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path: root/drivers/block/elevator.c
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Diffstat (limited to 'drivers/block/elevator.c')
-rw-r--r--drivers/block/elevator.c22
1 files changed, 14 insertions, 8 deletions
diff --git a/drivers/block/elevator.c b/drivers/block/elevator.c
index 6b79b431462..f831f08f839 100644
--- a/drivers/block/elevator.c
+++ b/drivers/block/elevator.c
@@ -220,11 +220,6 @@ void elevator_exit(elevator_t *e)
kfree(e);
}
-static int elevator_global_init(void)
-{
- return 0;
-}
-
int elv_merge(request_queue_t *q, struct request **req, struct bio *bio)
{
elevator_t *e = q->elevator;
@@ -291,6 +286,13 @@ void elv_requeue_request(request_queue_t *q, struct request *rq)
}
/*
+ * 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
*/
@@ -322,7 +324,7 @@ void __elv_add_request(request_queue_t *q, struct request *rq, int where,
int nrq = q->rq.count[READ] + q->rq.count[WRITE]
- q->in_flight;
- if (nrq == q->unplug_thresh)
+ if (nrq >= q->unplug_thresh)
__generic_unplug_device(q);
}
} else
@@ -386,6 +388,12 @@ 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) {
@@ -692,8 +700,6 @@ ssize_t elv_iosched_show(request_queue_t *q, char *name)
return len;
}
-module_init(elevator_global_init);
-
EXPORT_SYMBOL(elv_add_request);
EXPORT_SYMBOL(__elv_add_request);
EXPORT_SYMBOL(elv_requeue_request);