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 #include "blk-rq-qos.h" 54 55 struct dentry *blk_debugfs_root; 56 57 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap); 58 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap); 59 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete); 60 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split); 61 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug); 62 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_insert); 63 64 DEFINE_IDA(blk_queue_ida); 65 66 /* 67 * For queue allocation 68 */ 69 struct kmem_cache *blk_requestq_cachep; 70 struct kmem_cache *blk_requestq_srcu_cachep; 71 72 /* 73 * Controlling structure to kblockd 74 */ 75 static struct workqueue_struct *kblockd_workqueue; 76 77 /** 78 * blk_queue_flag_set - atomically set a queue flag 79 * @flag: flag to be set 80 * @q: request queue 81 */ 82 void blk_queue_flag_set(unsigned int flag, struct request_queue *q) 83 { 84 set_bit(flag, &q->queue_flags); 85 } 86 EXPORT_SYMBOL(blk_queue_flag_set); 87 88 /** 89 * blk_queue_flag_clear - atomically clear a queue flag 90 * @flag: flag to be cleared 91 * @q: request queue 92 */ 93 void blk_queue_flag_clear(unsigned int flag, struct request_queue *q) 94 { 95 clear_bit(flag, &q->queue_flags); 96 } 97 EXPORT_SYMBOL(blk_queue_flag_clear); 98 99 /** 100 * blk_queue_flag_test_and_set - atomically test and set a queue flag 101 * @flag: flag to be set 102 * @q: request queue 103 * 104 * Returns the previous value of @flag - 0 if the flag was not set and 1 if 105 * the flag was already set. 106 */ 107 bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q) 108 { 109 return test_and_set_bit(flag, &q->queue_flags); 110 } 111 EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set); 112 113 #define REQ_OP_NAME(name) [REQ_OP_##name] = #name 114 static const char *const blk_op_name[] = { 115 REQ_OP_NAME(READ), 116 REQ_OP_NAME(WRITE), 117 REQ_OP_NAME(FLUSH), 118 REQ_OP_NAME(DISCARD), 119 REQ_OP_NAME(SECURE_ERASE), 120 REQ_OP_NAME(ZONE_RESET), 121 REQ_OP_NAME(ZONE_RESET_ALL), 122 REQ_OP_NAME(ZONE_OPEN), 123 REQ_OP_NAME(ZONE_CLOSE), 124 REQ_OP_NAME(ZONE_FINISH), 125 REQ_OP_NAME(ZONE_APPEND), 126 REQ_OP_NAME(WRITE_SAME), 127 REQ_OP_NAME(WRITE_ZEROES), 128 REQ_OP_NAME(DRV_IN), 129 REQ_OP_NAME(DRV_OUT), 130 }; 131 #undef REQ_OP_NAME 132 133 /** 134 * blk_op_str - Return string XXX in the REQ_OP_XXX. 135 * @op: REQ_OP_XXX. 136 * 137 * Description: Centralize block layer function to convert REQ_OP_XXX into 138 * string format. Useful in the debugging and tracing bio or request. For 139 * invalid REQ_OP_XXX it returns string "UNKNOWN". 140 */ 141 inline const char *blk_op_str(unsigned int op) 142 { 143 const char *op_str = "UNKNOWN"; 144 145 if (op < ARRAY_SIZE(blk_op_name) && blk_op_name[op]) 146 op_str = blk_op_name[op]; 147 148 return op_str; 149 } 150 EXPORT_SYMBOL_GPL(blk_op_str); 151 152 static const struct { 153 int errno; 154 const char *name; 155 } blk_errors[] = { 156 [BLK_STS_OK] = { 0, "" }, 157 [BLK_STS_NOTSUPP] = { -EOPNOTSUPP, "operation not supported" }, 158 [BLK_STS_TIMEOUT] = { -ETIMEDOUT, "timeout" }, 159 [BLK_STS_NOSPC] = { -ENOSPC, "critical space allocation" }, 160 [BLK_STS_TRANSPORT] = { -ENOLINK, "recoverable transport" }, 161 [BLK_STS_TARGET] = { -EREMOTEIO, "critical target" }, 162 [BLK_STS_NEXUS] = { -EBADE, "critical nexus" }, 163 [BLK_STS_MEDIUM] = { -ENODATA, "critical medium" }, 164 [BLK_STS_PROTECTION] = { -EILSEQ, "protection" }, 165 [BLK_STS_RESOURCE] = { -ENOMEM, "kernel resource" }, 166 [BLK_STS_DEV_RESOURCE] = { -EBUSY, "device resource" }, 167 [BLK_STS_AGAIN] = { -EAGAIN, "nonblocking retry" }, 168 [BLK_STS_OFFLINE] = { -ENODEV, "device offline" }, 169 170 /* device mapper special case, should not leak out: */ 171 [BLK_STS_DM_REQUEUE] = { -EREMCHG, "dm internal retry" }, 172 173 /* zone device specific errors */ 174 [BLK_STS_ZONE_OPEN_RESOURCE] = { -ETOOMANYREFS, "open zones exceeded" }, 175 [BLK_STS_ZONE_ACTIVE_RESOURCE] = { -EOVERFLOW, "active zones exceeded" }, 176 177 /* everything else not covered above: */ 178 [BLK_STS_IOERR] = { -EIO, "I/O" }, 179 }; 180 181 blk_status_t errno_to_blk_status(int errno) 182 { 183 int i; 184 185 for (i = 0; i < ARRAY_SIZE(blk_errors); i++) { 186 if (blk_errors[i].errno == errno) 187 return (__force blk_status_t)i; 188 } 189 190 return BLK_STS_IOERR; 191 } 192 EXPORT_SYMBOL_GPL(errno_to_blk_status); 193 194 int blk_status_to_errno(blk_status_t status) 195 { 196 int idx = (__force int)status; 197 198 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 199 return -EIO; 200 return blk_errors[idx].errno; 201 } 202 EXPORT_SYMBOL_GPL(blk_status_to_errno); 203 204 const char *blk_status_to_str(blk_status_t status) 205 { 206 int idx = (__force int)status; 207 208 if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors))) 209 return "<null>"; 210 return blk_errors[idx].name; 211 } 212 213 /** 214 * blk_sync_queue - cancel any pending callbacks on a queue 215 * @q: the queue 216 * 217 * Description: 218 * The block layer may perform asynchronous callback activity 219 * on a queue, such as calling the unplug function after a timeout. 