287 lines
8.6 KiB
C
287 lines
8.6 KiB
C
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/*
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* QEMU Guest Agent Linux-specific command implementations
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*
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* Copyright IBM Corp. 2011
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*
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* Authors:
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* Michael Roth <mdroth@linux.vnet.ibm.com>
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* Michal Privoznik <mprivozn@redhat.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2 or later.
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* See the COPYING file in the top-level directory.
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*/
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#include "qemu/osdep.h"
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#include "qapi/error.h"
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#include "commands-common.h"
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#include "cutils.h"
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#include <mntent.h>
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#include <sys/ioctl.h>
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#if defined(CONFIG_FSFREEZE) || defined(CONFIG_FSTRIM)
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static int dev_major_minor(const char *devpath,
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unsigned int *devmajor, unsigned int *devminor)
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{
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struct stat st;
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*devmajor = 0;
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*devminor = 0;
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if (stat(devpath, &st) < 0) {
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slog("failed to stat device file '%s': %s", devpath, strerror(errno));
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return -1;
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}
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if (S_ISDIR(st.st_mode)) {
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/* It is bind mount */
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return -2;
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}
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if (S_ISBLK(st.st_mode)) {
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*devmajor = major(st.st_rdev);
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*devminor = minor(st.st_rdev);
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return 0;
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}
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return -1;
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}
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static bool build_fs_mount_list_from_mtab(FsMountList *mounts, Error **errp)
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{
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struct mntent *ment;
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FsMount *mount;
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char const *mtab = "/proc/self/mounts";
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FILE *fp;
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unsigned int devmajor, devminor;
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fp = setmntent(mtab, "r");
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if (!fp) {
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error_setg(errp, "failed to open mtab file: '%s'", mtab);
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return false;
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}
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while ((ment = getmntent(fp))) {
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/*
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* An entry which device name doesn't start with a '/' is
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* either a dummy file system or a network file system.
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* Add special handling for smbfs and cifs as is done by
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* coreutils as well.
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*/
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if ((ment->mnt_fsname[0] != '/') ||
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(strcmp(ment->mnt_type, "smbfs") == 0) ||
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(strcmp(ment->mnt_type, "cifs") == 0)) {
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continue;
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}
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if (dev_major_minor(ment->mnt_fsname, &devmajor, &devminor) == -2) {
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/* Skip bind mounts */
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continue;
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}
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mount = g_new0(FsMount, 1);
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mount->dirname = g_strdup(ment->mnt_dir);
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mount->devtype = g_strdup(ment->mnt_type);
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mount->devmajor = devmajor;
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mount->devminor = devminor;
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QTAILQ_INSERT_TAIL(mounts, mount, next);
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}
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endmntent(fp);
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return true;
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}
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static void decode_mntname(char *name, int len)
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{
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int i, j = 0;
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for (i = 0; i <= len; i++) {
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if (name[i] != '\\') {
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name[j++] = name[i];
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} else if (name[i + 1] == '\\') {
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name[j++] = '\\';
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i++;
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} else if (name[i + 1] >= '0' && name[i + 1] <= '3' &&
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name[i + 2] >= '0' && name[i + 2] <= '7' &&
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name[i + 3] >= '0' && name[i + 3] <= '7') {
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name[j++] = (name[i + 1] - '0') * 64 +
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(name[i + 2] - '0') * 8 +
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(name[i + 3] - '0');
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i += 3;
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} else {
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name[j++] = name[i];
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}
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}
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}
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/*
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* Walk the mount table and build a list of local file systems
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*/
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bool build_fs_mount_list(FsMountList *mounts, Error **errp)
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{
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FsMount *mount;
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char const *mountinfo = "/proc/self/mountinfo";
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FILE *fp;
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char *line = NULL, *dash;
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size_t n;
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char check;
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unsigned int devmajor, devminor;
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int ret, dir_s, dir_e, type_s, type_e, dev_s, dev_e;
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fp = fopen(mountinfo, "r");
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if (!fp) {
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return build_fs_mount_list_from_mtab(mounts, errp);
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}
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while (getline(&line, &n, fp) != -1) {
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ret = sscanf(line, "%*u %*u %u:%u %*s %n%*s%n%c",
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&devmajor, &devminor, &dir_s, &dir_e, &check);
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if (ret < 3) {
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continue;
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}
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dash = strstr(line + dir_e, " - ");
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if (!dash) {
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continue;
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}
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ret = sscanf(dash, " - %n%*s%n %n%*s%n%c",
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&type_s, &type_e, &dev_s, &dev_e, &check);
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if (ret < 1) {
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continue;
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}
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line[dir_e] = 0;
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dash[type_e] = 0;
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dash[dev_e] = 0;
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decode_mntname(line + dir_s, dir_e - dir_s);
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decode_mntname(dash + dev_s, dev_e - dev_s);
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if (devmajor == 0) {
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/* btrfs reports major number = 0 */
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if (strcmp("btrfs", dash + type_s) != 0 ||
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dev_major_minor(dash + dev_s, &devmajor, &devminor) < 0) {
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continue;
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}
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}
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mount = g_new0(FsMount, 1);
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mount->dirname = g_strdup(line + dir_s);
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mount->devtype = g_strdup(dash + type_s);
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mount->devmajor = devmajor;
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mount->devminor = devminor;
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QTAILQ_INSERT_TAIL(mounts, mount, next);
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}
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free(line);
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fclose(fp);
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return true;
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}
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#endif /* CONFIG_FSFREEZE || CONFIG_FSTRIM */
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#ifdef CONFIG_FSFREEZE
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/*
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* Walk list of mounted file systems in the guest, and freeze the ones which
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* are real local file systems.
