2 * include/linux/backing-dev.h
4 * low-level device information and state which is propagated up through
8 #ifndef _LINUX_BACKING_DEV_H
9 #define _LINUX_BACKING_DEV_H
11 #include <linux/percpu_counter.h>
12 #include <linux/log2.h>
13 #include <linux/proportions.h>
14 #include <linux/kernel.h>
16 #include <linux/sched.h>
17 #include <linux/writeback.h>
18 #include <asm/atomic.h>
25 * Bits in backing_dev_info.state
28 BDI_pending, /* On its way to being activated */
29 BDI_wb_alloc, /* Default embedded wb allocated */
30 BDI_async_congested, /* The async (write) queue is getting full */
31 BDI_sync_congested, /* The sync queue is getting full */
32 BDI_unused, /* Available bits start here */
35 typedef int (congested_fn)(void *, int);
43 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
45 struct bdi_writeback {
46 struct list_head list; /* hangs off the bdi */
48 struct backing_dev_info *bdi; /* our parent bdi */
51 unsigned long last_old_flush; /* last old data flush */
53 struct task_struct *task; /* writeback task */
54 struct list_head b_dirty; /* dirty inodes */
55 struct list_head b_io; /* parked for writeback */
56 struct list_head b_more_io; /* parked for more writeback */
59 struct backing_dev_info {
60 struct list_head bdi_list;
61 unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
62 unsigned long state; /* Always use atomic bitops on this */
63 unsigned int capabilities; /* Device capabilities */
64 congested_fn *congested_fn; /* Function pointer if device is md/dm */
65 void *congested_data; /* Pointer to aux data for congested func */
66 void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
69 struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
71 struct prop_local_percpu completions;
74 unsigned int min_ratio;
75 unsigned int max_ratio, max_prop_frac;
77 struct bdi_writeback wb; /* default writeback info for this bdi */
78 spinlock_t wb_lock; /* protects update side of wb_list */
79 struct list_head wb_list; /* the flusher threads hanging off this bdi */
80 unsigned long wb_mask; /* bitmask of registered tasks */
81 unsigned int wb_cnt; /* number of registered tasks */
83 struct list_head work_list;
87 #ifdef CONFIG_DEBUG_FS
88 struct dentry *debug_dir;
89 struct dentry *debug_stats;
93 int bdi_init(struct backing_dev_info *bdi);
94 void bdi_destroy(struct backing_dev_info *bdi);
96 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
97 const char *fmt, ...);
98 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
99 void bdi_unregister(struct backing_dev_info *bdi);
100 void bdi_start_writeback(struct writeback_control *wbc);
101 int bdi_writeback_task(struct bdi_writeback *wb);
102 int bdi_has_dirty_io(struct backing_dev_info *bdi);
104 extern spinlock_t bdi_lock;
105 extern struct list_head bdi_list;
107 static inline int wb_has_dirty_io(struct bdi_writeback *wb)
109 return !list_empty(&wb->b_dirty) ||
110 !list_empty(&wb->b_io) ||
111 !list_empty(&wb->b_more_io);
114 static inline void __add_bdi_stat(struct backing_dev_info *bdi,
115 enum bdi_stat_item item, s64 amount)
117 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
120 static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
121 enum bdi_stat_item item)
123 __add_bdi_stat(bdi, item, 1);
126 static inline void inc_bdi_stat(struct backing_dev_info *bdi,
127 enum bdi_stat_item item)
131 local_irq_save(flags);
132 __inc_bdi_stat(bdi, item);
133 local_irq_restore(flags);
136 static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
137 enum bdi_stat_item item)
139 __add_bdi_stat(bdi, item, -1);
142 static inline void dec_bdi_stat(struct backing_dev_info *bdi,
143 enum bdi_stat_item item)
147 local_irq_save(flags);
148 __dec_bdi_stat(bdi, item);
149 local_irq_restore(flags);
152 static inline s64 bdi_stat(struct backing_dev_info *bdi,
153 enum bdi_stat_item item)
155 return percpu_counter_read_positive(&bdi->bdi_stat[item]);
158 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
159 enum bdi_stat_item item)
161 return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
164 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
165 enum bdi_stat_item item)
170 local_irq_save(flags);
171 sum = __bdi_stat_sum(bdi, item);
172 local_irq_restore(flags);
177 extern void bdi_writeout_inc(struct backing_dev_info *bdi);
180 * maximal error of a stat counter.