220 * A block device may call blk_sync_queue to ensure that any 221 * such activity is cancelled, thus allowing it to release resources 222 * that the callbacks might use. The caller must already have made sure 223 * that its ->submit_bio will not re-add plugging prior to calling 224 * this function. 225 * 226 * This function does not cancel any asynchronous activity arising 227 * out of elevator or throttling code. That would require elevator_exit() 228 * and blkcg_exit_queue() to be called with queue lock initialized. 229 * 230 */ 231 void blk_sync_queue(struct request_queue *q) 232 { 233 del_timer_sync(&q->timeout); 234 cancel_work_sync(&q->timeout_work); 235 } 236 EXPORT_SYMBOL(blk_sync_queue); 237 238 /** 239 * blk_set_pm_only - increment pm_only counter 240 * @q: request queue pointer 241 */ 242 void blk_set_pm_only(struct request_queue *q) 243 { 244 atomic_inc(&q->pm_only); 245 } 246 EXPORT_SYMBOL_GPL(blk_set_pm_only); 247 248 void blk_clear_pm_only(struct request_queue *q) 249 { 250 int pm_only; 251 252 pm_only = atomic_dec_return(&q->pm_only); 253 WARN_ON_ONCE(pm_only < 0); 254 if (pm_only == 0) 255 wake_up_all(&q->mq_freeze_wq); 256 } 257 EXPORT_SYMBOL_GPL(blk_clear_pm_only); 258 259 /** 260 * blk_put_queue - decrement the request_queue refcount 261 * @q: the request_queue structure to decrement the refcount for 262 * 263 * Decrements the refcount of the request_queue kobject. When this reaches 0 264 * we'll have blk_release_queue() called. 265 * 266 * Context: Any context, but the last reference must not be dropped from 267 * atomic context. 268 */ 269 void blk_put_queue(struct request_queue *q) 270 { 271 kobject_put(&q->kobj); 272 } 273 EXPORT_SYMBOL(blk_put_queue); 274 275 void blk_queue_start_drain(struct request_queue *q) 276 { 277 /* 278 * When queue DYING flag is set, we need to block new req 279 * entering queue, so we call blk_freeze_queue_start() to 280 * prevent I/O from crossing blk_queue_enter(). 281 */ 282 blk_freeze_queue_start(q); 283 if (queue_is_mq(q)) 284 blk_mq_wake_waiters(q); 285 /* Make blk_queue_enter() reexamine the DYING flag. */ 286 wake_up_all(&q->mq_freeze_wq); 287 } 288 289 /** 290 * blk_cleanup_queue - shutdown a request queue 291 * @q: request queue to shutdown 292 * 293 * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and 294 * put it. All future requests will be failed immediately with -ENODEV. 295 * 296 * Context: can sleep 297 */ 298 void blk_cleanup_queue(struct request_queue *q) 299 { 300 /* cannot be called from atomic context */ 301 might_sleep(); 302 303 WARN_ON_ONCE(blk_queue_registered(q)); 304 305 /* mark @q DYING, no new request or merges will be allowed afterwards */ 306 blk_queue_flag_set(QUEUE_FLAG_DYING, q); 307 blk_queue_start_drain(q); 308 309 blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q); 310 blk_queue_flag_set(QUEUE_FLAG_NOXMERGES, q); 311 312 /* 313 * Drain all requests queued before DYING marking. Set DEAD flag to 314 * prevent that blk_mq_run_hw_queues() accesses the hardware queues 315 * after draining finished. 316 */ 317 blk_freeze_queue(q); 318 319 /* cleanup rq qos structures for queue without disk */ 320 rq_qos_exit(q); 321 322 blk_queue_flag_set(QUEUE_FLAG_DEAD, q); 323 324 blk_sync_queue(q); 325 if (queue_is_mq(q)) { 326 blk_mq_cancel_work_sync(q); 327 blk_mq_exit_queue(q); 328 } 329 330 /* 331 * In theory, request pool of sched_tags belongs to request queue. 332 * However, the current implementation requires tag_set for freeing 333 * requests, so free the pool now. 334 * 335 * Queue has become frozen, there can't be any in-queue requests, so 336 * it is safe to free requests now. 337 */ 338 mutex_lock(&q->sysfs_lock); 339 if (q->elevator) 340 blk_mq_sched_free_rqs(q); 341 mutex_unlock(&q->sysfs_lock); 342 343 /* @q is and will stay empty, shutdown and put */ 344 blk_put_queue(q); 345 } 346 EXPORT_SYMBOL(blk_cleanup_queue); 347 348 /** 349 * blk_queue_enter() - try to increase q->q_usage_counter 350 * @q: request queue pointer 351 * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PM 352 */ 353 int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) 354 { 355 const bool pm = flags & BLK_MQ_REQ_PM; 356 357 while (!blk_try_enter_queue(q, pm)) { 358 if (flags & BLK_MQ_REQ_NOWAIT) 359 return -EBUSY; 360 361 /* 362 * read pair of barrier in blk_freeze_queue_start(), we need to 363 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and 364 * reading .mq_freeze_depth or queue dying flag, otherwise the 365 * following wait may never return if the two reads are 366 * reordered. 