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 #include <linux/workqueue.h> 22 23 struct page; 24 struct device; 25 struct dentry; 26 27 /* 28 * Bits in backing_dev_info.state 29 */ 30 enum bdi_state { 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 }; 36 37 typedef int (congested_fn)(void *, int); 38 39 enum bdi_stat_item { 40 BDI_RECLAIMABLE, 41 BDI_WRITEBACK, 42 BDI_DIRTIED, 43 BDI_WRITTEN, 44 NR_BDI_STAT_ITEMS 45 }; 46 47 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids))) 48 49 struct bdi_writeback { 50 struct backing_dev_info *bdi; /* our parent bdi */ 51 52 unsigned long last_old_flush; /* last old data flush */ 53 54 struct delayed_work dwork; /* work item used for writeback */ 55 struct list_head b_dirty; /* dirty inodes */ 56 struct list_head b_io; /* parked for writeback */ 57 struct list_head b_more_io; /* parked for more writeback */ 58 spinlock_t list_lock; /* protects the b_* lists */ 59 }; 60 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 69 char *name; 70 71 struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS]; 72 73 unsigned long bw_time_stamp; /* last time write bw is updated */ 74 unsigned long dirtied_stamp; 75 unsigned long written_stamp; /* pages written at bw_time_stamp */ 76 unsigned long write_bandwidth; /* the estimated write bandwidth */ 77 unsigned long avg_write_bandwidth; /* further smoothed write bw */ 78 79 /* 80 * The base dirty throttle rate, re-calculated on every 200ms. 81 * All the bdi tasks' dirty rate will be curbed under it. 82 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit 83 * in small steps and is much more smooth/stable than the latter. 84 */ 85 unsigned long dirty_ratelimit; 86 unsigned long balanced_dirty_ratelimit; 87 88 struct fprop_local_percpu completions; 89 int dirty_exceeded; 90 91 unsigned int min_ratio; 92 unsigned int max_ratio, max_prop_frac; 93 94 struct bdi_writeback wb; /* default writeback info for this bdi */ 95 spinlock_t wb_lock; /* protects work_list & wb.dwork scheduling */ 96 97 struct list_head work_list; 98 99 struct device *dev; 100 101 struct timer_list laptop_mode_wb_timer; 102 103 #ifdef CONFIG_DEBUG_FS 104 struct dentry *debug_dir; 105 struct dentry *debug_stats; 106 #endif 107 }; 108 109 int __must_check bdi_init(struct backing_dev_info *bdi); 110 void bdi_destroy(struct backing_dev_info *bdi); 111 112 __printf(3, 4) 113 int bdi_register(struct backing_dev_info *bdi, struct device *parent, 114 const char *fmt, ...); 115 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev); 116 void bdi_unregister(struct backing_dev_info *bdi); 117 int __must_check bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int); 118 void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, 119 enum wb_reason reason); 120 void bdi_start_background_writeback(struct backing_dev_info *bdi); 121 void bdi_writeback_workfn(struct work_struct *work); 122 int bdi_has_dirty_io(struct backing_dev_info *bdi); 123 void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi); 124 125 extern spinlock_t bdi_lock; 126 extern struct list_head bdi_list; 127 128 extern struct workqueue_struct *bdi_wq; 129 130 static inline int wb_has_dirty_io(struct bdi_writeback *wb) 131 { 132 return !list_empty(&wb->b_dirty) || 133 !list_empty(&wb->b_io) || 134 !list_empty(&wb->b_more_io); 135 } 136 137 static inline void __add_bdi_stat(struct backing_dev_info *bdi, 138 enum bdi_stat_item item, s64 amount) 139 { 140 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH); 141 } 142 143 static inline void __inc_bdi_stat(struct backing_dev_info *bdi, 144 enum bdi_stat_item item) 145 { 146 __add_bdi_stat(bdi, item, 1); 147 } 148 149 static inline void inc_bdi_stat(struct backing_dev_info *bdi, 150 enum bdi_stat_item item) 151 { 152 unsigned long flags; 153 154 local_irq_save(flags); 155 __inc_bdi_stat(bdi, item); 156 local_irq_restore(flags); 157 } 158 159 static inline void __dec_bdi_stat(struct backing_dev_info *bdi, 160 enum bdi_stat_item item) 161 { 162 __add_bdi_stat(bdi, item, -1); 163 } 164 165 static inline void dec_bdi_stat(struct backing_dev_info *bdi, 166 enum bdi_stat_item item) 167 { 168 unsigned long flags; 169 170 local_irq_save(flags); 171 __dec_bdi_stat(bdi, item); 172 local_irq_restore(flags); 173 } 174 175 static inline s64 bdi_stat(struct backing_dev_info *bdi, 176 enum bdi_stat_item item) 177 { 178 return percpu_counter_read_positive(&bdi->bdi_stat[item]); 179 } 180 181 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi, 182 enum bdi_stat_item item) 183 { 184 return percpu_counter_sum_positive(&bdi->bdi_stat[item]); 185 } 186 187 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi, 188 enum bdi_stat_item item) 189 { 190 s64 sum; 191 unsigned long flags; 192 193 local_irq_save(flags); 194 sum = __bdi_stat_sum(bdi, item); 195 local_irq_restore(flags); 196 197 return sum; 198 } 199 200 extern void bdi_writeout_inc(struct backing_dev_info *bdi); 201 202 /* 203 * maximal error of a stat counter. 