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 struct list_head b_dirty_time; /* time stamps are dirty */
59 spinlock_t list_lock; /* protects the b_* lists */
62 struct backing_dev_info {
63 struct list_head bdi_list;
64 unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
65 unsigned long state; /* Always use atomic bitops on this */
66 unsigned int capabilities; /* Device capabilities */
67 congested_fn *congested_fn; /* Function pointer if device is md/dm */
68 void *congested_data; /* Pointer to aux data for congested func */
72 struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
74 unsigned long bw_time_stamp; /* last time write bw is updated */
75 unsigned long dirtied_stamp;
76 unsigned long written_stamp; /* pages written at bw_time_stamp */
77 unsigned long write_bandwidth; /* the estimated write bandwidth */
78 unsigned long avg_write_bandwidth; /* further smoothed write bw */
81 * The base dirty throttle rate, re-calculated on every 200ms.
82 * All the bdi tasks' dirty rate will be curbed under it.
83 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit
84 * in small steps and is much more smooth/stable than the latter.
86 unsigned long dirty_ratelimit;
87 unsigned long balanced_dirty_ratelimit;
89 struct fprop_local_percpu completions;
92 unsigned int min_ratio;
93 unsigned int max_ratio, max_prop_frac;
95 struct bdi_writeback wb; /* default writeback info for this bdi */
96 spinlock_t wb_lock; /* protects work_list & wb.dwork scheduling */
98 struct list_head work_list;
102 struct timer_list laptop_mode_wb_timer;
104 #ifdef CONFIG_DEBUG_FS
105 struct dentry *debug_dir;
106 struct dentry *debug_stats;
110 struct backing_dev_info *inode_to_bdi(struct inode *inode);
112 int __must_check bdi_init(struct backing_dev_info *bdi);
113 void bdi_destroy(struct backing_dev_info *bdi);
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 int __must_check bdi_setup_and_register(struct backing_dev_info *, char *);
120 void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
121 enum wb_reason reason);
122 void bdi_start_background_writeback(struct backing_dev_info *bdi);
123 void bdi_writeback_workfn(struct work_struct *work);
124 int bdi_has_dirty_io(struct backing_dev_info *bdi);
125 void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi);
127 extern spinlock_t bdi_lock;
128 extern struct list_head bdi_list;
130 extern struct workqueue_struct *bdi_wq;
132 static inline int wb_has_dirty_io(struct bdi_writeback *wb)
134 return !list_empty(&wb->b_dirty) ||
135 !list_empty(&wb->b_io) ||
136 !list_empty(&wb->b_more_io);
139 static inline void __add_bdi_stat(struct backing_dev_info *bdi,
140 enum bdi_stat_item item, s64 amount)
142 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
145 static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
146 enum bdi_stat_item item)
148 __add_bdi_stat(bdi, item, 1);
151 static inline void inc_bdi_stat(struct backing_dev_info *bdi,
152 enum bdi_stat_item item)
156 local_irq_save(flags);
157 __inc_bdi_stat(bdi, item);
158 local_irq_restore(flags);
161 static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
162 enum bdi_stat_item item)
164 __add_bdi_stat(bdi, item, -1);
167 static inline void dec_bdi_stat(struct backing_dev_info *bdi,
168 enum bdi_stat_item item)
172 local_irq_save(flags);
173 __dec_bdi_stat(bdi, item);
174 local_irq_restore(flags);
177 static inline s64 bdi_stat(struct backing_dev_info *bdi,
178 enum bdi_stat_item item)
180 return percpu_counter_read_positive(&bdi->bdi_stat[item]);
183 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
184 enum bdi_stat_item item)
186 return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
189 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
190 enum bdi_stat_item item)
195 local_irq_save(flags);
196 sum = __bdi_stat_sum(bdi, item);
197 local_irq_restore(flags);
202 extern void bdi_writeout_inc(struct backing_dev_info *bdi);
205 * maximal error of a stat counter.
207 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
210 return nr_cpu_ids * BDI_STAT_BATCH;
216 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
217 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
220 * Flags in backing_dev_info::capability
222 * The first three flags control whether dirty pages will contribute to the
223 * VM's accounting and whether writepages() should be called for dirty pages
224 * (something that would not, for example, be appropriate for ramfs)
226 * WARNING: these flags are closely related and should not normally be
227 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
228 * three flags into a single convenience macro.
230 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
231 * BDI_CAP_NO_WRITEBACK: Don't write pages back
232 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
233 * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
235 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
236 #define BDI_CAP_NO_WRITEBACK 0x00000002
237 #define BDI_CAP_NO_ACCT_WB 0x00000004
238 #define BDI_CAP_STABLE_WRITES 0x00000008
239 #define BDI_CAP_STRICTLIMIT 0x00000010
241 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
242 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
244 extern struct backing_dev_info noop_backing_dev_info;
246 int writeback_in_progress(struct backing_dev_info *bdi);
248 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
250 if (bdi->congested_fn)
251 return bdi->congested_fn(bdi->congested_data, bdi_bits);
252 return (bdi->state & bdi_bits);
255 static inline int bdi_read_congested(struct backing_dev_info *bdi)
257 return bdi_congested(bdi, 1 << BDI_sync_congested);
260 static inline int bdi_write_congested(struct backing_dev_info *bdi)
262 return bdi_congested(bdi, 1 << BDI_async_congested);
265 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
267 return bdi_congested(bdi, (1 << BDI_sync_congested) |
268 (1 << BDI_async_congested));
276 void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
277 void set_bdi_congested(struct backing_dev_info *bdi, int sync);
278 long congestion_wait(int sync, long timeout);
279 long wait_iff_congested(struct zone *zone, int sync, long timeout);
280 int pdflush_proc_obsolete(struct ctl_table *table, int write,
281 void __user *buffer, size_t *lenp, loff_t *ppos);
283 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi)
285 return bdi->capabilities & BDI_CAP_STABLE_WRITES;
288 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
290 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
293 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
295 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
298 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
300 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
301 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
302 BDI_CAP_NO_WRITEBACK));
305 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
307 return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host));
310 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
312 return bdi_cap_account_dirty(inode_to_bdi(mapping->host));
315 static inline int bdi_sched_wait(void *word)
321 #endif /* _LINUX_BACKING_DEV_H */