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