diff --git a/src/config.rs b/src/config.rs
new file mode 100644
index 0000000..8050da0
--- /dev/null
+++ b/src/config.rs
@@ -0,0 +1,41 @@
+use std::path::PathBuf;
+use std::num::NonZeroUsize;
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum Recursion
+{
+    None,
+    Limited(usize),
+    Unlimited,
+}
+
+impl Default for Recursion
+{
+    #[inline]
+    fn default() -> Self
+    {
+	Self::Unlimited
+    }
+}
+
+impl Recursion
+{
+    /// Can we run at this depth?
+    pub fn can_run(&self, depth: usize) -> bool
+    {
+	match self {
+	    Self::None => depth == 1,
+	    Self::Limited(limit) => depth <= *limit,
+	    Self::Unlimited => true
+	}
+    }
+}
+
+/// Configuration for this run
+#[derive(Debug, Clone, PartialEq, Eq, Default)]
+pub struct Config
+{
+    pub paths: Vec<PathBuf>,
+    pub recursive: Recursion,
+    pub max_tasks: Option<NonZeroUsize>,
+}
diff --git a/src/data/mod.rs b/src/data/mod.rs
index 8585b43..301cc6c 100644
--- a/src/data/mod.rs
+++ b/src/data/mod.rs
@@ -71,6 +71,22 @@ pub enum FsInfo
     Directory,
 }
 
+impl FsInfo
+{
+    /// Is this entry a directory
+    #[inline] pub fn is_dir(&self) -> bool
+    {
+	if let Self::Directory = self
+	{
+	    true
+	}
+	else {
+	    false
+	}
+    }
+}
+
+
 #[cfg(test)]
 mod tests
 {
diff --git a/src/ext.rs b/src/ext.rs
index e9d0387..4ecdd30 100644
--- a/src/ext.rs
+++ b/src/ext.rs
@@ -32,6 +32,15 @@ impl INodeExt for std::fs::Metadata
     }
 }
 
+impl INodeExt for tokio::fs::DirEntry
+{
+    #[inline] fn inode(&self) -> data::INode {
+	use std::os::unix::fs::DirEntryExt as _;
+
+	unsafe { data::INode::new_unchecked(self.ino()) }
+    }
+}
+
 /// A gated stream that releases every N items from the backing stream.
 #[pin_project]
 #[derive(Debug)]
diff --git a/src/main.rs b/src/main.rs
index 947b354..2c9100d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -7,6 +7,9 @@
 pub use ext::prelude::*;
 
 mod data;
+mod config;
+mod state;
+mod work;
 
