'qemuDomainPrepareDiskSourceData' propagates 'detect_zeroes' only for
the disk source image, but the mirror destination has the ambition to
replace the disk source when the job is finished, so we need to
propagate the 'detect_zeroes' setting also in that case.
Unfortunately it would become very hairy to either set 'disk->mirror'
sooner or propagate that we want this done into
'qemuDomainPrepareDiskSourceData', so the most straightforward solution
is to do the propagation inside 'qemuDomainBlockCopyCommon'.
Closes: https://gitlab.com/libvirt/libvirt/-/issues/277
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
---
src/qemu/qemu_driver.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index e417d358cd..4fc998cde5 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -14977,6 +14977,14 @@ qemuDomainBlockCopyCommon(virDomainObj *vm,
if (qemuDomainPrepareStorageSourceBlockdev(disk, n, priv, cfg) < 0)
goto endjob;
}
+
+ /* 'qemuDomainPrepareStorageSourceBlockdev' calls
+ * 'qemuDomainPrepareDiskSourceData' which propagates 'detect_zeroes'
+ * into the topmost virStorage source of the disk chain.
+ * Since 'mirror' has the ambition to replace it we need to propagate
+ * it into the mirror too. We do it directly as otherwise we'd need
+ * to modify all callers of 'qemuDomainPrepareStorageSourceBlockdev' */
+ mirror->detect_zeroes = disk->detect_zeroes;
}
/* If reusing an external image that includes a backing file but the user
--
2.35.1