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/*

 * Macros for manipulating and testing page->flags

 */

#ifndef PAGE_FLAGS_H

#define PAGE_FLAGS_H

#include <linux/types.h>

#include <linux/mm_types.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 on pagecache pages if they contain filesystem

 * specific data (which is normally at page->private). It can be used by

 * private allocations for its own usage.

 *

 * During initiation of disk I/O, PG_locked is set. This bit is set before I/O

 * and cleared when writeback _starts_ or when read _completes_. PG_writeback

 * is set before writeback starts and cleared when it finishes.

 *

 * PG_locked also pins a page in pagecache, and blocks truncation of the file

 * while it is held.

 *

 * page_waitqueue(page) is a wait queue of all tasks waiting for the page

 * to become unlocked.

 *

 * 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.

 *

 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and

 * file-backed pagecache (see mm/vmscan.c).

 *

 * 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...

 *

 * PG_buddy is set to indicate that the page is free and in the buddy system

 * (see mm/page_alloc.c).

 *

 */

/*

 * Don't use the *_dontuse flags.  Use the macros.  Otherwise you'll break

 * locked- and dirty-page accounting.

 *

 * The page flags field is split into two parts, the main flags area

 * which extends from the low bits upwards, and the fields area which

 * extends from the high bits downwards.

 *

 *  | FIELD | ... | FLAGS |

 *  N-1     ^             0

 *          (N-FLAGS_RESERVED)

 *

 * The fields area is reserved for fields mapping zone, node and SPARSEMEM

 * section.  The boundry between these two areas is defined by

 * 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 */

#if (BITS_PER_LONG > 32)

/*

 * 64-bit-only flags build down from bit 31

 *

 * 32 bit  -------------------------------| FIELDS |       FLAGS         |

 * 64 bit  |           FIELDS             | ??????         FLAGS         |

 *         63                            32                              0

 */

#define PG_uncached             31      /* Page has been mapped as uncached */

#endif

/*

 * 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)

#define PageUptodate(page)      test_bit(PG_uptodate, &(page)->flags)

#ifdef CONFIG_S390

static inline void SetPageUptodate(struct page *page)

{

        if (!test_and_set_bit(PG_uptodate, &page->flags))

                page_clear_dirty(page);

}

#else

#define SetPageUptodate(page)   set_bit(PG_uptodate, &(page)->flags)

#endif

#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 __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)

#ifdef CONFIG_HIGHMEM

#define PageHighMem(page)       is_highmem(page_zone(page))

#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 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)

/*

 * 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)

/*

 * PG_reclaim is used in combination with PG_compound to mark the

 * head and tail of a compound page

 *

 * 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 void __SetPageTail(struct page *page)

{

        page->flags |= PG_head_tail_mask;

}

static inline void __ClearPageTail(struct page *page)

{

        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 */