 #[tokio::main]
 async fn main() {
diff --git a/src/state.rs b/src/state.rs
new file mode 100644
index 0000000..bc802e7
--- /dev/null
+++ b/src/state.rs
@@ -0,0 +1,76 @@
+use super::*;
+use std::sync::Arc;
+
+use data::Cache;
+use config::Config;
+
+/// Program state
+#[derive(Debug, Clone)]
+pub struct State
+{
+    config: Arc<Config>,
+    cache: Cache,
+    depth: usize,
+}
+
+impl State
+{
+    /// Create a new state
+    pub fn new(cfg: Config) -> Self
+    {
+	Self {
+	    config: Arc::new(cfg),
+	    cache: Cache::new(),
+	    depth: 1,
+	}
+    }
+
+    /// Current depth of this tree
+    pub fn depth(&self) -> usize
+    {
+	self.depth
+    }
+    
+    /// Clone into increased depth, if config allows a deeper run.
+    pub fn deeper(&self) -> Option<Self>
+    {
+	if self.config.recursive.can_run(self.depth+1) {
+	    Some(Self{
+		depth: self.depth + 1,
+		..self.clone()
+	    })
+	} else {
+	    None
+	}
+    }
+
+    /// The configuration for this run
+    pub fn config(&self) -> &Config
+    {
+	&self.config
+    }
+
+    /// A reference to the cache of this run
+    pub fn cache(&self) -> &Cache
+    {
+	&self.cache
+    }
+
+    /// Subscribe to this state's cache
+    pub fn cache_sub(&self) -> Cache
+    {
+	self.cache.clone()
+    }
+
+    /// Try to consume the state into the cache.
+    ///
+    /// Fails if there are other references of this state alive.
+    pub fn try_into_cache(self) -> Result<Cache, Self>
+    {
+	match Arc::try_unwrap(self.config)
+	{
+	    Ok(_) => Ok(self.cache),
+	    Err(config) => Err(Self{config, ..self}),
+	}
+    }
+}
diff --git a/src/work.rs b/src/work.rs
new file mode 100644
index 0000000..a40ae43
--- /dev/null
+++ b/src/work.rs
@@ -0,0 +1,166 @@
+use super::*;
+use std::path::{Path, PathBuf};
+use std::collections::HashMap;
+use std::io;
+
+use futures::prelude::*;
+use futures::future::join_all;
+use futures::future::BoxFuture;
+
+use tokio::task::JoinHandle;
+use tokio::fs;
+
+use data::INode;
+use data::FsInfo;
+use state::State;
+
+/// Join a root path onto this hashmap.
+fn join_root<'a>(root: impl AsRef<Path> + 'a, map: HashMap<PathBuf, INode>) -> impl Iterator<Item=(PathBuf, INode)> + 'a
+{
+    map.into_iter().map(move |(k, v)| (root.as_ref().join(k), v))
+}
+
+async fn process_entry(entry: &tokio::fs::DirEntry, parent: INode) -> io::Result<FsInfo>
+{
+    let meta = entry.metadata().await?;
+    if meta.is_dir()
+    {
+	Ok(FsInfo::Directory)
+    } else if meta.is_file()
+    {
+	Ok(FsInfo::File(meta.len(), parent))
+    } else
+    {
+	Err(io::Error::new(io::ErrorKind::Other, "Unknown file type"))
+    }
+}
+
+/// Contains a graph of all paths and inodes that were successfully stat
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct INodeInfoGraph
+{
+    inodes: HashMap<INode, FsInfo>, // FsInfo `file` contains parent INode that can be used to look up again in this table
+    paths: HashMap<PathBuf, INode>, // map absolute paths to INodes to be looked up in `inodes` table.
+}
+
+impl INodeInfoGraph
+{
+    //TODO: Order by largest size
+}
+
+/// Walk on all paths in this state, then return a joined map of all
+///
+/// # Panics
+/// If there are any more held references to `state`.
+pub async fn work_on_all(state: State) -> INodeInfoGraph
+{
+    let comp_children = join_all(state.config().paths.iter().map(|path| {
+	let path = path.clone();
+	async  {
+	    match tokio::fs::symlink_metadata(&path).await {
+		Ok(meta) => {
+		    let inode = meta.inode();
+		    tokio::spawn(walk(state.clone(), path.clone(), inode)).await
+			.ok()
+			.map(move |res| (res, path))
+		},
+		Err(err) => {
+		    eprintln!("Failed to stat root {:?}: {}", path, err);
+		    None
+		},
+	    }
+	}
+    })).await;
+
+    // All children have completed here. Unwrap cache
+    let ino_map = {
+	let cache = state.try_into_cache().unwrap();
+	cache.try_complete().await.unwrap()
+    };
+    let mut output = HashMap::with_capacity(ino_map.len());
+
+    for path_comp in comp_children
+    {
+	if let Some((res, root)) = path_comp
+	{
+	    for (path, ino) in join_root(&root, res)
+	    {
+		if let Some(_) = ino_map.get(&ino) {
+		    output.insert(path, ino);
+		} else {
+		    eprintln!("No ino entry for {:?} ({:?})", path, ino);
+		}
+	    }
+	}
+    }
+
+    INodeInfoGraph {
+	inodes: ino_map,
+	paths: output,
+    }
+}
+
+/// Walk this directory.
+///
+/// # Returns
+/// A *unjoined* map of relative paths and `INode`s inserted into the state's `Cache`.
+/// The caller must join its `root` with these paths to provide a normalized map.
+/// Recusrive calls to `walk` handle this automatically.
+fn walk(state: State, root: PathBuf, root_ino: INode) -> BoxFuture<'static, HashMap<PathBuf, INode>>
+{
+    let mut output = HashMap::new();
+    let mut children: Vec<JoinHandle<HashMap<PathBuf, INode>>> = Vec::new();
+    async move {
+	match fs::read_dir(&root).await
+	{
+	    Ok(mut dir) => {
+		while let Some(entry) = dir.next().await
+		{
+		    match entry
+		    {
+			Ok(entry) => {
+			    let ino = entry.inode();
+			    // Check cache for this
+			    if state.cache().get(&ino).await.is_none() {
+				// Not added, process.
+				match process_entry(&entry, root_ino).await {
+				    Ok(fsinfo) => {
+					if fsinfo.is_dir()
+					{
+					    if let Some(next) = state.deeper()
+					    {
+						children.push(tokio::spawn(
+						    walk(next, entry.path(), ino)
+						));
+					    }
+					}
+					let mut cache = state.cache_sub();
+					cache.insert(ino, fsinfo).await;
+        			    },
+				    Err(err) => eprintln!("Failed to stat {:?}: {}", entry.path(), err),
+				}
+			    }
+			},
+			Err(err) => eprintln!("Walking {:?} failed: {}", root, err),
+		    }
+		}
+	    },
+	    Err(err) => eprintln!("Failed to walk {:?}: {}", root, err),
+	}
+	
+	// Join all children
+	for child in join_all(children.into_iter()).await
+	{
+	    if let Ok(map) = child
+	    {
+		output.extend(join_root(&root, map));
+	    } else {
+		eprintln!("Child panic");
+	    }
+	}
+	
+	output
+    }.boxed()
+}
+
+