ceph/src/os/filestore/BtrfsFileStoreBackend.cc

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
   7  *
   8  * This is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License version 2.1, as published by the Free Software
  11  * Foundation.  See file COPYING.
  12  *
  13  */
  14
  15 #include "include/int_types.h"
  16 #include "include/types.h"
  17
  18 #include <unistd.h>
  19 #include <fcntl.h>
  20 #include <errno.h>
  21 #include <stdlib.h>
  22 #include <sys/types.h>
  23 #include <sys/stat.h>
  24 #include <sys/ioctl.h>
  25 #include "include/compat.h"
  26 #include "include/linux_fiemap.h"
  27 #include "include/color.h"
  28 #include "include/buffer.h"
  29 #include "include/assert.h"
  30
  31 #ifndef __CYGWIN__
  32 #include "os/fs/btrfs_ioctl.h"
  33 #endif
  34
  35 #include <iostream>
  36 #include <fstream>
  37 #include <sstream>
  38
  39 #include "BtrfsFileStoreBackend.h"
  40
  41 #include "common/errno.h"
  42 #include "common/config.h"
  43
  44 #if defined(__linux__)
  45
  46 #define dout_context cct()
  47 #define dout_subsys ceph_subsys_filestore
  48 #undef dout_prefix
  49 #define dout_prefix *_dout << "btrfsfilestorebackend(" << get_basedir_path() << ") "
  50
  51 #define ALIGN_DOWN(x, by) ((x) - ((x) % (by)))
  52 #define ALIGNED(x, by) (!((x) % (by)))
  53 #define ALIGN_UP(x, by) (ALIGNED((x), (by)) ? (x) : (ALIGN_DOWN((x), (by)) + (by)))
  54
  55 BtrfsFileStoreBackend::BtrfsFileStoreBackend(FileStore *fs):
  56     GenericFileStoreBackend(fs), has_clone_range(false),
  57     has_snap_create(false), has_snap_destroy(false),
  58     has_snap_create_v2(false), has_wait_sync(false), stable_commits(false),
  59     m_filestore_btrfs_clone_range(cct()->_conf->filestore_btrfs_clone_range),
  60     m_filestore_btrfs_snap (cct()->_conf->filestore_btrfs_snap) { }
  61
  62 int BtrfsFileStoreBackend::detect_features()
  63 {
  64   int r;
  65
  66   r = GenericFileStoreBackend::detect_features();
  67   if (r < 0)
  68     return r;
  69
  70   // clone_range?
  71   if (m_filestore_btrfs_clone_range) {
  72     int fd = ::openat(get_basedir_fd(), "clone_range_test", O_CREAT|O_WRONLY, 0600);
  73     if (fd >= 0) {
  74       if (::unlinkat(get_basedir_fd(), "clone_range_test", 0) < 0) {
  75         r = -errno;
  76         dout(0) << "detect_feature: failed to unlink test file for CLONE_RANGE ioctl: "
  77                 << cpp_strerror(r) << dendl;
  78       }
  79       btrfs_ioctl_clone_range_args clone_args;
  80       memset(&clone_args, 0, sizeof(clone_args));
  81       clone_args.src_fd = -1;
  82       r = ::ioctl(fd, BTRFS_IOC_CLONE_RANGE, &clone_args);
  83       if (r < 0 && errno == EBADF) {
  84         dout(0) << "detect_feature: CLONE_RANGE ioctl is supported" << dendl;
  85         has_clone_range = true;
  86       } else {
  87         r = -errno;
  88         dout(0) << "detect_feature: CLONE_RANGE ioctl is NOT supported: " << cpp_strerror(r) << dendl;
  89       }
  90       TEMP_FAILURE_RETRY(::close(fd));
  91     } else {
  92       r = -errno;
  93       dout(0) << "detect_feature: failed to create test file for CLONE_RANGE ioctl: "
  94               << cpp_strerror(r) << dendl;
  95     }
  96   } else {
  97     dout(0) << "detect_feature: CLONE_RANGE ioctl is DISABLED via 'filestore btrfs clone range' option" << dendl;
  98   }
  99
 100   struct btrfs_ioctl_vol_args vol_args;
 101   memset(&vol_args, 0, sizeof(vol_args));
 102
 103   // create test source volume
 104   vol_args.fd = 0;
 105   strcpy(vol_args.name, "test_subvol");
 106   r = ::ioctl(get_basedir_fd(), BTRFS_IOC_SUBVOL_CREATE, &vol_args);
 107   if (r != 0) {
 108     r = -errno;
 109     dout(0) << "detect_feature: failed to create simple subvolume " << vol_args.name << ": " << cpp_strerror(r) << dendl;
 110   }
 111   int srcfd = ::openat(get_basedir_fd(), vol_args.name, O_RDONLY);
 112   if (srcfd < 0) {
 113     r = -errno;
 114     dout(0) << "detect_feature: failed to open " << vol_args.name << ": " << cpp_strerror(r) << dendl;
 115   }
 116
 117   // snap_create and snap_destroy?
