import ceph 12.2.12

[ceph.git] / ceph / src / os / filestore / LFNIndex.cc

// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
/*
 * Ceph - scalable distributed file system
 *
 * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
 *
 * This is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License version 2.1, as published by the Free Software
 * Foundation.  See file COPYING.
 *
 */

#include <string>
#include <map>
#include <set>
#include <vector>
#include <errno.h>
#include <string.h>

#if defined(__FreeBSD__)
#include <sys/param.h>
#endif

#include "osd/osd_types.h"
#include "include/object.h"
#include "common/config.h"
#include "common/debug.h"
#include "include/buffer.h"
#include "common/ceph_crypto.h"
#include "common/errno.h"
#include "include/compat.h"
#include "chain_xattr.h"

#include "LFNIndex.h"
using ceph::crypto::SHA1;

#define dout_context cct
#define dout_subsys ceph_subsys_filestore
#undef dout_prefix
#define dout_prefix *_dout << "LFNIndex(" << get_base_path() << ") "


const string LFNIndex::LFN_ATTR = "user.cephos.lfn";
const string LFNIndex::PHASH_ATTR_PREFIX = "user.cephos.phash.";
const string LFNIndex::SUBDIR_PREFIX = "DIR_";
const string LFNIndex::FILENAME_COOKIE = "long";
const int LFNIndex::FILENAME_PREFIX_LEN =  FILENAME_SHORT_LEN - FILENAME_HASH_LEN -
								FILENAME_COOKIE.size() -
								FILENAME_EXTRA;
void LFNIndex::maybe_inject_failure()
{
  if (error_injection_enabled) {
    if (current_failure > last_failure &&
	(((double)(rand() % 10000))/((double)(10000))
	 < error_injection_probability)) {
      last_failure = current_failure;
      current_failure = 0;
      throw RetryException();
    }
    ++current_failure;
  }
}

// Helper to close fd's when we leave scope.  This is useful when used
// in combination with RetryException, thrown by the above.
struct FDCloser {
  int fd;
  explicit FDCloser(int f) : fd(f) {}
  ~FDCloser() {
    VOID_TEMP_FAILURE_RETRY(::close(fd));
  }
};


/* Public methods */

uint64_t LFNIndex::get_max_escaped_name_len(const hobject_t &obj)
{
  ghobject_t ghobj(obj);
  ghobj.shard_id = shard_id_t(0);
  ghobj.generation = 0;
  ghobj.hobj.snap = 0;
  return lfn_generate_object_name_current(ghobj).size();
}

int LFNIndex::init()
{
  return _init();
}

int LFNIndex::created(const ghobject_t &oid, const char *path)
{
  WRAP_RETRY(
  vector<string> path_comp;
  string short_name;
  r = decompose_full_path(path, &path_comp, 0, &short_name);
  if (r < 0)
    goto out;
  r = lfn_created(path_comp, oid, short_name);
  if (r < 0) {
    if (failed) {
      /* This is hacky, but the only way we get ENOENT from lfn_created here is
       * if we did a failure injection in _created below AND actually started the
       * split or merge.  In that case, lfn_created already suceeded, and
       * WRAP_RETRY already cleaned it up and we are actually done.  In a real
       * failure, the filestore itself would have ended up calling this with
       * the new path, not the old one, so we'd find it.
       */
      r = 0;
    }
    goto out;
  }
  r = _created(path_comp, oid, short_name);
  if (r < 0)
    goto out;
    );
}

int LFNIndex::unlink(const ghobject_t &oid)
{
  WRAP_RETRY(
  vector<string> path;
  string short_name;
  r = _lookup(oid, &path, &short_name, NULL);
  if (r < 0) {
    goto out;
  }
  r = _remove(path, oid, short_name);
  if (r < 0) {
    goto out;
  }
  );
}

int LFNIndex::lookup(const ghobject_t &oid,
		     IndexedPath *out_path,
		     int *hardlink)
{
  WRAP_RETRY(
  vector<string> path;
  string short_name;
  r = _lookup(oid, &path, &short_name, hardlink);
  if (r < 0)
    goto out;
  string full_path = get_full_path(path, short_name);
  *out_path = std::make_shared<Path>(full_path, this);
  r = 0;
  );
}

int LFNIndex::pre_hash_collection(uint32_t pg_num, uint64_t expected_num_objs)
{
  return _pre_hash_collection(pg_num, expected_num_objs);
}


int LFNIndex::collection_list_partial(const ghobject_t &start,
				      const ghobject_t &end,
				      int max_count,
				      vector<ghobject_t> *ls,
				      ghobject_t *next)
{
  return _collection_list_partial(start, end, max_count, ls, next);
}

