Adding upstream version 16.2.11+ds.upstream/16.2.11+dsupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 707 insertions, 0 deletions

diff --git a/src/os/bluestore/BlueFS.h b/src/os/bluestore/BlueFS.h
new file mode 100644
index 000000000..988c7e37f
--- /dev/null
+++ b/src/os/bluestore/BlueFS.h
@@ -0,0 +1,707 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+#ifndef CEPH_OS_BLUESTORE_BLUEFS_H
+#define CEPH_OS_BLUESTORE_BLUEFS_H
+
+#include <atomic>
+#include <mutex>
+#include <limits>
+
+#include "bluefs_types.h"
+#include "blk/BlockDevice.h"
+
+#include "common/RefCountedObj.h"
+#include "common/ceph_context.h"
+#include "global/global_context.h"
+#include "include/common_fwd.h"
+
+#include "boost/intrusive/list.hpp"
+#include "boost/dynamic_bitset.hpp"
+
+class Allocator;
+
+enum {
+  l_bluefs_first = 732600,
+  l_bluefs_db_total_bytes,
+  l_bluefs_db_used_bytes,
+  l_bluefs_wal_total_bytes,
+  l_bluefs_wal_used_bytes,
+  l_bluefs_slow_total_bytes,
+  l_bluefs_slow_used_bytes,
+  l_bluefs_num_files,
+  l_bluefs_log_bytes,
+  l_bluefs_log_compactions,
+  l_bluefs_logged_bytes,
+  l_bluefs_files_written_wal,
+  l_bluefs_files_written_sst,
+  l_bluefs_bytes_written_wal,
+  l_bluefs_bytes_written_sst,
+  l_bluefs_bytes_written_slow,
+  l_bluefs_max_bytes_wal,
+  l_bluefs_max_bytes_db,
+  l_bluefs_max_bytes_slow,
+  l_bluefs_read_random_count,
+  l_bluefs_read_random_bytes,
+  l_bluefs_read_random_disk_count,
+  l_bluefs_read_random_disk_bytes,
+  l_bluefs_read_random_buffer_count,
+  l_bluefs_read_random_buffer_bytes,
+  l_bluefs_read_count,
+  l_bluefs_read_bytes,
+  l_bluefs_read_prefetch_count,
+  l_bluefs_read_prefetch_bytes,
+  l_bluefs_read_zeros_candidate,
+  l_bluefs_read_zeros_errors,
+
+  l_bluefs_last,
+};
+
+class BlueFSVolumeSelector {
+public:
+  typedef std::vector<std::pair<std::string, uint64_t>> paths;
+
+  virtual ~BlueFSVolumeSelector() {
+  }
+  virtual void* get_hint_for_log() const = 0;
+  virtual void* get_hint_by_dir(std::string_view dirname) const = 0;
+
+  virtual void add_usage(void* file_hint, const bluefs_fnode_t& fnode) = 0;
+  virtual void sub_usage(void* file_hint, const bluefs_fnode_t& fnode) = 0;
+  virtual void add_usage(void* file_hint, uint64_t fsize) = 0;
+  virtual void sub_usage(void* file_hint, uint64_t fsize) = 0;
+  virtual uint8_t select_prefer_bdev(void* hint) = 0;
+  virtual void get_paths(const std::string& base, paths& res) const = 0;
+  virtual void dump(std::ostream& sout) = 0;
+};
+
+struct bluefs_shared_alloc_context_t {
+  bool need_init = false;
+  Allocator* a = nullptr;
+
+  std::atomic<uint64_t> bluefs_used = 0;
+
+  void set(Allocator* _a) {
+    a = _a;
+    need_init = true;
+    bluefs_used = 0;
+  }
+  void reset() {
+    a = nullptr;
+  }
+};
+
+class BlueFS {
+public:
+  CephContext* cct;
+  static constexpr unsigned MAX_BDEV = 5;
+  static constexpr unsigned BDEV_WAL = 0;
+  static constexpr unsigned BDEV_DB = 1;
+  static constexpr unsigned BDEV_SLOW = 2;
+  static constexpr unsigned BDEV_NEWWAL = 3;
+  static constexpr unsigned BDEV_NEWDB = 4;
+
+  enum {
+    WRITER_UNKNOWN,
+    WRITER_WAL,
+    WRITER_SST,
