replace bdrv_{get, put}_buffer with bdrv_{load, save}_vmstate

The VM state offset is a concept internal to the image format.  Replace
the old bdrv_{get,put}_buffer method that require an index into the
image file that is constructed from the VM state offset and an offset
into the vmstate with the bdrv_{load,save}_vmstate that just take an
offset into the VM state.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/block.h b/block.h
index 406a199..ccd4c1e 100644
--- a/block.h
+++ b/block.h
@@ -159,9 +159,10 @@
                   const char *base_path,
                   const char *filename);
 
-int bdrv_put_buffer(BlockDriverState *bs, const uint8_t *buf,
-                    int64_t pos, int size);
+int bdrv_save_vmstate(BlockDriverState *bs, const uint8_t *buf,
+                      int64_t pos, int size);
 
-int bdrv_get_buffer(BlockDriverState *bs, uint8_t *buf, int64_t pos, int size);
+int bdrv_load_vmstate(BlockDriverState *bs, uint8_t *buf,
+                      int64_t pos, int size);
 
 #endif