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 */ 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 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 } 121 122 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 } 199 200 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 } 207 208 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 default: 233 print_usage(argv); 234 exit(EXIT_FAILURE); 235 } 236 } 237 238 if (daemonize && daemon(1, 0)) 239 return 1; 240 241 openlog("Hyper-V VSS", 0, LOG_USER); 242 syslog(LOG_INFO, "VSS starting; pid is:%d", getpid()); 243 244 vss_fd = open("/dev/vmbus/hv_vss", O_RDWR); 245 if (vss_fd < 0) { 246 syslog(LOG_ERR, "open /dev/vmbus/hv_vss failed; error: %d %s", 247 errno, strerror(errno)); 248 exit(EXIT_FAILURE); 249 } 250 /* 251 * Register ourselves with the kernel. 252 */ 253 vss_msg->vss_hdr.operation = VSS_OP_REGISTER1; 254 255 len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg)); 256 if (len < 0) { 257 syslog(LOG_ERR, "registration to kernel failed; error: %d %s", 258 errno, strerror(errno)); 259 close(vss_fd); 260 exit(EXIT_FAILURE); 261 } 262 263 pfd.fd = vss_fd; 264 265 while (1) { 266 pfd.events = POLLIN; 267 pfd.revents = 0; 268 269 if (poll(&pfd, 1, -1) < 0) { 270 syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno)); 271 if (errno == EINVAL) { 272 close(vss_fd); 273 exit(EXIT_FAILURE); 274 } 275 else 276 continue; 277 } 278 279 len = read(vss_fd, vss_msg, sizeof(struct hv_vss_msg)); 280 281 if (in_handshake) { 282 if (len != sizeof(kernel_modver)) { 283 syslog(LOG_ERR, "invalid version negotiation"); 284 exit(EXIT_FAILURE); 285 } 286 kernel_modver = *(__u32 *)vss_msg; 287 in_handshake = 0; 288 syslog(LOG_INFO, "VSS: kernel module version: %d", 289 kernel_modver); 290 continue; 291 } 292 293 if (len != sizeof(struct hv_vss_msg)) { 294 syslog(LOG_ERR, "read failed; error:%d %s", 295 errno, strerror(errno)); 296 close(vss_fd); 297 return EXIT_FAILURE; 298 } 299 300 op = vss_msg->vss_hdr.operation; 301 error = HV_S_OK; 302 303 switch (op) { 304 case VSS_OP_FREEZE: 305 case VSS_OP_THAW: 306 error = vss_operate(op); 307 syslog(LOG_INFO, "VSS: op=%s: %s\n", 308 op == VSS_OP_FREEZE ? "FREEZE" : "THAW", 309 error ? "failed" : "succeeded"); 310 311 if (error) { 312 error = HV_E_FAIL; 313 syslog(LOG_ERR, "op=%d failed!", op); 314 syslog(LOG_ERR, "report it with these files:"); 315 syslog(LOG_ERR, "/etc/fstab and /proc/mounts"); 316 } 317 break; 318 case VSS_OP_HOT_BACKUP: 319 syslog(LOG_INFO, "VSS: op=CHECK HOT BACKUP\n"); 320 break; 321 default: 322 syslog(LOG_ERR, "Illegal op:%d\n", op); 323 } 324 vss_msg->error = error; 325 len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg)); 326 if (len != sizeof(struct hv_vss_msg)) { 327 syslog(LOG_ERR, "write failed; error: %d %s", errno, 328 strerror(errno)); 329 330 if (op == VSS_OP_FREEZE) 331 vss_operate(VSS_OP_THAW); 332 } 333 } 334 335 close(vss_fd); 336 exit(0); 337 } 338