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
  24         return PTR_ERR_OR_ZERO(tfm);
  25 }
  26
  27 void btrfs_hash_exit(void)
  28 {
  29         crypto_free_shash(tfm);
  30 }
  31
  32 u32 btrfs_crc32c(u32 crc, const void *address, unsigned int length)
  33 {
  34         SHASH_DESC_ON_STACK(shash, tfm);
  35         u32 *ctx = (u32 *)shash_desc_ctx(shash);
  36         int err;
  37
  38         shash->tfm = tfm;
  39         shash->flags = 0;
  40         *ctx = crc;
  41
  42         err = crypto_shash_update(shash, address, length);
  43         BUG_ON(err);
  44
  45         return *ctx;
  46 }