refactor(tvix/store/fs): Separate FUSE and filesystem code r/6622

In prepration for adding virtiofs support, I thought it would make sense
to split out the filesystem implementation from FUSE itself.

The `fs` module holds the tvix-store filesystem implemetation and the
`fuse` module holds the code to spawn a FUSE daemon backed by multiple
threads.

Change-Id: I8c58447b8c3aa016a613068f8e7ec166554e237c
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9343
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI
Autosubmit: Connor Brewster <cbrewster@hey.com>

5 files changed, 0 insertions, 2453 deletions

diff --git a/tvix/store/src/fuse/file_attr.rs b/tvix/store/src/fuse/file_attr.rs
deleted file mode 100644
index b946aa977a0a..000000000000
--- a/tvix/store/src/fuse/file_attr.rs
+++ /dev/null
@@ -1,46 +0,0 @@
-use super::inodes::{DirectoryInodeData, InodeData};
-use fuse_backend_rs::abi::fuse_abi::Attr;
-
-/// The [Attr] describing the root
-pub const ROOT_FILE_ATTR: Attr = Attr {
-    ino: fuse_backend_rs::api::filesystem::ROOT_ID,
-    size: 0,
-    blksize: 1024,
-    blocks: 0,
-    mode: libc::S_IFDIR | 0o555,
-    atime: 0,
-    mtime: 0,
-    ctime: 0,
-    atimensec: 0,
-    mtimensec: 0,
-    ctimensec: 0,
-    nlink: 0,
-    uid: 0,
-    gid: 0,
-    rdev: 0,
-    flags: 0,
-};
-
-/// for given &Node and inode, construct an [Attr]
-pub fn gen_file_attr(inode_data: &InodeData, inode: u64) -> Attr {
-    Attr {
-        ino: inode,
-        // FUTUREWORK: play with this numbers, as it affects read sizes for client applications.
-        blocks: 1024,
-        size: match inode_data {
-            InodeData::Regular(_, size, _) => *size as u64,
-            InodeData::Symlink(target) => target.len() as u64,
-            InodeData::Directory(DirectoryInodeData::Sparse(_, size)) => *size as u64,
-            InodeData::Directory(DirectoryInodeData::Populated(_, ref children)) => {
-                children.len() as u64
-            }
-        },
-        mode: match inode_data {
-            InodeData::Regular(_, _, false) => libc::S_IFREG | 0o444, // no-executable files
-            InodeData::Regular(_, _, true) => libc::S_IFREG | 0o555,  // executable files
-            InodeData::Symlink(_) => libc::S_IFLNK | 0o444,
-            InodeData::Directory(_) => libc::S_IFDIR | 0o555,
-        },
-        ..Default::default()
-    }
-}
diff --git a/tvix/store/src/fuse/inode_tracker.rs b/tvix/store/src/fuse/inode_tracker.rs
deleted file mode 100644
index 97a9744c31d7..000000000000
--- a/tvix/store/src/fuse/inode_tracker.rs
+++ /dev/null
@@ -1,455 +0,0 @@
-use std::{collections::HashMap, sync::Arc};
-
-use crate::{proto, B3Digest};
-
-use super::inodes::{DirectoryInodeData, InodeData};
-
-/// InodeTracker keeps track of inodes, stores data being these inodes and deals
-/// with inode allocation.
-pub struct InodeTracker {
-    data: HashMap<u64, Arc<InodeData>>,
-
-    // lookup table for blobs by their B3Digest
-    blob_digest_to_inode: HashMap<B3Digest, u64>,
-
-    // lookup table for symlinks by their target
-    symlink_target_to_inode: HashMap<bytes::Bytes, u64>,
-
-    // lookup table for directories by their B3Digest.
-    // Note the corresponding directory may not be present in data yet.
-    directory_digest_to_inode: HashMap<B3Digest, u64>,
-
-    // the next inode to allocate
-    next_inode: u64,
-}
-
-impl Default for InodeTracker {
-    fn default() -> Self {
-        Self {
-            data: Default::default(),
-
-            blob_digest_to_inode: Default::default(),
-            symlink_target_to_inode: Default::default(),
-            directory_digest_to_inode: Default::default(),
-
-            next_inode: 2,
-        }
-    }
-}
-
-impl InodeTracker {
-    // Retrieves data for a given inode, if it exists.
-    pub fn get(&self, ino: u64) -> Option<Arc<InodeData>> {
-        self.data.get(&ino).cloned()
-    }
-
-    // Stores data and returns the inode for it.
-    // In case an inode has already been allocated for the same data, that inode
-    // is returned, otherwise a new one is allocated.
-    // In case data is a [InodeData::Directory], inodes for all items are looked
-    // up
-    pub fn put(&mut self, data: InodeData) -> u64 {
-        match data {
-            InodeData::Regular(ref digest, _, _) => {
-                match self.blob_digest_to_inode.get(digest) {
-                    Some(found_ino) => {
-                        // We already have it, return the inode.
-                        *found_ino
-                    }
-                    None => self.insert_and_increment(data),
-                }
-            }
-            InodeData::Symlink(ref target) => {
-                match self.symlink_target_to_inode.get(target) {
-                    Some(found_ino) => {
-                        // We already have it, return the inode.
-                        *found_ino
-                    }
-                    None => self.insert_and_increment(data),
-                }
-            }
-            InodeData::Directory(DirectoryInodeData::Sparse(ref digest, _size)) => {
-                // check the lookup table if the B3Digest is known.
-                match self.directory_digest_to_inode.get(digest) {
-                    Some(found_ino) => {
-                        // We already have it, return the inode.
-                        *found_ino
-                    }
-                    None => {
-                        // insert and return the inode
-                        self.insert_and_increment(data)
-                    }
-                }
-            }
-            // Inserting [DirectoryInodeData::Populated] usually replaces an
-            // existing [DirectoryInodeData::Sparse] one.
-            InodeData::Directory(DirectoryInodeData::Populated(ref digest, ref children)) => {
-                let dir_ino = self.directory_digest_to_inode.get(digest);
-                if let Some(dir_ino) = dir_ino {
-                    let dir_ino = *dir_ino;
-
-                    // We know the data must exist, as we found it in [directory_digest_to_inode].
-                    let needs_update = match **self.data.get(&dir_ino).unwrap() {
-                        InodeData::Regular(..) | InodeData::Symlink(_) => {
-                            panic!("unexpected type at inode {}", dir_ino);
-                        }
-                        // already populated, nothing to do
-                        InodeData::Directory(DirectoryInodeData::Populated(..)) => false,
-                        // in case the actual data is sparse, replace it with the populated one.
-                        // this allocates inodes for new children in the process.
-                        InodeData::Directory(DirectoryInodeData::Sparse(
-                            ref old_digest,
-                            ref _old_size,
-                        )) => {
-                            // sanity checking to ensure we update the right node
-                            debug_assert_eq!(old_digest, digest);
-
-                            true
-                        }
-                    };
-
-                    if needs_update {
-                        // populate inode fields in children
-                        let children = self.allocate_inodes_for_children(children.to_vec());
-
-                        // update sparse data with populated data
-                        self.data.insert(
-                            dir_ino,
-                            Arc::new(InodeData::Directory(DirectoryInodeData::Populated(
-                                digest.clone(),
-                                children,
-                            ))),
-                        );
-                    }
-
-                    dir_ino
-                } else {
-                    // populate inode fields in children
-                    let children = self.allocate_inodes_for_children(children.to_vec());
-                    // insert and return InodeData
-                    self.insert_and_increment(InodeData::Directory(DirectoryInodeData::Populated(
-                        digest.clone(),
-                        children,
-                    )))
-                }
-            }
-        }
-    }
-
-    // Consume a list of children with zeroed inodes, and allocate (or fetch existing) inodes.
-    fn allocate_inodes_for_children(
-        &mut self,
-        children: Vec<(u64, proto::node::Node)>,
-    ) -> Vec<(u64, proto::node::Node)> {
-        // allocate new inodes for all children
-        let mut children_new: Vec<(u64, proto::node::Node)> = Vec::new();
-
-        for (child_ino, ref child_node) in children {
-            debug_assert_eq!(0, child_ino, "expected child inode to be 0");
-            let child_ino = match child_node {
-                proto::node::Node::Directory(directory_node) => {
-                    // Try putting the sparse data in. If we already have a
-                    // populated version, it'll not update it.
-                    self.put(directory_node.into())
-                }
-                proto::node::Node::File(file_node) => self.put(file_node.into()),
-                proto::node::Node::Symlink(symlink_node) => self.put(symlink_node.into()),
-            };
-
-            children_new.push((child_ino, child_node.clone()))
-        }
-        children_new
-    }
-
-    // Inserts the data and returns the inode it was stored at, while
-    // incrementing next_inode.
-    fn insert_and_increment(&mut self, data: InodeData) -> u64 {
-        let ino = self.next_inode;
-        // insert into lookup tables
-        match data {
-            InodeData::Regular(ref digest, _, _) => {
-                self.blob_digest_to_inode.insert(digest.clone(), ino);
-            }
-            InodeData::Symlink(ref target) => {
-                self.symlink_target_to_inode.insert(target.clone(), ino);
-            }
-            InodeData::Directory(DirectoryInodeData::Sparse(ref digest, _size)) => {
-                self.directory_digest_to_inode.insert(digest.clone(), ino);
-            }
-            // This is currently not used outside test fixtures.
-            // Usually a [DirectoryInodeData::Sparse] is inserted and later
-            // "upgraded" with more data.
-            // However, as a future optimization, a lookup for a PathInfo could trigger a
-            // [DirectoryService::get_recursive()] request that "forks into
-            // background" and prepopulates all Directories in a closure.
-            InodeData::Directory(DirectoryInodeData::Populated(ref digest, _)) => {
-                self.directory_digest_to_inode.insert(digest.clone(), ino);
-            }
-        }
-        // Insert data
-        self.data.insert(ino, Arc::new(data));
-
-        // increment inode counter and return old inode.
