cmds-send.c

   1 /*
   2  * Copyright (C) 2012 Alexander Block.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #define _GNU_SOURCE
  20
  21 #include "kerncompat.h"
  22
  23 #include <unistd.h>
  24 #include <stdint.h>
  25 #include <dirent.h>
  26 #include <fcntl.h>
  27 #include <pthread.h>
  28 #include <math.h>
  29 #include <sys/stat.h>
  30 #include <sys/types.h>
  31 #include <sys/ioctl.h>
  32 #include <libgen.h>
  33 #include <mntent.h>
  34 #include <assert.h>
  35
  36 #include <uuid/uuid.h>
  37
  38 #include "ctree.h"
  39 #include "ioctl.h"
  40 #include "commands.h"
  41 #include "list.h"
  42 #include "utils.h"
  43
  44 #include "send.h"
  45 #include "send-utils.h"
  46
  47 static int g_verbose = 0;
  48
  49 struct btrfs_send {
  50         int send_fd;
  51         int dump_fd;
  52         int mnt_fd;
  53
  54         u64 *clone_sources;
  55         u64 clone_sources_count;
  56
  57         char *root_path;
  58         struct subvol_uuid_search sus;
  59 };
  60
  61 static int get_root_id(struct btrfs_send *s, const char *path, u64 *root_id)
  62 {
  63         struct subvol_info *si;
  64
  65         si = subvol_uuid_search(&s->sus, 0, NULL, 0, path,
  66                         subvol_search_by_path);
  67         if (!si)
  68                 return -ENOENT;
  69         *root_id = si->root_id;
  70         free(si->path);
  71         free(si);
  72         return 0;
  73 }
  74
  75 static struct subvol_info *get_parent(struct btrfs_send *s, u64 root_id)
  76 {
  77         struct subvol_info *si_tmp;
  78         struct subvol_info *si;
  79
  80         si_tmp = subvol_uuid_search(&s->sus, root_id, NULL, 0, NULL,
  81                         subvol_search_by_root_id);
  82         if (!si_tmp)
  83                 return NULL;
  84
  85         si = subvol_uuid_search(&s->sus, 0, si_tmp->parent_uuid, 0, NULL,
  86                         subvol_search_by_uuid);
  87         free(si_tmp->path);
  88         free(si_tmp);
  89         return si;
  90 }
  91
  92 static int find_good_parent(struct btrfs_send *s, u64 root_id, u64 *found)
  93 {
  94         int ret;
  95         struct subvol_info *parent = NULL;
  96         struct subvol_info *parent2 = NULL;
  97         struct subvol_info *best_parent = NULL;
  98         __s64 tmp;
  99         u64 best_diff = (u64)-1;
 100         int i;
 101
 102         parent = get_parent(s, root_id);
 103         if (!parent) {
 104                 ret = -ENOENT;
 105                 goto out;
 106         }
 107
 108         for (i = 0; i < s->clone_sources_count; i++) {
 109                 if (s->clone_sources[i] == parent->root_id) {
 110                         best_parent = parent;
 111                         parent = NULL;
 112                         goto out_found;
 113                 }
 114         }
 115
 116         for (i = 0; i < s->clone_sources_count; i++) {
 117                 parent2 = get_parent(s, s->clone_sources[i]);
 118                 if (!parent2)
 119                         continue;
 120                 if (parent2->root_id != parent->root_id) {
 121                         free(parent2->path);
 122                         free(parent2);
 123                         parent2 = NULL;
 124                         continue;
 125                 }
 126
 127                 free(parent2->path);
 128                 free(parent2);
 129                 parent2 = subvol_uuid_search(&s->sus, s->clone_sources[i], NULL,
 130                                 0, NULL, subvol_search_by_root_id);
 131
 132                 if (!parent2) {
 133                         ret = -ENOENT;
 134                         goto out;
 135                 }
 136                 tmp = parent2->ctransid - parent->ctransid;
 137                 if (tmp < 0)
 138                         tmp *= -1;
 139                 if (tmp < best_diff) {
 140                         if (best_parent) {
 141                                 free(best_parent->path);
 142                                 free(best_parent);
 143                         }
 144                         best_parent = parent2;
 145                         parent2 = NULL;
 146                         best_diff = tmp;
 147                 } else {
 148                         free(parent2->path);
