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feat(trickfs): trickfs now can signal ENOSPC
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So far, this is the fs-wide flag that when turned on will reject all
writes (and even fsync) returning the ENOSPC errors.
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@pepyakin
pepyakin committed Jan 30, 2025
1 parent 78fe6f0 commit 2d5ddcf
Showing 1 changed file with 105 additions and 16 deletions.
121 changes: 105 additions & 16 deletions trickfs/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@ use std::{
ffi::{OsStr, OsString},
fmt,
path::Path,
sync::LazyLock,
sync::{atomic::AtomicBool, Arc, LazyLock, Mutex},
time::{Duration, UNIX_EPOCH},
u64,
};
Expand Down Expand Up @@ -302,24 +302,33 @@ pub struct Trick {
/// Note that inodes are 1-based and this vector is 0-based.
inodes: Vec<InodeData>,
freelist: Vec<Inode>,
trigger_enospc: Arc<AtomicBool>,
}

impl Trick {
pub fn new() -> Self {
fn new() -> (Self, TrickHandle) {
let trigger_enospc = Arc::new(AtomicBool::new(false));

let tree = Tree::new();
let inodes = Vec::new();
let freelist = Vec::new();
let mut fs = Trick {
tree,
inodes,
freelist,
trigger_enospc: trigger_enospc.clone(),
};
// Initialize the root directory. Parent of the ROOT is ROOT.
fs.register_inode(InodeData::new_dir(Inode::ROOT));
fs.tree
.ino_to_container
.insert(Inode::ROOT, Container::new());
fs

let handle = TrickHandle {
bg_sess: None.into(),
trigger_enospc,
};
(fs, handle)
}

fn lookup_inode(&self, ino: Inode) -> Option<&InodeData> {
Expand Down Expand Up @@ -474,6 +483,13 @@ impl fuser::Filesystem for Trick {
) {
// we don't really care about these parameters.
let _ = (mode, umask, flags);
if self
.trigger_enospc
.load(std::sync::atomic::Ordering::Relaxed)
{
reply.error(libc::ENOSPC);
return;
}
let Some(parent_container) = self.tree.ino_to_container.get(&Inode(parent)) else {
log::trace!("parent inode doesn't exist");
reply.error(libc::ENOENT);
Expand Down Expand Up @@ -564,6 +580,9 @@ impl fuser::Filesystem for Trick {
reply: fuser::ReplyWrite,
) {
let _ = (fh, flags, write_flags, lock_owner);
let trigger_enospc = self
.trigger_enospc
.load(std::sync::atomic::Ordering::Relaxed);
let Some(inode_data) = self.lookup_inode_mut(Inode(ino)) else {
reply.error(libc::ENOENT);
return;
Expand All @@ -576,7 +595,12 @@ impl fuser::Filesystem for Trick {
reply.error(libc::EFBIG);
return;
}
// Extension: if the file size is less than the new size, we should extend the file.
if inode_data.size() < new_file_sz as u64 {
if trigger_enospc {
reply.error(libc::ENOSPC);
return;
}
inode_data.set_size(new_file_sz as u64);
}
inode_data.content_mut()[offset..offset + len].copy_from_slice(data);
Expand All @@ -593,6 +617,13 @@ impl fuser::Filesystem for Trick {
reply: fuser::ReplyEntry,
) {
let _ = (mode, umask);
if self
.trigger_enospc
.load(std::sync::atomic::Ordering::Relaxed)
{
reply.error(libc::ENOSPC);
return;
}
let Some(inode_data) = self.lookup_inode_mut(Inode(parent)) else {
reply.error(libc::ENOENT);
return;
Expand Down Expand Up @@ -753,14 +784,21 @@ impl fuser::Filesystem for Trick {
reply: fuser::ReplyEmpty,
) {
let _ = (fh, mode);
let trigger_enospc = self
.trigger_enospc
.load(std::sync::atomic::Ordering::Relaxed);
let Some(inode_data) = self.lookup_inode_mut(Inode(ino)) else {
reply.error(libc::ENOENT);
return;
};
// fallocate should preallocate stuff. We here just gon pretend that we are preallocating.
// we should set the length though.
// Here we should extend the file if the offset + length is greater than the current file.
let new_size = u64::try_from(offset).unwrap() + u64::try_from(length).unwrap();
if inode_data.size() < new_size {
if trigger_enospc {
reply.error(libc::ENOSPC);
return;
}
inode_data.set_size(new_size);
}
reply.ok();
Expand All @@ -776,6 +814,13 @@ impl fuser::Filesystem for Trick {
) {
// fsync doesn't do anything since we are working in-memory, so just return OK.
let _ = (ino, fh, datasync);
if self
.trigger_enospc
.load(std::sync::atomic::Ordering::Relaxed)
{
reply.error(libc::ENOSPC);
return;
}
reply.ok();
}

