[pbs-devel] [PATCH proxmox-backup 2/7] gc: chunk store: rework atime check and gc status into common helper

[Fabian Grünbichler]

On October 6, 2025 12:41 pm, Christian Ebner wrote:
> Use the shared code paths for both, filesystem and s3 backend to a
> common helper to avoid code duplication and adapt callsites
> accordingly.
> 
> Signed-off-by: Christian Ebner <c.ebner at proxmox.com>
> ---
>  pbs-datastore/src/chunk_store.rs | 69 ++++++++++++++++++++++----------
>  pbs-datastore/src/datastore.rs   | 29 +++++---------
>  2 files changed, 57 insertions(+), 41 deletions(-)
> 
> diff --git a/pbs-datastore/src/chunk_store.rs b/pbs-datastore/src/chunk_store.rs
> index 3c59612bb..0725ca3a7 100644
> --- a/pbs-datastore/src/chunk_store.rs
> +++ b/pbs-datastore/src/chunk_store.rs
> @@ -408,36 +408,27 @@ impl ChunkStore {
>  
>                  chunk_count += 1;
>  
> -                if stat.st_atime < min_atime {
> -                    //let age = now - stat.st_atime;
> -                    //println!("UNLINK {}  {:?}", age/(3600*24), filename);
> +                if Self::check_atime_and_update_gc_status(
> +                    stat.st_atime,
> +                    min_atime,
> +                    oldest_writer,
> +                    stat.st_size as u64,
> +                    bad,
> +                    status,
> +                ) {
>                      if let Err(err) = unlinkat(Some(dirfd), filename, UnlinkatFlags::NoRemoveDir) {

if this part where also handled by the helper (in a fashion that allows
using it for both cache and regular chunk store)

>                          if bad {
> +                            status.removed_bad -= 1;
>                              status.still_bad += 1;
> +                        } else {
> +                            status.removed_chunks += 1;
>                          }
> +                        status.removed_bytes -= stat.st_size as u64;

then this error handling here would not leak outside of the helper, and
we could "simply" call the helper and bubble up any error it returns..

>                          bail!(
>                              "unlinking chunk {filename:?} failed on store '{}' - {err}",
>                              self.name,
>                          );
>                      }
> -                    if bad {
> -                        status.removed_bad += 1;
> -                    } else {
> -                        status.removed_chunks += 1;
> -                    }
> -                    status.removed_bytes += stat.st_size as u64;
> -                } else if stat.st_atime < oldest_writer {
> -                    if bad {
> -                        status.still_bad += 1;
> -                    } else {
> -                        status.pending_chunks += 1;
> -                    }
> -                    status.pending_bytes += stat.st_size as u64;
> -                } else {
> -                    if !bad {
> -                        status.disk_chunks += 1;
> -                    }
> -                    status.disk_bytes += stat.st_size as u64;
>                  }
>              }
>              drop(lock);
> @@ -446,6 +437,42 @@ impl ChunkStore {
>          Ok(())
>      }
>  
> +    /// Check within what range the provided chunks atime falls and update the garbage collection
> +    /// status accordingly.
> +    ///
> +    /// Returns true if the chunk file should be removed.
> +    pub(super) fn check_atime_and_update_gc_status(
> +        atime: i64,
> +        min_atime: i64,
> +        oldest_writer: i64,
> +        size: u64,
> +        bad: bool,
> +        gc_status: &mut GarbageCollectionStatus,
> +    ) -> bool {
> +        if atime < min_atime {
> +            if bad {
> +                gc_status.removed_bad += 1;
> +            } else {
> +                gc_status.removed_chunks += 1;
> +            }
> +            gc_status.removed_bytes += size;
> +            return true;
> +        } else if atime < oldest_writer {
> +            if bad {
> +                gc_status.still_bad += 1;
> +            } else {
> +                gc_status.pending_chunks += 1;
> +            }
> +            gc_status.pending_bytes += size;
> +        } else {
> +            if !bad {
> +                gc_status.disk_chunks += 1;
> +            }
> +            gc_status.disk_bytes += size;
> +        }
> +        false
> +    }
> +
>      /// Check if atime updates are honored by the filesystem backing the chunk store.
>      ///
>      /// Checks if the atime is always updated by utimensat taking into consideration the Linux
> diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs
> index c2a82b8b8..e36af68fc 100644
> --- a/pbs-datastore/src/datastore.rs
> +++ b/pbs-datastore/src/datastore.rs
> @@ -1676,30 +1676,19 @@ impl DataStore {
>                          .extension()
>                          .is_some_and(|ext| ext == "bad");
>  
> -                    if atime < min_atime {
> +                    if ChunkStore::check_atime_and_update_gc_status(
> +                        atime,
> +                        min_atime,
> +                        oldest_writer,
> +                        content.size,
> +                        bad,
> +                        &mut gc_status,
> +                    ) {
>                          if let Some(cache) = self.cache() {
>                              // ignore errors, phase 3 will retry cleanup anyways
>                              let _ = cache.remove(&digest);
>                          }
> -                        delete_list.push(content.key.clone());
> -                        if bad {
> -                            gc_status.removed_bad += 1;
> -                        } else {
> -                            gc_status.removed_chunks += 1;
> -                        }
> -                        gc_status.removed_bytes += content.size;
> -                    } else if atime < oldest_writer {
> -                        if bad {
> -                            gc_status.still_bad += 1;
> -                        } else {
> -                            gc_status.pending_chunks += 1;
> -                        }
> -                        gc_status.pending_bytes += content.size;
> -                    } else {
> -                        if !bad {
> -                            gc_status.disk_chunks += 1;
> -                        }
> -                        gc_status.disk_bytes += content.size;
> +                        delete_list.push(content.key);

nit: this removal of the clone could have happened in patch #1

>                      }
>  
>                      chunk_count += 1;
> -- 
> 2.47.3
> 
> 
> 
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