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From: Christoph Hellwig <hch@infradead.org>
To: Yu Kuai <yukuai1@huaweicloud.com>
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Subject: Re: [PATCH -next RFC 02/14] xen/blkback: use bdev api in
 xen_update_blkif_status()
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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.