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/writeback.h> 18 #include <asm/atomic.h> 19 20 struct page; 21 struct device; 22 struct dentry; 23 24 /* 25 * Bits in backing_dev_info.state 26 */ 27 enum bdi_state { 28 BDI_pending, /* On its way to being activated */ 29 BDI_wb_alloc, /* Default embedded wb allocated */ 30 BDI_async_congested, /* The async (write) queue is getting full */ 31 BDI_sync_congested, /* The sync queue is getting full */ 32 BDI_registered, /* bdi_register() was done */ 33 BDI_unused, /* Available bits start here */ 34 }; 35 36 typedef int (congested_fn)(void *, int); 37 38 enum bdi_stat_item { 39 BDI_RECLAIMABLE, 40 BDI_WRITEBACK, 41 NR_BDI_STAT_ITEMS 42 }; 43 44 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids))) 45 46 struct bdi_writeback { 47 struct list_head list; /* hangs off the bdi */ 48 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 54 struct task_struct *task; /* writeback task */ 55 struct list_head b_dirty; /* dirty inodes */ 56 struct list_head b_io; /* parked for writeback */ 57 struct list_head b_more_io; /* parked for more writeback */ 58 }; 59 60 struct backing_dev_info { 61 struct list_head bdi_list; 62 struct rcu_head rcu_head; 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 update side of wb_list */ 83 struct list_head wb_list; /* the flusher threads hanging off this bdi */ 84 unsigned long wb_mask; /* bitmask of registered tasks */ 85 unsigned int wb_cnt; /* number of registered tasks */ 86 87 struct list_head work_list; 88 89 struct device *dev; 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, struct super_block *sb, 106 long nr_pages); 107 int bdi_writeback_task(struct bdi_writeback *wb); 108 int bdi_has_dirty_io(struct backing_dev_info *bdi); 109 110 extern spinlock_t bdi_lock; 111 extern struct list_head bdi_list; 112 113 static inline int wb_has_dirty_io(struct bdi_writeback *wb) 114 { 115 return !list_empty(&wb->b_dirty) || 116 !list_empty(&wb->b_io) || 117 !list_empty(&wb->b_more_io); 118 } 119 120 static inline void __add_bdi_stat(struct backing_dev_info *bdi, 121 enum bdi_stat_item item, s64 amount) 122 { 123 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH); 124 } 125 126 static inline void __inc_bdi_stat(struct backing_dev_info *bdi, 127 enum bdi_stat_item item) 128 { 129 __add_bdi_stat(bdi, item, 1); 130 } 131 132 static inline void inc_bdi_stat(struct backing_dev_info *bdi, 133 enum bdi_stat_item item) 134 { 135 unsigned long flags; 136 137 local_irq_save(flags); 138 __inc_bdi_stat(bdi, item); 139 local_irq_restore(flags); 140 } 141 142 static inline void __dec_bdi_stat(struct backing_dev_info *bdi, 143 enum bdi_stat_item item) 144 { 145 __add_bdi_stat(bdi, item, -1); 146 } 147 148 static inline void dec_bdi_stat(struct backing_dev_info *bdi, 149 enum bdi_stat_item item) 150 { 151 unsigned long flags; 152 153 local_irq_save(flags); 154 __dec_bdi_stat(bdi, item); 155 local_irq_restore(flags); 156 } 157 158 static inline s64 bdi_stat(struct backing_dev_info *bdi, 159 enum bdi_stat_item item) 160 { 161 return percpu_counter_read_positive(&bdi->bdi_stat[item]); 162 } 163 164 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi, 165 enum bdi_stat_item item) 166 { 167 return percpu_counter_sum_positive(&bdi->bdi_stat[item]); 168 } 169 170 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi, 171 enum bdi_stat_item item) 172 { 173 s64 sum; 174 unsigned long flags; 175 176 local_irq_save(flags); 177 sum = __bdi_stat_sum(bdi, item); 178 local_irq_restore(flags); 179 180 return sum; 181 } 182 183 extern void bdi_writeout_inc(struct backing_dev_info *bdi); 184 185 /* 186 * maximal error of a stat counter. 187 */ 188 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi) 189 { 190 #ifdef CONFIG_SMP 191 return nr_cpu_ids * BDI_STAT_BATCH; 192 #else 193 return 1; 194 #endif 195 } 196 197 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio); 198 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio); 199 200 /* 201 * Flags in backing_dev_info::capability 202 * 203 * The first three flags control whether dirty pages will contribute to the 204 * VM's accounting and whether writepages() should be called for dirty pages 205 * (something that would not, for example, be appropriate for ramfs) 206 * 207 * WARNING: these flags are closely related and should not normally be 208 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these 209 * three flags into a single convenience macro. 