From 31ce14e4c2ca3e60ea5b185aa85508bb60d3a1f3 Mon Sep 17 00:00:00 2001
From: Axel Burri <axel@tty0.ch>
Date: Tue, 22 Feb 2022 20:28:01 +0100
Subject: [PATCH] btrbk: handle errors from btrfs filesystem usage

Fix `btrbk usage` unhandled error case if usage data cannot be
retrieved, e.g.:

   ERROR: Failed to fetch btrfs filesystem usage for: example.com:/mnt/btr_pool
   ERROR: ... sh: ssh -i 'XXX' btrbk@example.com 'btrfs-filesystem-usage '\''/mnt/btr_pool'\'''
   ERROR: ... cannot access '/mnt/btr_pool': Permission denied
---
 btrbk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/btrbk b/btrbk
index c428909..cbea113 100755
--- a/btrbk
+++ b/btrbk
@@ -6439,7 +6439,7 @@ MAIN:
       return unless($mountpoint);
       my $mount_source = $mountpoint->{mount_source};
       my $mid = $vol->{MACHINE_ID} . $mount_source;
-      $usage_cache{$mid} //= btrfs_filesystem_usage($vol);
+      $usage_cache{$mid} //= btrfs_filesystem_usage($vol) // {};
       push @data, { %{$usage_cache{$mid}},
                     type => $type,
                     mount_source => $mount_source,