[v3,2/7] qga: Move Linux-specific FS freeze/thaw code to a separate file

In the next patches we are going to add FreeBSD support for QEMU Guest
Agent. In the result, code in commands-posix.c will be too cumbersome.

Move Linux-specific FS freeze/thaw code to a separate file commands-linux.c
keeping common POSIX code in commands-posix.c.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
---
 qga/commands-common.h |  35 +++++
 qga/commands-linux.c  | 286 +++++++++++++++++++++++++++++++++++++++++
 qga/commands-posix.c  | 289 +++---------------------------------------
 qga/meson.build       |   3 +
 4 files changed, 340 insertions(+), 273 deletions(-)
 create mode 100644 qga/commands-linux.c

Reviewed-by: Konstantin Kostiuk <kkostiuk@redhat.com>

On Mon, Oct 3, 2022 at 12:39 PM Alexander Ivanov <
alexander.ivanov@virtuozzo.com> wrote:

> In the next patches we are going to add FreeBSD support for QEMU Guest
> Agent. In the result, code in commands-posix.c will be too cumbersome.
>
> Move Linux-specific FS freeze/thaw code to a separate file commands-linux.c
> keeping common POSIX code in commands-posix.c.
>
> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
> ---
>  qga/commands-common.h |  35 +++++
>  qga/commands-linux.c  | 286 +++++++++++++++++++++++++++++++++++++++++
>  qga/commands-posix.c  | 289 +++---------------------------------------
>  qga/meson.build       |   3 +
>  4 files changed, 340 insertions(+), 273 deletions(-)
>  create mode 100644 qga/commands-linux.c
>
> diff --git a/qga/commands-common.h b/qga/commands-common.h
> index d0e4a9696f..181fc330aa 100644
> --- a/qga/commands-common.h
> +++ b/qga/commands-common.h
> @@ -10,6 +10,40 @@
>  #define QGA_COMMANDS_COMMON_H
>
>  #include "qga-qapi-types.h"
> +#include "guest-agent-core.h"
> +#include "qemu/queue.h"
> +
> +#if defined(__linux__)
> +#include <linux/fs.h>
> +#ifdef FIFREEZE
> +#define CONFIG_FSFREEZE
> +#endif
> +#ifdef FITRIM
> +#define CONFIG_FSTRIM
> +#endif
> +#endif /* __linux__ */
> +
> +#if defined(CONFIG_FSFREEZE) || defined(CONFIG_FSTRIM)
> +typedef struct FsMount {
> +    char *dirname;
> +    char *devtype;
> +    unsigned int devmajor, devminor;
> +    QTAILQ_ENTRY(FsMount) next;
> +} FsMount;
> +
> +typedef QTAILQ_HEAD(FsMountList, FsMount) FsMountList;
> +
> +bool build_fs_mount_list(FsMountList *mounts, Error **errp);
> +void free_fs_mount_list(FsMountList *mounts);
> +#endif /* CONFIG_FSFREEZE || CONFIG_FSTRIM */
> +
> +#if defined(CONFIG_FSFREEZE)
> +int64_t qmp_guest_fsfreeze_do_freeze_list(bool has_mountpoints,
> +                                          strList *mountpoints,
> +                                          FsMountList mounts,
> +                                          Error **errp);
> +int qmp_guest_fsfreeze_do_thaw(Error **errp);
> +#endif /* CONFIG_FSFREEZE */
>
>  typedef struct GuestFileHandle GuestFileHandle;
>
> @@ -29,4 +63,5 @@ GuestFileRead *guest_file_read_unsafe(GuestFileHandle
> *gfh,
>   */
>  char *qga_get_host_name(Error **errp);
>
> +void ga_wait_child(pid_t pid, int *status, Error **errp);
>  #endif
> 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 */
> diff --git a/qga/commands-posix.c b/qga/commands-posix.c
> index 16d67e9f6d..9574b83c92 100644
> --- a/qga/commands-posix.c
> +++ b/qga/commands-posix.c
> @@ -16,11 +16,9 @@
>  #include <sys/utsname.h>
>  #include <sys/wait.h>
>  #include <dirent.h>
> -#include "guest-agent-core.h"
>  #include "qga-qapi-commands.h"
>  #include "qapi/error.h"
>  #include "qapi/qmp/qerror.h"
> -#include "qemu/queue.h"
>  #include "qemu/host-utils.h"
>  #include "qemu/sockets.h"
>  #include "qemu/base64.h"
> @@ -70,7 +68,7 @@
>  #endif
>  #endif
>
> -static void ga_wait_child(pid_t pid, int *status, Error **errp)
> +void ga_wait_child(pid_t pid, int *status, Error **errp)
>  {
>      pid_t rpid;
>
> @@ -629,16 +627,7 @@ void qmp_guest_file_flush(int64_t handle, Error
> **errp)
>  #if defined(__linux__)
>
>  #if defined(CONFIG_FSFREEZE) || defined(CONFIG_FSTRIM)
> -typedef struct FsMount {
> -    char *dirname;
> -    char *devtype;
> -    unsigned int devmajor, devminor;
> -    QTAILQ_ENTRY(FsMount) next;
> -} FsMount;
> -
> -typedef QTAILQ_HEAD(FsMountList, FsMount) FsMountList;
> -
> -static void free_fs_mount_list(FsMountList *mounts)
> +void free_fs_mount_list(FsMountList *mounts)
>  {
>       FsMount *mount, *temp;
>
> @@ -653,157 +642,6 @@ static void free_fs_mount_list(FsMountList *mounts)
>           g_free(mount);
>       }
>  }
> -
> -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;
> -}
> -
> -/*
> - * Walk the mount table and build a list of local file systems
> - */
> -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];
> -        }
> -    }
> -}
> -
> -static 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
>
>  #if defined(CONFIG_FSFREEZE)
> @@ -1708,20 +1546,13 @@ int64_t qmp_guest_fsfreeze_freeze(Error **errp)
>      return qmp_guest_fsfreeze_freeze_list(false, NULL, errp);
>  }
>
> -/*
> - * Walk list of mounted file systems in the guest, and freeze the ones
> which
> - * are real local file systems.
> - */
>  int64_t qmp_guest_fsfreeze_freeze_list(bool has_mountpoints,
>                                         strList *mountpoints,
>                                         Error **errp)
>  {
> -    int ret = 0, i = 0;
> -    strList *list;
> +    int ret;
>      FsMountList mounts;
> -    struct FsMount *mount;
>      Error *local_err = NULL;
> -    int fd;
>
>      slog("guest-fsfreeze called");
>
> @@ -1740,122 +1571,34 @@ int64_t qmp_guest_fsfreeze_freeze_list(bool
> has_mountpoints,
>      /* cannot risk guest agent blocking itself on a write in this state */
>      ga_set_frozen(ga_state);
>
> -    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);
> -            goto error;
> -        }
> -
> -        /* 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);
> -                goto error;
> -            }
> -        } else {
> -            i++;
> -        }
> -        close(fd);
> -    }
> +    ret = qmp_guest_fsfreeze_do_freeze_list(has_mountpoints, mountpoints,
> +                                            mounts, errp);
>
>      free_fs_mount_list(&mounts);
>      /* We may not issue any FIFREEZE here.
>       * Just unset ga_state here and ready for the next call.
>       */
> -    if (i == 0) {
> +    if (ret == 0) {
>          ga_unset_frozen(ga_state);
> +    } else if (ret < 0) {
> +        qmp_guest_fsfreeze_thaw(NULL);
>      }
> -    return i;
> -
> -error:
> -    free_fs_mount_list(&mounts);
> -    qmp_guest_fsfreeze_thaw(NULL);
> -    return 0;
> +    return ret;
>  }
>
> -/*
> - * Walk list of frozen file systems in the guest, and thaw them.
> - */
>  int64_t qmp_guest_fsfreeze_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 0;
> +    ret = qmp_guest_fsfreeze_do_thaw(errp);
> +    if (ret >= 0) {
> +        ga_unset_frozen(ga_state);
> +        execute_fsfreeze_hook(FSFREEZE_HOOK_THAW, errp);
> +    } else {
> +        ret = 0;
>      }
>
> -    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);
> -    }
> -
> -    ga_unset_frozen(ga_state);
> -    free_fs_mount_list(&mounts);
> -
> -    execute_fsfreeze_hook(FSFREEZE_HOOK_THAW, errp);
> -
> -    return i;
> +    return ret;
>  }
>
>  static void guest_fsfreeze_cleanup(void)
> diff --git a/qga/meson.build b/qga/meson.build
> index 65c1e93846..409f49a000 100644
> --- a/qga/meson.build
> +++ b/qga/meson.build
> @@ -72,6 +72,9 @@ qga_ss.add(when: 'CONFIG_POSIX', if_true: files(
>    'commands-posix.c',
>    'commands-posix-ssh.c',
>  ))
> +qga_ss.add(when: 'CONFIG_LINUX', if_true: files(
> +  'commands-linux.c',
> +))
>  qga_ss.add(when: 'CONFIG_WIN32', if_true: files(
>    'channel-win32.c',
>    'commands-win32.c',
> --
> 2.34.1
>
>