Fix sb_read cache not be freed

Author: RoyWFHuang

dir.c

@@ -60,9 +60,11 @@ static int simplefs_iterate(struct file *dir, struct dir_context *ctx)
                 goto release_bh;
             }
             dblock = (struct simplefs_dir_block *) bh2->b_data;
-            if (dblock->files[0].inode == 0)
+            if (dblock->files[0].inode == 0) {
+                brelse(bh2);
+                bh2 = NULL;
                 break;
-
+            }
             /* Iterate every file in one block */
             for (; fi < SIMPLEFS_FILES_PER_BLOCK; fi++) {
                 f = &dblock->files[fi];

inode.c

@@ -749,8 +749,8 @@ static int simplefs_rename(struct inode *old_dir,
                     break;
                 }
             }
-            if (new_pos < 0)
-                brelse(bh2);
+
+            brelse(bh2);
         }
     }