swap: replace Discard= setting by a more generic Options= setting

For now, it's systemd itself that parses the options string, but as soon
as util-linux' swapon can take the option string directly with -o we
should pass it on unmodified.

man/systemd.swap.xml

@@ -171,14 +171,14 @@
                         </varlistentry>
 
                         <varlistentry>
-                                <term><varname>Discard=</varname></term>
+                                <term><varname>Options=</varname></term>
 
-                                <listitem><para>Enable discards, if the swap
+                                <listitem><para>May contain an option
-                                backing device supports the discard or trim
+                                string for the swap device. This may
-                                operation. Can be one of <literal>none</literal>,
+                                be used for controlling discard
-                                <literal>once</literal>, <literal>pages</literal>
+                                options among other functionality, if
-                                or <literal>all</literal>.  Defaults to
+                                the swap backing device supports the
-                                <literal>none</literal>. (See
+                                discard or trim operation. (See
                                 <citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>
                                 for more information.)
                                 </para></listitem>

src/core/dbus-swap.c

@@ -55,7 +55,7 @@ static int property_get_priority(
         return sd_bus_message_append(reply, "i", p);
 }
 
-static int property_get_discard(
+static int property_get_options(
                 sd_bus *bus,
                 const char *path,
                 const char *interface,
@@ -65,17 +65,16 @@ static int property_get_discard(
                 sd_bus_error *error) {
 
         Swap *s = SWAP(userdata);
-        const char *p;
+        const char *options = NULL;
 
         assert(bus);
         assert(reply);
         assert(s);
 
         if (s->from_fragment)
-                p = s->parameters_fragment.discard ?: "none";
+                options = s->parameters_fragment.options;
-        else
+
-                p = "none";
+        return sd_bus_message_append(reply, "s", options);
-        return sd_bus_message_append(reply, "s", p);
 }
 
 static BUS_DEFINE_PROPERTY_GET_ENUM(property_get_result, swap_result, SwapResult);
@@ -84,7 +83,7 @@ const sd_bus_vtable bus_swap_vtable[] = {
         SD_BUS_VTABLE_START(0),
         SD_BUS_PROPERTY("What", "s", NULL, offsetof(Swap, what), SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
         SD_BUS_PROPERTY("Priority", "i", property_get_priority, 0, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
-        SD_BUS_PROPERTY("Discard", "s", property_get_discard, 0, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
+        SD_BUS_PROPERTY("Options", "s", property_get_options, 0, SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
         SD_BUS_PROPERTY("TimeoutUSec", "t", bus_property_get_usec, offsetof(Swap, timeout_usec), SD_BUS_VTABLE_PROPERTY_CONST),
         SD_BUS_PROPERTY("ControlPID", "u", bus_property_get_pid, offsetof(Swap, control_pid), SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),
         SD_BUS_PROPERTY("Result", "s", property_get_result, offsetof(Swap, result), SD_BUS_VTABLE_PROPERTY_EMITS_CHANGE),

src/core/load-fragment-gperf.gperf.m4

@@ -299,7 +299,7 @@ Automount.DirectoryMode,         config_parse_mode,                  0,
 m4_dnl
 Swap.What,                       config_parse_path,                  0,                             offsetof(Swap, parameters_fragment.what)
 Swap.Priority,                   config_parse_int,                   0,                             offsetof(Swap, parameters_fragment.priority)
-Swap.Discard,                    config_parse_string,                0,                             offsetof(Swap, parameters_fragment.discard)
+Swap.Options,                    config_parse_string,                0,                             offsetof(Swap, parameters_fragment.options)
 Swap.TimeoutSec,                 config_parse_sec,                   0,                             offsetof(Swap, timeout_usec)
 EXEC_CONTEXT_CONFIG_ITEMS(Swap)m4_dnl
 CGROUP_CONTEXT_CONFIG_ITEMS(Swap)m4_dnl

src/core/swap.c

@@ -152,8 +152,8 @@ static void swap_done(Unit *u) {
         free(s->parameters_fragment.what);
         s->parameters_fragment.what = NULL;
 
-        free(s->parameters_fragment.discard);
+        free(s->parameters_fragment.options);
-        s->parameters_fragment.discard = NULL;
+        s->parameters_fragment.options = NULL;
 
         s->exec_runtime = exec_runtime_unref(s->exec_runtime);
         exec_command_done_array(s->exec_command, _SWAP_EXEC_COMMAND_MAX);
@@ -608,11 +608,11 @@ static void swap_dump(Unit *u, FILE *f, const char *prefix) {
                         "%sPriority: %i\n"
                         "%sNoAuto: %s\n"
                         "%sNoFail: %s\n"
-                        "%sDiscard: %s\n",
+                        "%sOptions: %s\n",
                         prefix, p->priority,
                         prefix, yes_no(p->noauto),
                         prefix, yes_no(p->nofail),
-                        prefix, p->discard ?: "none");
+                        prefix, strempty(p->options));
 
         if (s->control_pid > 0)
                 fprintf(f,
@@ -739,9 +739,74 @@ fail:
         swap_enter_dead(s, SWAP_FAILURE_RESOURCES);
 }
 
