nixpkgs/nixos/modules/tasks/filesystems.nix

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{ config, lib, pkgs, utils, ... }@moduleArgs:
with lib;
with utils;
let
# https://wiki.archlinux.org/index.php/fstab#Filepath_spaces
escape = string: builtins.replaceStrings [ " " "\t" ] [ "\\040" "\\011" ] string;
addCheckDesc = desc: elemType: check: types.addCheck elemType check
// { description = "${elemType.description} (with check: ${desc})"; };
isNonEmpty = s: (builtins.match "[ \t\n]*" s) == null;
nonEmptyStr = addCheckDesc "non-empty" types.str isNonEmpty;
fileSystems' = toposort fsBefore (attrValues config.fileSystems);
fileSystems = if fileSystems' ? result
then # use topologically sorted fileSystems everywhere
fileSystems'.result
else # the assertion below will catch this,
# but we fall back to the original order
# anyway so that other modules could check
# their assertions too
(attrValues config.fileSystems);
specialFSTypes = [ "proc" "sysfs" "tmpfs" "ramfs" "devtmpfs" "devpts" ];
nonEmptyWithoutTrailingSlash = addCheckDesc "non-empty without trailing slash" types.str
(s: isNonEmpty s && (builtins.match ".+/" s) == null);
coreFileSystemOpts = { name, config, ... }: {
options = {
mountPoint = mkOption {
example = "/mnt/usb";
type = nonEmptyWithoutTrailingSlash;
description = "Location of the mounted file system.";
};
stratis.poolUuid = lib.mkOption {
type = types.uniq (types.nullOr types.str);
description = ''
UUID of the stratis pool that the fs is located in
'';
example = "04c68063-90a5-4235-b9dd-6180098a20d9";
default = null;
};
device = mkOption {
default = null;
example = "/dev/sda";
type = types.nullOr nonEmptyStr;
description = "Location of the device.";
};
fsType = mkOption {
default = "auto";
example = "ext3";
type = nonEmptyStr;
description = "Type of the file system.";
};
options = mkOption {
default = [ "defaults" ];
example = [ "data=journal" ];
description = "Options used to mount the file system.";
type = types.nonEmptyListOf nonEmptyStr;
};
depends = mkOption {
default = [ ];
example = [ "/persist" ];
type = types.listOf nonEmptyWithoutTrailingSlash;
description = ''
List of paths that should be mounted before this one. This filesystem's
{option}`device` and {option}`mountPoint` are always
checked and do not need to be included explicitly. If a path is added
to this list, any other filesystem whose mount point is a parent of
the path will be mounted before this filesystem. The paths do not need
to actually be the {option}`mountPoint` of some other filesystem.
'';
};
};
config = {
mountPoint = mkDefault name;
device = mkIf (elem config.fsType specialFSTypes) (mkDefault config.fsType);
};
};
fileSystemOpts = { config, ... }: {
options = {
label = mkOption {
default = null;
example = "root-partition";
type = types.nullOr nonEmptyStr;
description = "Label of the device (if any).";
};
autoFormat = mkOption {
default = false;
type = types.bool;
description = ''
If the device does not currently contain a filesystem (as
determined by {command}`blkid`), then automatically
format it with the filesystem type specified in
{option}`fsType`. Use with caution.
'';
};
formatOptions = mkOption {
visible = false;
type = types.unspecified;
default = null;
};
autoResize = mkOption {
default = false;
type = types.bool;
description = ''
If set, the filesystem is grown to its maximum size before
being mounted. (This is typically the size of the containing
partition.) This is currently only supported for ext2/3/4
filesystems that are mounted during early boot.
'';
};
noCheck = mkOption {
default = false;
type = types.bool;
description = "Disable running fsck on this filesystem.";
};
};
config.device = lib.mkIf (config.label != null) (lib.mkDefault "/dev/disk/by-label/${escape config.label}");
config.options = let
inInitrd = utils.fsNeededForBoot config;
in mkMerge [
(mkIf config.autoResize [ "x-systemd.growfs" ])
(mkIf config.autoFormat [ "x-systemd.makefs" ])
(mkIf (utils.fsNeededForBoot config) [ "x-initrd.mount" ])
(mkIf
# With scripted stage 1, depends is implemented by sorting 'config.system.build.fileSystems'
(lib.length config.depends > 0 && (inInitrd -> moduleArgs.config.boot.initrd.systemd.enable))
(
map (
x: "x-systemd.requires-mounts-for=${optionalString inInitrd "/sysroot"}${x}"
) config.depends
)
)
];
};