/* Derived class utility methods */

int LFNIndex::fsync_dir(const vector<string> &path)
{
  maybe_inject_failure();
  int fd = ::open(get_full_path_subdir(path).c_str(), O_RDONLY|O_CLOEXEC);
  if (fd < 0)
    return -errno;
  FDCloser f(fd);
  maybe_inject_failure();
  int r = ::fsync(fd);
  maybe_inject_failure();
  if (r < 0) {
    derr << __func__ << " fsync failed: " << cpp_strerror(errno) << dendl;
    ceph_abort();
  }
  return 0;
}

int LFNIndex::link_object(const vector<string> &from,
			  const vector<string> &to,
			  const ghobject_t &oid,
			  const string &from_short_name)
{
  int r;
  string from_path = get_full_path(from, from_short_name);
  string to_path;
  maybe_inject_failure();
  r = lfn_get_name(to, oid, 0, &to_path, 0);
  if (r < 0)
    return r;
  maybe_inject_failure();
  r = ::link(from_path.c_str(), to_path.c_str());
  maybe_inject_failure();
  if (r < 0)
    return -errno;
  else
    return 0;
}

int LFNIndex::remove_objects(const vector<string> &dir,
			     const map<string, ghobject_t> &to_remove,
			     map<string, ghobject_t> *remaining)
{
  set<string> clean_chains;
  for (map<string, ghobject_t>::const_iterator to_clean = to_remove.begin();
       to_clean != to_remove.end();
       ++to_clean) {
    if (!lfn_is_hashed_filename(to_clean->first)) {
      maybe_inject_failure();
      int r = ::unlink(get_full_path(dir, to_clean->first).c_str());
      maybe_inject_failure();
      if (r < 0)
	return -errno;
      continue;
    }
    if (clean_chains.count(lfn_get_short_name(to_clean->second, 0)))
      continue;
    set<int> holes;
    map<int, pair<string, ghobject_t> > chain;
    for (int i = 0; ; ++i) {
      string short_name = lfn_get_short_name(to_clean->second, i);
      if (remaining->count(short_name)) {
	chain[i] = *(remaining->find(short_name));
      } else if (to_remove.count(short_name)) {
	holes.insert(i);
      } else {
	break;
      }
    }

    map<int, pair<string, ghobject_t > >::reverse_iterator candidate = chain.rbegin();
    for (set<int>::iterator i = holes.begin();
	 i != holes.end();
	 ++i) {
      if (candidate == chain.rend() || *i > candidate->first) {
	string remove_path_name =
	  get_full_path(dir, lfn_get_short_name(to_clean->second, *i));
	maybe_inject_failure();
	int r = ::unlink(remove_path_name.c_str());
	maybe_inject_failure();
	if (r < 0)
	  return -errno;
	continue;
      }
      string from = get_full_path(dir, candidate->second.first);
      string to = get_full_path(dir, lfn_get_short_name(candidate->second.second, *i));
      maybe_inject_failure();
      int r = ::rename(from.c_str(), to.c_str());
      maybe_inject_failure();
      if (r < 0)
	return -errno;
      remaining->erase(candidate->second.first);
      remaining->insert(pair<string, ghobject_t>(
			  lfn_get_short_name(candidate->second.second, *i),
					     candidate->second.second));
      ++candidate;
    }
    if (!holes.empty())
      clean_chains.insert(lfn_get_short_name(to_clean->second, 0));
  }
  return 0;
}

int LFNIndex::move_objects(const vector<string> &from,
			   const vector<string> &to)
{
  map<string, ghobject_t> to_move;
  int r;
  r = list_objects(from, 0, NULL, &to_move);
  if (r < 0)
    return r;
  for (map<string,ghobject_t>::iterator i = to_move.begin();
       i != to_move.end();
       ++i) {
    string from_path = get_full_path(from, i->first);
    string to_path, to_name;
    r = lfn_get_name(to, i->second, &to_name, &to_path, 0);
    if (r < 0)
      return r;
    maybe_inject_failure();
    r = ::link(from_path.c_str(), to_path.c_str());
    if (r < 0 && errno != EEXIST)
      return -errno;
    maybe_inject_failure();
    r = lfn_created(to, i->second, to_name);
    maybe_inject_failure();
    if (r < 0)
      return r;
  }
  r = fsync_dir(to);
  if (r < 0)
    return r;
  for (map<string,ghobject_t>::iterator i = to_move.begin();
       i != to_move.end();
       ++i) {
    maybe_inject_failure();
    r = ::unlink(get_full_path(from, i->first).c_str());
    maybe_inject_failure();
    if (r < 0)
      return -errno;
  }
  return fsync_dir(from);
}

int LFNIndex::remove_object(const vector<string> &from,
			    const ghobject_t &oid)
{
  string short_name;
  int r, exist;
  maybe_inject_failure();
  r = get_mangled_name(from, oid, &short_name, &exist);
  maybe_inject_failure();
  if (r < 0)
    return r;
  if (exist == 0)
    return -ENOENT;
  return lfn_unlink(from, oid, short_name);
}

int LFNIndex::get_mangled_name(const vector<string> &from,
			       const ghobject_t &oid,
			       string *mangled_name, int *hardlink)
{
  return lfn_get_name(from, oid, mangled_name, 0, hardlink);
}

int LFNIndex::move_subdir(
  LFNIndex &from,
  LFNIndex &dest,
  const vector<string> &path,
  string dir
  )
{
  vector<string> sub_path(path.begin(), path.end());
  sub_path.push_back(dir);
  string from_path(from.get_full_path_subdir(sub_path));
  string to_path(dest.get_full_path_subdir(sub_path));
  int r = ::rename(from_path.c_str(), to_path.c_str());
  if (r < 0)
    return -errno;
  return 0;
}

