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Jaegeuk Kim0a8165d2012-11-29 13:28:09 +09001/*
Jaegeuk Kim6b4ea012012-11-14 16:59:04 +09002 * 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
Jaegeuk Kim3304b562014-08-29 00:26:50 -070045static void str2hashbuf(const unsigned char *msg, size_t len,
46 unsigned int *buf, int num)
Jaegeuk Kim6b4ea012012-11-14 16:59:04 +090047{
48 unsigned pad, val;
49 int i;
50
51 pad = (__u32)len | ((__u32)len << 8);
52 pad |= pad << 16;
53
54 val = pad;
55 if (len > num * 4)
56 len = num * 4;
57 for (i = 0; i < len; i++) {
58 if ((i % 4) == 0)
59 val = pad;
60 val = msg[i] + (val << 8);
61 if ((i % 4) == 3) {
62 *buf++ = val;
63 val = pad;
64 num--;
65 }
66 }
67 if (--num >= 0)
68 *buf++ = val;
69 while (--num >= 0)
70 *buf++ = pad;
71}
72
Gu Zhengeee61602014-06-24 18:21:23 +080073f2fs_hash_t f2fs_dentry_hash(const struct qstr *name_info)
Jaegeuk Kim6b4ea012012-11-14 16:59:04 +090074{
Jaegeuk Kim2b506382012-12-26 14:39:50 +090075 __u32 hash;
Jaegeuk Kim6b4ea012012-11-14 16:59:04 +090076 f2fs_hash_t f2fs_hash;
Jaegeuk Kim3304b562014-08-29 00:26:50 -070077 const unsigned char *p;
Jaegeuk Kim6b4ea012012-11-14 16:59:04 +090078 __u32 in[8], buf[4];
Jaegeuk Kim3304b562014-08-29 00:26:50 -070079 const unsigned char *name = name_info->name;
Gu Zhengeee61602014-06-24 18:21:23 +080080 size_t len = name_info->len;
Jaegeuk Kim6b4ea012012-11-14 16:59:04 +090081
Jaegeuk Kimeaa693f2015-04-26 00:15:29 -070082 if (is_dot_dotdot(name_info))
Namjae Jeon38e0abd2012-12-13 23:44:11 +090083 return 0;
84
Jaegeuk Kim6b4ea012012-11-14 16:59:04 +090085 /* Initialize the default seed for the hash checksum functions */
86 buf[0] = 0x67452301;
87 buf[1] = 0xefcdab89;
88 buf[2] = 0x98badcfe;
89 buf[3] = 0x10325476;
90
91 p = name;
Leon Romanovsky9836b8b2012-12-27 19:55:46 +020092 while (1) {
Jaegeuk Kim6b4ea012012-11-14 16:59:04 +090093 str2hashbuf(p, len, in, 4);
94 TEA_transform(buf, in);
Jaegeuk Kim6b4ea012012-11-14 16:59:04 +090095 p += 16;
Leon Romanovsky9836b8b2012-12-27 19:55:46 +020096 if (len <= 16)
97 break;
98 len -= 16;
Jaegeuk Kim6b4ea012012-11-14 16:59:04 +090099 }
100 hash = buf[0];
Jaegeuk Kim25ca9232012-11-28 16:12:41 +0900101 f2fs_hash = cpu_to_le32(hash & ~F2FS_HASH_COL_BIT);
Jaegeuk Kim6b4ea012012-11-14 16:59:04 +0900102 return f2fs_hash;
103}