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>

1 files changed, 98 insertions, 0 deletions

diff --git a/fs/f2fs/hash.c b/fs/f2fs/hash.c
new file mode 100644
index 000000000000..098a1963d7c7
--- /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;
+}