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author | James Bottomley <jejb@mulgrave.il.steeleye.com> | 2006-11-22 12:06:44 -0600 |
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committer | James Bottomley <jejb@mulgrave.il.steeleye.com> | 2006-11-22 12:06:44 -0600 |
commit | 0bd2af46839ad6262d25714a6ec0365db9d6b98f (patch) | |
tree | dcced72d230d69fd0c5816ac6dd03ab84799a93e /fs/ext4/hash.c | |
parent | e138a5d2356729b8752e88520cc1525fae9794ac (diff) | |
parent | f26b90440cd74c78fe10c9bd5160809704a9627c (diff) |
Merge ../scsi-rc-fixes-2.6
Diffstat (limited to 'fs/ext4/hash.c')
-rw-r--r-- | fs/ext4/hash.c | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/fs/ext4/hash.c b/fs/ext4/hash.c new file mode 100644 index 00000000000..a67966385e0 --- /dev/null +++ b/fs/ext4/hash.c @@ -0,0 +1,152 @@ +/* + * linux/fs/ext4/hash.c + * + * Copyright (C) 2002 by Theodore Ts'o + * + * This file is released under the GPL v2. + * + * This file may be redistributed under the terms of the GNU Public + * License. + */ + +#include <linux/fs.h> +#include <linux/jbd2.h> +#include <linux/sched.h> +#include <linux/ext4_fs.h> +#include <linux/cryptohash.h> + +#define DELTA 0x9E3779B9 + +static void TEA_transform(__u32 buf[4], __u32 const in[]) +{ + __u32 sum = 0; + __u32 b0 = buf[0], b1 = buf[1]; + __u32 a = in[0], b = in[1], c = in[2], d = in[3]; + int n = 16; + + do { + sum += DELTA; + b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b); + b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d); + } while(--n); + + buf[0] += b0; + buf[1] += b1; +} + + +/* The old legacy hash */ +static __u32 dx_hack_hash (const char *name, int len) +{ + __u32 hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9; + while (len--) { + __u32 hash = hash1 + (hash0 ^ (*name++ * 7152373)); + + if (hash & 0x80000000) hash -= 0x7fffffff; + hash1 = hash0; + hash0 = hash; + } + return (hash0 << 1); +} + +static void str2hashbuf(const char *msg, int len, __u32 *buf, int num) +{ + __u32 pad, val; + int i; + + pad = (__u32)len | ((__u32)len << 8); + pad |= pad << 16; + + val = pad; + if (len > num*4) + len = num * 4; + for (i=0; i < len; i++) { + if ((i % 4) == 0) + val = pad; + val = msg[i] + (val << 8); + if ((i % 4) == 3) { + *buf++ = val; + val = pad; + num--; + } + } + if (--num >= 0) + *buf++ = val; + while (--num >= 0) + *buf++ = pad; +} + +/* + * Returns the hash of a filename. If len is 0 and name is NULL, then + * this function can be used to test whether or not a hash version is + * supported. + * + * The seed is an 4 longword (32 bits) "secret" which can be used to + * uniquify a hash. If the seed is all zero's, then some default seed + * may be used. + * + * A particular hash version specifies whether or not the seed is + * represented, and whether or not the returned hash is 32 bits or 64 + * bits. 32 bit hashes will return 0 for the minor hash. + */ +int ext4fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo) +{ + __u32 hash; + __u32 minor_hash = 0; + const char *p; + int i; + __u32 in[8], buf[4]; + + /* Initialize the default seed for the hash checksum functions */ + buf[0] = 0x67452301; + buf[1] = 0xefcdab89; + buf[2] = 0x98badcfe; + buf[3] = 0x10325476; + + /* Check to see if the seed is all zero's */ + if (hinfo->seed) { + for (i=0; i < 4; i++) { + if (hinfo->seed[i]) + break; + } + if (i < 4) + memcpy(buf, hinfo->seed, sizeof(buf)); + } + + switch (hinfo->hash_version) { + case DX_HASH_LEGACY: + hash = dx_hack_hash(name, len); + break; + case DX_HASH_HALF_MD4: + p = name; + while (len > 0) { + str2hashbuf(p, len, in, 8); + half_md4_transform(buf, in); + len -= 32; + p += 32; + } + minor_hash = buf[2]; + hash = buf[1]; + break; + case DX_HASH_TEA: + p = name; + while (len > 0) { + str2hashbuf(p, len, in, 4); + TEA_transform(buf, in); + len -= 16; + p += 16; + } + hash = buf[0]; + minor_hash = buf[1]; + break; + default: + hinfo->hash = 0; + return -1; + } + hash = hash & ~1; + if (hash == (EXT4_HTREE_EOF << 1)) + hash = (EXT4_HTREE_EOF-1) << 1; + hinfo->hash = hash; + hinfo->minor_hash = minor_hash; + return 0; +} |