-        self.next_inode += 1;
-        ino
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use crate::fuse::inodes::DirectoryInodeData;
-    use crate::proto;
-    use crate::tests::fixtures;
-
-    use super::InodeData;
-    use super::InodeTracker;
-
-    /// Getting something non-existent should be none
-    #[test]
-    fn get_nonexistent() {
-        let inode_tracker = InodeTracker::default();
-        assert!(inode_tracker.get(1).is_none());
-    }
-
-    /// Put of a regular file should allocate a uid, which should be the same when inserting again.
-    #[test]
-    fn put_regular() {
-        let mut inode_tracker = InodeTracker::default();
-        let f = InodeData::Regular(
-            fixtures::BLOB_A_DIGEST.clone(),
-            fixtures::BLOB_A.len() as u32,
-            false,
-        );
-
-        // put it in
-        let ino = inode_tracker.put(f.clone());
-
-        // a get should return the right data
-        let data = inode_tracker.get(ino).expect("must be some");
-        match *data {
-            InodeData::Regular(ref digest, _, _) => {
-                assert_eq!(&fixtures::BLOB_A_DIGEST.clone(), digest);
-            }
-            InodeData::Symlink(_) | InodeData::Directory(..) => panic!("wrong type"),
-        }
-
-        // another put should return the same ino
-        assert_eq!(ino, inode_tracker.put(f));
-
-        // inserting another file should return a different ino
-        assert_ne!(
-            ino,
-            inode_tracker.put(InodeData::Regular(
-                fixtures::BLOB_B_DIGEST.clone(),
-                fixtures::BLOB_B.len() as u32,
-                false,
-            ))
-        );
-    }
-
-    // Put of a symlink should allocate a uid, which should be the same when inserting again
-    #[test]
-    fn put_symlink() {
-        let mut inode_tracker = InodeTracker::default();
-        let f = InodeData::Symlink("target".into());
-
-        // put it in
-        let ino = inode_tracker.put(f.clone());
-
-        // a get should return the right data
-        let data = inode_tracker.get(ino).expect("must be some");
-        match *data {
-            InodeData::Symlink(ref target) => {
-                assert_eq!(b"target".to_vec(), *target);
-            }
-            InodeData::Regular(..) | InodeData::Directory(..) => panic!("wrong type"),
-        }
-
-        // another put should return the same ino
-        assert_eq!(ino, inode_tracker.put(f));
-
-        // inserting another file should return a different ino
-        assert_ne!(ino, inode_tracker.put(InodeData::Symlink("target2".into())));
-    }
-
-    // TODO: put sparse directory
-
-    /// Put a directory into the inode tracker, which refers to a file not seen yet.
-    #[test]
-    fn put_directory_leaf() {
-        let mut inode_tracker = InodeTracker::default();
-
-        // this is a directory with a single item, a ".keep" file pointing to a 0 bytes blob.
-        let dir: InodeData = fixtures::DIRECTORY_WITH_KEEP.clone().into();
-
-        // put it in
-        let dir_ino = inode_tracker.put(dir);
-
-        // a get should return the right data
-        let data = inode_tracker.get(dir_ino).expect("must be some");
-        match *data {
-            InodeData::Directory(super::DirectoryInodeData::Sparse(..)) => {
-                panic!("wrong type");
-            }
-            InodeData::Directory(super::DirectoryInodeData::Populated(
-                ref directory_digest,
-                ref children,
-            )) => {
-                // ensure the directory digest matches
-                assert_eq!(&fixtures::DIRECTORY_WITH_KEEP.digest(), directory_digest);
-
-                // ensure the child is populated, with a different inode than
-                // the parent, and the data matches expectations.
-                assert_eq!(1, children.len());
-                let (child_ino, child_node) = children.first().unwrap();
-                assert_ne!(dir_ino, *child_ino);
-                assert_eq!(
-                    &proto::node::Node::File(
-                        fixtures::DIRECTORY_WITH_KEEP.files.first().unwrap().clone()
-                    ),
-                    child_node
-                );
-
-                // ensure looking up that inode directly returns the data
-                let child_data = inode_tracker.get(*child_ino).expect("must exist");
-                match *child_data {
-                    InodeData::Regular(ref digest, size, executable) => {
-                        assert_eq!(&fixtures::EMPTY_BLOB_DIGEST.clone(), digest);
-                        assert_eq!(0, size);
-                        assert!(!executable);
-                    }
-                    InodeData::Symlink(_) | InodeData::Directory(..) => panic!("wrong type"),
-                }
-            }
-            InodeData::Symlink(_) | InodeData::Regular(..) => panic!("wrong type"),
-        }
-    }
-
-    /// Put a directory into the inode tracker, referring to files, directories
-    /// and symlinks not seen yet.
-    #[test]
-    fn put_directory_complicated() {
-        let mut inode_tracker = InodeTracker::default();
-
-        // this is a directory with a single item, a ".keep" file pointing to a 0 bytes blob.
-        let dir_complicated: InodeData = fixtures::DIRECTORY_COMPLICATED.clone().into();
-
-        // put it in
-        let dir_complicated_ino = inode_tracker.put(dir_complicated);
-
-        // a get should return the right data
-        let dir_data = inode_tracker
-            .get(dir_complicated_ino)
-            .expect("must be some");
-
-        let child_dir_ino = match *dir_data {
-            InodeData::Directory(DirectoryInodeData::Sparse(..)) => {
-                panic!("wrong type");
-            }
-            InodeData::Directory(DirectoryInodeData::Populated(
-                ref directory_digest,
-                ref children,
-            )) => {
-                // assert the directory digest matches
-                assert_eq!(&fixtures::DIRECTORY_COMPLICATED.digest(), directory_digest);
-
-                // ensure there's three children, all with different inodes
-                assert_eq!(3, children.len());
-                let mut seen_inodes = Vec::from([dir_complicated_ino]);
-
-                // check the first child (.keep)
-                {
-                    let (child_ino, child_node) = &children[0];
-                    assert!(!seen_inodes.contains(child_ino));
-                    assert_eq!(
-                        &proto::node::Node::File(fixtures::DIRECTORY_COMPLICATED.files[0].clone()),
-                        child_node
-                    );
-                    seen_inodes.push(*child_ino);
-                }
-
-                // check the second child (aa)
-                {
-                    let (child_ino, child_node) = &children[1];
-                    assert!(!seen_inodes.contains(child_ino));
-                    assert_eq!(
-                        &proto::node::Node::Symlink(
-                            fixtures::DIRECTORY_COMPLICATED.symlinks[0].clone()
-                        ),
-                        child_node
-                    );
-                    seen_inodes.push(*child_ino);
-                }
-
-                // check the third child (keep)
-                {
-                    let (child_ino, child_node) = &children[2];
-                    assert!(!seen_inodes.contains(child_ino));
-                    assert_eq!(
-                        &proto::node::Node::Directory(
-                            fixtures::DIRECTORY_COMPLICATED.directories[0].clone()
-                        ),
-                        child_node
-                    );
-                    seen_inodes.push(*child_ino);
-
-                    // return the child_ino
-                    *child_ino
-                }
-            }
-            InodeData::Regular(..) | InodeData::Symlink(_) => panic!("wrong type"),
-        };
-
-        // get of the inode for child_ino
-        let child_dir_data = inode_tracker.get(child_dir_ino).expect("must be some");
-        // it should be a sparse InodeData::Directory with the right digest.
-        match *child_dir_data {
-            InodeData::Directory(DirectoryInodeData::Sparse(
-                ref child_dir_digest,
-                child_dir_size,
-            )) => {
-                assert_eq!(&fixtures::DIRECTORY_WITH_KEEP.digest(), child_dir_digest);
-                assert_eq!(fixtures::DIRECTORY_WITH_KEEP.size(), child_dir_size);
-            }
-            InodeData::Directory(DirectoryInodeData::Populated(..))
-            | InodeData::Regular(..)
-            | InodeData::Symlink(_) => {
-                panic!("wrong type")
-            }
-        }
-
-        // put DIRECTORY_WITH_KEEP, which should return the same ino as [child_dir_ino],
-        // but update the sparse object to a populated one at the same time.
-        let child_dir_ino2 = inode_tracker.put(fixtures::DIRECTORY_WITH_KEEP.clone().into());
-        assert_eq!(child_dir_ino, child_dir_ino2);
-
-        // get the data
-        match *inode_tracker.get(child_dir_ino).expect("must be some") {
-            // it should be a populated InodeData::Directory with the right digest!
-            InodeData::Directory(DirectoryInodeData::Populated(
-                ref directory_digest,
-                ref children,
-            )) => {
-                // ensure the directory digest matches
-                assert_eq!(&fixtures::DIRECTORY_WITH_KEEP.digest(), directory_digest);
-
-                // ensure the child is populated, with a different inode than
-                // the parent, and the data matches expectations.
-                assert_eq!(1, children.len());
-                let (child_node_inode, child_node) = children.first().unwrap();
-                assert_ne!(dir_complicated_ino, *child_node_inode);
-                assert_eq!(
-                    &proto::node::Node::File(
-                        fixtures::DIRECTORY_WITH_KEEP.files.first().unwrap().clone()
-                    ),
-                    child_node
-                );
-            }
-            InodeData::Directory(DirectoryInodeData::Sparse(..))
-            | InodeData::Regular(..)
-            | InodeData::Symlink(_) => panic!("wrong type"),
-        }
-    }
-}
-
-// TODO: add test inserting a populated one first, then ensure an update doesn't degrade it back to sparse.
diff --git a/tvix/store/src/fuse/inodes.rs b/tvix/store/src/fuse/inodes.rs
deleted file mode 100644
index e8959ce3629b..000000000000
--- a/tvix/store/src/fuse/inodes.rs
+++ /dev/null
@@ -1,68 +0,0 @@
-//! This module contains all the data structures used to track information
-//! about inodes, which present tvix-store nodes in a filesystem.
