[mirror_ubuntu-zesty-kernel.git] / include / linux / page-flags.h

/*
 * Macros for manipulating and testing page->flags
 */

#ifndef PAGE_FLAGS_H
#define PAGE_FLAGS_H

#include <linux/types.h>
#ifndef __GENERATING_BOUNDS_H
#include <linux/mm_types.h>
#include <linux/bounds.h>
#endif /* !__GENERATING_BOUNDS_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 on pagecache pages if they contain filesystem
 * specific data (which is normally at page->private). It can be used by
 * private allocations for its own usage.
 *
 * During initiation of disk I/O, PG_locked is set. This bit is set before I/O
 * and cleared when writeback _starts_ or when read _completes_. PG_writeback
 * is set before writeback starts and cleared when it finishes.
 *
 * PG_locked also pins a page in pagecache, and blocks truncation of the file
 * while it is held.
 *
 * page_waitqueue(page) is a wait queue of all tasks waiting for the page
 * to become unlocked.
 *
 * 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.
 *
 * PG_referenced, PG_reclaim are used for page reclaim for anonymous and
 * file-backed pagecache (see mm/vmscan.c).
 *
 * 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...
 *
 * PG_buddy is set to indicate that the page is free and in the buddy system
 * (see mm/page_alloc.c).
 *
 */

/*
 * Don't use the *_dontuse flags.  Use the macros.  Otherwise you'll break
 * locked- and dirty-page accounting.
 *
 * The page flags field is split into two parts, the main flags area
 * which extends from the low bits upwards, and the fields area which
 * extends from the high bits downwards.
 *
 *  | FIELD | ... | FLAGS |
 *  N-1           ^       0
 *               (NR_PAGEFLAGS)
 *
 * The fields area is reserved for fields mapping zone, node (for NUMA) and
 * SPARSEMEM section (for variants of SPARSEMEM that require section ids like
 * SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP).
 */
enum pageflags {
	PG_locked,		/* Page is locked. Don't touch. */
	PG_error,
	PG_referenced,
	PG_uptodate,
	PG_dirty,
	PG_lru,
	PG_active,
	PG_slab,
	PG_owner_priv_1,	/* Owner use. If pagecache, fs may use*/
	PG_checked = PG_owner_priv_1, /* Used by some filesystems */
	PG_pinned = PG_owner_priv_1, /* Xen pinned pagetable */
	PG_arch_1,
	PG_reserved,
	PG_private,		/* If pagecache, has fs-private data */
	PG_writeback,		/* Page is under writeback */
	PG_compound,		/* A compound page */
	PG_swapcache,		/* Swap page: swp_entry_t in private */
	PG_mappedtodisk,	/* Has blocks allocated on-disk */
	PG_reclaim,		/* To be reclaimed asap */
	/* PG_readahead is only used for file reads; PG_reclaim is only for writes */
	PG_readahead = PG_reclaim, /* Reminder to do async read-ahead */
	PG_buddy,		/* Page is free, on buddy lists */

#if (BITS_PER_LONG > 32)
/*
 * 64-bit-only flags build down from bit 31
 *
 * 32 bit  -------------------------------| FIELDS |       FLAGS         |
 * 64 bit  |           FIELDS             | ??????         FLAGS         |
 *         63                            32                              0
 */
	PG_uncached = 31,		/* Page has been mapped as uncached */
#endif
	__NR_PAGEFLAGS
};

#ifndef __GENERATING_BOUNDS_H

/*
 * Macros to create function definitions for page flags
 */
#define TESTPAGEFLAG(uname, lname)					\
static inline int Page##uname(struct page *page) 			\
			{ return test_bit(PG_##lname, &page->flags); }

#define SETPAGEFLAG(uname, lname)					\
static inline void SetPage##uname(struct page *page)			\
			{ set_bit(PG_##lname, &page->flags); }

