Re: [PATCH] cifs: remove the retry in cifs_poxis_lock_set

[yangerkun <yangerkun@huawei.com>]

在 2020/7/1 6:34, NeilBrown 写道:
> On Tue, Jun 30 2020, yangerkun wrote:
> 
>> Ping...
>>
>> 在 2020/6/24 15:10, yangerkun 写道:
>>> The caller of cifs_posix_lock_set will do retry(like
>>> fcntl_setlk64->do_lock_file_wait) if we will wait for any file_lock.
>>> So the retry in cifs_poxis_lock_set seems duplicated, remove it to
>>> make a cleanup.
> 
> If cifs_posix_try_lock() returns FILE_LOCK_DEFERRED (which it might
> after your patch), then cifs_setlk() will check the return value:
> 
> 		if (!rc || rc < 0)
> 			return rc;
> 
> These tests will fail (as FILE_LOCK_DEFERRED is 1) and so it will
> continue on as though the lock was granted.
> 
> So I think your patch is wrong.
> However I think your goal is correct.  cifs shouldn't be waiting.
> No other filesystem waits when it gets FILE_LOCK_DEFERRED.
> 
> So maybe try to fix up your patch.

Yes, we should check FILE_LOCK_DEFERRED in cifs_setlk after this patch.
Also we may change 'int rc = 1;' exists in cifs_posix_lock_set since
FILE_LOCK_DEFERRED equals to 1.

I will send a v2 and thanks a lot for your review!

Thanks,
Kun.

> Thanks,
> NeilBrown
> 
> 
>>>
>>> Signed-off-by: yangerkun <yangerkun@huawei.com>
>>> ---
>>>    fs/cifs/file.c | 8 --------
>>>    1 file changed, 8 deletions(-)
>>>
>>> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
>>> index 9b0f8f33f832..2c9c24b1805d 100644
>>> --- a/fs/cifs/file.c
>>> +++ b/fs/cifs/file.c
>>> @@ -1162,7 +1162,6 @@ cifs_posix_lock_set(struct file *file, struct file_lock *flock)
>>>    	if ((flock->fl_flags & FL_POSIX) == 0)
>>>    		return rc;
>>>    
>>> -try_again:
>>>    	cifs_down_write(&cinode->lock_sem);
>>>    	if (!cinode->can_cache_brlcks) {
>>>    		up_write(&cinode->lock_sem);
>>> @@ -1171,13 +1170,6 @@ cifs_posix_lock_set(struct file *file, struct file_lock *flock)
>>>    
>>>    	rc = posix_lock_file(file, flock, NULL);
>>>    	up_write(&cinode->lock_sem);
>>> -	if (rc == FILE_LOCK_DEFERRED) {
>>> -		rc = wait_event_interruptible(flock->fl_wait,
>>> -					list_empty(&flock->fl_blocked_member));
>>> -		if (!rc)
>>> -			goto try_again;
>>> -		locks_delete_block(flock);
>>> -	}
>>>    	return rc;
>>>    }
>>>    
>>>