Simplify page_is_buddy() to reduce the redundant code for better code
readability.

Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
---
changes in v4:
 - change the return type of page_is_buddy() from int to bool.
 - reflow the comment into fewer lines.
---
 mm/page_alloc.c | 33 +++++++++++++--------------------
 1 file changed, 13 insertions(+), 20 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 3c4eb75..229fc8c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -791,32 +791,25 @@ static inline void set_page_order(struct page *page, unsigned int order)
  *
  * For recording page's order, we use page_private(page).
  */
-static inline int page_is_buddy(struct page *page, struct page *buddy,
+static inline bool page_is_buddy(struct page *page, struct page *buddy,
                                                        unsigned int order)
 {
-       if (page_is_guard(buddy) && page_order(buddy) == order) {
-               if (page_zone_id(page) != page_zone_id(buddy))
-                       return 0;
-
-               VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
+       if (!page_is_guard(buddy) && !PageBuddy(buddy))
+               return false;

-               return 1;
-       }
+       if (page_order(buddy) != order)
+               return false;

-       if (PageBuddy(buddy) && page_order(buddy) == order) {
-               /*
-                * zone check is done late to avoid uselessly
-                * calculating zone/node ids for pages that could
-                * never merge.
-                */
-               if (page_zone_id(page) != page_zone_id(buddy))
-                       return 0;
+       /*
+        * zone check is done late to avoid uselessly calculating
+        * zone/node ids for pages that could never merge.
+        */
+       if (page_zone_id(page) != page_zone_id(buddy))
+               return false;

-               VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);
+       VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy);

-               return 1;
-       }
-       return 0;
+       return true;
 }

 #ifdef CONFIG_COMPACTION
--

1.9.1