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Ram Pai07b20882005-11-07 17:19:07 -05001/*
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 */
Kirill Korotaev6b3286e2006-12-08 02:37:56 -08009#include <linux/mnt_namespace.h>
Ram Pai07b20882005-11-07 17:19:07 -050010#include <linux/mount.h>
11#include <linux/fs.h>
Eric W. Biederman132c94e2013-03-22 04:08:05 -070012#include <linux/nsproxy.h>
Al Viro6d59e7f2008-03-22 15:48:17 -040013#include "internal.h"
Ram Pai07b20882005-11-07 17:19:07 -050014#include "pnode.h"
15
Ram Pai03e06e62005-11-07 17:19:33 -050016/* return the next shared peer mount of @p */
Al Viroc9371352011-11-24 23:56:26 -050017static inline struct mount *next_peer(struct mount *p)
Ram Pai03e06e62005-11-07 17:19:33 -050018{
Al Viro6776db3d2011-11-25 00:22:05 -050019 return list_entry(p->mnt_share.next, struct mount, mnt_share);
Ram Pai03e06e62005-11-07 17:19:33 -050020}
21
Al Viroc9371352011-11-24 23:56:26 -050022static inline struct mount *first_slave(struct mount *p)
Ram Pai5afe0022005-11-07 17:21:01 -050023{
Al Viro6776db3d2011-11-25 00:22:05 -050024 return list_entry(p->mnt_slave_list.next, struct mount, mnt_slave);
Ram Pai5afe0022005-11-07 17:21:01 -050025}
26
Al Viroc9371352011-11-24 23:56:26 -050027static inline struct mount *next_slave(struct mount *p)
Ram Pai5afe0022005-11-07 17:21:01 -050028{
Al Viro6776db3d2011-11-25 00:22:05 -050029 return list_entry(p->mnt_slave.next, struct mount, mnt_slave);
Ram Pai5afe0022005-11-07 17:21:01 -050030}
31
Al Viro6fc78712011-11-24 23:35:54 -050032static struct mount *get_peer_under_root(struct mount *mnt,
33 struct mnt_namespace *ns,
34 const struct path *root)
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +010035{
Al Viro6fc78712011-11-24 23:35:54 -050036 struct mount *m = mnt;
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +010037
38 do {
39 /* Check the namespace first for optimization */
Al Viro143c8c92011-11-25 00:46:35 -050040 if (m->mnt_ns == ns && is_path_reachable(m, m->mnt.mnt_root, root))
Al Viro6fc78712011-11-24 23:35:54 -050041 return m;
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +010042
Al Viroc9371352011-11-24 23:56:26 -050043 m = next_peer(m);
Al Viro6fc78712011-11-24 23:35:54 -050044 } while (m != mnt);
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +010045
46 return NULL;
47}
48
49/*
50 * Get ID of closest dominating peer group having a representative
51 * under the given root.
52 *
53 * Caller must hold namespace_sem
54 */
Al Viro6fc78712011-11-24 23:35:54 -050055int get_dominating_id(struct mount *mnt, const struct path *root)
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +010056{
Al Viro6fc78712011-11-24 23:35:54 -050057 struct mount *m;
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +010058
Al Viro32301922011-11-25 00:10:28 -050059 for (m = mnt->mnt_master; m != NULL; m = m->mnt_master) {
Al Viro143c8c92011-11-25 00:46:35 -050060 struct mount *d = get_peer_under_root(m, mnt->mnt_ns, root);
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +010061 if (d)
Al Viro15169fe2011-11-25 00:50:41 -050062 return d->mnt_group_id;
Miklos Szeredi97e7e0f2008-03-27 13:06:26 +010063 }
64
65 return 0;
66}
67
Al Viro6fc78712011-11-24 23:35:54 -050068static int do_make_slave(struct mount *mnt)
Ram Paia58b0eb2005-11-07 17:20:48 -050069{
Al Viro32301922011-11-25 00:10:28 -050070 struct mount *peer_mnt = mnt, *master = mnt->mnt_master;
Al Virod10e8de2011-11-25 00:07:16 -050071 struct mount *slave_mnt;
Ram Paia58b0eb2005-11-07 17:20:48 -050072
73 /*
74 * slave 'mnt' to a peer mount that has the
Al Viro796a6b52010-01-16 13:28:47 -050075 * same root dentry. If none is available then
Ram Paia58b0eb2005-11-07 17:20:48 -050076 * slave it to anything that is available.
