From 0f3b7efa84490699051e64e3ed63fcd320903842 Mon Sep 17 00:00:00 2001
From: Stefan Reiter <s.reiter@proxmox.com>
Date: Mon, 7 Sep 2020 17:30:33 +0200
Subject: [PATCH] verify: rename corrupted chunks with .bad extension

This ensures that following backups will always upload the chunk,
thereby replacing it with a correct version again.

Format for renaming is <digest>.<counter>.bad where <counter> is used if
a chunk is found to be bad again before a GC cleans it up.

Care has been taken to deliberately only rename a chunk in conditions
where it is guaranteed to be an error in the chunk itself. Otherwise a
broken index file could lead to an unwanted mass-rename of chunks.

Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>
---
 src/backup/verify.rs | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/src/backup/verify.rs b/src/backup/verify.rs
index 1c848d57..697ed236 100644
--- a/src/backup/verify.rs
+++ b/src/backup/verify.rs
@@ -39,6 +39,34 @@ fn verify_blob(datastore: Arc<DataStore>, backup_dir: &BackupDir, info: &FileInf
     }
 }
 
+fn rename_corrupted_chunk(
+    datastore: Arc<DataStore>,
+    digest: &[u8;32],
+    worker: Arc<WorkerTask>,
+) {
+    let (path, digest_str) = datastore.chunk_path(digest);
+
+    let mut counter = 0;
+    let mut new_path = path.clone();
+    new_path.set_file_name(format!("{}.{}.bad", digest_str, counter));
+    while new_path.exists() && counter < 9 {
+        counter += 1;
+        new_path.set_file_name(format!("{}.{}.bad", digest_str, counter));
+    }
+
+    match std::fs::rename(&path, &new_path) {
+        Ok(_) => {
+            worker.log(format!("corrupted chunk renamed to {:?}", &new_path));
+        },
+        Err(err) => {
+            match err.kind() {
+                std::io::ErrorKind::NotFound => { /* ignored */ },
+                _ => worker.log(format!("could not rename corrupted chunk {:?} - {}", &path, err))
+            }
+        }
+    };
+}
+
 // We use a separate thread to read/load chunks, so that we can do
 // load and verify in parallel to increase performance.
 fn chunk_reader_thread(
@@ -73,6 +101,7 @@ fn chunk_reader_thread(
                     corrupt_chunks.lock().unwrap().insert(info.digest);
                     worker.log(format!("can't verify chunk, load failed - {}", err));
                     errors.fetch_add(1, Ordering::SeqCst);
+                    rename_corrupted_chunk(datastore.clone(), &info.digest, worker.clone());
                     continue;
                 }
                 Ok(chunk) => {
@@ -101,7 +130,7 @@ fn verify_index_chunks(
     let start_time = Instant::now();
 
     let chunk_channel = chunk_reader_thread(
-        datastore,
+        datastore.clone(),
         index,
         verified_chunks.clone(),
         corrupt_chunks.clone(),
@@ -148,6 +177,7 @@ fn verify_index_chunks(
             corrupt_chunks.lock().unwrap().insert(digest);
             worker.log(format!("{}", err));
             errors.fetch_add(1, Ordering::SeqCst);
+            rename_corrupted_chunk(datastore.clone(), &digest, worker.clone());
         } else {
             verified_chunks.lock().unwrap().insert(digest);
         }