block: update in-memory backing file and format

These are needed to print "info block" output correctly.  QCOW2 does this
because it needs it to write the header, but QED does not, and common code
is the right place to do it.

Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

diff --git a/block.c b/block.c
index 068e41d9d9617800f5206b4fd1c88c164377e5b5..dbd60e3f3ef7393e8073c7a417581179f7cfae70 100644 (file)
--- a/block.c
+++ b/block.c
@@ -1459,6 +1459,7 @@ int bdrv_change_backing_file(BlockDriverState *bs,
     const char *backing_file, const char *backing_fmt)
 {
     BlockDriver *drv = bs->drv;
+    int ret;
 
     /* Backing file format doesn't make sense without a backing file */
     if (backing_fmt && !backing_file) {
@@ -1466,10 +1467,16 @@ int bdrv_change_backing_file(BlockDriverState *bs,
     }
 
     if (drv->bdrv_change_backing_file != NULL) {
-        return drv->bdrv_change_backing_file(bs, backing_file, backing_fmt);
+        ret = drv->bdrv_change_backing_file(bs, backing_file, backing_fmt);
     } else {
-        return -ENOTSUP;
+        ret = -ENOTSUP;
+    }
+
+    if (ret == 0) {
+        pstrcpy(bs->backing_file, sizeof(bs->backing_file), backing_file ?: "");
+        pstrcpy(bs->backing_format, sizeof(bs->backing_format), backing_fmt ?: "");
     }
+    return ret;
 }
 
 static int bdrv_check_byte_request(BlockDriverState *bs, int64_t offset,

diff --git a/block/stream.c b/block/stream.c
index 6724af2764fa6c9e0183fa810db33c200d9a9d8c..b7e1ad4989183ba37f0c670408ce42eb859cb4f2 100644 (file)
--- a/block/stream.c
+++ b/block/stream.c
@@ -96,17 +96,6 @@ static void close_unused_images(BlockDriverState *top, BlockDriverState *base,
         bdrv_delete(unused);
     }
     top->backing_hd = base;
-
-    pstrcpy(top->backing_file, sizeof(top->backing_file), "");
-    pstrcpy(top->backing_format, sizeof(top->backing_format), "");
-    if (base_id) {
-        pstrcpy(top->backing_file, sizeof(top->backing_file), base_id);
-        if (base->drv) {
-            pstrcpy(top->backing_format, sizeof(top->backing_format),
-                    base->drv->format_name);
-        }
-    }
-
 }
 
 /*