| 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 <fcntl.h> |
| 25 | #include <stdio.h> |
| 26 | #include <mntent.h> |
| 27 | #include <stdlib.h> |
| 28 | #include <unistd.h> |
| 29 | #include <string.h> |
| 30 | #include <ctype.h> |
| 31 | #include <errno.h> |
| 32 | #include <linux/fs.h> |
| 33 | #include <linux/hyperv.h> |
| 34 | #include <syslog.h> |
| 35 | #include <getopt.h> |
| 36 | |
| 37 | /* Don't use syslog() in the function since that can cause write to disk */ |
| 38 | static int vss_do_freeze(char *dir, unsigned int cmd) |
| 39 | { |
| 40 | int ret, fd = open(dir, O_RDONLY); |
| 41 | |
| 42 | if (fd < 0) |
| 43 | return 1; |
| 44 | |
| 45 | ret = ioctl(fd, cmd, 0); |
| 46 | |
| 47 | /* |
| 48 | * If a partition is mounted more than once, only the first |
| 49 | * FREEZE/THAW can succeed and the later ones will get |
| 50 | * EBUSY/EINVAL respectively: there could be 2 cases: |
| 51 | * 1) a user may mount the same partition to differnt directories |
| 52 | * by mistake or on purpose; |
| 53 | * 2) The subvolume of btrfs appears to have the same partition |
| 54 | * mounted more than once. |
| 55 | */ |
| 56 | if (ret) { |
| 57 | if ((cmd == FIFREEZE && errno == EBUSY) || |
| 58 | (cmd == FITHAW && errno == EINVAL)) { |
| 59 | close(fd); |
| 60 | return 0; |
| 61 | } |
| 62 | } |
| 63 | |
| 64 | close(fd); |
| 65 | return !!ret; |
| 66 | } |
| 67 | |
| 68 | static int vss_operate(int operation) |
| 69 | { |
| 70 | char match[] = "/dev/"; |
| 71 | FILE *mounts; |
| 72 | struct mntent *ent; |
| 73 | char errdir[1024] = {0}; |
| 74 | unsigned int cmd; |
| 75 | int error = 0, root_seen = 0, save_errno = 0; |
| 76 | |
| 77 | switch (operation) { |
| 78 | case VSS_OP_FREEZE: |
| 79 | cmd = FIFREEZE; |
| 80 | break; |
| 81 | case VSS_OP_THAW: |
| 82 | cmd = FITHAW; |
| 83 | break; |
| 84 | default: |
| 85 | return -1; |
| 86 | } |
| 87 | |
| 88 | mounts = setmntent("/proc/mounts", "r"); |
| 89 | if (mounts == NULL) |
| 90 | return -1; |
| 91 | |
| 92 | while ((ent = getmntent(mounts))) { |
| 93 | if (strncmp(ent->mnt_fsname, match, strlen(match))) |
| 94 | continue; |
| 95 | if (hasmntopt(ent, MNTOPT_RO) != NULL) |
| 96 | continue; |
| 97 | if (strcmp(ent->mnt_type, "vfat") == 0) |
| 98 | continue; |
| 99 | if (strcmp(ent->mnt_dir, "/") == 0) { |
| 100 | root_seen = 1; |
| 101 | continue; |
| 102 | } |
| 103 | error |= vss_do_freeze(ent->mnt_dir, cmd); |
| 104 | if (error && operation == VSS_OP_FREEZE) |
| 105 | goto err; |
| 106 | } |
| 107 | |
| 108 | endmntent(mounts); |
| 109 | |
| 110 | if (root_seen) { |
| 111 | error |= vss_do_freeze("/", cmd); |
| 112 | if (error && operation == VSS_OP_FREEZE) |
| 113 | goto err; |
| 114 | } |
| 115 | |
| 116 | goto out; |
| 117 | err: |
| 118 | save_errno = errno; |
| 119 | if (ent) { |
| 120 | strncpy(errdir, ent->mnt_dir, sizeof(errdir)-1); |
| 121 | endmntent(mounts); |
| 122 | } |
| 123 | vss_operate(VSS_OP_THAW); |
| 124 | /* Call syslog after we thaw all filesystems */ |
| 125 | if (ent) |
| 126 | syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s", |
| 127 | errdir, save_errno, strerror(save_errno)); |
| 128 | else |
| 129 | syslog(LOG_ERR, "FREEZE of / failed; error:%d %s", save_errno, |
| 130 | strerror(save_errno)); |
| 131 | out: |
| 132 | return error; |
| 133 | } |
| 134 | |
| 135 | void print_usage(char *argv[]) |
| 136 | { |
| 137 | fprintf(stderr, "Usage: %s [options]\n" |
| 138 | "Options are:\n" |
| 139 | " -n, --no-daemon stay in foreground, don't daemonize\n" |
| 140 | " -h, --help print this help\n", argv[0]); |
| 141 | } |
| 142 | |
| 143 | int main(int argc, char *argv[]) |
| 144 | { |
| 145 | int vss_fd, len; |
| 146 | int error; |