 118   vol_args.fd = srcfd;
 119   strcpy(vol_args.name, "sync_snap_test");
 120   r = ::ioctl(get_basedir_fd(), BTRFS_IOC_SNAP_CREATE, &vol_args);
 121   int err = errno;
 122   if (r == 0 || errno == EEXIST) {
 123     dout(0) << "detect_feature: SNAP_CREATE is supported" << dendl;
 124     has_snap_create = true;
 125
 126     r = ::ioctl(get_basedir_fd(), BTRFS_IOC_SNAP_DESTROY, &vol_args);
 127     if (r == 0) {
 128       dout(0) << "detect_feature: SNAP_DESTROY is supported" << dendl;
 129       has_snap_destroy = true;
 130     } else {
 131       err = -errno;
 132       dout(0) << "detect_feature: SNAP_DESTROY failed: " << cpp_strerror(err) << dendl;
 133
 134       if (err == -EPERM && getuid() != 0) {
 135         dout(0) << "detect_feature: failed with EPERM as non-root; remount with -o user_subvol_rm_allowed" << dendl;
 136         cerr << TEXT_YELLOW
 137              << "btrfs SNAP_DESTROY failed as non-root; remount with -o user_subvol_rm_allowed"
 138              << TEXT_NORMAL << std::endl;
 139       } else if (err == -EOPNOTSUPP) {
 140         derr << "btrfs SNAP_DESTROY ioctl not supported; you need a kernel newer than 2.6.32" << dendl;
 141       }
 142     }
 143   } else {
 144     dout(0) << "detect_feature: SNAP_CREATE failed: " << cpp_strerror(err) << dendl;
 145   }
 146
 147   if (m_filestore_btrfs_snap) {
 148     if (has_snap_destroy)
 149       stable_commits = true;
 150     else
 151       dout(0) << "detect_feature: snaps enabled, but no SNAP_DESTROY ioctl; DISABLING" << dendl;
 152   }
 153
 154   // start_sync?
 155   __u64 transid = 0;
 156   r = ::ioctl(get_basedir_fd(), BTRFS_IOC_START_SYNC, &transid);
 157   if (r < 0) {
 158     int err = errno;
 159     dout(0) << "detect_feature: START_SYNC got " << cpp_strerror(err) << dendl;
 160   }
 161   if (r == 0 && transid > 0) {
 162     dout(0) << "detect_feature: START_SYNC is supported (transid " << transid << ")" << dendl;
 163
 164     // do we have wait_sync too?
 165     r = ::ioctl(get_basedir_fd(), BTRFS_IOC_WAIT_SYNC, &transid);
 166     if (r == 0 || errno == ERANGE) {
 167       dout(0) << "detect_feature: WAIT_SYNC is supported" << dendl;
 168       has_wait_sync = true;
 169     } else {
 170       int err = errno;
 171       dout(0) << "detect_feature: WAIT_SYNC is NOT supported: " << cpp_strerror(err) << dendl;
 172     }
 173   } else {
 174     int err = errno;
 175     dout(0) << "detect_feature: START_SYNC is NOT supported: " << cpp_strerror(err) << dendl;
 176   }
 177
 178   if (has_wait_sync) {
 179     // async snap creation?
