From 6f750627ca303b962cf2c610b9cd27bae0fc1439 Mon Sep 17 00:00:00 2001
Message-Id: <6f750627ca303b962cf2c610b9cd27bae0fc1439@dist-git>
From: Peter Krempa <pkrempa@redhat.com>
Date: Thu, 23 Nov 2017 19:02:20 +0100
Subject: [PATCH] qemu: snapshot: Disallow snapshot of unsupported shared disks

Creating a snapshot would introduce a possibly unsupported member for
sharing into the backing chain. Add a check to prevent that from
happening.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1511480
(cherry picked from commit 9b2fbfa6f6b535b9f41a7503531d43d86d7a8868)
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
---
 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 aa6a326bb4..620028fe07 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -13952,6 +13952,24 @@ 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)
@@ -14014,6 +14032,9 @@ qemuDomainSnapshotPrepareDiskExternalInactive(virDomainSnapshotDiskDefPtr snapdi
         return -1;
     }
 
+    if (qemuDomainSnapshotPrepareDiskShared(snapdisk, domdisk) < 0)
+        return -1;
+
     return 0;
 }
 
@@ -14073,6 +14094,9 @@ qemuDomainSnapshotPrepareDiskExternalActive(virDomainSnapshotDiskDefPtr snapdisk
         return -1;
     }
 
+    if (qemuDomainSnapshotPrepareDiskShared(snapdisk, domdisk) < 0)
+        return -1;
+
     return 0;
 }
 
-- 
2.15.0