int LFNIndex::move_object(
  LFNIndex &from,
  LFNIndex &dest,
  const vector<string> &path,
  const pair<string, ghobject_t> &obj
  )
{
  string from_path(from.get_full_path(path, obj.first));
  string to_path;
  string to_name;
  int exists;
  int r = dest.lfn_get_name(path, obj.second, &to_name, &to_path, &exists);
  if (r < 0)
    return r;
  if (!exists) {
    r = ::link(from_path.c_str(), to_path.c_str());
    if (r < 0)
      return r;
  }
  r = dest.lfn_created(path, obj.second, to_name);
  if (r < 0)
    return r;
  r = dest.fsync_dir(path);
  if (r < 0)
    return r;
  r = from.remove_object(path, obj.second);
  if (r < 0)
    return r;
  return from.fsync_dir(path);
}


static int get_hobject_from_oinfo(const char *dir, const char *file,
				  ghobject_t *o)
{
  char path[PATH_MAX];
  snprintf(path, sizeof(path), "%s/%s", dir, file);
  // Hack, user.ceph._ is the attribute used to store the object info
  bufferptr bp;
  int r = chain_getxattr_buf(
    path,
    "user.ceph._",
    &bp);
  if (r < 0)
    return r;
  bufferlist bl;
  if (r > 0)
    bl.push_back(bp);
  object_info_t oi(bl);
  *o = ghobject_t(oi.soid);
  return 0;
}


int LFNIndex::list_objects(const vector<string> &to_list, int max_objs,
			   long *handle, map<string, ghobject_t> *out)
{
  string to_list_path = get_full_path_subdir(to_list);
  DIR *dir = ::opendir(to_list_path.c_str());
  if (!dir) {
    return -errno;
  }

  if (handle && *handle) {
    seekdir(dir, *handle);
  }

  struct dirent *de = nullptr;
  int r = 0;
  int listed = 0;
  bool end = true;
  while ((de = ::readdir(dir))) {
    end = false;
    if (max_objs > 0 && listed >= max_objs) {
      break;
    }
    if (de->d_name[0] == '.')
      continue;
    string short_name(de->d_name);
    ghobject_t obj;
    if (lfn_is_object(short_name)) {
      r = lfn_translate(to_list, short_name, &obj);
      if (r == -EINVAL) {
	continue;
      } else if (r < 0) {
	goto cleanup;
      } else {
	string long_name = lfn_generate_object_name(obj);
	if (!lfn_must_hash(long_name)) {
	  assert(long_name == short_name);
	}
	if (index_version == HASH_INDEX_TAG)
	  get_hobject_from_oinfo(to_list_path.c_str(), short_name.c_str(), &obj);

	out->insert(pair<string, ghobject_t>(short_name, obj));
	++listed;
      }
    }
  }

  if (handle && !end) {
    *handle = telldir(dir);
  }

  r = 0;
 cleanup:
  ::closedir(dir);
  return r;
}

int LFNIndex::list_subdirs(const vector<string> &to_list,
			   vector<string> *out)
{
  string to_list_path = get_full_path_subdir(to_list);
  DIR *dir = ::opendir(to_list_path.c_str());
  if (!dir)
    return -errno;

  struct dirent *de = nullptr;
  while ((de = ::readdir(dir))) {
    string short_name(de->d_name);
    string demangled_name;
    if (lfn_is_subdir(short_name, &demangled_name)) {
      out->push_back(demangled_name);
    }
  }

  ::closedir(dir);
  return 0;
}

int LFNIndex::create_path(const vector<string> &to_create)
{
  maybe_inject_failure();
  int r = ::mkdir(get_full_path_subdir(to_create).c_str(), 0777);
  maybe_inject_failure();
  if (r < 0)
    return -errno;
  else
    return 0;
}

int LFNIndex::remove_path(const vector<string> &to_remove)
{
  maybe_inject_failure();
  int r = ::rmdir(get_full_path_subdir(to_remove).c_str());
  maybe_inject_failure();
  if (r < 0)
    return -errno;
  else
    return 0;
}

int LFNIndex::path_exists(const vector<string> &to_check, int *exists)
{
  string full_path = get_full_path_subdir(to_check);
  struct stat buf;
  if (::stat(full_path.c_str(), &buf)) {
    int r = -errno;
    if (r == -ENOENT) {
      *exists = 0;
      return 0;
    } else {
      return r;
    }
  } else {
    *exists = 1;
    return 0;
  }
}

int LFNIndex::add_attr_path(const vector<string> &path,
			    const string &attr_name,
			    bufferlist &attr_value)
{
  string full_path = get_full_path_subdir(path);
  maybe_inject_failure();
  return chain_setxattr<false, true>(
    full_path.c_str(), mangle_attr_name(attr_name).c_str(),
    reinterpret_cast<void *>(attr_value.c_str()),
    attr_value.length());
}

int LFNIndex::get_attr_path(const vector<string> &path,
			    const string &attr_name,
			    bufferlist &attr_value)
{
  string full_path = get_full_path_subdir(path);
  bufferptr bp;
  int r = chain_getxattr_buf(
    full_path.c_str(),
    mangle_attr_name(attr_name).c_str(),
    &bp);
  if (r > 0)
    attr_value.push_back(bp);
  return r;
}

int LFNIndex::remove_attr_path(const vector<string> &path,
			       const string &attr_name)
{
  string full_path = get_full_path_subdir(path);
  string mangled_attr_name = mangle_attr_name(attr_name);
  maybe_inject_failure();
  return chain_removexattr(full_path.c_str(), mangled_attr_name.c_str());
}

