From c171b63ec2db1caade13c64d8deaad2ec201bc51 Mon Sep 17 00:00:00 2001
From: Ishan Jain <contact@ishanjain.me>
Date: Tue, 9 Jul 2024 10:04:04 +0530
Subject: [PATCH] use O_DIRECT for file read operations

---
 Cargo.lock       | 1 +
 core/Cargo.toml  | 1 +
 core/io/linux.rs | 7 ++++++-
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/Cargo.lock b/Cargo.lock
index 176e381e5..cba209390 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -954,6 +954,7 @@ dependencies = [
  "criterion",
  "fallible-iterator 0.3.0",
  "io-uring",
+ "libc",
  "log",
  "mimalloc",
  "ordered-multimap",
diff --git a/core/Cargo.toml b/core/Cargo.toml
index 7777e2b03..ce6c65140 100644
--- a/core/Cargo.toml
+++ b/core/Cargo.toml
@@ -27,6 +27,7 @@ mimalloc = { version = "*", default-features = false }
 anyhow = "1.0.75"
 cfg_block = "0.1.1"
 fallible-iterator = "0.3.0"
+libc = "0.2.155"
 log = "0.4.20"
 ordered-multimap = "0.7.1"
 sieve-cache = "0.1.4"
diff --git a/core/io/linux.rs b/core/io/linux.rs
index 41a5b3242..b1750d565 100644
--- a/core/io/linux.rs
+++ b/core/io/linux.rs
@@ -2,6 +2,7 @@ use super::{Completion, File, WriteCompletion, IO};
 use anyhow::Result;
 use log::trace;
 use std::cell::RefCell;
+use std::os::unix::fs::OpenOptionsExt;
 use std::os::unix::io::AsRawFd;
 use std::rc::Rc;
 
@@ -21,7 +22,11 @@ impl LinuxIO {
 impl IO for LinuxIO {
     fn open_file(&self, path: &str) -> Result<Rc<dyn File>> {
         trace!("open_file(path = {})", path);
-        let file = std::fs::File::options().read(true).write(true).open(path)?;
+        let file = std::fs::File::options()
+            .read(true)
+            .write(true)
+            .custom_flags(libc::O_DIRECT)
+            .open(path)?;
         Ok(Rc::new(LinuxFile {
             ring: self.ring.clone(),
             file,