[pbs-devel] [PATCH proxmox-backup v5 05/22] add helper for checking if a removable datastore is available

[Hannes Laimer <h.laimer@proxmox.com>]

Signed-off-by: Hannes Laimer <h.laimer@proxmox.com>
---
 pbs-datastore/src/datastore.rs | 53 ++++++++++++++++++++++++++++++++++
 pbs-datastore/src/lib.rs       |  2 +-
 2 files changed, 54 insertions(+), 1 deletion(-)

diff --git a/pbs-datastore/src/datastore.rs b/pbs-datastore/src/datastore.rs
index a7fe3b8c..9b715163 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())
+            .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
@@ -149,6 +183,21 @@ impl DataStore {
             }
         }
 
+        if config.backing_device.is_some() {
+            let is_mounted = is_datastore_available(&config);
+            let mut datastore_cache = DATASTORE_MAP.lock().unwrap();
+            if let Some((_, true)) = datastore_cache.get(&config.name) {
+                if !is_mounted {
+                    datastore_cache.remove(&config.name);
+                }
+                bail!("Removable Datastore in progress to being removed.");
+            }
+            if !is_mounted {
+                datastore_cache.remove(&config.name);
+                bail!("Removable Datastore is not mounted");
+            }
+        }
+
         if let Some(operation) = operation {
             update_active_operations(name, operation, 1)?;
         }
@@ -253,6 +302,10 @@ 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::{
-- 
2.39.2



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