string LFNIndex::lfn_generate_object_name_keyless(const ghobject_t &oid)
{
  char s[FILENAME_MAX_LEN];
  char *end = s + sizeof(s);
  char *t = s;

  assert(oid.generation == ghobject_t::NO_GEN);
  const char *i = oid.hobj.oid.name.c_str();
  // Escape subdir prefix
  if (oid.hobj.oid.name.substr(0, 4) == "DIR_") {
    *t++ = '\\';
    *t++ = 'd';
    i += 4;
  }
  while (*i && t < end) {
    if (*i == '\\') {
      *t++ = '\\';
      *t++ = '\\';
    } else if (*i == '.' && i == oid.hobj.oid.name.c_str()) {  // only escape leading .
      *t++ = '\\';
      *t++ = '.';
    } else if (*i == '/') {
      *t++ = '\\';
      *t++ = 's';
    } else
      *t++ = *i;
    i++;
  }

  if (oid.hobj.snap == CEPH_NOSNAP)
    t += snprintf(t, end - t, "_head");
  else if (oid.hobj.snap == CEPH_SNAPDIR)
    t += snprintf(t, end - t, "_snapdir");
  else
    t += snprintf(t, end - t, "_%llx", (long long unsigned)oid.hobj.snap);
  snprintf(t, end - t, "_%.*X", (int)(sizeof(oid.hobj.get_hash())*2), oid.hobj.get_hash());

  return string(s);
}

static void append_escaped(string::const_iterator begin,
			   string::const_iterator end,
			   string *out)
{
  for (string::const_iterator i = begin; i != end; ++i) {
    if (*i == '\\') {
      out->append("\\\\");
    } else if (*i == '/') {
      out->append("\\s");
    } else if (*i == '_') {
      out->append("\\u");
    } else if (*i == '\0') {
      out->append("\\n");
    } else {
      out->append(i, i+1);
    }
  }
}

string LFNIndex::lfn_generate_object_name_current(const ghobject_t &oid)
{
  string full_name;
  string::const_iterator i = oid.hobj.oid.name.begin();
  if (oid.hobj.oid.name.substr(0, 4) == "DIR_") {
    full_name.append("\\d");
    i += 4;
  } else if (oid.hobj.oid.name[0] == '.') {
    full_name.append("\\.");
    ++i;
  }
  append_escaped(i, oid.hobj.oid.name.end(), &full_name);
  full_name.append("_");
  append_escaped(oid.hobj.get_key().begin(), oid.hobj.get_key().end(), &full_name);
  full_name.append("_");

  char buf[PATH_MAX];
  char *t = buf;
  const char *end = t + sizeof(buf);
  if (oid.hobj.snap == CEPH_NOSNAP)
    t += snprintf(t, end - t, "head");
  else if (oid.hobj.snap == CEPH_SNAPDIR)
    t += snprintf(t, end - t, "snapdir");
  else
    t += snprintf(t, end - t, "%llx", (long long unsigned)oid.hobj.snap);
  t += snprintf(t, end - t, "_%.*X", (int)(sizeof(oid.hobj.get_hash())*2), oid.hobj.get_hash());
  full_name.append(buf, t);
  full_name.append("_");

  append_escaped(oid.hobj.nspace.begin(), oid.hobj.nspace.end(), &full_name);
  full_name.append("_");

  t = buf;
  if (oid.hobj.pool == -1)
    t += snprintf(t, end - t, "none");
  else
    t += snprintf(t, end - t, "%llx", (long long unsigned)oid.hobj.pool);
  full_name.append(buf, t);

  if (oid.generation != ghobject_t::NO_GEN ||
      oid.shard_id != shard_id_t::NO_SHARD) {
    full_name.append("_");

    t = buf;
    t += snprintf(t, end - buf, "%llx", (long long unsigned)oid.generation);
    full_name.append(buf, t);

    full_name.append("_");

    t = buf;
    t += snprintf(t, end - buf, "%x", (int)oid.shard_id);
    full_name.append(buf, t);
  }

  return full_name;
}

string LFNIndex::lfn_generate_object_name_poolless(const ghobject_t &oid)
{
  if (index_version == HASH_INDEX_TAG)
    return lfn_generate_object_name_keyless(oid);

  assert(oid.generation == ghobject_t::NO_GEN);
  string full_name;
  string::const_iterator i = oid.hobj.oid.name.begin();
  if (oid.hobj.oid.name.substr(0, 4) == "DIR_") {
    full_name.append("\\d");
    i += 4;
  } else if (oid.hobj.oid.name[0] == '.') {
    full_name.append("\\.");
    ++i;
  }
  append_escaped(i, oid.hobj.oid.name.end(), &full_name);
  full_name.append("_");
  append_escaped(oid.hobj.get_key().begin(), oid.hobj.get_key().end(), &full_name);
  full_name.append("_");

  char snap_with_hash[PATH_MAX];
  char *t = snap_with_hash;
  char *end = t + sizeof(snap_with_hash);
  if (oid.hobj.snap == CEPH_NOSNAP)
    t += snprintf(t, end - t, "head");
  else if (oid.hobj.snap == CEPH_SNAPDIR)
    t += snprintf(t, end - t, "snapdir");
  else
    t += snprintf(t, end - t, "%llx", (long long unsigned)oid.hobj.snap);
  snprintf(t, end - t, "_%.*X", (int)(sizeof(oid.hobj.get_hash())*2), oid.hobj.get_hash());
  full_name += string(snap_with_hash);
  return full_name;
}

