linux-kernel - Re: [PATCH V4 4/6] erofs: introduce a pseudo mnt to manage shared cookies

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Message-ID: <6a716712-4a82-32d7-ddcd-3252f69c6454@linux.alibaba.com>
Date:   Fri, 16 Sep 2022 11:19:02 +0800
From:   JeffleXu <jefflexu@...ux.alibaba.com>
To:     Jia Zhu <zhujia.zj@...edance.com>, linux-erofs@...ts.ozlabs.org
Cc:     linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        yinxin.x@...edance.com
Subject: Re: [PATCH V4 4/6] erofs: introduce a pseudo mnt to manage shared
 cookies



On 9/15/22 8:42 PM, Jia Zhu wrote:

>  static int erofs_init_fs_context(struct fs_context *fc)
>  {
> -	struct erofs_fs_context *ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
> +	struct erofs_fs_context *ctx;
> +

We'd better add a simple comment here:

+	/* pseudo mount for anon inodes */
> +	if (fc->sb_flags & SB_KERNMOUNT) {
> +		fc->ops = &erofs_anon_context_ops;
> +		return 0;
> +	}

which will be more friendly to those not familiar with the background.

>  
> +	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
>  	if (!ctx)
>  		return -ENOMEM;
>  	ctx->devs = kzalloc(sizeof(struct erofs_dev_context), GFP_KERNEL);
> @@ -874,6 +896,11 @@ static void erofs_kill_sb(struct super_block *sb)
>  
>  	WARN_ON(sb->s_magic != EROFS_SUPER_MAGIC);
>  
> +	if (sb->s_flags & SB_KERNMOUNT) {
> +		kill_litter_super(sb);

I think kill_anon_super() is enough. At least in our case, there's only
one root dentry inside the anon super and thus d_genocide() is actually
a noop.


Otherwise LGTM.
Reviewed-by: Jingbo Xu <jefflexu@...ux.alibaba.com>


-- 
Thanks,
Jingbo