Add D-Bus method to get filesystem metadata

src/dbus_api/pool/mod.rs

@@ -260,6 +260,7 @@ pub fn create_dbus_pool<'a>(
                 .add_m(pool_3_0::rename_method(&f))
                 .add_m(pool_3_3::grow_physical_device_method(&f))
                 .add_m(pool_3_7::get_metadata_method(&f))
+                .add_m(pool_3_7::get_fs_metadata_method(&f))
                 .add_p(pool_3_0::name_property(&f))
                 .add_p(pool_3_0::uuid_property(&f))
                 .add_p(pool_3_0::encrypted_property(&f))

src/dbus_api/pool/pool_3_7/api.rs

@@ -7,7 +7,7 @@ use dbus_tree::{Access, EmitsChangedSignal, Factory, MTSync, Method, Property};
 use crate::dbus_api::{
     consts,
     pool::pool_3_7::{
-        methods::{destroy_filesystems, metadata},
+        methods::{destroy_filesystems, fs_metadata, metadata},
         props::get_pool_metadata_version,
     },
     types::TData,
@@ -47,3 +47,16 @@ pub fn metadata_version_property(
         .emits_changed(EmitsChangedSignal::Const)
         .on_get(get_pool_metadata_version)
 }
+
+pub fn get_fs_metadata_method(f: &Factory<MTSync<TData>, TData>) -> Method<MTSync<TData>, TData> {
+    f.method("FilesystemMetadata", (), fs_metadata)
+        .in_arg(("fs_name", "(bs)"))
+        .in_arg(("current", "b"))
+        // A string representing the pool's filesystem metadata in serialized
+        // JSON format.
+        //
+        // Rust representation: String
+        .out_arg(("results", "s"))
+        .out_arg(("return_code", "q"))
+        .out_arg(("return_string", "s"))
+}

src/dbus_api/pool/pool_3_7/methods.rs

@@ -11,7 +11,7 @@ use crate::{
     dbus_api::{
         consts::filesystem_interface_list,
         types::{DbusErrorEnum, TData, OK_STRING},
-        util::{engine_to_dbus_err_tuple, get_next_arg},
+        util::{engine_to_dbus_err_tuple, get_next_arg, tuple_to_option},
     },
     engine::{EngineAction, FilesystemUuid, StratisUuid},
 };
@@ -148,3 +148,47 @@ pub fn metadata(m: &MethodInfo<'_, MTSync<TData>, TData>) -> MethodResult {
     };
     Ok(vec![msg])
 }
+
+pub fn fs_metadata(m: &MethodInfo<'_, MTSync<TData>, TData>) -> MethodResult {
+    let default_return = String::new();
+
+    let message: &Message = m.msg;
+
+    let return_message = message.method_return();
+
+    let dbus_context = m.tree.get_data();
+    let object_path = m.path.get_name();
+
+    let pool_path = m
+        .tree
+        .get(object_path)
+        .expect("implicit argument must be in tree");
+    let pool_uuid = typed_uuid!(
+        get_data!(pool_path; default_return; return_message).uuid;
+        Pool;
+        default_return;
+        return_message
+    );
+
+    let mut iter = message.iter_init();
+    let filesystem_name: Option<&str> = tuple_to_option(get_next_arg(&mut iter, 0)?);
+    let current: bool = get_next_arg(&mut iter, 1)?;
+
+    let guard = get_pool!(dbus_context.engine; pool_uuid; default_return; return_message);
+    let (_, _, pool) = guard.as_tuple();
+
+    let result = if current {
+        pool.current_fs_metadata(filesystem_name)
+    } else {
+        pool.last_fs_metadata(filesystem_name)
+    };
+
+    let msg = match result {
+        Ok(v) => return_message.append3(v, DbusErrorEnum::OK as u16, OK_STRING.to_string()),
+        Err(err) => {
+            let (rc, rs) = engine_to_dbus_err_tuple(&err);
+            return_message.append3(default_return, rc, rs)
+        }
+    };
+    Ok(vec![msg])
+}

src/dbus_api/pool/pool_3_7/mod.rs

@@ -6,4 +6,7 @@ mod api;
 mod methods;
 mod props;
 
