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Date:   Sat, 30 Jan 2021 14:07:30 -0800 (PST)
From:   David Rientjes <rientjes@google.com>
To:     Miaohe Lin <linmiaohe@huawei.com>
cc:     akpm@linux-foundation.org, mike.kravetz@oracle.com,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] hugetlbfs: show pagesize in unit of GB if possible
In-Reply-To: <20210130090339.4378-1-linmiaohe@huawei.com>
Message-ID: <f5ac7d57-6653-aae-f119-b87d72acf192@google.com>
References: <20210130090339.4378-1-linmiaohe@huawei.com>
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On Sat, 30 Jan 2021, Miaohe Lin wrote:

> Hugepage size in unit of GB is supported. We could show pagesize in unit of
> GB to make it more friendly to read. Also rework the calculation code of
> page size unit to make it more readable.
> 
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
>  fs/hugetlbfs/inode.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
> index 3a08fbae3b53..40a9795f250a 100644
> --- a/fs/hugetlbfs/inode.c
> +++ b/fs/hugetlbfs/inode.c
> @@ -1014,11 +1014,15 @@ static int hugetlbfs_show_options(struct seq_file *m, struct dentry *root)
>  	if (sbinfo->max_inodes != -1)
>  		seq_printf(m, ",nr_inodes=%lu", sbinfo->max_inodes);
>  
> -	hpage_size /= 1024;
> -	mod = 'K';
> -	if (hpage_size >= 1024) {
> -		hpage_size /= 1024;
> +	if (hpage_size >= SZ_1G) {
> +		hpage_size /= SZ_1G;
> +		mod = 'G';
> +	} else if (hpage_size >= SZ_1M) {
> +		hpage_size /= SZ_1M;
>  		mod = 'M';
> +	} else {
> +		hpage_size /= SZ_1K;
> +		mod = 'K';
>  	}
>  	seq_printf(m, ",pagesize=%lu%c", hpage_size, mod);
>  	if (spool) {

NACK, this can break existing userspace parsing.