[Qemu-devel] [PATCH 0/2] v6 Decouple block device removal from device removal

[Ryan Harper <ryanh@us.ibm.com>]

After *much* discussion, here's version 6.

This patch series decouples the detachment of a block device from the removal
of the backing pci-device.  Removal of a hotplugged pci device requires the
guest to respond before qemu tears down the block device. In some cases, the
guest may not respond leaving the guest with continued access to the block
device.  

The new monitor command, drive_del, will revoke a guests access to the
block device independently of the removal of the pci device.

The first patch implements drive_del and bdrv_unplug, the second patch
implements the qmp version of the monitor command.

Changes since v5:
- Removed dangling pointers in guest and host state.  This ensures things like 
  info block no longer displays the deleted drive; though info pci will
  continue to display the pci device until the guest responds to the removal
  request.
- Renamed drive_unplug -> drive_del
Changes since v4:
- Droppped drive_get_by_id patch and use bdrv_find() instead
- Added additional details about drive_unplug to hmp/qmp interface

Changes since v3:
- Moved QMP command for drive_unplug() to separate patch

Changes since v2:
- Added QMP command for drive_unplug()

Changes since v1:
- CodingStyle fixes
- Added qemu_aio_flush() to bdrv_unplug()

Signed-off-by: Ryan Harper <ryanh@us.ibm.com>