Skip to content

nixos/filesystems: mount-pstore.service improvements #124431

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
lukegb merged 2 commits into from Jul 25, 2021
Merged

nixos/filesystems: mount-pstore.service improvements #124431

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
92cbe52
nixos/filesystems: condition mount-pstore.service on pstore module
May 25, 2021
af871f6
nixos/filesystems: await builtin pstore module backend in mount-pstore
May 30, 2021
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
25 changes: 15 additions & 10 deletions nixos/modules/tasks/filesystems.nix
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -305,28 +305,33 @@ in
in listToAttrs (map formatDevice (filter (fs: fs.autoFormat) fileSystems)) // {
# Mount /sys/fs/pstore for evacuating panic logs and crashdumps from persistent storage onto the disk using systemd-pstore.
# This cannot be done with the other special filesystems because the pstore module (which creates the mount point) is not loaded then.
# Since the pstore filesystem is usually empty right after mounting because the backend isn't registered yet, and a path unit cannot detect files inside of it, the same service waits for that to happen. systemd's restart mechanism can't be used here because the first failure also fails all dependent units.
"mount-pstore" = {
serviceConfig = {
Type = "oneshot";
ExecStart = "${pkgs.util-linux}/bin/mount -t pstore -o nosuid,noexec,nodev pstore /sys/fs/pstore";
ExecStartPost = pkgs.writeShellScript "wait-for-pstore.sh" ''
# skip on kernels without the pstore module
ExecCondition = "${pkgs.kmod}/bin/modprobe -b pstore";
ExecStart = pkgs.writeShellScript "mount-pstore.sh" ''
set -eu
TRIES=0
while [ $TRIES -lt 20 ] && [ "$(cat /sys/module/pstore/parameters/backend)" = "(null)" ]; do
sleep 0.1
TRIES=$((TRIES+1))
# if the pstore module is builtin it will have mounted the persistent store automatically. it may also be already mounted for other reasons.
${pkgs.util-linux}/bin/mountpoint -q /sys/fs/pstore || ${pkgs.util-linux}/bin/mount -t pstore -o nosuid,noexec,nodev pstore /sys/fs/pstore
# wait up to five seconds (arbitrary, happened within one in testing) for the backend to be registered and the files to appear. a systemd path unit cannot detect this happening; and succeeding after a restart would not start dependent units.
TRIES=50
while [ "$(cat /sys/module/pstore/parameters/backend)" = "(null)" ]; do
if (( $TRIES )); then
sleep 0.1
TRIES=$((TRIES-1))
else
echo "Persistent Storage backend was not registered in time." >&2
exit 1
fi
done
'';
RemainAfterExit = true;
};
unitConfig = {
ConditionPathIsMountPoint = "!/sys/fs/pstore";
ConditionVirtualization = "!container";
DefaultDependencies = false; # needed to prevent a cycle
};
after = [ "modprobe@pstore.service" ];
requires = [ "modprobe@pstore.service" ];
before = [ "systemd-pstore.service" ];
wantedBy = [ "systemd-pstore.service" ];
};
Expand Down