int LFNIndex::lfn_get_name(const vector<string> &path,
			   const ghobject_t &oid,
			   string *mangled_name, string *out_path,
			   int *hardlink)
{
  string full_name = lfn_generate_object_name(oid);
  int r;

  if (!lfn_must_hash(full_name)) {
    if (mangled_name)
      *mangled_name = full_name;
    if (out_path)
      *out_path = get_full_path(path, full_name);
    if (hardlink) {
      struct stat buf;
      string full_path = get_full_path(path, full_name);
      maybe_inject_failure();
      r = ::stat(full_path.c_str(), &buf);
      if (r < 0) {
	if (errno == ENOENT)
	  *hardlink = 0;
	else
	  return -errno;
      } else {
	*hardlink = buf.st_nlink;
      }
    }
    return 0;
  }

  int i = 0;
  string candidate;
  string candidate_path;
  for ( ; ; ++i) {
    candidate = lfn_get_short_name(oid, i);
    candidate_path = get_full_path(path, candidate);
    bufferptr bp;
    r = chain_getxattr_buf(
      candidate_path.c_str(),
      get_lfn_attr().c_str(),
      &bp);
    if (r < 0) {
      if (errno != ENODATA && errno != ENOENT)
	return -errno;
      if (errno == ENODATA) {
	// Left over from incomplete transaction, it'll be replayed
	maybe_inject_failure();
	r = ::unlink(candidate_path.c_str());
	maybe_inject_failure();
	if (r < 0)
	  return -errno;
      }
      if (mangled_name)
	*mangled_name = candidate;
      if (out_path)
	*out_path = candidate_path;
      if (hardlink)
	*hardlink = 0;
      return 0;
    }
    assert(r > 0);
    string lfn(bp.c_str(), bp.length());
    if (lfn == full_name) {
      if (mangled_name)
	*mangled_name = candidate;
      if (out_path)
	*out_path = candidate_path;
      if (hardlink) {
	struct stat st;
	r = ::stat(candidate_path.c_str(), &st);
        if (r < 0) {
          if (errno == ENOENT)
            *hardlink = 0;
          else
            return -errno;
        } else {
	  *hardlink = st.st_nlink;
	}
      }
      return 0;
    }
    bp = bufferptr();
    r = chain_getxattr_buf(
      candidate_path.c_str(),
      get_alt_lfn_attr().c_str(),
      &bp);
    if (r > 0) {
      // only consider alt name if nlink > 1
      struct stat st;
      int rc = ::stat(candidate_path.c_str(), &st);
      if (rc < 0)
	return -errno;
      if (st.st_nlink <= 1) {
	// left over from incomplete unlink, remove
	maybe_inject_failure();
	dout(20) << __func__ << " found extra alt attr for " << candidate_path
		 << ", long name " << string(bp.c_str(), bp.length()) << dendl;
	rc = chain_removexattr(candidate_path.c_str(),
			       get_alt_lfn_attr().c_str());
	maybe_inject_failure();
	if (rc < 0)
	  return rc;
	continue;
      }
      string lfn(bp.c_str(), bp.length());
      if (lfn == full_name) {
	dout(20) << __func__ << " used alt attr for " << full_name << dendl;
	if (mangled_name)
	  *mangled_name = candidate;
	if (out_path)
	  *out_path = candidate_path;
	if (hardlink)
	  *hardlink = st.st_nlink;
	return 0;
      }
    }
  }
  ceph_abort(); // Unreachable
  return 0;
}

int LFNIndex::lfn_created(const vector<string> &path,
			  const ghobject_t &oid,
			  const string &mangled_name)
{
  if (!lfn_is_hashed_filename(mangled_name))
    return 0;
  string full_path = get_full_path(path, mangled_name);
  string full_name = lfn_generate_object_name(oid);
  maybe_inject_failure();

  // if the main attr exists and is different, move it to the alt attr.
  bufferptr bp;
  int r = chain_getxattr_buf(
    full_path.c_str(),
    get_lfn_attr().c_str(),
    &bp);
  if (r > 0) {
    string lfn(bp.c_str(), bp.length());
    if (lfn != full_name) {
      dout(20) << __func__ << " " << mangled_name
	       << " moving old name to alt attr "
	       << lfn
	       << ", new name is " << full_name << dendl;
      r = chain_setxattr<false, true>(
	full_path.c_str(), get_alt_lfn_attr().c_str(),
	bp.c_str(), bp.length());
      if (r < 0)
	return r;
    }
  }

  return chain_setxattr<false, true>(
    full_path.c_str(), get_lfn_attr().c_str(),
    full_name.c_str(), full_name.size());
}

int LFNIndex::lfn_unlink(const vector<string> &path,
			 const ghobject_t &oid,
			 const string &mangled_name)
{
  if (!lfn_is_hashed_filename(mangled_name)) {
    string full_path = get_full_path(path, mangled_name);
    maybe_inject_failure();
    int r = ::unlink(full_path.c_str());
    maybe_inject_failure();
    if (r < 0)
      return -errno;
    return 0;
  }

