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[SCSI] make blk layer set REQ_SOFTBARRIER on defer and requeue 

This is the reworked version of the patch.  It sets REQ_SOFTBARRIER
in two places - in elv_next_request() on BLKPREP_DEFER and in
blk_requeue_request().

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
This commit is contained in:
Tejun Heo 2005-04-24 02:04:21 -05:00 committed by James Bottomley
parent 354d6b2196
commit 2e759cd4fa
1 changed files with 13 additions and 0 deletions
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13
drivers/block/elevator.c
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@ -290,6 +290,13 @@ void elv_requeue_request(request_queue_t *q, struct request *rq)
rq = rq->end_io_data;
}
/*
* the request is prepped and may have some resources allocated.
* allowing unprepped requests to pass this one may cause resource
* deadlock. turn on softbarrier.
*/
rq->flags |= REQ_SOFTBARRIER;
/*
* if iosched has an explicit requeue hook, then use that. otherwise
* just put the request at the front of the queue
@ -386,6 +393,12 @@ struct request *elv_next_request(request_queue_t *q)
if (ret == BLKPREP_OK) {
break;
} else if (ret == BLKPREP_DEFER) {
/*
* the request may have been (partially) prepped.
* we need to keep this request in the front to
* avoid resource deadlock. turn on softbarrier.
*/
rq->flags |= REQ_SOFTBARRIER;
rq = NULL;
break;
} else if (ret == BLKPREP_KILL) {