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 */
 19static void blk_end_sync_rq(struct request *rq, blk_status_t 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 */
 47void 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);
 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, BLK_STS_IOERR);
 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}
 81EXPORT_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 */
 94void 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}
110EXPORT_SYMBOL(blk_execute_rq);