EVOLUTION-MANAGER

Edit File: pagemap.h

#ifndef _LINUX_PAGEMAP_H #define _LINUX_PAGEMAP_H /* * Copyright 1995 Linus Torvalds */ #include <linux/mm.h> #include <linux/fs.h> #include <linux/list.h> #include <linux/highmem.h> #include <linux/compiler.h> #include <asm/uaccess.h> #include <linux/gfp.h> #include <linux/bitops.h> #include <linux/hardirq.h> /* for in_interrupt() */ #include <linux/hugetlb_inline.h> /* * Bits in mapping->flags. The lower __GFP_BITS_SHIFT bits are the page * allocation mode flags. */ enum mapping_flags { AS_EIO = __GFP_BITS_SHIFT + 0, /* IO error on async write */ AS_ENOSPC = __GFP_BITS_SHIFT + 1, /* ENOSPC on async write */ AS_MM_ALL_LOCKS = __GFP_BITS_SHIFT + 2, /* under mm_take_all_locks() */ AS_UNEVICTABLE = __GFP_BITS_SHIFT + 3, /* e.g., ramdisk, SHM_LOCK */ AS_EXITING = __GFP_BITS_SHIFT + 4, /* final truncate in progress */ /* writeback related tags are not used */ AS_NO_WRITEBACK_TAGS = __GFP_BITS_SHIFT + 5, }; static inline void mapping_set_error(struct address_space *mapping, int error) { if (unlikely(error)) { if (error == -ENOSPC) set_bit(AS_ENOSPC, &mapping->flags); else set_bit(AS_EIO, &mapping->flags); } } static inline void mapping_set_unevictable(struct address_space *mapping) { set_bit(AS_UNEVICTABLE, &mapping->flags); } static inline void mapping_clear_unevictable(struct address_space *mapping) { clear_bit(AS_UNEVICTABLE, &mapping->flags); } static inline int mapping_unevictable(struct address_space *mapping) { if (mapping) return test_bit(AS_UNEVICTABLE, &mapping->flags); return !!mapping; } static inline void mapping_set_exiting(struct address_space *mapping) { set_bit(AS_EXITING, &mapping->flags); } static inline int mapping_exiting(struct address_space *mapping) { return test_bit(AS_EXITING, &mapping->flags); } static inline void mapping_set_no_writeback_tags(struct address_space *mapping) { set_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags); } static inline int mapping_use_writeback_tags(struct address_space *mapping) { return !test_bit(AS_NO_WRITEBACK_TAGS, &mapping->flags); } static inline gfp_t mapping_gfp_mask(struct address_space * mapping) { return (__force gfp_t)mapping->flags & __GFP_BITS_MASK; } /* Restricts the given gfp_mask to what the mapping allows. */ static inline gfp_t mapping_gfp_constraint(struct address_space *mapping, gfp_t gfp_mask) { return mapping_gfp_mask(mapping) & gfp_mask; } /* * This is non-atomic. Only to be used before the mapping is activated. * Probably needs a barrier... */ static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask) { m->flags = (m->flags & ~(__force unsigned long)__GFP_BITS_MASK) | (__force unsigned long)mask; } /* * The page cache can done in larger chunks than * one page, because it allows for more efficient * throughput (it can then be mapped into user * space in smaller chunks for same flexibility). * * Or rather, it _will_ be done in larger chunks. */ #define PAGE_CACHE_SHIFT PAGE_SHIFT #define PAGE_CACHE_SIZE PAGE_SIZE #define PAGE_CACHE_MASK PAGE_MASK #define PAGE_CACHE_ALIGN(addr) (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK) #define page_cache_get(page) get_page(page) #define page_cache_release(page) put_page(page) void release_pages(struct page **pages, int nr, bool cold); /* * speculatively take a reference to a page. * If the page is free (_count == 0), then _count is untouched, and 0 * is returned. Otherwise, _count is incremented by 1 and 1 is returned. * * This function must be called inside the same rcu_read_lock() section as has * been used to lookup the page in the pagecache radix-tree (or page table): * this allows allocators to use a synchronize_rcu() to stabilize _count. * * Unless an RCU grace period has passed, the count of all pages coming out * of the allocator must be considered unstable. page_count may return higher * than expected, and put_page must be able to do the right thing when the * page has been finished with, no matter what it is subsequently allocated * for (because put_page is what is used here to drop an invalid speculative * reference). * * This is the interesting part of the lockless pagecache (and lockless * get_user_pages) locking protocol, where the lookup-side (eg. find_get_page) * has the following pattern: * 1. find page in radix tree * 2. conditionally increment refcount * 3. check the page is