[pbs-devel] [PATCH proxmox-backup] garbage collection: fix: account for created/deleted index files

[Christian Ebner]

Since commit 74361da8 ("garbage collection: generate index file list
via datastore iterators") not only snapshots present at the start of
the garbage collection run are considered for marking, but also newly
added ones. Take these into account by adapting the total index file
counter used for the progress output.

Further, correctly take into account also index files which have been
pruned during GC, therefore present in the list of still to process
index files but never encountered by the datastore iterators. These
would otherwise be interpreted incorrectly as strange paths and logged
accordingly, causing confusion as reported in the community forum [0].

Fixes: https://forum.proxmox.com/threads/164968/
Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
---
 pbs-datastore/src/datastore.rs | 26 ++++++++++++++++++--------
 1 file changed, 18 insertions(+), 8 deletions(-)

diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs
index fbd9eddba..aa38e2ac1 100644
--- a/pbs-datastore/src/datastore.rs
+++ b/pbs-datastore/src/datastore.rs
@@ -1129,7 +1129,7 @@ impl DataStore {
         // the detected index files not following the iterators logic.
 
         let mut unprocessed_index_list = self.list_index_files()?;
-        let index_count = unprocessed_index_list.len();
+        let mut index_count = unprocessed_index_list.len();
 
         let mut chunk_lru_cache = LruCache::new(cache_capacity);
         let mut processed_index_files = 0;
@@ -1156,7 +1156,10 @@ impl DataStore {
 
                         let index = match self.open_index_reader(&path)? {
                             Some(index) => index,
-                            None => continue,
+                            None => {
+                                unprocessed_index_list.remove(&path);
+                                continue;
+                            }
                         };
                         self.index_mark_used_chunks(
                             index,
@@ -1166,7 +1169,10 @@ impl DataStore {
                             worker,
                         )?;
 
-                        unprocessed_index_list.remove(&path);
+                        if !unprocessed_index_list.remove(&path) {
+                            info!("Encountered new index file '{path:?}', increment total index file count");
+                            index_count += 1;
+                        }
 
                         let percentage = (processed_index_files + 1) * 100 / index_count;
                         if percentage > last_percentage {
@@ -1182,18 +1188,22 @@ impl DataStore {
             }
         }
 
-        let strange_paths_count = unprocessed_index_list.len();
-        if strange_paths_count > 0 {
-            warn!("found {strange_paths_count} index files outside of expected directory scheme");
-        }
+        let mut strange_paths_count = unprocessed_index_list.len();
         for path in unprocessed_index_list {
             let index = match self.open_index_reader(&path)? {
                 Some(index) => index,
-                None => continue,
+                None => {
+                    // do not count vanished (pruned) backup snapshots as strange paths.
+                    strange_paths_count -= 1;
+                    continue;
+                }
             };
             self.index_mark_used_chunks(index, &path, &mut chunk_lru_cache, status, worker)?;
             warn!("Marked chunks for unexpected index file at '{path:?}'");
         }
+        if strange_paths_count > 0 {
+            warn!("Found {strange_paths_count} index files outside of expected directory scheme");
+        }
 
         Ok(())
     }
-- 
2.39.5