[pbs-devel] [PATCH proxmox-backup 1/2] use new atomic_open_or_create_file

[Dietmar Maurer <dietmar@proxmox.com>]

Factor out open_backup_lockfile() method to acquire locks owned by
user backup with permission 0660.
---
 src/api2/access/acl.rs                  |   4 +-
 src/api2/access/user.rs                 |  14 +--
 src/api2/config/datastore.rs            |   2 +-
 src/api2/config/remote.rs               |   8 +-
 src/api2/config/sync.rs                 |   8 +-
 src/api2/config/tape_backup_job.rs      |   9 +-
 src/api2/config/tape_encryption_keys.rs |  15 +---
 src/api2/config/verify.rs               |   9 +-
 src/api2/node/disks/directory.rs        |   4 +-
 src/api2/node/network.rs                |   9 +-
 src/backup/datastore.rs                 |   9 +-
 src/backup/mod.rs                       |  26 ++++++
 src/config/acme/plugin.rs               |   6 +-
 src/config/datastore.rs                 |   6 +-
 src/config/domains.rs                   |   6 +-
 src/config/drive.rs                     |   6 +-
 src/config/media_pool.rs                |   6 +-
 src/config/node.rs                      |   8 +-
 src/config/tape_encryption_keys.rs      |   8 +-
 src/config/tfa.rs                       |  11 ++-
 src/config/token_shadow.rs              |   9 +-
 src/server/jobstate.rs                  |  16 ++--
 src/server/worker_task.rs               |  14 ++-
 src/tape/drive/mod.rs                   |  46 +++++-----
 src/tape/drive/virtual_tape.rs          |   3 +-
 src/tape/inventory.rs                   |  49 ++---------
 src/tape/media_pool.rs                  |   5 +-
 src/tools/memcom.rs                     | 110 +++---------------------
 28 files changed, 158 insertions(+), 268 deletions(-)

diff --git a/src/api2/access/acl.rs b/src/api2/access/acl.rs
index a78aabcd..88a2667c 100644
--- a/src/api2/access/acl.rs
+++ b/src/api2/access/acl.rs
@@ -3,12 +3,12 @@
 use anyhow::{bail, Error};
 
 use proxmox::api::{api, Router, RpcEnvironment, Permission};
-use proxmox::tools::fs::open_file_locked;
 
 use crate::api2::types::*;
 use crate::config::acl;
 use crate::config::acl::{Role, PRIV_SYS_AUDIT, PRIV_PERMISSIONS_MODIFY};
 use crate::config::cached_user_info::CachedUserInfo;
+use crate::backup::open_backup_lockfile;
 
 fn extract_acl_node_data(
     node: &acl::AclTreeNode,
@@ -200,7 +200,7 @@ pub fn update_acl(
         };
     }
 
-    let _lock = open_file_locked(acl::ACL_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(acl::ACL_CFG_LOCKFILE, None, true)?;
 
     let (mut tree, expected_digest) = acl::config()?;
 
diff --git a/src/api2/access/user.rs b/src/api2/access/user.rs
index e080d57a..23c999b4 100644
--- a/src/api2/access/user.rs
+++ b/src/api2/access/user.rs
@@ -8,13 +8,13 @@ use std::collections::HashMap;
 use proxmox::api::{api, ApiMethod, Router, RpcEnvironment, Permission};
 use proxmox::api::router::SubdirMap;
 use proxmox::api::schema::{Schema, StringSchema};
-use proxmox::tools::fs::open_file_locked;
 
 use crate::api2::types::*;
 use crate::config::user;
 use crate::config::token_shadow;
 use crate::config::acl::{PRIV_SYS_AUDIT, PRIV_PERMISSIONS_MODIFY};
 use crate::config::cached_user_info::CachedUserInfo;
+use crate::backup::open_backup_lockfile;
 
 pub const PBS_PASSWORD_SCHEMA: Schema = StringSchema::new("User Password.")
     .format(&PASSWORD_FORMAT)
@@ -226,7 +226,7 @@ pub fn create_user(
     rpcenv: &mut dyn RpcEnvironment
 ) -> Result<(), Error> {
 
-    let _lock = open_file_locked(user::USER_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(user::USER_CFG_LOCKFILE, None, true)?;
 
     let user: user::User = serde_json::from_value(param)?;
 
@@ -368,7 +368,7 @@ pub fn update_user(
     rpcenv: &mut dyn RpcEnvironment,
 ) -> Result<(), Error> {
 
-    let _lock = open_file_locked(user::USER_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(user::USER_CFG_LOCKFILE, None, true)?;
 
     let (mut config, expected_digest) = user::config()?;
 
@@ -461,7 +461,7 @@ pub fn update_user(
 pub fn delete_user(userid: Userid, digest: Option<String>) -> Result<(), Error> {
 
     let _tfa_lock = crate::config::tfa::write_lock()?;
-    let _lock = open_file_locked(user::USER_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(user::USER_CFG_LOCKFILE, None, true)?;
 
     let (mut config, expected_digest) = user::config()?;
 
@@ -597,7 +597,7 @@ pub fn generate_token(
     digest: Option<String>,
 ) -> Result<Value, Error> {
 
-    let _lock = open_file_locked(user::USER_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(user::USER_CFG_LOCKFILE, None, true)?;
 
     let (mut config, expected_digest) = user::config()?;
 
@@ -678,7 +678,7 @@ pub fn update_token(
     digest: Option<String>,
 ) -> Result<(), Error> {
 
-    let _lock = open_file_locked(user::USER_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(user::USER_CFG_LOCKFILE, None, true)?;
 
     let (mut config, expected_digest) = user::config()?;
 
@@ -746,7 +746,7 @@ pub fn delete_token(
     digest: Option<String>,
 ) -> Result<(), Error> {
 
-    let _lock = open_file_locked(user::USER_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(user::USER_CFG_LOCKFILE, None, true)?;
 
     let (mut config, expected_digest) = user::config()?;
 
diff --git a/src/api2/config/datastore.rs b/src/api2/config/datastore.rs
index 19b822d4..a55e3bdc 100644
--- a/src/api2/config/datastore.rs
+++ b/src/api2/config/datastore.rs
@@ -60,7 +60,7 @@ pub fn list_datastores(
 }
 
 pub(crate) fn do_create_datastore(
-    _lock: std::fs::File,
+    _lock: BackupLockGuard,
     mut config: SectionConfigData,
     datastore: DataStoreConfig,
     worker: Option<&dyn TaskState>,
diff --git a/src/api2/config/remote.rs b/src/api2/config/remote.rs
index 446a2604..33c99bff 100644
--- a/src/api2/config/remote.rs
+++ b/src/api2/config/remote.rs
@@ -4,13 +4,13 @@ use ::serde::{Deserialize, Serialize};
 
 use proxmox::api::{api, ApiMethod, Router, RpcEnvironment, Permission};
 use proxmox::http_err;
-use proxmox::tools::fs::open_file_locked;
 
 use crate::api2::types::*;
 use crate::client::{HttpClient, HttpClientOptions};
 use crate::config::cached_user_info::CachedUserInfo;
 use crate::config::remote;
 use crate::config::acl::{PRIV_REMOTE_AUDIT, PRIV_REMOTE_MODIFY};
+use crate::backup::open_backup_lockfile;
 
