From 12d338dd9ba7cfba536e7fd6bf3e713ff72a6f10 Mon Sep 17 00:00:00 2001
From: LI Qing <geding.lq@antgroup.com>
Date: Wed, 31 Jan 2024 15:43:32 +0900
Subject: [PATCH] Replace `VmFrame::zero` with `VmWriter::fill`

---
 framework/aster-frame/src/vm/frame.rs        | 33 ++++++++++----------
 framework/aster-frame/src/vm/options.rs      |  8 +++--
 services/libs/aster-std/src/fs/ext2/inode.rs |  2 +-
 services/libs/aster-std/src/fs/ramfs/fs.rs   |  2 +-
 4 files changed, 23 insertions(+), 22 deletions(-)

diff --git a/framework/aster-frame/src/vm/frame.rs b/framework/aster-frame/src/vm/frame.rs
index abd5bcebd..6dc7147c0 100644
--- a/framework/aster-frame/src/vm/frame.rs
+++ b/framework/aster-frame/src/vm/frame.rs
@@ -6,6 +6,7 @@ use core::{
     marker::PhantomData,
     ops::{BitAnd, BitOr, Not, Range},
 };
+use pod::Pod;
 
 use crate::{config::PAGE_SIZE, prelude::*, Error};
 
@@ -57,11 +58,6 @@ impl VmFrameVec {
         Ok(())
     }
 
-    /// zero all internal vm frames
-    pub fn zero(&self) {
-        self.0.iter().for_each(|vm_frame| vm_frame.zero())
-    }
-
     /// Truncate some frames.
     ///
     /// If `new_len >= self.len()`, then this method has no effect.
@@ -228,12 +224,6 @@ impl VmFrame {
         (self.frame_index() + 1) * PAGE_SIZE
     }
 
-    /// Fills the frame with zero.
-    pub fn zero(&self) {
-        // Safety: The range of memory is valid for writes of one page data.
-        unsafe { core::ptr::write_bytes(self.as_mut_ptr(), 0, PAGE_SIZE) }
-    }
-
     fn need_dealloc(&self) -> bool {
         (*self.frame_index & VmFrameFlags::NEED_DEALLOC.bits()) != 0
     }
@@ -418,12 +408,6 @@ impl VmSegment {
         self.nframes() * PAGE_SIZE
     }
 
-    /// Fills the page frames with zero.
-    pub fn zero(&self) {
-        // Safety: The range of memory is valid for writes of `self.nbytes()` data.
-        unsafe { core::ptr::write_bytes(self.as_mut_ptr(), 0, self.nbytes()) }
-    }
-
     fn need_dealloc(&self) -> bool {
         (self.inner.start_frame_index & VmFrameFlags::NEED_DEALLOC.bits()) != 0
     }
@@ -700,6 +684,21 @@ impl<'a> VmWriter<'a> {
         }
         copy_len
     }
+
+    /// Fills the available space by repeating `value`.
+    ///
+    /// # Panic
+    ///
+    /// The size of the available space must be a multiple of the size of `value`.
+    /// Otherwise, the method would panic.
+    pub fn fill<T: Pod>(&mut self, value: T) {
+        assert!(self.avail() / value.as_bytes().len() > 0);
+        assert!(self.avail() % value.as_bytes().len() == 0);
+
+        while self.avail() > 0 {
+            self.write(&mut value.as_bytes().into());
+        }
+    }
 }
 
 impl<'a> From<&'a mut [u8]> for VmWriter<'a> {
diff --git a/framework/aster-frame/src/vm/options.rs b/framework/aster-frame/src/vm/options.rs
index 67c5c9986..f88e71350 100644
--- a/framework/aster-frame/src/vm/options.rs
+++ b/framework/aster-frame/src/vm/options.rs
@@ -59,7 +59,9 @@ impl VmAllocOptions {
             VmFrameVec(frame_list)
         };
         if !self.uninit {
-            frames.zero();
+            for frame in frames.iter() {
+                frame.writer().fill(0);
+            }
         }
 
         Ok(frames)
@@ -73,7 +75,7 @@ impl VmAllocOptions {
 
         let frame = frame_allocator::alloc_single(self.flags()).ok_or(Error::NoMemory)?;
         if !self.uninit {
-            frame.zero();
+            frame.writer().fill(0);
         }
 
         Ok(frame)
@@ -90,7 +92,7 @@ impl VmAllocOptions {
         let segment =
             frame_allocator::alloc_contiguous(self.nframes, self.flags()).ok_or(Error::NoMemory)?;
         if !self.uninit {
-            segment.zero();
+            segment.writer().fill(0);
         }
 
         Ok(segment)
diff --git a/services/libs/aster-std/src/fs/ext2/inode.rs b/services/libs/aster-std/src/fs/ext2/inode.rs
index e5a638476..9ce7f1b57 100644
--- a/services/libs/aster-std/src/fs/ext2/inode.rs
+++ b/services/libs/aster-std/src/fs/ext2/inode.rs
@@ -845,7 +845,7 @@ impl InodeImpl_ {
 
         debug_assert!(field::DIRECT.contains(&(bid as usize)));
         if self.blocks_hole_desc.is_hole(bid as usize) {
-            block.zero();
+            block.writer().fill(0);
             return Ok(());
         }
         let device_bid = Bid::new(self.desc.data[bid as usize] as _);
diff --git a/services/libs/aster-std/src/fs/ramfs/fs.rs b/services/libs/aster-std/src/fs/ramfs/fs.rs
index 238f6e319..f3c2df22a 100644
--- a/services/libs/aster-std/src/fs/ramfs/fs.rs
+++ b/services/libs/aster-std/src/fs/ramfs/fs.rs
@@ -414,7 +414,7 @@ impl RamInode {
 impl PageCacheBackend for RamInode {
     fn read_page(&self, _idx: usize, frame: &VmFrame) -> Result<()> {
         // Initially, any block/page in a RamFs inode contains all zeros
-        frame.zero();
+        frame.writer().fill(0);
         Ok(())
     }