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 <[email protected]>
---
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
--
On (29/02/08 20:05), Christoph Lameter didst pronounce:
> 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 <[email protected]>
>
> ---
> 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 */
These two verbose descriptions appear to go missing in the enum below.
It probably is intentional because they are aliases but you can preseve them
being aliases with
PG_checked = PG_owner_priv_1,
PG_pinned = PG_owner_priv_1,
That would keep the comments about flags in one place. I note that you
move the comment to the macro definitions in a later patch but maybe having
comments about some flags in multiple places is not very desirable?
> +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
>
> --
>
--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab