[deliverable/linux.git] / include / linux / backing-dev.h

/*
 * include/linux/backing-dev.h
 *
 * low-level device information and state which is propagated up through
 * to high-level code.
 */

#ifndef _LINUX_BACKING_DEV_H
#define _LINUX_BACKING_DEV_H

#include <linux/percpu_counter.h>
#include <linux/log2.h>
#include <linux/proportions.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/writeback.h>
#include <asm/atomic.h>

struct page;
struct device;
struct dentry;

/*
 * Bits in backing_dev_info.state
 */
enum bdi_state {
	BDI_pending,		/* On its way to being activated */
	BDI_wb_alloc,		/* Default embedded wb allocated */
	BDI_async_congested,	/* The async (write) queue is getting full */
	BDI_sync_congested,	/* The sync queue is getting full */
	BDI_registered,		/* bdi_register() was done */
	BDI_writeback_running,	/* Writeback is in progress */
	BDI_unused,		/* Available bits start here */
};

typedef int (congested_fn)(void *, int);

enum bdi_stat_item {
	BDI_RECLAIMABLE,
	BDI_WRITEBACK,
	NR_BDI_STAT_ITEMS
};

#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))

struct bdi_writeback {
	struct backing_dev_info *bdi;	/* our parent bdi */
	unsigned int nr;

	unsigned long last_old_flush;	/* last old data flush */
	unsigned long last_active;	/* last time bdi thread was active */

	struct task_struct *task;	/* writeback thread */
	struct timer_list wakeup_timer; /* used for delayed bdi thread wakeup */
	struct list_head b_dirty;	/* dirty inodes */
	struct list_head b_io;		/* parked for writeback */
	struct list_head b_more_io;	/* parked for more writeback */
};

struct backing_dev_info {
	struct list_head bdi_list;
	unsigned long ra_pages;	/* max readahead in PAGE_CACHE_SIZE units */
	unsigned long state;	/* Always use atomic bitops on this */
	unsigned int capabilities; /* Device capabilities */
	congested_fn *congested_fn; /* Function pointer if device is md/dm */
	void *congested_data;	/* Pointer to aux data for congested func */
	void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
	void *unplug_io_data;

	char *name;

	struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];

	struct prop_local_percpu completions;
	int dirty_exceeded;

	unsigned int min_ratio;
	unsigned int max_ratio, max_prop_frac;

	struct bdi_writeback wb;  /* default writeback info for this bdi */
	spinlock_t wb_lock;	  /* protects work_list */

	struct list_head work_list;

	struct device *dev;

	struct timer_list laptop_mode_wb_timer;

#ifdef CONFIG_DEBUG_FS
	struct dentry *debug_dir;
	struct dentry *debug_stats;
#endif
};

int bdi_init(struct backing_dev_info *bdi);
void bdi_destroy(struct backing_dev_info *bdi);

int bdi_register(struct backing_dev_info *bdi, struct device *parent,
		const char *fmt, ...);
int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
void bdi_unregister(struct backing_dev_info *bdi);
int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int);
void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages);
void bdi_start_background_writeback(struct backing_dev_info *bdi);
int bdi_writeback_thread(void *data);
int bdi_has_dirty_io(struct backing_dev_info *bdi);
void bdi_arm_supers_timer(void);
void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi);

extern spinlock_t bdi_lock;
extern struct list_head bdi_list;

static inline int wb_has_dirty_io(struct bdi_writeback *wb)
{
	return !list_empty(&wb->b_dirty) ||
	       !list_empty(&wb->b_io) ||
	       !list_empty(&wb->b_more_io);
}

static inline void __add_bdi_stat(struct backing_dev_info *bdi,
		enum bdi_stat_item item, s64 amount)
{
	__percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
}

static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
		enum bdi_stat_item item)
{
	__add_bdi_stat(bdi, item, 1);
}

static inline void inc_bdi_stat(struct backing_dev_info *bdi,
		enum bdi_stat_item item)
{
	unsigned long flags;

