move page writeback acounting out of macros
page-writeback accounting is presently performed in the page-flags macros.
This is inconsistent and a bit ugly and makes it awkward to implement
per-backing_dev under-writeback page accounting.
So move this accounting down to the callsite(s).
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index a454176..209d3a4 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -189,37 +189,15 @@
#define __SetPagePrivate(page) __set_bit(PG_private, &(page)->flags)
#define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags)
+/*
+ * Only test-and-set exist for PG_writeback. The unconditional operators are
+ * risky: they bypass page accounting.
+ */
#define PageWriteback(page) test_bit(PG_writeback, &(page)->flags)
-#define SetPageWriteback(page) \
- do { \
- if (!test_and_set_bit(PG_writeback, \
- &(page)->flags)) \
- inc_zone_page_state(page, NR_WRITEBACK); \
- } while (0)
-#define TestSetPageWriteback(page) \
- ({ \
- int ret; \
- ret = test_and_set_bit(PG_writeback, \
- &(page)->flags); \
- if (!ret) \
- inc_zone_page_state(page, NR_WRITEBACK); \
- ret; \
- })
-#define ClearPageWriteback(page) \
- do { \
- if (test_and_clear_bit(PG_writeback, \
- &(page)->flags)) \
- dec_zone_page_state(page, NR_WRITEBACK); \
- } while (0)
-#define TestClearPageWriteback(page) \
- ({ \
- int ret; \
- ret = test_and_clear_bit(PG_writeback, \
- &(page)->flags); \
- if (ret) \
- dec_zone_page_state(page, NR_WRITEBACK); \
- ret; \
- })
+#define TestSetPageWriteback(page) test_and_set_bit(PG_writeback, \
+ &(page)->flags)
+#define TestClearPageWriteback(page) test_and_clear_bit(PG_writeback, \
+ &(page)->flags)
#define PageBuddy(page) test_bit(PG_buddy, &(page)->flags)
#define __SetPageBuddy(page) __set_bit(PG_buddy, &(page)->flags)