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ide: dequeue in-flight request

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ide generally has single request in flight and tracks it using
hwif->rq and all state handlers follow the following convention.

* ide_started is returned if the request is in flight.

* ide_stopped is returned if the queue needs to be restarted.  The
  request might or might not have been processed fully or partially.

* hwif->rq is set to NULL, when an issued request completes.

So, dequeueing model can be implemented by dequeueing after fetch,
requeueing if hwif->rq isn't NULL on ide_stopped return and doing
about the same thing on completion / port unlock paths.  These changes
can be made in ide-io proper.

In addition to the above main changes, the following updates are
necessary.

* ide-cd shouldn't dequeue a request when issuing REQUEST SENSE for it
  as the request is already dequeued.

* ide-atapi uses request queue as stack when issuing REQUEST SENSE to
  put the REQUEST SENSE in front of the failed request.  This now
  needs to be done using requeueing.

[ Impact: dequeue in-flight request ]

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Cc: Borislav Petkov <petkovbb@googlemail.com>
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Tejun Heo
2009-05-08 11:53:59 +09:00
committed by Jens Axboe
parent 1011c1b9f2
commit 8f6205cd57
3 changed files with 39 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files
drivers/ide/ide-atapi.c
+12 -2
View File
@@ -246,6 +246,7 @@ EXPORT_SYMBOL_GPL(ide_queue_sense_rq);
*/
void ide_retry_pc(ide_drive_t *drive)
{
struct request *failed_rq = drive->hwif->rq;
struct request *sense_rq = &drive->sense_rq;
struct ide_atapi_pc *pc = &drive->request_sense_pc;
@@ -260,8 +261,17 @@ void ide_retry_pc(ide_drive_t *drive)
if (drive->media == ide_tape)
set_bit(IDE_AFLAG_IGNORE_DSC, &drive->atapi_flags);
if (ide_queue_sense_rq(drive, pc))
ide_complete_rq(drive, -EIO, blk_rq_bytes(drive->hwif->rq));
/*
* Push back the failed request and put request sense on top
* of it. The failed command will be retried after sense data
* is acquired.
*/
blk_requeue_request(failed_rq->q, failed_rq);
drive->hwif->rq = NULL;
if (ide_queue_sense_rq(drive, pc)) {
blkdev_dequeue_request(failed_rq);
ide_complete_rq(drive, -EIO, blk_rq_bytes(failed_rq));
}
}
EXPORT_SYMBOL_GPL(ide_retry_pc);