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 unsigned long wb_mask; /* bitmask of registered tasks */ 86 unsigned int wb_cnt; /* number of registered tasks */ 87 88 struct list_head work_list; 89 90 struct device *dev; 91 92 struct timer_list laptop_mode_wb_timer; 93 94 #ifdef CONFIG_DEBUG_FS 95 struct dentry *debug_dir; 96 struct dentry *debug_stats; 97 #endif 98 }; 99 100 int bdi_init(struct backing_dev_info *bdi); 101 void bdi_destroy(struct backing_dev_info *bdi); 102 103 int bdi_register(struct backing_dev_info *bdi, struct device *parent, 104 const char *fmt, ...); 105 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev); 106 void bdi_unregister(struct backing_dev_info *bdi); 107 int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int); 108 void bdi_start_writeback(struct backing_dev_info *bdi, struct super_block *sb, 109 long nr_pages); 110 int bdi_writeback_task(struct bdi_writeback *wb); 111 int bdi_has_dirty_io(struct backing_dev_info *bdi); 112 void bdi_arm_supers_timer(void); 113 114 extern spinlock_t bdi_lock; 115 extern struct list_head bdi_list; 116 117 static inline int wb_has_dirty_io(struct bdi_writeback *wb) 118 { 119 return !list_empty(&wb->b_dirty) || 120 !list_empty(&wb->b_io) || 121 !list_empty(&wb->b_more_io); 122 } 123 124 static inline void __add_bdi_stat(struct backing_dev_info *bdi, 125 enum bdi_stat_item item, s64 amount) 126 { 127 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH); 128 } 129 130 static inline void __inc_bdi_stat(struct backing_dev_info *bdi, 131 enum bdi_stat_item item) 132 { 133 __add_bdi_stat(bdi, item, 1); 134 } 135 136 static inline void inc_bdi_stat(struct backing_dev_info *bdi, 137 enum bdi_stat_item item) 138 { 139 unsigned long flags; 140 141 local_irq_save(flags); 142 __inc_bdi_stat(bdi, item); 143 local_irq_restore(flags); 144 } 145 146 static inline void __dec_bdi_stat(struct backing_dev_info *bdi, 147 enum bdi_stat_item item) 148 { 149 __add_bdi_stat(bdi, item, -1); 150 } 151 152 static inline void dec_bdi_stat(struct backing_dev_info *bdi, 153 enum bdi_stat_item item) 154 { 155 unsigned long flags; 156 157 local_irq_save(flags); 158 __dec_bdi_stat(bdi, item); 159 local_irq_restore(flags); 160 } 161 162 static inline s64 bdi_stat(struct backing_dev_info *bdi, 163 enum bdi_stat_item item) 164 { 165 return percpu_counter_read_positive(&bdi->bdi_stat[item]); 166 } 167 168 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi, 169 enum bdi_stat_item item) 170 { 171 return percpu_counter_sum_positive(&bdi->bdi_stat[item]); 172 } 173 174 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi, 175 enum bdi_stat_item item) 176 { 177 s64 sum; 178 unsigned long flags; 179 180 local_irq_save(flags); 181 sum = __bdi_stat_sum(bdi, item); 182 local_irq_restore(flags); 183 184 return sum; 185 } 186 187 extern void bdi_writeout_inc(struct backing_dev_info *bdi); 188 189 /* 190 * maximal error of a stat counter. 191 */ 192 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi) 193 { 194 #ifdef CONFIG_SMP 195 return nr_cpu_ids * BDI_STAT_BATCH; 196 #else 197 return 1; 198 #endif 199 } 200 201 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio); 202 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio); 203 204 /* 205 * Flags in backing_dev_info::capability 206 * 207 * The first three flags control whether dirty pages will contribute to the 208 * VM's accounting and whether writepages() should be called for dirty pages 209 * (something that would not, for example, be appropriate for ramfs) 210 * 211 * WARNING: these flags are closely related and should not normally be 212 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these 213 * three flags into a single convenience macro. 214 * 215 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting 216 * BDI_CAP_NO_WRITEBACK: Don't write pages back 217 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages 218 * 219 * These flags let !MMU mmap() govern direct device mapping vs immediate 220 * copying more easily for MAP_PRIVATE, especially for ROM filesystems. 