mount-options: Add Mount Options Support

When using zram for file system, we need to enable `discard` mount
option for issue discard/TRIM commands to the underlying zram block
device when blocks are freed. Else deleted files are not zero-ed, so
zram does not remove the compressed pages.

Fixes #89

src/config.rs

@@ -22,9 +22,10 @@ pub struct Device {
     pub disksize: u64,
 
     pub swap_priority: i32,
-    pub mount_point: Option<PathBuf>, // when set, a mount unit will be created
-    pub fs_type: Option<String>,      // useful mostly for mounts, None is the same
-                                      // as "swap" when mount_point is not set
+    pub mount_point: Option<PathBuf>,  // when set, a mount unit will be created
+    pub fs_type: Option<String>,       // useful mostly for mounts, None is the same
+                                       // as "swap" when mount_point is not set
+    pub mount_options: Option<String>, // when set, mount options will be applied
 }
 
 impl Device {
@@ -39,6 +40,7 @@ impl Device {
             swap_priority: 100,
             mount_point: None,
             fs_type: None,
+            mount_options: None,
         }
     }
 
@@ -295,6 +297,10 @@ fn parse_line(dev: &mut Device, key: &str, value: &str) -> Result<()> {
             dev.fs_type = Some(value.to_string());
         }
 
+        "mount-options" => {
+            dev.mount_options = Some(value.to_string());
+        }
+
         _ => {
             warn!("Unknown key {}, ignoring.", key);
         }

src/generator.rs

@@ -285,9 +285,11 @@ After=systemd-zram-setup@{zram_device}.service
 [Mount]
 What=/dev/{zram_device}
 Where={mount_point:?}
+Options={mount_options:?}
 ",
             zram_device = device.name,
             mount_point = device.mount_point.as_ref().unwrap(),
+            mount_options = device.mount_options.as_ref().unwrap_or(&String::new()),
         ),
     )?;
 

tests/07-mount-point/run.expected/units/var-compressed.mount

@@ -9,3 +9,4 @@ After=systemd-zram-setup@zram11.service
 [Mount]
 What=/dev/zram11
 Where="/var/compressed"
+Options=""

tests/09-mount-options/etc/systemd/zram-generator.conf

@@ -0,0 +1,4 @@
+[zram11]
+mount-point = /var/compressed
+fs-type = ext4
+mount-options = discard

tests/09-mount-options/proc/meminfo

@@ -0,0 +1,3 @@
+MemTotal:         801322 kB
+MemFree:          611992 kB
+MemAvailable:     139764 kB

tests/09-mount-options/run.expected/units/local-fs.target.wants/var-compressed.mount

@@ -0,0 +1 @@
+../var-compressed.mount

tests/09-mount-options/run.expected/units/systemd-zram-setup@zram11.service.d/bindsto-mount.conf

@@ -0,0 +1,4 @@
+# Automatically generated by "zram-generator"
+
+[Unit]
+BindsTo=var-compressed.mount

tests/09-mount-options/run.expected/units/var-compressed.mount

@@ -0,0 +1,12 @@
+# Automatically generated by "/home/zbyszek/src/zram-generator/target/debug/zram-generator"
+
+[Unit]
+Description=Compressed Storage on /dev/zram11
+Documentation=man:zram-generator(8) man:zram-generator.conf(5)
+Requires=systemd-zram-setup@zram11.service
+After=systemd-zram-setup@zram11.service
+
+[Mount]
+What=/dev/zram11
+Where="/var/compressed"
+Options="discard"

tests/test_cases.rs

@@ -183,3 +183,8 @@ fn test_07_mount_point() {
 fn test_08_plain_device() {
     test_generation("08-plain-device").unwrap();
 }
+
+#[test]
+fn test_09_mount_options() {
+    test_generation("09-mount-options").unwrap();
+}