210 * 211 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting 212 * BDI_CAP_NO_WRITEBACK: Don't write pages back 213 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages 214 * 215 * These flags let !MMU mmap() govern direct device mapping vs immediate 216 * copying more easily for MAP_PRIVATE, especially for ROM filesystems. 217 * 218 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE) 219 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED) 220 * BDI_CAP_READ_MAP: Can be mapped for reading 221 * BDI_CAP_WRITE_MAP: Can be mapped for writing 222 * BDI_CAP_EXEC_MAP: Can be mapped for execution 223 * 224 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed. 225 */ 226 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001 227 #define BDI_CAP_NO_WRITEBACK 0x00000002 228 #define BDI_CAP_MAP_COPY 0x00000004 229 #define BDI_CAP_MAP_DIRECT 0x00000008 230 #define BDI_CAP_READ_MAP 0x00000010 231 #define BDI_CAP_WRITE_MAP 0x00000020 232 #define BDI_CAP_EXEC_MAP 0x00000040 233 #define BDI_CAP_NO_ACCT_WB 0x00000080 234 #define BDI_CAP_SWAP_BACKED 0x00000100 235 236 #define BDI_CAP_VMFLAGS \ 237 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP) 238 239 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \ 240 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB) 241 242 #if defined(VM_MAYREAD) && \ 243 (BDI_CAP_READ_MAP != VM_MAYREAD || \ 244 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \ 245 BDI_CAP_EXEC_MAP != VM_MAYEXEC) 246 #error please change backing_dev_info::capabilities flags 247 #endif 248 249 extern struct backing_dev_info default_backing_dev_info; 250 extern struct backing_dev_info noop_backing_dev_info; 251 void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page); 252 253 int writeback_in_progress(struct backing_dev_info *bdi); 254 255 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits) 256 { 257 if (bdi->congested_fn) 258 return bdi->congested_fn(bdi->congested_data, bdi_bits); 259 return (bdi->state & bdi_bits); 260 } 261 262 static inline int bdi_read_congested(struct backing_dev_info *bdi) 263 { 264 return bdi_congested(bdi, 1 << BDI_sync_congested); 265 } 266 267 static inline int bdi_write_congested(struct backing_dev_info *bdi) 268 { 269 return bdi_congested(bdi, 1 << BDI_async_congested); 270 } 271 272 static inline int bdi_rw_congested(struct backing_dev_info *bdi) 273 { 274 return bdi_congested(bdi, (1 << BDI_sync_congested) | 275 (1 << BDI_async_congested)); 276 } 277 278 enum { 279 BLK_RW_ASYNC = 0, 280 BLK_RW_SYNC = 1, 281 }; 282 283 void clear_bdi_congested(struct backing_dev_info *bdi, int sync); 284 void set_bdi_congested(struct backing_dev_info *bdi, int sync); 285 long congestion_wait(int sync, long timeout); 286 287 288 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi) 289 { 290 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK); 291 } 292 293 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi) 294 { 295 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY); 296 } 297 298 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi) 299 { 300 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */ 301 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB | 302 BDI_CAP_NO_WRITEBACK)); 303 } 304 305 static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi) 306 { 307 return bdi->capabilities & BDI_CAP_SWAP_BACKED; 308 } 309 310 static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi) 311 { 312 return bdi == &default_backing_dev_info; 313 } 314 315 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping) 316 { 317 return bdi_cap_writeback_dirty(mapping->backing_dev_info); 318 } 319 320 static inline bool mapping_cap_account_dirty(struct address_space *mapping) 321 { 322 return bdi_cap_account_dirty(mapping->backing_dev_info); 323 } 324 325 static inline bool mapping_cap_swap_backed(struct address_space *mapping) 326 { 327 return bdi_cap_swap_backed(mapping->backing_dev_info); 328 } 329 330 static inline int bdi_sched_wait(void *word) 331 { 332 schedule(); 333 return 0; 334 } 335 336 static inline void blk_run_backing_dev(struct backing_dev_info *bdi, 337 struct page *page) 338 { 339 if (bdi && bdi->unplug_io_fn) 340 bdi->unplug_io_fn(bdi, page); 341 } 342 343 static inline void blk_run_address_space(struct address_space *mapping) 344 { 345 if (mapping) 346 blk_run_backing_dev(mapping->backing_dev_info, NULL); 347 } 348 349 #endif /* _LINUX_BACKING_DEV_H */ 350