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Linux/include/linux/backing-dev.h

  1 /*
  2  * include/linux/backing-dev.h
  3  *
  4  * low-level device information and state which is propagated up through
  5  * to high-level code.
  6  */
  7 
  8 #ifndef _LINUX_BACKING_DEV_H
  9 #define _LINUX_BACKING_DEV_H
 10 
 11 #include <linux/percpu_counter.h>
 12 #include <linux/log2.h>
 13 #include <linux/flex_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>
 20 #include <linux/sysctl.h>
 21 #include <linux/workqueue.h>
 22 
 23 struct page;
 24 struct device;
 25 struct dentry;
 26 
 27 /*
 28  * Bits in backing_dev_info.state
 29  */
 30 enum bdi_state {
 31         BDI_wb_alloc,           /* Default embedded wb allocated */
 32         BDI_async_congested,    /* The async (write) queue is getting full */
 33         BDI_sync_congested,     /* The sync queue is getting full */
 34         BDI_registered,         /* bdi_register() was done */
 35         BDI_writeback_running,  /* Writeback is in progress */
 36         BDI_unused,             /* Available bits start here */
 37 };
 38 
 39 typedef int (congested_fn)(void *, int);
 40 
 41 enum bdi_stat_item {
 42         BDI_RECLAIMABLE,
 43         BDI_WRITEBACK,
 44         BDI_DIRTIED,
 45         BDI_WRITTEN,
 46         NR_BDI_STAT_ITEMS
 47 };
 48 
 49 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
 50 
 51 struct bdi_writeback {
 52         struct backing_dev_info *bdi;   /* our parent bdi */
 53         unsigned int nr;
 54 
 55         unsigned long last_old_flush;   /* last old data flush */
 56 
 57         struct delayed_work dwork;      /* work item used for writeback */
 58         struct list_head b_dirty;       /* dirty inodes */
 59         struct list_head b_io;          /* parked for writeback */
 60         struct list_head b_more_io;     /* parked for more writeback */
 61         spinlock_t list_lock;           /* protects the b_* lists */
 62 };
 63 
 64 struct backing_dev_info {
 65         struct list_head bdi_list;
 66         unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
 67         unsigned long state;    /* Always use atomic bitops on this */
 68         unsigned int capabilities; /* Device capabilities */
 69         congested_fn *congested_fn; /* Function pointer if device is md/dm */
 70         void *congested_data;   /* Pointer to aux data for congested func */
 71 
 72         char *name;
 73 
 74         struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
 75 
 76         unsigned long bw_time_stamp;    /* last time write bw is updated */
 77         unsigned long dirtied_stamp;
 78         unsigned long written_stamp;    /* pages written at bw_time_stamp */
 79         unsigned long write_bandwidth;  /* the estimated write bandwidth */
 80         unsigned long avg_write_bandwidth; /* further smoothed write bw */
 81 
 82         /*
 83          * The base dirty throttle rate, re-calculated on every 200ms.
 84          * All the bdi tasks' dirty rate will be curbed under it.
 85          * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit
 86          * in small steps and is much more smooth/stable than the latter.
 87          */
 88         unsigned long dirty_ratelimit;
 89         unsigned long balanced_dirty_ratelimit;
 90 
 91         struct fprop_local_percpu completions;
 92         int dirty_exceeded;
 93 
 94         unsigned int min_ratio;
 95         unsigned int max_ratio, max_prop_frac;
 96 
 97         struct bdi_writeback wb;  /* default writeback info for this bdi */
 98         spinlock_t wb_lock;       /* protects work_list */
 99 
100         struct list_head work_list;
101 
102         struct device *dev;
103 
104         struct timer_list laptop_mode_wb_timer;
105 
106 #ifdef CONFIG_DEBUG_FS
107         struct dentry *debug_dir;
108         struct dentry *debug_stats;
109 #endif
110 };
111 
112 int __must_check bdi_init(struct backing_dev_info *bdi);
113 void bdi_destroy(struct backing_dev_info *bdi);
114 
115 __printf(3, 4)
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 __must_check 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 void bdi_writeback_workfn(struct work_struct *work);
125 int bdi_has_dirty_io(struct backing_dev_info *bdi);
126 void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi);
127 void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2);
128 
129 extern spinlock_t bdi_lock;
130 extern struct list_head bdi_list;
131 
132 extern struct workqueue_struct *bdi_wq;
133 
134 static inline int wb_has_dirty_io(struct bdi_writeback *wb)
135 {
136         return !list_empty(&wb->b_dirty) ||
137                !list_empty(&wb->b_io) ||
138                !list_empty(&wb->b_more_io);
139 }
140 
141 static inline void __add_bdi_stat(struct backing_dev_info *bdi,
142                 enum bdi_stat_item item, s64 amount)
143 {
144         __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
145 }
146 
147 static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
148                 enum bdi_stat_item item)
149 {
150         __add_bdi_stat(bdi, item, 1);
151 }
152 
153 static inline void inc_bdi_stat(struct backing_dev_info *bdi,
154                 enum bdi_stat_item item)
155 {
156         unsigned long flags;
157 
158         local_irq_save(flags);
159         __inc_bdi_stat(bdi, item);
160         local_irq_restore(flags);
161 }
162 
163 static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
164                 enum bdi_stat_item item)
165 {
166         __add_bdi_stat(bdi, item, -1);
167 }
168 
169 static inline void dec_bdi_stat(struct backing_dev_info *bdi,
170                 enum bdi_stat_item item)
171 {
172         unsigned long flags;
173 
174         local_irq_save(flags);
175         __dec_bdi_stat(bdi, item);
176         local_irq_restore(flags);
177 }
178 
179 static inline s64 bdi_stat(struct backing_dev_info *bdi,
180                 enum bdi_stat_item item)
181 {
182         return percpu_counter_read_positive(&bdi->bdi_stat[item]);
183 }
184 
185 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
186                 enum bdi_stat_item item)
187 {
188         return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
189 }
190 
191 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
192                 enum bdi_stat_item item)
193 {
194         s64 sum;
195         unsigned long flags;
196 
197         local_irq_save(flags);
198         sum = __bdi_stat_sum(bdi, item);
199         local_irq_restore(flags);
200 
201         return sum;
202 }
203 
204 extern void bdi_writeout_inc(struct backing_dev_info *bdi);
205 
206 /*
207  * maximal error of a stat counter.
