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_writeback_running,  /* Writeback is in progress */
  35         BDI_unused,             /* Available bits start here */
  36 };
  37
  38 typedef int (congested_fn)(void *, int);
  39
  40 enum bdi_stat_item {
  41         BDI_RECLAIMABLE,
  42         BDI_WRITEBACK,
  43         NR_BDI_STAT_ITEMS
  44 };
  45
  46 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
  47
  48 struct bdi_writeback {
  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         unsigned long last_active;      /* last time bdi thread was active */
  54
  55         struct task_struct *task;       /* writeback thread */
  56         struct timer_list wakeup_timer; /* used for delayed bdi thread wakeup */
  57         struct list_head b_dirty;       /* dirty inodes */
  58         struct list_head b_io;          /* parked for writeback */
  59         struct list_head b_more_io;     /* parked for more writeback */
  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         void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
  70         void *unplug_io_data;
  71
  72         char *name;
  73
  74         struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
  75
  76         struct prop_local_percpu completions;
  77         int dirty_exceeded;
  78
  79         unsigned int min_ratio;
  80         unsigned int max_ratio, max_prop_frac;
  81
  82         struct bdi_writeback wb;  /* default writeback info for this bdi */
  83         spinlock_t wb_lock;       /* protects work_list */
  84
  85         struct list_head work_list;
  86
  87         struct device *dev;
  88
  89         struct timer_list laptop_mode_wb_timer;
  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 int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int);
 105 void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages);
 106 void bdi_start_background_writeback(struct backing_dev_info *bdi);
 107 int bdi_writeback_thread(void *data);
 108 int bdi_has_dirty_io(struct backing_dev_info *bdi);
 109 void bdi_arm_supers_timer(void);
 110 void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi);
 111
 112 extern spinlock_t bdi_lock;
 113 extern struct list_head bdi_list;
 114
 115 static inline int wb_has_dirty_io(struct bdi_writeback *wb)
 116 {
 117         return !list_empty(&wb->b_dirty) ||
 118                !list_empty(&wb->b_io) ||
 119                !list_empty(&wb->b_more_io);
 120 }
 121
 122 static inline void __add_bdi_stat(struct backing_dev_info *bdi,
 123                 enum bdi_stat_item item, s64 amount)
 124 {
 125         __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
 126 }
 127
 128 static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
 129                 enum bdi_stat_item item)
 130 {
 131         __add_bdi_stat(bdi, item, 1);
 132 }
 133
 134 static inline void inc_bdi_stat(struct backing_dev_info *bdi,
 135                 enum bdi_stat_item item)
 136 {
 137         unsigned long flags;
 138
 139         local_irq_save(flags);
 140         __inc_bdi_stat(bdi, item);
 141         local_irq_restore(flags);
 142 }
 143
 144 static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
 145                 enum bdi_stat_item item)
 146 {
 147         __add_bdi_stat(bdi, item, -1);
 148 }
 149
 150 static inline void dec_bdi_stat(struct backing_dev_info *bdi,
 151                 enum bdi_stat_item item)
 152 {
 153         unsigned long flags;
 154
 155         local_irq_save(flags);
 156         __dec_bdi_stat(bdi, item);
 157         local_irq_restore(flags);
 158 }
 159
 160 static inline s64 bdi_stat(struct backing_dev_info *bdi,
 161                 enum bdi_stat_item item)
 162 {
 163         return percpu_counter_read_positive(&bdi->bdi_stat[item]);
 164 }
 165
 166 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
 167                 enum bdi_stat_item item)
 168 {
 169         return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
 170 }
 171
 172 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
 173                 enum bdi_stat_item item)
 174 {
 175         s64 sum;
 176         unsigned long flags;
 177
 178         local_irq_save(flags);
 179         sum = __bdi_stat_sum(bdi, item);
 180         local_irq_restore(flags);
 181
 182         return sum;
 183 }
 184
 185 extern void bdi_writeout_inc(struct backing_dev_info *bdi);
 186
 187 /*
 188  * maximal error of a stat counter.
 189  */
 190 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
 191 {
 192 #ifdef CONFIG_SMP
 193         return nr_cpu_ids * BDI_STAT_BATCH;
 194 #else
 195         return 1;
 196 #endif
 197 }
 198
 199 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
 200 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
 201
 202 /*
 203  * Flags in backing_dev_info::capability
 204  *
 205  * The first three flags control whether dirty pages will contribute to the
 206  * VM's accounting and whether writepages() should be called for dirty pages
 207  * (something that would not, for example, be appropriate for ramfs)
 208  *
 209  * WARNING: these flags are closely related and should not normally be
 210  * used separately.  The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
 211  * three flags into a single convenience macro.
