[PATCH proxmox 4/5] pbs-api-types: add WriteNonExpanding datastore operation

[Robert Obkircher <r.obkircher@proxmox.com>]

The new variant will be used for Write operations that should be
allowed in a new GarbageCollection maintenace mode. This name was
chosen over "Prune" because it might also make sense to allow other
administrative tasks that do not actually delete things.

Signed-off-by: Robert Obkircher <r.obkircher@proxmox.com>
---
 pbs-api-types/src/maintenance.rs | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/pbs-api-types/src/maintenance.rs b/pbs-api-types/src/maintenance.rs
index 7e9599be..2d11aff2 100644
--- a/pbs-api-types/src/maintenance.rs
+++ b/pbs-api-types/src/maintenance.rs
@@ -25,14 +25,16 @@ pub const MAINTENANCE_MESSAGE_SCHEMA: Schema =
 pub enum Operation {
     /// for any read operation like backup restore or RRD metric collection
     Read,
-    /// for any write/delete operation, like backup create or GC
+    /// for any read/write/delete operation, like backup create
     Write,
+    /// for read/write/delete operations that reduce or maintain
+    /// storage usage, like GC or prune.
+    WriteNonExpanding,
     /// for any purely logical operation on the in-memory state of the datastore, e.g., to check if
     /// some mutex could be locked (e.g., GC already running?)
     ///
     /// NOTE: one must *not* do any IO operations when only helding this Op state
     Lookup,
-    // GarbageCollect or Delete?
 }
 
 #[api]
@@ -105,7 +107,7 @@ impl MaintenanceMode {
             (MaintenanceType::Offline, _) => bail!("offline maintenance mode: {message}"),
             (MaintenanceType::S3Refresh, _) => bail!("S3 refresh maintenance mode: {message}"),
             (MaintenanceType::ReadOnly, Operation::Read) => Ok(()),
-            (MaintenanceType::ReadOnly, Operation::Write) => {
+            (MaintenanceType::ReadOnly, Operation::Write | Operation::WriteNonExpanding) => {
                 bail!("read-only maintenance mode: {message}")
             }
             #[cfg(feature = "enum-fallback")]
-- 
2.47.3