| 1 | /* |
| 2 | * linux/fs/pnode.c |
| 3 | * |
| 4 | * (C) Copyright IBM Corporation 2005. |
| 5 | * Released under GPL v2. |
| 6 | * Author : Ram Pai (linuxram@us.ibm.com) |
| 7 | * |
| 8 | */ |
| 9 | #include <linux/mnt_namespace.h> |
| 10 | #include <linux/mount.h> |
| 11 | #include <linux/fs.h> |
| 12 | #include <linux/nsproxy.h> |
| 13 | #include "internal.h" |
| 14 | #include "pnode.h" |
| 15 | |
| 16 | /* return the next shared peer mount of @p */ |
| 17 | static inline struct mount *next_peer(struct mount *p) |
| 18 | { |
| 19 | return list_entry(p->mnt_share.next, struct mount, mnt_share); |
| 20 | } |
| 21 | |
| 22 | static inline struct mount *first_slave(struct mount *p) |
| 23 | { |
| 24 | return list_entry(p->mnt_slave_list.next, struct mount, mnt_slave); |
| 25 | } |
| 26 | |
| 27 | static inline struct mount *last_slave(struct mount *p) |
| 28 | { |
| 29 | return list_entry(p->mnt_slave_list.prev, struct mount, mnt_slave); |
| 30 | } |
| 31 | |
| 32 | static inline struct mount *next_slave(struct mount *p) |
| 33 | { |
| 34 | return list_entry(p->mnt_slave.next, struct mount, mnt_slave); |
| 35 | } |
| 36 | |
| 37 | static struct mount *get_peer_under_root(struct mount *mnt, |
| 38 | struct mnt_namespace *ns, |
| 39 | const struct path *root) |
| 40 | { |
| 41 | struct mount *m = mnt; |
| 42 | |
| 43 | do { |
| 44 | /* Check the namespace first for optimization */ |
| 45 | if (m->mnt_ns == ns && is_path_reachable(m, m->mnt.mnt_root, root)) |
| 46 | return m; |
| 47 | |
| 48 | m = next_peer(m); |
| 49 | } while (m != mnt); |
| 50 | |
| 51 | return NULL; |
| 52 | } |
| 53 | |
| 54 | /* |
| 55 | * Get ID of closest dominating peer group having a representative |
| 56 | * under the given root. |
| 57 | * |
| 58 | * Caller must hold namespace_sem |
| 59 | */ |
| 60 | int get_dominating_id(struct mount *mnt, const struct path *root) |
| 61 | { |
| 62 | struct mount *m; |
| 63 | |
| 64 | for (m = mnt->mnt_master; m != NULL; m = m->mnt_master) { |
| 65 | struct mount *d = get_peer_under_root(m, mnt->mnt_ns, root); |
| 66 | if (d) |
| 67 | return d->mnt_group_id; |
| 68 | } |
| 69 | |
| 70 | return 0; |
| 71 | } |
| 72 | |
| 73 | static int do_make_slave(struct mount *mnt) |
| 74 | { |
| 75 | struct mount *master, *slave_mnt; |
| 76 | |
| 77 | if (list_empty(&mnt->mnt_share)) { |
| 78 | if (IS_MNT_SHARED(mnt)) { |
| 79 | mnt_release_group_id(mnt); |
| 80 | CLEAR_MNT_SHARED(mnt); |
| 81 | } |
| 82 | master = mnt->mnt_master; |
| 83 | if (!master) { |
| 84 | struct list_head *p = &mnt->mnt_slave_list; |
| 85 | while (!list_empty(p)) { |
| 86 | slave_mnt = list_first_entry(p, |
| 87 | struct mount, mnt_slave); |
| 88 | list_del_init(&slave_mnt->mnt_slave); |
| 89 | slave_mnt->mnt_master = NULL; |
| 90 | } |
| 91 | return 0; |
| 92 | } |
| 93 | } else { |
| 94 | struct mount *m; |
| 95 | /* |
| 96 | * slave 'mnt' to a peer mount that has the |
| 97 | * same root dentry. If none is available then |
| 98 | * slave it to anything that is available. |
| 99 | */ |
| 100 | for (m = master = next_peer(mnt); m != mnt; m = next_peer(m)) { |
| 101 | if (m->mnt.mnt_root == mnt->mnt.mnt_root) { |
| 102 | master = m; |
| 103 | break; |
| 104 | } |
| 105 | } |
| 106 | list_del_init(&mnt->mnt_share); |
| 107 | mnt->mnt_group_id = 0; |
| 108 | CLEAR_MNT_SHARED(mnt); |
| 109 | } |
| 110 | list_for_each_entry(slave_mnt, &mnt->mnt_slave_list, mnt_slave) |
| 111 | slave_mnt->mnt_master = master; |
