projects / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 0a8165d7 | 1 | /* |
| 6b4ea016 JK |
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 | ||
| 28 | static 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 | ||
| 9836b8b9 | 45 | static void str2hashbuf(const char *msg, size_t len, unsigned int *buf, int num) |
| 6b4ea016 JK |
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 | ||
| 9836b8b9 | 72 | f2fs_hash_t f2fs_dentry_hash(const char *name, size_t len) |
| 6b4ea016 | 73 | { |
| 2b50638d | 74 | __u32 hash; |
| 6b4ea016 JK |
75 | f2fs_hash_t f2fs_hash; |
| 76 | const char *p; | |
| 77 | __u32 in[8], buf[4]; | |
| 78 | ||
| 38e0abdc NJ |
79 | if ((len <= 2) && (name[0] == '.') && |
| 80 | (name[1] == '.' || name[1] == '\0')) | |
| 81 | return 0; | |
| 82 | ||
| 6b4ea016 JK |
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; | |
| 9836b8b9 | 90 | while (1) { |
| 6b4ea016 JK |
91 | str2hashbuf(p, len, in, 4); |
| 92 | TEA_transform(buf, in); | |
| 6b4ea016 | 93 | p += 16; |
| 9836b8b9 LR |
94 | if (len <= 16) |
| 95 | break; | |
| 96 | len -= 16; | |
| 6b4ea016 JK |
97 | } |
| 98 | hash = buf[0]; | |
| 25ca923b | 99 | f2fs_hash = cpu_to_le32(hash & ~F2FS_HASH_COL_BIT); |
| 6b4ea016 JK |
100 | return f2fs_hash; |
| 101 | } |