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*/
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int64_t qmp_guest_fsfreeze_do_freeze_list(bool has_mountpoints,
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strList *mountpoints,
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FsMountList mounts,
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Error **errp)
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{
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struct FsMount *mount;
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strList *list;
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int fd, ret, i = 0;
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QTAILQ_FOREACH_REVERSE(mount, &mounts, next) {
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/* To issue fsfreeze in the reverse order of mounts, check if the
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* mount is listed in the list here */
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if (has_mountpoints) {
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for (list = mountpoints; list; list = list->next) {
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if (strcmp(list->value, mount->dirname) == 0) {
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break;
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}
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}
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if (!list) {
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continue;
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}
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}
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fd = qga_open_cloexec(mount->dirname, O_RDONLY, 0);
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if (fd == -1) {
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error_setg_errno(errp, errno, "failed to open %s", mount->dirname);
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return -1;
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}
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/* we try to cull filesystems we know won't work in advance, but other
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* filesystems may not implement fsfreeze for less obvious reasons.
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* these will report EOPNOTSUPP. we simply ignore these when tallying
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* the number of frozen filesystems.
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* if a filesystem is mounted more than once (aka bind mount) a
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* consecutive attempt to freeze an already frozen filesystem will
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* return EBUSY.
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*
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* any other error means a failure to freeze a filesystem we
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* expect to be freezable, so return an error in those cases
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* and return system to thawed state.
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*/
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ret = ioctl(fd, FIFREEZE);
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if (ret == -1) {
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if (errno != EOPNOTSUPP && errno != EBUSY) {
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error_setg_errno(errp, errno, "failed to freeze %s",
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mount->dirname);
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close(fd);
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return -1;
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}
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} else {
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i++;
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}
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close(fd);
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}
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return i;
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}
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int qmp_guest_fsfreeze_do_thaw(Error **errp)
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{
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int ret;
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FsMountList mounts;
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FsMount *mount;
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int fd, i = 0, logged;
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Error *local_err = NULL;
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QTAILQ_INIT(&mounts);
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if (!build_fs_mount_list(&mounts, &local_err)) {
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error_propagate(errp, local_err);
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return -1;
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}
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QTAILQ_FOREACH(mount, &mounts, next) {
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logged = false;
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fd = qga_open_cloexec(mount->dirname, O_RDONLY, 0);
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if (fd == -1) {
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continue;
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}
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/* we have no way of knowing whether a filesystem was actually unfrozen
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* as a result of a successful call to FITHAW, only that if an error
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* was returned the filesystem was *not* unfrozen by that particular
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* call.
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*
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* since multiple preceding FIFREEZEs require multiple calls to FITHAW
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* to unfreeze, continuing issuing FITHAW until an error is returned,
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* in which case either the filesystem is in an unfreezable state, or,
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* more likely, it was thawed previously (and remains so afterward).
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*
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* also, since the most recent successful call is the one that did
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* the actual unfreeze, we can use this to provide an accurate count
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* of the number of filesystems unfrozen by guest-fsfreeze-thaw, which
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* may * be useful for determining whether a filesystem was unfrozen
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* during the freeze/thaw phase by a process other than qemu-ga.
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*/
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do {
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ret = ioctl(fd, FITHAW);
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if (ret == 0 && !logged) {
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i++;
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logged = true;
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}
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} while (ret == 0);
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close(fd);
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}
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free_fs_mount_list(&mounts);
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return i;
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}
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#endif /* CONFIG_FSFREEZE */
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