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 -EAGAIN; 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 -EAGAIN; 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; 380 381 q = kmem_cache_alloc_node(blk_get_queue_kmem_cache(alloc_srcu), 382 GFP_KERNEL | __GFP_ZERO, node_id); 383 if (!q) 384 return NULL; 385 386 if (alloc_srcu) { 387 blk_queue_flag_set(QUEUE_FLAG_HAS_SRCU, q); 388 if (init_srcu_struct(q->srcu) != 0) 389 goto fail_q; 390 } 391 392 q->last_merge = NULL; 393 394 q->id = ida_alloc(&blk_queue_ida, GFP_KERNEL); 395 if (q->id < 0) 396 goto fail_srcu; 397 398 q->stats = blk_alloc_queue_stats(); 399 if (!q->stats) 400 goto fail_id; 401 402 q->node = node_id; 403 404 atomic_set(&q->nr_active_requests_shared_tags, 0); 405 406 timer_setup(&q->timeout, blk_rq_timed_out_timer, 0); 407 INIT_WORK(&q->timeout_work, blk_timeout_work); 408 INIT_LIST_HEAD(&q->icq_list); 409 410 kobject_init(&q->kobj, &blk_queue_ktype); 411 412 mutex_init(&q->debugfs_mutex); 413 mutex_init(&q->sysfs_lock); 414 mutex_init(&q->sysfs_dir_lock); 415 spin_lock_init(&q->queue_lock); 416 417 init_waitqueue_head(&q->mq_freeze_wq); 418 mutex_init(&q->mq_freeze_lock); 419 420 /* 421 * Init percpu_ref in atomic mode so that it's faster to shutdown. 422 * See blk_register_queue() for details. 423 */ 424 if (percpu_ref_init(&q->q_usage_counter, 425 blk_queue_usage_counter_release, 426 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL)) 427 goto fail_stats; 428 429 blk_queue_dma_alignment(q, 511); 430 blk_set_default_limits(&q->limits); 431 q->nr_requests = BLKDEV_DEFAULT_RQ; 432 433 return q; 434 435 fail_stats: 436 blk_free_queue_stats(q->stats); 437 fail_id: 438 ida_free(&blk_queue_ida, q->id); 439 fail_srcu: 440 if (alloc_srcu) 441 cleanup_srcu_struct(q->srcu); 442 fail_q: 443 kmem_cache_free(blk_get_queue_kmem_cache(alloc_srcu), q); 444 return NULL; 445 } 446 447 /** 448 * blk_get_queue - increment the request_queue refcount 449 * @q: the request_queue structure to increment the refcount for 450 * 451 * Increment the refcount of the request_queue kobject. 452 * 453 * Context: Any context. 454 */ 455 bool blk_get_queue(struct request_queue *q) 456 { 457 if (unlikely(blk_queue_dying(q))) 458 return false; 459 kobject_get(&q->kobj); 460 return true; 461 } 462 EXPORT_SYMBOL(blk_get_queue); 463 464 #ifdef CONFIG_FAIL_MAKE_REQUEST 465 466 static DECLARE_FAULT_ATTR(fail_make_request); 467 468 static int __init setup_fail_make_request(char *str) 469 { 470 return setup_fault_attr(&fail_make_request, str); 471 } 472 __setup("fail_make_request=", setup_fail_make_request); 473 474 bool should_fail_request(struct block_device *part, unsigned int bytes) 475 { 476 return part->bd_make_it_fail && should_fail(&fail_make_request, bytes); 477 } 478 479 static int __init fail_make_request_debugfs(void) 480 { 481 struct dentry *dir = fault_create_debugfs_attr("fail_make_request", 482 NULL, &fail_make_request); 483 484 return PTR_ERR_OR_ZERO(dir); 485 } 486 487 late_initcall(fail_make_request_debugfs); 488 #endif /* CONFIG_FAIL_MAKE_REQUEST */ 489 490 static inline bool bio_check_ro(struct bio *bio) 491 { 492 if (op_is_write(bio_op(bio)) && bdev_read_only(bio->bi_bdev)) { 493 if (op_is_flush(bio->bi_opf) && !bio_sectors(bio)) 494 return false; 495 pr_warn("Trying to write to read-only block-device %pg\n", 496 bio->bi_bdev); 497 /* Older lvm-tools actually trigger this */ 498 return false; 499 } 500 501 return false; 502 } 503 504 static noinline int should_fail_bio(struct bio *bio) 505 { 506 if (should_fail_request(bdev_whole(bio->bi_bdev), bio->bi_iter.bi_size)) 507 return -EIO; 508 return 0; 509 } 510 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO); 511 512 /* 513 * Check whether this bio extends beyond the end of the device or partition. 