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/flex_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 <linux/atomic.h> 20 #include <linux/sysctl.h> 21 #include <linux/workqueue.h> 22 23 struct page; 24 struct device; 25 struct dentry; 26 27 /* 28 * Bits in backing_dev_info.state 29 */ 30 enum bdi_state { 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_writeback_running, /* Writeback is in progress */ 35 }; 36 37 typedef int (congested_fn)(void *, int); 38 39 enum bdi_stat_item { 40 BDI_RECLAIMABLE, 41 BDI_WRITEBACK, 42 BDI_DIRTIED, 43 BDI_WRITTEN, 44 NR_BDI_STAT_ITEMS 45 }; 46 47 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids))) 48 49 struct bdi_writeback { 50 struct backing_dev_info *bdi; /* our parent bdi */ 51 52 unsigned long last_old_flush; /* last old data flush */ 53 54 struct delayed_work dwork; /* work item used for writeback */ 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 struct list_head b_dirty_time; /* time stamps are dirty */ 59 spinlock_t list_lock; /* protects the b_* lists */ 60 }; 61 62 struct backing_dev_info { 63 struct list_head bdi_list; 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 70 char *name; 71 72 struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS]; 73 74 unsigned long bw_time_stamp; /* last time write bw is updated */ 75 unsigned long dirtied_stamp; 76 unsigned long written_stamp; /* pages written at bw_time_stamp */ 77 unsigned long write_bandwidth; /* the estimated write bandwidth */ 78 unsigned long avg_write_bandwidth; /* further smoothed write bw */ 79 80 /* 81 * The base dirty throttle rate, re-calculated on every 200ms. 82 * All the bdi tasks' dirty rate will be curbed under it. 83 * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit 84 * in small steps and is much more smooth/stable than the latter. 85 */ 86 unsigned long dirty_ratelimit; 87 unsigned long balanced_dirty_ratelimit; 88 89 struct fprop_local_percpu completions; 90 int dirty_exceeded; 91 92 unsigned int min_ratio; 93 unsigned int max_ratio, max_prop_frac; 94 95 struct bdi_writeback wb; /* default writeback info for this bdi */ 96 spinlock_t wb_lock; /* protects work_list & wb.dwork scheduling */ 97 98 struct list_head work_list; 99 100 struct device *dev; 101 102 struct timer_list laptop_mode_wb_timer; 103 104 #ifdef CONFIG_DEBUG_FS 105 struct dentry *debug_dir; 106 struct dentry *debug_stats; 107 #endif 108 }; 109 110 struct backing_dev_info *inode_to_bdi(struct inode *inode); 111 112 int __must_check bdi_init(struct backing_dev_info *bdi); 113 void bdi_destroy(struct backing_dev_info *bdi); 114 115 __printf(3, 4) 116 int bdi_register(struct backing_dev_info *bdi, struct device *parent, 117 const char *fmt, ...); 118 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev); 119 int __must_check bdi_setup_and_register(struct backing_dev_info *, char *); 120 void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages, 121 enum wb_reason reason); 122 void bdi_start_background_writeback(struct backing_dev_info *bdi); 123 void bdi_writeback_workfn(struct work_struct *work); 124 int bdi_has_dirty_io(struct backing_dev_info *bdi); 125 void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi); 126 127 extern spinlock_t bdi_lock; 128 extern struct list_head bdi_list; 129 130 extern struct workqueue_struct *bdi_wq; 131 132 static inline int wb_has_dirty_io(struct bdi_writeback *wb) 133 { 134 return !list_empty(&wb->b_dirty) || 135 !list_empty(&wb->b_io) || 136 !list_empty(&wb->b_more_io); 137 } 138 139 static inline void __add_bdi_stat(struct backing_dev_info *bdi, 140 enum bdi_stat_item item, s64 amount) 141 { 142 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH); 143 } 144 145 static inline void __inc_bdi_stat(struct backing_dev_info *bdi, 146 enum bdi_stat_item item) 147 { 148 __add_bdi_stat(bdi, item, 1); 149 } 150 151 static inline void inc_bdi_stat(struct backing_dev_info *bdi, 152 enum bdi_stat_item item) 153 { 154 unsigned long flags; 155 156 local_irq_save(flags); 157 __inc_bdi_stat(bdi, item); 158 local_irq_restore(flags); 159 } 160 161 static inline void __dec_bdi_stat(struct backing_dev_info *bdi, 162 enum bdi_stat_item item) 163 { 