/* * 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 <asm/atomic.h> struct page;struct device;struct dentry; /* * Bits in backing_dev_info.state */enum bdi_state {	BDI_pdflush,		/* A pdflush thread is working this device */	BDI_async_congested,	/* The async (write) queue is getting full */	BDI_sync_congested,	/* The sync queue is getting full */	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 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; 	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 device *dev; #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); 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;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));} 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);  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 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);} #endif		/* _LINUX_BACKING_DEV_H */