-use crate::{proto, B3Digest};
-
-#[derive(Clone, Debug)]
-pub enum InodeData {
-    Regular(B3Digest, u32, bool),  // digest, size, executable
-    Symlink(bytes::Bytes),         // target
-    Directory(DirectoryInodeData), // either [DirectoryInodeData:Sparse] or [DirectoryInodeData:Populated]
-}
-
-/// This encodes the two different states of [InodeData::Directory].
-/// Either the data still is sparse (we only saw a [proto::DirectoryNode], but
-/// didn't fetch the [proto::Directory] struct yet,
-/// or we processed a lookup and did fetch the data.
-#[derive(Clone, Debug)]
-pub enum DirectoryInodeData {
-    Sparse(B3Digest, u32),                              // digest, size
-    Populated(B3Digest, Vec<(u64, proto::node::Node)>), // [(child_inode, node)]
-}
-
-impl From<&proto::node::Node> for InodeData {
-    fn from(value: &proto::node::Node) -> Self {
-        match value {
-            proto::node::Node::Directory(directory_node) => directory_node.into(),
-            proto::node::Node::File(file_node) => file_node.into(),
-            proto::node::Node::Symlink(symlink_node) => symlink_node.into(),
-        }
-    }
-}
-
-impl From<&proto::SymlinkNode> for InodeData {
-    fn from(value: &proto::SymlinkNode) -> Self {
-        InodeData::Symlink(value.target.clone())
-    }
-}
-
-impl From<&proto::FileNode> for InodeData {
-    fn from(value: &proto::FileNode) -> Self {
-        InodeData::Regular(
-            value.digest.clone().try_into().unwrap(),
-            value.size,
-            value.executable,
-        )
-    }
-}
-
-/// Converts a DirectoryNode to a sparsely populated InodeData::Directory.
-impl From<&proto::DirectoryNode> for InodeData {
-    fn from(value: &proto::DirectoryNode) -> Self {
-        InodeData::Directory(DirectoryInodeData::Sparse(
-            value.digest.clone().try_into().unwrap(),
-            value.size,
-        ))
-    }
-}
-
-/// converts a proto::Directory to a InodeData::Directory(DirectoryInodeData::Populated(..)).
-/// The inodes for each child are 0, because it's up to the InodeTracker to allocate them.
-impl From<proto::Directory> for InodeData {
-    fn from(value: proto::Directory) -> Self {
-        let digest = value.digest();
-
-        let children: Vec<(u64, proto::node::Node)> = value.nodes().map(|node| (0, node)).collect();
-
-        InodeData::Directory(DirectoryInodeData::Populated(digest, children))
-    }
-}
diff --git a/tvix/store/src/fuse/mod.rs b/tvix/store/src/fuse/mod.rs
deleted file mode 100644
index 1a5d884ef7a9..000000000000
--- a/tvix/store/src/fuse/mod.rs
+++ /dev/null
@@ -1,771 +0,0 @@
-mod file_attr;
-mod inode_tracker;
-mod inodes;
-
-#[cfg(test)]
-mod tests;
-
-use crate::{
-    blobservice::{BlobReader, BlobService},
-    directoryservice::DirectoryService,
-    fuse::inodes::{DirectoryInodeData, InodeData},
-    pathinfoservice::PathInfoService,
-    proto::{node::Node, NamedNode},
-    B3Digest, Error,
-};
-use fuse_backend_rs::{
-    api::filesystem::{Context, FileSystem, FsOptions, ROOT_ID},
-    transport::FuseSession,
-};
-use nix_compat::store_path::StorePath;
-use parking_lot::RwLock;
-use std::{
-    collections::HashMap,
-    io,
-    path::Path,
-    str::FromStr,
-    sync::atomic::AtomicU64,
-    sync::{atomic::Ordering, Arc},
-    thread,
-    time::Duration,
-};
-use tokio::io::{AsyncBufReadExt, AsyncSeekExt};
-use tracing::{debug, error, info_span, warn};
-
-use self::{
-    file_attr::{gen_file_attr, ROOT_FILE_ATTR},
-    inode_tracker::InodeTracker,
-};
-
-/// This implements a read-only FUSE filesystem for a tvix-store
-/// with the passed [BlobService], [DirectoryService] and [PathInfoService].
-///
-/// We don't allow listing on the root mountpoint (inode 0).
-/// In the future, this might be made configurable once a listing method is
-/// added to [self.path_info_service], and then show all store paths in that
-/// store.
-///
-/// Linux uses inodes in filesystems. When implementing FUSE, most calls are
-/// *for* a given inode.
-///
-/// This means, we need to have a stable mapping of inode numbers to the
-/// corresponding store nodes.
-///
-/// We internally delegate all inode allocation and state keeping to the
-/// inode tracker, and store the currently "explored" store paths together with
-/// root inode of the root.
-///
-/// There's some places where inodes are allocated / data inserted into
-/// the inode tracker, if not allocated before already:
-///  - Processing a `lookup` request, either in the mount root, or somewhere
-///    deeper
-///  - Processing a `readdir` request
-///
-///  Things pointing to the same contents get the same inodes, irrespective of
-///  their own location.
-///  This means:
-///  - Symlinks with the same target will get the same inode.
-///  - Regular/executable files with the same contents will get the same inode
-///  - Directories with the same contents will get the same inode.
-///
-/// Due to the above being valid across the whole store, and considering the
-/// merkle structure is a DAG, not a tree, this also means we can't do "bucketed
-/// allocation", aka reserve Directory.size inodes for each PathInfo.
-pub struct FUSE {
-    blob_service: Arc<dyn BlobService>,
-    directory_service: Arc<dyn DirectoryService>,
-    path_info_service: Arc<dyn PathInfoService>,
-
-    /// Whether to (try) listing elements in the root.
-    list_root: bool,
-
-    /// This maps a given StorePath to the inode we allocated for the root inode.
-    store_paths: RwLock<HashMap<StorePath, u64>>,
-
-    /// This keeps track of inodes and data alongside them.
-    inode_tracker: RwLock<InodeTracker>,
-
-    /// This holds all open file handles
-    file_handles: RwLock<HashMap<u64, Arc<tokio::sync::Mutex<Box<dyn BlobReader>>>>>,
-
-    next_file_handle: AtomicU64,
-
-    tokio_handle: tokio::runtime::Handle,
-}
-
-impl FUSE {
-    pub fn new(
-        blob_service: Arc<dyn BlobService>,
-        directory_service: Arc<dyn DirectoryService>,
-        path_info_service: Arc<dyn PathInfoService>,
-        list_root: bool,
-    ) -> Self {
-        Self {
-            blob_service,
-            directory_service,
-            path_info_service,
-
-            list_root,
-
-            store_paths: RwLock::new(HashMap::default()),
-            inode_tracker: RwLock::new(Default::default()),
-
-            file_handles: RwLock::new(Default::default()),
-            next_file_handle: AtomicU64::new(1),
-            tokio_handle: tokio::runtime::Handle::current(),
-        }
-    }
-
-    /// This will turn a lookup request for [std::ffi::OsStr] in the root to
-    /// a ino and [InodeData].
-    /// It will peek in [self.store_paths], and then either look it up from
-    /// [self.inode_tracker],
-    /// or otherwise fetch from [self.path_info_service], and then insert into
-    /// [self.inode_tracker].
-    fn name_in_root_to_ino_and_data(
-        &self,
-        name: &std::ffi::CStr,
-    ) -> Result<Option<(u64, Arc<InodeData>)>, Error> {
-        // parse the name into a [StorePath].
-        let store_path = if let Some(name) = name.to_str().ok() {
-            match StorePath::from_str(name) {
-                Ok(store_path) => store_path,
-                Err(e) => {
-                    debug!(e=?e, "unable to parse as store path");
-                    // This is not an error, but a "ENOENT", as someone can stat
-                    // a file inside the root that's no valid store path
-                    return Ok(None);
-                }
-            }
-        } else {
-            debug!("{name:?} is not a valid utf-8 string");
-            // same here.
-            return Ok(None);
-        };
-
-        let ino = {
-            // This extra scope makes sure we drop the read lock
-            // immediately after reading, to prevent deadlocks.
-            let store_paths = self.store_paths.read();
-            store_paths.get(&store_path).cloned()
-        };
-
-        if let Some(ino) = ino {
-            // If we already have that store path, lookup the inode from
-            // self.store_paths and then get the data from [self.inode_tracker],
-            // which in the case of a [InodeData::Directory] will be fully
-            // populated.
-            Ok(Some((
-                ino,
-                self.inode_tracker.read().get(ino).expect("must exist"),
-            )))
-        } else {
-            // If we don't have it, look it up in PathInfoService.
-            match self.path_info_service.get(store_path.digest)? {
-                // the pathinfo doesn't exist, so the file doesn't exist.
-                None => Ok(None),
-                Some(path_info) => {
-                    // The pathinfo does exist, so there must be a root node
-                    let root_node = path_info.node.unwrap().node.unwrap();
-
-                    // The name must match what's passed in the lookup, otherwise we return nothing.
-                    if root_node.get_name() != store_path.to_string().as_bytes() {
-                        return Ok(None);
-                    }
-
-                    // Let's check if someone else beat us to updating the inode tracker and
-                    // store_paths map.
-                    let mut store_paths = self.store_paths.write();
-                    if let Some(ino) = store_paths.get(&store_path).cloned() {
-                        return Ok(Some((
-                            ino,
-                            self.inode_tracker.read().get(ino).expect("must exist"),
-                        )));
-                    }
-
-                    // insert the (sparse) inode data and register in
-                    // self.store_paths.
-                    // FUTUREWORK: change put to return the data after
-                    // inserting, so we don't need to lookup a second
-                    // time?