182 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
185 return nr_cpu_ids * BDI_STAT_BATCH;
191 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
192 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
195 * Flags in backing_dev_info::capability
197 * The first three flags control whether dirty pages will contribute to the
198 * VM's accounting and whether writepages() should be called for dirty pages
199 * (something that would not, for example, be appropriate for ramfs)
201 * WARNING: these flags are closely related and should not normally be
202 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
203 * three flags into a single convenience macro.
205 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
206 * BDI_CAP_NO_WRITEBACK: Don't write pages back
207 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
209 * These flags let !MMU mmap() govern direct device mapping vs immediate
210 * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
212 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE)
213 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED)
214 * BDI_CAP_READ_MAP: Can be mapped for reading
215 * BDI_CAP_WRITE_MAP: Can be mapped for writing
216 * BDI_CAP_EXEC_MAP: Can be mapped for execution
218 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed.
220 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
221 #define BDI_CAP_NO_WRITEBACK 0x00000002
222 #define BDI_CAP_MAP_COPY 0x00000004
223 #define BDI_CAP_MAP_DIRECT 0x00000008
224 #define BDI_CAP_READ_MAP 0x00000010
225 #define BDI_CAP_WRITE_MAP 0x00000020
226 #define BDI_CAP_EXEC_MAP 0x00000040
227 #define BDI_CAP_NO_ACCT_WB 0x00000080
228 #define BDI_CAP_SWAP_BACKED 0x00000100
230 #define BDI_CAP_VMFLAGS \
231 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
233 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
234 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
236 #if defined(VM_MAYREAD) && \
237 (BDI_CAP_READ_MAP != VM_MAYREAD || \
238 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
239 BDI_CAP_EXEC_MAP != VM_MAYEXEC)
240 #error please change backing_dev_info::capabilities flags
243 extern struct backing_dev_info default_backing_dev_info;
244 void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);
246 int writeback_in_progress(struct backing_dev_info *bdi);
248 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
250 if (bdi->congested_fn)
251 return bdi->congested_fn(bdi->congested_data, bdi_bits);
252 return (bdi->state & bdi_bits);
255 static inline int bdi_read_congested(struct backing_dev_info *bdi)
257 return bdi_congested(bdi, 1 << BDI_sync_congested);
260 static inline int bdi_write_congested(struct backing_dev_info *bdi)
262 return bdi_congested(bdi, 1 << BDI_async_congested);
265 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
267 return bdi_congested(bdi, (1 << BDI_sync_congested) |
268 (1 << BDI_async_congested));
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);
281 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
283 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
286 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
288 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
291 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
293 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
294 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
295 BDI_CAP_NO_WRITEBACK));
298 static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
300 return bdi->capabilities & BDI_CAP_SWAP_BACKED;
303 static inline bool bdi_cap_flush_forker(struct backing_dev_info *bdi)
305 return bdi == &default_backing_dev_info;
308 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
310 return bdi_cap_writeback_dirty(mapping->backing_dev_info);
313 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
315 return bdi_cap_account_dirty(mapping->backing_dev_info);
318 static inline bool mapping_cap_swap_backed(struct address_space *mapping)
320 return bdi_cap_swap_backed(mapping->backing_dev_info);
323 static inline int bdi_sched_wait(void *word)
329 #endif /* _LINUX_BACKING_DEV_H */