| 112 | list_move(&mnt->mnt_slave, &master->mnt_slave_list); |
| 113 | list_splice(&mnt->mnt_slave_list, master->mnt_slave_list.prev); |
| 114 | INIT_LIST_HEAD(&mnt->mnt_slave_list); |
| 115 | mnt->mnt_master = master; |
| 116 | return 0; |
| 117 | } |
| 118 | |
| 119 | /* |
| 120 | * vfsmount lock must be held for write |
| 121 | */ |
| 122 | void change_mnt_propagation(struct mount *mnt, int type) |
| 123 | { |
| 124 | if (type == MS_SHARED) { |
| 125 | set_mnt_shared(mnt); |
| 126 | return; |
| 127 | } |
| 128 | do_make_slave(mnt); |
| 129 | if (type != MS_SLAVE) { |
| 130 | list_del_init(&mnt->mnt_slave); |
| 131 | mnt->mnt_master = NULL; |
| 132 | if (type == MS_UNBINDABLE) |
| 133 | mnt->mnt.mnt_flags |= MNT_UNBINDABLE; |
| 134 | else |
| 135 | mnt->mnt.mnt_flags &= ~MNT_UNBINDABLE; |
| 136 | } |
| 137 | } |
| 138 | |
| 139 | /* |
| 140 | * get the next mount in the propagation tree. |
| 141 | * @m: the mount seen last |
| 142 | * @origin: the original mount from where the tree walk initiated |
| 143 | * |
| 144 | * Note that peer groups form contiguous segments of slave lists. |
| 145 | * We rely on that in get_source() to be able to find out if |
| 146 | * vfsmount found while iterating with propagation_next() is |
| 147 | * a peer of one we'd found earlier. |
| 148 | */ |
| 149 | static struct mount *propagation_next(struct mount *m, |
| 150 | struct mount *origin) |
| 151 | { |
| 152 | /* are there any slaves of this mount? */ |
| 153 | if (!IS_MNT_NEW(m) && !list_empty(&m->mnt_slave_list)) |
| 154 | return first_slave(m); |
| 155 | |
| 156 | while (1) { |
| 157 | struct mount *master = m->mnt_master; |
| 158 | |
| 159 | if (master == origin->mnt_master) { |
| 160 | struct mount *next = next_peer(m); |
| 161 | return (next == origin) ? NULL : next; |
| 162 | } else if (m->mnt_slave.next != &master->mnt_slave_list) |
| 163 | return next_slave(m); |
| 164 | |
| 165 | /* back at master */ |
| 166 | m = master; |
| 167 | } |
| 168 | } |
| 169 | |
| 170 | static struct mount *skip_propagation_subtree(struct mount *m, |
| 171 | struct mount *origin) |
| 172 | { |
| 173 | /* |
| 174 | * Advance m such that propagation_next will not return |
| 175 | * the slaves of m. |
| 176 | */ |
| 177 | if (!IS_MNT_NEW(m) && !list_empty(&m->mnt_slave_list)) |
| 178 | m = last_slave(m); |
| 179 | |
| 180 | return m; |
| 181 | } |
| 182 | |
| 183 | static struct mount *next_group(struct mount *m, struct mount *origin) |
| 184 | { |
| 185 | while (1) { |
| 186 | while (1) { |
| 187 | struct mount *next; |
| 188 | if (!IS_MNT_NEW(m) && !list_empty(&m->mnt_slave_list)) |
| 189 | return first_slave(m); |
| 190 | next = next_peer(m); |
| 191 | if (m->mnt_group_id == origin->mnt_group_id) { |
| 192 | if (next == origin) |
| 193 | return NULL; |
| 194 | } else if (m->mnt_slave.next != &next->mnt_slave) |
| 195 | break; |
| 196 | m = next; |
| 197 | } |
| 198 | /* m is the last peer */ |
| 199 | while (1) { |
| 200 | struct mount *master = m->mnt_master; |
| 201 | if (m->mnt_slave.next != &master->mnt_slave_list) |
| 202 | return next_slave(m); |
| 203 | m = next_peer(master); |
| 204 | if (master->mnt_group_id == origin->mnt_group_id) |
| 205 | break; |
| 206 | if (master->mnt_slave.next == &m->mnt_slave) |
| 207 | break; |
| 208 | m = master; |
| 209 | } |
| 210 | if (m == origin) |
| 211 | return NULL; |
| 212 | } |
| 213 | } |
| 214 | |
| 215 | /* all accesses are serialized by namespace_sem */ |
