block: support known backing format for image create and open (Uri Lublin)

Added a backing_format field to BlockDriverState.
Added bdrv_create2 and drv->bdrv_create2 to create an image with
a known backing file format.
Upon bdrv_open2 if backing format is known use it, instead of
probing the (backing) image.

Signed-off-by: Uri Lublin <uril@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6908 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 7 insertions, 0 deletions

diff --git a/block_int.h b/block_int.h
index b45bde04d4..af6dff6bd6 100644
--- a/block_int.h
+++ b/block_int.h
@@ -91,6 +91,12 @@ struct BlockDriver {
         BlockDriverCompletionFunc *cb, void *opaque);
 
     AIOPool aio_pool;
+
+    /* new create with backing file format */
+    int (*bdrv_create2)(const char *filename, int64_t total_sectors,
+                        const char *backing_file, const char *backing_format,
+                        int flags);
+
     struct BlockDriver *next;
 };
 
@@ -113,6 +119,7 @@ struct BlockDriverState {
     char filename[1024];
     char backing_file[1024]; /* if non zero, the image is a diff of
                                 this file image */
+    char backing_format[16]; /* if non-zero and backing_file exists */
     int is_temporary;
     int media_changed;