src/core/umount.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   This file is part of systemd.
   4
   5   Copyright 2010 ProFUSION embedded systems
   6 ***/
   7
   8 #include <errno.h>
   9 #include <fcntl.h>
  10 #include <linux/loop.h>
  11 #include <string.h>
  12 #include <sys/mount.h>
  13 #include <sys/swap.h>
  14
  15 /* This needs to be after sys/mount.h :( */
  16 #include <libmount.h>
  17
  18 #include "libudev.h"
  19
  20 #include "alloc-util.h"
  21 #include "blockdev-util.h"
  22 #include "def.h"
  23 #include "escape.h"
  24 #include "fd-util.h"
  25 #include "fstab-util.h"
  26 #include "linux-3.13/dm-ioctl.h"
  27 #include "mount-setup.h"
  28 #include "mount-util.h"
  29 #include "path-util.h"
  30 #include "process-util.h"
  31 #include "signal-util.h"
  32 #include "string-util.h"
  33 #include "udev-util.h"
  34 #include "umount.h"
  35 #include "util.h"
  36 #include "virt.h"
  37
  38 DEFINE_TRIVIAL_CLEANUP_FUNC(struct libmnt_table*, mnt_free_table);
  39 DEFINE_TRIVIAL_CLEANUP_FUNC(struct libmnt_iter*, mnt_free_iter);
  40
  41 static void mount_point_free(MountPoint **head, MountPoint *m) {
  42         assert(head);
  43         assert(m);
  44
  45         LIST_REMOVE(mount_point, *head, m);
  46
  47         free(m->path);
  48         free(m->remount_options);
  49         free(m);
  50 }
  51
  52 void mount_points_list_free(MountPoint **head) {
  53         assert(head);
  54
  55         while (*head)
  56                 mount_point_free(head, *head);
  57 }
  58
  59 int mount_points_list_get(const char *mountinfo, MountPoint **head) {
  60         _cleanup_(mnt_free_tablep) struct libmnt_table *t = NULL;
  61         _cleanup_(mnt_free_iterp) struct libmnt_iter *i = NULL;
  62         int r;
  63
  64         assert(head);
  65
  66         t = mnt_new_table();
  67         i = mnt_new_iter(MNT_ITER_FORWARD);
  68         if (!t || !i)
  69                 return log_oom();
  70
  71         r = mnt_table_parse_mtab(t, mountinfo);
  72         if (r < 0)
  73                 return log_error_errno(r, "Failed to parse %s: %m", mountinfo);
  74
  75         for (;;) {
  76                 struct libmnt_fs *fs;
  77                 const char *path, *options, *fstype;
  78                 _cleanup_free_ char *p = NULL;
  79                 unsigned long remount_flags = 0u;
  80                 _cleanup_free_ char *remount_options = NULL;
  81                 bool try_remount_ro;
  82                 MountPoint *m;
  83
  84                 r = mnt_table_next_fs(t, i, &fs);
  85                 if (r == 1)
  86                         break;
  87                 if (r < 0)
  88                         return log_error_errno(r, "Failed to get next entry from %s: %m", mountinfo);
  89
  90                 path = mnt_fs_get_target(fs);
  91                 if (!path)
  92                         continue;
  93
  94                 if (cunescape(path, UNESCAPE_RELAX, &p) < 0)
  95                         return log_oom();
  96
  97                 options = mnt_fs_get_options(fs);
  98                 fstype = mnt_fs_get_fstype(fs);
  99
 100                 /* Ignore mount points we can't unmount because they
 101                  * are API or because we are keeping them open (like
 102                  * /dev/console). Also, ignore all mounts below API
 103                  * file systems, since they are likely virtual too,
 104                  * and hence not worth spending time on. Also, in
 105                  * unprivileged containers we might lack the rights to
 106                  * unmount these things, hence don't bother. */
 107                 if (mount_point_is_api(p) ||
 108                     mount_point_ignore(p) ||
 109                     path_startswith(p, "/dev") ||
 110                     path_startswith(p, "/sys") ||
 111                     path_startswith(p, "/proc"))
 112                         continue;
 113
 114                 /* If we are in a container, don't attempt to
 115                  * read-only mount anything as that brings no real
 116                  * benefits, but might confuse the host, as we remount
 117                  * the superblock here, not the bind mount.
