[PATCH proxmox-backup] fix #7964: tape: make barcode-label task abortable

[Jakob-Tobias Winter <tobias@stuttgart.de>]

The barcode-label-media worker never checked whether an abort was
requested, so pressing stop in the GUI had no effect and the task kept
loading and labeling every unlabeled tape in the changer.

Check for an abort request before each tape is loaded, and again before
the label is written, since loading the media can take a while. A load
or label write that is already running cannot be interrupted, so those
operations still run to completion.

Signed-off-by: Jakob-Tobias Winter <tobias@stuttgart.de>
---
Tested on PBS 4.2.8 (patch applied on top of 4.2.8-1) with a real tape
library: stopping the barcode-label task now aborts after the current
load, without labeling the loaded tape or loading the next one.

 src/api2/tape/drive.rs | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/api2/tape/drive.rs b/src/api2/tape/drive.rs
index 79b3b269c..3d8cca128 100644
--- a/src/api2/tape/drive.rs
+++ b/src/api2/tape/drive.rs
@@ -30,6 +30,7 @@ use pbs_tape::{
     sg_tape::tape_alert_flags_critical,
 };
 use proxmox_rest_server::WorkerTask;
+use proxmox_worker_task::WorkerTaskContext;
 
 use crate::{
     api2::tape::restore::{fast_catalog_restore, restore_media},
@@ -1040,13 +1041,14 @@ pub fn barcode_label_media(
         drive.clone(),
         "barcode-label-media",
         Some(drive.clone()),
-        move |_worker, config| barcode_label_media_worker(drive, &config, pool),
+        move |worker, config| barcode_label_media_worker(&worker, drive, &config, pool),
     )?;
 
     Ok(upid_str.into())
 }
 
 fn barcode_label_media_worker(
+    worker: &WorkerTask,
     drive: String,
     drive_config: &SectionConfigData,
     pool: Option<String>,
@@ -1076,6 +1078,10 @@ fn barcode_label_media_worker(
             continue;
         }
 
+        // loading and labeling a tape cannot be interrupted, so check
+        // before starting with the next one
+        worker.check_abort()?;
+
         inventory.reload()?;
         match inventory.find_media_by_label_text(&label_text) {
             Ok(Some(_)) => {
@@ -1112,6 +1118,9 @@ fn barcode_label_media_worker(
             }
         }
 
+        // loading the media can take a while, so check again before writing the label
+        worker.check_abort()?;
+
         let ctime = proxmox_time::epoch_i64();
         let label = MediaLabel {
             label_text: label_text.to_string(),
-- 
2.53.0