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/sched/sysctl.h>
   9
  10 #include "blk.h"
  11
  12 /*
  13  * for max sense size
  14  */
  15 #include <scsi/scsi_cmnd.h>
  16
  17 /**
  18  * blk_end_sync_rq - executes a completion event on a request
  19  * @rq: request to complete
  20  * @error: end I/O status of the request
  21  */
  22 static void blk_end_sync_rq(struct request *rq, int error)
  23 {
  24         struct completion *waiting = rq->end_io_data;
  25
  26         rq->end_io_data = NULL;
  27         __blk_put_request(rq->q, rq);
  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          * need to check this before __blk_run_queue(), because rq can
  64          * be freed before that returns.
  65          */
  66         is_pm_resume = rq->cmd_type == REQ_TYPE_PM_RESUME;
  67
  68         spin_lock_irq(q->queue_lock);
  69
  70         if (unlikely(blk_queue_dying(q))) {
  71                 rq->errors = -ENXIO;
  72                 if (rq->end_io)
  73                         rq->end_io(rq, rq->errors);
  74                 spin_unlock_irq(q->queue_lock);
  75                 return;
  76         }
  77
  78         __elv_add_request(q, rq, where);
  79         __blk_run_queue(q);
  80         /* the queue is stopped so it won't be run */
  81         if (is_pm_resume)
  82                 __blk_run_queue_uncond(q);
  83         spin_unlock_irq(q->queue_lock);
  84 }
  85 EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
  86
  87 /**
  88  * blk_execute_rq - insert a request into queue for execution
  89  * @q:          queue to insert the request in
  90  * @bd_disk:    matching gendisk
  91  * @rq:         request to insert
  92  * @at_head:    insert request at head or tail of queue
  93  *
  94  * Description:
  95  *    Insert a fully prepared request at the back of the I/O scheduler queue
  96  *    for execution and wait for completion.
  97  */
  98 int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
  99                    struct request *rq, int at_head)
 100 {
 101         DECLARE_COMPLETION_ONSTACK(wait);
 102         char sense[SCSI_SENSE_BUFFERSIZE];
 103         int err = 0;
 104         unsigned long hang_check;
 105
 106         /*
 107          * we need an extra reference to the request, so we can look at
 108          * it after io completion
 109          */
 110         rq->ref_count++;
 111
 112         if (!rq->sense) {
 113                 memset(sense, 0, sizeof(sense));
 114                 rq->sense = sense;
 115                 rq->sense_len = 0;
 116         }
 117
 118         rq->end_io_data = &wait;
 119         blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
 120
 121         /* Prevent hang_check timer from firing at us during very long I/O */
 122         hang_check = sysctl_hung_task_timeout_secs;
 123         if (hang_check)
 124                 while (!wait_for_completion_io_timeout(&wait, hang_check * (HZ/2)));
 125         else
 126                 wait_for_completion_io(&wait);
 127
 128         if (rq->errors)
 129                 err = -EIO;
 130
 131         return err;
 132 }
 133 EXPORT_SYMBOL(blk_execute_rq);