+  };
+
+  struct File : public RefCountedObject {
+    MEMPOOL_CLASS_HELPERS();
+
+    bluefs_fnode_t fnode;
+    int refs;
+    uint64_t dirty_seq;
+    bool locked;
+    bool deleted;
+    bool is_dirty;
+    boost::intrusive::list_member_hook<> dirty_item;
+
+    std::atomic_int num_readers, num_writers;
+    std::atomic_int num_reading;
+
+    void* vselector_hint = nullptr;
+
+  private:
+    FRIEND_MAKE_REF(File);
+    File()
+      :
+	refs(0),
+	dirty_seq(0),
+	locked(false),
+	deleted(false),
+	is_dirty(false),
+	num_readers(0),
+	num_writers(0),
+	num_reading(0),
+        vselector_hint(nullptr)
+      {}
+    ~File() override {
+      ceph_assert(num_readers.load() == 0);
+      ceph_assert(num_writers.load() == 0);
+      ceph_assert(num_reading.load() == 0);
+      ceph_assert(!locked);
+    }
+  };
+  using FileRef = ceph::ref_t<File>;
+
+  typedef boost::intrusive::list<
+      File,
+      boost::intrusive::member_hook<
+        File,
+	boost::intrusive::list_member_hook<>,
+	&File::dirty_item> > dirty_file_list_t;
+
+  struct Dir : public RefCountedObject {
+    MEMPOOL_CLASS_HELPERS();
+
+    mempool::bluefs::map<std::string, FileRef, std::less<>> file_map;
+
+  private:
+    FRIEND_MAKE_REF(Dir);
+    Dir() = default;
+  };
+  using DirRef = ceph::ref_t<Dir>;
+
+  struct FileWriter {
+    MEMPOOL_CLASS_HELPERS();
+
+    FileRef file;
+    uint64_t pos = 0;       ///< start offset for buffer
+  private:
+    ceph::buffer::list buffer;      ///< new data to write (at end of file)
+    ceph::buffer::list tail_block;  ///< existing partial block at end of file, if any
+  public:
+    unsigned get_buffer_length() const {
+      return buffer.length();
+    }
+    ceph::bufferlist flush_buffer(
+      CephContext* cct,
+      const bool partial,
+      const unsigned length,
+      const bluefs_super_t& super);
+    ceph::buffer::list::page_aligned_appender buffer_appender;  //< for const char* only
+  public:
+    int writer_type = 0;    ///< WRITER_*
+    int write_hint = WRITE_LIFE_NOT_SET;
+
+    ceph::mutex lock = ceph::make_mutex("BlueFS::FileWriter::lock");
+    std::array<IOContext*,MAX_BDEV> iocv; ///< for each bdev
+    std::array<bool, MAX_BDEV> dirty_devs;
+
+    FileWriter(FileRef f)
+      : file(std::move(f)),
+       buffer_appender(buffer.get_page_aligned_appender(
+                         g_conf()->bluefs_alloc_size / CEPH_PAGE_SIZE)) {
+      ++file->num_writers;
+      iocv.fill(nullptr);
+      dirty_devs.fill(false);
+      if (file->fnode.ino == 1) {
+	write_hint = WRITE_LIFE_MEDIUM;
+      }
+    }
+    // NOTE: caller must call BlueFS::close_writer()
+    ~FileWriter() {
+      --file->num_writers;
+    }
+
+    // note: BlueRocksEnv uses this append exclusively, so it's safe
+    // to use buffer_appender exclusively here (e.g., it's notion of
+    // offset will remain accurate).
+    void append(const char *buf, size_t len) {
+      uint64_t l0 = get_buffer_length();
+      ceph_assert(l0 + len <= std::numeric_limits<unsigned>::max());
+      buffer_appender.append(buf, len);
+    }
+
+    // note: used internally only, for ino 1 or 0.
