[pbs-devel] superseded: [PATCH proxmox-backup] garbage-collect: switch to tokio Mutex

[Fabian Grünbichler]

by https://lore.proxmox.com/pbs-devel/20251001111915.2001026-2-f.gruenbichler@proxmox.com/T/#u

On September 29, 2025 11:32 am, Fabian Grünbichler wrote:
> this Mutex is held for the duration of the whole garbage collection run, which
> now includes async calls into S3 code. this is not a highly contested lock, so
> switching to the more expensive tokio variant shouldn't cause noticeable
> overhead, and fix potential deadlock problems that could occur because of
> holding the lock guard across await points.
> 
> Signed-off-by: Fabian Grünbichler <f.gruenbichler at proxmox.com>
> ---
> also found while going through std::sync::Mutex usage with S3
> 
>  pbs-datastore/src/datastore.rs | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs
> index 7cf020fc0..68043e7a5 100644
> --- a/pbs-datastore/src/datastore.rs
> +++ b/pbs-datastore/src/datastore.rs
> @@ -136,7 +136,7 @@ pub fn ensure_datastore_is_mounted(config: &DataStoreConfig) -> Result<(), Error
>  /// management interface for backup.
>  pub struct DataStoreImpl {
>      chunk_store: Arc<ChunkStore>,
> -    gc_mutex: Mutex<()>,
> +    gc_mutex: tokio::sync::Mutex<()>,
>      last_gc_status: Mutex<GarbageCollectionStatus>,
>      verify_new: bool,
>      chunk_order: ChunkOrder,
> @@ -152,7 +152,7 @@ impl DataStoreImpl {
>      pub(crate) unsafe fn new_test() -> Arc<Self> {
>          Arc::new(Self {
>              chunk_store: Arc::new(unsafe { ChunkStore::panic_store() }),
> -            gc_mutex: Mutex::new(()),
> +            gc_mutex: tokio::sync::Mutex::new(()),
>              last_gc_status: Mutex::new(GarbageCollectionStatus::default()),
>              verify_new: false,
>              chunk_order: Default::default(),
> @@ -513,7 +513,7 @@ impl DataStore {
>  
>          Ok(DataStoreImpl {
>              chunk_store,
> -            gc_mutex: Mutex::new(()),
> +            gc_mutex: tokio::sync::Mutex::new(()),
>              last_gc_status: Mutex::new(gc_status),
>              verify_new: config.verify_new.unwrap_or(false),
>              chunk_order: tuning.chunk_order.unwrap_or_default(),
> -- 
> 2.47.3
> 
> 
> 
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