 118                  *
 119                  * If the filesystem is a network fs, also skip the
 120                  * remount. It brings no value (we cannot leave
 121                  * a "dirty fs") and could hang if the network is down.
 122                  * Note that umount2() is more careful and will not
 123                  * hang because of the network being down. */
 124                 try_remount_ro = detect_container() <= 0 &&
 125                                  !fstype_is_network(fstype) &&
 126                                  !fstype_is_api_vfs(fstype) &&
 127                                  !fstype_is_ro(fstype) &&
 128                                  !fstab_test_yes_no_option(options, "ro\0rw\0");
 129
 130                 if (try_remount_ro) {
 131                         /* mount(2) states that mount flags and options need to be exactly the same
 132                          * as they were when the filesystem was mounted, except for the desired
 133                          * changes. So we reconstruct both here and adjust them for the later
 134                          * remount call too. */
 135
 136                         r = mnt_fs_get_propagation(fs, &remount_flags);
 137                         if (r < 0) {
 138                                 log_warning_errno(r, "mnt_fs_get_propagation() failed for %s, ignoring: %m", path);
 139                                 continue;
 140                         }
 141
 142                         r = mount_option_mangle(options, remount_flags, &remount_flags, &remount_options);
 143                         if (r < 0) {
 144                                 log_warning_errno(r, "mount_option_mangle failed for %s, ignoring: %m", path);
 145                                 continue;
 146                         }
 147
 148                         /* MS_BIND is special. If it is provided it will only make the mount-point
 149                          * read-only. If left out, the super block itself is remounted, which we want. */
 150                         remount_flags = (remount_flags|MS_REMOUNT|MS_RDONLY) & ~MS_BIND;
 151                 }
 152
 153                 m = new0(MountPoint, 1);
 154                 if (!m)
 155                         return log_oom();
 156
 157                 free_and_replace(m->path, p);
 158                 free_and_replace(m->remount_options, remount_options);
 159                 m->remount_flags = remount_flags;
 160                 m->try_remount_ro = try_remount_ro;
 161
 162                 LIST_PREPEND(mount_point, *head, m);
 163         }
 164
 165         return 0;
 166 }
 167
 168 int swap_list_get(const char *swaps, MountPoint **head) {
 169         _cleanup_(mnt_free_tablep) struct libmnt_table *t = NULL;
 170         _cleanup_(mnt_free_iterp) struct libmnt_iter *i = NULL;
 171         int r;
 172
 173         assert(head);
 174
 175         t = mnt_new_table();
 176         i = mnt_new_iter(MNT_ITER_FORWARD);
 177         if (!t || !i)
 178                 return log_oom();
 179
 180         r = mnt_table_parse_swaps(t, swaps);
 181         if (r < 0)
 182                 return log_error_errno(r, "Failed to parse %s: %m", swaps);
 183
 184         for (;;) {
 185                 struct libmnt_fs *fs;
 186
 187                 MountPoint *swap;
 188                 const char *source;
 189                 _cleanup_free_ char *d = NULL;
 190
 191                 r = mnt_table_next_fs(t, i, &fs);
 192                 if (r == 1)
 193                         break;
 194                 if (r < 0)
 195                         return log_error_errno(r, "Failed to get next entry from %s: %m", swaps);
 196
 197                 source = mnt_fs_get_source(fs);
 198                 if (!source)
 199                         continue;
 200
 201                 r = cunescape(source, UNESCAPE_RELAX, &d);
 202                 if (r < 0)
 203                         return r;
 204
 205                 swap = new0(MountPoint, 1);
 206                 if (!swap)
 207                         return -ENOMEM;
 208
 209                 free_and_replace(swap->path, d);
 210                 LIST_PREPEND(mount_point, *head, swap);
 211         }
 212
 213         return 0;
 214 }
 215
 216 static int loopback_list_get(MountPoint **head) {
 217         _cleanup_(udev_enumerate_unrefp) struct udev_enumerate *e = NULL;
 218         struct udev_list_entry *item = NULL, *first = NULL;
 219         _cleanup_(udev_unrefp) struct udev *udev = NULL;
 220         int r;
 221
 222         assert(head);
 223
 224         udev = udev_new();
 225         if (!udev)
 226                 return -ENOMEM;
