nilfs2: return f_fsid for statfs2

This follows the change of Coly Li's series ("fs: return f_fsid for
statfs(2)"), and make nilfs2 return f_fsid info for statfs(2).
Acked-by: NColy Li <coly.li@suse.de>
Signed-off-by: NRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

fs/nilfs2/super.c

@@ -476,11 +476,12 @@ static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 {
 	struct super_block *sb = dentry->d_sb;
 	struct nilfs_sb_info *sbi = NILFS_SB(sb);
+	struct the_nilfs *nilfs = sbi->s_nilfs;
+	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
 	unsigned long long blocks;
 	unsigned long overhead;
 	unsigned long nrsvblocks;
 	sector_t nfreeblocks;
-	struct the_nilfs *nilfs = sbi->s_nilfs;
 	int err;
 
 	/*
@@ -514,6 +515,9 @@ static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 	buf->f_files = atomic_read(&sbi->s_inodes_count);
 	buf->f_ffree = 0; /* nilfs_count_free_inodes(sb); */
 	buf->f_namelen = NILFS_NAME_LEN;
+	buf->f_fsid.val[0] = (u32)id;
+	buf->f_fsid.val[1] = (u32)(id >> 32);
+
 	return 0;
 }