From: Matthew Wilcox (Oracle) Date: Fri, 10 Dec 2021 20:09:21 +0000 (-0500) Subject: mm: Add folio_put_refs() X-Git-Tag: v5.17-rc1~9^2~1 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=3fe7fa5843d204e235d92902190fecb972a3f9cc;p=thirdparty%2Fkernel%2Flinux.git mm: Add folio_put_refs() This is like folio_put(), but puts N references at once instead of just one. It's like put_page_refs(), but does one atomic operation instead of two, and is available to more than just gup.c. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Christoph Hellwig Reviewed-by: John Hubbard Reviewed-by: Jason Gunthorpe Reviewed-by: William Kucharski --- diff --git a/include/linux/mm.h b/include/linux/mm.h index c768a7c81b0b1..cb98f75b245e8 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1244,6 +1244,26 @@ static inline void folio_put(struct folio *folio) __put_page(&folio->page); } +/** + * folio_put_refs - Reduce the reference count on a folio. + * @folio: The folio. + * @refs: The amount to subtract from the folio's reference count. + * + * If the folio's reference count reaches zero, the memory will be + * released back to the page allocator and may be used by another + * allocation immediately. Do not access the memory or the struct folio + * after calling folio_put_refs() unless you can be sure that these weren't + * the last references. + * + * Context: May be called in process or interrupt context, but not in NMI + * context. May be called while holding a spinlock. + */ +static inline void folio_put_refs(struct folio *folio, int refs) +{ + if (folio_ref_sub_and_test(folio, refs)) + __put_page(&folio->page); +} + static inline void put_page(struct page *page) { struct folio *folio = page_folio(page);