[GitHub/mt8127/android_kernel_alcatel_ttab.git] / include / linux / 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_BALLOON_MAP  = __GFP_BITS_SHIFT + 4, /* balloon page special map */
};

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_balloon(struct address_space *mapping)
{
	set_bit(AS_BALLOON_MAP, &mapping->flags);
}

static inline void mapping_clear_balloon(struct address_space *mapping)
{
	clear_bit(AS_BALLOON_MAP, &mapping->flags);
}

static inline int mapping_balloon(struct address_space *mapping)
{
	return mapping && test_bit(AS_BALLOON_MAP, &mapping->flags);
}

static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
{
	return (__force gfp_t)mapping->flags & __GFP_BITS_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, int 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_count(page) == 0);
	atomic_inc(&page->_count);

#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(PageTail(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_count(page) == 0);
	atomic_add(count, &page->_count);

#else
	if (unlikely(!atomic_add_unless(&page->_count, count, 0)))
		return 0;
#endif
	VM_BUG_ON(PageCompound(page) && page != compound_head(page));

	return 1;
}

static inline int page_freeze_refs(struct page *page, int count)
{
	return likely(atomic_cmpxchg(&page->_count, count, 0) == count);
}

static inline void page_unfreeze_refs(struct page *page, int count)
{
	VM_BUG_ON(page_count(page) != 0);
	VM_BUG_ON(count == 0);

	atomic_set(&page->_count, count);
}

#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 *);

extern struct page * find_get_page(struct address_space *mapping,
				pgoff_t index);
extern struct page * find_lock_page(struct address_space *mapping,
				pgoff_t index);
extern 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);
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);

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);
}

/*
 * 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.
 * Never use this directly!
 */
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);

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;
}

/* 
 * 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);

/*
 * 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)
{
	char __user *end = uaddr + size - 1;

	if (unlikely(size == 0))
		return 0;

	if (unlikely(uaddr > end))
		return -EFAULT;
	/*
	 * Writing zeroes into userspace here is OK, because we know that if
	 * the zero gets there, we'll be overwriting it.
	 */
	do {
		if (unlikely(__put_user(0, uaddr) != 0))
			return -EFAULT;
		uaddr += PAGE_SIZE;
	} while (uaddr <= end);

	/* Check whether the range spilled into the next page. */
	if (((unsigned long)uaddr & PAGE_MASK) ==
			((unsigned long)end & PAGE_MASK))
		return __put_user(0, end);

	return 0;
}

static inline int fault_in_multipages_readable(const char __user *uaddr,
					       int size)
{
	volatile char c;
	const char __user *end = uaddr + size - 1;

	if (unlikely(size == 0))
		return 0;

	if (unlikely(uaddr > end))
		return -EFAULT;

	do {
		if (unlikely(__get_user(c, uaddr) != 0))
			return -EFAULT;
		uaddr += PAGE_SIZE;
	} while (uaddr <= end);

	/* Check whether the range spilled into the next page. */
	if (((unsigned long)uaddr & PAGE_MASK) ==
			((unsigned long)end & PAGE_MASK)) {
		return __get_user(c, end);
	}

