Re: [PATCH 2/2] fs: Do not update nr_thps for mappings which support THPs

[Christoph Hellwig]

On Wed, Sep 16, 2020 at 04:27:17AM +0100, Matthew Wilcox (Oracle) wrote:
> The nr_thps counter is to support THPs in the page cache when the
> filesystem doesn't understand THPs.  Eventually it will be removed, but
> we should still support filesystems which do not understand THPs yet.
> Move the nr_thp manipulation functions to filemap.h since they're
> page-cache specific.

Honestly I don't think we should support the read-only THP crap.  We
should in fact never have merged that bandaid to start with given that
you did good progress on the real thing.