diff options
Diffstat (limited to 'qga/commands-linux.c')
| -rw-r--r-- | qga/commands-linux.c | 286 |
1 files changed, 286 insertions, 0 deletions
diff --git a/qga/commands-linux.c b/qga/commands-linux.c new file mode 100644 index 0000000000..214e408fcd --- /dev/null +++ b/qga/commands-linux.c @@ -0,0 +1,286 @@ +/* + * QEMU Guest Agent Linux-specific command implementations + * + * Copyright IBM Corp. 2011 + * + * Authors: + * Michael Roth <mdroth@linux.vnet.ibm.com> + * Michal Privoznik <mprivozn@redhat.com> + * + * This work is licensed under the terms of the GNU GPL, version 2 or later. + * See the COPYING file in the top-level directory. + */ + +#include "qemu/osdep.h" +#include "qapi/error.h" +#include "commands-common.h" +#include "cutils.h" +#include <mntent.h> +#include <sys/ioctl.h> + +#if defined(CONFIG_FSFREEZE) || defined(CONFIG_FSTRIM) +static int dev_major_minor(const char *devpath, + unsigned int *devmajor, unsigned int *devminor) +{ + struct stat st; + + *devmajor = 0; + *devminor = 0; + + if (stat(devpath, &st) < 0) { + slog("failed to stat device file '%s': %s", devpath, strerror(errno)); + return -1; + } + if (S_ISDIR(st.st_mode)) { + /* It is bind mount */ + return -2; + } + if (S_ISBLK(st.st_mode)) { + *devmajor = major(st.st_rdev); + *devminor = minor(st.st_rdev); + return 0; + } + return -1; +} + +static bool build_fs_mount_list_from_mtab(FsMountList *mounts, Error **errp) +{ + struct mntent *ment; + FsMount *mount; + char const *mtab = "/proc/self/mounts"; + FILE *fp; + unsigned int devmajor, devminor; + + fp = setmntent(mtab, "r"); + if (!fp) { + error_setg(errp, "failed to open mtab file: '%s'", mtab); + return false; + } + + while ((ment = getmntent(fp))) { + /* + * An entry which device name doesn't start with a '/' is + * either a dummy file system or a network file system. + * Add special handling for smbfs and cifs as is done by + * coreutils as well. + */ + if ((ment->mnt_fsname[0] != '/') || + (strcmp(ment->mnt_type, "smbfs") == 0) || + (strcmp(ment->mnt_type, "cifs") == 0)) { + continue; + } + if (dev_major_minor(ment->mnt_fsname, &devmajor, &devminor) == -2) { + /* Skip bind mounts */ + continue; + } + + mount = g_new0(FsMount, 1); + mount->dirname = g_strdup(ment->mnt_dir); + mount->devtype = g_strdup(ment->mnt_type); + mount->devmajor = devmajor; + mount->devminor = devminor; + + QTAILQ_INSERT_TAIL(mounts, mount, next); + } + + endmntent(fp); + return true; +} + +static void decode_mntname(char *name, int len) +{ + int i, j = 0; + for (i = 0; i <= len; i++) { + if (name[i] != '\\') { + name[j++] = name[i]; + } else if (name[i + 1] == '\\') { + name[j++] = '\\'; + i++; + } else if (name[i + 1] >= '0' && name[i + 1] <= '3' && + name[i + 2] >= '0' && name[i + 2] <= '7' && + name[i + 3] >= '0' && name[i + 3] <= '7') { + name[j++] = (name[i + 1] - '0') * 64 + + (name[i + 2] - '0') * 8 + + (name[i + 3] - '0'); + i += 3; + } else { + name[j++] = name[i]; + } + } +} + +/* + * Walk the mount table and build a list of local file systems + */ +bool build_fs_mount_list(FsMountList *mounts, Error **errp) +{ + FsMount *mount; + char const *mountinfo = "/proc/self/mountinfo"; + FILE *fp; + char *line = NULL, *dash; + size_t n; + char check; + unsigned int devmajor, devminor; + int ret, dir_s, dir_e, type_s, type_e, dev_s, dev_e; + + fp = fopen(mountinfo, "r"); + if (!fp) { + return build_fs_mount_list_from_mtab(mounts, errp); + } + + while (getline(&line, &n, fp) != -1) { + ret = sscanf(line, "%*u %*u %u:%u %*s %n%*s%n%c", + &devmajor, &devminor, &dir_s, &dir_e, &check); + if (ret < 3) { + continue; + } + dash = strstr(line + dir_e, " - "); + if (!dash) { + continue; + } + ret = sscanf(dash, " - %n%*s%n %n%*s%n%c", + &type_s, &type_e, &dev_s, &dev_e, &check); + if (ret < 1) { + continue; + } + line[dir_e] = 0; + dash[type_e] = 