Merge pull request #86967 from jakobrs/more-general-fsbefore

nixos/lib/utils: Add `fileSystems.<name>.depends` option and generalise fsBefore (fixes #86955)
This commit is contained in:
Kim Lindberger 2021-06-14 10:50:07 +02:00 committed by GitHub
commit 26706834a5
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
4 changed files with 54 additions and 4 deletions

View file

@ -14,8 +14,30 @@ rec {
fsNeededForBoot = fs: fs.neededForBoot || elem fs.mountPoint pathsNeededForBoot;
# Check whenever `b` depends on `a` as a fileSystem
fsBefore = a: b: a.mountPoint == b.device
|| hasPrefix "${a.mountPoint}${optionalString (!(hasSuffix "/" a.mountPoint)) "/"}" b.mountPoint;
fsBefore = a: b:
let
# normalisePath adds a slash at the end of the path if it didn't already
# have one.
#
# The reason slashes are added at the end of each path is to prevent `b`
# from accidentally depending on `a` in cases like
# a = { mountPoint = "/aaa"; ... }
# b = { device = "/aaaa"; ... }
# Here a.mountPoint *is* a prefix of b.device even though a.mountPoint is
# *not* a parent of b.device. If we add a slash at the end of each string,
# though, this is not a problem: "/aaa/" is not a prefix of "/aaaa/".
normalisePath = path: "${path}${optionalString (!(hasSuffix "/" path)) "/"}";
normalise = mount: mount // { device = normalisePath mount.device;
mountPoint = normalisePath mount.mountPoint;
depends = map normalisePath mount.depends;
};
a' = normalise a;
b' = normalise b;
in hasPrefix a'.mountPoint b'.device
|| hasPrefix a'.mountPoint b'.mountPoint
|| any (hasPrefix a'.mountPoint) b'.depends;
# Escape a path according to the systemd rules, e.g. /dev/xyzzy
# becomes dev-xyzzy. FIXME: slow.

View file

@ -680,6 +680,12 @@ in
"upperdir=/nix/.rw-store/store"
"workdir=/nix/.rw-store/work"
];
depends = [
"/nix/.ro-store"
"/nix/.rw-store/store"
"/nix/.rw-store/work"
];
};
boot.initrd.availableKernelModules = [ "squashfs" "iso9660" "uas" "overlay" ];

View file

@ -57,6 +57,12 @@ with lib;
"upperdir=/nix/.rw-store/store"
"workdir=/nix/.rw-store/work"
];
depends = [
"/nix/.ro-store"
"/nix/.rw-store/store"
"/nix/.rw-store/work"
];
};
boot.initrd.availableKernelModules = [ "squashfs" "overlay" ];

View file

@ -24,13 +24,15 @@ let
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 = addCheckDesc "non-empty without trailing slash" types.str
(s: isNonEmpty s && (builtins.match ".+/" s) == null);
type = nonEmptyWithoutTrailingSlash;
description = "Location of the mounted the file system.";
};
@ -55,6 +57,20 @@ let
type = types.listOf 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</option> and <option>mountPoint</option> 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</option> of some other filesystem.
'';
};
};
config = {