# Makes sequence of `specialMount device mountPoint options fsType` commands.
# `systemMount` should be defined in the sourcing script.
makeSpecialMounts = mounts:
pkgs.writeText "mounts.sh" (concatMapStringsSep "\n" (mount: ''
specialMount "${mount.device}" "${mount.mountPoint}" "${concatStringsSep "," mount.options}" "${mount.fsType}"
'') mounts);
makeFstabEntries =
let
fsToSkipCheck = [
"none"
"auto"
"overlay"
"iso9660"
"bindfs"
"udf"
"btrfs"
"zfs"
"tmpfs"
"bcachefs"
"nfs"
"nfs4"
"nilfs2"
"vboxsf"
"squashfs"
"glusterfs"
"apfs"
"9p"
"cifs"
"prl_fs"
"vmhgfs"
] ++ lib.optionals (!config.boot.initrd.checkJournalingFS) [
"ext3"
"ext4"
"reiserfs"
"xfs"
"jfs"
"f2fs"
];
isBindMount = fs: builtins.elem "bind" fs.options;
skipCheck = fs: fs.noCheck || fs.device == "none" || builtins.elem fs.fsType fsToSkipCheck || isBindMount fs;
in fstabFileSystems: { }: concatMapStrings (fs:
(if fs.device != null then escape fs.device
else throw "No device specified for mount point ${fs.mountPoint}.")
+ " " + escape fs.mountPoint
+ " " + fs.fsType
+ " " + escape (builtins.concatStringsSep "," fs.options)
+ " 0 " + (if skipCheck fs then "0" else if fs.mountPoint == "/" then "1" else "2")
+ "\n"
) fstabFileSystems;
initrdFstab = pkgs.writeText "initrd-fstab" (makeFstabEntries (filter utils.fsNeededForBoot fileSystems) { });
in
{
###### interface
options = {
fileSystems = mkOption {
default = {};
example = literalExpression ''
{
"/".device = "/dev/hda1";
"/data" = {
device = "/dev/hda2";
fsType = "ext3";
options = [ "data=journal" ];
};
"/bigdisk".label = "bigdisk";
}
'';
type = types.attrsOf (types.submodule [coreFileSystemOpts fileSystemOpts]);
description = ''
The file systems to be mounted. It must include an entry for
the root directory (`mountPoint = "/"`). Each
entry in the list is an attribute set with the following fields:
`mountPoint`, `device`,
`fsType` (a file system type recognised by
{command}`mount`; defaults to
`"auto"`), and `options`
(the mount options passed to {command}`mount` using the
{option}`-o` flag; defaults to `[ "defaults" ]`).
Instead of specifying `device`, you can also
specify a volume label (`label`) for file
systems that support it, such as ext2/ext3 (see {command}`mke2fs -L`).
'';
};
system.fsPackages = mkOption {
internal = true;
default = [ ];
description = "Packages supplying file system mounters and checkers.";
};
boot.supportedFilesystems = mkOption {
default = { };
example = lib.literalExpression ''
{
btrfs = true;
zfs = lib.mkForce false;
}
'';
type = types.coercedTo
(types.listOf types.str)
(enabled: lib.listToAttrs (map (fs: lib.nameValuePair fs true) enabled))
(types.attrsOf types.bool);
description = ''
Names of supported filesystem types, or an attribute set of file system types
and their state. The set form may be used together with `lib.mkForce` to
explicitly disable support for specific filesystems, e.g. to disable ZFS
with an unsupported kernel.
'';
};
boot.specialFileSystems = mkOption {
default = {};
type = types.attrsOf (types.submodule coreFileSystemOpts);
internal = true;
description = ''
Special filesystems that are mounted very early during boot.
'';
};
boot.devSize = mkOption {
default = "5%";
example = "32m";
type = types.str;
description = ''
Size limit for the /dev tmpfs. Look at mount(8), tmpfs size option,
for the accepted syntax.
'';
};
boot.devShmSize = mkOption {
default = "50%";
example = "256m";
type = types.str;
description = ''
Size limit for the /dev/shm tmpfs. Look at mount(8), tmpfs size option,
for the accepted syntax.
'';
};
boot.runSize = mkOption {
default = "25%";
example = "256m";
type = types.str;
description = ''
Size limit for the /run tmpfs. Look at mount(8), tmpfs size option,
for the accepted syntax.
'';
};
};
###### implementation
config = {
assertions = let
ls = sep: concatMapStringsSep sep (x: x.mountPoint);
resizableFSes = [
"ext3"
"ext4"
"btrfs"
"xfs"
];
notAutoResizable = fs: fs.autoResize && !(builtins.elem fs.fsType resizableFSes);
in [
{ assertion = ! (fileSystems' ? cycle);
message = "The fileSystems option can't be topologically sorted: mountpoint dependency path ${ls " -> " fileSystems'.cycle} loops to ${ls ", " fileSystems'.loops}";
}
{ assertion = ! (any notAutoResizable fileSystems);
message = let
fs = head (filter notAutoResizable fileSystems);
in ''
Mountpoint '${fs.mountPoint}': 'autoResize = true' is not supported for 'fsType = "${fs.fsType}"'
${optionalString (fs.fsType == "auto") "fsType has to be explicitly set and"}
only the following support it: ${lib.concatStringsSep ", " resizableFSes}.
'';
}
{
assertion = ! (any (fs: fs.formatOptions != null) fileSystems);
message = let
fs = head (filter (fs: fs.formatOptions != null) fileSystems);
in ''
'fileSystems.<name>.formatOptions' has been removed, since
systemd-makefs does not support any way to provide formatting
options.