367 */ 368 smp_rmb(); 369 wait_event(q->mq_freeze_wq, 370 (!q->mq_freeze_depth && 371 blk_pm_resume_queue(pm, q)) || 372 blk_queue_dying(q)); 373 if (blk_queue_dying(q)) 374 return -ENODEV; 375 } 376 377 return 0; 378 } 379 380 int __bio_queue_enter(struct request_queue *q, struct bio *bio) 381 { 382 while (!blk_try_enter_queue(q, false)) { 383 struct gendisk *disk = bio->bi_bdev->bd_disk; 384 385 if (bio->bi_opf & REQ_NOWAIT) { 386 if (test_bit(GD_DEAD, &disk->state)) 387 goto dead; 388 bio_wouldblock_error(bio); 389 return -EBUSY; 390 } 391 392 /* 393 * read pair of barrier in blk_freeze_queue_start(), we need to 394 * order reading __PERCPU_REF_DEAD flag of .q_usage_counter and 395 * reading .mq_freeze_depth or queue dying flag, otherwise the 396 * following wait may never return if the two reads are 397 * reordered. 398 */ 399 smp_rmb(); 400 wait_event(q->mq_freeze_wq, 401 (!q->mq_freeze_depth && 402 blk_pm_resume_queue(false, q)) || 403 test_bit(GD_DEAD, &disk->state)); 404 if (test_bit(GD_DEAD, &disk->state)) 405 goto dead; 406 } 407 408 return 0; 409 dead: 410 bio_io_error(bio); 411 return -ENODEV; 412 } 413 414 void blk_queue_exit(struct request_queue *q) 415 { 416 percpu_ref_put(&q->q_usage_counter); 417 } 418 419 static void blk_queue_usage_counter_release(struct percpu_ref *ref) 420 { 421 struct request_queue *q = 422 container_of(ref, struct request_queue, q_usage_counter); 423 424 wake_up_all(&q->mq_freeze_wq); 425 } 426 427 static void blk_rq_timed_out_timer(struct timer_list *t) 428 { 429 struct request_queue *q = from_timer(q, t, timeout); 430 431 kblockd_schedule_work(&q->timeout_work); 432 } 433 434 static void blk_timeout_work(struct work_struct *work) 435 { 436 } 437 438 struct request_queue *blk_alloc_queue(int node_id, bool alloc_srcu) 439 { 440 struct request_queue *q; 441 int ret; 442 443 q = kmem_cache_alloc_node(blk_get_queue_kmem_cache(alloc_srcu), 444 GFP_KERNEL | __GFP_ZERO, node_id); 445 if (!q) 446 return NULL; 447 448 if (alloc_srcu) { 449 blk_queue_flag_set(QUEUE_FLAG_HAS_SRCU, q); 450 if (init_srcu_struct(q->srcu) != 0) 451 goto fail_q; 452 } 453 454 q->last_merge = NULL; 455 456 q->id = ida_simple_get(&blk_queue_ida, 0, 0, GFP_KERNEL); 457 if (q->id < 0) 458 goto fail_srcu; 459 460 ret = bioset_init(&q->bio_split, BIO_POOL_SIZE, 0, 0); 461 if (ret) 462 goto fail_id; 463 464 q->stats = blk_alloc_queue_stats(); 465 if (!q->stats) 466 goto fail_split; 467 468 q->node = node_id; 469 470 atomic_set(&q->nr_active_requests_shared_tags, 0); 471 472 timer_setup(&q->timeout, blk_rq_timed_out_timer, 0); 473 INIT_WORK(&q->timeout_work, blk_timeout_work); 474 INIT_LIST_HEAD(&q->icq_list); 475 476 kobject_init(&q->kobj, &blk_queue_ktype); 477 478 mutex_init(&q->debugfs_mutex); 479 mutex_init(&q->sysfs_lock); 480 mutex_init(&q->sysfs_dir_lock); 481 spin_lock_init(&q->queue_lock); 482 483 init_waitqueue_head(&q->mq_freeze_wq); 484 mutex_init(&q->mq_freeze_lock); 485 486 /* 487 * Init percpu_ref in atomic mode so that it's faster to shutdown. 488 * See blk_register_queue() for details. 489 */ 490 if (percpu_ref_init(&q->q_usage_counter, 491 blk_queue_usage_counter_release, 492 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL)) 493 goto fail_stats; 494 495 blk_queue_dma_alignment(q, 511); 496 blk_set_default_limits(&q->limits); 497 q->nr_requests = BLKDEV_DEFAULT_RQ; 498 499 return q; 500 501 fail_stats: 502 blk_free_queue_stats(q->stats); 503 fail_split: 504 bioset_exit(&q->bio_split); 505 fail_id: 506 ida_simple_remove(&blk_queue_ida, q->id); 507 fail_srcu: 508 if (alloc_srcu) 509 cleanup_srcu_struct(q->srcu); 510 fail_q: 511 kmem_cache_free(blk_get_queue_kmem_cache(alloc_srcu), q); 512 return NULL; 513 } 514 515 /** 516 * blk_get_queue - increment the request_queue refcount 517 * @q: the request_queue structure to increment the refcount for 518 * 519 * Increment the refcount of the request_queue kobject. 520 * 521 * Context: Any context. 522 */ 523 bool blk_get_queue(struct request_queue *q) 524 { 525 if (likely(!blk_queue_dying(q))) { 526 __blk_get_queue(q); 527 return true; 528 } 529 530 return false; 531 } 532 EXPORT_SYMBOL(blk_get_queue); 533 534 #ifdef CONFIG_FAIL_MAKE_REQUEST 535 536 static DECLARE_FAULT_ATTR(fail_make_request); 537 538 static int __init setup_fail_make_request(char *str) 539 { 540 return setup_fault_attr(&fail_make_request, str); 541 } 542 __setup("fail_make_request=", setup_fail_make_request); 543 544 bool should_fail_request(struct block_device *part, unsigned int bytes) 545 { 546 return part->bd_make_it_fail && should_fail(&fail_make_request, bytes); 547 } 548 549 static int __init fail_make_request_debugfs(void) 550 { 551 struct dentry *dir = fault_create_debugfs_attr("fail_make_request", 552 NULL, &fail_make_request); 553 554 return PTR_ERR_OR_ZERO(dir); 555 } 556 557 late_initcall(fail_make_request_debugfs); 558 #endif /* CONFIG_FAIL_MAKE_REQUEST */ 559 560 static inline bool bio_check_ro(struct bio *bio) 561 { 562 if (op_is_write(bio_op(bio)) && bdev_read_only(bio->bi_bdev)) { 563 if (op_is_flush(bio->bi_opf) && !bio_sectors(bio)) 564 return false; 565 pr_warn("Trying to write to read-only block-device %pg\n", 566 bio->bi_bdev); 567 /* Older lvm-tools actually trigger this */ 568 return false; 569 } 570 571 return false; 572 } 573 574 static noinline int should_fail_bio(struct bio *bio) 575 { 576 if (should_fail_request(bdev_whole(bio->bi_bdev), bio->bi_iter.bi_size)) 577 return -EIO; 578 return 0; 579 } 580 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO); 581 582 /* 583 * Check whether this bio extends beyond the end of the device or partition. 