[linux-2.6-block.git] / block / blk-exec.c

/*
 * 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 "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;
	__blk_put_request(rq->q, rq);

	/*
	 * 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;

	WARN_ON(irqs_disabled());

	rq->rq_disk = bd_disk;
	rq->end_io = done;

	spin_lock_irq(q->queue_lock);

	if (unlikely(blk_queue_dead(q))) {
		rq->errors = -ENXIO;
		if (rq->end_io)
			rq->end_io(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 (rq->cmd_type == REQ_TYPE_PM_RESUME)
		q->request_fn(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;

	/*
	 * we need an extra reference to the request, so we can look at
	 * it after io completion
	 */
	rq->ref_count++;

	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_timeout(&wait, hang_check * (HZ/2)));
	else
		wait_for_completion(&wait);

	if (rq->errors)
		err = -EIO;

	return err;
}
EXPORT_SYMBOL(blk_execute_rq);
Commit	Line	Data
86db1e29 JA	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
	9	#include "blk.h"
	10
	11	/*
	12	* for max sense size
	13	*/
	14	#include <scsi/scsi_cmnd.h>
	15
	16	/**
	17	* blk_end_sync_rq - executes a completion event on a request
	18	* @rq: request to complete
710027a4	19	* @error: end I/O status of the request
86db1e29	20	*/
681a561b	21	static void blk_end_sync_rq(struct request *rq, int error)
86db1e29 JA	22	{
	23	struct completion *waiting = rq->end_io_data;
	24
	25	rq->end_io_data = NULL;
	26	__blk_put_request(rq->q, rq);
	27
	28	/*
	29	* complete last, if this is a stack request the process (and thus
	30	* the rq pointer) could be invalid right after this complete()
	31	*/
	32	complete(waiting);
	33	}
86db1e29 JA	34
	35	/**
	36	* blk_execute_rq_nowait - insert a request into queue for execution
	37	* @q: queue to insert the request in
	38	* @bd_disk: matching gendisk
	39	* @rq: request to insert
	40	* @at_head: insert request at head or tail of queue
	41	* @done: I/O completion handler
	42	*
	43	* Description:
710027a4	44	* Insert a fully prepared request at the back of the I/O scheduler queue
86db1e29	45	* for execution. Don't wait for completion.
e81ca6fe MR	46	*
	47	* Note:
	48	* This function will invoke @done directly if the queue is dead.
86db1e29 JA	49	*/
	50	void blk_execute_rq_nowait(struct request_queue q, struct gendisk bd_disk,
	51	struct request *rq, int at_head,
	52	rq_end_io_fn *done)
	53	{
	54	int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
	55
8ba61435	56	WARN_ON(irqs_disabled());
e81ca6fe MR	57
	58	rq->rq_disk = bd_disk;
	59	rq->end_io = done;
	60
8ba61435 TH	61	spin_lock_irq(q->queue_lock);
8ba61435 TH	62
34f6055c	63	if (unlikely(blk_queue_dead(q))) {
bfe159a5 JB	64	rq->errors = -ENXIO;
	65	if (rq->end_io)
	66	rq->end_io(rq, rq->errors);
e81ca6fe	67	spin_unlock_irq(q->queue_lock);
bfe159a5 JB	68	return;
	69	}
	70
7eaceacc	71	__elv_add_request(q, rq, where);
24ecfbe2	72	__blk_run_queue(q);
addd0a09	73	/* the queue is stopped so it won't be run */
33659ebb	74	if (rq->cmd_type == REQ_TYPE_PM_RESUME)
9a2d43b7	75	q->request_fn(q);
86db1e29 JA	76	spin_unlock_irq(q->queue_lock);
	77	}
	78	EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
	79
	80	/**
	81	* blk_execute_rq - insert a request into queue for execution
	82	* @q: queue to insert the request in
	83	* @bd_disk: matching gendisk
	84	* @rq: request to insert
	85	* @at_head: insert request at head or tail of queue
	86	*
	87	* Description:
710027a4	88	* Insert a fully prepared request at the back of the I/O scheduler queue
86db1e29 JA	89	* for execution and wait for completion.
	90	*/
	91	int blk_execute_rq(struct request_queue q, struct gendisk bd_disk,
	92	struct request *rq, int at_head)
	93	{
	94	DECLARE_COMPLETION_ONSTACK(wait);
	95	char sense[SCSI_SENSE_BUFFERSIZE];
	96	int err = 0;
4b197769	97	unsigned long hang_check;
86db1e29 JA	98
	99	/*
	100	* we need an extra reference to the request, so we can look at
	101	* it after io completion
	102	*/
	103	rq->ref_count++;
	104
	105	if (!rq->sense) {
	106	memset(sense, 0, sizeof(sense));
	107	rq->sense = sense;
	108	rq->sense_len = 0;
	109	}
	110
	111	rq->end_io_data = &wait;
	112	blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
4b197769 ML	113
	114	/* Prevent hang_check timer from firing at us during very long I/O */
	115	hang_check = sysctl_hung_task_timeout_secs;
	116	if (hang_check)
	117	while (!wait_for_completion_timeout(&wait, hang_check * (HZ/2)));
	118	else
	119	wait_for_completion(&wait);
86db1e29 JA	120
	121	if (rq->errors)
	122	err = -EIO;
	123
	124	return err;
	125	}
86db1e29	126	EXPORT_SYMBOL(blk_execute_rq);