Re: [PATCH v4 02/28] mm: Add an unlock function for PG_private_2/PG_fscache

[David Howells]

Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:

> So ... a page with both flags cleared should have a refcount of N.
> A page with one or both flags set should have a refcount of N+1.
> ...
> How is a poor filesystem supposed to make that true?  Also btrfs has this
> problem since it uses private_2 for its own purposes.

It's simpler if it's N+2 for both patches set.  Btw, patch 13 adds that - and
possibly that should be merged into an earlier patch.

David