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         spinlock_t list_lock;           /* protects the b_* lists */
  59 };
  60
  61 struct backing_dev_info {
  62         struct list_head bdi_list;
  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
  69         char *name;
  70
  71         struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
  72
  73         unsigned long bw_time_stamp;    /* last time write bw is updated */
  74         unsigned long dirtied_stamp;
  75         unsigned long written_stamp;    /* pages written at bw_time_stamp */
  76         unsigned long write_bandwidth;  /* the estimated write bandwidth */
  77         unsigned long avg_write_bandwidth; /* further smoothed write bw */
  78
  79         /*
  80          * The base dirty throttle rate, re-calculated on every 200ms.
  81          * All the bdi tasks' dirty rate will be curbed under it.
  82          * @dirty_ratelimit tracks the estimated @balanced_dirty_ratelimit
  83          * in small steps and is much more smooth/stable than the latter.
  84          */
  85         unsigned long dirty_ratelimit;
  86         unsigned long balanced_dirty_ratelimit;
  87
  88         struct fprop_local_percpu completions;
  89         int dirty_exceeded;
  90
  91         unsigned int min_ratio;
  92         unsigned int max_ratio, max_prop_frac;
  93
  94         struct bdi_writeback wb;  /* default writeback info for this bdi */
  95         spinlock_t wb_lock;       /* protects work_list & wb.dwork scheduling */
  96
  97         struct list_head work_list;
  98
  99         struct device *dev;
 100
 101         struct timer_list laptop_mode_wb_timer;
 102
 103 #ifdef CONFIG_DEBUG_FS
 104         struct dentry *debug_dir;
 105         struct dentry *debug_stats;
 106 #endif
 107 };
 108
 109 struct backing_dev_info *inode_to_bdi(struct inode *inode);
 110
 111 int __must_check bdi_init(struct backing_dev_info *bdi);
 112 void bdi_destroy(struct backing_dev_info *bdi);
 113
 114 __printf(3, 4)
 115 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
 116                 const char *fmt, ...);
 117 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
 118 void bdi_unregister(struct backing_dev_info *bdi);
 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 */