block: add interface to toggle copy-on-read

The bdrv_enable_copy_on_read()/bdrv_disable_copy_on_read() functions can
be used to programmatically enable or disable copy-on-read for a block
device.  Later patches add the actual copy-on-read logic.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/block.h b/block.h
index 8482dbce75..5f8a98a746 100644
--- a/block.h
+++ b/block.h
@@ -70,6 +70,7 @@ typedef struct BlockDevOps {
 #define BDRV_O_NATIVE_AIO  0x0080 /* use native AIO instead of the thread pool */
 #define BDRV_O_NO_BACKING  0x0100 /* don't open the backing file */
 #define BDRV_O_NO_FLUSH    0x0200 /* disable flushing on this disk */
+#define BDRV_O_COPY_ON_READ 0x0400 /* copy read backing sectors into image */
 
 #define BDRV_O_CACHE_MASK  (BDRV_O_NOCACHE | BDRV_O_CACHE_WB | BDRV_O_NO_FLUSH)
 
@@ -312,6 +313,9 @@ void bdrv_reset_dirty(BlockDriverState *bs, int64_t cur_sector,
                       int nr_sectors);
 int64_t bdrv_get_dirty_count(BlockDriverState *bs);
 
+void bdrv_enable_copy_on_read(BlockDriverState *bs);
+void bdrv_disable_copy_on_read(BlockDriverState *bs);
+
 void bdrv_set_in_use(BlockDriverState *bs, int in_use);
 int bdrv_in_use(BlockDriverState *bs);