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/*
* 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 */
};
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 */
};
extern struct backing_dev_info default_backing_dev_info;
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_read_congested(struct backing_dev_info *bdi)
{
return test_bit(BDI_read_congested, &bdi->state);
}
static inline int bdi_write_congested(struct backing_dev_info *bdi)
{
return test_bit(BDI_write_congested, &bdi->state);
}
#endif /* _LINUX_BACKING_DEV_H */
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