[libvirt] [PATCHv7.5 9/9] blockjob: relabel entire existing chain

[Eric Blake]

When using block copy to pivot over to a new chain, the backing files
for the new chain might still need labeling (particularly if the user
passes --reuse-ext with a relative backing file name).  Relabeling a
file that is already labeled won't hurt, so this just labels the entire
chain at the point of the pivot.

https://bugzilla.redhat.com/show_bug.cgi?id=856247

* src/qemu/qemu_driver.c (qemuDomainBlockPivot): Relabel chain before
asking qemu to pivot.
---

Diff from v7: do the recursive relabel at pivot time rather than
initial copy time, since we intentionally permit the copy operation
to start prior to copying the backing chain, to allow for some
parallelism in the overall storage migration operation.

I still plan on squashing this into patch 8/9; but am posting this
separately for ease of backporting to RHEL 6.3.

 src/qemu/qemu_driver.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 32cd9ad..4049fba 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -12615,6 +12615,7 @@ qemuDomainBlockPivot(virConnectPtr conn,
     virDomainBlockJobInfo info;
     bool reopen = qemuCapsGet(priv->caps, QEMU_CAPS_DRIVE_REOPEN);
     bool resume = false;
+    virCgroupPtr cgroup = NULL;

     /* Probe the status, if needed.  */
     if (!disk->mirroring) {
@@ -12662,6 +12663,23 @@ qemuDomainBlockPivot(virConnectPtr conn,
         }
     }

+    /* We previously labeled only the top-level image; but if the
+     * image includes a relative backing file, the pivot may result in
+     * qemu needing to open the entire backing chain, so we need to
+     * label the entire chain.  This action is safe even if the
+     * backing chain has already been labeled.  */
+    if (qemuCgroupControllerActive(driver, VIR_CGROUP_CONTROLLER_DEVICES) &&
+        virCgroupForDomain(driver->cgroup, vm->def->name, &cgroup, 0)) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Unable to find cgroup for %s"),
+                       vm->def->name);
+        goto cleanup;
+    }
+    if ((cgroup && qemuSetupDiskCgroup(driver, vm, cgroup, disk) < 0) ||
+        virSecurityManagerSetImageLabel(driver->securityManager, vm->def,
+                                        disk) < 0)
+        goto cleanup;
+
     /* Attempt the pivot.  */
     qemuDomainObjEnterMonitorWithDriver(driver, vm);
     ret = qemuMonitorDrivePivot(priv->mon, device, disk->mirror,
@@ -12702,6 +12720,8 @@ qemuDomainBlockPivot(virConnectPtr conn,
     }

 cleanup:
+    if (cgroup)
+        virCgroupFree(&cgroup);
     if (resume && virDomainObjIsActive(vm) &&
         qemuProcessStartCPUs(driver, vm, conn,
                              VIR_DOMAIN_RUNNING_UNPAUSED,
-- 
1.7.11.4