block/blk-core.c

/* [<][>][^][v][top][bottom][index][help] */
This source file includes following definitions.
blk_queue_flag_set
blk_queue_flag_clear
blk_queue_flag_test_and_set
blk_rq_init
blk_op_str
errno_to_blk_status
blk_status_to_errno
print_req_error
req_bio_endio
blk_dump_rq_flags
blk_sync_queue
blk_set_pm_only
blk_clear_pm_only
blk_put_queue
blk_set_queue_dying
blk_cleanup_queue
blk_alloc_queue
blk_queue_enter
blk_queue_exit
blk_queue_usage_counter_release
blk_rq_timed_out_timer
blk_timeout_work
blk_alloc_queue_node
blk_get_queue
blk_get_request
blk_put_request
bio_attempt_back_merge
bio_attempt_front_merge
bio_attempt_discard_merge
blk_attempt_plug_merge
handle_bad_sector
setup_fail_make_request
should_fail_request
fail_make_request_debugfs
should_fail_request
bio_check_ro
should_fail_bio
bio_check_eod
blk_partition_remap
generic_make_request_checks
generic_make_request
direct_make_request
submit_bio
blk_cloned_rq_check_limits
blk_insert_cloned_request
blk_rq_err_bytes
blk_account_io_completion
blk_account_io_done
blk_account_io_start
blk_steal_bios
blk_update_request
rq_flush_dcache_pages
blk_lld_busy
blk_rq_unprep_clone
__blk_rq_prep_clone
blk_rq_prep_clone
kblockd_schedule_work
kblockd_schedule_work_on
kblockd_mod_delayed_work_on
blk_start_plug
flush_plug_callbacks
blk_check_plugged
blk_flush_plug_list
blk_finish_plug
blk_dev_init
   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/backing-dev.h>
  18 #include <linux/bio.h>
  19 #include <linux/blkdev.h>
  20 #include <linux/blk-mq.h>
  21 #include <linux/highmem.h>
  22 #include <linux/mm.h>
  23 #include <linux/kernel_stat.h>
  24 #include <linux/string.h>
  25 #include <linux/init.h>
  26 #include <linux/completion.h>
  27 #include <linux/slab.h>
  28 #include <linux/swap.h>
  29 #include <linux/writeback.h>
  30 #include <linux/task_io_accounting_ops.h>
  31 #include <linux/fault-inject.h>
  32 #include <linux/list_sort.h>
  33 #include <linux/delay.h>
  34 #include <linux/ratelimit.h>
  35 #include <linux/pm_runtime.h>
  36 #include <linux/blk-cgroup.h>
  37 #include <linux/t10-pi.h>
  38 #include <linux/debugfs.h>
  39 #include <linux/bpf.h>
  40 #include <linux/psi.h>
  41 
  42 #define CREATE_TRACE_POINTS
  43 #include <trace/events/block.h>
  44 
  45 #include "blk.h"
  46 #include "blk-mq.h"
  47 #include "blk-mq-sched.h"
  48 #include "blk-pm.h"
  49 #include "blk-rq-qos.h"
  50 
  51 #ifdef CONFIG_DEBUG_FS
  52 struct dentry *blk_debugfs_root;
  53 #endif
  54 
  55 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_remap);
  56 EXPORT_TRACEPOINT_SYMBOL_GPL(block_rq_remap);
  57 EXPORT_TRACEPOINT_SYMBOL_GPL(block_bio_complete);
  58 EXPORT_TRACEPOINT_SYMBOL_GPL(block_split);
  59 EXPORT_TRACEPOINT_SYMBOL_GPL(block_unplug);
  60 
  61 DEFINE_IDA(blk_queue_ida);
  62 
  63 /*
  64  * For queue allocation
  65  */
  66 struct kmem_cache *blk_requestq_cachep;
  67 
  68 /*
  69  * Controlling structure to kblockd
  70  */
  71 static struct workqueue_struct *kblockd_workqueue;
  72 
  73 /**
  74  * blk_queue_flag_set - atomically set a queue flag
  75  * @flag: flag to be set
  76  * @q: request queue
  77  */
  78 void blk_queue_flag_set(unsigned int flag, struct request_queue *q)
  79 {
  80         set_bit(flag, &q->queue_flags);
  81 }
  82 EXPORT_SYMBOL(blk_queue_flag_set);
  83 
  84 /**
  85  * blk_queue_flag_clear - atomically clear a queue flag
  86  * @flag: flag to be cleared
  87  * @q: request queue
  88  */
  89 void blk_queue_flag_clear(unsigned int flag, struct request_queue *q)
  90 {
  91         clear_bit(flag, &q->queue_flags);
  92 }
  93 EXPORT_SYMBOL(blk_queue_flag_clear);
  94 
  95 /**
  96  * blk_queue_flag_test_and_set - atomically test and set a queue flag
  97  * @flag: flag to be set
  98  * @q: request queue
  99  *
 100  * Returns the previous value of @flag - 0 if the flag was not set and 1 if
 101  * the flag was already set.
 102  */
 103 bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q)
 104 {
 105         return test_and_set_bit(flag, &q->queue_flags);
 106 }
 107 EXPORT_SYMBOL_GPL(blk_queue_flag_test_and_set);
 108 
 109 void blk_rq_init(struct request_queue *q, struct request *rq)
 110 {
 111         memset(rq, 0, sizeof(*rq));
 112 
 113         INIT_LIST_HEAD(&rq->queuelist);
 114         rq->q = q;
 115         rq->__sector = (sector_t) -1;
 116         INIT_HLIST_NODE(&rq->hash);
 117         RB_CLEAR_NODE(&rq->rb_node);
 118         rq->tag = -1;
 119         rq->internal_tag = -1;
 120         rq->start_time_ns = ktime_get_ns();
 121         rq->part = NULL;
 122         refcount_set(&rq->ref, 1);
 123 }
 124 EXPORT_SYMBOL(blk_rq_init);
 125 
 126 #define REQ_OP_NAME(name) [REQ_OP_##name] = #name
 127 static const char *const blk_op_name[] = {
 128         REQ_OP_NAME(READ),
 129         REQ_OP_NAME(WRITE),
 130         REQ_OP_NAME(FLUSH),
 131         REQ_OP_NAME(DISCARD),
 132         REQ_OP_NAME(SECURE_ERASE),
 133         REQ_OP_NAME(ZONE_RESET),
 134         REQ_OP_NAME(ZONE_RESET_ALL),
 135         REQ_OP_NAME(WRITE_SAME),
 136         REQ_OP_NAME(WRITE_ZEROES),
 137         REQ_OP_NAME(SCSI_IN),
 138         REQ_OP_NAME(SCSI_OUT),
 139         REQ_OP_NAME(DRV_IN),
 140         REQ_OP_NAME(DRV_OUT),
 141 };
 142 #undef REQ_OP_NAME
 143 
 144 /**
 145  * blk_op_str - Return string XXX in the REQ_OP_XXX.
 146  * @op: REQ_OP_XXX.
 147  *
 148  * Description: Centralize block layer function to convert REQ_OP_XXX into
 149  * string format. Useful in the debugging and tracing bio or request. For
 150  * invalid REQ_OP_XXX it returns string "UNKNOWN".
