Add code for tearing down the backstore devices

src/engine/strat_engine/backstore/backstore.rs

@@ -511,6 +511,11 @@ impl Backstore {
         self.data_tier.destroy()
     }
 
+    /// Run code required to stop a pool on backstore data structures.
+    pub fn stop(&mut self) -> StratisResult<()> {
+        self.data_tier.block_mgr.teardown()
+    }
+
     /// Teardown the DM devices in the backstore.
     #[cfg(test)]
     pub fn teardown(&mut self) -> StratisResult<()> {

src/engine/strat_engine/backstore/blockdev.rs

@@ -297,6 +297,16 @@ impl StratBlockDev {
         })?;
         crypt_handle.rebind_clevis()
     }
+
+    /// If a pool is encrypted, tear down the cryptsetup devicemapper devices on the
+    /// physical device.
+    pub fn teardown(&mut self) -> StratisResult<()> {
+        if let Some(ch) = self.underlying_device.crypt_handle() {
+            ch.deactivate()
+        } else {
+            Ok(())
+        }
+    }
 }
 
 impl<'a> Into<Value> for &'a StratBlockDev {

src/engine/strat_engine/backstore/blockdevmgr.rs

@@ -690,6 +690,22 @@ impl BlockDevMgr {
             Ok(())
         }
     }
+
+    /// Tear down devicemapper devices for the block devices in this BlockDevMgr.
+    pub fn teardown(&mut self) -> StratisResult<()> {
+        let mut errors = Vec::new();
+        for bd in self.block_devs.iter_mut() {
+            if let Err(e) = bd.teardown() {
+                errors.push(e);
+            }
+        }
+
+        if errors.is_empty() {
+            Ok(())
+        } else {
+            Err(StratisError::BestEffortError("Failed to remove devicemapper devices for some or all physical devices in the pool".to_string(), errors))
+        }
+    }
 }
 
 fn operation_loop<'a, I, A>(blockdevs: I, action: A) -> StratisResult<()>

src/engine/strat_engine/backstore/crypt/handle.rs

@@ -358,7 +358,6 @@ impl CryptHandle {
     }
 
     /// Deactivate the device referenced by the current device handle.
-    #[cfg(test)]
     pub fn deactivate(&self) -> StratisResult<()> {
         super::shared::ensure_inactive(&mut self.acquire_crypt_device()?, &self.name)
     }

src/engine/strat_engine/pool.rs

@@ -360,6 +360,7 @@ impl StratPool {
     /// set up again later.
     pub fn stop(mut self) -> StratisResult<DeviceSet> {
         self.thin_pool.teardown()?;
+        self.backstore.stop()?;
         Ok(self
             .backstore
             .blockdevs()