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 21struct page; 22struct device; 23struct dentry; 24 25/* 26 * Bits in backing_dev_info.state 27 */ 28enum 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 38typedef int (congested_fn)(void *, int); 39 40enum 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 48struct 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 62struct 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 97int bdi_init(struct backing_dev_info *bdi); 98void bdi_destroy(struct backing_dev_info *bdi); 99 100int bdi_register(struct backing_dev_info *bdi, struct device *parent, 101 const char *fmt, ...); 102int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev); 103void bdi_unregister(struct backing_dev_info *bdi); 104int bdi_setup_and_register(struct backing_dev_info *, char *, unsigned int); 105void bdi_start_writeback(struct backing_dev_info *bdi, long nr_pages); 106void bdi_start_background_writeback(struct backing_dev_info *bdi); 107int bdi_writeback_thread(void *data); 108int bdi_has_dirty_io(struct backing_dev_info *bdi); 109void bdi_arm_supers_timer(void); 110void bdi_wakeup_thread_delayed(struct backing_dev_info *bdi); 111 112extern spinlock_t bdi_lock; 113extern struct list_head bdi_list; 114 115static 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 122static 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 128static 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 134static 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 144static 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 150static 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 160static 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 166static 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 172static 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 185extern void bdi_writeout_inc(struct backing_dev_info *bdi); 186 187/* 188 * maximal error of a stat counter. 189 */ 190static 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 199int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio); 200int 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) && (BDI_CAP_READ_MAP != VM_MAYREAD || BDI_CAP_WRITE_MAP != \ 245 VM_MAYWRITE || BDI_CAP_EXEC_MAP != VM_MAYEXEC) 246#error please change backing_dev_info::capabilities flags 247#endif 248 249extern struct backing_dev_info default_backing_dev_info; 250extern struct backing_dev_info noop_backing_dev_info; 251void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page); 252 253int writeback_in_progress(struct backing_dev_info *bdi); 254 255static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits) 256{ 257 if (bdi->congested_fn) 258 return bdi->congested_fn(bdi->congested_data, bdi_bits); 259 return (bdi->state & bdi_bits); 260} 261 262static inline int bdi_read_congested(struct backing_dev_info *bdi) 263{ 264 return bdi_congested(bdi, 1 << BDI_sync_congested); 265} 266 267static inline int bdi_write_congested(struct backing_dev_info *bdi) 268{ 269 return bdi_congested(bdi, 1 << BDI_async_congested); 270} 271 272static inline int bdi_rw_congested(struct backing_dev_info *bdi) 273{ 274 return bdi_congested(bdi, (1 << BDI_sync_congested) | 275 (1 << BDI_async_congested)); 276} 277 278enum { 279 BLK_RW_ASYNC = 0, 280 BLK_RW_SYNC = 1, 281}; 282 283void clear_bdi_congested(struct backing_dev_info *bdi, int sync); 284void set_bdi_congested(struct backing_dev_info *bdi, int sync); 285long congestion_wait(int sync, long timeout); 286 287 288static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi) 289{ 290 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK); 291} 292 293static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi) 294{ 295 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY); 296} 297 298static 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 305static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi) 306{ 307 return bdi->capabilities & BDI_CAP_SWAP_BACKED; 308} 309 310static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi) 311{ 312 return bdi == &default_backing_dev_info; 313} 314 315static inline bool mapping_cap_writeback_dirty(struct address_space *mapping) 316{ 317 return bdi_cap_writeback_dirty(mapping->backing_dev_info); 318} 319 320static inline bool mapping_cap_account_dirty(struct address_space *mapping) 321{ 322 return bdi_cap_account_dirty(mapping->backing_dev_info); 323} 324 325static inline bool mapping_cap_swap_backed(struct address_space *mapping) 326{ 327 return bdi_cap_swap_backed(mapping->backing_dev_info); 328} 329 330static inline int bdi_sched_wait(void *word) 331{ 332 schedule(); 333 return 0; 334} 335 336static inline void blk_run_backing_dev(struct backing_dev_info *bdi, 337 struct page *page) 338{ 339 if (bdi && bdi->unplug_io_fn) 340 bdi->unplug_io_fn(bdi, page); 341} 342 343static inline void blk_run_address_space(struct address_space *mapping) 344{ 345 if (mapping) 346 blk_run_backing_dev(mapping->backing_dev_info, NULL); 347} 348 349#endif /* _LINUX_BACKING_DEV_H */ 350