Re: option to mount read-only subvolume with read-write access

[Eric Levy <contact@ericlevy.name>]

On Thu, Nov 10 2022 at 11:46:38 AM -0500, Matthew Warren 
<matthewwarren101010@gmail.com> wrote:
>>  In some scenarios, upcoming changes to a file tree, intended to 
>> become
>>  the default mounts in future boot sessions, will be staged in a 
>> closed
>>  environment, which may include use of "chroot". It is helpful for 
>> the
>>  subvolume to be read-write in the environment created by temporary
>>  mount points, but still protected from accidental modification 
>> through
>>  its physical location on the root tree.
> 
> I think for that situation you'd want to make a snapshot of the
> subvolume (which is currently mounted read-only) and then modify it.
> You can then make the new subvolume have the name of the old
> subvolume. This should allow you to keep the old data in read-only
> until you reboot in which case the new data will be mounted.
> 
> Matthew Warren

It may work as well in many cases, but one limitation is that the child 
volume must reside permanently in the target location, or some other, 
until it replaces the parent volume.