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 <fcntl.h> 26 #include <stdio.h> 27 #include <mntent.h> 28 #include <stdlib.h> 29 #include <unistd.h> 30 #include <string.h> 31 #include <ctype.h> 32 #include <errno.h> 33 #include <linux/fs.h> 34 #include <linux/major.h> 35 #include <linux/hyperv.h> 36 #include <syslog.h> 37 #include <getopt.h> 38 39 /* Don't use syslog() in the function since that can cause write to disk */ 40 static int vss_do_freeze(char *dir, unsigned int cmd) 41 { 42 int ret, fd = open(dir, O_RDONLY); 43 44 if (fd < 0) 45 return 1; 46 47 ret = ioctl(fd, cmd, 0); 48 49 /* 50 * If a partition is mounted more than once, only the first 51 * FREEZE/THAW can succeed and the later ones will get 52 * EBUSY/EINVAL respectively: there could be 2 cases: 53 * 1) a user may mount the same partition to differnt directories 54 * by mistake or on purpose; 55 * 2) The subvolume of btrfs appears to have the same partition 56 * mounted more than once. 57 */ 58 if (ret) { 59 if ((cmd == FIFREEZE && errno == EBUSY) || 60 (cmd == FITHAW && errno == EINVAL)) { 61 close(fd); 62 return 0; 63 } 64 } 65 66 close(fd); 67 return !!ret; 68 } 69 70 static int vss_operate(int operation) 71 { 72 char match[] = "/dev/"; 73 FILE *mounts; 74 struct mntent *ent; 75 struct stat sb; 76 char errdir[1024] = {0}; 77 unsigned int cmd; 78 int error = 0, root_seen = 0, save_errno = 0; 79 80 switch (operation) { 81 case VSS_OP_FREEZE: 82 cmd = FIFREEZE; 83 break; 84 case VSS_OP_THAW: 85 cmd = FITHAW; 86 break; 87 default: 88 return -1; 89 } 90 91 mounts = setmntent("/proc/mounts", "r"); 92 if (mounts == NULL) 93 return -1; 94 95 while ((ent = getmntent(mounts))) { 96 if (strncmp(ent->mnt_fsname, match, strlen(match))) 97 continue; 98 if (stat(ent->mnt_fsname, &sb) == -1) 99 continue; 100 if (S_ISBLK(sb.st_mode) && major(sb.st_rdev) == LOOP_MAJOR) 101 continue; 102 if (hasmntopt(ent, MNTOPT_RO) != NULL) 103 continue; 104 if (strcmp(ent->mnt_type, "vfat") == 0) 105 continue; 106 if (strcmp(ent->mnt_dir, "/") == 0) { 107 root_seen = 1; 108 continue; 109 } 110 error |= vss_do_freeze(ent->mnt_dir, cmd); 111 if (error && operation == VSS_OP_FREEZE) 112 goto err; 113 } 114 115 endmntent(mounts); 116 117 if (root_seen) { 118 error |= vss_do_freeze("/", cmd); 119 if (error && operation == VSS_OP_FREEZE) 120 goto err; 121 } 122 123 goto out; 124 err: 125 save_errno = errno; 126 if (ent) { 127 strncpy(errdir, ent->mnt_dir, sizeof(errdir)-1); 128 endmntent(mounts); 129 } 130 vss_operate(VSS_OP_THAW); 131 /* Call syslog after we thaw all filesystems */ 132 if (ent) 133 syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s", 134 errdir, save_errno, strerror(save_errno)); 135 else 136 syslog(LOG_ERR, "FREEZE of / failed; error:%d %s", save_errno, 137 strerror(save_errno)); 138 out: 139 return error; 140 } 141 142 void print_usage(char *argv[]) 143 { 144 fprintf(stderr, "Usage: %s [options]\n" 145 "Options are:\n" 146 " -n, --no-daemon stay in foreground, don't daemonize\n" 147 " -h, --help print this help\n", argv[0]); 148 } 149 150 int main(int argc, char *argv[]) 151 { 152 int