113 lines
2.9 KiB
C
113 lines
2.9 KiB
C
/*
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* Functions related to setting various queue properties from drivers
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/bio.h>
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#include <linux/blkdev.h>
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#include "blk.h"
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/*
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* for max sense size
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*/
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#include <scsi/scsi_cmnd.h>
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/**
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* blk_end_sync_rq - executes a completion event on a request
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* @rq: request to complete
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* @error: end I/O status of the request
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*/
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static void blk_end_sync_rq(struct request *rq, int error)
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{
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struct completion *waiting = rq->end_io_data;
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rq->end_io_data = NULL;
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__blk_put_request(rq->q, rq);
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/*
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* complete last, if this is a stack request the process (and thus
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* the rq pointer) could be invalid right after this complete()
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*/
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complete(waiting);
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}
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/**
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* blk_execute_rq_nowait - insert a request into queue for execution
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* @q: queue to insert the request in
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* @bd_disk: matching gendisk
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* @rq: request to insert
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* @at_head: insert request at head or tail of queue
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* @done: I/O completion handler
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*
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* Description:
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* Insert a fully prepared request at the back of the I/O scheduler queue
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* for execution. Don't wait for completion.
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*/
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void blk_execute_rq_nowait(struct request_queue *q, struct gendisk *bd_disk,
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struct request *rq, int at_head,
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rq_end_io_fn *done)
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{
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int where = at_head ? ELEVATOR_INSERT_FRONT : ELEVATOR_INSERT_BACK;
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rq->rq_disk = bd_disk;
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rq->end_io = done;
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WARN_ON(irqs_disabled());
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spin_lock_irq(q->queue_lock);
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__elv_add_request(q, rq, where, 1);
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__generic_unplug_device(q);
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/* the queue is stopped so it won't be plugged+unplugged */
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if (rq->cmd_type == REQ_TYPE_PM_RESUME)
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q->request_fn(q);
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spin_unlock_irq(q->queue_lock);
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}
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EXPORT_SYMBOL_GPL(blk_execute_rq_nowait);
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/**
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* blk_execute_rq - insert a request into queue for execution
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* @q: queue to insert the request in
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* @bd_disk: matching gendisk
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* @rq: request to insert
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* @at_head: insert request at head or tail of queue
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*
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* Description:
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* Insert a fully prepared request at the back of the I/O scheduler queue
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* for execution and wait for completion.
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*/
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int blk_execute_rq(struct request_queue *q, struct gendisk *bd_disk,
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struct request *rq, int at_head)
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{
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DECLARE_COMPLETION_ONSTACK(wait);
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char sense[SCSI_SENSE_BUFFERSIZE];
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int err = 0;
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unsigned long hang_check;
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/*
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* we need an extra reference to the request, so we can look at
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* it after io completion
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*/
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rq->ref_count++;
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if (!rq->sense) {
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memset(sense, 0, sizeof(sense));
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rq->sense = sense;
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rq->sense_len = 0;
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}
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rq->end_io_data = &wait;
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blk_execute_rq_nowait(q, bd_disk, rq, at_head, blk_end_sync_rq);
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/* Prevent hang_check timer from firing at us during very long I/O */
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hang_check = sysctl_hung_task_timeout_secs;
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if (hang_check)
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while (!wait_for_completion_timeout(&wait, hang_check * (HZ/2)));
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else
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wait_for_completion(&wait);
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if (rq->errors)
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err = -EIO;
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return err;
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}
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EXPORT_SYMBOL(blk_execute_rq);
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