 149                         free(parent2);
 150                         parent2 = NULL;
 151                 }
 152         }
 153
 154         if (!best_parent) {
 155                 ret = -ENOENT;
 156                 goto out;
 157         }
 158
 159 out_found:
 160         *found = best_parent->root_id;
 161         ret = 0;
 162
 163 out:
 164         if (parent) {
 165                 free(parent->path);
 166                 free(parent);
 167         }
 168         if (best_parent) {
 169                 free(best_parent->path);
 170                 free(best_parent);
 171         }
 172         return ret;
 173 }
 174
 175 static void add_clone_source(struct btrfs_send *s, u64 root_id)
 176 {
 177         s->clone_sources = realloc(s->clone_sources,
 178                 sizeof(*s->clone_sources) * (s->clone_sources_count + 1));
 179         s->clone_sources[s->clone_sources_count++] = root_id;
 180 }
 181
 182 static int write_buf(int fd, const void *buf, int size)
 183 {
 184         int ret;
 185         int pos = 0;
 186
 187         while (pos < size) {
 188                 ret = write(fd, (char*)buf + pos, size - pos);
 189                 if (ret < 0) {
 190                         ret = -errno;
 191                         fprintf(stderr, "ERROR: failed to dump stream. %s",
 192                                         strerror(-ret));
 193                         goto out;
 194                 }
 195                 if (!ret) {
 196                         ret = -EIO;
 197                         fprintf(stderr, "ERROR: failed to dump stream. %s",
 198                                         strerror(-ret));
 199                         goto out;
 200                 }
 201                 pos += ret;
 202         }
 203         ret = 0;
 204
 205 out:
 206         return ret;
 207 }
 208
 209 static void *dump_thread(void *arg_)
 210 {
 211         int ret;
 212         struct btrfs_send *s = (struct btrfs_send*)arg_;
 213         char buf[4096];
 214         int readed;
 215
 216         while (1) {
 217                 readed = read(s->send_fd, buf, sizeof(buf));
 218                 if (readed < 0) {
 219                         ret = -errno;
 220                         fprintf(stderr, "ERROR: failed to read stream from "
 221                                         "kernel. %s\n", strerror(-ret));
 222                         goto out;
 223                 }
 224                 if (!readed) {
 225                         ret = 0;
 226                         goto out;
 227                 }
 228                 ret = write_buf(s->dump_fd, buf, readed);
 229                 if (ret < 0)
 230                         goto out;
 231         }
 232
 233 out:
 234         if (ret < 0) {
 235                 exit(-ret);
 236         }
 237
 238         return ERR_PTR(ret);
 239 }
 240
 241 static int do_send(struct btrfs_send *send, u64 parent_root_id,
 242                    int is_first_subvol, int is_last_subvol, char *subvol)
 243 {
 244         int ret;
 245         pthread_t t_read;
 246         struct btrfs_ioctl_send_args io_send;
 247         void *t_err = NULL;
 248         int subvol_fd = -1;
 249         int pipefd[2] = {-1, -1};
 250
 251         subvol_fd = openat(send->mnt_fd, subvol, O_RDONLY | O_NOATIME);
 252         if (subvol_fd < 0) {
 253                 ret = -errno;
 254                 fprintf(stderr, "ERROR: open %s failed. %s\n", subvol,
 255                                 strerror(-ret));
 256                 goto out;
 257         }
 258
 259         ret = pipe(pipefd);
 260         if (ret < 0) {
 261                 ret = -errno;
 262                 fprintf(stderr, "ERROR: pipe failed. %s\n", strerror(-ret));
 263                 goto out;
 264         }
 265
 266         memset(&io_send, 0, sizeof(io_send));
 267         io_send.send_fd = pipefd[1];
 268         send->send_fd = pipefd[0];
 269
 270         if (!ret)
 271                 ret = pthread_create(&t_read, NULL, dump_thread,
 272                                         send);
 273         if (ret) {
 274                 ret = -ret;
 275                 fprintf(stderr, "ERROR: thread setup failed: %s\n",
 276                         strerror(-ret));
 277                 goto out;
 278         }
 279
 280         io_send.clone_sources = (__u64*)send->clone_sources;
