btrfs-progs/cmds-send.c

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/*
* Copyright (C) 2012 Alexander Block. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#define _GNU_SOURCE
#include "kerncompat.h"
#include <unistd.h>
#include <stdint.h>
#include <dirent.h>
#include <fcntl.h>
#include <pthread.h>
#include <math.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <libgen.h>
#include <mntent.h>
#include <uuid/uuid.h>
#include "ctree.h"
#include "ioctl.h"
#include "commands.h"
#include "list.h"
#include "send.h"
#include "send-utils.h"
static int g_verbose = 0;
struct btrfs_send {
int send_fd;
int dump_fd;
int mnt_fd;
u64 *clone_sources;
u64 clone_sources_count;
char *root_path;
struct subvol_uuid_search sus;
};
int find_mount_root(const char *path, char **mount_root)
{
FILE *mnttab;
int fd;
struct mntent *ent;
int len;
int longest_matchlen = 0;
char *longest_match = NULL;
fd = open(path, O_RDONLY | O_NOATIME);
if (fd < 0)
return -errno;
close(fd);
mnttab = fopen("/etc/mtab", "r");
while ((ent = getmntent(mnttab))) {
len = strlen(ent->mnt_dir);
if (strncmp(ent->mnt_dir, path, len) == 0) {
/* match found */
if (longest_matchlen < len) {
free(longest_match);
longest_matchlen = len;
longest_match = strdup(ent->mnt_dir);
}
}
}
*mount_root = realpath(longest_match, NULL);
free(longest_match);
return 0;
}
static int get_root_id(struct btrfs_send *s, const char *path, u64 *root_id)
{
struct subvol_info *si;
si = subvol_uuid_search(&s->sus, 0, NULL, 0, path,
subvol_search_by_path);
if (!si)
return -ENOENT;
*root_id = si->root_id;
return 0;
}
static struct subvol_info *get_parent(struct btrfs_send *s, u64 root_id)
{
struct subvol_info *si;
si = subvol_uuid_search(&s->sus, root_id, NULL, 0, NULL,
subvol_search_by_root_id);
if (!si)
return NULL;
si = subvol_uuid_search(&s->sus, 0, si->parent_uuid, 0, NULL,
subvol_search_by_uuid);
if (!si)
return NULL;
return si;
}
static int find_good_parent(struct btrfs_send *s, u64 root_id, u64 *found)
{
int ret;
struct subvol_info *parent;
struct subvol_info *parent2;
struct subvol_info *best_parent = NULL;
__s64 tmp;
u64 best_diff = (u64)-1;
int i;
parent = get_parent(s, root_id);
if (!parent) {
ret = -ENOENT;
goto out;
}
for (i = 0; i < s->clone_sources_count; i++) {
if (s->clone_sources[i] == parent->root_id) {
best_parent = parent;
goto out_found;
}
}
for (i = 0; i < s->clone_sources_count; i++) {
parent2 = get_parent(s, s->clone_sources[i]);
if (parent2 != parent)
continue;
parent2 = subvol_uuid_search(&s->sus, s->clone_sources[i], NULL,
0, NULL, subvol_search_by_root_id);
tmp = parent2->ctransid - parent->ctransid;
if (tmp < 0)
tmp *= -1;
if (tmp < best_diff) {
best_parent = parent;
best_diff = tmp;
}
}
if (!best_parent) {
ret = -ENOENT;
goto out;
}
out_found:
*found = best_parent->root_id;
ret = 0;
out:
return ret;
}
static void add_clone_source(struct btrfs_send *s, u64 root_id)
{
s->clone_sources = realloc(s->clone_sources,
sizeof(*s->clone_sources) * (s->clone_sources_count + 1));
s->clone_sources[s->clone_sources_count++] = root_id;
}
static int write_buf(int fd, const void *buf, int size)
{
int ret;
int pos = 0;
while (pos < size) {