#define CLEARPAGEFLAG(uname, lname)					\
static inline void ClearPage##uname(struct page *page)			\
			{ clear_bit(PG_##lname, &page->flags); }

#define __SETPAGEFLAG(uname, lname)					\
static inline void __SetPage##uname(struct page *page)			\
			{ __set_bit(PG_##lname, &page->flags); }

#define __CLEARPAGEFLAG(uname, lname)					\
static inline void __ClearPage##uname(struct page *page)		\
			{ __clear_bit(PG_##lname, &page->flags); }

#define TESTSETFLAG(uname, lname)					\
static inline int TestSetPage##uname(struct page *page)			\
		{ return test_and_set_bit(PG_##lname, &page->flags); }

#define TESTCLEARFLAG(uname, lname)					\
static inline int TestClearPage##uname(struct page *page)		\
		{ return test_and_clear_bit(PG_##lname, &page->flags); }


#define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname)		\
	SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname)

#define __PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname)		\
	__SETPAGEFLAG(uname, lname)  __CLEARPAGEFLAG(uname, lname)

#define TESTSCFLAG(uname, lname)					\
	TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname)

struct page;	/* forward declaration */

PAGEFLAG(Locked, locked) TESTSCFLAG(Locked, locked)
PAGEFLAG(Error, error)
PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced)
PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty)
PAGEFLAG(LRU, lru) __CLEARPAGEFLAG(LRU, lru)
PAGEFLAG(Active, active) __CLEARPAGEFLAG(Active, active)
__PAGEFLAG(Slab, slab)
PAGEFLAG(Checked, checked)		/* Used by some filesystems */
PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned) /* Xen pagetable */
PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)
PAGEFLAG(Private, private) __CLEARPAGEFLAG(Private, private)
	__SETPAGEFLAG(Private, private)

/*
 * Only test-and-set exist for PG_writeback.  The unconditional operators are
 * risky: they bypass page accounting.
 */
TESTPAGEFLAG(Writeback, writeback) TESTSCFLAG(Writeback, writeback)
__PAGEFLAG(Buddy, buddy)
PAGEFLAG(MappedToDisk, mappedtodisk)

/* PG_readahead is only used for file reads; PG_reclaim is only for writes */
PAGEFLAG(Reclaim, reclaim) TESTCLEARFLAG(Reclaim, reclaim)
PAGEFLAG(Readahead, readahead)		/* Reminder to do async read-ahead */

#ifdef CONFIG_HIGHMEM
/*
 * Must use a macro here due to header dependency issues. page_zone() is not
 * available at this point.
 */
#define PageHighMem(__p) is_highmem(page_zone(page))
#else
static inline int PageHighMem(struct page *page)
{
	return 0;
}
#endif

#ifdef CONFIG_SWAP
PAGEFLAG(SwapCache, swapcache)
#else
static inline int PageSwapCache(struct page *page)
{
	return 0;
}
#endif

#if (BITS_PER_LONG > 32)
PAGEFLAG(Uncached, uncached)
#endif

static inline int PageUptodate(struct page *page)
{
	int ret = test_bit(PG_uptodate, &(page)->flags);

	/*
	 * Must ensure that the data we read out of the page is loaded
	 * _after_ we've loaded page->flags to check for PageUptodate.
	 * We can skip the barrier if the page is not uptodate, because
	 * we wouldn't be reading anything from it.
	 *
	 * See SetPageUptodate() for the other side of the story.
	 */
	if (ret)
		smp_rmb();

	return ret;
}

static inline void __SetPageUptodate(struct page *page)
{
	smp_wmb();
	__set_bit(PG_uptodate, &(page)->flags);
#ifdef CONFIG_S390
	page_clear_dirty(page);
#endif
}

static inline void SetPageUptodate(struct page *page)
{
#ifdef CONFIG_S390
	if (!test_and_set_bit(PG_uptodate, &page->flags))
		page_clear_dirty(page);
#else
	/*
	 * Memory barrier must be issued before setting the PG_uptodate bit,
	 * so that all previous stores issued in order to bring the page
	 * uptodate are actually visible before PageUptodate becomes true.
	 *
	 * s390 doesn't need an explicit smp_wmb here because the test and
	 * set bit already provides full barriers.
	 */
	smp_wmb();
	set_bit(PG_uptodate, &(page)->flags);
#endif
}