| 216 | static struct user_namespace *user_ns; |
| 217 | static struct mount *last_dest, *first_source, *last_source, *dest_master; |
| 218 | static struct mountpoint *mp; |
| 219 | static struct hlist_head *list; |
| 220 | |
| 221 | static inline bool peers(struct mount *m1, struct mount *m2) |
| 222 | { |
| 223 | return m1->mnt_group_id == m2->mnt_group_id && m1->mnt_group_id; |
| 224 | } |
| 225 | |
| 226 | static int propagate_one(struct mount *m) |
| 227 | { |
| 228 | struct mount *child; |
| 229 | int type; |
| 230 | /* skip ones added by this propagate_mnt() */ |
| 231 | if (IS_MNT_NEW(m)) |
| 232 | return 0; |
| 233 | /* skip if mountpoint isn't covered by it */ |
| 234 | if (!is_subdir(mp->m_dentry, m->mnt.mnt_root)) |
| 235 | return 0; |
| 236 | if (peers(m, last_dest)) { |
| 237 | type = CL_MAKE_SHARED; |
| 238 | } else { |
| 239 | struct mount *n, *p; |
| 240 | bool done; |
| 241 | for (n = m; ; n = p) { |
| 242 | p = n->mnt_master; |
| 243 | if (p == dest_master || IS_MNT_MARKED(p)) |
| 244 | break; |
| 245 | } |
| 246 | do { |
| 247 | struct mount *parent = last_source->mnt_parent; |
| 248 | if (last_source == first_source) |
| 249 | break; |
| 250 | done = parent->mnt_master == p; |
| 251 | if (done && peers(n, parent)) |
| 252 | break; |
| 253 | last_source = last_source->mnt_master; |
| 254 | } while (!done); |
| 255 | |
| 256 | type = CL_SLAVE; |
| 257 | /* beginning of peer group among the slaves? */ |
| 258 | if (IS_MNT_SHARED(m)) |
| 259 | type |= CL_MAKE_SHARED; |
| 260 | } |
| 261 | |
| 262 | /* Notice when we are propagating across user namespaces */ |
| 263 | if (m->mnt_ns->user_ns != user_ns) |
| 264 | type |= CL_UNPRIVILEGED; |
| 265 | child = copy_tree(last_source, last_source->mnt.mnt_root, type); |
| 266 | if (IS_ERR(child)) |
| 267 | return PTR_ERR(child); |
| 268 | child->mnt.mnt_flags &= ~MNT_LOCKED; |
| 269 | mnt_set_mountpoint(m, mp, child); |
| 270 | last_dest = m; |
| 271 | last_source = child; |
| 272 | if (m->mnt_master != dest_master) { |
| 273 | read_seqlock_excl(&mount_lock); |
| 274 | SET_MNT_MARK(m->mnt_master); |
| 275 | read_sequnlock_excl(&mount_lock); |
| 276 | } |
| 277 | hlist_add_head(&child->mnt_hash, list); |
| 278 | return count_mounts(m->mnt_ns, child); |
| 279 | } |
| 280 | |
| 281 | /* |
| 282 | * mount 'source_mnt' under the destination 'dest_mnt' at |
| 283 | * dentry 'dest_dentry'. And propagate that mount to |
| 284 | * all the peer and slave mounts of 'dest_mnt'. |
| 285 | * Link all the new mounts into a propagation tree headed at |
| 286 | * source_mnt. Also link all the new mounts using ->mnt_list |
| 287 | * headed at source_mnt's ->mnt_list |
| 288 | * |
| 289 | * @dest_mnt: destination mount. |
| 290 | * @dest_dentry: destination dentry. |
| 291 | * @source_mnt: source mount. |
| 292 | * @tree_list : list of heads of trees to be attached. |
| 293 | */ |
| 294 | int propagate_mnt(struct mount *dest_mnt, struct mountpoint *dest_mp, |
| 295 | struct mount *source_mnt, struct hlist_head *tree_list) |
| 296 | { |
| 297 | struct mount *m, *n; |
| 298 | int ret = 0; |
| 299 | |
| 300 | /* |
| 301 | * we don't want to bother passing tons of arguments to |
| 302 | * propagate_one(); everything is serialized by namespace_sem, |
| 303 | * so globals will do just fine. |
| 304 | */ |
| 305 | user_ns = current->nsproxy->mnt_ns->user_ns; |
| 306 | last_dest = dest_mnt; |
| 307 | first_source = source_mnt; |
