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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 | ||
11 | #include <asm/atomic.h> | |
12 | ||
3fcfab16 AM |
13 | struct page; |
14 | ||
1da177e4 LT |
15 | /* |
16 | * Bits in backing_dev_info.state | |
17 | */ | |
18 | enum bdi_state { | |
19 | BDI_pdflush, /* A pdflush thread is working this device */ | |
20 | BDI_write_congested, /* The write queue is getting full */ | |
21 | BDI_read_congested, /* The read queue is getting full */ | |
22 | BDI_unused, /* Available bits start here */ | |
23 | }; | |
24 | ||
25 | typedef int (congested_fn)(void *, int); | |
26 | ||
27 | struct backing_dev_info { | |
28 | unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */ | |
29 | unsigned long state; /* Always use atomic bitops on this */ | |
30 | unsigned int capabilities; /* Device capabilities */ | |
31 | congested_fn *congested_fn; /* Function pointer if device is md/dm */ | |
32 | void *congested_data; /* Pointer to aux data for congested func */ | |
33 | void (*unplug_io_fn)(struct backing_dev_info *, struct page *); | |
34 | void *unplug_io_data; | |
35 | }; | |
36 | ||
37 | ||
38 | /* | |
39 | * Flags in backing_dev_info::capability | |
40 | * - The first two flags control whether dirty pages will contribute to the | |
41 | * VM's accounting and whether writepages() should be called for dirty pages | |
42 | * (something that would not, for example, be appropriate for ramfs) | |
43 | * - These flags let !MMU mmap() govern direct device mapping vs immediate | |
44 | * copying more easily for MAP_PRIVATE, especially for ROM filesystems | |
45 | */ | |
46 | #define BDI_CAP_NO_ACCT_DIRTY 0x00000001 /* Dirty pages shouldn't contribute to accounting */ | |
47 | #define BDI_CAP_NO_WRITEBACK 0x00000002 /* Don't write pages back */ | |
48 | #define BDI_CAP_MAP_COPY 0x00000004 /* Copy can be mapped (MAP_PRIVATE) */ | |
49 | #define BDI_CAP_MAP_DIRECT 0x00000008 /* Can be mapped directly (MAP_SHARED) */ | |
50 | #define BDI_CAP_READ_MAP 0x00000010 /* Can be mapped for reading */ | |
51 | #define BDI_CAP_WRITE_MAP 0x00000020 /* Can be mapped for writing */ | |
52 | #define BDI_CAP_EXEC_MAP 0x00000040 /* Can be mapped for execution */ | |
53 | #define BDI_CAP_VMFLAGS \ | |
54 | (BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP | BDI_CAP_EXEC_MAP) | |
55 | ||
56 | #if defined(VM_MAYREAD) && \ | |
57 | (BDI_CAP_READ_MAP != VM_MAYREAD || \ | |
58 | BDI_CAP_WRITE_MAP != VM_MAYWRITE || \ | |
59 | BDI_CAP_EXEC_MAP != VM_MAYEXEC) | |
60 | #error please change backing_dev_info::capabilities flags | |
61 | #endif | |
62 | ||
63 | extern struct backing_dev_info default_backing_dev_info; | |
64 | void default_unplug_io_fn(struct backing_dev_info *bdi, struct page *page); | |
65 | ||
66 | int writeback_acquire(struct backing_dev_info *bdi); | |
67 | int writeback_in_progress(struct backing_dev_info *bdi); | |
68 | void writeback_release(struct backing_dev_info *bdi); | |
69 | ||
70 | static inline int bdi_congested(struct backing_dev_info *bdi, int bdi_bits) | |
71 | { | |
72 | if (bdi->congested_fn) | |
73 | return bdi->congested_fn(bdi->congested_data, bdi_bits); | |
74 | return (bdi->state & bdi_bits); | |
75 | } | |
76 | ||
77 | static inline int bdi_read_congested(struct backing_dev_info *bdi) | |
78 | { | |
79 | return bdi_congested(bdi, 1 << BDI_read_congested); | |
80 | } | |
81 | ||
82 | static inline int bdi_write_congested(struct backing_dev_info *bdi) | |
83 | { | |
84 | return bdi_congested(bdi, 1 << BDI_write_congested); | |
85 | } | |
86 | ||
87 | static inline int bdi_rw_congested(struct backing_dev_info *bdi) | |
88 | { | |
89 | return bdi_congested(bdi, (1 << BDI_read_congested)| | |
90 | (1 << BDI_write_congested)); | |
91 | } | |
92 | ||
3fcfab16 AM |
93 | void clear_bdi_congested(struct backing_dev_info *bdi, int rw); |
94 | void set_bdi_congested(struct backing_dev_info *bdi, int rw); | |
95 | long congestion_wait(int rw, long timeout); | |
96 | void congestion_end(int rw); | |
97 | ||
1da177e4 LT |
98 | #define bdi_cap_writeback_dirty(bdi) \ |
99 | (!((bdi)->capabilities & BDI_CAP_NO_WRITEBACK)) | |
100 | ||
101 | #define bdi_cap_account_dirty(bdi) \ | |
102 | (!((bdi)->capabilities & BDI_CAP_NO_ACCT_DIRTY)) | |
103 | ||
104 | #define mapping_cap_writeback_dirty(mapping) \ | |
105 | bdi_cap_writeback_dirty((mapping)->backing_dev_info) | |
106 | ||
107 | #define mapping_cap_account_dirty(mapping) \ | |
108 | bdi_cap_account_dirty((mapping)->backing_dev_info) | |
109 | ||
110 | ||
111 | #endif /* _LINUX_BACKING_DEV_H */ |