+    void append(ceph::buffer::list& bl) {
+      uint64_t l0 = get_buffer_length();
+      ceph_assert(l0 + bl.length() <= std::numeric_limits<unsigned>::max());
+      buffer.claim_append(bl);
+    }
+
+    void append_zero(size_t len) {
+      uint64_t l0 = get_buffer_length();
+      ceph_assert(l0 + len <= std::numeric_limits<unsigned>::max());
+      buffer_appender.append_zero(len);
+    }
+
+    uint64_t get_effective_write_pos() {
+      return pos + buffer.length();
+    }
+  };
+
+  struct FileReaderBuffer {
+    MEMPOOL_CLASS_HELPERS();
+
+    uint64_t bl_off = 0;    ///< prefetch buffer logical offset
+    ceph::buffer::list bl;          ///< prefetch buffer
+    uint64_t pos = 0;       ///< current logical offset
+    uint64_t max_prefetch;  ///< max allowed prefetch
+
+    explicit FileReaderBuffer(uint64_t mpf)
+      : max_prefetch(mpf) {}
+
+    uint64_t get_buf_end() const {
+      return bl_off + bl.length();
+    }
+    uint64_t get_buf_remaining(uint64_t p) const {
+      if (p >= bl_off && p < bl_off + bl.length())
+	return bl_off + bl.length() - p;
+      return 0;
+    }
+
+    void skip(size_t n) {
+      pos += n;
+    }
+
+    // For the sake of simplicity, we invalidate completed rather than
+    // for the provided extent
+    void invalidate_cache(uint64_t offset, uint64_t length) {
+      if (offset >= bl_off && offset < get_buf_end()) {
+	bl.clear();
+	bl_off = 0;
+      }
+    }
+  };
+
+  struct FileReader {
+    MEMPOOL_CLASS_HELPERS();
+
+    FileRef file;
+    FileReaderBuffer buf;
+    bool random;
+    bool ignore_eof;        ///< used when reading our log file
+
+    ceph::shared_mutex lock {
+     ceph::make_shared_mutex(std::string(), false, false, false)
+    };
+
+
+    FileReader(FileRef f, uint64_t mpf, bool rand, bool ie)
+      : file(f),
+	buf(mpf),
+	random(rand),
+	ignore_eof(ie) {
+      ++file->num_readers;
+    }
+    ~FileReader() {
+      --file->num_readers;
+    }
+  };
+
+  struct FileLock {
+    MEMPOOL_CLASS_HELPERS();
+
+    FileRef file;
+    explicit FileLock(FileRef f) : file(std::move(f)) {}
+  };
+
+private:
+  ceph::mutex lock = ceph::make_mutex("BlueFS::lock");
+
+  PerfCounters *logger = nullptr;
+
+  uint64_t max_bytes[MAX_BDEV] = {0};
+  uint64_t max_bytes_pcounters[MAX_BDEV] = {
+    l_bluefs_max_bytes_wal,
+    l_bluefs_max_bytes_db,
+    l_bluefs_max_bytes_slow,
+  };
+
+  // cache
+  mempool::bluefs::map<std::string, DirRef, std::less<>> dir_map;          ///< dirname -> Dir
+  mempool::bluefs::unordered_map<uint64_t, FileRef> file_map; ///< ino -> File
+
+  // map of dirty files, files of same dirty_seq are grouped into list.
+  std::map<uint64_t, dirty_file_list_t> dirty_files;
+
+  bluefs_super_t super;        ///< latest superblock (as last written)
+  uint64_t ino_last = 0;       ///< last assigned ino (this one is in use)
+  uint64_t log_seq = 0;        ///< last used log seq (by current pending log_t)
+  uint64_t log_seq_stable = 0; ///< last stable/synced log seq
+  FileWriter *log_writer = 0;  ///< writer for the log
+  bluefs_transaction_t log_t;  ///< pending, unwritten log transaction
+  bool log_flushing = false;   ///< true while flushing the log
+  ceph::condition_variable log_cond;
+
+  uint64_t new_log_jump_to = 0;
+  uint64_t old_log_jump_to = 0;
+  FileRef new_log = nullptr;
+  FileWriter *new_log_writer = nullptr;
+
+  /*
+   * There are up to 3 block devices:
+   *
+   *  BDEV_DB   db/      - the primary db device
+   *  BDEV_WAL  db.wal/  - a small, fast device, specifically for the WAL
+   *  BDEV_SLOW db.slow/ - a big, slow device, to spill over to as BDEV_DB fills
+   */
+  std::vector<BlockDevice*> bdev;                  ///< block devices we can use
+  std::vector<IOContext*> ioc;                     ///< IOContexts for bdevs
+  std::vector<uint64_t> block_reserved;            ///< starting reserve extent per device
+  std::vector<Allocator*> alloc;                   ///< allocators for bdevs
+  std::vector<uint64_t> alloc_size;                ///< alloc size for each device
