core: simplify requirements in unit_get_private_var_tmp() to just After=

As in the previous commit, checking for both requirements and ordering seems
unnecessary. In practical cases, the mount will be pulled in by the rest
of the transaction, so ordering is the part that matters. (The setup is
racy without the ordering.)  If we drop the second check, the admin can
just use After=tmp.mount to achieve the desired behaviour, without needing
to explicitly pull in the unit. This is easier to configure and more robust.

This changes the implementation introduced in
6156bec7a464815084fa5218fe782ea6cb20ad52.

Also actually describe the implemented behaviour in the man page.

diff --git a/man/systemd.exec.xml b/man/systemd.exec.xml
index 3f06f564b33c813cd7dee147dfe07bc6401c3a7a..e7d5e63c963de6c141cdbeae412448f30b1c9c83 100644 (file)
--- a/man/systemd.exec.xml
+++ b/man/systemd.exec.xml
@@ -76,7 +76,13 @@
       <listitem><para>Units with <varname>PrivateTmp=disconnected</varname> automatically gain dependencies
       of type <varname>Wants=</varname> and <varname>After=</varname> on the mount required to access
       <filename>/var/</filename>, unless <varname>DefaultDependencies=no</varname> and/or
-      <varname>RootDirectory=/RootImage=</varname> are specified.</para></listitem>
+      <varname>RootDirectory=</varname>/<varname>RootImage=</varname> are specified. If
+      <varname>DefaultDependencies=no</varname> is specified, and a
+      <varname>RequiresMountsFor=/var/</varname>, <varname>WantsMountsFor=/var/</varname>,
+      <varname>After=var.mount</varname>, <varname>RootDirectory=</varname>/<varname>RootImage=</varname> are
+      not specified, the private mount on <filename>/tmp/</filename> is reused for
+      <filename>/var/tmp/</filename> by setting <varname>$TMPDIR</varname> appropriately.</para>
+      </listitem>
 
       <listitem><para>Units whose standard output or error output is connected to <option>journal</option> or
       <option>kmsg</option> (or their combinations with console output, see below) automatically acquire

diff --git a/src/core/unit.c b/src/core/unit.c
index dc158fb335b8492e04ffb4ea965d565ea97a0f0d..bb3430186cab0ed998bfd43b1d3e8d0a7bde2b65 100644 (file)
--- a/src/core/unit.c
+++ b/src/core/unit.c
@@ -4373,17 +4373,9 @@ static PrivateTmp unit_get_private_var_tmp(const Unit *u, const ExecContext *c)
                 if (hashmap_contains(u->mounts_for[t], "/var/"))
                         return PRIVATE_TMP_DISCONNECTED;
 
-        /* Check the same but for After= with Requires=/Requisite=/Wants= or friends. */
+        /* Check the same but for After=. */
         Unit *m = manager_get_unit(u->manager, "var.mount");
-        if (!m)
-                return PRIVATE_TMP_NO;
-
-        if (!unit_has_dependency(u, UNIT_ATOM_AFTER, m))
-                return PRIVATE_TMP_NO;
-
-        if (unit_has_dependency(u, UNIT_ATOM_PULL_IN_START, m) ||
-            unit_has_dependency(u, UNIT_ATOM_PULL_IN_VERIFY, m) ||
-            unit_has_dependency(u, UNIT_ATOM_PULL_IN_START_IGNORED, m))
+        if (m && unit_has_dependency(u, UNIT_ATOM_AFTER, m))
                 return PRIVATE_TMP_DISCONNECTED;
 
         return PRIVATE_TMP_NO;