The file only writes partial bytes and doesn't raise any errors

[WenyXu]

Version
v1.29.1

Platform
The output of uname -a (UNIX), or version and 32 or 64-bit (Windows)

Linux 6.2.0-25-generic #25-Ubuntu SMP PREEMPT_DYNAMIC x86_64 GNU/Linux

Description
Enter your issue details here.
One way to structure the description:

tokio::fs::File only writes partial bytes and doesn't raise any errors.

We designed some chaos tests, which simulate what problems will occur when the disk is full.

fallocate -l 512K disk.img 
mkfs disk.img 
mkdir ./td
sudo mount -o loop td.img ./td
chmod a+wr ./td

I tried this code:

#[tokio::test(flavor = "multi_thread")]
async fn tokio_file_write() {
    let root_dir = "/tmp/chaos/td/test";

    let mut f = tokio::fs::File::create(root_dir).await.unwrap();
    // XKB
    let data = [96u8; 1024 * 512];
    let l = f.write(&data.to_vec()).await.unwrap();
    assert_eq!(1024 * 512, l);
}

#[tokio::test(flavor = "multi_thread")]
async fn tokio_file_write() {
    let root_dir = "/tmp/chaos/td/test";

    let mut f = tokio::fs::File::create(root_dir).await.unwrap();
    // XKB
    let data = [96u8; 1024 * 512];
    f.write_all(&data.to_vec()).await.unwrap();
}

I expected to see this happen:

I also tested with the std::fs::File, and it works as expected.

#[test]
fn std_file_write() {
    let root_dir = "/tmp/chaos/td/test";

    let mut f = std::fs::File::create(root_dir).unwrap();
    // XKB
    let data = [96u8; 1024 * 512];
    f.write_all(&data.to_vec()).unwrap();
}

Output:

called `Result::unwrap()` on an `Err` value: Os { code: 28, kind: StorageFull, message: "No space left on device" }
stack backtrace:
   0: rust_begin_unwind
             at /rustc/f3623871cfa0763c95ebd6ceafaa6dc2e44ca68f/library/std/src/panicking.rs:617:5

Instead, this happened:

The tokio::fs::File's writes only contain partial bytes and didn't raise any errors!

running 1 test
test tests::standalone_read_write::tokio_file_write ... ok

➜  td ls -lh  
total 448K
drwx------ 2 root root  16K Sep 13 08:28 lost+found
-rw-rw-r-- 1 weny weny 428K Sep 13 09:10 test

[Darksonn]

Tokio's file must be flushed.

[WenyXu]

Tokio's file must be flushed.

Cool,flush throws a NoSpace error. But why after calling the sync_all didn't throw any errors?
Are there any differences between the sync_all and flush?

[Darksonn]

Yes, sync_all and flush are completely different. The flush method ensures that things not yet written by Rust are written to the OS. The sync_all method ensures that everything written to the OS is flushed to disk.

Arguably the sync_all method should do a flush first.