2 * An implementation of the host initiated guest snapshot for Hyper-V.
5 * Copyright (C) 2013, Microsoft, Inc.
6 * Author : K. Y. Srinivasan <kys@microsoft.com>
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.
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
21 #include <sys/types.h>
23 #include <sys/ioctl.h>
33 #include <linux/hyperv.h>
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
)
40 int ret
, fd
= open(dir
, O_RDONLY
);
45 ret
= ioctl(fd
, cmd
, 0);
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.
57 if ((cmd
== FIFREEZE
&& errno
== EBUSY
) ||
58 (cmd
== FITHAW
&& errno
== EINVAL
)) {
68 static int vss_operate(int operation
)
70 char match
[] = "/dev/";
73 char errdir
[1024] = {0};
75 int error
= 0, root_seen
= 0, save_errno
= 0;
88 mounts
= setmntent("/proc/mounts", "r");
92 while ((ent
= getmntent(mounts
))) {
93 if (strncmp(ent
->mnt_fsname
, match
, strlen(match
)))
95 if (hasmntopt(ent
, MNTOPT_RO
) != NULL
)
97 if (strcmp(ent
->mnt_type
, "vfat") == 0)
99 if (strcmp(ent
->mnt_dir
, "/") == 0) {
103 error
|= vss_do_freeze(ent
->mnt_dir
, cmd
);
104 if (error
&& operation
== VSS_OP_FREEZE
)
111 error
|= vss_do_freeze("/", cmd
);
112 if (error
&& operation
== VSS_OP_FREEZE
)
120 strncpy(errdir
, ent
->mnt_dir
, sizeof(errdir
)-1);
123 vss_operate(VSS_OP_THAW
);
124 /* Call syslog after we thaw all filesystems */
126 syslog(LOG_ERR
, "FREEZE of %s failed; error:%d %s",
127 errdir
, save_errno
, strerror(save_errno
));
129 syslog(LOG_ERR
, "FREEZE of / failed; error:%d %s", save_errno
,
130 strerror(save_errno
));
135 void print_usage(char *argv
[])
137 fprintf(stderr
, "Usage: %s [options]\n"
139 " -n, --no-daemon stay in foreground, don't daemonize\n"
140 " -h, --help print this help\n", argv
[0]);
143 int main(int argc
, char *argv
[])
149 struct hv_vss_msg vss_msg
[1];
150 int daemonize
= 1, long_index
= 0, opt
;
151 int in_handshake
= 1;
154 static struct option long_options
[] = {
155 {"help", no_argument
, 0, 'h' },
156 {"no-daemon", no_argument
, 0, 'n' },
160 while ((opt
= getopt_long(argc
, argv
, "hn", long_options
,
161 &long_index
)) != -1) {
175 if (daemonize
&& daemon(1, 0))
178 openlog("Hyper-V VSS", 0, LOG_USER
);
179 syslog(LOG_INFO
, "VSS starting; pid is:%d", getpid());
181 vss_fd
= open("/dev/vmbus/hv_vss", O_RDWR
);
183 syslog(LOG_ERR
, "open /dev/vmbus/hv_vss failed; error: %d %s",
184 errno
, strerror(errno
));
188 * Register ourselves with the kernel.
190 vss_msg
->vss_hdr
.operation
= VSS_OP_REGISTER1
;
192 len
= write(vss_fd
, vss_msg
, sizeof(struct hv_vss_msg
));
194 syslog(LOG_ERR
, "registration to kernel failed; error: %d %s",
195 errno
, strerror(errno
));
206 if (poll(&pfd
, 1, -1) < 0) {
207 syslog(LOG_ERR
, "poll failed; error:%d %s", errno
, strerror(errno
));
208 if (errno
== EINVAL
) {
216 len
= read(vss_fd
, vss_msg
, sizeof(struct hv_vss_msg
));
219 if (len
!= sizeof(kernel_modver
)) {
220 syslog(LOG_ERR
, "invalid version negotiation");
223 kernel_modver
= *(__u32
*)vss_msg
;
225 syslog(LOG_INFO
, "VSS: kernel module version: %d",
230 if (len
!= sizeof(struct hv_vss_msg
)) {
231 syslog(LOG_ERR
, "read failed; error:%d %s",
232 errno
, strerror(errno
));
237 op
= vss_msg
->vss_hdr
.operation
;
243 error
= vss_operate(op
);
244 syslog(LOG_INFO
, "VSS: op=%s: %s\n",
245 op
== VSS_OP_FREEZE
? "FREEZE" : "THAW",
246 error
? "failed" : "succeeded");
250 syslog(LOG_ERR
, "op=%d failed!", op
);
251 syslog(LOG_ERR
, "report it with these files:");
252 syslog(LOG_ERR
, "/etc/fstab and /proc/mounts");
256 syslog(LOG_ERR
, "Illegal op:%d\n", op
);
258 vss_msg
->error
= error
;
259 len
= write(vss_fd
, vss_msg
, sizeof(struct hv_vss_msg
));
260 if (len
!= sizeof(struct hv_vss_msg
)) {
261 syslog(LOG_ERR
, "write failed; error: %d %s", errno
,