	local_irq_save(flags);
	__inc_bdi_stat(bdi, item);
	local_irq_restore(flags);
}

static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
		enum bdi_stat_item item)
{
	__add_bdi_stat(bdi, item, -1);
}

static inline void dec_bdi_stat(struct backing_dev_info *bdi,
		enum bdi_stat_item item)
{
	unsigned long flags;

	local_irq_save(flags);
	__dec_bdi_stat(bdi, item);
	local_irq_restore(flags);
}

static inline s64 bdi_stat(struct backing_dev_info *bdi,
		enum bdi_stat_item item)
{
	return percpu_counter_read_positive(&bdi->bdi_stat[item]);
}

static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
		enum bdi_stat_item item)
{
	return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
}

static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
		enum bdi_stat_item item)
{
	s64 sum;
	unsigned long flags;

	local_irq_save(flags);
	sum = __bdi_stat_sum(bdi, item);
	local_irq_restore(flags);

	return sum;
}

extern void bdi_writeout_inc(struct backing_dev_info *bdi);

/*
 * maximal error of a stat counter.
 */
static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
{
#ifdef CONFIG_SMP
	return nr_cpu_ids * BDI_STAT_BATCH;
#else
	return 1;
#endif
}

int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);

/*
 * Flags in backing_dev_info::capability
 *
 * The first three flags control whether dirty pages will contribute to the
 * VM's accounting and whether writepages() should be called for dirty pages
 * (something that would not, for example, be appropriate for ramfs)
 *
 * WARNING: these flags are closely related and should not normally be
 * used separately.  The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
 * three flags into a single convenience macro.
 *
 * BDI_CAP_NO_ACCT_DIRTY:  Dirty pages shouldn't contribute to accounting
 * BDI_CAP_NO_WRITEBACK:   Don't write pages back
 * BDI_CAP_NO_ACCT_WB:     Don't automatically account writeback pages
 *
 * These flags let !MMU mmap() govern direct device mapping vs immediate
 * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
 *
 * BDI_CAP_MAP_COPY:       Copy can be mapped (MAP_PRIVATE)
 * BDI_CAP_MAP_DIRECT:     Can be mapped directly (MAP_SHARED)
 * BDI_CAP_READ_MAP:       Can be mapped for reading
 * BDI_CAP_WRITE_MAP:      Can be mapped for writing
 * BDI_CAP_EXEC_MAP:       Can be mapped for execution
 *
 * BDI_CAP_SWAP_BACKED:    Count shmem/tmpfs objects as swap-backed.
 */
#define BDI_CAP_NO_ACCT_DIRTY	0x00000001
#define BDI_CAP_NO_WRITEBACK	0x00000002
#define BDI_CAP_MAP_COPY	0x00000004
#define BDI_CAP_MAP_DIRECT	0x00000008
#define BDI_CAP_READ_MAP	0x00000010
#define BDI_CAP_WRITE_MAP	0x00000020
#define BDI_CAP_EXEC_MAP	0x00000040
#define BDI_CAP_NO_ACCT_WB	0x00000080
#define BDI_CAP_SWAP_BACKED	0x00000100

#define BDI_CAP_VMFLAGS \
	(BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)

#define BDI_CAP_NO_ACCT_AND_WRITEBACK \
	(BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)

#if defined(VM_MAYREAD) && \
	(BDI_CAP_READ_MAP != VM_MAYREAD || \
	 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
	 BDI_CAP_EXEC_MAP != VM_MAYEXEC)
#error please change backing_dev_info::capabilities flags
#endif

extern struct backing_dev_info default_backing_dev_info;
extern struct backing_dev_info noop_backing_dev_info;
void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);

int writeback_in_progress(struct backing_dev_info *bdi);

static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
{
	if (bdi->congested_fn)
		return bdi->congested_fn(bdi->congested_data, bdi_bits);
	return (bdi->state & bdi_bits);
}

static inline int bdi_read_congested(struct backing_dev_info *bdi)
{
	return bdi_congested(bdi, 1 << BDI_sync_congested);
}

static inline int bdi_write_congested(struct backing_dev_info *bdi)
{
	return bdi_congested(bdi, 1 << BDI_async_congested);
}

