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Subject: Re: [PATCH RFC v3 for-6.8/block 02/17] xen/blkback: use bdev api in
 xen_update_blkif_status()
To: Jan Kara <jack@suse.cz>, Yu Kuai <yukuai1@huaweicloud.com>
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 <20240104110631.3vspsvxbbvcpdqdu@quack3>
From: Yu Kuai <yukuai1@huaweicloud.com>
Message-ID: <29bfcfc7-62b0-3876-78ce-f7ebe3506eb6@huaweicloud.com>
Date: Thu, 4 Jan 2024 20:19:05 +0800
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Hi, Jan!

?? 2024/01/04 19:06, Jan Kara д??:
> On Thu 21-12-23 16:56:57, Yu Kuai wrote:
>> From: Yu Kuai <yukuai3@huawei.com>
>>
>> Avoid to access bd_inode directly, prepare to remove bd_inode from
>> block_devcie.
>>
>> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
>> ---
>>   drivers/block/xen-blkback/xenbus.c | 3 +--
>>   1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
>> index e34219ea2b05..e645afa4af57 100644
>> --- a/drivers/block/xen-blkback/xenbus.c
>> +++ b/drivers/block/xen-blkback/xenbus.c
>> @@ -104,8 +104,7 @@ static void xen_update_blkif_status(struct xen_blkif *blkif)
>>   		xenbus_dev_error(blkif->be->dev, err, "block flush");
>>   		return;
>>   	}
>> -	invalidate_inode_pages2(
>> -			blkif->vbd.bdev_handle->bdev->bd_inode->i_mapping);
>> +	invalidate_bdev(blkif->vbd.bdev_handle->bdev);
> 
> This function uses invalidate_inode_pages2() while invalidate_bdev() ends
> up using mapping_try_invalidate() and there are subtle behavioral
> differences between these two (for example invalidate_inode_pages2() tries
> to clean dirty pages using the ->launder_folio method). So I think you'll
> need helper like invalidate_bdev2() for this.

Thanks for reviewing this patch, I know the differenct between then,
what I don't understand is that why using invalidate_inode_pages2()
here. sync_blockdev() is just called and 0 is returned, I think in this
case it's safe to call invalidate_bdev() directly, or am I missing
other things?

Thanks,
Kuai

> 
> 								Honza
>