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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/proportions.h> |
14 | #include <linux/kernel.h> |
15 | #include <linux/fs.h> |
16 | #include <linux/sched.h> |
17 | #include <linux/writeback.h> |
18 | #include <asm/atomic.h> |
19 | |
20 | struct page; |
21 | struct device; |
22 | struct dentry; |
23 | |
24 | /* |
25 | * Bits in backing_dev_info.state |
26 | */ |
27 | enum bdi_state { |
28 | BDI_pending, /* On its way to being activated */ |
29 | BDI_wb_alloc, /* Default embedded wb allocated */ |
30 | BDI_async_congested, /* The async (write) queue is getting full */ |
31 | BDI_sync_congested, /* The sync queue is getting full */ |
32 | BDI_registered, /* bdi_register() was done */ |
33 | BDI_unused, /* Available bits start here */ |
34 | }; |
35 | |
36 | typedef int (congested_fn)(void *, int); |
37 | |
38 | enum bdi_stat_item { |
39 | BDI_RECLAIMABLE, |
40 | BDI_WRITEBACK, |
41 | NR_BDI_STAT_ITEMS |
42 | }; |
43 | |
44 | #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids))) |
45 | |
46 | struct bdi_writeback { |
47 | struct list_head list; /* hangs off the bdi */ |
48 | |
49 | struct backing_dev_info *bdi; /* our parent bdi */ |
50 | unsigned int nr; |
51 | |
52 | unsigned long last_old_flush; /* last old data flush */ |
53 | |
54 | struct task_struct *task; /* writeback task */ |
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 */ |
58 | }; |
59 | |
60 | struct backing_dev_info { |
61 | struct list_head bdi_list; |
62 | struct rcu_head rcu_head; |
63 | unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */ |
64 | unsigned long state; /* Always use atomic bitops on this */ |
65 | unsigned int capabilities; /* Device capabilities */ |
66 | congested_fn *congested_fn; /* Function pointer if device is md/dm */ |
67 | void *congested_data; /* Pointer to aux data for congested func */ |
68 | void (*unplug_io_fn)(struct backing_dev_info *, struct page *); |
69 | void *unplug_io_data; |
70 | |
71 | char *name; |
72 | |
73 | struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS]; |
74 | |
75 | struct prop_local_percpu completions; |
76 | int dirty_exceeded; |
77 | |
78 | unsigned int min_ratio; |
79 | unsigned int max_ratio, max_prop_frac; |
80 | |
81 | struct bdi_writeback wb; /* default writeback info for this bdi */ |
82 | spinlock_t wb_lock; /* protects update side of wb_list */ |
83 | struct list_head wb_list; /* the flusher threads hanging off this bdi */ |
84 | unsigned long wb_mask; /* bitmask of registered tasks */ |
85 | unsigned int wb_cnt; /* number of registered tasks */ |
86 | |
87 | struct list_head work_list; |
88 | |
89 | struct device *dev; |
90 | |
91 | #ifdef CONFIG_DEBUG_FS |
92 | struct dentry *debug_dir; |
93 | struct dentry *debug_stats; |
94 | #endif |
95 | }; |
96 | |
97 | int bdi_init(struct backing_dev_info *bdi); |
98 | void bdi_destroy(struct backing_dev_info *bdi); |
99 | |
100 | int bdi_register(struct backing_dev_info *bdi, struct device *parent, |
101 | const char *fmt, ...); |
102 | int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev); |
103 | void bdi_unregister(struct backing_dev_info *bdi); |
104 | void bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb, |
105 | long nr_pages); |
106 | int bdi_writeback_task(struct bdi_writeback *wb); |
107 | int bdi_has_dirty_io(struct backing_dev_info *bdi); |
108 | |
109 | extern spinlock_t bdi_lock; |
110 | extern struct list_head bdi_list; |
111 | |
112 | static inline int wb_has_dirty_io(struct bdi_writeback *wb) |
113 | { |
114 | return !list_empty(&wb->b_dirty) || |
115 | !list_empty(&wb->b_io) || |
116 | !list_empty(&wb->b_more_io); |
117 | } |
118 | |
119 | static inline void __add_bdi_stat(struct backing_dev_info *bdi, |
120 | enum bdi_stat_item item, s64 amount) |
121 | { |
122 | __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH); |
123 | } |
124 | |
125 | static inline void __inc_bdi_stat(struct backing_dev_info *bdi, |
126 | enum bdi_stat_item item) |
127 | { |
128 | __add_bdi_stat(bdi, item, 1); |
129 | } |
130 | |
131 | static inline void inc_bdi_stat(struct backing_dev_info *bdi, |
132 | enum bdi_stat_item item) |
133 | { |
134 | unsigned long flags; |
135 | |
136 | local_irq_save(flags); |
137 | __inc_bdi_stat(bdi, item); |
138 | local_irq_restore(flags); |
139 | } |
140 | |
141 | static inline void __dec_bdi_stat(struct backing_dev_info *bdi, |
142 | enum bdi_stat_item item) |
143 | { |
144 | __add_bdi_stat(bdi, item, -1); |
145 | } |
146 | |
147 | static inline void dec_bdi_stat(struct backing_dev_info *bdi, |
148 | enum bdi_stat_item item) |
149 | { |
150 | unsigned long flags; |
151 | |
152 | local_irq_save(flags); |
153 | __dec_bdi_stat(bdi, item); |
154 | local_irq_restore(flags); |
155 | } |
156 | |
157 | static inline s64 bdi_stat(struct backing_dev_info *bdi, |
158 | enum bdi_stat_item item) |
159 | { |
