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Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from devic
From: |
Ryan Harper |
Subject: |
Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal |
Date: |
Fri, 5 Nov 2010 11:22:18 -0500 |
User-agent: |
Mutt/1.5.6+20040907i |
* Markus Armbruster <address@hidden> [2010-11-05 11:11]:
> Ryan Harper <address@hidden> writes:
>
> > * Markus Armbruster <address@hidden> [2010-11-05 08:28]:
> >> I'd be fine with any of these:
> >>
> >> 1. A new command "device_disconnet ID" (or similar name) to disconnect
> >> device ID from any host parts. Nice touch: you don't have to know
> >> about the device's host part(s) to disconnect it. But it might be
> >> more work than the other two.
> >
> > This is sort of what netdev_del() and drive_unplug() are today; we're
> > just saying sever the connection of this device id.
>
> No, I have netdev_del as (3).
>
> All three options are "sort of" the same, just different commands with
> a common purpose.
>
> > I'd like to rename drive_unplug() to blockdev_del() and call it done. I
> > was looking at libvirt and the right call to netdev_del is already
> > in-place; I'd just need to re-spin my block patch to call blockdev_del()
> > after invoking device_del() to match what is done for net.
>
> Unless I'm missing something, you can't just rename: your unplug does
> not delete the host part.
>
> >> 2. New commands netdev_disconnect, drive_disconnect (or similar names)
> >> to disconnect a host part from a guest device. Like (1), except you
> >> have to point to the other end of the connection to cut it.
> >
> > What's the advantage here? We need an additional piece of info (host
> > part) in addition to the device id?
>
> That's a disadvantage.
>
> Possible advantage: implementation could be slightly easier than (1),
> because you don't have to find the host parts.
>
> >> 3. A new command "drive_del ID" similar to existing netdev_del. This is
> >> (2) fused with delete. Conceptual wart: you can't disconnect and
> >> keep the host part around. Moreover, delete is slightly dangerous,
> >> because it renders any guest device still using the host part
> >> useless.
> >
> > Hrm, I thought that's what (1) is.
>
> No.
>
> With (1), the argument is a *device* ID, and we disconnect *all* host
> parts connected to this device (typically just one).
>
> With (3), the argument is a netdev/drive ID, and disconnect *this* host
> part from the peer device.
>
> > Well, either (1) or (3); I'd like to
> > rename drive_unplug() to blockdev_del() since they're similar function
> > w.r.t removing access to the host resource. And we can invoke them in
> > the same way from libvirt (after doing guest notification, remove
> > access).
>
> I'd call it drive_del for now, to match drive_add.
OK, drive_del() and as you mentioned, drive_unplug will take out the
block driver, but doesn't remove the dinfo object; that ends up dying
when we call the device destructor. I think for symmetry we'll want
drive_del to remove the dinfo object as well.
--
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
address@hidden
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, (continued)
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Markus Armbruster, 2010/11/03
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Ryan Harper, 2010/11/03
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Michael S. Tsirkin, 2010/11/03
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Ryan Harper, 2010/11/03
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Michael S. Tsirkin, 2010/11/03
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Ryan Harper, 2010/11/04
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Michael S. Tsirkin, 2010/11/04
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Markus Armbruster, 2010/11/05
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Ryan Harper, 2010/11/05
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Markus Armbruster, 2010/11/05
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal,
Ryan Harper <=
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Markus Armbruster, 2010/11/06
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Ryan Harper, 2010/11/07
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Markus Armbruster, 2010/11/08
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Michael S. Tsirkin, 2010/11/08
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Markus Armbruster, 2010/11/08
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Ryan Harper, 2010/11/08
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Michael S. Tsirkin, 2010/11/08
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Daniel P. Berrange, 2010/11/08
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Ryan Harper, 2010/11/08
- Re: [Qemu-devel] [PATCH 0/3] v4 Decouple block device removal from device removal, Ryan Harper, 2010/11/08