Commit | Line | Data |
---|---|---|
5cd068c2 SW |
1 | #ifndef FS_CEPH_FRAG_H |
2 | #define FS_CEPH_FRAG_H | |
de57606c SW |
3 | |
4 | /* | |
5 | * "Frags" are a way to describe a subset of a 32-bit number space, | |
6 | * using a mask and a value to match against that mask. Any given frag | |
7 | * (subset of the number space) can be partitioned into 2^n sub-frags. | |
8 | * | |
9 | * Frags are encoded into a 32-bit word: | |
10 | * 8 upper bits = "bits" | |
11 | * 24 lower bits = "value" | |
12 | * (We could go to 5+27 bits, but who cares.) | |
13 | * | |
14 | * We use the _most_ significant bits of the 24 bit value. This makes | |
15 | * values logically sort. | |
16 | * | |
17 | * Unfortunately, because the "bits" field is still in the high bits, we | |
18 | * can't sort encoded frags numerically. However, it does allow you | |
19 | * to feed encoded frags as values into frag_contains_value. | |
20 | */ | |
21 | static inline __u32 ceph_frag_make(__u32 b, __u32 v) | |
22 | { | |
23 | return (b << 24) | | |
24 | (v & (0xffffffu << (24-b)) & 0xffffffu); | |
25 | } | |
26 | static inline __u32 ceph_frag_bits(__u32 f) | |
27 | { | |
28 | return f >> 24; | |
29 | } | |
30 | static inline __u32 ceph_frag_value(__u32 f) | |
31 | { | |
32 | return f & 0xffffffu; | |
33 | } | |
34 | static inline __u32 ceph_frag_mask(__u32 f) | |
35 | { | |
36 | return (0xffffffu << (24-ceph_frag_bits(f))) & 0xffffffu; | |
37 | } | |
38 | static inline __u32 ceph_frag_mask_shift(__u32 f) | |
39 | { | |
40 | return 24 - ceph_frag_bits(f); | |
41 | } | |
42 | ||
79a3ed2e | 43 | static inline bool ceph_frag_contains_value(__u32 f, __u32 v) |
de57606c SW |
44 | { |
45 | return (v & ceph_frag_mask(f)) == ceph_frag_value(f); | |
46 | } | |
de57606c | 47 | |
de57606c SW |
48 | static inline __u32 ceph_frag_make_child(__u32 f, int by, int i) |
49 | { | |
50 | int newbits = ceph_frag_bits(f) + by; | |
51 | return ceph_frag_make(newbits, | |
52 | ceph_frag_value(f) | (i << (24 - newbits))); | |
53 | } | |
3b33f692 | 54 | static inline bool ceph_frag_is_leftmost(__u32 f) |
de57606c SW |
55 | { |
56 | return ceph_frag_value(f) == 0; | |
57 | } | |
3b33f692 | 58 | static inline bool ceph_frag_is_rightmost(__u32 f) |
de57606c SW |
59 | { |
60 | return ceph_frag_value(f) == ceph_frag_mask(f); | |
61 | } | |
62 | static inline __u32 ceph_frag_next(__u32 f) | |
63 | { | |
64 | return ceph_frag_make(ceph_frag_bits(f), | |
65 | ceph_frag_value(f) + (0x1000000 >> ceph_frag_bits(f))); | |
66 | } | |
67 | ||
68 | /* | |
69 | * comparator to sort frags logically, as when traversing the | |
70 | * number space in ascending order... | |
71 | */ | |
72 | int ceph_frag_compare(__u32 a, __u32 b); | |
73 | ||
74 | #endif |