	return 0;
}

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);
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 */
Commit	Line	Data
1da177e4 LT	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/compiler.h>
	12	#include <asm/uaccess.h>
	13	#include <linux/gfp.h>
3e9f45bd	14	#include <linux/bitops.h>
e286781d	15	#include <linux/hardirq.h> /* for in_interrupt() */
8edf344c	16	#include <linux/hugetlb_inline.h>
1da177e4 LT	17
	18	/*
	19	* Bits in mapping->flags. The lower __GFP_BITS_SHIFT bits are the page
	20	* allocation mode flags.
	21	*/
9a896c9a LS	22	enum mapping_flags {
	23	AS_EIO = __GFP_BITS_SHIFT + 0, /* IO error on async write */
	24	AS_ENOSPC = __GFP_BITS_SHIFT + 1, /* ENOSPC on async write */
	25	AS_MM_ALL_LOCKS = __GFP_BITS_SHIFT + 2, /* under mm_take_all_locks() */
9a896c9a	26	AS_UNEVICTABLE = __GFP_BITS_SHIFT + 3, /* e.g., ramdisk, SHM_LOCK */
18468d93	27	AS_BALLOON_MAP = __GFP_BITS_SHIFT + 4, /* balloon page special map */
9a896c9a	28	};
1da177e4	29
3e9f45bd GC	30	static inline void mapping_set_error(struct address_space *mapping, int error)
3e9f45bd GC	31	{
2185e69f	32	if (unlikely(error)) {
3e9f45bd GC	33	if (error == -ENOSPC)
	34	set_bit(AS_ENOSPC, &mapping->flags);
	35	else
	36	set_bit(AS_EIO, &mapping->flags);
	37	}
	38	}
	39
ba9ddf49 LS	40	static inline void mapping_set_unevictable(struct address_space *mapping)
	41	{
	42	set_bit(AS_UNEVICTABLE, &mapping->flags);
	43	}
	44
89e004ea LS	45	static inline void mapping_clear_unevictable(struct address_space *mapping)
	46	{
	47	clear_bit(AS_UNEVICTABLE, &mapping->flags);
	48	}
	49
ba9ddf49 LS	50	static inline int mapping_unevictable(struct address_space *mapping)
ba9ddf49 LS	51	{
088e5465	52	if (mapping)
89e004ea LS	53	return test_bit(AS_UNEVICTABLE, &mapping->flags);
89e004ea LS	54	return !!mapping;
ba9ddf49	55	}
ba9ddf49	56
18468d93 RA	57	static inline void mapping_set_balloon(struct address_space *mapping)
	58	{
	59	set_bit(AS_BALLOON_MAP, &mapping->flags);
	60	}
	61
	62	static inline void mapping_clear_balloon(struct address_space *mapping)
	63	{
	64	clear_bit(AS_BALLOON_MAP, &mapping->flags);
	65	}
	66
	67	static inline int mapping_balloon(struct address_space *mapping)
	68	{
	69	return mapping && test_bit(AS_BALLOON_MAP, &mapping->flags);
	70	}
	71
dd0fc66f	72	static inline gfp_t mapping_gfp_mask(struct address_space * mapping)
1da177e4	73	{
260b2367	74	return (__force gfp_t)mapping->flags & __GFP_BITS_MASK;
1da177e4 LT	75	}
	76
	77	/*
	78	* This is non-atomic. Only to be used before the mapping is activated.
	79	* Probably needs a barrier...
	80	*/
260b2367	81	static inline void mapping_set_gfp_mask(struct address_space *m, gfp_t mask)
1da177e4	82	{
260b2367 AV	83	m->flags = (m->flags & ~(__force unsigned long)__GFP_BITS_MASK) \|
260b2367 AV	84	(__force unsigned long)mask;
1da177e4 LT	85	}
	86
	87	/*
	88	* The page cache can done in larger chunks than
	89	* one page, because it allows for more efficient
	90	* throughput (it can then be mapped into user
	91	* space in smaller chunks for same flexibility).
	92	*
	93	* Or rather, it _will_ be done in larger chunks.
	94	*/
	95	#define PAGE_CACHE_SHIFT PAGE_SHIFT
	96	#define PAGE_CACHE_SIZE PAGE_SIZE
	97	#define PAGE_CACHE_MASK PAGE_MASK
	98	#define PAGE_CACHE_ALIGN(addr) (((addr)+PAGE_CACHE_SIZE-1)&PAGE_CACHE_MASK)
	99
	100	#define page_cache_get(page) get_page(page)
