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
40 /* Don't use syslog() in the function since that can cause write to disk */
vss_do_freeze(char * dir,unsigned int cmd)41 static int vss_do_freeze(char *dir, unsigned int cmd)
42 {
43 int ret, fd = open(dir, O_RDONLY);
44
45 if (fd < 0)
46 return 1;
47
48 ret = ioctl(fd, cmd, 0);
49
50 /*
51 * If a partition is mounted more than once, only the first
52 * FREEZE/THAW can succeed and the later ones will get
53 * EBUSY/EINVAL respectively: there could be 2 cases:
54 * 1) a user may mount the same partition to differnt directories
55 * by mistake or on purpose;
56 * 2) The subvolume of btrfs appears to have the same partition
57 * mounted more than once.
58 */
59 if (ret) {
60 if ((cmd == FIFREEZE && errno == EBUSY) ||
61 (cmd == FITHAW && errno == EINVAL)) {
62 close(fd);
63 return 0;
64 }
65 }
66
67 close(fd);
68 return !!ret;
69 }
70
vss_operate(int operation)71 static int vss_operate(int operation)
72 {
73 char match[] = "/dev/";
74 FILE *mounts;
75 struct mntent *ent;
76 struct stat sb;
77 char errdir[1024] = {0};
78 unsigned int cmd;
79 int error = 0, root_seen = 0, save_errno = 0;
80
81 switch (operation) {
82 case VSS_OP_FREEZE:
83 cmd = FIFREEZE;
84 break;
85 case VSS_OP_THAW:
86 cmd = FITHAW;
87 break;
88 default:
89 return -1;
90 }
91
92 mounts = setmntent("/proc/mounts", "r");
93 if (mounts == NULL)
94 return -1;
95
96 while ((ent = getmntent(mounts))) {
97 if (strncmp(ent->mnt_fsname, match, strlen(match)))
98 continue;
99 if (stat(ent->mnt_fsname, &sb) == -1)
100 continue;
101 if (S_ISBLK(sb.st_mode) && major(sb.st_rdev) == LOOP_MAJOR)
102 continue;
103 if (hasmntopt(ent, MNTOPT_RO) != NULL)
104 continue;
105 if (strcmp(ent->mnt_type, "vfat") == 0)
106 continue;
107 if (strcmp(ent->mnt_dir, "/") == 0) {
108 root_seen = 1;
109 continue;
110 }
111 error |= vss_do_freeze(ent->mnt_dir, cmd);
112 if (error && operation == VSS_OP_FREEZE)
113 goto err;
114 }
115
116 endmntent(mounts);
117
118 if (root_seen) {
119 error |= vss_do_freeze("/", cmd);
120 if (error && operation == VSS_OP_FREEZE)
121 goto err;
122 }
123
124 goto out;
125 err:
126 save_errno = errno;
127 if (ent) {
128 strncpy(errdir, ent->mnt_dir, sizeof(errdir)-1);
129 endmntent(mounts);
130 }
131 vss_operate(VSS_OP_THAW);
132 /* Call syslog after we thaw all filesystems */
133 if (ent)
134 syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s",
135 errdir, save_errno, strerror(save_errno));
136 else
137 syslog(LOG_ERR, "FREEZE of / failed; error:%d %s", save_errno,
138 strerror(save_errno));
139 out:
140 return error;
141 }
142
print_usage(char * argv[])143 void print_usage(char *argv[])
144 {
145 fprintf(stderr, "Usage: %s [options]\n"
146 "Options are:\n"
147 " -n, --no-daemon stay in foreground, don't daemonize\n"
148 " -h, --help print this help\n", argv[0]);
149 }
150
main(int argc,char * argv[])151 int main(int argc, char *argv[])
152 {
153 int vss_fd, len;
154 int error;
155 struct pollfd pfd;
156 int op;
157 struct hv_vss_msg vss_msg[1];
158 int daemonize = 1, long_index = 0, opt;
159 int in_handshake = 1;
160 __u32 kernel_modver;
161
162 static struct option long_options[] = {
163 {"help", no_argument, 0, 'h' },
164 {"no-daemon", no_argument, 0, 'n' },
165 {0, 0, 0, 0 }
166 };
167
168 while ((opt = getopt_long(argc, argv, "hn", long_options,
169 &long_index)) != -1) {
170 switch (opt) {
171 case 'n':
172 daemonize = 0;
173 break;
174 case 'h':
175 print_usage(argv);
176 exit(0);
177 default:
178 print_usage(argv);
179 exit(EXIT_FAILURE);
180 }
181 }
182
183 if (daemonize && daemon(1, 0))
184 return 1;
185
186 openlog("Hyper-V VSS", 0, LOG_USER);
187 syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
188
189 vss_fd = open("/dev/vmbus/hv_vss", O_RDWR);
190 if (vss_fd < 0) {
191 syslog(LOG_ERR, "open /dev/vmbus/hv_vss failed; error: %d %s",
192 errno, strerror(errno));
193 exit(EXIT_FAILURE);
194 }
195 /*
196 * Register ourselves with the kernel.
