[Qemu-devel] [PATCH v3 0/6]: block: Add I/O status support

[Luiz Capitulino <lcapitulino@redhat.com>]

This series adds support to the block layer to keep track of devices'
I/O status. That information is also made available in QMP and HMP.

The goal here is to allow management applications that miss the
BLOCK_IO_ERROR event to able to query the VM to determine if any device has
caused the VM to stop and which device caused it.

Here's an HMP example:

  (qemu) info status 
  VM status: paused (io-error)
  (qemu) info block
  ide0-hd0: removable=0 io-status=ok file=disks/test2.img ro=0 drv=qcow2 encrypted=0
  ide0-hd1: removable=0 io-status=nospace file=/dev/vg_doriath/kvmtest ro=0 drv=qcow2 encrypted=0
  ide1-cd0: removable=1 locked=0 io-status=ok [not inserted]
  floppy0: removable=1 locked=0 [not inserted]
  sd0: removable=1 locked=0 [not inserted]

The session above shows that the VM is stopped due to an I/O error. By using
the info block command it's possible to determine that the 'ide0-hd1' device
caused the error, which turns out to be due to no space.

changelog
---------

v3

o Introduce bdrv_iostatus_disable()
o Also reset the I/O status on bdrv_attach_dev()
o Fix bad assert() in bdrv_iostatus_enable()
o Improve documentation

v2

o Rebase against latest master
o Renamed bdrv_iostatus_update() to bdrv_iostatus_set_err()
o Minor changelog clarifications

 block.c         |   57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 block.h         |   10 +++++++++
 block_int.h     |    1 +
 hw/ide/core.c   |    2 +
 hw/scsi-disk.c  |    2 +
 hw/virtio-blk.c |    2 +
 monitor.c       |    6 +++++
 qmp-commands.hx |    6 +++++
 8 files changed, 86 insertions(+), 0 deletions(-)