Re: [GIT PULL] dtype handling cleanup for v4.21-rc1

[Matthew Wilcox <willy@infradead.org>]

On Wed, Jan 16, 2019 at 05:36:06AM +1200, Linus Torvalds wrote:
> On Tue, Jan 15, 2019 at 9:24 PM Jan Kara <jack@suse.cz> wrote:
> >
> > What has happened to this pull request? It may be too late for this to be
> > merged now but I'd like to understand why it was not merged or rejected...
> 
> Sorry, initially I left if for later consideration after rc1, and then
> I just forgot about it.
> 
> I didn't see much point to the cleanup when it actually adds lots of
> lines and no actual advantage. The whole dentry type translation
> really is fs-specific and it might just happen to be shared. But why
> share it if it only adds complexity and unnecessary abstraction?

The ext2/ext4 patches don't show much improvement.  The other patches show
more:

 fs/nilfs2/dir.c                    | 52 ++++++++++--------------------
 include/uapi/linux/nilfs2_ondisk.h |  1 +
 2 files changed, 18 insertions(+), 35 deletions(-)

(for example).

UFS ends up benefiting the most.  You can see the whole diffstat here:

https://lore.kernel.org/lkml/20181023201952.GA15676@pathfinder/

We'd see a lot more improvement in line count if Philip weren't quite
so paranoid about checking FOOFS_FT_* == FT_* at build time; eg for btrfs:

https://lore.kernel.org/lkml/20181023211728.GA16584@pathfinder/