[mirror_ubuntu-eoan-kernel.git] / tools / hv / hv_vss_daemon.c

/*
 * An implementation of the host initiated guest snapshot for Hyper-V.
 *
 *
 * Copyright (C) 2013, Microsoft, Inc.
 * Author : K. Y. Srinivasan <kys@microsoft.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 * NON INFRINGEMENT.  See the GNU General Public License for more
 * details.
 *
 */


#include <sys/types.h>
#include <sys/poll.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <mntent.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>
#include <linux/fs.h>
#include <linux/major.h>
#include <linux/hyperv.h>
#include <syslog.h>
#include <getopt.h>

/* Don't use syslog() in the function since that can cause write to disk */
static int vss_do_freeze(char *dir, unsigned int cmd)
{
	int ret, fd = open(dir, O_RDONLY);

	if (fd < 0)
		return 1;

	ret = ioctl(fd, cmd, 0);

	/*
	 * If a partition is mounted more than once, only the first
	 * FREEZE/THAW can succeed and the later ones will get
	 * EBUSY/EINVAL respectively: there could be 2 cases:
	 * 1) a user may mount the same partition to differnt directories
	 *  by mistake or on purpose;
	 * 2) The subvolume of btrfs appears to have the same partition
	 * mounted more than once.
	 */
	if (ret) {
		if ((cmd == FIFREEZE && errno == EBUSY) ||
		    (cmd == FITHAW && errno == EINVAL)) {
			close(fd);
			return 0;
		}
	}

	close(fd);
	return !!ret;
}

static int vss_operate(int operation)
{
	char match[] = "/dev/";
	FILE *mounts;
	struct mntent *ent;
	struct stat sb;
	char errdir[1024] = {0};
	unsigned int cmd;
	int error = 0, root_seen = 0, save_errno = 0;

	switch (operation) {
	case VSS_OP_FREEZE:
		cmd = FIFREEZE;
		break;
	case VSS_OP_THAW:
		cmd = FITHAW;
		break;
	default:
		return -1;
	}

	mounts = setmntent("/proc/mounts", "r");
	if (mounts == NULL)
		return -1;

	while ((ent = getmntent(mounts))) {
		if (strncmp(ent->mnt_fsname, match, strlen(match)))
			continue;
		if (stat(ent->mnt_fsname, &sb) == -1)
			continue;
		if (S_ISBLK(sb.st_mode) && major(sb.st_rdev) == LOOP_MAJOR)
			continue;
		if (hasmntopt(ent, MNTOPT_RO) != NULL)
			continue;
		if (strcmp(ent->mnt_type, "vfat") == 0)
			continue;
		if (strcmp(ent->mnt_dir, "/") == 0) {
			root_seen = 1;
			continue;
		}
		error |= vss_do_freeze(ent->mnt_dir, cmd);
		if (error && operation == VSS_OP_FREEZE)
			goto err;
	}

	endmntent(mounts);

	if (root_seen) {
		error |= vss_do_freeze("/", cmd);
		if (error && operation == VSS_OP_FREEZE)
			goto err;
	}

	goto out;
err:
	save_errno = errno;
	if (ent) {
		strncpy(errdir, ent->mnt_dir, sizeof(errdir)-1);
		endmntent(mounts);
	}
	vss_operate(VSS_OP_THAW);
	/* Call syslog after we thaw all filesystems */
	if (ent)
		syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s",
		       errdir, save_errno, strerror(save_errno));
	else
		syslog(LOG_ERR, "FREEZE of / failed; error:%d %s", save_errno,
		       strerror(save_errno));
out:
	return error;
}

void print_usage(char *argv[])
{
	fprintf(stderr, "Usage: %s [options]\n"
		"Options are:\n"
		"  -n, --no-daemon        stay in foreground, don't daemonize\n"
		"  -h, --help             print this help\n", argv[0]);
}

