Kernel: Convert read_block method to get a reference instead of pointer

BlockBasedFileSystem::read_block method should get a reference of
a UserOrKernelBuffer.

If we need to force caching a block, we will call other method to do so.

1 files changed, 16 insertions, 1 deletions

diff --git a/Kernel/FileSystem/BlockBasedFileSystem.h b/Kernel/FileSystem/BlockBasedFileSystem.h
index fcf096aec3..827d7ca927 100644
--- a/Kernel/FileSystem/BlockBasedFileSystem.h
+++ b/Kernel/FileSystem/BlockBasedFileSystem.h
@@ -27,10 +27,22 @@
 #pragma once
 
 #include <Kernel/FileSystem/FileBackedFileSystem.h>
+#include <Kernel/KResult.h>
 
 namespace Kernel {
 
+class DiskCache;
 class BlockBasedFS : public FileBackedFS {
+    friend class DiskCache;
+
+private:
+    struct CacheEntry {
+        IntrusiveListNode list_node;
+        u32 block_index { 0 };
+        u8* data { nullptr };
+        bool has_data { false };
+    };
+
 public:
     virtual ~BlockBasedFS() override;
 
@@ -42,7 +54,10 @@ public:
 protected:
     explicit BlockBasedFS(FileDescription&);
 
-    int read_block(unsigned index, UserOrKernelBuffer* buffer, size_t count, size_t offset = 0, bool allow_cache = true) const;
+    int read_block(unsigned index, UserOrKernelBuffer& buffer, size_t count, size_t offset = 0, bool allow_cache = true) const;
+    bool force_cache_block(unsigned index) const;
+    KResultOr<CacheEntry> cache_block(unsigned index) const;
+
     int read_blocks(unsigned index, unsigned count, UserOrKernelBuffer& buffer, bool allow_cache = true) const;
 
     bool raw_read(unsigned index, UserOrKernelBuffer& buffer);