsk->plug) 1066 return; 1067 1068 plug->mq_list = NULL; 1069 plug->cached_rq = NULL; 1070 plug->nr_ios = min_t(unsigned short, nr_ios, BLK_MAX_REQUEST_COUNT); 1071 plug->rq_count = 0; 1072 plug->multiple_queues = false; 1073 plug->has_elevator = false; 1074 plug->nowait = false; 1075 INIT_LIST_HEAD(&plug->cb_list); 1076 1077 /* 1078 * Store ordering should not be needed here, since a potential 1079 * preempt will imply a full memory barrier 1080 */ 1081 tsk->plug = plug; 1082 } 1083 1084 /** 1085 * blk_start_plug - initialize blk_plug and track it inside the task_struct 1086 * @plug: The &struct blk_plug that needs to be initialized 1087 * 1088 * Description: 1089 * blk_start_plug() indicates to the block layer an intent by the caller 1090 * to submit multiple I/O requests in a batch. The block layer may use 1091 * this hint to defer submitting I/Os from the caller until blk_finish_plug() 1092 * is called. However, the block layer may choose to submit requests 1093 * before a call to blk_finish_plug() if the number of queued I/Os 1094 * exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than 1095 * %BLK_PLUG_FLUSH_SIZE. The queued I/Os may also be submitted early if 1096 * the task schedules (see below). 1097 * 1098 * Tracking blk_plug inside the task_struct will help with auto-flushing the 1099 * pending I/O should the task end up blocking between blk_start_plug() and 1100 * blk_finish_plug(). This is important from a performance perspective, but 1101 * also ensures that we don't deadlock. For instance, if the task is blocking 1102 * for a memory allocation, memory reclaim could end up wanting to free a 1103 * page belonging to that request that is currently residing in our private 1104 * plug. By flushing the pending I/O when the process goes to sleep, we avoid 1105 * this kind of deadlock. 1106 */ 1107 void blk_start_plug(struct blk_plug *plug) 1108 { 1109 blk_start_plug_nr_ios(plug, 1); 1110 } 1111 EXPORT_SYMBOL(blk_start_plug); 1112 1113 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) 1114 { 1115 LIST_HEAD(callbacks); 1116 1117 while (!list_empty(&plug->cb_list)) { 1118 list_splice_init(&plug->cb_list, &callbacks); 1119 1120 while (!list_empty(&callbacks)) { 1121 struct blk_plug_cb *cb = list_first_entry(&callbacks, 1122 struct blk_plug_cb, 1123 list); 1124 list_del(&cb->list); 1125 cb->callback(cb, from_schedule); 1126 } 1127 } 1128 } 1129 1130 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, 1131 int size) 1132 { 1133 struct blk_plug *plug = current->plug; 1134 struct blk_plug_cb *cb; 1135 1136 if (!plug) 1137 return NULL; 1138 1139 list_for_each_entry(cb, &plug->cb_list, list) 1140 if (cb->callback == unplug && cb->data == data) 1141 return cb; 1142 1143 /* Not currently on the callback list */ 1144 BUG_ON(size < sizeof(*cb)); 1145 cb = kzalloc(size, GFP_ATOMIC); 1146 if (cb) { 1147 cb->data = data; 1148 cb->callback = unplug; 1149 list_add(&cb->list, &plug->cb_list); 1150 } 1151 return cb; 1152 } 1153 EXPORT_SYMBOL(blk_check_plugged); 1154 1155 void __blk_flush_plug(struct blk_plug *plug, bool from_schedule) 1156 { 1157 if (!list_empty(&plug->cb_list)) 1158 flush_plug_callbacks(plug, from_schedule); 1159 if (!rq_list_empty(plug->mq_list)) 1160 blk_mq_flush_plug_list(plug, from_schedule); 1161 /* 1162 * Unconditionally flush out cached requests, even if the unplug 1163 * event came from schedule. Since we know hold references to the 1164 * queue for cached requests, we don't want a blocked task holding 1165 * up a queue freeze/quiesce event. 1166 */ 1167 if (unlikely(!rq_list_empty(plug->cached_rq))) 1168 blk_mq_free_plug_rqs(plug); 1169 } 1170 1171 /** 1172 * blk_finish_plug - mark the end of a batch of submitted I/O 1173 * @plug: The &struct blk_plug passed to blk_start_plug() 1174 * 1175 * Description: 1176 * Indicate that a batch of I/O submissions is complete. This function 1177 * must be paired with an initial call to blk_start_plug(). The intent 1178 * is to allow the block layer to optimize I/O submission. See the 1179 * documentation for blk_start_plug() for more information. 1180 */ 1181 void blk_finish_plug(struct blk_plug *plug) 1182 { 1183 if (plug == current->plug) { 1184 __blk_flush_plug(plug, false); 1185 current->plug = NULL; 1186 } 1187 } 1188 EXPORT_SYMBOL(blk_finish_plug); 1189 1190 void blk_io_schedule(void) 1191 { 1192 /* Prevent hang_check timer from firing at us during very long I/O */ 1193 unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2; 1194 1195 if (timeout) 1196 io_schedule_timeout(timeout); 1197 else 1198 io_schedule(); 1199 } 1200 EXPORT_SYMBOL_GPL(blk_io_schedule); 1201 1202 int __init blk_dev_init(void) 1203 { 1204 BUILD_BUG_ON((__force u32)REQ_OP_LAST >= (1 << REQ_OP_BITS)); 1205 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1206 sizeof_field(struct request, cmd_flags)); 1207 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1208 sizeof_field(struct bio, bi_opf)); 1209 BUILD_BUG_ON(ALIGN(offsetof(struct request_queue, srcu), 1210 __alignof__(struct request_queue)) != 1211 sizeof(struct request_queue)); 1212 1213 /* used for unplugging and affects IO latency/throughput - HIGHPRI */ 1214 kblockd_workqueue = alloc_workqueue("kblockd", 1215 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1216 if (!kblockd_workqueue) 1217 panic("Failed to create kblockd\n"); 1218 1219 blk_requestq_cachep = kmem_cache_create("request_queue", 1220 sizeof(struct request_queue), 0, SLAB_PANIC, NULL); 1221 1222 blk_requestq_srcu_cachep = kmem_cache_create("request_queue_srcu", 1223 sizeof(struct request_queue) + 1224 sizeof(struct srcu_struct), 0, SLAB_PANIC, NULL); 1225 1226 blk_debugfs_root = debugfs_create_dir("block", NULL); 1227 1228 return 0; 1229 } 1230