Generalize unset_origin to set_origin

Semantics preserving, so pass None where it is invoked.

Signed-off-by: mulhern <[email protected]>

src/engine/sim_engine/filesystem.rs

@@ -85,9 +85,9 @@ impl SimFilesystem {
         }
     }
 
-    pub fn unset_origin(&mut self) -> bool {
-        let changed = self.origin.is_some();
-        self.origin = None;
+    pub fn set_origin(&mut self, value: Option<FilesystemUuid>) -> bool {
+        let changed = self.origin != value;
+        self.origin = value;
         changed
     }
 

src/engine/sim_engine/pool.rs

@@ -521,7 +521,7 @@ impl Pool for SimPool {
                     // removal.
                     if let Some((_, sn)) = self.filesystems.get_mut_by_uuid(sn_uuid) {
                         assert!(
-                            sn.unset_origin(),
+                            sn.set_origin(None),
                             "A snapshot can only have one origin, so it can be in snapshots.values() only once, so its origin value can be unset only once"
                         );
                         updated_origins.push(sn_uuid);

src/engine/strat_engine/thinpool/filesystem.rs

@@ -450,9 +450,9 @@ impl StratFilesystem {
         self.thin_dev.size()
     }
 
-    pub fn unset_origin(&mut self) -> bool {
-        let changed = self.origin.is_some();
-        self.origin = None;
+    pub fn set_origin(&mut self, value: Option<FilesystemUuid>) -> bool {
+        let changed = self.origin != value;
+        self.origin = value;
         changed
     }
 

src/engine/strat_engine/thinpool/thinpool.rs

@@ -828,7 +828,7 @@ impl<B> ThinPool<B> {
                     // removal.
                     if let Some((_, sn)) = self.get_mut_filesystem_by_uuid(sn_uuid) {
                         assert!(
-                            sn.unset_origin(),
+                            sn.set_origin(None),
                             "A snapshot can only have one origin, so it can be in snapshots.values() only once, so its origin value can be unset only once"
                         );
                         updated_origins.push(sn_uuid);