/* * Functions related to setting various queue properties from drivers */#include <linux/kernel.h>#include <linux/module.h>#include <linux/bio.h>#include <linux/blkdev.h>#include <linux/blk-mq.h>#include <linux/sched/sysctl.h> #include "blk.h" /* * for max sense size */#include <scsi/scsi_cmnd.h> /** * blk_end_sync_rq - executes a completion event on a request * @rq: request to complete * @error: end I/O status of the request */static void blk_end_sync_rq(struct request *rq, int error){	struct completion *waiting = rq->end_io_data; 	rq->end_io_data = NULL; 	/*	 * complete last, if this is a stack request the process (and thus	 * the rq pointer) could be invalid right after this complete()	 */	complete(waiting);} /** * blk_execute_rq_nowait - insert a request into queue for execution * @q:		queue to insert the request in * @bd_disk:	matching gendisk * @rq:		request to insert * @at_head:    insert request at head or tail of queue * @done:	I/O completion handler * * Description: *    Insert a fully prepared request at the back of the I/O scheduler queue *    for execution.  Don't wait for completion. * * Note: *    This function will invoke @done directly if the queue is dead. */void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,			   struct request *rq, int at_head,			   rq_end_io_fn *done){	int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;	bool is_pm_resume; 	WARN_ON(irqs_disabled()); 	rq->rq_disk = bd_disk;	rq->end_io = done; 	if (q->mq_ops) {		blk_mq_insert_request(q, rq, true);		return;	} 	/*	 * need to check this before __blk_run_queue(), because rq can	 * be freed before that returns.	 */	is_pm_resume = rq->cmd_type == REQ_TYPE_PM_RESUME; 	spin_lock_irq(q->queue_lock); 	if (unlikely(blk_queue_dying(q))) {		rq->cmd_flags |= REQ_QUIET; 		rq->errors = -ENXIO;		__blk_end_request_all(rq, rq->errors);		spin_unlock_irq(q->queue_lock);		return;	} 	__elv_add_request(q, rq, where);	__blk_run_queue(q);	/* the queue is stopped so it won't be run */	if (is_pm_resume)		__blk_run_queue_uncond(q);	spin_unlock_irq(q->queue_lock);}EXPORT_SYMBOL_GPL(blk_execute_rq_nowait); /** * blk_execute_rq - insert a request into queue for execution * @q:		queue to insert the request in * @bd_disk:	matching gendisk * @rq:		request to insert * @at_head:    insert request at head or tail of queue * * Description: *    Insert a fully prepared request at the back of the I/O scheduler queue *    for execution and wait for completion. */int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,		   struct request *rq, int at_head){	DECLARE_COMPLETION_ONSTACK(wait);	char sense[SCSI_SENSE_BUFFERSIZE];	int err = 0;	unsigned long hang_check; 	if (!rq->sense) {		memset(sense, 0, sizeof(sense));		rq->sense = sense;		rq->sense_len = 0;	} 	rq->end_io_data = &wait;	blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq); 	/* Prevent hang_check timer from firing at us during very long I/O */	hang_check = sysctl_hung_task_timeout_secs;	if (hang_check)		while (!wait_for_completion_io_timeout(&wait, hang_check * (HZ/2)));	else		wait_for_completion_io(&wait); 	if (rq->errors)		err = -EIO; 	return err;}EXPORT_SYMBOL(blk_execute_rq);