-                    let (ino, inode) = {
-                        let mut inode_tracker = self.inode_tracker.write();
-                        let ino = inode_tracker.put((&root_node).into());
-                        (ino, inode_tracker.get(ino).unwrap())
-                    };
-                    store_paths.insert(store_path, ino);
-
-                    Ok(Some((ino, inode)))
-                }
-            }
-        }
-    }
-
-    /// This will lookup a directory by digest, and will turn it into a
-    /// [InodeData::Directory(DirectoryInodeData::Populated(..))].
-    /// This is both used to initially insert the root node of a store path,
-    /// as well as when looking up an intermediate DirectoryNode.
-    fn fetch_directory_inode_data(&self, directory_digest: &B3Digest) -> Result<InodeData, Error> {
-        match self.directory_service.get(directory_digest) {
-            Err(e) => {
-                warn!(e = e.to_string(), directory.digest=%directory_digest, "failed to get directory");
-                Err(e)
-            }
-            // If the Directory can't be found, this is a hole, bail out.
-            Ok(None) => {
-                tracing::error!(directory.digest=%directory_digest, "directory not found in directory service");
-                Err(Error::StorageError(format!(
-                    "directory {} not found",
-                    directory_digest
-                )))
-            }
-            Ok(Some(directory)) => Ok(directory.into()),
-        }
-    }
-}
-
-impl FileSystem for FUSE {
-    type Inode = u64;
-    type Handle = u64;
-
-    fn init(&self, _capable: FsOptions) -> io::Result<FsOptions> {
-        Ok(FsOptions::empty())
-    }
-
-    #[tracing::instrument(skip_all, fields(rq.inode = inode))]
-    fn getattr(
-        &self,
-        _ctx: &Context,
-        inode: Self::Inode,
-        _handle: Option<Self::Handle>,
-    ) -> io::Result<(libc::stat64, Duration)> {
-        if inode == ROOT_ID {
-            return Ok((ROOT_FILE_ATTR.into(), Duration::MAX));
-        }
-
-        match self.inode_tracker.read().get(inode) {
-            None => return Err(io::Error::from_raw_os_error(libc::ENOENT)),
-            Some(node) => {
-                debug!(node = ?node, "found node");
-                Ok((gen_file_attr(&node, inode).into(), Duration::MAX))
-            }
-        }
-    }
-
-    #[tracing::instrument(skip_all, fields(rq.parent_inode = parent, rq.name = ?name))]
-    fn lookup(
-        &self,
-        _ctx: &Context,
-        parent: Self::Inode,
-        name: &std::ffi::CStr,
-    ) -> io::Result<fuse_backend_rs::api::filesystem::Entry> {
-        debug!("lookup");
-
-        // This goes from a parent inode to a node.
-        // - If the parent is [ROOT_ID], we need to check
-        //   [self.store_paths] (fetching from PathInfoService if needed)
-        // - Otherwise, lookup the parent in [self.inode_tracker] (which must be
-        //   a [InodeData::Directory]), and find the child with that name.
-        if parent == ROOT_ID {
-            return match self.name_in_root_to_ino_and_data(name) {
-                Err(e) => {
-                    warn!("{}", e);
-                    Err(io::Error::from_raw_os_error(libc::ENOENT))
-                }
-                Ok(None) => Err(io::Error::from_raw_os_error(libc::ENOENT)),
-                Ok(Some((ino, inode_data))) => {
-                    debug!(inode_data=?&inode_data, ino=ino, "Some");
-                    Ok(fuse_backend_rs::api::filesystem::Entry {
-                        inode: ino,
-                        attr: gen_file_attr(&inode_data, ino).into(),
-                        attr_timeout: Duration::MAX,
-                        entry_timeout: Duration::MAX,
-                        ..Default::default()
-                    })
-                }
-            };
-        }
-
-        // This is the "lookup for "a" inside inode 42.
-        // We already know that inode 42 must be a directory.
-        // It might not be populated yet, so if it isn't, we do (by
-        // fetching from [self.directory_service]), and save the result in
-        // [self.inode_tracker].
-        // Now it for sure is populated, so we search for that name in the
-        // list of children and return the FileAttrs.
-
-        // TODO: Reduce the critical section of this write lock.
-        let mut inode_tracker = self.inode_tracker.write();
-        let parent_data = inode_tracker.get(parent).unwrap();
-        let parent_data = match *parent_data {
-            InodeData::Regular(..) | InodeData::Symlink(_) => {
-                // if the parent inode was not a directory, this doesn't make sense
-                return Err(io::Error::from_raw_os_error(libc::ENOTDIR));
-            }
-            InodeData::Directory(DirectoryInodeData::Sparse(ref parent_digest, _)) => {
-                match self.fetch_directory_inode_data(parent_digest) {
-                    Ok(new_data) => {
-                        // update data in [self.inode_tracker] with populated variant.
-                        // FUTUREWORK: change put to return the data after
-                        // inserting, so we don't need to lookup a second
-                        // time?
-                        let ino = inode_tracker.put(new_data);
-                        inode_tracker.get(ino).unwrap()
-                    }
-                    Err(_e) => {
-                        return Err(io::Error::from_raw_os_error(libc::EIO));
-                    }
-                }
-            }
-            InodeData::Directory(DirectoryInodeData::Populated(..)) => parent_data,
-        };
-
-        // now parent_data can only be a [InodeData::Directory(DirectoryInodeData::Populated(..))].
-        let (parent_digest, children) = if let InodeData::Directory(
-            DirectoryInodeData::Populated(ref parent_digest, ref children),
-        ) = *parent_data
-        {
-            (parent_digest, children)
-        } else {
-            panic!("unexpected type")
-        };
-        let span = info_span!("lookup", directory.digest = %parent_digest);
-        let _enter = span.enter();
-
-        // in the children, find the one with the desired name.
-        if let Some((child_ino, _)) = children.iter().find(|e| e.1.get_name() == name.to_bytes()) {
-            // lookup the child [InodeData] in [self.inode_tracker].
-            // We know the inodes for children have already been allocated.
-            let child_inode_data = inode_tracker.get(*child_ino).unwrap();
-
-            // Reply with the file attributes for the child.
-            // For child directories, we still have all data we need to reply.
-            Ok(fuse_backend_rs::api::filesystem::Entry {
-                inode: *child_ino,
-                attr: gen_file_attr(&child_inode_data, *child_ino).into(),
-                attr_timeout: Duration::MAX,
-                entry_timeout: Duration::MAX,
-                ..Default::default()
-            })
-        } else {
-            // Child not found, return ENOENT.
-            Err(io::Error::from_raw_os_error(libc::ENOENT))
-        }
-    }
-
-    // TODO: readdirplus?
-
-    #[tracing::instrument(skip_all, fields(rq.inode = inode, rq.offset = offset))]
-    fn readdir(
-        &self,
-        _ctx: &Context,
-        inode: Self::Inode,
-        _handle: Self::Handle,
-        _size: u32,
-        offset: u64,
-        add_entry: &mut dyn FnMut(fuse_backend_rs::api::filesystem::DirEntry) -> io::Result<usize>,
-    ) -> io::Result<()> {
-        debug!("readdir");
-
-        if inode == ROOT_ID {
-            if !self.list_root {
-                return Err(io::Error::from_raw_os_error(libc::EPERM)); // same error code as ipfs/kubo
-            } else {
-                for (i, path_info) in self
-                    .path_info_service
-                    .list()
-                    .skip(offset as usize)
-                    .enumerate()
-                {
-                    let path_info = match path_info {
-                        Err(e) => {
-                            warn!("failed to retrieve pathinfo: {}", e);
-                            return Err(io::Error::from_raw_os_error(libc::EPERM));
-                        }
-                        Ok(path_info) => path_info,
-                    };
-
-                    // We know the root node exists and the store_path can be parsed because clients MUST validate.
-                    let root_node = path_info.node.unwrap().node.unwrap();
-                    let store_path = StorePath::from_bytes(root_node.get_name()).unwrap();
-
-                    let ino = {
-                        // This extra scope makes sure we drop the read lock
-                        // immediately after reading, to prevent deadlocks.
-                        let store_paths = self.store_paths.read();
-                        store_paths.get(&store_path).cloned()
-                    };
-                    let ino = match ino {
-                        Some(ino) => ino,
-                        None => {
-                            // insert the (sparse) inode data and register in
-                            // self.store_paths.
-                            let ino = self.inode_tracker.write().put((&root_node).into());
-                            self.store_paths.write().insert(store_path.clone(), ino);
-                            ino
-                        }
-                    };
-
-                    let ty = match root_node {
-                        Node::Directory(_) => libc::S_IFDIR,
-                        Node::File(_) => libc::S_IFREG,
-                        Node::Symlink(_) => libc::S_IFLNK,
-                    };
-
-                    let written = add_entry(fuse_backend_rs::api::filesystem::DirEntry {
-                        ino,
-                        offset: offset + i as u64 + 1,
-                        type_: ty,
-                        name: store_path.to_string().as_bytes(),
-                    })?;
-                    // If the buffer is full, add_entry will return `Ok(0)`.
-                    if written == 0 {
-                        break;
-                    }
-                }
-                return Ok(());
-            }
-        }
-
-        // lookup the inode data.
-        let mut inode_tracker = self.inode_tracker.write();
-        let dir_inode_data = inode_tracker.get(inode).unwrap();
-        let dir_inode_data = match *dir_inode_data {
-            InodeData::Regular(..) | InodeData::Symlink(..) => {
-                warn!("Not a directory");
-                return Err(io::Error::from_raw_os_error(libc::ENOTDIR));
-            }
-            InodeData::Directory(DirectoryInodeData::Sparse(ref directory_digest, _)) => {
-                match self.fetch_directory_inode_data(directory_digest) {
-                    Ok(new_data) => {
-                        // update data in [self.inode_tracker] with populated variant.
-                        // FUTUREWORK: change put to return the data after
-                        // inserting, so we don't need to lookup a second
-                        // time?