164 __add_bdi_stat(bdi, item, -1); 165 } 166 167 static inline void dec_bdi_stat(struct backing_dev_info *bdi, 168 enum bdi_stat_item item) 169 { 170 unsigned long flags; 171 172 local_irq_save(flags); 173 __dec_bdi_stat(bdi, item); 174 local_irq_restore(flags); 175 } 176 177 static inline s64 bdi_stat(struct backing_dev_info *bdi, 178 enum bdi_stat_item item) 179 { 180 return percpu_counter_read_positive(&bdi->bdi_stat[item]); 181 } 182 183 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi, 184 enum bdi_stat_item item) 185 { 186 return percpu_counter_sum_positive(&bdi->bdi_stat[item]); 187 } 188 189 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi, 190 enum bdi_stat_item item) 191 { 192 s64 sum; 193 unsigned long flags; 194 195 local_irq_save(flags); 196 sum = __bdi_stat_sum(bdi, item); 197 local_irq_restore(flags); 198 199 return sum; 200 } 201 202 extern void bdi_writeout_inc(struct backing_dev_info *bdi); 203 204 /* 205 * maximal error of a stat counter. 206 */ 207 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi) 208 { 209 #ifdef CONFIG_SMP 210 return nr_cpu_ids * BDI_STAT_BATCH; 211 #else 212 return 1; 213 #endif 214 } 215 216 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio); 217 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio); 218 219 /* 220 * Flags in backing_dev_info::capability 221 * 222 * The first three flags control whether dirty pages will contribute to the 223 * VM's accounting and whether writepages() should be called for dirty pages 224 * (something that would not, for example, be appropriate for ramfs) 225 * 226 * WARNING: these flags are closely related and should not normally be 227 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these 228 * three flags into a single convenience macro. 229 * 230 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting 231 * BDI_CAP_NO_WRITEBACK: Don't write pages back 232 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages 233 * BDI_CAP_STRICTLIMIT: Keep number of dirty pages below bdi threshold. 234 */ 235 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001 236 #define BDI_CAP_NO_WRITEBACK 0x00000002 237 #define BDI_CAP_NO_ACCT_WB 0x00000004 238 #define BDI_CAP_STABLE_WRITES 0x00000008 239 #define BDI_CAP_STRICTLIMIT 0x00000010 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 extern struct backing_dev_info noop_backing_dev_info; 245 246 int writeback_in_progress(struct backing_dev_info *bdi); 247 248 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits) 249 { 250 if (bdi->congested_fn) 251 return bdi->congested_fn(bdi->congested_data, bdi_bits); 252 return (bdi->state & bdi_bits); 253 } 254 255 static inline int bdi_read_congested(struct backing_dev_info *bdi) 256 { 257 return bdi_congested(bdi, 1 << BDI_sync_congested); 258 } 259 260 static inline int bdi_write_congested(struct backing_dev_info *bdi) 261 { 262 return bdi_congested(bdi, 1 << BDI_async_congested); 263 } 264 265 static inline int bdi_rw_congested(struct backing_dev_info *bdi) 266 { 267 return bdi_congested(bdi, (1 << BDI_sync_congested) | 268 (1 << BDI_async_congested)); 269 } 270 271 enum { 272 BLK_RW_ASYNC = 0, 273 BLK_RW_SYNC = 1, 274 }; 275 276 void clear_bdi_congested(struct backing_dev_info *bdi, int sync); 277 void set_bdi_congested(struct backing_dev_info *bdi, int sync); 278 long congestion_wait(int sync, long timeout); 279 long wait_iff_congested(struct zone *zone, int sync, long timeout); 280 int pdflush_proc_obsolete(struct ctl_table *table, int write, 281 void __user *buffer, size_t *lenp, loff_t *ppos); 282 283 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi) 284 { 285 return bdi->capabilities & BDI_CAP_STABLE_WRITES; 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 mapping_cap_writeback_dirty(struct address_space *mapping) 306 { 307 return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host)); 308 } 309 310 static inline bool mapping_cap_account_dirty(struct address_space *mapping) 311 { 312 return bdi_cap_account_dirty(inode_to_bdi(mapping->host)); 313 } 314 315 static inline int bdi_sched_wait(void *word) 316 { 317 schedule(); 318 return 0; 319 } 320 321 #endif /* _LINUX_BACKING_DEV_H */ 322