Re: [PATCH 3/5] fuse: Allow parallel direct writes for O_DIRECT

[Miklos Szeredi <miklos@szeredi.hu>]

On Mon, 28 Aug 2023 at 16:21, Bernd Schubert <bernd.schubert@fastmail.fm> wrote:
>
>
>
> On 8/28/23 12:42, Miklos Szeredi wrote:
> > On Thu, 24 Aug 2023 at 17:08, Bernd Schubert <bschubert@ddn.com> wrote:
> >>
> >> Take a shared lock in fuse_cache_write_iter.
> >>
> >> Cc: Hao Xu <howeyxu@tencent.com>
> >> Cc: Miklos Szeredi <miklos@szeredi.hu>
> >> Cc: Dharmendra Singh <dsingh@ddn.com>
> >> Cc: linux-fsdevel@vger.kernel.org
> >> Signed-off-by: Bernd Schubert <bschubert@ddn.com>
> >> ---
> >>   fs/fuse/file.c | 21 ++++++++++++++++-----
> >>   1 file changed, 16 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/fs/fuse/file.c b/fs/fuse/file.c
> >> index a16f9b6888de..905ce3bb0047 100644
> >> --- a/fs/fuse/file.c
> >> +++ b/fs/fuse/file.c
> >> @@ -1314,9 +1314,10 @@ static bool fuse_dio_wr_exclusive_lock(struct kiocb *iocb, struct iov_iter *from
> >>          struct file *file = iocb->ki_filp;
> >>          struct fuse_file *ff = file->private_data;
> >>
> >> -       return  !(ff->open_flags & FOPEN_PARALLEL_DIRECT_WRITES) ||
> >> -               iocb->ki_flags & IOCB_APPEND ||
> >> -               fuse_direct_write_extending_i_size(iocb, from);
> >> +       return ((!(iocb->ki_flags & IOCB_DIRECT)) ||
> >> +               (!(ff->open_flags & FOPEN_PARALLEL_DIRECT_WRITES)) ||
> >
> > Why the extra parenthesis around the negation in the above two conditions?
> >
> > So this condition will always be true at this point when called from
> > fuse_cache_write_iter()?  If so, you need to explain in the commit
> > message why are you doing this at this point (e.g. future patches
> > depend on this).
>
> Oh, thanks for spotting, the double parenthesis were accidentally.
> Although I don't think it would have an effect, it just results in
>
> return ((!(condition1)) || ...
>
> I.e. does not change the condition itself?

It doesn't change the condition, but degrades readability.

Thanks,
Miklos