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[zen-stable.git] / include / linux / backing-dev.h
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1 /*
2 * include/linux/backing-dev.h
4 * low-level device information and state which is propagated up through
5 * to high-level code.
6 */
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>
15 #include <linux/fs.h>
16 #include <linux/sched.h>
17 #include <linux/timer.h>
18 #include <linux/writeback.h>
19 #include <linux/atomic.h>
21 struct page;
22 struct device;
23 struct dentry;
26 * Bits in backing_dev_info.state
28 enum bdi_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_writeback_running, /* Writeback is in progress */
35 BDI_unused, /* Available bits start here */
38 typedef int (congested_fn)(void *, int);
40 enum bdi_stat_item {
41 BDI_RECLAIMABLE,
42 BDI_WRITEBACK,
43 BDI_DIRTIED,
44 BDI_WRITTEN,
45 NR_BDI_STAT_ITEMS
48 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
50 struct bdi_writeback {
51 struct backing_dev_info *bdi; /* our parent bdi */
52 unsigned int nr;
54 unsigned long last_old_flush; /* last old data flush */
55 unsigned long last_active; /* last time bdi thread was active */
57 struct task_struct *task; /* writeback thread */
58 struct timer_list wakeup_timer; /* used for delayed bdi thread wakeup */
59 struct list_head b_dirty; /* dirty inodes */
60 struct list_head b_io; /* parked for writeback */
61 struct list_head b_more_io; /* parked for more writeback */
62 spinlock_t list_lock; /* protects the b_* lists */
65 struct backing_dev_info {
66 struct list_head bdi_list;
67 unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
68 unsigned long state; /* Always use atomic bitops on this */
69 unsigned int capabilities; /* Device capabilities */
70 congested_fn *congested_fn; /* Function pointer if device is md/dm */
71 void *congested_data; /* Pointer to aux data for congested func */
73 char *name;
75 struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
77 unsigned long bw_time_stamp; /* last time write bw is updated */
78 unsigned long dirtied_stamp;
79 unsigned long written_stamp; /* pages written at bw_time_stamp */
80 unsigned long write_bandwidth; /* the estimated write bandwidth */
81 unsigned long avg_write_bandwidth; /* further smoothed write bw */
84 * The base dirty throttle rate, re-calculated on every 200ms.
85 * All the bdi tasks' dirty rate will be curbed under it.
86 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit
87 * in small steps and is much more smooth/stable than the latter.
89 unsigned long dirty_ratelimit;
90 unsigned long balanced_dirty_ratelimit;
92 struct prop_local_percpu completions;
93 int dirty_exceeded;
95 unsigned int min_ratio;
96 unsigned int max_ratio, max_prop_frac;
98 struct bdi_writeback wb; /* default writeback info for this bdi */
99 spinlock_t wb_lock; /* protects work_list */
101 struct list_head work_list;
103 struct device *dev;
105 struct timer_list laptop_mode_wb_timer;
107 #ifdef CONFIG_DEBUG_FS
108 struct dentry *debug_dir;
109 struct dentry *debug_stats;
110 #endif
113 int bdi_init(struct backing_dev_info *bdi);
114 void bdi_destroy(struct backing_dev_info *bdi);
116 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
117 const char *fmt, ...);
118 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
119 void bdi_unregister(struct backing_dev_info *bdi);
120 int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int);
121 void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
122 enum wb_reason reason);
123 void bdi_start_background_writeback(struct backing_dev_info *bdi);
124 int bdi_writeback_thread(void *data);
125 int bdi_has_dirty_io(struct backing_dev_info *bdi);
126 void bdi_arm_supers_timer(void);
127 void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi);
128 void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2);
130 extern spinlock_t bdi_lock;
131 extern struct list_head bdi_list;
132 extern struct list_head bdi_pending_list;
134 static inline int wb_has_dirty_io(struct bdi_writeback *wb)
136 return !list_empty(&wb->b_dirty) ||
137 !list_empty(&wb->b_io) ||
138 !list_empty(&wb->b_more_io);
141 static inline void __add_bdi_stat(struct backing_dev_info *bdi,
142 enum bdi_stat_item item, s64 amount)
144 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
147 static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
148 enum bdi_stat_item item)
150 __add_bdi_stat(bdi, item, 1);
153 static inline void inc_bdi_stat(struct backing_dev_info *bdi,
154 enum bdi_stat_item item)
156 unsigned long flags;
158 local_irq_save(flags);
159 __inc_bdi_stat(bdi, item);
160 local_irq_restore(flags);
163 static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
164 enum bdi_stat_item item)
166 __add_bdi_stat(bdi, item, -1);
169 static inline void dec_bdi_stat(struct backing_dev_info *bdi,
170 enum bdi_stat_item item)
172 unsigned long flags;
174 local_irq_save(flags);
175 __dec_bdi_stat(bdi, item);
176 local_irq_restore(flags);
179 static inline s64 bdi_stat(struct backing_dev_info *bdi,
180 enum bdi_stat_item item)
182 return percpu_counter_read_positive(&bdi->bdi_stat[item]);
185 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
186 enum bdi_stat_item item)
188 return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
191 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
192 enum bdi_stat_item item)
194 s64 sum;
195 unsigned long flags;
197 local_irq_save(flags);
198 sum = __bdi_stat_sum(bdi, item);
199 local_irq_restore(flags);
201 return sum;
204 extern void bdi_writeout_inc(struct backing_dev_info *bdi);
207 * maximal error of a stat counter.
