[pbs-devel] [PATCH proxmox-backup v3 05/24] add helper for checking if a removable datastore is available

[Hannes Laimer]

On Mon Apr 15, 2024 at 5:09 PM CEST, Christian Ebner wrote:
> some comments inline
>
> On 4/9/24 12:59, Hannes Laimer wrote:
> > Signed-off-by: Hannes Laimer <h.laimer at proxmox.com>
> > ---
> >   pbs-datastore/src/datastore.rs | 18 ++++++++++++++++++
> >   pbs-datastore/src/lib.rs       |  2 +-
> >   2 files changed, 19 insertions(+), 1 deletion(-)
> > 
> > diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs
> > index 0685cc84..db47205c 100644
> > --- a/pbs-datastore/src/datastore.rs
> > +++ b/pbs-datastore/src/datastore.rs
> > @@ -49,6 +49,22 @@ pub fn check_backup_owner(owner: &Authid, auth_id: &Authid) -> Result<(), Error>
> >       Ok(())
> >   }
> >   
> > +pub fn check_if_available(config: &DataStoreConfig) -> Result<(), Error> {
>
> the function signature suggests that this checks if the datastore is 
> available, so maybe call this `is_datastore_available` and let it return 
> a boolean instead, further distinguishing between error states because 
> of runtime errors and the datastore simply not being available.
>

makes sense, will do in v4

> > +    config.backing_device.as_ref().map_or(Ok(()), |uuid| {
> > +        let mut command = std::process::Command::new("findmnt");
> > +        command.args(["-n", "-o", "TARGET", "--source", &format!("UUID={uuid}")]);
> > +
> > +        match proxmox_sys::command::run_command(command, None) {
> > +            Ok(mount_point) if mount_point.trim_end() == config.path => Ok(()),
> > +            _ => Err(format_err!(
>
> this should distinguish between an error because of the `run_command` 
> failing because of e.g. outdated/incompatible command line arguments 
> passed to `findmnt` and the filesystem not being mounted.
> I see however that `findmnt` only has 2 error codes, so maybe this could 
> be done by using `lsblk` and filtering the output based on the `uuid` 
> instead, but there might be better solutions that I am not aware of.
>

yes, but I won't use an external tool in v4

> > +                "device for datastore '{}' has to be mounted at '{}'",
>
> should actually be the filesystem on the device that needs to be 
> mounted, not the device?
>
> > +                config.name,
> > +                config.path
> > +            )),
> > +        }
> > +    })
> > +}
> > +
> >   /// Datastore Management
> >   ///
> >   /// A Datastore can store severals backups, and provides the
> > @@ -261,6 +277,8 @@ impl DataStore {
> >       ) -> Result<Arc<Self>, Error> {
> >           let name = config.name.clone();
> >   
> > +        check_if_available(&config)?;
> > +
> >           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..f5e93e92 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, check_if_available, DataStore};
> >   
> >   mod hierarchy;
> >   pub use hierarchy::{