204 */ 205 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi) 206 { 207 #ifdef CONFIG_SMP 208 return nr_cpu_ids * BDI_STAT_BATCH; 209 #else 210 return 1; 211 #endif 212 } 213 214 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio); 215 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio); 216 217 /* 218 * Flags in backing_dev_info::capability 219 * 220 * The first three flags control whether dirty pages will contribute to the 221 * VM's accounting and whether writepages() should be called for dirty pages 222 * (something that would not, for example, be appropriate for ramfs) 223 * 224 * WARNING: these flags are closely related and should not normally be 225 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these 226 * three flags into a single convenience macro. 227 * 228 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting 229 * BDI_CAP_NO_WRITEBACK: Don't write pages back 230 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages 231 * 232 * These flags let !MMU mmap() govern direct device mapping vs immediate 233 * copying more easily for MAP_PRIVATE, especially for ROM filesystems. 234 * 235 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE) 236 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED) 237 * BDI_CAP_READ_MAP: Can be mapped for reading 238 * BDI_CAP_WRITE_MAP: Can be mapped for writing 239 * BDI_CAP_EXEC_MAP: Can be mapped for execution 240 * 241 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed. 242 * 243 * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold. 244 */ 245 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001 246 #define BDI_CAP_NO_WRITEBACK 0x00000002 247 #define BDI_CAP_MAP_COPY 0x00000004 248 #define BDI_CAP_MAP_DIRECT 0x00000008 249 #define BDI_CAP_READ_MAP 0x00000010 250 #define BDI_CAP_WRITE_MAP 0x00000020 251 #define BDI_CAP_EXEC_MAP 0x00000040 252 #define BDI_CAP_NO_ACCT_WB 0x00000080 253 #define BDI_CAP_SWAP_BACKED 0x00000100 254 #define BDI_CAP_STABLE_WRITES 0x00000200 255 #define BDI_CAP_STRICTLIMIT 0x00000400 256 257 #define BDI_CAP_VMFLAGS \ 258 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP) 259 260 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \ 261 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB) 262 263 #if defined(VM_MAYREAD) && \ 264 (BDI_CAP_READ_MAP != VM_MAYREAD || \ 265 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \ 266 BDI_CAP_EXEC_MAP != VM_MAYEXEC) 267 #error please change backing_dev_info::capabilities flags 268 #endif 269 270 extern struct backing_dev_info default_backing_dev_info; 271 extern struct backing_dev_info noop_backing_dev_info; 272 273 int writeback_in_progress(struct backing_dev_info *bdi); 274 275 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits) 276 { 277 if (bdi->congested_fn) 278 return bdi->congested_fn(bdi->congested_data, bdi_bits); 279 return (bdi->state & bdi_bits); 280 } 281 282 static inline int bdi_read_congested(struct backing_dev_info *bdi) 283 { 284 return bdi_congested(bdi, 1 << BDI_sync_congested); 285 } 286 287 static inline int bdi_write_congested(struct backing_dev_info *bdi) 288 { 289 return bdi_congested(bdi, 1 << BDI_async_congested); 290 } 291 292 static inline int bdi_rw_congested(struct backing_dev_info *bdi) 293 { 294 return bdi_congested(bdi, (1 << BDI_sync_congested) | 295 (1 << BDI_async_congested)); 296 } 297 298 enum { 299 BLK_RW_ASYNC = 0, 300 BLK_RW_SYNC = 1, 301 }; 302 303 void clear_bdi_congested(struct backing_dev_info *bdi, int sync); 304 void set_bdi_congested(struct backing_dev_info *bdi, int sync); 305 long congestion_wait(int sync, long timeout); 306 long wait_iff_congested(struct zone *zone, int sync, long timeout); 307 int pdflush_proc_obsolete(struct ctl_table *table, int write, 308 void __user *buffer, size_t *lenp, loff_t *ppos); 309 310 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi) 311 { 312 return bdi->capabilities & BDI_CAP_STABLE_WRITES; 313 } 314 315 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi) 316 { 317 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK); 318 } 319 320 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi) 321 { 322 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY); 323 } 324 325 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi) 326 { 327 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */ 328 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB | 329 BDI_CAP_NO_WRITEBACK)); 330 } 331 332 static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi) 333 { 334 return bdi->capabilities & BDI_CAP_SWAP_BACKED; 335 } 336 337 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping) 338 { 339 return bdi_cap_writeback_dirty(mapping->backing_dev_info); 340 } 341 342 static inline bool mapping_cap_account_dirty(struct address_space *mapping) 343 { 344 return bdi_cap_account_dirty(mapping->backing_dev_info); 345 } 346 347 static inline bool mapping_cap_swap_backed(struct address_space *mapping) 348 { 349 return bdi_cap_swap_backed(mapping->backing_dev_info); 350 } 351 352 static inline int bdi_sched_wait(void *word) 353 { 354 schedule(); 355 return 0; 356 } 357 358 #endif /* _LINUX_BACKING_DEV_H */ 359