[pbs-devel] [PATCH proxmox-backup v2] GC: chunk store: fix chunk using markers cleanup

[Christian Ebner]

Since commit 9510ef1a ("GC: assure chunk exists on s3 store when
creating missing chunk marker") chunks which are referenced by
an index file but do not have a local marker file are marked by a
file with the `using` extension, so they are not cleaned up during
phase 2 if the chunk is still present on the backend.

If the chunk is however not encountered, phase 3 will see the marker
and tries to clean it up, which currently however fails because
it is first tried to be cleaned up from the LRU cache, the filename
being converted to the chunk digest.

Therefore, clean up any using marker file encountered during phase 3
before any regular or bad chunk, independent from the atime.

Fixes: https://forum.proxmox.com/threads/176567/post-819437
Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
---
Changes since version 1 (thanks a lot for offlist discussion Thomas):
- Cleanup using marker chunks independent from atime cutoff

 pbs-datastore/src/chunk_store.rs | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/pbs-datastore/src/chunk_store.rs b/pbs-datastore/src/chunk_store.rs
index f53460664..7fe09b914 100644
--- a/pbs-datastore/src/chunk_store.rs
+++ b/pbs-datastore/src/chunk_store.rs
@@ -25,6 +25,8 @@ use crate::file_formats::{
 };
 use crate::{DataBlob, LocalDatastoreLruCache};
 
+const USING_MARKER_FILENAME_EXT: &str = "using";
+
 /// File system based chunk store
 pub struct ChunkStore {
     name: String, // used for error reporting
@@ -426,6 +428,16 @@ impl ChunkStore {
                     drop(lock);
                     continue;
                 }
+                if filename
+                    .to_bytes()
+                    .ends_with(USING_MARKER_FILENAME_EXT.as_bytes())
+                {
+                    unlinkat(Some(dirfd), filename, UnlinkatFlags::NoRemoveDir).map_err(|err| {
+                        format_err!("unlinking chunk using marker {filename:?} failed - {err}")
+                    })?;
+                    drop(lock);
+                    continue;
+                }
 
                 chunk_count += 1;
 
@@ -776,7 +788,7 @@ impl ChunkStore {
     /// Helper to generate marker file path for expected chunks
     fn chunk_expected_marker_path(&self, digest: &[u8; 32]) -> PathBuf {
         let (mut path, _digest_str) = self.chunk_path(digest);
-        path.set_extension("using");
+        path.set_extension(USING_MARKER_FILENAME_EXT);
         path
     }
 
-- 
2.47.3