[linux-2.6-block.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 <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 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 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':
		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>
1330fc35	25	#include <sys/sysmacros.h>
7b413b65	26	#include <fcntl.h>
96dd86fa	27	#include <stdio.h>
d3d1ee3a	28	#include <mntent.h>
96dd86fa S	29	#include <stdlib.h>
	30	#include <unistd.h>
	31	#include <string.h>
	32	#include <ctype.h>
	33	#include <errno.h>
7b413b65	34	#include <linux/fs.h>
ea81fdf0	35	#include <linux/major.h>
96dd86fa	36	#include <linux/hyperv.h>
96dd86fa	37	#include <syslog.h>
170f4bea	38	#include <getopt.h>
07136793 VK	39	#include <stdbool.h>
07136793 VK	40	#include <dirent.h>
96dd86fa	41
4f689190 DC	42	/* Don't use syslog() in the function since that can cause write to disk */
4f689190 DC	43	static int vss_do_freeze(char *dir, unsigned int cmd)
7b413b65 OH	44	{
	45	int ret, fd = open(dir, O_RDONLY);
	46
	47	if (fd < 0)
	48	return 1;
4f689190	49
7b413b65	50	ret = ioctl(fd, cmd, 0);
4f689190 DC	51
	52	/*
	53	* If a partition is mounted more than once, only the first
	54	* FREEZE/THAW can succeed and the later ones will get
	55	* EBUSY/EINVAL respectively: there could be 2 cases:
	56	* 1) a user may mount the same partition to differnt directories
	57	* by mistake or on purpose;
	58	* 2) The subvolume of btrfs appears to have the same partition
	59	* mounted more than once.
	60	*/
	61	if (ret) {
	62	if ((cmd == FIFREEZE && errno == EBUSY) \|\|
	63	(cmd == FITHAW && errno == EINVAL)) {
	64	close(fd);
	65	return 0;
	66	}
	67	}
	68
7b413b65 OH	69	close(fd);
	70	return !!ret;
	71	}
	72
07136793 VK	73	static bool is_dev_loop(const char *blkname)
	74	{
	75	char *buffer;
	76	DIR *dir;
	77	struct dirent *entry;
	78	bool ret = false;
	79
	80	buffer = malloc(PATH_MAX);
	81	if (!buffer) {
	82	syslog(LOG_ERR, "Can't allocate memory!");
	83	exit(1);
	84	}
	85
	86	snprintf(buffer, PATH_MAX, "%s/loop", blkname);
	87	if (!access(buffer, R_OK \| X_OK)) {
	88	ret = true;
	89	goto free_buffer;
	90	} else if (errno != ENOENT) {
	91	syslog(LOG_ERR, "Can't access: %s; error:%d %s!",
	92	buffer, errno, strerror(errno));
	93	}
	94
	95	snprintf(buffer, PATH_MAX, "%s/slaves", blkname);
	96	dir = opendir(buffer);
	97	if (!dir) {
	98	if (errno != ENOENT)
	99	syslog(LOG_ERR, "Can't opendir: %s; error:%d %s!",
	100	buffer, errno, strerror(errno));
	101	goto free_buffer;
	102	}
	103
	104	while ((entry = readdir(dir)) != NULL) {
	105	if (strcmp(entry->d_name, ".") == 0 \|\|
	106	strcmp(entry->d_name, "..") == 0)
	107	continue;
	108
	109	snprintf(buffer, PATH_MAX, "%s/slaves/%s", blkname,
	110	entry->d_name);
	111	if (is_dev_loop(buffer)) {
	112	ret = true;
	113	break;
	114	}
	115	}
	116	closedir(dir);
	117	free_buffer:
	118	free(buffer);
	119	return ret;
	120	}
	121
96dd86fa S	122	static int vss_operate(int operation)
96dd86fa S	123	{
d3d1ee3a OH	124	char match[] = "/dev/";
	125	FILE *mounts;
	126	struct mntent *ent;
ea81fdf0	127	struct stat sb;
4ce50e94	128	char errdir[1024] = {0};
07136793	129	char blkdir[23]; /* /sys/dev/block/XXX:XXX */
7b413b65	130	unsigned int cmd;
7a401744	131	int error = 0, root_seen = 0, save_errno = 0;
96dd86fa S	132
	133	switch (operation) {
	134	case VSS_OP_FREEZE:
7b413b65	135	cmd = FIFREEZE;
96dd86fa S	136	break;
96dd86fa S	137	case VSS_OP_THAW:
