Re: [Qemu-devel] [PATCH 0/3] blockdev: Add read-only option to change-blockdev

[Kevin Wolf <kwolf@redhat.com>]

Am 20.11.2014 um 13:44 hat Max Reitz geschrieben:
> The 'change' QMP and HMP command allows replacing the medium in drives
> which support this, e.g. floppy disk drives. For some drives, the medium
> carries information about whether it can be written to or not (again,
> floppy drives). Therefore, it should be possible to change the read-only
> state of block devices when changing the loaded medium.
> 
> This series adds an optional additional parameter to the 'change' QMP
> and HMP command which allows changing the read-only state in four ways:
> 
> - 'retain': Just keep the status as it was before; this is the current
>   behavior and thus this will be the default.
> - 'ro': Force read-only access
> - 'rw': Force writable access
> - 'auto': This opens the new file R/W first, if that fails, the file is
>   opened read-only.

Not sure if 'auto' is worth implementing (it's a typical HMP default
action that no QMP client would use, except that it isn't even the
default for HMP), but the implementation looks correct at least.

Reviewed-by: Kevin Wolf <kwolf@redhat.com>