From 8204d9b095ee8f89b2496c45cc48e8aab092ca8c Mon Sep 17 00:00:00 2001
From: Dietmar Maurer <dietmar@proxmox.com>
Date: Thu, 8 Apr 2021 11:26:08 +0200
Subject: [PATCH] tape: avoid unneccessary SCSI request in Drop

---
 src/tape/drive/lto/sg_tape.rs | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/tape/drive/lto/sg_tape.rs b/src/tape/drive/lto/sg_tape.rs
index 8e822924..b7cd677f 100644
--- a/src/tape/drive/lto/sg_tape.rs
+++ b/src/tape/drive/lto/sg_tape.rs
@@ -97,6 +97,7 @@ pub struct LtoTapeStatus {
 pub struct SgTape {
     file: File,
     info: InquiryInfo,
+    encryption_key_loaded: bool,
 }
 
 impl SgTape {
@@ -113,7 +114,11 @@ impl SgTape {
         if info.peripheral_type != 1 {
             bail!("not a tape device (peripheral_type = {})", info.peripheral_type);
         }
-        Ok(Self { file, info })
+        Ok(Self {
+            file,
+            info,
+            encryption_key_loaded: false,
+        })
     }
 
     /// Access to file descriptor - useful for testing
@@ -472,6 +477,9 @@ impl SgTape {
         &mut self,
         key: Option<[u8; 32]>,
     ) -> Result<(), Error> {
+
+        self.encryption_key_loaded = key.is_some();
+
         set_encryption(&mut self.file, key)
     }
 
@@ -664,7 +672,9 @@ impl SgTape {
 impl Drop for SgTape {
     fn drop(&mut self) {
         // For security reasons, clear the encryption key
-        let _ = self.set_encryption(None);
+        if self.encryption_key_loaded {
+            let _ = self.set_encryption(None);
+        }
     }
 }