From b683fd589c720a118b1578615b1c04cb36bdd714 Mon Sep 17 00:00:00 2001
From: Dominik Csapak <d.csapak@proxmox.com>
Date: Fri, 23 Oct 2020 16:32:32 +0200
Subject: [PATCH] backup/datastore: save garbage collection status to disk

and load it again when opening it

this way we can persist the status of the last garbage collect across
daemon reloads and reboots

Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
---
 src/backup/datastore.rs | 34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/src/backup/datastore.rs b/src/backup/datastore.rs
index 2389cc6c..485a10ff 100644
--- a/src/backup/datastore.rs
+++ b/src/backup/datastore.rs
@@ -9,7 +9,7 @@ use std::fs::File;
 use anyhow::{bail, format_err, Error};
 use lazy_static::lazy_static;
 
-use proxmox::tools::fs::{replace_file, CreateOptions, open_file_locked};
+use proxmox::tools::fs::{replace_file, file_read_optional_string, CreateOptions, open_file_locked};
 
 use super::backup_info::{BackupGroup, BackupDir};
 use super::chunk_store::ChunkStore;
@@ -71,7 +71,20 @@ impl DataStore {
     fn open_with_path(store_name: &str, path: &Path, config: DataStoreConfig) -> Result<Self, Error> {
         let chunk_store = ChunkStore::open(store_name, path)?;
 
-        let gc_status = GarbageCollectionStatus::default();
+        let mut gc_status_path = chunk_store.base_path();
+        gc_status_path.push(".gc-status");
+
+        let gc_status = if let Some(state) = file_read_optional_string(gc_status_path)? {
+            match serde_json::from_str(&state) {
+                Ok(state) => state,
+                Err(err) => {
+                    eprintln!("error reading gc-status: {}", err);
+                    GarbageCollectionStatus::default()
+                }
+            }
+        } else {
+            GarbageCollectionStatus::default()
+        };
 
         Ok(Self {
             chunk_store: Arc::new(chunk_store),
@@ -572,6 +585,23 @@ impl DataStore {
                 crate::task_log!(worker, "Average chunk size: {}", HumanByte::from(avg_chunk));
             }
 
+            if let Ok(serialized) = serde_json::to_string(&gc_status) {
+                let mut path = self.base_path();
+                path.push(".gc-status");
+
+                let backup_user = crate::backup::backup_user()?;
+                let mode = nix::sys::stat::Mode::from_bits_truncate(0o0644);
+                // set the correct owner/group/permissions while saving file
+                // owner(rw) = backup, group(r)= backup
+                let options = CreateOptions::new()
+                    .perm(mode)
+                    .owner(backup_user.uid)
+                    .group(backup_user.gid);
+
+                // ignore errors
+                let _ = replace_file(path, serialized.as_bytes(), options);
+            }
+
             *self.last_gc_status.lock().unwrap() = gc_status;
 
         } else {