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author | jakobrs <jakobrs100@gmail.com> | 2020-05-21 09:10:47 +0200 |
---|---|---|
committer | jakobrs <jakobrs100@gmail.com> | 2021-06-08 18:51:31 +0200 |
commit | b07602a604d6d5db3b1ff85d1c3c008ad25245fa (patch) | |
tree | c0a9b740b761540b69a0639857f06c38793a5142 /nixos | |
parent | c8e32eddf825bdec9d510185357cb887622531f9 (diff) | |
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nixos/lib, nixos/filesystems: Make fsBefore more stable, and add `depends` option
Diffstat (limited to 'nixos')
-rw-r--r-- | nixos/lib/utils.nix | 26 | ||||
-rw-r--r-- | nixos/modules/tasks/filesystems.nix | 20 |
2 files changed, 42 insertions, 4 deletions
diff --git a/nixos/lib/utils.nix b/nixos/lib/utils.nix index c9dfdbed99a..1a51b149e56 100644 --- a/nixos/lib/utils.nix +++ b/nixos/lib/utils.nix @@ -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. diff --git a/nixos/modules/tasks/filesystems.nix b/nixos/modules/tasks/filesystems.nix index 065d6cc95d1..2949c82df8f 100644 --- a/nixos/modules/tasks/filesystems.nix +++ b/nixos/modules/tasks/filesystems.nix @@ -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 = { |