/* * Macros for manipulating and testing page->flags */ #ifndef PAGE_FLAGS_H #define PAGE_FLAGS_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 * pagemap_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_dontuse 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.. */ #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 */ /* * Global page accounting. One instance per CPU. */ extern struct page_state { unsigned long nr_dirty; unsigned long nr_writeback; unsigned long nr_pagecache; unsigned long nr_active; /* on active_list LRU */ unsigned long nr_inactive; /* on inactive_list LRU */ unsigned long nr_page_table_pages; unsigned long nr_reverse_maps; } ____cacheline_aligned_in_smp page_states[NR_CPUS]; extern void get_page_state(struct page_state *ret); #define mod_page_state(member, delta) \ do { \ preempt_disable(); \ page_states[smp_processor_id()].member += (delta); \ preempt_enable(); \ } while (0) #define inc_page_state(member) mod_page_state(member, 1UL) #define dec_page_state(member) mod_page_state(member, 0UL - 1) /* * 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) #define SetPageUptodate(page) set_bit(PG_uptodate, &(page)->flags) #define ClearPageUptodate(page) clear_bit(PG_uptodate, &(page)->flags) #define PageDirty(page) test_bit(PG_dirty_dontuse, &(page)->flags) #define SetPageDirty(page) \ do { \ if (!test_and_set_bit(PG_dirty_dontuse, \ &(page)->flags)) \ inc_page_state(nr_dirty); \ } while (0) #define TestSetPageDirty(page) \ ({ \ int ret; \ ret = test_and_set_bit(PG_dirty_dontuse, \ &(page)->flags); \ if (!ret) \ inc_page_state(nr_dirty); \ ret; \ }) #define ClearPageDirty(page) \ do { \ if (test_and_clear_bit(PG_dirty_dontuse, \ &(page)->flags)) \ dec_page_state(nr_dirty); \ } while (0) #define TestClearPageDirty(page) \ ({ \ int ret; \ ret = test_and_clear_bit(PG_dirty_dontuse, \ &(page)->flags); \ if (ret) \ dec_page_state(nr_dirty); \ ret; \ }) #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 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) 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 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) /* * inlines for acquisition and release of PG_chainlock */ static inline void pte_chain_lock(struct page *page) { /* * Assuming the lock is uncontended, this never enters * the body of the outer loop. If it is contended, then * within the inner loop a non-atomic test is used to * busywait with less bus contention for a good time to * attempt to acquire the lock bit. */ preempt_disable(); #ifdef CONFIG_SMP while (test_and_set_bit(PG_chainlock, &page->flags)) { while (test_bit(PG_chainlock, &page->flags)) cpu_relax(); } #endif } static inline void pte_chain_unlock(struct page *page) { #ifdef CONFIG_SMP smp_mb__before_clear_bit(); clear_bit(PG_chainlock, &page->flags); #endif preempt_enable(); } /* * The PageSwapCache predicate doesn't use a PG_flag at this time, * but it may again do so one day. */ extern struct address_space swapper_space; #define PageSwapCache(page) ((page)->mapping == &swapper_space) #endif /* PAGE_FLAGS_H */