  int i = 0;
  for ( ; ; ++i) {
    string candidate = lfn_get_short_name(oid, i);
    if (candidate == mangled_name)
      break;
  }
  int removed_index = i;
  ++i;
  for ( ; ; ++i) {
    struct stat buf;
    string to_check = lfn_get_short_name(oid, i);
    string to_check_path = get_full_path(path, to_check);
    int r = ::stat(to_check_path.c_str(), &buf);
    if (r < 0) {
      if (errno == ENOENT) {
	break;
      } else {
	return -errno;
      }
    }
  }
  string full_path = get_full_path(path, mangled_name);
  int fd = ::open(full_path.c_str(), O_RDONLY|O_CLOEXEC);
  if (fd < 0)
    return -errno;
  FDCloser f(fd);
  if (i == removed_index + 1) {
    maybe_inject_failure();
    int r = ::unlink(full_path.c_str());
    maybe_inject_failure();
    if (r < 0)
      return -errno;
  } else {
    string& rename_to = full_path;
    string rename_from = get_full_path(path, lfn_get_short_name(oid, i - 1));
    maybe_inject_failure();
    int r = ::rename(rename_from.c_str(), rename_to.c_str());
    maybe_inject_failure();
    if (r < 0)
      return -errno;
  }
  struct stat st;
  int r = ::fstat(fd, &st);
  if (r == 0 && st.st_nlink > 0) {
    // remove alt attr
    dout(20) << __func__ << " removing alt attr from " << full_path << dendl;
    fsync_dir(path);
    chain_fremovexattr(fd, get_alt_lfn_attr().c_str());
  }
  return r;
}

int LFNIndex::lfn_translate(const vector<string> &path,
			    const string &short_name,
			    ghobject_t *out)
{
  if (!lfn_is_hashed_filename(short_name)) {
    return lfn_parse_object_name(short_name, out);
  }
  string full_path = get_full_path(path, short_name);
  // First, check alt attr
  bufferptr bp;
  int r = chain_getxattr_buf(
    full_path.c_str(),
    get_alt_lfn_attr().c_str(),
    &bp);
  if (r > 0) {
    // There is an alt attr, does it match?
    string lfn(bp.c_str(), bp.length());
    if (short_name_matches(short_name.c_str(), lfn.c_str())) {
      return lfn_parse_object_name(lfn, out);
    }
  }

  // Get lfn_attr
  bp = bufferptr();
  r = chain_getxattr_buf(
    full_path.c_str(),
    get_lfn_attr().c_str(),
    &bp);
  if (r < 0)
    return r;
  if (r == 0)
    return -EINVAL;

  string long_name(bp.c_str(), bp.length());
  return lfn_parse_object_name(long_name, out);
}

bool LFNIndex::lfn_is_object(const string &short_name)
{
  return lfn_is_hashed_filename(short_name) || !lfn_is_subdir(short_name, 0);
}

bool LFNIndex::lfn_is_subdir(const string &name, string *demangled)
{
  if (name.substr(0, SUBDIR_PREFIX.size()) == SUBDIR_PREFIX) {
    if (demangled)
      *demangled = demangle_path_component(name);
    return 1;
  }
  return 0;
}

static int parse_object(const char *s, ghobject_t& o)
{
  const char *hash = s + strlen(s) - 1;
  while (*hash != '_' &&
	 hash > s)
    hash--;
  const char *bar = hash - 1;
  while (*bar != '_' &&
	 bar > s)
    bar--;
  if (*bar == '_') {
    char buf[bar-s + 1];
    char *t = buf;
    const char *i = s;
    while (i < bar) {
      if (*i == '\\') {
	i++;
	switch (*i) {
	case '\\': *t++ = '\\'; break;
	case '.': *t++ = '.'; break;
	case 's': *t++ = '/'; break;
	case 'd': {
	  *t++ = 'D';
	  *t++ = 'I';
	  *t++ = 'R';
	  *t++ = '_';
	  break;
	}
	default: ceph_abort();
	}
      } else {
	*t++ = *i;
      }
      i++;
    }
    *t = 0;
    o.hobj.oid.name = string(buf, t-buf);
    if (strncmp(bar+1, "head", 4) == 0)
      o.hobj.snap = CEPH_NOSNAP;
    else if (strncmp(bar+1, "snapdir", 7) == 0)
      o.hobj.snap = CEPH_SNAPDIR;
    else
      o.hobj.snap = strtoull(bar+1, NULL, 16);

    uint32_t hobject_hash_input;
    sscanf(hash, "_%X", &hobject_hash_input);
    o.hobj.set_hash(hobject_hash_input);

    return 1;
  }
  return 0;
}

int LFNIndex::lfn_parse_object_name_keyless(const string &long_name, ghobject_t *out)
{
  int r = parse_object(long_name.c_str(), *out);
  int64_t pool = -1;
  spg_t pg;
  if (coll().is_pg_prefix(&pg))
    pool = (int64_t)pg.pgid.pool();
  out->hobj.pool = pool;
  if (!r) return -EINVAL;
  string temp = lfn_generate_object_name(*out);
  return r ? 0 : -EINVAL;
}