 281         io_send.clone_sources_count = send->clone_sources_count;
 282         io_send.parent_root = parent_root_id;
 283         if (!is_first_subvol)
 284                 io_send.flags |= BTRFS_SEND_FLAG_OMIT_STREAM_HEADER;
 285         if (!is_last_subvol)
 286                 io_send.flags |= BTRFS_SEND_FLAG_OMIT_END_CMD;
 287         ret = ioctl(subvol_fd, BTRFS_IOC_SEND, &io_send);
 288         if (ret) {
 289                 ret = -errno;
 290                 fprintf(stderr, "ERROR: send ioctl failed with %d: %s\n", ret,
 291                         strerror(-ret));
 292                 if (ret == -EINVAL && (!is_first_subvol || !is_last_subvol))
 293                         fprintf(stderr,
 294                                 "Try upgrading your kernel or don't use -e.\n");
 295                 goto out;
 296         }
 297         if (g_verbose > 0)
 298                 fprintf(stderr, "BTRFS_IOC_SEND returned %d\n", ret);
 299
 300         if (g_verbose > 0)
 301                 fprintf(stderr, "joining genl thread\n");
 302
 303         close(pipefd[1]);
 304         pipefd[1] = -1;
 305
 306         ret = pthread_join(t_read, &t_err);
 307         if (ret) {
 308                 ret = -ret;
 309                 fprintf(stderr, "ERROR: pthread_join failed: %s\n",
 310                         strerror(-ret));
 311                 goto out;
 312         }
 313         if (t_err) {
 314                 ret = (long int)t_err;
 315                 fprintf(stderr, "ERROR: failed to process send stream, ret=%ld "
 316                         "(%s)\n", (long int)t_err, strerror(-ret));
 317                 goto out;
 318         }
 319
 320         ret = 0;
 321
 322 out:
 323         if (subvol_fd != -1)
 324                 close(subvol_fd);
 325         if (pipefd[0] != -1)
 326                 close(pipefd[0]);
 327         if (pipefd[1] != -1)
 328                 close(pipefd[1]);
 329         return ret;
 330 }
 331
 332 char *get_subvol_name(char *mnt, char *full_path)
 333 {
 334         int len = strlen(mnt);
 335         if (!len)
 336                 return full_path;
 337         if (mnt[len - 1] != '/')
 338                 len += 1;
 339
 340         return full_path + len;
 341 }
 342
 343 static int init_root_path(struct btrfs_send *s, const char *subvol)
 344 {
 345         int ret = 0;
 346
 347         if (s->root_path)
 348                 goto out;
 349
 350         ret = find_mount_root(subvol, &s->root_path);
 351         if (ret < 0) {
 352                 ret = -EINVAL;
 353                 fprintf(stderr, "ERROR: failed to determine mount point "
 354                                 "for %s\n", subvol);
 355                 goto out;
 356         }
 357
 358         s->mnt_fd = open(s->root_path, O_RDONLY | O_NOATIME);
 359         if (s->mnt_fd < 0) {
 360                 ret = -errno;
 361                 fprintf(stderr, "ERROR: can't open '%s': %s\n", s->root_path,
 362                         strerror(-ret));
 363                 goto out;
 364         }
 365
 366         ret = subvol_uuid_search_init(s->mnt_fd, &s->sus);
 367         if (ret < 0) {
 368                 fprintf(stderr, "ERROR: failed to initialize subvol search. "
 369                                 "%s\n", strerror(-ret));
 370                 goto out;
 371         }
 372
 373 out:
 374         return ret;
 375
 376 }
 377
 378 static int is_subvol_ro(struct btrfs_send *s, char *subvol)
 379 {
 380         int ret;
 381         u64 flags;
 382         int fd = -1;
 383
 384         fd = openat(s->mnt_fd, subvol, O_RDONLY | O_NOATIME);
 385         if (fd < 0) {
 386                 ret = -errno;
 387                 fprintf(stderr, "ERROR: failed to open %s. %s\n",
 388                                 subvol, strerror(-ret));
 389                 goto out;
 390         }
 391
 392         ret = ioctl(fd, BTRFS_IOC_SUBVOL_GETFLAGS, &flags);
 393         if (ret < 0) {
 394                 ret = -errno;
 395                 fprintf(stderr, "ERROR: failed to get flags for subvolume. "
 396                                 "%s\n", strerror(-ret));
 397                 goto out;
 398         }
 399
 400         if (flags & BTRFS_SUBVOL_RDONLY)
 401                 ret = 1;
 402         else
 403                 ret = 0;
 404
 405 out:
