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 <linux/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_writeback_running, /* Writeback is in progress */
35 BDI_unused, /* Available bits start here */
38 typedef int (congested_fn)(void *, int);
48 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
50 struct bdi_writeback {
51 struct backing_dev_info *bdi; /* our parent bdi */
54 unsigned long last_old_flush; /* last old data flush */
55 unsigned long last_active; /* last time bdi thread was active */
57 struct task_struct *task; /* writeback thread */
58 struct timer_list wakeup_timer; /* used for delayed bdi thread wakeup */
59 struct list_head b_dirty; /* dirty inodes */
60 struct list_head b_io; /* parked for writeback */
61 struct list_head b_more_io; /* parked for more writeback */
62 spinlock_t list_lock; /* protects the b_* lists */
65 struct backing_dev_info {
66 struct list_head bdi_list;
67 unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
68 unsigned long state; /* Always use atomic bitops on this */
69 unsigned int capabilities; /* Device capabilities */
70 congested_fn *congested_fn; /* Function pointer if device is md/dm */
71 void *congested_data; /* Pointer to aux data for congested func */
75 struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
77 unsigned long bw_time_stamp; /* last time write bw is updated */
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 */
82 struct prop_local_percpu completions;
85 unsigned int min_ratio;
86 unsigned int max_ratio, max_prop_frac;
88 struct bdi_writeback wb; /* default writeback info for this bdi */
89 spinlock_t wb_lock; /* protects work_list */
91 struct list_head work_list;
95 struct timer_list laptop_mode_wb_timer;
97 #ifdef CONFIG_DEBUG_FS
98 struct dentry *debug_dir;
99 struct dentry *debug_stats;
103 int bdi_init(struct backing_dev_info *bdi);
104 void bdi_destroy(struct backing_dev_info *bdi);
106 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
107 const char *fmt, ...);
108 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
109 void bdi_unregister(struct backing_dev_info *bdi);
110 int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int);
111 void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages);
112 void bdi_start_background_writeback(struct backing_dev_info *bdi);
113 int bdi_writeback_thread(void *data);
114 int bdi_has_dirty_io(struct backing_dev_info *bdi);
115 void bdi_arm_supers_timer(void);
116 void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi);
117 void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2);
119 extern spinlock_t bdi_lock;
120 extern struct list_head bdi_list;
121 extern struct list_head bdi_pending_list;
123 static inline int wb_has_dirty_io(struct bdi_writeback *wb)
125 return !list_empty(&wb->b_dirty) ||
126 !list_empty(&wb->b_io) ||
127 !list_empty(&wb->b_more_io);
130 static inline void __add_bdi_stat(struct backing_dev_info *bdi,
131 enum bdi_stat_item item, s64 amount)
133 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
136 static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
137 enum bdi_stat_item item)
139 __add_bdi_stat(bdi, item, 1);
142 static inline void inc_bdi_stat(struct backing_dev_info *bdi,
143 enum bdi_stat_item item)
147 local_irq_save(flags);
148 __inc_bdi_stat(bdi, item);
149 local_irq_restore(flags);
152 static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
153 enum bdi_stat_item item)
155 __add_bdi_stat(bdi, item, -1);
158 static inline void dec_bdi_stat(struct backing_dev_info *bdi,
159 enum bdi_stat_item item)
163 local_irq_save(flags);
164 __dec_bdi_stat(bdi, item);
165 local_irq_restore(flags);
168 static inline s64 bdi_stat(struct backing_dev_info *bdi,
169 enum bdi_stat_item item)
171 return percpu_counter_read_positive(&bdi->bdi_stat[item]);
174 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
175 enum bdi_stat_item item)
177 return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
180 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
181 enum bdi_stat_item item)
186 local_irq_save(flags);
187 sum = __bdi_stat_sum(bdi, item);
188 local_irq_restore(flags);
193 extern void bdi_writeout_inc(struct backing_dev_info *bdi);
196 * maximal error of a stat counter.
198 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
201 return nr_cpu_ids * BDI_STAT_BATCH;
207 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
208 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
211 * Flags in backing_dev_info::capability
213 * The first three flags control whether dirty pages will contribute to the
214 * VM's accounting and whether writepages() should be called for dirty pages
215 * (something that would not, for example, be appropriate for ramfs)
217 * WARNING: these flags are closely related and should not normally be
218 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
219 * three flags into a single convenience macro.
221 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
222 * BDI_CAP_NO_WRITEBACK: Don't write pages back
223 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
225 * These flags let !MMU mmap() govern direct device mapping vs immediate
226 * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
228 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE)
229 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED)
230 * BDI_CAP_READ_MAP: Can be mapped for reading
231 * BDI_CAP_WRITE_MAP: Can be mapped for writing
232 * BDI_CAP_EXEC_MAP: Can be mapped for execution
234 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed.
236 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
237 #define BDI_CAP_NO_WRITEBACK 0x00000002
238 #define BDI_CAP_MAP_COPY 0x00000004
239 #define BDI_CAP_MAP_DIRECT 0x00000008
240 #define BDI_CAP_READ_MAP 0x00000010
241 #define BDI_CAP_WRITE_MAP 0x00000020
242 #define BDI_CAP_EXEC_MAP 0x00000040
243 #define BDI_CAP_NO_ACCT_WB 0x00000080
244 #define BDI_CAP_SWAP_BACKED 0x00000100
246 #define BDI_CAP_VMFLAGS \
247 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
249 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
250 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
252 #if defined(VM_MAYREAD) && \
253 (BDI_CAP_READ_MAP != VM_MAYREAD || \
254 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
255 BDI_CAP_EXEC_MAP != VM_MAYEXEC)
256 #error please change backing_dev_info::capabilities flags
259 extern struct backing_dev_info default_backing_dev_info;
260 extern struct backing_dev_info noop_backing_dev_info;
262 int writeback_in_progress(struct backing_dev_info *bdi);
264 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
266 if (bdi->congested_fn)
267 return bdi->congested_fn(bdi->congested_data, bdi_bits);
268 return (bdi->state & bdi_bits);
271 static inline int bdi_read_congested(struct backing_dev_info *bdi)
273 return bdi_congested(bdi, 1 << BDI_sync_congested);
276 static inline int bdi_write_congested(struct backing_dev_info *bdi)
278 return bdi_congested(bdi, 1 << BDI_async_congested);
281 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
283 return bdi_congested(bdi, (1 << BDI_sync_congested) |
284 (1 << BDI_async_congested));
292 void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
293 void set_bdi_congested(struct backing_dev_info *bdi, int sync);
294 long congestion_wait(int sync, long timeout);
295 long wait_iff_congested(struct zone *zone, int sync, long timeout);
297 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
299 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
302 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
304 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
307 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
309 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
310 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
311 BDI_CAP_NO_WRITEBACK));
314 static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
316 return bdi->capabilities & BDI_CAP_SWAP_BACKED;
319 static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi)
321 return bdi == &default_backing_dev_info;
324 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
326 return bdi_cap_writeback_dirty(mapping->backing_dev_info);
329 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
331 return bdi_cap_account_dirty(mapping->backing_dev_info);
334 static inline bool mapping_cap_swap_backed(struct address_space *mapping)
336 return bdi_cap_swap_backed(mapping->backing_dev_info);
339 static inline int bdi_sched_wait(void *word)
345 #endif /* _LINUX_BACKING_DEV_H */