584 * This may well happen - the kernel calls bread() without checking the size of 585 * the device, e.g., when mounting a file system. 586 */ 587 static inline int bio_check_eod(struct bio *bio) 588 { 589 sector_t maxsector = bdev_nr_sectors(bio->bi_bdev); 590 unsigned int nr_sectors = bio_sectors(bio); 591 592 if (nr_sectors && maxsector && 593 (nr_sectors > maxsector || 594 bio->bi_iter.bi_sector > maxsector - nr_sectors)) { 595 pr_info_ratelimited("%s: attempt to access beyond end of device\n" 596 "%pg: rw=%d, want=%llu, limit=%llu\n", 597 current->comm, 598 bio->bi_bdev, bio->bi_opf, 599 bio_end_sector(bio), maxsector); 600 return -EIO; 601 } 602 return 0; 603 } 604 605 /* 606 * Remap block n of partition p to block n+start(p) of the disk. 607 */ 608 static int blk_partition_remap(struct bio *bio) 609 { 610 struct block_device *p = bio->bi_bdev; 611 612 if (unlikely(should_fail_request(p, bio->bi_iter.bi_size))) 613 return -EIO; 614 if (bio_sectors(bio)) { 615 bio->bi_iter.bi_sector += p->bd_start_sect; 616 trace_block_bio_remap(bio, p->bd_dev, 617 bio->bi_iter.bi_sector - 618 p->bd_start_sect); 619 } 620 bio_set_flag(bio, BIO_REMAPPED); 621 return 0; 622 } 623 624 /* 625 * Check write append to a zoned block device. 626 */ 627 static inline blk_status_t blk_check_zone_append(struct request_queue *q, 628 struct bio *bio) 629 { 630 sector_t pos = bio->bi_iter.bi_sector; 631 int nr_sectors = bio_sectors(bio); 632 633 /* Only applicable to zoned block devices */ 634 if (!blk_queue_is_zoned(q)) 635 return BLK_STS_NOTSUPP; 636 637 /* The bio sector must point to the start of a sequential zone */ 638 if (pos & (blk_queue_zone_sectors(q) - 1) || 639 !blk_queue_zone_is_seq(q, pos)) 640 return BLK_STS_IOERR; 641 642 /* 643 * Not allowed to cross zone boundaries. Otherwise, the BIO will be 644 * split and could result in non-contiguous sectors being written in 645 * different zones. 646 */ 647 if (nr_sectors > q->limits.chunk_sectors) 648 return BLK_STS_IOERR; 649 650 /* Make sure the BIO is small enough and will not get split */ 651 if (nr_sectors > q->limits.max_zone_append_sectors) 652 return BLK_STS_IOERR; 653 654 bio->bi_opf |= REQ_NOMERGE; 655 656 return BLK_STS_OK; 657 } 658 659 static void __submit_bio(struct bio *bio) 660 { 661 struct gendisk *disk = bio->bi_bdev->bd_disk; 662 663 if (unlikely(!blk_crypto_bio_prep(&bio))) 664 return; 665 666 if (!disk->fops->submit_bio) { 667 blk_mq_submit_bio(bio); 668 } else if (likely(bio_queue_enter(bio) == 0)) { 669 disk->fops->submit_bio(bio); 670 blk_queue_exit(disk->queue); 671 } 672 } 673 674 /* 675 * The loop in this function may be a bit non-obvious, and so deserves some 676 * explanation: 677 * 678 * - Before entering the loop, bio->bi_next is NULL (as all callers ensure 679 * that), so we have a list with a single bio. 680 * - We pretend that we have just taken it off a longer list, so we assign 681 * bio_list to a pointer to the bio_list_on_stack, thus initialising the 682 * bio_list of new bios to be added. ->submit_bio() may indeed add some more 683 * bios through a recursive call to submit_bio_noacct. If it did, we find a 684 * non-NULL value in bio_list and re-enter the loop from the top. 685 * - In this case we really did just take the bio of the top of the list (no 686 * pretending) and so remove it from bio_list, and call into ->submit_bio() 687 * again. 688 * 689 * bio_list_on_stack[0] contains bios submitted by the current ->submit_bio. 690 * bio_list_on_stack[1] contains bios that were submitted before the current 691 * ->submit_bio_bio, but that haven't been processed yet. 692 */ 693 static void __submit_bio_noacct(struct bio *bio) 694 { 695 struct bio_list bio_list_on_stack[2]; 696 697 BUG_ON(bio->bi_next); 698 699 bio_list_init(&bio_list_on_stack[0]); 700 current->bio_list = bio_list_on_stack; 701 702 do { 703 struct request_queue *q = bdev_get_queue(bio->bi_bdev); 704 struct bio_list lower, same; 705 706 /* 707 * Create a fresh bio_list for all subordinate requests. 708 */ 709 bio_list_on_stack[1] = bio_list_on_stack[0]; 710 bio_list_init(&bio_list_on_stack[0]); 711 712 __submit_bio(bio); 713 714 /* 715 * Sort new bios into those for a lower level and those for the 716 * same level. 