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Message-ID: <46253829-689c-4f06-8d08-a999c0ddbd1b@linux.alibaba.com>
Date: Tue, 9 Apr 2024 17:36:38 +0800
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Subject: Re: [PATCH] erofs: derive fsid from on-disk UUID for .statfs() if
 possible
Content-Language: en-US
To: Hongzhen Luo <hongzhen@linux.alibaba.com>, xiang@kernel.org,
 chao@kernel.org, linux-erofs@lists.ozlabs.org
Cc: huyue2@coolpad.com, dhavale@google.com, linux-kernel@vger.kernel.org
References: <20240409081135.6102-1-hongzhen@linux.alibaba.com>
From: Jingbo Xu <jefflexu@linux.alibaba.com>
In-Reply-To: <20240409081135.6102-1-hongzhen@linux.alibaba.com>
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On 4/9/24 4:11 PM, Hongzhen Luo wrote:
> Use the superblock's UUID to generate the fsid when it's non-null.
> 
> Signed-off-by: Hongzhen Luo <hongzhen@linux.alibaba.com>
> ---
>  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);

How about

	buf->f_fsid = uuid_to_fsid(sb->s_uuid.b);

which looks cleaner.

Otherwise LGTM.

Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>


-- 
Thanks,
Jingbo