Re: [Qemu-devel] [PATCH v4] Stop VM on ENOSPC error.

[Gleb Natapov]

On Tue, Jan 20, 2009 at 02:01:21PM +0000, Ian Jackson wrote:
> Gleb Natapov writes ("[Qemu-devel] [PATCH v4] Stop VM on ENOSPC error."):
> > This version of the patch adds new option "werror" to -drive flag.
> > Possible values are:
> > 
> > report    - report errors to a guest as IO errors
> > ignore    - continue as if nothing happened
> > stop      - stop VM on any error and retry last command on resume
> > enospc    - stop vm on ENOSPC error and retry last command on resume
> >             all other errors are reported to a guest.
> 
> Great, thanks.
> 
> Are we sure that the ide layer is the right place to do this ?
> Perhaps it would be better to do it in block.c.  That way it would
> seamlessly affect scsi too and other kinds of weird block devices
> on other platforms.
> 
> That way the ide code can remain oblivious.
> 
> What do you think ?
> 
I thought about it and I see only two places where this can be done. In
ide/scsi/pv-block layer or in individual block implementations
(qcow,raw, etc). The problem doing it in generic block.c layer is that
how should it handle errors during blocking writes? It can't return
error to the caller and it can't wait inside the function. Doing this in
the ide layer allows for error handling flexibility that this patch
provides.

--
                        Gleb.