f Use sync_all rather than libc::fsync

As it iternally does the right thing (tm): call `libc::fsync` on
non-macOS UNIXes and `libc::fcntl` with `libc::F_FULLSYNC` set on macOS
(as Apple decided to break POSIX to cheat benchmarks).

Author: tnull

lightning-persister/src/fs_store.rs

@@ -9,9 +9,6 @@ use std::path::{Path, PathBuf};
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::sync::{Arc, Mutex, RwLock};
 
-#[cfg(not(target_os = "windows"))]
-use std::os::unix::io::AsRawFd;
-
 #[cfg(target_os = "windows")]
 use {std::ffi::OsStr, std::os::windows::ffi::OsStrExt};
 
@@ -134,9 +131,7 @@ impl KVStore for FilesystemStore {
 		{
 			fs::rename(&tmp_file_path, &dest_file_path)?;
 			let dir_file = fs::OpenOptions::new().read(true).open(&parent_directory)?;
-			unsafe {
-				libc::fsync(dir_file.as_raw_fd());
-			}
+			dir_file.sync_all()?;
 			Ok(())
 		}
 
@@ -204,15 +199,13 @@ impl KVStore for FilesystemStore {
 				std::io::Error::new(std::io::ErrorKind::InvalidInput, msg)
 			})?;
 			let dir_file = fs::OpenOptions::new().read(true).open(parent_directory)?;
-			unsafe {
-				// The above call to `fs::remove_file` corresponds to POSIX `unlink`, whose changes
-				// to the inode might get cached (and hence possibly lost on crash), depending on
-				// the target platform and file system.
-				//
-				// In order to assert we permanently removed the file in question we therefore
-				// call `fsync` on the parent directory on platforms that support it,
-				libc::fsync(dir_file.as_raw_fd());
-			}
+			// The above call to `fs::remove_file` corresponds to POSIX `unlink`, whose changes
+			// to the inode might get cached (and hence possibly lost on crash), depending on
+			// the target platform and file system.
+			//
+			// In order to assert we permanently removed the file in question we therefore
+			// call `fsync` on the parent directory on platforms that support it,
+			dir_file.sync_all()?;
 		}
 
 		if dest_file_path.is_file() {