1 files changed, 4 insertions, 1 deletions
diff --git a/block.h b/block.h
index f0129130be..72c1c24bb4 100644
--- a/block.h
+++ b/block.h
@@ -47,7 +47,10 @@ typedef struct QEMUSnapshotInfo {
                                      use a disk image format on top of
                                      it (default for
                                      bdrv_file_open()) */
-#define BDRV_O_DIRECT      0x0020
+#define BDRV_O_NOCACHE     0x0020 /* do not use the host page cache */
+#define BDRV_O_CACHE_WB    0x0040 /* use write-back caching */
+
+#define BDRV_O_CACHE_MASK  (BDRV_O_NOCACHE | BDRV_O_CACHE_WB)
 
 void bdrv_info(void);
 void bdrv_info_stats(void);