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1da177e4 LT |
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 | ||
b2e8fb6e PZ |
11 | #include <linux/percpu_counter.h> |
12 | #include <linux/log2.h> | |
04fbfdc1 | 13 | #include <linux/proportions.h> |
cf0ca9fe | 14 | #include <linux/kernel.h> |
1da177e4 LT |
15 | #include <asm/atomic.h> |
16 | ||
3fcfab16 | 17 | struct page; |
cf0ca9fe | 18 | struct device; |
3fcfab16 | 19 | |
1da177e4 LT |
20 | /* |
21 | * Bits in backing_dev_info.state | |
22 | */ | |
23 | enum bdi_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 */ | |
28 | }; | |
29 | ||
30 | typedef int (congested_fn)(void *, int); | |
31 | ||
b2e8fb6e | 32 | enum bdi_stat_item { |
c9e51e41 | 33 | BDI_RECLAIMABLE, |
69cb51d1 | 34 | BDI_WRITEBACK, |
b2e8fb6e PZ |
35 | NR_BDI_STAT_ITEMS |
36 | }; | |
37 | ||
38 | #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids))) | |
39 | ||
1da177e4 LT |
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 *); | |
47 | void *unplug_io_data; | |
b2e8fb6e PZ |
48 | |
49 | struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS]; | |
04fbfdc1 PZ |
50 | |
51 | struct prop_local_percpu completions; | |
52 | int dirty_exceeded; | |
cf0ca9fe PZ |
53 | |
54 | struct device *dev; | |
1da177e4 LT |
55 | }; |
56 | ||
b2e8fb6e PZ |
57 | int bdi_init(struct backing_dev_info *bdi); |
58 | void bdi_destroy(struct backing_dev_info *bdi); | |
59 | ||
cf0ca9fe PZ |
60 | int bdi_register(struct backing_dev_info *bdi, struct device *parent, |
61 | const char *fmt, ...); | |
62 | int bdi_register_dev(struct backing_dev_info *bdi, dev_t dev); | |
63 | void bdi_unregister(struct backing_dev_info *bdi); | |
64 | ||
b2e8fb6e PZ |
65 | static inline void __add_bdi_stat(struct backing_dev_info *bdi, |
66 | enum bdi_stat_item item, s64 amount) | |
67 | { | |
68 | __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH); | |
69 | } | |
70 | ||
71 | static inline void __inc_bdi_stat(struct backing_dev_info *bdi, | |
72 | enum bdi_stat_item item) | |
73 | { | |
74 | __add_bdi_stat(bdi, item, 1); | |
75 | } | |
76 | ||
77 | static inline void inc_bdi_stat(struct backing_dev_info *bdi, | |
78 | enum bdi_stat_item item) | |
79 | { | |
80 | unsigned long flags; | |
81 | ||
82 | local_irq_save(flags); | |
83 | __inc_bdi_stat(bdi, item); | |
84 | local_irq_restore(flags); | |
85 | } | |
86 | ||
87 | static inline void __dec_bdi_stat(struct backing_dev_info *bdi, | |
88 | enum bdi_stat_item item) | |
89 | { | |
90 | __add_bdi_stat(bdi, item, -1); | |
91 | } | |
92 | ||
93 | static inline void dec_bdi_stat(struct backing_dev_info *bdi, | |
94 | enum bdi_stat_item item) | |
95 | { | |
96 | unsigned long flags; | |
97 | ||
98 | local_irq_save(flags); | |
99 | __dec_bdi_stat(bdi, item); | |
100 | local_irq_restore(flags); | |
101 | } | |
102 | ||
103 | static inline s64 bdi_stat(struct backing_dev_info *bdi, | |
104 | enum bdi_stat_item item) | |
105 | { | |
106 | return percpu_counter_read_positive(&bdi->bdi_stat[item]); | |
107 | } | |
108 | ||
109 | static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi, | |
110 | enum bdi_stat_item item) | |
111 | { | |
112 | return percpu_counter_sum_positive(&bdi->bdi_stat[item]); | |
113 | } | |
114 | ||
115 | static inline s64 bdi_stat_sum(struct backing_dev_info *bdi, | |
116 | enum bdi_stat_item item) | |
e0bf68dd | 117 | { |
b2e8fb6e PZ |
118 | s64 sum; |
119 | unsigned long flags; | |
120 | ||
121 | local_irq_save(flags); | |
122 | sum = __bdi_stat_sum(bdi, item); | |
123 | local_irq_restore(flags); | |
124 | ||
125 | return sum; | |
e0bf68dd PZ |
126 | } |
127 | ||
b2e8fb6e PZ |
128 | /* |