514 * This may well happen - the kernel calls bread() without checking the size of 515 * the device, e.g., when mounting a file system. 516 */ 517 static inline int bio_check_eod(struct bio *bio) 518 { 519 sector_t maxsector = bdev_nr_sectors(bio->bi_bdev); 520 unsigned int nr_sectors = bio_sectors(bio); 521 522 if (nr_sectors && maxsector && 523 (nr_sectors > maxsector || 524 bio->bi_iter.bi_sector > maxsector - nr_sectors)) { 525 pr_info_ratelimited("%s: attempt to access beyond end of device\n" 526 "%pg: rw=%d, sector=%llu, nr_sectors = %u limit=%llu\n", 527 current->comm, bio->bi_bdev, bio->bi_opf, 528 bio->bi_iter.bi_sector, nr_sectors, maxsector); 529 return -EIO; 530 } 531 return 0; 532 } 533 534 /* 535 * Remap block n of partition p to block n+start(p) of the disk. 536 */ 537 static int blk_partition_remap(struct bio *bio) 538 { 539 struct block_device *p = bio->bi_bdev; 540 541 if (unlikely(should_fail_request(p, bio->bi_iter.bi_size))) 542 return -EIO; 543 if (bio_sectors(bio)) { 544 bio->bi_iter.bi_sector += p->bd_start_sect; 545 trace_block_bio_remap(bio, p->bd_dev, 546 bio->bi_iter.bi_sector - 547 p->bd_start_sect); 548 } 549 bio_set_flag(bio, BIO_REMAPPED); 550 return 0; 551 } 552 553 /* 554 * Check write append to a zoned block device. 555 */ 556 static inline blk_status_t blk_check_zone_append(struct request_queue *q, 557 struct bio *bio) 558 { 559 int nr_sectors = bio_sectors(bio); 560 561 /* Only applicable to zoned block devices */ 562 if (!bdev_is_zoned(bio->bi_bdev)) 563 return BLK_STS_NOTSUPP; 564 565 /* The bio sector must point to the start of a sequential zone */ 566 if (bio->bi_iter.bi_sector & (bdev_zone_sectors(bio->bi_bdev) - 1) || 567 !bio_zone_is_seq(bio)) 568 return BLK_STS_IOERR; 569 570 /* 571 * Not allowed to cross zone boundaries. Otherwise, the BIO will be 572 * split and could result in non-contiguous sectors being written in 573 * different zones. 574 */ 575 if (nr_sectors > q->limits.chunk_sectors) 576 return BLK_STS_IOERR; 577 578 /* Make sure the BIO is small enough and will not get split */ 579 if (nr_sectors > q->limits.max_zone_append_sectors) 580 return BLK_STS_IOERR; 581 582 bio->bi_opf |= REQ_NOMERGE; 583 584 return BLK_STS_OK; 585 } 586 587 static void __submit_bio(struct bio *bio) 588 { 589 struct gendisk *disk = bio->bi_bdev->bd_disk; 590 591 if (unlikely(!blk_crypto_bio_prep(&bio))) 592 return; 593 594 if (!disk->fops->submit_bio) { 595 blk_mq_submit_bio(bio); 596 } else if (likely(bio_queue_enter(bio) == 0)) { 597 disk->fops->submit_bio(bio); 598 blk_queue_exit(disk->queue); 599 } 600 } 601 602 /* 603 * The loop in this function may be a bit non-obvious, and so deserves some 604 * explanation: 605 * 606 * - Before entering the loop, bio->bi_next is NULL (as all callers ensure 607 * that), so we have a list with a single bio. 608 * - We pretend that we have just taken