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