From 6dcfb751c927879399e404b3885cbdef7d8d368b Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk Date: Thu, 5 May 2011 12:41:03 -0400 Subject: [PATCH] xen-blkfront: Provide for 'feature-flush-cache' the BLKIF_OP_WRITE_FLUSH_CACHE operation. The operation BLKIF_OP_WRITE_FLUSH_CACHE has existed in the Xen tree header file for years but it was never present in the Linux tree because the frontend (nor the backend) supported this interface. Signed-off-by: Konrad Rzeszutek Wilk --- include/xen/interface/io/blkif.h | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/include/xen/interface/io/blkif.h b/include/xen/interface/io/blkif.h index 61e523af3c46..3d5d6db864fe 100644 --- a/include/xen/interface/io/blkif.h +++ b/include/xen/interface/io/blkif.h @@ -44,6 +44,19 @@ typedef uint64_t blkif_sector_t; */ #define BLKIF_OP_WRITE_BARRIER 2 +/* + * Recognised if "feature-flush-cache" is present in backend xenbus + * info. A flush will ask the underlying storage hardware to flush its + * non-volatile caches as appropriate. The "feature-flush-cache" node + * contains a boolean indicating whether flush requests are likely to + * succeed or fail. Either way, a flush request may fail at any time + * with BLKIF_RSP_EOPNOTSUPP if it is unsupported by the underlying + * block-device hardware. The boolean simply indicates whether or not it + * is worthwhile for the frontend to attempt flushes. If a backend does + * not recognise BLKIF_OP_WRITE_FLUSH_CACHE, it should *not* create the + * "feature-flush-cache" node! + */ +#define BLKIF_OP_FLUSH_DISKCACHE 3 /* * Maximum scatter/gather segments per request. * This is carefully chosen so that sizeof(struct blkif_ring) <= PAGE_SIZE. -- 2.20.1