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_unused, /* Available bits start here */ 35 }; 36 37 typedef int (congested_fn)(void *, int); 38 39 enum bdi_stat_item { 40 BDI_RECLAIMABLE, 41 BDI_WRITEBACK, 42 NR_BDI_STAT_ITEMS 43 }; 44 45 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids))) 46 47 struct bdi_writeback { 48 struct backing_dev_info *bdi; /* our parent bdi */ 49 unsigned int nr; 50 51 unsigned long last_old_flush; /* last old data flush */ 52 unsigned long last_active; /* last time bdi thread was active */ 53 54 struct task_struct *task; /* writeback thread */ 55 struct timer_list wakeup_timer; /* used for delayed bdi thread wakeup */ 56 struct list_head b_dirty; /* dirty inodes */ 57 struct list_head b_io; /* parked for writeback */ 58 struct list_head b_more_io; /* parked for more writeback */ 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 void (*unplug_io_fn)(struct backing_dev_info *, struct page *); 69 void *unplug_io_data; 70 71 char *name; 72 73 struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS]; 74 75 struct prop_local_percpu completions; 76 int dirty_exceeded; 77 78 unsigned int min_ratio; 79 unsigned int max_ratio, max_prop_frac; 80 81 struct bdi_writeback wb; /* default writeback info for this bdi */ 82 spinlock_t wb_lock; /* protects work_list */ 83 84 struct list_head work_list; 85 86 struct device *dev; 87 88 struct timer_list laptop_mode_wb_timer; 89 90 #ifdef CONFIG_DEBUG_FS 91 struct dentry *debug_dir; 92 struct dentry *debug_stats; 93 #endif 94 }; 95 96 int bdi_init(struct backing_dev_info *bdi); 97 void bdi_destroy(struct backing_dev_info *bdi); 98 99 int bdi_register(struct backing_dev_info *bdi, struct device *parent, 100 const char *fmt, ...); 101 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev); 102 void bdi_unregister(struct backing_dev_info *bdi); 103 int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int); 104 void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages); 105 void bdi_start_background_writeback(struct backing_dev_info *bdi); 106 int bdi_writeback_thread(void *data); 107 int bdi_has_dirty_io(struct backing_dev_info *bdi); 108 void bdi_arm_supers_timer(void); 109 void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi); 110 111 extern spinlock_t bdi_lock; 112 extern struct list_head bdi_list; 113 114 static inline int wb_has_dirty_io(struct bdi_writeback *wb) 115 { 116 return !list_empty(&wb->b_dirty) || 117 !list_empty(&wb->b_io) || 118 !list_empty(&wb->b_more_io); 119 } 120 121 static inline void __add_bdi_stat(struct backing_dev_info *bdi, 122 enum bdi_stat_item item, s64 amount) 123 { 124 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH); 125 } 126 127 static inline void __inc_bdi_stat(struct backing_dev_info *bdi, 128 enum bdi_stat_item item) 129 { 130 __add_bdi_stat(bdi, item, 1); 131 } 132 133 static inline void inc_bdi_stat(struct backing_dev_info *bdi, 134 enum bdi_stat_item item) 135 { 136 unsigned long flags; 137 138 local_irq_save(flags); 139 __inc_bdi_stat(bdi, item); 140 local_irq_restore(flags); 141 } 142 143 static inline void __dec_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 dec_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 __dec_bdi_stat(bdi, item); 156 local_irq_restore(flags); 157 } 158 159 static inline s64 bdi_stat(struct backing_dev_info *bdi, 160 enum bdi_stat_item item) 161 { 162 return percpu_counter_read_positive(&bdi->bdi_stat[item]); 163 } 164 165 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi, 166 enum bdi_stat_item item) 167 { 168 return percpu_counter_sum_positive(&bdi->bdi_stat[item]); 169 } 170 171 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi, 172 enum bdi_stat_item item) 173 { 174 s64 sum; 175 unsigned long flags; 176 177 local_irq_save(flags); 178 sum = __bdi_stat_sum(bdi, item); 179 local_irq_restore(flags); 180 181 return sum; 182 } 183 184 extern void bdi_writeout_inc(struct backing_dev_info *bdi); 185 186 /* 187 * maximal error of a stat counter. 188 */ 189 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi) 190 { 191 #ifdef CONFIG_SMP 192 return nr_cpu_ids * BDI_STAT_BATCH; 193 #else 194 return 1; 195 #endif 196 } 197 198 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio); 199 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio); 200 201 /* 202 * Flags in backing_dev_info::capability 203 * 204 * The first three flags control whether dirty pages will contribute to the 205 * VM's accounting and whether writepages() should be called for dirty pages 206 * (something that would not, for example, be appropriate for ramfs) 207 * 208 * WARNING: these flags are closely related and should not normally be 209 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these 210 * three flags into a single convenience macro. 