1 /*
2 * An implementation of the host initiated guest snapshot for Hyper-V.
3 *
4 *
5 * Copyright (C) 2013, Microsoft, Inc.
6 * Author : K. Y. Srinivasan <kys@microsoft.com>
7 *
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.
11 *
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
16 * details.
17 *
18 */
19
20
21 #include <sys/types.h>
22 #include <sys/poll.h>
23 #include <sys/ioctl.h>
24 #include <sys/stat.h>
25 #include <sys/sysmacros.h>
26 #include <fcntl.h>
27 #include <stdio.h>
28 #include <mntent.h>
29 #include <stdlib.h>
30 #include <unistd.h>
31 #include <string.h>
32 #include <ctype.h>
33 #include <errno.h>
34 #include <linux/fs.h>
35 #include <linux/major.h>
36 #include <linux/hyperv.h>
37 #include <syslog.h>
38 #include <getopt.h>
39 #include <stdbool.h>
40 #include <dirent.h>
41
42 /* Don't use syslog() in the function since that can cause write to disk */
vss_do_freeze(char * dir,unsigned int cmd)43 static int vss_do_freeze(char *dir, unsigned int cmd)
44 {
45 int ret, fd = open(dir, O_RDONLY);
46
47 if (fd < 0)
48 return 1;
49
50 ret = ioctl(fd, cmd, 0);
51
52 /*
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.
60 */
61 if (ret) {
62 if ((cmd == FIFREEZE && errno == EBUSY) ||
63 (cmd == FITHAW && errno == EINVAL)) {
64 close(fd);
65 return 0;
66 }
67 }
68
69 close(fd);
70 return !!ret;
71 }
72
is_dev_loop(const char * blkname)73 static bool is_dev_loop(const char *blkname)
74 {
75 char *buffer;
76 DIR *dir;
77 struct dirent *entry;
78 bool ret = false;
79
80 buffer = malloc(PATH_MAX);
81 if (!buffer) {
82 syslog(LOG_ERR, "Can't allocate memory!");
83 exit(1);
84 }
85
86 snprintf(buffer, PATH_MAX, "%s/loop", blkname);
87 if (!access(buffer, R_OK | X_OK)) {
88 ret = true;
89 goto free_buffer;
90 } else if (errno != ENOENT) {
91 syslog(LOG_ERR, "Can't access: %s; error:%d %s!",
92 buffer, errno, strerror(errno));
93 }
94
95 snprintf(buffer, PATH_MAX, "%s/slaves", blkname);
96 dir = opendir(buffer);
97 if (!dir) {
98 if (errno != ENOENT)
99 syslog(LOG_ERR, "Can't opendir: %s; error:%d %s!",
100 buffer, errno, strerror(errno));
101 goto free_buffer;
102 }
103
104 while ((entry = readdir(dir)) != NULL) {
105 if (strcmp(entry->d_name, ".") == 0 ||
106 strcmp(entry->d_name, "..") == 0)
107 continue;
108
109 snprintf(buffer, PATH_MAX, "%s/slaves/%s", blkname,
110 entry->d_name);
111 if (is_dev_loop(buffer)) {
112 ret = true;
113 break;
114 }
115 }
116 closedir(dir);
117 free_buffer:
118 free(buffer);
119 return ret;
120 }
121
vss_operate(int operation)122 static int vss_operate(int operation)
123 {
124 char match[] = "/dev/";
125 FILE *mounts;
126 struct mntent *ent;
127 struct stat sb;
128 char errdir[1024] = {0};
129 char blkdir[23]; /* /sys/dev/block/XXX:XXX */
130 unsigned int cmd;
131 int error = 0, root_seen = 0, save_errno = 0;
132
133 switch (operation) {
134 case VSS_OP_FREEZE:
135 cmd = FIFREEZE;
136 break;
137 case VSS_OP_THAW:
138 cmd = FITHAW;
139 break;
140 default:
141 return -1;
142 }
143
144 mounts = setmntent("/proc/mounts", "r");
145 if (mounts == NULL)
146 return -1;
147
148 while ((ent = getmntent(mounts))) {
149 if (strncmp(ent->mnt_fsname, match, strlen(match)))
150 continue;
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));
154 } else {
155 sprintf(blkdir, "/sys/dev/block/%d:%d",
156 major(sb.st_rdev), minor(sb.st_rdev));
157 if (is_dev_loop(blkdir))
158 continue;
159 }
160 if (hasmntopt(ent, MNTOPT_RO) != NULL)
161 continue;
162 if (strcmp(ent->mnt_type, "vfat") == 0)
163 continue;
164 if (strcmp(ent->mnt_dir, "/") == 0) {
165 root_seen = 1;
166 continue;
167 }
168 error |= vss_do_freeze(ent->mnt_dir, cmd);
169 if (error && operation == VSS_OP_FREEZE)
170 goto err;
171 }
172
173 endmntent(mounts);
174
175 if (root_seen) {
