Commit | Line | Data |
---|---|---|
b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
5cd068c2 SW |
2 | #ifndef FS_CEPH_FRAG_H |
3 | #define FS_CEPH_FRAG_H | |
de57606c SW |
4 | |
5 | /* | |
6 | * "Frags" are a way to describe a subset of a 32-bit number space, | |
7 | * using a mask and a value to match against that mask. Any given frag | |
8 | * (subset of the number space) can be partitioned into 2^n sub-frags. | |
9 | * | |
10 | * Frags are encoded into a 32-bit word: | |
11 | * 8 upper bits = "bits" | |
12 | * 24 lower bits = "value" | |
13 | * (We could go to 5+27 bits, but who cares.) | |
14 | * | |
15 | * We use the _most_ significant bits of the 24 bit value. This makes | |
16 | * values logically sort. | |
17 | * | |
18 | * Unfortunately, because the "bits" field is still in the high bits, we | |
19 | * can't sort encoded frags numerically. However, it does allow you | |
20 | * to feed encoded frags as values into frag_contains_value. | |
21 | */ | |
22 | static inline __u32 ceph_frag_make(__u32 b, __u32 v) | |
23 | { | |
24 | return (b << 24) | | |
25 | (v & (0xffffffu << (24-b)) & 0xffffffu); | |
26 | } | |
27 | static inline __u32 ceph_frag_bits(__u32 f) | |
28 | { | |
29 | return f >> 24; | |
30 | } | |
31 | static inline __u32 ceph_frag_value(__u32 f) | |
32 | { | |
33 | return f & 0xffffffu; | |
34 | } | |
35 | static inline __u32 ceph_frag_mask(__u32 f) | |
36 | { | |
37 | return (0xffffffu << (24-ceph_frag_bits(f))) & 0xffffffu; | |
38 | } | |
39 | static inline __u32 ceph_frag_mask_shift(__u32 f) | |
40 | { | |
41 | return 24 - ceph_frag_bits(f); | |
42 | } | |
43 | ||
79a3ed2e | 44 | static inline bool ceph_frag_contains_value(__u32 f, __u32 v) |
de57606c SW |
45 | { |
46 | return (v & ceph_frag_mask(f)) == ceph_frag_value(f); | |
47 | } | |
de57606c | 48 | |
de57606c SW |
49 | static inline __u32 ceph_frag_make_child(__u32 f, int by, int i) |
50 | { | |
51 | int newbits = ceph_frag_bits(f) + by; | |
52 | return ceph_frag_make(newbits, | |
53 | ceph_frag_value(f) | (i << (24 - newbits))); | |
54 | } | |
3b33f692 | 55 | static inline bool ceph_frag_is_leftmost(__u32 f) |
de57606c SW |
56 | { |
57 | return ceph_frag_value(f) == 0; | |
58 | } | |
3b33f692 | 59 | static inline bool ceph_frag_is_rightmost(__u32 f) |
de57606c SW |
60 | { |
61 | return ceph_frag_value(f) == ceph_frag_mask(f); | |
62 | } | |
63 | static inline __u32 ceph_frag_next(__u32 f) | |
64 | { | |
65 | return ceph_frag_make(ceph_frag_bits(f), | |
66 | ceph_frag_value(f) + (0x1000000 >> ceph_frag_bits(f))); | |
67 | } | |
68 | ||
69 | /* | |
70 | * comparator to sort frags logically, as when traversing the | |
71 | * number space in ascending order... | |
72 | */ | |
73 | int ceph_frag_compare(__u32 a, __u32 b); | |
74 | ||
75 | #endif |