208  */
209 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
210 {
211 #ifdef CONFIG_SMP
212         return nr_cpu_ids * BDI_STAT_BATCH;
213 #else
214         return 1;
215 #endif
216 }
217 
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);
220 
221 /*
222  * Flags in backing_dev_info::capability
223  *
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)
227  *
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.
231  *
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
235  *
236  * These flags let !MMU mmap() govern direct device mapping vs immediate
237  * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
238  *
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
244  *
245  * BDI_CAP_SWAP_BACKED:    Count shmem/tmpfs objects as swap-backed.
246  *
247  * BDI_CAP_STRICTLIMIT:    Keep number of dirty pages below bdi threshold.
248  */
249 #define BDI_CAP_NO_ACCT_DIRTY   0x00000001
250 #define BDI_CAP_NO_WRITEBACK    0x00000002
251 #define BDI_CAP_MAP_COPY        0x00000004
252 #define BDI_CAP_MAP_DIRECT      0x00000008
253 #define BDI_CAP_READ_MAP        0x00000010
254 #define BDI_CAP_WRITE_MAP       0x00000020
255 #define BDI_CAP_EXEC_MAP        0x00000040
256 #define BDI_CAP_NO_ACCT_WB      0x00000080
257 #define BDI_CAP_SWAP_BACKED     0x00000100
258 #define BDI_CAP_STABLE_WRITES   0x00000200
259 #define BDI_CAP_STRICTLIMIT     0x00000400
260 
261 #define BDI_CAP_VMFLAGS \
262         (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
263 
264 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
265         (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
266 
267 #if defined(VM_MAYREAD) && \
268         (BDI_CAP_READ_MAP != VM_MAYREAD || \
269          BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
270          BDI_CAP_EXEC_MAP != VM_MAYEXEC)
271 #error please change backing_dev_info::capabilities flags
272 #endif
273 
274 extern struct backing_dev_info default_backing_dev_info;
275 extern struct backing_dev_info noop_backing_dev_info;
276 
277 int writeback_in_progress(struct backing_dev_info *bdi);
278 
279 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
280 {
281         if (bdi->congested_fn)
282                 return bdi->congested_fn(bdi->congested_data, bdi_bits);
283         return (bdi->state & bdi_bits);
284 }
285 
286 static inline int bdi_read_congested(struct backing_dev_info *bdi)
287 {
288         return bdi_congested(bdi, 1 << BDI_sync_congested);
289 }
290 
291 static inline int bdi_write_congested(struct backing_dev_info *bdi)
292 {
293         return bdi_congested(bdi, 1 << BDI_async_congested);
294 }
295 
296 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
297 {
298         return bdi_congested(bdi, (1 << BDI_sync_congested) |
299                                   (1 << BDI_async_congested));
300 }
301 
302 enum {
303         BLK_RW_ASYNC    = 0,
304         BLK_RW_SYNC     = 1,
305 };
306 
307 void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
308 void set_bdi_congested(struct backing_dev_info *bdi, int sync);
309 long congestion_wait(int sync, long timeout);
310 long wait_iff_congested(struct zone *zone, int sync, long timeout);
311 int pdflush_proc_obsolete(struct ctl_table *table, int write,
312                 void __user *buffer, size_t *lenp, loff_t *ppos);
313 
314 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi)
315 {
316         return bdi->capabilities & BDI_CAP_STABLE_WRITES;
317 }
318 
319 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
320 {
321         return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
322 }
323 
324 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
325 {
326         return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
327 }
328 
329 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
330 {
331         /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
332         return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
333                                       BDI_CAP_NO_WRITEBACK));
334 }
335 
336 static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
337 {
338         return bdi->capabilities & BDI_CAP_SWAP_BACKED;
339 }
340 
341 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
342 {
343         return bdi_cap_writeback_dirty(mapping->backing_dev_info);
344 }
345 
346 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
347 {
348         return bdi_cap_account_dirty(mapping->backing_dev_info);
349 }
350 
351 static inline bool mapping_cap_swap_backed(struct address_space *mapping)
352 {
353         return bdi_cap_swap_backed(mapping->backing_dev_info);
354 }
355 
356 static inline int bdi_sched_wait(void *word)
357 {
358         schedule();
359         return 0;
360 }
361 
362 #endif          /* _LINUX_BACKING_DEV_H */
363 

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