still in pagecache (if no, goto 1) * * Remove-side that cares about stability of _count (eg. reclaim) has the * following (with tree_lock held for write): * A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg) * B. remove page from pagecache * C. free the page * * There are 2 critical interleavings that matter: * - 2 runs before A: in this case, A sees elevated refcount and bails out * - A runs before 2: in this case, 2 sees zero refcount and retries; * subsequently, B will complete and 1 will find no page, causing the * lookup to return NULL. * * It is possible that between 1 and 2, the page is removed then the exact same * page is inserted into the same position in pagecache. That's OK: the * old find_get_page using tree_lock could equally have run before or after * such a re-insertion, depending on order that locks are granted. * * Lookups racing against pagecache insertion isn't a big problem: either 1 * will find the page or it will not. Likewise, the old find_get_page could run * either before the insertion or afterwards, depending on timing. */ static inline int page_cache_get_speculative(struct page *page) { VM_BUG_ON(in_interrupt()); #ifdef CONFIG_TINY_RCU # ifdef CONFIG_PREEMPT_COUNT VM_BUG_ON(!in_atomic()); # endif /* * Preempt must be disabled here - we rely on rcu_read_lock doing * this for us. * * Pagecache won't be truncated from interrupt context, so if we have * found a page in the radix tree here, we have pinned its refcount by * disabling preempt, and hence no need for the "speculative get" that * SMP requires. */ VM_BUG_ON_PAGE(page_count(page) == 0, page); page_ref_inc(page); #else if (unlikely(!get_page_unless_zero(page))) { /* * Either the page has been freed, or will be freed. * In either case, retry here and the caller should * do the right thing (see comments above). */ return 0; } #endif VM_BUG_ON_PAGE(PageTail(page), page); return 1; } /* * Same as above, but add instead of inc (could just be merged) */ static inline int page_cache_add_speculative(struct page *page, int count) { VM_BUG_ON(in_interrupt()); #if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU) # ifdef CONFIG_PREEMPT_COUNT VM_BUG_ON(!in_atomic()); # endif VM_BUG_ON_PAGE(page_count(page) == 0, page); page_ref_add(page, count); #else if (unlikely(!page_ref_add_unless(page, count, 0))) return 0; #endif VM_BUG_ON_PAGE(PageCompound(page) && page != compound_head(page), page); return 1; } /* * Return the compund head page with ref appropriately incremented, * or NULL if that failed. */ static inline struct page *try_get_compound_head(struct page *page, int refs) { struct page *head = compound_head(page); if (WARN_ON_ONCE(page_ref_count(head) < 0)) return NULL; if (unlikely(!page_cache_add_speculative(head, refs))) return NULL; return head; } #ifdef CONFIG_NUMA extern struct page *__page_cache_alloc(gfp_t gfp); #else static inline struct page *__page_cache_alloc(gfp_t gfp) { return alloc_pages(gfp, 0); } #endif static inline struct page *page_cache_alloc(struct address_space *x) { return __page_cache_alloc(mapping_gfp_mask(x)); } static inline struct page *page_cache_alloc_cold(struct address_space *x) { return __page_cache_alloc(mapping_gfp_mask(x)|__GFP_COLD); } static inline struct page *page_cache_alloc_readahead(struct address_space *x) { return __page_cache_alloc(mapping_gfp_mask(x) | __GFP_COLD | __GFP_NORETRY | __GFP_NOWARN); } typedef int filler_t(void *, struct page *); pgoff_t page_cache_next_hole(struct address_space *mapping, pgoff_t index, unsigned long max_scan); pgoff_t page_cache_prev_hole(struct address_space *mapping, pgoff_t index, unsigned long max_scan); struct page *__find_get_page(struct address_space *mapping, pgoff_t offset); struct page *find_get_page(struct address_space *mapping, pgoff_t offset); struct page *__find_lock_page(struct address_space *mapping, pgoff_t offset); struct page *find_lock_page(struct address_space *mapping, pgoff_t offset); struct page *find_or_create_page(struct address_space *mapping, pgoff_t index, gfp_t gfp_mask); unsigned __find_get_pages(struct address_space *mapping, pgoff_t start, unsigned int nr_pages, struct page **pages, pgoff_t *indices); unsigned find_get_pages(struct address_space *mapping, pgoff_t start, unsigned int nr_pages, struct page **pages); unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start, unsigned