Doc fix and fix double subtraction of offset

Author: Daksh14

tokio/src/fs/read.rs

@@ -30,6 +30,16 @@ use std::{io, path::Path};
 ///
 /// [`ErrorKind::Interrupted`]: std::io::ErrorKind::Interrupted
 ///
+/// # io_uring support
+///
+/// On Linux, you can also use io_uring for executing system calls. To enable
+/// io_uring, you need to specify the --cfg tokio_unstable flag at compile time,
+/// enable the io-uring cargo feature, and set the Builder::enable_io_uring
+/// runtime option.
+///
+/// Support for io_uring is currently experimental, so its behavior may change
+/// or it may be removed in future versions.
+///
 /// # Examples
 ///
 /// ```no_run

tokio/src/fs/read_uring.rs

@@ -27,7 +27,6 @@ pub(crate) async fn read_uring(path: &Path) -> io::Result<Vec<u8>> {
         .expect("unexpected in-flight operation detected")
         .into();
 
-    // extra single capacity for the whole size to fit without any reallocation
     let mut buf = Vec::new();
 
     if let Some(size_hint) = size_hint {
@@ -71,7 +70,6 @@ async fn read_to_end_uring(
 
             buf = r_buf;
             fd = r_fd;
-            offset += size_read as u64;
         }
 
         // buf is full, need more capacity
@@ -83,7 +81,7 @@ async fn read_to_end_uring(
         let buf_len = usize::min(buf.spare_capacity_mut().len(), MAX_READ_SIZE);
 
         // buf_len cannot be greater than u32::MAX because MAX_READ_SIZE
-        // is u32::MAX
+        // is less than u32::MAX
         let read_len = buf_len as u32;
 
         // read into spare capacity