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>
25 #include <sys/sysmacros.h>
35 #include <linux/major.h>
36 #include <linux/hyperv.h>
42 /* Don't use syslog() in the function since that can cause write to disk */
43 static int vss_do_freeze(char *dir, unsigned int cmd)
45 int ret, fd = open(dir, O_RDONLY);
50 ret = ioctl(fd, cmd, 0);
53 * If a partition is mounted more than once, only the first
54 * FREEZE/THAW can succeed and the later ones will get
55 * EBUSY/EINVAL respectively: there could be 2 cases:
56 * 1) a user may mount the same partition to differnt directories
57 * by mistake or on purpose;
58 * 2) The subvolume of btrfs appears to have the same partition
59 * mounted more than once.
62 if ((cmd == FIFREEZE && errno == EBUSY) ||
63 (cmd == FITHAW && errno == EINVAL)) {
73 static bool is_dev_loop(const char *blkname)
80 buffer = malloc(PATH_MAX);
82 syslog(LOG_ERR, "Can't allocate memory!");
86 snprintf(buffer, PATH_MAX, "%s/loop", blkname);
87 if (!access(buffer, R_OK | X_OK)) {
90 } else if (errno != ENOENT) {
91 syslog(LOG_ERR, "Can't access: %s; error:%d %s!",
92 buffer, errno, strerror(errno));
95 snprintf(buffer, PATH_MAX, "%s/slaves", blkname);
96 dir = opendir(buffer);
99 syslog(LOG_ERR, "Can't opendir: %s; error:%d %s!",
100 buffer, errno, strerror(errno));
104 while ((entry = readdir(dir)) != NULL) {
105 if (strcmp(entry->d_name, ".") == 0 ||
106 strcmp(entry->d_name, "..") == 0)
109 snprintf(buffer, PATH_MAX, "%s/slaves/%s", blkname,
111 if (is_dev_loop(buffer)) {
122 static int vss_operate(int operation)
124 char match[] = "/dev/";
128 char errdir[1024] = {0};
129 char blkdir[23]; /* /sys/dev/block/XXX:XXX */
131 int error = 0, root_seen = 0, save_errno = 0;
144 mounts = setmntent("/proc/mounts", "r");
148 while ((ent = getmntent(mounts))) {
149 if (strncmp(ent->mnt_fsname, match, strlen(match)))
151 if (stat(ent->mnt_fsname, &sb)) {
152 syslog(LOG_ERR, "Can't stat: %s; error:%d %s!",
153 ent->mnt_fsname, errno, strerror(errno));
155 sprintf(blkdir, "/sys/dev/block/%d:%d",
156 major(sb.st_rdev), minor(sb.st_rdev));
157 if (is_dev_loop(blkdir))
160 if (hasmntopt(ent, MNTOPT_RO) != NULL)
162 if (strcmp(ent->mnt_type, "vfat") == 0)
164 if (strcmp(ent->mnt_dir, "/") == 0) {
168 error |= vss_do_freeze(ent->mnt_dir, cmd);
169 if (error && operation == VSS_OP_FREEZE)
176 error |= vss_do_freeze("/", cmd);
177 if (error && operation == VSS_OP_FREEZE)
185 strncpy(errdir, ent->mnt_dir, sizeof(errdir)-1);
188 vss_operate(VSS_OP_THAW);
189 /* Call syslog after we thaw all filesystems */
191 syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s",
192 errdir, save_errno, strerror(save_errno));
194 syslog(LOG_ERR, "FREEZE of / failed; error:%d %s", save_errno,
195 strerror(save_errno));
200 void print_usage(char *argv[])
202 fprintf(stderr, "Usage: %s [options]\n"
204 " -n, --no-daemon stay in foreground, don't daemonize\n"
205 " -h, --help print this help\n", argv[0]);
208 int main(int argc, char *argv[])
214 struct hv_vss_msg vss_msg[1];
215 int daemonize = 1, long_index = 0, opt;
216 int in_handshake = 1;
219 static struct option long_options[] = {
220 {"help", no_argument, 0, 'h' },
221 {"no-daemon", no_argument, 0, 'n' },
225 while ((opt = getopt_long(argc, argv, "hn", long_options,
226 &long_index)) != -1) {
240 if (daemonize && daemon(1, 0))
243 openlog("Hyper-V VSS", 0, LOG_USER);
244 syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
246 vss_fd = open("/dev/vmbus/hv_vss", O_RDWR);
248 syslog(LOG_ERR, "open /dev/vmbus/hv_vss failed; error: %d %s",
249 errno, strerror(errno));
253 * Register ourselves with the kernel.
255 vss_msg->vss_hdr.operation = VSS_OP_REGISTER1;
257 len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
259 syslog(LOG_ERR, "registration to kernel failed; error: %d %s",
260 errno, strerror(errno));
271 if (poll(&pfd, 1, -1) < 0) {
272 syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno));
273 if (errno == EINVAL) {
281 len = read(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
284 if (len != sizeof(kernel_modver)) {
285 syslog(LOG_ERR, "invalid version negotiation");
288 kernel_modver = *(__u32 *)vss_msg;
290 syslog(LOG_INFO, "VSS: kernel module version: %d",
295 if (len != sizeof(struct hv_vss_msg)) {
296 syslog(LOG_ERR, "read failed; error:%d %s",
297 errno, strerror(errno));
302 op = vss_msg->vss_hdr.operation;
308 error = vss_operate(op);
309 syslog(LOG_INFO, "VSS: op=%s: %s\n",
310 op == VSS_OP_FREEZE ? "FREEZE" : "THAW",
311 error ? "failed" : "succeeded");
315 syslog(LOG_ERR, "op=%d failed!", op);
316 syslog(LOG_ERR, "report it with these files:");
317 syslog(LOG_ERR, "/etc/fstab and /proc/mounts");
320 case VSS_OP_HOT_BACKUP:
321 syslog(LOG_INFO, "VSS: op=CHECK HOT BACKUP\n");
324 syslog(LOG_ERR, "Illegal op:%d\n", op);
326 vss_msg->error = error;
327 len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
328 if (len != sizeof(struct hv_vss_msg)) {
329 syslog(LOG_ERR, "write failed; error: %d %s", errno,
332 if (op == VSS_OP_FREEZE)
333 vss_operate(VSS_OP_THAW);