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/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 <asm/atomic.h>
  20
  21 struct page;
  22 struct device;
  23 struct dentry;
  24
  25 /*
  26  * Bits in backing_dev_info.state
  27  */
  28 enum bdi_state {
  29         BDI_pending,            /* On its way to being activated */
  30         BDI_wb_alloc,           /* Default embedded wb allocated */
  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_unused,             /* Available bits start here */
  35 };
  36
  37 typedef int (congested_fn)(void *, int);
  38
  39 enum bdi_stat_item {
  40         BDI_RECLAIMABLE,
  41         BDI_WRITEBACK,
  42         NR_BDI_STAT_ITEMS
  43 };
  44
  45 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
  46
  47 struct bdi_writeback {
  48         struct backing_dev_info *bdi;   /* our parent bdi */
  49         unsigned int nr;
  50
  51         unsigned long last_old_flush;   /* last old data flush */
  52         unsigned long last_active;      /* last time bdi thread was active */
  53
  54         struct task_struct *task;       /* writeback thread */
  55         struct timer_list wakeup_timer; /* used for delayed bdi thread wakeup */
  56         struct list_head b_dirty;       /* dirty inodes */
  57         struct list_head b_io;          /* parked for writeback */
  58         struct list_head b_more_io;     /* parked for more writeback */
  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         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 work_list */
  83
  84         struct list_head work_list;
  85
  86         struct device *dev;
  87
  88         struct timer_list laptop_mode_wb_timer;
  89
  90 #ifdef CONFIG_DEBUG_FS
  91         struct dentry *debug_dir;
  92         struct dentry *debug_stats;
  93 #endif
  94 };
  95
  96 int bdi_init(struct backing_dev_info *bdi);
  97 void bdi_destroy(struct backing_dev_info *bdi);
  98
  99 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
 100                 const char *fmt, ...);
 101 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
 102 void bdi_unregister(struct backing_dev_info *bdi);
 103 int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int);
 104 void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages);
 105 void bdi_start_background_writeback(struct backing_dev_info *bdi);
 106 int bdi_writeback_thread(void *data);
 107 int bdi_has_dirty_io(struct backing_dev_info *bdi);
 108 void bdi_arm_supers_timer(void);
 109 void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi);
 110
 111 extern spinlock_t bdi_lock;
 112 extern struct list_head bdi_list;
 113
 114 static inline int wb_has_dirty_io(struct bdi_writeback *wb)
 115 {
 116         return !list_empty(&wb->b_dirty) ||
 117                !list_empty(&wb->b_io) ||
 118                !list_empty(&wb->b_more_io);
 119 }
 120
 121 static inline void __add_bdi_stat(struct backing_dev_info *bdi,
 122                 enum bdi_stat_item item, s64 amount)
 123 {
 124         __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
 125 }
 126
 127 static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
 128                 enum bdi_stat_item item)
 129 {
 130         __add_bdi_stat(bdi, item, 1);
 131 }
 132
 133 static inline void inc_bdi_stat(struct backing_dev_info *bdi,
 134                 enum bdi_stat_item item)
 135 {
 136         unsigned long flags;
 137
 138         local_irq_save(flags);
 139         __inc_bdi_stat(bdi, item);
 140         local_irq_restore(flags);
 141 }
 142
 143 static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
 144                 enum bdi_stat_item item)
 145 {
 146         __add_bdi_stat(bdi, item, -1);
 147 }
 148
 149 static inline void dec_bdi_stat(struct backing_dev_info *bdi,
 150                 enum bdi_stat_item item)
 151 {
 152         unsigned long flags;
 153
 154         local_irq_save(flags);
 155         __dec_bdi_stat(bdi, item);
 156         local_irq_restore(flags);
 157 }
 158
 159 static inline s64 bdi_stat(struct backing_dev_info *bdi,
 160                 enum bdi_stat_item item)
 161 {
 162         return percpu_counter_read_positive(&bdi->bdi_stat[item]);
 163 }
 164
 165 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
 166                 enum bdi_stat_item item)
 167 {
 168         return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
 169 }
 170
 171 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
 172                 enum bdi_stat_item item)
 173 {
 174         s64 sum;
 175         unsigned long flags;
 176
 177         local_irq_save(flags);
 178         sum = __bdi_stat_sum(bdi, item);
 179         local_irq_restore(flags);
 180
 181         return sum;
 182 }
 183
 184 extern void bdi_writeout_inc(struct backing_dev_info *bdi);
 185
 186 /*
 187  * maximal error of a stat counter.
 188  */
 189 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
 190 {
 191 #ifdef CONFIG_SMP
 192         return nr_cpu_ids * BDI_STAT_BATCH;
 193 #else
 194         return 1;
 195 #endif
 196 }
 197
 198 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
 199 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
 200
 201 /*
 202  * Flags in backing_dev_info::capability
 203  *
 204  * The first three flags control whether dirty pages will contribute to the
 205  * VM's accounting and whether writepages() should be called for dirty pages
 206  * (something that would not, for example, be appropriate for ramfs)
 207  *
 208  * WARNING: these flags are closely related and should not normally be
 209  * used separately.  The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
 210  * three flags into a single convenience macro.