-                        let ino = inode_tracker.put(new_data.clone());
-                        inode_tracker.get(ino).unwrap()
-                    }
-                    Err(_e) => {
-                        return Err(io::Error::from_raw_os_error(libc::EIO));
-                    }
-                }
-            }
-            InodeData::Directory(DirectoryInodeData::Populated(..)) => dir_inode_data,
-        };
-
-        // now parent_data can only be InodeData::Directory(DirectoryInodeData::Populated(..))
-        if let InodeData::Directory(DirectoryInodeData::Populated(ref _digest, ref children)) =
-            *dir_inode_data
-        {
-            for (i, (ino, child_node)) in children.iter().skip(offset as usize).enumerate() {
-                // the second parameter will become the "offset" parameter on the next call.
-                let written = add_entry(fuse_backend_rs::api::filesystem::DirEntry {
-                    ino: *ino,
-                    offset: offset + i as u64 + 1,
-                    type_: match child_node {
-                        Node::Directory(_) => libc::S_IFDIR,
-                        Node::File(_) => libc::S_IFREG,
-                        Node::Symlink(_) => libc::S_IFLNK,
-                    },
-                    name: child_node.get_name(),
-                })?;
-                // If the buffer is full, add_entry will return `Ok(0)`.
-                if written == 0 {
-                    break;
-                }
-            }
-        } else {
-            panic!("unexpected type")
-        }
-
-        Ok(())
-    }
-
-    #[tracing::instrument(skip_all, fields(rq.inode = inode))]
-    fn open(
-        &self,
-        _ctx: &Context,
-        inode: Self::Inode,
-        _flags: u32,
-        _fuse_flags: u32,
-    ) -> io::Result<(
-        Option<Self::Handle>,
-        fuse_backend_rs::api::filesystem::OpenOptions,
-    )> {
-        if inode == ROOT_ID {
-            return Err(io::Error::from_raw_os_error(libc::ENOSYS));
-        }
-
-        // lookup the inode
-        match *self.inode_tracker.read().get(inode).unwrap() {
-            // read is invalid on non-files.
-            InodeData::Directory(..) | InodeData::Symlink(_) => {
-                warn!("is directory");
-                return Err(io::Error::from_raw_os_error(libc::EISDIR));
-            }
-            InodeData::Regular(ref blob_digest, _blob_size, _) => {
-                let span = info_span!("read", blob.digest = %blob_digest);
-                let _enter = span.enter();
-
-                let blob_service = self.blob_service.clone();
-                let blob_digest = blob_digest.clone();
-
-                let task = self
-                    .tokio_handle
-                    .spawn(async move { blob_service.open_read(&blob_digest).await });
-
-                let blob_reader = self.tokio_handle.block_on(task).unwrap();
-
-                match blob_reader {
-                    Ok(None) => {
-                        warn!("blob not found");
-                        return Err(io::Error::from_raw_os_error(libc::EIO));
-                    }
-                    Err(e) => {
-                        warn!(e=?e, "error opening blob");
-                        return Err(io::Error::from_raw_os_error(libc::EIO));
-                    }
-                    Ok(Some(blob_reader)) => {
-                        // get a new file handle
-                        // TODO: this will overflow after 2**64 operations,
-                        // which is fine for now.
-                        // See https://cl.tvl.fyi/c/depot/+/8834/comment/a6684ce0_d72469d1
-                        // for the discussion on alternatives.
-                        let fh = self.next_file_handle.fetch_add(1, Ordering::SeqCst);
-
-                        debug!("add file handle {}", fh);
-                        self.file_handles
-                            .write()
-                            .insert(fh, Arc::new(tokio::sync::Mutex::new(blob_reader)));
-
-                        Ok((
-                            Some(fh),
-                            fuse_backend_rs::api::filesystem::OpenOptions::empty(),
-                        ))
-                    }
-                }
-            }
-        }
-    }
-
-    #[tracing::instrument(skip_all, fields(rq.inode = inode, fh = handle))]
-    fn release(
-        &self,
-        _ctx: &Context,
-        inode: Self::Inode,
-        _flags: u32,
-        handle: Self::Handle,
-        _flush: bool,
-        _flock_release: bool,
-        _lock_owner: Option<u64>,
-    ) -> io::Result<()> {
-        // remove and get ownership on the blob reader
-        match self.file_handles.write().remove(&handle) {
-            // drop it, which will close it.
-            Some(blob_reader) => drop(blob_reader),
-            None => {
-                // These might already be dropped if a read error occured.
-                debug!("file_handle {} not found", handle);
-            }
-        }
-
-        Ok(())
-    }
-
-    #[tracing::instrument(skip_all, fields(rq.inode = inode, rq.offset = offset, rq.size = size))]
-    fn read(
-        &self,
-        _ctx: &Context,
-        inode: Self::Inode,
-        handle: Self::Handle,
-        w: &mut dyn fuse_backend_rs::api::filesystem::ZeroCopyWriter,
-        size: u32,
-        offset: u64,
-        _lock_owner: Option<u64>,
-        _flags: u32,
-    ) -> io::Result<usize> {
-        debug!("read");
-
-        // We need to take out the blob reader from self.file_handles, so we can
-        // interact with it in the separate task.
-        // On success, we pass it back out of the task, so we can put it back in self.file_handles.
-        let blob_reader = match self.file_handles.read().get(&handle) {
-            Some(blob_reader) => blob_reader.clone(),
-            None => {
-                warn!("file handle {} unknown", handle);
-                return Err(io::Error::from_raw_os_error(libc::EIO));
-            }
-        };
-
-        let task = self.tokio_handle.spawn(async move {
-            let mut blob_reader = blob_reader.lock().await;
-
-            // seek to the offset specified, which is relative to the start of the file.
-            let resp = blob_reader.seek(io::SeekFrom::Start(offset as u64)).await;
-
-            match resp {
-                Ok(pos) => {
-                    debug_assert_eq!(offset as u64, pos);
-                }
-                Err(e) => {
-                    warn!("failed to seek to offset {}: {}", offset, e);
-                    return Err(io::Error::from_raw_os_error(libc::EIO));
-                }
-            }
-
-            // As written in the fuse docs, read should send exactly the number
-            // of bytes requested except on EOF or error.
-
-            let mut buf: Vec<u8> = Vec::with_capacity(size as usize);
-
-            while (buf.len() as u64) < size as u64 {
-                let int_buf = blob_reader.fill_buf().await?;
-                // copy things from the internal buffer into buf to fill it till up until size
-
-                // an empty buffer signals we reached EOF.
-                if int_buf.is_empty() {
-                    break;
-                }
-
-                // calculate how many bytes we can read from int_buf.
-                // It's either all of int_buf, or the number of bytes missing in buf to reach size.
-                let len_to_copy = std::cmp::min(int_buf.len(), size as usize - buf.len());
-
-                // copy these bytes into our buffer
-                buf.extend_from_slice(&int_buf[..len_to_copy]);
-                // and consume them in the buffered reader.
-                blob_reader.consume(len_to_copy);
-            }
-
-            Ok(buf)
-        });
-
-        let buf = self.tokio_handle.block_on(task).unwrap()?;
-
-        w.write(&buf)
-    }
-
-    #[tracing::instrument(skip_all, fields(rq.inode = inode))]
-    fn readlink(&self, _ctx: &Context, inode: Self::Inode) -> io::Result<Vec<u8>> {
-        if inode == ROOT_ID {
-            return Err(io::Error::from_raw_os_error(libc::ENOSYS));
-        }
-
-        // lookup the inode
-        match *self.inode_tracker.read().get(inode).unwrap() {
-            InodeData::Directory(..) | InodeData::Regular(..) => {
-                Err(io::Error::from_raw_os_error(libc::EINVAL))
-            }
-            InodeData::Symlink(ref target) => Ok(target.to_vec()),
-        }
-    }
-}
-
-struct FuseServer<FS>
-where
-    FS: FileSystem + Sync + Send,
-{
-    server: Arc<fuse_backend_rs::api::server::Server<Arc<FS>>>,
-    channel: fuse_backend_rs::transport::FuseChannel,
-}
-
-impl<FS> FuseServer<FS>
-where
-    FS: FileSystem + Sync + Send,
-{
-    fn start(&mut self) -> io::Result<()> {
-        loop {
-            if let Some((reader, writer)) = self
-                .channel
-                .get_request()
-                .map_err(|_| io::Error::from_raw_os_error(libc::EINVAL))?
-            {
-                if let Err(e) = self
-                    .server
-                    .handle_message(reader, writer.into(), None, None)
-                {
-                    match e {
-                        // This indicates the session has been shut down.
