LXR linux/block/blk-exec.c

   1/*
   2 * Functions related to setting various queue properties from drivers
   3 */
   4#include <linux/kernel.h>
   5#include <linux/module.h>
   6#include <linux/bio.h>
   7#include <linux/blkdev.h>
   8#include <linux/blk-mq.h>
   9#include <linux/sched/sysctl.h>
  10
  11#include "blk.h"
  12
  13/*
  14 * for max sense size
  15 */
  16#include <scsi/scsi_cmnd.h>
  17
  18/**
  19 * blk_end_sync_rq - executes a completion event on a request
  20 * @rq: request to complete
  21 * @error: end I/O status of the request
  22 */
  23static void blk_end_sync_rq(struct request *rq, int error)
  24{
  25        struct completion *waiting = rq->end_io_data;
  26
  27        rq->end_io_data = NULL;
  28
  29        /*
  30         * complete last, if this is a stack request the process (and thus
  31         * the rq pointer) could be invalid right after this complete()
  32         */
  33        complete(waiting);
  34}
  35
  36/**
  37 * blk_execute_rq_nowait - insert a request into queue for execution
  38 * @q:          queue to insert the request in
  39 * @bd_disk:    matching gendisk
  40 * @rq:         request to insert
  41 * @at_head:    insert request at head or tail of queue
  42 * @done:       I/O completion handler
  43 *
  44 * Description:
  45 *    Insert a fully prepared request at the back of the I/O scheduler queue
  46 *    for execution.  Don't wait for completion.
  47 *
  48 * Note:
  49 *    This function will invoke @done directly if the queue is dead.
  50 */
  51void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
  52                           struct request *rq, int at_head,
  53                           rq_end_io_fn *done)
  54{
  55        int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
  56
  57        WARN_ON(irqs_disabled());
  58        WARN_ON(rq->cmd_type == REQ_TYPE_FS);
  59
  60        rq->rq_disk = bd_disk;
  61        rq->end_io = done;
  62
  63        /*
  64         * don't check dying flag for MQ because the request won't
  65         * be reused after dying flag is set
  66         */
  67        if (q->mq_ops) {
  68                blk_mq_insert_request(rq, at_head, true, false);
  69                return;
  70        }
  71
  72        spin_lock_irq(q->queue_lock);
  73
  74        if (unlikely(blk_queue_dying(q))) {
  75                rq->cmd_flags |= REQ_QUIET; 
  76                rq->errors = -ENXIO;
  77                __blk_end_request_all(rq, rq->errors);
  78                spin_unlock_irq(q->queue_lock);
  79                return;
  80        }
  81
  82        __elv_add_request(q, rq, where);
  83        __blk_run_queue(q);
  84        spin_unlock_irq(q->queue_lock);
  85}
  86EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
  87
  88/**
  89 * blk_execute_rq - insert a request into queue for execution
  90 * @q:          queue to insert the request in
  91 * @bd_disk:    matching gendisk
  92 * @rq:         request to insert
  93 * @at_head:    insert request at head or tail of queue
  94 *
  95 * Description:
  96 *    Insert a fully prepared request at the back of the I/O scheduler queue
  97 *    for execution and wait for completion.
  98 */
  99int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
 100                   struct request *rq, int at_head)
 101{
 102        DECLARE_COMPLETION_ONSTACK(wait);
 103        char sense[SCSI_SENSE_BUFFERSIZE];
 104        int err = 0;
 105        unsigned long hang_check;
 106
 107        if (!rq->sense) {
 108                memset(sense, 0, sizeof(sense));
 109                rq->sense = sense;
 110                rq->sense_len = 0;
 111        }
 112
 113        rq->end_io_data = &wait;
 114        blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
 115
 116        /* Prevent hang_check timer from firing at us during very long I/O */
 117        hang_check = sysctl_hung_task_timeout_secs;
 118        if (hang_check)
 119                while (!wait_for_completion_io_timeout(&wait, hang_check * (HZ/2)));
 120        else
 121                wait_for_completion_io(&wait);
 122
 123        if (rq->errors)
 124                err = -EIO;
 125
 126        if (rq->sense == sense) {
 127                rq->sense = NULL;
 128                rq->sense_len = 0;
 129        }
 130
 131        return err;
 132}
 133EXPORT_SYMBOL(blk_execute_rq);
 134