 406         if (fd != -1)
 407                 close(fd);
 408
 409         return ret;
 410 }
 411
 412 int cmd_send(int argc, char **argv)
 413 {
 414         char *subvol = NULL;
 415         int c;
 416         int ret;
 417         char *outname = NULL;
 418         struct btrfs_send send;
 419         u32 i;
 420         char *mount_root = NULL;
 421         char *snapshot_parent = NULL;
 422         u64 root_id;
 423         u64 parent_root_id = 0;
 424         int full_send = 1;
 425         int new_end_cmd_semantic = 0;
 426
 427         memset(&send, 0, sizeof(send));
 428         send.dump_fd = fileno(stdout);
 429
 430         while ((c = getopt(argc, argv, "vec:f:i:p:")) != -1) {
 431                 switch (c) {
 432                 case 'v':
 433                         g_verbose++;
 434                         break;
 435                 case 'e':
 436                         new_end_cmd_semantic = 1;
 437                         break;
 438                 case 'c':
 439                         subvol = realpath(optarg, NULL);
 440                         if (!subvol) {
 441                                 ret = -errno;
 442                                 fprintf(stderr, "ERROR: realpath %s failed. "
 443                                                 "%s\n", optarg, strerror(-ret));
 444                                 goto out;
 445                         }
 446
 447                         ret = init_root_path(&send, subvol);
 448                         if (ret < 0)
 449                                 goto out;
 450
 451                         ret = get_root_id(&send, get_subvol_name(send.root_path, subvol),
 452                                         &root_id);
 453                         if (ret < 0) {
 454                                 fprintf(stderr, "ERROR: could not resolve "
 455                                                 "root_id for %s\n", subvol);
 456                                 goto out;
 457                         }
 458
 459                         ret = is_subvol_ro(&send, subvol);
 460                         if (ret < 0)
 461                                 goto out;
 462                         if (!ret) {
 463                                 ret = -EINVAL;
 464                                 fprintf(stderr,
 465                                 "ERROR: cloned subvol %s is not read-only.\n",
 466                                         subvol);
 467                                 goto out;
 468                         }
 469
 470                         add_clone_source(&send, root_id);
 471                         subvol_uuid_search_finit(&send.sus);
 472                         free(subvol);
 473                         subvol = NULL;
 474                         if (send.mnt_fd >= 0) {
 475                                 close(send.mnt_fd);
 476                                 send.mnt_fd = -1;
 477                         }
 478                         free(send.root_path);
 479                         send.root_path = NULL;
 480                         full_send = 0;
 481                         break;
 482                 case 'f':
 483                         outname = optarg;
 484                         break;
 485                 case 'p':
 486                         if (snapshot_parent) {
 487                                 fprintf(stderr, "ERROR: you cannot have more than one parent (-p)\n");
 488                                 ret = 1;
 489                                 goto out;
 490                         }
 491                         snapshot_parent = realpath(optarg, NULL);
 492                         if (!snapshot_parent) {
 493                                 ret = -errno;
 494                                 fprintf(stderr, "ERROR: realpath %s failed. "
 495                                                 "%s\n", optarg, strerror(-ret));
 496                                 goto out;
 497                         }
 498
 499                         ret = is_subvol_ro(&send, snapshot_parent);
 500                         if (ret < 0)
 501                                 goto out;
 502                         if (!ret) {
 503                                 ret = -EINVAL;
 504                                 fprintf(stderr,
 505                                         "ERROR: parent %s is not read-only.\n",