 180     struct btrfs_ioctl_vol_args_v2 async_args;
 181     memset(&async_args, 0, sizeof(async_args));
 182     async_args.fd = srcfd;
 183     async_args.flags = BTRFS_SUBVOL_CREATE_ASYNC;
 184     strcpy(async_args.name, "async_snap_test");
 185
 186     // remove old one, first
 187     struct stat st;
 188     strcpy(vol_args.name, async_args.name);
 189     if (::fstatat(get_basedir_fd(), vol_args.name, &st, 0) == 0) {
 190       dout(0) << "detect_feature: removing old async_snap_test" << dendl;
 191       r = ::ioctl(get_basedir_fd(), BTRFS_IOC_SNAP_DESTROY, &vol_args);
 192       if (r != 0) {
 193         int err = errno;
 194         dout(0) << "detect_feature: failed to remove old async_snap_test: " << cpp_strerror(err) << dendl;
 195       }
 196     }
 197
 198     r = ::ioctl(get_basedir_fd(), BTRFS_IOC_SNAP_CREATE_V2, &async_args);
 199     if (r == 0 || errno == EEXIST) {
 200       dout(0) << "detect_feature: SNAP_CREATE_V2 is supported" << dendl;
 201       has_snap_create_v2 = true;
 202
 203       // clean up
 204       strcpy(vol_args.name, "async_snap_test");
 205       r = ::ioctl(get_basedir_fd(), BTRFS_IOC_SNAP_DESTROY, &vol_args);
 206       if (r != 0) {
 207         int err = errno;
 208         dout(0) << "detect_feature: SNAP_DESTROY failed: " << cpp_strerror(err) << dendl;
 209       }
 210     } else {
 211       int err = errno;
 212       dout(0) << "detect_feature: SNAP_CREATE_V2 is NOT supported: " << cpp_strerror(err) << dendl;
 213     }
 214   }
 215
 216   // clean up test subvol
 217   if (srcfd >= 0)
 218     TEMP_FAILURE_RETRY(::close(srcfd));
 219
 220   strcpy(vol_args.name, "test_subvol");
 221   r = ::ioctl(get_basedir_fd(), BTRFS_IOC_SNAP_DESTROY, &vol_args);
 222   if (r < 0) {
 223     r = -errno;
 224     dout(0) << "detect_feature: failed to remove " << vol_args.name << ": " << cpp_strerror(r) << dendl;
 225   }
 226
 227   if (m_filestore_btrfs_snap && !has_snap_create_v2) {
 228     dout(0) << "mount WARNING: btrfs snaps enabled, but no SNAP_CREATE_V2 ioctl (from kernel 2.6.37+)" << dendl;
 229     cerr << TEXT_YELLOW
 230       << " ** WARNING: 'filestore btrfs snap' is enabled (for safe transactions,\n"
 231       << "             rollback), but btrfs does not support the SNAP_CREATE_V2 ioctl\n"
 232       << "             (added in Linux 2.6.37).  Expect slow btrfs sync/commit\n"
 233       << "             performance.\n"
 234       << TEXT_NORMAL;
 235   }
 236
 237   return 0;
 238 }
 239
 240 bool BtrfsFileStoreBackend::can_checkpoint()
 241 {
 242   return stable_commits;
 243 }
 244
 245 int BtrfsFileStoreBackend::create_current()
 246 {
 247   struct stat st;
 248   int ret = ::stat(get_current_path().c_str(), &st);
 249   if (ret == 0) {
 250     // current/ exists
 251     if (!S_ISDIR(st.st_mode)) {
 252       dout(0) << "create_current: current/ exists but is not a directory" << dendl;
 253       return -EINVAL;
 254     }
 255
 256     struct stat basest;
 257     struct statfs currentfs;
 258     ret = ::fstat(get_basedir_fd(), &basest);
 259     if (ret < 0) {
 260       ret = -errno;
 261       dout(0) << "create_current: cannot fstat basedir " << cpp_strerror(ret) << dendl;
 262       return ret;
 263     }
 264     ret = ::statfs(get_current_path().c_str(), &currentfs);
 265     if (ret < 0) {
 266       ret = -errno;
 267       dout(0) << "create_current: cannot statsf basedir " << cpp_strerror(ret) << dendl;
 268       return ret;
 269     }
 270     if (currentfs.f_type == BTRFS_SUPER_MAGIC && basest.st_dev != st.st_dev) {
