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  * blk_end_sync_rq - executes a completion event on a request
  16  * @rq: request to complete
  17  * @error: end I/O status of the request
  18  */
  19 static void blk_end_sync_rq(struct request *rq, int error)
  20 {
  21         struct completion *waiting = rq->end_io_data;
  22
  23         rq->end_io_data = NULL;
  24
  25         /*
  26          * complete last, if this is a stack request the process (and thus
  27          * the rq pointer) could be invalid right after this complete()
  28          */
  29         complete(waiting);
  30 }
  31
  32 /**
  33  * blk_execute_rq_nowait - insert a request into queue for execution
  34  * @q:          queue to insert the request in
  35  * @bd_disk:    matching gendisk
  36  * @rq:         request to insert
  37  * @at_head:    insert request at head or tail of queue
  38  * @done:       I/O completion handler
  39  *
  40  * Description:
  41  *    Insert a fully prepared request at the back of the I/O scheduler queue
  42  *    for execution.  Don't wait for completion.
  43  *
  44  * Note:
  45  *    This function will invoke @done directly if the queue is dead.
  46  */
  47 void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
  48                            struct request *rq, int at_head,
  49                            rq_end_io_fn *done)
  50 {
  51         int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
  52
  53         WARN_ON(irqs_disabled());
  54         WARN_ON(!blk_rq_is_passthrough(rq));
  55
  56         rq->rq_disk = bd_disk;
  57         rq->end_io = done;
  58
  59         /*
  60          * don't check dying flag for MQ because the request won't
  61          * be reused after dying flag is set
  62          */
  63         if (q->mq_ops) {
  64                 blk_mq_sched_insert_request(rq, at_head, true, false, false);
  65                 return;
  66         }
  67
  68         spin_lock_irq(q->queue_lock);
  69
  70         if (unlikely(blk_queue_dying(q))) {
  71                 rq->rq_flags |= RQF_QUIET;
  72                 __blk_end_request_all(rq, -ENXIO);
  73                 spin_unlock_irq(q->queue_lock);
  74                 return;
  75         }
  76
  77         __elv_add_request(q, rq, where);
  78         __blk_run_queue(q);
  79         spin_unlock_irq(q->queue_lock);
  80 }
  81 EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
  82
  83 /**
  84  * blk_execute_rq - insert a request into queue for execution
  85  * @q:          queue to insert the request in
  86  * @bd_disk:    matching gendisk
  87  * @rq:         request to insert
  88  * @at_head:    insert request at head or tail of queue
  89  *
  90  * Description:
  91  *    Insert a fully prepared request at the back of the I/O scheduler queue
  92  *    for execution and wait for completion.
  93  */
  94 void blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
  95                    struct request *rq, int at_head)
  96 {
  97         DECLARE_COMPLETION_ONSTACK(wait);
  98         unsigned long hang_check;
  99
 100         rq->end_io_data = &wait;
 101         blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
 102
 103         /* Prevent hang_check timer from firing at us during very long I/O */
 104         hang_check = sysctl_hung_task_timeout_secs;
 105         if (hang_check)
 106                 while (!wait_for_completion_io_timeout(&wait, hang_check * (HZ/2)));
 107         else
 108                 wait_for_completion_io(&wait);
 109 }
 110 EXPORT_SYMBOL(blk_execute_rq);