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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
commit | 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch) | |
tree | a94efe259b9009378be6d90eb30d2b019d95c194 /tools/hv/hv_vss_daemon.c | |
parent | Initial commit. (diff) | |
download | linux-430c2fc249ea5c0536abd21c23382884005c9093.tar.xz linux-430c2fc249ea5c0536abd21c23382884005c9093.zip |
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'tools/hv/hv_vss_daemon.c')
-rw-r--r-- | tools/hv/hv_vss_daemon.c | 355 |
1 files changed, 355 insertions, 0 deletions
diff --git a/tools/hv/hv_vss_daemon.c b/tools/hv/hv_vss_daemon.c new file mode 100644 index 000000000..dd111870b --- /dev/null +++ b/tools/hv/hv_vss_daemon.c @@ -0,0 +1,355 @@ +// 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> + +static bool fs_frozen; + +/* 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 (operation == VSS_OP_FREEZE) { + if (error) + goto err; + fs_frozen = true; + } + } + + endmntent(mounts); + + if (root_seen) { + error |= vss_do_freeze("/", cmd); + if (operation == VSS_OP_FREEZE) { + if (error) + goto err; + fs_frozen = true; + } + } + + if (operation == VSS_OP_THAW && !error) + fs_frozen = false; + + goto out; +err: + save_errno = errno; + if (ent) { + strncpy(errdir, ent->mnt_dir, sizeof(errdir)-1); + endmntent(mounts); + } + vss_operate(VSS_OP_THAW); + fs_frozen = false; + /* 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 = -1, 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; + __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()); + +reopen_vss_fd: + if (vss_fd != -1) + close(vss_fd); + if (fs_frozen) { + if (vss_operate(VSS_OP_THAW) || fs_frozen) { + syslog(LOG_ERR, "failed to thaw file system: err=%d", + errno); + exit(EXIT_FAILURE); + } + } + + in_handshake = 1; + 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)); + goto reopen_vss_fd; + } + + 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); + } + + /* + * The write() may return an error due to the faked VSS_OP_THAW + * message upon hibernation. Ignore the error by resetting the + * dev file, i.e. closing and re-opening it. + */ + 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)); + goto reopen_vss_fd; + } + } + + close(vss_fd); + exit(0); +} |