swap: restore support for nofail

systemd stops adding automatic dependencies on swap.target to swap
units. If a dependency is required, it has to be added by unit
configuration. fstab-generator did that already, except that now it is
modified to create a Requires or Wants type dependency, depending on
whether nofail is specified in /etc/fstab. This makes .swap units
obey the nofail/noauto options more or less the same as .mount units.

Documentation is extended to clarify that, and to make
systemd.mount(5) and system.swap(5) more similar. The gist is not
changed, because current behaviour actually matches existing
documentation.

https://bugs.freedesktop.org/show_bug.cgi?id=86488

4 files changed, 70 insertions, 50 deletions

diff --git a/man/systemd.mount.xml b/man/systemd.mount.xml
index ba841c3bab..6d8eae6a93 100644
--- a/man/systemd.mount.xml
+++ b/man/systemd.mount.xml
@@ -124,7 +124,7 @@
         </refsect1>
 
         <refsect1>
-                <title><filename>/etc/fstab</filename></title>
+                <title><filename>fstab</filename></title>
 
                 <para>Mount units may either be configured via unit
                 files, or via <filename>/etc/fstab</filename> (see
@@ -142,8 +142,7 @@
                 <para>When reading <filename>/etc/fstab</filename> a
                 few special mount options are understood by systemd
                 which influence how dependencies are created for mount
-                points from <filename>/etc/fstab</filename>. systemd
-                will create a dependency of type
+                points. systemd will create a dependency of type
                 <option>Wants</option> or <option>Requires</option>
                 (see option <option>nofail</option> below), from
                 either <filename>local-fs.target</filename> or
@@ -181,26 +180,13 @@
                   </varlistentry>
 
                   <varlistentry>
-                    <term><option>nofail</option></term>
-                    <term><option>fail</option></term>
-
-                    <listitem><para>With <option>nofail</option> this
-                    mount will be only wanted, not required, by the
-                    <filename>local-fs.target</filename>. This means
-                    that the boot will continue even if this mount
-                    point is not mounted successfully. Option
-                    <option>fail</option> has the opposite meaning and
-                    is the default.</para>
-                    </listitem>
-                  </varlistentry>
-
-                  <varlistentry>
                     <term><option>noauto</option></term>
                     <term><option>auto</option></term>
 
                     <listitem><para>With <option>noauto</option>, this
                     mount will not be added as a dependency for
-                    <filename>local-fs.target</filename>. This means
+                    <filename>local-fs.target</filename> or
+                    <filename>remote-fs.target</filename>. This means
                     that it will not be mounted automatically during
                     boot, unless it is pulled in by some other
                     unit. Option <option>auto</option> has the
@@ -209,6 +195,21 @@
                   </varlistentry>
 
                   <varlistentry>
+                    <term><option>nofail</option></term>
+                    <term><option>fail</option></term>
+
+                    <listitem><para>With <option>nofail</option> this
+                    mount will be only wanted, not required, by
+                    <filename>local-fs.target</filename> or
+                    <filename>remote-fs.target</filename>. This means
+                    that the boot will continue even if this mount
+                    point is not mounted successfully. Option
+                    <option>fail</option> has the opposite meaning and
+                    is the default.</para>
+                    </listitem>
+                  </varlistentry>
+
+                  <varlistentry>
                     <term><option>x-initrd.mount</option></term>
 
                     <listitem><para>An additional filesystem to be
diff --git a/man/systemd.swap.xml b/man/systemd.swap.xml
index 44c16e7bcc..1155758e28 100644
--- a/man/systemd.swap.xml
+++ b/man/systemd.swap.xml
@@ -117,12 +117,40 @@
                 <filename>/etc/fstab</filename> and a unit file, the
                 configuration in the latter takes precedence.</para>
 
-                <para>Unless the <option>noauto</option> option is set
-                for them all swap units configured in
-                <filename>/etc/fstab</filename> are also added as
-                requirements to <filename>swap.target</filename>, so
-                that they are waited for and activated during
-                boot.</para>
+                <para>When reading <filename>/etc/fstab</filename> a
+                few special options are understood by systemd which
+                influence how dependencies are created for swap
+                units.</para>
+
+                <variablelist class='fstab-options'>
+                  <varlistentry>
+                    <term><option>noauto</option></term>
+                    <term><option>auto</option></term>
+
+                    <listitem><para>With <option>noauto</option> the
+                    swap unit will not be added as a dependency for
+                    <filename>swap.target</filename>. This means that
+                    it will not be activated automatically during
+                    boot, unless it is pulled in by some other
+                    unit. Option <option>auto</option> has the
+                    opposite meaning and is the default.</para>
+                    </listitem>
+                  </varlistentry>
+
+                  <varlistentry>
+                    <term><option>nofail</option></term>
+                    <term><option>fail</option></term>
+
+                    <listitem><para>With <option>nofail</option> the
+                    swap unit will be only wanted, not required by
+                    <filename>swap.target</filename>. This means that
+                    the boot will continue even if this swap device is
+                    not activated successfully. Option
+                    <option>fail</option> has the opposite meaning and
+                    is the default.</para>
+                    </listitem>
+                  </varlistentry>
+                </variablelist>
         </refsect1>
 
