2 * include/linux/backing-dev.h
4 * low-level device information and state which is propagated up through
8 #ifndef _LINUX_BACKING_DEV_H
9 #define _LINUX_BACKING_DEV_H
11 #include <linux/percpu_counter.h>
12 #include <linux/log2.h>
13 #include <linux/proportions.h>
14 #include <linux/kernel.h>
16 #include <linux/sched.h>
17 #include <linux/timer.h>
18 #include <linux/writeback.h>
19 #include <asm/atomic.h>
26 * Bits in backing_dev_info.state
29 BDI_pending, /* On its way to being activated */
30 BDI_wb_alloc, /* Default embedded wb allocated */
31 BDI_async_congested, /* The async (write) queue is getting full */
32 BDI_sync_congested, /* The sync queue is getting full */
33 BDI_registered, /* bdi_register() was done */
34 BDI_unused, /* Available bits start here */
37 typedef int (congested_fn)(void *, int);
45 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
47 struct bdi_writeback {
48 struct backing_dev_info *bdi; /* our parent bdi */
51 unsigned long last_old_flush; /* last old data flush */
52 unsigned long last_active; /* last time bdi thread was active */
54 struct task_struct *task; /* writeback thread */
55 struct list_head b_dirty; /* dirty inodes */
56 struct list_head b_io; /* parked for writeback */
57 struct list_head b_more_io; /* parked for more writeback */
60 struct backing_dev_info {
61 struct list_head bdi_list;
62 unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
63 unsigned long state; /* Always use atomic bitops on this */
64 unsigned int capabilities; /* Device capabilities */
65 congested_fn *congested_fn; /* Function pointer if device is md/dm */
66 void *congested_data; /* Pointer to aux data for congested func */
67 void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
72 struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
74 struct prop_local_percpu completions;
77 unsigned int min_ratio;
78 unsigned int max_ratio, max_prop_frac;
80 struct bdi_writeback wb; /* default writeback info for this bdi */
81 spinlock_t wb_lock; /* protects work_list */
83 struct list_head work_list;
87 struct timer_list laptop_mode_wb_timer;
89 #ifdef CONFIG_DEBUG_FS
90 struct dentry *debug_dir;
91 struct dentry *debug_stats;
95 int bdi_init(struct backing_dev_info *bdi);
96 void bdi_destroy(struct backing_dev_info *bdi);
98 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
99 const char *fmt, ...);
100 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
101 void bdi_unregister(struct backing_dev_info *bdi);
102 int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int);
103 void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages);
104 void bdi_start_background_writeback(struct backing_dev_info *bdi);
105 int bdi_writeback_thread(void *data);
106 int bdi_has_dirty_io(struct backing_dev_info *bdi);
107 void bdi_arm_supers_timer(void);
109 extern spinlock_t bdi_lock;
110 extern struct list_head bdi_list;
112 static inline int wb_has_dirty_io(struct bdi_writeback *wb)
114 return !list_empty(&wb->b_dirty) ||
115 !list_empty(&wb->b_io) ||
116 !list_empty(&wb->b_more_io);
119 static inline void __add_bdi_stat(struct backing_dev_info *bdi,
120 enum bdi_stat_item item, s64 amount)
122 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
125 static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
126 enum bdi_stat_item item)
128 __add_bdi_stat(bdi, item, 1);
131 static inline void inc_bdi_stat(struct backing_dev_info *bdi,
132 enum bdi_stat_item item)
136 local_irq_save(flags);
137 __inc_bdi_stat(bdi, item);
138 local_irq_restore(flags);
141 static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
142 enum bdi_stat_item item)
144 __add_bdi_stat(bdi, item, -1);
147 static inline void dec_bdi_stat(struct backing_dev_info *bdi,
148 enum bdi_stat_item item)
152 local_irq_save(flags);
153 __dec_bdi_stat(bdi, item);
154 local_irq_restore(flags);
157 static inline s64 bdi_stat(struct backing_dev_info *bdi,
158 enum bdi_stat_item item)
160 return percpu_counter_read_positive(&bdi->bdi_stat[item]);
163 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
164 enum bdi_stat_item item)
166 return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
169 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
170 enum bdi_stat_item item)
175 local_irq_save(flags);
176 sum = __bdi_stat_sum(bdi, item);
177 local_irq_restore(flags);
182 extern void bdi_writeout_inc(struct backing_dev_info *bdi);
185 * maximal error of a stat counter.
