[Cluster-devel] [PATCH] gfs2: Clean up gfs2_file_write_iter and fix O_SYNC write handling

[Andreas Gruenbacher]

On Thu, Feb 6, 2020 at 5:34 PM Christoph Hellwig <hch at lst.de> wrote:
> >       if (iocb->ki_flags & IOCB_DIRECT) {
> >               struct address_space *mapping = file->f_mapping;
> > +             ssize_t buffered, ret2;
> >
> > +             ret = gfs2_file_direct_write(iocb, from);
> > +             if (ret < 0 || !iov_iter_count(from))
> >                       goto out_unlock;
> >
> >               current->backing_dev_info = inode_to_bdi(inode);
> > +             buffered = iomap_file_buffered_write(iocb, from, &gfs2_iomap_ops);
> >               current->backing_dev_info = NULL;
> > -             if (unlikely(ret < 0))
> > +             if (unlikely(buffered <= 0))
> >                       goto out_unlock;
> >
> >               /*
> >                * We need to ensure that the page cache pages are written to
> >                * disk and invalidated to preserve the expected O_DIRECT
> > +              * semantics.  If the writeback or invalidate fails, only report
> > +              * the direct I/O range as we don't know if the buffered pages
> > +              * made it to disk.
> >                */
> > +             iocb->ki_pos += buffered;
> > +             iocb->ki_flags |= IOCB_DSYNC;
>
> I think I'd rather add IOCB_DSYNC before calling
> iomap_file_buffered_write, just in case we ever do optimizations for
> synchronous I/O there.

Okay, that shouldn't hurt.

> > +             ret2 = generic_write_sync(iocb, buffered);
> > +             invalidate_mapping_pages(mapping,
> > +                                      (iocb->ki_pos - buffered) >> PAGE_SHIFT,
>
> This adds a line > 80 chars.
>
> Otherwise this looks fine to me, although I'd just put the fix in the
> subject line and just mention the cleanup at the end of the actual
> commit log.

Alright.

Thanks,
Andreas