717 */ 718 bio_list_init(&lower); 719 bio_list_init(&same); 720 while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL) 721 if (q == bdev_get_queue(bio->bi_bdev)) 722 bio_list_add(&same, bio); 723 else 724 bio_list_add(&lower, bio); 725 726 /* 727 * Now assemble so we handle the lowest level first. 728 */ 729 bio_list_merge(&bio_list_on_stack[0], &lower); 730 bio_list_merge(&bio_list_on_stack[0], &same); 731 bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]); 732 } while ((bio = bio_list_pop(&bio_list_on_stack[0]))); 733 734 current->bio_list = NULL; 735 } 736 737 static void __submit_bio_noacct_mq(struct bio *bio) 738 { 739 struct bio_list bio_list[2] = { }; 740 741 current->bio_list = bio_list; 742 743 do { 744 __submit_bio(bio); 745 } while ((bio = bio_list_pop(&bio_list[0]))); 746 747 current->bio_list = NULL; 748 } 749 750 void submit_bio_noacct_nocheck(struct bio *bio) 751 { 752 /* 753 * We only want one ->submit_bio to be active at a time, else stack 754 * usage with stacked devices could be a problem. Use current->bio_list 755 * to collect a list of requests submited by a ->submit_bio method while 756 * it is active, and then process them after it returned. 757 */ 758 if (current->bio_list) 759 bio_list_add(¤t->bio_list[0], bio); 760 else if (!bio->bi_bdev->bd_disk->fops->submit_bio) 761 __submit_bio_noacct_mq(bio); 762 else 763 __submit_bio_noacct(bio); 764 } 765 766 /** 767 * submit_bio_noacct - re-submit a bio to the block device layer for I/O 768 * @bio: The bio describing the location in memory and on the device. 769 * 770 * This is a version of submit_bio() that shall only be used for I/O that is 771 * resubmitted to lower level drivers by stacking block drivers. All file 772 * systems and other upper level users of the block layer should use 773 * submit_bio() instead. 774 */ 775 void submit_bio_noacct(struct bio *bio) 776 { 777 struct block_device *bdev = bio->bi_bdev; 778 struct request_queue *q = bdev_get_queue(bdev); 779 blk_status_t status = BLK_STS_IOERR; 780 struct blk_plug *plug; 781 782 might_sleep(); 783 784 plug = blk_mq_plug(q, bio); 785 if (plug && plug->nowait) 786 bio->bi_opf |= REQ_NOWAIT; 787 788 /* 789 * For a REQ_NOWAIT based request, return -EOPNOTSUPP 790 * if queue does not support NOWAIT. 791 */ 792 if ((bio->bi_opf & REQ_NOWAIT) && !blk_queue_nowait(q)) 793 goto not_supported; 794 795 if (should_fail_bio(bio)) 796 goto end_io; 797 if (unlikely(bio_check_ro(bio))) 798 goto end_io; 799 if (!bio_flagged(bio, BIO_REMAPPED)) { 800 if (unlikely(bio_check_eod(bio))) 801 goto end_io; 802 if (bdev->bd_partno && unlikely(blk_partition_remap(bio))) 803 goto end_io; 804 } 805 806 /* 807 * Filter flush bio's early so that bio based drivers without flush 808 * support don't have to worry about them. 809 */ 810 if (op_is_flush(bio->bi_opf) && 811 !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) { 812 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA); 813 if (!bio_sectors(bio)) { 814 status = BLK_STS_OK; 815 goto end_io; 816 } 817 } 818 819 if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) 820 bio_clear_polled(bio); 821 822 switch (bio_op(bio)) { 823 case REQ_OP_DISCARD: 824 if (!blk_queue_discard(q)) 825 goto not_supported; 826 break; 827 case REQ_OP_SECURE_ERASE: 828 if (!blk_queue_secure_erase(q)) 829 goto not_supported; 830 break; 831 case REQ_OP_WRITE_SAME: 832 if (!q->limits.max_write_same_sectors) 833 goto not_supported; 834 break; 835 case REQ_OP_ZONE_APPEND: 836 status = blk_check_zone_append(q, bio); 837 if (status != BLK_STS_OK) 838 goto end_io; 839 break; 840 case REQ_OP_ZONE_RESET: 841 case REQ_OP_ZONE_OPEN: 842 case REQ_OP_ZONE_CLOSE: 843 case REQ_OP_ZONE_FINISH: 844 if (!blk_queue_is_zoned(q)) 845 goto not_supported; 846 break; 847 case REQ_OP_ZONE_RESET_ALL: 848 if (!blk_queue_is_zoned(q) || !blk_queue_zone_resetall(q)) 849 goto not_supported; 850 break; 851 case REQ_OP_WRITE_ZEROES: 852 if (!q->limits.max_write_zeroes_sectors) 853 goto not_supported; 854 break; 855 default: 856 break; 857 } 858 859 if (blk_throtl_bio(bio)) 860 return; 861 862 blk_cgroup_bio_start(bio); 863 blkcg_bio_issue_init(bio); 864 865 if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) { 866 trace_block_bio_queue(bio); 867 /* Now that enqueuing has been traced, we need to trace 868 * completion as well. 869 */ 870 bio_set_flag(bio, BIO_TRACE_COMPLETION); 871 } 872 submit_bio_noacct_nocheck(bio); 873 return; 874 875 not_supported: 876 status = BLK_STS_NOTSUPP; 877 end_io: 878 bio->bi_status = status; 879 bio_endio(bio); 880 } 881 EXPORT_SYMBOL(submit_bio_noacct); 882 883 /** 884 * submit_bio - submit a bio to the block device layer for I/O 885 * @bio: The &struct bio which describes the I/O 886 * 887 * submit_bio() is used to submit I/O requests to block devices. It is passed a 888 * fully set up &struct bio that describes the I/O that needs to be done. The 889 * bio will be send to the device described by the bi_bdev field. 