-                        fuse_backend_rs::Error::EncodeMessage(e)
-                            if e.raw_os_error() == Some(libc::EBADFD) =>
-                        {
-                            break;
-                        }
-                        error => {
-                            error!(?error, "failed to handle fuse request");
-                            continue;
-                        }
-                    }
-                }
-            } else {
-                break;
-            }
-        }
-        Ok(())
-    }
-}
-
-pub struct FuseDaemon {
-    session: FuseSession,
-    threads: Vec<thread::JoinHandle<()>>,
-}
-
-impl FuseDaemon {
-    pub fn new<FS, P>(fs: FS, mountpoint: P, threads: usize) -> Result<Self, io::Error>
-    where
-        FS: FileSystem + Sync + Send + 'static,
-        P: AsRef<Path>,
-    {
-        let server = Arc::new(fuse_backend_rs::api::server::Server::new(Arc::new(fs)));
-
-        let mut session = FuseSession::new(mountpoint.as_ref(), "tvix-store", "", true)
-            .map_err(|e| io::Error::new(io::ErrorKind::Other, e.to_string()))?;
-
-        session.set_allow_other(false);
-        session
-            .mount()
-            .map_err(|e| io::Error::new(io::ErrorKind::Other, e.to_string()))?;
-        let mut join_handles = Vec::with_capacity(threads);
-        for _ in 0..threads {
-            let mut server = FuseServer {
-                server: server.clone(),
-                channel: session
-                    .new_channel()
-                    .map_err(|e| io::Error::new(io::ErrorKind::Other, e.to_string()))?,
-            };
-            let join_handle = thread::Builder::new()
-                .name("fuse_server".to_string())
-                .spawn(move || {
-                    let _ = server.start();
-                })?;
-            join_handles.push(join_handle);
-        }
-
-        Ok(FuseDaemon {
-            session,
-            threads: join_handles,
-        })
-    }
-
-    pub fn unmount(&mut self) -> Result<(), io::Error> {
-        self.session
-            .umount()
-            .map_err(|e| io::Error::new(io::ErrorKind::Other, e.to_string()))?;
-
-        for thread in self.threads.drain(..) {
-            thread.join().map_err(|_| {
-                io::Error::new(io::ErrorKind::Other, "failed to join fuse server thread")
-            })?;
-        }
-
-        Ok(())
-    }
-}
-
-impl Drop for FuseDaemon {
-    fn drop(&mut self) {
-        if let Err(error) = self.unmount() {
-            error!(?error, "failed to unmont fuse filesystem")
-        }
-    }
-}
diff --git a/tvix/store/src/fuse/tests.rs b/tvix/store/src/fuse/tests.rs
deleted file mode 100644
index 81de8b13de58..000000000000
--- a/tvix/store/src/fuse/tests.rs
+++ /dev/null
@@ -1,1113 +0,0 @@
-use std::io::Cursor;
-use std::os::unix::prelude::MetadataExt;
-use std::path::Path;
-use std::sync::Arc;
-use std::{fs, io};
-
-use tempfile::TempDir;
-
-use crate::blobservice::BlobService;
-use crate::directoryservice::DirectoryService;
-use crate::pathinfoservice::PathInfoService;
-use crate::proto::{DirectoryNode, FileNode, PathInfo};
-use crate::tests::fixtures;
-use crate::tests::utils::{gen_blob_service, gen_directory_service, gen_pathinfo_service};
-use crate::{proto, FuseDaemon, FUSE};
-
-const BLOB_A_NAME: &str = "00000000000000000000000000000000-test";
-const BLOB_B_NAME: &str = "55555555555555555555555555555555-test";
-const HELLOWORLD_BLOB_NAME: &str = "66666666666666666666666666666666-test";
-const SYMLINK_NAME: &str = "11111111111111111111111111111111-test";
-const SYMLINK_NAME2: &str = "44444444444444444444444444444444-test";
-const DIRECTORY_WITH_KEEP_NAME: &str = "22222222222222222222222222222222-test";
-const DIRECTORY_COMPLICATED_NAME: &str = "33333333333333333333333333333333-test";
-
-fn gen_svcs() -> (
-    Arc<dyn BlobService>,
-    Arc<dyn DirectoryService>,
-    Arc<dyn PathInfoService>,
-) {
-    let blob_service = gen_blob_service();
-    let directory_service = gen_directory_service();
-    let path_info_service = gen_pathinfo_service(blob_service.clone(), directory_service.clone());
-
-    (blob_service, directory_service, path_info_service)
-}
-
-fn do_mount<P: AsRef<Path>>(
-    blob_service: Arc<dyn BlobService>,
-    directory_service: Arc<dyn DirectoryService>,
-    path_info_service: Arc<dyn PathInfoService>,
-    mountpoint: P,
-    list_root: bool,
-) -> io::Result<FuseDaemon> {
-    let fs = FUSE::new(
-        blob_service,
-        directory_service,
-        path_info_service,
-        list_root,
-    );
-    FuseDaemon::new(fs, mountpoint.as_ref(), 4)
-}
-
-async fn populate_blob_a(
-    blob_service: &Arc<dyn BlobService>,
-    _directory_service: &Arc<dyn DirectoryService>,
-    path_info_service: &Arc<dyn PathInfoService>,
-) {
-    // Upload BLOB_A
-    let mut bw = blob_service.open_write().await;
-    tokio::io::copy(&mut Cursor::new(fixtures::BLOB_A.to_vec()), &mut bw)
-        .await
-        .expect("must succeed uploading");
-    bw.close().await.expect("must succeed closing");
-
-    // Create a PathInfo for it
-    let path_info = PathInfo {
-        node: Some(proto::Node {
-            node: Some(proto::node::Node::File(FileNode {
-                name: BLOB_A_NAME.into(),
-                digest: fixtures::BLOB_A_DIGEST.clone().into(),
-                size: fixtures::BLOB_A.len() as u32,
-                executable: false,
-            })),
-        }),
-        ..Default::default()
-    };
-    path_info_service.put(path_info).expect("must succeed");
-}
-
-async fn populate_blob_b(
-    blob_service: &Arc<dyn BlobService>,
-    _directory_service: &Arc<dyn DirectoryService>,
-    path_info_service: &Arc<dyn PathInfoService>,
-) {
-    // Upload BLOB_B
-    let mut bw = blob_service.open_write().await;
-    tokio::io::copy(&mut Cursor::new(fixtures::BLOB_B.to_vec()), &mut bw)
-        .await
-        .expect("must succeed uploading");
-    bw.close().await.expect("must succeed closing");
-
-    // Create a PathInfo for it
-    let path_info = PathInfo {
-        node: Some(proto::Node {
-            node: Some(proto::node::Node::File(FileNode {
-                name: BLOB_B_NAME.into(),
-                digest: fixtures::BLOB_B_DIGEST.clone().into(),
-                size: fixtures::BLOB_B.len() as u32,
-                executable: false,
-            })),
-        }),
-        ..Default::default()
-    };
-    path_info_service.put(path_info).expect("must succeed");
-}
-
-/// adds a blob containing helloworld and marks it as executable
-async fn populate_helloworld_blob(
-    blob_service: &Arc<dyn BlobService>,
-    _directory_service: &Arc<dyn DirectoryService>,
-    path_info_service: &Arc<dyn PathInfoService>,
-) {
-    // Upload BLOB_B
-    let mut bw = blob_service.open_write().await;
-    tokio::io::copy(
-        &mut Cursor::new(fixtures::HELLOWORLD_BLOB_CONTENTS.to_vec()),
-        &mut bw,
-    )
-    .await
-    .expect("must succeed uploading");
-    bw.close().await.expect("must succeed closing");
-
-    // Create a PathInfo for it
-    let path_info = PathInfo {
-        node: Some(proto::Node {
-            node: Some(proto::node::Node::File(FileNode {
-                name: HELLOWORLD_BLOB_NAME.into(),
-                digest: fixtures::HELLOWORLD_BLOB_DIGEST.clone().into(),
-                size: fixtures::HELLOWORLD_BLOB_CONTENTS.len() as u32,
-                executable: true,
-            })),
-        }),
-        ..Default::default()
-    };
-    path_info_service.put(path_info).expect("must succeed");
-}
-
-fn populate_symlink(
-    _blob_service: &Arc<dyn BlobService>,
-    _directory_service: &Arc<dyn DirectoryService>,
-    path_info_service: &Arc<dyn PathInfoService>,
-) {
-    // Create a PathInfo for it
-    let path_info = PathInfo {
-        node: Some(proto::Node {
-            node: Some(proto::node::Node::Symlink(proto::SymlinkNode {
-                name: SYMLINK_NAME.into(),
-                target: BLOB_A_NAME.into(),
-            })),
-        }),
-        ..Default::default()
-    };
-    path_info_service.put(path_info).expect("must succeed");
-}
-
-/// This writes a symlink pointing to /nix/store/somewhereelse,
-/// which is the same symlink target as "aa" inside DIRECTORY_COMPLICATED.
-fn populate_symlink2(
-    _blob_service: &Arc<dyn BlobService>,
-    _directory_service: &Arc<dyn DirectoryService>,
-    path_info_service: &Arc<dyn PathInfoService>,
-) {
-    // Create a PathInfo for it
-    let path_info = PathInfo {
-        node: Some(proto::Node {
-            node: Some(proto::node::Node::Symlink(proto::SymlinkNode {
-                name: SYMLINK_NAME2.into(),
-                target: "/nix/store/somewhereelse".into(),
-            })),
-        }),
-        ..Default::default()
-    };
-    path_info_service.put(path_info).expect("must succeed");
-}
-
-async fn populate_directory_with_keep(
-    blob_service: &Arc<dyn BlobService>,
-    directory_service: &Arc<dyn DirectoryService>,
-    path_info_service: &Arc<dyn PathInfoService>,
-) {
-    // upload empty blob
-    let mut bw = blob_service.open_write().await;
-    assert_eq!(
-        fixtures::EMPTY_BLOB_DIGEST.to_vec(),
-        bw.close().await.expect("must succeed closing").to_vec(),
-    );
-
-    // upload directory
-    directory_service
-        .put(fixtures::DIRECTORY_WITH_KEEP.clone())
-        .expect("must succeed uploading");
-
-    // upload pathinfo
-    let path_info = PathInfo {
-        node: Some(proto::Node {
-            node: Some(proto::node::Node::Directory(DirectoryNode {
-                name: DIRECTORY_WITH_KEEP_NAME.into(),
-                digest: fixtures::DIRECTORY_WITH_KEEP.digest().into(),
-                size: fixtures::DIRECTORY_WITH_KEEP.size(),
-            })),
-        }),
-        ..Default::default()
-    };
-    path_info_service.put(path_info).expect("must succeed");
-}
-
-/// Insert [PathInfo] for DIRECTORY_WITH_KEEP, but don't provide the Directory
-/// itself.
