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-rw-r--r--drivers/block/elevator.c13
1 files changed, 13 insertions, 0 deletions
diff --git a/drivers/block/elevator.c b/drivers/block/elevator.c
index 8998292..f831f08 100644
--- a/drivers/block/elevator.c
+++ b/drivers/block/elevator.c
@@ -286,6 +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
*/
@@ -381,6 +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) {