ret = write(fd, (char*)buf + pos, size - pos);
if (ret < 0) {
ret = -errno;
fprintf(stderr, "ERROR: failed to dump stream. %s",
strerror(-ret));
goto out;
}
if (!ret) {
ret = -EIO;
fprintf(stderr, "ERROR: failed to dump stream. %s",
strerror(-ret));
goto out;
}
pos += ret;
}
ret = 0;
out:
return ret;
}
static void *dump_thread(void *arg_)
{
int ret;
struct btrfs_send *s = (struct btrfs_send*)arg_;
char buf[4096];
int readed;
while (1) {
readed = read(s->send_fd, buf, sizeof(buf));
if (readed < 0) {
ret = -errno;
fprintf(stderr, "ERROR: failed to read stream from "
"kernel. %s\n", strerror(-ret));
goto out;
}
if (!readed) {
ret = 0;
goto out;
}
ret = write_buf(s->dump_fd, buf, readed);
if (ret < 0)
goto out;
}
out:
if (ret < 0) {
exit(-ret);
}
return ERR_PTR(ret);
}
static int do_send(struct btrfs_send *send, u64 root_id, u64 parent_root)
{
int ret;
pthread_t t_read;
pthread_attr_t t_attr;
struct btrfs_ioctl_send_args io_send;
struct subvol_info *si;
void *t_err = NULL;
int subvol_fd = -1;
int pipefd[2];
si = subvol_uuid_search(&send->sus, root_id, NULL, 0, NULL,
subvol_search_by_root_id);
if (!si) {
ret = -ENOENT;
fprintf(stderr, "ERROR: could not find subvol info for %llu",
root_id);
goto out;
}
subvol_fd = openat(send->mnt_fd, si->path, O_RDONLY | O_NOATIME);
if (subvol_fd < 0) {
ret = -errno;
fprintf(stderr, "ERROR: open %s failed. %s\n", si->path,
strerror(-ret));
goto out;
}
ret = pthread_attr_init(&t_attr);
ret = pipe(pipefd);
if (ret < 0) {
ret = -errno;
fprintf(stderr, "ERROR: pipe failed. %s\n", strerror(-ret));
goto out;
}
io_send.send_fd = pipefd[1];
send->send_fd = pipefd[0];
if (!ret)
ret = pthread_create(&t_read, &t_attr, dump_thread,
send);
if (ret) {
ret = -ret;
fprintf(stderr, "ERROR: thread setup failed: %s\n",
strerror(-ret));
goto out;
}
io_send.clone_sources = (__u64*)send->clone_sources;
io_send.clone_sources_count = send->clone_sources_count;
io_send.parent_root = parent_root;
ret = ioctl(subvol_fd, BTRFS_IOC_SEND, &io_send);
if (ret) {
ret = -errno;
fprintf(stderr, "ERROR: send ioctl failed with %d: %s\n", ret,
strerror(-ret));
goto out;
}
if (g_verbose > 0)
fprintf(stderr, "BTRFS_IOC_SEND returned %d\n", ret);
if (g_verbose > 0)
fprintf(stderr, "joining genl thread\n");
close(pipefd[1]);
pipefd[1] = 0;
ret = pthread_join(t_read, &t_err);
if (ret) {
ret = -ret;
fprintf(stderr, "ERROR: pthread_join failed: %s\n",
strerror(-ret));
goto out;
}
if (t_err) {
ret = (long int)t_err;
fprintf(stderr, "ERROR: failed to process send stream, ret=%ld "
"(%s)\n", (long int)t_err, strerror(-ret));
goto out;
}
pthread_attr_destroy(&t_attr);
ret = 0;
out:
if (subvol_fd != -1)
close(subvol_fd);
if (pipefd[0])
close(pipefd[0]);
if (pipefd[1])
close(pipefd[1]);
return ret;
}
static const char *get_subvol_name(struct btrfs_send *s, const char *full_path)
{
int len = strlen(s->root_path);
if (!len)
return full_path;
if (s->root_path[len - 1] != '/')
len += 1;
return full_path + len;
}
static int init_root_path(struct btrfs_send *s, const char *subvol)
{
int ret = 0;
if (s->root_path)
goto out;
ret = find_mount_root(subvol, &s->root_path);
if (ret < 0) {
ret = -EINVAL;