 227
 228         e = udev_enumerate_new(udev);
 229         if (!e)
 230                 return -ENOMEM;
 231
 232         r = udev_enumerate_add_match_subsystem(e, "block");
 233         if (r < 0)
 234                 return r;
 235
 236         r = udev_enumerate_add_match_sysname(e, "loop*");
 237         if (r < 0)
 238                 return r;
 239
 240         r = udev_enumerate_add_match_sysattr(e, "loop/backing_file", NULL);
 241         if (r < 0)
 242                 return r;
 243
 244         r = udev_enumerate_scan_devices(e);
 245         if (r < 0)
 246                 return r;
 247
 248         first = udev_enumerate_get_list_entry(e);
 249         udev_list_entry_foreach(item, first) {
 250                 _cleanup_(udev_device_unrefp) struct udev_device *d;
 251                 const char *dn;
 252                 _cleanup_free_ MountPoint *lb = NULL;
 253
 254                 d = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item));
 255                 if (!d)
 256                         return -ENOMEM;
 257
 258                 dn = udev_device_get_devnode(d);
 259                 if (!dn)
 260                         continue;
 261
 262                 lb = new0(MountPoint, 1);
 263                 if (!lb)
 264                         return -ENOMEM;
 265
 266                 r = free_and_strdup(&lb->path, dn);
 267                 if (r < 0)
 268                         return r;
 269
 270                 LIST_PREPEND(mount_point, *head, lb);
 271                 lb = NULL;
 272         }
 273
 274         return 0;
 275 }
 276
 277 static int dm_list_get(MountPoint **head) {
 278         _cleanup_(udev_enumerate_unrefp) struct udev_enumerate *e = NULL;
 279         struct udev_list_entry *item = NULL, *first = NULL;
 280         _cleanup_(udev_unrefp) struct udev *udev = NULL;
 281         int r;
 282
 283         assert(head);
 284
 285         udev = udev_new();
 286         if (!udev)
 287                 return -ENOMEM;
 288
 289         e = udev_enumerate_new(udev);
 290         if (!e)
 291                 return -ENOMEM;
 292
 293         r = udev_enumerate_add_match_subsystem(e, "block");
 294         if (r < 0)
 295                 return r;
 296
 297         r = udev_enumerate_add_match_sysname(e, "dm-*");
 298         if (r < 0)
 299                 return r;
 300
 301         r = udev_enumerate_scan_devices(e);
 302         if (r < 0)
 303                 return r;
 304
 305         first = udev_enumerate_get_list_entry(e);
 306         udev_list_entry_foreach(item, first) {
 307                 _cleanup_(udev_device_unrefp) struct udev_device *d;
 308                 dev_t devnum;
 309                 const char *dn;
 310                 _cleanup_free_ MountPoint *m = NULL;
 311
 312                 d = udev_device_new_from_syspath(udev, udev_list_entry_get_name(item));
 313                 if (!d)
 314                         return -ENOMEM;
 315
 316                 devnum = udev_device_get_devnum(d);
 317                 dn = udev_device_get_devnode(d);
 318                 if (major(devnum) == 0 || !dn)
 319                         continue;
 320
 321                 m = new0(MountPoint, 1);
 322                 if (!m)
 323                         return -ENOMEM;
 324
 325                 m->devnum = devnum;
 326                 r = free_and_strdup(&m->path, dn);
 327                 if (r < 0)
 328                         return r;
 329
 330                 LIST_PREPEND(mount_point, *head, m);
 331                 m = NULL;
 332         }
 333
 334         return 0;
 335 }
 336
 337 static int delete_loopback(const char *device) {
 338         _cleanup_close_ int fd = -1;
 339         int r;
 340
 341         assert(device);
 342
 343         fd = open(device, O_RDONLY|O_CLOEXEC);
 344         if (fd < 0)
 345                 return errno == ENOENT ? 0 : -errno;
 346
 347         r = ioctl(fd, LOOP_CLR_FD, 0);
 348         if (r >= 0)
 349                 return 1;
 350
 351         /* ENXIO: not bound, so no error */
 352         if (errno == ENXIO)
 353                 return 0;
 354
 355         return -errno;
 356 }
 357
 358 static int delete_dm(dev_t devnum) {
 359
 360         struct dm_ioctl dm = {
 361                 .version = {
 362                         DM_VERSION_MAJOR,
 363                         DM_VERSION_MINOR,
 364                         DM_VERSION_PATCHLEVEL
 365                 },
 366                 .data_size = sizeof(dm),
 367                 .dev = devnum,
 368         };
 369
 370         _cleanup_close_ int fd = -1;
 371
 372         assert(major(devnum) != 0);
 373
