fix warnings

pageserver/src/virtual_file.rs

@@ -16,10 +16,9 @@ use camino::{Utf8Path, Utf8PathBuf};
 use once_cell::sync::OnceCell;
 use std::fs::{self, File};
 use std::io::{Error, ErrorKind, Seek, SeekFrom};
-use std::os::fd::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, OwnedFd, RawFd};
+use std::os::fd::{AsRawFd, FromRawFd, OwnedFd, RawFd};
 use std::os::unix::fs::FileExt;
 use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
-use std::sync::Arc;
 use tokio::sync::{RwLock, RwLockReadGuard, RwLockWriteGuard};
 use tokio::time::Instant;
 use utils::fs_ext;
@@ -271,6 +270,10 @@ macro_rules! observe_duration {
 
 macro_rules! with_file {
     ($this:expr, $op:expr, | $ident:ident | $($body:tt)*) => {{
+        let $ident = $this.lock_file().await?;
+        observe_duration!($op, $($body)*)
+    }};
+    ($this:expr, $op:expr, | mut $ident:ident | $($body:tt)*) => {{
         let mut $ident = $this.lock_file().await?;
         observe_duration!($op, $($body)*)
     }};
@@ -550,8 +553,8 @@ impl VirtualFile {
                 self.pos = offset;
             }
             SeekFrom::End(offset) => {
-                self.pos = with_file!(self, StorageIoOperation::Seek, |file_guard| file_guard
-                    .with_std_file(|std_file| std_file.seek(SeekFrom::End(offset))))?
+                self.pos = with_file!(self, StorageIoOperation::Seek, |mut file_guard| file_guard
+                    .with_std_file_mut(|std_file| std_file.seek(SeekFrom::End(offset))))?
             }
             SeekFrom::Current(offset) => {
                 let pos = self.pos as i128 + offset as i128;
@@ -702,8 +705,18 @@ impl AsRef<OwnedFd> for FileGuard {
 
 impl FileGuard {
     // TODO: switch to tokio-epoll-uring native operations.
-    #[deprecated]
-    fn with_std_file<F, R>(&mut self, with: F) -> R
+    fn with_std_file<F, R>(&self, with: F) -> R
+    where
+        F: FnOnce(&File) -> R,
+    {
+        // SAFETY:
+        // - lifetime of the fd: `file` doesn't outlive the OwnedFd stored in `self`.
+        // - `&` usage below: `self` is `&`, hence Rust typesystem guarantees there are is no `&mut`
+        let file = unsafe { File::from_raw_fd(self.as_ref().as_raw_fd()) };
+        with(&file)
+    }
+    // TODO: switch to tokio-epoll-uring native operations.
+    fn with_std_file_mut<F, R>(&mut self, with: F) -> R
     where
         F: FnOnce(&mut File) -> R,
     {