static inline int bdi_rw_congested(struct backing_dev_info *bdi)
{
	return bdi_congested(bdi, (1 << BDI_sync_congested) |
				  (1 << BDI_async_congested));
}

enum {
	BLK_RW_ASYNC	= 0,
	BLK_RW_SYNC	= 1,
};

void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
void set_bdi_congested(struct backing_dev_info *bdi, int sync);
long congestion_wait(int sync, long timeout);


static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
{
	return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
}

static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
{
	return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
}

static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
{
	/* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
	return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
				      BDI_CAP_NO_WRITEBACK));
}

static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
{
	return bdi->capabilities & BDI_CAP_SWAP_BACKED;
}

static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi)
{
	return bdi == &default_backing_dev_info;
}

static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
{
	return bdi_cap_writeback_dirty(mapping->backing_dev_info);
}

static inline bool mapping_cap_account_dirty(struct address_space *mapping)
{
	return bdi_cap_account_dirty(mapping->backing_dev_info);
}

static inline bool mapping_cap_swap_backed(struct address_space *mapping)
{
	return bdi_cap_swap_backed(mapping->backing_dev_info);
}

static inline int bdi_sched_wait(void *word)
{
	schedule();
	return 0;
}

static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
				       struct page *page)
{
	if (bdi && bdi->unplug_io_fn)
		bdi->unplug_io_fn(bdi, page);
}

static inline void blk_run_address_space(struct address_space *mapping)
{
	if (mapping)
		blk_run_backing_dev(mapping->backing_dev_info, NULL);
}