         <refsect1>
diff --git a/src/core/swap.c b/src/core/swap.c
index 0a1cc80936..e509a633d0 100644
--- a/src/core/swap.c
+++ b/src/core/swap.c
@@ -209,8 +209,6 @@ static int swap_add_device_links(Swap *s) {
 }
 
 static int swap_add_default_dependencies(Swap *s) {
-        int r;
-
         assert(s);
 
         if (UNIT(s)->manager->running_as != SYSTEMD_SYSTEM)
@@ -219,19 +217,7 @@ static int swap_add_default_dependencies(Swap *s) {
         if (detect_container(NULL) > 0)
                 return 0;
 
-        r = unit_add_two_dependencies_by_name(UNIT(s), UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_UMOUNT_TARGET, NULL, true);
-        if (r < 0)
-                return r;
-
-        if (!s->from_fragment)
-                /* The swap unit can either be for an alternative device name, in which
-                 * case we don't need to add the dependency on swap.target because this unit
-                 * is following a different unit which will have this dependency added,
-                 * or it can be derived from /proc/swaps, in which case it was started
-                 * manually, and should not become a dependency of swap.target. */
-                return 0;
-
-        return unit_add_two_dependencies_by_name_inverse(UNIT(s), UNIT_AFTER, UNIT_REQUIRES, SPECIAL_SWAP_TARGET, NULL, true);
+        return unit_add_two_dependencies_by_name(UNIT(s), UNIT_BEFORE, UNIT_CONFLICTS, SPECIAL_UMOUNT_TARGET, NULL, true);
 }
 
 static int swap_verify(Swap *s) {
diff --git a/src/fstab-generator/fstab-generator.c b/src/fstab-generator/fstab-generator.c
index af45c25400..14e664236e 100644
--- a/src/fstab-generator/fstab-generator.c
+++ b/src/fstab-generator/fstab-generator.c
@@ -74,11 +74,14 @@ static int mount_find_pri(struct mntent *me, int *ret) {
         return 1;
 }
 
-static int add_swap(const char *what, struct mntent *me) {
+static int add_swap(
+                const char *what,
+                struct mntent *me,
+                bool noauto,
+                bool nofail) {
+
         _cleanup_free_ char *name = NULL, *unit = NULL, *lnk = NULL;
         _cleanup_fclose_ FILE *f = NULL;
-
-        bool noauto;
         int r, pri = -1;
 
         assert(what);
@@ -95,8 +98,6 @@ static int add_swap(const char *what, struct mntent *me) {
                 return r;
         }
 
-        noauto = !!hasmntopt(me, "noauto");
-
         name = unit_name_from_path(what, ".swap");
         if (!name)
                 return log_oom();
@@ -143,7 +144,8 @@ static int add_swap(const char *what, struct mntent *me) {
                 return r;
 
         if (!noauto) {
-                lnk = strjoin(arg_dest, "/" SPECIAL_SWAP_TARGET ".wants/", name, NULL);
+                lnk = strjoin(arg_dest, "/" SPECIAL_SWAP_TARGET,
+                              nofail ? ".wants/" : ".requires/", name, NULL);
                 if (!lnk)
                         return log_oom();
 
@@ -357,6 +359,7 @@ static int parse_fstab(bool initrd) {
 
         while ((me = getmntent(f))) {
                 _cleanup_free_ char *where = NULL, *what = NULL;
+                bool noauto, nofail;
                 int k;
 
                 if (initrd && !mount_in_initrd(me))
@@ -378,16 +381,18 @@ static int parse_fstab(bool initrd) {
                 if (is_path(where))
                         path_kill_slashes(where);
 
-                log_debug("Found entry what=%s where=%s type=%s", what, where, me->mnt_type);
+                noauto = !!hasmntopt(me, "noauto");
+                nofail = !!hasmntopt(me, "nofail");
+                log_debug("Found entry what=%s where=%s type=%s nofail=%s noauto=%s",
+                          what, where, me->mnt_type,
+                          yes_no(noauto), yes_no(nofail));
 
                 if (streq(me->mnt_type, "swap"))
-                        k = add_swap(what, me);
+                        k = add_swap(what, me, noauto, nofail);
                 else {
-                        bool noauto, nofail, automount;
+                        bool automount;
                         const char *post;
 
-                        noauto = !!hasmntopt(me, "noauto");
-                        nofail = !!hasmntopt(me, "nofail");
                         automount =
                                   hasmntopt(me, "comment=systemd.automount") ||
                                   hasmntopt(me, "x-systemd.automount");