[rfc 01/10] Pageflags: Use an enum for the flags

From: Christoph Lameter
Date: Fri Feb 29 2008 - 23:07:32 EST


Use an enum to ease the maintenance of page flags. This is going to change the
numbering from 0 to 18.

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

---
include/linux/page-flags.h | 54 ++++++++++++++++++++-------------------------
1 file changed, 24 insertions(+), 30 deletions(-)

Index: linux-2.6/include/linux/page-flags.h
===================================================================
--- linux-2.6.orig/include/linux/page-flags.h 2008-02-29 14:54:22.000000000 -0800
+++ linux-2.6/include/linux/page-flags.h 2008-02-29 15:00:00.000000000 -0800
@@ -67,35 +67,28 @@
* FLAGS_RESERVED which defines the width of the fields section
* (see linux/mmzone.h). New flags must _not_ overlap with this area.
*/
-#define PG_locked 0 /* Page is locked. Don't touch. */
-#define PG_error 1
-#define PG_referenced 2
-#define PG_uptodate 3
-
-#define PG_dirty 4
-#define PG_lru 5
-#define PG_active 6
-#define PG_slab 7 /* slab debug (Suparna wants this) */
-
-#define PG_owner_priv_1 8 /* Owner use. If pagecache, fs may use*/
-#define PG_arch_1 9
-#define PG_reserved 10
-#define PG_private 11 /* If pagecache, has fs-private data */
-
-#define PG_writeback 12 /* Page is under writeback */
-#define PG_compound 14 /* Part of a compound page */
-#define PG_swapcache 15 /* Swap page: swp_entry_t in private */
-
-#define PG_mappedtodisk 16 /* Has blocks allocated on-disk */
-#define PG_reclaim 17 /* To be reclaimed asap */
-#define PG_buddy 19 /* Page is free, on buddy lists */
-
-/* PG_readahead is only used for file reads; PG_reclaim is only for writes */
-#define PG_readahead PG_reclaim /* Reminder to do async read-ahead */
-
-/* PG_owner_priv_1 users should have descriptive aliases */
-#define PG_checked PG_owner_priv_1 /* Used by some filesystems */
-#define PG_pinned PG_owner_priv_1 /* Xen pinned pagetable */
+enum pageflags {
+ PG_locked, /* Page is locked. Don't touch. */
+ PG_error,
+ PG_referenced,
+ PG_uptodate,
+ PG_dirty,
+ PG_lru,
+ PG_active,
+ PG_slab,
+ PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/
+ PG_arch_1,
+ PG_reserved,
+ PG_private, /* If pagecache, has fs-private data */
+ PG_writeback, /* Page is under writeback */
+ PG_compound, /* A compound page */
+ PG_swapcache, /* Swap page: swp_entry_t in private */
+ PG_mappedtodisk, /* Has blocks allocated on-disk */
+ PG_reclaim, /* To be reclaimed asap */
+ /* PG_readahead is only used for file reads; PG_reclaim is only for writes */
+ PG_readahead = PG_reclaim, /* Reminder to do async read-ahead */
+ PG_buddy, /* Page is free, on buddy lists */
+ NR_PAGEFLAGS, /* For verification purposes */

#if (BITS_PER_LONG > 32)
/*
@@ -105,8 +98,9 @@
* 64 bit | FIELDS | ?????? FLAGS |
* 63 32 0
*/
-#define PG_uncached 31 /* Page has been mapped as uncached */
+ PG_uncached = 31, /* Page has been mapped as uncached */
#endif
+};

/*
* Manipulation of page state flags

--
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