 211  *
 212  * BDI_CAP_NO_ACCT_DIRTY:  Dirty pages shouldn't contribute to accounting
 213  * BDI_CAP_NO_WRITEBACK:   Don't write pages back
 214  * BDI_CAP_NO_ACCT_WB:     Don't automatically account writeback pages
 215  *
 216  * These flags let !MMU mmap() govern direct device mapping vs immediate
 217  * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
 218  *
 219  * BDI_CAP_MAP_COPY:       Copy can be mapped (MAP_PRIVATE)
 220  * BDI_CAP_MAP_DIRECT:     Can be mapped directly (MAP_SHARED)
 221  * BDI_CAP_READ_MAP:       Can be mapped for reading
 222  * BDI_CAP_WRITE_MAP:      Can be mapped for writing
 223  * BDI_CAP_EXEC_MAP:       Can be mapped for execution
 224  *
 225  * BDI_CAP_SWAP_BACKED:    Count shmem/tmpfs objects as swap-backed.
 226  */
 227 #define BDI_CAP_NO_ACCT_DIRTY   0x00000001
 228 #define BDI_CAP_NO_WRITEBACK    0x00000002
 229 #define BDI_CAP_MAP_COPY        0x00000004
 230 #define BDI_CAP_MAP_DIRECT      0x00000008
 231 #define BDI_CAP_READ_MAP        0x00000010
 232 #define BDI_CAP_WRITE_MAP       0x00000020
 233 #define BDI_CAP_EXEC_MAP        0x00000040
 234 #define BDI_CAP_NO_ACCT_WB      0x00000080
 235 #define BDI_CAP_SWAP_BACKED     0x00000100
 236
 237 #define BDI_CAP_VMFLAGS \
 238         (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
 239
 240 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
 241         (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
 242
 243 #if defined(VM_MAYREAD) && \
 244         (BDI_CAP_READ_MAP != VM_MAYREAD || \
 245          BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
 246          BDI_CAP_EXEC_MAP != VM_MAYEXEC)
 247 #error please change backing_dev_info::capabilities flags
 248 #endif
 249
 250 extern struct backing_dev_info default_backing_dev_info;
 251 extern struct backing_dev_info noop_backing_dev_info;
 252 void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);
 253
 254 int writeback_in_progress(struct backing_dev_info *bdi);
 255
 256 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
 257 {
 258         if (bdi->congested_fn)
 259                 return bdi->congested_fn(bdi->congested_data, bdi_bits);
 260         return (bdi->state & bdi_bits);
 261 }
 262
 263 static inline int bdi_read_congested(struct backing_dev_info *bdi)
 264 {
 265         return bdi_congested(bdi, 1 << BDI_sync_congested);
 266 }
 267
 268 static inline int bdi_write_congested(struct backing_dev_info *bdi)
 269 {
 270         return bdi_congested(bdi, 1 << BDI_async_congested);
 271 }
 272
 273 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
 274 {
 275         return bdi_congested(bdi, (1 << BDI_sync_congested) |
 276                                   (1 << BDI_async_congested));
 277 }
 278
 279 enum {
 280         BLK_RW_ASYNC    = 0,
 281         BLK_RW_SYNC     = 1,
 282 };
 283
 284 void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
 285 void set_bdi_congested(struct backing_dev_info *bdi, int sync);
 286 long congestion_wait(int sync, long timeout);
 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 bdi_cap_swap_backed(struct backing_dev_info *bdi)
 307 {
 308         return bdi->capabilities & BDI_CAP_SWAP_BACKED;
 309 }
 310
 311 static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi)
 312 {
 313         return bdi == &default_backing_dev_info;
 314 }
 315
 316 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
 317 {
 318         return bdi_cap_writeback_dirty(mapping->backing_dev_info);
 319 }
 320
 321 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
 322 {
 323         return bdi_cap_account_dirty(mapping->backing_dev_info);
 324 }
 325
 326 static inline bool mapping_cap_swap_backed(struct address_space *mapping)
 327 {
 328         return bdi_cap_swap_backed(mapping->backing_dev_info);
 329 }
 330
 331 static inline int bdi_sched_wait(void *word)
 332 {
 333         schedule();
 334         return 0;
 335 }
 336
 337 static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
 338                                        struct page *page)
 339 {
 340         if (bdi && bdi->unplug_io_fn)
 341                 bdi->unplug_io_fn(bdi, page);
 342 }
 343
 344 static inline void blk_run_address_space(struct address_space *mapping)
 345 {
 346         if (mapping)
 347                 blk_run_backing_dev(mapping->backing_dev_info, NULL);
 348 }
 349
 350 #endif          /* _LINUX_BACKING_DEV_H */