feat(storage)!: add live root-disk growth

Cargo.toml

@@ -205,3 +205,17 @@ parking_lot = "0.12"
 rpassword = "7"
 russh = "0.62.4"
 russh-sftp = "2.3.0"
+
+# Keep this stack reproducible until the block-capacity API is released.
+[patch.crates-io]
+msb_krun = { git = "https://github.com/superradcompany/libkrun", rev = "ec9f119dcc144f1c011fe62ebd224d660c2191a3" }
+msb_krun_arch = { git = "https://github.com/superradcompany/libkrun", rev = "ec9f119dcc144f1c011fe62ebd224d660c2191a3" }
+msb_krun_arch_gen = { git = "https://github.com/superradcompany/libkrun", rev = "ec9f119dcc144f1c011fe62ebd224d660c2191a3" }
+msb_krun_cpuid = { git = "https://github.com/superradcompany/libkrun", rev = "ec9f119dcc144f1c011fe62ebd224d660c2191a3" }
+msb_krun_devices = { git = "https://github.com/superradcompany/libkrun", rev = "ec9f119dcc144f1c011fe62ebd224d660c2191a3" }
+msb_krun_hvf = { git = "https://github.com/superradcompany/libkrun", rev = "ec9f119dcc144f1c011fe62ebd224d660c2191a3" }
+msb_krun_kernel = { git = "https://github.com/superradcompany/libkrun", rev = "ec9f119dcc144f1c011fe62ebd224d660c2191a3" }
+msb_krun_polly = { git = "https://github.com/superradcompany/libkrun", rev = "ec9f119dcc144f1c011fe62ebd224d660c2191a3" }
+msb_krun_smbios = { git = "https://github.com/superradcompany/libkrun", rev = "ec9f119dcc144f1c011fe62ebd224d660c2191a3" }
+msb_krun_utils = { git = "https://github.com/superradcompany/libkrun", rev = "ec9f119dcc144f1c011fe62ebd224d660c2191a3" }
+msb_krun_vmm = { git = "https://github.com/superradcompany/libkrun", rev = "ec9f119dcc144f1c011fe62ebd224d660c2191a3" }

crates/agentd/lib/agent.rs

@@ -490,6 +490,37 @@ async fn handle_message(
     heartbeat_control: &heartbeat::HeartbeatControl,
 ) -> AgentdResult<()> {
     match msg.t {
+        MessageType::RootDiskPrepare | MessageType::RootDiskGrow => {
+            let Some(request) = decode_payload_or_core_error::<
+                microsandbox_protocol::core::RootDiskGrow,
+            >(&msg, out_buf)?
+            else {
+                return Ok(());
+            };
+            let apply = msg.t == MessageType::RootDiskGrow;
+            let result = tokio::task::spawn_blocking(move || {
+                crate::root_disk::resize(request.size_bytes, apply)
+            })
+            .await
+            .map_err(|e| AgentdError::ExecSession(format!("root grow worker: {e}")))?;
+            let reply = match result {
+                Ok(state) => Message::with_payload(MessageType::RootDiskState, msg.id, &state),
+                Err(message) => Message::with_payload(
+                    MessageType::CoreError,
+                    msg.id,
+                    &CoreError {
+                        kind: CoreErrorKind::CapabilityUnavailable,
+                        message,
+                        offending_type: Some(msg.t.as_str().into()),
+                    },
+                ),
+            }
+            .map_err(|e| AgentdError::ExecSession(format!("encode root capacity: {e}")))?;
+            codec::encode_to_buf(&reply, out_buf).map_err(|e| {
+                AgentdError::ExecSession(format!("encode root capacity frame: {e}"))
+            })?;
+        }
+
         MessageType::Ping => {
             let Some(_) = decode_payload_or_core_error::<Ping>(&msg, out_buf)? else {
                 return Ok(());

crates/agentd/lib/init.rs

@@ -266,6 +266,7 @@ mod linux {
         match spec {
             BlockRootSpec::DiskImage { device, fstype } => {
                 mount_disk_image(device, fstype.as_deref())?;
+                crate::root_disk::register("/newroot", device);
             }
             BlockRootSpec::OciErofs { lower, upper } => {
                 mount_oci_erofs(lower, upper)?;
@@ -328,6 +329,7 @@ mod linux {
                     None::<&str>,
                 )
                 .map_err(|e| AgentdError::Init(format!("mount {device} at {upperfs_dir}: {e}")))?;
+                crate::root_disk::register(upperfs_dir, device);
             }
             BlockRootUpper::Tmpfs { size_mib } => {
                 let data = size_mib

crates/agentd/lib/lib.rs

@@ -9,6 +9,7 @@
 mod config;
 mod error;
 mod rlimit;
+mod root_disk;
 mod workload;
 
 //--------------------------------------------------------------------------------------------------