Commit 5fec0719 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

mm/gup: Convert try_grab_page() to use a folio 



Hoist the folio conversion and the folio_ref_count() check to the
top of the function instead of using the one buried in try_get_page().

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent ece1ed7b

mm/gup.c

+13 −15
Original line number Diff line number Diff line
@@ -174,15 +174,14 @@ static void put_compound_head(struct page *page, int refs, unsigned int flags) 


/**

 * try_grab_page() - elevate a page's refcount by a flag-dependent amount

 * @page:    pointer to page to be grabbed

 * @flags:   gup flags: these are the FOLL_* flag values.

 *

 * This might not do anything at all, depending on the flags argument.

 *

 * "grab" names in this file mean, "look at flags to decide whether to use

 * FOLL_PIN or FOLL_GET behavior, when incrementing the page's refcount.

 *

 * @page:    pointer to page to be grabbed

 * @flags:   gup flags: these are the FOLL_* flag values.

 *

 * Either FOLL_PIN or FOLL_GET (or neither) may be set, but not both at the same

 * time. Cases: please see the try_grab_folio() documentation, with

 * "refs=1".
@@ -193,29 +192,28 @@ static void put_compound_head(struct page *page, int refs, unsigned int flags) 
 */

bool __must_check try_grab_page(struct page *page, unsigned int flags)

{

	struct folio *folio = page_folio(page);



	WARN_ON_ONCE((flags & (FOLL_GET | FOLL_PIN)) == (FOLL_GET | FOLL_PIN));

	if (WARN_ON_ONCE(folio_ref_count(folio) <= 0))

		return false;



	if (flags & FOLL_GET)

		return try_get_page(page);

		folio_ref_inc(folio);

	else if (flags & FOLL_PIN) {

		page = compound_head(page);



		if (WARN_ON_ONCE(page_ref_count(page) <= 0))

			return false;



		/*

		 * Similar to try_grab_compound_head(): be sure to *also*

		 * Similar to try_grab_folio(): be sure to *also*

		 * increment the normal page refcount field at least once,

		 * so that the page really is pinned.

		 */

		if (PageHead(page)) {

			page_ref_add(page, 1);

			atomic_add(1, compound_pincount_ptr(page));

		if (folio_test_large(folio)) {

			folio_ref_add(folio, 1);

			atomic_add(1, folio_pincount_ptr(folio));

		} else {

			page_ref_add(page, GUP_PIN_COUNTING_BIAS);

			folio_ref_add(folio, GUP_PIN_COUNTING_BIAS);

		}



		mod_node_page_state(page_pgdat(page), NR_FOLL_PIN_ACQUIRED, 1);

		node_stat_mod_folio(folio, NR_FOLL_PIN_ACQUIRED, 1);

	}



	return true;