load-fragment: make IOScheduling{Class,Priority}= accept the empty string

2 files changed, 17 insertions, 2 deletions

diff --git a/man/systemd.exec.xml b/man/systemd.exec.xml
index b21c5aa10..8fb9ecc6d 100644
--- a/man/systemd.exec.xml
+++ b/man/systemd.exec.xml
@@ -728,7 +728,8 @@ CapabilityBoundingSet=~CAP_B CAP_C</programlisting>
 
         <listitem><para>Sets the I/O scheduling class for executed processes. Takes an integer between 0 and 3 or one
         of the strings <option>none</option>, <option>realtime</option>, <option>best-effort</option> or
-        <option>idle</option>. See
+        <option>idle</option>. If the empty string is assigned to this option, all prior assignments to both
+        <varname>IOSchedulingClass=</varname> and <varname>IOSchedulingPriority=</varname> have no effect. See
         <citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry> for
         details.</para></listitem>
       </varlistentry>
@@ -738,7 +739,9 @@ CapabilityBoundingSet=~CAP_B CAP_C</programlisting>
 
         <listitem><para>Sets the I/O scheduling priority for executed processes. Takes an integer between 0 (highest
         priority) and 7 (lowest priority). The available priorities depend on the selected I/O scheduling class (see
-        above). See <citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry> for
+        above). If the empty string is assigned to this option, all prior assignments to both
+        <varname>IOSchedulingClass=</varname> and <varname>IOSchedulingPriority=</varname> have no effect.
+        See <citerefentry><refentrytitle>ioprio_set</refentrytitle><manvolnum>2</manvolnum></citerefentry> for
         details.</para></listitem>
       </varlistentry>
 
diff --git a/src/core/load-fragment.c b/src/core/load-fragment.c
index d2ce73f72..94583b566 100644
--- a/src/core/load-fragment.c
+++ b/src/core/load-fragment.c
@@ -1115,6 +1115,12 @@ int config_parse_exec_io_class(const char *unit,
         assert(rvalue);
         assert(data);
 
+        if (isempty(rvalue)) {
+                c->ioprio_set = false;
+                c->ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, 0);
+                return 0;
+        }
+
         x = ioprio_class_from_string(rvalue);
         if (x < 0) {
                 log_syntax(unit, LOG_ERR, filename, line, 0, "Failed to parse IO scheduling class, ignoring: %s", rvalue);
@@ -1146,6 +1152,12 @@ int config_parse_exec_io_priority(const char *unit,
         assert(rvalue);
         assert(data);
 
+        if (isempty(rvalue)) {
+                c->ioprio_set = false;
+                c->ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, 0);
+                return 0;
+        }
+
         r = ioprio_parse_priority(rvalue, &i);
         if (r < 0) {
                 log_syntax(unit, LOG_ERR, filename, line, r, "Failed to parse IO priority, ignoring: %s", rvalue);