Kernel: Handle OOM in DiskCache when mounting Ext2 filesystems

Create the disk cache up front, so we can verify it succeeds.
Make the KBuffer allocation fail-able, so we can properly handle
failure when the user asks up to mount a Ext2 filesystem under
OOM conditions.

1 files changed, 6 insertions, 0 deletions

diff --git a/Kernel/FileSystem/Ext2FileSystem.cpp b/Kernel/FileSystem/Ext2FileSystem.cpp
index 579f5e2f29..2bd8ddb7ce 100644
--- a/Kernel/FileSystem/Ext2FileSystem.cpp
+++ b/Kernel/FileSystem/Ext2FileSystem.cpp
@@ -89,6 +89,7 @@ const ext2_group_desc& Ext2FS::group_descriptor(GroupIndex group_index) const
 bool Ext2FS::initialize()
 {
     MutexLocker locker(m_lock);
+
     VERIFY((sizeof(ext2_super_block) % logical_block_size()) == 0);
     auto super_block_buffer = UserOrKernelBuffer::for_kernel_buffer((u8*)&m_super_block);
     bool success = raw_read_blocks(2, (sizeof(ext2_super_block) / logical_block_size()), super_block_buffer);
@@ -115,6 +116,11 @@ bool Ext2FS::initialize()
     set_block_size(EXT2_BLOCK_SIZE(&super_block));
     set_fragment_size(EXT2_FRAG_SIZE(&super_block));
 
+    // Note: This depends on the block size being available.
+    auto baseclass_result = BlockBasedFileSystem::initialize();
+    if (!baseclass_result)
+        return baseclass_result;
+
     VERIFY(block_size() <= (int)max_block_size);
 
     m_block_group_count = ceil_div(super_block.s_blocks_count, super_block.s_blocks_per_group);