include/linux/backing-dev.h

   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 void bdi_unregister(struct backing_dev_info *bdi);
 120 int __must_check bdi_setup_and_register(struct backing_dev_info *, char *);
 121 void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages,
 122                         enum wb_reason reason);
 123 void bdi_start_background_writeback(struct backing_dev_info *bdi);
 124 void bdi_writeback_workfn(struct work_struct *work);
 125 int bdi_has_dirty_io(struct backing_dev_info *bdi);
 126 void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi);
 127
 128 extern spinlock_t bdi_lock;
 129 extern struct list_head bdi_list;
 130
 131 extern struct workqueue_struct *bdi_wq;
 132
 133 static inline int wb_has_dirty_io(struct bdi_writeback *wb)
 134 {
 135         return !list_empty(&wb->b_dirty) ||
 136                !list_empty(&wb->b_io) ||
 137                !list_empty(&wb->b_more_io);
 138 }
 139
 140 static inline void __add_bdi_stat(struct backing_dev_info *bdi,
 141                 enum bdi_stat_item item, s64 amount)
 142 {
 143         __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
 144 }
 145
 146 static inline void __inc_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 inc_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         __inc_bdi_stat(bdi, item);
 159         local_irq_restore(flags);
 160 }
 161
 162 static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
 163                 enum bdi_stat_item item)
 164 {
 165         __add_bdi_stat(bdi, item, -1);
 166 }
 167
 168 static inline void dec_bdi_stat(struct backing_dev_info *bdi,
 169                 enum bdi_stat_item item)
 170 {
 171         unsigned long flags;
 172
 173         local_irq_save(flags);
 174         __dec_bdi_stat(bdi, item);
 175         local_irq_restore(flags);
 176 }
 177
 178 static inline s64 bdi_stat(struct backing_dev_info *bdi,
 179                 enum bdi_stat_item item)
 180 {
 181         return percpu_counter_read_positive(&bdi->bdi_stat[item]);
 182 }
 183
 184 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
 185                 enum bdi_stat_item item)
 186 {
 187         return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
 188 }
 189
 190 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
 191                 enum bdi_stat_item item)
 192 {
 193         s64 sum;
 194         unsigned long flags;
 195
 196         local_irq_save(flags);
 197         sum = __bdi_stat_sum(bdi, item);
 198         local_irq_restore(flags);
 199
 200         return sum;
 201 }
 202
 203 extern void bdi_writeout_inc(struct backing_dev_info *bdi);
 204
 205 /*
 206  * maximal error of a stat counter.
 207  */
 208 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
 209 {
 210 #ifdef CONFIG_SMP
 211         return nr_cpu_ids * BDI_STAT_BATCH;
 212 #else
 213         return 1;
 214 #endif
 215 }
 216
 217 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
 218 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
 219
 220 /*
 221  * Flags in backing_dev_info::capability
 222  *
 223  * The first three flags control whether dirty pages will contribute to the
 224  * VM's accounting and whether writepages() should be called for dirty pages
 225  * (something that would not, for example, be appropriate for ramfs)
 226  *
 227  * WARNING: these flags are closely related and should not normally be
 228  * used separately.  The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
 229  * three flags into a single convenience macro.
 230  *
 231  * BDI_CAP_NO_ACCT_DIRTY:  Dirty pages shouldn't contribute to accounting
 232  * BDI_CAP_NO_WRITEBACK:   Don't write pages back
 233  * BDI_CAP_NO_ACCT_WB:     Don't automatically account writeback pages
 234  * BDI_CAP_STRICTLIMIT:    Keep number of dirty pages below bdi threshold.
 235  */
 236 #define BDI_CAP_NO_ACCT_DIRTY   0x00000001
 237 #define BDI_CAP_NO_WRITEBACK    0x00000002
 238 #define BDI_CAP_NO_ACCT_WB      0x00000004
 239 #define BDI_CAP_STABLE_WRITES   0x00000008
 240 #define BDI_CAP_STRICTLIMIT     0x00000010
 241
 242 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
 243         (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
 244
 245 extern struct backing_dev_info noop_backing_dev_info;
 246
 247 int writeback_in_progress(struct backing_dev_info *bdi);
 248
 249 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
 250 {
 251         if (bdi->congested_fn)
 252                 return bdi->congested_fn(bdi->congested_data, bdi_bits);
 253         return (bdi->state & bdi_bits);
 254 }
 255
 256 static inline int bdi_read_congested(struct backing_dev_info *bdi)
 257 {
 258         return bdi_congested(bdi, 1 << BDI_sync_congested);
 259 }
 260
 261 static inline int bdi_write_congested(struct backing_dev_info *bdi)
 262 {
 263         return bdi_congested(bdi, 1 << BDI_async_congested);
 264 }
 265
 266 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
 267 {
 268         return bdi_congested(bdi, (1 << BDI_sync_congested) |
 269                                   (1 << BDI_async_congested));
 270 }
 271
 272 enum {
 273         BLK_RW_ASYNC    = 0,
 274         BLK_RW_SYNC     = 1,
 275 };
 276
 277 void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
 278 void set_bdi_congested(struct backing_dev_info *bdi, int sync);
 279 long congestion_wait(int sync, long timeout);
 280 long wait_iff_congested(struct zone *zone, int sync, long timeout);
 281 int pdflush_proc_obsolete(struct ctl_table *table, int write,
 282                 void __user *buffer, size_t *lenp, loff_t *ppos);
 283
 284 static inline bool bdi_cap_stable_pages_required(struct backing_dev_info *bdi)
 285 {
 286         return bdi->capabilities & BDI_CAP_STABLE_WRITES;
 287 }
 288
 289 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
 290 {
 291         return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
 292 }
 293
 294 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
 295 {
 296         return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
 297 }
 298
 299 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
 300 {
 301         /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
 302         return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
 303                                       BDI_CAP_NO_WRITEBACK));
 304 }
 305
 306 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
 307 {
 308         return bdi_cap_writeback_dirty(inode_to_bdi(mapping->host));
 309 }
 310
 311 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
 312 {
 313         return bdi_cap_account_dirty(inode_to_bdi(mapping->host));
 314 }
 315
 316 static inline int bdi_sched_wait(void *word)
 317 {
 318         schedule();
 319         return 0;
 320 }
 321
 322 #endif          /* _LINUX_BACKING_DEV_H */