CLEARPAGEFLAG(Uptodate, uptodate)

extern void cancel_dirty_page(struct page *page, unsigned int account_size);

int test_clear_page_writeback(struct page *page);
int test_set_page_writeback(struct page *page);

static inline void set_page_writeback(struct page *page)
{
	test_set_page_writeback(page);
}

TESTPAGEFLAG(Compound, compound)
__PAGEFLAG(Head, compound)

/*
 * PG_reclaim is used in combination with PG_compound to mark the
 * head and tail of a compound page. This saves one page flag
 * but makes it impossible to use compound pages for the page cache.
 * The PG_reclaim bit would have to be used for reclaim or readahead
 * if compound pages enter the page cache.
 *
 * PG_compound & PG_reclaim	=> Tail page
 * PG_compound & ~PG_reclaim	=> Head page
 */
#define PG_head_tail_mask ((1L << PG_compound) | (1L << PG_reclaim))

static inline int PageTail(struct page *page)
{
	return ((page->flags & PG_head_tail_mask) == PG_head_tail_mask);
}

static inline void __SetPageTail(struct page *page)
{
	page->flags |= PG_head_tail_mask;
}

static inline void __ClearPageTail(struct page *page)
{
	page->flags &= ~PG_head_tail_mask;
}

#endif /* !__GENERATING_BOUNDS_H */
#endif	/* PAGE_FLAGS_H */
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Macros for manipulating and testing page->flags
	3	*/
	4
	5	#ifndef PAGE_FLAGS_H
	6	#define PAGE_FLAGS_H
	7
f886ed44	8	#include <linux/types.h>
9223b419	9	#ifndef __GENERATING_BOUNDS_H
6d777953	10	#include <linux/mm_types.h>
9223b419 CL	11	#include <linux/bounds.h>
9223b419 CL	12	#endif /* !__GENERATING_BOUNDS_H */
f886ed44	13
1da177e4 LT	14	/*
	15	* Various page->flags bits:
	16	*
	17	* PG_reserved is set for special pages, which can never be swapped out. Some
	18	* of them might not even exist (eg empty_bad_page)...
	19	*
da6052f7 NP	20	* The PG_private bitflag is set on pagecache pages if they contain filesystem
	21	* specific data (which is normally at page->private). It can be used by
	22	* private allocations for its own usage.
1da177e4	23	*
da6052f7 NP	24	* During initiation of disk I/O, PG_locked is set. This bit is set before I/O
	25	* and cleared when writeback _starts_ or when read _completes_. PG_writeback
	26	* is set before writeback starts and cleared when it finishes.
	27	*
	28	* PG_locked also pins a page in pagecache, and blocks truncation of the file
	29	* while it is held.
	30	*
	31	* page_waitqueue(page) is a wait queue of all tasks waiting for the page
	32	* to become unlocked.
1da177e4 LT	33	*
	34	* PG_uptodate tells whether the page's contents is valid. When a read
	35	* completes, the page becomes uptodate, unless a disk I/O error happened.
	36	*
da6052f7 NP	37	* PG_referenced, PG_reclaim are used for page reclaim for anonymous and
da6052f7 NP	38	* file-backed pagecache (see mm/vmscan.c).
1da177e4 LT	39	*
	40	* PG_error is set to indicate that an I/O error occurred on this page.
	41	*
	42	* PG_arch_1 is an architecture specific page state bit. The generic code
	43	* guarantees that this bit is cleared for a page when it first is entered into
