Re: [Qemu-block] [Qemu-devel] [PATCH] block/rbd: add .bdrv_reopen_prepare() stub

[Jason Dillaman]

On Wed, May 18, 2016 at 4:19 AM, Kevin Wolf <address@hidden> wrote:
>> Updating this setting on an open image won't do anything, but if you
>> rbd_close() and rbd_open() it again the setting will take effect.
>> rbd_close() will force a flush of any pending I/O in librbd and
>> free the memory for librbd's ImageCtx, which may or may not be desired
>> here.
>
> First rbd_close() and then rbd_open() risks that the rbd_open() fails
> and we end up with no usable image at all. Can we open a second instance
> of the image first and only close the first one if that succeeded?
>
> We already flush all requests before calling this, so that part
> shouldn't make a difference.


You can open the same image twice without issue.  It's perfectly fine
to rbd_open() with the new settings and upon success rbd_close() the
original image handle.

-- 
Jason