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 <asm/atomic.h>
23 * Bits in backing_dev_info.state
26 BDI_pdflush, /* A pdflush thread is working this device */
27 BDI_async_congested, /* The async (write) queue is getting full */
28 BDI_sync_congested, /* The sync queue is getting full */
29 BDI_unused, /* Available bits start here */
32 typedef int (congested_fn)(void *, int);
40 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
42 struct backing_dev_info {
43 struct list_head bdi_list;
45 unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
46 unsigned long state; /* Always use atomic bitops on this */
47 unsigned int capabilities; /* Device capabilities */
48 congested_fn *congested_fn; /* Function pointer if device is md/dm */
49 void *congested_data; /* Pointer to aux data for congested func */
50 void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
53 struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
55 struct prop_local_percpu completions;
58 unsigned int min_ratio;
59 unsigned int max_ratio, max_prop_frac;
63 struct list_head b_dirty; /* dirty inodes */
64 struct list_head b_io; /* parked for writeback */
65 struct list_head b_more_io; /* parked for more writeback */
67 #ifdef CONFIG_DEBUG_FS
68 struct dentry *debug_dir;
69 struct dentry *debug_stats;
73 int bdi_init(struct backing_dev_info *bdi);
74 void bdi_destroy(struct backing_dev_info *bdi);
76 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
77 const char *fmt, ...);
78 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
79 void bdi_unregister(struct backing_dev_info *bdi);
81 extern struct mutex bdi_lock;
82 extern struct list_head bdi_list;
84 static inline void __add_bdi_stat(struct backing_dev_info *bdi,
85 enum bdi_stat_item item, s64 amount)
87 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
90 static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
91 enum bdi_stat_item item)
93 __add_bdi_stat(bdi, item, 1);
96 static inline void inc_bdi_stat(struct backing_dev_info *bdi,
97 enum bdi_stat_item item)
101 local_irq_save(flags);
102 __inc_bdi_stat(bdi, item);
103 local_irq_restore(flags);
106 static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
107 enum bdi_stat_item item)
109 __add_bdi_stat(bdi, item, -1);
112 static inline void dec_bdi_stat(struct backing_dev_info *bdi,
113 enum bdi_stat_item item)
117 local_irq_save(flags);
118 __dec_bdi_stat(bdi, item);
119 local_irq_restore(flags);
122 static inline s64 bdi_stat(struct backing_dev_info *bdi,
123 enum bdi_stat_item item)
125 return percpu_counter_read_positive(&bdi->bdi_stat[item]);
128 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
129 enum bdi_stat_item item)
131 return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
134 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
135 enum bdi_stat_item item)
140 local_irq_save(flags);
141 sum = __bdi_stat_sum(bdi, item);
142 local_irq_restore(flags);
147 extern void bdi_writeout_inc(struct backing_dev_info *bdi);
150 * maximal error of a stat counter.
152 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
155 return nr_cpu_ids * BDI_STAT_BATCH;
161 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
162 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
165 * Flags in backing_dev_info::capability
167 * The first three flags control whether dirty pages will contribute to the
168 * VM's accounting and whether writepages() should be called for dirty pages
169 * (something that would not, for example, be appropriate for ramfs)
171 * WARNING: these flags are closely related and should not normally be
172 * used separately. The BDI_CAP_NO_ACCT_AND_WRITEBACK combines these
173 * three flags into a single convenience macro.
175 * BDI_CAP_NO_ACCT_DIRTY: Dirty pages shouldn't contribute to accounting
176 * BDI_CAP_NO_WRITEBACK: Don't write pages back
177 * BDI_CAP_NO_ACCT_WB: Don't automatically account writeback pages
179 * These flags let !MMU mmap() govern direct device mapping vs immediate
180 * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
182 * BDI_CAP_MAP_COPY: Copy can be mapped (MAP_PRIVATE)
183 * BDI_CAP_MAP_DIRECT: Can be mapped directly (MAP_SHARED)
184 * BDI_CAP_READ_MAP: Can be mapped for reading
185 * BDI_CAP_WRITE_MAP: Can be mapped for writing
186 * BDI_CAP_EXEC_MAP: Can be mapped for execution
188 * BDI_CAP_SWAP_BACKED: Count shmem/tmpfs objects as swap-backed.
190 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001
191 #define BDI_CAP_NO_WRITEBACK 0x00000002
192 #define BDI_CAP_MAP_COPY 0x00000004
193 #define BDI_CAP_MAP_DIRECT 0x00000008
194 #define BDI_CAP_READ_MAP 0x00000010
195 #define BDI_CAP_WRITE_MAP 0x00000020
196 #define BDI_CAP_EXEC_MAP 0x00000040
197 #define BDI_CAP_NO_ACCT_WB 0x00000080
198 #define BDI_CAP_SWAP_BACKED 0x00000100
200 #define BDI_CAP_VMFLAGS \
201 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
203 #define BDI_CAP_NO_ACCT_AND_WRITEBACK \
204 (BDI_CAP_NO_WRITEBACK | BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_ACCT_WB)
206 #if defined(VM_MAYREAD) && \
207 (BDI_CAP_READ_MAP != VM_MAYREAD || \
208 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
209 BDI_CAP_EXEC_MAP != VM_MAYEXEC)
210 #error please change backing_dev_info::capabilities flags
213 extern struct backing_dev_info default_backing_dev_info;
214 void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);
216 int writeback_in_progress(struct backing_dev_info *bdi);
218 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
220 if (bdi->congested_fn)
221 return bdi->congested_fn(bdi->congested_data, bdi_bits);
222 return (bdi->state & bdi_bits);
225 static inline int bdi_read_congested(struct backing_dev_info *bdi)
227 return bdi_congested(bdi, 1 << BDI_sync_congested);
230 static inline int bdi_write_congested(struct backing_dev_info *bdi)
232 return bdi_congested(bdi, 1 << BDI_async_congested);
235 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
237 return bdi_congested(bdi, (1 << BDI_sync_congested) |
238 (1 << BDI_async_congested));
246 void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
247 void set_bdi_congested(struct backing_dev_info *bdi, int sync);
248 long congestion_wait(int sync, long timeout);
251 static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
253 return !(bdi->capabilities & BDI_CAP_NO_WRITEBACK);
256 static inline bool bdi_cap_account_dirty(struct backing_dev_info *bdi)
258 return !(bdi->capabilities & BDI_CAP_NO_ACCT_DIRTY);
261 static inline bool bdi_cap_account_writeback(struct backing_dev_info *bdi)
263 /* Paranoia: BDI_CAP_NO_WRITEBACK implies BDI_CAP_NO_ACCT_WB */
264 return !(bdi->capabilities & (BDI_CAP_NO_ACCT_WB |
265 BDI_CAP_NO_WRITEBACK));
268 static inline bool bdi_cap_swap_backed(struct backing_dev_info *bdi)
270 return bdi->capabilities & BDI_CAP_SWAP_BACKED;
273 static inline bool mapping_cap_writeback_dirty(struct address_space *mapping)
275 return bdi_cap_writeback_dirty(mapping->backing_dev_info);
278 static inline bool mapping_cap_account_dirty(struct address_space *mapping)
280 return bdi_cap_account_dirty(mapping->backing_dev_info);
283 static inline bool mapping_cap_swap_backed(struct address_space *mapping)
285 return bdi_cap_swap_backed(mapping->backing_dev_info);
288 #endif /* _LINUX_BACKING_DEV_H */