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/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 21 struct page; 22 struct device; 23 struct dentry; 24 25 /* 26 * Bits in backing_dev_info.state 27 */ 28 enum bdi_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 */ 36 }; 37 38 typedef int (congested_fn)(void *, int); 39 40 enum bdi_stat_item { 41 BDI_RECLAIMABLE, 42 BDI_WRITEBACK, 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 unsigned int nr; 52 53 unsigned long last_old_flush; /* last old data flush */ 54 unsigned long last_active; /* last time bdi thread was active */ 55 56 struct task_struct *task; /* writeback thread */ 57 struct timer_list wakeup_timer; /* used for delayed bdi thread wakeup */ 58 struct list_head b_dirty; /* dirty inodes */ 59 struct list_head b_io; /* parked for writeback */ 60 struct list_head b_more_io; /* parked for more writeback */ 61 spinlock_t list_lock; /* protects the b_* lists */ 62 }; 63 64 struct backing_dev_info { 65 struct list_head bdi_list; 66 unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */ 67 unsigned long state; /* Always use atomic bitops on this */ 68 unsigned int capabilities; /* Device capabilities */ 69 congested_fn *congested_fn; /* Function pointer if device is md/dm */ 70 void *congested_data; /* Pointer to aux data for congested func */ 71 72 char *name; 73 74 struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS]; 75 76 unsigned long bw_time_stamp; /* last time write bw is updated */ 77 unsigned long written_stamp; /* pages written at bw_time_stamp */ 78 unsigned long write_bandwidth; /* the estimated write bandwidth */ 79 unsigned long avg_write_bandwidth; /* further smoothed write bw */ 80 81 struct prop_local_percpu completions; 82 int dirty_exceeded; 83 84 unsigned int min_ratio; 85 unsigned int max_ratio, max_prop_frac; 86 87 struct bdi_writeback wb; /* default writeback info for this bdi */ 88 spinlock_t wb_lock; /* protects work_list */ 89 90 struct list_head work_list; 91 92 struct device *dev; 93 94 struct timer_list laptop_mode_wb_timer; 95 96 #ifdef CONFIG_DEBUG_FS 97 struct dentry *debug_dir; 98 struct dentry *debug_stats; 99 #endif 100 }; 101 102 int bdi_init(struct backing_dev_info *bdi); 103 void bdi_destroy(struct backing_dev_info *bdi); 104 105 int bdi_register(struct backing_dev_info *bdi, struct device *parent, 106 const char *fmt, ...); 107 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev); 108 void bdi_unregister(struct backing_dev_info *bdi); 109 int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int); 110 void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages); 111 void bdi_start_background_writeback(struct backing_dev_info *bdi); 112 int bdi_writeback_thread(void *data); 113 int bdi_has_dirty_io(struct backing_dev_info *bdi); 114 void bdi_arm_supers_timer(void); 115 void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi); 116 void bdi_lock_two(struct bdi_writeback *wb1, struct bdi_writeback *wb2); 117 118 extern spinlock_t bdi_lock; 119 extern struct list_head bdi_list; 120 extern struct list_head bdi_pending_list; 121 122 static inline int wb_has_dirty_io(struct bdi_writeback *wb) 123 { 124 return !list_empty(&wb->b_dirty) || 125 !list_empty(&wb->b_io) || 126 !list_empty(&wb->b_more_io); 127 } 128 129 static inline void __add_bdi_stat(struct backing_dev_info *bdi, 130 enum bdi_stat_item item, s64 amount) 131 { 132 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH); 133 } 134 135 static inline void __inc_bdi_stat(struct backing_dev_info *bdi, 136 enum bdi_stat_item item) 137 { 138 __add_bdi_stat(bdi, item, 1); 139 } 140 141 static inline void inc_bdi_stat(struct backing_dev_info *bdi, 142 enum bdi_stat_item item) 143 { 144 unsigned long flags; 145 146 local_irq_save(flags); 147 __inc_bdi_stat(bdi, item); 148 local_irq_restore(flags); 149 } 150 151 static inline void __dec_bdi_stat(struct backing_dev_info *bdi, 152 enum bdi_stat_item item) 153 { 154 __add_bdi_stat(bdi, item, -1); 155 } 156 157 static inline void dec_bdi_stat(struct backing_dev_info *bdi, 158 enum bdi_stat_item item) 159 { 160 unsigned long flags; 161 162 local_irq_save(flags); 163 __dec_bdi_stat(bdi, item); 164 local_irq_restore(flags); 165 } 166 167 static inline s64 bdi_stat(struct backing_dev_info *bdi, 168 enum bdi_stat_item item) 169 { 170 return percpu_counter_read_positive(&bdi->bdi_stat[item]); 171 } 172 173 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi, 174 enum bdi_stat_item item) 175 { 176 return percpu_counter_sum_positive(&bdi->bdi_stat[item]); 177 } 178 179 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi, 180 enum bdi_stat_item item) 181 { 182 s64 sum; 183 unsigned long flags; 184 185 local_irq_save(flags); 186 sum = __bdi_stat_sum(bdi, item); 187 local_irq_restore(flags); 188 189 return sum; 190 } 191 192 extern void bdi_writeout_inc(struct backing_dev_info *bdi); 193 194 /* 195 * maximal error of a stat counter. 