-pub use api::{destroy_filesystems_method, get_metadata_method, metadata_version_property};
+pub use api::{
+    destroy_filesystems_method, get_fs_metadata_method, get_metadata_method,
+    metadata_version_property,
+};

src/engine/engine.rs

@@ -350,6 +350,12 @@ pub trait Pool: Debug + Send + Sync {
 
     /// Get the metadata version for a given pool.
     fn metadata_version(&self) -> StratSigblockVersion;
+
+    /// Get the filesystem metadata that would be written if written now.
+    fn current_fs_metadata(&self, fs_name: Option<&str>) -> StratisResult<String>;
+
+    /// Get the last written filesystem metadata.
+    fn last_fs_metadata(&self, fs_name: Option<&str>) -> StratisResult<String>;
 }
 
 pub type HandleEvents<P> = (

src/engine/sim_engine/filesystem.rs

@@ -10,10 +10,25 @@ use serde_json::{Map, Value};
 use devicemapper::{Bytes, Sectors};
 
 use crate::{
-    engine::{types::FilesystemUuid, Filesystem},
+    engine::{
+        types::{FilesystemUuid, Name},
+        Filesystem,
+    },
     stratis::{StratisError, StratisResult},
 };
 
+#[derive(Debug, Eq, PartialEq, Serialize)]
+pub struct FilesystemSave {
+    name: String,
+    uuid: FilesystemUuid,
+    size: Sectors,
+    created: u64,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    fs_size_limit: Option<Sectors>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    origin: Option<FilesystemUuid>,
+}
+
 #[derive(Debug)]
 pub struct SimFilesystem {
     rand: u32,
@@ -73,6 +88,17 @@ impl SimFilesystem {
         self.origin = None;
         changed
     }
+
+    pub fn record(&self, name: &Name, uuid: FilesystemUuid) -> FilesystemSave {
+        FilesystemSave {
+            name: name.to_owned(),
+            uuid,
+            size: self.size,
+            created: self.created.timestamp() as u64,
+            fs_size_limit: self.size_limit,
+            origin: self.origin,
+        }
+    }
 }
 
 impl Filesystem for SimFilesystem {

src/engine/sim_engine/pool.rs

@@ -758,6 +758,29 @@ impl Pool for SimPool {
     fn metadata_version(&self) -> StratSigblockVersion {
         StratSigblockVersion::V2
     }
+
+    fn current_fs_metadata(&self, fs_name: Option<&str>) -> StratisResult<String> {
+        serde_json::to_string(
+            &self
+                .filesystems
+                .iter()
+                .filter_map(|(name, uuid, fs)| {
+                    if fs_name.map(|n| *n == **name).unwrap_or(true) {
+                        Some((uuid, fs.record(name, *uuid)))
+                    } else {
+                        None
+                    }
+                })
+                .collect::<HashMap<_, _>>(),
+        )
+        .map_err(|e| e.into())
+    }
+
+    fn last_fs_metadata(&self, fs_name: Option<&str>) -> StratisResult<String> {
+        // The sim pool doesn't write data, so the last fs metadata and the
+        // current fs metadata are, by definition, the same.
+        self.current_fs_metadata(fs_name)
+    }
 }
 
