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
);
125 extern spinlock_t bdi_lock
;
126 extern struct list_head bdi_list
;
128 extern struct workqueue_struct
*bdi_wq
;
130 static inline int wb_has_dirty_io(struct bdi_writeback
*wb
)
132 return !list_empty(&wb
->b_dirty
) ||
133 !list_empty(&wb
->b_io
) ||
134 !list_empty(&wb
->b_more_io
);
137 static inline void __add_bdi_stat(struct backing_dev_info
*bdi
,
138 enum bdi_stat_item item
, s64 amount
)
140 __percpu_counter_add(&bdi
->bdi_stat
[item
], amount
, BDI_STAT_BATCH
);
143 static inline void __inc_bdi_stat(struct backing_dev_info
*bdi
,
144 enum bdi_stat_item item
)
146 __add_bdi_stat(bdi
, item
, 1);
149 static inline void inc_bdi_stat(struct backing_dev_info
*bdi
,
150 enum bdi_stat_item item
)
154 local_irq_save(flags
);
155 __inc_bdi_stat(bdi
, item
);
156 local_irq_restore(flags
);
159 static inline void __dec_bdi_stat(struct backing_dev_info
*bdi
,
160 enum bdi_stat_item item
)
162 __add_bdi_stat(bdi
, item
, -1);
165 static inline void dec_bdi_stat(struct backing_dev_info
*bdi
,
166 enum bdi_stat_item item
)
170 local_irq_save(flags
);
171 __dec_bdi_stat(bdi
, item
);
172 local_irq_restore(flags
);
175 static inline s64
bdi_stat(struct backing_dev_info
*bdi
,
176 enum bdi_stat_item item
)
178 return percpu_counter_read_positive(&bdi
->bdi_stat
[item
]);
181 static inline s64
__bdi_stat_sum(struct backing_dev_info
*bdi
,
182 enum bdi_stat_item item
)
184 return percpu_counter_sum_positive(&bdi
->bdi_stat
[item
]);
187 static inline s64
bdi_stat_sum(struct backing_dev_info
*bdi
,
188 enum bdi_stat_item item
)
193 local_irq_save(flags
);
194 sum
= __bdi_stat_sum(bdi
, item
);
195 local_irq_restore(flags
);
200 extern void bdi_writeout_inc(struct backing_dev_info
*bdi
);
203 * maximal error of a stat counter.
205 static inline unsigned long bdi_stat_error(struct backing_dev_info
*bdi
)
208 return nr_cpu_ids
* BDI_STAT_BATCH
;
214 int bdi_set_min_ratio(struct backing_dev_info
*bdi
, unsigned int min_ratio
);
215 int bdi_set_max_ratio(struct backing_dev_info
*bdi
, unsigned int max_ratio
);
218 * Flags in backing_dev_info::capability
220 * The first three flags control whether dirty pages will contribute to the
221 * VM's accounting and whether writepages() should be called for dirty pages
222 * (something that would not, for example, be appropriate for ramfs)
224 * WARNING: these flags are closely related and should not normally be
225 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
226 * three flags into a single convenience macro.
228 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
229 * BDI_CAP_NO_WRITEBACK: Don't write pages back
230 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
232 * These flags let !MMU mmap() govern direct device mapping vs immediate
233 * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
235 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE)
236 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED)
237 * BDI_CAP_READ_MAP: Can be mapped for reading
238 * BDI_CAP_WRITE_MAP: Can be mapped for writing
239 * BDI_CAP_EXEC_MAP: Can be mapped for execution
241 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed.
243 * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold.
245 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
246 #define BDI_CAP_NO_WRITEBACK 0x00000002
247 #define BDI_CAP_MAP_COPY 0x00000004
248 #define BDI_CAP_MAP_DIRECT 0x00000008
249 #define BDI_CAP_READ_MAP 0x00000010
250 #define BDI_CAP_WRITE_MAP 0x00000020
251 #define BDI_CAP_EXEC_MAP 0x00000040
252 #define BDI_CAP_NO_ACCT_WB 0x00000080
253 #define BDI_CAP_SWAP_BACKED 0x00000100
254 #define BDI_CAP_STABLE_WRITES 0x00000200
255 #define BDI_CAP_STRICTLIMIT 0x00000400
257 #define BDI_CAP_VMFLAGS \
258 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
260 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
261 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
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
270 extern struct backing_dev_info default_backing_dev_info
;
271 extern struct backing_dev_info noop_backing_dev_info
;
273 int writeback_in_progress(struct backing_dev_info
*bdi
);
275 static inline int bdi_congested(struct backing_dev_info
*bdi
, int bdi_bits
)
277 if (bdi
->congested_fn
)
278 return bdi
->congested_fn(bdi
->congested_data
, bdi_bits
);
279 return (bdi
->state
& bdi_bits
);
282 static inline int bdi_read_congested(struct backing_dev_info
*bdi
)
284 return bdi_congested(bdi
, 1 << BDI_sync_congested
);
287 static inline int bdi_write_congested(struct backing_dev_info
*bdi
)
289 return bdi_congested(bdi
, 1 << BDI_async_congested
);
292 static inline int bdi_rw_congested(struct backing_dev_info
*bdi
)
294 return bdi_congested(bdi
, (1 << BDI_sync_congested
) |
295 (1 << BDI_async_congested
));
303 void clear_bdi_congested(struct backing_dev_info
*bdi
, int sync
);
304 void set_bdi_congested(struct backing_dev_info
*bdi
, int sync
);
305 long congestion_wait(int sync
, long timeout
);
306 long wait_iff_congested(struct zone
*zone
, int sync
, long timeout
);
307 int pdflush_proc_obsolete(struct ctl_table
*table
, int write
,
308 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
);
310 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info
*bdi
)
312 return bdi
->capabilities
& BDI_CAP_STABLE_WRITES
;
315 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info
*bdi
)
317 return !(bdi
->capabilities
& BDI_CAP_NO_WRITEBACK
);
320 static inline bool bdi_cap_account_dirty(struct backing_dev_info
*bdi
)
322 return !(bdi
->capabilities
& BDI_CAP_NO_ACCT_DIRTY
);
325 static inline bool bdi_cap_account_writeback(struct backing_dev_info
*bdi
)
327 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
328 return !(bdi
->capabilities
& (BDI_CAP_NO_ACCT_WB
|
329 BDI_CAP_NO_WRITEBACK
));
332 static inline bool bdi_cap_swap_backed(struct backing_dev_info
*bdi
)
334 return bdi
->capabilities
& BDI_CAP_SWAP_BACKED
;
337 static inline bool mapping_cap_writeback_dirty(struct address_space
*mapping
)
339 return bdi_cap_writeback_dirty(mapping
->backing_dev_info
);
342 static inline bool mapping_cap_account_dirty(struct address_space
*mapping
)
344 return bdi_cap_account_dirty(mapping
->backing_dev_info
);
347 static inline bool mapping_cap_swap_backed(struct address_space
*mapping
)
349 return bdi_cap_swap_backed(mapping
->backing_dev_info
);
352 static inline int bdi_sched_wait(void *word
)
358 #endif /* _LINUX_BACKING_DEV_H */