Re: [Qemu-devel] [RFC PATCH] block: Fix eject -f for locked devices

[Blue Swirl]

On Fri, Feb 18, 2011 at 5:16 PM, Markus Armbruster <address@hidden> wrote:
> From 8cd4978c9be6ff2bcc414bb1c1b258b96b9a74c1 Mon Sep 17 00:00:00 2001
> From: Markus Armbruster <address@hidden>
> Date: Fri, 18 Feb 2011 15:54:02 +0100
>
> After forcefully ejecting media locked by the guest, you can't ever
> again insert new media.
>
> Example:
>
>    (qemu) info block
>    hda: type=hd removable=0 file=test.img ro=0 drv=raw encrypted=0
>    cd: type=cdrom removable=1 locked=1 file=x.iso ro=0 drv=raw encrypted=0
>    (qemu) eject cd
>    Device 'cd' is locked
>    (qemu) eject -f cd
>    (qemu) info block
>    hda: type=hd removable=0 file=test.img ro=0 drv=raw encrypted=0
>    cd: type=cdrom removable=1 locked=1 [not inserted]
>    (qemu) change cd x.iso
>    Device 'cd' is locked
>
> Signed-off-by: Markus Armbruster <address@hidden>
> ---
> I'm not entirely sure this is the appropriate fix, and that's why
> there's RFC in the subject.
>
> Both IDE and SCSI devices expose their drive's BlockDriverState member
> locked to the guest via mode sense.
>
> What does real hardware do when I force-eject media (typically by
> rummaging in that little hole with a paperclip)?  Does it actively
> notify the OS?  Does mode sense change?

No idea, but IIRC the drive is still usable after that, so locking the
drive does not look correct.

> A possible alternative fix is to make do_change_block() ignore
> bdrv_is_locked() when inserting media into an empty drive.

Then the meaning of locked would change, maybe eject_disabled would
then describe the state better.