text: /*
   * Copyright (c) 2020, Liav A. <liavalb@hotmail.co.il>
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright notice, this
   *    list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include <AK/Memory.h>
  #include <AK/StringView.h>
  #include <Kernel/Debug.h>
  #include <Kernel/FileSystem/FileDescription.h>
  #include <Kernel/Storage/StorageDevice.h>
  
  namespace Kernel {
  
  StorageDevice::StorageDevice(const StorageController& controller, int major, int minor, size_t sector_size, size_t max_addressable_block)
      : BlockDevice(major, minor, sector_size)
      , m_storage_controller(controller)
      , m_max_addressable_block(max_addressable_block)
  {
  }
  
  const char* StorageDevice::class_name() const
  {
      return "StorageDevice";
  }
  
  NonnullRefPtr<StorageController> StorageDevice::controller() const
  {
      return m_storage_controller;
  }
  
  KResultOr<size_t> StorageDevice::read(FileDescription&, size_t offset, UserOrKernelBuffer& outbuf, size_t len)
  {
      unsigned index = offset / block_size();
      u16 whole_blocks = len / block_size();
      ssize_t remaining = len % block_size();
  
      unsigned blocks_per_page = PAGE_SIZE / block_size();
  
      // PATAChannel will chuck a wobbly if we try to read more than PAGE_SIZE
      // at a time, because it uses a single page for its DMA buffer.
      if (whole_blocks >= blocks_per_page) {
          whole_blocks = blocks_per_page;
          remaining = 0;
      }
  
  #if STORAGE_DEVICE_DEBUG
      klog() << "StorageDevice::read() index=" << index << " whole_blocks=" << whole_blocks << " remaining=" << remaining;
  #endif
  
      if (whole_blocks > 0) {
          auto read_request = make_request<AsyncBlockDeviceRequest>(AsyncBlockDeviceRequest::Read, index, whole_blocks, outbuf, whole_blocks * block_size());
          auto result = read_request->wait();
          if (result.wait_result().was_interrupted())
              return EINTR;
          switch (result.request_result()) {
          case AsyncDeviceRequest::Failure:
          case AsyncDeviceRequest::Cancelled:
              return EIO;
          case AsyncDeviceRequest::MemoryFault:
              return EFAULT;
          default:
              break;
          }
      }
  
      off_t pos = whole_blocks * block_size();
  
      if (remaining > 0) {
          auto data = ByteBuffer::create_uninitialized(block_size());
          auto data_buffer = UserOrKernelBuffer::for_kernel_buffer(data.data());
          auto read_request = make_request<AsyncBlockDeviceRequest>(AsyncBlockDeviceRequest::Read, index + whole_blocks, 1, data_buffer, block_size());
          auto result = read_request->wait();
          if (result.wait_result().was_interrupted())
              return EINTR;
          switch (result.request_result()) {
          case AsyncDeviceRequest::Failure:
              return pos;
          case AsyncDeviceRequest::Cancelled:
              return EIO;
          case AsyncDeviceRequest::MemoryFault:
              // This should never happen, we're writing to a kernel buffer!
              VERIFY_NOT_REACHED();
          default:
              break;
          }
          if (!outbuf.write(data.data(), pos, remaining))
              return EFAULT;
      }
  
      return pos + remaining;
  }
  
  bool StorageDevice::can_read(const FileDescription&, size_t offset) const
  {
      return offset < (max_addressable_block() * block_size());
  }
  
  KResultOr<size_t> StorageDevice::write(FileDescription&, size_t offset, const UserOrKernelBuffer& inbuf, size_t len)
  {
      unsigned index = offset / block_size();
      u16 whole_blocks = len / block_size();
      ssize_t remaining = len % block_size();
  
      unsigned blocks_per_page = PAGE_SIZE / block_size();
  
      // PATAChannel will chuck a wobbly if we try to write more than PAGE_SIZE
      // at a time, because it uses a single page for its DMA buffer.
      if (whole_blocks >= blocks_per_page) {
          whole_blocks = blocks_per_page;
          remaining = 0;
      }
  
  #if STORAGE_DEVICE_DEBUG
      klog() << "StorageDevice::write() index=" << index << " whole_blocks=" << whole_blocks << " remaining=" << remaining;
  #endif
  
      if (whole_blocks > 0) {
          auto write_request = make_request<AsyncBlockDeviceRequest>(AsyncBlockDeviceRequest::Write, index, whole_blocks, inbuf, whole_blocks * block_size());
          auto result = write_request->wait();
          if (result.wait_result().was_interrupted())
              return EINTR;
          switch (result.request_result()) {
          case AsyncDeviceRequest::Failure:
          case AsyncDeviceRequest::Cancelled:
              return EIO;
          case AsyncDeviceRequest::MemoryFault:
              return EFAULT;
          default:
              break;
          }
      }
  
      off_t pos = whole_blocks * block_size();
  
      // since we can only write in block_size() increments, if we want to do a
      // partial write, we have to read the block's content first, modify it,
      // then write the whole block back to the disk.
      if (remaining > 0) {
          auto data = ByteBuffer::create_zeroed(block_size());
          auto data_buffer = UserOrKernelBuffer::for_kernel_buffer(data.data());
  
          {
              auto read_request = make_request<AsyncBlockDeviceRequest>(AsyncBlockDeviceRequest::Read, index + whole_blocks, 1, data_buffer, block_size());
              auto result = read_request->wait();
              if (result.wait_result().was_interrupted())
                  return EINTR;
              switch (result.request_result()) {
              case AsyncDeviceRequest::Failure:
                  return pos;
              case AsyncDeviceRequest::Cancelled:
                  return EIO;
              case AsyncDeviceRequest::MemoryFault:
                  // This should never happen, we're writing to a kernel buffer!
                  VERIFY_NOT_REACHED();
              default:
                  break;
              }
          }
  
          if (!inbuf.read(data.data(), pos, remaining))
              return EFAULT;
  
          {
              auto write_request = make_request<AsyncBlockDeviceRequest>(AsyncBlockDeviceRequest::Write, index + whole_blocks, 1, data_buffer, block_size());
              auto result = write_request->wait();
              if (result.wait_result().was_interrupted())
                  return EINTR;
              switch (result.request_result()) {
              case AsyncDeviceRequest::Failure:
                  return pos;
              case AsyncDeviceRequest::Cancelled:
                  return EIO;
              case AsyncDeviceRequest::MemoryFault:
                  // This should never happen, we're writing to a kernel buffer!
                  VERIFY_NOT_REACHED();
              default:
                  break;
              }
          }
      }
  
      return pos + remaining;
  }
  
  bool StorageDevice::can_write(const FileDescription&, size_t offset) const
  {
      return offset < (max_addressable_block() * block_size());
  }
  
  }
  