7b413b65	138	cmd = FITHAW;
96dd86fa	139	break;
eb8905b8 OH	140	default:
eb8905b8 OH	141	return -1;
96dd86fa S	142	}
96dd86fa S	143
d3d1ee3a OH	144	mounts = setmntent("/proc/mounts", "r");
d3d1ee3a OH	145	if (mounts == NULL)
eb8905b8	146	return -1;
96dd86fa	147
0e272639	148	while ((ent = getmntent(mounts))) {
d3d1ee3a	149	if (strncmp(ent->mnt_fsname, match, strlen(match)))
96dd86fa	150	continue;
07136793 VK	151	if (stat(ent->mnt_fsname, &sb)) {
	152	syslog(LOG_ERR, "Can't stat: %s; error:%d %s!",
	153	ent->mnt_fsname, errno, strerror(errno));
	154	} else {
	155	sprintf(blkdir, "/sys/dev/block/%d:%d",
	156	major(sb.st_rdev), minor(sb.st_rdev));
	157	if (is_dev_loop(blkdir))
	158	continue;
	159	}
9e5db05a	160	if (hasmntopt(ent, MNTOPT_RO) != NULL)
10b637b4	161	continue;
f33b2155 S	162	if (strcmp(ent->mnt_type, "vfat") == 0)
f33b2155 S	163	continue;
d3d1ee3a OH	164	if (strcmp(ent->mnt_dir, "/") == 0) {
	165	root_seen = 1;
	166	continue;
	167	}
4f689190 DC	168	error \|= vss_do_freeze(ent->mnt_dir, cmd);
	169	if (error && operation == VSS_OP_FREEZE)
	170	goto err;
96dd86fa	171	}
96dd86fa	172
4ce50e94 VC	173	endmntent(mounts);
4ce50e94 VC	174
d3d1ee3a	175	if (root_seen) {
4f689190 DC	176	error \|= vss_do_freeze("/", cmd);
	177	if (error && operation == VSS_OP_FREEZE)
	178	goto err;
d3d1ee3a	179	}
96dd86fa	180
7a401744	181	goto out;
4f689190	182	err:
7a401744	183	save_errno = errno;
4ce50e94 VC	184	if (ent) {
	185	strncpy(errdir, ent->mnt_dir, sizeof(errdir)-1);
	186	endmntent(mounts);
	187	}
4f689190	188	vss_operate(VSS_OP_THAW);
7a401744 VK	189	/* Call syslog after we thaw all filesystems */
	190	if (ent)
	191	syslog(LOG_ERR, "FREEZE of %s failed; error:%d %s",
4ce50e94	192	errdir, save_errno, strerror(save_errno));
7a401744 VK	193	else
	194	syslog(LOG_ERR, "FREEZE of / failed; error:%d %s", save_errno,
	195	strerror(save_errno));
	196	out:
96dd86fa S	197	return error;
	198	}
	199
170f4bea VK	200	void print_usage(char *argv[])
	201	{
	202	fprintf(stderr, "Usage: %s [options]\n"
	203	"Options are:\n"
	204	" -n, --no-daemon stay in foreground, don't daemonize\n"
	205	" -h, --help print this help\n", argv[0]);
	206	}
	207
	208	int main(int argc, char *argv[])
96dd86fa	209	{
f5722b9b	210	int vss_fd, len;
96dd86fa	211	int error;
96dd86fa	212	struct pollfd pfd;
96dd86fa	213	int op;
f5722b9b	214	struct hv_vss_msg vss_msg[1];
170f4bea	215	int daemonize = 1, long_index = 0, opt;
cd8dc054 VK	216	int in_handshake = 1;
cd8dc054 VK	217	__u32 kernel_modver;
170f4bea VK	218
	219	static struct option long_options[] = {
	220	{"help", no_argument, 0, 'h' },
	221	{"no-daemon", no_argument, 0, 'n' },
	222	{0, 0, 0, 0 }
	223	};
	224
	225	while ((opt = getopt_long(argc, argv, "hn", long_options,
	226	&long_index)) != -1) {
	227	switch (opt) {
	228	case 'n':
	229	daemonize = 0;
	230	break;
	231	case 'h':
	232	default:
	233	print_usage(argv);
	234	exit(EXIT_FAILURE);
	235	}
	236	}
96dd86fa	237
170f4bea	238	if (daemonize && daemon(1, 0))
eb8905b8 OH	239	return 1;
eb8905b8 OH	240
96dd86fa S	241	openlog("Hyper-V VSS", 0, LOG_USER);
	242	syslog(LOG_INFO, "VSS starting; pid is:%d", getpid());
	243
f5722b9b VK	244	vss_fd = open("/dev/vmbus/hv_vss", O_RDWR);
	245	if (vss_fd < 0) {
	246	syslog(LOG_ERR, "open /dev/vmbus/hv_vss failed; error: %d %s",
	247	errno, strerror(errno));
d12e1469 TH	248	exit(EXIT_FAILURE);
d12e1469 TH	249	}
96dd86fa S	250	/*
	251	* Register ourselves with the kernel.