static bool append_unescaped(string::const_iterator begin,
			     string::const_iterator end,
			     string *out)
{
  for (string::const_iterator i = begin; i != end; ++i) {
    if (*i == '\\') {
      ++i;
      if (*i == '\\')
	out->append("\\");
      else if (*i == 's')
	out->append("/");
      else if (*i == 'n')
	(*out) += '\0';
      else if (*i == 'u')
	out->append("_");
      else
	return false;
    } else {
      out->append(i, i+1);
    }
  }
  return true;
}

int LFNIndex::lfn_parse_object_name_poolless(const string &long_name,
					     ghobject_t *out)
{
  string name;
  string key;
  uint32_t hash;
  snapid_t snap;

  string::const_iterator current = long_name.begin();
  if (*current == '\\') {
    ++current;
    if (current == long_name.end()) {
      return -EINVAL;
    } else if (*current == 'd') {
      name.append("DIR_");
      ++current;
    } else if (*current == '.') {
      name.append(".");
      ++current;
    } else {
      --current;
    }
  }

  string::const_iterator end = current;
  for ( ; end != long_name.end() && *end != '_'; ++end) ;
  if (end == long_name.end())
    return -EINVAL;
  if (!append_unescaped(current, end, &name))
    return -EINVAL;

  current = ++end;
  for ( ; end != long_name.end() && *end != '_'; ++end) ;
  if (end == long_name.end())
    return -EINVAL;
  if (!append_unescaped(current, end, &key))
    return -EINVAL;

  current = ++end;
  for ( ; end != long_name.end() && *end != '_'; ++end) ;
  if (end == long_name.end())
    return -EINVAL;
  string snap_str(current, end);

  current = ++end;
  for ( ; end != long_name.end() && *end != '_'; ++end) ;
  if (end != long_name.end())
    return -EINVAL;
  string hash_str(current, end);

  if (snap_str == "head")
    snap = CEPH_NOSNAP;
  else if (snap_str == "snapdir")
    snap = CEPH_SNAPDIR;
  else
    snap = strtoull(snap_str.c_str(), NULL, 16);
  sscanf(hash_str.c_str(), "%X", &hash);


  int64_t pool = -1;
  spg_t pg;
  if (coll().is_pg_prefix(&pg))
    pool = (int64_t)pg.pgid.pool();
  (*out) = ghobject_t(hobject_t(name, key, snap, hash, pool, ""));
  return 0;
}


int LFNIndex::lfn_parse_object_name(const string &long_name, ghobject_t *out)
{
  string name;
  string key;
  string ns;
  uint32_t hash;
  snapid_t snap;
  uint64_t pool;
  gen_t generation = ghobject_t::NO_GEN;
  shard_id_t shard_id = shard_id_t::NO_SHARD;

  if (index_version == HASH_INDEX_TAG)
    return lfn_parse_object_name_keyless(long_name, out);
  if (index_version == HASH_INDEX_TAG_2)
    return lfn_parse_object_name_poolless(long_name, out);

  string::const_iterator current = long_name.begin();
  if (*current == '\\') {
    ++current;
    if (current == long_name.end()) {
      return -EINVAL;
    } else if (*current == 'd') {
      name.append("DIR_");
      ++current;
    } else if (*current == '.') {
      name.append(".");
      ++current;
    } else {
      --current;
    }
  }

  string::const_iterator end = current;
  for ( ; end != long_name.end() && *end != '_'; ++end) ;
  if (end == long_name.end())
    return -EINVAL;
  if (!append_unescaped(current, end, &name))
    return -EINVAL;

  current = ++end;
  for ( ; end != long_name.end() && *end != '_'; ++end) ;
  if (end == long_name.end())
    return -EINVAL;
  if (!append_unescaped(current, end, &key))
    return -EINVAL;

  current = ++end;
  for ( ; end != long_name.end() && *end != '_'; ++end) ;
  if (end == long_name.end())
    return -EINVAL;
  string snap_str(current, end);

  current = ++end;
  for ( ; end != long_name.end() && *end != '_'; ++end) ;
  if (end == long_name.end())
    return -EINVAL;
  string hash_str(current, end);

  current = ++end;
  for ( ; end != long_name.end() && *end != '_'; ++end) ;
  if (end == long_name.end())
    return -EINVAL;
  if (!append_unescaped(current, end, &ns))
    return -EINVAL;

  current = ++end;
  for ( ; end != long_name.end() && *end != '_'; ++end) ;
  string pstring(current, end);

  // Optional generation/shard_id
  string genstring, shardstring;
  if (end != long_name.end()) {
    current = ++end;
    for ( ; end != long_name.end() && *end != '_'; ++end) ;
    if (end == long_name.end())
      return -EINVAL;
    genstring = string(current, end);

    generation = (gen_t)strtoull(genstring.c_str(), NULL, 16);

    current = ++end;
    for ( ; end != long_name.end() && *end != '_'; ++end) ;
    if (end != long_name.end())
      return -EINVAL;
    shardstring = string(current, end);

    shard_id = (shard_id_t)strtoul(shardstring.c_str(), NULL, 16);
  }

  if (snap_str == "head")
    snap = CEPH_NOSNAP;
  else if (snap_str == "snapdir")
    snap = CEPH_SNAPDIR;
  else
    snap = strtoull(snap_str.c_str(), NULL, 16);
  sscanf(hash_str.c_str(), "%X", &hash);

  if (pstring == "none")
    pool = (uint64_t)-1;
  else
    pool = strtoull(pstring.c_str(), NULL, 16);

