[PATCH v2] qemu: Revoke access to mirror on failed blockcopy

[Michal Privoznik]

When preparing to do a blockcopy, the mirror image is modified so
that QEMU can access it. For instance, the mirror has seclabels
set, if it is a NVMe disk it is detached from the host and so on.
And usually, the restore is done upon successful finish of the
blockcopy operation. But, if something fails then we need to
explicitly revoke the access to the mirror image (and thus
reattach NVMe disk back to the host).

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1822538

Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
---

diff to v1:
- Fix call of qemuDomainStorageSourceChainAccessRevoke() so that it is
called even if data = crdata = NULL.

 src/qemu/qemu_driver.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 31f199fdef..dfe0adaad8 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -17950,6 +17950,7 @@ qemuDomainBlockCopyCommon(virDomainObjPtr vm,
     virDomainDiskDefPtr disk = NULL;
     int ret = -1;
     bool need_unlink = false;
+    bool need_revoke = false;
     g_autoptr(virQEMUDriverConfig) cfg = virQEMUDriverGetConfig(driver);
     const char *format = NULL;
     bool mirror_reuse = !!(flags & VIR_DOMAIN_BLOCK_COPY_REUSE_EXT);
@@ -18124,6 +18125,7 @@ qemuDomainBlockCopyCommon(virDomainObjPtr vm,
 
     if (qemuDomainStorageSourceChainAccessAllow(driver, vm, mirror) < 0)
         goto endjob;
+    need_revoke = true;
 
     if (blockdev) {
         if (mirror_reuse) {
@@ -18232,14 +18234,17 @@ qemuDomainBlockCopyCommon(virDomainObjPtr vm,
 
  endjob:
     if (ret < 0 &&
-        virDomainObjIsActive(vm) &&
-        (data || crdata)) {
-        qemuDomainObjEnterMonitor(driver, vm);
-        if (data)
-            qemuBlockStorageSourceChainDetach(priv->mon, data);
-        if (crdata)
-            qemuBlockStorageSourceAttachRollback(priv->mon, crdata->srcdata[0]);
-        ignore_value(qemuDomainObjExitMonitor(driver, vm));
+        virDomainObjIsActive(vm)) {
+        if (data || crdata) {
+            qemuDomainObjEnterMonitor(driver, vm);
+            if (data)
+                qemuBlockStorageSourceChainDetach(priv->mon, data);
+            if (crdata)
+                qemuBlockStorageSourceAttachRollback(priv->mon, crdata->srcdata[0]);
+            ignore_value(qemuDomainObjExitMonitor(driver, vm));
+        }
+        if (need_revoke)
+            qemuDomainStorageSourceChainAccessRevoke(driver, vm, mirror);
     }
     if (need_unlink && virStorageFileUnlink(mirror) < 0)
         VIR_WARN("%s", _("unable to remove just-created copy target"));
-- 
2.25.3