diff options
| -rw-r--r-- | nixos/doc/manual/development/what-happens-during-a-system-switch.chapter.md | 5 | ||||
| -rwxr-xr-x | nixos/modules/system/activation/switch-to-configuration.pl | 18 | ||||
| -rw-r--r-- | nixos/tests/switch-test.nix | 69 |
3 files changed, 86 insertions, 6 deletions
diff --git a/nixos/doc/manual/development/what-happens-during-a-system-switch.chapter.md b/nixos/doc/manual/development/what-happens-during-a-system-switch.chapter.md index 9cbec729803..5d6d67f1aa9 100644 --- a/nixos/doc/manual/development/what-happens-during-a-system-switch.chapter.md +++ b/nixos/doc/manual/development/what-happens-during-a-system-switch.chapter.md @@ -21,8 +21,9 @@ If the action is `switch` or `test`, the currently running system is inspected and the actions to switch to the new system are calculated. This process takes two data sources into account: `/etc/fstab` and the current systemd status. Mounts and swaps are read from `/etc/fstab` and the corresponding actions are -generated. If a new mount is added, for example, the proper `.mount` unit is -marked to be started. The current systemd state is inspected, the difference +generated. If the options of a mount are modified, for example, the proper `.mount` +unit is reloaded (or restarted if anything else changed and it's neither the root +mount or the nix store). The current systemd state is inspected, the difference between the current system and the desired configuration is calculated and actions are generated to get to this state. There are a lot of nuances that can be controlled by the units which are explained here. diff --git a/nixos/modules/system/activation/switch-to-configuration.pl b/nixos/modules/system/activation/switch-to-configuration.pl index 95308d5da94..e05f89bb0fb 100755 --- a/nixos/modules/system/activation/switch-to-configuration.pl +++ b/nixos/modules/system/activation/switch-to-configuration.pl @@ -661,10 +661,20 @@ foreach my $mount_point (keys(%{$cur_fss})) { # Filesystem entry disappeared, so unmount it. $units_to_stop{$unit} = 1; } elsif ($cur->{fsType} ne $new->{fsType} || $cur->{device} ne $new->{device}) { - # Filesystem type or device changed, so unmount and mount it. - $units_to_stop{$unit} = 1; - $units_to_start{$unit} = 1; - record_unit($start_list_file, $unit); + if ($mount_point eq '/' or $mount_point eq '/nix') { + if ($cur->{options} ne $new->{options}) { + # Mount options changed, so remount it. + $units_to_reload{$unit} = 1; + record_unit($reload_list_file, $unit); + } else { + # Don't unmount / or /nix if the device changed + $units_to_skip{$unit} = 1; + } + } else { + # Filesystem type or device changed, so unmount and mount it. + $units_to_restart{$unit} = 1; + record_unit($restart_list_file, $unit); + } } elsif ($cur->{options} ne $new->{options}) { # Mount options changes, so remount it. $units_to_reload{$unit} = 1; diff --git a/nixos/tests/switch-test.nix b/nixos/tests/switch-test.nix index c0bf8f2518d..5e9b38d2913 100644 --- a/nixos/tests/switch-test.nix +++ b/nixos/tests/switch-test.nix @@ -66,6 +66,25 @@ in { # Hello world! ''; + addedMount.configuration.virtualisation.fileSystems."/test" = { + device = "tmpfs"; + fsType = "tmpfs"; + }; + + addedMountOptsModified.configuration = { + imports = [ addedMount.configuration ]; + virtualisation.fileSystems."/test".options = [ "x-test" ]; + }; + + addedMountDevModified.configuration = { + imports = [ addedMountOptsModified.configuration ]; + virtualisation.fileSystems."/test".device = lib.mkForce "ramfs"; + }; + + storeMountModified.configuration = { + virtualisation.fileSystems."/".device = lib.mkForce "auto"; + }; + simpleService.configuration = { systemd.services.test = { wantedBy = [ "multi-user.target" ]; @@ -672,6 +691,56 @@ in { out = switch_to_specialisation("${machine}", "modifiedSystemConf") assert_contains(out, "starting the following units: dbus.service\n") + with subtest("fstab mounts"): + switch_to_specialisation("${machine}", "") + # add a mountpoint + out = switch_to_specialisation("${machine}", "addedMount") + assert_lacks(out, "stopping the following units:") + assert_lacks(out, "NOT restarting the following changed units:") + assert_lacks(out, "\nrestarting the following units:") + assert_lacks(out, "\nstarting the following units:") + assert_contains(out, "the following new units were started: test.mount\n") + # modify the mountpoint's options + out = switch_to_specialisation("${machine}", "addedMountOptsModified") + assert_lacks(out, "stopping the following units:") + assert_lacks(out, "NOT restarting the following changed units:") + assert_contains(out, "reloading the following units: test.mount\n") + assert_lacks(out, "\nrestarting the following units:") + assert_lacks(out, "\nstarting the following units:") + assert_lacks(out, "the following new units were started:") + # modify the device + out = switch_to_specialisation("${machine}", "addedMountDevModified") + assert_lacks(out, "stopping the following units:") + assert_lacks(out, "NOT restarting the following changed units:") + assert_lacks(out, "reloading the following units:") + assert_contains(out, "\nrestarting the following units: test.mount\n") + assert_lacks(out, "\nstarting the following units:") + assert_lacks(out, "the following new units were started:") + # modify both + out = switch_to_specialisation("${machine}", "addedMount") + assert_lacks(out, "stopping the following units:") + assert_lacks(out, "NOT restarting the following changed units:") + assert_lacks(out, "reloading the following units:") + assert_contains(out, "\nrestarting the following units: test.mount\n") + assert_lacks(out, "\nstarting the following units:") + assert_lacks(out, "the following new units were started:") + # remove the mount + out = switch_to_specialisation("${machine}", "") + assert_contains(out, "stopping the following units: test.mount\n") + assert_lacks(out, "NOT restarting the following changed units:") + assert_contains(out, "reloading the following units: dbus.service\n") + assert_lacks(out, "\nrestarting the following units:") + assert_lacks(out, "\nstarting the following units:") + assert_lacks(out, "the following new units were started:") + # change something about the / mount + out = switch_to_specialisation("${machine}", "storeMountModified") + assert_lacks(out, "stopping the following units:") + assert_contains(out, "NOT restarting the following changed units: -.mount") + assert_contains(out, "reloading the following units: dbus.service\n") + assert_lacks(out, "\nrestarting the following units:") + assert_lacks(out, "\nstarting the following units:") + assert_lacks(out, "the following new units were started:") + with subtest("services"): switch_to_specialisation("${machine}", "") # Nothing happens when nothing is changed |