[rfc 03/10] Pageflags: Convert to the use of new macros

[Christoph Lameter]

Replace explicit definitions of page flags through the use of macros.
Significantly reduces the size of the definitions and removes a lot of
opportunity for errors. Additonal page flags can typically be generated
with a single line.

RFC->V1:
- Use inline function for PageHighMem() (suggested by Mel)

Signed-off-by: Christoph Lameter <clameter@xxxxxxx>

---
 include/linux/page-flags.h |  191 +++++++++++++++------------------------------
 1 file changed, 64 insertions(+), 127 deletions(-)

Index: linux-2.6/include/linux/page-flags.h
===================================================================
--- linux-2.6.orig/include/linux/page-flags.h	2008-03-03 15:45:56.827992817 -0800
+++ linux-2.6/include/linux/page-flags.h	2008-03-03 15:46:15.848254180 -0800
@@ -145,28 +145,54 @@ static inline int TestClearPage##uname(s
 #define TESTSCFLAG(uname, lname)					\
 	TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname)
 
+struct page;	/* forward declaration */
+
+PAGEFLAG(Locked, locked) TESTSCFLAG(Locked, locked)
+PAGEFLAG(Error, error)
+PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced)
+PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty)
+PAGEFLAG(LRU, lru) __CLEARPAGEFLAG(LRU, lru)
+PAGEFLAG(Active, active) __CLEARPAGEFLAG(Active, active)
+__PAGEFLAG(Slab, slab)
+PAGEFLAG(Checked, checked)		/* Used by some filesystems */
+PAGEFLAG(Pinned, pinned)		/* Xen pinned pagetable */
+PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)
+PAGEFLAG(Private, private) __CLEARPAGEFLAG(Private, private)
+	__SETPAGEFLAG(Private, private)
+
 /*
- * Manipulation of page state flags
+ * Only test-and-set exist for PG_writeback.  The unconditional operators are
+ * risky: they bypass page accounting.
  */
-#define PageLocked(page)		\
-		test_bit(PG_locked, &(page)->flags)
-#define SetPageLocked(page)		\
-		set_bit(PG_locked, &(page)->flags)
-#define TestSetPageLocked(page)		\
-		test_and_set_bit(PG_locked, &(page)->flags)
-#define ClearPageLocked(page)		\
-		clear_bit(PG_locked, &(page)->flags)
-#define TestClearPageLocked(page)	\
-		test_and_clear_bit(PG_locked, &(page)->flags)
-
-#define PageError(page)		test_bit(PG_error, &(page)->flags)
-#define SetPageError(page)	set_bit(PG_error, &(page)->flags)
-#define ClearPageError(page)	clear_bit(PG_error, &(page)->flags)
-
-#define PageReferenced(page)	test_bit(PG_referenced, &(page)->flags)
-#define SetPageReferenced(page)	set_bit(PG_referenced, &(page)->flags)
-#define ClearPageReferenced(page)	clear_bit(PG_referenced, &(page)->flags)
-#define TestClearPageReferenced(page) test_and_clear_bit(PG_referenced, &(page)->flags)
+TESTPAGEFLAG(Writeback, writeback) TESTSCFLAG(Writeback, writeback)
+__PAGEFLAG(Buddy, buddy)
+PAGEFLAG(MappedToDisk, mappedtodisk)
+
+/* PG_readahead is only used for file reads; PG_reclaim is only for writes */
+PAGEFLAG(Reclaim, reclaim) TESTCLEARFLAG(Reclaim, reclaim)
+PAGEFLAG(Readahead, readahead)		/* Reminder to do async read-ahead */
+
+static inline int PageHighMem(struct page *page)
+{
+#ifdef CONFIG_HIGHMEM
+	return is_highmem(page_zone(page);
+#else
+	return 0; /* needed to optimize away at compile time */
+#endif
+}
+
+#ifdef CONFIG_SWAP
+PAGEFLAG(SwapCache, swapcache)
+#else
+static inline int PageSwapCache(struct page *page)
+{
+	return 0;
+}
+#endif
+
+#if (BITS_PER_LONG > 32)
+PAGEFLAG(Uncached, uncached)
+#endif
 
 static inline int PageUptodate(struct page *page)
 {
@@ -214,97 +240,37 @@ static inline void SetPageUptodate(struc
 #endif
 }
 
-#define ClearPageUptodate(page)	clear_bit(PG_uptodate, &(page)->flags)
+CLEARPAGEFLAG(Uptodate, uptodate)
 
-#define PageDirty(page)		test_bit(PG_dirty, &(page)->flags)
-#define SetPageDirty(page)	set_bit(PG_dirty, &(page)->flags)
-#define TestSetPageDirty(page)	test_and_set_bit(PG_dirty, &(page)->flags)
-#define ClearPageDirty(page)	clear_bit(PG_dirty, &(page)->flags)
-#define __ClearPageDirty(page)	__clear_bit(PG_dirty, &(page)->flags)
-#define TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags)
-
-#define PageLRU(page)		test_bit(PG_lru, &(page)->flags)
-#define SetPageLRU(page)	set_bit(PG_lru, &(page)->flags)
-#define ClearPageLRU(page)	clear_bit(PG_lru, &(page)->flags)
-#define __ClearPageLRU(page)	__clear_bit(PG_lru, &(page)->flags)
-
-#define PageActive(page)	test_bit(PG_active, &(page)->flags)
-#define SetPageActive(page)	set_bit(PG_active, &(page)->flags)
-#define ClearPageActive(page)	clear_bit(PG_active, &(page)->flags)
-#define __ClearPageActive(page)	__clear_bit(PG_active, &(page)->flags)
-
-#define PageSlab(page)		test_bit(PG_slab, &(page)->flags)
-#define __SetPageSlab(page)	__set_bit(PG_slab, &(page)->flags)
-#define __ClearPageSlab(page)	__clear_bit(PG_slab, &(page)->flags)
+extern void cancel_dirty_page(struct page *page, unsigned int account_size);
 
