Re: [PATCH v2 2/5] fuse: Create helper function if DIO write needs exclusive lock

[Bernd Schubert <bernd.schubert@fastmail.fm>]

On 2/7/24 14:44, Jingbo Xu wrote:
> 
> 
> On 2/7/24 9:38 PM, Bernd Schubert wrote:
>>
>>
>> On 2/6/24 10:20, Jingbo Xu wrote:
>>>
>>>
>>> On 2/1/24 7:08 AM, Bernd Schubert wrote:
>>>> @@ -1591,10 +1616,10 @@ static ssize_t fuse_direct_write_iter(struct kiocb *iocb, struct iov_iter *from)
>>>>  	else {
>>>>  		inode_lock_shared(inode);
>>>>  
>>>> -		/* A race with truncate might have come up as the decision for
>>>> -		 * the lock type was done without holding the lock, check again.
>>>> +		/*
>>>> +		 * Previous check was without any lock and might have raced.
>>>>  		 */
> 
> 
>>>> -		if (fuse_direct_write_extending_i_size(iocb, from)) {
>>>> +		if (fuse_dio_wr_exclusive_lock(iocb, from)) {
>>> 			^
> 
> I mean, in patch 2/5
> 
>> -		if (fuse_direct_write_extending_i_size(iocb, from)) {
>> +		if (fuse_io_past_eof(iocb, from)) {
> 
> is better, otherwise it's not an equivalent change.

Ah thanks, good catch! Now I see what you mean. Yeah, we can switch to
fuse_io_past_eof() here. And yeah, 3/5 changes it back.
Fortunately there is actually not much harm, as
fuse_dio_wr_exclusive_lock also calls into fuse_io_past_eof.


Thanks,
Bernd