[libvirt] [PATCH 08/11] qemu: snapshot: Disallow snapshot of unsupported shared disks

[Peter Krempa]

Snapshots introduce a new layer into the backing chain, so we need to
make sure that we don't use format which does not support being shared.

This effectively disables snapshots on <shareable/> disks since only raw
format is currently supported.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1511480
---
 src/qemu/qemu_driver.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index f907ede16..f7984a87d 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -13944,6 +13944,24 @@ qemuDomainSnapshotCreateActiveInternal(virConnectPtr conn,
 }


+static int
+qemuDomainSnapshotPrepareDiskShared(virDomainSnapshotDiskDefPtr snapdisk,
+                                    virDomainDiskDefPtr domdisk)
+{
+    if (!domdisk->src->shared || domdisk->src->readonly)
+        return 0;
+
+    if (!qemuBlockStorageSourceSupportsConcurrentAccess(snapdisk->src)) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("shared access for disk '%s' requires use of "
+                         "supported storage format"), domdisk->dst);
+        return -1;
+    }
+
+    return 0;
+}
+
+
 static int
 qemuDomainSnapshotPrepareDiskExternalInactive(virDomainSnapshotDiskDefPtr snapdisk,
                                               virDomainDiskDefPtr domdisk)
@@ -14006,6 +14024,9 @@ qemuDomainSnapshotPrepareDiskExternalInactive(virDomainSnapshotDiskDefPtr snapdi
         return -1;
     }

+    if (qemuDomainSnapshotPrepareDiskShared(snapdisk, domdisk) < 0)
+        return -1;
+
     return 0;
 }

@@ -14065,6 +14086,9 @@ qemuDomainSnapshotPrepareDiskExternalActive(virDomainSnapshotDiskDefPtr snapdisk
         return -1;
     }

+    if (qemuDomainSnapshotPrepareDiskShared(snapdisk, domdisk) < 0)
+        return -1;
+
     return 0;
 }

-- 
2.14.3