 #[api(
     input: {
@@ -94,7 +94,7 @@ pub fn list_remotes(
 /// Create new remote.
 pub fn create_remote(password: String, param: Value) -> Result<(), Error> {
 
-    let _lock = open_file_locked(remote::REMOTE_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(remote::REMOTE_CFG_LOCKFILE, None, true)?;
 
     let mut data = param;
     data["password"] = Value::from(base64::encode(password.as_bytes()));
@@ -216,7 +216,7 @@ pub fn update_remote(
     digest: Option<String>,
 ) -> Result<(), Error> {
 
-    let _lock = open_file_locked(remote::REMOTE_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(remote::REMOTE_CFG_LOCKFILE, None, true)?;
 
     let (mut config, expected_digest) = remote::config()?;
 
@@ -290,7 +290,7 @@ pub fn delete_remote(name: String, digest: Option<String>) -> Result<(), Error>
         }
     }
 
-    let _lock = open_file_locked(remote::REMOTE_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(remote::REMOTE_CFG_LOCKFILE, None, true)?;
 
     let (mut config, expected_digest) = remote::config()?;
 
diff --git a/src/api2/config/sync.rs b/src/api2/config/sync.rs
index e784029a..bc7b9f24 100644
--- a/src/api2/config/sync.rs
+++ b/src/api2/config/sync.rs
@@ -3,7 +3,6 @@ use serde_json::Value;
 use ::serde::{Deserialize, Serialize};
 
 use proxmox::api::{api, Permission, Router, RpcEnvironment};
-use proxmox::tools::fs::open_file_locked;
 
 use crate::api2::types::*;
 
@@ -18,6 +17,7 @@ use crate::config::acl::{
 
 use crate::config::cached_user_info::CachedUserInfo;
 use crate::config::sync::{self, SyncJobConfig};
+use crate::backup::open_backup_lockfile;
 
 pub fn check_sync_job_read_access(
     user_info: &CachedUserInfo,
@@ -152,7 +152,7 @@ pub fn create_sync_job(
     let auth_id: Authid = rpcenv.get_auth_id().unwrap().parse()?;
     let user_info = CachedUserInfo::new()?;
 
-    let _lock = open_file_locked(sync::SYNC_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(sync::SYNC_CFG_LOCKFILE, None, true)?;
 
     let sync_job: sync::SyncJobConfig = serde_json::from_value(param)?;
     if !check_sync_job_modify_access(&user_info, &auth_id, &sync_job) {
@@ -296,7 +296,7 @@ pub fn update_sync_job(
     let auth_id: Authid = rpcenv.get_auth_id().unwrap().parse()?;
     let user_info = CachedUserInfo::new()?;
 
-    let _lock = open_file_locked(sync::SYNC_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(sync::SYNC_CFG_LOCKFILE, None, true)?;
 
     // pass/compare digest
     let (mut config, expected_digest) = sync::config()?;
@@ -379,7 +379,7 @@ pub fn delete_sync_job(
     let auth_id: Authid = rpcenv.get_auth_id().unwrap().parse()?;
     let user_info = CachedUserInfo::new()?;
 
-    let _lock = open_file_locked(sync::SYNC_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(sync::SYNC_CFG_LOCKFILE, None, true)?;
 
     let (mut config, expected_digest) = sync::config()?;
 
diff --git a/src/api2/config/tape_backup_job.rs b/src/api2/config/tape_backup_job.rs
index 22afeb6d..02fa6f7d 100644
--- a/src/api2/config/tape_backup_job.rs
+++ b/src/api2/config/tape_backup_job.rs
@@ -3,7 +3,6 @@ use serde_json::Value;
 use ::serde::{Deserialize, Serialize};
 
 use proxmox::api::{api, Router, RpcEnvironment, Permission};
-use proxmox::tools::fs::open_file_locked;
 
 use crate::{
     api2::types::{
@@ -17,6 +16,7 @@ use crate::{
         MEDIA_POOL_NAME_SCHEMA,
         SYNC_SCHEDULE_SCHEMA,
     },
+    backup::open_backup_lockfile,
     config::{
         self,
         cached_user_info::CachedUserInfo,
@@ -89,8 +89,7 @@ pub fn create_tape_backup_job(
     job: TapeBackupJobConfig,
     _rpcenv: &mut dyn RpcEnvironment,
 ) -> Result<(), Error> {
-
-    let _lock = open_file_locked(TAPE_JOB_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(TAPE_JOB_CFG_LOCKFILE, None, true)?;
 
     let (mut config, _digest) = config::tape_job::config()?;
 
@@ -233,7 +232,7 @@ pub fn update_tape_backup_job(
     delete: Option<Vec<DeletableProperty>>,
     digest: Option<String>,
 ) -> Result<(), Error> {
-    let _lock = open_file_locked(TAPE_JOB_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(TAPE_JOB_CFG_LOCKFILE, None, true)?;
 
     let (mut config, expected_digest) = config::tape_job::config()?;
 
@@ -312,7 +311,7 @@ pub fn delete_tape_backup_job(
     digest: Option<String>,
     _rpcenv: &mut dyn RpcEnvironment,
 ) -> Result<(), Error> {
-    let _lock = open_file_locked(TAPE_JOB_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(TAPE_JOB_CFG_LOCKFILE, None, true)?;
 
     let (mut config, expected_digest) = config::tape_job::config()?;
 
diff --git a/src/api2/config/tape_encryption_keys.rs b/src/api2/config/tape_encryption_keys.rs
index e1b42fb8..6fbfaded 100644
--- a/src/api2/config/tape_encryption_keys.rs
+++ b/src/api2/config/tape_encryption_keys.rs
@@ -9,7 +9,6 @@ use proxmox::{
         RpcEnvironment,
         Permission,
     },
-    tools::fs::open_file_locked,
 };
 
 use pbs_datastore::{KeyInfo, Kdf};
@@ -35,6 +34,7 @@ use crate::{
         PASSWORD_HINT_SCHEMA,
     },
     backup::{
+        open_backup_lockfile,
         KeyConfig,
         Fingerprint,
     },
@@ -122,11 +122,7 @@ pub fn change_passphrase(
         bail!("Please specify a key derivation function (none is not allowed here).");
     }
 
-    let _lock = open_file_locked(
-        TAPE_KEYS_LOCKFILE,
-        std::time::Duration::new(10, 0),
-        true,
-    )?;
+    let _lock = open_backup_lockfile(TAPE_KEYS_LOCKFILE, None, true)?;
 
     let (mut config_map, expected_digest) = load_key_configs()?;
 