fprintf(stderr, "ERROR: failed to determine mount point "
"for %s\n", subvol);
goto out;
}
s->mnt_fd = open(s->root_path, O_RDONLY | O_NOATIME);
if (s->mnt_fd < 0) {
ret = -errno;
fprintf(stderr, "ERROR: can't open '%s': %s\n", s->root_path,
strerror(-ret));
goto out;
}
ret = subvol_uuid_search_init(s->mnt_fd, &s->sus);
if (ret < 0) {
fprintf(stderr, "ERROR: failed to initialize subvol search. "
"%s\n", strerror(-ret));
goto out;
}
out:
return ret;
}
static int is_subvol_ro(struct btrfs_send *s, char *subvol)
{
int ret;
u64 flags;
int fd = -1;
fd = openat(s->mnt_fd, subvol, O_RDONLY | O_NOATIME);
if (fd < 0) {
ret = -errno;
fprintf(stderr, "ERROR: failed to open %s. %s\n",
subvol, strerror(-ret));
goto out;
}
ret = ioctl(fd, BTRFS_IOC_SUBVOL_GETFLAGS, &flags);
if (ret < 0) {
ret = -errno;
fprintf(stderr, "ERROR: failed to get flags for subvolume. "
"%s\n", strerror(-ret));
goto out;
}
if (flags & BTRFS_SUBVOL_RDONLY)
ret = 1;
else
ret = 0;
out:
if (fd != -1)
close(fd);
return ret;
}
int cmd_send_start(int argc, char **argv)
{
char *subvol = NULL;
char c;
int ret;
char *outname = NULL;
struct btrfs_send send;
u32 i;
char *mount_root = NULL;
char *snapshot_parent = NULL;
u64 root_id;
u64 parent_root_id = 0;
memset(&send, 0, sizeof(send));
send.dump_fd = fileno(stdout);
if (isatty(send.dump_fd)) {
fprintf(stderr, "ERROR: not dumping send stream into a terminal, redirect it into a file\n");
return 1;
}
while ((c = getopt(argc, argv, "vf:i:p:")) != -1) {
switch (c) {
case 'v':
g_verbose++;
break;
case 'i': {
subvol = realpath(optarg, NULL);
if (!subvol) {
ret = -errno;
fprintf(stderr, "ERROR: realpath %s failed. "
"%s\n", optarg, strerror(-ret));
goto out;
}
ret = init_root_path(&send, subvol);
if (ret < 0)
goto out;
ret = get_root_id(&send, get_subvol_name(&send, subvol),
&root_id);
if (ret < 0) {
fprintf(stderr, "ERROR: could not resolve "
"root_id for %s\n", subvol);
goto out;
}
add_clone_source(&send, root_id);
free(subvol);
break;
}
case 'f':
outname = optarg;
break;
case 'p':
snapshot_parent = realpath(optarg, NULL);
if (!snapshot_parent) {
ret = -errno;
fprintf(stderr, "ERROR: realpath %s failed. "
"%s\n", optarg, strerror(-ret));
goto out;
}
break;
case '?':
default:
fprintf(stderr, "ERROR: send args invalid.\n");
return 1;
}
}
if (optind == argc) {
fprintf(stderr, "ERROR: send needs path to snapshot\n");
return 1;
}
if (outname != NULL) {
send.dump_fd = creat(outname, 0600);
if (send.dump_fd == -1) {
ret = -errno;
fprintf(stderr, "ERROR: can't create '%s': %s\n",
outname, strerror(-ret));
goto out;
}
}
/* use first send subvol to determine mount_root */
subvol = argv[optind];
subvol = realpath(argv[optind], NULL);
if (!subvol) {
ret = -errno;
fprintf(stderr, "ERROR: unable to resolve %s\n", argv[optind]);
goto out;
}
ret = init_root_path(&send, subvol);
if (ret < 0)
goto out;
if (snapshot_parent != NULL) {
ret = get_root_id(&send,
get_subvol_name(&send, snapshot_parent),
&parent_root_id);
if (ret < 0) {
fprintf(stderr, "ERROR: could not resolve root_id "
"for %s\n", snapshot_parent);
goto out;
}
add_clone_source(&send, parent_root_id);
}
for (i = optind; i < argc; i++) {
subvol = realpath(argv[i], NULL);
if (!subvol) {
