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>
15 #include <asm/atomic.h>
21 * Bits in backing_dev_info.state
24 BDI_pdflush, /* A pdflush thread is working this device */
25 BDI_write_congested, /* The write queue is getting full */
26 BDI_read_congested, /* The read queue is getting full */
27 BDI_unused, /* Available bits start here */
30 typedef int (congested_fn)(void *, int);
38 #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids)))
40 struct backing_dev_info {
41 unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */
42 unsigned long state; /* Always use atomic bitops on this */
43 unsigned int capabilities; /* Device capabilities */
44 congested_fn *congested_fn; /* Function pointer if device is md/dm */
45 void *congested_data; /* Pointer to aux data for congested func */
46 void (*unplug_io_fn)(struct backing_dev_info *, struct page *);
49 struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS];
51 struct prop_local_percpu completions;
54 unsigned int min_ratio;
55 unsigned int max_ratio, max_prop_frac;
60 int bdi_init(struct backing_dev_info *bdi);
61 void bdi_destroy(struct backing_dev_info *bdi);
63 int bdi_register(struct backing_dev_info *bdi, struct device *parent,
64 const char *fmt, ...);
65 int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev);
66 void bdi_unregister(struct backing_dev_info *bdi);
68 static inline void __add_bdi_stat(struct backing_dev_info *bdi,
69 enum bdi_stat_item item, s64 amount)
71 __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH);
74 static inline void __inc_bdi_stat(struct backing_dev_info *bdi,
75 enum bdi_stat_item item)
77 __add_bdi_stat(bdi, item, 1);
80 static inline void inc_bdi_stat(struct backing_dev_info *bdi,
81 enum bdi_stat_item item)
85 local_irq_save(flags);
86 __inc_bdi_stat(bdi, item);
87 local_irq_restore(flags);
90 static inline void __dec_bdi_stat(struct backing_dev_info *bdi,
91 enum bdi_stat_item item)
93 __add_bdi_stat(bdi, item, -1);
96 static inline void dec_bdi_stat(struct backing_dev_info *bdi,
97 enum bdi_stat_item item)
101 local_irq_save(flags);
102 __dec_bdi_stat(bdi, item);
103 local_irq_restore(flags);
106 static inline s64 bdi_stat(struct backing_dev_info *bdi,
107 enum bdi_stat_item item)
109 return percpu_counter_read_positive(&bdi->bdi_stat[item]);
112 static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi,
113 enum bdi_stat_item item)
115 return percpu_counter_sum_positive(&bdi->bdi_stat[item]);
118 static inline s64 bdi_stat_sum(struct backing_dev_info *bdi,
119 enum bdi_stat_item item)
124 local_irq_save(flags);
125 sum = __bdi_stat_sum(bdi, item);
126 local_irq_restore(flags);
132 * maximal error of a stat counter.
134 static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi)
137 return nr_cpu_ids * BDI_STAT_BATCH;
143 int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
144 int bdi_set_max_ratio(struct backing_dev_info *bdi, unsigned int max_ratio);
147 * Flags in backing_dev_info::capability
148 * - The first two flags control whether dirty pages will contribute to the
149 * VM's accounting and whether writepages() should be called for dirty pages
150 * (something that would not, for example, be appropriate for ramfs)
151 * - These flags let !MMU mmap() govern direct device mapping vs immediate
152 * copying more easily for MAP_PRIVATE, especially for ROM filesystems
154 #define BDI_CAP_NO_ACCT_DIRTY 0x00000001 /* Dirty pages shouldn't contribute to accounting */
155 #define BDI_CAP_NO_WRITEBACK 0x00000002 /* Don't write pages back */
156 #define BDI_CAP_MAP_COPY 0x00000004 /* Copy can be mapped (MAP_PRIVATE) */
157 #define BDI_CAP_MAP_DIRECT 0x00000008 /* Can be mapped directly (MAP_SHARED) */
158 #define BDI_CAP_READ_MAP 0x00000010 /* Can be mapped for reading */
159 #define BDI_CAP_WRITE_MAP 0x00000020 /* Can be mapped for writing */
160 #define BDI_CAP_EXEC_MAP 0x00000040 /* Can be mapped for execution */
161 #define BDI_CAP_VMFLAGS \
162 (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP)
164 #if defined(VM_MAYREAD) && \
165 (BDI_CAP_READ_MAP != VM_MAYREAD || \
166 BDI_CAP_WRITE_MAP != VM_MAYWRITE || \
167 BDI_CAP_EXEC_MAP != VM_MAYEXEC)
168 #error please change backing_dev_info::capabilities flags
171 extern struct backing_dev_info default_backing_dev_info;
172 void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page);
174 int writeback_in_progress(struct backing_dev_info *bdi);
176 static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits)
178 if (bdi->congested_fn)
179 return bdi->congested_fn(bdi->congested_data, bdi_bits);
180 return (bdi->state & bdi_bits);
183 static inline int bdi_read_congested(struct backing_dev_info *bdi)
185 return bdi_congested(bdi, 1 << BDI_read_congested);
188 static inline int bdi_write_congested(struct backing_dev_info *bdi)
190 return bdi_congested(bdi, 1 << BDI_write_congested);
193 static inline int bdi_rw_congested(struct backing_dev_info *bdi)
195 return bdi_congested(bdi, (1 << BDI_read_congested)|
196 (1 << BDI_write_congested));
199 void clear_bdi_congested(struct backing_dev_info *bdi, int rw);
200 void set_bdi_congested(struct backing_dev_info *bdi, int rw);
201 long congestion_wait(int rw, long timeout);
203 #define bdi_cap_writeback_dirty(bdi) \
204 (!((bdi)->capabilities & BDI_CAP_NO_WRITEBACK))
206 #define bdi_cap_account_dirty(bdi) \
207 (!((bdi)->capabilities & BDI_CAP_NO_ACCT_DIRTY))
209 #define mapping_cap_writeback_dirty(mapping) \
210 bdi_cap_writeback_dirty((mapping)->backing_dev_info)
212 #define mapping_cap_account_dirty(mapping) \
213 bdi_cap_account_dirty((mapping)->backing_dev_info)
216 #endif /* _LINUX_BACKING_DEV_H */