[lvm-devel] snapshot: refactor snapshot-merge deptree and device removal

[Mike Snitzer]

On Mon, Feb 15 2010 at  5:43pm -0500,
Mike Snitzer <snitzer at redhat.com> wrote:

> Add a merging snapshot using the "error" target rather than avoid
> adding it entirely.  This allows proper cleanup of the -cow device
> without having to rename the -cow to use the origin's name as a
> prefix.
> 
> Moved the preloading of the origin LV, after a merge, from
> lv_remove_single() to vg_remove_single().  Having vg_remove_single()
> preload the origin free up the -cow device so that it can be removed
> via deactivate_lv().  This is reliable because the associated snapshot
> LV, that is to be removed when a snapshot-merge completes, is always
> added no to the deptree (and kernel -- via "error" target).
> 
> Now when the snapshot LV is removed both the -cow and -real devices
> get removed using uuid rather than device name.  This paves the way
> for us to switch over to info-by-uuid queries.

I tested this patch with and without Milan's info-by-uuid patches here:
http://mazyland.englab.brq.redhat.com/test-shared/

Mike