@@ -261,12 +257,7 @@ pub fn delete_key(
     digest: Option<String>,
     _rpcenv: &mut dyn RpcEnvironment,
 ) -> Result<(), Error> {
-
-    let _lock = open_file_locked(
-        TAPE_KEYS_LOCKFILE,
-        std::time::Duration::new(10, 0),
-        true,
-    )?;
+    let _lock = open_backup_lockfile(TAPE_KEYS_LOCKFILE, None, true)?;
 
     let (mut config_map, expected_digest) = load_key_configs()?;
     let (mut key_map, _) = load_keys()?;
diff --git a/src/api2/config/verify.rs b/src/api2/config/verify.rs
index 477cda89..1a613327 100644
--- a/src/api2/config/verify.rs
+++ b/src/api2/config/verify.rs
@@ -3,7 +3,6 @@ use serde_json::Value;
 use ::serde::{Deserialize, Serialize};
 
 use proxmox::api::{api, Permission, Router, RpcEnvironment};
-use proxmox::tools::fs::open_file_locked;
 
 use crate::api2::types::*;
 
@@ -13,8 +12,8 @@ use crate::config::acl::{
 };
 
 use crate::config::cached_user_info::CachedUserInfo;
-
 use crate::config::verify::{self, VerificationJobConfig};
+use crate::backup::open_backup_lockfile;
 
 #[api(
     input: {
@@ -102,7 +101,7 @@ pub fn create_verification_job(
 
     user_info.check_privs(&auth_id, &["datastore", &verification_job.store], PRIV_DATASTORE_VERIFY, false)?;
 
-    let _lock = open_file_locked(verify::VERIFICATION_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(verify::VERIFICATION_CFG_LOCKFILE, None, true)?;
 
     let (mut config, _digest) = verify::config()?;
 
@@ -230,7 +229,7 @@ pub fn update_verification_job(
     let auth_id: Authid = rpcenv.get_auth_id().unwrap().parse()?;
     let user_info = CachedUserInfo::new()?;
 
-    let _lock = open_file_locked(verify::VERIFICATION_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(verify::VERIFICATION_CFG_LOCKFILE, None, true)?;
 
     // pass/compare digest
     let (mut config, expected_digest) = verify::config()?;
@@ -315,7 +314,7 @@ pub fn delete_verification_job(
     let auth_id: Authid = rpcenv.get_auth_id().unwrap().parse()?;
     let user_info = CachedUserInfo::new()?;
 
-    let _lock = open_file_locked(verify::VERIFICATION_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(verify::VERIFICATION_CFG_LOCKFILE, None, true)?;
 
     let (mut config, expected_digest) = verify::config()?;
 
diff --git a/src/api2/node/disks/directory.rs b/src/api2/node/disks/directory.rs
index ae8a3974..75e0ea02 100644
--- a/src/api2/node/disks/directory.rs
+++ b/src/api2/node/disks/directory.rs
@@ -5,7 +5,6 @@ use ::serde::{Deserialize, Serialize};
 use proxmox::api::{api, Permission, RpcEnvironment, RpcEnvironmentType};
 use proxmox::api::section_config::SectionConfigData;
 use proxmox::api::router::Router;
-use proxmox::tools::fs::open_file_locked;
 
 use crate::config::acl::{PRIV_SYS_AUDIT, PRIV_SYS_MODIFY};
 use crate::tools::disks::{
@@ -18,6 +17,7 @@ use crate::server::WorkerTask;
 
 use crate::api2::types::*;
 use crate::config::datastore::{self, DataStoreConfig};
+use crate::backup::open_backup_lockfile;
 
 #[api(
     properties: {
@@ -180,7 +180,7 @@ pub fn create_datastore_disk(
             systemd::start_unit(&mount_unit_name)?;
 
             if add_datastore {
-                let lock = open_file_locked(datastore::DATASTORE_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+                let lock = open_backup_lockfile(datastore::DATASTORE_CFG_LOCKFILE, None, true)?;
                 let datastore: DataStoreConfig =
                     serde_json::from_value(json!({ "name": name, "path": mount_point }))?;
 
diff --git a/src/api2/node/network.rs b/src/api2/node/network.rs
index 0dc321b8..ecf112a4 100644
--- a/src/api2/node/network.rs
+++ b/src/api2/node/network.rs
@@ -4,12 +4,12 @@ use ::serde::{Deserialize, Serialize};
 
 use proxmox::api::{api, ApiMethod, Router, RpcEnvironment, Permission};
 use proxmox::api::schema::parse_property_string;
-use proxmox::tools::fs::open_file_locked;
 
 use crate::config::network::{self, NetworkConfig};
 use crate::config::acl::{PRIV_SYS_AUDIT, PRIV_SYS_MODIFY};
 use crate::api2::types::*;
 use crate::server::{WorkerTask};
+use crate::backup::open_backup_lockfile;
 
 fn split_interface_list(list: &str) -> Result<Vec<String>, Error> {
     let value = parse_property_string(&list, &NETWORK_INTERFACE_ARRAY_SCHEMA)?;
@@ -238,7 +238,7 @@ pub fn create_interface(
     let interface_type = crate::tools::required_string_param(&param, "type")?;
     let interface_type: NetworkInterfaceType = serde_json::from_value(interface_type.into())?;
 
-    let _lock = open_file_locked(network::NETWORK_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(network::NETWORK_LOCKFILE, None, true)?;
 
     let (mut config, _digest) = network::config()?;
 
@@ -502,7 +502,7 @@ pub fn update_interface(
     param: Value,
 ) -> Result<(), Error> {
 
-    let _lock = open_file_locked(network::NETWORK_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(network::NETWORK_LOCKFILE, None, true)?;
 
     let (mut config, expected_digest) = network::config()?;
 
@@ -642,8 +642,7 @@ pub fn update_interface(
 )]
 /// Remove network interface configuration.
 pub fn delete_interface(iface: String, digest: Option<String>) -> Result<(), Error> {
-
-    let _lock = open_file_locked(network::NETWORK_LOCKFILE, std::time::Duration::new(10, 0), true)?;
+    let _lock = open_backup_lockfile(network::NETWORK_LOCKFILE, None, true)?;
 
     let (mut config, expected_digest) = network::config()?;
 
diff --git a/src/backup/datastore.rs b/src/backup/datastore.rs
index d47c412b..5695adcc 100644
--- a/src/backup/datastore.rs
+++ b/src/backup/datastore.rs
@@ -5,12 +5,11 @@ use std::sync::{Arc, Mutex};
 use std::convert::TryFrom;
 use std::str::FromStr;
 use std::time::Duration;
-use std::fs::File;
 
 use anyhow::{bail, format_err, Error};
 use lazy_static::lazy_static;
 
-use proxmox::tools::fs::{replace_file, file_read_optional_string, CreateOptions, open_file_locked};
+use proxmox::tools::fs::{replace_file, file_read_optional_string, CreateOptions};
 
 use pbs_api_types::upid::UPID;
 use pbs_api_types::{Authid, GarbageCollectionStatus};
@@ -32,6 +31,8 @@ use pbs_tools::fs::{lock_dir_noblock, DirLockGuard};
 
 use crate::config::datastore::{self, DataStoreConfig};
 use crate::tools;
+use crate::backup::{open_backup_lockfile, BackupLockGuard};
+
 
 lazy_static! {
     static ref DATASTORE_MAP: Mutex<HashMap<String, Arc<DataStore>>> = Mutex::new(HashMap::new());
@@ -777,12 +778,12 @@ impl DataStore {
     fn lock_manifest(
         &self,
         backup_dir: &BackupDir,
-    ) -> Result<File, Error> {
+    ) -> Result<BackupLockGuard, Error> {
         let path = self.manifest_lock_path(backup_dir)?;
 
