tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1/*
2 * fs/f2fs/hash.c
3 *
4 * Copyright (c) 2012 Samsung Electronics Co., Ltd.
5 * http://www.samsung.com/
6 *
7 * Portions of this code from linux/fs/ext3/hash.c
8 *
9 * Copyright (C) 2002 by Theodore Ts'o
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License version 2 as
13 * published by the Free Software Foundation.
14 */
15#include <linux/types.h>
16#include <linux/fs.h>
17#include <linux/f2fs_fs.h>
18#include <linux/cryptohash.h>
19#include <linux/pagemap.h>
20
21#include "f2fs.h"
22
23/*
24 * Hashing code copied from ext3
25 */
26#define DELTA 0x9E3779B9
27
28static void TEA_transform(unsigned int buf[4], unsigned int const in[])
29{
30 __u32 sum = 0;
31 __u32 b0 = buf[0], b1 = buf[1];
32 __u32 a = in[0], b = in[1], c = in[2], d = in[3];
33 int n = 16;
34
35 do {
36 sum += DELTA;
37 b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
38 b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
39 } while (--n);
40
41 buf[0] += b0;
42 buf[1] += b1;
43}
44
45static void str2hashbuf(const char *msg, size_t len, unsigned int *buf, int num)
46{
47 unsigned pad, val;
48 int i;
49
50 pad = (__u32)len | ((__u32)len << 8);
51 pad |= pad << 16;
52
53 val = pad;
54 if (len > num * 4)
55 len = num * 4;
56 for (i = 0; i < len; i++) {
57 if ((i % 4) == 0)
58 val = pad;
59 val = msg[i] + (val << 8);
60 if ((i % 4) == 3) {
61 *buf++ = val;
62 val = pad;
63 num--;
64 }
65 }
66 if (--num >= 0)
67 *buf++ = val;
68 while (--num >= 0)
69 *buf++ = pad;
70}
71
72f2fs_hash_t f2fs_dentry_hash(const char *name, size_t len)
73{
74 __u32 hash;
75 f2fs_hash_t f2fs_hash;
76 const char *p;
77 __u32 in[8], buf[4];
78
79 if ((len <= 2) && (name[0] == '.') &&
80 (name[1] == '.' || name[1] == '\0'))
81 return 0;
82
83 /* Initialize the default seed for the hash checksum functions */
84 buf[0] = 0x67452301;
85 buf[1] = 0xefcdab89;
86 buf[2] = 0x98badcfe;
87 buf[3] = 0x10325476;
88
89 p = name;
90 while (1) {
91 str2hashbuf(p, len, in, 4);
92 TEA_transform(buf, in);
93 p += 16;
94 if (len <= 16)
95 break;
96 len -= 16;
97 }
98 hash = buf[0];
99 f2fs_hash = cpu_to_le32(hash & ~F2FS_HASH_COL_BIT);
100 return f2fs_hash;
101}