int nr_pages, struct page **pages); unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index, int tag, unsigned int nr_pages, struct page **pages); unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start, int tag, unsigned int nr_entries, struct page **entries, pgoff_t *indices); struct page *grab_cache_page_write_begin(struct address_space *mapping, pgoff_t index, unsigned flags); /* * Returns locked page at given index in given cache, creating it if needed. */ static inline struct page *grab_cache_page(struct address_space *mapping, pgoff_t index) { return find_or_create_page(mapping, index, mapping_gfp_mask(mapping)); } extern struct page * grab_cache_page_nowait(struct address_space *mapping, pgoff_t index); extern struct page * read_cache_page_async(struct address_space *mapping, pgoff_t index, filler_t *filler, void *data); extern struct page * read_cache_page(struct address_space *mapping, pgoff_t index, filler_t *filler, void *data); extern struct page * read_cache_page_gfp(struct address_space *mapping, pgoff_t index, gfp_t gfp_mask); extern int read_cache_pages(struct address_space *mapping, struct list_head *pages, filler_t *filler, void *data); static inline struct page *read_mapping_page_async( struct address_space *mapping, pgoff_t index, void *data) { filler_t *filler = (filler_t *)mapping->a_ops->readpage; return read_cache_page_async(mapping, index, filler, data); } static inline struct page *read_mapping_page(struct address_space *mapping, pgoff_t index, void *data) { filler_t *filler = (filler_t *)mapping->a_ops->readpage; return read_cache_page(mapping, index, filler, data); } /* * Get the offset in PAGE_SIZE. * (TODO: hugepage should have ->index in PAGE_SIZE) */ static inline pgoff_t page_to_pgoff(struct page *page) { if (unlikely(PageHeadHuge(page))) return page->index << compound_order(page); else return page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); } /* * Return byte-offset into filesystem object for page. */ static inline loff_t page_offset(struct page *page) { return ((loff_t)page->index) << PAGE_CACHE_SHIFT; } static inline loff_t page_file_offset(struct page *page) { return ((loff_t)page_file_index(page)) << PAGE_CACHE_SHIFT; } extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma, unsigned long address); static inline pgoff_t linear_page_index(struct vm_area_struct *vma, unsigned long address) { pgoff_t pgoff; if (unlikely(is_vm_hugetlb_page(vma))) return linear_hugepage_index(vma, address); pgoff = (address - vma->vm_start) >> PAGE_SHIFT; pgoff += vma->vm_pgoff; return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT); } extern void __lock_page(struct page *page); extern int __lock_page_killable(struct page *page); extern int __lock_page_or_retry(struct page *page, struct mm_struct *mm, unsigned int flags); extern void unlock_page(struct page *page); static inline void __set_page_locked(struct page *page) { __set_bit(PG_locked, &page->flags); } static inline void __clear_page_locked(struct page *page) { __clear_bit(PG_locked, &page->flags); } static inline int trylock_page(struct page *page) { return (likely(!test_and_set_bit_lock(PG_locked, &page->flags))); } /* * lock_page may only be called if we have the page's inode pinned. */ static inline void lock_page(struct page *page) { might_sleep(); if (!trylock_page(page)) __lock_page(page); } /* * lock_page_killable is like lock_page but can be interrupted by fatal * signals. It returns 0 if it locked the page and -EINTR if it was * killed while waiting. */ static inline int lock_page_killable(struct page *page) { might_sleep(); if (!trylock_page(page)) return __lock_page_killable(page); return 0; } /* * lock_page_or_retry - Lock the page, unless this would block and the * caller indicated that it can handle a retry. */ static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm, unsigned int flags) { might_sleep(); return trylock_page(page) || __lock_page_or_retry(page, mm, flags); } /* * This is exported only for wait_on_page_locked/wait_on_page_writeback, * and for filesystems which need to wait on PG_private. */ extern void wait_on_page_bit(struct page *page, int bit_nr); extern int wait_on_page_bit_killable(struct page *page, int bit_nr); extern int wait_on_page_bit_killable_timeout(struct page *page, int bit_nr, unsigned long timeout); static