211 * 212 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting 213 * BDI_CAP_NO_WRITEBACK: Don't write pages back 214 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages 215 * 216 * These flags let !MMU mmap() govern direct device mapping vs immediate 217 * copying more easily for MAP_PRIVATE, especially for ROM filesystems. 218 * 219 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE) 220 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED) 221 * BDI_CAP_READ_MAP: Can be mapped for reading 222 * BDI_CAP_WRITE_MAP: Can be mapped for writing 223 * BDI_CAP_EXEC_MAP: Can be mapped for execution 224 * 225 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed. 226 */ 227 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001 228 #define BDI_CAP_NO_WRITEBACK 0x00000002 229 #define BDI_CAP_MAP_COPY 0x00000004 230 #define BDI_CAP_MAP_DIRECT 0x00000008 231 #define BDI_CAP_READ_MAP 0x00000010 232 #define BDI_CAP_WRITE_MAP 0x00000020 233 #define BDI_CAP_EXEC_MAP 0x00000040 234 #define BDI_CAP_NO_ACCT_WB 0x00000080 235 #define BDI_CAP_SWAP_BACKED 0x00000100 236 237 #define BDI_CAP_VMFLAGS \ 238 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP) 239 240 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \ 241 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB) 242 243 #if defined(VM_MAYREAD) && \ 244 (BDI_CAP_READ_MAP != VM_MAYREAD || \ 245 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \ 246 BDI_CAP_EXEC_MAP != VM_MAYEXEC) 247 #error please change backing_dev_info::capabilities flags 248 #endif 249 250 extern struct backing_dev_info default_backing_dev_info; 251 extern struct backing_dev_info noop_backing_dev_info; 252 void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page); 253 254 int writeback_in_progress(struct backing_dev_info *bdi); 255 256 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits) 257 { 258 if (bdi->congested_fn) 259 return bdi->congested_fn(bdi->congested_data, bdi_bits); 260 return (bdi->state & bdi_bits); 261 } 262 263 static inline int bdi_read_congested(struct backing_dev_info *bdi) 264 { 265 return bdi_congested(bdi, 1 << BDI_sync_congested); 266 } 267 268 static inline int bdi_write_congested(struct backing_dev_info *bdi) 269 { 270 return bdi_congested(bdi, 1 << BDI_async_congested); 271 } 272 273 static inline int bdi_rw_congested(struct backing_dev_info *bdi) 274 { 275 return bdi_congested(bdi, (1 << BDI_sync_congested) | 276 (1 << BDI_async_congested)); 277 } 278 279 enum { 280 BLK_RW_ASYNC = 0, 281 BLK_RW_SYNC = 1, 282 }; 283 284 void clear_bdi_congested(struct backing_dev_info *bdi, int sync); 285 void set_bdi_congested(struct backing_dev_info *bdi, int sync); 286 long congestion_wait(int sync, long timeout); 287 288 289 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi) 290 { 291 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK); 292 } 293 294 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi) 295 { 296 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY); 297 } 298 299 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi) 300 { 301 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */ 302 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB | 303 BDI_CAP_NO_WRITEBACK)); 304 } 305 306 static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi) 307 { 308 return bdi->capabilities & BDI_CAP_SWAP_BACKED; 309 } 310 311 static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi) 312 { 313 return bdi == &default_backing_dev_info; 314 } 315 316 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping) 317 { 318 return bdi_cap_writeback_dirty(mapping->backing_dev_info); 319 } 320 321 static inline bool mapping_cap_account_dirty(struct address_space *mapping) 322 { 323 return bdi_cap_account_dirty(mapping->backing_dev_info); 324 } 325 326 static inline bool mapping_cap_swap_backed(struct address_space *mapping) 327 { 328 return bdi_cap_swap_backed(mapping->backing_dev_info); 329 } 330 331 static inline int bdi_sched_wait(void *word) 332 { 333 schedule(); 334 return 0; 335 } 336 337 static inline void blk_run_backing_dev(struct backing_dev_info *bdi, 338 struct page *page) 339 { 340 if (bdi && bdi->unplug_io_fn) 341 bdi->unplug_io_fn(bdi, page); 342 } 343 344 static inline void blk_run_address_space(struct address_space *mapping) 345 { 346 if (mapping) 347 blk_run_backing_dev(mapping->backing_dev_info, NULL); 348 } 349 350 #endif /* _LINUX_BACKING_DEV_H */ 351