160 | return percpu_counter_read_positive(&bdi->bdi_stat[item]); |
161 | } |
162 | |
163 | static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi, |
164 | enum bdi_stat_item item) |
165 | { |
166 | return percpu_counter_sum_positive(&bdi->bdi_stat[item]); |
167 | } |
168 | |
169 | static inline s64 bdi_stat_sum(struct backing_dev_info *bdi, |
170 | enum bdi_stat_item item) |
171 | { |
172 | s64 sum; |
173 | unsigned long flags; |
174 | |
175 | local_irq_save(flags); |
176 | sum = __bdi_stat_sum(bdi, item); |
177 | local_irq_restore(flags); |
178 | |
179 | return sum; |
180 | } |
181 | |
182 | extern void bdi_writeout_inc(struct backing_dev_info *bdi); |
183 | |
184 | /* |
185 | * maximal error of a stat counter. |
186 | */ |
187 | static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi) |
188 | { |
189 | #ifdef CONFIG_SMP |
190 | return nr_cpu_ids * BDI_STAT_BATCH; |
191 | #else |
192 | return 1; |
193 | #endif |
194 | } |
195 | |
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); |
198 | |
199 | /* |
200 | * Flags in backing_dev_info::capability |
201 | * |
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) |
205 | * |
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. |
209 | * |
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 |
213 | * |
214 | * These flags let !MMU mmap() govern direct device mapping vs immediate |
215 | * copying more easily for MAP_PRIVATE, especially for ROM filesystems. |
216 | * |
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 |
222 | * |
223 | * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed. |
224 | */ |
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 |
234 | |
235 | #define BDI_CAP_VMFLAGS \ |
236 | (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP) |
237 | |
238 | #define BDI_CAP_NO_ACCT_AND_WRITEBACK \ |
239 | (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB) |
240 | |
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 |
246 | #endif |
247 | |
248 | extern struct backing_dev_info default_backing_dev_info; |
249 | void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page); |
250 | |
251 | int writeback_in_progress(struct backing_dev_info *bdi); |
252 | |
253 | static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits) |
254 | { |
255 | if (bdi->congested_fn) |
256 | return bdi->congested_fn(bdi->congested_data, bdi_bits); |
257 | return (bdi->state & bdi_bits); |
258 | } |
259 | |
260 | static inline int bdi_read_congested(struct backing_dev_info *bdi) |
261 | { |
262 | return bdi_congested(bdi, 1 << BDI_sync_congested); |
263 | } |
264 | |
265 | static inline int bdi_write_congested(struct backing_dev_info *bdi) |
266 | { |
267 | return bdi_congested(bdi, 1 << BDI_async_congested); |
268 | } |
269 | |
270 | static inline int bdi_rw_congested(struct backing_dev_info *bdi) |
271 | { |
272 | return bdi_congested(bdi, (1 << BDI_sync_congested) | |
273 | (1 << BDI_async_congested)); |
274 | } |
275 | |
276 | enum { |
277 | BLK_RW_ASYNC = 0, |
278 | BLK_RW_SYNC = 1, |
279 | }; |
280 | |
281 | void clear_bdi_congested(struct backing_dev_info *bdi, int sync); |
282 | void set_bdi_congested(struct backing_dev_info *bdi, int sync); |
283 | long congestion_wait(int sync, long timeout); |
284 | |
285 | |
286 | static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi) |
287 | { |
288 | return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK); |
289 | } |
290 | |
291 | static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi) |
292 | { |
293 | return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY); |
294 | } |
295 | |
296 | static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi) |
297 | { |
298 | /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */ |
299 | return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB | |
300 | BDI_CAP_NO_WRITEBACK)); |
301 | } |
302 | |
303 | static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi) |
304 | { |
305 | return bdi->capabilities & BDI_CAP_SWAP_BACKED; |
306 | } |
307 | |
308 | static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi) |
309 | { |
310 | return bdi == &default_backing_dev_info; |
311 | } |
312 | |
313 | static inline bool mapping_cap_writeback_dirty(struct address_space *mapping) |
314 | { |
315 | return bdi_cap_writeback_dirty(mapping->backing_dev_info); |
316 | } |
317 | |
318 | static inline bool mapping_cap_account_dirty(struct address_space *mapping) |
319 | { |
320 | return bdi_cap_account_dirty(mapping->backing_dev_info); |
321 | } |
322 | |
323 | static inline bool mapping_cap_swap_backed(struct address_space *mapping) |
324 | { |
325 | return bdi_cap_swap_backed(mapping->backing_dev_info); |
326 | } |
327 | |
328 | static inline int bdi_sched_wait(void *word) |
329 | { |
330 | schedule(); |
331 | return 0; |
332 | } |
333 | |
334 | #endif /* _LINUX_BACKING_DEV_H */ |
335 |
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