1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Functions related to setting various queue properties from drivers
  4 */
  5#include <linux/kernel.h>
  6#include <linux/module.h>
  7#include <linux/bio.h>
  8#include <linux/blkdev.h>
  9#include <linux/blk-mq.h>
 10#include <linux/sched/sysctl.h>
 11
 12#include "blk.h"
 13#include "blk-mq-sched.h"
 14
 15/**
 16 * blk_end_sync_rq - executes a completion event on a request
 17 * @rq: request to complete
 18 * @error: end I/O status of the request
 19 */
 20static void blk_end_sync_rq(struct request *rq, blk_status_t error)
 21{
 22	struct completion *waiting = rq->end_io_data;
 23
 24	rq->end_io_data = (void *)(uintptr_t)error;
 25
 26	/*
 27	 * complete last, if this is a stack request the process (and thus
 28	 * the rq pointer) could be invalid right after this complete()
 29	 */
 30	complete(waiting);
 31}
 32
 33/**
 34 * blk_execute_rq_nowait - insert a request to I/O scheduler for execution
 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 gendisk *bd_disk, struct request *rq,
 48			   int at_head, rq_end_io_fn *done)
 49{
 50	WARN_ON(irqs_disabled());
 51	WARN_ON(!blk_rq_is_passthrough(rq));
 52
 53	rq->rq_disk = bd_disk;
 54	rq->end_io = done;
 55
 56	blk_account_io_start(rq);
 57
 58	/*
 59	 * don't check dying flag for MQ because the request won't
 60	 * be reused after dying flag is set
 61	 */
 62	blk_mq_sched_insert_request(rq, at_head, true, false);
 63}
 64EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
 65
 66static bool blk_rq_is_poll(struct request *rq)
 67{
 68	return rq->mq_hctx && rq->mq_hctx->type == HCTX_TYPE_POLL;
 69}
 70
 71static void blk_rq_poll_completion(struct request *rq, struct completion *wait)
 72{
 73	do {
 74		blk_poll(rq->q, request_to_qc_t(rq->mq_hctx, rq), true);
 75		cond_resched();
 76	} while (!completion_done(wait));
 77}
 78
 79/**
 80 * blk_execute_rq - insert a request into queue for execution
 81 * @bd_disk:	matching gendisk
 82 * @rq:		request to insert
 83 * @at_head:    insert request at head or tail of queue
 84 *
 85 * Description:
 86 *    Insert a fully prepared request at the back of the I/O scheduler queue
 87 *    for execution and wait for completion.
 88 * Return: The blk_status_t result provided to blk_mq_end_request().
 89 */
 90blk_status_t blk_execute_rq(struct gendisk *bd_disk, struct request *rq, int at_head)
 91{
 92	DECLARE_COMPLETION_ONSTACK(wait);
 93	unsigned long hang_check;
 94
 95	rq->end_io_data = &wait;
 96	blk_execute_rq_nowait(bd_disk, rq, at_head, blk_end_sync_rq);
 97
 98	/* Prevent hang_check timer from firing at us during very long I/O */
 99	hang_check = sysctl_hung_task_timeout_secs;
100
101	if (blk_rq_is_poll(rq))
102		blk_rq_poll_completion(rq, &wait);
103	else if (hang_check)
104		while (!wait_for_completion_io_timeout(&wait, hang_check * (HZ/2)));
105	else
106		wait_for_completion_io(&wait);
107
108	return (blk_status_t)(uintptr_t)rq->end_io_data;
109}
110EXPORT_SYMBOL(blk_execute_rq);