[pbs-devel] [PATCH proxmox-backup v2 12/12] pull: guard chunk upload and only insert into cache after upload

[Christian Ebner]

Inserting the chunk into the local datastore cache leads to it being
considered as present on the backend. The upload might however still
fail, leading to missing chunks.

Therefore, only insert the chunk after the upload completed with
success and guard the upload by the backend upload marker file to
avoid races with garbage collection.

Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
---
 src/server/pull.rs | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/server/pull.rs b/src/server/pull.rs
index 08e6e6b64..dd03a3dc8 100644
--- a/src/server/pull.rs
+++ b/src/server/pull.rs
@@ -176,14 +176,22 @@ async fn pull_index_chunks<I: IndexFile>(
                     if target2.cache_contains(&digest) {
                         return Ok(());
                     }
-                    target2.cache_insert(&digest, &chunk)?;
                     let data = chunk.raw_data().to_vec();
                     let upload_data = hyper::body::Bytes::from(data);
                     let object_key = pbs_datastore::s3::object_key_from_digest(&digest)?;
-                    let _is_duplicate = proxmox_async::runtime::block_on(
+                    if !target2.insert_backend_upload_marker(&digest)? {
+                        return Ok(());
+                    }
+                    match proxmox_async::runtime::block_on(
                         s3_client.upload_no_replace_with_retry(object_key, upload_data),
-                    )
-                    .context("failed to upload chunk to s3 backend")?;
+                    ) {
+                        Ok(_is_duplicate) => (),
+                        Err(err) => {
+                            target2.cleanup_backend_upload_marker(&digest)?;
+                            return Err(err.context("failed to upload chunk to s3 backend"));
+                        }
+                    }
+                    target2.cache_insert(&digest, &chunk)?;
                 }
             }
             Ok(())
-- 
2.47.3