[dm-devel] Re: [PATCH v2 02/17] dm snapshot: add suspended flag to dm_snapshot

[Mike Snitzer]

On Wed, Nov 04 2009 at  7:56pm -0500,
Alasdair G Kergon <agk at redhat.com> wrote:

> On Tue, Oct 20, 2009 at 06:46:50PM -0400, Mike Snitzer wrote:
> > Allow the snapshot target to be able to verify its state relative to a
> > requested operation.  Allows for invalid operations to be prevented,
> > e.g. an attempt handover an "old" snapshot's exceptions without it
> > having been suspended first.
>  
> OK - same as we do in dm-raid1.
> 
> But just be aware that:
>         /* This does not get reverted if there's an error later. */
>         dm_table_presuspend_targets(map);
> 
> and so it's not identical to querying the dm_suspended() property directly.

Right, it is now clear that I should be using postsuspend.  The handover
patch has a need to know that another snapshot target has been
suspended; setting dm-snapshot's 'suspended' in .presuspend doesn't give
us that information.

So the dm-snapshot-track-suspended-state-in-target.patch that you have
queued should be changed with: s/presuspend/postsuspend/

(the same search and replace is needed in the v7 handover patch)

Mike