Commit 3fe7fa58 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

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: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Reviewed-by: default avatarWilliam Kucharski <william.kucharski@oracle.com>
parent 6840f909

include/linux/mm.h

+20 −0
Original line number Diff line number Diff line
@@ -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);