209 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
211 #ifdef CONFIG_SMP
212 return nr_cpu_ids * BDI_STAT_BATCH;
213 #else
214 return 1;
215 #endif
218 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
219 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
222 * Flags in backing_dev_info::capability
224 * The first three flags control whether dirty pages will contribute to the
225 * VM's accounting and whether writepages() should be called for dirty pages
226 * (something that would not, for example, be appropriate for ramfs)
228 * WARNING: these flags are closely related and should not normally be
229 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
230 * three flags into a single convenience macro.
232 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
233 * BDI_CAP_NO_WRITEBACK: Don't write pages back
234 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
236 * These flags let !MMU mmap() govern direct device mapping vs immediate
237 * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
239 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE)
240 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED)
241 * BDI_CAP_READ_MAP: Can be mapped for reading
242 * BDI_CAP_WRITE_MAP: Can be mapped for writing
243 * BDI_CAP_EXEC_MAP: Can be mapped for execution
245 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed.
247 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
248 #define BDI_CAP_NO_WRITEBACK 0x00000002
249 #define BDI_CAP_MAP_COPY 0x00000004
250 #define BDI_CAP_MAP_DIRECT 0x00000008
251 #define BDI_CAP_READ_MAP 0x00000010
252 #define BDI_CAP_WRITE_MAP 0x00000020
253 #define BDI_CAP_EXEC_MAP 0x00000040
254 #define BDI_CAP_NO_ACCT_WB 0x00000080
255 #define BDI_CAP_SWAP_BACKED 0x00000100
257 #define BDI_CAP_VMFLAGS \
258 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
260 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
261 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
263 #if defined(VM_MAYREAD) && \
264 (BDI_CAP_READ_MAP != VM_MAYREAD || \
265 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
266 BDI_CAP_EXEC_MAP != VM_MAYEXEC)
267 #error please change backing_dev_info::capabilities flags
268 #endif
270 extern struct backing_dev_info default_backing_dev_info;
271 extern struct backing_dev_info noop_backing_dev_info;
273 int writeback_in_progress(struct backing_dev_info *bdi);
275 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
277 if (bdi->congested_fn)
278 return bdi->congested_fn(bdi->congested_data, bdi_bits);
279 return (bdi->state & bdi_bits);
282 static inline int bdi_read_congested(struct backing_dev_info *bdi)
284 return bdi_congested(bdi, 1 << BDI_sync_congested);
287 static inline int bdi_write_congested(struct backing_dev_info *bdi)
289 return bdi_congested(bdi, 1 << BDI_async_congested);
292 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
294 return bdi_congested(bdi, (1 << BDI_sync_congested) |
295 (1 << BDI_async_congested));
298 enum {
299 BLK_RW_ASYNC = 0,
300 BLK_RW_SYNC = 1,
303 void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
304 void set_bdi_congested(struct backing_dev_info *bdi, int sync);
305 long congestion_wait(int sync, long timeout);
306 long wait_iff_congested(struct zone *zone, int sync, long timeout);
308 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
310 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
313 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
315 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
318 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
320 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
321 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
322 BDI_CAP_NO_WRITEBACK));
325 static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
327 return bdi->capabilities & BDI_CAP_SWAP_BACKED;
330 static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi)
332 return bdi == &default_backing_dev_info;
335 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
337 return bdi_cap_writeback_dirty(mapping->backing_dev_info);
340 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
342 return bdi_cap_account_dirty(mapping->backing_dev_info);
345 static inline bool mapping_cap_swap_backed(struct address_space *mapping)
347 return bdi_cap_swap_backed(mapping->backing_dev_info);
350 static inline int bdi_sched_wait(void *word)
352 schedule();
353 return 0;
356 #endif /* _LINUX_BACKING_DEV_H */