[Libguestfs] [PATCHv4 0/2] Introduce vfs_minimum_size API to get minimum filesystem size.

[Maxim Perevedentsev]

On 10/20/2015 08:58 PM, Richard W.M. Jones wrote:
> On Tue, Oct 20, 2015 at 08:56:25PM +0300, Maxim Perevedentsev wrote:
>> I have an issue with btrfs:
>>
>> There's an API
>>> btrfs inspect-internal min-dev-size /sysroot/
>> But this API is available only in btrfs-progs >= 4.2.
>> Before this, there's no reliable way to get minimum size (I could
>> parse "btrfs filesystem show", but it is veeery inaccurate).
>>
>> Can we require btrfs-progs v4.2? Or how should I work-around this issue?
> Well it's a new API, so we can just tell people they need new
> btrfs-progs if they want to use the new API.
>
> It would be a problem if we were changing an old API, but that's not
> the case here.
>
> Rich.
OK. I have another question:

The call for ext works on mounted and unmounted fs.
               for ntfs on read-only-mounted and unmounted.
               for btrfs on mounted (ro and rw).
               for xfs on mounted (ro and rw) (xfs does not support 
shrinking, so guestfs_xfs_info).

Should we require the user to care about fs mount status / do 
mounts/unmounts ourselves (how to choose mountpoint?) / refuse to work 
if fs is not ro-mounted?

I would vote for 1st option: include mount check into functions and 
politely report incompatible mount status to user.

-- 
Your sincerely,
Maxim Perevedentsev