2 * Copyright (C) 2012 Alexander Block. All rights reserved.
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.
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.
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.
20 #include "kerncompat.h"
29 #include <sys/types.h>
30 #include <sys/ioctl.h>
35 #include <uuid/uuid.h>
45 #include "send-utils.h"
47 #define SEND_BUFFER_SIZE (64 * 1024)
50 * Default is 1 for historical reasons, changing may break scripts that expect
51 * the 'At subvol' message.
53 static int g_verbose = 1;
61 u64 clone_sources_count;
64 struct subvol_uuid_search sus;
67 static int get_root_id(struct btrfs_send *sctx, const char *path, u64 *root_id)
69 struct subvol_info *si;
71 si = subvol_uuid_search(&sctx->sus, 0, NULL, 0, path,
72 subvol_search_by_path);
75 *root_id = si->root_id;
81 static struct subvol_info *get_parent(struct btrfs_send *sctx, u64 root_id)
83 struct subvol_info *si_tmp;
84 struct subvol_info *si;
86 si_tmp = subvol_uuid_search(&sctx->sus, root_id, NULL, 0, NULL,
87 subvol_search_by_root_id);
91 si = subvol_uuid_search(&sctx->sus, 0, si_tmp->parent_uuid, 0, NULL,
92 subvol_search_by_uuid);
98 static int find_good_parent(struct btrfs_send *sctx, u64 root_id, u64 *found)
101 struct subvol_info *parent = NULL;
102 struct subvol_info *parent2 = NULL;
103 struct subvol_info *best_parent = NULL;
104 u64 best_diff = (u64)-1;
107 parent = get_parent(sctx, root_id);
113 for (i = 0; i < sctx->clone_sources_count; i++) {
114 if (sctx->clone_sources[i] == parent->root_id) {
115 best_parent = parent;
121 for (i = 0; i < sctx->clone_sources_count; i++) {
124 parent2 = get_parent(sctx, sctx->clone_sources[i]);
127 if (parent2->root_id != parent->root_id) {
136 parent2 = subvol_uuid_search(&sctx->sus,
137 sctx->clone_sources[i], NULL, 0, NULL,
138 subvol_search_by_root_id);
144 tmp = parent2->ctransid - parent->ctransid;
147 if (tmp < best_diff) {
149 free(best_parent->path);
152 best_parent = parent2;
168 *found = best_parent->root_id;
177 free(best_parent->path);
183 static int add_clone_source(struct btrfs_send *sctx, u64 root_id)
187 tmp = sctx->clone_sources;
188 sctx->clone_sources = realloc(sctx->clone_sources,
189 sizeof(*sctx->clone_sources) * (sctx->clone_sources_count + 1));
191 if (!sctx->clone_sources) {
195 sctx->clone_sources[sctx->clone_sources_count++] = root_id;
200 static int write_buf(int fd, const char *buf, size_t size)
208 wbytes = write(fd, buf + pos, size - pos);
211 error("failed to dump stream: %s", strerror(-ret));
216 error("failed to dump stream: %s", strerror(-ret));
227 static void *dump_thread(void *arg)
230 struct btrfs_send *sctx = (struct btrfs_send*)arg;
231 char buf[SEND_BUFFER_SIZE];
236 rbytes = read(sctx->send_fd, buf, sizeof(buf));
239 error("failed to read stream from kernel: %s\n",
247 ret = write_buf(sctx->dump_fd, buf, rbytes);
259 static int do_send(struct btrfs_send *send, u64 parent_root_id,
260 int is_first_subvol, int is_last_subvol, const char *subvol,
265 struct btrfs_ioctl_send_args io_send;
268 int pipefd[2] = {-1, -1};
270 subvol_fd = openat(send->mnt_fd, subvol, O_RDONLY | O_NOATIME);
273 error("cannot open %s: %s", subvol, strerror(-ret));
280 error("pipe failed: %s", strerror(-ret));
284 memset(&io_send, 0, sizeof(io_send));
285 io_send.send_fd = pipefd[1];
286 send->send_fd = pipefd[0];
289 ret = pthread_create(&t_read, NULL, dump_thread,
293 error("thread setup failed: %s", strerror(-ret));
297 io_send.flags = flags;
298 io_send.clone_sources = (__u64*)send->clone_sources;
299 io_send.clone_sources_count = send->clone_sources_count;
300 io_send.parent_root = parent_root_id;
301 if (!is_first_subvol)
302 io_send.flags |= BTRFS_SEND_FLAG_OMIT_STREAM_HEADER;
