diff mbox series

[-next,RFC,02/14] xen/blkback: use bdev api in xen_update_blkif_status()

Message ID 20231205123728.1866699-3-yukuai1@huaweicloud.com (mailing list archive)
State Superseded
Headers show
Series block: don't access bd_inode directly from other modules | expand

Commit Message

Yu Kuai Dec. 5, 2023, 12:37 p.m. UTC 
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(-)

Comments

Christoph Hellwig Dec. 6, 2023, 5:55 a.m. UTC | #1 
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.
Yu Kuai Dec. 6, 2023, 6:56 a.m. UTC | #2 
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

> 
> .
>
Christoph Hellwig Dec. 6, 2023, 7:21 a.m. UTC | #3 
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.
diff mbox series

Patch

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];