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/proportions.h>
14 #include <linux/kernel.h>
16 #include <linux/sched.h>
17 #include <linux/timer.h>
18 #include <linux/writeback.h>
19 #include <asm/atomic.h>
26 * Bits in backing_dev_info.state
29 BDI_pending
, /* On its way to being activated */
30 BDI_wb_alloc
, /* Default embedded wb allocated */
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_unused
, /* Available bits start here */
37 typedef int (congested_fn
)(void *, int);
45 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
47 struct bdi_writeback
{
48 struct backing_dev_info
*bdi
; /* our parent bdi */
51 unsigned long last_old_flush
; /* last old data flush */
52 unsigned long last_active
; /* last time bdi thread was active */
54 struct task_struct
*task
; /* writeback thread */
55 struct timer_list wakeup_timer
; /* used for delayed bdi thread wakeup */
56 struct list_head b_dirty
; /* dirty inodes */
57 struct list_head b_io
; /* parked for writeback */
58 struct list_head b_more_io
; /* parked for more writeback */
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 */
68 void (*unplug_io_fn
)(struct backing_dev_info
*, struct page
*);
73 struct percpu_counter bdi_stat
[NR_BDI_STAT_ITEMS
];
75 struct prop_local_percpu completions
;
78 unsigned int min_ratio
;
79 unsigned int max_ratio
, max_prop_frac
;
81 struct bdi_writeback wb
; /* default writeback info for this bdi */
82 spinlock_t wb_lock
; /* protects work_list */
84 struct list_head work_list
;
88 struct timer_list laptop_mode_wb_timer
;
90 #ifdef CONFIG_DEBUG_FS
91 struct dentry
*debug_dir
;
92 struct dentry
*debug_stats
;
96 int bdi_init(struct backing_dev_info
*bdi
);
97 void bdi_destroy(struct backing_dev_info
*bdi
);
99 int bdi_register(struct backing_dev_info
*bdi
, struct device
*parent
,
100 const char *fmt
, ...);
101 int bdi_register_dev(struct backing_dev_info
*bdi
, dev_t dev
);
102 void bdi_unregister(struct backing_dev_info
*bdi
);
103 int bdi_setup_and_register(struct backing_dev_info
*, char *, unsigned int);
104 void bdi_start_writeback(struct backing_dev_info
*bdi
, long nr_pages
);
105 void bdi_start_background_writeback(struct backing_dev_info
*bdi
);
106 int bdi_writeback_thread(void *data
);
107 int bdi_has_dirty_io(struct backing_dev_info
*bdi
);
108 void bdi_arm_supers_timer(void);
109 void bdi_wakeup_thread_delayed(struct backing_dev_info
*bdi
);
111 extern spinlock_t bdi_lock
;
112 extern struct list_head bdi_list
;
114 static inline int wb_has_dirty_io(struct bdi_writeback
*wb
)
116 return !list_empty(&wb
->b_dirty
) ||
117 !list_empty(&wb
->b_io
) ||
118 !list_empty(&wb
->b_more_io
);
121 static inline void __add_bdi_stat(struct backing_dev_info
*bdi
,
122 enum bdi_stat_item item
, s64 amount
)
124 __percpu_counter_add(&bdi
->bdi_stat
[item
], amount
, BDI_STAT_BATCH
);
127 static inline void __inc_bdi_stat(struct backing_dev_info
*bdi
,
128 enum bdi_stat_item item
)
130 __add_bdi_stat(bdi
, item
, 1);
133 static inline void inc_bdi_stat(struct backing_dev_info
*bdi
,
134 enum bdi_stat_item item
)
138 local_irq_save(flags
);
139 __inc_bdi_stat(bdi
, item
);
140 local_irq_restore(flags
);
143 static inline void __dec_bdi_stat(struct backing_dev_info
*bdi
,
144 enum bdi_stat_item item
)
146 __add_bdi_stat(bdi
, item
, -1);
149 static inline void dec_bdi_stat(struct backing_dev_info
*bdi
,
150 enum bdi_stat_item item
)
154 local_irq_save(flags
);
155 __dec_bdi_stat(bdi
, item
);
156 local_irq_restore(flags
);
159 static inline s64
bdi_stat(struct backing_dev_info
*bdi
,
160 enum bdi_stat_item item
)
162 return percpu_counter_read_positive(&bdi
->bdi_stat
[item
]);
165 static inline s64
__bdi_stat_sum(struct backing_dev_info
*bdi
,
166 enum bdi_stat_item item
)
168 return percpu_counter_sum_positive(&bdi
->bdi_stat
[item
]);
171 static inline s64
bdi_stat_sum(struct backing_dev_info
*bdi
,
172 enum bdi_stat_item item
)
177 local_irq_save(flags
);
178 sum
= __bdi_stat_sum(bdi
, item
);
179 local_irq_restore(flags
);
184 extern void bdi_writeout_inc(struct backing_dev_info
*bdi
);
187 * maximal error of a stat counter.
