On 2018-05-09 23:00, Max Reitz wrote:
> [Unchanged text from v1 ahead]
> 
> Currently, "qemu-img amend -f $format -o help" prints many things which
> it claims to be supported, but most of the time it's wrong.  Usually
> that starts with the format already: No format but qcow2 supports option
> amendment, so we should never claim that a format supports any options
> when it actually does not support amendment in the first place.
> 
> It goes on with the options themselves.  The qcow2 driver does not
> support amendment of all creation options, so we should not claim it
> does.  Actually knowing which formats are supported exactly would be a
> bit difficult (this would probably involve adding a field to
> QemuOptDesc, and I don't really want to do that), but what we can do
> instead is to at least advise the user that the options we print are all
> of the creation options and that we might not support amending all of
> them.
> 
> There is a Bugzilla for this here:
> https://bugzilla.redhat.com/show_bug.cgi?id=1537956
> 
> On the way to address these issues, there is more to be done, though.
> bdrv_amend_options() does not have an Error parameter yet, and there is
> no real excuse for that.
> 
> Also, "qemu-img create -o help" has its own little issue with formats
> that do not support creation:
> 
>     $ qemu-img create -f bochs -o help
>     Supported options:
>     qemu-img: util/qemu-option.c:219:
>     qemu_opts_print_help: Assertion `list' failed.
>     [1]    24831 abort (core dumped)  qemu-img create -f bochs -o help
> 
> Let's fix that, too.
> 
> 
> v2:
> - Patch 2: [Eric]
>   - Use error_setg_errno() where possible
>   - Use assertions instead of error messages where that makes sense
>   - Rephrase an error message since we're already touching it
> 
> 
> git-backport-diff against v1:
> 
> Key:
> [----] : patches are identical
> [####] : number of functional differences between upstream/downstream patch
> [down] : patch is downstream-only
> The flags [FC] indicate (F)unctional and (C)ontextual differences, respectively
> 
> 001/7:[----] [--] 'qemu-img: Amendment support implies create_opts'
> 002/7:[0042] [FC] 'block: Add Error parameter to bdrv_amend_options'
> 003/7:[----] [--] 'qemu-option: Pull out "Supported options" print'
> 004/7:[----] [--] 'qemu-img: Add print_amend_option_help()'
> 005/7:[----] [--] 'qemu-img: Recognize no creation support in -o help'
> 006/7:[----] [--] 'iotests: Test help option for unsupporting formats'
> 007/7:[----] [--] 'iotests: Rework 113'
> 
> 
> Max Reitz (7):
>   qemu-img: Amendment support implies create_opts
>   block: Add Error parameter to bdrv_amend_options
>   qemu-option: Pull out "Supported options" print
>   qemu-img: Add print_amend_option_help()
>   qemu-img: Recognize no creation support in -o help
>   iotests: Test help option for unsupporting formats
>   iotests: Rework 113
> 
>  include/block/block.h      |  3 +-
>  include/block/block_int.h  |  3 +-
>  block.c                    |  8 ++++--
>  block/qcow2.c              | 72 ++++++++++++++++++++++++++--------------------
>  qemu-img.c                 | 52 +++++++++++++++++++++++++++++----
>  util/qemu-option.c         |  1 -
>  tests/qemu-iotests/060.out |  4 +--
>  tests/qemu-iotests/061.out |  7 -----
>  tests/qemu-iotests/080.out |  4 +--
>  tests/qemu-iotests/082     |  9 ++++++
>  tests/qemu-iotests/082.out | 53 +++++++++++++++++++++++-----------
>  tests/qemu-iotests/112.out |  3 --
>  tests/qemu-iotests/113     | 19 ++++++------
>  tests/qemu-iotests/113.out |  7 +++--
>  14 files changed, 159 insertions(+), 86 deletions(-)

Applied to my block branch.

Max