 151  */
 152 inline const char *blk_op_str(unsigned int op)
 153 {
 154         const char *op_str = "UNKNOWN";
 155 
 156         if (op < ARRAY_SIZE(blk_op_name) && blk_op_name[op])
 157                 op_str = blk_op_name[op];
 158 
 159         return op_str;
 160 }
 161 EXPORT_SYMBOL_GPL(blk_op_str);
 162 
 163 static const struct {
 164         int             errno;
 165         const char      *name;
 166 } blk_errors[] = {
 167         [BLK_STS_OK]            = { 0,          "" },
 168         [BLK_STS_NOTSUPP]       = { -EOPNOTSUPP, "operation not supported" },
 169         [BLK_STS_TIMEOUT]       = { -ETIMEDOUT, "timeout" },
 170         [BLK_STS_NOSPC]         = { -ENOSPC,    "critical space allocation" },
 171         [BLK_STS_TRANSPORT]     = { -ENOLINK,   "recoverable transport" },
 172         [BLK_STS_TARGET]        = { -EREMOTEIO, "critical target" },
 173         [BLK_STS_NEXUS]         = { -EBADE,     "critical nexus" },
 174         [BLK_STS_MEDIUM]        = { -ENODATA,   "critical medium" },
 175         [BLK_STS_PROTECTION]    = { -EILSEQ,    "protection" },
 176         [BLK_STS_RESOURCE]      = { -ENOMEM,    "kernel resource" },
 177         [BLK_STS_DEV_RESOURCE]  = { -EBUSY,     "device resource" },
 178         [BLK_STS_AGAIN]         = { -EAGAIN,    "nonblocking retry" },
 179 
 180         /* device mapper special case, should not leak out: */
 181         [BLK_STS_DM_REQUEUE]    = { -EREMCHG, "dm internal retry" },
 182 
 183         /* everything else not covered above: */
 184         [BLK_STS_IOERR]         = { -EIO,       "I/O" },
 185 };
 186 
 187 blk_status_t errno_to_blk_status(int errno)
 188 {
 189         int i;
 190 
 191         for (i = 0; i < ARRAY_SIZE(blk_errors); i++) {
 192                 if (blk_errors[i].errno == errno)
 193                         return (__force blk_status_t)i;
 194         }
 195 
 196         return BLK_STS_IOERR;
 197 }
 198 EXPORT_SYMBOL_GPL(errno_to_blk_status);
 199 
 200 int blk_status_to_errno(blk_status_t status)
 201 {
 202         int idx = (__force int)status;
 203 
 204         if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
 205                 return -EIO;
 206         return blk_errors[idx].errno;
 207 }
 208 EXPORT_SYMBOL_GPL(blk_status_to_errno);
 209 
 210 static void print_req_error(struct request *req, blk_status_t status,
 211                 const char *caller)
 212 {
 213         int idx = (__force int)status;
 214 
 215         if (WARN_ON_ONCE(idx >= ARRAY_SIZE(blk_errors)))
 216                 return;
 217 
 218         printk_ratelimited(KERN_ERR
 219                 "%s: %s error, dev %s, sector %llu op 0x%x:(%s) flags 0x%x "
 220                 "phys_seg %u prio class %u\n",
 221                 caller, blk_errors[idx].name,
 222                 req->rq_disk ? req->rq_disk->disk_name : "?",
 223                 blk_rq_pos(req), req_op(req), blk_op_str(req_op(req)),
 224                 req->cmd_flags & ~REQ_OP_MASK,
 225                 req->nr_phys_segments,
 226                 IOPRIO_PRIO_CLASS(req->ioprio));
 227 }
 228 
 229 static void req_bio_endio(struct request *rq, struct bio *bio,
 230                           unsigned int nbytes, blk_status_t error)
 231 {
 232         if (error)
 233                 bio->bi_status = error;
 234 
 235         if (unlikely(rq->rq_flags & RQF_QUIET))
 236                 bio_set_flag(bio, BIO_QUIET);
 237 
 238         bio_advance(bio, nbytes);
 239 
 240         /* don't actually finish bio if it's part of flush sequence */
 241         if (bio->bi_iter.bi_size == 0 && !(rq->rq_flags & RQF_FLUSH_SEQ))
 242                 bio_endio(bio);
 243 }
 244 
 245 void blk_dump_rq_flags(struct request *rq, char *msg)
 246 {
 247         printk(KERN_INFO "%s: dev %s: flags=%llx\n", msg,
 248                 rq->rq_disk ? rq->rq_disk->disk_name : "?",
 249                 (unsigned long long) rq->cmd_flags);
 250 
 251         printk(KERN_INFO "  sector %llu, nr/cnr %u/%u\n",
 252                (unsigned long long)blk_rq_pos(rq),
 253                blk_rq_sectors(rq), blk_rq_cur_sectors(rq));
 254         printk(KERN_INFO "  bio %p, biotail %p, len %u\n",
 255                rq->bio, rq->biotail, blk_rq_bytes(rq));
 256 }
 257 EXPORT_SYMBOL(blk_dump_rq_flags);
 258 
 259 /**
 260  * blk_sync_queue - cancel any pending callbacks on a queue
 261  * @q: the queue
 262  *
 263  * Description:
 264  *     The block layer may perform asynchronous callback activity
 265  *     on a queue, such as calling the unplug function after a timeout.
 266  *     A block device may call blk_sync_queue to ensure that any
 267  *     such activity is cancelled, thus allowing it to release resources
 268  *     that the callbacks might use. The caller must already have made sure
 269  *     that its ->make_request_fn will not re-add plugging prior to calling
 270  *     this function.
 271  *
 272  *     This function does not cancel any asynchronous activity arising
 273  *     out of elevator or throttling code. That would require elevator_exit()
 274  *     and blkcg_exit_queue() to be called with queue lock initialized.
 275  *
 276  */
 277 void blk_sync_queue(struct request_queue *q)
 278 {
 279         del_timer_sync(&q->timeout);
 280         cancel_work_sync(&q->timeout_work);
 281 }
 282 EXPORT_SYMBOL(blk_sync_queue);
 283 
 284 /**
 285  * blk_set_pm_only - increment pm_only counter
 286  * @q: request queue pointer
 287  */
 288 void blk_set_pm_only(struct request_queue *q)
 289 {
 290         atomic_inc(&q->pm_only);
 291 }
 292 EXPORT_SYMBOL_GPL(blk_set_pm_only);
 293 
 294 void blk_clear_pm_only(struct request_queue *q)
 295 {
 296         int pm_only;
 297 
 298         pm_only = atomic_dec_return(&q->pm_only);
 299         WARN_ON_ONCE(pm_only < 0);
 300         if (pm_only == 0)
 301                 wake_up_all(&q->mq_freeze_wq);
 302 }
 303 EXPORT_SYMBOL_GPL(blk_clear_pm_only);
 304 
 305 void blk_put_queue(struct request_queue *q)
 306 {
 307         kobject_put(&q->kobj);
 308 }
 309 EXPORT_SYMBOL(blk_put_queue);
 310 
 311 void blk_set_queue_dying(struct request_queue *q)
 312 {
 313         blk_queue_flag_set(QUEUE_FLAG_DYING, q);
 314 
 315         /*
 316          * When queue DYING flag is set, we need to block new req
 317          * entering queue, so we call blk_freeze_queue_start() to
 318          * prevent I/O from crossing blk_queue_enter().
 319          */
 320         blk_freeze_queue_start(q);
 321 
 322         if (queue_is_mq(q))
 323                 blk_mq_wake_waiters(q);
 324 
 325         /* Make blk_queue_enter() reexamine the DYING flag. */
 326         wake_up_all(&q->mq_freeze_wq);
 327 }
 328 EXPORT_SYMBOL_GPL(blk_set_queue_dying);
 329 
 330 /**
 331  * blk_cleanup_queue - shutdown a request queue
 332  * @q: request queue to shutdown
 333  *
 334  * Mark @q DYING, drain all pending requests, mark @q DEAD, destroy and
 335  * put it.  All future requests will be failed immediately with -ENODEV.
 336  */
 337 void blk_cleanup_queue(struct request_queue *q)
 338 {
 339         /* mark @q DYING, no new request or merges will be allowed afterwards */
 340         mutex_lock(&q->sysfs_lock);
 341         blk_set_queue_dying(q);
 342 
 343         blk_queue_flag_set(QUEUE_FLAG_NOMERGES, q);
 344         blk_queue_flag_set(QUEUE_FLAG_NOXMERGES, q);
 345         blk_queue_flag_set(QUEUE_FLAG_DYING, q);
 346         mutex_unlock(&q->sysfs_lock);
 347 
 348         /*
 349          * Drain all requests queued before DYING marking. Set DEAD flag to
 350          * prevent that blk_mq_run_hw_queues() accesses the hardware queues
 351          * after draining finished.
 352          */
 353         blk_freeze_queue(q);
 354 
 355         rq_qos_exit(q);
 356 
 357         blk_queue_flag_set(QUEUE_FLAG_DEAD, q);
 358 
 359         /* for synchronous bio-based driver finish in-flight integrity i/o */
 360         blk_flush_integrity();
 361 
 362         /* @q won't process any more request, flush async actions */
 363         del_timer_sync(&q->backing_dev_info->laptop_mode_wb_timer);
 364         blk_sync_queue(q);
 365 
 366         if (queue_is_mq(q))
 367                 blk_mq_exit_queue(q);
 368 
 369         /*
 370          * In theory, request pool of sched_tags belongs to request queue.
 371          * However, the current implementation requires tag_set for freeing
 372          * requests, so free the pool now.
 373          *
 374          * Queue has become frozen, there can't be any in-queue requests, so
 375          * it is safe to free requests now.
 376          */
 377         mutex_lock(&q->sysfs_lock);
 378         if (q->elevator)
 379                 blk_mq_sched_free_requests(q);
 380         mutex_unlock(&q->sysfs_lock);
 381 
 382         percpu_ref_exit(&q->q_usage_counter);
 383 
 384         /* @q is and will stay empty, shutdown and put */
 385         blk_put_queue(q);
 386 }
 387 EXPORT_SYMBOL(blk_cleanup_queue);
 388 
 389 struct request_queue *blk_alloc_queue(gfp_t gfp_mask)
 390 {
 391         return blk_alloc_queue_node(gfp_mask, NUMA_NO_NODE);
 392 }
 393 EXPORT_SYMBOL(blk_alloc_queue);
 394 
 395 /**
 396  * blk_queue_enter() - try to increase q->q_usage_counter
 397  * @q: request queue pointer
 398  * @flags: BLK_MQ_REQ_NOWAIT and/or BLK_MQ_REQ_PREEMPT
 399  */
 400 int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags)
 401 {
 402         const bool pm = flags & BLK_MQ_REQ_PREEMPT;
 403 
 404         while (true) {
 405                 bool success = false;
 406 
 407                 rcu_read_lock();
 408                 if (percpu_ref_tryget_live(&q->q_usage_counter)) {
 409                         /*
 410                          * The code that increments the pm_only counter is
 411                          * responsible for ensuring that that counter is
 412                          * globally visible before the queue is unfrozen.
