[linux-2.6-block.git] / tools / hv / hv_vss_daemon.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * An implementation of the host initiated guest snapshot for Hyper-V.
 *
 * Copyright (C) 2013, Microsoft, Inc.
 * Author : K. Y. Srinivasan <kys@microsoft.com>
 */


#include <sys/types.h>
#include <sys/poll.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/sysmacros.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>
#include <stdbool.h>
#include <dirent.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 different 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 bool is_dev_loop(const char *blkname)
{
	char *buffer;
	DIR *dir;
	struct dirent *entry;
	bool ret = false;

	buffer = malloc(PATH_MAX);
	if (!buffer) {
		syslog(LOG_ERR, "Can't allocate memory!");
		exit(1);
	}

	snprintf(buffer, PATH_MAX, "%s/loop", blkname);
	if (!access(buffer, R_OK | X_OK)) {
		ret = true;
		goto free_buffer;
	} else if (errno != ENOENT) {
		syslog(LOG_ERR, "Can't access: %s; error:%d %s!",
		       buffer, errno, strerror(errno));
	}

	snprintf(buffer, PATH_MAX, "%s/slaves", blkname);
	dir = opendir(buffer);
	if (!dir) {
		if (errno != ENOENT)
			syslog(LOG_ERR, "Can't opendir: %s; error:%d %s!",
			       buffer, errno, strerror(errno));
		goto free_buffer;
	}

	while ((entry = readdir(dir)) != NULL) {
		if (strcmp(entry->d_name, ".") == 0 ||
		    strcmp(entry->d_name, "..") == 0)
			continue;

		snprintf(buffer, PATH_MAX, "%s/slaves/%s", blkname,
			 entry->d_name);
		if (is_dev_loop(buffer)) {
			ret = true;
			break;
		}
	}
	closedir(dir);
free_buffer:
	free(buffer);
	return ret;
}