304 io_send.flags |= BTRFS_SEND_FLAG_OMIT_END_CMD;
305 ret = ioctl(subvol_fd, BTRFS_IOC_SEND, &io_send);
308 error("send ioctl failed with %d: %s", ret, strerror(-ret));
309 if (ret == -EINVAL && (!is_first_subvol || !is_last_subvol))
311 "Try upgrading your kernel or don't use -e.\n");
315 fprintf(stderr, "BTRFS_IOC_SEND returned %d\n", ret);
318 fprintf(stderr, "joining genl thread\n");
323 ret = pthread_join(t_read, &t_err);
326 error("pthread_join failed: %s", strerror(-ret));
330 ret = (long int)t_err;
331 error("failed to process send stream, ret=%ld (%s)",
332 (long int)t_err, strerror(-ret));
348 static int init_root_path(struct btrfs_send *sctx, const char *subvol)
355 ret = find_mount_root(subvol, &sctx->root_path);
357 error("failed to determine mount point for %s: %s",
358 subvol, strerror(-ret));
363 error("%s doesn't belong to btrfs mount point", subvol);
368 sctx->mnt_fd = open(sctx->root_path, O_RDONLY | O_NOATIME);
369 if (sctx->mnt_fd < 0) {
371 error("cannot open '%s': %s", sctx->root_path, strerror(-ret));
375 ret = subvol_uuid_search_init(sctx->mnt_fd, &sctx->sus);
377 error("failed to initialize subvol search: %s",
387 static int is_subvol_ro(struct btrfs_send *sctx, const char *subvol)
393 fd = openat(sctx->mnt_fd, subvol, O_RDONLY | O_NOATIME);
396 error("cannot open %s: %s", subvol, strerror(-ret));
400 ret = ioctl(fd, BTRFS_IOC_SUBVOL_GETFLAGS, &flags);
403 error("failed to get flags for subvolume %s: %s",
404 subvol, strerror(-ret));
408 if (flags & BTRFS_SUBVOL_RDONLY)
420 int cmd_send(int argc, char **argv)
424 char outname[PATH_MAX];
425 struct btrfs_send send;
427 char *mount_root = NULL;
428 char *snapshot_parent = NULL;
430 u64 parent_root_id = 0;
432 int new_end_cmd_semantic = 0;
435 memset(&send, 0, sizeof(send));
436 send.dump_fd = fileno(stdout);
440 enum { GETOPT_VAL_SEND_NO_DATA = 256 };
441 static const struct option long_options[] = {
442 { "verbose", no_argument, NULL, 'v' },
443 { "quiet", no_argument, NULL, 'q' },
444 { "no-data", no_argument, NULL, GETOPT_VAL_SEND_NO_DATA }
446 int c = getopt_long(argc, argv, "vqec:f:i:p:", long_options, NULL);
459 new_end_cmd_semantic = 1;
462 subvol = realpath(optarg, NULL);
465 error("realpath %s failed: %s\n", optarg, strerror(-ret));
469 ret = init_root_path(&send, subvol);
473 ret = get_root_id(&send,
474 subvol_strip_mountpoint(send.root_path, subvol),
477 error("cannot resolve rootid for %s", subvol);
481 ret = is_subvol_ro(&send, subvol);
486 error("cloned subvolume %s is not read-only", subvol);
490 ret = add_clone_source(&send, root_id);
492 error("cannot add clone source: %s", strerror(-ret));
495 subvol_uuid_search_finit(&send.sus);
498 if (send.mnt_fd >= 0) {
502 free(send.root_path);
503 send.root_path = NULL;
507 if (arg_copy_path(outname, optarg, sizeof(outname))) {
508 error("output file path too long (%zu)", strlen(optarg));
514 if (snapshot_parent) {
515 error("you cannot have more than one parent (-p)");
519 snapshot_parent = realpath(optarg, NULL);
520 if (!snapshot_parent) {
522 error("realpath %s failed: %s", optarg, strerror(-ret));
526 ret = is_subvol_ro(&send, snapshot_parent);
531 error("parent subvolume %s is not read-only",
539 error("option -i was removed, use -c instead");
542 case GETOPT_VAL_SEND_NO_DATA:
543 send_flags |= BTRFS_SEND_FLAG_NO_FILE_DATA;
547 error("send arguments invalid");
553 if (check_argc_min(argc - optind, 1))
554 usage(cmd_send_usage);
557 send.dump_fd = creat(outname, 0600);
558 if (send.dump_fd == -1) {
560 error("cannot create '%s': %s", outname, strerror(-ret));
565 if (isatty(send.dump_fd)) {
567 "not dumping send stream into a terminal, redirect it into a file");
572 /* use first send subvol to determine mount_root */
