From 73e10ded33a1cfc0c72404aaedc493e9813b6239 Mon Sep 17 00:00:00 2001 From: David Howells Date: Mon, 10 Feb 2020 10:00:21 +0000 Subject: mm: Add set/end/wait functions for PG_private_2 Add three functions to manipulate PG_private_2: (*) set_page_private_2() - Set the flag and take an appropriate reference on the flagged page. (*) end_page_private_2() - Clear the flag, drop the reference and wake up any waiters, somewhat analogously with end_page_writeback(). (*) wait_on_page_private_2() - Wait for the flag to be cleared. Wrappers will need to be placed in the netfs lib header in the patch that adds that. [This implements a suggestion by Linus[1] to not mix the terminology of PG_private_2 and PG_fscache in the mm core function] Changes: v7: - Use compound_head() in all the functions to make them THP safe[6]. v5: - Add set and end functions, calling the end function end rather than unlock[3]. - Keep a ref on the page when PG_private_2 is set[4][5]. v4: - Remove extern from the declaration[2]. Suggested-by: Linus Torvalds Signed-off-by: David Howells Reviewed-by: Matthew Wilcox (Oracle) Tested-by: Jeff Layton Tested-by: Dave Wysochanski Tested-By: Marc Dionne cc: Alexander Viro cc: Christoph Hellwig cc: linux-mm@kvack.org cc: linux-cachefs@redhat.com cc: linux-afs@lists.infradead.org cc: linux-nfs@vger.kernel.org cc: linux-cifs@vger.kernel.org cc: ceph-devel@vger.kernel.org cc: v9fs-developer@lists.sourceforge.net cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/1330473.1612974547@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/CAHk-=wjgA-74ddehziVk=XAEMTKswPu1Yw4uaro1R3ibs27ztw@mail.gmail.com/ [1] Link: https://lore.kernel.org/r/20210216102659.GA27714@lst.de/ [2] Link: https://lore.kernel.org/r/161340387944.1303470.7944159520278177652.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/161539528910.286939.1252328699383291173.stgit@warthog.procyon.org.uk # v4 Link: https://lore.kernel.org/r/20210321105309.GG3420@casper.infradead.org [3] Link: https://lore.kernel.org/r/CAHk-=wh+2gbF7XEjYc=HV9w_2uVzVf7vs60BPz0gFA=+pUm3ww@mail.gmail.com/ [4] Link: https://lore.kernel.org/r/CAHk-=wjSGsRj7xwhSMQ6dAQiz53xA39pOG+XA_WeTgwBBu4uqg@mail.gmail.com/ [5] Link: https://lore.kernel.org/r/20210408145057.GN2531743@casper.infradead.org/ [6] Link: https://lore.kernel.org/r/161653788200.2770958.9517755716374927208.stgit@warthog.procyon.org.uk/ # v5 Link: https://lore.kernel.org/r/161789066013.6155.9816857201817288382.stgit@warthog.procyon.org.uk/ # v6 --- include/linux/pagemap.h | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'include/linux') diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 8c9947fd62f3..bb4433c98d02 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -688,6 +688,26 @@ void wait_for_stable_page(struct page *page); void page_endio(struct page *page, bool is_write, int err); +/** + * set_page_private_2 - Set PG_private_2 on a page and take a ref + * @page: The page. + * + * Set the PG_private_2 flag on a page and take the reference needed for the VM + * to handle its lifetime correctly. This sets the flag and takes the + * reference unconditionally, so care must be taken not to set the flag again + * if it's already set. + */ +static inline void set_page_private_2(struct page *page) +{ + page = compound_head(page); + get_page(page); + SetPagePrivate2(page); +} + +void end_page_private_2(struct page *page); +void wait_on_page_private_2(struct page *page); +int wait_on_page_private_2_killable(struct page *page); + /* * Add an arbitrary waiter to a page's wait queue */ -- cgit v1.2.3-71-gd317