use statvfs instead of mount list to determine free data/meta space (fix #611)

src/rpc/Cargo.toml

@@ -24,7 +24,7 @@ hex = "0.4"
 tracing = "0.1"
 rand = "0.8"
 sodiumoxide = { version = "0.2.5-0", package = "kuska-sodiumoxide" }
-systemstat = "0.2.3"
+nix = { version = "0.27", default-features = false, features = ["fs"] }
 
 async-trait = "0.1.7"
 serde = { version = "1.0", default-features = false, features = ["derive", "rc"] }

src/rpc/system.rs

@@ -891,15 +891,14 @@ impl NodeStatus {
 	}
 
 	fn update_disk_usage(&mut self, meta_dir: &Path, data_dir: &Path, metrics: &SystemMetrics) {
-		use systemstat::{Platform, System};
-		let mounts = System::new().mounts().unwrap_or_default();
-
-		let mount_avail = |path: &Path| {
-			mounts
-				.iter()
-				.filter(|x| path.starts_with(&x.fs_mounted_on))
-				.max_by_key(|x| x.fs_mounted_on.len())
-				.map(|x| (x.avail.as_u64(), x.total.as_u64()))
+		use nix::sys::statvfs::statvfs;
+		let mount_avail = |path: &Path| match statvfs(path) {
+			Ok(x) => {
+				let avail = x.blocks_available() * x.fragment_size();
+				let total = x.blocks() * x.fragment_size();
+				Some((avail, total))
+			}
+			Err(_) => None,
 		};
 
 		self.meta_disk_avail = mount_avail(meta_dir);