-fn populate_pathinfo_without_directory(
-    _: &Arc<dyn BlobService>,
-    _: &Arc<dyn DirectoryService>,
-    path_info_service: &Arc<dyn PathInfoService>,
-) {
-    // upload pathinfo
-    let path_info = PathInfo {
-        node: Some(proto::Node {
-            node: Some(proto::node::Node::Directory(DirectoryNode {
-                name: DIRECTORY_WITH_KEEP_NAME.into(),
-                digest: fixtures::DIRECTORY_WITH_KEEP.digest().into(),
-                size: fixtures::DIRECTORY_WITH_KEEP.size(),
-            })),
-        }),
-        ..Default::default()
-    };
-    path_info_service.put(path_info).expect("must succeed");
-}
-
-/// Insert , but don't provide the blob .keep is pointing to
-fn populate_blob_a_without_blob(
-    _: &Arc<dyn BlobService>,
-    _: &Arc<dyn DirectoryService>,
-    path_info_service: &Arc<dyn PathInfoService>,
-) {
-    // Create a PathInfo for blob A
-    let path_info = PathInfo {
-        node: Some(proto::Node {
-            node: Some(proto::node::Node::File(FileNode {
-                name: BLOB_A_NAME.into(),
-                digest: fixtures::BLOB_A_DIGEST.clone().into(),
-                size: fixtures::BLOB_A.len() as u32,
-                executable: false,
-            })),
-        }),
-        ..Default::default()
-    };
-    path_info_service.put(path_info).expect("must succeed");
-}
-
-async fn populate_directory_complicated(
-    blob_service: &Arc<dyn BlobService>,
-    directory_service: &Arc<dyn DirectoryService>,
-    path_info_service: &Arc<dyn PathInfoService>,
-) {
-    // upload empty blob
-    let mut bw = blob_service.open_write().await;
-    assert_eq!(
-        fixtures::EMPTY_BLOB_DIGEST.to_vec(),
-        bw.close().await.expect("must succeed closing").to_vec(),
-    );
-
-    // upload inner directory
-    directory_service
-        .put(fixtures::DIRECTORY_WITH_KEEP.clone())
-        .expect("must succeed uploading");
-
-    // uplodad parent directory
-    directory_service
-        .put(fixtures::DIRECTORY_COMPLICATED.clone())
-        .expect("must succeed uploading");
-
-    // upload pathinfo
-    let path_info = PathInfo {
-        node: Some(proto::Node {
-            node: Some(proto::node::Node::Directory(DirectoryNode {
-                name: DIRECTORY_COMPLICATED_NAME.into(),
-                digest: fixtures::DIRECTORY_COMPLICATED.digest().into(),
-                size: fixtures::DIRECTORY_COMPLICATED.size(),
-            })),
-        }),
-        ..Default::default()
-    };
-    path_info_service.put(path_info).expect("must succeed");
-}
-
-/// Ensure mounting itself doesn't fail
-#[tokio::test]
-async fn mount() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-/// Ensure listing the root isn't allowed
-#[tokio::test]
-async fn root() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    {
-        // read_dir succeeds, but getting the first element will fail.
-        let mut it = fs::read_dir(tmpdir).expect("must succeed");
-
-        let err = it.next().expect("must be some").expect_err("must be err");
-        assert_eq!(std::io::ErrorKind::PermissionDenied, err.kind());
-    }
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-/// Ensure listing the root is allowed if configured explicitly
-#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
-async fn root_with_listing() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_blob_a(&blob_service, &directory_service, &path_info_service).await;
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        true, /* allow listing */
-    )
-    .expect("must succeed");
-
-    {
-        // read_dir succeeds, but getting the first element will fail.
-        let mut it = fs::read_dir(tmpdir).expect("must succeed");
-
-        let e = it.next().expect("must be some").expect("must succeed");
-
-        let metadata = e.metadata().expect("must succeed");
-        assert!(metadata.is_file());
-        assert!(metadata.permissions().readonly());
-        assert_eq!(fixtures::BLOB_A.len() as u64, metadata.len());
-    }
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-/// Ensure we can stat a file at the root
-#[tokio::test]
-async fn stat_file_at_root() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_blob_a(&blob_service, &directory_service, &path_info_service).await;
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    let p = tmpdir.path().join(BLOB_A_NAME);
-
-    // peek at the file metadata
-    let metadata = fs::metadata(p).expect("must succeed");
-
-    assert!(metadata.is_file());
-    assert!(metadata.permissions().readonly());
-    assert_eq!(fixtures::BLOB_A.len() as u64, metadata.len());
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-/// Ensure we can read a file at the root
-#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
-async fn read_file_at_root() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_blob_a(&blob_service, &directory_service, &path_info_service).await;
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    let p = tmpdir.path().join(BLOB_A_NAME);
-
-    // read the file contents
-    let data = fs::read(p).expect("must succeed");
-
-    // ensure size and contents match
-    assert_eq!(fixtures::BLOB_A.len(), data.len());
-    assert_eq!(fixtures::BLOB_A.to_vec(), data);
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-/// Ensure we can read a large file at the root
-#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
-async fn read_large_file_at_root() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_blob_b(&blob_service, &directory_service, &path_info_service).await;
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    let p = tmpdir.path().join(BLOB_B_NAME);
-    {
-        // peek at the file metadata
-        let metadata = fs::metadata(&p).expect("must succeed");
-
-        assert!(metadata.is_file());
-        assert!(metadata.permissions().readonly());
-        assert_eq!(fixtures::BLOB_B.len() as u64, metadata.len());
-    }
-
-    // read the file contents
-    let data = fs::read(p).expect("must succeed");
-
-    // ensure size and contents match
-    assert_eq!(fixtures::BLOB_B.len(), data.len());
-    assert_eq!(fixtures::BLOB_B.to_vec(), data);
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-/// Read the target of a symlink
-#[tokio::test]
-async fn symlink_readlink() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_symlink(&blob_service, &directory_service, &path_info_service);
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    let p = tmpdir.path().join(SYMLINK_NAME);
-
-    let target = fs::read_link(&p).expect("must succeed");
-    assert_eq!(BLOB_A_NAME, target.to_str().unwrap());
-
-    // peek at the file metadata, which follows symlinks.
-    // this must fail, as we didn't populate the target.
-    let e = fs::metadata(&p).expect_err("must fail");
-    assert_eq!(std::io::ErrorKind::NotFound, e.kind());
-
-    // peeking at the file metadata without following symlinks will succeed.
-    let metadata = fs::symlink_metadata(&p).expect("must succeed");
-    assert!(metadata.is_symlink());
-
-    // reading from the symlink (which follows) will fail, because the target doesn't exist.
-    let e = fs::read(p).expect_err("must fail");
-    assert_eq!(std::io::ErrorKind::NotFound, e.kind());
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-/// Read and stat a regular file through a symlink pointing to it.
-#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
-async fn read_stat_through_symlink() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_blob_a(&blob_service, &directory_service, &path_info_service).await;
-    populate_symlink(&blob_service, &directory_service, &path_info_service);
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    let p_symlink = tmpdir.path().join(SYMLINK_NAME);
-    let p_blob = tmpdir.path().join(SYMLINK_NAME);
-
-    // peek at the file metadata, which follows symlinks.
-    // this must now return the same metadata as when statting at the target directly.
-    let metadata_symlink = fs::metadata(&p_symlink).expect("must succeed");
-    let metadata_blob = fs::metadata(&p_blob).expect("must succeed");
-    assert_eq!(metadata_blob.file_type(), metadata_symlink.file_type());
-    assert_eq!(metadata_blob.len(), metadata_symlink.len());
-
-    // reading from the symlink (which follows) will return the same data as if
-    // we were reading from the file directly.
-    assert_eq!(
-        std::fs::read(p_blob).expect("must succeed"),
-        std::fs::read(p_symlink).expect("must succeed"),
-    );
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-/// Read a directory in the root, and validate some attributes.
-#[tokio::test]
-async fn read_stat_directory() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_directory_with_keep(&blob_service, &directory_service, &path_info_service).await;
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    let p = tmpdir.path().join(DIRECTORY_WITH_KEEP_NAME);
-
-    // peek at the metadata of the directory
-    let metadata = fs::metadata(p).expect("must succeed");
-    assert!(metadata.is_dir());
-    assert!(metadata.permissions().readonly());
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
-/// Read a blob inside a directory. This ensures we successfully populate directory data.
-async fn read_blob_inside_dir() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_directory_with_keep(&blob_service, &directory_service, &path_info_service).await;
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    let p = tmpdir.path().join(DIRECTORY_WITH_KEEP_NAME).join(".keep");
-
-    // peek at metadata.
-    let metadata = fs::metadata(&p).expect("must succeed");
-    assert!(metadata.is_file());
-    assert!(metadata.permissions().readonly());
-
-    // read from it
-    let data = fs::read(&p).expect("must succeed");
-    assert_eq!(fixtures::EMPTY_BLOB_CONTENTS.to_vec(), data);
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
-/// Read a blob inside a directory inside a directory. This ensures we properly
-/// populate directories as we traverse down the structure.
-async fn read_blob_deep_inside_dir() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_directory_complicated(&blob_service, &directory_service, &path_info_service).await;
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    let p = tmpdir
-        .path()
-        .join(DIRECTORY_COMPLICATED_NAME)
-        .join("keep")
-        .join(".keep");
-
-    // peek at metadata.
-    let metadata = fs::metadata(&p).expect("must succeed");
-    assert!(metadata.is_file());
-    assert!(metadata.permissions().readonly());
-
-    // read from it
-    let data = fs::read(&p).expect("must succeed");
-    assert_eq!(fixtures::EMPTY_BLOB_CONTENTS.to_vec(), data);
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-/// Ensure readdir works.
-#[tokio::test]
-async fn readdir() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_directory_complicated(&blob_service, &directory_service, &path_info_service).await;
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    let p = tmpdir.path().join(DIRECTORY_COMPLICATED_NAME);
-
-    {
-        // read_dir should succeed. Collect all elements
-        let elements: Vec<_> = fs::read_dir(p)
-            .expect("must succeed")
-            .map(|e| e.expect("must not be err"))
-            .collect();
-
-        assert_eq!(3, elements.len(), "number of elements should be 3"); // rust skips . and ..
