WebSVN - shark - Blame - Rev 1618 - /shark/branches/xen/drivers/linuxc26/include/linux/pagemap.h

Rev	Author	Line No.	Line
422	giacomo	1	#ifndef _LINUX_PAGEMAP_H
		2	#define _LINUX_PAGEMAP_H
		3
		4	/*
		5	* Copyright 1995 Linus Torvalds
		6	*/
		7	#include <linux/mm.h>
		8	#include <linux/fs.h>
		9	#include <linux/list.h>
		10	#include <linux/highmem.h>
		11	#include <linux/pagemap.h>
		12	#include <asm/uaccess.h>
		13	#include <linux/gfp.h>
		14
		15	/*
		16	* Bits in mapping->flags. The lower __GFP_BITS_SHIFT bits are the page
		17	* allocation mode flags.
		18	*/
		19	#define AS_EIO (__GFP_BITS_SHIFT + 0) /* IO error on async write */
		20	#define AS_ENOSPC (__GFP_BITS_SHIFT + 1) /* ENOSPC on async write */
		21
		22	static inline int mapping_gfp_mask(struct address_space * mapping)
		23	{
		24	return mapping->flags & __GFP_BITS_MASK;
		25	}
		26
		27	/*
		28	* This is non-atomic. Only to be used before the mapping is activated.
		29	* Probably needs a barrier...
		30	*/
		31	static inline void mapping_set_gfp_mask(struct address_space *m, int mask)
		32	{
		33	m->flags = (m->flags & ~__GFP_BITS_MASK) \| mask;
		34	}
		35
		36	/*
		37	* The page cache can done in larger chunks than
		38	* one page, because it allows for more efficient
		39	* throughput (it can then be mapped into user
		40	* space in smaller chunks for same flexibility).
		41	*
		42	* Or rather, it _will_ be done in larger chunks.
		43	*/
		44	#define PAGE_CACHE_SHIFT PAGE_SHIFT
		45	#define PAGE_CACHE_SIZE PAGE_SIZE
		46	#define PAGE_CACHE_MASK PAGE_MASK
		47	#define PAGE_CACHE_ALIGN(addr) (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK)
		48
		49	#define page_cache_get(page) get_page(page)
		50	#define page_cache_release(page) put_page(page)
		51	void release_pages(struct page **pages, int nr, int cold);
		52
		53	static inline struct page page_cache_alloc(struct address_space x)
		54	{
		55	return alloc_pages(mapping_gfp_mask(x), 0);
		56	}
		57
		58	static inline struct page page_cache_alloc_cold(struct address_space x)
		59	{
		60	return alloc_pages(mapping_gfp_mask(x)\|__GFP_COLD, 0);
		61	}
		62
		63	typedef int filler_t(void , struct page );
		64
		65	extern struct page * find_get_page(struct address_space *mapping,
		66	unsigned long index);
		67	extern struct page * find_lock_page(struct address_space *mapping,
		68	unsigned long index);
		69	extern struct page * find_trylock_page(struct address_space *mapping,
		70	unsigned long index);
		71	extern struct page * find_or_create_page(struct address_space *mapping,
		72	unsigned long index, unsigned int gfp_mask);
		73	extern unsigned int find_get_pages(struct address_space *mapping,
		74	pgoff_t start, unsigned int nr_pages,
		75	struct page **pages);
		76
		77	/*
		78	* Returns locked page at given index in given cache, creating it if needed.
		79	*/
		80	static inline struct page grab_cache_page(struct address_space mapping, unsigned long index)
		81	{
		82	return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
		83	}
		84
		85	extern struct page * grab_cache_page_nowait(struct address_space *mapping,
		86	unsigned long index);
		87	extern struct page * read_cache_page(struct address_space *mapping,
		88	unsigned long index, filler_t *filler,
		89	void *data);
		90	extern int read_cache_pages(struct address_space *mapping,
		91	struct list_head pages, filler_t filler, void *data);
		92
		93	int add_to_page_cache(struct page page, struct address_space mapping,
		94	unsigned long index, int gfp_mask);
		95	int add_to_page_cache_lru(struct page page, struct address_space mapping,
		96	unsigned long index, int gfp_mask);
		97	extern void remove_from_page_cache(struct page *page);
		98	extern void __remove_from_page_cache(struct page *page);
		99
		100	extern atomic_t nr_pagecache;
		101
		102	#ifdef CONFIG_SMP
		103
		104	#define PAGECACHE_ACCT_THRESHOLD max(16, NR_CPUS * 2)
		105	DECLARE_PER_CPU(long, nr_pagecache_local);
		106
		107	/*
		108	* pagecache_acct implements approximate accounting for pagecache.
