mod file_attr;
mod inode_tracker;
mod inodes;
#[cfg(feature = "fuse")]
pub mod fuse;
#[cfg(feature = "virtiofs")]
pub mod virtiofs;
#[cfg(test)]
mod tests;
use crate::pathinfoservice::PathInfoService;
use fuse_backend_rs::abi::fuse_abi::stat64;
use fuse_backend_rs::api::filesystem::{Context, FileSystem, FsOptions, ROOT_ID};
use futures::StreamExt;
use nix_compat::store_path::StorePath;
use parking_lot::RwLock;
use std::{
collections::HashMap,
io,
str::FromStr,
sync::atomic::AtomicU64,
sync::{atomic::Ordering, Arc},
time::Duration,
};
use tokio::{
io::{AsyncBufReadExt, AsyncSeekExt},
sync::mpsc,
};
use tracing::{debug, info_span, warn};
use tvix_castore::{
blobservice::{BlobReader, BlobService},
directoryservice::DirectoryService,
proto::{node::Node, NamedNode},
B3Digest, Error,
};
use self::{
file_attr::{gen_file_attr, ROOT_FILE_ATTR},
inode_tracker::InodeTracker,
inodes::{DirectoryInodeData, InodeData},
};
/// 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 TvixStoreFs {
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 TvixStoreFs {
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.
let path_info_service = self.path_info_service.clone();
let task = self
.tokio_handle
.spawn(async move { path_info_service.get(store_path.digest).await });
match self.tokio_handle.block_on(task).unwrap()? {
// 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> {
let directory_service = self.directory_service.clone();
let directory_digest_clone = directory_digest.clone();
let task = self
.tokio_handle
.spawn(async move { directory_service.get(&directory_digest_clone).await });
match self.tokio_handle.block_on(task).unwrap() {
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 TvixStoreFs {
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<(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 {
let path_info_service = self.path_info_service.clone();
let (tx, mut rx) = mpsc::channel(16);
// This task will run in the background immediately and will exit
// after the stream ends or if we no longer want any more entries.
self.tokio_handle.spawn(async move {
let mut stream = path_info_service.list().skip(offset as usize).enumerate();
while let Some(path_info) = stream.next().await {
if tx.send(path_info).await.is_err() {
// If we get a send error, it means the sync code
// doesn't want any more entries.
break;
}
}
});
while let Some((i, path_info)) = rx.blocking_recv() {
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 as u32,
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 as u32,
Node::File(_) => libc::S_IFREG as u32,
Node::Symlink(_) => libc::S_IFLNK as u32,
},
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()),
}
}
}
