/* * 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> /* * 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 */	int memory_backed;	/* Cannot clean pages with writepage */	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;}; 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));} #endif		/* _LINUX_BACKING_DEV_H */