 413                          */
 414                         if (pm || !blk_queue_pm_only(q)) {
 415                                 success = true;
 416                         } else {
 417                                 percpu_ref_put(&q->q_usage_counter);
 418                         }
 419                 }
 420                 rcu_read_unlock();
 421 
 422                 if (success)
 423                         return 0;
 424 
 425                 if (flags & BLK_MQ_REQ_NOWAIT)
 426                         return -EBUSY;
 427 
 428                 /*
 429                  * read pair of barrier in blk_freeze_queue_start(),
 430                  * we need to order reading __PERCPU_REF_DEAD flag of
 431                  * .q_usage_counter and reading .mq_freeze_depth or
 432                  * queue dying flag, otherwise the following wait may
 433                  * never return if the two reads are reordered.
 434                  */
 435                 smp_rmb();
 436 
 437                 wait_event(q->mq_freeze_wq,
 438                            (!q->mq_freeze_depth &&
 439                             (pm || (blk_pm_request_resume(q),
 440                                     !blk_queue_pm_only(q)))) ||
 441                            blk_queue_dying(q));
 442                 if (blk_queue_dying(q))
 443                         return -ENODEV;
 444         }
 445 }
 446 
 447 void blk_queue_exit(struct request_queue *q)
 448 {
 449         percpu_ref_put(&q->q_usage_counter);
 450 }
 451 
 452 static void blk_queue_usage_counter_release(struct percpu_ref *ref)
 453 {
 454         struct request_queue *q =
 455                 container_of(ref, struct request_queue, q_usage_counter);
 456 
 457         wake_up_all(&q->mq_freeze_wq);
 458 }
 459 
 460 static void blk_rq_timed_out_timer(struct timer_list *t)
 461 {
 462         struct request_queue *q = from_timer(q, t, timeout);
 463 
 464         kblockd_schedule_work(&q->timeout_work);
 465 }
 466 
 467 static void blk_timeout_work(struct work_struct *work)
 468 {
 469 }
 470 
 471 /**
 472  * blk_alloc_queue_node - allocate a request queue
 473  * @gfp_mask: memory allocation flags
 474  * @node_id: NUMA node to allocate memory from
 475  */
 476 struct request_queue *blk_alloc_queue_node(gfp_t gfp_mask, int node_id)
 477 {
 478         struct request_queue *q;
 479         int ret;
 480 
 481         q = kmem_cache_alloc_node(blk_requestq_cachep,
 482                                 gfp_mask | __GFP_ZERO, node_id);
 483         if (!q)
 484                 return NULL;
 485 
 486         q->last_merge = NULL;
 487 
 488         q->id = ida_simple_get(&blk_queue_ida, 0, 0, gfp_mask);
 489         if (q->id < 0)
 490                 goto fail_q;
 491 
 492         ret = bioset_init(&q->bio_split, BIO_POOL_SIZE, 0, BIOSET_NEED_BVECS);
 493         if (ret)
 494                 goto fail_id;
 495 
 496         q->backing_dev_info = bdi_alloc_node(gfp_mask, node_id);
 497         if (!q->backing_dev_info)
 498                 goto fail_split;
 499 
 500         q->stats = blk_alloc_queue_stats();
 501         if (!q->stats)
 502                 goto fail_stats;
 503 
 504         q->backing_dev_info->ra_pages = VM_READAHEAD_PAGES;
 505         q->backing_dev_info->capabilities = BDI_CAP_CGROUP_WRITEBACK;
 506         q->backing_dev_info->name = "block";
 507         q->node = node_id;
 508 
 509         timer_setup(&q->backing_dev_info->laptop_mode_wb_timer,
 510                     laptop_mode_timer_fn, 0);
 511         timer_setup(&q->timeout, blk_rq_timed_out_timer, 0);
 512         INIT_WORK(&q->timeout_work, blk_timeout_work);
 513         INIT_LIST_HEAD(&q->icq_list);
 514 #ifdef CONFIG_BLK_CGROUP
 515         INIT_LIST_HEAD(&q->blkg_list);
 516 #endif
 517 
 518         kobject_init(&q->kobj, &blk_queue_ktype);
 519 
 520 #ifdef CONFIG_BLK_DEV_IO_TRACE
 521         mutex_init(&q->blk_trace_mutex);
 522 #endif
 523         mutex_init(&q->sysfs_lock);
 524         mutex_init(&q->sysfs_dir_lock);
 525         spin_lock_init(&q->queue_lock);
 526 
 527         init_waitqueue_head(&q->mq_freeze_wq);
 528         mutex_init(&q->mq_freeze_lock);
 529 
 530         /*
 531          * Init percpu_ref in atomic mode so that it's faster to shutdown.
 532          * See blk_register_queue() for details.
 533          */
 534         if (percpu_ref_init(&q->q_usage_counter,
 535                                 blk_queue_usage_counter_release,
 536                                 PERCPU_REF_INIT_ATOMIC, GFP_KERNEL))
 537                 goto fail_bdi;
 538 
 539         if (blkcg_init_queue(q))
 540                 goto fail_ref;
 541 
 542         return q;
 543 
 544 fail_ref:
 545         percpu_ref_exit(&q->q_usage_counter);
 546 fail_bdi:
 547         blk_free_queue_stats(q->stats);
 548 fail_stats:
 549         bdi_put(q->backing_dev_info);
 550 fail_split:
 551         bioset_exit(&q->bio_split);
 552 fail_id:
 553         ida_simple_remove(&blk_queue_ida, q->id);
 554 fail_q:
 555         kmem_cache_free(blk_requestq_cachep, q);
 556         return NULL;
 557 }
 558 EXPORT_SYMBOL(blk_alloc_queue_node);
 559 
 560 bool blk_get_queue(struct request_queue *q)
 561 {
 562         if (likely(!blk_queue_dying(q))) {
 563                 __blk_get_queue(q);
 564                 return true;
 565         }
 566 
 567         return false;
 568 }
 569 EXPORT_SYMBOL(blk_get_queue);
 570 
 571 /**
 572  * blk_get_request - allocate a request
 573  * @q: request queue to allocate a request for
 574  * @op: operation (REQ_OP_*) and REQ_* flags, e.g. REQ_SYNC.
 575  * @flags: BLK_MQ_REQ_* flags, e.g. BLK_MQ_REQ_NOWAIT.
 576  */
 577 struct request *blk_get_request(struct request_queue *q, unsigned int op,
 578                                 blk_mq_req_flags_t flags)
 579 {
 580         struct request *req;
 581 
 582         WARN_ON_ONCE(op & REQ_NOWAIT);
 583         WARN_ON_ONCE(flags & ~(BLK_MQ_REQ_NOWAIT | BLK_MQ_REQ_PREEMPT));
 584 
 585         req = blk_mq_alloc_request(q, op, flags);
 586         if (!IS_ERR(req) && q->mq_ops->initialize_rq_fn)
 587                 q->mq_ops->initialize_rq_fn(req);
 588 
 589         return req;
 590 }
 591 EXPORT_SYMBOL(blk_get_request);
 592 
 593 void blk_put_request(struct request *req)
 594 {
 595         blk_mq_free_request(req);
 596 }
 597 EXPORT_SYMBOL(blk_put_request);
 598 
 599 bool bio_attempt_back_merge(struct request *req, struct bio *bio,
 600                 unsigned int nr_segs)
 601 {
 602         const int ff = bio->bi_opf & REQ_FAILFAST_MASK;
 603 
 604         if (!ll_back_merge_fn(req, bio, nr_segs))
 605                 return false;
 606 
 607         trace_block_bio_backmerge(req->q, req, bio);
 608         rq_qos_merge(req->q, req, bio);
 609 
 610         if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
 611                 blk_rq_set_mixed_merge(req);
 612 
 613         req->biotail->bi_next = bio;
 614         req->biotail = bio;
 615         req->__data_len += bio->bi_iter.bi_size;
 616 
 617         blk_account_io_start(req, false);
 618         return true;
 619 }
 620 
 621 bool bio_attempt_front_merge(struct request *req, struct bio *bio,
 622                 unsigned int nr_segs)
 623 {
 624         const int ff = bio->bi_opf & REQ_FAILFAST_MASK;
 625 
 626         if (!ll_front_merge_fn(req, bio, nr_segs))
 627                 return false;
 628 
 629         trace_block_bio_frontmerge(req->q, req, bio);
 630         rq_qos_merge(req->q, req, bio);
 631 
 632         if ((req->cmd_flags & REQ_FAILFAST_MASK) != ff)
 633                 blk_rq_set_mixed_merge(req);
 634 
 635         bio->bi_next = req->bio;
 636         req->bio = bio;
 637 
 638         req->__sector = bio->bi_iter.bi_sector;
 639         req->__data_len += bio->bi_iter.bi_size;
 640 
 641         blk_account_io_start(req, false);
 642         return true;
 643 }
 644 
 645 bool bio_attempt_discard_merge(struct request_queue *q, struct request *req,
 646                 struct bio *bio)
 647 {
 648         unsigned short segments = blk_rq_nr_discard_segments(req);
 649 
 650         if (segments >= queue_max_discard_segments(q))
 651                 goto no_merge;
 652         if (blk_rq_sectors(req) + bio_sectors(bio) >
 653             blk_rq_get_max_sectors(req, blk_rq_pos(req)))
 654                 goto no_merge;
 655 
 656         rq_qos_merge(q, req, bio);
 657 
 658         req->biotail->bi_next = bio;
 659         req->biotail = bio;
 660         req->__data_len += bio->bi_iter.bi_size;
 661         req->nr_phys_segments = segments + 1;
 662 
 663         blk_account_io_start(req, false);
 664         return true;
 665 no_merge:
 666         req_set_nomerge(q, req);
 667         return false;
 668 }
 669 
 670 /**
 671  * blk_attempt_plug_merge - try to merge with %current's plugged list
 672  * @q: request_queue new bio is being queued at
 673  * @bio: new bio being queued
 674  * @nr_segs: number of segments in @bio
 675  * @same_queue_rq: pointer to &struct request that gets filled in when
 676  * another request associated with @q is found on the plug list
 677  * (optional, may be %NULL)
 678  *
 679  * Determine whether @bio being queued on @q can be merged with a request
 680  * on %current's plugged list.  Returns %true if merge was successful,
 681  * otherwise %false.