         // update_manifest should never take a long time, so if someone else has
         // the lock we can simply block a bit and should get it soon
-        open_file_locked(&path, Duration::from_secs(5), true)
+        open_backup_lockfile(&path, Some(Duration::from_secs(5)), true)
             .map_err(|err| {
                 format_err!(
                     "unable to acquire manifest lock {:?} - {}", &path, err
diff --git a/src/backup/mod.rs b/src/backup/mod.rs
index 4161b402..1db61cf5 100644
--- a/src/backup/mod.rs
+++ b/src/backup/mod.rs
@@ -108,3 +108,29 @@ pub use catalog_shell::*;
 
 mod cached_chunk_reader;
 pub use cached_chunk_reader::*;
+
+pub struct BackupLockGuard(std::fs::File);
+
+/// Open or create a lock file owned by user "backup" and lock it.
+///
+/// Owner/Group of the file is set to backup/backup.
+/// File mode is 0660.
+/// Default timeout is 10 seconds.
+///
+/// Note: This method needs to be called by user "root" or "backup".
+pub fn open_backup_lockfile<P: AsRef<std::path::Path>>(
+    path: P,
+    timeout: Option<std::time::Duration>,
+    exclusive: bool,
+) -> Result<BackupLockGuard, Error> {
+    let user = backup_user()?;
+    let options = proxmox::tools::fs::CreateOptions::new()
+        .perm(nix::sys::stat::Mode::from_bits_truncate(0o660))
+        .owner(user.uid)
+        .group(user.gid);
+
+    let timeout = timeout.unwrap_or(std::time::Duration::new(10, 0));
+
+    let file = proxmox::tools::fs::open_file_locked(&path, timeout, exclusive, options)?;
+    Ok(BackupLockGuard(file))
+}
diff --git a/src/config/acme/plugin.rs b/src/config/acme/plugin.rs
index 960aec3a..fde800e2 100644
--- a/src/config/acme/plugin.rs
+++ b/src/config/acme/plugin.rs
@@ -12,6 +12,7 @@ use proxmox::api::{
 use proxmox::tools::{fs::replace_file, fs::CreateOptions};
 
 use crate::api2::types::PROXMOX_SAFE_ID_FORMAT;
+use crate::backup::{open_backup_lockfile, BackupLockGuard};
 
 pub const PLUGIN_ID_SCHEMA: Schema = StringSchema::new("ACME Challenge Plugin ID.")
     .format(&PROXMOX_SAFE_ID_FORMAT)
@@ -142,11 +143,10 @@ fn init() -> SectionConfig {
 
 const ACME_PLUGIN_CFG_FILENAME: &str = pbs_buildcfg::configdir!("/acme/plugins.cfg");
 const ACME_PLUGIN_CFG_LOCKFILE: &str = pbs_buildcfg::configdir!("/acme/.plugins.lck");
-const LOCK_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(10);
 
-pub fn lock() -> Result<std::fs::File, Error> {
+pub fn lock() -> Result<BackupLockGuard, Error> {
     super::make_acme_dir()?;
-    proxmox::tools::fs::open_file_locked(ACME_PLUGIN_CFG_LOCKFILE, LOCK_TIMEOUT, true)
+    open_backup_lockfile(ACME_PLUGIN_CFG_LOCKFILE, None, true)
 }
 
 pub fn config() -> Result<(PluginData, [u8; 32]), Error> {
diff --git a/src/config/datastore.rs b/src/config/datastore.rs
index d22fa316..9e37073d 100644
--- a/src/config/datastore.rs
+++ b/src/config/datastore.rs
@@ -14,12 +14,12 @@ use proxmox::api::{
 };
 
 use proxmox::tools::fs::{
-    open_file_locked,
     replace_file,
     CreateOptions,
 };
 
 use crate::api2::types::*;
+use crate::backup::{open_backup_lockfile, BackupLockGuard};
 
 lazy_static! {
     pub static ref CONFIG: SectionConfig = init();
@@ -138,8 +138,8 @@ pub const DATASTORE_CFG_FILENAME: &str = "/etc/proxmox-backup/datastore.cfg";
 pub const DATASTORE_CFG_LOCKFILE: &str = "/etc/proxmox-backup/.datastore.lck";
 
 /// Get exclusive lock
-pub fn lock_config() -> Result<std::fs::File, Error> {
-    open_file_locked(DATASTORE_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)
+pub fn lock_config() -> Result<BackupLockGuard, Error> {
+    open_backup_lockfile(DATASTORE_CFG_LOCKFILE, None, true)
 }
 
 pub fn config() -> Result<(SectionConfigData, [u8;32]), Error> {
diff --git a/src/config/domains.rs b/src/config/domains.rs
index 775c02f3..9f513a44 100644
--- a/src/config/domains.rs
+++ b/src/config/domains.rs
@@ -14,12 +14,12 @@ use proxmox::api::{
 };
 
 use proxmox::tools::fs::{
-    open_file_locked,
     replace_file,
     CreateOptions,
 };
 
 use crate::api2::types::*;
+use crate::backup::{open_backup_lockfile, BackupLockGuard};
 
 lazy_static! {
     pub static ref CONFIG: SectionConfig = init();
@@ -110,8 +110,8 @@ pub const DOMAINS_CFG_FILENAME: &str = "/etc/proxmox-backup/domains.cfg";
 pub const DOMAINS_CFG_LOCKFILE: &str = "/etc/proxmox-backup/.domains.lck";
 
 /// Get exclusive lock
-pub fn lock_config() -> Result<std::fs::File, Error> {
-    open_file_locked(DOMAINS_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)
+pub fn lock_config() -> Result<BackupLockGuard, Error> {
+    open_backup_lockfile(DOMAINS_CFG_LOCKFILE, None, true)
 }
 
 pub fn config() -> Result<(SectionConfigData, [u8;32]), Error> {
diff --git a/src/config/drive.rs b/src/config/drive.rs
index 57f6911f..9c20051f 100644
--- a/src/config/drive.rs
+++ b/src/config/drive.rs
@@ -26,13 +26,13 @@ use proxmox::{
         },
     },
     tools::fs::{
-        open_file_locked,
         replace_file,
         CreateOptions,
     },
 };
 
 use crate::{
+    backup::{open_backup_lockfile, BackupLockGuard},
     api2::types::{
         DRIVE_NAME_SCHEMA,
         VirtualTapeDrive,
@@ -79,8 +79,8 @@ pub const DRIVE_CFG_FILENAME: &str = "/etc/proxmox-backup/tape.cfg";
 pub const DRIVE_CFG_LOCKFILE: &str = "/etc/proxmox-backup/.tape.lck";
 
 /// Get exclusive lock
-pub fn lock() -> Result<std::fs::File, Error> {
-    open_file_locked(DRIVE_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)
+pub fn lock() -> Result<BackupLockGuard, Error> {
+    open_backup_lockfile(DRIVE_CFG_LOCKFILE, None, true)
 }
 
