[PATCH 2/3] mm/gup: small refactoring: simplify try_grab_page()

From: John Hubbard
Date: Sun Aug 08 2021 - 19:50:38 EST


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.

Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
---
mm/gup.c | 29 ++---------------------------
1 file changed, 2 insertions(+), 27 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index 5cb18b62921c..4be6f060fa0b 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -203,33 +203,8 @@ 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 try_grab_compound_head(page, 1, flags) != NULL;

return true;
}
--
2.32.0