[PATCH 1/3] block: add queue flag for paravirt frontend drivers

Fernando Luis Vázquez Cao
2008-10-27T09:44:56Z

As is the case with SSD devices, we do not want to idle in AS/CFQ when
the block device is a paravirt front-end driver. This patch adds a flag
(QUEUE_FLAG_VIRT) which should be used by front-end drivers such as
virtio_blk and xen-blkfront to indicate a paravirtualized device.

Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
---

diff -urNp linux-2.6.28-rc2-orig/include/linux/blkdev.h linux-2.6.28-rc2/include/linux/blkdev.h
--- linux-2.6.28-rc2-orig/include/linux/blkdev.h 2008-10-27 17:41:58.000000000 +0900
+++ linux-2.6.28-rc2/include/linux/blkdev.h 2008-10-27 17:34:49.000000000 +0900
@@ -449,6 +449,7 @@ struct request_queue
#define QUEUE_FLAG_FAIL_IO 12 /* fake timeout */
#define QUEUE_FLAG_STACKABLE 13 /* supports request stacking */
#define QUEUE_FLAG_NONROT 14 /* non-rotational device (SSD) */
+#define QUEUE_FLAG_VIRT QUEUE_FLAG_NONROT /* paravirt device */

static inline int queue_is_locked(struct request_queue *q)
{