it off a longer list, so we assign 609 * bio_list to a pointer to the bio_list_on_stack, thus initialising the 610 * bio_list of new bios to be added. ->submit_bio() may indeed add some more 611 * bios through a recursive call to submit_bio_noacct. If it did, we find a 612 * non-NULL value in bio_list and re-enter the loop from the top. 613 * - In this case we really did just take the bio of the top of the list (no 614 * pretending) and so remove it from bio_list, and call into ->submit_bio() 615 * again. 616 * 617 * bio_list_on_stack[0] contains bios submitted by the current ->submit_bio. 618 * bio_list_on_stack[1] contains bios that were submitted before the current 619 * ->submit_bio, but that haven't been processed yet. 620 */ 621 static void __submit_bio_noacct(struct bio *bio) 622 { 623 struct bio_list bio_list_on_stack[2]; 624 625 BUG_ON(bio->bi_next); 626 627 bio_list_init(&bio_list_on_stack[0]); 628 current->bio_list = bio_list_on_stack; 629 630 do { 631 struct request_queue *q = bdev_get_queue(bio->bi_bdev); 632 struct bio_list lower, same; 633 634 /* 635 * Create a fresh bio_list for all subordinate requests. 636 */ 637 bio_list_on_stack[1] = bio_list_on_stack[0]; 638 bio_list_init(&bio_list_on_stack[0]); 639 640 __submit_bio(bio); 641 642 /* 643 * Sort new bios into those for a lower level and those for the 644 * same level. 645 */ 646 bio_list_init(&lower); 647 bio_list_init(&same); 648 while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL) 649 if (q == bdev_get_queue(bio->bi_bdev)) 650 bio_list_add(&same, bio); 651 else 652 bio_list_add(&lower, bio); 653 654 /* 655 * Now assemble so we handle the lowest level first. 656 */ 657 bio_list_merge(&bio_list_on_stack[0], &lower); 658 bio_list_merge(&bio_list_on_stack[0], &same); 659 bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); 660 } while ((bio = bio_list_pop(&bio_list_on_stack[0]))); 661 662 current->bio_list = NULL; 663 } 664 665 static void __submit_bio_noacct_mq(struct bio *bio) 666 { 667 struct bio_list bio_list[2] = { }; 668 669 current->bio_list = bio_list; 670 671 do { 672 __submit_bio(bio); 673 } while ((bio = bio_list_pop(&bio_list[0]))); 674 675 current->bio_list = NULL; 676 } 677 678 void submit_bio_noacct_nocheck(struct bio *bio) 679 { 680 /* 681 * We only want one ->submit_bio to be active at a time, else stack 682 * usage with stacked devices could be a problem. Use current->bio_list 683 * to collect a list of requests submited by a ->submit_bio method while 684 * it is active, and then process them after it returned. 685 */ 686 if (current->bio_list) 687 bio_list_add(¤t->bio_list[0], bio); 688 else if (!bio->bi_bdev->bd_disk->fops->submit_bio) 689 __submit_bio_noacct_mq(bio); 690 else 691 __submit_bio_noacct(bio); 692 } 693 694 /** 695 * submit_bio_noacct - re-submit a bio to the block device layer for I/O 696 * @bio: The bio describing the location in memory and on the device. 697 * 698 * This is a version of submit_bio() that shall only be used for I/O that is 699 * resubmitted to lower level drivers by stacking block drivers. All file 700 * systems and other upper level users of the block layer should use 701 * submit_bio() instead. 