[libvirt] [PATCH 02/12] qemu: Fix logic in qemuDomainBlockCopyCommonValidateUserMirrorBackingStore
Allow reusing original backing chain when doing a shallow copy without
reuse of external image. The existing logic didn't allow it but it will
be possible. Also add a note to explain that logic.
Signed-off-by: Peter Krempa <pkrempa(a)redhat.com>
---
src/qemu/qemu_driver.c | 29 +++++++++++++----------------
1 file changed, 13 insertions(+), 16 deletions(-)
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index ff83d1c024..3e0aa1b90f 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -18263,19 +18263,23 @@
qemuDomainBlockCopyCommonValidateUserMirrorBackingStore(virStorageSourcePtr mirr
{
/* note that if original disk does not have backing chain, shallow is cleared */
bool shallow = flags & VIR_DOMAIN_BLOCK_COPY_SHALLOW;
- bool reuse = flags & VIR_DOMAIN_BLOCK_COPY_REUSE_EXT;
- if (!mirror->backingStore) {
- /* deep copy won't need backing store so we can terminate it */
- if (!shallow &&
+ if (!virStorageSourceHasBacking(mirror)) {
+ /* for deep copy there won't be backing chain so we can terminate it */
+ if (!mirror->backingStore &&
+ !shallow &&
!(mirror->backingStore = virStorageSourceNew()))
return -1;
- return 0;
- }
-
- /* validate user provided backing store */
- if (virStorageSourceHasBacking(mirror)) {
+ /* When reusing an external image we document that the user must ensure
+ * that the <mirror> image must expose data as the original image did
+ * either by providing correct chain or prepopulating the image. This
+ * means we can't validate this any more regardless of whether shallow
+ * copy is requested.
+ *
+ * For a copy when we are not reusing external image requesting shallow
+ * is okay and will inherit the original backing chain */
+ } else {
if (!blockdev) {
virReportError(VIR_ERR_INVALID_ARG, "%s",
_("backingStore of mirror target is not supported by this
qemu"));
@@ -18287,13 +18291,6 @@
qemuDomainBlockCopyCommonValidateUserMirrorBackingStore(virStorageSourcePtr mirr
_("backingStore of mirror without
VIR_DOMAIN_BLOCK_COPY_SHALLOW doesn't make sense"));
return -1;
}
- } else {
- /* shallow copy without reuse requires some kind of backing data */
- if (!reuse && shallow) {
- virReportError(VIR_ERR_INVALID_ARG, "%s",
- _("VIR_DOMAIN_BLOCK_COPY_SHALLOW implies backing chain
for mirror"));
- return -1;
- }
}
return 0;
--
2.21.0