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
  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 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         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 }
  86 EXPORT_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  */
  99 int 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 }
 133 EXPORT_SYMBOL(blk_execute_rq);