int main(int argc, char *argv[])
{
	int vss_fd, len;
	int error;
	struct pollfd pfd;
	int	op;
	struct hv_vss_msg vss_msg[1];
	int daemonize = 1, long_index = 0, opt;
	int in_handshake = 1;
	__u32 kernel_modver;

	static struct option long_options[] = {
		{"help",	no_argument,	   0,  'h' },
		{"no-daemon",	no_argument,	   0,  'n' },
		{0,		0,		   0,  0   }
	};

	while ((opt = getopt_long(argc, argv, "hn", long_options,
				  &long_index)) != -1) {
		switch (opt) {
		case 'n':
			daemonize = 0;
			break;
		case 'h':
		default:
			print_usage(argv);
			exit(EXIT_FAILURE);
		}
	}

	if (daemonize && daemon(1, 0))
		return 1;

	openlog("Hyper-V VSS", 0, LOG_USER);
	syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());

	vss_fd = open("/dev/vmbus/hv_vss", O_RDWR);
	if (vss_fd < 0) {
		syslog(LOG_ERR, "open /dev/vmbus/hv_vss failed; error: %d %s",
		       errno, strerror(errno));
		exit(EXIT_FAILURE);
	}
	/*
	 * Register ourselves with the kernel.
	 */
	vss_msg->vss_hdr.operation = VSS_OP_REGISTER1;

	len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
	if (len < 0) {
		syslog(LOG_ERR, "registration to kernel failed; error: %d %s",
		       errno, strerror(errno));
		close(vss_fd);
		exit(EXIT_FAILURE);
	}

	pfd.fd = vss_fd;

	while (1) {
		pfd.events = POLLIN;
		pfd.revents = 0;

		if (poll(&pfd, 1, -1) < 0) {
			syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno));
			if (errno == EINVAL) {
				close(vss_fd);
				exit(EXIT_FAILURE);
			}
			else
				continue;
		}

		len = read(vss_fd, vss_msg, sizeof(struct hv_vss_msg));

		if (in_handshake) {
			if (len != sizeof(kernel_modver)) {
				syslog(LOG_ERR, "invalid version negotiation");
				exit(EXIT_FAILURE);
			}
			kernel_modver = *(__u32 *)vss_msg;
			in_handshake = 0;
			syslog(LOG_INFO, "VSS: kernel module version: %d",
			       kernel_modver);
			continue;
		}

		if (len != sizeof(struct hv_vss_msg)) {
			syslog(LOG_ERR, "read failed; error:%d %s",
			       errno, strerror(errno));
			close(vss_fd);
			return EXIT_FAILURE;
		}

		op = vss_msg->vss_hdr.operation;
		error =  HV_S_OK;

		switch (op) {
		case VSS_OP_FREEZE:
		case VSS_OP_THAW:
			error = vss_operate(op);
			syslog(LOG_INFO, "VSS: op=%s: %s\n",
				op == VSS_OP_FREEZE ? "FREEZE" : "THAW",
				error ? "failed" : "succeeded");

			if (error) {
				error = HV_E_FAIL;
				syslog(LOG_ERR, "op=%d failed!", op);
				syslog(LOG_ERR, "report it with these files:");
				syslog(LOG_ERR, "/etc/fstab and /proc/mounts");
			}
			break;
		case VSS_OP_HOT_BACKUP:
			syslog(LOG_INFO, "VSS: op=CHECK HOT BACKUP\n");
			break;
		default:
			syslog(LOG_ERR, "Illegal op:%d\n", op);
		}
		vss_msg->error = error;
		len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
		if (len != sizeof(struct hv_vss_msg)) {
			syslog(LOG_ERR, "write failed; error: %d %s", errno,
			       strerror(errno));