890 * 891 * The success/failure status of the request, along with notification of 892 * completion, is delivered asynchronously through the ->bi_end_io() callback 893 * in @bio. The bio must NOT be touched by thecaller until ->bi_end_io() has 894 * been called. 895 */ 896 void submit_bio(struct bio *bio) 897 { 898 if (blkcg_punt_bio_submit(bio)) 899 return; 900 901 /* 902 * If it's a regular read/write or a barrier with data attached, 903 * go through the normal accounting stuff before submission. 904 */ 905 if (bio_has_data(bio)) { 906 unsigned int count; 907 908 if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME)) 909 count = queue_logical_block_size( 910 bdev_get_queue(bio->bi_bdev)) >> 9; 911 else 912 count = bio_sectors(bio); 913 914 if (op_is_write(bio_op(bio))) { 915 count_vm_events(PGPGOUT, count); 916 } else { 917 task_io_account_read(bio->bi_iter.bi_size); 918 count_vm_events(PGPGIN, count); 919 } 920 } 921 922 /* 923 * If we're reading data that is part of the userspace workingset, count 924 * submission time as memory stall. When the device is congested, or 925 * the submitting cgroup IO-throttled, submission can be a significant 926 * part of overall IO time. 927 */ 928 if (unlikely(bio_op(bio) == REQ_OP_READ && 929 bio_flagged(bio, BIO_WORKINGSET))) { 930 unsigned long pflags; 931 932 psi_memstall_enter(&pflags); 933 submit_bio_noacct(bio); 934 psi_memstall_leave(&pflags); 935 return; 936 } 937 938 submit_bio_noacct(bio); 939 } 940 EXPORT_SYMBOL(submit_bio); 941 942 /** 943 * bio_poll - poll for BIO completions 944 * @bio: bio to poll for 945 * @iob: batches of IO 946 * @flags: BLK_POLL_* flags that control the behavior 947 * 948 * Poll for completions on queue associated with the bio. Returns number of 949 * completed entries found. 950 * 951 * Note: the caller must either be the context that submitted @bio, or 952 * be in a RCU critical section to prevent freeing of @bio. 953 */ 954 int bio_poll(struct bio *bio, struct io_comp_batch *iob, unsigned int flags) 955 { 956 struct request_queue *q = bdev_get_queue(bio->bi_bdev); 957 blk_qc_t cookie = READ_ONCE(bio->bi_cookie); 958 int ret; 959 960 if (cookie == BLK_QC_T_NONE || 961 !test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) 962 return 0; 963 964 blk_flush_plug(current->plug, false); 965 966 if (blk_queue_enter(q, BLK_MQ_REQ_NOWAIT)) 967 return 0; 968 if (WARN_ON_ONCE(!queue_is_mq(q))) 969 ret = 0; /* not yet implemented, should not happen */ 970 else 971 ret = blk_mq_poll(q, cookie, iob, flags); 972 blk_queue_exit(q); 973 return ret; 974 } 975 EXPORT_SYMBOL_GPL(bio_poll); 976 977 /* 978 * Helper to implement file_operations.iopoll. Requires the bio to be stored 979 * in iocb->private, and cleared before freeing the bio. 980 */ 981 int iocb_bio_iopoll(struct kiocb *kiocb, struct io_comp_batch *iob, 982 unsigned int flags) 983 { 984 struct bio *bio; 985 int ret = 0; 986 987 /* 988 * Note: the bio cache only uses SLAB_TYPESAFE_BY_RCU, so bio can 989 * point to a freshly allocated bio at this point. If that happens 990 * we have a few cases to consider: 991 * 992 * 1) the bio is beeing initialized and bi_bdev is NULL. We can just 993 * simply nothing in this case 994 * 2) the bio points to a not poll enabled device. bio_poll will catch 995 * this and return 0 996 * 3) the bio points to a poll capable device, including but not 997 * limited to the one that the original bio pointed to. In this 998 * case we will call into the actual poll method and poll for I/O, 999 * even if we don't need to, but it won't cause harm either. 1000 * 1001 * For cases 2) and 3) above the RCU grace period ensures that bi_bdev 1002 * is still allocated. Because partitions hold a reference to the whole 1003 * device bdev and thus disk, the disk is also still valid. Grabbing 1004 * a reference to the queue in bio_poll() ensures the hctxs and requests 1005 * are still valid as well. 1006 */ 1007 rcu_read_lock(); 1008 bio = READ_ONCE(kiocb->private); 1009 if (bio && bio->bi_bdev) 1010 ret = bio_poll(bio, iob, flags); 1011 rcu_read_unlock(); 1012 1013 return ret; 1014 } 1015 EXPORT_SYMBOL_GPL(iocb_bio_iopoll); 1016 1017 void update_io_ticks(struct block_device *part, unsigned long now, bool end) 1018 { 1019 unsigned long stamp; 1020 again: 1021 stamp = READ_ONCE(part->bd_stamp); 1022 if (unlikely(time_after(now, stamp))) { 1023 if (likely(cmpxchg(&part->bd_stamp, stamp, now) == stamp)) 1024 __part_stat_add(part, io_ticks, end ? now - stamp : 1); 1025 } 1026 if (part->bd_partno) { 1027 part = bdev_whole(part); 1028 goto again; 1029 } 1030 } 1031 1032 static unsigned long __part_start_io_acct(struct block_device *part, 1033 unsigned int sectors, unsigned int op, 1034 unsigned long start_time) 1035 { 1036 const int sgrp = op_stat_group(op); 1037 1038 part_stat_lock(); 1039 update_io_ticks(part, start_time, false); 1040 part_stat_inc(part, ios[sgrp]); 1041 part_stat_add(part, sectors[sgrp], sectors); 1042 part_stat_local_inc(part, in_flight[op_is_write(op)]); 1043 part_stat_unlock(); 1044 1045 return start_time; 1046 } 1047 1048 /** 1049 * bio_start_io_acct_time - start I/O accounting for bio based drivers 1050 * @bio: bio to start account for 1051 * @start_time: start time that should be passed back to bio_end_io_acct(). 