[libvirt] [PATCH 3/3] qemu: Allow migration with disk cache on

When QEMU supports flushing caches at the end of migration, we can safely allow migration even if disk/driver/@cache is not none nor directsync. Signed-off-by: Jiri Denemark <jdenemar(a)redhat.com&gt; --- src/qemu/qemu_migration.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c index 2bd1a464bf..bd40a8e70d 100644 --- a/src/qemu/qemu_migration.c +++ b/src/qemu/qemu_migration.c @@ -1214,6 +1214,7 @@ qemuMigrationSrcIsAllowed(virQEMUDriverPtr driver, static bool qemuMigrationSrcIsSafe(virDomainDefPtr def, + virQEMUCapsPtr qemuCaps, size_t nmigrate_disks, const char **migrate_disks, unsigned int flags) @@ -1264,6 +1265,11 @@ qemuMigrationSrcIsSafe(virDomainDefPtr def, disk->cachemode == VIR_DOMAIN_DISK_CACHE_DIRECTSYNC) continue; + if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_MIGRATION_FILE_DROP_CACHE)) { + VIR_DEBUG("QEMU supports flushing caches; migration is safe"); + continue; + } + virReportError(VIR_ERR_MIGRATE_UNSAFE, "%s", _("Migration may lead to data corruption if disks" " use cache other than none or directsync")); @@ -1971,7 +1977,8 @@ qemuMigrationSrcBeginPhase(virQEMUDriverPtr driver, goto cleanup; if (!(flags & (VIR_MIGRATE_UNSAFE | VIR_MIGRATE_OFFLINE)) && - !qemuMigrationSrcIsSafe(vm->def, nmigrate_disks, migrate_disks, flags)) + !qemuMigrationSrcIsSafe(vm->def, priv->qemuCaps, + nmigrate_disks, migrate_disks, flags)) goto cleanup; if (flags & VIR_MIGRATE_POSTCOPY && @@ -4583,7 +4590,8 @@ qemuMigrationSrcPerformJob(virQEMUDriverPtr driver, goto endjob; if (!(flags & (VIR_MIGRATE_UNSAFE | VIR_MIGRATE_OFFLINE)) && - !qemuMigrationSrcIsSafe(vm->def, nmigrate_disks, migrate_disks, flags)) + !qemuMigrationSrcIsSafe(vm->def, priv->qemuCaps, + nmigrate_disks, migrate_disks, flags)) goto endjob; qemuMigrationSrcStoreDomainState(vm); -- 2.22.1