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;
201 static int write_buf(int fd, const char *buf, size_t size)
209 wbytes = write(fd, buf + pos, size - pos);
212 error("failed to dump stream: %s", strerror(-ret));
217 error("failed to dump stream: %s", strerror(-ret));
228 static void *dump_thread_copy(void *arg)
231 struct btrfs_send *sctx = (struct btrfs_send*)arg;
232 char buf[SEND_BUFFER_SIZE];
237 rbytes = read(sctx->send_fd, buf, sizeof(buf));
240 error("failed to read stream from kernel: %s",
248 ret = write_buf(sctx->dump_fd, buf, rbytes);
261 static void* dump_thread(void *arg)
264 struct btrfs_send *sctx = (struct btrfs_send*)arg;
269 /* Source is a pipe, output is either file or stdout */
270 sbytes = splice(sctx->send_fd, NULL, sctx->dump_fd,
271 NULL, SEND_BUFFER_SIZE, SPLICE_F_MORE);
274 error("failed to read stream from kernel: %s",
291 static int do_send(struct btrfs_send *send, u64 parent_root_id,
292 int is_first_subvol, int is_last_subvol, const char *subvol,
297 struct btrfs_ioctl_send_args io_send;
300 int pipefd[2] = {-1, -1};
302 subvol_fd = openat(send->mnt_fd, subvol, O_RDONLY | O_NOATIME);
305 error("cannot open %s: %s", subvol, strerror(-ret));
312 error("pipe failed: %s", strerror(-ret));
316 memset(&io_send, 0, sizeof(io_send));
317 io_send.send_fd = pipefd[1];
318 send->send_fd = pipefd[0];
321 ret = pthread_create(&t_read, NULL, dump_thread,
325 error("thread setup failed: %s", strerror(-ret));
329 io_send.flags = flags;
330 io_send.clone_sources = (__u64*)send->clone_sources;
331 io_send.clone_sources_count = send->clone_sources_count;
332 io_send.parent_root = parent_root_id;
333 if (!is_first_subvol)
334 io_send.flags |= BTRFS_SEND_FLAG_OMIT_STREAM_HEADER;
336 io_send.flags |= BTRFS_SEND_FLAG_OMIT_END_CMD;
337 ret = ioctl(subvol_fd, BTRFS_IOC_SEND, &io_send);
340 error("send ioctl failed with %d: %s", ret, strerror(-ret));
341 if (ret == -EINVAL && (!is_first_subvol || !is_last_subvol))
343 "Try upgrading your kernel or don't use -e.\n");
347 fprintf(stderr, "BTRFS_IOC_SEND returned %d\n", ret);
350 fprintf(stderr, "joining genl thread\n");
355 ret = pthread_join(t_read, &t_err);
358 error("pthread_join failed: %s", strerror(-ret));
362 ret = (long int)t_err;
363 error("failed to process send stream, ret=%ld (%s)",
364 (long int)t_err, strerror(-ret));
380 static int init_root_path(struct btrfs_send *sctx, const char *subvol)
387 ret = find_mount_root(subvol, &sctx->root_path);
389 error("failed to determine mount point for %s: %s",
390 subvol, strerror(-ret));
395 error("%s doesn't belong to btrfs mount point", subvol);
400 sctx->mnt_fd = open(sctx->root_path, O_RDONLY | O_NOATIME);
401 if (sctx->mnt_fd < 0) {
403 error("cannot open '%s': %s", sctx->root_path, strerror(-ret));
407 ret = subvol_uuid_search_init(sctx->mnt_fd, &sctx->sus);
409 error("failed to initialize subvol search: %s",
419 static int is_subvol_ro(struct btrfs_send *sctx, const char *subvol)
425 fd = openat(sctx->mnt_fd, subvol, O_RDONLY | O_NOATIME);
428 error("cannot open %s: %s", subvol, strerror(-ret));
432 ret = ioctl(fd, BTRFS_IOC_SUBVOL_GETFLAGS, &flags);
435 error("failed to get flags for subvolume %s: %s",
436 subvol, strerror(-ret));
440 if (flags & BTRFS_SUBVOL_RDONLY)
452 static int set_root_info(struct btrfs_send *sctx, const char *subvol,
457 ret = init_root_path(sctx, subvol);
461 ret = get_root_id(sctx, subvol_strip_mountpoint(sctx->root_path, subvol),
464 error("cannot resolve rootid for %s", subvol);
472 static void free_send_info(struct btrfs_send *sctx)
474 if (sctx->mnt_fd >= 0) {
478 free(sctx->root_path);
479 sctx->root_path = NULL;
480 subvol_uuid_search_finit(&sctx->sus);
483 int cmd_send(int argc, char **argv)
487 char outname[PATH_MAX];
488 struct btrfs_send send;
490 char *mount_root = NULL;
491 char *snapshot_parent = NULL;
493 u64 parent_root_id = 0;
495 int new_end_cmd_semantic = 0;
498 memset(&send, 0, sizeof(send));
499 send.dump_fd = fileno(stdout);
503 enum { GETOPT_VAL_SEND_NO_DATA = 256 };
504 static const struct option long_options[] = {
505 { "verbose", no_argument, NULL, 'v' },
506 { "quiet", no_argument, NULL, 'q' },
507 { "no-data", no_argument, NULL, GETOPT_VAL_SEND_NO_DATA }
509 int c = getopt_long(argc, argv, "vqec:f:i:p:", long_options, NULL);
522 new_end_cmd_semantic = 1;
525 subvol = realpath(optarg, NULL);
528 error("realpath %s failed: %s\n", optarg, strerror(-ret));
532 ret = set_root_info(&send, subvol, &root_id);
536 ret = is_subvol_ro(&send, subvol);
541 error("cloned subvolume %s is not read-only", subvol);
545 ret = add_clone_source(&send, root_id);
547 error("cannot add clone source: %s", strerror(-ret));
552 free_send_info(&send);
556 if (arg_copy_path(outname, optarg, sizeof(outname))) {
557 error("output file path too long (%zu)", strlen(optarg));
563 if (snapshot_parent) {
564 error("you cannot have more than one parent (-p)");
568 snapshot_parent = realpath(optarg, NULL);
569 if (!snapshot_parent) {
571 error("realpath %s failed: %s", optarg, strerror(-ret));
575 ret = is_subvol_ro(&send, snapshot_parent);
580 error("parent subvolume %s is not read-only",
588 error("option -i was removed, use -c instead");
591 case GETOPT_VAL_SEND_NO_DATA:
592 send_flags |= BTRFS_SEND_FLAG_NO_FILE_DATA;
596 error("send arguments invalid");
602 if (check_argc_min(argc - optind, 1))
603 usage(cmd_send_usage);
609 * Try to use an existing file first. Even if send runs as
610 * root, it might not have permissions to create file (eg. on a
611 * NFS) but it should still be able to use a pre-created file.