 271       dout(2) << "create_current: current appears to be a btrfs subvolume" << dendl;
 272       stable_commits = true;
 273     }
 274     return 0;
 275   }
 276
 277   struct btrfs_ioctl_vol_args volargs;
 278   memset(&volargs, 0, sizeof(volargs));
 279
 280   volargs.fd = 0;
 281   strcpy(volargs.name, "current");
 282   if (::ioctl(get_basedir_fd(), BTRFS_IOC_SUBVOL_CREATE, (unsigned long int)&volargs) < 0) {
 283     ret = -errno;
 284     dout(0) << "create_current: BTRFS_IOC_SUBVOL_CREATE failed with error "
 285             << cpp_strerror(ret) << dendl;
 286     return ret;
 287   }
 288
 289   dout(2) << "create_current: created btrfs subvol " << get_current_path() << dendl;
 290   if (::chmod(get_current_path().c_str(), 0755) < 0) {
 291     ret = -errno;
 292     dout(0) << "create_current: failed to chmod " << get_current_path() << " to 0755: "
 293             << cpp_strerror(ret) << dendl;
 294     return ret;
 295   }
 296
 297   stable_commits = true;
 298   return 0;
 299 }
 300
 301 int BtrfsFileStoreBackend::list_checkpoints(list<string>& ls)
 302 {
 303   int ret, err = 0;
 304
 305   struct stat basest;
 306   ret = ::fstat(get_basedir_fd(), &basest);
 307   if (ret < 0) {
 308     ret = -errno;
 309     dout(0) << "list_checkpoints: cannot fstat basedir " << cpp_strerror(ret) << dendl;
 310     return ret;
 311   }
 312
 313   // get snap list
 314   DIR *dir = ::opendir(get_basedir_path().c_str());
 315   if (!dir) {
 316     ret = -errno;
 317     dout(0) << "list_checkpoints: opendir '" << get_basedir_path() << "' failed: "
 318             << cpp_strerror(ret) << dendl;
 319     return ret;
 320   }
 321
 322   list<string> snaps;
 323   char path[PATH_MAX];
 324   struct dirent *de;
 325   while ((de = ::readdir(dir))) {
 326     snprintf(path, sizeof(path), "%s/%s", get_basedir_path().c_str(), de->d_name);
 327
 328     struct stat st;
 329     ret = ::stat(path, &st);
 330     if (ret < 0) {
 331       err = -errno;
 332       dout(0) << "list_checkpoints: stat '" << path << "' failed: "
 333               << cpp_strerror(err) << dendl;
 334       break;
 335     }
 336
 337     if (!S_ISDIR(st.st_mode))
 338       continue;
 339
 340     struct statfs fs;
 341     ret = ::statfs(path, &fs);
 342     if (ret < 0) {
 343       err = -errno;
 344       dout(0) << "list_checkpoints: statfs '" << path << "' failed: "
 345               << cpp_strerror(err) << dendl;
 346       break;
 347     }
 348
 349     if (fs.f_type == BTRFS_SUPER_MAGIC && basest.st_dev != st.st_dev)
 350       snaps.push_back(string(de->d_name));
 351   }
 352
 353   if (::closedir(dir) < 0) {
 354       ret = -errno;
 355       dout(0) << "list_checkpoints: closedir failed: " << cpp_strerror(ret) << dendl;
 356       if (!err)
 357         err = ret;
 358   }
 359
 360   if (err)
 361     return err;
 362
 363   ls.swap(snaps);
 364   return 0;
 365 }
 366
 367 int BtrfsFileStoreBackend::create_checkpoint(const string& name, uint64_t *transid)
 368 {
 369   dout(10) << "create_checkpoint: '" << name << "'" << dendl;
 370   if (has_snap_create_v2 && transid) {
 371     struct btrfs_ioctl_vol_args_v2 async_args;
 372     memset(&async_args, 0, sizeof(async_args));
 373     async_args.fd = get_current_fd();
 374     async_args.flags = BTRFS_SUBVOL_CREATE_ASYNC;
 375
 376     size_t name_size = sizeof(async_args.name);
 377     strncpy(async_args.name, name.c_str(), name_size);
 378     async_args.name[name_size-1] = '\0';
 379
