fs/btrfs/hash.c

   1 /*
   2  * Copyright (C) 2014 Filipe David Borba Manana <fdmanana@gmail.com>
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  */
  13
  14 #include <crypto/hash.h>
  15 #include <linux/err.h>
  16 #include "hash.h"
  17
  18 static struct crypto_shash *tfm;
  19
  20 int __init btrfs_hash_init(void)
  21 {
  22         tfm = crypto_alloc_shash("crc32c", 0, 0);
  23         if (IS_ERR(tfm))
  24                 return PTR_ERR(tfm);
  25
  26         return 0;
  27 }
  28
  29 void btrfs_hash_exit(void)
  30 {
  31         crypto_free_shash(tfm);
  32 }
  33
  34 u32 btrfs_crc32c(u32 crc, const void *address, unsigned int length)
  35 {
  36         struct {
  37                 struct shash_desc shash;
  38                 char ctx[crypto_shash_descsize(tfm)];
  39         } desc;
  40         int err;
  41
  42         desc.shash.tfm = tfm;
  43         desc.shash.flags = 0;
  44         *(u32 *)desc.ctx = crc;
  45
  46         err = crypto_shash_update(&desc.shash, address, length);
  47         BUG_ON(err);
  48
  49         return *(u32 *)desc.ctx;
  50 }