Re: Is it safe to mount subvolumes of already-mounted volumes (even with different options)?

[Sebastian Ochmann <ochmann@informatik.uni-bonn.de>]

Hello,

I need to clarify, I'm _not_ sharing a drive between multiple computers 
at the _same_ time. It's a portable device which I use at different 
locations with different computers. I just wanted to give a rationale 
for mounting the whole drive to some mountpoint and then also part of 
that drive (a subvolume) to the respective computer's /home mountpoint. 
So it's controlled by the same kernel in the same computer, it's just 
that part of the filesystem is mounted at multiple mountpoints, much 
like a bind-mount, but I'm interested in mounting a subvolume of the 
already-mounted volume to some other mountpoint. Sorry for the confusion.

Best regards
Sebastian


On 17.07.2014 01:18, Chris Murphy wrote:
>
> On Jul 16, 2014, at 4:18 PM, Sebastian Ochmann <ochmann@informatik.uni-bonn.de> wrote:
>
>> Hello,
>>
>> I'm sharing a btrfs-formatted drive between multiple computers and each of the machines has a separate home directory on that drive.
>
> 2+ computers writing to the same block device? I don't see how this is safe. Seems possibly a bug that the 1st mount event isn't setting some metadata so that another kernel instance knows not to allow another mount.
>
>
> Chris Murphy
>