block: Introduce BDRV_O_NO_BACKING
If an image references a backing file that doesn't exist, qemu-img info fails
to open this image. Exactly in this case the info would be valuable, though:
the user might want to find out which file is missing.
This patch introduces a BDRV_O_NO_BACKING flag to ignore the backing file when
opening the image. qemu-img info is the first user and provides info now even
if the backing file is invalid.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/block.h b/block.h
index fa51ddf..f660d5f 100644
--- a/block.h
+++ b/block.h
@@ -39,6 +39,7 @@
#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_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_CACHE_MASK (BDRV_O_NOCACHE | BDRV_O_CACHE_WB)