 506                                         snapshot_parent);
 507                                 goto out;
 508                         }
 509
 510                         full_send = 0;
 511                         break;
 512                 case 'i':
 513                         fprintf(stderr,
 514                                 "ERROR: -i was removed, use -c instead\n");
 515                         ret = 1;
 516                         goto out;
 517                 case '?':
 518                 default:
 519                         fprintf(stderr, "ERROR: send args invalid.\n");
 520                         ret = 1;
 521                         goto out;
 522                 }
 523         }
 524
 525         if (optind == argc)
 526                 usage(cmd_send_usage);
 527
 528         if (outname != NULL) {
 529                 send.dump_fd = creat(outname, 0600);
 530                 if (send.dump_fd == -1) {
 531                         ret = -errno;
 532                         fprintf(stderr, "ERROR: can't create '%s': %s\n",
 533                                         outname, strerror(-ret));
 534                         goto out;
 535                 }
 536         }
 537
 538         if (isatty(send.dump_fd)) {
 539                 fprintf(stderr,
 540                         "ERROR: not dumping send stream into a terminal, "
 541                         "redirect it into a file\n");
 542                 ret = 1;
 543                 goto out;
 544         }
 545
 546         /* use first send subvol to determine mount_root */
 547         subvol = argv[optind];
 548
 549         subvol = realpath(argv[optind], NULL);
 550         if (!subvol) {
 551                 ret = -errno;
 552                 fprintf(stderr, "ERROR: unable to resolve %s\n", argv[optind]);
 553                 goto out;
 554         }
 555
 556         ret = init_root_path(&send, subvol);
 557         if (ret < 0)
 558                 goto out;
 559
 560         if (snapshot_parent != NULL) {
 561                 ret = get_root_id(&send,
 562                                 get_subvol_name(send.root_path, snapshot_parent),
 563                                 &parent_root_id);
 564                 if (ret < 0) {
 565                         fprintf(stderr, "ERROR: could not resolve root_id "
 566                                         "for %s\n", snapshot_parent);
 567                         goto out;
 568                 }
 569
 570                 add_clone_source(&send, parent_root_id);
 571         }
 572
 573         for (i = optind; i < argc; i++) {
 574                 free(subvol);
 575                 subvol = realpath(argv[i], NULL);
 576                 if (!subvol) {
 577                         ret = -errno;
 578                         fprintf(stderr, "ERROR: unable to resolve %s\n", argv[i]);
 579                         goto out;
 580                 }
 581
 582                 ret = find_mount_root(subvol, &mount_root);
 583                 if (ret < 0) {
 584                         fprintf(stderr, "ERROR: find_mount_root failed on %s: "
 585                                         "%s\n", subvol,
 586                                 strerror(-ret));
 587                         goto out;
 588                 }
 589                 if (strcmp(send.root_path, mount_root) != 0) {
 590                         ret = -EINVAL;
 591                         fprintf(stderr, "ERROR: all subvols must be from the "
 592                                         "same fs.\n");
 593                         goto out;
 594                 }
 595                 free(mount_root);
 596
 597                 ret = is_subvol_ro(&send, subvol);
 598                 if (ret < 0)
 599                         goto out;
 600                 if (!ret) {
 601                         ret = -EINVAL;
 602                         fprintf(stderr, "ERROR: %s is not read-only.\n",
 603                                         subvol);
 604                         goto out;
 605                 }
 606         }
 607
 608         for (i = optind; i < argc; i++) {
 609                 int is_first_subvol;
 610                 int is_last_subvol;
 611
 612                 free(subvol);
 613                 subvol = argv[i];
 614