	101	#define page_cache_release(page) put_page(page)
	102	void release_pages(struct page **pages, int nr, int cold);
	103
e286781d NP	104	/*
	105	* speculatively take a reference to a page.
	106	* If the page is free (_count == 0), then _count is untouched, and 0
	107	* is returned. Otherwise, _count is incremented by 1 and 1 is returned.
	108	*
	109	* This function must be called inside the same rcu_read_lock() section as has
	110	* been used to lookup the page in the pagecache radix-tree (or page table):
	111	* this allows allocators to use a synchronize_rcu() to stabilize _count.
	112	*
	113	* Unless an RCU grace period has passed, the count of all pages coming out
	114	* of the allocator must be considered unstable. page_count may return higher
	115	* than expected, and put_page must be able to do the right thing when the
	116	* page has been finished with, no matter what it is subsequently allocated
	117	* for (because put_page is what is used here to drop an invalid speculative
	118	* reference).
	119	*
	120	* This is the interesting part of the lockless pagecache (and lockless
	121	* get_user_pages) locking protocol, where the lookup-side (eg. find_get_page)
	122	* has the following pattern:
	123	* 1. find page in radix tree
	124	* 2. conditionally increment refcount
	125	* 3. check the page is still in pagecache (if no, goto 1)
	126	*
	127	* Remove-side that cares about stability of _count (eg. reclaim) has the
	128	* following (with tree_lock held for write):
	129	* A. atomically check refcount is correct and set it to 0 (atomic_cmpxchg)
	130	* B. remove page from pagecache
	131	* C. free the page
	132	*
	133	* There are 2 critical interleavings that matter:
	134	* - 2 runs before A: in this case, A sees elevated refcount and bails out
	135	* - A runs before 2: in this case, 2 sees zero refcount and retries;
	136	* subsequently, B will complete and 1 will find no page, causing the
	137	* lookup to return NULL.
	138	*
	139	* It is possible that between 1 and 2, the page is removed then the exact same
	140	* page is inserted into the same position in pagecache. That's OK: the
	141	* old find_get_page using tree_lock could equally have run before or after
	142	* such a re-insertion, depending on order that locks are granted.
	143	*
	144	* Lookups racing against pagecache insertion isn't a big problem: either 1
	145	* will find the page or it will not. Likewise, the old find_get_page could run
	146	* either before the insertion or afterwards, depending on timing.
	147	*/
	148	static inline int page_cache_get_speculative(struct page *page)
	149	{
	150	VM_BUG_ON(in_interrupt());
	151
8375ad98	152	#ifdef CONFIG_TINY_RCU
bdd4e85d	153	# ifdef CONFIG_PREEMPT_COUNT
e286781d NP	154	VM_BUG_ON(!in_atomic());
	155	# endif
	156	/*
	157	* Preempt must be disabled here - we rely on rcu_read_lock doing
	158	* this for us.
	159	*
	160	* Pagecache won't be truncated from interrupt context, so if we have
	161	* found a page in the radix tree here, we have pinned its refcount by
	162	* disabling preempt, and hence no need for the "speculative get" that
	163	* SMP requires.
	164	*/
	165	VM_BUG_ON(page_count(page) == 0);
	166	atomic_inc(&page->_count);
	167
	168	#else
	169	if (unlikely(!get_page_unless_zero(page))) {
	170	/*
	171	* Either the page has been freed, or will be freed.
