2 * include/linux/backing-dev.h
4 * low-level device information and state which is propagated up through
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/flex_proportions.h>
14 #include <linux/kernel.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>
28 * Bits in backing_dev_info.state
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 */
37 typedef int (congested_fn)(void *, int);
47 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
49 struct bdi_writeback {
50 struct backing_dev_info *bdi; /* our parent bdi */
52 unsigned long last_old_flush; /* last old data flush */
54 struct delayed_work dwork; /* work item used for writeback */
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 spinlock_t list_lock; /* protects the b_* lists */
61 struct backing_dev_info {
62 struct list_head bdi_list;
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 */
71 struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
73 unsigned long bw_time_stamp; /* last time write bw is updated */
74 unsigned long dirtied_stamp;
75 unsigned long written_stamp; /* pages written at bw_time_stamp */
76 unsigned long write_bandwidth; /* the estimated write bandwidth */
77 unsigned long avg_write_bandwidth; /* further smoothed write bw */
80 * The base dirty throttle rate, re-calculated on every 200ms.
81 * All the bdi tasks' dirty rate will be curbed under it.
82 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit
83 * in small steps and is much more smooth/stable than the latter.
85 unsigned long dirty_ratelimit;
86 unsigned long balanced_dirty_ratelimit;
88 struct fprop_local_percpu completions;
91 unsigned int min_ratio;
92 unsigned int max_ratio, max_prop_frac;
94 struct bdi_writeback wb; /* default writeback info for this bdi */
95 spinlock_t wb_lock; /* protects work_list & wb.dwork scheduling */
97 struct list_head work_list;
101 struct timer_list laptop_mode_wb_timer;
103 #ifdef CONFIG_DEBUG_FS
104 struct dentry *debug_dir;
105 struct dentry *debug_stats;
109 int __must_check bdi_init(struct backing_dev_info *bdi);
110 void bdi_destroy(struct backing_dev_info *bdi);
113 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
114 const char *fmt, ...);
115 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
116 void bdi_unregister(struct backing_dev_info *bdi);
117 int __must_check bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int);
118 void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
119 enum wb_reason reason);
120 void bdi_start_background_writeback(struct backing_dev_info *bdi);
121 void bdi_writeback_workfn(struct work_struct *work);
122 int bdi_has_dirty_io(struct backing_dev_info *bdi);
123 void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi);
124 void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2);
126 extern spinlock_t bdi_lock;
127 extern struct list_head bdi_list;
129 extern struct workqueue_struct *bdi_wq;
131 static inline int wb_has_dirty_io(struct bdi_writeback *wb)
133 return !list_empty(&wb->b_dirty) ||
134 !list_empty(&wb->b_io) ||
135 !list_empty(&wb->b_more_io);
138 static inline void __add_bdi_stat(struct backing_dev_info *bdi,
139 enum bdi_stat_item item, s64 amount)
141 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
144 static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
145 enum bdi_stat_item item)
147 __add_bdi_stat(bdi, item, 1);
150 static inline void inc_bdi_stat(struct backing_dev_info *bdi,
151 enum bdi_stat_item item)
155 local_irq_save(flags);
156 __inc_bdi_stat(bdi, item);
157 local_irq_restore(flags);
160 static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
161 enum bdi_stat_item item)
163 __add_bdi_stat(bdi, item, -1);
166 static inline void dec_bdi_stat(struct backing_dev_info *bdi,
167 enum bdi_stat_item item)
171 local_irq_save(flags);
172 __dec_bdi_stat(bdi, item);
173 local_irq_restore(flags);
176 static inline s64 bdi_stat(struct backing_dev_info *bdi,
177 enum bdi_stat_item item)
179 return percpu_counter_read_positive(&bdi->bdi_stat[item]);
182 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
183 enum bdi_stat_item item)
185 return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
188 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
189 enum bdi_stat_item item)
194 local_irq_save(flags);
195 sum = __bdi_stat_sum(bdi, item);
196 local_irq_restore(flags);
201 extern void bdi_writeout_inc(struct backing_dev_info *bdi);
204 * maximal error of a stat counter.
