linux-kernel - Re: [PATCH] erofs: set SB_NODEV sb

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Message-ID: <47247f78-eafb-cb4f-495f-e91a647c3f3c@huawei.com>
Date: Wed, 17 Apr 2024 11:26:18 +0800
From: Baokun Li <libaokun1@...wei.com>
To: Christian Brauner <brauner@...nel.org>, <xiang@...nel.org>
CC: <linux-erofs@...ts.ozlabs.org>, <chao@...nel.org>, <huyue2@...lpad.com>,
	<jefflexu@...ux.alibaba.com>, <viro@...iv.linux.org.uk>,
	<linux-kernel@...r.kernel.org>, <yangerkun@...wei.com>, <houtao1@...wei.com>,
	Baokun Li <libaokun1@...wei.com>
Subject: Re: [PATCH] erofs: set SB_NODEV sb_flags when mounting with fsid

On 2024/4/17 11:11, Gao Xiang wrote:
> On Wed, Apr 17, 2024 at 10:59:53AM +0800, Baokun Li wrote:
>> On 2024/4/16 22:49, Gao Xiang wrote:
>>> On Tue, Apr 16, 2024 at 02:35:08PM +0200, Christian Brauner wrote:
>>>>>> I'm not sure how to resolve it in EROFS itself, anyway...
>>>> Instead of allocating the erofs_sb_info in fill_super() allocate it
>>>> during erofs_get_tree() and then you can ensure that you always have the
>>>> info you need available during erofs_kill_sb(). See the appended
>>>> (untested) patch.
>>> Hi Christian,
>>>
>>> Yeah, that is a good way I think.  Although sbi will be allocated
>>> unconditionally instead but that is minor.
>>>
>>> I'm on OSSNA this week, will test this patch more when returning.
>>>
>>> Hi Baokun,
>>>
>>> Could you also check this on your side?
>>>
>>> Thanks,
>>> Gao Xiang
>> Hi Xiang,
>>
>> This patch does fix the initial problem.
>>
>>
>> Hi Christian,
>>
>> Thanks for the patch, this is a good idea. Just with nits below.
>> Otherwise feel free to add.
>>
>> Reviewed-and-tested-by: Baokun Li <libaokun1@...wei.com>
>>>>   From e4f586a41748b6edc05aca36d49b7b39e55def81 Mon Sep 17 00:00:00 2001
>>>> From: Christian Brauner <brauner@...nel.org>
>>>> Date: Mon, 15 Apr 2024 20:17:46 +0800
>>>> Subject: [PATCH] erofs: reliably distinguish block based and fscache mode
>>>>
>> SNIP
>>
>>>> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
>>>> index c0eb139adb07..4ed80154edf8 100644
>>>> --- a/fs/erofs/super.c
>>>> +++ b/fs/erofs/super.c
>>>> @@ -581,7 +581,7 @@ static const struct export_operations erofs_export_ops = {
>>>>    static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
>>>>    {
>>>>    	struct inode *inode;
>>>> -	struct erofs_sb_info *sbi;
>>>> +	struct erofs_sb_info *sbi = EROFS_SB(sb);
>>>>    	struct erofs_fs_context *ctx = fc->fs_private;
>>>>    	int err;
>>>> @@ -590,15 +590,10 @@ static int erofs_fc_fill_super(struct super_block *sb, struct fs_context *fc)
>>>>    	sb->s_maxbytes = MAX_LFS_FILESIZE;
>>>>    	sb->s_op = &erofs_sops;
>>>> -	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
>>>> -	if (!sbi)
>>>> -		return -ENOMEM;
>>>> -
>>>>    	sb->s_fs_info = sbi;
>> This line is no longer needed.
>>>>    	sbi->opt = ctx->opt;
>>>>    	sbi->devs = ctx->devs;
>>>>    	ctx->devs = NULL;
>>>> -	sbi->fsid = ctx->fsid;
>>>>    	ctx->fsid = NULL;
>>>>    	sbi->domain_id = ctx->domain_id;
>>>>    	ctx->domain_id = NULL;
>> Since erofs_sb_info is now allocated in erofs_fc_get_tree(), why not
>> encapsulate the above lines as erofs_ctx_to_info() helper function
>> to be called in erofs_fc_get_tree()？Then erofs_fc_fill_super() wouldn't
>> have to use erofs_fs_context and would prevent the fsid from being
>> freed twice.
> Hi Baokun,
>
> I'm not sure if Christian has enough time to polish the whole
> codebase (I'm happy if do so).  Basically, that is just a hint
> to the issue, if you have more time, I guess you could also help
> revive this patch together (also because you also have a real
> EROFS test environment).
>
> Let me also check this next week after OSSNA travelling.
>
> Thanks,
> Gao Xiang

Hi Xiang,

Ok, then I will polish the patch and send it out as a v2.

Thanks,
Baokun