613 tmpfd = open(outname, O_WRONLY | O_TRUNC);
616 tmpfd = open(outname,
617 O_CREAT | O_WRONLY | O_TRUNC, 0600);
619 send.dump_fd = tmpfd;
620 if (send.dump_fd == -1) {
622 error("cannot create '%s': %s", outname, strerror(-ret));
627 if (isatty(send.dump_fd)) {
629 "not dumping send stream into a terminal, redirect it into a file");
634 /* use first send subvol to determine mount_root */
635 subvol = realpath(argv[optind], NULL);
638 error("unable to resolve %s", argv[optind]);
642 ret = init_root_path(&send, subvol);
646 if (snapshot_parent != NULL) {
647 ret = get_root_id(&send,
648 subvol_strip_mountpoint(send.root_path, snapshot_parent),
651 error("could not resolve rootid for %s", snapshot_parent);
655 ret = add_clone_source(&send, parent_root_id);
657 error("cannot add clone source: %s", strerror(-ret));
662 for (i = optind; i < argc; i++) {
664 subvol = realpath(argv[i], NULL);
667 error("unable to resolve %s", argv[i]);
671 ret = find_mount_root(subvol, &mount_root);
673 error("find_mount_root failed on %s: %s", subvol,
678 error("%s does not belong to btrfs mount point",
683 if (strcmp(send.root_path, mount_root) != 0) {
685 error("all subvolumes must be from the same filesystem");
690 ret = is_subvol_ro(&send, subvol);
695 error("subvolume %s is not read-only", subvol);
700 if ((send_flags & BTRFS_SEND_FLAG_NO_FILE_DATA) && g_verbose > 1)
702 fprintf(stderr, "Mode NO_FILE_DATA enabled\n");
704 for (i = optind; i < argc; i++) {
712 fprintf(stderr, "At subvol %s\n", subvol);
714 subvol = realpath(subvol, NULL);
717 error("realpath %s failed: %s", argv[i], strerror(-ret));
721 if (!full_send && !snapshot_parent) {
722 ret = set_root_info(&send, subvol, &root_id);
726 ret = find_good_parent(&send, root_id, &parent_root_id);
728 error("parent determination failed for %lld",
734 if (new_end_cmd_semantic) {
735 /* require new kernel */
736 is_first_subvol = (i == optind);
737 is_last_subvol = (i == argc - 1);
739 /* be compatible to old and new kernel */
743 ret = do_send(&send, parent_root_id, is_first_subvol,
744 is_last_subvol, subvol, send_flags);
748 if (!full_send && !snapshot_parent) {
749 /* done with this subvol, so add it to the clone sources */
750 ret = add_clone_source(&send, root_id);
752 error("cannot add clone source: %s", strerror(-ret));
755 free_send_info(&send);
763 free(snapshot_parent);
764 free(send.clone_sources);
765 free_send_info(&send);
769 const char * const cmd_send_usage[] = {
770 "btrfs send [-ve] [-p <parent>] [-c <clone-src>] [-f <outfile>] <subvol> [<subvol>...]",
771 "Send the subvolume(s) to stdout.",
772 "Sends the subvolume(s) specified by <subvol> to stdout.",
773 "<subvol> should be read-only here.",
774 "By default, this will send the whole subvolume. To do an incremental",
775 "send, use '-p <parent>'. If you want to allow btrfs to clone from",
776 "any additional local snapshots, use '-c <clone-src>' (multiple times",
777 "where applicable). You must not specify clone sources unless you",
778 "guarantee that these snapshots are exactly in the same state on both",
779 "sides, the sender and the receiver. It is allowed to omit the",
780 "'-p <parent>' option when '-c <clone-src>' options are given, in",
781 "which case 'btrfs send' will determine a suitable parent among the",
782 "clone sources itself.",
784 "-e If sending multiple subvols at once, use the new",
785 " format and omit the end-cmd between the subvols.",
786 "-p <parent> Send an incremental stream from <parent> to",
788 "-c <clone-src> Use this snapshot as a clone source for an ",
789 " incremental send (multiple allowed)",
790 "-f <outfile> Output is normally written to stdout. To write to",
791 " a file, use this option. An alternative would be to",
793 "--no-data send in NO_FILE_DATA mode, Note: the output stream",
794 " does not contain any file data and thus cannot be used",
795 " to transfer changes. This mode is faster and useful to",
796 " show the differences in metadata.",
797 "-v|--verbose enable verbose output to stderr, each occurrence of",
798 " this option increases verbosity",
799 "-q|--quiet suppress all messages, except errors",