573 subvol = realpath(argv[optind], NULL);
576 error("unable to resolve %s", argv[optind]);
580 ret = init_root_path(&send, subvol);
584 if (snapshot_parent != NULL) {
585 ret = get_root_id(&send,
586 subvol_strip_mountpoint(send.root_path, snapshot_parent),
589 error("could not resolve rootid for %s", snapshot_parent);
593 ret = add_clone_source(&send, parent_root_id);
595 error("cannot add clone source: %s", strerror(-ret));
600 for (i = optind; i < argc; i++) {
602 subvol = realpath(argv[i], NULL);
605 error("unable to resolve %s", argv[i]);
609 ret = find_mount_root(subvol, &mount_root);
611 error("find_mount_root failed on %s: %s", subvol,
616 error("%s does not belong to btrfs mount point",
621 if (strcmp(send.root_path, mount_root) != 0) {
623 error("all subvolumes must be from the same filesystem");
628 ret = is_subvol_ro(&send, subvol);
633 error("subvolume %s is not read-only", subvol);
638 if ((send_flags & BTRFS_SEND_FLAG_NO_FILE_DATA) && g_verbose > 1)
640 fprintf(stderr, "Mode NO_FILE_DATA enabled\n");
642 for (i = optind; i < argc; i++) {
650 fprintf(stderr, "At subvol %s\n", subvol);
652 subvol = realpath(subvol, NULL);
655 error("realpath %s failed: %s", argv[i], strerror(-ret));
659 if (!full_send && root_id) {
660 ret = find_good_parent(&send, root_id, &parent_root_id);
662 error("parent determination failed for %lld",
668 if (new_end_cmd_semantic) {
669 /* require new kernel */
670 is_first_subvol = (i == optind);
671 is_last_subvol = (i == argc - 1);
673 /* be compatible to old and new kernel */
677 ret = do_send(&send, parent_root_id, is_first_subvol,
678 is_last_subvol, subvol, send_flags);
682 if (!full_send && root_id) {
683 /* done with this subvol, so add it to the clone sources */
684 ret = add_clone_source(&send, root_id);
686 error("cannot add clone source: %s", strerror(-ret));
696 free(snapshot_parent);
697 free(send.clone_sources);
698 if (send.mnt_fd >= 0)
700 free(send.root_path);
701 subvol_uuid_search_finit(&send.sus);
705 const char * const cmd_send_usage[] = {
706 "btrfs send [-ve] [-p <parent>] [-c <clone-src>] [-f <outfile>] <subvol> [<subvol>...]",
707 "Send the subvolume(s) to stdout.",
708 "Sends the subvolume(s) specified by <subvol> to stdout.",
709 "<subvol> should be read-only here.",
710 "By default, this will send the whole subvolume. To do an incremental",
711 "send, use '-p <parent>'. If you want to allow btrfs to clone from",
712 "any additional local snapshots, use '-c <clone-src>' (multiple times",
713 "where applicable). You must not specify clone sources unless you",
714 "guarantee that these snapshots are exactly in the same state on both",
715 "sides, the sender and the receiver. It is allowed to omit the",
716 "'-p <parent>' option when '-c <clone-src>' options are given, in",
717 "which case 'btrfs send' will determine a suitable parent among the",
718 "clone sources itself.",
720 "-e If sending multiple subvols at once, use the new",
721 " format and omit the end-cmd between the subvols.",
722 "-p <parent> Send an incremental stream from <parent> to",
724 "-c <clone-src> Use this snapshot as a clone source for an ",
725 " incremental send (multiple allowed)",
726 "-f <outfile> Output is normally written to stdout. To write to",
727 " a file, use this option. An alternative would be to",
729 "--no-data send in NO_FILE_DATA mode, Note: the output stream",
730 " does not contain any file data and thus cannot be used",
731 " to transfer changes. This mode is faster and useful to",
732 " show the differences in metadata.",
733 "-v|--verbose enable verbose output to stderr, each occurrence of",
734 " this option increases verbosity",
735 "-q|--quiet suppress all messages, except errors",