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>
33 #include <linux/hyperv.h>
37 /* Don't use syslog() in the function since that can cause write to disk */
38 static int vss_do_freeze(char *dir, unsigned int cmd)
40 int ret, fd = open(dir, O_RDONLY);
45 ret = ioctl(fd, cmd, 0);
48 * If a partition is mounted more than once, only the first
49 * FREEZE/THAW can succeed and the later ones will get
50 * EBUSY/EINVAL respectively: there could be 2 cases:
51 * 1) a user may mount the same partition to differnt directories
52 * by mistake or on purpose;
53 * 2) The subvolume of btrfs appears to have the same partition
54 * mounted more than once.
57 if ((cmd == FIFREEZE && errno == EBUSY) ||
58 (cmd == FITHAW && errno == EINVAL)) {
68 static int vss_operate(int operation)
70 char match[] = "/dev/";
73 char errdir[1024] = {0};
75 int error = 0, root_seen = 0, save_errno = 0;
88 mounts = setmntent("/proc/mounts", "r");
92 while ((ent = getmntent(mounts))) {
93 if (strncmp(ent->mnt_fsname, match, strlen(match)))
95 if (hasmntopt(ent, MNTOPT_RO) != NULL)
97 if (strcmp(ent->mnt_type, "vfat") == 0)
99 if (strcmp(ent->mnt_dir, "/") == 0) {
103 error |= vss_do_freeze(ent->mnt_dir, cmd);
104 if (error && operation == VSS_OP_FREEZE)
111 error |= vss_do_freeze("/", cmd);
112 if (error && operation == VSS_OP_FREEZE)
120 strncpy(errdir, ent->mnt_dir, sizeof(errdir)-1);
123 vss_operate(VSS_OP_THAW);
124 /* Call syslog after we thaw all filesystems */
126 syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s",
127 errdir, save_errno, strerror(save_errno));
129 syslog(LOG_ERR, "FREEZE of / failed; error:%d %s", save_errno,
130 strerror(save_errno));
135 void print_usage(char *argv[])
137 fprintf(stderr, "Usage: %s [options]\n"
139 " -n, --no-daemon stay in foreground, don't daemonize\n"
140 " -h, --help print this help\n", argv[0]);
143 int main(int argc, char *argv[])
149 struct hv_vss_msg vss_msg[1];
150 int daemonize = 1, long_index = 0, opt;
151 int in_handshake = 1;
154 static struct option long_options[] = {
155 {"help", no_argument, 0, 'h' },
156 {"no-daemon", no_argument, 0, 'n' },
160 while ((opt = getopt_long(argc, argv, "hn", long_options,
161 &long_index)) != -1) {
175 if (daemonize && daemon(1, 0))
178 openlog("Hyper-V VSS", 0, LOG_USER);
179 syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
181 vss_fd = open("/dev/vmbus/hv_vss", O_RDWR);
183 syslog(LOG_ERR, "open /dev/vmbus/hv_vss failed; error: %d %s",
184 errno, strerror(errno));
188 * Register ourselves with the kernel.
190 vss_msg->vss_hdr.operation = VSS_OP_REGISTER1;
192 len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
194 syslog(LOG_ERR, "registration to kernel failed; error: %d %s",
195 errno, strerror(errno));
206 if (poll(&pfd, 1, -1) < 0) {
207 syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno));
208 if (errno == EINVAL) {
216 len = read(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
219 if (len != sizeof(kernel_modver)) {
220 syslog(LOG_ERR, "invalid version negotiation");
223 kernel_modver = *(__u32 *)vss_msg;
225 syslog(LOG_INFO, "VSS: kernel module version: %d",
230 if (len != sizeof(struct hv_vss_msg)) {
231 syslog(LOG_ERR, "read failed; error:%d %s",
232 errno, strerror(errno));
237 op = vss_msg->vss_hdr.operation;
243 error = vss_operate(op);
244 syslog(LOG_INFO, "VSS: op=%s: %s\n",
245 op == VSS_OP_FREEZE ? "FREEZE" : "THAW",
246 error ? "failed" : "succeeded");
250 syslog(LOG_ERR, "op=%d failed!", op);
251 syslog(LOG_ERR, "report it with these files:");
252 syslog(LOG_ERR, "/etc/fstab and /proc/mounts");
256 syslog(LOG_ERR, "Illegal op:%d\n", op);
258 vss_msg->error = error;
259 len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
260 if (len != sizeof(struct hv_vss_msg)) {
261 syslog(LOG_ERR, "write failed; error: %d %s", errno,