tools/hv/hv_vss_daemon.c - linux/torvalds/linux - Git at Google

 // 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);
 }
	// 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);
	}