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authorJens Axboe <jens.axboe@oracle.com>2007-09-27 13:01:25 +0200
committerJens Axboe <jens.axboe@oracle.com>2007-10-16 11:03:56 +0200
commitbf2de6f5a4faf0197268f18d08969b003b87b6e8 (patch)
tree16830a15a7effea352445a7aba5dbb433314d3eb /block/elevator.c
parentc07e2b41291853b19fff11ceee3657df252a4e42 (diff)
downloadlinux-bf2de6f5a4faf0197268f18d08969b003b87b6e8.tar.bz2
block: Initial support for data-less (or empty) barrier support
This implements functionality to pass down or insert a barrier in a queue, without having data attached to it. The ->prepare_flush_fn() infrastructure from data barriers are reused to provide this functionality. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'block/elevator.c')
-rw-r--r--block/elevator.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/block/elevator.c b/block/elevator.c
index ec23ca02f2fe..952aee04a68a 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -712,6 +712,14 @@ struct request *elv_next_request(struct request_queue *q)
int ret;
while ((rq = __elv_next_request(q)) != NULL) {
+ /*
+ * Kill the empty barrier place holder, the driver must
+ * not ever see it.
+ */
+ if (blk_empty_barrier(rq)) {
+ end_queued_request(rq, 1);
+ continue;
+ }
if (!(rq->cmd_flags & REQ_STARTED)) {
/*
* This is the first time the device driver