ret = -errno;
fprintf(stderr, "ERROR: unable to resolve %s\n", argv[i]);
goto out;
}
ret = find_mount_root(subvol, &mount_root);
if (ret < 0) {
fprintf(stderr, "ERROR: find_mount_root failed on %s: "
"%s\n", subvol,
strerror(-ret));
goto out;
}
if (strcmp(send.root_path, mount_root) != 0) {
ret = -EINVAL;
fprintf(stderr, "ERROR: all subvols must be from the "
"same fs.\n");
goto out;
}
free(mount_root);
ret = is_subvol_ro(&send, subvol);
if (ret < 0)
goto out;
if (!ret) {
ret = -EINVAL;
fprintf(stderr, "ERROR: %s is not read-only.\n",
subvol);
goto out;
}
free(subvol);
}
for (i = optind; i < argc; i++) {
subvol = argv[i];
fprintf(stderr, "At subvol %s\n", subvol);
subvol = realpath(subvol, NULL);
if (!subvol) {
ret = -errno;
fprintf(stderr, "ERROR: realpath %s failed. "
"%s\n", argv[i], strerror(-ret));
goto out;
}
ret = get_root_id(&send, get_subvol_name(&send, subvol),
&root_id);
if (ret < 0) {
fprintf(stderr, "ERROR: could not resolve root_id "
"for %s\n", subvol);
goto out;
}
if (!parent_root_id) {
ret = find_good_parent(&send, root_id, &parent_root_id);
if (ret < 0)
parent_root_id = 0;
}
ret = is_subvol_ro(&send, subvol);
if (ret < 0)
goto out;
if (!ret) {
ret = -EINVAL;
fprintf(stderr, "ERROR: %s is not read-only.\n",
subvol);
goto out;
}
ret = do_send(&send, root_id, parent_root_id);
if (ret < 0)
goto out;
/* done with this subvol, so add it to the clone sources */
add_clone_source(&send, root_id);
parent_root_id = 0;
free(subvol);
}
ret = 0;
out:
if (send.mnt_fd >= 0)
close(send.mnt_fd);
return ret;
}
static const char * const send_cmd_group_usage[] = {
"btrfs send <command> <args>",
NULL
};
static const char * const cmd_send_usage[] = {
"btrfs send [-v] [-i <subvol>] [-p <parent>] <subvol>",
"Send the subvolume to stdout.",
"Sends the subvolume specified by <subvol> to stdout.",
"By default, this will send the whole subvolume. To do",
"an incremental send, one or multiple '-i <clone_source>'",
"arguments have to be specified. A 'clone source' is",
"a subvolume that is known to exist on the receiving",
"side in exactly the same state as on the sending side.\n",
"Normally, a good snapshot parent is searched automatically",
"in the list of 'clone sources'. To override this, use",
"'-p <parent>' to manually specify a snapshot parent.",
"A manually specified snapshot parent is also regarded",
"as 'clone source'.\n",
"-v Enable verbose debug output. Each",
" occurrency of this option increases the",
" verbose level more.",
"-i <subvol> Informs btrfs send that this subvolume,",
" can be taken as 'clone source'. This can",
" be used for incremental sends.",
"-p <subvol> Disable automatic snaphot parent",
" determination and use <subvol> as parent.",
" This subvolume is also added to the list",
" of 'clone sources' (see -i).",
"-f <outfile> Output is normally written to stdout.",
" To write to a file, use this option.",
" An alternative would be to use pipes.",
NULL
};
const struct cmd_group send_cmd_group = {
send_cmd_group_usage, NULL, {
{ "send", cmd_send_start, cmd_send_usage, NULL, 0 },
{ 0, 0, 0, 0, 0 },
},
};
int cmd_send(int argc, char **argv)
{
return cmd_send_start(argc, argv);
}