702 */ 703 void submit_bio_noacct(struct bio *bio) 704 { 705 struct block_device *bdev = bio->bi_bdev; 706 struct request_queue *q = bdev_get_queue(bdev); 707 blk_status_t status = BLK_STS_IOERR; 708 struct blk_plug *plug; 709 710 might_sleep(); 711 712 plug = blk_mq_plug(bio); 713 if (plug && plug->nowait) 714 bio->bi_opf |= REQ_NOWAIT; 715 716 /* 717 * For a REQ_NOWAIT based request, return -EOPNOTSUPP 718 * if queue does not support NOWAIT. 719 */ 720 if ((bio->bi_opf & REQ_NOWAIT) && !blk_queue_nowait(q)) 721 goto not_supported; 722 723 if (should_fail_bio(bio)) 724 goto end_io; 725 if (unlikely(bio_check_ro(bio))) 726 goto end_io; 727 if (!bio_flagged(bio, BIO_REMAPPED)) { 728 if (unlikely(bio_check_eod(bio))) 729 goto end_io; 730 if (bdev->bd_partno && unlikely(blk_partition_remap(bio))) 731 goto end_io; 732 } 733 734 /* 735 * Filter flush bio's early so that bio based drivers without flush 736 * support don't have to worry about them. 737 */ 738 if (op_is_flush(bio->bi_opf) && 739 !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) { 740 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA); 741 if (!bio_sectors(bio)) { 742 status = BLK_STS_OK; 743 goto end_io; 744 } 745 } 746 747 if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) 748 bio_clear_polled(bio); 749 750 switch (bio_op(bio)) { 751 case REQ_OP_DISCARD: 752 if (!bdev_max_discard_sectors(bdev)) 753 goto not_supported; 754 break; 755 case REQ_OP_SECURE_ERASE: 756 if (!bdev_max_secure_erase_sectors(bdev)) 757 goto not_supported; 758 break; 759 case REQ_OP_ZONE_APPEND: 760 status = blk_check_zone_append(q, bio); 761 if (status != BLK_STS_OK) 762 goto end_io; 763 break; 764 case REQ_OP_ZONE_RESET: 765 case REQ_OP_ZONE_OPEN: 766 case REQ_OP_ZONE_CLOSE: 767 case REQ_OP_ZONE_FINISH: 768 if (!bdev_is_zoned(bio->bi_bdev)) 769 goto not_supported; 770 break; 771 case REQ_OP_ZONE_RESET_ALL: 772 if (!bdev_is_zoned(bio->bi_bdev) || !blk_queue_zone_resetall(q)) 773 goto not_supported; 774 break; 775 case REQ_OP_WRITE_ZEROES: 776 if (!q->limits.max_write_zeroes_sectors) 777 goto not_supported; 778 break; 779 default: 780 break; 781 } 782 783 if (blk_throtl_bio(bio)) 784 return; 785 786 blk_cgroup_bio_start(bio); 787 blkcg_bio_issue_init(bio); 788 789 if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) { 790 trace_block_bio_queue(bio); 791 /* Now that enqueuing has been traced, we need to trace 792 * completion as well. 793 */ 794 bio_set_flag(bio, BIO_TRACE_COMPLETION); 795 } 796 submit_bio_noacct_nocheck(bio); 797 return; 798 799 not_supported: 800 status = BLK_STS_NOTSUPP; 801 end_io: 802 bio->bi_status = status; 803 bio_endio(bio); 804 } 805 EXPORT_SYMBOL(submit_bio_noacct); 806 807 /** 808 * submit_bio - submit a bio to the block device layer for I/O 809 * @bio: The &struct bio which describes the I/O 810 * 811 * submit_bio() is used to submit I/O requests to block devices. It is passed a 812 * fully set up &struct bio that describes the I/O that needs to be done. The 813 * bio will be send to the device described by the bi_bdev field. 814 * 815 * The success/failure status of the request, along with notification of 816 * completion, is delivered asynchronously through the ->bi_end_io() callback 817 * in @bio. The bio must NOT be touched by thecaller until ->bi_end_io() has 818 * been called. 