Re: [Qemu-block] [PATCH v2 09/13] block: Add a 'mutable_opts' field to BlockDriver

[Alberto Garcia]

On Tue 12 Mar 2019 01:32:00 PM CET, Kevin Wolf wrote:
> Am 06.03.2019 um 19:11 hat Alberto Garcia geschrieben:
>> If we reopen a BlockDriverState and there is an option that is present
>> in bs->options but missing from the new set of options then we have to
>> return an error unless the driver is able to reset it to its default
>> value.
>> 
>> This patch adds a new 'mutable_opts' field to BlockDriver. This is
>> a list of runtime options that can be modified during reopen. If an
>> option in this list is unspecified on reopen then it must be reset (or
>> return an error).
>> 
>> Signed-off-by: Alberto Garcia <address@hidden>
>> ---
>>  block/file-posix.c        |  6 ++++++
>>  block/qcow2.c             | 25 +++++++++++++++++++++++++
>>  block/raw-format.c        |  3 +++
>>  include/block/block_int.h |  8 ++++++++
>>  4 files changed, 42 insertions(+)
>
> Two more drivers seem to be able to change options: gluster (debug and
> logfile) and throttle (throttle-group).

Unless I missed something gluster doesn't allow changing any options
during reopen, the _reopen_prepare() function only reads the flags.

The 'throttle-group' option is mandatory so it cannot be left unset. We
can add mutable_opts to that driver but it won't make any difference in
practice.

Berto