Revert "backup: ensure base snapshots are still available after backup"

This reverts commit d53fbe24741ed3bd920ee1c61bc163b1874b7c82.

The HashSet and "register" function are unnecessary, as we already know
which backup is the one we need to check: the last one, stored as
'last_backup'.

Signed-off-by: Stefan Reiter <s.reiter@proxmox.com>

src/api2/backup.rs

@@ -661,7 +661,6 @@ fn download_previous(
             };
             if let Some(index) = index {
                 env.log(format!("register chunks in '{}' from previous backup.", archive_name));
-                env.register_base_snapshot(last_backup.backup_dir.clone());
 
                 for pos in 0..index.index_count() {
                     let info = index.chunk_info(pos).unwrap();

src/api2/backup/environment.rs

@@ -1,6 +1,6 @@
 use anyhow::{bail, format_err, Error};
 use std::sync::{Arc, Mutex};
-use std::collections::{HashMap, HashSet};
+use std::collections::HashMap;
 
 use ::serde::{Serialize};
 use serde_json::{json, Value};
@@ -73,7 +73,6 @@ struct SharedBackupState {
     dynamic_writers: HashMap<usize, DynamicWriterState>,
     fixed_writers: HashMap<usize, FixedWriterState>,
     known_chunks: HashMap<[u8;32], u32>,
-    base_snapshots: HashSet<BackupDir>,
     backup_size: u64, // sums up size of all files
     backup_stat: UploadStatistic,
 }
@@ -127,7 +126,6 @@ impl BackupEnvironment {
             dynamic_writers: HashMap::new(),
             fixed_writers: HashMap::new(),
             known_chunks: HashMap::new(),
-            base_snapshots: HashSet::new(),
             backup_size: 0,
             backup_stat: UploadStatistic::new(),
         };
@@ -146,13 +144,6 @@ impl BackupEnvironment {
         }
     }
 
-    /// Register a snapshot as a predecessor of the current backup.
-    /// It's existance will be ensured on finishing.
-    pub fn register_base_snapshot(&self, snap: BackupDir) {
-        let mut state = self.state.lock().unwrap();
-        state.base_snapshots.insert(snap);
-    }
-
     /// Register a Chunk with associated length.
     ///
     /// We do not fully trust clients, so a client may only use registered
@@ -489,16 +480,6 @@ impl BackupEnvironment {
         self.datastore.store_manifest(&self.backup_dir, manifest)
             .map_err(|err| format_err!("unable to store manifest blob - {}", err))?;
 
-        for snap in &state.base_snapshots {
-            let path = self.datastore.snapshot_path(snap);
-            if !path.exists() {
-                bail!(
-                    "base snapshot {} was removed during backup, cannot finish as chunks might be missing",
-                    snap
-                );
-            }
-        }
-
         // marks the backup as successful
         state.finished = true;
 

src/backup/backup_info.rs

@@ -173,7 +173,7 @@ impl std::str::FromStr for BackupGroup {
 /// Uniquely identify a Backup (relative to data store)
 ///
 /// We also call this a backup snaphost.
-#[derive(Debug, Eq, PartialEq, Hash, Clone)]
+#[derive(Debug, Eq, PartialEq, Clone)]
 pub struct BackupDir {
     /// Backup group
     group: BackupGroup,