[libvirt] [PATCH v5] qemu: call drive_del in DetachPciDiskDevice

[Daniel P. Berrange]

On Fri, Nov 12, 2010 at 12:23:41PM -0600, Ryan Harper wrote:
> Currently libvirt doesn't confirm whether the guest has responded to the
> disk removal request.  In some cases this can leave the guest with
> continued access to the device while the mgmt layer believes that it has
> been removed.  With a recent qemu monitor command[1] we can
> deterministically revoke a guests access to the disk (on the QEMU side)
> to ensure no futher access is permitted.
> 
> This patch adds support for the drive_del() command and introduces it
> in the disk removal paths.  If the guest is running in a QEMU without this
> command we currently explicitly check for unknown command/CommandNotFound
> and log the issue.
> 
> If QEMU supports the command we issue the drive_del command after we attempt
> to remove the device.  The guest may respond and remove the block device
> before we get to attempt to call drive_del.  In that case, we explicitly check
> for 'Device not found' from the monitor indicating that the target drive
> was auto-deleted upon guest responds to the device removal notification.
> 
> 1. http://thread.gmane.org/gmane.comp.emulators.qemu/84745
> 
> Signed-off-by: Ryan Harper <ryanh at us.ibm.com>
> ---
> Changes since v4:
>  - removed PATH_MAX, use virAsprintf()
>  - moved drivestr allocation before call to EnterMonitor
> Changes since v3:
>  - Renamed DriveUnplug -> DriveDel, use drive_del monitor cmd.
>  - Moved invocation to after DelDevice and guest notification.
>  - Handle the case where drive is auto-deleted before we call
>    DriveDel by catching and ignoring 'Device not found' error.
>  - Simplified DriveDel invocation; no need to check return codes
>    as the monitor implementations handle all failure case and logs
>    or ignores as needed.
> Changes since v2:
>  - use VIR_ERROR to report when unplug command not found
> Changes since v1:
>  - return > 0 when command isn't present, < 0 on command failure
>  - detect when drive_unplug command isn't present and log error
>    instead of failing entire command
> 
>  src/qemu/qemu_driver.c       |   28 +++++++++++++++++++++
>  src/qemu/qemu_monitor.c      |   19 ++++++++++++++
>  src/qemu/qemu_monitor.h      |    3 ++
>  src/qemu/qemu_monitor_json.c |   38 +++++++++++++++++++++++++++++
>  src/qemu/qemu_monitor_json.h |    3 ++
>  src/qemu/qemu_monitor_text.c |   54 ++++++++++++++++++++++++++++++++++++++++++
>  src/qemu/qemu_monitor_text.h |    3 ++
>  7 files changed, 148 insertions(+), 0 deletions(-)

ACK, once this drive_del  hits the main QEMU git repos


Daniel
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