refining vfs

kernel/syscall.c

@@ -56,7 +56,7 @@ static int32_t sys_read(int fd, void* buf, size_t count) {
 }
 
 static int32_t sys_open(const char* filename, int flags) {
-    return open(filename, flags);
+    return vfs_open(filename, flags);
 }
 
 static int32_t sys_close(int fd) {