	44	* the page cache.
	45	*
	46	* PG_highmem pages are not permanently mapped into the kernel virtual address
	47	* space, they need to be kmapped separately for doing IO on the pages. The
	48	* struct page (these bits with information) are always mapped into kernel
	49	* address space...
da6052f7 NP	50	*
	51	* PG_buddy is set to indicate that the page is free and in the buddy system
	52	* (see mm/page_alloc.c).
	53	*
1da177e4 LT	54	*/
	55
	56	/*
	57	* Don't use the *_dontuse flags. Use the macros. Otherwise you'll break
91fc8ab3 AW	58	* locked- and dirty-page accounting.
	59	*
	60	* The page flags field is split into two parts, the main flags area
	61	* which extends from the low bits upwards, and the fields area which
	62	* extends from the high bits downwards.
	63	*
	64	* \| FIELD \| ... \| FLAGS \|
9223b419 CL	65	* N-1 ^ 0
9223b419 CL	66	* (NR_PAGEFLAGS)
91fc8ab3	67	*
9223b419 CL	68	* The fields area is reserved for fields mapping zone, node (for NUMA) and
	69	* SPARSEMEM section (for variants of SPARSEMEM that require section ids like
	70	* SPARSEMEM_EXTREME with !SPARSEMEM_VMEMMAP).
1da177e4	71	*/
e2683181 CL	72	enum pageflags {
	73	PG_locked, /* Page is locked. Don't touch. */
	74	PG_error,
	75	PG_referenced,
	76	PG_uptodate,
	77	PG_dirty,
	78	PG_lru,
	79	PG_active,
	80	PG_slab,
	81	PG_owner_priv_1, /* Owner use. If pagecache, fs may use*/
	82	PG_checked = PG_owner_priv_1, /* Used by some filesystems */
	83	PG_pinned = PG_owner_priv_1, /* Xen pinned pagetable */
	84	PG_arch_1,
	85	PG_reserved,
	86	PG_private, /* If pagecache, has fs-private data */
	87	PG_writeback, /* Page is under writeback */
	88	PG_compound, /* A compound page */
	89	PG_swapcache, /* Swap page: swp_entry_t in private */
	90	PG_mappedtodisk, /* Has blocks allocated on-disk */
	91	PG_reclaim, /* To be reclaimed asap */
	92	/* PG_readahead is only used for file reads; PG_reclaim is only for writes */
	93	PG_readahead = PG_reclaim, /* Reminder to do async read-ahead */
	94	PG_buddy, /* Page is free, on buddy lists */
f886ed44 AM	95
	96	#if (BITS_PER_LONG > 32)
	97	/*
	98	* 64-bit-only flags build down from bit 31
	99	*
	100	* 32 bit -------------------------------\| FIELDS \| FLAGS \|
	101	* 64 bit \| FIELDS \| ?????? FLAGS \|
	102	* 63 32 0
	103	*/
e2683181	104	PG_uncached = 31, /* Page has been mapped as uncached */
f886ed44	105	#endif
9223b419	106	__NR_PAGEFLAGS
e2683181	107	};
1da177e4	108
9223b419 CL	109	#ifndef __GENERATING_BOUNDS_H
9223b419 CL	110
f94a62e9 CL	111	/*
	112	* Macros to create function definitions for page flags
	113	*/
	114	#define TESTPAGEFLAG(uname, lname) \
	115	static inline int Page##uname(struct page *page) \
	116	{ return test_bit(PG_##lname, &page->flags); }
	117
	118	#define SETPAGEFLAG(uname, lname) \
	119	static inline void SetPage##uname(struct page *page) \
	120	{ set_bit(PG_##lname, &page->flags); }
	121
	122	#define CLEARPAGEFLAG(uname, lname) \
	123	static inline void ClearPage##uname(struct page *page) \
	124	{ clear_bit(PG_##lname, &page->flags); }