| 147 | struct pollfd pfd; |
| 148 | int op; |
| 149 | struct hv_vss_msg vss_msg[1]; |
| 150 | int daemonize = 1, long_index = 0, opt; |
| 151 | int in_handshake = 1; |
| 152 | __u32 kernel_modver; |
| 153 | |
| 154 | static struct option long_options[] = { |
| 155 | {"help", no_argument, 0, 'h' }, |
| 156 | {"no-daemon", no_argument, 0, 'n' }, |
| 157 | {0, 0, 0, 0 } |
| 158 | }; |
| 159 | |
| 160 | while ((opt = getopt_long(argc, argv, "hn", long_options, |
| 161 | &long_index)) != -1) { |
| 162 | switch (opt) { |
| 163 | case 'n': |
| 164 | daemonize = 0; |
| 165 | break; |
| 166 | case 'h': |
| 167 | default: |
| 168 | print_usage(argv); |
| 169 | exit(EXIT_FAILURE); |
| 170 | } |
| 171 | } |
| 172 | |
| 173 | if (daemonize && daemon(1, 0)) |
| 174 | return 1; |
| 175 | |
| 176 | openlog("Hyper-V VSS", 0, LOG_USER); |
| 177 | syslog(LOG_INFO, "VSS starting; pid is:%d", getpid()); |
| 178 | |
| 179 | vss_fd = open("/dev/vmbus/hv_vss", O_RDWR); |
| 180 | if (vss_fd < 0) { |
| 181 | syslog(LOG_ERR, "open /dev/vmbus/hv_vss failed; error: %d %s", |
| 182 | errno, strerror(errno)); |
| 183 | exit(EXIT_FAILURE); |
| 184 | } |
| 185 | /* |
| 186 | * Register ourselves with the kernel. |
| 187 | */ |
| 188 | vss_msg->vss_hdr.operation = VSS_OP_REGISTER1; |
| 189 | |
| 190 | len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg)); |
| 191 | if (len < 0) { |
| 192 | syslog(LOG_ERR, "registration to kernel failed; error: %d %s", |
| 193 | errno, strerror(errno)); |
| 194 | close(vss_fd); |
| 195 | exit(EXIT_FAILURE); |
| 196 | } |
| 197 | |
| 198 | pfd.fd = vss_fd; |
| 199 | |
| 200 | while (1) { |
| 201 | pfd.events = POLLIN; |
| 202 | pfd.revents = 0; |
| 203 | |
| 204 | if (poll(&pfd, 1, -1) < 0) { |
| 205 | syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno)); |
| 206 | if (errno == EINVAL) { |
| 207 | close(vss_fd); |
| 208 | exit(EXIT_FAILURE); |
| 209 | } |
| 210 | else |
| 211 | continue; |
| 212 | } |
| 213 | |
| 214 | len = read(vss_fd, vss_msg, sizeof(struct hv_vss_msg)); |
| 215 | |
| 216 | if (in_handshake) { |
| 217 | if (len != sizeof(kernel_modver)) { |
| 218 | syslog(LOG_ERR, "invalid version negotiation"); |
| 219 | exit(EXIT_FAILURE); |
| 220 | } |
| 221 | kernel_modver = *(__u32 *)vss_msg; |
| 222 | in_handshake = 0; |
| 223 | syslog(LOG_INFO, "VSS: kernel module version: %d", |
| 224 | kernel_modver); |
| 225 | continue; |
| 226 | } |
| 227 | |
| 228 | if (len != sizeof(struct hv_vss_msg)) { |
| 229 | syslog(LOG_ERR, "read failed; error:%d %s", |
| 230 | errno, strerror(errno)); |
| 231 | close(vss_fd); |
| 232 | return EXIT_FAILURE; |
| 233 | } |
| 234 | |
| 235 | op = vss_msg->vss_hdr.operation; |
| 236 | error = HV_S_OK; |
| 237 | |
| 238 | switch (op) { |
| 239 | case VSS_OP_FREEZE: |
| 240 | case VSS_OP_THAW: |
| 241 | error = vss_operate(op); |
| 242 | syslog(LOG_INFO, "VSS: op=%s: %s\n", |
| 243 | op == VSS_OP_FREEZE ? "FREEZE" : "THAW", |
| 244 | error ? "failed" : "succeeded"); |
| 245 | |
| 246 | if (error) { |
| 247 | error = HV_E_FAIL; |
| 248 | syslog(LOG_ERR, "op=%d failed!", op); |
| 249 | syslog(LOG_ERR, "report it with these files:"); |
| 250 | syslog(LOG_ERR, "/etc/fstab and /proc/mounts"); |
| 251 | } |
| 252 | break; |
| 253 | default: |
| 254 | syslog(LOG_ERR, "Illegal op:%d\n", op); |
| 255 | } |
| 256 | vss_msg->error = error; |
| 257 | len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg)); |
| 258 | if (len != sizeof(struct hv_vss_msg)) { |
| 259 | syslog(LOG_ERR, "write failed; error: %d %s", errno, |
| 260 | strerror(errno)); |
| 261 | exit(EXIT_FAILURE); |
| 262 | } |
| 263 | } |
| 264 | |
| 265 | close(vss_fd); |
| 266 | exit(0); |
| 267 | } |