f2fs: support inode checksum

This patch adds to support inode checksum in f2fs.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
[Jaegeuk Kim: fix verification flow]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 4c28576..fc757c8 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1993,6 +1993,11 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent)
 	sb->s_fs_info = sbi;
 	sbi->raw_super = raw_super;
 
+	/* precompute checksum seed for metadata */
+	if (f2fs_sb_has_inode_chksum(sb))
+		sbi->s_chksum_seed = f2fs_chksum(sbi, ~0, raw_super->uuid,
+						sizeof(raw_super->uuid));
+
 	/*
 	 * The BLKZONED feature indicates that the drive was formatted with
 	 * zone alignment optimization. This is optional for host-aware