2 * An implementation of the host initiated guest snapshot for Hyper-V.
5 * Copyright (C) 2013, Microsoft, Inc.
6 * Author : K. Y. Srinivasan <kys@microsoft.com>
8 * This program is free software; you can redistribute it and/or modify it
9 * under the terms of the GNU General Public License version 2 as published
10 * by the Free Software Foundation.
12 * This program is distributed in the hope that it will be useful, but
13 * WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
15 * NON INFRINGEMENT. See the GNU General Public License for more
21 #include <sys/types.h>
23 #include <sys/ioctl.h>
34 #include <linux/major.h>
35 #include <linux/hyperv.h>
39 /* Don't use syslog() in the function since that can cause write to disk */
40 static int vss_do_freeze(char *dir, unsigned int cmd)
42 int ret, fd = open(dir, O_RDONLY);
47 ret = ioctl(fd, cmd, 0);
50 * If a partition is mounted more than once, only the first
51 * FREEZE/THAW can succeed and the later ones will get
52 * EBUSY/EINVAL respectively: there could be 2 cases:
53 * 1) a user may mount the same partition to differnt directories
54 * by mistake or on purpose;
55 * 2) The subvolume of btrfs appears to have the same partition
56 * mounted more than once.
59 if ((cmd == FIFREEZE && errno == EBUSY) ||
60 (cmd == FITHAW && errno == EINVAL)) {
70 static int vss_operate(int operation)
72 char match[] = "/dev/";
76 char errdir[1024] = {0};
78 int error = 0, root_seen = 0, save_errno = 0;
91 mounts = setmntent("/proc/mounts", "r");
95 while ((ent = getmntent(mounts))) {
96 if (strncmp(ent->mnt_fsname, match, strlen(match)))
98 if (stat(ent->mnt_fsname, &sb) == -1)
100 if (S_ISBLK(sb.st_mode) && major(sb.st_rdev) == LOOP_MAJOR)
102 if (hasmntopt(ent, MNTOPT_RO) != NULL)
104 if (strcmp(ent->mnt_type, "vfat") == 0)
106 if (strcmp(ent->mnt_dir, "/") == 0) {
110 error |= vss_do_freeze(ent->mnt_dir, cmd);
111 if (error && operation == VSS_OP_FREEZE)
118 error |= vss_do_freeze("/", cmd);
119 if (error && operation == VSS_OP_FREEZE)
127 strncpy(errdir, ent->mnt_dir, sizeof(errdir)-1);
130 vss_operate(VSS_OP_THAW);
131 /* Call syslog after we thaw all filesystems */
133 syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s",
134 errdir, save_errno, strerror(save_errno));
136 syslog(LOG_ERR, "FREEZE of / failed; error:%d %s", save_errno,
137 strerror(save_errno));
142 void print_usage(char *argv[])
144 fprintf(stderr, "Usage: %s [options]\n"
146 " -n, --no-daemon stay in foreground, don't daemonize\n"
147 " -h, --help print this help\n", argv[0]);
150 int main(int argc, char *argv[])
156 struct hv_vss_msg vss_msg[1];
157 int daemonize = 1, long_index = 0, opt;
158 int in_handshake = 1;
161 static struct option long_options[] = {
162 {"help", no_argument, 0, 'h' },
163 {"no-daemon", no_argument, 0, 'n' },
167 while ((opt = getopt_long(argc, argv, "hn", long_options,
168 &long_index)) != -1) {
180 if (daemonize && daemon(1, 0))
183 openlog("Hyper-V VSS", 0, LOG_USER);
184 syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
186 vss_fd = open("/dev/vmbus/hv_vss", O_RDWR);
188 syslog(LOG_ERR, "open /dev/vmbus/hv_vss failed; error: %d %s",
189 errno, strerror(errno));
193 * Register ourselves with the kernel.
195 vss_msg->vss_hdr.operation = VSS_OP_REGISTER1;
197 len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
199 syslog(LOG_ERR, "registration to kernel failed; error: %d %s",
200 errno, strerror(errno));
211 if (poll(&pfd, 1, -1) < 0) {
212 syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno));
213 if (errno == EINVAL) {
221 len = read(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
224 if (len != sizeof(kernel_modver)) {
225 syslog(LOG_ERR, "invalid version negotiation");
228 kernel_modver = *(__u32 *)vss_msg;
230 syslog(LOG_INFO, "VSS: kernel module version: %d",
235 if (len != sizeof(struct hv_vss_msg)) {
236 syslog(LOG_ERR, "read failed; error:%d %s",
237 errno, strerror(errno));
242 op = vss_msg->vss_hdr.operation;
248 error = vss_operate(op);
249 syslog(LOG_INFO, "VSS: op=%s: %s\n",
250 op == VSS_OP_FREEZE ? "FREEZE" : "THAW",
251 error ? "failed" : "succeeded");
255 syslog(LOG_ERR, "op=%d failed!", op);
256 syslog(LOG_ERR, "report it with these files:");
257 syslog(LOG_ERR, "/etc/fstab and /proc/mounts");
260 case VSS_OP_HOT_BACKUP:
261 syslog(LOG_INFO, "VSS: op=CHECK HOT BACKUP\n");
264 syslog(LOG_ERR, "Illegal op:%d\n", op);
266 vss_msg->error = error;
267 len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
268 if (len != sizeof(struct hv_vss_msg)) {
269 syslog(LOG_ERR, "write failed; error: %d %s", errno,
272 if (op == VSS_OP_FREEZE)
273 vss_operate(VSS_OP_THAW);