+  std::vector<interval_set<uint64_t>> pending_release; ///< extents to release
+  //std::vector<interval_set<uint64_t>> block_unused_too_granular;
+
+  BlockDevice::aio_callback_t discard_cb[3]; //discard callbacks for each dev
+
+  std::unique_ptr<BlueFSVolumeSelector> vselector;
+
+  bluefs_shared_alloc_context_t* shared_alloc = nullptr;
+  unsigned shared_alloc_id = unsigned(-1);
+  inline bool is_shared_alloc(unsigned id) const {
+    return id == shared_alloc_id;
+  }
+
+  class SocketHook;
+  SocketHook* asok_hook = nullptr;
+  // used to trigger zeros into read (debug / verify)
+  std::atomic<uint64_t> inject_read_zeros{0};
+
+  void _init_logger();
+  void _shutdown_logger();
+  void _update_logger_stats();
+
+  void _init_alloc();
+  void _stop_alloc();
+
+  void _pad_bl(ceph::buffer::list& bl);  ///< pad ceph::buffer::list to block size w/ zeros
+
+  uint64_t _get_used(unsigned id) const;
+  uint64_t _get_total(unsigned id) const;
+
+
+  FileRef _get_file(uint64_t ino);
+  void _drop_link(FileRef f);
+
+  unsigned _get_slow_device_id() {
+    return bdev[BDEV_SLOW] ? BDEV_SLOW : BDEV_DB;
+  }
+  const char* get_device_name(unsigned id);
+  int _allocate(uint8_t bdev, uint64_t len,
+		bluefs_fnode_t* node);
+  int _allocate_without_fallback(uint8_t id, uint64_t len,
+				 PExtentVector* extents);
+
+  /* signal replay log to include h->file in nearest log flush */
+  int _signal_dirty_to_log(FileWriter *h);
+  int _flush_range(FileWriter *h, uint64_t offset, uint64_t length);
+  int _flush(FileWriter *h, bool force, std::unique_lock<ceph::mutex>& l);
+  int _flush(FileWriter *h, bool force, bool *flushed = nullptr);
+  int _fsync(FileWriter *h, std::unique_lock<ceph::mutex>& l);
+
+#ifdef HAVE_LIBAIO
+  void _claim_completed_aios(FileWriter *h, std::list<aio_t> *ls);
+  void wait_for_aio(FileWriter *h);  // safe to call without a lock
+#endif
+
+  int _flush_and_sync_log(std::unique_lock<ceph::mutex>& l,
+			  uint64_t want_seq = 0,
+			  uint64_t jump_to = 0);
+  uint64_t _estimate_log_size();
+  bool _should_compact_log();
+
+  enum {
+    REMOVE_DB = 1,
+    REMOVE_WAL = 2,
+    RENAME_SLOW2DB = 4,
+    RENAME_DB2SLOW = 8,
+  };
+  void _compact_log_dump_metadata(bluefs_transaction_t *t,
+				  int flags);
+  void _compact_log_sync();
+  void _compact_log_async(std::unique_lock<ceph::mutex>& l);
+
+  void _rewrite_log_and_layout_sync(bool allocate_with_fallback,
+				    int super_dev,
+				    int log_dev,
+				    int new_log_dev,
+				    int flags,
+				    std::optional<bluefs_layout_t> layout);
+
+  //void _aio_finish(void *priv);
+
+  void _flush_bdev_safely(FileWriter *h);
+  void flush_bdev();  // this is safe to call without a lock
+  void flush_bdev(std::array<bool, MAX_BDEV>& dirty_bdevs);  // this is safe to call without a lock
+
+  int _preallocate(FileRef f, uint64_t off, uint64_t len);
+  int _truncate(FileWriter *h, uint64_t off);
+
+  int64_t _read(
+    FileReader *h,   ///< [in] read from here
+    uint64_t offset, ///< [in] offset
+    size_t len,      ///< [in] this many bytes
+    ceph::buffer::list *outbl,   ///< [out] optional: reference the result here
+    char *out);      ///< [out] optional: or copy it here
+  int64_t _read_random(
+    FileReader *h,   ///< [in] read from here
+    uint64_t offset, ///< [in] offset
+    uint64_t len,    ///< [in] this many bytes
+    char *out);      ///< [out] optional: or copy it here
+
+  void _invalidate_cache(FileRef f, uint64_t offset, uint64_t length);
+
+  int _open_super();
+  int _write_super(int dev);
+  int _check_allocations(const bluefs_fnode_t& fnode,
+    boost::dynamic_bitset<uint64_t>* used_blocks,
+    bool is_alloc, //true when allocating, false when deallocating
+    const char* op_name);
+  int _verify_alloc_granularity(
+    __u8 id, uint64_t offset, uint64_t length,
+    const char *op);
+  int _replay(bool noop, bool to_stdout = false); ///< replay journal
+
+  FileWriter *_create_writer(FileRef f);
+  void _close_writer(FileWriter *h);
+
+  // always put the super in the second 4k block.  FIXME should this be
+  // block size independent?
