[pbs-devel] [PATCH proxmox-backup v9 06/26] datastore: add helper for checking if a removable datastore is available

[Gabriel Goller]

On Tue Apr 23, 2024 at 10:29 AM CEST, Hannes Laimer wrote:
> diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs
> index f9b986c1..978ebb70 100644
> --- a/pbs-datastore/src/datastore.rs
> +++ b/pbs-datastore/src/datastore.rs
> @@ -14,6 +14,7 @@ use proxmox_schema::ApiType;
>  use proxmox_sys::error::SysError;
>  use proxmox_sys::fs::{file_read_optional_string, replace_file, CreateOptions};
>  use proxmox_sys::fs::{lock_dir_noblock, DirLockGuard};
> +use proxmox_sys::linux::procfs::MountInfo;
>  use proxmox_sys::process_locker::ProcessLockSharedGuard;
>  use proxmox_sys::WorkerTaskContext;
>  use proxmox_sys::{task_log, task_warn};
> @@ -49,6 +50,39 @@ pub fn check_backup_owner(owner: &Authid, auth_id: &Authid) -> Result<(), Error>
>      Ok(())
>  }
>  
> +/// check if a removable datastore is currently available/mounted by using the UUID
> +/// to find the `/dev/sdX` path and checking in /proc/self/mountinfo for entries containing it.

Capitalize the "c" in "check".

> +/// If it should mounted, but not in the expected path, so config.path, it is considered not
> +/// available.

I think it's better to rewrite this:

    /// If the datastore should be mounted, but is not in the expected path (config.path), it is considered not
    /// available.

> +pub fn is_datastore_available(config: &DataStoreConfig) -> bool {
> +    config.backing_device.as_ref().map_or(true, |uuid| {
> +        if let Ok(store_dev_path) = std::fs::read_link(Path::new("/dev/disk/by-uuid").join(uuid))
> +            .map(|p| p.to_string_lossy().into_owned())
> +            .map(|p| p.replace("../..", "/dev"))
> +            .map(PathBuf::from)
> +        {
> +            let store_mount_point = config.get_mount_point().map(|mp| PathBuf::from(&mp));
> +
> +            MountInfo::read().map_or(false, |mount_info| {
> +                mount_info
> +                    .iter()
> +                    .filter_map(|(_, entry)| {
> +                        entry
> +                            .mount_source
> +                            .as_ref()
> +                            .map(|source| (&entry.mount_point, source))
> +                    })
> +                    .any(|(mount_point, mount_source)| {
> +                        Some(PathBuf::from(&mount_point)) == store_mount_point
> +                            && PathBuf::from(&mount_source) == store_dev_path
> +                    })
> +            })
> +        } else {
> +            false
> +        }
> +    })
> +}
> +
>  /// Datastore Management
>  ///
>  /// A Datastore can store severals backups, and provides the
> @@ -158,6 +192,12 @@ impl DataStore {
>              }
>          }
>  
> +        if config.backing_device.is_some() && !is_datastore_available(&config) {
> +            let mut datastore_cache = DATASTORE_MAP.lock().unwrap();
> +            datastore_cache.remove(&config.name);
> +            bail!("Removable Datastore is not mounted");
> +        }
> +
>          if let Some(operation) = operation {
>              update_active_operations(name, operation, 1)?;
>          }
> @@ -261,6 +301,10 @@ impl DataStore {
>      ) -> Result<Arc<Self>, Error> {
>          let name = config.name.clone();
>  
> +        if !is_datastore_available(&config) {
> +            bail!("Datastore is not available")
> +        }
> +
>          let tuning: DatastoreTuning = serde_json::from_value(
>              DatastoreTuning::API_SCHEMA
>                  .parse_property_string(config.tuning.as_deref().unwrap_or(""))?,
> diff --git a/pbs-datastore/src/lib.rs b/pbs-datastore/src/lib.rs
> index 43050162..458f93d9 100644
> --- a/pbs-datastore/src/lib.rs
> +++ b/pbs-datastore/src/lib.rs
> @@ -206,7 +206,7 @@ pub use manifest::BackupManifest;
>  pub use store_progress::StoreProgress;
>  
>  mod datastore;
> -pub use datastore::{check_backup_owner, DataStore};
> +pub use datastore::{check_backup_owner, is_datastore_available, DataStore};
>  
>  mod hierarchy;
>  pub use hierarchy::{