189 static inline unsigned long bdi_stat_error(struct backing_dev_info
*bdi
)
192 return nr_cpu_ids
* BDI_STAT_BATCH
;
198 int bdi_set_min_ratio(struct backing_dev_info
*bdi
, unsigned int min_ratio
);
199 int bdi_set_max_ratio(struct backing_dev_info
*bdi
, unsigned int max_ratio
);
202 * Flags in backing_dev_info::capability
204 * The first three flags control whether dirty pages will contribute to the
205 * VM's accounting and whether writepages() should be called for dirty pages
206 * (something that would not, for example, be appropriate for ramfs)
208 * WARNING: these flags are closely related and should not normally be
209 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
210 * three flags into a single convenience macro.
212 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
213 * BDI_CAP_NO_WRITEBACK: Don't write pages back
214 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
216 * These flags let !MMU mmap() govern direct device mapping vs immediate
217 * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
219 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE)
220 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED)
221 * BDI_CAP_READ_MAP: Can be mapped for reading
222 * BDI_CAP_WRITE_MAP: Can be mapped for writing
223 * BDI_CAP_EXEC_MAP: Can be mapped for execution
225 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed.
227 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
228 #define BDI_CAP_NO_WRITEBACK 0x00000002
229 #define BDI_CAP_MAP_COPY 0x00000004
230 #define BDI_CAP_MAP_DIRECT 0x00000008
231 #define BDI_CAP_READ_MAP 0x00000010
232 #define BDI_CAP_WRITE_MAP 0x00000020
233 #define BDI_CAP_EXEC_MAP 0x00000040
234 #define BDI_CAP_NO_ACCT_WB 0x00000080
235 #define BDI_CAP_SWAP_BACKED 0x00000100
237 #define BDI_CAP_VMFLAGS \
238 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
240 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
241 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
243 #if defined(VM_MAYREAD) && \
244 (BDI_CAP_READ_MAP != VM_MAYREAD || \
245 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
246 BDI_CAP_EXEC_MAP != VM_MAYEXEC)
247 #error please change backing_dev_info::capabilities flags
250 extern struct backing_dev_info default_backing_dev_info
;
251 extern struct backing_dev_info noop_backing_dev_info
;
252 void default_unplug_io_fn(struct backing_dev_info
*bdi
, struct page
*page
);
254 int writeback_in_progress(struct backing_dev_info
*bdi
);
256 static inline int bdi_congested(struct backing_dev_info
*bdi
, int bdi_bits
)
258 if (bdi
->congested_fn
)
259 return bdi
->congested_fn(bdi
->congested_data
, bdi_bits
);
260 return (bdi
->state
& bdi_bits
);
263 static inline int bdi_read_congested(struct backing_dev_info
*bdi
)
265 return bdi_congested(bdi
, 1 << BDI_sync_congested
);
268 static inline int bdi_write_congested(struct backing_dev_info
*bdi
)
270 return bdi_congested(bdi
, 1 << BDI_async_congested
);
273 static inline int bdi_rw_congested(struct backing_dev_info
*bdi
)
275 return bdi_congested(bdi
, (1 << BDI_sync_congested
) |
276 (1 << BDI_async_congested
));
284 void clear_bdi_congested(struct backing_dev_info
*bdi
, int sync
);
285 void set_bdi_congested(struct backing_dev_info
*bdi
, int sync
);
286 long congestion_wait(int sync
, long timeout
);
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 bdi_cap_swap_backed(struct backing_dev_info
*bdi
)
308 return bdi
->capabilities
& BDI_CAP_SWAP_BACKED
;
311 static inline bool bdi_cap_flush_forker(struct backing_dev_info
*bdi
)
313 return bdi
== &default_backing_dev_info
;
316 static inline bool mapping_cap_writeback_dirty(struct address_space
*mapping
)
318 return bdi_cap_writeback_dirty(mapping
->backing_dev_info
);
321 static inline bool mapping_cap_account_dirty(struct address_space
*mapping
)
323 return bdi_cap_account_dirty(mapping
->backing_dev_info
);
326 static inline bool mapping_cap_swap_backed(struct address_space
*mapping
)
328 return bdi_cap_swap_backed(mapping
->backing_dev_info
);
331 static inline int bdi_sched_wait(void *word
)
337 static inline void blk_run_backing_dev(struct backing_dev_info
*bdi
,
340 if (bdi
&& bdi
->unplug_io_fn
)
341 bdi
->unplug_io_fn(bdi
, page
);
344 static inline void blk_run_address_space(struct address_space
*mapping
)
347 blk_run_backing_dev(mapping
->backing_dev_info
, NULL
);
350 #endif /* _LINUX_BACKING_DEV_H */