blk-mq: don't call into depth limiting for reserved tags
It's not useful, they are internal and/or error handling recovery
commands.
Acked-by: Paolo Valente <paolo.valente@linaro.org>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 4e9d835..64630ca 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -360,9 +360,11 @@ static struct request *blk_mq_get_request(struct request_queue *q,
/*
* Flush requests are special and go directly to the
- * dispatch list.
+ * dispatch list. Don't include reserved tags in the
+ * limiting, as it isn't useful.
*/
- if (!op_is_flush(op) && e->type->ops.mq.limit_depth)
+ if (!op_is_flush(op) && e->type->ops.mq.limit_depth &&
+ !(data->flags & BLK_MQ_REQ_RESERVED))
e->type->ops.mq.limit_depth(op, data);
}