 374         fd = open("/dev/mapper/control", O_RDWR|O_CLOEXEC);
 375         if (fd < 0)
 376                 return -errno;
 377
 378         if (ioctl(fd, DM_DEV_REMOVE, &dm) < 0)
 379                 return -errno;
 380
 381         return 0;
 382 }
 383
 384 static bool nonunmountable_path(const char *path) {
 385         return path_equal(path, "/")
 386 #if ! HAVE_SPLIT_USR
 387                 || path_equal(path, "/usr")
 388 #endif
 389                 || path_startswith(path, "/run/initramfs");
 390 }
 391
 392 static int remount_with_timeout(MountPoint *m, int umount_log_level) {
 393         pid_t pid;
 394         int r;
 395
 396         BLOCK_SIGNALS(SIGCHLD);
 397
 398         assert(m);
 399
 400         /* Due to the possiblity of a remount operation hanging, we
 401          * fork a child process and set a timeout. If the timeout
 402          * lapses, the assumption is that that particular remount
 403          * failed. */
 404         r = safe_fork("(sd-remount)", FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_LOG|FORK_REOPEN_LOG, &pid);
 405         if (r < 0)
 406                 return r;
 407         if (r == 0) {
 408                 log_info("Remounting '%s' read-only in with options '%s'.", m->path, m->remount_options);
 409
 410                 /* Start the mount operation here in the child */
 411                 r = mount(NULL, m->path, NULL, m->remount_flags, m->remount_options);
 412                 if (r < 0)
 413                         log_full_errno(umount_log_level, errno, "Failed to remount '%s' read-only: %m", m->path);
 414
 415                 _exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS);
 416         }
 417
 418         r = wait_for_terminate_with_timeout(pid, DEFAULT_TIMEOUT_USEC);
 419         if (r == -ETIMEDOUT) {
 420                 log_error_errno(r, "Remounting '%s' timed out, issuing SIGKILL to PID " PID_FMT ".", m->path, pid);
 421                 (void) kill(pid, SIGKILL);
 422         } else if (r == -EPROTO)
 423                 log_debug_errno(r, "Remounting '%s' failed abnormally, child process " PID_FMT " aborted or exited non-zero.", m->path, pid);
 424         else if (r < 0)
 425                 log_error_errno(r, "Remounting '%s' failed unexpectedly, couldn't wait for child process " PID_FMT ": %m", m->path, pid);
 426
 427         return r;
 428 }
 429
 430 static int umount_with_timeout(MountPoint *m, int umount_log_level) {
 431         pid_t pid;
 432         int r;
 433
 434         BLOCK_SIGNALS(SIGCHLD);
 435
 436         assert(m);
 437
 438         /* Due to the possiblity of a umount operation hanging, we
 439          * fork a child process and set a timeout. If the timeout
 440          * lapses, the assumption is that that particular umount
 441          * failed. */
 442         r = safe_fork("(sd-umount)", FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_LOG|FORK_REOPEN_LOG, &pid);
 443         if (r < 0)
 444                 return r;
 445         if (r == 0) {
 446                 log_info("Unmounting '%s'.", m->path);
 447
 448                 /* Start the mount operation here in the child Using MNT_FORCE
 449                  * causes some filesystems (e.g. FUSE and NFS and other network
 450                  * filesystems) to abort any pending requests and return -EIO
 451                  * rather than blocking indefinitely. If the filesysten is
 452                  * "busy", this may allow processes to die, thus making the
 453                  * filesystem less busy so the unmount might succeed (rather
 454                  * then return EBUSY).*/
 455                 r = umount2(m->path, MNT_FORCE);
 456                 if (r < 0)
 457                         log_full_errno(umount_log_level, errno, "Failed to unmount %s: %m", m->path);
 458
 459                 _exit(r < 0 ? EXIT_FAILURE : EXIT_SUCCESS);
 460         }
 461
 462         r = wait_for_terminate_with_timeout(pid, DEFAULT_TIMEOUT_USEC);
 463         if (r == -ETIMEDOUT) {
 464                 log_error_errno(r, "Unmounting '%s' timed out, issuing SIGKILL to PID " PID_FMT ".", m->path, pid);
 465                 (void) kill(pid, SIGKILL);
 466         } else if (r == -EPROTO)
 467                 log_debug_errno(r, "Unmounting '%s' failed abnormally, child process " PID_FMT " aborted or exited non-zero.", m->path, pid);
 468         else if (r < 0)
 469                 log_error_errno(r, "Unmounting '%s' failed unexpectedly, couldn't wait for child process " PID_FMT ": %m", m->path, pid);
 470
 471         return r;
 472 }
 473
 474 /* This includes remounting readonly, which changes the kernel mount options.