		109	* vm_enough_memory() do not need high accuracy. Writers will keep
		110	* an offset in their per-cpu arena and will spill that into the
		111	* global count whenever the absolute value of the local count
		112	* exceeds the counter's threshold.
		113	*
		114	* MUST be protected from preemption.
		115	* current protection is mapping->page_lock.
		116	*/
		117	static inline void pagecache_acct(int count)
		118	{
		119	long *local;
		120
		121	local = &__get_cpu_var(nr_pagecache_local);
		122	*local += count;
		123	if (local > PAGECACHE_ACCT_THRESHOLD \|\| local < -PAGECACHE_ACCT_THRESHOLD) {
		124	atomic_add(*local, &nr_pagecache);
		125	*local = 0;
		126	}
		127	}
		128
		129	#else
		130
		131	static inline void pagecache_acct(int count)
		132	{
		133	atomic_add(count, &nr_pagecache);
		134	}
		135	#endif
		136
		137	static inline unsigned long get_page_cache_size(void)
		138	{
		139	return atomic_read(&nr_pagecache);
		140	}
		141
		142	static inline void ___add_to_page_cache(struct page *page,
		143	struct address_space *mapping, unsigned long index)
		144	{
		145	list_add(&page->list, &mapping->clean_pages);
		146	page->mapping = mapping;
		147	page->index = index;
		148
		149	mapping->nrpages++;
		150	pagecache_acct(1);
		151	}
		152
		153	extern void FASTCALL(__lock_page(struct page *page));
		154	extern void FASTCALL(unlock_page(struct page *page));
		155
		156	static inline void lock_page(struct page *page)
		157	{
		158	if (TestSetPageLocked(page))
		159	__lock_page(page);
		160	}
		161
		162	/*
		163	* This is exported only for wait_on_page_locked/wait_on_page_writeback.
		164	* Never use this directly!
		165	*/
		166	extern void FASTCALL(wait_on_page_bit(struct page *page, int bit_nr));
		167
		168	/*
		169	* Wait for a page to be unlocked.
		170	*
		171	* This must be called with the caller "holding" the page,
		172	* ie with increased "page->count" so that the page won't
		173	* go away during the wait..
		174	*/
		175	static inline void wait_on_page_locked(struct page *page)
		176	{
		177	if (PageLocked(page))
		178	wait_on_page_bit(page, PG_locked);
		179	}
		180
		181	/*
		182	* Wait for a page to complete writeback
		183	*/
		184	static inline void wait_on_page_writeback(struct page *page)
		185	{
		186	if (PageWriteback(page))
		187	wait_on_page_bit(page, PG_writeback);
		188	}
		189
		190	extern void end_page_writeback(struct page *page);
		191
		192	/*
		193	* Fault a userspace page into pagetables. Return non-zero on a fault.
		194	*
		195	* This assumes that two userspace pages are always sufficient. That's
		196	* not true if PAGE_CACHE_SIZE > PAGE_SIZE.
		197	*/
		198	static inline int fault_in_pages_writeable(char __user *uaddr, int size)
		199	{
		200	int ret;
		201
		202	/*
		203	* Writing zeroes into userspace here is OK, because we know that if
		204	* the zero gets there, we'll be overwriting it.
		205	*/
		206	ret = __put_user(0, uaddr);
		207	if (ret == 0) {
		208	char __user *end = uaddr + size - 1;
		209
		210	/*
		211	* If the page was already mapped, this will get a cache miss
		212	* for sure, so try to avoid doing it.
		213	*/
		214	if (((unsigned long)uaddr & PAGE_MASK) !=
		215	((unsigned long)end & PAGE_MASK))
		216	ret = __put_user(0, end);
		217	}
		218	return ret;
		219	}
		220
		221	static inline void fault_in_pages_readable(const char __user *uaddr, int size)
		222	{
		223	volatile char c;
		224	int ret;
		225
		226	ret = __get_user(c, (char *)uaddr);
		227	if (ret == 0) {
		228	const char __user *end = uaddr + size - 1;
		229
		230	if (((unsigned long)uaddr & PAGE_MASK) !=
		231	((unsigned long)end & PAGE_MASK))
		232	__get_user(c, (char *)end);
		233	}
		234	}
		235
		236	#endif /* _LINUX_PAGEMAP_H */

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