Re: [Qemu-devel] [PATCH] block: extend BLOCK_IO_ERROR event with nospace indicator

[Eric Blake <eblake@redhat.com>]

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On 08/29/2014 02:07 PM, Luiz Capitulino wrote:
> Management software, such as RHEV's vdsm, want to be able to allocate
> disk space on demand. The basic use case is to start a VM with a small
> disk and then the disk is enlarged when QEMU hits a ENOSPC condition.
> 
> To this end, the management software has to be notified when QEMU
> encounters ENOSPC. The solution implemented by this commit is simple:
> it extends the BLOCK_IO_ERROR with a 'nospace' key, which is true
> when QEMU is stopped due to ENOSPC.
> 
> Note that support for querying this event is already present in
> query-block by means of the 'io-status' key. Also, the new 'nospace'
> BLOCK_IO_ERROR field shares the same semantics with 'io-status',
> which basically means that werror= has to be set to either
> 'stop' or 'enospc' to enable 'nospace'.
> 
> Finally, this commit also updates the 'io-status' key doc in the
> schema with a list of supported device models.
> 
> Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
> ---

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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