221 * 222 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE) 223 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED) 224 * BDI_CAP_READ_MAP: Can be mapped for reading 225 * BDI_CAP_WRITE_MAP: Can be mapped for writing 226 * BDI_CAP_EXEC_MAP: Can be mapped for execution 227 * 228 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed. 229 */ 230 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001 231 #define BDI_CAP_NO_WRITEBACK 0x00000002 232 #define BDI_CAP_MAP_COPY 0x00000004 233 #define BDI_CAP_MAP_DIRECT 0x00000008 234 #define BDI_CAP_READ_MAP 0x00000010 235 #define BDI_CAP_WRITE_MAP 0x00000020 236 #define BDI_CAP_EXEC_MAP 0x00000040 237 #define BDI_CAP_NO_ACCT_WB 0x00000080 238 #define BDI_CAP_SWAP_BACKED 0x00000100 239 240 #define BDI_CAP_VMFLAGS \ 241 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP) 242 243 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \ 244 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB) 245 246 #if defined(VM_MAYREAD) && \ 247 (BDI_CAP_READ_MAP != VM_MAYREAD || \ 248 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \ 249 BDI_CAP_EXEC_MAP != VM_MAYEXEC) 250 #error please change backing_dev_info::capabilities flags 251 #endif 252 253 extern struct backing_dev_info default_backing_dev_info; 254 extern struct backing_dev_info noop_backing_dev_info; 255 void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page); 256 257 int writeback_in_progress(struct backing_dev_info *bdi); 258 259 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits) 260 { 261 if (bdi->congested_fn) 262 return bdi->congested_fn(bdi->congested_data, bdi_bits); 263 return (bdi->state & bdi_bits); 264 } 265 266 static inline int bdi_read_congested(struct backing_dev_info *bdi) 267 { 268 return bdi_congested(bdi, 1 << BDI_sync_congested); 269 } 270 271 static inline int bdi_write_congested(struct backing_dev_info *bdi) 272 { 273 return bdi_congested(bdi, 1 << BDI_async_congested); 274 } 275 276 static inline int bdi_rw_congested(struct backing_dev_info *bdi) 277 { 278 return bdi_congested(bdi, (1 << BDI_sync_congested) | 279 (1 << BDI_async_congested)); 280 } 281 282 enum { 283 BLK_RW_ASYNC = 0, 284 BLK_RW_SYNC = 1, 285 }; 286 287 void clear_bdi_congested(struct backing_dev_info *bdi, int sync); 288 void set_bdi_congested(struct backing_dev_info *bdi, int sync); 289 long congestion_wait(int sync, long timeout); 290 291 292 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi) 293 { 294 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK); 295 } 296 297 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi) 298 { 299 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY); 300 } 301 302 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi) 303 { 304 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */ 305 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB | 306 BDI_CAP_NO_WRITEBACK)); 307 } 308 309 static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi) 310 { 311 return bdi->capabilities & BDI_CAP_SWAP_BACKED; 312 } 313 314 static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi) 315 { 316 return bdi == &default_backing_dev_info; 317 } 318 319 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping) 320 { 321 return bdi_cap_writeback_dirty(mapping->backing_dev_info); 322 } 323 324 static inline bool mapping_cap_account_dirty(struct address_space *mapping) 325 { 326 return bdi_cap_account_dirty(mapping->backing_dev_info); 327 } 328 329 static inline bool mapping_cap_swap_backed(struct address_space *mapping) 330 { 331 return bdi_cap_swap_backed(mapping->backing_dev_info); 332 } 333 334 static inline int bdi_sched_wait(void *word) 335 { 336 schedule(); 337 return 0; 338 } 339 340 static inline void blk_run_backing_dev(struct backing_dev_info *bdi, 341 struct page *page) 342 { 343 if (bdi && bdi->unplug_io_fn) 344 bdi->unplug_io_fn(bdi, page); 345 } 346 347 static inline void blk_run_address_space(struct address_space *mapping) 348 { 349 if (mapping) 350 blk_run_backing_dev(mapping->backing_dev_info, NULL); 351 } 352 353 #endif /* _LINUX_BACKING_DEV_H */ 354