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 list_head list; /* hangs off the bdi */ 49 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 55 struct task_struct *task; /* writeback task */ 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 struct rcu_head rcu_head; 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 update side of wb_list */ 84 struct list_head wb_list; /* the flusher threads hanging off this bdi */ 85 86 struct list_head work_list; 87 88 struct device *dev; 89 90 struct timer_list laptop_mode_wb_timer; 91 92 #ifdef CONFIG_DEBUG_FS 93 struct dentry *debug_dir; 94 struct dentry *debug_stats; 95 #endif 96 }; 97 98 int bdi_init(struct backing_dev_info *bdi); 99 void bdi_destroy(struct backing_dev_info *bdi); 100 101 int bdi_register(struct backing_dev_info *bdi, struct device *parent, 102 const char *fmt, ...); 103 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev); 104 void bdi_unregister(struct backing_dev_info *bdi); 105 int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int); 106 void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages); 107 void bdi_start_background_writeback(struct backing_dev_info *bdi); 108 int bdi_writeback_task(struct bdi_writeback *wb); 109 int bdi_has_dirty_io(struct backing_dev_info *bdi); 110 void bdi_arm_supers_timer(void); 111 112 extern spinlock_t bdi_lock; 113 extern struct list_head bdi_list; 114 115 static inline int wb_has_dirty_io(struct bdi_writeback *wb) 116 { 117 return !list_empty(&wb->b_dirty) || 118 !list_empty(&wb->b_io) || 119 !list_empty(&wb->b_more_io); 120 } 121 122 static inline void __add_bdi_stat(struct backing_dev_info *bdi, 123 enum bdi_stat_item item, s64 amount) 124 { 125 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH); 126 } 127 128 static inline void __inc_bdi_stat(struct backing_dev_info *bdi, 129 enum bdi_stat_item item) 130 { 131 __add_bdi_stat(bdi, item, 1); 132 } 133 134 static inline void inc_bdi_stat(struct backing_dev_info *bdi, 135 enum bdi_stat_item item) 136 { 137 unsigned long flags; 138 139 local_irq_save(flags); 140 __inc_bdi_stat(bdi, item); 141 local_irq_restore(flags); 142 } 143 144 static inline void __dec_bdi_stat(struct backing_dev_info *bdi, 145 enum bdi_stat_item item) 146 { 147 __add_bdi_stat(bdi, item, -1); 148 } 149 150 static inline void dec_bdi_stat(struct backing_dev_info *bdi, 151 enum bdi_stat_item item) 152 { 153 unsigned long flags; 154 155 local_irq_save(flags); 156 __dec_bdi_stat(bdi, item); 157 local_irq_restore(flags); 158 } 159 160 static inline s64 bdi_stat(struct backing_dev_info *bdi, 161 enum bdi_stat_item item) 162 { 163 return percpu_counter_read_positive(&bdi->bdi_stat[item]); 164 } 165 166 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi, 167 enum bdi_stat_item item) 168 { 169 return percpu_counter_sum_positive(&bdi->bdi_stat[item]); 170 } 171 172 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi, 173 enum bdi_stat_item item) 174 { 175 s64 sum; 176 unsigned long flags; 177 178 local_irq_save(flags); 179 sum = __bdi_stat_sum(bdi, item); 180 local_irq_restore(flags); 181 182 return sum; 183 } 184 185 extern void bdi_writeout_inc(struct backing_dev_info *bdi); 186 187 /* 188 * maximal error of a stat counter. 189 */ 190 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi) 191 { 192 #ifdef CONFIG_SMP 193 return nr_cpu_ids * BDI_STAT_BATCH; 194 #else 195 return 1; 196 #endif 197 } 198 199 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio); 200 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio); 201 202 /* 203 * Flags in backing_dev_info::capability 204 * 205 * The first three flags control whether dirty pages will contribute to the 206 * VM's accounting and whether writepages() should be called for dirty pages 207 * (something that would not, for example, be appropriate for ramfs) 208 * 209 * WARNING: these flags are closely related and should not normally be 210 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these 211 * three flags into a single convenience macro. 212 * 213 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting 214 * BDI_CAP_NO_WRITEBACK: Don't write pages back 215 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages 216 * 217 * These flags let !MMU mmap() govern direct device mapping vs immediate 218 * copying more easily for MAP_PRIVATE, especially for ROM filesystems. 