1052 */ 1053 void bio_start_io_acct_time(struct bio *bio, unsigned long start_time) 1054 { 1055 __part_start_io_acct(bio->bi_bdev, bio_sectors(bio), 1056 bio_op(bio), start_time); 1057 } 1058 EXPORT_SYMBOL_GPL(bio_start_io_acct_time); 1059 1060 /** 1061 * bio_start_io_acct - start I/O accounting for bio based drivers 1062 * @bio: bio to start account for 1063 * 1064 * Returns the start time that should be passed back to bio_end_io_acct(). 1065 */ 1066 unsigned long bio_start_io_acct(struct bio *bio) 1067 { 1068 return __part_start_io_acct(bio->bi_bdev, bio_sectors(bio), 1069 bio_op(bio), jiffies); 1070 } 1071 EXPORT_SYMBOL_GPL(bio_start_io_acct); 1072 1073 unsigned long disk_start_io_acct(struct gendisk *disk, unsigned int sectors, 1074 unsigned int op) 1075 { 1076 return __part_start_io_acct(disk->part0, sectors, op, jiffies); 1077 } 1078 EXPORT_SYMBOL(disk_start_io_acct); 1079 1080 static void __part_end_io_acct(struct block_device *part, unsigned int op, 1081 unsigned long start_time) 1082 { 1083 const int sgrp = op_stat_group(op); 1084 unsigned long now = READ_ONCE(jiffies); 1085 unsigned long duration = now - start_time; 1086 1087 part_stat_lock(); 1088 update_io_ticks(part, now, true); 1089 part_stat_add(part, nsecs[sgrp], jiffies_to_nsecs(duration)); 1090 part_stat_local_dec(part, in_flight[op_is_write(op)]); 1091 part_stat_unlock(); 1092 } 1093 1094 void bio_end_io_acct_remapped(struct bio *bio, unsigned long start_time, 1095 struct block_device *orig_bdev) 1096 { 1097 __part_end_io_acct(orig_bdev, bio_op(bio), start_time); 1098 } 1099 EXPORT_SYMBOL_GPL(bio_end_io_acct_remapped); 1100 1101 void disk_end_io_acct(struct gendisk *disk, unsigned int op, 1102 unsigned long start_time) 1103 { 1104 __part_end_io_acct(disk->part0, op, start_time); 1105 } 1106 EXPORT_SYMBOL(disk_end_io_acct); 1107 1108 /** 1109 * blk_lld_busy - Check if underlying low-level drivers of a device are busy 1110 * @q : the queue of the device being checked 1111 * 1112 * Description: 1113 * Check if underlying low-level drivers of a device are busy. 1114 * If the drivers want to export their busy state, they must set own 1115 * exporting function using blk_queue_lld_busy() first. 1116 * 1117 * Basically, this function is used only by request stacking drivers 1118 * to stop dispatching requests to underlying devices when underlying 1119 * devices are busy. This behavior helps more I/O merging on the queue 1120 * of the request stacking driver and prevents I/O throughput regression 1121 * on burst I/O load. 1122 * 1123 * Return: 1124 * 0 - Not busy (The request stacking driver should dispatch request) 1125 * 1 - Busy (The request stacking driver should stop dispatching request) 1126 */ 1127 int blk_lld_busy(struct request_queue *q) 1128 { 1129 if (queue_is_mq(q) && q->mq_ops->busy) 1130 return q->mq_ops->busy(q); 1131 1132 return 0; 1133 } 1134 EXPORT_SYMBOL_GPL(blk_lld_busy); 1135 1136 int kblockd_schedule_work(struct work_struct *work) 1137 { 1138 return queue_work(kblockd_workqueue, work); 1139 } 1140 EXPORT_SYMBOL(kblockd_schedule_work); 1141 1142 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork, 1143 unsigned long delay) 1144 { 1145 return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay); 1146 } 1147 EXPORT_SYMBOL(kblockd_mod_delayed_work_on); 1148 1149 void blk_start_plug_nr_ios(struct blk_plug *plug, unsigned short nr_ios) 1150 { 1151 struct task_struct *tsk = current; 1152 1153 /* 1154 * If this is a nested plug, don't actually assign it. 1155 */ 1156 if (tsk->plug) 1157 return; 1158 1159 plug->mq_list = NULL; 1160 plug->cached_rq = NULL; 1161 plug->nr_ios = min_t(unsigned short, nr_ios, BLK_MAX_REQUEST_COUNT); 1162 plug->rq_count = 0; 1163 plug->multiple_queues = false; 1164 plug->has_elevator = false; 1165 plug->nowait = false; 1166 INIT_LIST_HEAD(&plug->cb_list); 1167 1168 /* 1169 * Store ordering should not be needed here, since a potential 1170 * preempt will imply a full memory barrier 1171 */ 1172 tsk->plug = plug; 1173 } 1174 1175 /** 1176 * blk_start_plug - initialize blk_plug and track it inside the task_struct 1177 * @plug: The &struct blk_plug that needs to be initialized 1178 * 1179 * Description: 1180 * blk_start_plug() indicates to the block layer an intent by the caller 1181 * to submit multiple I/O requests in a batch. The block layer may use 1182 * this hint to defer submitting I/Os from the caller until blk_finish_plug() 1183 * is called. However, the block layer may choose to submit requests 1184 * before a call to blk_finish_plug() if the number of queued I/Os 1185 * exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than 1186 * %BLK_PLUG_FLUSH_SIZE. The queued I/Os may also be submitted early if 1187 * the task schedules (see below). 