#endif		/* _LINUX_BACKING_DEV_H */
Commit	Line	Data
1da177e4 LT	1	/*
	2	* include/linux/backing-dev.h
	3	*
	4	* low-level device information and state which is propagated up through
	5	* to high-level code.
	6	*/
	7
	8	#ifndef _LINUX_BACKING_DEV_H
	9	#define _LINUX_BACKING_DEV_H
	10
b2e8fb6e PZ	11	#include <linux/percpu_counter.h>
b2e8fb6e PZ	12	#include <linux/log2.h>
04fbfdc1	13	#include <linux/proportions.h>
cf0ca9fe	14	#include <linux/kernel.h>
e4ad08fe	15	#include <linux/fs.h>
03ba3782	16	#include <linux/sched.h>
31373d09	17	#include <linux/timer.h>
03ba3782	18	#include <linux/writeback.h>
1da177e4 LT	19	#include <asm/atomic.h>
1da177e4 LT	20
3fcfab16	21	struct page;
cf0ca9fe	22	struct device;
76f1418b	23	struct dentry;
3fcfab16	24
1da177e4 LT	25	/*
	26	* Bits in backing_dev_info.state
	27	*/
	28	enum bdi_state {
03ba3782 JA	29	BDI_pending, /* On its way to being activated */
03ba3782 JA	30	BDI_wb_alloc, /* Default embedded wb allocated */
1faa16d2 JA	31	BDI_async_congested, /* The async (write) queue is getting full */
1faa16d2 JA	32	BDI_sync_congested, /* The sync queue is getting full */
500b067c	33	BDI_registered, /* bdi_register() was done */
81d73a32	34	BDI_writeback_running, /* Writeback is in progress */
1da177e4 LT	35	BDI_unused, /* Available bits start here */
	36	};
	37
	38	typedef int (congested_fn)(void *, int);
	39
b2e8fb6e	40	enum bdi_stat_item {
c9e51e41	41	BDI_RECLAIMABLE,
69cb51d1	42	BDI_WRITEBACK,
b2e8fb6e PZ	43	NR_BDI_STAT_ITEMS
	44	};
	45
	46	#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
	47
03ba3782	48	struct bdi_writeback {
ecd58403	49	struct backing_dev_info bdi; / our parent bdi */
03ba3782 JA	50	unsigned int nr;
03ba3782 JA	51
ecd58403 AB	52	unsigned long last_old_flush; /* last old data flush */
ecd58403 AB	53	unsigned long last_active; /* last time bdi thread was active */
03ba3782	54
ecd58403	55	struct task_struct task; / writeback thread */
6467716a	56	struct timer_list wakeup_timer; /* used for delayed bdi thread wakeup */
ecd58403 AB	57	struct list_head b_dirty; /* dirty inodes */
	58	struct list_head b_io; /* parked for writeback */
	59	struct list_head b_more_io; /* parked for more writeback */
03ba3782 JA	60	};
03ba3782 JA	61
1da177e4	62	struct backing_dev_info {
66f3b8e2	63	struct list_head bdi_list;
1da177e4 LT	64	unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
	65	unsigned long state; /* Always use atomic bitops on this */
	66	unsigned int capabilities; /* Device capabilities */
	67	congested_fn congested_fn; / Function pointer if device is md/dm */
	68	void congested_data; / Pointer to aux data for congested func */
	69	void (unplug_io_fn)(struct backing_dev_info , struct page *);
	70	void *unplug_io_data;
b2e8fb6e	71
d993831f JA	72	char *name;
d993831f JA	73
b2e8fb6e	74	struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
04fbfdc1 PZ	75
	76	struct prop_local_percpu completions;
	77	int dirty_exceeded;
cf0ca9fe	78
189d3c4a	79	unsigned int min_ratio;
a42dde04	80	unsigned int max_ratio, max_prop_frac;
189d3c4a	81
03ba3782	82	struct bdi_writeback wb; /* default writeback info for this bdi */
c1955ce3	83	spinlock_t wb_lock; /* protects work_list */
76f1418b	84
03ba3782 JA	85	struct list_head work_list;
	86
	87	struct device *dev;
66f3b8e2	88
31373d09 MG	89	struct timer_list laptop_mode_wb_timer;
31373d09 MG	90
76f1418b MS	91	#ifdef CONFIG_DEBUG_FS
	92	struct dentry *debug_dir;
	93	struct dentry *debug_stats;
	94	#endif
1da177e4 LT	95	};
1da177e4 LT	96
b2e8fb6e PZ	97	int bdi_init(struct backing_dev_info *bdi);
	98	void bdi_destroy(struct backing_dev_info *bdi);
	99
cf0ca9fe PZ	100	int bdi_register(struct backing_dev_info bdi, struct device parent,
	101	const char *fmt, ...);
	102	int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
	103	void bdi_unregister(struct backing_dev_info *bdi);
c3c53206	104	int bdi_setup_and_register(struct backing_dev_info , char , unsigned int);
c5444198 CH	105	void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages);
c5444198 CH	106	void bdi_start_background_writeback(struct backing_dev_info *bdi);
08243900	107	int bdi_writeback_thread(void *data);
