From f4ea23b72ccb22c471402e9d332015483380affb Mon Sep 17 00:00:00 2001
From: LI Qing <geding.lq@antgroup.com>
Date: Thu, 16 May 2024 15:04:42 +0800
Subject: [PATCH] Revise the pages() method in the page cache to only return a
 reference

---
 kernel/aster-nix/src/fs/exfat/inode.rs      | 14 ++++++--------
 kernel/aster-nix/src/fs/ext2/inode.rs       |  2 +-
 kernel/aster-nix/src/fs/ramfs/fs.rs         |  2 +-
 kernel/aster-nix/src/fs/utils/page_cache.rs |  4 ++--
 4 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/kernel/aster-nix/src/fs/exfat/inode.rs b/kernel/aster-nix/src/fs/exfat/inode.rs
index d45dc6b33..f75c90058 100644
--- a/kernel/aster-nix/src/fs/exfat/inode.rs
+++ b/kernel/aster-nix/src/fs/exfat/inode.rs
@@ -235,7 +235,7 @@ impl ExfatInodeInner {
             return Ok((0, 0));
         }
 
-        let iterator = ExfatDentryIterator::new(self.page_cache.pages(), 0, Some(self.size))?;
+        let iterator = ExfatDentryIterator::new(self.page_cache.pages().dup(), 0, Some(self.size))?;
         let mut sub_inodes = 0;
         let mut sub_dirs = 0;
         for dentry_result in iterator {
@@ -301,10 +301,8 @@ impl ExfatInodeInner {
 
         // Need to read the latest dentry set from parent inode.
 
-        let mut dentry_set = ExfatDentrySet::read_from(
-            page_cache.dup().unwrap(),
-            self.dentry_entry as usize * DENTRY_SIZE,
-        )?;
+        let mut dentry_set =
+            ExfatDentrySet::read_from(page_cache.dup(), self.dentry_entry as usize * DENTRY_SIZE)?;
 
         let mut file_dentry = dentry_set.get_file_dentry();
         let mut stream_dentry = dentry_set.get_stream_dentry();
@@ -366,7 +364,7 @@ impl ExfatInodeInner {
         let fs = self.fs();
         let cluster_size = fs.cluster_size();
 
-        let mut iter = ExfatDentryIterator::new(self.page_cache.pages(), offset, None)?;
+        let mut iter = ExfatDentryIterator::new(self.page_cache.pages().dup(), offset, None)?;
 
         let mut dir_read = 0;
         let mut current_off = offset;
@@ -809,7 +807,7 @@ impl ExfatInode {
         let inner = self.inner.upread();
 
         let dentry_iterator =
-            ExfatDentryIterator::new(inner.page_cache.pages(), 0, Some(inner.size))?;
+            ExfatDentryIterator::new(inner.page_cache.pages().dup(), 0, Some(inner.size))?;
 
         let mut contiguous_unused = 0;
         let mut entry_id = 0;
@@ -1197,7 +1195,7 @@ impl Inode for ExfatInode {
     }
 
     fn page_cache(&self) -> Option<Vmo<Full>> {
-        Some(self.inner.read().page_cache.pages())
+        Some(self.inner.read().page_cache.pages().dup())
     }
 
     fn read_at(&self, offset: usize, buf: &mut [u8]) -> Result<usize> {
diff --git a/kernel/aster-nix/src/fs/ext2/inode.rs b/kernel/aster-nix/src/fs/ext2/inode.rs
index ae10cb721..7fcba9859 100644
--- a/kernel/aster-nix/src/fs/ext2/inode.rs
+++ b/kernel/aster-nix/src/fs/ext2/inode.rs
@@ -67,7 +67,7 @@ impl Inode {
     }
 
     pub fn page_cache(&self) -> Vmo<Full> {
-        self.inner.read().page_cache.pages()
+        self.inner.read().page_cache.pages().dup()
     }
 
     pub fn create(
diff --git a/kernel/aster-nix/src/fs/ramfs/fs.rs b/kernel/aster-nix/src/fs/ramfs/fs.rs
index e8651c72d..522a5968d 100644
--- a/kernel/aster-nix/src/fs/ramfs/fs.rs
+++ b/kernel/aster-nix/src/fs/ramfs/fs.rs
@@ -458,7 +458,7 @@ impl Inode for RamInode {
             .read()
             .inner
             .as_file()
-            .map(|page_cache| page_cache.pages())
+            .map(|page_cache| page_cache.pages().dup())
     }
 
     fn read_at(&self, offset: usize, buf: &mut [u8]) -> Result<usize> {
diff --git a/kernel/aster-nix/src/fs/utils/page_cache.rs b/kernel/aster-nix/src/fs/utils/page_cache.rs
index 4e8fef4c2..4352561e7 100644
--- a/kernel/aster-nix/src/fs/utils/page_cache.rs
+++ b/kernel/aster-nix/src/fs/utils/page_cache.rs
@@ -44,8 +44,8 @@ impl PageCache {
     /// Returns the Vmo object.
     // TODO: The capability is too high，restrict it to eliminate the possibility of misuse.
     //       For example, the `resize` api should be forbidded.
-    pub fn pages(&self) -> Vmo<Full> {
-        self.pages.dup()
+    pub fn pages(&self) -> &Vmo<Full> {
+        &self.pages
     }
 
     /// Evict the data within a specified range from the page cache and persist