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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> | |
1da177e4 LT |
13 | #include <asm/atomic.h> |
14 | ||
3fcfab16 AM |
15 | struct page; |
16 | ||
1da177e4 LT |
17 | /* |
18 | * Bits in backing_dev_info.state | |
19 | */ | |
20 | enum bdi_state { | |
21 | BDI_pdflush, /* A pdflush thread is working this device */ | |
22 | BDI_write_congested, /* The write queue is getting full */ | |
23 | BDI_read_congested, /* The read queue is getting full */ | |
24 | BDI_unused, /* Available bits start here */ | |
25 | }; | |
26 | ||
27 | typedef int (congested_fn)(void *, int); | |
28 | ||
b2e8fb6e | 29 | enum bdi_stat_item { |
c9e51e41 | 30 | BDI_RECLAIMABLE, |
69cb51d1 | 31 | BDI_WRITEBACK, |
b2e8fb6e PZ |
32 | NR_BDI_STAT_ITEMS |
33 | }; | |
34 | ||
35 | #define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids))) | |
36 | ||
1da177e4 LT |
37 | struct backing_dev_info { |
38 | unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */ | |
39 | unsigned long state; /* Always use atomic bitops on this */ | |
40 | unsigned int capabilities; /* Device capabilities */ | |
41 | congested_fn *congested_fn; /* Function pointer if device is md/dm */ | |
42 | void *congested_data; /* Pointer to aux data for congested func */ | |
43 | void (*unplug_io_fn)(struct backing_dev_info *, struct page *); | |
44 | void *unplug_io_data; | |
b2e8fb6e PZ |
45 | |
46 | struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS]; | |
1da177e4 LT |
47 | }; |
48 | ||
b2e8fb6e PZ |
49 | int bdi_init(struct backing_dev_info *bdi); |
50 | void bdi_destroy(struct backing_dev_info *bdi); | |
51 | ||
52 | static inline void __add_bdi_stat(struct backing_dev_info *bdi, | |
53 | enum bdi_stat_item item, s64 amount) | |
54 | { | |
55 | __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH); | |
56 | } | |
57 | ||
58 | static inline void __inc_bdi_stat(struct backing_dev_info *bdi, | |
59 | enum bdi_stat_item item) | |
60 | { | |
61 | __add_bdi_stat(bdi, item, 1); | |
62 | } | |
63 | ||
64 | static inline void inc_bdi_stat(struct backing_dev_info *bdi, | |
65 | enum bdi_stat_item item) | |
66 | { | |
67 | unsigned long flags; | |
68 | ||
69 | local_irq_save(flags); | |
70 | __inc_bdi_stat(bdi, item); | |
71 | local_irq_restore(flags); | |
72 | } | |
73 | ||
74 | static inline void __dec_bdi_stat(struct backing_dev_info *bdi, | |
75 | enum bdi_stat_item item) | |
76 | { | |
77 | __add_bdi_stat(bdi, item, -1); | |
78 | } | |
79 | ||
80 | static inline void dec_bdi_stat(struct backing_dev_info *bdi, | |
81 | enum bdi_stat_item item) | |
82 | { | |
83 | unsigned long flags; | |
84 | ||
85 | local_irq_save(flags); | |
86 | __dec_bdi_stat(bdi, item); | |
87 | local_irq_restore(flags); | |
88 | } | |
89 | ||
90 | static inline s64 bdi_stat(struct backing_dev_info *bdi, | |
91 | enum bdi_stat_item item) | |
92 | { | |
93 | return percpu_counter_read_positive(&bdi->bdi_stat[item]); | |
94 | } | |
95 | ||
96 | static inline s64 __bdi_stat_sum(struct backing_dev_info *bdi, | |
97 | enum bdi_stat_item item) | |
98 | { | |
99 | return percpu_counter_sum_positive(&bdi->bdi_stat[item]); | |
100 | } | |
101 | ||
102 | static inline s64 bdi_stat_sum(struct backing_dev_info *bdi, | |
103 | enum bdi_stat_item item) | |
e0bf68dd | 104 | { |
b2e8fb6e PZ |
105 | s64 sum; |
106 | unsigned long flags; | |
107 | ||
108 | local_irq_save(flags); | |
109 | sum = __bdi_stat_sum(bdi, item); | |
110 | local_irq_restore(flags); | |
111 | ||
112 | return sum; | |
e0bf68dd PZ |
113 | } |
114 | ||
b2e8fb6e PZ |
115 | /* |
116 | * maximal error of a stat counter. | |
117 | */ | |
