1 files changed, 50 insertions, 0 deletions
diff --git a/fs/btrfs/hash.c b/fs/btrfs/hash.c
new file mode 100644
index 000000000000..85889aa82c62
--- /dev/null
+++ b/fs/btrfs/hash.c
@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2014 Filipe David Borba Manana <fdmanana@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License v2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include <crypto/hash.h>
+#include <linux/err.h>
+#include "hash.h"
+
+static struct crypto_shash *tfm;
+
+int __init btrfs_hash_init(void)
+{
+	tfm = crypto_alloc_shash("crc32c", 0, 0);
+	if (IS_ERR(tfm))
+		return PTR_ERR(tfm);
+
+	return 0;
+}
+
+void btrfs_hash_exit(void)
+{
+	crypto_free_shash(tfm);
+}
+
+u32 btrfs_crc32c(u32 crc, const void *address, unsigned int length)
+{
+	struct {
+		struct shash_desc shash;
+		char ctx[crypto_shash_descsize(tfm)];
+	} desc;
+	int err;
+
+	desc.shash.tfm = tfm;
+	desc.shash.flags = 0;
+	*(u32 *)desc.ctx = crc;
+
+	err = crypto_shash_update(&desc.shash, address, length);
+	BUG_ON(err);
+
+	return *(u32 *)desc.ctx;
+}