Expand All @@ -789,6 +834,13 @@ impl fuser::Filesystem for Trick {
) {
// just like fsync, fsyncdir doesn't do anything.
let _ = (req, ino, fh, datasync);
if self
.trigger_enospc
.load(std::sync::atomic::Ordering::Relaxed)
{
reply.error(libc::ENOSPC);
return;
}
reply.ok();
}
}
Expand All @@ -798,13 +850,21 @@ fn has_odirect(flags: i32) -> bool {
}

pub struct TrickHandle {
bg_sess: fuser::BackgroundSession,
bg_sess: Mutex<Option<fuser::BackgroundSession>>,
trigger_enospc: Arc<AtomicBool>,
}

impl TrickHandle {
/// Sets whether the file system should return ENOSPC on the subsequent write operations.
pub fn set_trigger_enospc(&self, on: bool) {
self.trigger_enospc
.store(on, std::sync::atomic::Ordering::Relaxed);
}

pub fn unmount_and_join(self) {
self.bg_sess.join();
if let Some(bg_sess) = self.bg_sess.lock().unwrap().take() {
bg_sess.join();
}
}
}

Expand All @@ -818,9 +878,9 @@ pub fn spawn_trick<P: AsRef<Path>>(mountpoint: P) -> std::io::Result<TrickHandle
MountOption::AutoUnmount,
MountOption::FSName("trick".to_string()),
];
let fs = Trick::new();
let bg_sess = fuser::spawn_mount2(fs, &mountpoint, options)?;
Ok(TrickHandle { bg_sess })
let (fs, mut handle) = Trick::new();
handle.bg_sess = Some(fuser::spawn_mount2(fs, &mountpoint, options)?).into();
Ok(handle)
}

#[cfg(test)]
Expand Down Expand Up @@ -848,7 +908,7 @@ mod tests {
init_log();
let mountpoint = tempfile::tempdir().unwrap();
let options = &[MountOption::RO, MountOption::FSName("trick".to_string())];
let fs = Trick::new();
let (fs, _handle) = Trick::new();
let mount_handle = fuser::spawn_mount2(fs, &mountpoint, options).unwrap();
drop(mount_handle);
}
Expand All @@ -859,7 +919,7 @@ mod tests {
init_log();
let mountpoint = tempfile::tempdir().unwrap();
let options = &[MountOption::RW, MountOption::FSName("trick".to_string())];
let fs = Trick::new();
let (fs, _handle) = Trick::new();
let mount_handle = fuser::spawn_mount2(fs, &mountpoint, options).unwrap();
let filename = mountpoint.path().join("file");
let file = fs::File::create(&filename).unwrap();
Expand All @@ -872,7 +932,7 @@ mod tests {
init_log();
let mountpoint = tempfile::tempdir().unwrap();
let options = &[MountOption::RW, MountOption::FSName("trick".to_string())];
let fs = Trick::new();
let (fs, _handle) = Trick::new();
let mount_handle = fuser::spawn_mount2(fs, &mountpoint, options).unwrap();
let filename = mountpoint.path().join("file");
let file = fs::File::create(&filename).unwrap();
Expand All @@ -891,7 +951,7 @@ mod tests {
MountOption::AutoUnmount,
MountOption::FSName("trick".to_string()),
];
let fs = Trick::new();
let (fs, _handle) = Trick::new();
let mount_handle = fuser::spawn_mount2(fs, &mountpoint, options).unwrap();
let filename = mountpoint.path().join("file");
let mut file = fs::File::options()
Expand Down Expand Up @@ -924,7 +984,7 @@ mod tests {
MountOption::AutoUnmount,
MountOption::FSName("trick".to_string()),
];
let fs = Trick::new();
let (fs, _handle) = Trick::new();
let mount_handle = fuser::spawn_mount2(fs, &mountpoint, options).unwrap();
let mut files = Vec::new();
for i in 0..100 {
Expand Down Expand Up @@ -955,7 +1015,7 @@ mod tests {
MountOption::AutoUnmount,
MountOption::FSName("trick".to_string()),
];
let fs = Trick::new();
let (fs, _handle) = Trick::new();
let mount_handle = fuser::spawn_mount2(fs, &mountpoint, options).unwrap();

// Create a file
Expand All @@ -977,7 +1037,7 @@ mod tests {
MountOption::AutoUnmount,
MountOption::FSName("trick".to_string()),
];
let fs = Trick::new();
let (fs, _handle) = Trick::new();
let mount_handle = fuser::spawn_mount2(fs, &mountpoint, options).unwrap();

let filename = mountpoint.path().join("file");
Expand Down Expand Up @@ -1009,4 +1069,33 @@ mod tests {
drop(file);
drop(mount_handle);
}

#[test]
fn out_of_space() {
init_log();
let mountpoint = tempfile::tempdir().unwrap();
let options = &[
MountOption::RW,
MountOption::AutoUnmount,
MountOption::FSName("trick".to_string()),
];
let (fs, handle) = Trick::new();
let mount_handle = fuser::spawn_mount2(fs, &mountpoint, options).unwrap();

let filename = mountpoint.path().join("file");
let mut file = fs::File::options()
.create_new(true)
.write(true)
.open(&filename)
.unwrap();

let test_data = b"hello world";
handle.set_trigger_enospc(true);
let _ = file.write_all(test_data).unwrap_err();
handle.set_trigger_enospc(false);
let _ = file.write_all(test_data).unwrap();

drop(file);
drop(mount_handle);
}
}

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