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From: Dominik Csapak <d.csapak@proxmox.com>
To: pbs-devel@lists.proxmox.com
Date: Wed, 2 Jun 2021 14:19:19 +0200
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information. [mod.rs, backup.rs]
Subject: [pbs-devel] [PATCH proxmox-backup v2] tape/drive: improve tape
device locking behaviour
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by implementing a custom error type that is either 'TimeOut' or
'Other'.
In the api, check in the worker loop for exactly 'TimeOut' errors and continue only
then. All other errors lead to a aborted task.
Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
---
changes from v1:
* implement custom error types, so that we can detect the one
special error condition more cleanly
src/api2/tape/backup.rs | 14 +++++++++-----
src/tape/drive/mod.rs | 34 +++++++++++++++++++++++++++++-----
2 files changed, 38 insertions(+), 10 deletions(-)
diff --git a/src/api2/tape/backup.rs b/src/api2/tape/backup.rs
index 77b11bb0..c3b541c7 100644
--- a/src/api2/tape/backup.rs
+++ b/src/api2/tape/backup.rs
@@ -65,6 +65,7 @@ use crate::{
drive::{
media_changer,
lock_tape_device,
+ TapeLockError,
set_tape_device_state,
},
changer::update_changer_online_status,
@@ -203,12 +204,15 @@ pub fn do_tape_backup_job(
// for scheduled tape backup jobs, we wait indefinitely for the lock
task_log!(worker, "waiting for drive lock...");
loop {
- if let Ok(lock) = lock_tape_device(&drive_config, &setup.drive) {
- drive_lock = Some(lock);
- break;
- } // ignore errors
-
worker.check_abort()?;
+ match lock_tape_device(&drive_config, &setup.drive) {
+ Ok(lock) => {
+ drive_lock = Some(lock);
+ break;
+ }
+ Err(TapeLockError::TimeOut) => continue,
+ Err(TapeLockError::Other(err)) => return Err(err),
+ }
}
}
set_tape_device_state(&setup.drive, &worker.upid().to_string())?;
diff --git a/src/tape/drive/mod.rs b/src/tape/drive/mod.rs
index f72e0b51..7bc02f9e 100644
--- a/src/tape/drive/mod.rs
+++ b/src/tape/drive/mod.rs
@@ -477,16 +477,34 @@ pub fn request_and_load_media(
}
}
+#[derive(thiserror::Error, Debug)]
+pub enum TapeLockError {
+ #[error("timeout while trying to lock")]
+ TimeOut,
+ #[error("{0}")]
+ Other(#[from] Error),
+}
+
+impl From<std::io::Error> for TapeLockError {
+ fn from(error: std::io::Error) -> Self {
+ Self::Other(error.into())
+ }
+}
+
/// Acquires an exclusive lock for the tape device
///
/// Basically calls lock_device_path() using the configured drive path.
pub fn lock_tape_device(
config: &SectionConfigData,
drive: &str,
-) -> Result<DeviceLockGuard, Error> {
+) -> Result<DeviceLockGuard, TapeLockError> {
let path = tape_device_path(config, drive)?;
- lock_device_path(&path)
- .map_err(|err| format_err!("unable to lock drive '{}' - {}", drive, err))
+ lock_device_path(&path).map_err(|err| match err {
+ TapeLockError::Other(err) => {
+ TapeLockError::Other(format_err!("unable to lock drive '{}' - {}", drive, err))
+ }
+ other => other,
+ })
}
/// Writes the given state for the specified drive
@@ -555,7 +573,7 @@ pub struct DeviceLockGuard(std::fs::File);
//
// 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, Error> {
+fn lock_device_path(device_path: &str) -> Result<DeviceLockGuard, TapeLockError> {
let lock_name = crate::tools::systemd::escape_unit(device_path, true);
@@ -564,7 +582,13 @@ fn lock_device_path(device_path: &str) -> Result<DeviceLockGuard, Error> {
let timeout = std::time::Duration::new(10, 0);
let mut file = std::fs::OpenOptions::new().create(true).append(true).open(path)?;
- proxmox::tools::fs::lock_file(&mut file, true, Some(timeout))?;
+ if let Err(err) = proxmox::tools::fs::lock_file(&mut file, true, Some(timeout)) {
+ if err.kind() == std::io::ErrorKind::Interrupted {
+ return Err(TapeLockError::TimeOut);
+ } else {
+ return Err(err.into());
+ }
+ }
let backup_user = crate::backup::backup_user()?;
fchown(file.as_raw_fd(), Some(backup_user.uid), Some(backup_user.gid))?;
--
2.20.1