Line data Source code
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 & wb.dwork scheduling */
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 99183 : if (bdi->congested_fn)
282 0 : return bdi->congested_fn(bdi->congested_data, bdi_bits);
283 99183 : 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 */
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