| 308 | last_source = source_mnt; |
| 309 | mp = dest_mp; |
| 310 | list = tree_list; |
| 311 | dest_master = dest_mnt->mnt_master; |
| 312 | |
| 313 | /* all peers of dest_mnt, except dest_mnt itself */ |
| 314 | for (n = next_peer(dest_mnt); n != dest_mnt; n = next_peer(n)) { |
| 315 | ret = propagate_one(n); |
| 316 | if (ret) |
| 317 | goto out; |
| 318 | } |
| 319 | |
| 320 | /* all slave groups */ |
| 321 | for (m = next_group(dest_mnt, dest_mnt); m; |
| 322 | m = next_group(m, dest_mnt)) { |
| 323 | /* everything in that slave group */ |
| 324 | n = m; |
| 325 | do { |
| 326 | ret = propagate_one(n); |
| 327 | if (ret) |
| 328 | goto out; |
| 329 | n = next_peer(n); |
| 330 | } while (n != m); |
| 331 | } |
| 332 | out: |
| 333 | read_seqlock_excl(&mount_lock); |
| 334 | hlist_for_each_entry(n, tree_list, mnt_hash) { |
| 335 | m = n->mnt_parent; |
| 336 | if (m->mnt_master != dest_mnt->mnt_master) |
| 337 | CLEAR_MNT_MARK(m->mnt_master); |
| 338 | } |
| 339 | read_sequnlock_excl(&mount_lock); |
| 340 | return ret; |
| 341 | } |
| 342 | |
| 343 | static struct mount *find_topper(struct mount *mnt) |
| 344 | { |
| 345 | /* If there is exactly one mount covering mnt completely return it. */ |
| 346 | struct mount *child; |
| 347 | |
| 348 | if (!list_is_singular(&mnt->mnt_mounts)) |
| 349 | return NULL; |
| 350 | |
| 351 | child = list_first_entry(&mnt->mnt_mounts, struct mount, mnt_child); |
| 352 | if (child->mnt_mountpoint != mnt->mnt.mnt_root) |
| 353 | return NULL; |
| 354 | |
| 355 | return child; |
| 356 | } |
| 357 | |
| 358 | /* |
| 359 | * return true if the refcount is greater than count |
| 360 | */ |
| 361 | static inline int do_refcount_check(struct mount *mnt, int count) |
| 362 | { |
| 363 | return mnt_get_count(mnt) > count; |
| 364 | } |
| 365 | |
| 366 | /* |
| 367 | * check if the mount 'mnt' can be unmounted successfully. |
| 368 | * @mnt: the mount to be checked for unmount |
| 369 | * NOTE: unmounting 'mnt' would naturally propagate to all |
| 370 | * other mounts its parent propagates to. |
| 371 | * Check if any of these mounts that **do not have submounts** |
| 372 | * have more references than 'refcnt'. If so return busy. |
| 373 | * |
| 374 | * vfsmount lock must be held for write |
| 375 | */ |
| 376 | int propagate_mount_busy(struct mount *mnt, int refcnt) |
| 377 | { |
| 378 | struct mount *m, *child, *topper; |
| 379 | struct mount *parent = mnt->mnt_parent; |
| 380 | |
| 381 | if (mnt == parent) |
| 382 | return do_refcount_check(mnt, refcnt); |
| 383 | |
| 384 | /* |
| 385 | * quickly check if the current mount can be unmounted. |
| 386 | * If not, we don't have to go checking for all other |
| 387 | * mounts |
| 388 | */ |
| 389 | if (!list_empty(&mnt->mnt_mounts) || do_refcount_check(mnt, refcnt)) |
| 390 | return 1; |
| 391 | |
| 392 | for (m = propagation_next(parent, parent); m; |
| 393 | m = propagation_next(m, parent)) { |
| 394 | int count = 1; |
| 395 | child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint); |
| 396 | if (!child) |
| 397 | continue; |
| 398 | |
| 399 | /* Is there exactly one mount on the child that covers |
| 400 | * it completely whose reference should be ignored? |
| 401 | */ |
| 402 | topper = find_topper(child); |
| 403 | if (topper) |
| 404 | count += 1; |
| 405 | else if (!list_empty(&child->mnt_mounts)) |
| 406 | continue; |
| 407 | |
| 408 | if (do_refcount_check(child, count)) |
| 409 | return 1; |
| 410 | } |
