diff options
Diffstat (limited to 'tvix/castore/src/fs/mod.rs')
| -rw-r--r-- | tvix/castore/src/fs/mod.rs | 627 |
1 files changed, 627 insertions, 0 deletions
diff --git a/tvix/castore/src/fs/mod.rs b/tvix/castore/src/fs/mod.rs new file mode 100644 index 000000000000..9bd021cb09fe --- /dev/null +++ b/tvix/castore/src/fs/mod.rs @@ -0,0 +1,627 @@ +mod file_attr; +mod inode_tracker; +mod inodes; +mod root_nodes; + +#[cfg(feature = "fuse")] +pub mod fuse; + +#[cfg(feature = "virtiofs")] +pub mod virtiofs; + +use crate::proto as castorepb; +use crate::{ + blobservice::{BlobReader, BlobService}, + directoryservice::DirectoryService, + proto::{node::Node, NamedNode}, + B3Digest, +}; +use fuse_backend_rs::abi::fuse_abi::stat64; +use fuse_backend_rs::api::filesystem::{Context, FileSystem, FsOptions, ROOT_ID}; +use futures::StreamExt; +use parking_lot::RwLock; +use std::ops::Deref; +use std::{ + collections::HashMap, + io, + sync::atomic::AtomicU64, + sync::{atomic::Ordering, Arc}, + time::Duration, +}; +use tokio::{ + io::{AsyncReadExt, AsyncSeekExt}, + sync::mpsc, +}; +use tracing::{debug, info_span, instrument, warn}; + +pub use self::root_nodes::RootNodes; +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 [RootNodes]. +/// +/// 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. +/// We store a mapping from currently "explored" names in the root to their +/// inode. +/// +/// 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 directory node we +/// explore. +/// Tests for this live in the tvix-store crate. +pub struct TvixStoreFs<BS, DS, RN> { + blob_service: BS, + directory_service: DS, + root_nodes_provider: RN, + + /// Whether to (try) listing elements in the root. + list_root: bool, + + /// This maps a given basename in the root to the inode we allocated for the node. + root_nodes: RwLock<HashMap<Vec<u8>, u64>>, + + /// This keeps track of inodes and data alongside them. + inode_tracker: RwLock<InodeTracker>, + + /// This holds all open file handles + #[allow(clippy::type_complexity)] + file_handles: RwLock<HashMap<u64, Arc<tokio::sync::Mutex<Box<dyn BlobReader>>>>>, + + next_file_handle: AtomicU64, + + tokio_handle: tokio::runtime::Handle, +} + +impl<BS, DS, RN> TvixStoreFs<BS, DS, RN> +where + BS: Deref<Target = dyn BlobService> + Clone + Send, + DS: Deref<Target = dyn DirectoryService> + Clone + Send + 'static, + RN: RootNodes + Clone + 'static, +{ + pub fn new( + blob_service: BS, + directory_service: DS, + root_nodes_provider: RN, + list_root: bool, + ) -> Self { + Self { + blob_service, + directory_service, + root_nodes_provider, + + list_root, + + root_nodes: 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(), + } + } + + /// Retrieves the inode for a given root node basename, if present. + /// This obtains a read lock on self.root_nodes. + fn get_inode_for_root_name(&self, name: &[u8]) -> Option<u64> { + self.root_nodes.read().get(name).cloned() + } + + /// For a given inode, look up the given directory behind it (from + /// self.inode_tracker), and return its children. + /// The inode_tracker MUST know about this inode already, and it MUST point + /// to a [InodeData::Directory]. + /// It is ok if it's a [DirectoryInodeData::Sparse] - in that case, a lookup + /// in self.directory_service is performed, and self.inode_tracker is updated with the + /// [DirectoryInodeData::Populated]. + #[instrument(skip(self), err)] + fn get_directory_children(&self, ino: u64) -> io::Result<(B3Digest, Vec<(u64, Node)>)> { + let data = self.inode_tracker.read().get(ino).unwrap(); + match *data { + // if it's populated already, return children. + InodeData::Directory(DirectoryInodeData::Populated( + ref parent_digest, + ref children, + )) => Ok((parent_digest.clone(), children.clone())), + // if it's sparse, fetch data using directory_service, populate child nodes + // and update it in [self.inode_tracker]. + InodeData::Directory(DirectoryInodeData::Sparse(ref parent_digest, _)) => { + let directory = self + .tokio_handle + .block_on(self.tokio_handle.spawn({ + let directory_service = self.directory_service.clone(); + let parent_digest = parent_digest.to_owned(); + async move { directory_service.get(&parent_digest).await } + })) + .unwrap()? + .ok_or_else(|| { + warn!(directory.digest=%parent_digest, "directory not found"); + // If the Directory can't be found, this is a hole, bail out. + io::Error::from_raw_os_error(libc::EIO) + })?; + + // Turn the retrieved directory into a InodeData::Directory(DirectoryInodeData::Populated(..)), + // allocating inodes for the children on the way. + let children = { + let mut inode_tracker = self.inode_tracker.write(); + + let children: Vec<(u64, castorepb::node::Node)> = directory + .nodes() + .map(|child_node| { + let child_ino = inode_tracker.put((&child_node).into()); + (child_ino, child_node) + }) + .collect(); + + // replace. + inode_tracker.replace( + ino, + Arc::new(InodeData::Directory(DirectoryInodeData::Populated( + parent_digest.clone(), + children.clone(), + ))), + ); + + children + }; + + Ok((parent_digest.clone(), children)) + } + // if the parent inode was not a directory, this doesn't make sense + InodeData::Regular(..) | InodeData::Symlink(_) => { + Err(io::Error::from_raw_os_error(libc::ENOTDIR)) + } + } + } + + /// This will turn a lookup request for a name in the root to a ino and + /// [InodeData]. + /// It will peek in [self.root_nodes], and then either look it up from + /// [self.inode_tracker], + /// or otherwise fetch from [self.root_nodes], and then insert into + /// [self.inode_tracker]. + /// In the case the name can't be