inline int wait_on_page_locked_killable(struct page *page) { if (PageLocked(page)) return wait_on_page_bit_killable(page, PG_locked); return 0; } extern wait_queue_head_t *page_waitqueue(struct page *page); static inline void wake_up_page(struct page *page, int bit) { __wake_up_bit(page_waitqueue(page), &page->flags, bit); } /* * Wait for a page to be unlocked. * * This must be called with the caller "holding" the page, * ie with increased "page->count" so that the page won't * go away during the wait.. */ static inline void wait_on_page_locked(struct page *page) { if (PageLocked(page)) wait_on_page_bit(page, PG_locked); } /* * Wait for a page to complete writeback */ static inline void wait_on_page_writeback(struct page *page) { if (PageWriteback(page)) wait_on_page_bit(page, PG_writeback); } extern void end_page_writeback(struct page *page); void wait_for_stable_page(struct page *page); void page_endio(struct page *page, int rw, int err); /* * Add an arbitrary waiter to a page's wait queue */ extern void add_page_wait_queue(struct page *page, wait_queue_t *waiter); /* * Fault a userspace page into pagetables. Return non-zero on a fault. * * This assumes that two userspace pages are always sufficient. That's * not true if PAGE_CACHE_SIZE > PAGE_SIZE. */ static inline int fault_in_pages_writeable(char __user *uaddr, int size) { int ret; if (unlikely(size == 0)) return 0; /* * Writing zeroes into userspace here is OK, because we know that if * the zero gets there, we'll be overwriting it. */ ret = __put_user(0, uaddr); if (ret == 0) { char __user *end = uaddr + size - 1; /* * If the page was already mapped, this will get a cache miss * for sure, so try to avoid doing it. */ if (((unsigned long)uaddr & PAGE_MASK) != ((unsigned long)end & PAGE_MASK)) ret = __put_user(0, end); } return ret; } static inline int fault_in_pages_readable(const char __user *uaddr, int size) { volatile char c; int ret; if (unlikely(size == 0)) return 0; ret = __get_user(c, uaddr); if (ret == 0) { const char __user *end = uaddr + size - 1; if (((unsigned long)uaddr & PAGE_MASK) != ((unsigned long)end & PAGE_MASK)) { ret = __get_user(c, end); (void)c; } } return ret; } /* * Multipage variants of the above prefault helpers, useful if more than * PAGE_SIZE of data needs to be prefaulted. These are separate from the above * functions (which only handle up to PAGE_SIZE) to avoid clobbering the * filemap.c hotpaths. */ static inline int fault_in_multipages_writeable(char __user *uaddr, int size) { int ret = 0; char __user *end = uaddr + size - 1; if (unlikely(size == 0)) return ret; /* * Writing zeroes into userspace here is OK, because we know that if * the zero gets there, we'll be overwriting it. */ while (uaddr <= end) { ret = __put_user(0, uaddr); if (ret != 0) return ret; uaddr += PAGE_SIZE; } /* Check whether the range spilled into the next page. */ if (((unsigned long)uaddr & PAGE_MASK) == ((unsigned long)end & PAGE_MASK)) ret = __put_user(0, end); return ret; } static inline int fault_in_multipages_readable(const char __user *uaddr, int size) { volatile char c; int ret = 0; const char __user *end = uaddr + size - 1; if (unlikely(size == 0)) return ret; while (uaddr <= end) { ret = __get_user(c, uaddr); if (ret != 0) return ret; uaddr += PAGE_SIZE; } /* Check whether the range spilled into the next page. */ if (((unsigned long)uaddr & PAGE_MASK) == ((unsigned long)end & PAGE_MASK)) { ret = __get_user(c, end); (void)c; } return ret; } int add_to_page_cache_locked(struct page *page, struct address_space *mapping, pgoff_t index, gfp_t gfp_mask); int add_to_page_cache_lru(struct page *page, struct address_space *mapping, pgoff_t index, gfp_t gfp_mask); extern void delete_from_page_cache(struct page *page); extern void __delete_from_page_cache(struct page *page, void *shadow); int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask); /* * Like add_to_page_cache_locked, but used to add newly allocated pages: * the page is new, so we can just run __set_page_locked() against it. */ static inline int add_to_page_cache(struct page *page, struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask) { int error; __set_page_locked(page); error = add_to_page_cache_locked(page, mapping, offset, gfp_mask); if (unlikely(error)) __clear_page_locked(page); return error; } #endif /* _LINUX_PAGEMAP_H */