static int vss_operate(int operation)
{
	char match[] = "/dev/";
	FILE *mounts;
	struct mntent *ent;
	struct stat sb;
	char errdir[1024] = {0};
	char blkdir[23]; /* /sys/dev/block/XXX:XXX */
	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)) {
			syslog(LOG_ERR, "Can't stat: %s; error:%d %s!",
			       ent->mnt_fsname, errno, strerror(errno));
		} else {
			sprintf(blkdir, "/sys/dev/block/%d:%d",
				major(sb.st_rdev), minor(sb.st_rdev));
			if (is_dev_loop(blkdir))
				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':
			print_usage(argv);
			exit(0);
		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
43aa3132	1	// SPDX-License-Identifier: GPL-2.0-only
96dd86fa S	2	/*
	3	* An implementation of the host initiated guest snapshot for Hyper-V.
	4	*
96dd86fa S	5	* Copyright (C) 2013, Microsoft, Inc.
96dd86fa S	6	* Author : K. Y. Srinivasan <kys@microsoft.com>
96dd86fa S	7	*/
	8
	9
	10	#include <sys/types.h>
96dd86fa	11	#include <sys/poll.h>
7b413b65	12	#include <sys/ioctl.h>
ea81fdf0	13	#include <sys/stat.h>
1330fc35	14	#include <sys/sysmacros.h>
7b413b65	15	#include <fcntl.h>
96dd86fa	16	#include <stdio.h>
d3d1ee3a	17	#include <mntent.h>
96dd86fa S	18	#include <stdlib.h>
	19	#include <unistd.h>
	20	#include <string.h>
	21	#include <ctype.h>
	22	#include <errno.h>
7b413b65	23	#include <linux/fs.h>
ea81fdf0	24	#include <linux/major.h>
96dd86fa	25	#include <linux/hyperv.h>
96dd86fa	26	#include <syslog.h>
170f4bea	27	#include <getopt.h>
07136793 VK	28	#include <stdbool.h>
07136793 VK	29	#include <dirent.h>
96dd86fa	30
4f689190 DC	31	/* Don't use syslog() in the function since that can cause write to disk */
4f689190 DC	32	static int vss_do_freeze(char *dir, unsigned int cmd)
7b413b65 OH	33	{
	34	int ret, fd = open(dir, O_RDONLY);
	35
	36	if (fd < 0)
	37	return 1;
4f689190	38
7b413b65	39	ret = ioctl(fd, cmd, 0);
4f689190 DC	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:
2d35c660	45	* 1) a user may mount the same partition to different directories
4f689190 DC	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
7b413b65 OH	58	close(fd);
	59	return !!ret;
	60	}
	61
07136793 VK	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
96dd86fa S	111	static int vss_operate(int operation)
96dd86fa S	112	{
d3d1ee3a OH	113	char match[] = "/dev/";
	114	FILE *mounts;
	115	struct mntent *ent;
ea81fdf0	116	struct stat sb;
4ce50e94	117	char errdir[1024] = {0};
07136793	118	char blkdir[23]; /* /sys/dev/block/XXX:XXX */
7b413b65	119	unsigned int cmd;
7a401744	120	int error = 0, root_seen = 0, save_errno = 0;
96dd86fa S	121
	122	switch (operation) {
	123	case VSS_OP_FREEZE:
7b413b65	124	cmd = FIFREEZE;
96dd86fa S	125	break;
96dd86fa S	126	case VSS_OP_THAW:
7b413b65	127	cmd = FITHAW;
96dd86fa	128	break;
eb8905b8 OH	129	default:
eb8905b8 OH	130	return -1;
96dd86fa S	131	}
96dd86fa S	132
d3d1ee3a OH	133	mounts = setmntent("/proc/mounts", "r");
d3d1ee3a OH	134	if (mounts == NULL)
eb8905b8	135	return -1;
96dd86fa	136
0e272639	137	while ((ent = getmntent(mounts))) {
d3d1ee3a	138	if (strncmp(ent->mnt_fsname, match, strlen(match)))
96dd86fa	139	continue;
07136793 VK	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	}
9e5db05a	149	if (hasmntopt(ent, MNTOPT_RO) != NULL)
10b637b4	150	continue;
f33b2155 S	151	if (strcmp(ent->mnt_type, "vfat") == 0)
f33b2155 S	152	continue;
d3d1ee3a OH	153	if (strcmp(ent->mnt_dir, "/") == 0) {
	154	root_seen = 1;
	155	continue;
	156	}
4f689190 DC	157	error \|= vss_do_freeze(ent->mnt_dir, cmd);
	158	if (error && operation == VSS_OP_FREEZE)
	159	goto err;
96dd86fa	160	}
96dd86fa	161
4ce50e94 VC	162	endmntent(mounts);
4ce50e94 VC	163
d3d1ee3a	164	if (root_seen) {
4f689190 DC	165	error \|= vss_do_freeze("/", cmd);
	166	if (error && operation == VSS_OP_FREEZE)
	167	goto err;
d3d1ee3a	168	}
96dd86fa	169
7a401744	170	goto out;
4f689190	171	err:
7a401744	172	save_errno = errno;
4ce50e94 VC	173	if (ent) {
	174	strncpy(errdir, ent->mnt_dir, sizeof(errdir)-1);
	175	endmntent(mounts);
	176	}
4f689190	177	vss_operate(VSS_OP_THAW);
7a401744 VK	178	/* Call syslog after we thaw all filesystems */
	179	if (ent)
	180	syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s",
4ce50e94	181	errdir, save_errno, strerror(save_errno));
7a401744 VK	182	else
	183	syslog(LOG_ERR, "FREEZE of / failed; error:%d %s", save_errno,
	184	strerror(save_errno));
	185	out:
96dd86fa S	186	return error;
	187	}
	188
170f4bea VK	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[])
96dd86fa	198	{
f5722b9b	199	int vss_fd, len;
96dd86fa	200	int error;
96dd86fa	201	struct pollfd pfd;
96dd86fa	202	int op;
f5722b9b	203	struct hv_vss_msg vss_msg[1];
170f4bea	204	int daemonize = 1, long_index = 0, opt;
cd8dc054 VK	205	int in_handshake = 1;
cd8dc054 VK	206	__u32 kernel_modver;
170f4bea VK	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':
b0995156 AV	221	print_usage(argv);
b0995156 AV	222	exit(0);
170f4bea VK	223	default:
	224	print_usage(argv);
	225	exit(EXIT_FAILURE);
	226	}
	227	}
96dd86fa	228
170f4bea	229	if (daemonize && daemon(1, 0))
eb8905b8 OH	230	return 1;
eb8905b8 OH	231
96dd86fa S	232	openlog("Hyper-V VSS", 0, LOG_USER);
	233	syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
	234
f5722b9b VK	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));
d12e1469 TH	239	exit(EXIT_FAILURE);
d12e1469 TH	240	}
96dd86fa S	241	/*
	242	* Register ourselves with the kernel.
	243	*/
f5722b9b	244	vss_msg->vss_hdr.operation = VSS_OP_REGISTER1;
96dd86fa	245
f5722b9b	246	len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
96dd86fa	247	if (len < 0) {
f5722b9b VK	248	syslog(LOG_ERR, "registration to kernel failed; error: %d %s",
	249	errno, strerror(errno));
	250	close(vss_fd);
96dd86fa S	251	exit(EXIT_FAILURE);
	252	}
	253
f5722b9b	254	pfd.fd = vss_fd;
96dd86fa S	255
96dd86fa S	256	while (1) {
96dd86fa S	257	pfd.events = POLLIN;
96dd86fa S	258	pfd.revents = 0;
9561d479 TH	259
	260	if (poll(&pfd, 1, -1) < 0) {
	261	syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno));
	262	if (errno == EINVAL) {
f5722b9b	263	close(vss_fd);
9561d479 TH	264	exit(EXIT_FAILURE);
	265	}
	266	else
	267	continue;
	268	}
96dd86fa	269
f5722b9b	270	len = read(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
96dd86fa	271
cd8dc054 VK	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
f5722b9b VK	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;
5edf5ee4 OH	289	}
5edf5ee4 OH	290
96dd86fa S	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);
4f689190 DC	298	syslog(LOG_INFO, "VSS: op=%s: %s\n",
	299	op == VSS_OP_FREEZE ? "FREEZE" : "THAW",
	300	error ? "failed" : "succeeded");
	301
	302	if (error) {
96dd86fa	303	error = HV_E_FAIL;
4f689190 DC	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	}
96dd86fa	308	break;
db886e4d AN	309	case VSS_OP_HOT_BACKUP:
	310	syslog(LOG_INFO, "VSS: op=CHECK HOT BACKUP\n");
	311	break;
96dd86fa S	312	default:
	313	syslog(LOG_ERR, "Illegal op:%d\n", op);
	314	}
	315	vss_msg->error = error;
a689d251	316	len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
f5722b9b VK	317	if (len != sizeof(struct hv_vss_msg)) {
	318	syslog(LOG_ERR, "write failed; error: %d %s", errno,
	319	strerror(errno));
6113e3d2 AN	320
	321	if (op == VSS_OP_FREEZE)
	322	vss_operate(VSS_OP_THAW);
96dd86fa S	323	}
	324	}
	325
f5722b9b VK	326	close(vss_fd);
f5722b9b VK	327	exit(0);
96dd86fa	328	}