 475  * Therefore the list passed to this function is invalidated, and should not be reused. */
 476 static int mount_points_list_umount(MountPoint **head, bool *changed, int umount_log_level) {
 477         MountPoint *m;
 478         int n_failed = 0;
 479
 480         assert(head);
 481         assert(changed);
 482
 483         LIST_FOREACH(mount_point, m, *head) {
 484                 if (m->try_remount_ro) {
 485                         /* We always try to remount directories
 486                          * read-only first, before we go on and umount
 487                          * them.
 488                          *
 489                          * Mount points can be stacked. If a mount
 490                          * point is stacked below / or /usr, we
 491                          * cannot umount or remount it directly,
 492                          * since there is no way to refer to the
 493                          * underlying mount. There's nothing we can do
 494                          * about it for the general case, but we can
 495                          * do something about it if it is aliased
 496                          * somehwere else via a bind mount. If we
 497                          * explicitly remount the super block of that
 498                          * alias read-only we hence should be
 499                          * relatively safe regarding keeping a dirty fs
 500                          * we cannot otherwise see.
 501                          *
 502                          * Since the remount can hang in the instance of
 503                          * remote filesystems, we remount asynchronously
 504                          * and skip the subsequent umount if it fails. */
 505                         if (remount_with_timeout(m, umount_log_level) < 0) {
 506                                 /* Remount failed, but try unmounting anyway,
 507                                  * unless this is a mount point we want to skip. */
 508                                 if (nonunmountable_path(m->path)) {
 509                                         n_failed++;
 510                                         continue;
 511                                 }
 512                         }
 513                 }
 514
 515                 /* Skip / and /usr since we cannot unmount that
 516                  * anyway, since we are running from it. They have
 517                  * already been remounted ro. */
 518                 if (nonunmountable_path(m->path))
 519                         continue;
 520
 521                 /* Trying to umount */
 522                 if (umount_with_timeout(m, umount_log_level) < 0)
 523                         n_failed++;
 524                 else
 525                         *changed = true;
 526         }
 527
 528         return n_failed;
 529 }
 530
 531 static int swap_points_list_off(MountPoint **head, bool *changed) {
 532         MountPoint *m, *n;
 533         int n_failed = 0;
 534
 535         assert(head);
 536         assert(changed);
 537
 538         LIST_FOREACH_SAFE(mount_point, m, n, *head) {
 539                 log_info("Deactivating swap %s.", m->path);
 540                 if (swapoff(m->path) == 0) {
 541                         *changed = true;
 542                         mount_point_free(head, m);
 543                 } else {
 544                         log_warning_errno(errno, "Could not deactivate swap %s: %m", m->path);
 545                         n_failed++;
 546                 }
 547         }
 548
 549         return n_failed;
 550 }
 551
 552 static int loopback_points_list_detach(MountPoint **head, bool *changed, int umount_log_level) {
 553         MountPoint *m, *n;
 554         int n_failed = 0, k;
 555         struct stat root_st;
 556
 557         assert(head);
 558         assert(changed);
 559
 560         k = lstat("/", &root_st);
 561
 562         LIST_FOREACH_SAFE(mount_point, m, n, *head) {
 563                 int r;
 564                 struct stat loopback_st;
 565
 566                 if (k >= 0 &&
 567                     major(root_st.st_dev) != 0 &&
 568                     lstat(m->path, &loopback_st) >= 0 &&
 569                     root_st.st_dev == loopback_st.st_rdev) {
 570                         n_failed++;
 571                         continue;
