root/block/blk-exec.c

DEFINITIONS

1. blk_end_sync_rq
2. blk_execute_rq_nowait
3. blk_execute_rq

/*
 * 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.
 */
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;

        rq->rq_disk = bd_disk;
        rq->cmd_flags |= REQ_NOMERGE;
        rq->end_io = done;
        WARN_ON(irqs_disabled());
        spin_lock_irq(q->queue_lock);
        __elv_add_request(q, rq, where, 1);
        __generic_unplug_device(q);
        /* the queue is stopped so it won't be plugged+unplugged */
        if (blk_pm_resume_request(rq))
                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;

        /*
         * 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);
        wait_for_completion(&wait);

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

        return err;
}
EXPORT_SYMBOL(blk_execute_rq);