Re: [PATCH] block/nvme: Do not allow image creation with NVMe block driver

[Kevin Wolf]

Am 17.12.2020 um 17:17 hat Stefan Hajnoczi geschrieben:
> On Mon, Dec 07, 2020 at 06:16:04PM +0100, Philippe Mathieu-Daudé wrote:
> > On 12/4/20 11:28 PM, Philippe Mathieu-Daudé wrote:
> > > On 12/4/20 5:57 PM, Philippe Mathieu-Daudé wrote:
> > >> The NVMe driver does not support image creation.
> > >> The full drive has to be passed to the guest.
> > >>
> > >> Before:
> > >>
> > >>   $ qemu-img create -f raw nvme://0000:04:00.0/1 20G
> > >>   Formatting 'nvme://0000:04:00.0/1', fmt=raw size=21474836480
> > >>
> > >>   $ qemu-img info nvme://0000:04:00.0/1
> > >>   image: nvme://0000:04:00.0/1
> > >>   file format: raw
> > >>   virtual size: 349 GiB (375083606016 bytes)
> > >>   disk size: unavailable
> > 
> > Maybe I should not forbid all formats... But 'raw' is kinda
> > dangerous, as there is no way to enforce the next layer to
> > access beside the size allocated.
> > 
> > Safe drive partitioning can be achieved creating namespaces,
> > feature which is not yet implemented.
> 
> I don't see the need for this patch. Or if there is a need then
> block/file-posix.c, block/iscsi.c, and block/nbd.c should also be
> changed (anything that uses bdrv_co_create_opts_simple()).
> 
> Instead I suggest adding a warning at creation time if a raw format
> image is created on top of a BDS that is larger than requested. The
> warning should remind the user that they need to use the raw format
> drivers's size= open option to restrict the disk capacity when opening
> the image.

This sounds like a good idea to me.

Kevin

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