03ba3782	108	int bdi_has_dirty_io(struct backing_dev_info *bdi);
6423104b	109	void bdi_arm_supers_timer(void);
6467716a	110	void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi);
cf0ca9fe	111
03ba3782	112	extern spinlock_t bdi_lock;
66f3b8e2 JA	113	extern struct list_head bdi_list;
66f3b8e2 JA	114
03ba3782 JA	115	static inline int wb_has_dirty_io(struct bdi_writeback *wb)
	116	{
	117	return !list_empty(&wb->b_dirty) \|\|
	118	!list_empty(&wb->b_io) \|\|
	119	!list_empty(&wb->b_more_io);
	120	}
	121
b2e8fb6e PZ	122	static inline void __add_bdi_stat(struct backing_dev_info *bdi,
	123	enum bdi_stat_item item, s64 amount)
	124	{
	125	__percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
	126	}
	127
	128	static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
	129	enum bdi_stat_item item)
	130	{
	131	__add_bdi_stat(bdi, item, 1);
	132	}
	133
	134	static inline void inc_bdi_stat(struct backing_dev_info *bdi,
	135	enum bdi_stat_item item)
	136	{
	137	unsigned long flags;
	138
	139	local_irq_save(flags);
	140	__inc_bdi_stat(bdi, item);
	141	local_irq_restore(flags);
	142	}
	143
	144	static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
	145	enum bdi_stat_item item)
	146	{
	147	__add_bdi_stat(bdi, item, -1);
	148	}
	149
	150	static inline void dec_bdi_stat(struct backing_dev_info *bdi,
	151	enum bdi_stat_item item)
	152	{
	153	unsigned long flags;
	154
	155	local_irq_save(flags);
	156	__dec_bdi_stat(bdi, item);
	157	local_irq_restore(flags);
	158	}
	159
	160	static inline s64 bdi_stat(struct backing_dev_info *bdi,
	161	enum bdi_stat_item item)
	162	{
	163	return percpu_counter_read_positive(&bdi->bdi_stat[item]);
	164	}
	165
	166	static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
	167	enum bdi_stat_item item)
	168	{
	169	return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
	170	}
	171
	172	static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
	173	enum bdi_stat_item item)
e0bf68dd	174	{
b2e8fb6e PZ	175	s64 sum;
	176	unsigned long flags;
	177
	178	local_irq_save(flags);
	179	sum = __bdi_stat_sum(bdi, item);
	180	local_irq_restore(flags);
	181
	182	return sum;
e0bf68dd PZ	183	}
e0bf68dd PZ	184
dd5656e5 MS	185	extern void bdi_writeout_inc(struct backing_dev_info *bdi);
dd5656e5 MS	186
b2e8fb6e PZ	187	/*
	188	* maximal error of a stat counter.
	189	*/
	190	static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
e0bf68dd	191	{
b2e8fb6e PZ	192	#ifdef CONFIG_SMP
	193	return nr_cpu_ids * BDI_STAT_BATCH;
	194	#else
	195	return 1;
	196	#endif
e0bf68dd	197	}
1da177e4	198
189d3c4a	199	int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
a42dde04	200	int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
189d3c4a	201
1da177e4 LT	202	/*
1da177e4 LT	203	* Flags in backing_dev_info::capability
e4ad08fe MS	204	*
	205	* The first three flags control whether dirty pages will contribute to the
	206	* VM's accounting and whether writepages() should be called for dirty pages
	207	* (something that would not, for example, be appropriate for ramfs)
	208	*
	209	* WARNING: these flags are closely related and should not normally be
	210	* used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
	211	* three flags into a single convenience macro.
	212	*
	213	* BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
	214	* BDI_CAP_NO_WRITEBACK: Don't write pages back
	215	* BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
	216	*
	217	* These flags let !MMU mmap() govern direct device mapping vs immediate
	218	* copying more easily for MAP_PRIVATE, especially for ROM filesystems.
	219	*
	220	* BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE)
	221	* BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED)
	222	* BDI_CAP_READ_MAP: Can be mapped for reading
	223	* BDI_CAP_WRITE_MAP: Can be mapped for writing
	224	* BDI_CAP_EXEC_MAP: Can be mapped for execution
4f98a2fe RR	225	*
4f98a2fe RR	226	* BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed.
1da177e4	227	*/
e4ad08fe MS	228	#define BDI_CAP_NO_ACCT_DIRTY 0x00000001
	229	#define BDI_CAP_NO_WRITEBACK 0x00000002