118 | static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi) | |
e0bf68dd | 119 | { |
b2e8fb6e PZ |
120 | #ifdef CONFIG_SMP |
121 | return nr_cpu_ids * BDI_STAT_BATCH; | |
122 | #else | |
123 | return 1; | |
124 | #endif | |
e0bf68dd | 125 | } |
1da177e4 LT |
126 | |
127 | /* | |
128 | * Flags in backing_dev_info::capability | |
129 | * - The first two flags control whether dirty pages will contribute to the | |
130 | * VM's accounting and whether writepages() should be called for dirty pages | |
131 | * (something that would not, for example, be appropriate for ramfs) | |
132 | * - These flags let !MMU mmap() govern direct device mapping vs immediate | |
133 | * copying more easily for MAP_PRIVATE, especially for ROM filesystems | |
134 | */ | |
135 | #define BDI_CAP_NO_ACCT_DIRTY 0x00000001 /* Dirty pages shouldn't contribute to accounting */ | |
136 | #define BDI_CAP_NO_WRITEBACK 0x00000002 /* Don't write pages back */ | |
137 | #define BDI_CAP_MAP_COPY 0x00000004 /* Copy can be mapped (MAP_PRIVATE) */ | |
138 | #define BDI_CAP_MAP_DIRECT 0x00000008 /* Can be mapped directly (MAP_SHARED) */ | |
139 | #define BDI_CAP_READ_MAP 0x00000010 /* Can be mapped for reading */ | |
140 | #define BDI_CAP_WRITE_MAP 0x00000020 /* Can be mapped for writing */ | |
141 | #define BDI_CAP_EXEC_MAP 0x00000040 /* Can be mapped for execution */ | |
142 | #define BDI_CAP_VMFLAGS \ | |
143 | (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP) | |
144 | ||
145 | #if defined(VM_MAYREAD) && \ | |
146 | (BDI_CAP_READ_MAP != VM_MAYREAD || \ | |
147 | BDI_CAP_WRITE_MAP != VM_MAYWRITE || \ | |
148 | BDI_CAP_EXEC_MAP != VM_MAYEXEC) | |
149 | #error please change backing_dev_info::capabilities flags | |
150 | #endif | |
151 | ||
152 | extern struct backing_dev_info default_backing_dev_info; | |
153 | void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page); | |
154 | ||
155 | int writeback_acquire(struct backing_dev_info *bdi); | |
156 | int writeback_in_progress(struct backing_dev_info *bdi); | |
157 | void writeback_release(struct backing_dev_info *bdi); | |
158 | ||
159 | static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits) | |
160 | { | |
161 | if (bdi->congested_fn) | |
162 | return bdi->congested_fn(bdi->congested_data, bdi_bits); | |
163 | return (bdi->state & bdi_bits); | |
164 | } | |
165 | ||
166 | static inline int bdi_read_congested(struct backing_dev_info *bdi) | |
167 | { | |
168 | return bdi_congested(bdi, 1 << BDI_read_congested); | |
169 | } | |
170 | ||
171 | static inline int bdi_write_congested(struct backing_dev_info *bdi) | |
172 | { | |
173 | return bdi_congested(bdi, 1 << BDI_write_congested); | |
174 | } | |
175 | ||
176 | static inline int bdi_rw_congested(struct backing_dev_info *bdi) | |
177 | { | |
178 | return bdi_congested(bdi, (1 << BDI_read_congested)| | |
179 | (1 << BDI_write_congested)); | |
180 | } | |
181 | ||
3fcfab16 AM |
182 | void clear_bdi_congested(struct backing_dev_info *bdi, int rw); |
183 | void set_bdi_congested(struct backing_dev_info *bdi, int rw); | |
184 | long congestion_wait(int rw, long timeout); | |
3fcfab16 | 185 | |
1da177e4 LT |
186 | #define bdi_cap_writeback_dirty(bdi) \ |
187 | (!((bdi)->capabilities & BDI_CAP_NO_WRITEBACK)) | |
188 | ||
189 | #define bdi_cap_account_dirty(bdi) \ | |
190 | (!((bdi)->capabilities & BDI_CAP_NO_ACCT_DIRTY)) | |
191 | ||
192 | #define mapping_cap_writeback_dirty(mapping) \ | |
193 | bdi_cap_writeback_dirty((mapping)->backing_dev_info) | |
194 | ||
195 | #define mapping_cap_account_dirty(mapping) \ | |
196 | bdi_cap_account_dirty((mapping)->backing_dev_info) | |
197 | ||
198 | ||
199 | #endif /* _LINUX_BACKING_DEV_H */ |