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/*
 * Macros for manipulating and testing page->flags
 */


#ifndef PAGE_FLAGS_H
#define PAGE_FLAGS_H

#include <linux/percpu.h>
#include <linux/cache.h>
#include <asm/pgtable.h>

/*
 * Various page->flags bits:
 *
 * PG_reserved is set for special pages, which can never be swapped out. Some
 * of them might not even exist (eg empty_bad_page)...
 *
 * The PG_private bitflag is set if page->private contains a valid value.
 *
 * During disk I/O, PG_locked is used. This bit is set before I/O and
 * reset when I/O completes. page_waitqueue(page) is a wait queue of all tasks
 * waiting for the I/O on this page to complete.
 *
 * PG_uptodate tells whether the page's contents is valid.  When a read
 * completes, the page becomes uptodate, unless a disk I/O error happened.
 *
 * For choosing which pages to swap out, inode pages carry a PG_referenced bit,
 * which is set any time the system accesses that page through the (mapping,
 * index) hash table.  This referenced bit, together with the referenced bit
 * in the page tables, is used to manipulate page->age and move the page across
 * the active, inactive_dirty and inactive_clean lists.
 *
 * Note that the referenced bit, the page->lru list_head and the active,
 * inactive_dirty and inactive_clean lists are protected by the
 * zone->lru_lock, and *NOT* by the usual PG_locked bit!
 *
 * PG_error is set to indicate that an I/O error occurred on this page.
 *
 * PG_arch_1 is an architecture specific page state bit.  The generic code
 * guarantees that this bit is cleared for a page when it first is entered into
 * the page cache.
 *
 * PG_highmem pages are not permanently mapped into the kernel virtual address
 * space, they need to be kmapped separately for doing IO on the pages.  The
 * struct page (these bits with information) are always mapped into kernel
 * address space...
 */


/*
 * Don't use the *_dontuse flags.  Use the macros.  Otherwise you'll break
 * locked- and dirty-page accounting.  The top eight bits of page->flags are
 * used for page->zone, so putting flag bits there doesn't work.
 */

#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_highmem               8
#define PG_checked               9      /* kill me in 2.5.<early>. */
#define PG_arch_1               10
#define PG_reserved             11

#define PG_private              12      /* Has something at ->private */
#define PG_writeback            13      /* Page is under writeback */
#define PG_nosave               14      /* Used for system suspend/resume */
#define PG_chainlock            15      /* lock bit for ->pte_chain */

#define PG_direct               16      /* ->pte_chain points directly at pte */
#define PG_mappedtodisk         17      /* Has blocks allocated on-disk */
#define PG_reclaim              18      /* To be reclaimed asap */
#define PG_compound             19      /* Part of a compound page */


/*
 * Global page accounting.  One instance per CPU.  Only unsigned longs are
 * allowed.
 */

struct page_state {
        unsigned long nr_dirty;         /* Dirty writeable pages */
        unsigned long nr_writeback;     /* Pages under writeback */
        unsigned long nr_unstable;      /* NFS unstable pages */
        unsigned long nr_page_table_pages;/* Pages used for pagetables */
        unsigned long nr_mapped;        /* mapped into pagetables */
        unsigned long nr_slab;          /* In slab */
#define GET_PAGE_STATE_LAST nr_slab

        /*
         * The below are zeroed by get_page_state().  Use get_full_page_state()
         * to add up all these.
         */

        unsigned long pgpgin;           /* Disk reads */
        unsigned long pgpgout;          /* Disk writes */
        unsigned long pswpin;           /* swap reads */
        unsigned long pswpout;          /* swap writes */
        unsigned long pgalloc;          /* page allocations */

        unsigned long pgfree;           /* page freeings */
        unsigned long pgactivate;       /* pages moved inactive->active */
        unsigned long pgdeactivate;     /* pages moved active->inactive */
        unsigned long pgfault;          /* faults (major+minor) */
        unsigned long pgmajfault;       /* faults (major only) */

        unsigned long pgscan;           /* pages scanned by page reclaim */
        unsigned long pgrefill;         /* inspected in refill_inactive_zone */
        unsigned long pgsteal;          /* total pages reclaimed */
        unsigned long pginodesteal;     /* pages reclaimed via inode freeing */
        unsigned long kswapd_steal;     /* pages reclaimed by kswapd */

        unsigned long kswapd_inodesteal;/* reclaimed via kswapd inode freeing */
        unsigned long pageoutrun;       /* kswapd's calls to page reclaim */
        unsigned long allocstall;       /* direct reclaim calls */
        unsigned long pgrotated;        /* pages rotated to tail of the LRU */
} ____cacheline_aligned;