-
-        // We explicitly look at specific positions here, because we always emit
-        // them ordered.
-
-        // ".keep", 0 byte file.
-        let e = &elements[0];
-        assert_eq!(".keep", e.file_name());
-        assert!(e.file_type().expect("must succeed").is_file());
-        assert_eq!(0, e.metadata().expect("must succeed").len());
-
-        // "aa", symlink.
-        let e = &elements[1];
-        assert_eq!("aa", e.file_name());
-        assert!(e.file_type().expect("must succeed").is_symlink());
-
-        // "keep", directory
-        let e = &elements[2];
-        assert_eq!("keep", e.file_name());
-        assert!(e.file_type().expect("must succeed").is_dir());
-    }
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-#[tokio::test]
-/// Do a readdir deeper inside a directory, without doing readdir or stat in the parent directory.
-async fn readdir_deep() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_directory_complicated(&blob_service, &directory_service, &path_info_service).await;
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    let p = tmpdir.path().join(DIRECTORY_COMPLICATED_NAME).join("keep");
-
-    {
-        // read_dir should succeed. Collect all elements
-        let elements: Vec<_> = fs::read_dir(p)
-            .expect("must succeed")
-            .map(|e| e.expect("must not be err"))
-            .collect();
-
-        assert_eq!(1, elements.len(), "number of elements should be 1"); // rust skips . and ..
-
-        // ".keep", 0 byte file.
-        let e = &elements[0];
-        assert_eq!(".keep", e.file_name());
-        assert!(e.file_type().expect("must succeed").is_file());
-        assert_eq!(0, e.metadata().expect("must succeed").len());
-    }
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-/// Check attributes match how they show up in /nix/store normally.
-#[tokio::test]
-async fn check_attributes() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_blob_a(&blob_service, &directory_service, &path_info_service).await;
-    populate_directory_with_keep(&blob_service, &directory_service, &path_info_service).await;
-    populate_symlink(&blob_service, &directory_service, &path_info_service);
-    populate_helloworld_blob(&blob_service, &directory_service, &path_info_service).await;
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    let p_file = tmpdir.path().join(BLOB_A_NAME);
-    let p_directory = tmpdir.path().join(DIRECTORY_WITH_KEEP_NAME);
-    let p_symlink = tmpdir.path().join(SYMLINK_NAME);
-    let p_executable_file = tmpdir.path().join(HELLOWORLD_BLOB_NAME);
-
-    // peek at metadata. We use symlink_metadata to ensure we don't traverse a symlink by accident.
-    let metadata_file = fs::symlink_metadata(&p_file).expect("must succeed");
-    let metadata_executable_file = fs::symlink_metadata(&p_executable_file).expect("must succeed");
-    let metadata_directory = fs::symlink_metadata(&p_directory).expect("must succeed");
-    let metadata_symlink = fs::symlink_metadata(&p_symlink).expect("must succeed");
-
-    // modes should match. We & with 0o777 to remove any higher bits.
-    assert_eq!(0o444, metadata_file.mode() & 0o777);
-    assert_eq!(0o555, metadata_executable_file.mode() & 0o777);
-    assert_eq!(0o555, metadata_directory.mode() & 0o777);
-    assert_eq!(0o444, metadata_symlink.mode() & 0o777);
-
-    // files should have the correct filesize
-    assert_eq!(fixtures::BLOB_A.len() as u64, metadata_file.len());
-    // directories should have their "size" as filesize
-    assert_eq!(
-        fixtures::DIRECTORY_WITH_KEEP.size() as u64,
-        metadata_directory.size()
-    );
-
-    for metadata in &[&metadata_file, &metadata_directory, &metadata_symlink] {
-        // uid and gid should be 0.
-        assert_eq!(0, metadata.uid());
-        assert_eq!(0, metadata.gid());
-
-        // all times should be set to the unix epoch.
-        assert_eq!(0, metadata.atime());
-        assert_eq!(0, metadata.mtime());
-        assert_eq!(0, metadata.ctime());
-        // crtime seems MacOS only
-    }
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-#[tokio::test]
-/// Ensure we allocate the same inodes for the same directory contents.
-/// $DIRECTORY_COMPLICATED_NAME/keep contains the same data as $DIRECTORY_WITH_KEEP.
-async fn compare_inodes_directories() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_directory_with_keep(&blob_service, &directory_service, &path_info_service).await;
-    populate_directory_complicated(&blob_service, &directory_service, &path_info_service).await;
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    let p_dir_with_keep = tmpdir.path().join(DIRECTORY_WITH_KEEP_NAME);
-    let p_sibling_dir = tmpdir.path().join(DIRECTORY_COMPLICATED_NAME).join("keep");
-
-    // peek at metadata.
-    assert_eq!(
-        fs::metadata(p_dir_with_keep).expect("must succeed").ino(),
-        fs::metadata(p_sibling_dir).expect("must succeed").ino()
-    );
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-/// Ensure we allocate the same inodes for the same directory contents.
-/// $DIRECTORY_COMPLICATED_NAME/keep/,keep contains the same data as $DIRECTORY_COMPLICATED_NAME/.keep
-#[tokio::test]
-async fn compare_inodes_files() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_directory_complicated(&blob_service, &directory_service, &path_info_service).await;
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    let p_keep1 = tmpdir.path().join(DIRECTORY_COMPLICATED_NAME).join(".keep");
-    let p_keep2 = tmpdir
-        .path()
-        .join(DIRECTORY_COMPLICATED_NAME)
-        .join("keep")
-        .join(".keep");
-
-    // peek at metadata.
-    assert_eq!(
-        fs::metadata(p_keep1).expect("must succeed").ino(),
-        fs::metadata(p_keep2).expect("must succeed").ino()
-    );
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-/// Ensure we allocate the same inode for symlinks pointing to the same targets.
-/// $DIRECTORY_COMPLICATED_NAME/aa points to the same target as SYMLINK_NAME2.
-#[tokio::test]
-async fn compare_inodes_symlinks() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_directory_complicated(&blob_service, &directory_service, &path_info_service).await;
-    populate_symlink2(&blob_service, &directory_service, &path_info_service);
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    let p1 = tmpdir.path().join(DIRECTORY_COMPLICATED_NAME).join("aa");
-    let p2 = tmpdir.path().join(SYMLINK_NAME2);
-
-    // peek at metadata.
-    assert_eq!(
-        fs::symlink_metadata(p1).expect("must succeed").ino(),
-        fs::symlink_metadata(p2).expect("must succeed").ino()
-    );
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-/// Check we match paths exactly.
-#[tokio::test]
-async fn read_wrong_paths_in_root() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_blob_a(&blob_service, &directory_service, &path_info_service).await;
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    // wrong name
-    assert!(!tmpdir
-        .path()
-        .join("00000000000000000000000000000000-tes")
-        .exists());
-
-    // invalid hash
-    assert!(!tmpdir
-        .path()
-        .join("0000000000000000000000000000000-test")
-        .exists());
-
-    // right name, must exist
-    assert!(tmpdir
-        .path()
-        .join("00000000000000000000000000000000-test")
-        .exists());
-
-    // now wrong name with right hash still may not exist
-    assert!(!tmpdir
-        .path()
-        .join("00000000000000000000000000000000-tes")
-        .exists());
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-/// Make sure writes are not allowed
-#[tokio::test]
-async fn disallow_writes() {
-    // https://plume.benboeckel.net/~/JustAnotherBlog/skipping-tests-in-rust
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    let p = tmpdir.path().join(BLOB_A_NAME);
-    let e = std::fs::File::create(p).expect_err("must fail");
-
-    assert_eq!(Some(libc::EROFS), e.raw_os_error());
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-#[tokio::test]
-/// Ensure we get an IO error if the directory service does not have the Directory object.
-async fn missing_directory() {
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_pathinfo_without_directory(&blob_service, &directory_service, &path_info_service);
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    let p = tmpdir.path().join(DIRECTORY_WITH_KEEP_NAME);
-
-    {
-        // `stat` on the path should succeed, because it doesn't trigger the directory request.
-        fs::metadata(&p).expect("must succeed");
-
-        // However, calling either `readdir` or `stat` on a child should fail with an IO error.
-        // It fails when trying to pull the first entry, because we don't implement opendir separately
-        fs::read_dir(&p)
-            .unwrap()
-            .next()
-            .expect("must be some")
-            .expect_err("must be err");
-
-        // rust currently sets e.kind() to Uncategorized, which isn't very
-        // helpful, so we don't look at the error more closely than that..
-        fs::metadata(p.join(".keep")).expect_err("must fail");
-    }
-
-    fuse_daemon.unmount().expect("unmount");
-}
-
-#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
-/// Ensure we get an IO error if the blob service does not have the blob
-async fn missing_blob() {
-    if !std::path::Path::new("/dev/fuse").exists() {
-        eprintln!("skipping test");
-        return;
-    }
-    let tmpdir = TempDir::new().unwrap();
-
-    let (blob_service, directory_service, path_info_service) = gen_svcs();
-    populate_blob_a_without_blob(&blob_service, &directory_service, &path_info_service);
-
-    let mut fuse_daemon = do_mount(
-        blob_service,
-        directory_service,
-        path_info_service,
-        tmpdir.path(),
-        false,
-    )
-    .expect("must succeed");
-
-    let p = tmpdir.path().join(BLOB_A_NAME);
-
-    {
-        // `stat` on the blob should succeed, because it doesn't trigger a request to the blob service.
-        fs::metadata(&p).expect("must succeed");
-
-        // However, calling read on the blob should fail.
-        // rust currently sets e.kind() to Uncategorized, which isn't very
-        // helpful, so we don't look at the error more closely than that..
-        fs::read(p).expect_err("must fail");
-    }
-
-    fuse_daemon.unmount().expect("unmount");
-}