 /// Read and parse the configuration file
diff --git a/src/config/media_pool.rs b/src/config/media_pool.rs
index 5ba1a6b2..e50992d8 100644
--- a/src/config/media_pool.rs
+++ b/src/config/media_pool.rs
@@ -21,13 +21,13 @@ use proxmox::{
         }
     },
     tools::fs::{
-        open_file_locked,
         replace_file,
         CreateOptions,
     },
 };
 
 use crate::{
+    backup::{open_backup_lockfile, BackupLockGuard},
     api2::types::{
         MEDIA_POOL_NAME_SCHEMA,
         MediaPoolConfig,
@@ -59,8 +59,8 @@ pub const MEDIA_POOL_CFG_LOCKFILE: &str = "/etc/proxmox-backup/.media-pool.lck";
 
 
 /// Get exclusive lock
-pub fn lock() -> Result<std::fs::File, Error> {
-    open_file_locked(MEDIA_POOL_CFG_LOCKFILE, std::time::Duration::new(10, 0), true)
+pub fn lock() -> Result<BackupLockGuard, Error> {
+    open_backup_lockfile(MEDIA_POOL_CFG_LOCKFILE, None, true)
 }
 
 /// Read and parse the configuration file
diff --git a/src/config/node.rs b/src/config/node.rs
index 27e32cd1..dc3eeeb0 100644
--- a/src/config/node.rs
+++ b/src/config/node.rs
@@ -1,6 +1,4 @@
 use std::collections::HashSet;
-use std::fs::File;
-use std::time::Duration;
 
 use anyhow::{bail, Error};
 use nix::sys::stat::Mode;
@@ -14,6 +12,7 @@ use proxmox_http::ProxyConfig;
 
 use pbs_buildcfg::configdir;
 
+use crate::backup::{open_backup_lockfile, BackupLockGuard};
 use crate::acme::AcmeClient;
 use crate::api2::types::{
     AcmeAccountName, AcmeDomain, ACME_DOMAIN_PROPERTY_SCHEMA, HTTP_PROXY_SCHEMA,
@@ -21,10 +20,9 @@ use crate::api2::types::{
 
 const CONF_FILE: &str = configdir!("/node.cfg");
 const LOCK_FILE: &str = configdir!("/.node.lck");
-const LOCK_TIMEOUT: Duration = Duration::from_secs(10);
 
-pub fn lock() -> Result<File, Error> {
-    proxmox::tools::fs::open_file_locked(LOCK_FILE, LOCK_TIMEOUT, true)
+pub fn lock() -> Result<BackupLockGuard, Error> {
+    open_backup_lockfile(LOCK_FILE, None, true)
 }
 
 /// Read the Node Config.
diff --git a/src/config/tape_encryption_keys.rs b/src/config/tape_encryption_keys.rs
index e3aab1d8..5ee0ac1f 100644
--- a/src/config/tape_encryption_keys.rs
+++ b/src/config/tape_encryption_keys.rs
@@ -18,12 +18,12 @@ use serde::{Deserialize, Serialize};
 use proxmox::tools::fs::{
     file_read_optional_string,
     replace_file,
-    open_file_locked,
     CreateOptions,
 };
 
 use crate::{
     backup::{
+        open_backup_lockfile,
         Fingerprint,
         KeyConfig,
     },
@@ -187,11 +187,7 @@ pub fn save_key_configs(map: HashMap<Fingerprint, KeyConfig>) -> Result<(), Erro
 /// Get the lock, load both files, insert the new key, store files.
 pub fn insert_key(key: [u8;32], key_config: KeyConfig, force: bool) -> Result<(), Error> {
 
-    let _lock = open_file_locked(
-        TAPE_KEYS_LOCKFILE,
-        std::time::Duration::new(10, 0),
-        true,
-    )?;
+    let _lock = open_backup_lockfile(TAPE_KEYS_LOCKFILE, None, true)?;
 
     let (mut key_map, _) = load_keys()?;
     let (mut config_map, _) = load_key_configs()?;
diff --git a/src/config/tfa.rs b/src/config/tfa.rs
index 341307db..efba0c13 100644
--- a/src/config/tfa.rs
+++ b/src/config/tfa.rs
@@ -4,7 +4,6 @@ use std::io::{self, Read, Seek, SeekFrom};
 use std::os::unix::fs::OpenOptionsExt;
 use std::os::unix::io::AsRawFd;
 use std::path::PathBuf;
-use std::time::Duration;
 
 use anyhow::{bail, format_err, Error};
 use nix::sys::stat::Mode;
@@ -29,25 +28,25 @@ use proxmox::tools::AsHex;
 use pbs_buildcfg::configdir;
 
 use crate::api2::types::Userid;
+use crate::backup::{open_backup_lockfile, BackupLockGuard};
 
 /// Mapping of userid to TFA entry.
 pub type TfaUsers = HashMap<Userid, TfaUserData>;
 
 const CONF_FILE: &str = configdir!("/tfa.json");
 const LOCK_FILE: &str = configdir!("/tfa.json.lock");
-const LOCK_TIMEOUT: Duration = Duration::from_secs(5);
 
 const CHALLENGE_DATA_PATH: &str = pbs_buildcfg::rundir!("/tfa/challenges");
 
 /// U2F registration challenges time out after 2 minutes.
 const CHALLENGE_TIMEOUT: i64 = 2 * 60;
 
-pub fn read_lock() -> Result<File, Error> {
-    proxmox::tools::fs::open_file_locked(LOCK_FILE, LOCK_TIMEOUT, false)
+pub fn read_lock() -> Result<BackupLockGuard, Error> {
+    open_backup_lockfile(LOCK_FILE, None, false)
 }
 
-pub fn write_lock() -> Result<File, Error> {
-    proxmox::tools::fs::open_file_locked(LOCK_FILE, LOCK_TIMEOUT, true)
+pub fn write_lock() -> Result<BackupLockGuard, Error> {
+    open_backup_lockfile(LOCK_FILE, None, true)
 }
 
 /// Read the TFA entries.
diff --git a/src/config/token_shadow.rs b/src/config/token_shadow.rs
index 9f8bb2e0..a210ffb2 100644
--- a/src/config/token_shadow.rs
+++ b/src/config/token_shadow.rs
@@ -1,18 +1,17 @@
 use std::collections::HashMap;
-use std::time::Duration;
 
 use anyhow::{bail, format_err, Error};
 use serde::{Serialize, Deserialize};
 use serde_json::{from_value, Value};
 
-use proxmox::tools::fs::{open_file_locked, CreateOptions};
+use proxmox::tools::fs::CreateOptions;
 
 use crate::api2::types::Authid;
 use crate::auth;
+use crate::backup::open_backup_lockfile;
 
 const LOCK_FILE: &str = pbs_buildcfg::configdir!("/token.shadow.lock");
 const CONF_FILE: &str = pbs_buildcfg::configdir!("/token.shadow");
-const LOCK_TIMEOUT: Duration = Duration::from_secs(5);
 
