1 /* 2 * include/linux/backing-dev.h 3 * 4 * low-level device information and state which is propagated up through 5 * to high-level code. 6 */ 7 8 #ifndef _LINUX_BACKING_DEV_H 9 #define _LINUX_BACKING_DEV_H 10 11 #include <linux/percpu_counter.h> 12 #include <linux/log2.h> 13 #include <linux/flex_proportions.h> 14 #include <linux/kernel.h> 15 #include <linux/fs.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 22 struct page; 23 struct device; 24 struct dentry; 25 26 /* 27 * Bits in backing_dev_info.state 28 */ 29 enum bdi_state { 30 BDI_pending, /* On its way to being activated */ 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 */ 37 }; 38 39 typedef int (congested_fn)(void *, int); 40 41 enum bdi_stat_item { 42 BDI_RECLAIMABLE, 43 BDI_WRITEBACK, 44 BDI_DIRTIED, 45 BDI_WRITTEN, 46 NR_BDI_STAT_ITEMS 47 }; 48 49 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids))) 50 51 struct bdi_writeback { 52 struct backing_dev_info *bdi; /* our parent bdi */ 53 unsigned int nr; 54 55 unsigned long last_old_flush; /* last old data flush */ 56 unsigned long last_active; /* last time bdi thread was active */ 57 58 struct task_struct *task; /* writeback thread */ 59 struct timer_list wakeup_timer; /* used for delayed bdi thread wakeup */ 60 struct list_head b_dirty; /* dirty inodes */ 61 struct list_head b_io; /* parked for writeback */ 62 struct list_head b_more_io; /* parked for more writeback */ 63 spinlock_t list_lock; /* protects the b_* lists */ 64 }; 65 66 struct backing_dev_info { 67 struct list_head bdi_list; 68 unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */ 69 unsigned long state; /* Always use atomic bitops on this */ 70 unsigned int capabilities; /* Device capabilities */ 71 congested_fn *congested_fn; /* Function pointer if device is md/dm */ 72 void *congested_data; /* Pointer to aux data for congested func */ 73 74 char *name; 75 76 struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS]; 77 78 unsigned long bw_time_stamp; /* last time write bw is updated */ 79 unsigned long dirtied_stamp; 80 unsigned long written_stamp; /* pages written at bw_time_stamp */ 81 unsigned long write_bandwidth; /* the estimated write bandwidth */ 82 unsigned long avg_write_bandwidth; /* further smoothed write bw */ 83 84 /* 85 * The base dirty throttle rate, re-calculated on every 200ms. 86 * All the bdi tasks' dirty rate will be curbed under it. 87 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit 88 * in small steps and is much more smooth/stable than the latter. 89 */ 90 unsigned long dirty_ratelimit; 91 unsigned long balanced_dirty_ratelimit; 92 93 struct fprop_local_percpu completions; 94 int dirty_exceeded; 95 96 unsigned int min_ratio; 97 unsigned int max_ratio, max_prop_frac; 98 99 struct bdi_writeback wb; /* default writeback info for this bdi */ 100 spinlock_t wb_lock; /* protects work_list */ 101 102 struct list_head work_list; 103 104 struct device *dev; 105 106 struct timer_list laptop_mode_wb_timer; 107 108 #ifdef CONFIG_DEBUG_FS 109 struct dentry *debug_dir; 110 struct dentry *debug_stats; 111 #endif 112 }; 113 114 int bdi_init(struct backing_dev_info *bdi); 115 void bdi_destroy(struct backing_dev_info *bdi); 116 117 __printf(3, 4) 118 int bdi_register(struct backing_dev_info *bdi, struct device *parent, 119 const char *fmt, ...); 120 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev); 121 void bdi_unregister(struct backing_dev_info *bdi); 122 int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int); 123 void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, 124 enum wb_reason reason); 125 void bdi_start_background_writeback(struct backing_dev_info *bdi); 126 int bdi_writeback_thread(void *data); 127 int bdi_has_dirty_io(struct backing_dev_info *bdi); 128 void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi); 129 void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2); 130 131 extern spinlock_t bdi_lock; 132 extern struct list_head bdi_list; 133 extern struct list_head bdi_pending_list; 134 135 static inline int wb_has_dirty_io(struct bdi_writeback *wb) 136 { 137 return !list_empty(&wb->b_dirty) || 138 !list_empty(&wb->b_io) || 139 !list_empty(&wb->b_more_io); 140 } 141 142 static inline void __add_bdi_stat(struct backing_dev_info *bdi, 143 enum bdi_stat_item item, s64 amount) 144 { 145 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH); 146 } 147 148 static inline void __inc_bdi_stat(struct backing_dev_info *bdi, 149 enum bdi_stat_item item) 150 { 151 __add_bdi_stat(bdi, item, 1); 152 } 153 154 static inline void inc_bdi_stat(struct backing_dev_info *bdi, 155 enum bdi_stat_item item) 156 { 157 unsigned long flags; 158 159 local_irq_save(flags); 160 __inc_bdi_stat(bdi, item); 161 local_irq_restore(flags); 162 } 163 164 static inline void __dec_bdi_stat(struct backing_dev_info *bdi, 165 enum bdi_stat_item item) 166 { 167 __add_bdi_stat(bdi, item, -1); 168 } 169 170 static inline void dec_bdi_stat(struct backing_dev_info *bdi, 171 enum bdi_stat_item item) 172 { 173 unsigned long flags; 174 175 local_irq_save(flags); 176 __dec_bdi_stat(bdi, item); 177 local_irq_restore(flags); 178 } 179 180 static inline s64 bdi_stat(struct backing_dev_info *bdi, 181 enum bdi_stat_item item) 182 { 183 return percpu_counter_read_positive(&bdi->bdi_stat[item]); 184 } 185 186 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi, 187 enum bdi_stat_item item) 188 { 189 return percpu_counter_sum_positive(&bdi->bdi_stat[item]); 190 } 191 192 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi, 193 enum bdi_stat_item item) 194 { 195 s64 sum; 196 unsigned long flags; 197 198 local_irq_save(flags); 199 sum = __bdi_stat_sum(bdi, item); 200 local_irq_restore(flags); 201 202 return sum; 203 } 204 205 extern void bdi_writeout_inc(struct backing_dev_info *bdi); 206 207 /* 208 * maximal error of a stat counter. 