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-rw-r--r--include/linux/page-flags.h9
1 files changed, 9 insertions, 0 deletions
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index a57c909a15e4..c56b39890a41 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -73,6 +73,7 @@
*/
enum pageflags {
PG_locked, /* Page is locked. Don't touch. */
+ PG_waiters, /* Page has waiters, check its waitqueue */
PG_error,
PG_referenced,
PG_uptodate,
@@ -169,6 +170,9 @@ static __always_inline int PageCompound(struct page *page)
* for compound page all operations related to the page flag applied to
* head page.
*
+ * PF_ONLY_HEAD:
+ * for compound page, callers only ever operate on the head page.
+ *
* PF_NO_TAIL:
* modifications of the page flag must be done on small or head pages,
* checks can be done on tail pages too.
@@ -178,6 +182,9 @@ static __always_inline int PageCompound(struct page *page)
*/
#define PF_ANY(page, enforce) page
#define PF_HEAD(page, enforce) compound_head(page)
+#define PF_ONLY_HEAD(page, enforce) ({ \
+ VM_BUG_ON_PGFLAGS(PageTail(page), page); \
+ page;})
#define PF_NO_TAIL(page, enforce) ({ \
VM_BUG_ON_PGFLAGS(enforce && PageTail(page), page); \
compound_head(page);})
@@ -255,6 +262,7 @@ static inline int TestClearPage##uname(struct page *page) { return 0; }
TESTSETFLAG_FALSE(uname) TESTCLEARFLAG_FALSE(uname)
__PAGEFLAG(Locked, locked, PF_NO_TAIL)
+PAGEFLAG(Waiters, waiters, PF_ONLY_HEAD) __CLEARPAGEFLAG(Waiters, waiters, PF_ONLY_HEAD)
PAGEFLAG(Error, error, PF_NO_COMPOUND) TESTCLEARFLAG(Error, error, PF_NO_COMPOUND)
PAGEFLAG(Referenced, referenced, PF_HEAD)
TESTCLEARFLAG(Referenced, referenced, PF_HEAD)
@@ -743,6 +751,7 @@ static inline int page_has_private(struct page *page)
#undef PF_ANY
#undef PF_HEAD
+#undef PF_ONLY_HEAD
#undef PF_NO_TAIL
#undef PF_NO_COMPOUND
#endif /* !__GENERATING_BOUNDS_H */