Re: [PATCH 2/2] btrfs: add ioctl for directly writing compressed data

Omar Sandoval
2019-09-19T07:59:54Z

On Thu, Sep 19, 2019 at 09:46:31AM +0200, Nikolay Borisov wrote:
>
>
> On 19.09.19 г. 9:14 ч., Omar Sandoval wrote:
> > On Thu, Sep 05, 2019 at 01:33:56PM +0300, Nikolay Borisov wrote:
>
> <snip>
>
> >>
> >> Won't btrfs_lock_and_flush_ordered_range suffice here? Perhaps call that
> >> function + invalidate_inode_pages2_range ?
> >
> > No, btrfs_lock_and_flush_ordered_range() doesn't write out dirty pages,
> > so it's not sufficient here.
>
> But it does - it calls btrfs_start_ordered_extent which calls
> filemap_fdatawrite_range.

It only calls that for ranges which already have an ordered extent,
which we don't create until we're writing the dirty pages out (take a
look at where we call btrfs_add_ordered_extent()).