 380     int r = ::ioctl(get_basedir_fd(), BTRFS_IOC_SNAP_CREATE_V2, &async_args);
 381     if (r < 0) {
 382       r = -errno;
 383       dout(0) << "create_checkpoint: async snap create '" << name << "' got " << cpp_strerror(r) << dendl;
 384       return r;
 385     }
 386     dout(20) << "create_checkpoint: async snap create '" << name << "' transid " << async_args.transid << dendl;
 387     *transid = async_args.transid;
 388   } else {
 389     struct btrfs_ioctl_vol_args vol_args;
 390     memset(&vol_args, 0, sizeof(vol_args));
 391     vol_args.fd = get_current_fd();
 392
 393     size_t name_size = sizeof(vol_args.name);
 394     strncpy(vol_args.name, name.c_str(), name_size);
 395     vol_args.name[name_size-1] = '\0';
 396
 397     int r = ::ioctl(get_basedir_fd(), BTRFS_IOC_SNAP_CREATE, &vol_args);
 398     if (r < 0) {
 399       r = -errno;
 400       dout(0) << "create_checkpoint: snap create '" << name << "' got " << cpp_strerror(r) << dendl;
 401       return r;
 402     }
 403     if (transid)
 404       *transid = 0;
 405   }
 406   return 0;
 407 }
 408
 409 int BtrfsFileStoreBackend::sync_checkpoint(uint64_t transid)
 410 {
 411   // wait for commit
 412   dout(10) << "sync_checkpoint: transid " << transid << " to complete" << dendl;
 413   int ret = ::ioctl(get_op_fd(), BTRFS_IOC_WAIT_SYNC, &transid);
 414   if (ret < 0) {
 415     ret = -errno;
 416     dout(0) << "sync_checkpoint: ioctl WAIT_SYNC got " << cpp_strerror(ret) << dendl;
 417     return -errno;
 418   }
 419   dout(20) << "sync_checkpoint: done waiting for transid " << transid << dendl;
 420   return 0;
 421 }
 422
 423 int BtrfsFileStoreBackend::rollback_to(const string& name)
 424 {
 425   dout(10) << "rollback_to: to '" << name << "'" << dendl;
 426   char s[PATH_MAX];
 427   btrfs_ioctl_vol_args vol_args;
 428
 429   memset(&vol_args, 0, sizeof(vol_args));
 430   vol_args.fd = 0;
 431   strcpy(vol_args.name, "current");
 432
 433   int ret = ::ioctl(get_basedir_fd(), BTRFS_IOC_SNAP_DESTROY, &vol_args);
 434   if (ret && errno != ENOENT) {
 435     dout(0) << "rollback_to: error removing old current subvol: " << cpp_strerror(ret) << dendl;
 436     snprintf(s, sizeof(s), "%s/current.remove.me.%d", get_basedir_path().c_str(), rand());
 437     if (::rename(get_current_path().c_str(), s)) {
 438       ret = -errno;
 439       dout(0) << "rollback_to: error renaming old current subvol: "
 440               << cpp_strerror(ret) << dendl;
 441       return ret;
 442     }
 443   }
 444
 445   snprintf(s, sizeof(s), "%s/%s", get_basedir_path().c_str(), name.c_str());
 446
 447   // roll back
 448   vol_args.fd = ::open(s, O_RDONLY);
 449   if (vol_args.fd < 0) {
 450     ret = -errno;
 451     dout(0) << "rollback_to: error opening '" << s << "': " << cpp_strerror(ret) << dendl;
 452     return ret;
 453   }
 454   ret = ::ioctl(get_basedir_fd(), BTRFS_IOC_SNAP_CREATE, &vol_args);
 455   if (ret < 0 ) {
 456     ret = -errno;
 457     dout(0) << "rollback_to: ioctl SNAP_CREATE got " << cpp_strerror(ret) << dendl;
 458   }
 459   TEMP_FAILURE_RETRY(::close(vol_args.fd));
 460   return ret;
 461 }
 462
 463 int BtrfsFileStoreBackend::destroy_checkpoint(const string& name)
 464 {
 465   dout(10) << "destroy_checkpoint: '" << name << "'" << dendl;
 466   btrfs_ioctl_vol_args vol_args;
 467   memset(&vol_args, 0, sizeof(vol_args));
 468   vol_args.fd = 0;
 469   strncpy(vol_args.name, name.c_str(), sizeof(vol_args.name));
 470
 471   int ret = ::ioctl(get_basedir_fd(), BTRFS_IOC_SNAP_DESTROY, &vol_args);
 472   if (ret) {
