linux-kernel - Re: [PATCH v2 2/5] cachefiles: flush all requests for the object that is being dropped

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Message-ID: <e40b80fc-52b8-4f89-800a-3ffa0034a072@huaweicloud.com>
Date: Thu, 27 Jun 2024 19:20:16 +0800
From: Baokun Li <libaokun@...weicloud.com>
To: Jeff Layton <jlayton@...nel.org>
Cc: netfs@...ts.linux.dev, dhowells@...hat.com, hsiangkao@...ux.alibaba.com,
 jefflexu@...ux.alibaba.com, zhujia.zj@...edance.com,
 linux-erofs@...ts.ozlabs.org, linux-fsdevel@...r.kernel.org,
 linux-kernel@...r.kernel.org, yangerkun@...wei.com, houtao1@...wei.com,
 yukuai3@...wei.com, wozizhi@...wei.com, Baokun Li <libaokun1@...wei.com>,
 Baokun Li <libaokun@...weicloud.com>
Subject: Re: [PATCH v2 2/5] cachefiles: flush all requests for the object that
 is being dropped

On 2024/6/27 19:01, Jeff Layton wrote:
> On Wed, 2024-05-15 at 20:51 +0800, libaokun@...weicloud.com wrote:
>> From: Baokun Li <libaokun1@...wei.com>
>>
>> Because after an object is dropped, requests for that object are
>> useless,
>> flush them to avoid causing other problems.
>>
>> This prepares for the later addition of cancel_work_sync(). After the
>> reopen requests is generated, flush it to avoid cancel_work_sync()
>> blocking by waiting for daemon to complete the reopen requests.
>>
>> Signed-off-by: Baokun Li <libaokun1@...wei.com>
>> ---
>>   fs/cachefiles/ondemand.c | 19 +++++++++++++++++++
>>   1 file changed, 19 insertions(+)
>>
>> diff --git a/fs/cachefiles/ondemand.c b/fs/cachefiles/ondemand.c
>> index 73da4d4eaa9b..d24bff43499b 100644
>> --- a/fs/cachefiles/ondemand.c
>> +++ b/fs/cachefiles/ondemand.c
>> @@ -564,12 +564,31 @@ int cachefiles_ondemand_init_object(struct
>> cachefiles_object *object)
>>   
>>   void cachefiles_ondemand_clean_object(struct cachefiles_object
>> *object)
>>   {
>> +	unsigned long index;
>> +	struct cachefiles_req *req;
>> +	struct cachefiles_cache *cache;
>> +
>>   	if (!object->ondemand)
>>   		return;
>>   
>>   	cachefiles_ondemand_send_req(object, CACHEFILES_OP_CLOSE, 0,
>>   			cachefiles_ondemand_init_close_req, NULL);
>> +
>> +	if (!object->ondemand->ondemand_id)
>> +		return;
>> +
>> +	/* Flush all requests for the object that is being dropped.
>> */
> I wouldn't call this a "Flush". In the context of writeback, that
> usually means that we're writing out pages now in order to do something
> else. In this case, it looks like you're more canceling these requests
> since you're marking them with an error and declaring them complete.
Makes sense, I'll update 'flush' to 'cancel' in the comment and subject.

I am not a native speaker of English, so some of the expressions may
not be accurate, thank you for correcting me.

Thanks,
Baokun
>> +	cache = object->volume->cache;
>> +	xa_lock(&cache->reqs);
>>   	cachefiles_ondemand_set_object_dropping(object);
>> +	xa_for_each(&cache->reqs, index, req) {
>> +		if (req->object == object) {
>> +			req->error = -EIO;
>> +			complete(&req->done);
>> +			__xa_erase(&cache->reqs, index);
>> +		}
>> +	}
>> +	xa_unlock(&cache->reqs);
>>   }
>>   
>>   int cachefiles_ondemand_init_obj_info(struct cachefiles_object
>> *object,