819 */ 820 void submit_bio(struct bio *bio) 821 { 822 if (blkcg_punt_bio_submit(bio)) 823 return; 824 825 if (bio_op(bio) == REQ_OP_READ) { 826 task_io_account_read(bio->bi_iter.bi_size); 827 count_vm_events(PGPGIN, bio_sectors(bio)); 828 } else if (bio_op(bio) == REQ_OP_WRITE) { 829 count_vm_events(PGPGOUT, bio_sectors(bio)); 830 } 831 832 /* 833 * If we're reading data that is part of the userspace workingset, count 834 * submission time as memory stall. When the device is congested, or 835 * the submitting cgroup IO-throttled, submission can be a significant 836 * part of overall IO time. 837 */ 838 if (unlikely(bio_op(bio) == REQ_OP_READ && 839 bio_flagged(bio, BIO_WORKINGSET))) { 840 unsigned long pflags; 841 842 psi_memstall_enter(&pflags); 843 submit_bio_noacct(bio); 844 psi_memstall_leave(&pflags); 845 return; 846 } 847 848 submit_bio_noacct(bio); 849 } 850 EXPORT_SYMBOL(submit_bio); 851 852 /** 853 * bio_poll - poll for BIO completions 854 * @bio: bio to poll for 855 * @iob: batches of IO 856 * @flags: BLK_POLL_* flags that control the behavior 857 * 858 * Poll for completions on queue associated with the bio. Returns number of 859 * completed entries found. 860 * 861 * Note: the caller must either be the context that submitted @bio, or 862 * be in a RCU critical section to prevent freeing of @bio. 863 */ 864 int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags) 865 { 866 struct request_queue *q = bdev_get_queue(bio->bi_bdev); 867 blk_qc_t cookie = READ_ONCE(bio->bi_cookie); 868 int ret = 0; 869 870 if (cookie == BLK_QC_T_NONE || 871 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) 872 return 0; 873 874 blk_flush_plug(current->plug, false); 875 876 if (bio_queue_enter(bio)) 877 return 0; 878 if (queue_is_mq(q)) { 879 ret = blk_mq_poll(q, cookie, iob, flags); 880 } else { 881 struct gendisk *disk = q->disk; 882 883 if (disk && disk->fops->poll_bio) 884 ret = disk->fops->poll_bio(bio, iob, flags); 885 } 886 blk_queue_exit(q); 887 return ret; 888 } 889 EXPORT_SYMBOL_GPL(bio_poll); 890 891 /* 892 * Helper to implement file_operations.iopoll. Requires the bio to be stored 893 * in iocb->private, and cleared before freeing the bio. 894 */ 895 int iocb_bio_iopoll(struct kiocb *kiocb, struct io_comp_batch *iob, 896 unsigned int flags) 897 { 898 struct bio *bio; 899 int ret = 0; 900 901 /* 902 * Note: the bio cache only uses SLAB_TYPESAFE_BY_RCU, so bio can 903 * point to a freshly allocated bio at this point. If that happens 904 * we have a few cases to consider: 905 * 906 * 1) the bio is beeing initialized and bi_bdev is NULL. We can just 907 * simply nothing in this case 908 * 2) the bio points to a not poll enabled device. bio_poll will catch 909 * this and return 0 910 * 3) the bio points to a poll capable device, including but not 911 * limited to the one that the original bio pointed to. In this 912 * case we will call into the actual poll method and poll for I/O, 913 * even if we don't need to, but it won't cause harm either. 