On Mon, Feb 26, 2018 at 11:05:49AM +0100, Michal Privoznik wrote:
https://bugzilla.redhat.com/show_bug.cgi?id=1494454
If a domain disk is stored on local filesystem (e.g. ext4) but is not being migrated it is very likely that domain is not able to run on destination. Regardless of share/cache mode.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com> --- src/qemu/qemu_migration.c | 28 ++++++++++++++++++---------- 1 file changed, 18 insertions(+), 10 deletions(-)
diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c index b22a327b5..e98b1e4ce 100644 --- a/src/qemu/qemu_migration.c +++ b/src/qemu/qemu_migration.c @@ -1215,25 +1215,26 @@ qemuMigrationSrcIsSafe(virDomainDefPtr def, virDomainDiskDefPtr disk = def->disks[i]; const char *src = virDomainDiskGetSource(disk);
- /* Our code elsewhere guarantees shared disks are either readonly (in - * which case cache mode doesn't matter) or used with cache=none or used with cache=directsync */ + /* Disks without any source (i.e. floppies and CD-ROMs) + * OR readonly are safe. */ if (virStorageSourceIsEmpty(disk->src) || - disk->src->readonly || - disk->src->shared || - disk->cachemode == VIR_DOMAIN_DISK_CACHE_DISABLE || - disk->cachemode == VIR_DOMAIN_DISK_CACHE_DIRECTSYNC) + disk->src->readonly) continue;
- /* disks which are migrated by qemu are safe too */ + /* Disks which are migrated by qemu are safe too. */ if (storagemigration && qemuMigrationAnyCopyDisk(disk, nmigrate_disks, migrate_disks)) continue;
+ /* However, disks on local FS (e.g. ext4) are not safe. */ if (virDomainDiskGetType(disk) == VIR_STORAGE_TYPE_FILE) { - if ((rc = virFileIsSharedFS(src)) < 0) + if ((rc = virFileIsSharedFS(src)) < 0) { return false; - else if (rc == 0) - continue; + } else if (rc == 0) { + virReportError(VIR_ERR_MIGRATE_UNSAFE, "%s", + _("Migration without shared storage is unsafe")); + return false; + } if ((rc = virStorageFileIsClusterFS(src)) < 0) return false; else if (rc == 1) @@ -1243,6 +1244,13 @@ qemuMigrationSrcIsSafe(virDomainDefPtr def, continue; }
+ /* Our code elsewhere guarantees shared disks are either readonly (in + * which case cache mode doesn't matter) or used with cache=none or used with cache=directsync */ + if (disk->src->shared || + disk->cachemode == VIR_DOMAIN_DISK_CACHE_DISABLE || + disk->cachemode == VIR_DOMAIN_DISK_CACHE_DIRECTSYNC) + continue; + virReportError(VIR_ERR_MIGRATE_UNSAFE, "%s", _("Migration may lead to data corruption if disks" " use cache != none or cache != directsync"));
A little hard to follow but the key difference is that the old code would immediately return saying it is "safe" if the cache mode was set to a reasonable value, and not get to checking whether disk is local or not. We've essentially reversed that so we detect unsafe scenarios first, and then later check safe options. Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|