104 строки
2.1 KiB
C
104 строки
2.1 KiB
C
/*
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* fs/f2fs/hash.c
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*
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* Copyright (c) 2012 Samsung Electronics Co., Ltd.
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* http://www.samsung.com/
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*
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* Portions of this code from linux/fs/ext3/hash.c
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*
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* Copyright (C) 2002 by Theodore Ts'o
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/types.h>
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#include <linux/fs.h>
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#include <linux/f2fs_fs.h>
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#include <linux/cryptohash.h>
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#include <linux/pagemap.h>
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#include "f2fs.h"
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/*
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* Hashing code copied from ext3
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*/
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#define DELTA 0x9E3779B9
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static void TEA_transform(unsigned int buf[4], unsigned int const in[])
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{
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__u32 sum = 0;
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__u32 b0 = buf[0], b1 = buf[1];
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__u32 a = in[0], b = in[1], c = in[2], d = in[3];
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int n = 16;
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do {
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sum += DELTA;
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b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
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b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
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} while (--n);
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buf[0] += b0;
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buf[1] += b1;
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}
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static void str2hashbuf(const char *msg, size_t len, unsigned int *buf, int num)
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{
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unsigned pad, val;
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int i;
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pad = (__u32)len | ((__u32)len << 8);
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pad |= pad << 16;
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val = pad;
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if (len > num * 4)
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len = num * 4;
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for (i = 0; i < len; i++) {
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if ((i % 4) == 0)
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val = pad;
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val = msg[i] + (val << 8);
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if ((i % 4) == 3) {
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*buf++ = val;
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val = pad;
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num--;
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}
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}
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if (--num >= 0)
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*buf++ = val;
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while (--num >= 0)
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*buf++ = pad;
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}
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f2fs_hash_t f2fs_dentry_hash(const struct qstr *name_info)
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{
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__u32 hash;
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f2fs_hash_t f2fs_hash;
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const char *p;
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__u32 in[8], buf[4];
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const char *name = name_info->name;
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size_t len = name_info->len;
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if ((len <= 2) && (name[0] == '.') &&
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(name[1] == '.' || name[1] == '\0'))
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return 0;
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/* Initialize the default seed for the hash checksum functions */
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buf[0] = 0x67452301;
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buf[1] = 0xefcdab89;
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buf[2] = 0x98badcfe;
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buf[3] = 0x10325476;
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p = name;
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while (1) {
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str2hashbuf(p, len, in, 4);
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TEA_transform(buf, in);
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p += 16;
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if (len <= 16)
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break;
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len -= 16;
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}
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hash = buf[0];
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f2fs_hash = cpu_to_le32(hash & ~F2FS_HASH_COL_BIT);
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return f2fs_hash;
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}
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