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
 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 reused 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->rq_flags |= RQF_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}
 86EXPORT_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 */
 99int 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}
133EXPORT_SYMBOL(blk_execute_rq);