Re: [Qemu-devel] [PATCH 2/7] block: Framework for reopening files safely

[Kevin Wolf <kwolf@redhat.com>]

Am 11.09.2012 16:57, schrieb Jeff Cody:
> On 08/30/2012 02:47 PM, Jeff Cody wrote:
>> This is based heavily on Supriya Kannery's bdrv_reopen()
>> patch series.
>>
>> This provides a transactional method to reopen multiple
>> images files safely.
>>
>> Image files are queue for reopen via bdrv_reopen_queue(), and the
>> reopen occurs when bdrv_reopen_multiple() is called.  Changes are
>> staged in bdrv_reopen_prepare() and in the equivalent driver level
>> functions.  If any of the staged images fails a prepare, then all
>> of the images left untouched, and the staged changes for each image
>> abandoned.
>>
> 
> Open question (my assumption is yes):
> 
> Is it safe to assume that reopen() should always enable BDRV_O_CACHE_WB
> (without affecting enable_write_cache), so as to not undo what was done
> by Paolo's commit e1e9b0ac?

I think it makes sense to behave the same as bdrv_open_common(), so I
guess yes. But now I'm wondering if we also need other code from there,
like filtering out BDRV_O_SNAPSHOT/NO_BACKING etc.

Kevin