qga: Add UFS freeze/thaw support for FreeBSD

UFS supports FS freezing through ioctl UFSSUSPEND on /dev/ufssuspend.
Frozen FS can be thawed by closing /dev/ufssuspend file descriptior.

Use getmntinfo to get a list of mounted FS.

Reviewed-by: Konstantin Kostiuk <kkostiuk@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>
Signed-off-by: Konstantin Kostiuk <kkostiuk@redhat.com>

qga/commands-bsd.c

@@ -0,0 +1,169 @@
+/*
+ * QEMU Guest Agent BSD-specific command implementations
+ *
+ * Copyright (c) Virtuozzo International GmbH.
+ *
+ * Authors:
+ *  Alexander Ivanov  <alexander.ivanov@virtuozzo.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 "qga-qapi-commands.h"
+#include "qapi/qmp/qerror.h"
+#include "qapi/error.h"
+#include "qemu/queue.h"
+#include "commands-common.h"
+#include <sys/ioctl.h>
+#include <sys/param.h>
+#include <sys/ucred.h>
+#include <sys/mount.h>
+#include <paths.h>
+
+#if defined(CONFIG_FSFREEZE) || defined(CONFIG_FSTRIM)
+bool build_fs_mount_list(FsMountList *mounts, Error **errp)
+{
+    FsMount *mount;
+    struct statfs *mntbuf, *mntp;
+    struct stat statbuf;
+    int i, count, ret;
+
+    count = getmntinfo(&mntbuf, MNT_NOWAIT);
+    if (count == 0) {
+        error_setg_errno(errp, errno, "getmntinfo failed");
+        return false;
+    }
+
+    for (i = 0; i < count; i++) {
+        mntp = &mntbuf[i];
+        ret = stat(mntp->f_mntonname, &statbuf);
+        if (ret != 0) {
+            error_setg_errno(errp, errno, "stat failed on %s",
+                             mntp->f_mntonname);
+            return false;
+        }
+
+        mount = g_new0(FsMount, 1);
+
+        mount->dirname = g_strdup(mntp->f_mntonname);
+        mount->devtype = g_strdup(mntp->f_fstypename);
+        mount->devmajor = major(mount->dev);
+        mount->devminor = minor(mount->dev);
+        mount->fsid = mntp->f_fsid;
+        mount->dev = statbuf.st_dev;
+
+        QTAILQ_INSERT_TAIL(mounts, mount, next);
+    }
+    return true;
+}
+#endif /* CONFIG_FSFREEZE || CONFIG_FSTRIM */
+
+#if defined(CONFIG_FSFREEZE)
+static int ufssuspend_fd = -1;
+static int ufssuspend_cnt;
+
+int64_t qmp_guest_fsfreeze_do_freeze_list(bool has_mountpoints,
+                                          strList *mountpoints,
+                                          FsMountList mounts,
+                                          Error **errp)
+{
+    int ret;
+    strList *list;
+    struct FsMount *mount;
+
+    if (ufssuspend_fd != -1) {
+        error_setg(errp, "filesystems have already frozen");
+        return -1;
+    }
+
+    ufssuspend_cnt = 0;
+    ufssuspend_fd = qemu_open(_PATH_UFSSUSPEND, O_RDWR, errp);
+    if (ufssuspend_fd == -1) {
+        return -1;
+    }
+
+    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 (g_str_equal(list->value, mount->dirname)) {
+                    break;
+                }
+            }
+            if (!list) {
+                continue;
+            }
+        }
+
+        /* Only UFS supports suspend */
+        if (!g_str_equal(mount->devtype, "ufs")) {
+            continue;
+        }
+
+        ret = ioctl(ufssuspend_fd, UFSSUSPEND, &mount->fsid);
+        if (ret == -1) {
+            /*
+             * ioctl returns EBUSY for all the FS except the first one
+             * that was suspended
+             */
+            if (errno == EBUSY) {
+                continue;
+            }
+            error_setg_errno(errp, errno, "failed to freeze %s",
+                             mount->dirname);
+            goto error;
+        }
+        ufssuspend_cnt++;
+    }
+    return ufssuspend_cnt;
+error:
+    close(ufssuspend_fd);
+    ufssuspend_fd = -1;
+    return -1;
+
+}
+
+/*
+ * We don't need to call UFSRESUME ioctl because all the frozen FS
+ * are thawed on /dev/ufssuspend closing.
+ */
+int qmp_guest_fsfreeze_do_thaw(Error **errp)
+{
+    int ret = ufssuspend_cnt;
+    ufssuspend_cnt = 0;
+    if (ufssuspend_fd != -1) {
+        close(ufssuspend_fd);
+        ufssuspend_fd = -1;
+    }
+    return ret;
+}
+
+GuestFilesystemInfoList *qmp_guest_get_fsinfo(Error **errp)
+{
+    error_setg(errp, QERR_UNSUPPORTED);
+    return NULL;
+}
+
+GuestDiskInfoList *qmp_guest_get_disks(Error **errp)
+{
+    error_setg(errp, QERR_UNSUPPORTED);
+    return NULL;
+}
+
+GuestDiskStatsInfoList *qmp_guest_get_diskstats(Error **errp)
+{
+    error_setg(errp, QERR_UNSUPPORTED);
+    return NULL;
+}
+
+GuestCpuStatsList *qmp_guest_get_cpustats(Error **errp)
+{
+    error_setg(errp, QERR_UNSUPPORTED);
+    return NULL;
+}
+#endif /* CONFIG_FSFREEZE */