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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 | #ifndef FS_CEPH_FRAG_H #define FS_CEPH_FRAG_H /* * "Frags" are a way to describe a subset of a 32-bit number space, * using a mask and a value to match against that mask. Any given frag * (subset of the number space) can be partitioned into 2^n sub-frags. * * Frags are encoded into a 32-bit word: * 8 upper bits = "bits" * 24 lower bits = "value" * (We could go to 5+27 bits, but who cares.) * * We use the _most_ significant bits of the 24 bit value. This makes * values logically sort. * * Unfortunately, because the "bits" field is still in the high bits, we * can't sort encoded frags numerically. However, it does allow you * to feed encoded frags as values into frag_contains_value. */ static inline __u32 ceph_frag_make(__u32 b, __u32 v) { return (b << 24) | (v & (0xffffffu << (24-b)) & 0xffffffu); } static inline __u32 ceph_frag_bits(__u32 f) { return f >> 24; } static inline __u32 ceph_frag_value(__u32 f) { return f & 0xffffffu; } static inline __u32 ceph_frag_mask(__u32 f) { return (0xffffffu << (24-ceph_frag_bits(f))) & 0xffffffu; } static inline __u32 ceph_frag_mask_shift(__u32 f) { return 24 - ceph_frag_bits(f); } static inline int ceph_frag_contains_value(__u32 f, __u32 v) { return (v & ceph_frag_mask(f)) == ceph_frag_value(f); } static inline int ceph_frag_contains_frag(__u32 f, __u32 sub) { /* is sub as specific as us, and contained by us? */ return ceph_frag_bits(sub) >= ceph_frag_bits(f) && (ceph_frag_value(sub) & ceph_frag_mask(f)) == ceph_frag_value(f); } static inline __u32 ceph_frag_parent(__u32 f) { return ceph_frag_make(ceph_frag_bits(f) - 1, ceph_frag_value(f) & (ceph_frag_mask(f) << 1)); } static inline int ceph_frag_is_left_child(__u32 f) { return ceph_frag_bits(f) > 0 && (ceph_frag_value(f) & (0x1000000 >> ceph_frag_bits(f))) == 0; } static inline int ceph_frag_is_right_child(__u32 f) { return ceph_frag_bits(f) > 0 && (ceph_frag_value(f) & (0x1000000 >> ceph_frag_bits(f))) == 1; } static inline __u32 ceph_frag_sibling(__u32 f) { return ceph_frag_make(ceph_frag_bits(f), ceph_frag_value(f) ^ (0x1000000 >> ceph_frag_bits(f))); } static inline __u32 ceph_frag_left_child(__u32 f) { return ceph_frag_make(ceph_frag_bits(f)+1, ceph_frag_value(f)); } static inline __u32 ceph_frag_right_child(__u32 f) { return ceph_frag_make(ceph_frag_bits(f)+1, ceph_frag_value(f) | (0x1000000 >> (1+ceph_frag_bits(f)))); } static inline __u32 ceph_frag_make_child(__u32 f, int by, int i) { int newbits = ceph_frag_bits(f) + by; return ceph_frag_make(newbits, ceph_frag_value(f) | (i << (24 - newbits))); } static inline int ceph_frag_is_leftmost(__u32 f) { return ceph_frag_value(f) == 0; } static inline int ceph_frag_is_rightmost(__u32 f) { return ceph_frag_value(f) == ceph_frag_mask(f); } static inline __u32 ceph_frag_next(__u32 f) { return ceph_frag_make(ceph_frag_bits(f), ceph_frag_value(f) + (0x1000000 >> ceph_frag_bits(f))); } /* * comparator to sort frags logically, as when traversing the * number space in ascending order... */ int ceph_frag_compare(__u32 a, __u32 b); #endif |