	230	#define BDI_CAP_MAP_COPY 0x00000004
	231	#define BDI_CAP_MAP_DIRECT 0x00000008
	232	#define BDI_CAP_READ_MAP 0x00000010
	233	#define BDI_CAP_WRITE_MAP 0x00000020
	234	#define BDI_CAP_EXEC_MAP 0x00000040
	235	#define BDI_CAP_NO_ACCT_WB 0x00000080
4f98a2fe	236	#define BDI_CAP_SWAP_BACKED 0x00000100
e4ad08fe	237
1da177e4 LT	238	#define BDI_CAP_VMFLAGS \
	239	(BDI_CAP_READ_MAP \| BDI_CAP_WRITE_MAP \| BDI_CAP_EXEC_MAP)
	240
e4ad08fe MS	241	#define BDI_CAP_NO_ACCT_AND_WRITEBACK \
	242	(BDI_CAP_NO_WRITEBACK \| BDI_CAP_NO_ACCT_DIRTY \| BDI_CAP_NO_ACCT_WB)
	243
1da177e4 LT	244	#if defined(VM_MAYREAD) && \
	245	(BDI_CAP_READ_MAP != VM_MAYREAD \|\| \
	246	BDI_CAP_WRITE_MAP != VM_MAYWRITE \|\| \
	247	BDI_CAP_EXEC_MAP != VM_MAYEXEC)
	248	#error please change backing_dev_info::capabilities flags
	249	#endif
	250
	251	extern struct backing_dev_info default_backing_dev_info;
5129a469	252	extern struct backing_dev_info noop_backing_dev_info;
1da177e4 LT	253	void default_unplug_io_fn(struct backing_dev_info bdi, struct page page);
1da177e4 LT	254
1da177e4	255	int writeback_in_progress(struct backing_dev_info *bdi);
1da177e4 LT	256
	257	static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
	258	{
	259	if (bdi->congested_fn)
	260	return bdi->congested_fn(bdi->congested_data, bdi_bits);
	261	return (bdi->state & bdi_bits);
	262	}
	263
	264	static inline int bdi_read_congested(struct backing_dev_info *bdi)
	265	{
1faa16d2	266	return bdi_congested(bdi, 1 << BDI_sync_congested);
1da177e4 LT	267	}
	268
	269	static inline int bdi_write_congested(struct backing_dev_info *bdi)
	270	{
1faa16d2	271	return bdi_congested(bdi, 1 << BDI_async_congested);
1da177e4 LT	272	}
	273
	274	static inline int bdi_rw_congested(struct backing_dev_info *bdi)
	275	{
1faa16d2 JA	276	return bdi_congested(bdi, (1 << BDI_sync_congested) \|
1faa16d2 JA	277	(1 << BDI_async_congested));
1da177e4 LT	278	}
1da177e4 LT	279
373c0a7e TM	280	enum {
	281	BLK_RW_ASYNC = 0,
	282	BLK_RW_SYNC = 1,
	283	};
	284
8aa7e847 JA	285	void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
	286	void set_bdi_congested(struct backing_dev_info *bdi, int sync);
	287	long congestion_wait(int sync, long timeout);
3fcfab16	288
1da177e4	289
e4ad08fe MS	290	static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
	291	{
	292	return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
	293	}
	294
	295	static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
	296	{
	297	return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
	298	}
1da177e4	299
e4ad08fe MS	300	static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
	301	{
	302	/* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
	303	return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB \|
	304	BDI_CAP_NO_WRITEBACK));
	305	}
1da177e4	306
4f98a2fe RR	307	static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
	308	{
	309	return bdi->capabilities & BDI_CAP_SWAP_BACKED;
	310	}
	311
03ba3782 JA	312	static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi)
	313	{
	314	return bdi == &default_backing_dev_info;
	315	}
	316
e4ad08fe MS	317	static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
	318	{
	319	return bdi_cap_writeback_dirty(mapping->backing_dev_info);
	320	}
1da177e4	321
e4ad08fe MS	322	static inline bool mapping_cap_account_dirty(struct address_space *mapping)
	323	{
	324	return bdi_cap_account_dirty(mapping->backing_dev_info);
	325	}
1da177e4	326
4f98a2fe RR	327	static inline bool mapping_cap_swap_backed(struct address_space *mapping)
	328	{
	329	return bdi_cap_swap_backed(mapping->backing_dev_info);
	330	}
	331
03ba3782 JA	332	static inline int bdi_sched_wait(void *word)
	333	{
	334	schedule();
	335	return 0;
	336	}
	337
b9d128f1 JA	338	static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
	339	struct page *page)
	340	{
	341	if (bdi && bdi->unplug_io_fn)
	342	bdi->unplug_io_fn(bdi, page);
	343	}
	344
	345	static inline void blk_run_address_space(struct address_space *mapping)
	346	{
	347	if (mapping)
	348	blk_run_backing_dev(mapping->backing_dev_info, NULL);
	349	}
	350
1da177e4	351	#endif /* _LINUX_BACKING_DEV_H */