Fix instance>path to contain unit address for wildcard nodes

instance>path (and instance>qpath) which are used among others by
the client interface "instance-to-path" are broken when dealing
with wildcard nodes (node with no unit address which obtain one
when opened).

This fixes this by properly using the instance address when building
instance path.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

slof/fs/node.fs

@@ -216,6 +216,22 @@ CREATE $indent 100 allot  VARIABLE indent 0 indent !
    THEN
 ;
 
+: $cat-instance-unit
+   dup parent 0= IF drop EXIT THEN
+   dup instance>#units 0= IF drop EXIT THEN
+   dup >r push-my-self
+   ['] my-unit CATCH IF pop-my-self r> drop EXIT THEN
+   pop-my-self
+   s" encode-unit"
+   r> ihandle>phandle parent
+   $call-static
+   dup IF
+      dup >r here swap move s" @" $cat here r> $cat
+   ELSE
+      2drop
+   THEN
+;
+
 \ Getting basic info about a node.
 : node>name  dup >r s" name" rot get-property IF r> (u.) ELSE 1- r> drop THEN ;
 : node>qname dup node>name rot ['] $cat-unit CATCH IF drop THEN ;
@@ -238,9 +254,15 @@ CREATE $indent 100 allot  VARIABLE indent 0 indent !
   \ open-dev and friends, if there were no interposition.
   dup instance>parent @ dup 0= IF 2drop false EXIT THEN
   ihandle>phandle swap ihandle>phandle parent <> ;
-: instance>qname  dup >r interposed? IF s" %" ELSE 0 0 THEN
-                  r@ ihandle>phandle node>qname $cat  r> instance>args 2@
-                  dup IF 2>r s" :" $cat 2r> $cat ELSE 2drop THEN ;
+
+: instance>qname
+  dup >r interposed? IF s" %" ELSE 0 0 THEN
+  r@ dup ihandle>phandle node>name
+  rot ['] $cat-instance-unit CATCH IF drop THEN
+  $cat r> instance>args 2@
+  dup IF 2>r s" :" $cat 2r> $cat ELSE 2drop THEN
+;
+
 : instance>qpath \ With interposed nodes.
   here 0 rot BEGIN dup WHILE dup instance>parent @ REPEAT 2drop
   dup 0= IF [char] / c, THEN