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  */
  23 static 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  */
  51 void 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         bool is_pm_resume;
  57
  58         WARN_ON(irqs_disabled());
  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 resued 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         /*
  73          * need to check this before __blk_run_queue(), because rq can
  74          * be freed before that returns.
  75          */
  76         is_pm_resume = rq->cmd_type == REQ_TYPE_PM_RESUME;
  77
  78         spin_lock_irq(q->queue_lock);
  79
  80         if (unlikely(blk_queue_dying(q))) {
  81                 rq->cmd_flags |= REQ_QUIET;
  82                 rq->errors = -ENXIO;
  83                 __blk_end_request_all(rq, rq->errors);
  84                 spin_unlock_irq(q->queue_lock);
  85                 return;
  86         }
  87
  88         __elv_add_request(q, rq, where);
  89         __blk_run_queue(q);
  90         /* the queue is stopped so it won't be run */
  91         if (is_pm_resume)
  92                 __blk_run_queue_uncond(q);
  93         spin_unlock_irq(q->queue_lock);
  94 }
  95 EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
  96
  97 /**
  98  * blk_execute_rq - insert a request into queue for execution
  99  * @q:          queue to insert the request in
 100  * @bd_disk:    matching gendisk
 101  * @rq:         request to insert
 102  * @at_head:    insert request at head or tail of queue
 103  *
 104  * Description:
 105  *    Insert a fully prepared request at the back of the I/O scheduler queue
 106  *    for execution and wait for completion.
 107  */
 108 int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
 109                    struct request *rq, int at_head)
 110 {
 111         DECLARE_COMPLETION_ONSTACK(wait);
 112         char sense[SCSI_SENSE_BUFFERSIZE];
 113         int err = 0;
 114         unsigned long hang_check;
 115
 116         if (!rq->sense) {
 117                 memset(sense, 0, sizeof(sense));
 118                 rq->sense = sense;
 119                 rq->sense_len = 0;
 120         }
 121
 122         rq->end_io_data = &wait;
 123         blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
 124
 125         /* Prevent hang_check timer from firing at us during very long I/O */
 126         hang_check = sysctl_hung_task_timeout_secs;
 127         if (hang_check)
 128                 while (!wait_for_completion_io_timeout(&wait, hang_check * (HZ/2)));
 129         else
 130                 wait_for_completion_io(&wait);
 131
 132         if (rq->errors)
 133                 err = -EIO;
 134
 135         if (rq->sense == sense) {
 136                 rq->sense = NULL;
 137                 rq->sense_len = 0;
 138         }
 139
 140         return err;
 141 }
 142 EXPORT_SYMBOL(blk_execute_rq);