	172	* In either case, retry here and the caller should
	173	* do the right thing (see comments above).
	174	*/
	175	return 0;
	176	}
	177	#endif
	178	VM_BUG_ON(PageTail(page));
	179
	180	return 1;
	181	}
	182
ce0ad7f0 NP	183	/*
	184	* Same as above, but add instead of inc (could just be merged)
	185	*/
	186	static inline int page_cache_add_speculative(struct page *page, int count)
	187	{
	188	VM_BUG_ON(in_interrupt());
	189
b560d8ad	190	#if !defined(CONFIG_SMP) && defined(CONFIG_TREE_RCU)
bdd4e85d	191	# ifdef CONFIG_PREEMPT_COUNT
ce0ad7f0 NP	192	VM_BUG_ON(!in_atomic());
	193	# endif
	194	VM_BUG_ON(page_count(page) == 0);
	195	atomic_add(count, &page->_count);
	196
	197	#else
	198	if (unlikely(!atomic_add_unless(&page->_count, count, 0)))
	199	return 0;
	200	#endif
	201	VM_BUG_ON(PageCompound(page) && page != compound_head(page));
	202
	203	return 1;
	204	}
	205
e286781d NP	206	static inline int page_freeze_refs(struct page *page, int count)
	207	{
	208	return likely(atomic_cmpxchg(&page->_count, count, 0) == count);
	209	}
	210
	211	static inline void page_unfreeze_refs(struct page *page, int count)
	212	{
	213	VM_BUG_ON(page_count(page) != 0);
	214	VM_BUG_ON(count == 0);
	215
	216	atomic_set(&page->_count, count);
	217	}
	218
44110fe3	219	#ifdef CONFIG_NUMA
2ae88149	220	extern struct page *__page_cache_alloc(gfp_t gfp);
44110fe3	221	#else
2ae88149 NP	222	static inline struct page *__page_cache_alloc(gfp_t gfp)
	223	{
	224	return alloc_pages(gfp, 0);
	225	}
	226	#endif
	227
1da177e4 LT	228	static inline struct page page_cache_alloc(struct address_space x)
1da177e4 LT	229	{
2ae88149	230	return __page_cache_alloc(mapping_gfp_mask(x));
1da177e4 LT	231	}
	232
	233	static inline struct page page_cache_alloc_cold(struct address_space x)
	234	{
2ae88149	235	return __page_cache_alloc(mapping_gfp_mask(x)\|__GFP_COLD);
1da177e4 LT	236	}
1da177e4 LT	237
7b1de586 WF	238	static inline struct page page_cache_alloc_readahead(struct address_space x)
	239	{
	240	return __page_cache_alloc(mapping_gfp_mask(x) \|
	241	__GFP_COLD \| __GFP_NORETRY \| __GFP_NOWARN);
	242	}
	243
1da177e4 LT	244	typedef int filler_t(void , struct page );
	245
	246	extern struct page * find_get_page(struct address_space *mapping,
57f6b96c	247	pgoff_t index);
1da177e4	248	extern struct page * find_lock_page(struct address_space *mapping,
57f6b96c	249	pgoff_t index);
1da177e4	250	extern struct page * find_or_create_page(struct address_space *mapping,
57f6b96c	251	pgoff_t index, gfp_t gfp_mask);
1da177e4 LT	252	unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
1da177e4 LT	253	unsigned int nr_pages, struct page **pages);
ebf43500 JA	254	unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t start,
ebf43500 JA	255	unsigned int nr_pages, struct page **pages);
1da177e4 LT	256	unsigned find_get_pages_tag(struct address_space mapping, pgoff_t index,
	257	int tag, unsigned int nr_pages, struct page **pages);
	258
54566b2c NP	259	struct page grab_cache_page_write_begin(struct address_space mapping,
54566b2c NP	260	pgoff_t index, unsigned flags);
afddba49	261
1da177e4 LT	262	/*
	263	* Returns locked page at given index in given cache, creating it if needed.
	264	*/
57f6b96c FW	265	static inline struct page grab_cache_page(struct address_space mapping,
57f6b96c FW	266	pgoff_t index)
1da177e4 LT	267	{
	268	return find_or_create_page(mapping, index, mapping_gfp_mask(mapping));
