linux-kernel - Re: [PATCH v9 03/21] cachefiles: unbind cachefiles gracefully in on-demand mode

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Date:   Fri, 22 Apr 2022 10:44:19 +0800
From:   JeffleXu <jefflexu@...ux.alibaba.com>
To:     David Howells <dhowells@...hat.com>
Cc:     linux-cachefs@...hat.com, xiang@...nel.org, chao@...nel.org,
        linux-erofs@...ts.ozlabs.org, torvalds@...ux-foundation.org,
        gregkh@...uxfoundation.org, willy@...radead.org,
        linux-fsdevel@...r.kernel.org, joseph.qi@...ux.alibaba.com,
        bo.liu@...ux.alibaba.com, tao.peng@...ux.alibaba.com,
        gerry@...ux.alibaba.com, eguan@...ux.alibaba.com,
        linux-kernel@...r.kernel.org, luodaowen.backend@...edance.com,
        tianzichen@...ishou.com, fannaihao@...du.com,
        zhangjiachen.jaycee@...edance.com
Subject: Re: [PATCH v9 03/21] cachefiles: unbind cachefiles gracefully in
 on-demand mode



On 4/21/22 10:02 PM, David Howells wrote:
> Jeffle Xu <jefflexu@...ux.alibaba.com> wrote:
> 
>> +	struct kref			unbind_pincount;/* refcount to do daemon unbind */
> 
> Please use refcount_t or atomic_t, especially as this isn't the refcount for
> the structure.

Okay, will be done in the next version.

> 
>> -	cachefiles_daemon_unbind(cache);
>> -
>>  	/* clean up the control file interface */
>>  	cache->cachefilesd = NULL;
>>  	file->private_data = NULL;
>>  	cachefiles_open = 0;
> 
> Please call cachefiles_daemon_unbind() before the cleanup.

Since the cachefiles_struct struct will be freed once the pincount is
decreased to 0, "cache->cachefilesd = NULL;" needs to be done before
decreasing the pincount. BTW, "cachefiles_open = 0;" indeed should be
done only when pincount has been decreased to 0.


-- 
Thanks,
Jeffle