Re: [PATCH v2 3/8] docs/designs/xenstore-migration.md: clarify that deletes are recursive

[Edwin Torok <edvin.torok@xxxxxxxxxx>]

On Fri, 2021-01-22 at 14:04 +0100, Jürgen Groß wrote:
> On 15.01.21 23:28, Edwin Török wrote:
> > Signed-off-by: Edwin Török <edvin.torok@xxxxxxxxxx>
> > ---
> > Changed since V1:
> > * post publicly now that the XSA is out
> > ---
> >   docs/designs/xenstore-migration.md | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/docs/designs/xenstore-migration.md
> > b/docs/designs/xenstore-migration.md
> > index 2ce2c836f5..f44bc0c61d 100644
> > --- a/docs/designs/xenstore-migration.md
> > +++ b/docs/designs/xenstore-migration.md
> > @@ -365,7 +365,8 @@ record previously present).
> >   |              | 0x0001: read                                   |
> >   |              | 0x0002: written                                |
> >   |              |                                                |
> > -|              | The value will be zero for a deleted node      |
> > +|              | The value will be zero for a recursively       |
> > +|              | deleted node                                   |
> 
> I don't see the value in this modification.
> 
> The wording is ambiguous: is the value zero only for nodes which were
> deleted due to recursion, or do you mean deletes are recursive?

I was looking at this from the point of view of generating the diff,
where you can optimize and reduce the size of the diff if you notice
that it is sufficient to add a record only for the topmost entry when
the entire subtree is deleted.

You are right that looking at it from the point of view of applying the
transaction record you would reuse the existing delete implementation
which is already recursive.

> 
> Per docs/misc/xenstore.txt all deletes are recursive, so there is no
> need to repeat that here. And a zero value only for the recursions
> makes
> no sense at all.
> 
> So I'd nack this patch.

We can drop it.
--Edwin
> 
> Juergen