197 */
198 vss_msg->vss_hdr.operation = VSS_OP_REGISTER1;
199
200 len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
201 if (len < 0) {
202 syslog(LOG_ERR, "registration to kernel failed; error: %d %s",
203 errno, strerror(errno));
204 close(vss_fd);
205 exit(EXIT_FAILURE);
206 }
207
208 pfd.fd = vss_fd;
209
210 while (1) {
211 pfd.events = POLLIN;
212 pfd.revents = 0;
213
214 if (poll(&pfd, 1, -1) < 0) {
215 syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno));
216 if (errno == EINVAL) {
217 close(vss_fd);
218 exit(EXIT_FAILURE);
219 }
220 else
221 continue;
222 }
223
224 len = read(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
225
226 if (in_handshake) {
227 if (len != sizeof(kernel_modver)) {
228 syslog(LOG_ERR, "invalid version negotiation");
229 exit(EXIT_FAILURE);
230 }
231 kernel_modver = *(__u32 *)vss_msg;
232 in_handshake = 0;
233 syslog(LOG_INFO, "VSS: kernel module version: %d",
234 kernel_modver);
235 continue;
236 }
237
238 if (len != sizeof(struct hv_vss_msg)) {
239 syslog(LOG_ERR, "read failed; error:%d %s",
240 errno, strerror(errno));
241 close(vss_fd);
242 return EXIT_FAILURE;
243 }
244
245 op = vss_msg->vss_hdr.operation;
246 error = HV_S_OK;
247
248 switch (op) {
249 case VSS_OP_FREEZE:
250 case VSS_OP_THAW:
251 error = vss_operate(op);
252 syslog(LOG_INFO, "VSS: op=%s: %s\n",
253 op == VSS_OP_FREEZE ? "FREEZE" : "THAW",
254 error ? "failed" : "succeeded");
255
256 if (error) {
257 error = HV_E_FAIL;
258 syslog(LOG_ERR, "op=%d failed!", op);
259 syslog(LOG_ERR, "report it with these files:");
260 syslog(LOG_ERR, "/etc/fstab and /proc/mounts");
261 }
262 break;
263 case VSS_OP_HOT_BACKUP:
264 syslog(LOG_INFO, "VSS: op=CHECK HOT BACKUP\n");
265 break;
266 default:
267 syslog(LOG_ERR, "Illegal op:%d\n", op);
268 }
269 vss_msg->error = error;
270 len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
271 if (len != sizeof(struct hv_vss_msg)) {
272 syslog(LOG_ERR, "write failed; error: %d %s", errno,
273 strerror(errno));
274
275 if (op == VSS_OP_FREEZE)
276 vss_operate(VSS_OP_THAW);
277 }
278 }
279
280 close(vss_fd);
281 exit(0);
282 }
283