oxenstored: exempt dom0 from domU node quotas

If a domU has exhausted its quota we still want the toolstack in dom0 to
be able to create new nodes in places like
  /local/domain/%d/control/shutdown

Without this patch, a domU which has exhausted its quota can only be
powered off, which is not as good as being able to request a clean
shutdown.

Reported-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Sanders <thomas.sanders@citrix.com>
Signed-off-by: Euan Harris <euan.harris@citrix.com>
Acked-by: David Scott <dave.scott@citrix.com>

diff --git a/tools/ocaml/xenstored/store.ml b/tools/ocaml/xenstored/store.ml
index cac0b44ddf9ee5673c58f6beb9487df29d2ffe1c..3efe515dcc2a8843eb4024299d3a6f9d94e039ed 100644 (file)
--- a/tools/ocaml/xenstored/store.ml
+++ b/tools/ocaml/xenstored/store.ml
@@ -383,7 +383,7 @@ let set_node store path node =
 let write store perm path value =
        let node, existing = get_deepest_existing_node store path in
        let owner = Node.get_owner node in
-       if existing then
+       if existing || (Perms.Connection.is_dom0 perm) then
                (* Only check the string length limit *)
                Quota.check store.quota (-1) (String.length value)
        else
@@ -398,7 +398,7 @@ let mkdir store perm path =
        let node, existing = get_deepest_existing_node store path in
        let owner = Node.get_owner node in
        (* It's upt to the mkdir logic to decide what to do with existing path *)
-       if not existing then Quota.check store.quota owner 0;
+       if not (existing || (Perms.Connection.is_dom0 perm)) then Quota.check store.quota owner 0;
        store.root <- path_mkdir store perm path;
        Quota.add_entry store.quota owner
 
@@ -416,7 +416,7 @@ let setperms store perm path nperms =
        | Some node ->
                let old_owner = Node.get_owner node in
                let new_owner = Perms.Node.get_owner nperms in
-               if old_owner <> new_owner then Quota.check store.quota new_owner 0;
+               if not ((old_owner = new_owner) || (Perms.Connection.is_dom0 perm)) then Quota.check store.quota new_owner 0;
                store.root <- path_setperms store perm path nperms;
                Quota.del_entry store.quota old_owner;
                Quota.add_entry store.quota new_owner