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

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

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.

>>
>> After:
>>
>>   $ qemu-img create -f raw nvme://0000:04:00.0/1 20G
>>   qemu-img: nvme://0000:04:00.0/1: Protocol driver 'nvme' does not support image creation
>>
>> Fixes: 5a5e7f8cd86 ("block: trickle down the fallback image creation function use to the block drivers")
>> Reported-by: Xueqiang Wei <xuwei@redhat.com>
>> Suggested-by: Max Reitz <mreitz@redhat.com>
> 
> Well Max didn't suggest the change but pointed me to commit 5a5e7f8cd86.
> 
>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>> ---
>> Cc: Maxim Levitsky <mlevitsk@redhat.com>
>> ---
>>  block/nvme.c | 3 ---
>>  1 file changed, 3 deletions(-)
>>
>> diff --git a/block/nvme.c b/block/nvme.c
>> index a06a188d530..73ddf837c2b 100644
>> --- a/block/nvme.c
>> +++ b/block/nvme.c
>> @@ -1515,9 +1515,6 @@ static BlockDriver bdrv_nvme = {
>>      .protocol_name            = "nvme",
>>      .instance_size            = sizeof(BDRVNVMeState),
>>  
>> -    .bdrv_co_create_opts      = bdrv_co_create_opts_simple,
>> -    .create_opts              = &bdrv_create_opts_simple,
>> -
>>      .bdrv_parse_filename      = nvme_parse_filename,
>>      .bdrv_file_open           = nvme_file_open,
>>      .bdrv_close               = nvme_close,
>>
>