[net-next-2.6.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 <asm/atomic.h>

struct page;

/*
 * Bits in backing_dev_info.state
 */
enum bdi_state {
	BDI_pdflush,		/* A pdflush thread is working this device */
	BDI_write_congested,	/* The write queue is getting full */
	BDI_read_congested,	/* The read queue is getting full */
	BDI_unused,		/* Available bits start here */
};

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

struct backing_dev_info {
	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;
};


/*
 * Flags in backing_dev_info::capability
 * - The first two 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)
 * - These flags let !MMU mmap() govern direct device mapping vs immediate
 *   copying more easily for MAP_PRIVATE, especially for ROM filesystems
 */
#define BDI_CAP_NO_ACCT_DIRTY	0x00000001	/* Dirty pages shouldn't contribute to accounting */
#define BDI_CAP_NO_WRITEBACK	0x00000002	/* Don't write pages back */
#define BDI_CAP_MAP_COPY	0x00000004	/* Copy can be mapped (MAP_PRIVATE) */
#define BDI_CAP_MAP_DIRECT	0x00000008	/* Can be mapped directly (MAP_SHARED) */
#define BDI_CAP_READ_MAP	0x00000010	/* Can be mapped for reading */
#define BDI_CAP_WRITE_MAP	0x00000020	/* Can be mapped for writing */
#define BDI_CAP_EXEC_MAP	0x00000040	/* Can be mapped for execution */
#define BDI_CAP_VMFLAGS \
	(BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)

#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;
void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);

int writeback_acquire(struct backing_dev_info *bdi);
int writeback_in_progress(struct backing_dev_info *bdi);
void writeback_release(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_read_congested);
}

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

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

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

#define bdi_cap_writeback_dirty(bdi) \
	(!((bdi)->capabilities & BDI_CAP_NO_WRITEBACK))

#define bdi_cap_account_dirty(bdi) \
	(!((bdi)->capabilities & BDI_CAP_NO_ACCT_DIRTY))

#define mapping_cap_writeback_dirty(mapping) \
	bdi_cap_writeback_dirty((mapping)->backing_dev_info)

#define mapping_cap_account_dirty(mapping) \
	bdi_cap_account_dirty((mapping)->backing_dev_info)


#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
	11	#include <asm/atomic.h>
	12
3fcfab16 AM	13	struct page;
3fcfab16 AM	14
1da177e4 LT	15	/*
	16	* Bits in backing_dev_info.state
	17	*/
	18	enum bdi_state {
	19	BDI_pdflush, /* A pdflush thread is working this device */
	20	BDI_write_congested, /* The write queue is getting full */
	21	BDI_read_congested, /* The read queue is getting full */
	22	BDI_unused, /* Available bits start here */
	23	};
	24
	25	typedef int (congested_fn)(void *, int);
	26
	27	struct backing_dev_info {
	28	unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
	29	unsigned long state; /* Always use atomic bitops on this */
	30	unsigned int capabilities; /* Device capabilities */
	31	congested_fn congested_fn; / Function pointer if device is md/dm */
	32	void congested_data; / Pointer to aux data for congested func */
	33	void (unplug_io_fn)(struct backing_dev_info , struct page *);
	34	void *unplug_io_data;
	35	};
	36
	37
	38	/*
	39	* Flags in backing_dev_info::capability
	40	* - The first two flags control whether dirty pages will contribute to the
	41	* VM's accounting and whether writepages() should be called for dirty pages
	42	* (something that would not, for example, be appropriate for ramfs)
	43	* - These flags let !MMU mmap() govern direct device mapping vs immediate
	44	* copying more easily for MAP_PRIVATE, especially for ROM filesystems
	45	*/
	46	#define BDI_CAP_NO_ACCT_DIRTY 0x00000001 /* Dirty pages shouldn't contribute to accounting */
	47	#define BDI_CAP_NO_WRITEBACK 0x00000002 /* Don't write pages back */
	48	#define BDI_CAP_MAP_COPY 0x00000004 /* Copy can be mapped (MAP_PRIVATE) */
	49	#define BDI_CAP_MAP_DIRECT 0x00000008 /* Can be mapped directly (MAP_SHARED) */
	50	#define BDI_CAP_READ_MAP 0x00000010 /* Can be mapped for reading */
	51	#define BDI_CAP_WRITE_MAP 0x00000020 /* Can be mapped for writing */
	52	#define BDI_CAP_EXEC_MAP 0x00000040 /* Can be mapped for execution */
	53	#define BDI_CAP_VMFLAGS \
	54	(BDI_CAP_READ_MAP \| BDI_CAP_WRITE_MAP \| BDI_CAP_EXEC_MAP)
	55
	56	#if defined(VM_MAYREAD) && \
	57	(BDI_CAP_READ_MAP != VM_MAYREAD \|\| \
	58	BDI_CAP_WRITE_MAP != VM_MAYWRITE \|\| \
	59	BDI_CAP_EXEC_MAP != VM_MAYEXEC)
	60	#error please change backing_dev_info::capabilities flags
	61	#endif
	62
	63	extern struct backing_dev_info default_backing_dev_info;
	64	void default_unplug_io_fn(struct backing_dev_info bdi, struct page page);
	65
	66	int writeback_acquire(struct backing_dev_info *bdi);
	67	int writeback_in_progress(struct backing_dev_info *bdi);
	68	void writeback_release(struct backing_dev_info *bdi);
	69
	70	static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
	71	{
	72	if (bdi->congested_fn)
	73	return bdi->congested_fn(bdi->congested_data, bdi_bits);
	74	return (bdi->state & bdi_bits);
	75	}
	76
	77	static inline int bdi_read_congested(struct backing_dev_info *bdi)
	78	{
79	return bdi_congested(bdi, 1 << BDI_read_congested);
80	}
81
82	static inline int bdi_write_congested(struct backing_dev_info *bdi)
83	{
84	return bdi_congested(bdi, 1 << BDI_write_congested);
85	}
86
87	static inline int bdi_rw_congested(struct backing_dev_info *bdi)
88	{
89	return bdi_congested(bdi, (1 << BDI_read_congested)\|
90	(1 << BDI_write_congested));
91	}
92
3fcfab16 AM	93	void clear_bdi_congested(struct backing_dev_info *bdi, int rw);
	94	void set_bdi_congested(struct backing_dev_info *bdi, int rw);
	95	long congestion_wait(int rw, long timeout);
	96	void congestion_end(int rw);
	97
1da177e4 LT	98	#define bdi_cap_writeback_dirty(bdi) \
	99	(!((bdi)->capabilities & BDI_CAP_NO_WRITEBACK))
	100
	101	#define bdi_cap_account_dirty(bdi) \
	102	(!((bdi)->capabilities & BDI_CAP_NO_ACCT_DIRTY))
	103
	104	#define mapping_cap_writeback_dirty(mapping) \
	105	bdi_cap_writeback_dirty((mapping)->backing_dev_info)
	106
	107	#define mapping_cap_account_dirty(mapping) \
	108	bdi_cap_account_dirty((mapping)->backing_dev_info)
	109
	110
	111	#endif /* _LINUX_BACKING_DEV_H */