129 | * maximal error of a stat counter. | |
130 | */ | |
131 | static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi) | |
e0bf68dd | 132 | { |
b2e8fb6e PZ |
133 | #ifdef CONFIG_SMP |
134 | return nr_cpu_ids * BDI_STAT_BATCH; | |
135 | #else | |
136 | return 1; | |
137 | #endif | |
e0bf68dd | 138 | } |
1da177e4 LT |
139 | |
140 | /* | |
141 | * Flags in backing_dev_info::capability | |
142 | * - The first two flags control whether dirty pages will contribute to the | |
143 | * VM's accounting and whether writepages() should be called for dirty pages | |
144 | * (something that would not, for example, be appropriate for ramfs) | |
145 | * - These flags let !MMU mmap() govern direct device mapping vs immediate | |
146 | * copying more easily for MAP_PRIVATE, especially for ROM filesystems | |
147 | */ | |
148 | #define BDI_CAP_NO_ACCT_DIRTY 0x00000001 /* Dirty pages shouldn't contribute to accounting */ | |
149 | #define BDI_CAP_NO_WRITEBACK 0x00000002 /* Don't write pages back */ | |
150 | #define BDI_CAP_MAP_COPY 0x00000004 /* Copy can be mapped (MAP_PRIVATE) */ | |
151 | #define BDI_CAP_MAP_DIRECT 0x00000008 /* Can be mapped directly (MAP_SHARED) */ | |
152 | #define BDI_CAP_READ_MAP 0x00000010 /* Can be mapped for reading */ | |
153 | #define BDI_CAP_WRITE_MAP 0x00000020 /* Can be mapped for writing */ | |
154 | #define BDI_CAP_EXEC_MAP 0x00000040 /* Can be mapped for execution */ | |
155 | #define BDI_CAP_VMFLAGS \ | |
156 | (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP) | |
157 | ||
158 | #if defined(VM_MAYREAD) && \ | |
159 | (BDI_CAP_READ_MAP != VM_MAYREAD || \ | |
160 | BDI_CAP_WRITE_MAP != VM_MAYWRITE || \ | |
161 | BDI_CAP_EXEC_MAP != VM_MAYEXEC) | |
162 | #error please change backing_dev_info::capabilities flags | |
163 | #endif | |
164 | ||
165 | extern struct backing_dev_info default_backing_dev_info; | |
166 | void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page); | |
167 | ||
1da177e4 | 168 | int writeback_in_progress(struct backing_dev_info *bdi); |
1da177e4 LT |
169 | |
170 | static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits) | |
171 | { | |
172 | if (bdi->congested_fn) | |
173 | return bdi->congested_fn(bdi->congested_data, bdi_bits); | |
174 | return (bdi->state & bdi_bits); | |
175 | } | |
176 | ||
177 | static inline int bdi_read_congested(struct backing_dev_info *bdi) | |
178 | { | |
179 | return bdi_congested(bdi, 1 << BDI_read_congested); | |
180 | } | |
181 | ||
182 | static inline int bdi_write_congested(struct backing_dev_info *bdi) | |
183 | { | |
184 | return bdi_congested(bdi, 1 << BDI_write_congested); | |
185 | } | |
186 | ||
187 | static inline int bdi_rw_congested(struct backing_dev_info *bdi) | |
188 | { | |
189 | return bdi_congested(bdi, (1 << BDI_read_congested)| | |
190 | (1 << BDI_write_congested)); | |
191 | } | |
192 | ||
3fcfab16 AM |
193 | void clear_bdi_congested(struct backing_dev_info *bdi, int rw); |
194 | void set_bdi_congested(struct backing_dev_info *bdi, int rw); | |
195 | long congestion_wait(int rw, long timeout); | |
3fcfab16 | 196 | |
1da177e4 LT |
197 | #define bdi_cap_writeback_dirty(bdi) \ |
198 | (!((bdi)->capabilities & BDI_CAP_NO_WRITEBACK)) | |
199 | ||
200 | #define bdi_cap_account_dirty(bdi) \ | |
201 | (!((bdi)->capabilities & BDI_CAP_NO_ACCT_DIRTY)) | |
202 | ||
203 | #define mapping_cap_writeback_dirty(mapping) \ | |
204 | bdi_cap_writeback_dirty((mapping)->backing_dev_info) | |
205 | ||
206 | #define mapping_cap_account_dirty(mapping) \ | |
207 | bdi_cap_account_dirty((mapping)->backing_dev_info) | |
208 | ||
209 | ||
210 | #endif /* _LINUX_BACKING_DEV_H */ |