'';
}
] ++ lib.map (fs: {
assertion = fs.label != null -> fs.device == "/dev/disk/by-label/${escape fs.label}";
message = ''
The filesystem with mount point ${fs.mountPoint} has its label and device set to inconsistent values:
label: ${toString fs.label}
device: ${toString fs.device}
'filesystems.<name>.label' and 'filesystems.<name>.device' are mutually exclusive. Please set only one.
'';
}) fileSystems;
# Export for use in other modules
system.build.fileSystems = fileSystems;
system.build.earlyMountScript = makeSpecialMounts (toposort fsBefore (attrValues config.boot.specialFileSystems)).result;
boot.supportedFilesystems = map (fs: fs.fsType) fileSystems;
# Add the mount helpers to the system path so that `mount' can find them.
system.fsPackages = [ pkgs.dosfstools ];
environment.systemPackages = with pkgs; [ fuse3 fuse ] ++ config.system.fsPackages;
environment.etc.fstab.text =
let
swapOptions = sw: concatStringsSep "," (
sw.options
++ optional (sw.priority != null) "pri=${toString sw.priority}"
++ optional (sw.discardPolicy != null) "discard${optionalString (sw.discardPolicy != "both") "=${toString sw.discardPolicy}"}"
);
in ''
# This is a generated file. Do not edit!
#
# To make changes, edit the fileSystems and swapDevices NixOS options
# in your /etc/nixos/configuration.nix file.
#
# <file system> <mount point> <type> <options> <dump> <pass>
# Filesystems.
${makeFstabEntries fileSystems {}}
# Swap devices.
${flip concatMapStrings config.swapDevices (sw:
"${sw.realDevice} none swap ${swapOptions sw}\n"
)}
'';
boot.initrd.systemd.storePaths = [initrdFstab];
boot.initrd.systemd.managerEnvironment.SYSTEMD_SYSROOT_FSTAB = initrdFstab;
boot.initrd.systemd.services.initrd-parse-etc.environment.SYSTEMD_SYSROOT_FSTAB = initrdFstab;
# Provide a target that pulls in all filesystems.
systemd.targets.fs =
{ description = "All File Systems";
wants = [ "local-fs.target" "remote-fs.target" ];
};
systemd.services = {
# Mount /sys/fs/pstore for evacuating panic logs and crashdumps from persistent storage onto the disk using systemd-pstore.
# This cannot be done with the other special filesystems because the pstore module (which creates the mount point) is not loaded then.
"mount-pstore" = {
serviceConfig = {
Type = "oneshot";
# skip on kernels without the pstore module
ExecCondition = "${pkgs.kmod}/bin/modprobe -b pstore";
ExecStart = pkgs.writeShellScript "mount-pstore.sh" ''
set -eu
# 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 || ${pkgs.util-linux}/bin/mount -t pstore -o nosuid,noexec,nodev pstore /sys/fs/pstore
# wait up to 1.5 seconds for the backend to be registered and the files to appear. a systemd path unit cannot detect this happening; and succeeding after a restart would not start dependent units.
TRIES=15
while [ "$(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
break
fi
done
'';
RemainAfterExit = true;
};
unitConfig = {
ConditionVirtualization = "!container";
DefaultDependencies = false; # needed to prevent a cycle
};
before = [ "systemd-pstore.service" "shutdown.target" ];
conflicts = [ "shutdown.target" ];
wantedBy = [ "systemd-pstore.service" ];
};
};
systemd.tmpfiles.rules = [
"d /run/keys 0750 root ${toString config.ids.gids.keys}"
"z /run/keys 0750 root ${toString config.ids.gids.keys}"
];
# Sync mount options with systemd's src/core/mount-setup.c: mount_table.
boot.specialFileSystems = {
"/proc" = { fsType = "proc"; options = [ "nosuid" "noexec" "nodev" ]; };
"/run" = { fsType = "tmpfs"; options = [ "nosuid" "nodev" "strictatime" "mode=755" "size=${config.boot.runSize}" ]; };
"/dev" = { fsType = "devtmpfs"; options = [ "nosuid" "strictatime" "mode=755" "size=${config.boot.devSize}" ]; };
"/dev/shm" = { fsType = "tmpfs"; options = [ "nosuid" "nodev" "strictatime" "mode=1777" "size=${config.boot.devShmSize}" ]; };
"/dev/pts" = { fsType = "devpts"; options = [ "nosuid" "noexec" "mode=620" "ptmxmode=0666" "gid=${toString config.ids.gids.tty}" ]; };
# To hold secrets that shouldn't be written to disk
"/run/keys" = { fsType = "ramfs"; options = [ "nosuid" "nodev" "mode=750" ]; };
} // optionalAttrs (!config.boot.isContainer) {
# systemd-nspawn populates /sys by itself, and remounting it causes all
# kinds of weird issues (most noticeably, waiting for host disk device
# nodes).
"/sys" = { fsType = "sysfs"; options = [ "nosuid" "noexec" "nodev" ]; };
};
};
}