176 error |= vss_do_freeze("/", cmd);
177 if (error && operation == VSS_OP_FREEZE)
178 goto err;
179 }
180
181 goto out;
182 err:
183 save_errno = errno;
184 if (ent) {
185 strncpy(errdir, ent->mnt_dir, sizeof(errdir)-1);
186 endmntent(mounts);
187 }
188 vss_operate(VSS_OP_THAW);
189 /* Call syslog after we thaw all filesystems */
190 if (ent)
191 syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s",
192 errdir, save_errno, strerror(save_errno));
193 else
194 syslog(LOG_ERR, "FREEZE of / failed; error:%d %s", save_errno,
195 strerror(save_errno));
196 out:
197 return error;
198 }
199
print_usage(char * argv[])200 void print_usage(char *argv[])
201 {
202 fprintf(stderr, "Usage: %s [options]\n"
203 "Options are:\n"
204 " -n, --no-daemon stay in foreground, don't daemonize\n"
205 " -h, --help print this help\n", argv[0]);
206 }
207
main(int argc,char * argv[])208 int main(int argc, char *argv[])
209 {
210 int vss_fd, len;
211 int error;
212 struct pollfd pfd;
213 int op;
214 struct hv_vss_msg vss_msg[1];
215 int daemonize = 1, long_index = 0, opt;
216 int in_handshake = 1;
217 __u32 kernel_modver;
218
219 static struct option long_options[] = {
220 {"help", no_argument, 0, 'h' },
221 {"no-daemon", no_argument, 0, 'n' },
222 {0, 0, 0, 0 }
223 };
224
225 while ((opt = getopt_long(argc, argv, "hn", long_options,
226 &long_index)) != -1) {
227 switch (opt) {
228 case 'n':
229 daemonize = 0;
230 break;
231 case 'h':
232 print_usage(argv);
233 exit(0);
234 default:
235 print_usage(argv);
236 exit(EXIT_FAILURE);
237 }
238 }
239
240 if (daemonize && daemon(1, 0))
241 return 1;
242
243 openlog("Hyper-V VSS", 0, LOG_USER);
244 syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
245
246 vss_fd = open("/dev/vmbus/hv_vss", O_RDWR);
247 if (vss_fd < 0) {
248 syslog(LOG_ERR, "open /dev/vmbus/hv_vss failed; error: %d %s",
249 errno, strerror(errno));
250 exit(EXIT_FAILURE);
251 }
252 /*
253 * Register ourselves with the kernel.
254 */
255 vss_msg->vss_hdr.operation = VSS_OP_REGISTER1;
256
257 len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
258 if (len < 0) {
259 syslog(LOG_ERR, "registration to kernel failed; error: %d %s",
260 errno, strerror(errno));
261 close(vss_fd);
262 exit(EXIT_FAILURE);
263 }
264
265 pfd.fd = vss_fd;
266
267 while (1) {
268 pfd.events = POLLIN;
269 pfd.revents = 0;
270
271 if (poll(&pfd, 1, -1) < 0) {
272 syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno));
273 if (errno == EINVAL) {
274 close(vss_fd);
275 exit(EXIT_FAILURE);
276 }
277 else
278 continue;
279 }
280
281 len = read(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
282
283 if (in_handshake) {
284 if (len != sizeof(kernel_modver)) {
285 syslog(LOG_ERR, "invalid version negotiation");
286 exit(EXIT_FAILURE);
287 }
288 kernel_modver = *(__u32 *)vss_msg;
289 in_handshake = 0;
290 syslog(LOG_INFO, "VSS: kernel module version: %d",
291 kernel_modver);
292 continue;
293 }
294
295 if (len != sizeof(struct hv_vss_msg)) {
296 syslog(LOG_ERR, "read failed; error:%d %s",
297 errno, strerror(errno));
298 close(vss_fd);
299 return EXIT_FAILURE;
300 }
301
302 op = vss_msg->vss_hdr.operation;
303 error = HV_S_OK;
304
305 switch (op) {
306 case VSS_OP_FREEZE:
307 case VSS_OP_THAW:
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");
312
313 if (error) {
314 error = HV_E_FAIL;
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");
318 }
319 break;
320 case VSS_OP_HOT_BACKUP:
321 syslog(LOG_INFO, "VSS: op=CHECK HOT BACKUP\n");
322 break;
323 default:
324 syslog(LOG_ERR, "Illegal op:%d\n", op);
325 }
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,
330 strerror(errno));
331
332 if (op == VSS_OP_FREEZE)
333 vss_operate(VSS_OP_THAW);
334 }
335 }
336
337 close(vss_fd);
338 exit(0);
339 }
340