	125
	126	#define __SETPAGEFLAG(uname, lname) \
	127	static inline void __SetPage##uname(struct page *page) \
	128	{ __set_bit(PG_##lname, &page->flags); }
	129
	130	#define __CLEARPAGEFLAG(uname, lname) \
	131	static inline void __ClearPage##uname(struct page *page) \
	132	{ __clear_bit(PG_##lname, &page->flags); }
	133
	134	#define TESTSETFLAG(uname, lname) \
	135	static inline int TestSetPage##uname(struct page *page) \
	136	{ return test_and_set_bit(PG_##lname, &page->flags); }
	137
	138	#define TESTCLEARFLAG(uname, lname) \
	139	static inline int TestClearPage##uname(struct page *page) \
	140	{ return test_and_clear_bit(PG_##lname, &page->flags); }
	141
	142
	143	#define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
	144	SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname)
	145
	146	#define __PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
	147	__SETPAGEFLAG(uname, lname) __CLEARPAGEFLAG(uname, lname)
	148
	149	#define TESTSCFLAG(uname, lname) \
	150	TESTSETFLAG(uname, lname) TESTCLEARFLAG(uname, lname)
	151
6a1e7f77 CL	152	struct page; /* forward declaration */
	153
	154	PAGEFLAG(Locked, locked) TESTSCFLAG(Locked, locked)
	155	PAGEFLAG(Error, error)
	156	PAGEFLAG(Referenced, referenced) TESTCLEARFLAG(Referenced, referenced)
	157	PAGEFLAG(Dirty, dirty) TESTSCFLAG(Dirty, dirty) __CLEARPAGEFLAG(Dirty, dirty)
	158	PAGEFLAG(LRU, lru) __CLEARPAGEFLAG(LRU, lru)
	159	PAGEFLAG(Active, active) __CLEARPAGEFLAG(Active, active)
	160	__PAGEFLAG(Slab, slab)
	161	PAGEFLAG(Checked, checked) /* Used by some filesystems */
d60cd46b	162	PAGEFLAG(Pinned, pinned) TESTSCFLAG(Pinned, pinned) /* Xen pagetable */
6a1e7f77 CL	163	PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)
	164	PAGEFLAG(Private, private) __CLEARPAGEFLAG(Private, private)
	165	__SETPAGEFLAG(Private, private)
	166
	167	/*
	168	* Only test-and-set exist for PG_writeback. The unconditional operators are
	169	* risky: they bypass page accounting.
	170	*/
	171	TESTPAGEFLAG(Writeback, writeback) TESTSCFLAG(Writeback, writeback)
	172	__PAGEFLAG(Buddy, buddy)
	173	PAGEFLAG(MappedToDisk, mappedtodisk)
	174
	175	/* PG_readahead is only used for file reads; PG_reclaim is only for writes */
	176	PAGEFLAG(Reclaim, reclaim) TESTCLEARFLAG(Reclaim, reclaim)
	177	PAGEFLAG(Readahead, readahead) /* Reminder to do async read-ahead */
	178
	179	#ifdef CONFIG_HIGHMEM
1da177e4	180	/*
6a1e7f77 CL	181	* Must use a macro here due to header dependency issues. page_zone() is not
6a1e7f77 CL	182	* available at this point.
1da177e4	183	*/
6a1e7f77 CL	184	#define PageHighMem(__p) is_highmem(page_zone(page))
	185	#else
	186	static inline int PageHighMem(struct page *page)
	187	{
	188	return 0;
	189	}
	190	#endif
	191
	192	#ifdef CONFIG_SWAP
	193	PAGEFLAG(SwapCache, swapcache)
	194	#else
	195	static inline int PageSwapCache(struct page *page)
	196	{
	197	return 0;
	198	}
	199	#endif
	200
	201	#if (BITS_PER_LONG > 32)
	202	PAGEFLAG(Uncached, uncached)
	203	#endif
1da177e4	204
0ed361de NP	205	static inline int PageUptodate(struct page *page)
