diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/mm.h | 33 | ||||
| -rw-r--r-- | include/linux/page-flags.h | 14 |
2 files changed, 42 insertions, 5 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index c95d96ebd5ad..8c149fa4491d 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -267,17 +267,28 @@ static inline int get_page_unless_zero(struct page *page) return atomic_inc_not_zero(&page->_count); } +static inline struct page *compound_head(struct page *page) +{ + /* + * We could avoid the PageCompound(page) check if + * we would not overload PageTail(). + * + * This check has to be done in several performance critical + * paths of the slab etc. IMHO PageTail deserves its own flag. + */ + if (unlikely(PageCompound(page) && PageTail(page))) + return page->first_page; + return page; +} + static inline int page_count(struct page *page) { - if (unlikely(PageCompound(page))) - page = (struct page *)page_private(page); - return atomic_read(&page->_count); + return atomic_read(&compound_head(page)->_count); } static inline void get_page(struct page *page) { - if (unlikely(PageCompound(page))) - page = (struct page *)page_private(page); + page = compound_head(page); VM_BUG_ON(atomic_read(&page->_count) == 0); atomic_inc(&page->_count); } @@ -314,6 +325,18 @@ static inline compound_page_dtor *get_compound_page_dtor(struct page *page) return (compound_page_dtor *)page[1].lru.next; } +static inline int compound_order(struct page *page) +{ + if (!PageCompound(page) || PageTail(page)) + return 0; + return (unsigned long)page[1].lru.prev; +} + +static inline void set_compound_order(struct page *page, unsigned long order) +{ + page[1].lru.prev = (void *)order; +} + /* * Multiple processes may "see" the same page. E.g. for untouched * mappings of /dev/null, all processes see the same page full of diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 96326594e55d..a1e143634946 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -94,6 +94,12 @@ /* PG_owner_priv_1 users should have descriptive aliases */ #define PG_checked PG_owner_priv_1 /* Used by some filesystems */ +/* + * Marks tail portion of a compound page. We currently do not reclaim + * compound pages so we can reuse a flag only used for reclaim here. + */ +#define PG_tail PG_reclaim + #if (BITS_PER_LONG > 32) /* * 64-bit-only flags build down from bit 31 @@ -241,6 +247,14 @@ static inline void SetPageUptodate(struct page *page) #define __SetPageCompound(page) __set_bit(PG_compound, &(page)->flags) #define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags) +/* + * Note: PG_tail is an alias of another page flag. The result of PageTail() + * is only valid if PageCompound(page) is true. + */ +#define PageTail(page) test_bit(PG_tail, &(page)->flags) +#define __SetPageTail(page) __set_bit(PG_tail, &(page)->flags) +#define __ClearPageTail(page) __clear_bit(PG_tail, &(page)->flags) + #ifdef CONFIG_SWAP #define PageSwapCache(page) test_bit(PG_swapcache, &(page)->flags) #define SetPageSwapCache(page) set_bit(PG_swapcache, &(page)->flags) |