resolve tenant-snapshot conflict with list_timeline_blobs index parsing

Signed-off-by: Yuchen Liang <yuchen@neon.tech>

storage_scrubber/src/checks.rs

@@ -172,8 +172,11 @@ pub(crate) async fn branch_cleanup_and_check_errors(
                     }
                 }
                 BlobDataParseResult::Relic => {}
-                BlobDataParseResult::Incorrect(parse_errors) => result.errors.extend(
-                    parse_errors
+                BlobDataParseResult::Incorrect {
+                    errors,
+                    s3_layers: _,
+                } => result.errors.extend(
+                    errors
                         .into_iter()
                         .map(|error| format!("parse error: {error}")),
                 ),
@@ -300,7 +303,10 @@ pub(crate) enum BlobDataParseResult {
     },
     /// The remains of a deleted Timeline (i.e. an initdb archive only)
     Relic,
-    Incorrect(Vec<String>),
+    Incorrect {
+        errors: Vec<String>,
+        s3_layers: HashSet<(LayerName, Generation)>,
+    },
 }
 
 pub(crate) fn parse_layer_object_name(name: &str) -> Result<(LayerName, Generation), String> {
@@ -443,7 +449,7 @@ pub(crate) async fn list_timeline_blobs(
     }
 
     Ok(S3TimelineBlobData {
-        blob_data: BlobDataParseResult::Incorrect(errors),
+        blob_data: BlobDataParseResult::Incorrect { errors, s3_layers },
         unused_index_keys: index_part_keys,
         unknown_keys,
     })

storage_scrubber/src/pageserver_physical_gc.rs

@@ -389,10 +389,13 @@ async fn gc_ancestor(
                 // Post-deletion tenant location: don't try and GC it.
                 continue;
             }
-            BlobDataParseResult::Incorrect(reasons) => {
+            BlobDataParseResult::Incorrect {
+                errors,
+                s3_layers: _, // TODO(yuchen): could still check references to these s3 layers?
+            } => {
                 // Our primary purpose isn't to report on bad data, but log this rather than skipping silently
                 tracing::warn!(
-                    "Skipping ancestor GC for timeline {ttid}, bad metadata: {reasons:?}"
+                    "Skipping ancestor GC for timeline {ttid}, bad metadata: {errors:?}"
                 );
                 continue;
             }
@@ -518,9 +521,12 @@ pub async fn pageserver_physical_gc(
                 // Post-deletion tenant location: don't try and GC it.
                 return Ok(summary);
             }
-            BlobDataParseResult::Incorrect(reasons) => {
+            BlobDataParseResult::Incorrect {
+                errors,
+                s3_layers: _,
+            } => {
                 // Our primary purpose isn't to report on bad data, but log this rather than skipping silently
-                tracing::warn!("Skipping timeline {ttid}, bad metadata: {reasons:?}");
+                tracing::warn!("Skipping timeline {ttid}, bad metadata: {errors:?}");
                 return Ok(summary);
             }
         };

storage_scrubber/src/scan_pageserver_metadata.rs

@@ -290,13 +290,21 @@ pub async fn scan_metadata(
             }
         }
 
-        if let BlobDataParseResult::Parsed {
-            index_part: _index_part,
-            index_part_generation: _index_part_generation,
-            s3_layers,
-        } = &data.blob_data
-        {
-            tenant_objects.push(ttid, s3_layers.clone());
+        match &data.blob_data {
+            BlobDataParseResult::Parsed {
+                index_part: _index_part,
+                index_part_generation: _index_part_generation,
+                s3_layers,
+            } => {
+                tenant_objects.push(ttid, s3_layers.clone());
+            }
+            BlobDataParseResult::Relic => (),
+            BlobDataParseResult::Incorrect {
+                errors: _,
+                s3_layers,
+            } => {
+                tenant_objects.push(ttid, s3_layers.clone());
+            }
         }
         tenant_timeline_results.push((ttid, data));
     }

storage_scrubber/src/tenant_snapshot.rs

@@ -269,7 +269,7 @@ impl SnapshotDownloader {
                         .context("Downloading timeline")?;
                     }
                     BlobDataParseResult::Relic => {}
-                    BlobDataParseResult::Incorrect(_) => {
+                    BlobDataParseResult::Incorrect { .. } => {
                         tracing::error!("Bad metadata in timeline {ttid}");
                     }
                 };