fix(pageserver): ensure initial image layers have correct key ranges

Signed-off-by: Alex Chi Z <chi@neon.tech>

pageserver/src/tenant/timeline.rs

@@ -3781,35 +3781,31 @@ impl Timeline {
                 return Err(FlushLayerError::Cancelled);
             }
 
+            // Ensure that we have a single call to `create_image_layers` with a combined dense keyspace.
+            // So that the key ranges don't overlap.
+            let mut partitions = KeyPartitioning::default();
+            partitions.parts.extend(rel_partition.parts);
+            if !metadata_partition.parts.is_empty() {
+                assert_eq!(
+                    metadata_partition.parts.len(),
+                    1,
+                    "currently sparse keyspace should only contain a single metadata keyspace"
+                );
+                partitions
+                    .parts
+                    .extend(metadata_partition.into_dense().parts);
+            }
+
             let mut layers_to_upload = Vec::new();
             layers_to_upload.extend(
                 self.create_image_layers(
-                    &rel_partition,
+                    &partitions,
                     self.initdb_lsn,
                     ImageLayerCreationMode::Initial,
                     ctx,
                 )
                 .await?,
             );
-            if !metadata_partition.parts.is_empty() {
-                assert_eq!(
-                    metadata_partition.parts.len(),
-                    1,
-                    "currently sparse keyspace should only contain a single metadata keyspace"
-                );
-                layers_to_upload.extend(
-                    self.create_image_layers(
-                        // Safety: create_image_layers treat sparse keyspaces differently that it does not scan
-                        // every single key within the keyspace, and therefore, it's safe to force converting it
-                        // into a dense keyspace before calling this function.
-                        &metadata_partition.into_dense(),
-                        self.initdb_lsn,
-                        ImageLayerCreationMode::Initial,
-                        ctx,
-                    )
-                    .await?,
-                );
-            }
 
             (layers_to_upload, None)
         } else {