| 411 | return 0; |
| 412 | } |
| 413 | |
| 414 | /* |
| 415 | * Clear MNT_LOCKED when it can be shown to be safe. |
| 416 | * |
| 417 | * mount_lock lock must be held for write |
| 418 | */ |
| 419 | void propagate_mount_unlock(struct mount *mnt) |
| 420 | { |
| 421 | struct mount *parent = mnt->mnt_parent; |
| 422 | struct mount *m, *child; |
| 423 | |
| 424 | BUG_ON(parent == mnt); |
| 425 | |
| 426 | for (m = propagation_next(parent, parent); m; |
| 427 | m = propagation_next(m, parent)) { |
| 428 | child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint); |
| 429 | if (child) |
| 430 | child->mnt.mnt_flags &= ~MNT_LOCKED; |
| 431 | } |
| 432 | } |
| 433 | |
| 434 | static void umount_one(struct mount *mnt, struct list_head *to_umount) |
| 435 | { |
| 436 | CLEAR_MNT_MARK(mnt); |
| 437 | mnt->mnt.mnt_flags |= MNT_UMOUNT; |
| 438 | list_del_init(&mnt->mnt_child); |
| 439 | list_del_init(&mnt->mnt_umounting); |
| 440 | list_move_tail(&mnt->mnt_list, to_umount); |
| 441 | } |
| 442 | |
| 443 | /* |
| 444 | * NOTE: unmounting 'mnt' naturally propagates to all other mounts its |
| 445 | * parent propagates to. |
| 446 | */ |
| 447 | static bool __propagate_umount(struct mount *mnt, |
| 448 | struct list_head *to_umount, |
| 449 | struct list_head *to_restore) |
| 450 | { |
| 451 | bool progress = false; |
| 452 | struct mount *child; |
| 453 | |
| 454 | /* |
| 455 | * The state of the parent won't change if this mount is |
| 456 | * already unmounted or marked as without children. |
| 457 | */ |
| 458 | if (mnt->mnt.mnt_flags & (MNT_UMOUNT | MNT_MARKED)) |
| 459 | goto out; |
| 460 | |
| 461 | /* Verify topper is the only grandchild that has not been |
| 462 | * speculatively unmounted. |
| 463 | */ |
| 464 | list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { |
| 465 | if (child->mnt_mountpoint == mnt->mnt.mnt_root) |
| 466 | continue; |
| 467 | if (!list_empty(&child->mnt_umounting) && IS_MNT_MARKED(child)) |
| 468 | continue; |
| 469 | /* Found a mounted child */ |
| 470 | goto children; |
| 471 | } |
| 472 | |
| 473 | /* Mark mounts that can be unmounted if not locked */ |
| 474 | SET_MNT_MARK(mnt); |
| 475 | progress = true; |
| 476 | |
| 477 | /* If a mount is without children and not locked umount it. */ |
| 478 | if (!IS_MNT_LOCKED(mnt)) { |
| 479 | umount_one(mnt, to_umount); |
| 480 | } else { |
| 481 | children: |
| 482 | list_move_tail(&mnt->mnt_umounting, to_restore); |
| 483 | } |
| 484 | out: |
| 485 | return progress; |
| 486 | } |
| 487 | |
| 488 | static void umount_list(struct list_head *to_umount, |
| 489 | struct list_head *to_restore) |
| 490 | { |
| 491 | struct mount *mnt, *child, *tmp; |
| 492 | list_for_each_entry(mnt, to_umount, mnt_list) { |
| 493 | list_for_each_entry_safe(child, tmp, &mnt->mnt_mounts, mnt_child) { |
| 494 | /* topper? */ |
| 495 | if (child->mnt_mountpoint == mnt->mnt.mnt_root) |
| 496 | list_move_tail(&child->mnt_umounting, to_restore); |
| 497 | else |
| 498 | umount_one(child, to_umount); |
| 499 | } |
| 500 | } |
| 501 | } |
| 502 | |
| 503 | static void restore_mounts(struct list_head *to_restore) |
| 504 | { |
| 505 | /* Restore mounts to a clean working state */ |
| 506 | while (!list_empty(to_restore)) { |
| 507 | struct mount *mnt, *parent; |
| 508 | struct mountpoint *mp; |
| 509 | |
| 510 | mnt = list_first_entry(to_restore, struct mount, mnt_umounting); |
| 511 | CLEAR_MNT_MARK(mnt); |