914 * 915 * For cases 2) and 3) above the RCU grace period ensures that bi_bdev 916 * is still allocated. Because partitions hold a reference to the whole 917 * device bdev and thus disk, the disk is also still valid. Grabbing 918 * a reference to the queue in bio_poll() ensures the hctxs and requests 919 * are still valid as well. 920 */ 921 rcu_read_lock(); 922 bio = READ_ONCE(kiocb->private); 923 if (bio && bio->bi_bdev) 924 ret = bio_poll(bio, iob, flags); 925 rcu_read_unlock(); 926 927 return ret; 928 } 929 EXPORT_SYMBOL_GPL(iocb_bio_iopoll); 930 931 void update_io_ticks(struct block_device *part, unsigned long now, bool end) 932 { 933 unsigned long stamp; 934 again: 935 stamp = READ_ONCE(part->bd_stamp); 936 if (unlikely(time_after(now, stamp))) { 937 if (likely(try_cmpxchg(&part->bd_stamp, &stamp, now))) 938 __part_stat_add(part, io_ticks, end ? now - stamp : 1); 939 } 940 if (part->bd_partno) { 941 part = bdev_whole(part); 942 goto again; 943 } 944 } 945 946 unsigned long bdev_start_io_acct(struct block_device *bdev, 947 unsigned int sectors, enum req_op op, 948 unsigned long start_time) 949 { 950 const int sgrp = op_stat_group(op); 951 952 part_stat_lock(); 953 update_io_ticks(bdev, start_time, false); 954 part_stat_inc(bdev, ios[sgrp]); 955 part_stat_add(bdev, sectors[sgrp], sectors); 956 part_stat_local_inc(bdev, in_flight[op_is_write(op)]); 957 part_stat_unlock(); 958 959 return start_time; 960 } 961 EXPORT_SYMBOL(bdev_start_io_acct); 962 963 /** 964 * bio_start_io_acct_time - start I/O accounting for bio based drivers 965 * @bio: bio to start account for 966 * @start_time: start time that should be passed back to bio_end_io_acct(). 967 */ 968 void bio_start_io_acct_time(struct bio *bio, unsigned long start_time) 969 { 970 bdev_start_io_acct(bio->bi_bdev, bio_sectors(bio), 971 bio_op(bio), start_time); 972 } 973 EXPORT_SYMBOL_GPL(bio_start_io_acct_time); 974 975 /** 976 * bio_start_io_acct - start I/O accounting for bio based drivers 977 * @bio: bio to start account for 978 * 979 * Returns the start time that should be passed back to bio_end_io_acct(). 980 */ 981 unsigned long bio_start_io_acct(struct bio *bio) 982 { 983 return bdev_start_io_acct(bio->bi_bdev, bio_sectors(bio), 984 bio_op(bio), jiffies); 985 } 986 EXPORT_SYMBOL_GPL(bio_start_io_acct); 987 988 void bdev_end_io_acct(struct block_device *bdev, enum req_op op, 989 unsigned long start_time) 990 { 991 const int sgrp = op_stat_group(op); 992 unsigned long now = READ_ONCE(jiffies); 993 unsigned long duration = now - start_time; 994 995 part_stat_lock(); 996 update_io_ticks(bdev, now, true); 997 part_stat_add(bdev, nsecs[sgrp], jiffies_to_nsecs(duration)); 998 part_stat_local_dec(bdev, in_flight[op_is_write(op)]); 999 part_stat_unlock(); 1000 } 1001 EXPORT_SYMBOL(bdev_end_io_acct); 1002 1003 void bio_end_io_acct_remapped(struct bio *bio, unsigned long start_time, 1004 struct block_device *orig_bdev) 1005 { 1006 bdev_end_io_acct(orig_bdev, bio_op(bio), start_time); 1007 } 1008 EXPORT_SYMBOL_GPL(bio_end_io_acct_remapped); 1009 1010 /** 1011 * blk_lld_busy - Check if underlying low-level drivers of a device are busy 1012 * @q : the queue of the device being checked 1013 * 1014 * Description: 1015 * Check if underlying low-level drivers of a device are busy. 1016 * If the drivers want to export their busy state, they must set own 1017 * exporting function using blk_queue_lld_busy() first. 