 572                 }
 573
 574                 log_info("Detaching loopback %s.", m->path);
 575                 r = delete_loopback(m->path);
 576                 if (r >= 0) {
 577                         if (r > 0)
 578                                 *changed = true;
 579
 580                         mount_point_free(head, m);
 581                 } else {
 582                         log_full_errno(umount_log_level, errno, "Could not detach loopback %s: %m", m->path);
 583                         n_failed++;
 584                 }
 585         }
 586
 587         return n_failed;
 588 }
 589
 590 static int dm_points_list_detach(MountPoint **head, bool *changed, int umount_log_level) {
 591         MountPoint *m, *n;
 592         int n_failed = 0, r;
 593         dev_t rootdev;
 594
 595         assert(head);
 596         assert(changed);
 597
 598         r = get_block_device("/", &rootdev);
 599         if (r <= 0)
 600                 rootdev = 0;
 601
 602         LIST_FOREACH_SAFE(mount_point, m, n, *head) {
 603
 604                 if (major(rootdev) != 0 && rootdev == m->devnum) {
 605                         n_failed ++;
 606                         continue;
 607                 }
 608
 609                 log_info("Detaching DM %u:%u.", major(m->devnum), minor(m->devnum));
 610                 r = delete_dm(m->devnum);
 611                 if (r >= 0) {
 612                         *changed = true;
 613                         mount_point_free(head, m);
 614                 } else {
 615                         log_full_errno(umount_log_level, errno, "Could not detach DM %s: %m", m->path);
 616                         n_failed++;
 617                 }
 618         }
 619
 620         return n_failed;
 621 }
 622
 623 static int umount_all_once(bool *changed, int umount_log_level) {
 624         int r;
 625         _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, mp_list_head);
 626
 627         assert(changed);
 628
 629         LIST_HEAD_INIT(mp_list_head);
 630         r = mount_points_list_get(NULL, &mp_list_head);
 631         if (r < 0)
 632                 return r;
 633
 634         return mount_points_list_umount(&mp_list_head, changed, umount_log_level);
 635 }
 636
 637 int umount_all(bool *changed, int umount_log_level) {
 638         bool umount_changed;
 639         int r;
 640
 641         assert(changed);
 642
 643         /* Retry umount, until nothing can be umounted anymore. Mounts are
 644          * processed in order, newest first. The retries are needed when
 645          * an old mount has been moved, to a path inside a newer mount. */
 646         do {
 647                 umount_changed = false;
 648
 649                 r = umount_all_once(&umount_changed, umount_log_level);
 650                 if (umount_changed)
 651                         *changed = true;
 652         } while (umount_changed);
 653
 654         return r;
 655 }
 656
 657 int swapoff_all(bool *changed) {
 658         _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, swap_list_head);
 659         int r;
 660
 661         assert(changed);
 662
 663         LIST_HEAD_INIT(swap_list_head);
 664
 665         r = swap_list_get(NULL, &swap_list_head);
 666         if (r < 0)
 667                 return r;
 668
 669         return swap_points_list_off(&swap_list_head, changed);
 670 }
 671
 672 int loopback_detach_all(bool *changed, int umount_log_level) {
 673         _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, loopback_list_head);
 674         int r;
 675
 676         assert(changed);
 677
 678         LIST_HEAD_INIT(loopback_list_head);
 679
 680         r = loopback_list_get(&loopback_list_head);
 681         if (r < 0)
 682                 return r;
 683
 684         return loopback_points_list_detach(&loopback_list_head, changed, umount_log_level);
 685 }
 686
 687 int dm_detach_all(bool *changed, int umount_log_level) {
 688         _cleanup_(mount_points_list_free) LIST_HEAD(MountPoint, dm_list_head);
 689         int r;
 690
 691         assert(changed);
 692
 693         LIST_HEAD_INIT(dm_list_head);
 694
 695         r = dm_list_get(&dm_list_head);
 696         if (r < 0)
 697                 return r;
 698
 699         return dm_points_list_detach(&dm_list_head, changed, umount_log_level);
 700 }