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_wb_alloc
, /* Default embedded wb allocated */
32 BDI_async_congested
, /* The async (write) queue is getting full */
33 BDI_sync_congested
, /* The sync queue is getting full */
34 BDI_registered
, /* bdi_register() was done */
35 BDI_writeback_running
, /* Writeback is in progress */
36 BDI_unused
, /* Available bits start here */
39 typedef int (congested_fn
)(void *, int);
49 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
51 struct bdi_writeback
{
52 struct backing_dev_info
*bdi
; /* our parent bdi */
55 unsigned long last_old_flush
; /* last old data flush */
57 struct delayed_work dwork
; /* work item used for writeback */
58 struct list_head b_dirty
; /* dirty inodes */
59 struct list_head b_io
; /* parked for writeback */
60 struct list_head b_more_io
; /* parked for more writeback */
61 spinlock_t list_lock
; /* protects the b_* lists */
64 struct backing_dev_info
{
65 struct list_head bdi_list
;
66 unsigned long ra_pages
; /* max readahead in PAGE_CACHE_SIZE units */
67 unsigned long state
; /* Always use atomic bitops on this */
68 unsigned int capabilities
; /* Device capabilities */
69 congested_fn
*congested_fn
; /* Function pointer if device is md/dm */
70 void *congested_data
; /* Pointer to aux data for congested func */
74 struct percpu_counter bdi_stat
[NR_BDI_STAT_ITEMS
];
76 unsigned long bw_time_stamp
; /* last time write bw is updated */
77 unsigned long dirtied_stamp
;
78 unsigned long written_stamp
; /* pages written at bw_time_stamp */
79 unsigned long write_bandwidth
; /* the estimated write bandwidth */
80 unsigned long avg_write_bandwidth
; /* further smoothed write bw */
83 * The base dirty throttle rate, re-calculated on every 200ms.
84 * All the bdi tasks' dirty rate will be curbed under it.
85 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit
86 * in small steps and is much more smooth/stable than the latter.
88 unsigned long dirty_ratelimit
;
89 unsigned long balanced_dirty_ratelimit
;
91 struct fprop_local_percpu completions
;
94 unsigned int min_ratio
;
95 unsigned int max_ratio
, max_prop_frac
;
97 struct bdi_writeback wb
; /* default writeback info for this bdi */
98 spinlock_t wb_lock
; /* protects work_list */
100 struct list_head work_list
;
104 struct timer_list laptop_mode_wb_timer
;
106 #ifdef CONFIG_DEBUG_FS
107 struct dentry
*debug_dir
;
108 struct dentry
*debug_stats
;
112 int 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 bdi_setup_and_register(struct backing_dev_info
*, char *, unsigned int);
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
);
127 void bdi_lock_two(struct bdi_writeback
*wb1
, struct bdi_writeback
*wb2
);
129 extern spinlock_t bdi_lock
;
130 extern struct list_head bdi_list
;
132 extern struct workqueue_struct
*bdi_wq
;
134 static inline int wb_has_dirty_io(struct bdi_writeback
*wb
)
136 return !list_empty(&wb
->b_dirty
) ||
137 !list_empty(&wb
->b_io
) ||
138 !list_empty(&wb
->b_more_io
);
141 static inline void __add_bdi_stat(struct backing_dev_info
*bdi
,
142 enum bdi_stat_item item
, s64 amount
)
144 __percpu_counter_add(&bdi
->bdi_stat
[item
], amount
, BDI_STAT_BATCH
);
147 static inline void __inc_bdi_stat(struct backing_dev_info
*bdi
,
148 enum bdi_stat_item item
)
150 __add_bdi_stat(bdi
, item
, 1);
153 static inline void inc_bdi_stat(struct backing_dev_info
*bdi
,
154 enum bdi_stat_item item
)
158 local_irq_save(flags
);
159 __inc_bdi_stat(bdi
, item
);
160 local_irq_restore(flags
);
163 static inline void __dec_bdi_stat(struct backing_dev_info
*bdi
,
164 enum bdi_stat_item item
)
166 __add_bdi_stat(bdi
, item
, -1);
169 static inline void dec_bdi_stat(struct backing_dev_info
*bdi
,
170 enum bdi_stat_item item
)
174 local_irq_save(flags
);
175 __dec_bdi_stat(bdi
, item
);
176 local_irq_restore(flags
);
179 static inline s64
bdi_stat(struct backing_dev_info
*bdi
,
180 enum bdi_stat_item item
)
182 return percpu_counter_read_positive(&bdi
->bdi_stat
[item
]);
185 static inline s64
__bdi_stat_sum(struct backing_dev_info
*bdi
,
186 enum bdi_stat_item item
)
188 return percpu_counter_sum_positive(&bdi
->bdi_stat
[item
]);
191 static inline s64
bdi_stat_sum(struct backing_dev_info
*bdi
,
192 enum bdi_stat_item item
)
197 local_irq_save(flags
);
198 sum
= __bdi_stat_sum(bdi
, item
);
199 local_irq_restore(flags
);
204 extern void bdi_writeout_inc(struct backing_dev_info
*bdi
);
207 * maximal error of a stat counter.
209 static inline unsigned long bdi_stat_error(struct backing_dev_info
*bdi
)
212 return nr_cpu_ids
* BDI_STAT_BATCH
;
218 int bdi_set_min_ratio(struct backing_dev_info
*bdi
, unsigned int min_ratio
);
219 int bdi_set_max_ratio(struct backing_dev_info
*bdi
, unsigned int max_ratio
);
222 * Flags in backing_dev_info::capability
224 * The first three flags control whether dirty pages will contribute to the
225 * VM's accounting and whether writepages() should be called for dirty pages
226 * (something that would not, for example, be appropriate for ramfs)
228 * WARNING: these flags are closely related and should not normally be
229 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
230 * three flags into a single convenience macro.
232 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
233 * BDI_CAP_NO_WRITEBACK: Don't write pages back
234 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
236 * These flags let !MMU mmap() govern direct device mapping vs immediate
237 * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
239 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE)
240 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED)
241 * BDI_CAP_READ_MAP: Can be mapped for reading
242 * BDI_CAP_WRITE_MAP: Can be mapped for writing
243 * BDI_CAP_EXEC_MAP: Can be mapped for execution
245 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed.
247 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
248 #define BDI_CAP_NO_WRITEBACK 0x00000002
249 #define BDI_CAP_MAP_COPY 0x00000004
250 #define BDI_CAP_MAP_DIRECT 0x00000008
251 #define BDI_CAP_READ_MAP 0x00000010
252 #define BDI_CAP_WRITE_MAP 0x00000020
253 #define BDI_CAP_EXEC_MAP 0x00000040
254 #define BDI_CAP_NO_ACCT_WB 0x00000080
255 #define BDI_CAP_SWAP_BACKED 0x00000100
256 #define BDI_CAP_STABLE_WRITES 0x00000200
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 */