			if (op == VSS_OP_FREEZE)
				vss_operate(VSS_OP_THAW);
		}
	}

	close(vss_fd);
	exit(0);
}
Commit	Line	Data
96dd86fa S	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>
96dd86fa	22	#include <sys/poll.h>
7b413b65	23	#include <sys/ioctl.h>
ea81fdf0	24	#include <sys/stat.h>
7b413b65	25	#include <fcntl.h>
96dd86fa	26	#include <stdio.h>
d3d1ee3a	27	#include <mntent.h>
96dd86fa S	28	#include <stdlib.h>
	29	#include <unistd.h>
	30	#include <string.h>
	31	#include <ctype.h>
	32	#include <errno.h>
7b413b65	33	#include <linux/fs.h>
ea81fdf0	34	#include <linux/major.h>
96dd86fa	35	#include <linux/hyperv.h>
96dd86fa	36	#include <syslog.h>
170f4bea	37	#include <getopt.h>
96dd86fa	38
4f689190 DC	39	/* Don't use syslog() in the function since that can cause write to disk */
4f689190 DC	40	static int vss_do_freeze(char *dir, unsigned int cmd)
7b413b65 OH	41	{
	42	int ret, fd = open(dir, O_RDONLY);
	43
	44	if (fd < 0)
	45	return 1;
4f689190	46
7b413b65	47	ret = ioctl(fd, cmd, 0);
4f689190 DC	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
7b413b65 OH	66	close(fd);
	67	return !!ret;
	68	}
	69
96dd86fa S	70	static int vss_operate(int operation)
96dd86fa S	71	{
d3d1ee3a OH	72	char match[] = "/dev/";
	73	FILE *mounts;
	74	struct mntent *ent;
ea81fdf0	75	struct stat sb;
4ce50e94	76	char errdir[1024] = {0};
7b413b65	77	unsigned int cmd;
7a401744	78	int error = 0, root_seen = 0, save_errno = 0;
96dd86fa S	79
	80	switch (operation) {
	81	case VSS_OP_FREEZE:
7b413b65	82	cmd = FIFREEZE;
96dd86fa S	83	break;
96dd86fa S	84	case VSS_OP_THAW:
7b413b65	85	cmd = FITHAW;
96dd86fa	86	break;
eb8905b8 OH	87	default:
eb8905b8 OH	88	return -1;
96dd86fa S	89	}
96dd86fa S	90
d3d1ee3a OH	91	mounts = setmntent("/proc/mounts", "r");
d3d1ee3a OH	92	if (mounts == NULL)
eb8905b8	93	return -1;
96dd86fa	94
0e272639	95	while ((ent = getmntent(mounts))) {
d3d1ee3a	96	if (strncmp(ent->mnt_fsname, match, strlen(match)))
96dd86fa	97	continue;
ea81fdf0 AN	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;
9e5db05a	102	if (hasmntopt(ent, MNTOPT_RO) != NULL)
10b637b4	103	continue;
f33b2155 S	104	if (strcmp(ent->mnt_type, "vfat") == 0)
f33b2155 S	105	continue;
d3d1ee3a OH	106	if (strcmp(ent->mnt_dir, "/") == 0) {
	107	root_seen = 1;
	108	continue;
	109	}
4f689190 DC	110	error \|= vss_do_freeze(ent->mnt_dir, cmd);
	111	if (error && operation == VSS_OP_FREEZE)
	112	goto err;
96dd86fa	113	}
96dd86fa	114
4ce50e94 VC	115	endmntent(mounts);
4ce50e94 VC	116
d3d1ee3a	117	if (root_seen) {
4f689190 DC	118	error \|= vss_do_freeze("/", cmd);
	119	if (error && operation == VSS_OP_FREEZE)
	120	goto err;
d3d1ee3a	121	}
96dd86fa	122
7a401744	123	goto out;
4f689190	124	err:
7a401744	125	save_errno = errno;
4ce50e94 VC	126	if (ent) {
	127	strncpy(errdir, ent->mnt_dir, sizeof(errdir)-1);
	128	endmntent(mounts);
	129	}
4f689190	130	vss_operate(VSS_OP_THAW);
7a401744 VK	131	/* Call syslog after we thaw all filesystems */
	132	if (ent)
	133	syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s",