 #[derive(Serialize, Deserialize)]
 #[serde(rename_all="kebab-case")]
@@ -65,7 +64,7 @@ pub fn set_secret(tokenid: &Authid, secret: &str) -> Result<(), Error> {
         bail!("not an API token ID");
     }
 
-    let _guard = open_file_locked(LOCK_FILE, LOCK_TIMEOUT, true)?;
+    let _guard = open_backup_lockfile(LOCK_FILE, None, true)?;
 
     let mut data = read_file()?;
     let hashed_secret = auth::encrypt_pw(secret)?;
@@ -81,7 +80,7 @@ pub fn delete_secret(tokenid: &Authid) -> Result<(), Error> {
         bail!("not an API token ID");
     }
 
-    let _guard = open_file_locked(LOCK_FILE, LOCK_TIMEOUT, true)?;
+    let _guard = open_backup_lockfile(LOCK_FILE, None, true)?;
 
     let mut data = read_file()?;
     data.remove(tokenid);
diff --git a/src/server/jobstate.rs b/src/server/jobstate.rs
index 96dd21aa..4b15fabc 100644
--- a/src/server/jobstate.rs
+++ b/src/server/jobstate.rs
@@ -37,18 +37,17 @@
 //! # }
 //!
 //! ```
-use std::fs::File;
 use std::path::{Path, PathBuf};
-use std::time::Duration;
 
 use anyhow::{bail, format_err, Error};
 use proxmox::tools::fs::{
-    create_path, file_read_optional_string, open_file_locked, replace_file, CreateOptions,
+    create_path, file_read_optional_string, replace_file, CreateOptions,
 };
 use serde::{Deserialize, Serialize};
 
 use crate::{
-   tools::systemd::time::{
+    backup::{open_backup_lockfile, BackupLockGuard},
+    tools::systemd::time::{
         parse_calendar_event,
         compute_next_event,
     },
@@ -83,7 +82,7 @@ pub struct Job {
     jobname: String,
     /// The State of the job
     pub state: JobState,
-    _lock: File,
+    _lock: BackupLockGuard,
 }
 
 const JOB_STATE_BASEDIR: &str = "/var/lib/proxmox-backup/jobstates";
@@ -107,16 +106,13 @@ fn get_path(jobtype: &str, jobname: &str) -> PathBuf {
     path
 }
 
-fn get_lock<P>(path: P) -> Result<File, Error>
+fn get_lock<P>(path: P) -> Result<BackupLockGuard, Error>
 where
     P: AsRef<Path>,
 {
     let mut path = path.as_ref().to_path_buf();
     path.set_extension("lck");
-    let lock = open_file_locked(&path, Duration::new(10, 0), true)?;
-    let backup_user = crate::backup::backup_user()?;
-    nix::unistd::chown(&path, Some(backup_user.uid), Some(backup_user.gid))?;
-    Ok(lock)
+    open_backup_lockfile(&path, None, true)
 }
 
 /// Removes the statefile of a job, this is useful if we delete a job
diff --git a/src/server/worker_task.rs b/src/server/worker_task.rs
index 13578446..8507842b 100644
--- a/src/server/worker_task.rs
+++ b/src/server/worker_task.rs
@@ -14,7 +14,7 @@ use tokio::sync::oneshot;
 
 use proxmox::sys::linux::procfs;
 use proxmox::try_block;
-use proxmox::tools::fs::{create_path, open_file_locked, replace_file, CreateOptions};
+use proxmox::tools::fs::{create_path, replace_file, CreateOptions};
 
 use super::{UPID, UPIDExt};
 
@@ -24,6 +24,7 @@ use crate::server;
 use crate::tools::logrotate::{LogRotate, LogRotateFiles};
 use crate::tools::{FileLogger, FileLogOptions};
 use crate::api2::types::{Authid, TaskStateType};
+use crate::backup::{open_backup_lockfile, BackupLockGuard};
 
 macro_rules! taskdir {
     ($subdir:expr) => (concat!(pbs_buildcfg::PROXMOX_BACKUP_LOG_DIR_M!(), "/tasks", $subdir))
@@ -313,13 +314,8 @@ pub struct TaskListInfo {
     pub state: Option<TaskState>, // endtime, status
 }
 
-fn lock_task_list_files(exclusive: bool) -> Result<std::fs::File, Error> {
-    let backup_user = crate::backup::backup_user()?;
-
-    let lock = open_file_locked(PROXMOX_BACKUP_TASK_LOCK_FN, std::time::Duration::new(10, 0), exclusive)?;
-    nix::unistd::chown(PROXMOX_BACKUP_TASK_LOCK_FN, Some(backup_user.uid), Some(backup_user.gid))?;
-
-    Ok(lock)
+fn lock_task_list_files(exclusive: bool) -> Result<BackupLockGuard, Error> {
+    open_backup_lockfile(PROXMOX_BACKUP_TASK_LOCK_FN, None, exclusive)
 }
 
 /// checks if the Task Archive is bigger that 'size_threshold' bytes, and
@@ -481,7 +477,7 @@ pub struct TaskListInfoIterator {
     list: VecDeque<TaskListInfo>,
     end: bool,
     archive: Option<LogRotateFiles>,
-    lock: Option<File>,
+    lock: Option<BackupLockGuard>,
 }
 
 impl TaskListInfoIterator {
diff --git a/src/tape/drive/mod.rs b/src/tape/drive/mod.rs
index fb4b6f47..a6cbed84 100644
--- a/src/tape/drive/mod.rs
+++ b/src/tape/drive/mod.rs
@@ -5,19 +5,21 @@ mod virtual_tape;
 mod lto;
 pub use lto::*;
 
-use std::os::unix::io::AsRawFd;
 use std::path::PathBuf;
 
 use anyhow::{bail, format_err, Error};
 use ::serde::{Deserialize};
 use serde_json::Value;
+use nix::fcntl::OFlag;
+use nix::sys::stat::Mode;
 
 use proxmox::{
     tools::{
         Uuid,
         io::ReadExt,
         fs::{
-            fchown,
+            lock_file,
+            atomic_open_or_create_file,
             file_read_optional_string,
             replace_file,
             CreateOptions,
@@ -604,20 +606,34 @@ fn tape_device_path(
 
 pub struct DeviceLockGuard(std::fs::File);
 
-// Acquires an exclusive lock on `device_path`
-//
 // Uses systemd escape_unit to compute a file name from `device_path`, the try
 // to lock `/var/lock/<name>`.
-fn lock_device_path(device_path: &str) -> Result<DeviceLockGuard, TapeLockError> {
-
+fn open_device_lock(device_path: &str) -> Result<std::fs::File, Error> {
     let lock_name = crate::tools::systemd::escape_unit(device_path, true);
 
     let mut path = std::path::PathBuf::from(crate::tape::DRIVE_LOCK_DIR);
     path.push(lock_name);
 