77 */
Al Viroc9371352011-11-24 23:56:26 -050078 while ((peer_mnt = next_peer(peer_mnt)) != mnt &&
Al Viro6fc78712011-11-24 23:35:54 -050079 peer_mnt->mnt.mnt_root != mnt->mnt.mnt_root) ;
Ram Paia58b0eb2005-11-07 17:20:48 -050080
81 if (peer_mnt == mnt) {
Al Viroc9371352011-11-24 23:56:26 -050082 peer_mnt = next_peer(mnt);
Ram Paia58b0eb2005-11-07 17:20:48 -050083 if (peer_mnt == mnt)
84 peer_mnt = NULL;
85 }
Takashi Iwai5d477b62013-05-10 14:04:11 +020086 if (mnt->mnt_group_id && IS_MNT_SHARED(mnt) &&
87 list_empty(&mnt->mnt_share))
Al Viro6fc78712011-11-24 23:35:54 -050088 mnt_release_group_id(mnt);
Miklos Szeredi719f5d72008-03-27 13:06:23 +010089
Al Viro6776db3d2011-11-25 00:22:05 -050090 list_del_init(&mnt->mnt_share);
Al Viro15169fe2011-11-25 00:50:41 -050091 mnt->mnt_group_id = 0;
Ram Paia58b0eb2005-11-07 17:20:48 -050092
93 if (peer_mnt)
94 master = peer_mnt;
95
96 if (master) {
Al Viro6776db3d2011-11-25 00:22:05 -050097 list_for_each_entry(slave_mnt, &mnt->mnt_slave_list, mnt_slave)
Al Viro32301922011-11-25 00:10:28 -050098 slave_mnt->mnt_master = master;
Al Viro6776db3d2011-11-25 00:22:05 -050099 list_move(&mnt->mnt_slave, &master->mnt_slave_list);
100 list_splice(&mnt->mnt_slave_list, master->mnt_slave_list.prev);
101 INIT_LIST_HEAD(&mnt->mnt_slave_list);
Ram Paia58b0eb2005-11-07 17:20:48 -0500102 } else {
Al Viro6776db3d2011-11-25 00:22:05 -0500103 struct list_head *p = &mnt->mnt_slave_list;
Ram Paia58b0eb2005-11-07 17:20:48 -0500104 while (!list_empty(p)) {
Pavel Emelianovb5e61812007-05-08 00:30:19 -0700105 slave_mnt = list_first_entry(p,
Al Viro6776db3d2011-11-25 00:22:05 -0500106 struct mount, mnt_slave);
107 list_del_init(&slave_mnt->mnt_slave);
Ram Paia58b0eb2005-11-07 17:20:48 -0500108 slave_mnt->mnt_master = NULL;
109 }
110 }
Al Viro32301922011-11-25 00:10:28 -0500111 mnt->mnt_master = master;
Al Virofc7be132011-11-25 01:05:37 -0500112 CLEAR_MNT_SHARED(mnt);
Ram Paia58b0eb2005-11-07 17:20:48 -0500113 return 0;
114}
115
Nick Piggin99b7db72010-08-18 04:37:39 +1000116/*
117 * vfsmount lock must be held for write
118 */
Al Viro0f0afb12011-11-24 20:43:10 -0500119void change_mnt_propagation(struct mount *mnt, int type)
Ram Pai07b20882005-11-07 17:19:07 -0500120{
Ram Pai03e06e62005-11-07 17:19:33 -0500121 if (type == MS_SHARED) {
Ram Paib90fa9a2005-11-07 17:19:50 -0500122 set_mnt_shared(mnt);
Ram Paia58b0eb2005-11-07 17:20:48 -0500123 return;
124 }
Al Viro6fc78712011-11-24 23:35:54 -0500125 do_make_slave(mnt);
Ram Paia58b0eb2005-11-07 17:20:48 -0500126 if (type != MS_SLAVE) {
Al Viro6776db3d2011-11-25 00:22:05 -0500127 list_del_init(&mnt->mnt_slave);
Al Virod10e8de2011-11-25 00:07:16 -0500128 mnt->mnt_master = NULL;
Ram Pai9676f0c2005-11-07 17:21:20 -0500129 if (type == MS_UNBINDABLE)
Al Viro0f0afb12011-11-24 20:43:10 -0500130 mnt->mnt.mnt_flags |= MNT_UNBINDABLE;
Andries E. Brouwer0b03cfb2008-02-06 01:36:32 -0800131 else
Al Viro0f0afb12011-11-24 20:43:10 -0500132 mnt->mnt.mnt_flags &= ~MNT_UNBINDABLE;
Ram Pai03e06e62005-11-07 17:19:33 -0500133 }
Ram Pai07b20882005-11-07 17:19:07 -0500134}
Ram Paib90fa9a2005-11-07 17:19:50 -0500135
136/*
137 * get the next mount in the propagation tree.
138 * @m: the mount seen last
139 * @origin: the original mount from where the tree walk initiated
Al Viro796a6b52010-01-16 13:28:47 -0500140 *
141 * Note that peer groups form contiguous segments of slave lists.
142 * We rely on that in get_source() to be able to find out if
143 * vfsmount found while iterating with propagation_next() is
144 * a peer of one we'd found earlier.
