mergerfs/src/fs_inode.cpp

/*
  ISC License

  Copyright (c) 2020, Antonio SJ Musumeci <trapexit@spawn.link>

  Permission to use, copy, modify, and/or distribute this software for any
  purpose with or without fee is hereby granted, provided that the above
  copyright notice and this permission notice appear in all copies.

  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#include "fs_inode.hpp"

#include "ef.hpp"
#include "errno.hpp"
#include "rapidhash.h"

#include <cstdint>
#include <string>

#include <pthread.h>
#include <string.h>
#include <sys/stat.h>

using namespace nonstd;

typedef uint64_t (*inodefunc_t)(const string_view,
                                const string_view,
                                const mode_t,
                                const ino_t);

static uint64_t hybrid_hash(const string_view,
                            const string_view,
                            const mode_t,
                            const ino_t);


static inodefunc_t g_func = hybrid_hash;


static
uint32_t
h64_to_h32(uint64_t h_)
{
  h_ ^= (h_ >> 32);
  h_ *= 0x9E3779B9;
  return h_;
}

static
uint64_t
passthrough(const string_view branch_path_,
            const string_view fusepath_,
            const mode_t      mode_,
            const ino_t       ino_)
{
  return ino_;
}

static
uint64_t
path_hash(const string_view branch_path_,
          const string_view fusepath_,
          const mode_t      mode_,
          const ino_t       ino_)
{
  uint64_t seed;

  seed = rapidhash(&fusepath_[0],fusepath_.size());

  return seed;
}

static
uint64_t
path_hash32(const string_view branch_path_,
            const string_view fusepath_,
            const mode_t      mode_,
            const ino_t       ino_)
{
  uint64_t h;

  h = path_hash(branch_path_,
                fusepath_,
                mode_,
                ino_);

  return h64_to_h32(h);
}

static
uint64_t
devino_hash(const string_view branch_path_,
            const string_view fusepath_,
            const mode_t      mode_,
            const ino_t       ino_)
{
  uint64_t seed;

  seed = rapidhash(&branch_path_[0],branch_path_.size());
  seed = rapidhash_withSeed(&ino_,sizeof(ino_),seed);

  return seed;
}

static
uint64_t
devino_hash32(const string_view branch_path_,
              const string_view fusepath_,
              const mode_t      mode_,
              const ino_t       ino_)
{
  uint64_t h;

  h = devino_hash(branch_path_,
                  fusepath_,
                  mode_,
                  ino_);

  return h64_to_h32(h);
}

static
uint64_t
hybrid_hash(const string_view branch_path_,
            const string_view fusepath_,
            const mode_t      mode_,
            const ino_t       ino_)
{
  return (S_ISDIR(mode_) ?
          path_hash(branch_path_,fusepath_,mode_,ino_) :
          devino_hash(branch_path_,fusepath_,mode_,ino_));
}

static
uint64_t
hybrid_hash32(const string_view branch_path_,
              const string_view fusepath_,
              const mode_t      mode_,
              const ino_t       ino_)
{
  return (S_ISDIR(mode_) ?
          path_hash32(branch_path_,fusepath_,mode_,ino_) :
          devino_hash32(branch_path_,fusepath_,mode_,ino_));
}

namespace fs
{
  namespace inode
  {
    int
    set_algo(const std::string &algo_)
    {
      if(algo_ == "passthrough")
        g_func = passthrough;
      ef(algo_ == "path-hash")
        g_func = path_hash;
      ef(algo_ == "path-hash32")
        g_func = path_hash32;
      ef(algo_ == "devino-hash")
        g_func = devino_hash;
      ef(algo_ == "devino-hash32")
        g_func = devino_hash32;
      ef(algo_ == "hybrid-hash")
        g_func = hybrid_hash;
      ef(algo_ == "hybrid-hash32")
        g_func = hybrid_hash32;
      else
        return -EINVAL;

      return 0;
    }

    std::string
    get_algo(void)
    {
      if(g_func == passthrough)
        return "passthrough";
      if(g_func == path_hash)
        return "path-hash";
      if(g_func == path_hash32)
        return "path-hash32";
      if(g_func == devino_hash)
        return "devino-hash";
      if(g_func == devino_hash32)
        return "devino-hash32";
      if(g_func == hybrid_hash)
        return "hybrid-hash";
      if(g_func == hybrid_hash32)
        return "hybrid-hash32";

      return std::string();
    }

    uint64_t
    calc(const string_view branch_path_,
         const string_view fusepath_,
         const mode_t      mode_,
         const ino_t       ino_)
    {
      return g_func(branch_path_,fusepath_,mode_,ino_);
    }

    void
    calc(const string_view  branch_path_,
         const string_view  fusepath_,
         struct stat       *st_)
    {
      st_->st_ino = calc(branch_path_,
                         fusepath_,
                         st_->st_mode,
                         st_->st_ino);
    }

    void
    calc(const string_view  branch_path_,
         const string_view  fusepath_,
         struct fuse_statx *st_)
    {
      st_->ino = calc(branch_path_,
                      fusepath_,
                      st_->mode,
                      st_->ino);
    }
  }
}