vss_fd, len; 153 int error; 154 struct pollfd pfd; 155 int op; 156 struct hv_vss_msg vss_msg[1]; 157 int daemonize = 1, long_index = 0, opt; 158 int in_handshake = 1; 159 __u32 kernel_modver; 160 161 static struct option long_options[] = { 162 {"help", no_argument, 0, 'h' }, 163 {"no-daemon", no_argument, 0, 'n' }, 164 {0, 0, 0, 0 } 165 }; 166 167 while ((opt = getopt_long(argc, argv, "hn", long_options, 168 &long_index)) != -1) { 169 switch (opt) { 170 case 'n': 171 daemonize = 0; 172 break; 173 case 'h': 174 default: 175 print_usage(argv); 176 exit(EXIT_FAILURE); 177 } 178 } 179 180 if (daemonize && daemon(1, 0)) 181 return 1; 182 183 openlog("Hyper-V VSS", 0, LOG_USER); 184 syslog(LOG_INFO, "VSS starting; pid is:%d", getpid()); 185 186 vss_fd = open("/dev/vmbus/hv_vss", O_RDWR); 187 if (vss_fd < 0) { 188 syslog(LOG_ERR, "open /dev/vmbus/hv_vss failed; error: %d %s", 189 errno, strerror(errno)); 190 exit(EXIT_FAILURE); 191 } 192 /* 193 * Register ourselves with the kernel. 194 */ 195 vss_msg->vss_hdr.operation = VSS_OP_REGISTER1; 196 197 len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg)); 198 if (len < 0) { 199 syslog(LOG_ERR, "registration to kernel failed; error: %d %s", 200 errno, strerror(errno)); 201 close(vss_fd); 202 exit(EXIT_FAILURE); 203 } 204 205 pfd.fd = vss_fd; 206 207 while (1) { 208 pfd.events = POLLIN; 209 pfd.revents = 0; 210 211 if (poll(&pfd, 1, -1) < 0) { 212 syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno)); 213 if (errno == EINVAL) { 214 close(vss_fd); 215 exit(EXIT_FAILURE); 216 } 217 else 218 continue; 219 } 220 221 len = read(vss_fd, vss_msg, sizeof(struct hv_vss_msg)); 222 223 if (in_handshake) { 224 if (len != sizeof(kernel_modver)) { 225 syslog(LOG_ERR, "invalid version negotiation"); 226 exit(EXIT_FAILURE); 227 } 228 kernel_modver = *(__u32 *)vss_msg; 229 in_handshake = 0; 230 syslog(LOG_INFO, "VSS: kernel module version: %d", 231 kernel_modver); 232 continue; 233 } 234 235 if (len != sizeof(struct hv_vss_msg)) { 236 syslog(LOG_ERR, "read failed; error:%d %s", 237 errno, strerror(errno)); 238 close(vss_fd); 239 return EXIT_FAILURE; 240 } 241 242 op = vss_msg->vss_hdr.operation; 243 error = HV_S_OK; 244 245 switch (op) { 246 case VSS_OP_FREEZE: 247 case VSS_OP_THAW: 248 error = vss_operate(op); 249 syslog(LOG_INFO, "VSS: op=%s: %s\n", 250 op == VSS_OP_FREEZE ? "FREEZE" : "THAW", 251 error ? "failed" : "succeeded"); 252 253 if (error) { 254 error = HV_E_FAIL; 255 syslog(LOG_ERR, "op=%d failed!", op); 256 syslog(LOG_ERR, "report it with these files:"); 257 syslog(LOG_ERR, "/etc/fstab and /proc/mounts"); 258 } 259 break; 260 case VSS_OP_HOT_BACKUP: 261 syslog(LOG_INFO, "VSS: op=CHECK HOT BACKUP\n"); 262 break; 263 default: 264 syslog(LOG_ERR, "Illegal op:%d\n", op); 265 } 266 vss_msg->error = error; 267 len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg)); 268 if (len != sizeof(struct hv_vss_msg)) { 269 syslog(LOG_ERR, "write failed; error: %d %s", errno, 270 strerror(errno)); 271 272 if (op == VSS_OP_FREEZE) 273 vss_operate(VSS_OP_THAW); 274 } 275 } 276 277 close(vss_fd); 278 exit(0); 279 } 280