 615                 fprintf(stderr, "At subvol %s\n", subvol);
 616
 617                 subvol = realpath(subvol, NULL);
 618                 if (!subvol) {
 619                         ret = -errno;
 620                         fprintf(stderr, "ERROR: realpath %s failed. "
 621                                         "%s\n", argv[i], strerror(-ret));
 622                         goto out;
 623                 }
 624
 625                 if (!full_send && !parent_root_id) {
 626                         ret = find_good_parent(&send, root_id, &parent_root_id);
 627                         if (ret < 0) {
 628                                 fprintf(stderr, "ERROR: parent determination failed for %lld\n",
 629                                         root_id);
 630                                 goto out;
 631                         }
 632                 }
 633
 634                 ret = is_subvol_ro(&send, subvol);
 635                 if (ret < 0)
 636                         goto out;
 637                 if (!ret) {
 638                         ret = -EINVAL;
 639                         fprintf(stderr, "ERROR: %s is not read-only.\n",
 640                                         subvol);
 641                         goto out;
 642                 }
 643
 644                 if (new_end_cmd_semantic) {
 645                         /* require new kernel */
 646                         is_first_subvol = (i == optind);
 647                         is_last_subvol = (i == argc - 1);
 648                 } else {
 649                         /* be compatible to old and new kernel */
 650                         is_first_subvol = 1;
 651                         is_last_subvol = 1;
 652                 }
 653                 ret = do_send(&send, parent_root_id, is_first_subvol,
 654                               is_last_subvol, subvol);
 655                 if (ret < 0)
 656                         goto out;
 657
 658                 /* done with this subvol, so add it to the clone sources */
 659                 add_clone_source(&send, root_id);
 660
 661                 parent_root_id = 0;
 662                 full_send = 0;
 663         }
 664
 665         ret = 0;
 666
 667 out:
 668         free(subvol);
 669         free(snapshot_parent);
 670         free(send.clone_sources);
 671         if (send.mnt_fd >= 0)
 672                 close(send.mnt_fd);
 673         free(send.root_path);
 674         subvol_uuid_search_finit(&send.sus);
 675         return !!ret;
 676 }
 677
 678 const char * const cmd_send_usage[] = {
 679         "btrfs send [-ve] [-p <parent>] [-c <clone-src>] [-f <outfile>] <subvol> [<subvol>...]",
 680         "Send the subvolume(s) to stdout.",
 681         "Sends the subvolume(s) specified by <subvol> to stdout.",
 682         "By default, this will send the whole subvolume. To do an incremental",
 683         "send, use '-p <parent>'. If you want to allow btrfs to clone from",
 684         "any additional local snapshots, use '-c <clone-src>' (multiple times",
 685         "where applicable). You must not specify clone sources unless you",
 686         "guarantee that these snapshots are exactly in the same state on both",
 687         "sides, the sender and the receiver. It is allowed to omit the",
 688         "'-p <parent>' option when '-c <clone-src>' options are given, in",
 689         "which case 'btrfs send' will determine a suitable parent among the",
 690         "clone sources itself.",
 691         "\n",
 692         "-v               Enable verbose debug output. Each occurrence of",
 693         "                 this option increases the verbose level more.",
 694         "-e               If sending multiple subvols at once, use the new",
 695         "                 format and omit the end-cmd between the subvols.",
 696         "-p <parent>      Send an incremental stream from <parent> to",
 697         "                 <subvol>.",
 698         "-c <clone-src>   Use this snapshot as a clone source for an ",
 699         "                 incremental send (multiple allowed)",
 700         "-f <outfile>     Output is normally written to stdout. To write to",
 701         "                 a file, use this option. An alternative would be to",
 702         "                 use pipes.",
 703         NULL
 704 };