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 */
 23static 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 */
 51void 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
 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	/*
 73	 * need to check this before __blk_run_queue(), because rq can
 74	 * be freed before that returns.
 75	 */
 76	is_pm_resume = rq->cmd_type == REQ_TYPE_PM_RESUME;
 77
 78	spin_lock_irq(q->queue_lock);
 79
 80	if (unlikely(blk_queue_dying(q))) {
 81		rq->cmd_flags |= REQ_QUIET; 
 82		rq->errors = -ENXIO;
 83		__blk_end_request_all(rq, rq->errors);
 84		spin_unlock_irq(q->queue_lock);
 85		return;
 86	}
 87
 88	__elv_add_request(q, rq, where);
 89	__blk_run_queue(q);
 90	/* the queue is stopped so it won't be run */
 91	if (is_pm_resume)
 92		__blk_run_queue_uncond(q);
 93	spin_unlock_irq(q->queue_lock);
 94}
 95EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
 96
 97/**
 98 * blk_execute_rq - insert a request into queue for execution
 99 * @q:		queue to insert the request in
100 * @bd_disk:	matching gendisk
101 * @rq:		request to insert
102 * @at_head:    insert request at head or tail of queue
103 *
104 * Description:
105 *    Insert a fully prepared request at the back of the I/O scheduler queue
106 *    for execution and wait for completion.
107 */
108int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
109		   struct request *rq, int at_head)
110{
111	DECLARE_COMPLETION_ONSTACK(wait);
112	char sense[SCSI_SENSE_BUFFERSIZE];
113	int err = 0;
114	unsigned long hang_check;
115
116	if (!rq->sense) {
117		memset(sense, 0, sizeof(sense));
118		rq->sense = sense;
119		rq->sense_len = 0;
120	}
121
122	rq->end_io_data = &wait;
123	blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
124
125	/* Prevent hang_check timer from firing at us during very long I/O */
126	hang_check = sysctl_hung_task_timeout_secs;
127	if (hang_check)
128		while (!wait_for_completion_io_timeout(&wait, hang_check * (HZ/2)));
129	else
130		wait_for_completion_io(&wait);
131
132	if (rq->errors)
133		err = -EIO;
134
135	return err;
136}
137EXPORT_SYMBOL(blk_execute_rq);