+  unsigned get_super_offset() {
+    return 4096;
+  }
+  unsigned get_super_length() {
+    return 4096;
+  }
+
+public:
+  BlueFS(CephContext* cct);
+  ~BlueFS();
+
+  // the super is always stored on bdev 0
+  int mkfs(uuid_d osd_uuid, const bluefs_layout_t& layout);
+  int mount();
+  int maybe_verify_layout(const bluefs_layout_t& layout) const;
+  void umount(bool avoid_compact = false);
+  int prepare_new_device(int id, const bluefs_layout_t& layout);
+  
+  int log_dump();
+
+  void collect_metadata(std::map<std::string,std::string> *pm, unsigned skip_bdev_id);
+  void get_devices(std::set<std::string> *ls);
+  uint64_t get_alloc_size(int id) {
+    return alloc_size[id];
+  }
+  int fsck();
+
+  int device_migrate_to_new(
+    CephContext *cct,
+    const std::set<int>& devs_source,
+    int dev_target,
+    const bluefs_layout_t& layout);
+  int device_migrate_to_existing(
+    CephContext *cct,
+    const std::set<int>& devs_source,
+    int dev_target,
+    const bluefs_layout_t& layout);
+
+  uint64_t get_used();
+  uint64_t get_total(unsigned id);
+  uint64_t get_free(unsigned id);
+  uint64_t get_used(unsigned id);
+  void dump_perf_counters(ceph::Formatter *f);
+
+  void dump_block_extents(std::ostream& out);
+
+  /// get current extents that we own for given block device
+  int get_block_extents(unsigned id, interval_set<uint64_t> *extents);
+
+  int open_for_write(
+    std::string_view dir,
+    std::string_view file,
+    FileWriter **h,
+    bool overwrite);
+
+  int open_for_read(
+    std::string_view dir,
+    std::string_view file,
+    FileReader **h,
+    bool random = false);
+
+  void close_writer(FileWriter *h) {
+    std::lock_guard l(lock);
+    _close_writer(h);
+  }
+
+  int rename(std::string_view old_dir, std::string_view old_file,
+	     std::string_view new_dir, std::string_view new_file);
+
+  int readdir(std::string_view dirname, std::vector<std::string> *ls);
+
+  int unlink(std::string_view dirname, std::string_view filename);
+  int mkdir(std::string_view dirname);
+  int rmdir(std::string_view dirname);
+  bool wal_is_rotational();
+
+  bool dir_exists(std::string_view dirname);
+  int stat(std::string_view dirname, std::string_view filename,
+	   uint64_t *size, utime_t *mtime);
+
+  int lock_file(std::string_view dirname, std::string_view filename, FileLock **p);
+  int unlock_file(FileLock *l);
+
+  void compact_log();
+
+  /// sync any uncommitted state to disk
+  void sync_metadata(bool avoid_compact);
+  /// test and compact log, if necessary
+  void _maybe_compact_log(std::unique_lock<ceph::mutex>& l);
+
+  void set_volume_selector(BlueFSVolumeSelector* s) {
+    vselector.reset(s);
+  }
+  void dump_volume_selector(std::ostream& sout) {
+    vselector->dump(sout);
+  }
+  void get_vselector_paths(const std::string& base,
+                           BlueFSVolumeSelector::paths& res) const {
+    return vselector->get_paths(base, res);
+  }
+
+  int add_block_device(unsigned bdev, const std::string& path, bool trim,
+                       uint64_t reserved,
+		       bluefs_shared_alloc_context_t* _shared_alloc = nullptr);
+  bool bdev_support_label(unsigned id);
+  uint64_t get_block_device_size(unsigned bdev) const;
+
+  // handler for discard event
+  void handle_discard(unsigned dev, interval_set<uint64_t>& to_release);
+
+  void flush(FileWriter *h, bool force = false) {
+    std::unique_lock l(lock);
+    int r = _flush(h, force, l);
+    ceph_assert(r == 0);
+  }
+
+  void append_try_flush(FileWriter *h, const char* buf, size_t len) {
+    size_t max_size = 1ull << 30; // cap to 1GB
+    while (len > 0) {
+      bool need_flush = true;
+      auto l0 = h->get_buffer_length();
+      if (l0 < max_size) {
+	size_t l = std::min(len, max_size - l0);
+	h->append(buf, l);
+	buf += l;
+	len -= l;
+	need_flush = h->get_buffer_length() >= cct->_conf->bluefs_min_flush_size;
+      }
+      if (need_flush) {
+	flush(h, true);
+	// make sure we've made any progress with flush hence the
+	// loop doesn't iterate forever
+	ceph_assert(h->get_buffer_length() < max_size);
+      }
+    }
+  }
+  void flush_range(FileWriter *h, uint64_t offset, uint64_t length) {
+    std::lock_guard l(lock);
+    _flush_range(h, offset, length);
+  }
+  int fsync(FileWriter *h) {
+    std::unique_lock l(lock);
+    int r = _fsync(h, l);
+    _maybe_compact_log(l);
+    return r;
+  }
+  int64_t read(FileReader *h, uint64_t offset, size_t len,
+	   ceph::buffer::list *outbl, char *out) {
+    // no need to hold the global lock here; we only touch h and
+    // h->file, and read vs write or delete is already protected (via
+    // atomics and asserts).
