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 */
53 struct task_struct *task; /* writeback thread */
54 struct list_head b_dirty; /* dirty inodes */
55 struct list_head b_io; /* parked for writeback */
56 struct list_head b_more_io; /* parked for more writeback */
59 struct backing_dev_info {
60 struct list_head bdi_list;
61 unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
62 unsigned long state; /* Always use atomic bitops on this */
63 unsigned int capabilities; /* Device capabilities */
64 congested_fn *congested_fn; /* Function pointer if device is md/dm */
65 void *congested_data; /* Pointer to aux data for congested func */
66 void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
71 struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
73 struct prop_local_percpu completions;
76 unsigned int min_ratio;
77 unsigned int max_ratio, max_prop_frac;
79 struct bdi_writeback wb; /* default writeback info for this bdi */
80 spinlock_t wb_lock; /* protects work_list */
82 struct list_head work_list;
86 struct timer_list laptop_mode_wb_timer;
88 #ifdef CONFIG_DEBUG_FS
89 struct dentry *debug_dir;
90 struct dentry *debug_stats;
94 int bdi_init(struct backing_dev_info *bdi);
95 void bdi_destroy(struct backing_dev_info *bdi);
97 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
98 const char *fmt, ...);
99 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
100 void bdi_unregister(struct backing_dev_info *bdi);
101 int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int);
102 void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages);
103 void bdi_start_background_writeback(struct backing_dev_info *bdi);
104 int bdi_writeback_thread(void *data);
105 int bdi_has_dirty_io(struct backing_dev_info *bdi);
106 void bdi_arm_supers_timer(void);
108 extern spinlock_t bdi_lock;
109 extern struct list_head bdi_list;
111 static inline int wb_has_dirty_io(struct bdi_writeback *wb)
113 return !list_empty(&wb->b_dirty) ||
114 !list_empty(&wb->b_io) ||
115 !list_empty(&wb->b_more_io);
118 static inline void __add_bdi_stat(struct backing_dev_info *bdi,
119 enum bdi_stat_item item, s64 amount)
121 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
124 static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
125 enum bdi_stat_item item)
127 __add_bdi_stat(bdi, item, 1);
130 static inline void inc_bdi_stat(struct backing_dev_info *bdi,
131 enum bdi_stat_item item)
135 local_irq_save(flags);
136 __inc_bdi_stat(bdi, item);
137 local_irq_restore(flags);
140 static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
141 enum bdi_stat_item item)
143 __add_bdi_stat(bdi, item, -1);
146 static inline void dec_bdi_stat(struct backing_dev_info *bdi,
147 enum bdi_stat_item item)
151 local_irq_save(flags);
152 __dec_bdi_stat(bdi, item);
153 local_irq_restore(flags);
156 static inline s64 bdi_stat(struct backing_dev_info *bdi,
157 enum bdi_stat_item item)
159 return percpu_counter_read_positive(&bdi->bdi_stat[item]);
162 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
163 enum bdi_stat_item item)
165 return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
168 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
169 enum bdi_stat_item item)
174 local_irq_save(flags);
175 sum = __bdi_stat_sum(bdi, item);
176 local_irq_restore(flags);
181 extern void bdi_writeout_inc(struct backing_dev_info *bdi);
184 * maximal error of a stat counter.
186 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
189 return nr_cpu_ids * BDI_STAT_BATCH;
195 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
196 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
199 * Flags in backing_dev_info::capability
201 * The first three flags control whether dirty pages will contribute to the
202 * VM's accounting and whether writepages() should be called for dirty pages
203 * (something that would not, for example, be appropriate for ramfs)
205 * WARNING: these flags are closely related and should not normally be
206 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
207 * three flags into a single convenience macro.
209 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
210 * BDI_CAP_NO_WRITEBACK: Don't write pages back
211 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
213 * These flags let !MMU mmap() govern direct device mapping vs immediate
214 * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
216 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE)
217 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED)
218 * BDI_CAP_READ_MAP: Can be mapped for reading
219 * BDI_CAP_WRITE_MAP: Can be mapped for writing
220 * BDI_CAP_EXEC_MAP: Can be mapped for execution
222 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed.
224 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
225 #define BDI_CAP_NO_WRITEBACK 0x00000002
226 #define BDI_CAP_MAP_COPY 0x00000004
227 #define BDI_CAP_MAP_DIRECT 0x00000008
228 #define BDI_CAP_READ_MAP 0x00000010
229 #define BDI_CAP_WRITE_MAP 0x00000020
230 #define BDI_CAP_EXEC_MAP 0x00000040
231 #define BDI_CAP_NO_ACCT_WB 0x00000080
232 #define BDI_CAP_SWAP_BACKED 0x00000100
234 #define BDI_CAP_VMFLAGS \
235 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
237 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
238 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
240 #if defined(VM_MAYREAD) && \
241 (BDI_CAP_READ_MAP != VM_MAYREAD || \
242 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
243 BDI_CAP_EXEC_MAP != VM_MAYEXEC)
244 #error please change backing_dev_info::capabilities flags
247 extern struct backing_dev_info default_backing_dev_info;
248 extern struct backing_dev_info noop_backing_dev_info;
249 void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);
251 int writeback_in_progress(struct backing_dev_info *bdi);
253 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
255 if (bdi->congested_fn)
256 return bdi->congested_fn(bdi->congested_data, bdi_bits);
257 return (bdi->state & bdi_bits);
260 static inline int bdi_read_congested(struct backing_dev_info *bdi)
262 return bdi_congested(bdi, 1 << BDI_sync_congested);
265 static inline int bdi_write_congested(struct backing_dev_info *bdi)
267 return bdi_congested(bdi, 1 << BDI_async_congested);
270 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
272 return bdi_congested(bdi, (1 << BDI_sync_congested) |
273 (1 << BDI_async_congested));
281 void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
282 void set_bdi_congested(struct backing_dev_info *bdi, int sync);
283 long congestion_wait(int sync, long timeout);
286 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
288 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
291 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
293 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
296 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
298 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
299 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
300 BDI_CAP_NO_WRITEBACK));
303 static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
305 return bdi->capabilities & BDI_CAP_SWAP_BACKED;
308 static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi)
310 return bdi == &default_backing_dev_info;
313 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
315 return bdi_cap_writeback_dirty(mapping->backing_dev_info);
318 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
320 return bdi_cap_account_dirty(mapping->backing_dev_info);
323 static inline bool mapping_cap_swap_backed(struct address_space *mapping)
325 return bdi_cap_swap_backed(mapping->backing_dev_info);
328 static inline int bdi_sched_wait(void *word)
334 static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
337 if (bdi && bdi->unplug_io_fn)
338 bdi->unplug_io_fn(bdi, page);
341 static inline void blk_run_address_space(struct address_space *mapping)
344 blk_run_backing_dev(mapping->backing_dev_info, NULL);
347 #endif /* _LINUX_BACKING_DEV_H */