	269	}
	270
	271	extern struct page * grab_cache_page_nowait(struct address_space *mapping,
57f6b96c	272	pgoff_t index);
6fe6900e	273	extern struct page * read_cache_page_async(struct address_space *mapping,
5e5358e7	274	pgoff_t index, filler_t filler, void data);
1da177e4	275	extern struct page * read_cache_page(struct address_space *mapping,
5e5358e7	276	pgoff_t index, filler_t filler, void data);
0531b2aa LT	277	extern struct page * read_cache_page_gfp(struct address_space *mapping,
0531b2aa LT	278	pgoff_t index, gfp_t gfp_mask);
1da177e4 LT	279	extern int read_cache_pages(struct address_space *mapping,
	280	struct list_head pages, filler_t filler, void *data);
	281
6fe6900e	282	static inline struct page *read_mapping_page_async(
5e5358e7 HD	283	struct address_space *mapping,
5e5358e7 HD	284	pgoff_t index, void *data)
6fe6900e NP	285	{
	286	filler_t filler = (filler_t )mapping->a_ops->readpage;
	287	return read_cache_page_async(mapping, index, filler, data);
	288	}
	289
090d2b18	290	static inline struct page read_mapping_page(struct address_space mapping,
5e5358e7	291	pgoff_t index, void *data)
090d2b18 PE	292	{
	293	filler_t filler = (filler_t )mapping->a_ops->readpage;
	294	return read_cache_page(mapping, index, filler, data);
	295	}
	296
1da177e4 LT	297	/*
	298	* Return byte-offset into filesystem object for page.
	299	*/
	300	static inline loff_t page_offset(struct page *page)
	301	{
	302	return ((loff_t)page->index) << PAGE_CACHE_SHIFT;
	303	}
	304
f981c595 MG	305	static inline loff_t page_file_offset(struct page *page)
	306	{
	307	return ((loff_t)page_file_index(page)) << PAGE_CACHE_SHIFT;
	308	}
	309
0fe6e20b NH	310	extern pgoff_t linear_hugepage_index(struct vm_area_struct *vma,
	311	unsigned long address);
	312
1da177e4 LT	313	static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
	314	unsigned long address)
	315	{
0fe6e20b NH	316	pgoff_t pgoff;
	317	if (unlikely(is_vm_hugetlb_page(vma)))
	318	return linear_hugepage_index(vma, address);
	319	pgoff = (address - vma->vm_start) >> PAGE_SHIFT;
1da177e4 LT	320	pgoff += vma->vm_pgoff;
	321	return pgoff >> (PAGE_CACHE_SHIFT - PAGE_SHIFT);
	322	}
	323
b3c97528 HH	324	extern void __lock_page(struct page *page);
b3c97528 HH	325	extern int __lock_page_killable(struct page *page);
d065bd81 ML	326	extern int __lock_page_or_retry(struct page page, struct mm_struct mm,
d065bd81 ML	327	unsigned int flags);
b3c97528	328	extern void unlock_page(struct page *page);
1da177e4	329
f45840b5	330	static inline void __set_page_locked(struct page *page)
529ae9aa	331	{
f45840b5	332	__set_bit(PG_locked, &page->flags);
529ae9aa NP	333	}
529ae9aa NP	334
f45840b5	335	static inline void __clear_page_locked(struct page *page)
529ae9aa	336	{
f45840b5	337	__clear_bit(PG_locked, &page->flags);
529ae9aa NP	338	}
	339
	340	static inline int trylock_page(struct page *page)
	341	{
8413ac9d	342	return (likely(!test_and_set_bit_lock(PG_locked, &page->flags)));
529ae9aa NP	343	}
529ae9aa NP	344
db37648c NP	345	/*
	346	* lock_page may only be called if we have the page's inode pinned.
	347	*/
1da177e4 LT	348	static inline void lock_page(struct page *page)
	349	{
	350	might_sleep();
529ae9aa	351	if (!trylock_page(page))
1da177e4 LT	352	__lock_page(page);
1da177e4 LT	353	}
db37648c	354
2687a356 MW	355	/*
	356	* lock_page_killable is like lock_page but can be interrupted by fatal