+    return _read(h, offset, len, outbl, out);
+  }
+  int64_t read_random(FileReader *h, uint64_t offset, size_t len,
+		  char *out) {
+    // no need to hold the global lock here; we only touch h and
+    // h->file, and read vs write or delete is already protected (via
+    // atomics and asserts).
+    return _read_random(h, offset, len, out);
+  }
+  void invalidate_cache(FileRef f, uint64_t offset, uint64_t len) {
+    std::lock_guard l(lock);
+    _invalidate_cache(f, offset, len);
+  }
+  int preallocate(FileRef f, uint64_t offset, uint64_t len) {
+    std::lock_guard l(lock);
+    return _preallocate(f, offset, len);
+  }
+  int truncate(FileWriter *h, uint64_t offset) {
+    std::lock_guard l(lock);
+    return _truncate(h, offset);
+  }
+  int do_replay_recovery_read(FileReader *log,
+			      size_t log_pos,
+			      size_t read_offset,
+			      size_t read_len,
+			      bufferlist* bl);
+
+  size_t probe_alloc_avail(int dev, uint64_t alloc_size);
+
+  /// test purpose methods
+  const PerfCounters* get_perf_counters() const {
+    return logger;
+  }
+  uint64_t debug_get_dirty_seq(FileWriter *h);
+  bool debug_get_is_dev_dirty(FileWriter *h, uint8_t dev);
+
+private:
+  // Wrappers for BlockDevice::read(...) and BlockDevice::read_random(...)
+  // They are used for checking if read values are all 0, and reread if so.
+  int read(uint8_t ndev, uint64_t off, uint64_t len,
+	   ceph::buffer::list *pbl, IOContext *ioc, bool buffered);
+  int read_random(uint8_t ndev, uint64_t off, uint64_t len, char *buf, bool buffered);
+};
+
+class OriginalVolumeSelector : public BlueFSVolumeSelector {
+  uint64_t wal_total;
+  uint64_t db_total;
+  uint64_t slow_total;
+
+public:
+  OriginalVolumeSelector(
+    uint64_t _wal_total,
+    uint64_t _db_total,
+    uint64_t _slow_total)
+    : wal_total(_wal_total), db_total(_db_total), slow_total(_slow_total) {}
+
+  void* get_hint_for_log() const override;
+  void* get_hint_by_dir(std::string_view dirname) const override;
+
+  void add_usage(void* hint, const bluefs_fnode_t& fnode) override {
+    // do nothing
+    return;
+  }
+  void sub_usage(void* hint, const bluefs_fnode_t& fnode) override {
+    // do nothing
+    return;
+  }
+  void add_usage(void* hint, uint64_t fsize) override {
+    // do nothing
+    return;
+  }
+  void sub_usage(void* hint, uint64_t fsize) override {
+    // do nothing
+    return;
+  }
+
+  uint8_t select_prefer_bdev(void* hint) override;
+  void get_paths(const std::string& base, paths& res) const override;
+  void dump(std::ostream& sout) override;
+};
+
+class FitToFastVolumeSelector : public OriginalVolumeSelector {
+public:
+  FitToFastVolumeSelector(
+    uint64_t _wal_total,
+    uint64_t _db_total,
+    uint64_t _slow_total)
+    : OriginalVolumeSelector(_wal_total, _db_total, _slow_total) {}
+
+  void get_paths(const std::string& base, paths& res) const override;
+};
+
+#endif