Re: [PATCH 2/2] kdump-emergency: fix "Transaction is destructive" emergency failure

[Baoquan He]

On 03/27/17 at 12:07pm, Xunlei Pang wrote:
> This will lead to systemd two contradictable jobs queued as an
> atomic transaction:
> job 1) the emergency service gets started by initrd-root-fs.target
> job 2) the emergency service gets stopped due to "systemctl isolate"
> thereby throwing "Transaction is destructive".
>
> In order to solve it, we can utilize "IgnoreOnIsolate=yes" for
> both kdump-emergency.service and kdump-emergency.target to avoid
> being isolated, then they can keep going on as expected in case
> of failures.

A small concern. Above paragraph, IgnoreOnIsolate is newly introduced
option, we could make it clearer for later reviewing if forget. How
about writing it like:

In order to solve it, we can utilize "IgnoreOnIsolate=yes" for both
kdump-emergency.service and kdump-emergency.target. Service or target
with attribute "IgnoreOnIsolate=yes" won't be stopped by other service
/target being isolated, then they can keep going as expected in case be
triggered by any failure.

Here, not sure if we can use systemd unit instead of service/target. I
feel systemd unit is not appropriate here.
> We add kdump-emergency.target dedicated to kdump the similar way
> as did for kdump-emergency.service(i.e. will replace systemd's
> emergency.target with kdump-emergency.target under kdump), and
> adds "IgnoreOnIsolate=yes" into both of them.
> Signed-off-by: Xunlei Pang
>
> dracut-kdump-emergency.service |  1 +
>  dracut-kdump-emergency.target  | 14 ++++++++++++++
>  dracut-module-setup.sh         |  3 ++-
>  kexec-tools.spec               |  2 ++
>  4 files changed, 19 insertions(+), 1 deletion(-)
>  create mode 100644 dracut-kdump-emergency.target
>
> diff --git a/dracut-kdump-emergency.service b/dracut-kdump-emergency.service
> index fb764f2..e023284 100644
> --- a/dracut-kdump-emergency.service
> +++ b/dracut-kdump-emergency.service
> @@ -12,6 +12,7 @@
>  [Unit]
>  Description=Kdump Emergency
>  DefaultDependencies=no
> +IgnoreOnIsolate=yes
>
> [Service]
>  ExecStart=/usr/bin/systemctl --no-block isolate kdump-error-handler.service
> diff --git a/dracut-kdump-emergency.target b/dracut-kdump-emergency.target
> new file mode 100644
> index 0000000..a1bb493
> --- /dev/null
> +++ b/dracut-kdump-emergency.target
> @@ -0,0 +1,14 @@
> +#  This file is part of systemd.
> +#
> +#  systemd is free software; you can redistribute it and/or modify it
> +#  under the terms of the GNU Lesser General Public License as published by
> +#  the Free Software Foundation; either version 2.1 of the License, or
> +#  (at your option) any later version.
>
> +[Unit]
> +Description=Emergency Mode
> +Documentation=man:systemd.special(7)
> +Requires=emergency.service
> +After=emergency.service
> +AllowIsolate=yes
> +IgnoreOnIsolate=yes
> diff --git a/dracut-module-setup.sh b/dracut-module-setup.sh
> index 1f96bb8..fa4fa2a 100755
> --- a/dracut-module-setup.sh
> +++ b/dracut-module-setup.sh
> @@ -734,8 +734,9 @@ install() {
>      ln_r "$systemdsystemunitdir/kdump-capture.service" "$systemdsystemunitdir/initrd.target.wants/kdump-capture.service"
>      inst "$moddir/kdump-error-handler.sh" "/usr/bin/kdump-error-handler.sh"
>      inst "$moddir/kdump-error-handler.service" "$systemdsystemunitdir/kdump-error-handler.service"
> # Replace existing emergency service
> # Replace existing emergency service and emergency target
> cp "$moddir/kdump-emergency.service" "$initdir/$systemdsystemunitdir/emergency.service"
> cp "$moddir/kdump-emergency.target" "$initdir/$systemdsystemunitdir/emergency.target"
> # Also redirect dracut-emergency to kdump error handler
> ln_r "$systemdsystemunitdir/emergency.service" "$systemdsystemunitdir/dracut-emergency.service"
>
> diff --git a/kexec-tools.spec b/kexec-tools.spec
> index 2a176f3..c3359fb 100644
> --- a/kexec-tools.spec
> +++ b/kexec-tools.spec
> @@ -41,6 +41,7 @@ Source103: dracut-kdump-error-handler.sh
>  Source104: dracut-kdump-emergency.service
>  Source105: dracut-kdump-error-handler.service
>  Source106: dracut-kdump-capture.service
> +Source107: dracut-kdump-emergency.target
>
> Requires(post): systemd-units
>  Requires(preun): systemd-units
> @@ -197,6 +198,7 @@ cp %{SOURCE103} $RPM_BUILD_ROOT/etc/kdump-adv-conf/kdump_dracut_modules/99kdumpb
>  cp %{SOURCE104} $RPM_BUILD_ROOT/etc/kdump-adv-conf/kdump_dracut_modules/99kdumpbase/%{remove_dracut_prefix %{SOURCE104}}
>  cp %{SOURCE105} $RPM_BUILD_ROOT/etc/kdump-adv-conf/kdump_dracut_modules/99kdumpbase/%{remove_dracut_prefix %{SOURCE105}}
>  cp %{SOURCE106} $RPM_BUILD_ROOT/etc/kdump-adv-conf/kdump_dracut_modules/99kdumpbase/%{remove_dracut_prefix %{SOURCE106}}
> +cp %{SOURCE107} $RPM_BUILD_ROOT/etc/kdump-adv-conf/kdump_dracut_modules/99kdumpbase/%{remove_dracut_prefix %{SOURCE107}}
>  chmod 755 $RPM_BUILD_ROOT/etc/kdump-adv-conf/kdump_dracut_modules/99kdumpbase/%{remove_dracut_prefix %{SOURCE100}}
>  chmod 755 $RPM_BUILD_ROOT/etc/kdump-adv-conf/kdump_dracut_modules/99kdumpbase/%{remove_dracut_prefix %{SOURCE101}}
>
> -- 
> 1.8.3.1
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