209 */ 210 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi) 211 { 212 #ifdef CONFIG_SMP 213 return nr_cpu_ids * BDI_STAT_BATCH; 214 #else 215 return 1; 216 #endif 217 } 218 219 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio); 220 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio); 221 222 /* 223 * Flags in backing_dev_info::capability 224 * 225 * The first three flags control whether dirty pages will contribute to the 226 * VM's accounting and whether writepages() should be called for dirty pages 227 * (something that would not, for example, be appropriate for ramfs) 228 * 229 * WARNING: these flags are closely related and should not normally be 230 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these 231 * three flags into a single convenience macro. 232 * 233 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting 234 * BDI_CAP_NO_WRITEBACK: Don't write pages back 235 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages 236 * 237 * These flags let !MMU mmap() govern direct device mapping vs immediate 238 * copying more easily for MAP_PRIVATE, especially for ROM filesystems. 239 * 240 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE) 241 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED) 242 * BDI_CAP_READ_MAP: Can be mapped for reading 243 * BDI_CAP_WRITE_MAP: Can be mapped for writing 244 * BDI_CAP_EXEC_MAP: Can be mapped for execution 245 * 246 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed. 247 */ 248 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001 249 #define BDI_CAP_NO_WRITEBACK 0x00000002 250 #define BDI_CAP_MAP_COPY 0x00000004 251 #define BDI_CAP_MAP_DIRECT 0x00000008 252 #define BDI_CAP_READ_MAP 0x00000010 253 #define BDI_CAP_WRITE_MAP 0x00000020 254 #define BDI_CAP_EXEC_MAP 0x00000040 255 #define BDI_CAP_NO_ACCT_WB 0x00000080 256 #define BDI_CAP_SWAP_BACKED 0x00000100 257 #define BDI_CAP_STABLE_WRITES 0x00000200 258 259 #define BDI_CAP_VMFLAGS \ 260 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP) 261 262 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \ 263 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB) 264 265 #if defined(VM_MAYREAD) && \ 266 (BDI_CAP_READ_MAP != VM_MAYREAD || \ 267 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \ 268 BDI_CAP_EXEC_MAP != VM_MAYEXEC) 269 #error please change backing_dev_info::capabilities flags 270 #endif 271 272 extern struct backing_dev_info default_backing_dev_info; 273 extern struct backing_dev_info noop_backing_dev_info; 274 275 int writeback_in_progress(struct backing_dev_info *bdi); 276 277 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits) 278 { 279 if (bdi->congested_fn) 280 return bdi->congested_fn(bdi->congested_data, bdi_bits); 281 return (bdi->state & bdi_bits); 282 } 283 284 static inline int bdi_read_congested(struct backing_dev_info *bdi) 285 { 286 return bdi_congested(bdi, 1 << BDI_sync_congested); 287 } 288 289 static inline int bdi_write_congested(struct backing_dev_info *bdi) 290 { 291 return bdi_congested(bdi, 1 << BDI_async_congested); 292 } 293 294 static inline int bdi_rw_congested(struct backing_dev_info *bdi) 295 { 296 return bdi_congested(bdi, (1 << BDI_sync_congested) | 297 (1 << BDI_async_congested)); 298 } 299 300 enum { 301 BLK_RW_ASYNC = 0, 302 BLK_RW_SYNC = 1, 303 }; 304 305 void clear_bdi_congested(struct backing_dev_info *bdi, int sync); 306 void set_bdi_congested(struct backing_dev_info *bdi, int sync); 307 long congestion_wait(int sync, long timeout); 308 long wait_iff_congested(struct zone *zone, int sync, long timeout); 309 int pdflush_proc_obsolete(struct ctl_table *table, int write, 310 void __user *buffer, size_t *lenp, loff_t *ppos); 311 312 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi) 313 { 314 return bdi->capabilities & BDI_CAP_STABLE_WRITES; 315 } 316 317 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi) 318 { 319 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK); 320 } 321 322 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi) 323 { 324 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY); 325 } 326 327 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi) 328 { 329 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */ 330 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB | 331 BDI_CAP_NO_WRITEBACK)); 332 } 333 334 static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi) 335 { 336 return bdi->capabilities & BDI_CAP_SWAP_BACKED; 337 } 338 339 static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi) 340 { 341 return bdi == &default_backing_dev_info; 342 } 343 344 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping) 345 { 346 return bdi_cap_writeback_dirty(mapping->backing_dev_info); 347 } 348 349 static inline bool mapping_cap_account_dirty(struct address_space *mapping) 350 { 351 return bdi_cap_account_dirty(mapping->backing_dev_info); 352 } 353 354 static inline bool mapping_cap_swap_backed(struct address_space *mapping) 355 { 356 return bdi_cap_swap_backed(mapping->backing_dev_info); 357 } 358 359 static inline int bdi_sched_wait(void *word) 360 { 361 schedule(); 362 return 0; 363 } 364 365 #endif /* _LINUX_BACKING_DEV_H */ 366