 473     ret = -errno;
 474     dout(0) << "destroy_checkpoint: ioctl SNAP_DESTROY got " << cpp_strerror(ret) << dendl;
 475     return ret;
 476   }
 477   return 0;
 478 }
 479
 480 int BtrfsFileStoreBackend::syncfs()
 481 {
 482   dout(15) << "syncfs" << dendl;
 483   // do a full btrfs commit
 484   int ret = ::ioctl(get_op_fd(), BTRFS_IOC_SYNC);
 485   if (ret < 0) {
 486     ret = -errno;
 487     dout(0) << "syncfs: btrfs IOC_SYNC got " << cpp_strerror(ret) << dendl;
 488   }
 489   return ret;
 490 }
 491
 492 int BtrfsFileStoreBackend::clone_range(int from, int to, uint64_t srcoff, uint64_t len, uint64_t dstoff)
 493 {
 494   dout(20) << "clone_range: " << srcoff << "~" << len << " to " << dstoff << dendl;
 495   size_t blk_size = get_blksize();
 496   if (!has_clone_range ||
 497       srcoff % blk_size != dstoff % blk_size) {
 498     dout(20) << "clone_range: using copy" << dendl;
 499     return _copy_range(from, to, srcoff, len, dstoff);
 500   }
 501
 502   int err = 0;
 503   int r = 0;
 504
 505   uint64_t srcoffclone = ALIGN_UP(srcoff, blk_size);
 506   uint64_t dstoffclone = ALIGN_UP(dstoff, blk_size);
 507   if (srcoffclone >= srcoff + len) {
 508     dout(20) << "clone_range: using copy, extent too short to align srcoff" << dendl;
 509     return _copy_range(from, to, srcoff, len, dstoff);
 510   }
 511
 512   uint64_t lenclone = len - (srcoffclone - srcoff);
 513   if (!ALIGNED(lenclone, blk_size)) {
 514     struct stat from_stat, to_stat;
 515     err = ::fstat(from, &from_stat);
 516     if (err) return -errno;
 517     err = ::fstat(to , &to_stat);
 518     if (err) return -errno;
 519
 520     if (srcoff + len != (uint64_t)from_stat.st_size ||
 521         dstoff + len < (uint64_t)to_stat.st_size) {
 522       // Not to the end of the file, need to align length as well
 523       lenclone = ALIGN_DOWN(lenclone, blk_size);
 524     }
 525   }
 526   if (lenclone == 0) {
 527     // too short
 528     return _copy_range(from, to, srcoff, len, dstoff);
 529   }
 530
 531   dout(20) << "clone_range: cloning " << srcoffclone << "~" << lenclone
 532            << " to " << dstoffclone << " = " << r << dendl;
 533   btrfs_ioctl_clone_range_args a;
 534   a.src_fd = from;
 535   a.src_offset = srcoffclone;
 536   a.src_length = lenclone;
 537   a.dest_offset = dstoffclone;
 538   err = ::ioctl(to, BTRFS_IOC_CLONE_RANGE, &a);
 539   if (err >= 0) {
 540     r += err;
 541   } else if (errno == EINVAL) {
 542     // Still failed, might be compressed
 543     dout(20) << "clone_range: failed CLONE_RANGE call with -EINVAL, using copy" << dendl;
 544     return _copy_range(from, to, srcoff, len, dstoff);
 545   } else {
 546     return -errno;
 547   }
 548
 549   // Take care any trimmed from front
 550   if (srcoffclone != srcoff) {
 551     err = _copy_range(from, to, srcoff, srcoffclone - srcoff, dstoff);
 552     if (err >= 0) {
 553       r += err;
 554     } else {
 555       return err;
 556     }
 557   }
 558
 559   // Copy end
 560   if (srcoffclone + lenclone != srcoff + len) {
 561     err = _copy_range(from, to,
 562                          srcoffclone + lenclone,
 563                          (srcoff + len) - (srcoffclone + lenclone),
 564                          dstoffclone + lenclone);
 565     if (err >= 0) {
 566       r += err;
 567     } else {
 568       return err;
 569     }
 570   }
 571   dout(20) << "clone_range: finished " << srcoff << "~" << len
 572            << " to " << dstoff << " = " << r << dendl;
 573   return r;
 574 }
 575 #endif