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 void bdi_unregister(struct backing_dev_info
*bdi
);
120 int __must_check
bdi_setup_and_register(struct backing_dev_info
*, char *);
121 void bdi_start_writeback(struct backing_dev_info
*bdi
, long nr_pages
,
122 enum wb_reason reason
);
123 void bdi_start_background_writeback(struct backing_dev_info
*bdi
);
124 void bdi_writeback_workfn(struct work_struct
*work
);
125 int bdi_has_dirty_io(struct backing_dev_info
*bdi
);
126 void bdi_wakeup_thread_delayed(struct backing_dev_info
*bdi
);
128 extern spinlock_t bdi_lock
;
129 extern struct list_head bdi_list
;
131 extern struct workqueue_struct
*bdi_wq
;
133 static inline int wb_has_dirty_io(struct bdi_writeback
*wb
)
135 return !list_empty(&wb
->b_dirty
) ||
136 !list_empty(&wb
->b_io
) ||
137 !list_empty(&wb
->b_more_io
);
140 static inline void __add_bdi_stat(struct backing_dev_info
*bdi
,
141 enum bdi_stat_item item
, s64 amount
)
143 __percpu_counter_add(&bdi
->bdi_stat
[item
], amount
, BDI_STAT_BATCH
);
146 static inline void __inc_bdi_stat(struct backing_dev_info
*bdi
,
147 enum bdi_stat_item item
)
149 __add_bdi_stat(bdi
, item
, 1);
152 static inline void inc_bdi_stat(struct backing_dev_info
*bdi
,
153 enum bdi_stat_item item
)
157 local_irq_save(flags
);
158 __inc_bdi_stat(bdi
, item
);
159 local_irq_restore(flags
);
162 static inline void __dec_bdi_stat(struct backing_dev_info
*bdi
,
163 enum bdi_stat_item item
)
165 __add_bdi_stat(bdi
, item
, -1);
168 static inline void dec_bdi_stat(struct backing_dev_info
*bdi
,
169 enum bdi_stat_item item
)
173 local_irq_save(flags
);
174 __dec_bdi_stat(bdi
, item
);
175 local_irq_restore(flags
);
178 static inline s64
bdi_stat(struct backing_dev_info
*bdi
,
179 enum bdi_stat_item item
)
181 return percpu_counter_read_positive(&bdi
->bdi_stat
[item
]);
184 static inline s64
__bdi_stat_sum(struct backing_dev_info
*bdi
,
185 enum bdi_stat_item item
)
187 return percpu_counter_sum_positive(&bdi
->bdi_stat
[item
]);
190 static inline s64
bdi_stat_sum(struct backing_dev_info
*bdi
,
191 enum bdi_stat_item item
)
196 local_irq_save(flags
);
197 sum
= __bdi_stat_sum(bdi
, item
);
198 local_irq_restore(flags
);
203 extern void bdi_writeout_inc(struct backing_dev_info
*bdi
);
206 * maximal error of a stat counter.
208 static inline unsigned long bdi_stat_error(struct backing_dev_info
*bdi
)
211 return nr_cpu_ids
* BDI_STAT_BATCH
;
217 int bdi_set_min_ratio(struct backing_dev_info
*bdi
, unsigned int min_ratio
);
218 int bdi_set_max_ratio(struct backing_dev_info
*bdi
, unsigned int max_ratio
);
221 * Flags in backing_dev_info::capability
223 * The first three flags control whether dirty pages will contribute to the
224 * VM's accounting and whether writepages() should be called for dirty pages
225 * (something that would not, for example, be appropriate for ramfs)
227 * WARNING: these flags are closely related and should not normally be
228 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
229 * three flags into a single convenience macro.
231 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
232 * BDI_CAP_NO_WRITEBACK: Don't write pages back
233 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
234 * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
236 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
237 #define BDI_CAP_NO_WRITEBACK 0x00000002
238 #define BDI_CAP_NO_ACCT_WB 0x00000004
239 #define BDI_CAP_STABLE_WRITES 0x00000008
240 #define BDI_CAP_STRICTLIMIT 0x00000010
242 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
243 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
245 extern struct backing_dev_info noop_backing_dev_info
;
247 int writeback_in_progress(struct backing_dev_info
*bdi
);
249 static inline int bdi_congested(struct backing_dev_info
*bdi
, int bdi_bits
)
251 if (bdi
->congested_fn
)
252 return bdi
->congested_fn(bdi
->congested_data
, bdi_bits
);
253 return (bdi
->state
& bdi_bits
);
256 static inline int bdi_read_congested(struct backing_dev_info
*bdi
)
258 return bdi_congested(bdi
, 1 << BDI_sync_congested
);
261 static inline int bdi_write_congested(struct backing_dev_info
*bdi
)
263 return bdi_congested(bdi
, 1 << BDI_async_congested
);
266 static inline int bdi_rw_congested(struct backing_dev_info
*bdi
)
268 return bdi_congested(bdi
, (1 << BDI_sync_congested
) |
269 (1 << BDI_async_congested
));
277 void clear_bdi_congested(struct backing_dev_info
*bdi
, int sync
);
278 void set_bdi_congested(struct backing_dev_info
*bdi
, int sync
);
279 long congestion_wait(int sync
, long timeout
);
280 long wait_iff_congested(struct zone
*zone
, int sync
, long timeout
);
281 int pdflush_proc_obsolete(struct ctl_table
*table
, int write
,
282 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
);
284 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info
*bdi
)
286 return bdi
->capabilities
& BDI_CAP_STABLE_WRITES
;
289 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info
*bdi
)
291 return !(bdi
->capabilities
& BDI_CAP_NO_WRITEBACK
);
294 static inline bool bdi_cap_account_dirty(struct backing_dev_info
*bdi
)
296 return !(bdi
->capabilities
& BDI_CAP_NO_ACCT_DIRTY
);
299 static inline bool bdi_cap_account_writeback(struct backing_dev_info
*bdi
)
301 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
302 return !(bdi
->capabilities
& (BDI_CAP_NO_ACCT_WB
|
303 BDI_CAP_NO_WRITEBACK
));
306 static inline bool mapping_cap_writeback_dirty(struct address_space
*mapping
)
308 return bdi_cap_writeback_dirty(inode_to_bdi(mapping
->host
));
311 static inline bool mapping_cap_account_dirty(struct address_space
*mapping
)
313 return bdi_cap_account_dirty(inode_to_bdi(mapping
->host
));
316 static inline int bdi_sched_wait(void *word
)
322 #endif /* _LINUX_BACKING_DEV_H */