 682  *
 683  * Plugging coalesces IOs from the same issuer for the same purpose without
 684  * going through @q->queue_lock.  As such it's more of an issuing mechanism
 685  * than scheduling, and the request, while may have elvpriv data, is not
 686  * added on the elevator at this point.  In addition, we don't have
 687  * reliable access to the elevator outside queue lock.  Only check basic
 688  * merging parameters without querying the elevator.
 689  *
 690  * Caller must ensure !blk_queue_nomerges(q) beforehand.
 691  */
 692 bool blk_attempt_plug_merge(struct request_queue *q, struct bio *bio,
 693                 unsigned int nr_segs, struct request **same_queue_rq)
 694 {
 695         struct blk_plug *plug;
 696         struct request *rq;
 697         struct list_head *plug_list;
 698 
 699         plug = blk_mq_plug(q, bio);
 700         if (!plug)
 701                 return false;
 702 
 703         plug_list = &plug->mq_list;
 704 
 705         list_for_each_entry_reverse(rq, plug_list, queuelist) {
 706                 bool merged = false;
 707 
 708                 if (rq->q == q && same_queue_rq) {
 709                         /*
 710                          * Only blk-mq multiple hardware queues case checks the
 711                          * rq in the same queue, there should be only one such
 712                          * rq in a queue
 713                          **/
 714                         *same_queue_rq = rq;
 715                 }
 716 
 717                 if (rq->q != q || !blk_rq_merge_ok(rq, bio))
 718                         continue;
 719 
 720                 switch (blk_try_merge(rq, bio)) {
 721                 case ELEVATOR_BACK_MERGE:
 722                         merged = bio_attempt_back_merge(rq, bio, nr_segs);
 723                         break;
 724                 case ELEVATOR_FRONT_MERGE:
 725                         merged = bio_attempt_front_merge(rq, bio, nr_segs);
 726                         break;
 727                 case ELEVATOR_DISCARD_MERGE:
 728                         merged = bio_attempt_discard_merge(q, rq, bio);
 729                         break;
 730                 default:
 731                         break;
 732                 }
 733 
 734                 if (merged)
 735                         return true;
 736         }
 737 
 738         return false;
 739 }
 740 
 741 static void handle_bad_sector(struct bio *bio, sector_t maxsector)
 742 {
 743         char b[BDEVNAME_SIZE];
 744 
 745         printk(KERN_INFO "attempt to access beyond end of device\n");
 746         printk(KERN_INFO "%s: rw=%d, want=%Lu, limit=%Lu\n",
 747                         bio_devname(bio, b), bio->bi_opf,
 748                         (unsigned long long)bio_end_sector(bio),
 749                         (long long)maxsector);
 750 }
 751 
 752 #ifdef CONFIG_FAIL_MAKE_REQUEST
 753 
 754 static DECLARE_FAULT_ATTR(fail_make_request);
 755 
 756 static int __init setup_fail_make_request(char *str)
 757 {
 758         return setup_fault_attr(&fail_make_request, str);
 759 }
 760 __setup("fail_make_request=", setup_fail_make_request);
 761 
 762 static bool should_fail_request(struct hd_struct *part, unsigned int bytes)
 763 {
 764         return part->make_it_fail && should_fail(&fail_make_request, bytes);
 765 }
 766 
 767 static int __init fail_make_request_debugfs(void)
 768 {
 769         struct dentry *dir = fault_create_debugfs_attr("fail_make_request",
 770                                                 NULL, &fail_make_request);
 771 
 772         return PTR_ERR_OR_ZERO(dir);
 773 }
 774 
 775 late_initcall(fail_make_request_debugfs);
 776 
 777 #else /* CONFIG_FAIL_MAKE_REQUEST */
 778 
 779 static inline bool should_fail_request(struct hd_struct *part,
 780                                         unsigned int bytes)
 781 {
 782         return false;
 783 }
 784 
 785 #endif /* CONFIG_FAIL_MAKE_REQUEST */
 786 
 787 static inline bool bio_check_ro(struct bio *bio, struct hd_struct *part)
 788 {
 789         const int op = bio_op(bio);
 790 
 791         if (part->policy && op_is_write(op)) {
 792                 char b[BDEVNAME_SIZE];
 793 
 794                 if (op_is_flush(bio->bi_opf) && !bio_sectors(bio))
 795                         return false;
 796 
 797                 WARN_ONCE(1,
 798                        "generic_make_request: Trying to write "
 799                         "to read-only block-device %s (partno %d)\n",
 800                         bio_devname(bio, b), part->partno);
 801                 /* Older lvm-tools actually trigger this */
 802                 return false;
 803         }
 804 
 805         return false;
 806 }
 807 
 808 static noinline int should_fail_bio(struct bio *bio)
 809 {
 810         if (should_fail_request(&bio->bi_disk->part0, bio->bi_iter.bi_size))
 811                 return -EIO;
 812         return 0;
 813 }
 814 ALLOW_ERROR_INJECTION(should_fail_bio, ERRNO);
 815 
 816 /*
 817  * Check whether this bio extends beyond the end of the device or partition.
 818  * This may well happen - the kernel calls bread() without checking the size of
 819  * the device, e.g., when mounting a file system.
 820  */
 821 static inline int bio_check_eod(struct bio *bio, sector_t maxsector)
 822 {
 823         unsigned int nr_sectors = bio_sectors(bio);
 824 
 825         if (nr_sectors && maxsector &&
 826             (nr_sectors > maxsector ||
 827              bio->bi_iter.bi_sector > maxsector - nr_sectors)) {
 828                 handle_bad_sector(bio, maxsector);
 829                 return -EIO;
 830         }
 831         return 0;
 832 }
 833 
 834 /*
 835  * Remap block n of partition p to block n+start(p) of the disk.
 836  */
 837 static inline int blk_partition_remap(struct bio *bio)
 838 {
 839         struct hd_struct *p;
 840         int ret = -EIO;
 841 
 842         rcu_read_lock();
 843         p = __disk_get_part(bio->bi_disk, bio->bi_partno);
 844         if (unlikely(!p))
 845                 goto out;
 846         if (unlikely(should_fail_request(p, bio->bi_iter.bi_size)))
 847                 goto out;
 848         if (unlikely(bio_check_ro(bio, p)))
 849                 goto out;
 850 
 851         /*
 852          * Zone reset does not include bi_size so bio_sectors() is always 0.
 853          * Include a test for the reset op code and perform the remap if needed.
 854          */
 855         if (bio_sectors(bio) || bio_op(bio) == REQ_OP_ZONE_RESET) {
 856                 if (bio_check_eod(bio, part_nr_sects_read(p)))
 857                         goto out;
 858                 bio->bi_iter.bi_sector += p->start_sect;
 859                 trace_block_bio_remap(bio->bi_disk->queue, bio, part_devt(p),
 860                                       bio->bi_iter.bi_sector - p->start_sect);
 861         }
 862         bio->bi_partno = 0;
 863         ret = 0;
 864 out:
 865         rcu_read_unlock();
 866         return ret;
 867 }
 868 
 869 static noinline_for_stack bool
 870 generic_make_request_checks(struct bio *bio)
 871 {
 872         struct request_queue *q;
 873         int nr_sectors = bio_sectors(bio);
 874         blk_status_t status = BLK_STS_IOERR;
 875         char b[BDEVNAME_SIZE];
 876 
 877         might_sleep();
 878 
 879         q = bio->bi_disk->queue;
 880         if (unlikely(!q)) {
 881                 printk(KERN_ERR
 882                        "generic_make_request: Trying to access "
 883                         "nonexistent block-device %s (%Lu)\n",
 884                         bio_devname(bio, b), (long long)bio->bi_iter.bi_sector);
 885                 goto end_io;
 886         }
 887 
 888         /*
 889          * For a REQ_NOWAIT based request, return -EOPNOTSUPP
 890          * if queue is not a request based queue.
