Commit 54d516b1 authored by John Hubbard's avatar John Hubbard Committed by Linus Torvalds
Browse files

mm/gup: small refactoring: simplify try_grab_page() 

try_grab_page() does the same thing as try_grab_compound_head(..., refs=1,
...), just with a different API.  So there is a lot of code duplication
there.

Change try_grab_page() to call try_grab_compound_head(), while keeping the
API contract identical for callers.

Also, now that try_grab_compound_head() always has a caller, remove the
__maybe_unused annotation.

Link: https://lkml.kernel.org/r/20210813044133.1536842-3-jhubbard@nvidia.com


Signed-off-by: default avatarJohn Hubbard <jhubbard@nvidia.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3967db22

include/linux/mm.h

+2 −2
Original line number Diff line number Diff line
@@ -1214,7 +1214,7 @@ static inline void get_page(struct page *page) 
}



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

__maybe_unused struct page *try_grab_compound_head(struct page *page, int refs,

struct page *try_grab_compound_head(struct page *page, int refs,

				    unsigned int flags);

mm/gup.c

+5 −30
Original line number Diff line number Diff line
@@ -124,7 +124,7 @@ static inline struct page *try_get_compound_head(struct page *page, int refs) 
 * considered failure, and furthermore, a likely bug in the caller, so a warning

 * is also emitted.

 */

__maybe_unused struct page *try_grab_compound_head(struct page *page,

struct page *try_grab_compound_head(struct page *page,

				    int refs, unsigned int flags)

{

	if (flags & FOLL_GET)
@@ -208,35 +208,10 @@ 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)

{

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



	if (flags & FOLL_GET)

		return try_get_page(page);

	else if (flags & FOLL_PIN) {

		int refs = 1;



		page = compound_head(page);



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

			return false;



		if (hpage_pincount_available(page))

			hpage_pincount_add(page, 1);

		else

			refs = GUP_PIN_COUNTING_BIAS;



		/*

		 * Similar to try_grab_compound_head(): even if using the

		 * hpage_pincount_add/_sub() routines, be sure to

		 * *also* increment the normal page refcount field at least

		 * once, so that the page really is pinned.

		 */

		page_ref_add(page, refs);



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

	}



	if (!(flags & (FOLL_GET | FOLL_PIN)))

		return true;



	return try_grab_compound_head(page, 1, flags);

}



/**