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246 lines
6.7 KiB
246 lines
6.7 KiB
#ifndef _LINUX_PAGEMAP_H
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#define _LINUX_PAGEMAP_H
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/*
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* Copyright 1995 Linus Torvalds
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*/
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#include <linux/mm.h>
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#include <linux/fs.h>
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#include <linux/list.h>
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#include <linux/highmem.h>
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#include <linux/compiler.h>
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#include <asm/uaccess.h>
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#include <linux/gfp.h>
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/*
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* Bits in mapping->flags. The lower __GFP_BITS_SHIFT bits are the page
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* allocation mode flags.
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*/
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#define AS_EIO (__GFP_BITS_SHIFT + 0) /* IO error on async write */
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#define AS_ENOSPC (__GFP_BITS_SHIFT + 1) /* ENOSPC on async write */
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static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
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{
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return mapping->flags & __GFP_BITS_MASK;
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}
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/*
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* This is non-atomic. Only to be used before the mapping is activated.
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* Probably needs a barrier...
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*/
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static inline void mapping_set_gfp_mask(struct address_space *m, int mask)
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{
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m->flags = (m->flags & ~__GFP_BITS_MASK) | mask;
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}
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/*
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* The page cache can done in larger chunks than
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* one page, because it allows for more efficient
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* throughput (it can then be mapped into user
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* space in smaller chunks for same flexibility).
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*
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* Or rather, it _will_ be done in larger chunks.
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*/
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#define PAGE_CACHE_SHIFT PAGE_SHIFT
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#define PAGE_CACHE_SIZE PAGE_SIZE
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#define PAGE_CACHE_MASK PAGE_MASK
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#define PAGE_CACHE_ALIGN(addr) (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK)
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#define page_cache_get(page) get_page(page)
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#define page_cache_release(page) put_page(page)
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void release_pages(struct page **pages, int nr, int cold);
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static inline struct page *page_cache_alloc(struct address_space *x)
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{
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return alloc_pages(mapping_gfp_mask(x)|__GFP_NORECLAIM, 0);
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}
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static inline struct page *page_cache_alloc_cold(struct address_space *x)
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{
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return alloc_pages(mapping_gfp_mask(x)|__GFP_COLD|__GFP_NORECLAIM, 0);
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}
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typedef int filler_t(void *, struct page *);
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extern struct page * find_get_page(struct address_space *mapping,
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unsigned long index);
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extern struct page * find_lock_page(struct address_space *mapping,
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unsigned long index);
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extern struct page * find_trylock_page(struct address_space *mapping,
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unsigned long index);
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extern struct page * find_or_create_page(struct address_space *mapping,
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unsigned long index, unsigned int gfp_mask);
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unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
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unsigned int nr_pages, struct page **pages);
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unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
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int tag, unsigned int nr_pages, struct page **pages);
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/*
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* Returns locked page at given index in given cache, creating it if needed.
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*/
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static inline struct page *grab_cache_page(struct address_space *mapping, unsigned long index)
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{
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return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
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}
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extern struct page * grab_cache_page_nowait(struct address_space *mapping,
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unsigned long index);
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extern struct page * read_cache_page(struct address_space *mapping,
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unsigned long index, filler_t *filler,
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void *data);
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extern int read_cache_pages(struct address_space *mapping,
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struct list_head *pages, filler_t *filler, void *data);
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int add_to_page_cache(struct page *page, struct address_space *mapping,
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unsigned long index, int gfp_mask);
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int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
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unsigned long index, int gfp_mask);
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extern void remove_from_page_cache(struct page *page);
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extern void __remove_from_page_cache(struct page *page);
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extern atomic_t nr_pagecache;
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#ifdef CONFIG_SMP
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#define PAGECACHE_ACCT_THRESHOLD max(16, NR_CPUS * 2)
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DECLARE_PER_CPU(long, nr_pagecache_local);
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/*
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* pagecache_acct implements approximate accounting for pagecache.
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* vm_enough_memory() do not need high accuracy. Writers will keep
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* an offset in their per-cpu arena and will spill that into the
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* global count whenever the absolute value of the local count
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* exceeds the counter's threshold.
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*
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* MUST be protected from preemption.
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* current protection is mapping->page_lock.
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*/
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static inline void pagecache_acct(int count)
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{
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long *local;
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local = &__get_cpu_var(nr_pagecache_local);
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*local += count;
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if (*local > PAGECACHE_ACCT_THRESHOLD || *local < -PAGECACHE_ACCT_THRESHOLD) {
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atomic_add(*local, &nr_pagecache);
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*local = 0;
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}
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}
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#else
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static inline void pagecache_acct(int count)
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{
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atomic_add(count, &nr_pagecache);
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}
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#endif
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static inline unsigned long get_page_cache_size(void)
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{
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int ret = atomic_read(&nr_pagecache);
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if (unlikely(ret < 0))
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ret = 0;
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return ret;
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}
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/*
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* Return byte-offset into filesystem object for page.
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*/
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static inline loff_t page_offset(struct page *page)
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{
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return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
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}
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static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
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unsigned long address)
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{
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pgoff_t pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
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pgoff += vma->vm_pgoff;
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return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT);
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}
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extern void FASTCALL(__lock_page(struct page *page));
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extern void FASTCALL(unlock_page(struct page *page));
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static inline void lock_page(struct page *page)
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{
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might_sleep();
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if (TestSetPageLocked(page))
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__lock_page(page);
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}
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/*
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* This is exported only for wait_on_page_locked/wait_on_page_writeback.
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* Never use this directly!
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*/
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extern void FASTCALL(wait_on_page_bit(struct page *page, int bit_nr));
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/*
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* Wait for a page to be unlocked.
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*
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* This must be called with the caller "holding" the page,
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* ie with increased "page->count" so that the page won't
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* go away during the wait..
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*/
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static inline void wait_on_page_locked(struct page *page)
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{
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if (PageLocked(page))
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wait_on_page_bit(page, PG_locked);
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}
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/*
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* Wait for a page to complete writeback
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*/
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static inline void wait_on_page_writeback(struct page *page)
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{
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if (PageWriteback(page))
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wait_on_page_bit(page, PG_writeback);
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}
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extern void end_page_writeback(struct page *page);
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/*
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* Fault a userspace page into pagetables. Return non-zero on a fault.
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*
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* This assumes that two userspace pages are always sufficient. That's
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* not true if PAGE_CACHE_SIZE > PAGE_SIZE.
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*/
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static inline int fault_in_pages_writeable(char __user *uaddr, int size)
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{
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int ret;
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/*
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* Writing zeroes into userspace here is OK, because we know that if
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* the zero gets there, we'll be overwriting it.
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*/
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ret = __put_user(0, uaddr);
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if (ret == 0) {
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char __user *end = uaddr + size - 1;
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/*
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* If the page was already mapped, this will get a cache miss
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* for sure, so try to avoid doing it.
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*/
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if (((unsigned long)uaddr & PAGE_MASK) !=
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((unsigned long)end & PAGE_MASK))
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ret = __put_user(0, end);
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}
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return ret;
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}
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static inline void fault_in_pages_readable(const char __user *uaddr, int size)
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{
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volatile char c;
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int ret;
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ret = __get_user(c, uaddr);
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if (ret == 0) {
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const char __user *end = uaddr + size - 1;
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if (((unsigned long)uaddr & PAGE_MASK) !=
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((unsigned long)end & PAGE_MASK))
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__get_user(c, end);
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}
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}
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#endif /* _LINUX_PAGEMAP_H */
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