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/include/linux/ceph/ceph_frag.h

https://github.com/airy09/android_kernel_sony_apq8064
C Header | 109 lines | 82 code | 5 blank | 22 comment | 6 complexity | 26dd781d46f522c75411a6b5f10c0706 MD5 | raw file
  1#ifndef FS_CEPH_FRAG_H
  2#define FS_CEPH_FRAG_H
  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 */
 21static inline __u32 ceph_frag_make(__u32 b, __u32 v)
 22{
 23	return (b << 24) |
 24		(v & (0xffffffu << (24-b)) & 0xffffffu);
 25}
 26static inline __u32 ceph_frag_bits(__u32 f)
 27{
 28	return f >> 24;
 29}
 30static inline __u32 ceph_frag_value(__u32 f)
 31{
 32	return f & 0xffffffu;
 33}
 34static inline __u32 ceph_frag_mask(__u32 f)
 35{
 36	return (0xffffffu << (24-ceph_frag_bits(f))) & 0xffffffu;
 37}
 38static inline __u32 ceph_frag_mask_shift(__u32 f)
 39{
 40	return 24 - ceph_frag_bits(f);
 41}
 42
 43static inline int ceph_frag_contains_value(__u32 f, __u32 v)
 44{
 45	return (v & ceph_frag_mask(f)) == ceph_frag_value(f);
 46}
 47static inline int ceph_frag_contains_frag(__u32 f, __u32 sub)
 48{
 49	/* is sub as specific as us, and contained by us? */
 50	return ceph_frag_bits(sub) >= ceph_frag_bits(f) &&
 51	       (ceph_frag_value(sub) & ceph_frag_mask(f)) == ceph_frag_value(f);
 52}
 53
 54static inline __u32 ceph_frag_parent(__u32 f)
 55{
 56	return ceph_frag_make(ceph_frag_bits(f) - 1,
 57			 ceph_frag_value(f) & (ceph_frag_mask(f) << 1));
 58}
 59static inline int ceph_frag_is_left_child(__u32 f)
 60{
 61	return ceph_frag_bits(f) > 0 &&
 62		(ceph_frag_value(f) & (0x1000000 >> ceph_frag_bits(f))) == 0;
 63}
 64static inline int ceph_frag_is_right_child(__u32 f)
 65{
 66	return ceph_frag_bits(f) > 0 &&
 67		(ceph_frag_value(f) & (0x1000000 >> ceph_frag_bits(f))) == 1;
 68}
 69static inline __u32 ceph_frag_sibling(__u32 f)
 70{
 71	return ceph_frag_make(ceph_frag_bits(f),
 72		      ceph_frag_value(f) ^ (0x1000000 >> ceph_frag_bits(f)));
 73}
 74static inline __u32 ceph_frag_left_child(__u32 f)
 75{
 76	return ceph_frag_make(ceph_frag_bits(f)+1, ceph_frag_value(f));
 77}
 78static inline __u32 ceph_frag_right_child(__u32 f)
 79{
 80	return ceph_frag_make(ceph_frag_bits(f)+1,
 81	      ceph_frag_value(f) | (0x1000000 >> (1+ceph_frag_bits(f))));
 82}
 83static inline __u32 ceph_frag_make_child(__u32 f, int by, int i)
 84{
 85	int newbits = ceph_frag_bits(f) + by;
 86	return ceph_frag_make(newbits,
 87			 ceph_frag_value(f) | (i << (24 - newbits)));
 88}
 89static inline int ceph_frag_is_leftmost(__u32 f)
 90{
 91	return ceph_frag_value(f) == 0;
 92}
 93static inline int ceph_frag_is_rightmost(__u32 f)
 94{
 95	return ceph_frag_value(f) == ceph_frag_mask(f);
 96}
 97static inline __u32 ceph_frag_next(__u32 f)
 98{
 99	return ceph_frag_make(ceph_frag_bits(f),
100			 ceph_frag_value(f) + (0x1000000 >> ceph_frag_bits(f)));
101}
102
103/*
104 * comparator to sort frags logically, as when traversing the
105 * number space in ascending order...
106 */
107int ceph_frag_compare(__u32 a, __u32 b);
108
109#endif