pageflags: use an enum for the flags

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@sgi.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 26 insertions, 30 deletions

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index b5b30f1c1e59..d66971530caa 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -67,35 +67,29 @@
  * 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_checked = PG_owner_priv_1, /* Used by some filesystems */
+        PG_pinned = PG_owner_priv_1, /* Xen pinned pagetable */
+        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 */
 
 #if (BITS_PER_LONG > 32)
 /*
@@ -105,8 +99,10 @@
  * 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
+        NR_PAGEFLAGS
+};
 
 /*
  * Manipulation of page state flags