4ce50e94	134	errdir, save_errno, strerror(save_errno));
7a401744 VK	135	else
	136	syslog(LOG_ERR, "FREEZE of / failed; error:%d %s", save_errno,
	137	strerror(save_errno));
	138	out:
96dd86fa S	139	return error;
	140	}
	141
170f4bea VK	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[])
96dd86fa	151	{
f5722b9b	152	int vss_fd, len;
96dd86fa	153	int error;
96dd86fa	154	struct pollfd pfd;
96dd86fa	155	int op;
f5722b9b	156	struct hv_vss_msg vss_msg[1];
170f4bea	157	int daemonize = 1, long_index = 0, opt;
cd8dc054 VK	158	int in_handshake = 1;
cd8dc054 VK	159	__u32 kernel_modver;
170f4bea VK	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	}
96dd86fa	179
170f4bea	180	if (daemonize && daemon(1, 0))
eb8905b8 OH	181	return 1;
eb8905b8 OH	182
96dd86fa S	183	openlog("Hyper-V VSS", 0, LOG_USER);
	184	syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
	185
f5722b9b VK	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));
d12e1469 TH	190	exit(EXIT_FAILURE);
d12e1469 TH	191	}
96dd86fa S	192	/*
	193	* Register ourselves with the kernel.
	194	*/
f5722b9b	195	vss_msg->vss_hdr.operation = VSS_OP_REGISTER1;
96dd86fa	196
f5722b9b	197	len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
96dd86fa	198	if (len < 0) {
f5722b9b VK	199	syslog(LOG_ERR, "registration to kernel failed; error: %d %s",
	200	errno, strerror(errno));
	201	close(vss_fd);
96dd86fa S	202	exit(EXIT_FAILURE);
	203	}
	204
f5722b9b	205	pfd.fd = vss_fd;
96dd86fa S	206
96dd86fa S	207	while (1) {
96dd86fa S	208	pfd.events = POLLIN;
96dd86fa S	209	pfd.revents = 0;
9561d479 TH	210
	211	if (poll(&pfd, 1, -1) < 0) {
	212	syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno));
	213	if (errno == EINVAL) {
f5722b9b	214	close(vss_fd);
9561d479 TH	215	exit(EXIT_FAILURE);
	216	}
	217	else
	218	continue;
	219	}
96dd86fa	220
f5722b9b	221	len = read(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
96dd86fa	222
cd8dc054 VK	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
f5722b9b VK	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;
5edf5ee4 OH	240	}
5edf5ee4 OH	241
96dd86fa S	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);
4f689190 DC	249	syslog(LOG_INFO, "VSS: op=%s: %s\n",
	250	op == VSS_OP_FREEZE ? "FREEZE" : "THAW",
	251	error ? "failed" : "succeeded");
	252
	253	if (error) {
96dd86fa	254	error = HV_E_FAIL;
4f689190 DC	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	}
96dd86fa	259	break;
db886e4d AN	260	case VSS_OP_HOT_BACKUP:
	261	syslog(LOG_INFO, "VSS: op=CHECK HOT BACKUP\n");
	262	break;
96dd86fa S	263	default:
	264	syslog(LOG_ERR, "Illegal op:%d\n", op);
	265	}
	266	vss_msg->error = error;
a689d251	267	len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
f5722b9b VK	268	if (len != sizeof(struct hv_vss_msg)) {
	269	syslog(LOG_ERR, "write failed; error: %d %s", errno,
	270	strerror(errno));
6113e3d2 AN	271
	272	if (op == VSS_OP_FREEZE)
	273	vss_operate(VSS_OP_THAW);
96dd86fa S	274	}
	275	}
	276
f5722b9b VK	277	close(vss_fd);
f5722b9b VK	278	exit(0);
96dd86fa	279	}