0; + dash[dev_e] = 0; + decode_mntname(line + dir_s, dir_e - dir_s); + decode_mntname(dash + dev_s, dev_e - dev_s); + if (devmajor == 0) { + /* btrfs reports major number = 0 */ + if (strcmp("btrfs", dash + type_s) != 0 || + dev_major_minor(dash + dev_s, &devmajor, &devminor) < 0) { + continue; + } + } + + mount = g_new0(FsMount, 1); + mount->dirname = g_strdup(line + dir_s); + mount->devtype = g_strdup(dash + type_s); + mount->devmajor = devmajor; + mount->devminor = devminor; + + QTAILQ_INSERT_TAIL(mounts, mount, next); + } + free(line); + + fclose(fp); + return true; +} +#endif /* CONFIG_FSFREEZE || CONFIG_FSTRIM */ + +#ifdef CONFIG_FSFREEZE +/* + * Walk list of mounted file systems in the guest, and freeze the ones which + * are real local file systems. + */ +int64_t qmp_guest_fsfreeze_do_freeze_list(bool has_mountpoints, + strList *mountpoints, + FsMountList mounts, + Error **errp) +{ + struct FsMount *mount; + strList *list; + int fd, ret, i = 0; + + QTAILQ_FOREACH_REVERSE(mount, &mounts, next) { + /* To issue fsfreeze in the reverse order of mounts, check if the + * mount is listed in the list here */ + if (has_mountpoints) { + for (list = mountpoints; list; list = list->next) { + if (strcmp(list->value, mount->dirname) == 0) { + break; + } + } + if (!list) { + continue; + } + } + + fd = qga_open_cloexec(mount->dirname, O_RDONLY, 0); + if (fd == -1) { + error_setg_errno(errp, errno, "failed to open %s", mount->dirname); + return -1; + } + + /* we try to cull filesystems we know won't work in advance, but other + * filesystems may not implement fsfreeze for less obvious reasons. + * these will report EOPNOTSUPP. we simply ignore these when tallying + * the number of frozen filesystems. + * if a filesystem is mounted more than once (aka bind mount) a + * consecutive attempt to freeze an already frozen filesystem will + * return EBUSY. + * + * any other error means a failure to freeze a filesystem we + * expect to be freezable, so return an error in those cases + * and return system to thawed state. + */ + ret = ioctl(fd, FIFREEZE); + if (ret == -1) { + if (errno != EOPNOTSUPP && errno != EBUSY) { + error_setg_errno(errp, errno, "failed to freeze %s", + mount->dirname); + close(fd); + return -1; + } + } else { + i++; + } + close(fd); + } + return i; +} + +int qmp_guest_fsfreeze_do_thaw(Error **errp) +{ + int ret; + FsMountList mounts; + FsMount *mount; + int fd, i = 0, logged; + Error *local_err = NULL; + + QTAILQ_INIT(&mounts); + if (!build_fs_mount_list(&mounts, &local_err)) { + error_propagate(errp, local_err); + return -1; + } + + QTAILQ_FOREACH(mount, &mounts, next) { + logged = false; + fd = qga_open_cloexec(mount->dirname, O_RDONLY, 0); + if (fd == -1) { + continue; + } + /* we have no way of knowing whether a filesystem was actually unfrozen + * as a result of a successful call to FITHAW, only that if an error + * was returned the filesystem was *not* unfrozen by that particular + * call. + * + * since multiple preceding FIFREEZEs require multiple calls to FITHAW + * to unfreeze, continuing issuing FITHAW until an error is returned, + * in which case either the filesystem is in an unfreezable state, or, + * more likely, it was thawed previously (and remains so afterward). + * + * also, since the most recent successful call is the one that did + * the actual unfreeze, we can use this to provide an accurate count + * of the number of filesystems unfrozen by guest-fsfreeze-thaw, which + * may * be useful for determining whether a filesystem was unfrozen + * during the freeze/thaw phase by a process other than qemu-ga. + */ + do { + ret = ioctl(fd, FITHAW); + if (ret == 0 && !logged) { + i++; + logged = true; + } + } while (ret == 0); + close(fd); + } + + free_fs_mount_list(&mounts); + + return i; +} +#endif /* CONFIG_FSFREEZE */ |