-#ifdef CONFIG_HIGHMEM
-#define PageHighMem(page)	is_highmem(page_zone(page))
-#else
-#define PageHighMem(page)	0 /* needed to optimize away at compile time */
-#endif
+int test_clear_page_writeback(struct page *page);
+int test_set_page_writeback(struct page *page);
 
-#define PageChecked(page)	test_bit(PG_checked, &(page)->flags)
-#define SetPageChecked(page)	set_bit(PG_checked, &(page)->flags)
-#define ClearPageChecked(page)	clear_bit(PG_checked, &(page)->flags)
-
-#define PagePinned(page)	test_bit(PG_pinned, &(page)->flags)
-#define SetPagePinned(page)	set_bit(PG_pinned, &(page)->flags)
-#define ClearPagePinned(page)	clear_bit(PG_pinned, &(page)->flags)
-
-#define PageReserved(page)	test_bit(PG_reserved, &(page)->flags)
-#define SetPageReserved(page)	set_bit(PG_reserved, &(page)->flags)
-#define ClearPageReserved(page)	clear_bit(PG_reserved, &(page)->flags)
-#define __ClearPageReserved(page)	__clear_bit(PG_reserved, &(page)->flags)
-
-#define SetPagePrivate(page)	set_bit(PG_private, &(page)->flags)
-#define ClearPagePrivate(page)	clear_bit(PG_private, &(page)->flags)
-#define PagePrivate(page)	test_bit(PG_private, &(page)->flags)
-#define __SetPagePrivate(page)  __set_bit(PG_private, &(page)->flags)
-#define __ClearPagePrivate(page) __clear_bit(PG_private, &(page)->flags)
+static inline void set_page_writeback(struct page *page)
+{
+	test_set_page_writeback(page);
+}
 
-/*
- * 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 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)
-#define __ClearPageBuddy(page)	__clear_bit(PG_buddy, &(page)->flags)
-
-#define PageMappedToDisk(page)	test_bit(PG_mappedtodisk, &(page)->flags)
-#define SetPageMappedToDisk(page) set_bit(PG_mappedtodisk, &(page)->flags)
-#define ClearPageMappedToDisk(page) clear_bit(PG_mappedtodisk, &(page)->flags)
-
-#define PageReadahead(page)	test_bit(PG_readahead, &(page)->flags)
-#define SetPageReadahead(page)	set_bit(PG_readahead, &(page)->flags)
-#define ClearPageReadahead(page) clear_bit(PG_readahead, &(page)->flags)
-
-#define PageReclaim(page)	test_bit(PG_reclaim, &(page)->flags)
-#define SetPageReclaim(page)	set_bit(PG_reclaim, &(page)->flags)
-#define ClearPageReclaim(page)	clear_bit(PG_reclaim, &(page)->flags)
-#define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags)
-
-#define PageCompound(page)	test_bit(PG_compound, &(page)->flags)
-#define __SetPageCompound(page)	__set_bit(PG_compound, &(page)->flags)
-#define __ClearPageCompound(page) __clear_bit(PG_compound, &(page)->flags)
+TESTPAGEFLAG(Compound, compound)
+__PAGEFLAG(Head, compound)
 
 /*
  * PG_reclaim is used in combination with PG_compound to mark the
- * head and tail of a compound page
+ * head and tail of a compound page. This saves one page flag
+ * but makes it impossible to use compound pages for the page cache.
+ * The PG_reclaim bit would have to be used for reclaim or readahead
+ * if compound pages enter the page cache.
  *
  * PG_compound & PG_reclaim	=> Tail page
  * PG_compound & ~PG_reclaim	=> Head page
  */
-
 #define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))
 
-#define PageTail(page)	(((page)->flags & PG_head_tail_mask)	\
-				== PG_head_tail_mask)
+static inline int PageTail(struct page *page)
+{
+	return ((page->flags & PG_head_tail_mask) == PG_head_tail_mask);
+}
 
 static inline void __SetPageTail(struct page *page)
 {
@@ -316,33 +282,4 @@ static inline void __ClearPageTail(struc
 	page->flags &= ~PG_head_tail_mask;
 }
 
-#define PageHead(page)	(((page)->flags & PG_head_tail_mask)	\
-				== (1L << PG_compound))
-#define __SetPageHead(page)	__SetPageCompound(page)
-#define __ClearPageHead(page)	__ClearPageCompound(page)
-
-#ifdef CONFIG_SWAP
-#define PageSwapCache(page)	test_bit(PG_swapcache, &(page)->flags)
-#define SetPageSwapCache(page)	set_bit(PG_swapcache, &(page)->flags)
-#define ClearPageSwapCache(page) clear_bit(PG_swapcache, &(page)->flags)
-#else
-#define PageSwapCache(page)	0
-#endif
-
-#define PageUncached(page)	test_bit(PG_uncached, &(page)->flags)
-#define SetPageUncached(page)	set_bit(PG_uncached, &(page)->flags)
-#define ClearPageUncached(page)	clear_bit(PG_uncached, &(page)->flags)
-
-struct page;	/* forward declaration */
-
-extern void cancel_dirty_page(struct page *page, unsigned int account_size);
-
-int test_clear_page_writeback(struct page *page);
-int test_set_page_writeback(struct page *page);
-
-static inline void set_page_writeback(struct page *page)
-{
-	test_set_page_writeback(page);
-}
-
 #endif	/* PAGE_FLAGS_H */

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