219 * 220 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE) 221 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED) 222 * BDI_CAP_READ_MAP: Can be mapped for reading 223 * BDI_CAP_WRITE_MAP: Can be mapped for writing 224 * BDI_CAP_EXEC_MAP: Can be mapped for execution 225 * 226 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed. 227 */ 228 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001 229 #define BDI_CAP_NO_WRITEBACK 0x00000002 230 #define BDI_CAP_MAP_COPY 0x00000004 231 #define BDI_CAP_MAP_DIRECT 0x00000008 232 #define BDI_CAP_READ_MAP 0x00000010 233 #define BDI_CAP_WRITE_MAP 0x00000020 234 #define BDI_CAP_EXEC_MAP 0x00000040 235 #define BDI_CAP_NO_ACCT_WB 0x00000080 236 #define BDI_CAP_SWAP_BACKED 0x00000100 237 238 #define BDI_CAP_VMFLAGS \ 239 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP) 240 241 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \ 242 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB) 243 244 #if defined(VM_MAYREAD) && \ 245 (BDI_CAP_READ_MAP != VM_MAYREAD || \ 246 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \ 247 BDI_CAP_EXEC_MAP != VM_MAYEXEC) 248 #error please change backing_dev_info::capabilities flags 249 #endif 250 251 extern struct backing_dev_info default_backing_dev_info; 252 extern struct backing_dev_info noop_backing_dev_info; 253 void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page); 254 255 int writeback_in_progress(struct backing_dev_info *bdi); 256 257 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits) 258 { 259 if (bdi->congested_fn) 260 return bdi->congested_fn(bdi->congested_data, bdi_bits); 261 return (bdi->state & bdi_bits); 262 } 263 264 static inline int bdi_read_congested(struct backing_dev_info *bdi) 265 { 266 return bdi_congested(bdi, 1 << BDI_sync_congested); 267 } 268 269 static inline int bdi_write_congested(struct backing_dev_info *bdi) 270 { 271 return bdi_congested(bdi, 1 << BDI_async_congested); 272 } 273 274 static inline int bdi_rw_congested(struct backing_dev_info *bdi) 275 { 276 return bdi_congested(bdi, (1 << BDI_sync_congested) | 277 (1 << BDI_async_congested)); 278 } 279 280 enum { 281 BLK_RW_ASYNC = 0, 282 BLK_RW_SYNC = 1, 283 }; 284 285 void clear_bdi_congested(struct backing_dev_info *bdi, int sync); 286 void set_bdi_congested(struct backing_dev_info *bdi, int sync); 287 long congestion_wait(int sync, long timeout); 288 289 290 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi) 291 { 292 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK); 293 } 294 295 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi) 296 { 297 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY); 298 } 299 300 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi) 301 { 302 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */ 303 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB | 304 BDI_CAP_NO_WRITEBACK)); 305 } 306 307 static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi) 308 { 309 return bdi->capabilities & BDI_CAP_SWAP_BACKED; 310 } 311 312 static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi) 313 { 314 return bdi == &default_backing_dev_info; 315 } 316 317 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping) 318 { 319 return bdi_cap_writeback_dirty(mapping->backing_dev_info); 320 } 321 322 static inline bool mapping_cap_account_dirty(struct address_space *mapping) 323 { 324 return bdi_cap_account_dirty(mapping->backing_dev_info); 325 } 326 327 static inline bool mapping_cap_swap_backed(struct address_space *mapping) 328 { 329 return bdi_cap_swap_backed(mapping->backing_dev_info); 330 } 331 332 static inline int bdi_sched_wait(void *word) 333 { 334 schedule(); 335 return 0; 336 } 337 338 static inline void blk_run_backing_dev(struct backing_dev_info *bdi, 339 struct page *page) 340 { 341 if (bdi && bdi->unplug_io_fn) 342 bdi->unplug_io_fn(bdi, page); 343 } 344 345 static inline void blk_run_address_space(struct address_space *mapping) 346 { 347 if (mapping) 348 blk_run_backing_dev(mapping->backing_dev_info, NULL); 349 } 350 351 #endif /* _LINUX_BACKING_DEV_H */ 352