1188 * 1189 * Tracking blk_plug inside the task_struct will help with auto-flushing the 1190 * pending I/O should the task end up blocking between blk_start_plug() and 1191 * blk_finish_plug(). This is important from a performance perspective, but 1192 * also ensures that we don't deadlock. For instance, if the task is blocking 1193 * for a memory allocation, memory reclaim could end up wanting to free a 1194 * page belonging to that request that is currently residing in our private 1195 * plug. By flushing the pending I/O when the process goes to sleep, we avoid 1196 * this kind of deadlock. 1197 */ 1198 void blk_start_plug(struct blk_plug *plug) 1199 { 1200 blk_start_plug_nr_ios(plug, 1); 1201 } 1202 EXPORT_SYMBOL(blk_start_plug); 1203 1204 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule) 1205 { 1206 LIST_HEAD(callbacks); 1207 1208 while (!list_empty(&plug->cb_list)) { 1209 list_splice_init(&plug->cb_list, &callbacks); 1210 1211 while (!list_empty(&callbacks)) { 1212 struct blk_plug_cb *cb = list_first_entry(&callbacks, 1213 struct blk_plug_cb, 1214 list); 1215 list_del(&cb->list); 1216 cb->callback(cb, from_schedule); 1217 } 1218 } 1219 } 1220 1221 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data, 1222 int size) 1223 { 1224 struct blk_plug *plug = current->plug; 1225 struct blk_plug_cb *cb; 1226 1227 if (!plug) 1228 return NULL; 1229 1230 list_for_each_entry(cb, &plug->cb_list, list) 1231 if (cb->callback == unplug && cb->data == data) 1232 return cb; 1233 1234 /* Not currently on the callback list */ 1235 BUG_ON(size < sizeof(*cb)); 1236 cb = kzalloc(size, GFP_ATOMIC); 1237 if (cb) { 1238 cb->data = data; 1239 cb->callback = unplug; 1240 list_add(&cb->list, &plug->cb_list); 1241 } 1242 return cb; 1243 } 1244 EXPORT_SYMBOL(blk_check_plugged); 1245 1246 void __blk_flush_plug(struct blk_plug *plug, bool from_schedule) 1247 { 1248 if (!list_empty(&plug->cb_list)) 1249 flush_plug_callbacks(plug, from_schedule); 1250 if (!rq_list_empty(plug->mq_list)) 1251 blk_mq_flush_plug_list(plug, from_schedule); 1252 /* 1253 * Unconditionally flush out cached requests, even if the unplug 1254 * event came from schedule. Since we know hold references to the 1255 * queue for cached requests, we don't want a blocked task holding 1256 * up a queue freeze/quiesce event. 1257 */ 1258 if (unlikely(!rq_list_empty(plug->cached_rq))) 1259 blk_mq_free_plug_rqs(plug); 1260 } 1261 1262 /** 1263 * blk_finish_plug - mark the end of a batch of submitted I/O 1264 * @plug: The &struct blk_plug passed to blk_start_plug() 1265 * 1266 * Description: 1267 * Indicate that a batch of I/O submissions is complete. This function 1268 * must be paired with an initial call to blk_start_plug(). The intent 1269 * is to allow the block layer to optimize I/O submission. See the 1270 * documentation for blk_start_plug() for more information. 1271 */ 1272 void blk_finish_plug(struct blk_plug *plug) 1273 { 1274 if (plug == current->plug) { 1275 __blk_flush_plug(plug, false); 1276 current->plug = NULL; 1277 } 1278 } 1279 EXPORT_SYMBOL(blk_finish_plug); 1280 1281 void blk_io_schedule(void) 1282 { 1283 /* Prevent hang_check timer from firing at us during very long I/O */ 1284 unsigned long timeout = sysctl_hung_task_timeout_secs * HZ / 2; 1285 1286 if (timeout) 1287 io_schedule_timeout(timeout); 1288 else 1289 io_schedule(); 1290 } 1291 EXPORT_SYMBOL_GPL(blk_io_schedule); 1292 1293 int __init blk_dev_init(void) 1294 { 1295 BUILD_BUG_ON(REQ_OP_LAST >= (1 << REQ_OP_BITS)); 1296 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1297 sizeof_field(struct request, cmd_flags)); 1298 BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 * 1299 sizeof_field(struct bio, bi_opf)); 1300 BUILD_BUG_ON(ALIGN(offsetof(struct request_queue, srcu), 1301 __alignof__(struct request_queue)) != 1302 sizeof(struct request_queue)); 1303 1304 /* used for unplugging and affects IO latency/throughput - HIGHPRI */ 1305 kblockd_workqueue = alloc_workqueue("kblockd", 1306 WQ_MEM_RECLAIM | WQ_HIGHPRI, 0); 1307 if (!kblockd_workqueue) 1308 panic("Failed to create kblockd\n"); 1309 1310 blk_requestq_cachep = kmem_cache_create("request_queue", 1311 sizeof(struct request_queue), 0, SLAB_PANIC, NULL); 1312 1313 blk_requestq_srcu_cachep = kmem_cache_create("request_queue_srcu", 1314 sizeof(struct request_queue) + 1315 sizeof(struct srcu_struct), 0, SLAB_PANIC, NULL); 1316 1317 blk_debugfs_root = debugfs_create_dir("block", NULL); 1318 1319 return 0; 1320 } 1321