projects/linux·blob v3.7-rc3 · refs

358 lines · 10.2 KiB

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
22struct page;
23struct device;
24struct dentry;
25
26/*
27 * Bits in backing_dev_info.state
28 */
29enum bdi_state {
30 BDI_pending, /* On its way to being activated */
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
39typedef int (congested_fn)(void *, int);
40
41enum 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
51struct 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 unsigned long last_active; /* last time bdi thread was active */
57
58 struct task_struct *task; /* writeback thread */
59 struct timer_list wakeup_timer; /* used for delayed bdi thread wakeup */
60 struct list_head b_dirty; /* dirty inodes */
61 struct list_head b_io; /* parked for writeback */
62 struct list_head b_more_io; /* parked for more writeback */
63 spinlock_t list_lock; /* protects the b_* lists */
64};
65
66struct backing_dev_info {
67 struct list_head bdi_list;
68 unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
69 unsigned long state; /* Always use atomic bitops on this */
70 unsigned int capabilities; /* Device capabilities */
71 congested_fn *congested_fn; /* Function pointer if device is md/dm */
72 void *congested_data; /* Pointer to aux data for congested func */
73
74 char *name;
75
76 struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
77
78 unsigned long bw_time_stamp; /* last time write bw is updated */
79 unsigned long dirtied_stamp;
80 unsigned long written_stamp; /* pages written at bw_time_stamp */
81 unsigned long write_bandwidth; /* the estimated write bandwidth */
82 unsigned long avg_write_bandwidth; /* further smoothed write bw */
83
84 /*
85 * The base dirty throttle rate, re-calculated on every 200ms.
86 * All the bdi tasks' dirty rate will be curbed under it.
87 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit
88 * in small steps and is much more smooth/stable than the latter.
89 */
90 unsigned long dirty_ratelimit;
91 unsigned long balanced_dirty_ratelimit;
92
93 struct fprop_local_percpu completions;
94 int dirty_exceeded;
95
96 unsigned int min_ratio;
97 unsigned int max_ratio, max_prop_frac;
98
99 struct bdi_writeback wb; /* default writeback info for this bdi */
100 spinlock_t wb_lock; /* protects work_list */
101
102 struct list_head work_list;
103
104 struct device *dev;
105
106 struct timer_list laptop_mode_wb_timer;
107
108#ifdef CONFIG_DEBUG_FS
109 struct dentry *debug_dir;
110 struct dentry *debug_stats;
111#endif
112};
113
114int bdi_init(struct backing_dev_info *bdi);
115void bdi_destroy(struct backing_dev_info *bdi);
116
117int bdi_register(struct backing_dev_info *bdi, struct device *parent,
118 const char *fmt, ...);
119int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
120void bdi_unregister(struct backing_dev_info *bdi);
121int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int);
122void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
123 enum wb_reason reason);
124void bdi_start_background_writeback(struct backing_dev_info *bdi);
125int bdi_writeback_thread(void *data);
126int bdi_has_dirty_io(struct backing_dev_info *bdi);
127void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi);
128void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2);
129
130extern spinlock_t bdi_lock;
131extern struct list_head bdi_list;
132extern struct list_head bdi_pending_list;
133
134static 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
141static 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
147static 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
153static 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
163static 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
169static 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
179static 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
185static 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
191static 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
204extern void bdi_writeout_inc(struct backing_dev_info *bdi);
205
206/*
207 * maximal error of a stat counter.
208 */
209static 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
218int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
219int 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#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
256
257#define BDI_CAP_VMFLAGS \
258 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
259
260#define BDI_CAP_NO_ACCT_AND_WRITEBACK \
261 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
262
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
269
270extern struct backing_dev_info default_backing_dev_info;
271extern struct backing_dev_info noop_backing_dev_info;
272
273int writeback_in_progress(struct backing_dev_info *bdi);
274
275static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
276{
277 if (bdi->congested_fn)
278 return bdi->congested_fn(bdi->congested_data, bdi_bits);
279 return (bdi->state & bdi_bits);
280}
281
282static inline int bdi_read_congested(struct backing_dev_info *bdi)
283{
284 return bdi_congested(bdi, 1 << BDI_sync_congested);
285}
286
287static inline int bdi_write_congested(struct backing_dev_info *bdi)
288{
289 return bdi_congested(bdi, 1 << BDI_async_congested);
290}
291
292static inline int bdi_rw_congested(struct backing_dev_info *bdi)
293{
294 return bdi_congested(bdi, (1 << BDI_sync_congested) |
295 (1 << BDI_async_congested));
296}
297
298enum {
299 BLK_RW_ASYNC = 0,
300 BLK_RW_SYNC = 1,
301};
302
303void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
304void set_bdi_congested(struct backing_dev_info *bdi, int sync);
305long congestion_wait(int sync, long timeout);
306long wait_iff_congested(struct zone *zone, int sync, long timeout);
307int pdflush_proc_obsolete(struct ctl_table *table, int write,
308 void __user *buffer, size_t *lenp, loff_t *ppos);
309
310static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
311{
312 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
313}
314
315static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
316{
317 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
318}
319
320static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
321{
322 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
323 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
324 BDI_CAP_NO_WRITEBACK));
325}
326
327static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
328{
329 return bdi->capabilities & BDI_CAP_SWAP_BACKED;
330}
331
332static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi)
333{
334 return bdi == &default_backing_dev_info;
335}
336
337static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
338{
339 return bdi_cap_writeback_dirty(mapping->backing_dev_info);
340}
341
342static inline bool mapping_cap_account_dirty(struct address_space *mapping)
343{
344 return bdi_cap_account_dirty(mapping->backing_dev_info);
345}
346
347static inline bool mapping_cap_swap_backed(struct address_space *mapping)
348{
349 return bdi_cap_swap_backed(mapping->backing_dev_info);
350}
351
352static inline int bdi_sched_wait(void *word)
353{
354 schedule();
355 return 0;
356}
357
358#endif /* _LINUX_BACKING_DEV_H */