| 512 | list_del_init(&mnt->mnt_umounting); |
| 513 | |
| 514 | /* Should this mount be reparented? */ |
| 515 | mp = mnt->mnt_mp; |
| 516 | parent = mnt->mnt_parent; |
| 517 | while (parent->mnt.mnt_flags & MNT_UMOUNT) { |
| 518 | mp = parent->mnt_mp; |
| 519 | parent = parent->mnt_parent; |
| 520 | } |
| 521 | if (parent != mnt->mnt_parent) |
| 522 | mnt_change_mountpoint(parent, mp, mnt); |
| 523 | } |
| 524 | } |
| 525 | |
| 526 | static void cleanup_umount_visitations(struct list_head *visited) |
| 527 | { |
| 528 | while (!list_empty(visited)) { |
| 529 | struct mount *mnt = |
| 530 | list_first_entry(visited, struct mount, mnt_umounting); |
| 531 | list_del_init(&mnt->mnt_umounting); |
| 532 | } |
| 533 | } |
| 534 | |
| 535 | /* |
| 536 | * collect all mounts that receive propagation from the mount in @list, |
| 537 | * and return these additional mounts in the same list. |
| 538 | * @list: the list of mounts to be unmounted. |
| 539 | * |
| 540 | * vfsmount lock must be held for write |
| 541 | */ |
| 542 | int propagate_umount(struct list_head *list) |
| 543 | { |
| 544 | struct mount *mnt; |
| 545 | LIST_HEAD(to_restore); |
| 546 | LIST_HEAD(to_umount); |
| 547 | LIST_HEAD(visited); |
| 548 | |
| 549 | /* Find candidates for unmounting */ |
| 550 | list_for_each_entry_reverse(mnt, list, mnt_list) { |
| 551 | struct mount *parent = mnt->mnt_parent; |
| 552 | struct mount *m; |
| 553 | |
| 554 | /* |
| 555 | * If this mount has already been visited it is known that it's |
| 556 | * entire peer group and all of their slaves in the propagation |
| 557 | * tree for the mountpoint has already been visited and there is |
| 558 | * no need to visit them again. |
| 559 | */ |
| 560 | if (!list_empty(&mnt->mnt_umounting)) |
| 561 | continue; |
| 562 | |
| 563 | list_add_tail(&mnt->mnt_umounting, &visited); |
| 564 | for (m = propagation_next(parent, parent); m; |
| 565 | m = propagation_next(m, parent)) { |
| 566 | struct mount *child = __lookup_mnt(&m->mnt, |
| 567 | mnt->mnt_mountpoint); |
| 568 | if (!child) |
| 569 | continue; |
| 570 | |
| 571 | if (!list_empty(&child->mnt_umounting)) { |
| 572 | /* |
| 573 | * If the child has already been visited it is |
| 574 | * know that it's entire peer group and all of |
| 575 | * their slaves in the propgation tree for the |
| 576 | * mountpoint has already been visited and there |
| 577 | * is no need to visit this subtree again. |
| 578 | */ |
| 579 | m = skip_propagation_subtree(m, parent); |
| 580 | continue; |
| 581 | } else if (child->mnt.mnt_flags & MNT_UMOUNT) { |
| 582 | /* |
| 583 | * We have come accross an partially unmounted |
| 584 | * mount in list that has not been visited yet. |
| 585 | * Remember it has been visited and continue |
| 586 | * about our merry way. |
| 587 | */ |
| 588 | list_add_tail(&child->mnt_umounting, &visited); |
| 589 | continue; |
| 590 | } |
| 591 | |
| 592 | /* Check the child and parents while progress is made */ |
| 593 | while (__propagate_umount(child, |
| 594 | &to_umount, &to_restore)) { |
| 595 | /* Is the parent a umount candidate? */ |
| 596 | child = child->mnt_parent; |
| 597 | if (list_empty(&child->mnt_umounting)) |
| 598 | break; |
| 599 | } |
| 600 | } |
| 601 | } |
| 602 | |
| 603 | umount_list(&to_umount, &to_restore); |
| 604 | restore_mounts(&to_restore); |
| 605 | cleanup_umount_visitations(&visited); |
| 606 | list_splice_tail(&to_umount, list); |
| 607 | |
| 608 | return 0; |
| 609 | } |