 #[cfg(test)]

src/engine/strat_engine/pool/dispatch.rs

@@ -348,4 +348,18 @@ impl Pool for AnyPool {
             AnyPool::V2(p) => p.metadata_version(),
         }
     }
+
+    fn current_fs_metadata(&self, fs_name: Option<&str>) -> StratisResult<String> {
+        match self {
+            AnyPool::V1(p) => p.current_fs_metadata(fs_name),
+            AnyPool::V2(p) => p.current_fs_metadata(fs_name),
+        }
+    }
+
+    fn last_fs_metadata(&self, fs_name: Option<&str>) -> StratisResult<String> {
+        match self {
+            AnyPool::V1(p) => p.last_fs_metadata(fs_name),
+            AnyPool::V2(p) => p.last_fs_metadata(fs_name),
+        }
+    }
 }

src/engine/strat_engine/pool/v1.rs

@@ -1293,6 +1293,14 @@ impl Pool for StratPool {
     fn metadata_version(&self) -> StratSigblockVersion {
         StratSigblockVersion::V1
     }
+
+    fn current_fs_metadata(&self, fs_name: Option<&str>) -> StratisResult<String> {
+        self.thin_pool.current_fs_metadata(fs_name)
+    }
+
+    fn last_fs_metadata(&self, fs_name: Option<&str>) -> StratisResult<String> {
+        self.thin_pool.last_fs_metadata(fs_name)
+    }
 }
 
 pub struct StratPoolState {

src/engine/strat_engine/pool/v2.rs

@@ -1200,6 +1200,14 @@ impl Pool for StratPool {
     fn metadata_version(&self) -> StratSigblockVersion {
         StratSigblockVersion::V2
     }
+
+    fn current_fs_metadata(&self, fs_name: Option<&str>) -> StratisResult<String> {
+        self.thin_pool.current_fs_metadata(fs_name)
+    }
+
+    fn last_fs_metadata(&self, fs_name: Option<&str>) -> StratisResult<String> {
+        self.thin_pool.last_fs_metadata(fs_name)
+    }
 }
 
 pub struct StratPoolState {

src/engine/strat_engine/thinpool/thinpool.rs

@@ -728,6 +728,43 @@ impl<B> ThinPool<B> {
     pub fn clear_out_of_meta_flag(&mut self) {
         self.out_of_meta_space = false;
     }
+
+    /// Calculate filesystem metadata from current state
+    pub fn current_fs_metadata(&self, fs_name: Option<&str>) -> StratisResult<String> {
+        serde_json::to_string(
+            &self
+                .filesystems
+                .iter()
+                .filter_map(|(name, uuid, fs)| {
+                    if fs_name.map(|n| *n == **name).unwrap_or(true) {
+                        Some((*uuid, fs.record(name, *uuid)))
+                    } else {
+                        None
+                    }
+                })
+                .collect::<HashMap<_, _>>(),
+        )
+        .map_err(|e| e.into())
+    }
+
+    /// Read filesystem metadata from mdv
+    pub fn last_fs_metadata(&self, fs_name: Option<&str>) -> StratisResult<String> {
+        serde_json::to_string(
+            &self
+                .mdv
+                .filesystems()?
+                .iter()
+                .filter_map(|fssave| {
+                    if fs_name.map(|n| *n == fssave.name).unwrap_or(true) {
+                        Some((fssave.uuid, fssave))
+                    } else {
+                        None
+                    }
+                })
+                .collect::<HashMap<_, _>>(),
+        )
+        .map_err(|e| e.into())
+    }
 }
 
 impl ThinPool<v1::Backstore> {

tests/client-dbus/src/stratisd_client_dbus/_introspect.py

@@ -176,6 +176,13 @@
       <arg name="return_code" type="q" direction="out" />
       <arg name="return_string" type="s" direction="out" />
     </method>
+    <method name="FilesystemMetadata">
+      <arg name="fs_name" type="(bs)" direction="in" />
+      <arg name="current" type="b" direction="in" />
+      <arg name="results" type="s" direction="out" />
+      <arg name="return_code" type="q" direction="out" />
+      <arg name="return_string" type="s" direction="out" />
+    </method>
     <method name="GrowPhysicalDevice">
       <arg name="dev" type="s" direction="in" />
       <arg name="results" type="b" direction="out" />