1018 * 1019 * Basically, this function is used only by request stacking drivers 1020 * to stop dispatching requests to underlying devices when underlying 1021 * devices are busy. This behavior helps more I/O merging on the queue 1022 * of the request stacking driver and prevents I/O throughput regression 1023 * on burst I/O load. 1024 * 1025 * Return: 1026 * 0 - Not busy (The request stacking driver should dispatch request) 1027 * 1 - Busy (The request stacking driver should stop dispatching request) 1028 */ 1029 int blk_lld_busy(struct request_queue *q) 1030 { 1031 if (queue_is_mq(q) && q->mq_ops->busy) 1032 return q->mq_ops->busy(q); 1033 1034 return 0; 1035 } 1036 EXPORT_SYMBOL_GPL(blk_lld_busy); 1037 1038 int kblockd_schedule_work(struct work_struct *work) 1039 { 1040 return queue_work(kblockd_workqueue, work); 1041 } 1042 EXPORT_SYMBOL(kblockd_schedule_work); 1043 1044 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, 1045 unsigned long delay) 1046 { 1047 return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay); 1048 } 1049 EXPORT_SYMBOL(kblockd_mod_delayed_work_on); 1050 1051 void blk_start_plug_nr_ios(struct blk_plug *plug, unsigned short nr_ios) 1052 { 1053 struct task_struct *tsk = current; 1054 1055 /* 1056 * If this is a nested plug, don't actually assign it. 1057 */ 1058 if (tsk->plug) 1059 return; 1060 1061 plug->mq_list = NULL; 1062 plug->cached_rq = NULL; 1063 plug->nr_ios = min_t(unsigned short, nr_ios, BLK_MAX_REQUEST_COUNT); 1064 plug->rq_count = 0; 1065 plug->multiple_queues = false; 1066 plug->has_elevator = false; 1067 plug->nowait = false; 1068 INIT_LIST_HEAD(&plug->cb_list); 1069 1070 /* 1071 * Store ordering should not be needed here, since a potential 1072 * preempt will imply a full memory barrier 1073 */ 1074 tsk->plug = plug; 1075 } 1076 1077 /** 1078 * blk_start_plug - initialize blk_plug and track it inside the task_struct 1079 * @plug: The &struct blk_plug that needs to be initialized 1080 * 1081 * Description: 1082 * blk_start_plug() indicates to the block layer an intent by the caller 1083 * to submit multiple I/O requests in a batch. The block layer may use 1084 * this hint to defer submitting I/Os from the caller until blk_finish_plug() 1085 * is called. However, the block layer may choose to submit requests 1086 * before a call to blk_finish_plug() if the number of queued I/Os 1087 * exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than 1088 * %BLK_PLUG_FLUSH_SIZE. The queued I/Os may also be submitted early if 1089 * the task schedules (see below). 1090 * 1091 * Tracking blk_plug inside the task_struct will help with auto-flushing the 1092 * pending I/O should the task end up blocking between blk_start_plug() and 1093 * blk_finish_plug(). This is important from a performance perspective, but 1094 * also ensures that we don't deadlock. For instance, if the task is blocking 1095 * for a memory allocation, memory reclaim could end up wanting to free a 1096 * page belonging to that request that is currently residing in our private 1097 * plug. By flushing the pending I/O when the process goes to sleep, we avoid 1098 * this kind of deadlock. 1099 */ 1100 void blk_start_plug(struct blk_plug *plug) 1101 { 1102 blk_start_plug_nr_ios(plug, 1); 1103 } 1104 EXPORT_SYMBOL(blk_start_plug); 1105 1106 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) 1107 { 1108 LIST_HEAD(callbacks); 1109 1110 while (!list_empty(&plug->cb_list)) { 1111 list_splice_init(&plug->cb_list, &callbacks); 1112 1113 while (!list_empty(&callbacks)) { 1114 struct blk_plug_cb *cb = list_first_entry(&callbacks, 1115 struct blk_plug_cb, 1116 list); 1117 list_del(&cb->list); 1118 cb->callback(cb, from_schedule); 1119 } 1120 } 1121 } 