tape: avoid executor blocking in drive API

By using tokio::task::spawn_blocking().

src/api2/tape/drive.rs

@@ -70,7 +70,7 @@ use crate::{
     },
 )]
 /// Load media via changer from slot
-pub fn load_slot(
+pub async fn load_slot(
     drive: String,
     slot: u64,
     _param: Value,
@@ -85,9 +85,10 @@ pub fn load_slot(
         None => bail!("drive '{}' has no associated changer", drive),
     };
 
+    tokio::task::spawn_blocking(move || {
         let drivenum = drive_config.changer_drive_id.unwrap_or(0);
-
         mtx_load(&changer.path, slot, drivenum)
+    }).await?
 }
 
 #[api(
@@ -105,15 +106,14 @@ pub fn load_slot(
 /// Load media with specified label
 ///
 /// Issue a media load request to the associated changer device.
-pub fn load_media(drive: String, changer_id: String) -> Result<(), Error> {
+pub async fn load_media(drive: String, changer_id: String) -> Result<(), Error> {
 
     let (config, _digest) = config::drive::config()?;
 
+    tokio::task::spawn_blocking(move || {
         let (mut changer, _) = media_changer(&config, &drive, false)?;
-
+        changer.load_media(&changer_id)
-    changer.load_media(&changer_id)?;
+    }).await?
-
-    Ok(())
 }
 
 #[api(
@@ -131,7 +131,7 @@ pub fn load_media(drive: String, changer_id: String) -> Result<(), Error> {
     },
 )]
 /// Unload media via changer
-pub fn unload(
+pub async fn unload(
     drive: String,
     slot: Option<u64>,
     _param: Value,
@@ -146,13 +146,15 @@ pub fn unload(
         None => bail!("drive '{}' has no associated changer", drive),
     };
 
-    let drivenum: u64 = 0;
+    let drivenum = drive_config.changer_drive_id.unwrap_or(0);
 
+    tokio::task::spawn_blocking(move || {
         if let Some(slot) = slot {
             mtx_unload(&changer.path, slot, drivenum)
         } else {
             drive_config.unload_media()
         }
+    }).await?
 }
 
 #[api(
@@ -270,10 +272,11 @@ pub fn rewind(
     },
 )]
 /// Eject/Unload drive media
-pub fn eject_media(drive: String) -> Result<(), Error> {
+pub async fn eject_media(drive: String) -> Result<(), Error> {
 
     let (config, _digest) = config::drive::config()?;
 
+    tokio::task::spawn_blocking(move || {
         let (mut changer, _) = media_changer(&config, &drive, false)?;
 
         if !changer.eject_on_unload() {
@@ -281,9 +284,8 @@ pub fn eject_media(drive: String) -> Result<(), Error> {
             drive.eject_media()?;
         }
 
-    changer.unload_media()?;
+        changer.unload_media()
-
+    }).await?
-    Ok(())
 }
 
 #[api(
@@ -439,10 +441,11 @@ fn write_media_label(
     },
 )]
 /// Read media label
-pub fn read_label(drive: String) -> Result<MediaLabelInfoFlat, Error> {
+pub async fn read_label(drive: String) -> Result<MediaLabelInfoFlat, Error> {
 
     let (config, _digest) = config::drive::config()?;
 
+    tokio::task::spawn_blocking(move || {
         let mut drive = open_drive(&config, &drive)?;
 
         let info = drive.read_label()?;
@@ -472,6 +475,7 @@ pub fn read_label(drive: String) -> Result<MediaLabelInfoFlat, Error> {
         };
 
         Ok(info)
+    }).await?
 }
 
 #[api(
@@ -497,12 +501,13 @@ pub fn read_label(drive: String) -> Result<MediaLabelInfoFlat, Error> {
 /// This method queries the changer to get a list of media labels.
 ///
 /// Note: This updates the media online status.
-pub fn inventory(
+pub async fn inventory(
     drive: String,
 ) -> Result<Vec<LabelUuidMap>, Error> {
 
     let (config, _digest) = config::drive::config()?;
 
+    tokio::task::spawn_blocking(move || {
         let (changer, changer_name) = media_changer(&config, &drive, false)?;
 
         let changer_id_list = changer.list_media_changer_ids()?;
@@ -512,7 +517,13 @@ pub fn inventory(
         let mut inventory = Inventory::load(state_path)?;
         let mut state_db = MediaStateDatabase::load(state_path)?;
 
-    update_changer_online_status(&config, &mut inventory, &mut state_db, &changer_name, &changer_id_list)?;
+        update_changer_online_status(
+            &config,
+            &mut inventory,
+            &mut state_db,
+            &changer_name,
+            &changer_id_list,
+        )?;
 
         let mut list = Vec::new();
 
@@ -532,6 +543,7 @@ pub fn inventory(
         }
 
         Ok(list)
+    }).await?
 }
 
 #[api(