From 7e1db8c8a1de346d3a6350e1079fd7e6eb30033c Mon Sep 17 00:00:00 2001
From: Kirill Bulatov <kirill@neon.tech>
Date: Fri, 29 Apr 2022 17:08:51 +0300
Subject: [PATCH] Show which virtual file got the deserialization errors

---
 pageserver/src/layered_repository/delta_layer.rs | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/pageserver/src/layered_repository/delta_layer.rs b/pageserver/src/layered_repository/delta_layer.rs
index ef4c3cccb0..4952f64ccd 100644
--- a/pageserver/src/layered_repository/delta_layer.rs
+++ b/pageserver/src/layered_repository/delta_layer.rs
@@ -258,8 +258,18 @@ impl Layer for DeltaLayer {
             // Ok, 'offsets' now contains the offsets of all the entries we need to read
             let mut cursor = file.block_cursor();
             for (entry_lsn, pos) in offsets {
-                let buf = cursor.read_blob(pos)?;
-                let val = Value::des(&buf)?;
+                let buf = cursor.read_blob(pos).with_context(|| {
+                    format!(
+                        "Failed to read blob from virtual file {}",
+                        file.file.path.display()
+                    )
+                })?;
+                let val = Value::des(&buf).with_context(|| {
+                    format!(
+                        "Failed to deserialize file blob from virtual file {}",
+                        file.file.path.display()
+                    )
+                })?;
                 match val {
                     Value::Image(img) => {
                         reconstruct_state.img = Some((entry_lsn, img));