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-rw-r--r--block.c29
-rw-r--r--tests/unit/test-bdrv-drain.c1
-rw-r--r--tests/unit/test-bdrv-graph-mod.c1
3 files changed, 17 insertions, 14 deletions
diff --git a/block.c b/block.c
index d047cae43c..0a73335380 100644
--- a/block.c
+++ b/block.c
@@ -3152,6 +3152,14 @@ static int bdrv_set_file_or_backing_noperm(BlockDriverState *parent_bs,
return -EPERM;
}
+ if (is_backing && !parent_bs->drv->is_filter &&
+ !parent_bs->drv->supports_backing)
+ {
+ error_setg(errp, "Driver '%s' of node '%s' does not support backing "
+ "files", parent_bs->drv->format_name, parent_bs->node_name);
+ return -EINVAL;
+ }
+
if (parent_bs->drv->is_filter) {
role = BDRV_CHILD_FILTERED | BDRV_CHILD_PRIMARY;
} else if (is_backing) {
@@ -4278,20 +4286,13 @@ static int bdrv_reopen_parse_backing(BDRVReopenState *reopen_state,
}
}
- /*
- * Ensure that @bs can really handle backing files, because we are
- * about to give it one (or swap the existing one)
- */
- if (bs->drv->is_filter) {
- /* Filters always have a file or a backing child */
- if (!bs->backing) {
- error_setg(errp, "'%s' is a %s filter node that does not support a "
- "backing child", bs->node_name, bs->drv->format_name);
- return -EINVAL;
- }
- } else if (!bs->drv->supports_backing) {
- error_setg(errp, "Driver '%s' of node '%s' does not support backing "
- "files", bs->drv->format_name, bs->node_name);
+ if (bs->drv->is_filter && !bs->backing) {
+ /*
+ * Filters always have a file or a backing child, so we are trying to
+ * change wrong child
+ */
+ error_setg(errp, "'%s' is a %s filter node that does not support a "
+ "backing child", bs->node_name, bs->drv->format_name);
return -EINVAL;
}
diff --git a/tests/unit/test-bdrv-drain.c b/tests/unit/test-bdrv-drain.c
index 892f7f47d8..ce071b5fc5 100644
--- a/tests/unit/test-bdrv-drain.c
+++ b/tests/unit/test-bdrv-drain.c
@@ -95,6 +95,7 @@ static int bdrv_test_change_backing_file(BlockDriverState *bs,
static BlockDriver bdrv_test = {
.format_name = "test",
.instance_size = sizeof(BDRVTestState),
+ .supports_backing = true,
.bdrv_close = bdrv_test_close,
.bdrv_co_preadv = bdrv_test_co_preadv,
diff --git a/tests/unit/test-bdrv-graph-mod.c b/tests/unit/test-bdrv-graph-mod.c
index 88f25c0cdb..a6e3bb79be 100644
--- a/tests/unit/test-bdrv-graph-mod.c
+++ b/tests/unit/test-bdrv-graph-mod.c
@@ -41,6 +41,7 @@ static void no_perm_default_perms(BlockDriverState *bs, BdrvChild *c,
static BlockDriver bdrv_no_perm = {
.format_name = "no-perm",
+ .supports_backing = true,
.bdrv_child_perm = no_perm_default_perms,
};