| /* |
| * 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 <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 { |
| 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]; |
| }; |
| |
| 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 */ |