1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * Copyright (C) 2021-2023 Oracle. All Rights Reserved. 4 * Author: Darrick J. Wong <djwong@kernel.org> 5 */ 6 #ifndef __XFS_SCRUB_XFARRAY_H__ 7 #define __XFS_SCRUB_XFARRAY_H__ 8 9 /* xfile array index type, along with cursor initialization */ 10 typedef uint64_t xfarray_idx_t; 11 #define XFARRAY_CURSOR_INIT ((__force xfarray_idx_t)0) 12 13 /* Iterate each index of an xfile array. */ 14 #define foreach_xfarray_idx(array, idx) \ 15 for ((idx) = XFARRAY_CURSOR_INIT; \ 16 (idx) < xfarray_length(array); \ 17 (idx)++) 18 19 struct xfarray { 20 /* Underlying file that backs the array. */ 21 struct xfile *xfile; 22 23 /* Number of array elements. */ 24 xfarray_idx_t nr; 25 26 /* Maximum possible array size. */ 27 xfarray_idx_t max_nr; 28 29 /* Number of unset slots in the array below @nr. */ 30 uint64_t unset_slots; 31 32 /* Size of an array element. */ 33 size_t obj_size; 34 35 /* log2 of array element size, if possible. */ 36 int obj_size_log; 37 }; 38 39 int xfarray_create(const char *descr, unsigned long long required_capacity, 40 size_t obj_size, struct xfarray **arrayp); 41 void xfarray_destroy(struct xfarray *array); 42 int xfarray_load(struct xfarray *array, xfarray_idx_t idx, void *ptr); 43 int xfarray_unset(struct xfarray *array, xfarray_idx_t idx); 44 int xfarray_store(struct xfarray *array, xfarray_idx_t idx, const void *ptr); 45 int xfarray_store_anywhere(struct xfarray *array, const void *ptr); 46 bool xfarray_element_is_null(struct xfarray *array, const void *ptr); 47 48 /* Append an element to the array. */ 49 static inline int xfarray_append(struct xfarray *array, const void *ptr) 50 { 51 return xfarray_store(array, array->nr, ptr); 52 } 53 54 uint64_t xfarray_length(struct xfarray *array); 55 int xfarray_load_next(struct xfarray *array, xfarray_idx_t *idx, void *rec); 56 57 /* Declarations for xfile array sort functionality. */ 58 59 typedef cmp_func_t xfarray_cmp_fn; 60 61 /* Perform an in-memory heapsort for small subsets. */ 62 #define XFARRAY_ISORT_SHIFT (4) 63 #define XFARRAY_ISORT_NR (1U << XFARRAY_ISORT_SHIFT) 64 65 /* Evalulate this many points to find the qsort pivot. */ 66 #define XFARRAY_QSORT_PIVOT_NR (9) 67 68 struct xfarray_sortinfo { 69 struct xfarray *array; 70 71 /* Comparison function for the sort. */ 72 xfarray_cmp_fn cmp_fn; 73 74 /* Maximum height of the partition stack. */ 75 uint8_t max_stack_depth; 76 77 /* Current height of the partition stack. */ 78 int8_t stack_depth; 79 80 /* Maximum stack depth ever used. */ 81 uint8_t max_stack_used; 82 83 /* XFARRAY_SORT_* flags; see below. */ 84 unsigned int flags; 85 86 /* Cache a page here for faster access. */ 87 struct xfile_page xfpage; 88 void *page_kaddr; 89 90 #ifdef DEBUG 91 /* Performance statistics. */ 92 uint64_t loads; 93 uint64_t stores; 94 uint64_t compares; 95 uint64_t heapsorts; 96 #endif 97 /* 98 * Extra bytes are allocated beyond the end of the structure to store 99 * quicksort information. C does not permit multiple VLAs per struct, 100 * so we document all of this in a comment. 101 * 102 * Pretend that we have a typedef for array records: 103 * 104 * typedef char[array->obj_size] xfarray_rec_t; 105 * 106 * First comes the quicksort partition stack: 107 * 108 * xfarray_idx_t lo[max_stack_depth]; 109 * xfarray_idx_t hi[max_stack_depth]; 110 * 111 * union { 112 * 113 * If for a given subset we decide to use an in-memory sort, we use a 114 * block of scratchpad records here to compare items: 115 * 116 * xfarray_rec_t scratch[ISORT_NR]; 117 * 118 * Otherwise, we want to partition the records to partition the array. 119 * We store the chosen pivot record at the start of the scratchpad area 120 * and use the rest to sample some records to estimate the median. 121 * The format of the qsort_pivot array enables us to use the kernel 122 * heapsort function to place the median value in the middle. 123 * 124 * struct { 125 * xfarray_rec_t pivot; 126 * struct { 127 * xfarray_rec_t rec; (rounded up to 8 bytes) 128 * xfarray_idx_t idx; 129 * } qsort_pivot[QSORT_PIVOT_NR]; 130 * }; 131 * } 132 */ 133 }; 134 135 /* Sort can be interrupted by a fatal signal. */ 136 #define XFARRAY_SORT_KILLABLE (1U << 0) 137 138 int xfarray_sort(struct xfarray *array, xfarray_cmp_fn cmp_fn, 139 unsigned int flags); 140 141 #endif /* __XFS_SCRUB_XFARRAY_H__ */ 142