[victoriafalls] Add an Ext2Driver class which probes the superblock.

sys/victoriafalls/fs/ext2/ext2_driver.h

@@ -0,0 +1,29 @@
+#pragma once
+
+#include <denali/denali_client.h>
+#include <glacier/memory/move.h>
+
+#include "fs/ext2/ext2.h"
+
+class Ext2Driver {
+ public:
+  Ext2Driver(ScopedDenaliClient&& denali) : denali_(glcr::Move(denali)) {}
+
+  glcr::ErrorCode ProbePartition();
+
+  glcr::ErrorOr<MappedMemoryRegion> ReadBlocks(uint64_t block_num,
+                                               uint64_t num_blocks) {
+    return denali_.ReadSectors(SectorsPerBlock() * block_num,
+                               SectorsPerBlock() * num_blocks);
+  }
+
+  uint64_t SectorsPerBlock() { return 1 << (superblock_->log_block_size + 1); }
+  uint64_t BlockToLba(uint64_t block) { return block * SectorsPerBlock(); }
+  uint64_t BytesToBlockCount(uint64_t bytes) {
+    return (bytes - 1) / (1024 << superblock_->log_block_size) + 1;
+  }
+
+ private:
+  ScopedDenaliClient denali_;
+  Superblock* superblock_;
+};