[Qemu-devel] [PATCH 11/16] block/parallels: add support for backing files

["Denis V. Lunev" <den@openvz.org>]

From: Roman Kagan <rkagan@parallels.com>

Add backing file support to Parallels format driver.

That said, I think backing file operations should end up in the generic
block layer, but that's a longer story...

Signed-off-by: Roman Kagan <rkagan@parallels.com>
Signed-off-by: Denis V. Lunev <den@openvz.org>
CC: Jeff Cody <jcody@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
CC: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/parallels.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/block/parallels.c b/block/parallels.c
index 2d3e962..718274b 100644
--- a/block/parallels.c
+++ b/block/parallels.c
@@ -419,6 +419,11 @@ static int parallels_read(BlockDriverState *bs, int64_t sector_num,
             if (ret < 0) {
                 return ret;
             }
+        } else if (bs->backing_hd) {
+            int ret = bdrv_read(bs->backing_hd, sector_num, buf, n);
+            if (ret < 0) {
+                return ret;
+            }
         } else {
             memset(buf, 0, n << BDRV_SECTOR_BITS);
         }
@@ -454,6 +459,7 @@ static BlockDriver bdrv_parallels = {
     .bdrv_read          = parallels_co_read,
     .bdrv_close		= parallels_close,
     .bdrv_co_get_block_status = parallels_co_get_block_status,
+    .supports_backing  = true,
 };
 
 static void bdrv_parallels_init(void)
-- 
1.9.1