Merge pull request #2184 from phillxnet/2099_failure_to_remove_detach…

…ed_disks_via_pool_resize

failure to remove detached disks via pool resize. Fixes #2099

src/rockstor/fs/btrfs.py

@@ -1751,7 +1751,30 @@ def start_resize_pool(cmd):
     :param cmd: btrfs dev add/delete command in run_command() format (ie list).
     """
     logger.debug("Resize pool command ({}).".format(cmd))
-    run_command(cmd)
+    # N.B. in some instances, such as live disk removal, an attempt to remove missing:
+    # btrfs device delete missing /mnt2/pool-label
+    # results in rc=1, out=[""], and err=
+    # ["ERROR: error removing device 'missing': no missing devices found to remove", '']
+    # return advice, in this case, to improve usability. Customised exception message is
+    # presented in Pool details page - Balances tab, Errors or Notes column.
+    try:
+        run_command(cmd, log=True)
+    except CommandException as e:
+        emsg = (
+            "ERROR: error removing device 'missing': no missing devices found to remove"
+        )
+        if e.err[0] == emsg:
+            msg = (
+                "Missing Device removal failed, ensure degraded,rw mount options are used "
+                "(a reboot may be required)."
+            )
+            logger.error(msg)
+            raise Exception(
+                "{} Command was ({}). Command Exception was ({}).".format(
+                    msg, " ".join(cmd), emsg
+                )
+            )
+        raise e
 
 
 @task()

src/rockstor/storageadmin/views/command.py

@@ -90,6 +90,16 @@ def _refresh_pool_state():
                     "are no attached devices. Moving on.".format(p.name)
                 )
                 continue
+            # If pool has no missing remove all detached disk pool associations.
+            # Accounts for 'end of run' clean-up in removing a detached disk and for cli
+            # maintenance re pool returned to no missing dev status. Also re-establishes
+            # pool info as source of truth re missing.
+            if not p.has_missing_dev:
+                for disk in p.disk_set.filter(name__startswith="detached-"):
+                    logger.info("Removing detached disk from Pool {}: no missing "
+                                "devices found.".format(p.name))
+                    disk.pool = None
+                    disk.save()
             try:
                 # Get and save what info we can prior to mount.
                 first_dev = p.disk_set.attached().first()