[PATCH] erofs: derive fsid from on-disk UUID for .statfs() if possible

[Gao Xiang]

On 2024/4/9 16:11, Hongzhen Luo wrote:
> Use the superblock's UUID to generate the fsid when it's non-null.
> 
> Signed-off-by: Hongzhen Luo <hongzhen at linux.alibaba.com>

Reviewed-by: Gao Xiang <hsiangkao at linux.alibaba.com>

Thanks,
Gao Xiang

> ---
>   fs/erofs/super.c | 12 +++++-------
>   1 file changed, 5 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
> index c0eb139adb07..83bd8ee3b5ba 100644
> --- a/fs/erofs/super.c
> +++ b/fs/erofs/super.c
> @@ -923,22 +923,20 @@ static int erofs_statfs(struct dentry *dentry, struct kstatfs *buf)
>   {
>   	struct super_block *sb = dentry->d_sb;
>   	struct erofs_sb_info *sbi = EROFS_SB(sb);
> -	u64 id = 0;
> -
> -	if (!erofs_is_fscache_mode(sb))
> -		id = huge_encode_dev(sb->s_bdev->bd_dev);
>   
>   	buf->f_type = sb->s_magic;
>   	buf->f_bsize = sb->s_blocksize;
>   	buf->f_blocks = sbi->total_blocks;
>   	buf->f_bfree = buf->f_bavail = 0;
> -
>   	buf->f_files = ULLONG_MAX;
>   	buf->f_ffree = ULLONG_MAX - sbi->inos;
> -
>   	buf->f_namelen = EROFS_NAME_LEN;
>   
> -	buf->f_fsid    = u64_to_fsid(id);
> +	if (uuid_is_null(&sb->s_uuid))
> +		buf->f_fsid = u64_to_fsid(erofs_is_fscache_mode(sb) ? 0 :
> +				huge_encode_dev(sb->s_bdev->bd_dev));
> +	else
> +		buf->f_fsid = uuid_to_fsid((__u8 *)&sb->s_uuid);
>   	return 0;
>   }
>