DECLARE_PER_CPU(struct page_state, page_states);

extern void get_page_state(struct page_state *ret);
extern void get_full_page_state(struct page_state *ret);

#define mod_page_state(member, delta)                                   \
        do {                                                            \
                unsigned long flags;                                    \
                local_irq_save(flags);                                  \
                __get_cpu_var(page_states).member += (delta);           \
                local_irq_restore(flags);                               \
        } while (0)


#define inc_page_state(member)  mod_page_state(member, 1UL)
#define dec_page_state(member)  mod_page_state(member, 0UL - 1)
#define sub_page_state(member,delta) mod_page_state(member, 0UL - (delta))


/*
 * Manipulation of page state flags
 */

#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)

#ifndef arch_set_page_uptodate
#define arch_set_page_uptodate(page) do { } while (0)
#endif

#define PageUptodate(page)      test_bit(PG_uptodate, &(page)->flags)
#define SetPageUptodate(page) \
        do {                                                            \
                arch_set_page_uptodate(page);                           \
                set_bit(PG_uptodate, &(page)->flags);                   \
        } while (0)

#define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags)

#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 TestClearPageDirty(page) test_and_clear_bit(PG_dirty, &(page)->flags)

#define SetPageLRU(page)        set_bit(PG_lru, &(page)->flags)
#define PageLRU(page)           test_bit(PG_lru, &(page)->flags)
#define TestSetPageLRU(page)    test_and_set_bit(PG_lru, &(page)->flags)
#define TestClearPageLRU(page)  test_and_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 TestClearPageActive(page) test_and_clear_bit(PG_active, &(page)->flags)
#define TestSetPageActive(page) test_and_set_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)
#define TestClearPageSlab(page) test_and_clear_bit(PG_slab, &(page)->flags)
#define TestSetPageSlab(page)   test_and_set_bit(PG_slab, &(page)->flags)

#ifdef CONFIG_HIGHMEM
#define PageHighMem(page)       test_bit(PG_highmem, &(page)->flags)
#else
#define PageHighMem(page)       0 /* needed to optimize away at compile time */
#endif

#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 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 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 PageWriteback(page)     test_bit(PG_writeback, &(page)->flags)
#define SetPageWriteback(page)                                          \
        do {                                                            \
                if (!test_and_set_bit(PG_writeback,                     \
                                &(page)->flags))                        \
                        inc_page_state(nr_writeback);                   \
        } while (0)

#define TestSetPageWriteback(page)                                      \
        ({                                                              \
                int ret;                                                \
                ret = test_and_set_bit(PG_writeback,                    \
                                        &(page)->flags);                \
                if (!ret)                                               \
                        inc_page_state(nr_writeback);                   \
                ret;                                                    \
        })

#define ClearPageWriteback(page)                                        \
        do {                                                            \
                if (test_and_clear_bit(PG_writeback,                    \
                                &(page)->flags))                        \
                        dec_page_state(nr_writeback);                   \
        } while (0)

#define TestClearPageWriteback(page)                                    \
        ({                                                              \
                int ret;                                                \
                ret = test_and_clear_bit(PG_writeback,                  \
                                &(page)->flags);                        \
                if (ret)                                                \
                        dec_page_state(nr_writeback);                   \
                ret;                                                    \
        })


#define PageNosave(page)        test_bit(PG_nosave, &(page)->flags)
#define SetPageNosave(page)     set_bit(PG_nosave, &(page)->flags)
#define TestSetPageNosave(page) test_and_set_bit(PG_nosave, &(page)->flags)
#define ClearPageNosave(page)           clear_bit(PG_nosave, &(page)->flags)
#define TestClearPageNosave(page)       test_and_clear_bit(PG_nosave, &(page)->flags)

#define PageDirect(page)        test_bit(PG_direct, &(page)->flags)
#define SetPageDirect(page)     set_bit(PG_direct, &(page)->flags)
#define TestSetPageDirect(page) test_and_set_bit(PG_direct, &(page)->flags)
#define ClearPageDirect(page)           clear_bit(PG_direct, &(page)->flags)
#define TestClearPageDirect(page)       test_and_clear_bit(PG_direct, &(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 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)

/*
 * The PageSwapCache predicate doesn't use a PG_flag at this time,
 * but it may again do so one day.
 */

#ifdef CONFIG_SWAP
extern struct address_space swapper_space;
#define PageSwapCache(page) ((page)->mapping == &swapper_space)
#else
#define PageSwapCache(page) 0
#endif

struct page;    /* forward declaration */

int test_clear_page_dirty(struct page *page);

static inline void clear_page_dirty(struct page *page)
{
        test_clear_page_dirty(page);
}

#endif  /* PAGE_FLAGS_H */