From 9911807f7cf94ab328916fd9f00f20cc09a6455a Mon Sep 17 00:00:00 2001
Message-Id: <9911807f7cf94ab328916fd9f00f20cc09a6455a@dist-git>
From: Peter Krempa <pkrempa@redhat.com>
Date: Thu, 23 Nov 2017 19:02:21 +0100
Subject: [PATCH] qemu: Disallow pivot of shared disks to unsupported storage

Pivoting to a unsupported storage type might break the assumption that
shared disks will not corrupt metadata.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1511480
(cherry picked from commit 2b41c86294786c07f53afa633fe3dce703debc3c)
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
---
 src/qemu/qemu_driver.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 620028fe07..d0d29747cf 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -16509,6 +16509,16 @@ qemuDomainBlockPivot(virQEMUDriverPtr driver,
         goto cleanup;
     }
 
+    /* When pivoting to a shareable disk we need to make sure that the disk can
+     * be safely shared, since block copy might have changed the format. */
+    if (disk->src->shared && !disk->src->readonly &&
+        !qemuBlockStorageSourceSupportsConcurrentAccess(disk->mirror)) {
+        virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
+                       _("can't pivot a shared disk to a storage volume not "
+                         "supporting sharing"));
+        goto cleanup;
+    }
+
     /* For active commit, the mirror is part of the already labeled
      * chain.  For blockcopy, we previously labeled only the top-level
      * image; but if the user is reusing an external image that
-- 
2.15.0