Re: [pbs-devel] [PATCH proxmox-backup v2] api: enhance directory existence check

[Christian Ebner <c.ebner@proxmox.com>]

> On 30.11.2023 10:33 CET Markus Frank <m.frank@proxmox.com> wrote:
> 
>  
> If a directory exists on the specified path,
> it now also checks whether the directory is empty and not already mounted.
> 
> Previously, if a directory were deleted and a directory with the same name
> would be created, the old check prevented the creation even though the
> directory could be used as a mount point.
> 
> Signed-off-by: Markus Frank <m.frank@proxmox.com>
> ---
> v2: added check if another file system is mounted on the specified path
> 
>  src/api2/node/disks/directory.rs | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/src/api2/node/disks/directory.rs b/src/api2/node/disks/directory.rs
> index 5e1cb124..48e0bd57 100644
> --- a/src/api2/node/disks/directory.rs
> +++ b/src/api2/node/disks/directory.rs
> @@ -1,6 +1,7 @@
>  use ::serde::{Deserialize, Serialize};
>  use anyhow::{bail, Error};
>  use serde_json::json;
> +use std::os::linux::fs::MetadataExt;
>  
>  use proxmox_router::{Permission, Router, RpcEnvironment, RpcEnvironmentType};
>  use proxmox_schema::api;
> @@ -156,12 +157,20 @@ pub fn create_datastore_disk(
>      let mount_point = format!("{}{}", BASE_MOUNT_DIR, &name);
>  
>      // check if the default path does exist already and bail if it does
> +    // and is not empty or another file system is already mounted on it

nit: not very well readable anymore. I would suggest
// check if the default path exists already.
// bail if it is not empty or another filesystem mounted on top
>      let default_path = std::path::PathBuf::from(&mount_point);
>  
>      match std::fs::metadata(&default_path) {
>          Err(_) => {} // path does not exist
> -        Ok(_) => {
> -            bail!("path {:?} already exists", default_path);
> +        Ok(stat) => {
> +            let basedir_dev = std::fs::metadata(BASE_MOUNT_DIR)?.st_dev();
> +            if stat.st_dev() != basedir_dev {
> +                bail!("path {default_path:?} already exists and is mountpoint");
> +            }
> +            let is_empty = default_path.read_dir()?.next().is_none();
> +            if !is_empty {
> +                bail!("path {default_path:?} already exists and is not empty");
> +            }
>          }
>      }
>  
> -- 
> 2.39.2

other than that looks good to me, please consider this:

Tested-by: Christian Ebner <c.ebner@proxmox.com>