core/swap: follow the configured unit by default

Phenomenon: parameters configured in /etc/fstab for swap units are
ignored. E.g. pri= settings have no effect when systemd starts swap
units. What is even more confusing, .swap units for the name used in
/etc/fstab initially show proper values for Priority=, but after
starting them, they are re-initalized from /proc/swaps and show the -1
value from /proc/swaps.

Change swap units to follow the original configured unit. This way
proper settings are used when starting the swap.

1 files changed, 18 insertions, 3 deletions

diff --git a/src/core/swap.c b/src/core/swap.c
index 36c9e029e9..ef90d0efde 100644
--- a/src/core/swap.c
+++ b/src/core/swap.c
@@ -1208,11 +1208,25 @@ static Unit *swap_following(Unit *u) {
 
         assert(s);
 
-        if (streq_ptr(s->what, s->devnode))
+        /* If the user configured the swap through /etc/fstab or
+         * a device unit, follow that. */
+
+        if (s->from_fragment)
                 return NULL;
 
-        /* Make everybody follow the unit that's named after the swap
-         * device in the kernel */
+        LIST_FOREACH_AFTER(same_devnode, other, s)
+                if (other->from_fragment)
+                        return UNIT(other);
+
+        LIST_FOREACH_BEFORE(same_devnode, other, s)
+                if (other->from_fragment)
+                        return UNIT(other);
+
+        /* Otherwise make everybody follow the unit that's named after
+         * the swap device in the kernel */
+
+        if (streq_ptr(s->what, s->devnode))
+                return NULL;
 
         LIST_FOREACH_AFTER(same_devnode, other, s)
                 if (streq_ptr(other->what, other->devnode))
@@ -1225,6 +1239,7 @@ static Unit *swap_following(Unit *u) {
                 first = other;
         }
 
+        /* Fall back to the first on the list */
         return UNIT(first);
 }