Merge tag 'csky-for-linus-5.4-rc1' of git://github.com/c-sky/csky-linux
[linux-2.6-microblaze.git] / tools / hv / hv_vss_daemon.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * An implementation of the host initiated guest snapshot for Hyper-V.
4  *
5  * Copyright (C) 2013, Microsoft, Inc.
6  * Author : K. Y. Srinivasan <kys@microsoft.com>
7  */
8
9
10 #include <sys/types.h>
11 #include <sys/poll.h>
12 #include <sys/ioctl.h>
13 #include <sys/stat.h>
14 #include <sys/sysmacros.h>
15 #include <fcntl.h>
16 #include <stdio.h>
17 #include <mntent.h>
18 #include <stdlib.h>
19 #include <unistd.h>
20 #include <string.h>
21 #include <ctype.h>
22 #include <errno.h>
23 #include <linux/fs.h>
24 #include <linux/major.h>
25 #include <linux/hyperv.h>
26 #include <syslog.h>
27 #include <getopt.h>
28 #include <stdbool.h>
29 #include <dirent.h>
30
31 /* Don't use syslog() in the function since that can cause write to disk */
32 static int vss_do_freeze(char *dir, unsigned int cmd)
33 {
34         int ret, fd = open(dir, O_RDONLY);
35
36         if (fd < 0)
37                 return 1;
38
39         ret = ioctl(fd, cmd, 0);
40
41         /*
42          * If a partition is mounted more than once, only the first
43          * FREEZE/THAW can succeed and the later ones will get
44          * EBUSY/EINVAL respectively: there could be 2 cases:
45          * 1) a user may mount the same partition to different directories
46          *  by mistake or on purpose;
47          * 2) The subvolume of btrfs appears to have the same partition
48          * mounted more than once.
49          */
50         if (ret) {
51                 if ((cmd == FIFREEZE && errno == EBUSY) ||
52                     (cmd == FITHAW && errno == EINVAL)) {
53                         close(fd);
54                         return 0;
55                 }
56         }
57
58         close(fd);
59         return !!ret;
60 }
61
62 static bool is_dev_loop(const char *blkname)
63 {
64         char *buffer;
65         DIR *dir;
66         struct dirent *entry;
67         bool ret = false;
68
69         buffer = malloc(PATH_MAX);
70         if (!buffer) {
71                 syslog(LOG_ERR, "Can't allocate memory!");
72                 exit(1);
73         }
74
75         snprintf(buffer, PATH_MAX, "%s/loop", blkname);
76         if (!access(buffer, R_OK | X_OK)) {
77                 ret = true;
78                 goto free_buffer;
79         } else if (errno != ENOENT) {
80                 syslog(LOG_ERR, "Can't access: %s; error:%d %s!",
81                        buffer, errno, strerror(errno));
82         }
83
84         snprintf(buffer, PATH_MAX, "%s/slaves", blkname);
85         dir = opendir(buffer);
86         if (!dir) {
87                 if (errno != ENOENT)
88                         syslog(LOG_ERR, "Can't opendir: %s; error:%d %s!",
89                                buffer, errno, strerror(errno));
90                 goto free_buffer;
91         }
92
93         while ((entry = readdir(dir)) != NULL) {
94                 if (strcmp(entry->d_name, ".") == 0 ||
95                     strcmp(entry->d_name, "..") == 0)
96                         continue;
97
98                 snprintf(buffer, PATH_MAX, "%s/slaves/%s", blkname,
99                          entry->d_name);
100                 if (is_dev_loop(buffer)) {
101                         ret = true;
102                         break;
103                 }
104         }
105         closedir(dir);
106 free_buffer:
107         free(buffer);
108         return ret;
109 }
110
111 static int vss_operate(int operation)
112 {
113         char match[] = "/dev/";
114         FILE *mounts;
115         struct mntent *ent;
116         struct stat sb;
117         char errdir[1024] = {0};
118         char blkdir[23]; /* /sys/dev/block/XXX:XXX */
119         unsigned int cmd;
120         int error = 0, root_seen = 0, save_errno = 0;
121
122         switch (operation) {
123         case VSS_OP_FREEZE:
124                 cmd = FIFREEZE;
125                 break;
126         case VSS_OP_THAW:
127                 cmd = FITHAW;
128                 break;
129         default:
130                 return -1;
131         }
132
133         mounts = setmntent("/proc/mounts", "r");
134         if (mounts == NULL)
135                 return -1;
136
137         while ((ent = getmntent(mounts))) {
138                 if (strncmp(ent->mnt_fsname, match, strlen(match)))
139                         continue;
140                 if (stat(ent->mnt_fsname, &sb)) {
141                         syslog(LOG_ERR, "Can't stat: %s; error:%d %s!",
142                                ent->mnt_fsname, errno, strerror(errno));
143                 } else {
144                         sprintf(blkdir, "/sys/dev/block/%d:%d",
145                                 major(sb.st_rdev), minor(sb.st_rdev));
146                         if (is_dev_loop(blkdir))
147                                 continue;
148                 }
149                 if (hasmntopt(ent, MNTOPT_RO) != NULL)
150                         continue;
151                 if (strcmp(ent->mnt_type, "vfat") == 0)
152                         continue;
153                 if (strcmp(ent->mnt_dir, "/") == 0) {
154                         root_seen = 1;
155                         continue;
156                 }
157                 error |= vss_do_freeze(ent->mnt_dir, cmd);
158                 if (error && operation == VSS_OP_FREEZE)
159                         goto err;
160         }
161
162         endmntent(mounts);
163
164         if (root_seen) {
165                 error |= vss_do_freeze("/", cmd);
166                 if (error && operation == VSS_OP_FREEZE)
167                         goto err;
168         }
169
170         goto out;
171 err:
172         save_errno = errno;
173         if (ent) {
174                 strncpy(errdir, ent->mnt_dir, sizeof(errdir)-1);
175                 endmntent(mounts);
176         }
177         vss_operate(VSS_OP_THAW);
