Re: [dm-devel] generic wrappers for multi-device FS operations

[Alasdair G Kergon <agk@redhat.com>]

On Tue, Mar 08, 2011 at 10:05:40AM -0800, Wendy Cheng wrote:
> So the "resize" is on the filesystem, not the volume ? The "grow" part
> is probably easy. Unfortunately, the "shrink" may not be easy for some
> of the filesystems:

The LVM situation today works both ways around.

You can use 'lvresize' with an option to resize the filesystem too,
or use 'fsadm' with an option to resize the LV.  We felt that 'fsadm'
was a more-natural approach: allow the user to resize their filesystem 
and automatically adjust the things underneath as necessary.

Long term, we'd like it to be possible to configure a system for resizing
entire device stacks both top down (fsadm) and bottom up (triggered by the
appropriate Unit Attention).
 
(The current fsadm script was written as a proof-of-concept under the
constraint of just wrapping existing binaries. Of course there are cleaner
ways to do it when you allow filesystem-specific code.)

Alasdair