qemu: Shared or readonly disks are always safe wrt migration

No matter what cache mode is used, readonly disks are always safe wrt
migration. Shared disks are required to be readonly or to disable
host-side cache, which makes them safe as well.

diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
index 84037e4eafc5d2f1e5affb1fc8f46c2528c665f5..5c4297c3b73c622267c0645c44fe3b7255d2c45d 100644 (file)
--- a/src/qemu/qemu_migration.c
+++ b/src/qemu/qemu_migration.c
@@ -828,10 +828,12 @@ qemuMigrationIsSafe(virDomainDefPtr def)
     for (i = 0 ; i < def->ndisks ; i++) {
         virDomainDiskDefPtr disk = def->disks[i];
 
-        /* shared && !readonly implies cache=none */
+        /* Our code elsewhere guarantees shared disks are either readonly (in
+         * which case cache mode doesn't matter) or used with cache=none */
         if (disk->src &&
-            disk->cachemode != VIR_DOMAIN_DISK_CACHE_DISABLE &&
-            (disk->cachemode || !disk->shared || disk->readonly)) {
+            !disk->shared &&
+            !disk->readonly &&
+            disk->cachemode != VIR_DOMAIN_DISK_CACHE_DISABLE) {
             int cfs;
             if ((cfs = virStorageFileIsClusterFS(disk->src)) == 1)
                 continue;