This patch creates new type that is compatible with struct page on memory layout, but distinct from C point of view.
compound_head_t() has the same functionality as compound_head(), but returns pointer on struct head_page. Not-yet-signed-off-by: Kirill A. Shutemov <[email protected]> --- include/linux/mm_types.h | 4 ++++ include/linux/page-flags.h | 9 ++++++++- 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 944b2b37313b..247e86adaa1c 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -225,6 +225,10 @@ struct page { #endif ; +struct head_page { + struct page page; +}; + struct page_frag { struct page *page; #if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index d111caad2a22..54801253b85c 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -133,7 +133,9 @@ enum pageflags { #ifndef __GENERATING_BOUNDS_H -struct page; /* forward declaration */ +/* forward declaration */ +struct page; +struct head_page; static inline struct page *compound_head(struct page *page) { @@ -144,6 +146,11 @@ static inline struct page *compound_head(struct page *page) return page; } +static inline struct head_page *compound_head_t(struct page *page) +{ + return (struct head_page *)compound_head(page); +} + static __always_inline int PageTail(struct page *page) { return READ_ONCE(page->compound_head) & 1; -- 2.8.0.rc3
