blob: 2b6f81bf0130acaf702f3f8ea3f6955a5610ba08 [file] [log] [blame]
// Copyright 2020 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <lib/zx/result.h>
#include <range/range.h>
namespace minfs {
using ByteRange = range::Range<uint64_t>;
using BlockRange = range::Range<uint64_t>;
// Represents a block on a device. The block should be relative to the start of the device, and the
// block size is that used by the file system. The block can also be unmapped a.k.a. sparse. Files
// that are unmapped blocks are zeroed; they occupy no space on the disk, but the user sees zeroed
// data.
class DeviceBlock {
static DeviceBlock Unmapped() { return {}; }
DeviceBlock() = default;
DeviceBlock(uint64_t block) : block_(block) { ZX_ASSERT(block != kUnmapped); }
DeviceBlock(const DeviceBlock& other) = default;
DeviceBlock& operator=(const DeviceBlock& other) = default;
bool IsMapped() const { return block_ != kUnmapped; }
uint64_t block() const {
ZX_ASSERT(block_ != kUnmapped);
return block_;
bool operator==(const DeviceBlock& other) const { return block_ == other.block_; }
bool operator!=(const DeviceBlock& other) const { return block_ != other.block_; }
static constexpr uint64_t kUnmapped = std::numeric_limits<uint64_t>::max();
uint64_t block_ = kUnmapped;
class DeviceBlockRange {
DeviceBlockRange() = default;
DeviceBlockRange(DeviceBlock device_block, uint64_t count)
: device_block_(device_block), count_(count) {}
DeviceBlockRange(const DeviceBlockRange& other) = default;
DeviceBlockRange& operator=(const DeviceBlockRange& other) = default;
DeviceBlock device_block() const { return device_block_; }
bool IsMapped() const { return device_block_.IsMapped(); }
uint64_t block() const { return device_block_.block(); }
uint64_t count() const { return count_; }
DeviceBlock device_block_;
uint64_t count_ = 0;
// Given a byte range, returns a block range that covers the byte range.
static inline BlockRange BytesToBlocks(ByteRange range, unsigned block_size) {
return BlockRange(range.Start() / block_size, (range.End() + block_size - 1) / block_size);
// Helpers that will call |callback| for all the blocks that encompass the range, which
// is in blocks. |callback| is of the form:
// zx::result<uint64_t> callback(range::Range<BlockType> range);
// |callback| can modify |block_count| to indicate how many blocks it processed if less than all of
// the blocks, or leave it unchanged if all blocks are processed.
template <typename BlockType, typename F>
[[nodiscard]] zx::result<> EnumerateBlocks(range::Range<BlockType> range, F callback) {
uint64_t len;
BlockType block = range.Start();
for (; block < range.End(); block += len) {
zx::result<uint64_t> status = callback(range::Range(block, range.End()));
if (status.is_error())
return status.take_error();
len = status.value();
return zx::ok();
// Same, but for bytes rather than blocks. It will enumerate all blocks touched by the range.
template <typename F>
[[nodiscard]] zx::result<> EnumerateBlocks(ByteRange range, unsigned block_size, F callback) {
if (range.Length() == 0)
return zx::ok();
return EnumerateBlocks(BytesToBlocks(range, block_size), callback);
} // namespace minfs