 891          */
 892         if ((bio->bi_opf & REQ_NOWAIT) && !queue_is_mq(q))
 893                 goto not_supported;
 894 
 895         if (should_fail_bio(bio))
 896                 goto end_io;
 897 
 898         if (bio->bi_partno) {
 899                 if (unlikely(blk_partition_remap(bio)))
 900                         goto end_io;
 901         } else {
 902                 if (unlikely(bio_check_ro(bio, &bio->bi_disk->part0)))
 903                         goto end_io;
 904                 if (unlikely(bio_check_eod(bio, get_capacity(bio->bi_disk))))
 905                         goto end_io;
 906         }
 907 
 908         /*
 909          * Filter flush bio's early so that make_request based
 910          * drivers without flush support don't have to worry
 911          * about them.
 912          */
 913         if (op_is_flush(bio->bi_opf) &&
 914             !test_bit(QUEUE_FLAG_WC, &q->queue_flags)) {
 915                 bio->bi_opf &= ~(REQ_PREFLUSH | REQ_FUA);
 916                 if (!nr_sectors) {
 917                         status = BLK_STS_OK;
 918                         goto end_io;
 919                 }
 920         }
 921 
 922         if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
 923                 bio->bi_opf &= ~REQ_HIPRI;
 924 
 925         switch (bio_op(bio)) {
 926         case REQ_OP_DISCARD:
 927                 if (!blk_queue_discard(q))
 928                         goto not_supported;
 929                 break;
 930         case REQ_OP_SECURE_ERASE:
 931                 if (!blk_queue_secure_erase(q))
 932                         goto not_supported;
 933                 break;
 934         case REQ_OP_WRITE_SAME:
 935                 if (!q->limits.max_write_same_sectors)
 936                         goto not_supported;
 937                 break;
 938         case REQ_OP_ZONE_RESET:
 939                 if (!blk_queue_is_zoned(q))
 940                         goto not_supported;
 941                 break;
 942         case REQ_OP_ZONE_RESET_ALL:
 943                 if (!blk_queue_is_zoned(q) || !blk_queue_zone_resetall(q))
 944                         goto not_supported;
 945                 break;
 946         case REQ_OP_WRITE_ZEROES:
 947                 if (!q->limits.max_write_zeroes_sectors)
 948                         goto not_supported;
 949                 break;
 950         default:
 951                 break;
 952         }
 953 
 954         /*
 955          * Various block parts want %current->io_context and lazy ioc
 956          * allocation ends up trading a lot of pain for a small amount of
 957          * memory.  Just allocate it upfront.  This may fail and block
 958          * layer knows how to live with it.
 959          */
 960         create_io_context(GFP_ATOMIC, q->node);
 961 
 962         if (!blkcg_bio_issue_check(q, bio))
 963                 return false;
 964 
 965         if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) {
 966                 trace_block_bio_queue(q, bio);
 967                 /* Now that enqueuing has been traced, we need to trace
 968                  * completion as well.
 969                  */
 970                 bio_set_flag(bio, BIO_TRACE_COMPLETION);
 971         }
 972         return true;
 973 
 974 not_supported:
 975         status = BLK_STS_NOTSUPP;
 976 end_io:
 977         bio->bi_status = status;
 978         bio_endio(bio);
 979         return false;
 980 }
 981 
 982 /**
 983  * generic_make_request - hand a buffer to its device driver for I/O
 984  * @bio:  The bio describing the location in memory and on the device.
 985  *
 986  * generic_make_request() is used to make I/O requests of block
 987  * devices. It is passed a &struct bio, which describes the I/O that needs
 988  * to be done.
 989  *
 990  * generic_make_request() does not return any status.  The
 991  * success/failure status of the request, along with notification of
 992  * completion, is delivered asynchronously through the bio->bi_end_io
 993  * function described (one day) else where.
 994  *
 995  * The caller of generic_make_request must make sure that bi_io_vec
 996  * are set to describe the memory buffer, and that bi_dev and bi_sector are
 997  * set to describe the device address, and the
 998  * bi_end_io and optionally bi_private are set to describe how
 999  * completion notification should be signaled.
1000  *
1001  * generic_make_request and the drivers it calls may use bi_next if this
1002  * bio happens to be merged with someone else, and may resubmit the bio to
1003  * a lower device by calling into generic_make_request recursively, which
1004  * means the bio should NOT be touched after the call to ->make_request_fn.
1005  */
1006 blk_qc_t generic_make_request(struct bio *bio)
1007 {
1008         /*
1009          * bio_list_on_stack[0] contains bios submitted by the current
1010          * make_request_fn.
1011          * bio_list_on_stack[1] contains bios that were submitted before
1012          * the current make_request_fn, but that haven't been processed
1013          * yet.
1014          */
1015         struct bio_list bio_list_on_stack[2];
1016         blk_qc_t ret = BLK_QC_T_NONE;
1017 
1018         if (!generic_make_request_checks(bio))
1019                 goto out;
1020 
1021         /*
1022          * We only want one ->make_request_fn to be active at a time, else
1023          * stack usage with stacked devices could be a problem.  So use
1024          * current->bio_list to keep a list of requests submited by a
1025          * make_request_fn function.  current->bio_list is also used as a
1026          * flag to say if generic_make_request is currently active in this
1027          * task or not.  If it is NULL, then no make_request is active.  If
1028          * it is non-NULL, then a make_request is active, and new requests
1029          * should be added at the tail
1030          */
1031         if (current->bio_list) {
1032                 bio_list_add(&current->bio_list[0], bio);
1033                 goto out;
1034         }
1035 
1036         /* following loop may be a bit non-obvious, and so deserves some
1037          * explanation.
1038          * Before entering the loop, bio->bi_next is NULL (as all callers
1039          * ensure that) so we have a list with a single bio.
1040          * We pretend that we have just taken it off a longer list, so
1041          * we assign bio_list to a pointer to the bio_list_on_stack,
1042          * thus initialising the bio_list of new bios to be
1043          * added.  ->make_request() may indeed add some more bios
1044          * through a recursive call to generic_make_request.  If it
1045          * did, we find a non-NULL value in bio_list and re-enter the loop
1046          * from the top.  In this case we really did just take the bio
1047          * of the top of the list (no pretending) and so remove it from
1048          * bio_list, and call into ->make_request() again.
1049          */
1050         BUG_ON(bio->bi_next);
1051         bio_list_init(&bio_list_on_stack[0]);
1052         current->bio_list = bio_list_on_stack;
1053         do {
1054                 struct request_queue *q = bio->bi_disk->queue;
1055                 blk_mq_req_flags_t flags = bio->bi_opf & REQ_NOWAIT ?
1056                         BLK_MQ_REQ_NOWAIT : 0;
1057 
1058                 if (likely(blk_queue_enter(q, flags) == 0)) {
1059                         struct bio_list lower, same;
1060 
1061                         /* Create a fresh bio_list for all subordinate requests */
1062                         bio_list_on_stack[1] = bio_list_on_stack[0];
1063                         bio_list_init(&bio_list_on_stack[0]);
1064                         ret = q->make_request_fn(q, bio);
1065 
1066                         blk_queue_exit(q);
1067 
1068                         /* sort new bios into those for a lower level
1069                          * and those for the same level
1070                          */
1071                         bio_list_init(&lower);
1072                         bio_list_init(&same);
1073                         while ((bio = bio_list_pop(&bio_list_on_stack[0])) != NULL)
1074                                 if (q == bio->bi_disk->queue)
1075                                         bio_list_add(&same, bio);
1076                                 else
1077                                         bio_list_add(&lower, bio);
1078                         /* now assemble so we handle the lowest level first */
1079                         bio_list_merge(&bio_list_on_stack[0], &lower);
1080                         bio_list_merge(&bio_list_on_stack[0], &same);
1081                         bio_list_merge(&bio_list_on_stack[0], &bio_list_on_stack[1]);
1082                 } else {
1083                         if (unlikely(!blk_queue_dying(q) &&
1084                                         (bio->bi_opf & REQ_NOWAIT)))
1085                                 bio_wouldblock_error(bio);
1086                         else
1087                                 bio_io_error(bio);
1088                 }
1089                 bio = bio_list_pop(&bio_list_on_stack[0]);
1090         } while (bio);
1091         current->bio_list = NULL; /* deactivate */
1092 
1093 out:
1094         return ret;
1095 }
1096 EXPORT_SYMBOL(generic_make_request);
1097 
1098 /**
1099  * direct_make_request - hand a buffer directly to its device driver for I/O
1100  * @bio:  The bio describing the location in memory and on the device.
1101  *
1102  * This function behaves like generic_make_request(), but does not protect
1103  * against recursion.  Must only be used if the called driver is known
1104  * to not call generic_make_request (or direct_make_request) again from
1105  * its make_request function.  (Calling direct_make_request again from
1106  * a workqueue is perfectly fine as that doesn't recurse).
