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);
 
 	for (i = 0; i < blkif->nr_rings; i++) {
 		ring = &blkif->rings[i];
-- 
2.39.2

On Tue, Dec 05, 2023 at 08:37:16PM +0800, Yu Kuai wrote:
> 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);

blkbak is a bdev exported.   I don't think it should ever call
invalidate_inode_pages2, through a wrapper or not.

Hi,

在 2023/12/06 13:55, Christoph Hellwig 写道:
> On Tue, Dec 05, 2023 at 08:37:16PM +0800, Yu Kuai wrote:
>> 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);
> 
> blkbak is a bdev exported.   I don't think it should ever call
> invalidate_inode_pages2, through a wrapper or not.

I'm not sure about this. I'm not familiar with xen/blkback, but I saw
that xen-blkback will open a bdev from xen_vbd_create(), hence this
looks like a dm/md for me, hence it sounds reasonable to sync +
invalidate the opened bdev while initialization. Please kindly correct
me if I'm wrong.

Thanks,
Kuai

> 
> .
> 

On Wed, Dec 06, 2023 at 02:56:05PM +0800, Yu Kuai wrote:
> > > -	invalidate_inode_pages2(
> > > -			blkif->vbd.bdev_handle->bdev->bd_inode->i_mapping);
> > > +	invalidate_bdev(blkif->vbd.bdev_handle->bdev);
> > 
> > blkbak is a bdev exported.   I don't think it should ever call
> > invalidate_inode_pages2, through a wrapper or not.
> 
> I'm not sure about this. I'm not familiar with xen/blkback, but I saw
> that xen-blkback will open a bdev from xen_vbd_create(), hence this
> looks like a dm/md for me, hence it sounds reasonable to sync +
> invalidate the opened bdev while initialization. Please kindly correct
> me if I'm wrong.

I guess we have enough precedence for this, so the switchover here
isn't wrong.  But all this invalidating of the bdev cache seems to
be asking for trouble.