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Re: [Qemu-devel] [PATCH RFC] blkdebug: make the fault injection function
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH RFC] blkdebug: make the fault injection functionality callable from QMP |
Date: |
Wed, 13 Aug 2014 08:20:53 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.7.0 |
On 08/12/2014 10:48 PM, Hitoshi Mitake wrote:
> This patch makes the fault injection functionality of blkdebug
> callable from QMP. Motivation of this change is for testing and
> debugging distributed systems. Ordinal distributed systems must handle
> hardware faults because of its reason for existence, but testing
> whether the systems can hanle such faults and recover in a correct
> manner is really hard.
>
>
> {"execute": "set-block-fault-state", "arguments": {"id": "ide0-hd0",
> "state": "error"}} # <- inject error to /dev/sda
> {"return": {}}
>
Sounds interesting.
> Now the guest OS on the VM finds the disk is broken.
>
> Of course, using QMP directly is painful for users (developers and
> admins of distributed systems). I'm implementing user friendly
> interface in vagrant-kvm [4] for blackbox testing. In addition, a
> testing framework for injecting faults at critical timing (which
> requires solid understanding of target systems) is in progress.
>
> [1] http://ucare.cs.uchicago.edu/pdf/socc13-limplock.pdf
> [2] http://docs.openstack.org/developer/swift/howto_installmultinode.html
> [3] http://www.amazon.com/dp/B00C93QFHI
> [4] https://github.com/adrahon/vagrant-kvm
>
> Cc: Kevin Wolf <address@hidden>
> Cc: Stefan Hajnoczi <address@hidden>
> Signed-off-by: Hitoshi Mitake <address@hidden>
> ---
> +++ b/qapi-schema.json
> @@ -3481,3 +3481,42 @@
> # Since: 2.1
> ##
> { 'command': 'rtc-reset-reinjection' }
> +
> +##
> +# @BlockFaultState:
> +#
> +# Injected fault state for a block device.
> +#
> +# @none: no fault
> +#
> +# @error: visible error
> +#
Needs a Since: 2.2 line, as well as the ## trailing marker.
> +{ 'enum': 'BlockFaultState', 'data': [ 'none', 'error' ] }
> +
> +##
> +# @query-block-fault-state:
> +#
> +# Return block fault state information for the given block device.
> +#
> +# @name: name of block device
> +#
> +# Returns: @BlockFaultState of a block device.
> +#
> +# Since: 1.6
s/1.6/2.2/
Personally, I think this command is overkill. Just enhance the existing
query-block to output the fault state alongside everything else it
already does. There's no need to add a new command that outputs a
subset of the existing command.
> +##
> +{ 'command': 'query-block-fault-state', 'data': { 'id': 'str' },
> + 'returns': 'BlockFaultState' }
> +##
> +# @set-block-fault-state:
> +#
> +# Set fault state for the given block device.
> +#
> +# @name: the chardev's ID, must exist and not be in use
> +# @state: fault state
> +#
> +# Returns: Nothing on success
> +#
> +# Since: 1.6
s/1.6/2.2/
> +##
> +{ 'command': 'set-block-fault-state', 'data': {'id': 'str',
> + 'state': 'BlockFaultState' }}
> diff --git a/qmp-commands.hx b/qmp-commands.hx
> index 4be4765..96ae7e2 100644
> --- a/qmp-commands.hx
> +++ b/qmp-commands.hx
> @@ -3755,3 +3755,27 @@ Example:
> <- { "return": {} }
>
> EQMP
> + {
> + .name = "query-block-fault-state",
> + .args_type = "id:s",
> + .mhandler.cmd_new = qmp_marshal_input_query_block_fault_state,
> + },
> +
> +SQMP
> +query-block-fault-state
> +-----------------------
> +
> +Show block fault information.
> +
> +EQMP
> + {
> + .name = "set-block-fault-state",
> + .args_type = "id:s,state:q",
> + .mhandler.cmd_new = qmp_marshal_input_set_block_fault_state,
> + },
> +
> +SQMP
> +set-block-fault-state
> +-----------------------
> +
> +Set block fault information.
>
It would be nice to include an example section for the new command(s)
(well, I argue that only one new command is needed).
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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