	357	* signals. It returns 0 if it locked the page and -EINTR if it was
	358	* killed while waiting.
	359	*/
	360	static inline int lock_page_killable(struct page *page)
	361	{
	362	might_sleep();
529ae9aa	363	if (!trylock_page(page))
2687a356 MW	364	return __lock_page_killable(page);
	365	return 0;
	366	}
	367
d065bd81 ML	368	/*
	369	* lock_page_or_retry - Lock the page, unless this would block and the
	370	* caller indicated that it can handle a retry.
	371	*/
	372	static inline int lock_page_or_retry(struct page page, struct mm_struct mm,
	373	unsigned int flags)
	374	{
	375	might_sleep();
	376	return trylock_page(page) \|\| __lock_page_or_retry(page, mm, flags);
	377	}
	378
1da177e4 LT	379	/*
	380	* This is exported only for wait_on_page_locked/wait_on_page_writeback.
	381	* Never use this directly!
	382	*/
b3c97528	383	extern void wait_on_page_bit(struct page *page, int bit_nr);
1da177e4	384
f62e00cc KM	385	extern int wait_on_page_bit_killable(struct page *page, int bit_nr);
	386
	387	static inline int wait_on_page_locked_killable(struct page *page)
	388	{
	389	if (PageLocked(page))
	390	return wait_on_page_bit_killable(page, PG_locked);
	391	return 0;
	392	}
	393
1da177e4 LT	394	/*
	395	* Wait for a page to be unlocked.
	396	*
	397	* This must be called with the caller "holding" the page,
	398	* ie with increased "page->count" so that the page won't
	399	* go away during the wait..
	400	*/
	401	static inline void wait_on_page_locked(struct page *page)
	402	{
	403	if (PageLocked(page))
	404	wait_on_page_bit(page, PG_locked);
	405	}
	406
	407	/*
	408	* Wait for a page to complete writeback
	409	*/
	410	static inline void wait_on_page_writeback(struct page *page)
	411	{
	412	if (PageWriteback(page))
	413	wait_on_page_bit(page, PG_writeback);
	414	}
	415
	416	extern void end_page_writeback(struct page *page);
1d1d1a76	417	void wait_for_stable_page(struct page *page);
1da177e4	418
385e1ca5 DH	419	/*
	420	* Add an arbitrary waiter to a page's wait queue
	421	*/
	422	extern void add_page_wait_queue(struct page page, wait_queue_t waiter);
	423
1da177e4 LT	424	/*
	425	* Fault a userspace page into pagetables. Return non-zero on a fault.
	426	*
	427	* This assumes that two userspace pages are always sufficient. That's
	428	* not true if PAGE_CACHE_SIZE > PAGE_SIZE.
	429	*/
	430	static inline int fault_in_pages_writeable(char __user *uaddr, int size)
	431	{
	432	int ret;
	433
08291429 NP	434	if (unlikely(size == 0))
	435	return 0;
	436
1da177e4 LT	437	/*
	438	* Writing zeroes into userspace here is OK, because we know that if
	439	* the zero gets there, we'll be overwriting it.
	440	*/
	441	ret = __put_user(0, uaddr);
	442	if (ret == 0) {
	443	char __user *end = uaddr + size - 1;
	444
	445	/*
	446	* If the page was already mapped, this will get a cache miss
	447	* for sure, so try to avoid doing it.
	448	*/
	449	if (((unsigned long)uaddr & PAGE_MASK) !=
	450	((unsigned long)end & PAGE_MASK))
f56f821f	451	ret = __put_user(0, end);
1da177e4 LT	452	}
	453	return ret;
	454	}
	455
08291429	456	static inline int fault_in_pages_readable(const char __user *uaddr, int size)
1da177e4 LT	457	{
	458	volatile char c;
	459	int ret;
	460
08291429 NP	461	if (unlikely(size == 0))
	462	return 0;
	463
1da177e4 LT	464	ret = __get_user(c, uaddr);
	465	if (ret == 0) {