found, a libc::ENOENT is returned. + fn name_in_root_to_ino_and_data( + &self, + name: &std::ffi::CStr, + ) -> io::Result<(u64, Arc<InodeData>)> { + // Look up the inode for that root node. + // If there's one, [self.inode_tracker] MUST also contain the data, + // which we can then return. + if let Some(inode) = self.get_inode_for_root_name(name.to_bytes()) { + return Ok(( + inode, + self.inode_tracker + .read() + .get(inode) + .expect("must exist") + .to_owned(), + )); + } + + // We don't have it yet, look it up in [self.root_nodes]. + match self.tokio_handle.block_on({ + let root_nodes_provider = self.root_nodes_provider.clone(); + async move { root_nodes_provider.get_by_basename(name.to_bytes()).await } + }) { + // if there was an error looking up the root node, propagate up an IO error. + Err(_e) => Err(io::Error::from_raw_os_error(libc::EIO)), + // the root node doesn't exist, so the file doesn't exist. + Ok(None) => Err(io::Error::from_raw_os_error(libc::ENOENT)), + // The root node does exist + Ok(Some(root_node)) => { + // The name must match what's passed in the lookup, otherwise this is also a ENOENT. + if root_node.get_name() != name.to_bytes() { + debug!(root_node.name=?root_node.get_name(), found_node.name=%name.to_string_lossy(), "node name mismatch"); + return Err(io::Error::from_raw_os_error(libc::ENOENT)); + } + + // Let's check if someone else beat us to updating the inode tracker and + // root_nodes map. This avoids locking inode_tracker for writing. + if let Some(ino) = self.root_nodes.read().get(name.to_bytes()) { + return Ok(( + *ino, + self.inode_tracker.read().get(*ino).expect("must exist"), + )); + } + + // Only in case it doesn't, lock [self.root_nodes] and + // [self.inode_tracker] for writing. + let mut root_nodes = self.root_nodes.write(); + let mut inode_tracker = self.inode_tracker.write(); + + // insert the (sparse) inode data and register in + // self.root_nodes. + let inode_data: InodeData = (&root_node).into(); + let ino = inode_tracker.put(inode_data.clone()); + root_nodes.insert(name.to_bytes().into(), ino); + + Ok((ino, Arc::new(inode_data))) + } + } + } +} + +impl<BS, DS, RN> FileSystem for TvixStoreFs<BS, DS, RN> +where + BS: Deref<Target = dyn BlobService> + Clone + Send + 'static, + DS: Deref<Target = dyn DirectoryService> + Send + Clone + 'static, + RN: RootNodes + Clone + 'static, +{ + type Handle = u64; + type Inode = 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 => 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.root_nodes] (fetching from a [RootNode] provider 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 { + let (ino, inode_data) = self.name_in_root_to_ino_and_data(name)?; + + debug!(inode_data=?&inode_data, ino=ino, "Some"); + return 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. + let (parent_digest, children) = self.get_directory_children(parent)?; + + let span = info_span!("lookup", directory.digest = %parent_digest); + let _enter = span.enter(); + + // Search for that name in the list of children and return the FileAttrs. + + // 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 = self.inode_tracker.read().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 root_nodes_provider = self.root_nodes_provider.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 = root_nodes_provider.list().skip(offset as usize).enumerate(); + while let Some(node) = stream.next().await { + if tx.send(node).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, root_node)) = rx.blocking_recv() { + let root_node = match root_node { + Err(e) => { + warn!("failed to retrieve pathinfo: {}", e); + return Err(io::Error::from_raw_os_error(libc::EPERM)); + } + Ok(root_node) => root_node, + }; + + let name = root_node.get_name(); + // obtain the inode, or allocate a new one. + let ino = self.get_inode_for_root_name(name).unwrap_or_else(|| { + // insert the (sparse) inode data and register in + // self.root_nodes. + let ino = self.inode_tracker.write().put((&root_node).into()); + self.root_nodes.write().insert(name.into(), 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, + })?; + // If the buffer is full, add_entry will return `Ok(0)`. + if written == 0 { + break; + } + } + + return Ok(()); + } + } + + // lookup the children, or return an error if it's not a directory. + let (parent_digest, children) = self.get_directory_children(inode)?; + + let span = info_span!("lookup", directory.digest = %parent_digest); + let _enter = span.enter(); + + 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 { + #[allow(clippy::unnecessary_cast)] + // libc::S_IFDIR is u32 on Linux and u16 on MacOS + Node::Directory(_) => libc::S_IFDIR as u32, + #[allow(clippy::unnecessary_cast)] + // libc::S_IFDIR is u32 on Linux and u16 on MacOS + Node::File(_) => libc::S_IFREG as u32, + #[allow(clippy::unnecessary_cast)] + // libc::S_IFDIR is u32 on Linux and u16 on MacOS + 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; + } + } + + 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"); + 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"); + Err(io::Error::from_raw_os_error(libc::EIO)) + } + Err(e) => { + warn!(e=?e, "error opening blob"); + 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)).await; + + match resp { + Ok(pos) => { + debug_assert_eq!(offset, 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); + + // copy things from the internal buffer into buf to fill it till up until size + tokio::io::copy(&mut blob_reader.as_mut().take(size as u64), &mut buf).await?; + + 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()), + } + } +} |