  (*out) = ghobject_t(hobject_t(name, key, snap, hash, (int64_t)pool, ns), generation, shard_id);
  return 0;
}

bool LFNIndex::lfn_is_hashed_filename(const string &name)
{
  if (name.size() < (unsigned)FILENAME_SHORT_LEN) {
    return 0;
  }
  if (name.substr(name.size() - FILENAME_COOKIE.size(), FILENAME_COOKIE.size())
      == FILENAME_COOKIE) {
    return 1;
  } else {
    return 0;
  }
}

bool LFNIndex::lfn_must_hash(const string &long_name)
{
  return (int)long_name.size() >= FILENAME_SHORT_LEN;
}

static inline void buf_to_hex(const unsigned char *buf, int len, char *str)
{
  int i;
  str[0] = '\0';
  for (i = 0; i < len; i++) {
    sprintf(&str[i*2], "%02x", (int)buf[i]);
  }
}

int LFNIndex::hash_filename(const char *filename, char *hash, int buf_len)
{
  if (buf_len < FILENAME_HASH_LEN + 1)
    return -EINVAL;

  char buf[FILENAME_LFN_DIGEST_SIZE];
  char hex[FILENAME_LFN_DIGEST_SIZE * 2];

  SHA1 h;
  h.Update((const byte *)filename, strlen(filename));
  h.Final((byte *)buf);

  buf_to_hex((byte *)buf, (FILENAME_HASH_LEN + 1) / 2, hex);
  strncpy(hash, hex, FILENAME_HASH_LEN);
  hash[FILENAME_HASH_LEN] = '\0';
  return 0;
}

void LFNIndex::build_filename(const char *old_filename, int i, char *filename, int len)
{
  char hash[FILENAME_HASH_LEN + 1];

  assert(len >= FILENAME_SHORT_LEN + 4);

  strncpy(filename, old_filename, FILENAME_PREFIX_LEN);
  filename[FILENAME_PREFIX_LEN] = '\0';
  if ((int)strlen(filename) < FILENAME_PREFIX_LEN)
    return;
  if (old_filename[FILENAME_PREFIX_LEN] == '\0')
    return;

  hash_filename(old_filename, hash, sizeof(hash));
  int ofs = FILENAME_PREFIX_LEN;
  while (1) {
    int suffix_len = sprintf(filename + ofs, "_%s_%d_%s", hash, i, FILENAME_COOKIE.c_str());
    if (ofs + suffix_len <= FILENAME_SHORT_LEN || !ofs)
      break;
    ofs--;
  }
}

bool LFNIndex::short_name_matches(const char *short_name, const char *cand_long_name)
{
  const char *end = short_name;
  while (*end) ++end;
  const char *suffix = end;
  if (suffix > short_name)  --suffix;                   // last char
  while (suffix > short_name && *suffix != '_') --suffix; // back to first _
  if (suffix > short_name) --suffix;                   // one behind that
  while (suffix > short_name && *suffix != '_') --suffix; // back to second _

  int index = -1;
  char buf[FILENAME_SHORT_LEN + 4];
  assert((end - suffix) < (int)sizeof(buf));
  int r = sscanf(suffix, "_%d_%s", &index, buf);
  if (r < 2)
    return false;
  if (strcmp(buf, FILENAME_COOKIE.c_str()) != 0)
    return false;
  build_filename(cand_long_name, index, buf, sizeof(buf));
  return strcmp(short_name, buf) == 0;
}

string LFNIndex::lfn_get_short_name(const ghobject_t &oid, int i)
{
  string long_name = lfn_generate_object_name(oid);
  assert(lfn_must_hash(long_name));
  char buf[FILENAME_SHORT_LEN + 4];
  build_filename(long_name.c_str(), i, buf, sizeof(buf));
  return string(buf);
}

const string &LFNIndex::get_base_path()
{
  return base_path;
}

string LFNIndex::get_full_path_subdir(const vector<string> &rel)
{
  string retval = get_base_path();
  for (vector<string>::const_iterator i = rel.begin();
       i != rel.end();
       ++i) {
    retval += "/";
    retval += mangle_path_component(*i);
  }
  return retval;
}

string LFNIndex::get_full_path(const vector<string> &rel, const string &name)
{
  return get_full_path_subdir(rel) + "/" + name;
}

string LFNIndex::mangle_path_component(const string &component)
{
  return SUBDIR_PREFIX + component;
}

string LFNIndex::demangle_path_component(const string &component)
{
  return component.substr(SUBDIR_PREFIX.size(), component.size() - SUBDIR_PREFIX.size());
}

int LFNIndex::decompose_full_path(const char *in, vector<string> *out,
				  ghobject_t *oid, string *shortname)
{
  const char *beginning = in + get_base_path().size();
  const char *end = beginning;
  while (1) {
    end++;
    beginning = end++;
    for ( ; *end != '\0' && *end != '/'; ++end) ;
    if (*end != '\0') {
      out->push_back(demangle_path_component(string(beginning, end - beginning)));
      continue;
    } else {
      break;
    }
  }
  *shortname = string(beginning, end - beginning);
  if (oid) {
    int r = lfn_translate(*out, *shortname, oid);
    if (r < 0)
      return r;
  }
  return 0;
}

string LFNIndex::mangle_attr_name(const string &attr)
{
  return PHASH_ATTR_PREFIX + attr;
}