187 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
190 return nr_cpu_ids * BDI_STAT_BATCH;
196 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
197 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
200 * Flags in backing_dev_info::capability
202 * The first three flags control whether dirty pages will contribute to the
203 * VM's accounting and whether writepages() should be called for dirty pages
204 * (something that would not, for example, be appropriate for ramfs)
206 * WARNING: these flags are closely related and should not normally be
207 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
208 * three flags into a single convenience macro.
210 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
211 * BDI_CAP_NO_WRITEBACK: Don't write pages back
212 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
214 * These flags let !MMU mmap() govern direct device mapping vs immediate
215 * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
217 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE)
218 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED)
219 * BDI_CAP_READ_MAP: Can be mapped for reading
220 * BDI_CAP_WRITE_MAP: Can be mapped for writing
221 * BDI_CAP_EXEC_MAP: Can be mapped for execution
223 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed.
225 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
226 #define BDI_CAP_NO_WRITEBACK 0x00000002
227 #define BDI_CAP_MAP_COPY 0x00000004
228 #define BDI_CAP_MAP_DIRECT 0x00000008
229 #define BDI_CAP_READ_MAP 0x00000010
230 #define BDI_CAP_WRITE_MAP 0x00000020
231 #define BDI_CAP_EXEC_MAP 0x00000040
232 #define BDI_CAP_NO_ACCT_WB 0x00000080
233 #define BDI_CAP_SWAP_BACKED 0x00000100
235 #define BDI_CAP_VMFLAGS \
236 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
238 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
239 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
241 #if defined(VM_MAYREAD) && \
242 (BDI_CAP_READ_MAP != VM_MAYREAD || \
243 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
244 BDI_CAP_EXEC_MAP != VM_MAYEXEC)
245 #error please change backing_dev_info::capabilities flags
248 extern struct backing_dev_info default_backing_dev_info;
249 extern struct backing_dev_info noop_backing_dev_info;
250 void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);
252 int writeback_in_progress(struct backing_dev_info *bdi);
254 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
256 if (bdi->congested_fn)
257 return bdi->congested_fn(bdi->congested_data, bdi_bits);
258 return (bdi->state & bdi_bits);
261 static inline int bdi_read_congested(struct backing_dev_info *bdi)
263 return bdi_congested(bdi, 1 << BDI_sync_congested);
266 static inline int bdi_write_congested(struct backing_dev_info *bdi)
268 return bdi_congested(bdi, 1 << BDI_async_congested);
271 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
273 return bdi_congested(bdi, (1 << BDI_sync_congested) |
274 (1 << BDI_async_congested));
282 void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
283 void set_bdi_congested(struct backing_dev_info *bdi, int sync);
284 long congestion_wait(int sync, long timeout);
287 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
289 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
292 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
294 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
297 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
299 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
300 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
301 BDI_CAP_NO_WRITEBACK));
304 static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
306 return bdi->capabilities & BDI_CAP_SWAP_BACKED;
309 static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi)
311 return bdi == &default_backing_dev_info;
314 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
316 return bdi_cap_writeback_dirty(mapping->backing_dev_info);
319 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
321 return bdi_cap_account_dirty(mapping->backing_dev_info);
324 static inline bool mapping_cap_swap_backed(struct address_space *mapping)
326 return bdi_cap_swap_backed(mapping->backing_dev_info);
329 static inline int bdi_sched_wait(void *word)
335 static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
338 if (bdi && bdi->unplug_io_fn)
339 bdi->unplug_io_fn(bdi, page);
342 static inline void blk_run_address_space(struct address_space *mapping)
345 blk_run_backing_dev(mapping->backing_dev_info, NULL);
348 #endif /* _LINUX_BACKING_DEV_H */