+    let user = crate::backup::backup_user()?;
+    let options = CreateOptions::new()
+        .perm(Mode::from_bits_truncate(0o660))
+        .owner(user.uid)
+        .group(user.gid);
+
+    atomic_open_or_create_file(
+        path,
+        OFlag::O_RDWR | OFlag::O_CLOEXEC | OFlag::O_APPEND,
+        &[],
+        options,
+    )
+}
+
+// Acquires an exclusive lock on `device_path`
+//
+fn lock_device_path(device_path: &str) -> Result<DeviceLockGuard, TapeLockError> {
+    let mut file = open_device_lock(device_path)?; 
     let timeout = std::time::Duration::new(10, 0);
-    let mut file = std::fs::OpenOptions::new().create(true).append(true).open(path)?;
-    if let Err(err) =  proxmox::tools::fs::lock_file(&mut file, true, Some(timeout)) {
+    if let Err(err) = lock_file(&mut file, true, Some(timeout)) {
         if err.kind() == std::io::ErrorKind::Interrupted {
             return Err(TapeLockError::TimeOut);
         } else {
@@ -625,9 +641,6 @@ fn lock_device_path(device_path: &str) -> Result<DeviceLockGuard, TapeLockError>
         }
     }
 
-    let backup_user = crate::backup::backup_user()?;
-    fchown(file.as_raw_fd(), Some(backup_user.uid), Some(backup_user.gid))?;
-
     Ok(DeviceLockGuard(file))
 }
 
@@ -635,14 +648,10 @@ fn lock_device_path(device_path: &str) -> Result<DeviceLockGuard, TapeLockError>
 // non-blocking, and returning if the file is locked or not
 fn test_device_path_lock(device_path: &str) -> Result<bool, Error> {
 
-    let lock_name = crate::tools::systemd::escape_unit(device_path, true);
-
-    let mut path = std::path::PathBuf::from(crate::tape::DRIVE_LOCK_DIR);
-    path.push(lock_name);
+    let mut file = open_device_lock(device_path)?; 
 
     let timeout = std::time::Duration::new(0, 0);
-    let mut file = std::fs::OpenOptions::new().create(true).append(true).open(path)?;
-    match proxmox::tools::fs::lock_file(&mut file, true, Some(timeout)) {
+    match lock_file(&mut file, true, Some(timeout)) {
         // file was not locked, continue
         Ok(()) => {},
         // file was locked, return true
@@ -650,8 +659,5 @@ fn test_device_path_lock(device_path: &str) -> Result<bool, Error> {
         Err(err) => bail!("{}", err),
     }
 
-    let backup_user = crate::backup::backup_user()?;
-    fchown(file.as_raw_fd(), Some(backup_user.uid), Some(backup_user.gid))?;
-
     Ok(false)
 }
diff --git a/src/tape/drive/virtual_tape.rs b/src/tape/drive/virtual_tape.rs
index 3c5f9502..f48afa79 100644
--- a/src/tape/drive/virtual_tape.rs
+++ b/src/tape/drive/virtual_tape.rs
@@ -49,8 +49,9 @@ impl VirtualTapeDrive {
             let mut lock_path = std::path::PathBuf::from(&self.path);
             lock_path.push(".drive.lck");
 
+            let options = CreateOptions::new();
             let timeout = std::time::Duration::new(10, 0);
-            let lock = proxmox::tools::fs::open_file_locked(&lock_path, timeout, true)?;
+            let lock = proxmox::tools::fs::open_file_locked(&lock_path, timeout, true, options)?;
 
             Ok(VirtualTapeHandle {
                 _lock: lock,
diff --git a/src/tape/inventory.rs b/src/tape/inventory.rs
index 4bb6d4f8..e97f07f3 100644
--- a/src/tape/inventory.rs
+++ b/src/tape/inventory.rs
@@ -24,8 +24,6 @@
 
 use std::collections::{HashMap, BTreeMap};
 use std::path::{Path, PathBuf};
-use std::os::unix::io::AsRawFd;
-use std::fs::File;
 use std::time::Duration;
 
 use anyhow::{bail, Error};
@@ -35,9 +33,7 @@ use serde_json::json;
 use proxmox::tools::{
     Uuid,
     fs::{
-        open_file_locked,
         replace_file,
-        fchown,
         file_get_json,
         CreateOptions,
     },
@@ -51,6 +47,7 @@ use crate::{
         MediaStatus,
         MediaLocation,
     },
+    backup::{open_backup_lockfile, BackupLockGuard},
     tape::{
         TAPE_STATUS_DIR,
         MediaSet,
@@ -149,17 +146,8 @@ impl Inventory {
     }
 
     /// Lock the database
-    fn lock(&self) -> Result<std::fs::File, Error> {
-        let file = open_file_locked(&self.lockfile_path, std::time::Duration::new(10, 0), true)?;
-        if cfg!(test) {
-            // We cannot use chown inside test environment (no permissions)
-            return Ok(file);
-        }
-
-        let backup_user = crate::backup::backup_user()?;
-        fchown(file.as_raw_fd(), Some(backup_user.uid), Some(backup_user.gid))?;
-
-        Ok(file)
+    fn lock(&self) -> Result<BackupLockGuard, Error> {
+        open_backup_lockfile(&self.lockfile_path, None, true)
     }
 
     fn load_media_db(path: &Path) -> Result<BTreeMap<Uuid, MediaStateEntry>, Error> {
@@ -756,27 +744,16 @@ impl Inventory {
 }
 
 /// Lock a media pool
-pub fn lock_media_pool(base_path: &Path, name: &str) -> Result<File, Error> {
+pub fn lock_media_pool(base_path: &Path, name: &str) -> Result<BackupLockGuard, Error> {
     let mut path = base_path.to_owned();
     path.push(format!(".pool-{}", name));
     path.set_extension("lck");
 
-    let timeout = std::time::Duration::new(10, 0);
-    let lock = proxmox::tools::fs::open_file_locked(&path, timeout, true)?;
-
-    if cfg!(test) {
-        // We cannot use chown inside test environment (no permissions)
-        return Ok(lock);
-    }
-
-    let backup_user = crate::backup::backup_user()?;
-    fchown(lock.as_raw_fd(), Some(backup_user.uid), Some(backup_user.gid))?;
-
-    Ok(lock)
+    open_backup_lockfile(&path, None, true)
 }
 
 /// Lock for media not assigned to any pool
-pub fn lock_unassigned_media_pool(base_path: &Path)  -> Result<File, Error> {
+pub fn lock_unassigned_media_pool(base_path: &Path)  -> Result<BackupLockGuard, Error> {
     // lock artificial "__UNASSIGNED__" pool to avoid races
     lock_media_pool(base_path, "__UNASSIGNED__")
 }
@@ -788,22 +765,12 @@ pub fn lock_media_set(
     base_path: &Path,
     media_set_uuid: &Uuid,
     timeout: Option<Duration>,
-) -> Result<File, Error> {
+) -> Result<BackupLockGuard, Error> {
     let mut path = base_path.to_owned();
     path.push(format!(".media-set-{}", media_set_uuid));
     path.set_extension("lck");
 
-    let timeout = timeout.unwrap_or(Duration::new(10, 0));
-    let file = open_file_locked(&path, timeout, true)?;
-    if cfg!(test) {
-        // We cannot use chown inside test environment (no permissions)
-        return Ok(file);
-    }
-
-    let backup_user = crate::backup::backup_user()?;
-    fchown(file.as_raw_fd(), Some(backup_user.uid), Some(backup_user.gid))?;
-
-    Ok(file)
+    open_backup_lockfile(&path, timeout, true)
 }
 
