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 struct backing_dev_info
*inode_to_bdi(struct inode
*inode
);
111 int __must_check
bdi_init(struct backing_dev_info
*bdi
);
112 void bdi_destroy(struct backing_dev_info
*bdi
);
115 int bdi_register(struct backing_dev_info
*bdi
, struct device
*parent
,
116 const char *fmt
, ...);
117 int bdi_register_dev(struct backing_dev_info
*bdi
, dev_t dev
);
118 void bdi_unregister(struct backing_dev_info
*bdi
);
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 */