206 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
209 return nr_cpu_ids * BDI_STAT_BATCH;
215 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
216 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
219 * Flags in backing_dev_info::capability
221 * The first three flags control whether dirty pages will contribute to the
222 * VM's accounting and whether writepages() should be called for dirty pages
223 * (something that would not, for example, be appropriate for ramfs)
225 * WARNING: these flags are closely related and should not normally be
226 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
227 * three flags into a single convenience macro.
229 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
230 * BDI_CAP_NO_WRITEBACK: Don't write pages back
231 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
233 * These flags let !MMU mmap() govern direct device mapping vs immediate
234 * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
236 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE)
237 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED)
238 * BDI_CAP_READ_MAP: Can be mapped for reading
239 * BDI_CAP_WRITE_MAP: Can be mapped for writing
240 * BDI_CAP_EXEC_MAP: Can be mapped for execution
242 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed.
244 * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
246 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
247 #define BDI_CAP_NO_WRITEBACK 0x00000002
248 #define BDI_CAP_MAP_COPY 0x00000004
249 #define BDI_CAP_MAP_DIRECT 0x00000008
250 #define BDI_CAP_READ_MAP 0x00000010
251 #define BDI_CAP_WRITE_MAP 0x00000020
252 #define BDI_CAP_EXEC_MAP 0x00000040
253 #define BDI_CAP_NO_ACCT_WB 0x00000080
254 #define BDI_CAP_SWAP_BACKED 0x00000100
255 #define BDI_CAP_STABLE_WRITES 0x00000200
256 #define BDI_CAP_STRICTLIMIT 0x00000400
258 #define BDI_CAP_VMFLAGS \
259 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
261 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
262 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
264 #if defined(VM_MAYREAD) && \
265 (BDI_CAP_READ_MAP != VM_MAYREAD || \
266 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
267 BDI_CAP_EXEC_MAP != VM_MAYEXEC)
268 #error please change backing_dev_info::capabilities flags
271 extern struct backing_dev_info default_backing_dev_info;
272 extern struct backing_dev_info noop_backing_dev_info;
274 int writeback_in_progress(struct backing_dev_info *bdi);
276 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
278 if (bdi->congested_fn)
279 return bdi->congested_fn(bdi->congested_data, bdi_bits);
280 return (bdi->state & bdi_bits);
283 static inline int bdi_read_congested(struct backing_dev_info *bdi)
285 return bdi_congested(bdi, 1 << BDI_sync_congested);
288 static inline int bdi_write_congested(struct backing_dev_info *bdi)
290 return bdi_congested(bdi, 1 << BDI_async_congested);
293 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
295 return bdi_congested(bdi, (1 << BDI_sync_congested) |
296 (1 << BDI_async_congested));
304 void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
305 void set_bdi_congested(struct backing_dev_info *bdi, int sync);
306 long congestion_wait(int sync, long timeout);
307 long wait_iff_congested(struct zone *zone, int sync, long timeout);
308 int pdflush_proc_obsolete(struct ctl_table *table, int write,
309 void __user *buffer, size_t *lenp, loff_t *ppos);
311 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi)
313 return bdi->capabilities & BDI_CAP_STABLE_WRITES;
316 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
318 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
321 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
323 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
326 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
328 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
329 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
330 BDI_CAP_NO_WRITEBACK));
333 static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
335 return bdi->capabilities & BDI_CAP_SWAP_BACKED;
338 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
340 return bdi_cap_writeback_dirty(mapping->backing_dev_info);
343 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
345 return bdi_cap_account_dirty(mapping->backing_dev_info);
348 static inline bool mapping_cap_swap_backed(struct address_space *mapping)
350 return bdi_cap_swap_backed(mapping->backing_dev_info);
353 static inline int bdi_sched_wait(void *word)
359 #endif /* _LINUX_BACKING_DEV_H */