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         WARN_ON(rq->cmd_type == REQ_TYPE_FS);
  60
  61         rq->rq_disk = bd_disk;
  62         rq->end_io = done;
  63
  64         /*
  65          * don't check dying flag for MQ because the request won't
  66          * be resued after dying flag is set
  67          */
  68         if (q->mq_ops) {
  69                 blk_mq_insert_request(rq, at_head, true, false);
  70                 return;
  71         }
  72
  73         /*
  74          * need to check this before __blk_run_queue(), because rq can
  75          * be freed before that returns.
  76          */
  77         is_pm_resume = rq->cmd_type == REQ_TYPE_PM_RESUME;
  78
  79         spin_lock_irq(q->queue_lock);
  80
  81         if (unlikely(blk_queue_dying(q))) {
  82                 rq->cmd_flags |= REQ_QUIET;
  83                 rq->errors = -ENXIO;
  84                 __blk_end_request_all(rq, rq->errors);
  85                 spin_unlock_irq(q->queue_lock);
  86                 return;
  87         }
  88
  89         __elv_add_request(q, rq, where);
  90         __blk_run_queue(q);
  91         /* the queue is stopped so it won't be run */
  92         if (is_pm_resume)
  93                 __blk_run_queue_uncond(q);
  94         spin_unlock_irq(q->queue_lock);
  95 }
  96 EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
  97
  98 /**
  99  * blk_execute_rq - insert a request into queue for execution
 100  * @q:          queue to insert the request in
 101  * @bd_disk:    matching gendisk
 102  * @rq:         request to insert
 103  * @at_head:    insert request at head or tail of queue
 104  *
 105  * Description:
 106  *    Insert a fully prepared request at the back of the I/O scheduler queue
 107  *    for execution and wait for completion.
 108  */
 109 int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
 110                    struct request *rq, int at_head)
 111 {
 112         DECLARE_COMPLETION_ONSTACK(wait);
 113         char sense[SCSI_SENSE_BUFFERSIZE];
 114         int err = 0;
 115         unsigned long hang_check;
 116
 117         if (!rq->sense) {
 118                 memset(sense, 0, sizeof(sense));
 119                 rq->sense = sense;
 120                 rq->sense_len = 0;
 121         }
 122
 123         rq->end_io_data = &wait;
 124         blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
 125
 126         /* Prevent hang_check timer from firing at us during very long I/O */
 127         hang_check = sysctl_hung_task_timeout_secs;
 128         if (hang_check)
 129                 while (!wait_for_completion_io_timeout(&wait, hang_check * (HZ/2)));
 130         else
 131                 wait_for_completion_io(&wait);
 132
 133         if (rq->errors)
 134                 err = -EIO;
 135
 136         if (rq->sense == sense) {
 137                 rq->sense = NULL;
 138                 rq->sense_len = 0;
 139         }
 140
 141         return err;
 142 }
 143 EXPORT_SYMBOL(blk_execute_rq);