[pbs-devel] [PATCH proxmox-backup v7 04/20] datastore: add helper for checking if a removable datastore is available

[Christian Ebner]

On 4/19/24 10:58, Hannes Laimer wrote:
> Signed-off-by: Hannes Laimer <h.laimer at proxmox.com>
> ---
>   pbs-api-types/src/maintenance.rs |  2 +-
>   pbs-datastore/src/datastore.rs   | 44 ++++++++++++++++++++++++++++++++
>   pbs-datastore/src/lib.rs         |  2 +-
>   3 files changed, 46 insertions(+), 2 deletions(-)
> 
> diff --git a/pbs-api-types/src/maintenance.rs b/pbs-api-types/src/maintenance.rs
> index fd4d3416..4f653ec7 100644
> --- a/pbs-api-types/src/maintenance.rs
> +++ b/pbs-api-types/src/maintenance.rs
> @@ -81,7 +81,7 @@ impl MaintenanceMode {
>       /// Used for deciding whether the datastore is cleared from the internal cache after the last
>       /// task finishes, so all open files are closed.
>       pub fn is_offline(&self) -> bool {
> -        self.ty == MaintenanceType::Offline
> +        self.ty == MaintenanceType::Offline || self.ty == MaintenanceType::Unmount
>       }
>   
>       pub fn check(&self, operation: Option<Operation>) -> Result<(), Error> {
> diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs
> index f95da761..274f1506 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.
> +/// If it should mounted, but not in the expected path, so 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())

while this probably never happens for this case, the `to_string_lossy` 
might replace non UTF-8 characters here.

So I think this and the next two map calls should be replaced with a 
`canonicalize` of `PathBuf`, which also resolves the symlink?

https://doc.rust-lang.org/std/path/struct.PathBuf.html#method.canonicalize

> +            .map(|p| p.replace("../..", "/dev"))
> +            .map(PathBuf::from)
> +        {
> +            let store_mount_point = PathBuf::from(&config.path);
> +
> +            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)| {
> +                        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::{