[libvirt] [PATCH v3] qemu-migration: Disallow migration of read only disk

Currently Libvirt allows attempts to migrate read only disks. Qemu cannot handle this as read only disks cannot be written to on the destination system. The end result is a cryptic error message and a failed migration. This patch causes migration to fail earlier and provides a meaningful error message stating that migrating read only disks is not supported. Signed-off-by: Corey S. McQuay <csmcquay(a)linux.vnet.ibm.com&gt; Reviewed-by: Jason J. Herne <jjherne(a)linux.vnet.ibm.com&gt; Reviewed-by: Boris Fiuczynski <fiuczy(a)linux.vnet.ibm.com&gt; --- src/qemu/qemu_migration.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c index e451ef6..c8fb7ec 100644 --- a/src/qemu/qemu_migration.c +++ b/src/qemu/qemu_migration.c @@ -1764,6 +1764,12 @@ qemuMigrationStartNBDServer(virQEMUDriverPtr driver, /* check whether disk should be migrated */ if (!qemuMigrateDisk(disk, nmigrate_disks, migrate_disks)) continue; + + if (disk->src->readonly) { + virReportError(VIR_ERR_OPERATION_UNSUPPORTED, + _("Cannot migrate read-only disk %s"), disk->dst); + goto cleanup; + } VIR_FREE(diskAlias); if (!(diskAlias = qemuAliasFromDisk(disk))) -- 2.7.4