f2fs: fix crc endian conversion

While calculating CRC for the checkpoint block, we use __u32, but when storing
the crc value to the disk, we use __le32.

Let's fix the inconsistency.

Reported-and-Tested-by: Oded Gabbay <ogabbay@advaoptical.com>
Signed-off-by: Jaegeuk Kim <jaegeuk.kim@samsung.com>
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 863a5e91..467d42d 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -47,14 +47,25 @@
 	unsigned int	opt;
 };
 
-static inline __u32 f2fs_crc32(void *buff, size_t len)
+#define CRCPOLY_LE 0xedb88320
+
+static inline __u32 f2fs_crc32(void *buf, size_t len)
 {
-	return crc32_le(F2FS_SUPER_MAGIC, buff, len);
+	unsigned char *p = (unsigned char *)buf;
+	__u32 crc = F2FS_SUPER_MAGIC;
+	int i;
+
+	while (len--) {
+		crc ^= *p++;
+		for (i = 0; i < 8; i++)
+			crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY_LE : 0);
+	}
+	return crc;
 }
 
-static inline bool f2fs_crc_valid(__u32 blk_crc, void *buff, size_t buff_size)
+static inline bool f2fs_crc_valid(__u32 blk_crc, void *buf, size_t buf_size)
 {
-	return f2fs_crc32(buff, buff_size) == blk_crc;
+	return f2fs_crc32(buf, buf_size) == blk_crc;
 }
 
 /*