	252	*/
f5722b9b	253	vss_msg->vss_hdr.operation = VSS_OP_REGISTER1;
96dd86fa	254
f5722b9b	255	len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
96dd86fa	256	if (len < 0) {
f5722b9b VK	257	syslog(LOG_ERR, "registration to kernel failed; error: %d %s",
	258	errno, strerror(errno));
	259	close(vss_fd);
96dd86fa S	260	exit(EXIT_FAILURE);
	261	}
	262
f5722b9b	263	pfd.fd = vss_fd;
96dd86fa S	264
96dd86fa S	265	while (1) {
96dd86fa S	266	pfd.events = POLLIN;
96dd86fa S	267	pfd.revents = 0;
9561d479 TH	268
	269	if (poll(&pfd, 1, -1) < 0) {
	270	syslog(LOG_ERR, "poll failed; error:%d %s", errno, strerror(errno));
	271	if (errno == EINVAL) {
f5722b9b	272	close(vss_fd);
9561d479 TH	273	exit(EXIT_FAILURE);
	274	}
	275	else
	276	continue;
	277	}
96dd86fa	278
f5722b9b	279	len = read(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
96dd86fa	280
cd8dc054 VK	281	if (in_handshake) {
	282	if (len != sizeof(kernel_modver)) {
	283	syslog(LOG_ERR, "invalid version negotiation");
	284	exit(EXIT_FAILURE);
	285	}
	286	kernel_modver = (__u32 )vss_msg;
	287	in_handshake = 0;
	288	syslog(LOG_INFO, "VSS: kernel module version: %d",
	289	kernel_modver);
	290	continue;
	291	}
	292
f5722b9b VK	293	if (len != sizeof(struct hv_vss_msg)) {
	294	syslog(LOG_ERR, "read failed; error:%d %s",
	295	errno, strerror(errno));
	296	close(vss_fd);
	297	return EXIT_FAILURE;
5edf5ee4 OH	298	}
5edf5ee4 OH	299
96dd86fa S	300	op = vss_msg->vss_hdr.operation;
	301	error = HV_S_OK;
	302
	303	switch (op) {
	304	case VSS_OP_FREEZE:
	305	case VSS_OP_THAW:
	306	error = vss_operate(op);
4f689190 DC	307	syslog(LOG_INFO, "VSS: op=%s: %s\n",
	308	op == VSS_OP_FREEZE ? "FREEZE" : "THAW",
	309	error ? "failed" : "succeeded");
	310
	311	if (error) {
96dd86fa	312	error = HV_E_FAIL;
4f689190 DC	313	syslog(LOG_ERR, "op=%d failed!", op);
	314	syslog(LOG_ERR, "report it with these files:");
	315	syslog(LOG_ERR, "/etc/fstab and /proc/mounts");
	316	}
96dd86fa	317	break;
db886e4d AN	318	case VSS_OP_HOT_BACKUP:
	319	syslog(LOG_INFO, "VSS: op=CHECK HOT BACKUP\n");
	320	break;
96dd86fa S	321	default:
	322	syslog(LOG_ERR, "Illegal op:%d\n", op);
	323	}
	324	vss_msg->error = error;
a689d251	325	len = write(vss_fd, vss_msg, sizeof(struct hv_vss_msg));
f5722b9b VK	326	if (len != sizeof(struct hv_vss_msg)) {
	327	syslog(LOG_ERR, "write failed; error: %d %s", errno,
	328	strerror(errno));
6113e3d2 AN	329
	330	if (op == VSS_OP_FREEZE)
	331	vss_operate(VSS_OP_THAW);
96dd86fa S	332	}
	333	}
	334
f5722b9b VK	335	close(vss_fd);
f5722b9b VK	336	exit(0);
96dd86fa	337	}