	466	const char __user *end = uaddr + size - 1;
	467
	468	if (((unsigned long)uaddr & PAGE_MASK) !=
627295e4	469	((unsigned long)end & PAGE_MASK)) {
f56f821f	470	ret = __get_user(c, end);
627295e4 AK	471	(void)c;
627295e4 AK	472	}
1da177e4	473	}
08291429	474	return ret;
1da177e4 LT	475	}
1da177e4 LT	476
f56f821f DV	477	/*
	478	* Multipage variants of the above prefault helpers, useful if more than
	479	* PAGE_SIZE of data needs to be prefaulted. These are separate from the above
	480	* functions (which only handle up to PAGE_SIZE) to avoid clobbering the
	481	* filemap.c hotpaths.
	482	*/
	483	static inline int fault_in_multipages_writeable(char __user *uaddr, int size)
	484	{
9923777d	485	char __user *end = uaddr + size - 1;
f56f821f DV	486
f56f821f DV	487	if (unlikely(size == 0))
138c0121	488	return 0;
f56f821f	489
138c0121 AV	490	if (unlikely(uaddr > end))
138c0121 AV	491	return -EFAULT;
f56f821f DV	492	/*
	493	* Writing zeroes into userspace here is OK, because we know that if
	494	* the zero gets there, we'll be overwriting it.
	495	*/
138c0121 AV	496	do {
	497	if (unlikely(__put_user(0, uaddr) != 0))
	498	return -EFAULT;
f56f821f	499	uaddr += PAGE_SIZE;
138c0121	500	} while (uaddr <= end);
f56f821f DV	501
	502	/* Check whether the range spilled into the next page. */
	503	if (((unsigned long)uaddr & PAGE_MASK) ==
	504	((unsigned long)end & PAGE_MASK))
138c0121	505	return __put_user(0, end);
f56f821f	506
138c0121	507	return 0;
f56f821f DV	508	}
	509
	510	static inline int fault_in_multipages_readable(const char __user *uaddr,
	511	int size)
	512	{
	513	volatile char c;
f56f821f DV	514	const char __user *end = uaddr + size - 1;
	515
	516	if (unlikely(size == 0))
138c0121	517	return 0;
f56f821f	518
138c0121 AV	519	if (unlikely(uaddr > end))
	520	return -EFAULT;
	521
	522	do {
	523	if (unlikely(__get_user(c, uaddr) != 0))
	524	return -EFAULT;
f56f821f	525	uaddr += PAGE_SIZE;
138c0121	526	} while (uaddr <= end);
f56f821f DV	527
	528	/* Check whether the range spilled into the next page. */
	529	if (((unsigned long)uaddr & PAGE_MASK) ==
	530	((unsigned long)end & PAGE_MASK)) {
138c0121	531	return __get_user(c, end);
f56f821f DV	532	}
f56f821f DV	533
138c0121	534	return 0;
f56f821f DV	535	}
f56f821f DV	536
529ae9aa NP	537	int add_to_page_cache_locked(struct page page, struct address_space mapping,
	538	pgoff_t index, gfp_t gfp_mask);
	539	int add_to_page_cache_lru(struct page page, struct address_space mapping,
	540	pgoff_t index, gfp_t gfp_mask);
97cecb5a	541	extern void delete_from_page_cache(struct page *page);
e64a782f	542	extern void __delete_from_page_cache(struct page *page);
ef6a3c63	543	int replace_page_cache_page(struct page old, struct page new, gfp_t gfp_mask);
529ae9aa NP	544
	545	/*
	546	* Like add_to_page_cache_locked, but used to add newly allocated pages:
f45840b5	547	* the page is new, so we can just run __set_page_locked() against it.
529ae9aa NP	548	*/
	549	static inline int add_to_page_cache(struct page *page,
	550	struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask)
	551	{
	552	int error;
	553
f45840b5	554	__set_page_locked(page);
529ae9aa NP	555	error = add_to_page_cache_locked(page, mapping, offset, gfp_mask);
529ae9aa NP	556	if (unlikely(error))
f45840b5	557	__clear_page_locked(page);
529ae9aa NP	558	return error;
	559	}
	560
1da177e4	561	#endif /* _LINUX_PAGEMAP_H */