Unlock mutexes on failed up/downgrade

Signed-off-by: kim (grufwub) <grufwub@gmail.com>

core/filesystem.go

@@ -307,16 +307,18 @@ func (fs *FileSystemObject) FetchFile(client *Client, fd *os.File, stat os.FileI
 			return err
 		}
 
-		// Try upgrade our lock, else error out
+		// Try upgrade our lock, else error out (have to remember to unlock!!)
 		if !fs.UpgradeLock() {
+			fs.Unlock()
 			return NewError(MutexUpgradeErr)
 		}
 
 		// Put file in cache
 		fs.cache.Put(p.Absolute(), f)
 
-		// Try downgrade our lock, else error out
+		// Try downgrade our lock, else error out (have to remember to runlock!!)
 		if !fs.DowngradeLock() {
+			fs.RUnlock()
 			return NewError(MutexDowngradeErr)
 		}
 
@@ -328,8 +330,9 @@ func (fs *FileSystemObject) FetchFile(client *Client, fd *os.File, stat os.FileI
 
 		// Check for file freshness
 		if !f.IsFresh() {
-			// Try upgrade file lock, else error out
+			// Try upgrade file lock, else error out (have to remember to unlock!!)
 			if !f.UpgradeLock() {
+				f.Unlock()
 				return NewError(MutexUpgradeErr)
 			}
 
@@ -341,8 +344,9 @@ func (fs *FileSystemObject) FetchFile(client *Client, fd *os.File, stat os.FileI
 				return err
 			}
 
-			// Try downgrade file lock, else error out
+			// Try downgrade file lock, else error out (have to remember to runlock!!)
 			if !f.DowngradeLock() {
+				f.RUnlock()
 				return NewError(MutexDowngradeErr)
 			}
 		}