1107  */
1108 blk_qc_t direct_make_request(struct bio *bio)
1109 {
1110         struct request_queue *q = bio->bi_disk->queue;
1111         bool nowait = bio->bi_opf & REQ_NOWAIT;
1112         blk_qc_t ret;
1113 
1114         if (!generic_make_request_checks(bio))
1115                 return BLK_QC_T_NONE;
1116 
1117         if (unlikely(blk_queue_enter(q, nowait ? BLK_MQ_REQ_NOWAIT : 0))) {
1118                 if (nowait && !blk_queue_dying(q))
1119                         bio->bi_status = BLK_STS_AGAIN;
1120                 else
1121                         bio->bi_status = BLK_STS_IOERR;
1122                 bio_endio(bio);
1123                 return BLK_QC_T_NONE;
1124         }
1125 
1126         ret = q->make_request_fn(q, bio);
1127         blk_queue_exit(q);
1128         return ret;
1129 }
1130 EXPORT_SYMBOL_GPL(direct_make_request);
1131 
1132 /**
1133  * submit_bio - submit a bio to the block device layer for I/O
1134  * @bio: The &struct bio which describes the I/O
1135  *
1136  * submit_bio() is very similar in purpose to generic_make_request(), and
1137  * uses that function to do most of the work. Both are fairly rough
1138  * interfaces; @bio must be presetup and ready for I/O.
1139  *
1140  */
1141 blk_qc_t submit_bio(struct bio *bio)
1142 {
1143         bool workingset_read = false;
1144         unsigned long pflags;
1145         blk_qc_t ret;
1146 
1147         if (blkcg_punt_bio_submit(bio))
1148                 return BLK_QC_T_NONE;
1149 
1150         /*
1151          * If it's a regular read/write or a barrier with data attached,
1152          * go through the normal accounting stuff before submission.
1153          */
1154         if (bio_has_data(bio)) {
1155                 unsigned int count;
1156 
1157                 if (unlikely(bio_op(bio) == REQ_OP_WRITE_SAME))
1158                         count = queue_logical_block_size(bio->bi_disk->queue) >> 9;
1159                 else
1160                         count = bio_sectors(bio);
1161 
1162                 if (op_is_write(bio_op(bio))) {
1163                         count_vm_events(PGPGOUT, count);
1164                 } else {
1165                         if (bio_flagged(bio, BIO_WORKINGSET))
1166                                 workingset_read = true;
1167                         task_io_account_read(bio->bi_iter.bi_size);
1168                         count_vm_events(PGPGIN, count);
1169                 }
1170 
1171                 if (unlikely(block_dump)) {
1172                         char b[BDEVNAME_SIZE];
1173                         printk(KERN_DEBUG "%s(%d): %s block %Lu on %s (%u sectors)\n",
1174                         current->comm, task_pid_nr(current),
1175                                 op_is_write(bio_op(bio)) ? "WRITE" : "READ",
1176                                 (unsigned long long)bio->bi_iter.bi_sector,
1177                                 bio_devname(bio, b), count);
1178                 }
1179         }
1180 
1181         /*
1182          * If we're reading data that is part of the userspace
1183          * workingset, count submission time as memory stall. When the
1184          * device is congested, or the submitting cgroup IO-throttled,
1185          * submission can be a significant part of overall IO time.
1186          */
1187         if (workingset_read)
1188                 psi_memstall_enter(&pflags);
1189 
1190         ret = generic_make_request(bio);
1191 
1192         if (workingset_read)
1193                 psi_memstall_leave(&pflags);
1194 
1195         return ret;
1196 }
1197 EXPORT_SYMBOL(submit_bio);
1198 
1199 /**
1200  * blk_cloned_rq_check_limits - Helper function to check a cloned request
1201  *                              for new the queue limits
1202  * @q:  the queue
1203  * @rq: the request being checked
1204  *
1205  * Description:
1206  *    @rq may have been made based on weaker limitations of upper-level queues
1207  *    in request stacking drivers, and it may violate the limitation of @q.
1208  *    Since the block layer and the underlying device driver trust @rq
1209  *    after it is inserted to @q, it should be checked against @q before
1210  *    the insertion using this generic function.
1211  *
1212  *    Request stacking drivers like request-based dm may change the queue
1213  *    limits when retrying requests on other queues. Those requests need
1214  *    to be checked against the new queue limits again during dispatch.
1215  */
1216 static int blk_cloned_rq_check_limits(struct request_queue *q,
1217                                       struct request *rq)
1218 {
1219         if (blk_rq_sectors(rq) > blk_queue_get_max_sectors(q, req_op(rq))) {
1220                 printk(KERN_ERR "%s: over max size limit. (%u > %u)\n",
1221                         __func__, blk_rq_sectors(rq),
1222                         blk_queue_get_max_sectors(q, req_op(rq)));
1223                 return -EIO;
1224         }
1225 
1226         /*
1227          * queue's settings related to segment counting like q->bounce_pfn
1228          * may differ from that of other stacking queues.
1229          * Recalculate it to check the request correctly on this queue's
1230          * limitation.
1231          */
1232         rq->nr_phys_segments = blk_recalc_rq_segments(rq);
1233         if (rq->nr_phys_segments > queue_max_segments(q)) {
1234                 printk(KERN_ERR "%s: over max segments limit. (%hu > %hu)\n",
1235                         __func__, rq->nr_phys_segments, queue_max_segments(q));
1236                 return -EIO;
1237         }
1238 
1239         return 0;
1240 }
1241 
1242 /**
1243  * blk_insert_cloned_request - Helper for stacking drivers to submit a request
1244  * @q:  the queue to submit the request
1245  * @rq: the request being queued
1246  */
1247 blk_status_t blk_insert_cloned_request(struct request_queue *q, struct request *rq)
1248 {
1249         if (blk_cloned_rq_check_limits(q, rq))
1250                 return BLK_STS_IOERR;
1251 
1252         if (rq->rq_disk &&
1253             should_fail_request(&rq->rq_disk->part0, blk_rq_bytes(rq)))
1254                 return BLK_STS_IOERR;
1255 
1256         if (blk_queue_io_stat(q))
1257                 blk_account_io_start(rq, true);
1258 
1259         /*
1260          * Since we have a scheduler attached on the top device,
1261          * bypass a potential scheduler on the bottom device for
1262          * insert.
1263          */
1264         return blk_mq_request_issue_directly(rq, true);
1265 }
1266 EXPORT_SYMBOL_GPL(blk_insert_cloned_request);
1267 
1268 /**
1269  * blk_rq_err_bytes - determine number of bytes till the next failure boundary
1270  * @rq: request to examine
1271  *
1272  * Description:
1273  *     A request could be merge of IOs which require different failure
1274  *     handling.  This function determines the number of bytes which
1275  *     can be failed from the beginning of the request without
1276  *     crossing into area which need to be retried further.
1277  *
1278  * Return:
1279  *     The number of bytes to fail.
1280  */
1281 unsigned int blk_rq_err_bytes(const struct request *rq)
1282 {
1283         unsigned int ff = rq->cmd_flags & REQ_FAILFAST_MASK;
1284         unsigned int bytes = 0;
1285         struct bio *bio;
1286 
1287         if (!(rq->rq_flags & RQF_MIXED_MERGE))
1288                 return blk_rq_bytes(rq);
1289 
1290         /*
1291          * Currently the only 'mixing' which can happen is between
1292          * different fastfail types.  We can safely fail portions
1293          * which have all the failfast bits that the first one has -
1294          * the ones which are at least as eager to fail as the first
1295          * one.
1296          */
1297         for (bio = rq->bio; bio; bio = bio->bi_next) {
1298                 if ((bio->bi_opf & ff) != ff)
1299                         break;
1300                 bytes += bio->bi_iter.bi_size;
1301         }
1302 
1303         /* this could lead to infinite loop */
1304         BUG_ON(blk_rq_bytes(rq) && !bytes);
1305         return bytes;
1306 }
1307 EXPORT_SYMBOL_GPL(blk_rq_err_bytes);
1308 
1309 void blk_account_io_completion(struct request *req, unsigned int bytes)
1310 {
1311         if (blk_do_io_stat(req)) {
1312                 const int sgrp = op_stat_group(req_op(req));
1313                 struct hd_struct *part;
1314 
1315                 part_stat_lock();
1316                 part = req->part;
1317                 part_stat_add(part, sectors[sgrp], bytes >> 9);
1318                 part_stat_unlock();
1319         }
1320 }
1321 
1322 void blk_account_io_done(struct request *req, u64 now)
1323 {
1324         /*
1325          * Account IO completion.  flush_rq isn't accounted as a
1326          * normal IO on queueing nor completion.  Accounting the
1327          * containing request is enough.
