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-rw-r--r--include/linux/page-flags.h37
1 files changed, 26 insertions, 11 deletions
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index a1e143634946..a3c8b60a9c3a 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -6,6 +6,7 @@
6#define PAGE_FLAGS_H 6#define PAGE_FLAGS_H
7 7
8#include <linux/types.h> 8#include <linux/types.h>
9#include <linux/mm_types.h>
9 10
10/* 11/*
11 * Various page->flags bits: 12 * Various page->flags bits:
@@ -94,12 +95,6 @@
94/* PG_owner_priv_1 users should have descriptive aliases */ 95/* PG_owner_priv_1 users should have descriptive aliases */
95#define PG_checked PG_owner_priv_1 /* Used by some filesystems */ 96#define PG_checked PG_owner_priv_1 /* Used by some filesystems */
96 97
97/*
98 * Marks tail portion of a compound page. We currently do not reclaim
99 * compound pages so we can reuse a flag only used for reclaim here.
100 */
101#define PG_tail PG_reclaim
102
103#if (BITS_PER_LONG > 32) 98#if (BITS_PER_LONG > 32)
104/* 99/*
105 * 64-bit-only flags build down from bit 31 100 * 64-bit-only flags build down from bit 31
@@ -248,12 +243,32 @@ static inline void SetPageUptodate(struct page *page)
248#define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags) 243#define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags)
249 244
250/* 245/*
251 * Note: PG_tail is an alias of another page flag. The result of PageTail() 246 * PG_reclaim is used in combination with PG_compound to mark the
252 * is only valid if PageCompound(page) is true. 247 * head and tail of a compound page
248 *
249 * PG_compound & PG_reclaim => Tail page
250 * PG_compound & ~PG_reclaim => Head page
253 */ 251 */
254#define PageTail(page) test_bit(PG_tail, &(page)->flags) 252
255#define __SetPageTail(page) __set_bit(PG_tail, &(page)->flags) 253#define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))
256#define __ClearPageTail(page) __clear_bit(PG_tail, &(page)->flags) 254
255#define PageTail(page) ((page->flags & PG_head_tail_mask) \
256 == PG_head_tail_mask)
257
258static inline void __SetPageTail(struct page *page)
259{
260 page->flags |= PG_head_tail_mask;
261}
262
263static inline void __ClearPageTail(struct page *page)
264{
265 page->flags &= ~PG_head_tail_mask;
266}
267
268#define PageHead(page) ((page->flags & PG_head_tail_mask) \
269 == (1L << PG_compound))
270#define __SetPageHead(page) __SetPageCompound(page)
271#define __ClearPageHead(page) __ClearPageCompound(page)
257 272
258#ifdef CONFIG_SWAP 273#ifdef CONFIG_SWAP
259#define PageSwapCache(page) test_bit(PG_swapcache, &(page)->flags) 274#define PageSwapCache(page) test_bit(PG_swapcache, &(page)->flags)