 212  *
 213  * BDI_CAP_NO_ACCT_DIRTY:  Dirty pages shouldn't contribute to accounting
 214  * BDI_CAP_NO_WRITEBACK:   Don't write pages back
 215  * BDI_CAP_NO_ACCT_WB:     Don't automatically account writeback pages
 216  *
 217  * These flags let !MMU mmap() govern direct device mapping vs immediate
 218  * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
 219  *
 220  * BDI_CAP_MAP_COPY:       Copy can be mapped (MAP_PRIVATE)
 221  * BDI_CAP_MAP_DIRECT:     Can be mapped directly (MAP_SHARED)
 222  * BDI_CAP_READ_MAP:       Can be mapped for reading
 223  * BDI_CAP_WRITE_MAP:      Can be mapped for writing
 224  * BDI_CAP_EXEC_MAP:       Can be mapped for execution
 225  *
 226  * BDI_CAP_SWAP_BACKED:    Count shmem/tmpfs objects as swap-backed.
 227  */
 228 #define BDI_CAP_NO_ACCT_DIRTY   0x00000001
 229 #define BDI_CAP_NO_WRITEBACK    0x00000002
 230 #define BDI_CAP_MAP_COPY        0x00000004
 231 #define BDI_CAP_MAP_DIRECT      0x00000008
 232 #define BDI_CAP_READ_MAP        0x00000010
 233 #define BDI_CAP_WRITE_MAP       0x00000020
 234 #define BDI_CAP_EXEC_MAP        0x00000040
 235 #define BDI_CAP_NO_ACCT_WB      0x00000080
 236 #define BDI_CAP_SWAP_BACKED     0x00000100
 237
 238 #define BDI_CAP_VMFLAGS \
 239         (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
 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 #if defined(VM_MAYREAD) && \
 245         (BDI_CAP_READ_MAP != VM_MAYREAD || \
 246          BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
 247          BDI_CAP_EXEC_MAP != VM_MAYEXEC)
 248 #error please change backing_dev_info::capabilities flags
 249 #endif
 250
 251 extern struct backing_dev_info default_backing_dev_info;
 252 extern struct backing_dev_info noop_backing_dev_info;
 253 void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);
 254
 255 int writeback_in_progress(struct backing_dev_info *bdi);
 256
 257 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
 258 {
 259         if (bdi->congested_fn)
 260                 return bdi->congested_fn(bdi->congested_data, bdi_bits);
 261         return (bdi->state & bdi_bits);
 262 }
 263
 264 static inline int bdi_read_congested(struct backing_dev_info *bdi)
 265 {
 266         return bdi_congested(bdi, 1 << BDI_sync_congested);
 267 }
 268
 269 static inline int bdi_write_congested(struct backing_dev_info *bdi)
 270 {
 271         return bdi_congested(bdi, 1 << BDI_async_congested);
 272 }
 273
 274 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
 275 {
 276         return bdi_congested(bdi, (1 << BDI_sync_congested) |
 277                                   (1 << BDI_async_congested));
 278 }
 279
 280 enum {
 281         BLK_RW_ASYNC    = 0,
 282         BLK_RW_SYNC     = 1,
 283 };
 284
 285 void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
 286 void set_bdi_congested(struct backing_dev_info *bdi, int sync);
 287 long congestion_wait(int sync, long timeout);
 288
 289
 290 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
 291 {
 292         return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
 293 }
 294
 295 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
 296 {
 297         return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
 298 }
 299
 300 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
 301 {
 302         /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
 303         return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
 304                                       BDI_CAP_NO_WRITEBACK));
 305 }
 306
 307 static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
 308 {
 309         return bdi->capabilities & BDI_CAP_SWAP_BACKED;
 310 }
 311
 312 static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi)
 313 {
 314         return bdi == &default_backing_dev_info;
 315 }
 316
 317 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
 318 {
 319         return bdi_cap_writeback_dirty(mapping->backing_dev_info);
 320 }
 321
 322 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
 323 {
 324         return bdi_cap_account_dirty(mapping->backing_dev_info);
 325 }
 326
 327 static inline bool mapping_cap_swap_backed(struct address_space *mapping)
 328 {
 329         return bdi_cap_swap_backed(mapping->backing_dev_info);
 330 }
 331
 332 static inline int bdi_sched_wait(void *word)
 333 {
 334         schedule();
 335         return 0;
 336 }
 337
 338 static inline void blk_run_backing_dev(struct backing_dev_info *bdi,
 339                                        struct page *page)
 340 {
 341         if (bdi && bdi->unplug_io_fn)
 342                 bdi->unplug_io_fn(bdi, page);
 343 }
 344
 345 static inline void blk_run_address_space(struct address_space *mapping)
 346 {
 347         if (mapping)
 348                 blk_run_backing_dev(mapping->backing_dev_info, NULL);
 349 }
 350
 351 #endif          /* _LINUX_BACKING_DEV_H */