Re: [Qemu-devel] [PATCH RFC] blkdebug: make the fault injection functionality callable from QMP

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Wed, Aug 13, 2014 at 01:48:41PM +0900, Hitoshi Mitake wrote:
> @@ -485,6 +493,10 @@ static BlockDriverAIOCB *blkdebug_aio_readv(BlockDriverState *bs,
>      BDRVBlkdebugState *s = bs->opaque;
>      BlkdebugRule *rule = NULL;
>  
> +    if (s->qmp_fault_state != BLOCK_FAULT_STATE_NONE) {
> +        return inject_error(bs, cb, opaque, rule);
> +    }
> +
>      QSIMPLEQ_FOREACH(rule, &s->active_rules, active_next) {
>          if (rule->options.inject.sector == -1 ||
>              (rule->options.inject.sector >= sector_num &&

A QMP command is a good idea but the hardcoded s->qmp_fault_state error
injection is much less powerful than the rules that blkdebug already
supports.

Can you make the QMP command take a list of rules instead of setting
s->qmp_fault_state?

For example:

  # Clear all rules
  blkdebug-set-rules drive0 []

  # Return EIO on disk flush after L1 update
  blkdebug-set-rules drive0 [
    {"type": "set-state",
     "event": "BLKDBG_L1_UPDATE",
     "state": 0,
     "new-state" 1}
    {"type": "inject-error",
     "state": 1,
     "event": "BLKDBG_FLUSH_TO_DISK",
     "errno": "EIO",
     "once": true},
  ]

In other words, instead of adding a new (more limited) mechanism for
triggering error injection, please make the QMP command install a list
of blkdebug rules.

Stefan

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