Re: [Qemu-block] [PATCH 6/9] file-posix: Forbid trying to change unsupported options during reopen

[Alberto Garcia]

On Wed 29 Aug 2018 01:33:13 PM CEST, Max Reitz wrote:
> On 2018-08-26 16:09, Alberto Garcia wrote:
>> The file-posix code is used for the "file", "host_device" and
>> "host_cdrom" drivers, and it allows reopening images. However the only
>> option that is actually processed is "x-check-cache-dropped", and
>> changes in all other options (e.g. "filename") are silently ignored:
>> 
>>    (qemu) qemu-io virtio0 "reopen -o file.filename=no-such-file"
>> 
>> While we could allow changing some of the other options, let's keep
>> things as they are for now but return an error if the user tries to
>> change any of them.
>> 
>> Signed-off-by: Alberto Garcia <address@hidden>
>> ---
>>  block/file-posix.c | 9 +++++++--
>>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> Looks OK, but the same question from the last patch arises.  If
> unspecified options mean using the default, shouldn't the user have to
> re-specify all mandatory options, so at least @filename in this case?

This is the old (existing) reopen command, which takes the current
options and applies the user-specified changes on top. In this one we
can leave options out because the old values are kept.

It's in the new QMP blockdev-reopen command (not in this series yet)
that you need to specify all options (among other things because it
takes a BlockdevOptions struct, so there's no choice not to specify the
mandatory ones).

Berto