/* * 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 <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); 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; }; int bdi_init(struct backing_dev_info *bdi); void bdi_destroy(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; } /* * 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 } /* * 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); #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 */