Re: [Xen-devel] [PATCH] xen-blkfront: emit KOBJ_OFFLINE uevent when detaching device

[Vincent Legout <vincent.legout@gandi.net>]

On Wed, Jul 05, 2017 at 06:53:25AM -0600, Jan Beulich wrote :
> >>> On 05.07.17 at 14:37, <vincent.legout@gandi.net> wrote:
> > On Wed, Jul 05, 2017 at 02:17:24AM -0600, Jan Beulich wrote :
> >> >>> On 05.07.17 at 10:08, <vincent.legout@gandi.net> wrote:
> >> > Without the patch, blkif_release and xlvbd_release_gendisk are never
> >> > called, and no call to blk_unregister_queue is made.
> >> 
> >> But isn't that what needs to be fixed then? The device should be
> >> removed once its last user goes away (which would be at the time
> >> the umount is eventually done aiui).
> > 
> > You mean that block-detach should fail if the device is still mounted?
> > or find a way to wait until all the users are gone?
> > 
> > I don't say that's not what should be done, but that's not what I get.
> > The device is removed after a block-detach, even if still mounted. So
> > the system is left in an unstable state without the patch.
> 
> Unstable? I'd expect subsequent I/O to fail for that device, yes, but
> that's still a stable system. Are you observing anything else?

Yes, that's what I meant by unstable, nothing else. Sorry for the
confusion.

Vincent