+static int mount_find_pri(const char *options, int *ret) {
+        const char *opt;
+        char *end;
+        unsigned long r;
+
+        assert(ret);
+
+        if (!options)
+                return 0;
+
+        opt = mount_test_option(options, "pri");
+        if (!opt)
+                return 0;
+
+        opt += strlen("pri");
+        if (*opt != '=')
+                return -EINVAL;
+
+        errno = 0;
+        r = strtoul(opt + 1, &end, 10);
+        if (errno > 0)
+                return -errno;
+
+        if (end == opt + 1 || (*end != ',' && *end != 0))
+                return -EINVAL;
+
+        *ret = (int) r;
+        return 1;
+}
+
+static int mount_find_discard(const char *options, char **ret) {
+        const char *opt;
+        char *ans;
+        size_t len;
+
+        assert(ret);
+
+        if (!options)
+                return 0;
+
+        opt = mount_test_option(options, "discard");
+        if (!opt)
+                return 0;
+
+        opt += strlen("discard");
+        if (*opt == ',' || *opt == '\0')
+                ans = strdup("all");
+        else {
+                if (*opt != '=')
+                        return -EINVAL;
+
+                len = strcspn(opt + 1, ",");
+                if (len == 0)
+                        return -EINVAL;
+
+                ans = strndup(opt + 1, len);
+        }
+
+        if (!ans)
+                return -ENOMEM;
+
+        *ret = ans;
+        return 1;
+}
+
 static void swap_enter_activating(Swap *s) {
-        int r, priority;
+        _cleanup_free_ char *discard = NULL;
-        char *discard;
+        int r, priority = -1;
 
         assert(s);
 
@@ -749,11 +814,11 @@ static void swap_enter_activating(Swap *s) {
         s->control_command = s->exec_command + SWAP_EXEC_ACTIVATE;
 
         if (s->from_fragment) {
+                mount_find_discard(s->parameters_fragment.options, &discard);
+
                 priority = s->parameters_fragment.priority;
-                discard = s->parameters_fragment.discard;
+                if (priority < 0)
-        } else {
+                        mount_find_pri(s->parameters_fragment.options, &priority);
-                priority = -1;
-                discard = NULL;
         }
 
         r = exec_command_set(s->control_command, "/sbin/swapon", NULL);
@@ -770,9 +835,11 @@ static void swap_enter_activating(Swap *s) {
         }
 
         if (discard && !streq(discard, "none")) {
-                const char *discard_arg = "--discard";
+                const char *discard_arg;
 
-                if (!streq(discard, "all"))
+                if (streq(discard, "all"))
+                        discard_arg = "--discard";
+                else
                         discard_arg = strappenda("--discard=", discard);
 
                 r = exec_command_append(s->control_command, discard_arg, NULL);

src/core/swap.h

@@ -63,7 +63,7 @@ typedef enum SwapResult {
 
 typedef struct SwapParameters {
         char *what;
-        char *discard;
+        char *options;
         int priority;
         bool noauto:1;
         bool nofail:1;

src/fstab-generator/fstab-generator.c

@@ -47,7 +47,6 @@ static char *arg_usr_what = NULL;
 static char *arg_usr_fstype = NULL;
 static char *arg_usr_options = NULL;
 
-
 static int mount_find_pri(struct mntent *me, int *ret) {
         char *end, *opt;
         unsigned long r;
@@ -60,7 +59,6 @@ static int mount_find_pri(struct mntent *me, int *ret) {
                 return 0;
 
         opt += strlen("pri");
-
         if (*opt != '=')
                 return -EINVAL;
 
@@ -76,43 +74,9 @@ static int mount_find_pri(struct mntent *me, int *ret) {
         return 1;
 }
 
-static int mount_find_discard(struct mntent *me, char **ret) {
-        char *opt, *ans;
-        size_t len;
-
-        assert(me);
-        assert(ret);
-
-        opt = hasmntopt(me, "discard");
-        if (!opt)
-                return 0;
-
-        opt += strlen("discard");
-
-        if (*opt == ',' || *opt == '\0')
-                ans = strdup("all");
-        else {
-                if (*opt != '=')
-                        return -EINVAL;
-
-                len = strcspn(opt + 1, ",");
-                if (len == 0)
-                        return -EINVAL;
-
-                ans = strndup(opt + 1, len);
-        }
-
-        if (!ans)
-                return -ENOMEM;
-
-        *ret = ans;
-        return 1;
-}
-
 static int add_swap(const char *what, struct mntent *me) {
         _cleanup_free_ char *name = NULL, *unit = NULL, *lnk = NULL;
         _cleanup_fclose_ FILE *f = NULL;
-        _cleanup_free_ char *discard = NULL;
 
         bool noauto;
         int r, pri = -1;
@@ -131,12 +95,6 @@ static int add_swap(const char *what, struct mntent *me) {
                 return r;
         }
 
-        r = mount_find_discard(me, &discard);
-        if (r < 0) {
-                log_error("Failed to parse discard");
-                return r;
-        }
-
         noauto = !!hasmntopt(me, "noauto");
 
         name = unit_name_from_path(what, ".swap");
@@ -165,16 +123,18 @@ static int add_swap(const char *what, struct mntent *me) {
                 "What=%s\n",
                 what);
 
+        /* Note that we currently pass the priority field twice, once
+         * in Priority=, and once in Options= */
         if (pri >= 0)
                 fprintf(f, "Priority=%i\n", pri);
 
-        if (discard)
+        if (!isempty(me->mnt_opts) && !streq(me->mnt_opts, "defaults"))
-                fprintf(f, "Discard=%s\n", discard);
+                fprintf(f, "Options=%s\n", me->mnt_opts);
 
-        fflush(f);
+        r = fflush_and_check(f);
-        if (ferror(f)) {
+        if (r < 0) {
-                log_error("Failed to write unit file %s: %m", unit);
+                log_error("Failed to write unit file %s: %s", unit, strerror(-r));
-                return -errno;
+                return r;
         }
 
         /* use what as where, to have a nicer error message */