The condition modified here is not about potentially filtered children,
but only about COW sources (i.e. traditional backing files).
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
block/io.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/block/io.c b/block/io.c
index dc9891d6ce..097a3861d8 100644
--- a/block/io.c
+++ b/block/io.c
@@ -3308,7 +3308,7 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child,
int64_t offset, bool exact,
Error **errp)
{
BlockDriverState *bs = child->bs;
- BdrvChild *filtered;
+ BdrvChild *filtered, *backing;
BlockDriver *drv = bs->drv;
BdrvTrackedRequest req;
int64_t old_size, new_bytes;
@@ -3361,6 +3361,7 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child,
int64_t offset, bool exact,
}
filtered = bdrv_filter_child(bs);
+ backing = bdrv_cow_child(bs);
/*
* If the image has a backing file that is large enough that it would
@@ -3372,10 +3373,10 @@ int coroutine_fn bdrv_co_truncate(BdrvChild *child,
int64_t offset, bool exact,
* backing file, taking care of keeping things consistent with that
backing
* file is the user's responsibility.
*/
- if (new_bytes && bs->backing) {
+ if (new_bytes && backing) {
int64_t backing_len;
- backing_len = bdrv_getlength(backing_bs(bs));
+ backing_len = bdrv_getlength(backing->bs);
if (backing_len < 0) {
ret = backing_len;
error_setg_errno(errp, -ret, "Could not get backing file size");