/* * 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 <linux/sched.h> #include <linux/writeback.h> #include <asm/atomic.h> struct page; struct device; struct dentry; /* * Bits in backing_dev_info.state */ enum bdi_state { BDI_pending, /* On its way to being activated */ BDI_wb_alloc, /* Default embedded wb allocated */ BDI_async_congested, /* The async (write) queue is getting full */ BDI_sync_congested, /* The sync queue is getting full */ BDI_registered, /* bdi_register() was done */ 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 bdi_writeback { struct list_head list; /* hangs off the bdi */ struct backing_dev_info *bdi; /* our parent bdi */ unsigned int nr; unsigned long last_old_flush; /* last old data flush */ struct task_struct *task; /* writeback task */ struct list_head b_dirty; /* dirty inodes */ struct list_head b_io; /* parked for writeback */ struct list_head b_more_io; /* parked for more writeback */ }; struct backing_dev_info { struct list_head bdi_list; struct rcu_head rcu_head; 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; char *name; 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 bdi_writeback wb; /* default writeback info for this bdi */ spinlock_t wb_lock; /* protects update side of wb_list */ struct list_head wb_list; /* the flusher threads hanging off this bdi */ unsigned long wb_mask; /* bitmask of registered tasks */ unsigned int wb_cnt; /* number of registered tasks */ struct list_head work_list; 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); void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages); int bdi_writeback_task(struct bdi_writeback *wb); int bdi_has_dirty_io(struct backing_dev_info *bdi); extern spinlock_t bdi_lock; extern struct list_head bdi_list; static inline int wb_has_dirty_io(struct bdi_writeback *wb) { return !list_empty(&wb->b_dirty) || !list_empty(&wb->b_io) || !list_empty(&wb->b_more_io); } 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)); } enum { BLK_RW_ASYNC = 0, BLK_RW_SYNC = 1, }; void clear_bdi_congested(struct backing_dev_info *bdi, int sync); void set_bdi_congested(struct backing_dev_info *bdi, int sync); long congestion_wait(int sync, 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 bdi_cap_flush_forker(struct backing_dev_info *bdi) { return bdi == &default_backing_dev_info; } 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); } static inline int bdi_sched_wait(void *word) { schedule(); return 0; } #endif /* _LINUX_BACKING_DEV_H */