 // shell completion helper
diff --git a/src/tape/media_pool.rs b/src/tape/media_pool.rs
index dd471551..7bb7fbdb 100644
--- a/src/tape/media_pool.rs
+++ b/src/tape/media_pool.rs
@@ -8,7 +8,6 @@
 //!
 
 use std::path::{PathBuf, Path};
-use std::fs::File;
 
 use anyhow::{bail, Error};
 use ::serde::{Deserialize, Serialize};
@@ -16,7 +15,7 @@ use ::serde::{Deserialize, Serialize};
 use proxmox::tools::Uuid;
 
 use crate::{
-    backup::Fingerprint,
+    backup::{Fingerprint, BackupLockGuard},
     api2::types::{
         MediaStatus,
         MediaLocation,
@@ -61,7 +60,7 @@ pub struct MediaPool {
     inventory: Inventory,
 
     current_media_set: MediaSet,
-    current_media_set_lock: Option<File>,
+    current_media_set_lock: Option<BackupLockGuard>,
 }
 
 impl MediaPool {
diff --git a/src/tools/memcom.rs b/src/tools/memcom.rs
index 9921f5c9..87b73561 100644
--- a/src/tools/memcom.rs
+++ b/src/tools/memcom.rs
@@ -1,21 +1,17 @@
 //! Memory based communication channel between proxy & daemon for things such as cache
 //! invalidation.
 
-use std::ffi::CString;
-use std::io;
 use std::os::unix::io::AsRawFd;
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::Arc;
 
-use anyhow::{bail, format_err, Error};
-use nix::errno::Errno;
+use anyhow::Error;
 use nix::fcntl::OFlag;
 use nix::sys::mman::{MapFlags, ProtFlags};
 use nix::sys::stat::Mode;
 use once_cell::sync::OnceCell;
 
-use proxmox::sys::error::SysError;
-use proxmox::tools::fd::Fd;
+use proxmox::tools::fs::CreateOptions;
 use proxmox::tools::mmap::Mmap;
 
 /// In-memory communication channel.
@@ -32,6 +28,7 @@ struct Head {
 static INSTANCE: OnceCell<Arc<Memcom>> = OnceCell::new();
 
 const MEMCOM_FILE_PATH: &str = pbs_buildcfg::rundir!("/proxmox-backup-memcom");
+const EMPTY_PAGE: [u8; 4096] = [0u8; 4096];
 
 impl Memcom {
     /// Open the memory based communication channel singleton.
@@ -41,15 +38,20 @@ impl Memcom {
 
     // Actual work of `new`:
     fn open() -> Result<Arc<Self>, Error> {
-        let fd = match open_existing() {
-            Ok(fd) => fd,
-            Err(err) if err.not_found() => create_new()?,
-            Err(err) => bail!("failed to open {} - {}", MEMCOM_FILE_PATH, err),
-        };
+        let user = crate::backup::backup_user()?;
+        let options = CreateOptions::new()
+            .perm(Mode::from_bits_truncate(0o660))
+            .owner(user.uid)
+            .group(user.gid);
+
+        let file = proxmox::tools::fs::atomic_open_or_create_file(
+            MEMCOM_FILE_PATH,
+            OFlag::O_RDWR | OFlag::O_CLOEXEC,
+            &EMPTY_PAGE, options)?;
 
         let mmap = unsafe {
             Mmap::<u8>::map_fd(
-                fd.as_raw_fd(),
+                file.as_raw_fd(),
                 0,
                 4096,
                 ProtFlags::PROT_READ | ProtFlags::PROT_WRITE,
@@ -77,87 +79,3 @@ impl Memcom {
             .fetch_add(1, Ordering::AcqRel);
     }
 }
-
-/// The fast path opens an existing file.
-fn open_existing() -> Result<Fd, nix::Error> {
-    Fd::open(
-        MEMCOM_FILE_PATH,
-        OFlag::O_RDWR | OFlag::O_CLOEXEC,
-        Mode::empty(),
-    )
-}
-
-/// Since we need to initialize the file, we also need a solid slow path where we create the file.
-/// In order to make sure the next user's `open()` vs `mmap()` race against our `truncate()` call,
-/// we create it in a temporary location and rotate it in place.
-fn create_new() -> Result<Fd, Error> {
-    // create a temporary file:
-    let temp_file_name = format!("{}.{}", MEMCOM_FILE_PATH, unsafe { libc::getpid() });
-    let fd = Fd::open(
-        temp_file_name.as_str(),
-        OFlag::O_CREAT | OFlag::O_EXCL | OFlag::O_RDWR | OFlag::O_CLOEXEC,
-        Mode::from_bits_truncate(0o660),
-    )
-    .map_err(|err| {
-        format_err!(
-            "failed to create new in-memory communication file at {} - {}",
-            temp_file_name,
-            err
-        )
-    })?;
-
-    // let it be a page in size, it'll be initialized to zero by the kernel
-    nix::unistd::ftruncate(fd.as_raw_fd(), 4096)
-        .map_err(|err| format_err!("failed to set size of {} - {}", temp_file_name, err))?;
-
-    // if this is the pbs-daemon (running as root) rather than the proxy (running as backup user),
-    // make sure the backup user can access the file:
-    if let Ok(backup_user) = crate::backup::backup_user() {
-        match nix::unistd::fchown(fd.as_raw_fd(), None, Some(backup_user.gid)) {
-            Ok(()) => (),
-            Err(err) if err.is_errno(Errno::EPERM) => {
-                // we're not the daemon (root), so the file is already owned by the backup user
-            }
-            Err(err) => bail!(
-                "failed to set group to 'backup' for {} - {}",
-                temp_file_name,
-                err
-            ),
-        }
-    }
-
-    // rotate the file into place, but use `RENAME_NOREPLACE`, so in case 2 processes race against
-    // the initialization, the first one wins!
-    // TODO: nicer `renameat2()` wrapper in `proxmox::sys`?
-    let c_file_name = CString::new(temp_file_name.as_bytes()).unwrap();
-    let new_path = CString::new(MEMCOM_FILE_PATH).unwrap();
-    let rc = unsafe {
-        libc::renameat2(
-            -1,
-            c_file_name.as_ptr(),
-            -1,
-            new_path.as_ptr(),
-            libc::RENAME_NOREPLACE,
-        )
-    };
-    if rc == 0 {
-        return Ok(fd);
-    }
-    let err = io::Error::last_os_error();
-
-    // if another process has already raced ahead and created the file, let's just open theirs
-    // instead:
-    if err.kind() == io::ErrorKind::AlreadyExists {
-        // someone beat us to it:
-        drop(fd);
-        return open_existing().map_err(Error::from);
-    }
-
-    // for any other errors, just bail out
-    bail!(
-        "failed to move file at {} into place at {} - {}",
-        temp_file_name,
-        MEMCOM_FILE_PATH,
-        err
-    );
-}
-- 
2.30.2