nixpkgs/modules/tasks/filesystems.nix

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{pkgs, config, ...}:
let
###### interface
inherit (pkgs.lib) mkOption types;
options = {
fileSystems = mkOption {
example = [
{ mountPoint = "/";
device = "/dev/hda1";
}
{ mountPoint = "/data";
device = "/dev/hda2";
fsType = "ext3";
options = "data=journal";
}
{ mountPoint = "/bigdisk";
label = "bigdisk";
}
];
description = "
The file systems to be mounted. It must include an entry for
the root directory (<literal>mountPoint = \"/\"</literal>). Each
entry in the list is an attribute set with the following fields:
<literal>mountPoint</literal>, <literal>device</literal>,
<literal>fsType</literal> (a file system type recognised by
<command>mount</command>; defaults to
<literal>\"auto\"</literal>), and <literal>options</literal>
(the mount options passed to <command>mount</command> using the
<option>-o</option> flag; defaults to <literal>\"defaults\"</literal>).
Instead of specifying <literal>device</literal>, you can also
specify a volume label (<literal>label</literal>) for file
systems that support it, such as ext2/ext3 (see <command>mke2fs
-L</command>).
<literal>autocreate</literal> forces <literal>mountPoint</literal> to be created with
<command>mkdir -p</command> .
";
type = types.nullOr (types.list types.optionSet);
options = {
mountPoint = mkOption {
example = "/mnt/usb";
type = types.uniq types.string;
description = "
Location of the mounted the file system.
";
};
device = mkOption {
default = null;
example = "/dev/sda";
type = types.uniq (types.nullOr types.string);
description = "
Location of the device.
";
};
label = mkOption {
default = null;
example = "root-partition";
type = types.uniq (types.nullOr types.string);
description = "
Label of the device (if any).
";
};
fsType = mkOption {
default = "auto";
example = "ext3";
type = types.uniq types.string;
description = "
Type of the file system.
";
};
options = mkOption {
default = "defaults,relatime";
example = "data=journal";
type = types.string;
merge = pkgs.lib.concatStringsSep ",";
description = "
Option used to mount the file system.
";
};
autocreate = mkOption {
default = false;
type = types.bool;
description = "
Automatically create the mount point defined in
<option>fileSystems.*.mountPoint</option>.
";
};
};
};
system.sbin.mount = mkOption {
internal = true;
default = pkgs.utillinuxng.override {
buildMountOnly = true;
mountHelpers = pkgs.buildEnv {
name = "mount-helpers";
paths = [
pkgs.ntfs3g
pkgs.mount_cifs
pkgs.nfsUtils
];
pathsToLink = "/sbin";
} + "/sbin";
};
description = "
A patched `mount' command that looks in a directory in the Nix
store instead of in /sbin for mount helpers (like mount.ntfs-3g or
mount.cifs).
";
};
};
###### implementation
inherit (pkgs) e2fsprogs;
fileSystems = config.fileSystems;
mountPoints = map (fs: fs.mountPoint) fileSystems;
devices = map (fs: if fs.device != null then fs.device else "LABEL=" + fs.label) fileSystems;
fsTypes = map (fs: fs.fsType) fileSystems;
optionss = map (fs: fs.options) fileSystems;
autocreates = map (fs: fs.autocreate) fileSystems;
mount = config.system.sbin.mount;
job = ''
start on startup
start on new-devices
start on ip-up
script
PATH=${e2fsprogs}/sbin:$PATH
mountPoints=(${toString mountPoints})
devices=(${toString devices})
fsTypes=(${toString fsTypes})
optionss=(${toString optionss})
autocreates=(${toString autocreates})
newDevices=1
# If we mount any file system, we repeat this loop, because new
# mount opportunities may have become available (such as images
# for loopback mounts).
while test -n "$newDevices"; do
newDevices=
for ((n = 0; n < ''${#mountPoints[*]}; n++)); do
mountPoint=''${mountPoints[$n]}
device=''${devices[$n]}
fsType=''${fsTypes[$n]}
options=''${optionss[$n]}
autocreate=''${autocreates[$n]}
isLabel=
if echo "$device" | grep -q '^LABEL='; then isLabel=1; fi
isPseudo=
if test "$fsType" = "nfs" || test "$fsType" = "tmpfs" ||
test "$fsType" = "ext3cow"; then isPseudo=1; fi
if ! test -n "$isLabel" -o -n "$isPseudo" -o -e "$device"; then
echo "skipping $device, doesn't exist (yet)"
continue
fi
# !!! quick hack: if mount point already exists, try a
# remount to change the options but nothing else.
if cat /proc/mounts | grep -F -q " $mountPoint "; then
echo "remounting $device on $mountPoint"
${mount}/bin/mount -t "$fsType" \
-o remount,"$options" \
"$device" "$mountPoint" || true
continue
fi
# If $device is already mounted somewhere else, unmount it first.
# !!! Note: we use /etc/mtab, not /proc/mounts, because mtab
# contains more accurate info when using loop devices.
# !!! not very smart about labels yet; should resolve the label somehow.
if test -z "$isLabel" -a -z "$isPseudo"; then
device=$(readlink -f "$device")
prevMountPoint=$(
cat /etc/mtab \
| grep "^$device " \
| sed 's|^[^ ]\+ \+\([^ ]\+\).*|\1|' \
)
if test "$prevMountPoint" = "$mountPoint"; then
echo "remounting $device on $mountPoint"
${mount}/bin/mount -t "$fsType" \
-o remount,"$options" \
"$device" "$mountPoint" || true
continue
fi
if test -n "$prevMountPoint"; then
echo "unmount $device from $prevMountPoint"
${mount}/bin/umount "$prevMountPoint" || true
fi
fi
echo "mounting $device on $mountPoint"
# !!! should do something with the result; also prevent repeated fscks.
if test -z "$isPseudo"; then
fsck -a "$device" || true
fi
if test "$autocreate" = 1; then mkdir -p "$mountPoint"; fi
if ${mount}/bin/mount -t "$fsType" -o "$options" "$device" "$mountPoint"; then
newDevices=1
fi
done
done
end script
'';
in
{
require = [options];
services = {
extraJobs = [{
name = "filesystems";
inherit job;
}];
};
}