196 */ 197 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi) 198 { 199 #ifdef CONFIG_SMP 200 return nr_cpu_ids * BDI_STAT_BATCH; 201 #else 202 return 1; 203 #endif 204 } 205 206 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio); 207 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio); 208 209 /* 210 * Flags in backing_dev_info::capability 211 * 212 * The first three flags control whether dirty pages will contribute to the 213 * VM's accounting and whether writepages() should be called for dirty pages 214 * (something that would not, for example, be appropriate for ramfs) 215 * 216 * WARNING: these flags are closely related and should not normally be 217 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these 218 * three flags into a single convenience macro. 219 * 220 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting 221 * BDI_CAP_NO_WRITEBACK: Don't write pages back 222 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages 223 * 224 * These flags let !MMU mmap() govern direct device mapping vs immediate 225 * copying more easily for MAP_PRIVATE, especially for ROM filesystems. 226 * 227 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE) 228 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED) 229 * BDI_CAP_READ_MAP: Can be mapped for reading 230 * BDI_CAP_WRITE_MAP: Can be mapped for writing 231 * BDI_CAP_EXEC_MAP: Can be mapped for execution 232 * 233 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed. 234 */ 235 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001 236 #define BDI_CAP_NO_WRITEBACK 0x00000002 237 #define BDI_CAP_MAP_COPY 0x00000004 238 #define BDI_CAP_MAP_DIRECT 0x00000008 239 #define BDI_CAP_READ_MAP 0x00000010 240 #define BDI_CAP_WRITE_MAP 0x00000020 241 #define BDI_CAP_EXEC_MAP 0x00000040 242 #define BDI_CAP_NO_ACCT_WB 0x00000080 243 #define BDI_CAP_SWAP_BACKED 0x00000100 244 245 #define BDI_CAP_VMFLAGS \ 246 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP) 247 248 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \ 249 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB) 250 251 #if defined(VM_MAYREAD) && \ 252 (BDI_CAP_READ_MAP != VM_MAYREAD || \ 253 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \ 254 BDI_CAP_EXEC_MAP != VM_MAYEXEC) 255 #error please change backing_dev_info::capabilities flags 256 #endif 257 258 extern struct backing_dev_info default_backing_dev_info; 259 extern struct backing_dev_info noop_backing_dev_info; 260 261 int writeback_in_progress(struct backing_dev_info *bdi); 262 263 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits) 264 { 265 if (bdi->congested_fn) 266 return bdi->congested_fn(bdi->congested_data, bdi_bits); 267 return (bdi->state & bdi_bits); 268 } 269 270 static inline int bdi_read_congested(struct backing_dev_info *bdi) 271 { 272 return bdi_congested(bdi, 1 << BDI_sync_congested); 273 } 274 275 static inline int bdi_write_congested(struct backing_dev_info *bdi) 276 { 277 return bdi_congested(bdi, 1 << BDI_async_congested); 278 } 279 280 static inline int bdi_rw_congested(struct backing_dev_info *bdi) 281 { 282 return bdi_congested(bdi, (1 << BDI_sync_congested) | 283 (1 << BDI_async_congested)); 284 } 285 286 enum { 287 BLK_RW_ASYNC = 0, 288 BLK_RW_SYNC = 1, 289 }; 290 291 void clear_bdi_congested(struct backing_dev_info *bdi, int sync); 292 void set_bdi_congested(struct backing_dev_info *bdi, int sync); 293 long congestion_wait(int sync, long timeout); 294 long wait_iff_congested(struct zone *zone, int sync, long timeout); 295 296 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi) 297 { 298 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK); 299 } 300 301 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi) 302 { 303 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY); 304 } 305 306 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi) 307 { 308 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */ 309 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB | 310 BDI_CAP_NO_WRITEBACK)); 311 } 312 313 static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi) 314 { 315 return bdi->capabilities & BDI_CAP_SWAP_BACKED; 316 } 317 318 static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi) 319 { 320 return bdi == &default_backing_dev_info; 321 } 322 323 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping) 324 { 325 return bdi_cap_writeback_dirty(mapping->backing_dev_info); 326 } 327 328 static inline bool mapping_cap_account_dirty(struct address_space *mapping) 329 { 330 return bdi_cap_account_dirty(mapping->backing_dev_info); 331 } 332 333 static inline bool mapping_cap_swap_backed(struct address_space *mapping) 334 { 335 return bdi_cap_swap_backed(mapping->backing_dev_info); 336 } 337 338 static inline int bdi_sched_wait(void *word) 339 { 340 schedule(); 341 return 0; 342 } 343 344 #endif /* _LINUX_BACKING_DEV_H */ 345