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