vfs: vfscache: Fix renaming of items while they are being uploaded

Previous to the fix, if an item was being uploaded and it was renamed,
the upload would fail with missing checksum errors.

This change cancels any uploads in progress if the file is renamed.

vfs/vfscache/item.go

@@ -1018,36 +1018,35 @@ func (item *Item) Sync() (err error) {
 
 // rename the item
 func (item *Item) rename(name string, newName string, newObj fs.Object) (err error) {
-	var downloaders *downloaders.Downloaders
-	// close downloader with mutex unlocked
-	defer func() {
-		if downloaders != nil {
-			_ = downloaders.Close(nil)
-		}
-	}()
-
 	item.mu.Lock()
-	defer item.mu.Unlock()
 
 	// stop downloader
-	downloaders = item.downloaders
+	downloaders := item.downloaders
 	item.downloaders = nil
 
+	// id for writeback cancel
+	id := item.writeBackID
+
 	// Set internal state
 	item.name = newName
 	item.o = newObj
 
 	// Rename cache file if it exists
 	err = rename(item.c.toOSPath(name), item.c.toOSPath(newName)) // No locking in Cache
-	if err != nil {
-		return err
-	}
 
 	// Rename meta file if it exists
-	err = rename(item.c.toOSPathMeta(name), item.c.toOSPathMeta(newName)) // No locking in Cache
-	if err != nil {
-		return err
+	err2 := rename(item.c.toOSPathMeta(name), item.c.toOSPathMeta(newName)) // No locking in Cache
+	if err2 != nil {
+		err = err2
 	}
 
-	return nil
+	item.mu.Unlock()
+
+	// close downloader and cancel writebacks with mutex unlocked
+	if downloaders != nil {
+		_ = downloaders.Close(nil)
+	}
+	item.c.writeback.Rename(id, newName)
+
+	return err
 }