	206	{
	207	int ret = test_bit(PG_uptodate, &(page)->flags);
	208
	209	/*
	210	* Must ensure that the data we read out of the page is loaded
	211	* _after_ we've loaded page->flags to check for PageUptodate.
	212	* We can skip the barrier if the page is not uptodate, because
	213	* we wouldn't be reading anything from it.
	214	*
	215	* See SetPageUptodate() for the other side of the story.
	216	*/
	217	if (ret)
	218	smp_rmb();
	219
	220	return ret;
	221	}
	222
	223	static inline void __SetPageUptodate(struct page *page)
	224	{
	225	smp_wmb();
	226	__set_bit(PG_uptodate, &(page)->flags);
f6ac2354	227	#ifdef CONFIG_S390
0ed361de NP	228	page_clear_dirty(page);
	229	#endif
	230	}
	231
2dcea57a HC	232	static inline void SetPageUptodate(struct page *page)
2dcea57a HC	233	{
0ed361de	234	#ifdef CONFIG_S390
2dcea57a	235	if (!test_and_set_bit(PG_uptodate, &page->flags))
6c210482	236	page_clear_dirty(page);
f6ac2354	237	#else
0ed361de NP	238	/*
	239	* Memory barrier must be issued before setting the PG_uptodate bit,
	240	* so that all previous stores issued in order to bring the page
	241	* uptodate are actually visible before PageUptodate becomes true.
	242	*
	243	* s390 doesn't need an explicit smp_wmb here because the test and
	244	* set bit already provides full barriers.
	245	*/
	246	smp_wmb();
	247	set_bit(PG_uptodate, &(page)->flags);
1da177e4	248	#endif
0ed361de NP	249	}
0ed361de NP	250
6a1e7f77	251	CLEARPAGEFLAG(Uptodate, uptodate)
1da177e4	252
6a1e7f77	253	extern void cancel_dirty_page(struct page *page, unsigned int account_size);
d77c2d7c	254
6a1e7f77 CL	255	int test_clear_page_writeback(struct page *page);
6a1e7f77 CL	256	int test_set_page_writeback(struct page *page);
1da177e4	257
6a1e7f77 CL	258	static inline void set_page_writeback(struct page *page)
	259	{
	260	test_set_page_writeback(page);
	261	}
1da177e4	262
6a1e7f77 CL	263	TESTPAGEFLAG(Compound, compound)
6a1e7f77 CL	264	__PAGEFLAG(Head, compound)
1da177e4	265
d85f3385	266	/*
6d777953	267	* PG_reclaim is used in combination with PG_compound to mark the
6a1e7f77 CL	268	* head and tail of a compound page. This saves one page flag
	269	* but makes it impossible to use compound pages for the page cache.
	270	* The PG_reclaim bit would have to be used for reclaim or readahead
	271	* if compound pages enter the page cache.
6d777953 CL	272	*
	273	* PG_compound & PG_reclaim => Tail page
	274	* PG_compound & ~PG_reclaim => Head page
d85f3385	275	*/
6d777953 CL	276	#define PG_head_tail_mask ((1L << PG_compound) \| (1L << PG_reclaim))
6d777953 CL	277
6a1e7f77 CL	278	static inline int PageTail(struct page *page)
	279	{
	280	return ((page->flags & PG_head_tail_mask) == PG_head_tail_mask);
	281	}
6d777953 CL	282
	283	static inline void __SetPageTail(struct page *page)
	284	{
	285	page->flags \|= PG_head_tail_mask;
	286	}
	287
	288	static inline void __ClearPageTail(struct page *page)
	289	{
	290	page->flags &= ~PG_head_tail_mask;
	291	}
	292
9223b419	293	#endif /* !__GENERATING_BOUNDS_H */
1da177e4	294	#endif /* PAGE_FLAGS_H */