Edit File: ceph_frag.h
#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 bool ceph_frag_contains_value(__u32 f, __u32 v) { return (v & ceph_frag_mask(f)) == ceph_frag_value(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 bool ceph_frag_is_leftmost(__u32 f) { return ceph_frag_value(f) == 0; } static inline bool 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