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