1328          */
1329         if (blk_do_io_stat(req) && !(req->rq_flags & RQF_FLUSH_SEQ)) {
1330                 const int sgrp = op_stat_group(req_op(req));
1331                 struct hd_struct *part;
1332 
1333                 part_stat_lock();
1334                 part = req->part;
1335 
1336                 update_io_ticks(part, jiffies);
1337                 part_stat_inc(part, ios[sgrp]);
1338                 part_stat_add(part, nsecs[sgrp], now - req->start_time_ns);
1339                 part_stat_add(part, time_in_queue, nsecs_to_jiffies64(now - req->start_time_ns));
1340                 part_dec_in_flight(req->q, part, rq_data_dir(req));
1341 
1342                 hd_struct_put(part);
1343                 part_stat_unlock();
1344         }
1345 }
1346 
1347 void blk_account_io_start(struct request *rq, bool new_io)
1348 {
1349         struct hd_struct *part;
1350         int rw = rq_data_dir(rq);
1351 
1352         if (!blk_do_io_stat(rq))
1353                 return;
1354 
1355         part_stat_lock();
1356 
1357         if (!new_io) {
1358                 part = rq->part;
1359                 part_stat_inc(part, merges[rw]);
1360         } else {
1361                 part = disk_map_sector_rcu(rq->rq_disk, blk_rq_pos(rq));
1362                 if (!hd_struct_try_get(part)) {
1363                         /*
1364                          * The partition is already being removed,
1365                          * the request will be accounted on the disk only
1366                          *
1367                          * We take a reference on disk->part0 although that
1368                          * partition will never be deleted, so we can treat
1369                          * it as any other partition.
1370                          */
1371                         part = &rq->rq_disk->part0;
1372                         hd_struct_get(part);
1373                 }
1374                 part_inc_in_flight(rq->q, part, rw);
1375                 rq->part = part;
1376         }
1377 
1378         update_io_ticks(part, jiffies);
1379 
1380         part_stat_unlock();
1381 }
1382 
1383 /*
1384  * Steal bios from a request and add them to a bio list.
1385  * The request must not have been partially completed before.
1386  */
1387 void blk_steal_bios(struct bio_list *list, struct request *rq)
1388 {
1389         if (rq->bio) {
1390                 if (list->tail)
1391                         list->tail->bi_next = rq->bio;
1392                 else
1393                         list->head = rq->bio;
1394                 list->tail = rq->biotail;
1395 
1396                 rq->bio = NULL;
1397                 rq->biotail = NULL;
1398         }
1399 
1400         rq->__data_len = 0;
1401 }
1402 EXPORT_SYMBOL_GPL(blk_steal_bios);
1403 
1404 /**
1405  * blk_update_request - Special helper function for request stacking drivers
1406  * @req:      the request being processed
1407  * @error:    block status code
1408  * @nr_bytes: number of bytes to complete @req
1409  *
1410  * Description:
1411  *     Ends I/O on a number of bytes attached to @req, but doesn't complete
1412  *     the request structure even if @req doesn't have leftover.
1413  *     If @req has leftover, sets it up for the next range of segments.
1414  *
1415  *     This special helper function is only for request stacking drivers
1416  *     (e.g. request-based dm) so that they can handle partial completion.
1417  *     Actual device drivers should use blk_mq_end_request instead.
1418  *
1419  *     Passing the result of blk_rq_bytes() as @nr_bytes guarantees
1420  *     %false return from this function.
1421  *
1422  * Note:
1423  *      The RQF_SPECIAL_PAYLOAD flag is ignored on purpose in both
1424  *      blk_rq_bytes() and in blk_update_request().
1425  *
1426  * Return:
1427  *     %false - this request doesn't have any more data
1428  *     %true  - this request has more data
1429  **/
1430 bool blk_update_request(struct request *req, blk_status_t error,
1431                 unsigned int nr_bytes)
1432 {
1433         int total_bytes;
1434 
1435         trace_block_rq_complete(req, blk_status_to_errno(error), nr_bytes);
1436 
1437         if (!req->bio)
1438                 return false;
1439 
1440 #ifdef CONFIG_BLK_DEV_INTEGRITY
1441         if (blk_integrity_rq(req) && req_op(req) == REQ_OP_READ &&
1442             error == BLK_STS_OK)
1443                 req->q->integrity.profile->complete_fn(req, nr_bytes);
1444 #endif
1445 
1446         if (unlikely(error && !blk_rq_is_passthrough(req) &&
1447                      !(req->rq_flags & RQF_QUIET)))
1448                 print_req_error(req, error, __func__);
1449 
1450         blk_account_io_completion(req, nr_bytes);
1451 
1452         total_bytes = 0;
1453         while (req->bio) {
1454                 struct bio *bio = req->bio;
1455                 unsigned bio_bytes = min(bio->bi_iter.bi_size, nr_bytes);
1456 
1457                 if (bio_bytes == bio->bi_iter.bi_size)
1458                         req->bio = bio->bi_next;
1459 
1460                 /* Completion has already been traced */
1461                 bio_clear_flag(bio, BIO_TRACE_COMPLETION);
1462                 req_bio_endio(req, bio, bio_bytes, error);
1463 
1464                 total_bytes += bio_bytes;
1465                 nr_bytes -= bio_bytes;
1466 
1467                 if (!nr_bytes)
1468                         break;
1469         }
1470 
1471         /*
1472          * completely done
1473          */
1474         if (!req->bio) {
1475                 /*
1476                  * Reset counters so that the request stacking driver
1477                  * can find how many bytes remain in the request
1478                  * later.
1479                  */
1480                 req->__data_len = 0;
1481                 return false;
1482         }
1483 
1484         req->__data_len -= total_bytes;
1485 
1486         /* update sector only for requests with clear definition of sector */
1487         if (!blk_rq_is_passthrough(req))
1488                 req->__sector += total_bytes >> 9;
1489 
1490         /* mixed attributes always follow the first bio */
1491         if (req->rq_flags & RQF_MIXED_MERGE) {
1492                 req->cmd_flags &= ~REQ_FAILFAST_MASK;
1493                 req->cmd_flags |= req->bio->bi_opf & REQ_FAILFAST_MASK;
1494         }
1495 
1496         if (!(req->rq_flags & RQF_SPECIAL_PAYLOAD)) {
1497                 /*
1498                  * If total number of sectors is less than the first segment
1499                  * size, something has gone terribly wrong.
1500                  */
1501                 if (blk_rq_bytes(req) < blk_rq_cur_bytes(req)) {
1502                         blk_dump_rq_flags(req, "request botched");
1503                         req->__data_len = blk_rq_cur_bytes(req);
1504                 }
1505 
1506                 /* recalculate the number of segments */
1507                 req->nr_phys_segments = blk_recalc_rq_segments(req);
1508         }
1509 
1510         return true;
1511 }
1512 EXPORT_SYMBOL_GPL(blk_update_request);
1513 
1514 #if ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE
1515 /**
1516  * rq_flush_dcache_pages - Helper function to flush all pages in a request
1517  * @rq: the request to be flushed
1518  *
1519  * Description:
1520  *     Flush all pages in @rq.
1521  */
1522 void rq_flush_dcache_pages(struct request *rq)
1523 {
1524         struct req_iterator iter;
1525         struct bio_vec bvec;
1526 
1527         rq_for_each_segment(bvec, rq, iter)
1528                 flush_dcache_page(bvec.bv_page);
1529 }
1530 EXPORT_SYMBOL_GPL(rq_flush_dcache_pages);
1531 #endif
1532 
1533 /**
1534  * blk_lld_busy - Check if underlying low-level drivers of a device are busy
1535  * @q : the queue of the device being checked
1536  *
1537  * Description:
1538  *    Check if underlying low-level drivers of a device are busy.
1539  *    If the drivers want to export their busy state, they must set own
1540  *    exporting function using blk_queue_lld_busy() first.
1541  *
1542  *    Basically, this function is used only by request stacking drivers
1543  *    to stop dispatching requests to underlying devices when underlying
1544  *    devices are busy.  This behavior helps more I/O merging on the queue
1545  *    of the request stacking driver and prevents I/O throughput regression
1546  *    on burst I/O load.
1547  *
1548  * Return:
1549  *    0 - Not busy (The request stacking driver should dispatch request)
1550  *    1 - Busy (The request stacking driver should stop dispatching request)
1551  */
1552 int blk_lld_busy(struct request_queue *q)
1553 {
1554         if (queue_is_mq(q) && q->mq_ops->busy)
1555                 return q->mq_ops->busy(q);
1556 
1557         return 0;
1558 }
1559 EXPORT_SYMBOL_GPL(blk_lld_busy);
1560 
1561 /**
1562  * blk_rq_unprep_clone - Helper function to free all bios in a cloned request
1563  * @rq: the clone request to be cleaned up
1564  *
1565  * Description:
1566  *     Free all bios in @rq for a cloned request.
1567  */
1568 void blk_rq_unprep_clone(struct request *rq)
1569 {
1570         struct bio *bio;
1571 
1572         while ((bio = rq->bio) != NULL) {
1573                 rq->bio = bio->bi_next;
1574 
1575                 bio_put(bio);
1576         }
1577 }
1578 EXPORT_SYMBOL_GPL(blk_rq_unprep_clone);
1579 
1580 /*
1581  * Copy attributes of the original request to the clone request.
1582  * The actual data parts (e.g. ->cmd, ->sense) are not copied.
1583  */
1584 static void __blk_rq_prep_clone(struct request *dst, struct request *src)
1585 {
1586         dst->__sector = blk_rq_pos(src);
1587         dst->__data_len = blk_rq_bytes(src);
1588         if (src->rq_flags & RQF_SPECIAL_PAYLOAD) {
1589                 dst->rq_flags |= RQF_SPECIAL_PAYLOAD;
1590                 dst->special_vec = src->special_vec;
1591         }
1592         dst->nr_phys_segments = src->nr_phys_segments;
1593         dst->ioprio = src->ioprio;
1594         dst->extra_len = src->extra_len;
1595 }
1596 
1597 /**
1598  * blk_rq_prep_clone - Helper function to setup clone request
1599  * @rq: the request to be setup
1600  * @rq_src: original request to be cloned
1601  * @bs: bio_set that bios for clone are allocated from
1602  * @gfp_mask: memory allocation mask for bio
1603  * @bio_ctr: setup function to be called for each clone bio.
