13     syscall::SystemError,
123     ) -> Result<usize, SystemError> {  in read_at()  argument
125             return Err(SystemError::EINVAL);  in read_at()
132             return Err(SystemError::EISDIR);  in read_at()
140             return Err(SystemError::ENOBUFS);  in read_at()
155     ) -> Result<usize, SystemError> {  in write_at()  argument
157             return Err(SystemError::EINVAL);  in write_at()
165             return Err(SystemError::EISDIR);  in write_at()
180     fn poll(&self) -> Result<PollStatus, SystemError> {  in poll()  argument
186             return Err(SystemError::EISDIR);  in poll()
200     fn metadata(&self) -> Result<Metadata, SystemError> {  in metadata()  argument
208     fn set_metadata(&self, metadata: &Metadata) -> Result<(), SystemError> {  in set_metadata()  argument
220     fn resize(&self, len: usize) -> Result<(), SystemError> {  in resize()  argument
226             return Err(SystemError::EINVAL);  in resize()
236     ) -> Result<Arc<dyn IndexNode>, SystemError> {  in create_with_data()  argument
241             return Err(SystemError::ENOTDIR);  in create_with_data()
245             return Err(SystemError::EEXIST);  in create_with_data()
282     fn link(&self, name: &str, other: &Arc<dyn IndexNode>) -> Result<(), SystemError> {  in link()  argument
285             .ok_or(SystemError::EPERM)?;  in link()
291             return Err(SystemError::ENOTDIR);  in link()
296             return Err(SystemError::EISDIR);  in link()
301             return Err(SystemError::EEXIST);  in link()
313     fn unlink(&self, name: &str) -> Result<(), SystemError> {  in unlink()  argument
317             return Err(SystemError::ENOTDIR);  in unlink()
321             return Err(SystemError::ENOTEMPTY);  in unlink()
325         let to_delete = inode.children.get(name).ok_or(SystemError::ENOENT)?;  in unlink()
327             return Err(SystemError::EPERM);  in unlink()
336     fn rmdir(&self, name: &str) -> Result<(), SystemError> {  in rmdir()  argument
340             return Err(SystemError::ENOTDIR);  in rmdir()
343         let to_delete = inode.children.get(name).ok_or(SystemError::ENOENT)?;  in rmdir()
345             return Err(SystemError::ENOTDIR);  in rmdir()
359     ) -> Result<(), SystemError> {  in move_()  argument
373     fn find(&self, name: &str) -> Result<Arc<dyn IndexNode>, SystemError> {  in find()  argument
377             return Err(SystemError::ENOTDIR);  in find()
382                 return Ok(inode.self_ref.upgrade().ok_or(SystemError::ENOENT)?);  in find()
386                 return Ok(inode.parent.upgrade().ok_or(SystemError::ENOENT)?);  in find()
390                 return Ok(inode.children.get(name).ok_or(SystemError::ENOENT)?.clone());  in find()
395     fn get_entry_name(&self, ino: InodeId) -> Result<String, SystemError> {  in get_entry_name()  argument
398             return Err(SystemError::ENOTDIR);  in get_entry_name()
419                     0=>{return Err(SystemError::ENOENT);}  in get_entry_name()
427     fn list(&self) -> Result<Vec<String>, SystemError> {  in list()  argument
430             return Err(SystemError::ENOTDIR);  in list()