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-rw-r--r--qemu-img.c13
1 files changed, 12 insertions, 1 deletions
diff --git a/qemu-img.c b/qemu-img.c
index 585b65640f..2b2a3a86ca 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -3814,6 +3814,8 @@ static int img_rebase(int argc, char **argv)
}
if (prefix_chain_bs) {
+ uint64_t bytes = n;
+
/*
* If cluster wasn't changed since prefix_chain, we don't need
* to take action
@@ -3826,9 +3828,18 @@ static int img_rebase(int argc, char **argv)
strerror(-ret));
goto out;
}
- if (!ret) {
+ if (!ret && n) {
continue;
}
+ if (!n) {
+ /*
+ * If we've reached EOF of the old backing, it means that
+ * offsets beyond the old backing size were read as zeroes.
+ * Now we will need to explicitly zero the cluster in
+ * order to preserve that state after the rebase.
+ */
+ n = bytes;
+ }
}
/*