1604  *           Returns %0 for success, non %0 for failure.
1605  * @data: private data to be passed to @bio_ctr
1606  *
1607  * Description:
1608  *     Clones bios in @rq_src to @rq, and copies attributes of @rq_src to @rq.
1609  *     The actual data parts of @rq_src (e.g. ->cmd, ->sense)
1610  *     are not copied, and copying such parts is the caller's responsibility.
1611  *     Also, pages which the original bios are pointing to are not copied
1612  *     and the cloned bios just point same pages.
1613  *     So cloned bios must be completed before original bios, which means
1614  *     the caller must complete @rq before @rq_src.
1615  */
1616 int blk_rq_prep_clone(struct request *rq, struct request *rq_src,
1617                       struct bio_set *bs, gfp_t gfp_mask,
1618                       int (*bio_ctr)(struct bio *, struct bio *, void *),
1619                       void *data)
1620 {
1621         struct bio *bio, *bio_src;
1622 
1623         if (!bs)
1624                 bs = &fs_bio_set;
1625 
1626         __rq_for_each_bio(bio_src, rq_src) {
1627                 bio = bio_clone_fast(bio_src, gfp_mask, bs);
1628                 if (!bio)
1629                         goto free_and_out;
1630 
1631                 if (bio_ctr && bio_ctr(bio, bio_src, data))
1632                         goto free_and_out;
1633 
1634                 if (rq->bio) {
1635                         rq->biotail->bi_next = bio;
1636                         rq->biotail = bio;
1637                 } else
1638                         rq->bio = rq->biotail = bio;
1639         }
1640 
1641         __blk_rq_prep_clone(rq, rq_src);
1642 
1643         return 0;
1644 
1645 free_and_out:
1646         if (bio)
1647                 bio_put(bio);
1648         blk_rq_unprep_clone(rq);
1649 
1650         return -ENOMEM;
1651 }
1652 EXPORT_SYMBOL_GPL(blk_rq_prep_clone);
1653 
1654 int kblockd_schedule_work(struct work_struct *work)
1655 {
1656         return queue_work(kblockd_workqueue, work);
1657 }
1658 EXPORT_SYMBOL(kblockd_schedule_work);
1659 
1660 int kblockd_schedule_work_on(int cpu, struct work_struct *work)
1661 {
1662         return queue_work_on(cpu, kblockd_workqueue, work);
1663 }
1664 EXPORT_SYMBOL(kblockd_schedule_work_on);
1665 
1666 int kblockd_mod_delayed_work_on(int cpu, struct delayed_work *dwork,
1667                                 unsigned long delay)
1668 {
1669         return mod_delayed_work_on(cpu, kblockd_workqueue, dwork, delay);
1670 }
1671 EXPORT_SYMBOL(kblockd_mod_delayed_work_on);
1672 
1673 /**
1674  * blk_start_plug - initialize blk_plug and track it inside the task_struct
1675  * @plug:       The &struct blk_plug that needs to be initialized
1676  *
1677  * Description:
1678  *   blk_start_plug() indicates to the block layer an intent by the caller
1679  *   to submit multiple I/O requests in a batch.  The block layer may use
1680  *   this hint to defer submitting I/Os from the caller until blk_finish_plug()
1681  *   is called.  However, the block layer may choose to submit requests
1682  *   before a call to blk_finish_plug() if the number of queued I/Os
1683  *   exceeds %BLK_MAX_REQUEST_COUNT, or if the size of the I/O is larger than
1684  *   %BLK_PLUG_FLUSH_SIZE.  The queued I/Os may also be submitted early if
1685  *   the task schedules (see below).
1686  *
1687  *   Tracking blk_plug inside the task_struct will help with auto-flushing the
1688  *   pending I/O should the task end up blocking between blk_start_plug() and
1689  *   blk_finish_plug(). This is important from a performance perspective, but
1690  *   also ensures that we don't deadlock. For instance, if the task is blocking
1691  *   for a memory allocation, memory reclaim could end up wanting to free a
1692  *   page belonging to that request that is currently residing in our private
1693  *   plug. By flushing the pending I/O when the process goes to sleep, we avoid
1694  *   this kind of deadlock.
1695  */
1696 void blk_start_plug(struct blk_plug *plug)
1697 {
1698         struct task_struct *tsk = current;
1699 
1700         /*
1701          * If this is a nested plug, don't actually assign it.
1702          */
1703         if (tsk->plug)
1704                 return;
1705 
1706         INIT_LIST_HEAD(&plug->mq_list);
1707         INIT_LIST_HEAD(&plug->cb_list);
1708         plug->rq_count = 0;
1709         plug->multiple_queues = false;
1710 
1711         /*
1712          * Store ordering should not be needed here, since a potential
1713          * preempt will imply a full memory barrier
1714          */
1715         tsk->plug = plug;
1716 }
1717 EXPORT_SYMBOL(blk_start_plug);
1718 
1719 static void flush_plug_callbacks(struct blk_plug *plug, bool from_schedule)
1720 {
1721         LIST_HEAD(callbacks);
1722 
1723         while (!list_empty(&plug->cb_list)) {
1724                 list_splice_init(&plug->cb_list, &callbacks);
1725 
1726                 while (!list_empty(&callbacks)) {
1727                         struct blk_plug_cb *cb = list_first_entry(&callbacks,
1728                                                           struct blk_plug_cb,
1729                                                           list);
1730                         list_del(&cb->list);
1731                         cb->callback(cb, from_schedule);
1732                 }
1733         }
1734 }
1735 
1736 struct blk_plug_cb *blk_check_plugged(blk_plug_cb_fn unplug, void *data,
1737                                       int size)
1738 {
1739         struct blk_plug *plug = current->plug;
1740         struct blk_plug_cb *cb;
1741 
1742         if (!plug)
1743                 return NULL;
1744 
1745         list_for_each_entry(cb, &plug->cb_list, list)
1746                 if (cb->callback == unplug && cb->data == data)
1747                         return cb;
1748 
1749         /* Not currently on the callback list */
1750         BUG_ON(size < sizeof(*cb));
1751         cb = kzalloc(size, GFP_ATOMIC);
1752         if (cb) {
1753                 cb->data = data;
1754                 cb->callback = unplug;
1755                 list_add(&cb->list, &plug->cb_list);
1756         }
1757         return cb;
1758 }
1759 EXPORT_SYMBOL(blk_check_plugged);
1760 
1761 void blk_flush_plug_list(struct blk_plug *plug, bool from_schedule)
1762 {
1763         flush_plug_callbacks(plug, from_schedule);
1764 
1765         if (!list_empty(&plug->mq_list))
1766                 blk_mq_flush_plug_list(plug, from_schedule);
1767 }
1768 
1769 /**
1770  * blk_finish_plug - mark the end of a batch of submitted I/O
1771  * @plug:       The &struct blk_plug passed to blk_start_plug()
1772  *
1773  * Description:
1774  * Indicate that a batch of I/O submissions is complete.  This function
1775  * must be paired with an initial call to blk_start_plug().  The intent
1776  * is to allow the block layer to optimize I/O submission.  See the
1777  * documentation for blk_start_plug() for more information.
1778  */
1779 void blk_finish_plug(struct blk_plug *plug)
1780 {
1781         if (plug != current->plug)
1782                 return;
1783         blk_flush_plug_list(plug, false);
1784 
1785         current->plug = NULL;
1786 }
1787 EXPORT_SYMBOL(blk_finish_plug);
1788 
1789 int __init blk_dev_init(void)
1790 {
1791         BUILD_BUG_ON(REQ_OP_LAST >= (1 << REQ_OP_BITS));
1792         BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 *
1793                         FIELD_SIZEOF(struct request, cmd_flags));
1794         BUILD_BUG_ON(REQ_OP_BITS + REQ_FLAG_BITS > 8 *
1795                         FIELD_SIZEOF(struct bio, bi_opf));
1796 
1797         /* used for unplugging and affects IO latency/throughput - HIGHPRI */
1798         kblockd_workqueue = alloc_workqueue("kblockd",
1799                                             WQ_MEM_RECLAIM | WQ_HIGHPRI, 0);
1800         if (!kblockd_workqueue)
1801                 panic("Failed to create kblockd\n");
1802 
1803         blk_requestq_cachep = kmem_cache_create("request_queue",
1804                         sizeof(struct request_queue), 0, SLAB_PANIC, NULL);
1805 
1806 #ifdef CONFIG_DEBUG_FS
1807         blk_debugfs_root = debugfs_create_dir("block", NULL);
1808 #endif
1809 
1810         return 0;
1811 }
/* [<][>][^][v][top][bottom][index][help] */
root/block/blk-core.c

DEFINITIONS
