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Date: Thu, 7 Nov 2019 10:55:54 +0100
From: Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 2/5] block: merge invalidate_partitions into
 rescan_partitions
Message-ID: <20191107095554.GA11283@lst.de>
References: <20191106151439.30056-1-hch@lst.de> <20191106151439.30056-3-hch@lst.de> <f95d65cb-f864-5cfe-1161-4f940a59f38e@suse.de>
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To: Hannes Reinecke <hare@suse.de>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>, Jan Kara <jack@suse.cz>, linux-block@vger.kernel.org, linux-s390@vger.kernel.org

On Thu, Nov 07, 2019 at 10:47:39AM +0100, Hannes Reinecke wrote:
> > +	check_disk_size_change(disk, bdev, !invalidate);
> >  	bdev->bd_invalidated = 0;
> >  
> > -	if (!get_capacity(disk))
> > +	if (!get_capacity(disk)) {
> > +		/*
> > +		 * Tell userspace that the media / partition table may have
> > +		 * changed.
> > +		 */
> > +		kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
> >  		return 0;
> > +	}
> >  	
> I wonder; wouldn't we miss a true size change here?

Why would we?  We first unconditionally drop all partitions.  Then if
the device ha a non-zero capacity we probe for partitions.  What could
we miss?