linux-kernel - Re: [PATCH] fuse: invalidate the page cache after direct write

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Message-ID: <1fa83cdf-010b-4e95-9dcc-0e9f5cefa68b@linux.alibaba.com>
Date: Fri, 9 Jan 2026 10:21:31 +0800
From: Jingbo Xu <jefflexu@...ux.alibaba.com>
To: Bernd Schubert <bernd@...ernd.com>, miklos@...redi.hu,
 linux-fsdevel@...r.kernel.org, bschubert@....com
Cc: linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fuse: invalidate the page cache after direct write

Hi Bernd,

On 1/9/26 10:13 AM, Jingbo Xu wrote:
> 
> 
> On 1/9/26 12:16 AM, Bernd Schubert wrote:
>>
>> The side effect should only come without FOPEN_DIRECT_IO. Could you add
>> this diff to avoid it?
>>
>> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
>> index d6ae3b4652f8..c04296316a82 100644
>> --- a/fs/fuse/file.c
>> +++ b/fs/fuse/file.c
>> @@ -1177,7 +1177,13 @@ static ssize_t fuse_send_write(struct fuse_io_args *ia, loff_t pos,
>>         written = ia->write.out.size;
>>         if (!err && written > count)
>>                 err = -EIO;
>> -       if (!err && written && mapping->nrpages) {
>> +
>> +       /*
>> +        * without FOPEN_DIRECT_IO generic_file_direct_write() does the
>> +        * invalidation for us
>> +        */
>> +       if (!err && written && mapping->nrpages &&
>> +           (ff->open_flags & FOPEN_DIRECT_IO)) {
>>                 /*
>>                  * As in generic_file_direct_write(), invalidate after the
>>                  * write, to invalidate read-ahead cache that may have competed
>>
> 
> Actually I think it's more complicated:
> 
> ```
> /*
>  * without FOPEN_DIRECT_IO generic_file_direct_write() does the
>  * invalidation for synchronous write.
>  */
> if (!err && written && mapping->nrpages &&
>     ((ff->open_flags & FOPEN_DIRECT_IO) || !io->blocking)) {
> ```
> 
> I will send v2 soon if you feel good about the above diff.
> 

Sorry I just realized that the invalidation for asynchronous write will
be done in fuse_aio_complete() of v1 patch.

I will apply the diff you suggested and send v2 soon.

-- 
Thanks,
Jingbo