From 1ed08f62d34ac3d14d238c72bb7dea612a0c5d1a Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Mon, 6 Nov 2023 10:44:37 +0200
Subject: [PATCH] Kernel: TmpInode blocks are on demand allocated

---
 kernel/include/kernel/FS/TmpFS/Inode.h |  3 ++-
 kernel/kernel/FS/TmpFS/Inode.cpp       | 23 ++++++++++++-----------
 2 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/kernel/include/kernel/FS/TmpFS/Inode.h b/kernel/include/kernel/FS/TmpFS/Inode.h
index b0fd593ac..4a4da99f8 100644
--- a/kernel/include/kernel/FS/TmpFS/Inode.h
+++ b/kernel/include/kernel/FS/TmpFS/Inode.h
@@ -1,6 +1,7 @@
 #pragma once
 
 #include <BAN/Iteration.h>
+#include <BAN/Optional.h>
 #include <kernel/FS/Inode.h>
 #include <kernel/FS/TmpFS/Definitions.h>
 
@@ -35,7 +36,7 @@ namespace Kernel
 		void sync();
 		void free_all_blocks();
 
-		size_t block_index(size_t data_block_index);
+		BAN::Optional<size_t> block_index(size_t data_block_index);
 		BAN::ErrorOr<size_t> block_index_with_allocation(size_t data_block_index);
 
 	protected:
diff --git a/kernel/kernel/FS/TmpFS/Inode.cpp b/kernel/kernel/FS/TmpFS/Inode.cpp
index b0820d81d..a97dd1b3a 100644
--- a/kernel/kernel/FS/TmpFS/Inode.cpp
+++ b/kernel/kernel/FS/TmpFS/Inode.cpp
@@ -77,11 +77,12 @@ namespace Kernel
 			ASSERT(block == 0);
 	}
 
-	size_t TmpInode::block_index(size_t data_block_index)
+	BAN::Optional<size_t> TmpInode::block_index(size_t data_block_index)
 	{
 		ASSERT(data_block_index < TmpInodeInfo::direct_block_count);
-		ASSERT(m_inode_info.block[data_block_index]);
-		return m_inode_info.block[data_block_index];
+		if (m_inode_info.block[data_block_index])
+			return m_inode_info.block[data_block_index];
+		return {};
 	}
 
 	BAN::ErrorOr<size_t> TmpInode::block_index_with_allocation(size_t data_block_index)
@@ -146,11 +147,14 @@ namespace Kernel
 			const size_t data_block_index = (read_done + offset) / blksize();
 			const size_t block_offset     = (read_done + offset) % blksize();
 
-			const size_t block_index = this->block_index(data_block_index);
+			const auto block_index = this->block_index(data_block_index);
 
 			const size_t bytes = BAN::Math::min<size_t>(bytes_to_read - read_done, blksize() - block_offset);
 
-			m_fs.read_block(block_index, block_buffer.span());
+			if (block_index.has_value())
+				m_fs.read_block(block_index.value(), block_buffer.span());
+			else
+				memset(block_buffer.data(), 0x00, block_buffer.size());
 
 			memcpy(buffer.data() + read_done, block_buffer.data() + block_offset, bytes);
 
@@ -178,7 +182,7 @@ namespace Kernel
 			const size_t data_block_index = (write_done + offset) / blksize();
 			const size_t block_offset     = (write_done + offset) % blksize();
 
-			const size_t block_index = this->block_index(data_block_index);
+			const size_t block_index = TRY(block_index_with_allocation(data_block_index));
 
 			const size_t bytes = BAN::Math::min<size_t>(bytes_to_write - write_done, blksize() - block_offset);
 
@@ -196,9 +200,6 @@ namespace Kernel
 
 	BAN::ErrorOr<void> TmpFileInode::truncate_impl(size_t new_size)
 	{
-		size_t start_block = size() / blksize() * blksize();
-		for (size_t off = start_block; off < new_size; off += blksize())
-			TRY(block_index_with_allocation(off / blksize()));
 		m_inode_info.size = new_size;
 		return {};
 	}
@@ -349,8 +350,8 @@ namespace Kernel
 		size_t full_offset = 0;
 		while (full_offset < (size_t)size())
 		{
-			size_t data_block_index = full_offset / blksize();
-			size_t block_index = this->block_index(data_block_index);
+			const size_t data_block_index = full_offset / blksize();
+			const size_t block_index = this->block_index(data_block_index).value();
 
 			// FIXME: implement fast heap pages?
 			BAN::Vector<uint8_t> buffer;