xen_disk: Account for flush operations

Currently both BLKIF_OP_WRITE and BLKIF_OP_FLUSH_DISKCACHE are being
accounted as write operations.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 7a2a14e3ac62027aa6267a6c02abc70717be9c0a.1446044837.git.berto@igalia.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

hw/block/xen_disk.c

diff --git a/hw/block/xen_disk.c b/hw/block/xen_disk.c
index 1bbc111..4869518 100644
--- a/hw/block/xen_disk.c
+++ b/hw/block/xen_disk.c
@@ -576,7 +576,9 @@
         }
 
         block_acct_start(blk_get_stats(blkdev->blk), &ioreq->acct,
-                         ioreq->v.size, BLOCK_ACCT_WRITE);
+                         ioreq->v.size,
+                         ioreq->req.operation == BLKIF_OP_WRITE ?
+                         BLOCK_ACCT_WRITE : BLOCK_ACCT_FLUSH);
         ioreq->aio_inflight++;
         blk_aio_writev(blkdev->blk, ioreq->start / BLOCK_SIZE,
                        &ioreq->v, ioreq->v.size / BLOCK_SIZE,