f2fs: add core directory operations
this adds core functions to find, add, delete, and link dentries.
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
diff --git a/fs/f2fs/hash.c b/fs/f2fs/hash.c
new file mode 100644
index 0000000..098a196
--- /dev/null
+++ b/fs/f2fs/hash.c
@@ -0,0 +1,98 @@
+/**
+ * fs/f2fs/hash.c
+ *
+ * Copyright (c) 2012 Samsung Electronics Co., Ltd.
+ * http://www.samsung.com/
+ *
+ * Portions of this code from linux/fs/ext3/hash.c
+ *
+ * Copyright (C) 2002 by Theodore Ts'o
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/f2fs_fs.h>
+#include <linux/cryptohash.h>
+#include <linux/pagemap.h>
+
+#include "f2fs.h"
+
+/*
+ * Hashing code copied from ext3
+ */
+#define DELTA 0x9E3779B9
+
+static void TEA_transform(unsigned int buf[4], unsigned int 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;
+}
+
+static void str2hashbuf(const char *msg, int len, unsigned int *buf, int num)
+{
+ unsigned 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;
+}
+
+f2fs_hash_t f2fs_dentry_hash(const char *name, int len)
+{
+ __u32 hash, minor_hash;
+ f2fs_hash_t f2fs_hash;
+ const char *p;
+ __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;
+
+ 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];
+
+ f2fs_hash = hash;
+ f2fs_hash &= ~F2FS_HASH_COL_BIT;
+ return f2fs_hash;
+}