engine: sync only own device before snapshot

If a global sync is performed, no flush command arrive to spdk.
Instead, if for every volume a sync over the corresponding
/dev/nvmeXnY is performed, the flush command is correctly
received by spdk_tgt.

Longhorn 7559

Signed-off-by: Damiano Cipriani <damiano.cipriani@suse.com>

pkg/spdk/engine.go

@@ -1097,8 +1097,7 @@ func (e *Engine) snapshotOperation(spdkClient *spdkclient.Client, inputSnapshotN
 				e.log.WithError(err).Errorf("WARNING: failed to get the executor for snapshot op %v with snapshot %s, will skip the sync and continue", snapshotOp, inputSnapshotName)
 			} else {
 				e.log.Infof("Requesting system sync %v before snapshot", devicePath)
-				// TODO: only sync the device path rather than all filesystems
-				if _, err := ne.Execute(nil, "sync", []string{}, SyncTimeout); err != nil {
+				if _, err := ne.Execute(nil, "sync", []string{devicePath}, SyncTimeout); err != nil {
 					// sync should never fail though, so it more like due to the nsenter
 					e.log.WithError(err).Errorf("WARNING: failed to sync for snapshot op %v with snapshot %s, will skip the sync and continue", snapshotOp, inputSnapshotName)
 				}