1122 1123 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, 1124 int size) 1125 { 1126 struct blk_plug *plug = current->plug; 1127 struct blk_plug_cb *cb; 1128 1129 if (!plug) 1130 return NULL; 1131 1132 list_for_each_entry(cb, &plug->cb_list, list) 1133 if (cb->callback == unplug && cb->data == data) 1134 return cb; 1135 1136 /* Not currently on the callback list */ 1137 BUG_ON(size < sizeof(*cb)); 1138 cb = kzalloc(size, GFP_ATOMIC); 1139 if (cb) { 1140 cb->data = data; 1141 cb->callback = unplug; 1142 list_add(&cb->list, &plug->cb_list); 1143 } 1144 return cb; 1145 } 1146 EXPORT_SYMBOL(blk_check_plugged); 1147 1148 void __blk_flush_plug(struct blk_plug *plug, bool from_schedule) 1149 { 1150 if (!list_empty(&plug->cb_list)) 1151 flush_plug_callbacks(plug, from_schedule); 1152 if (!rq_list_empty(plug->mq_list)) 1153 blk_mq_flush_plug_list(plug, from_schedule); 1154 /* 1155 * Unconditionally flush out cached requests, even if the unplug 1156 * event came from schedule. Since we know hold references to the 1157 * queue for cached requests, we don't want a blocked task holding 1158 * up a queue freeze/quiesce event. 1159 */ 1160 if (unlikely(!rq_list_empty(plug->cached_rq))) 1161 blk_mq_free_plug_rqs(plug); 1162 } 1163 1164 /** 1165 * blk_finish_plug - mark the end of a batch of submitted I/O 1166 * @plug: The &struct blk_plug passed to blk_start_plug() 1167 * 1168 * Description: 1169 * Indicate that a batch of I/O submissions is complete. This function 1170 * must be paired with an initial call to blk_start_plug(). The intent 1171 * is to allow the block layer to optimize I/O submission. See the 1172 * documentation for blk_start_plug() for more information. 1173 */ 1174 void blk_finish_plug(struct blk_plug *plug) 1175 { 1176 if (plug == current->plug) { 1177 __blk_flush_plug(plug, false); 1178 current->plug = NULL; 1179 } 1180 } 1181 EXPORT_SYMBOL(blk_finish_plug); 1182 1183 void blk_io_schedule(void) 1184 { 1185 /* Prevent hang_check timer from firing at us during very long I/O */ 1186 unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2; 1187 1188 if (timeout) 1189 io_schedule_timeout(timeout); 1190 else 1191 io_schedule(); 1192 } 1193 EXPORT_SYMBOL_GPL(blk_io_schedule); 1194 1195 int __init blk_dev_init(void) 1196 { 1197 BUILD_BUG_ON((__force u32)REQ_OP_LAST >= (1 << REQ_OP_BITS)); 1198 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1199 sizeof_field(struct request, cmd_flags)); 1200 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1201 sizeof_field(struct bio, bi_opf)); 1202 BUILD_BUG_ON(ALIGN(offsetof(struct request_queue, srcu), 1203 __alignof__(struct request_queue)) != 1204 sizeof(struct request_queue)); 1205 1206 /* used for unplugging and affects IO latency/throughput - HIGHPRI */ 1207 kblockd_workqueue = alloc_workqueue("kblockd", 1208 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1209 if (!kblockd_workqueue) 1210 panic("Failed to create kblockd\n"); 1211 1212 blk_requestq_cachep = kmem_cache_create("request_queue", 1213 sizeof(struct request_queue), 0, SLAB_PANIC, NULL); 1214 1215 blk_requestq_srcu_cachep = kmem_cache_create("request_queue_srcu", 1216 sizeof(struct request_queue) + 1217 sizeof(struct srcu_struct), 0, SLAB_PANIC, NULL); 1218 1219 blk_debugfs_root = debugfs_create_dir("block", NULL); 1220 1221 return 0; 1222 } 1223