178         /* Call syslog after we thaw all filesystems */
179         if (ent)
180                 syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s",
181                        errdir, save_errno, strerror(save_errno));
182         else
183                 syslog(LOG_ERR, "FREEZE of / failed; error:%d %s", save_errno,
184                        strerror(save_errno));
185 out:
186         return error;
187 }
188
189 void print_usage(char *argv[])
190 {
191         fprintf(stderr, "Usage: %s [options]\n"
192                 "Options are:\n"
193                 "  -n, --no-daemon        stay in foreground, don't daemonize\n"
194                 "  -h, --help             print this help\n", argv[0]);
195 }
196
197 int main(int argc, char *argv[])
198 {
199         int vss_fd, len;
200         int error;
201         struct pollfd pfd;
202         int     op;
203         struct hv_vss_msg vss_msg[1];
204         int daemonize = 1, long_index = 0, opt;
205         int in_handshake = 1;
206         __u32 kernel_modver;
207
208         static struct option long_options[] = {
209                 {"help",        no_argument,       0,  'h' },
210                 {"no-daemon",   no_argument,       0,  'n' },
211                 {0,             0,                 0,  0   }
212         };
213
214         while ((opt = getopt_long(argc, argv, "hn", long_options,
215                                   &long_index)) != -1) {
216                 switch (opt) {
217                 case 'n':
218                         daemonize = 0;
219                         break;
220                 case 'h':
221                         print_usage(argv);
222                         exit(0);
223                 default:
224                         print_usage(argv);
225                         exit(EXIT_FAILURE);
226                 }
227         }
228
229         if (daemonize && daemon(1, 0))
230                 return 1;
231
232         openlog("Hyper-V VSS", 0, LOG_USER);
233         syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
234
235         vss_fd = open("/dev/vmbus/hv_vss", O_RDWR);
236         if (vss_fd < 0) {
237                 syslog(LOG_ERR, "open /dev/vmbus/hv_vss failed; error: %d %s",
238                        errno, strerror(errno));
239                 exit(EXIT_FAILURE);
240         }
241         /*
242          * Register ourselves with the kernel.
243          */
244         vss_msg->vss_hdr.operation = VSS_OP_REGISTER1;
245
246         len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
247         if (len < 0) {
248                 syslog(LOG_ERR, "registration to kernel failed; error: %d %s",
249                        errno, strerror(errno));
250                 close(vss_fd);
251                 exit(EXIT_FAILURE);
252         }
253
254         pfd.fd = vss_fd;
255
256         while (1) {
257                 pfd.events = POLLIN;
258                 pfd.revents = 0;
259
260                 if (poll(&pfd, 1, -1) < 0) {
261                         syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno));
262                         if (errno == EINVAL) {
263                                 close(vss_fd);
264                                 exit(EXIT_FAILURE);
265                         }
266                         else
267                                 continue;
268                 }
269
270                 len = read(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
271
272                 if (in_handshake) {
273                         if (len != sizeof(kernel_modver)) {
274                                 syslog(LOG_ERR, "invalid version negotiation");
275                                 exit(EXIT_FAILURE);
276                         }
277                         kernel_modver = *(__u32 *)vss_msg;
278                         in_handshake = 0;
279                         syslog(LOG_INFO, "VSS: kernel module version: %d",
280                                kernel_modver);
281                         continue;
282                 }
283
284                 if (len != sizeof(struct hv_vss_msg)) {
285                         syslog(LOG_ERR, "read failed; error:%d %s",
286                                errno, strerror(errno));
287                         close(vss_fd);
288                         return EXIT_FAILURE;
289                 }
290
291                 op = vss_msg->vss_hdr.operation;
292                 error =  HV_S_OK;
293
294                 switch (op) {
295                 case VSS_OP_FREEZE:
296                 case VSS_OP_THAW:
297                         error = vss_operate(op);
298                         syslog(LOG_INFO, "VSS: op=%s: %s\n",
299                                 op == VSS_OP_FREEZE ? "FREEZE" : "THAW",
300                                 error ? "failed" : "succeeded");
301
302                         if (error) {
303                                 error = HV_E_FAIL;
304                                 syslog(LOG_ERR, "op=%d failed!", op);
305                                 syslog(LOG_ERR, "report it with these files:");
306                                 syslog(LOG_ERR, "/etc/fstab and /proc/mounts");
307                         }
308                         break;
309                 case VSS_OP_HOT_BACKUP:
310                         syslog(LOG_INFO, "VSS: op=CHECK HOT BACKUP\n");
311                         break;
312                 default:
313                         syslog(LOG_ERR, "Illegal op:%d\n", op);
314                 }
315                 vss_msg->error = error;
316                 len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
317                 if (len != sizeof(struct hv_vss_msg)) {
318                         syslog(LOG_ERR, "write failed; error: %d %s", errno,
319                                strerror(errno));
320
321                         if (op == VSS_OP_FREEZE)
322                                 vss_operate(VSS_OP_THAW);
323                 }
324         }
325
326         close(vss_fd);
327         exit(0);
328 }