/* * 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 */