Ram Paib90fa9a2005-11-07 17:19:50 -0500145 */
Al Viroc9371352011-11-24 23:56:26 -0500146static struct mount *propagation_next(struct mount *m,
147 struct mount *origin)
Ram Paib90fa9a2005-11-07 17:19:50 -0500148{
Ram Pai5afe0022005-11-07 17:21:01 -0500149 /* are there any slaves of this mount? */
Al Viro143c8c92011-11-25 00:46:35 -0500150 if (!IS_MNT_NEW(m) && !list_empty(&m->mnt_slave_list))
Ram Pai5afe0022005-11-07 17:21:01 -0500151 return first_slave(m);
152
153 while (1) {
Al Viro32301922011-11-25 00:10:28 -0500154 struct mount *master = m->mnt_master;
Ram Pai5afe0022005-11-07 17:21:01 -0500155
Al Viro32301922011-11-25 00:10:28 -0500156 if (master == origin->mnt_master) {
Al Viroc9371352011-11-24 23:56:26 -0500157 struct mount *next = next_peer(m);
158 return (next == origin) ? NULL : next;
Al Viro6776db3d2011-11-25 00:22:05 -0500159 } else if (m->mnt_slave.next != &master->mnt_slave_list)
Ram Pai5afe0022005-11-07 17:21:01 -0500160 return next_slave(m);
161
162 /* back at master */
163 m = master;
164 }
165}
166
Al Virof2ebb3a2014-02-27 09:35:45 -0500167static struct mount *next_group(struct mount *m, struct mount *origin)
Ram Pai5afe0022005-11-07 17:21:01 -0500168{
Al Virof2ebb3a2014-02-27 09:35:45 -0500169 while (1) {
170 while (1) {
171 struct mount *next;
172 if (!IS_MNT_NEW(m) && !list_empty(&m->mnt_slave_list))
173 return first_slave(m);
174 next = next_peer(m);
175 if (m->mnt_group_id == origin->mnt_group_id) {
176 if (next == origin)
177 return NULL;
178 } else if (m->mnt_slave.next != &next->mnt_slave)
179 break;
180 m = next;
Al Viro796a6b52010-01-16 13:28:47 -0500181 }
Al Virof2ebb3a2014-02-27 09:35:45 -0500182 /* m is the last peer */
183 while (1) {
184 struct mount *master = m->mnt_master;
185 if (m->mnt_slave.next != &master->mnt_slave_list)
186 return next_slave(m);
187 m = next_peer(master);
188 if (master->mnt_group_id == origin->mnt_group_id)
189 break;
190 if (master->mnt_slave.next == &m->mnt_slave)
191 break;
192 m = master;
193 }
194 if (m == origin)
195 return NULL;
Ram Pai5afe0022005-11-07 17:21:01 -0500196 }
Al Virof2ebb3a2014-02-27 09:35:45 -0500197}
198
199/* all accesses are serialized by namespace_sem */
200static struct user_namespace *user_ns;
Eric W. Biederman5ec08112016-05-05 09:29:29 -0500201static struct mount *last_dest, *first_source, *last_source, *dest_master;
Al Virof2ebb3a2014-02-27 09:35:45 -0500202static struct mountpoint *mp;
203static struct hlist_head *list;
204
Maxim Patlasov7ae8fd02016-02-16 11:45:33 -0800205static inline bool peers(struct mount *m1, struct mount *m2)
206{
207 return m1->mnt_group_id == m2->mnt_group_id && m1->mnt_group_id;
208}
209
Al Virof2ebb3a2014-02-27 09:35:45 -0500210static int propagate_one(struct mount *m)
211{
212 struct mount *child;
213 int type;
214 /* skip ones added by this propagate_mnt() */
215 if (IS_MNT_NEW(m))
216 return 0;
217 /* skip if mountpoint isn't covered by it */
218 if (!is_subdir(mp->m_dentry, m->mnt.mnt_root))
219 return 0;
Maxim Patlasov7ae8fd02016-02-16 11:45:33 -0800220 if (peers(m, last_dest)) {
Al Virof2ebb3a2014-02-27 09:35:45 -0500221 type = CL_MAKE_SHARED;
222 } else {
223 struct mount *n, *p;
Eric W. Biederman5ec08112016-05-05 09:29:29 -0500224 bool done;
Al Virof2ebb3a2014-02-27 09:35:45 -0500225 for (n = m; ; n = p) {
226 p = n->mnt_master;
Eric W. Biederman5ec08112016-05-05 09:29:29 -0500227 if (p == dest_master || IS_MNT_MARKED(p))
Al Virof2ebb3a2014-02-27 09:35:45 -0500228 break;
Al Virof2ebb3a2014-02-27 09:35:45 -0500229 }
Eric W. Biederman5ec08112016-05-05 09:29:29 -0500230 do {
231 struct mount *parent = last_source->mnt_parent;
232 if (last_source == first_source)
233 break;
234 done = parent->mnt_master == p;
235 if (done && peers(n, parent))
236 break;
237 last_source = last_source->mnt_master;
238 } while (!done);
239
Al Virof2ebb3a2014-02-27 09:35:45 -0500240 type = CL_SLAVE;
241 /* beginning of peer group among the slaves? */
242 if (IS_MNT_SHARED(m))
243 type |= CL_MAKE_SHARED;
244 }
245
246 /* Notice when we are propagating across user namespaces */
247 if (m->mnt_ns->user_ns != user_ns)
248 type |= CL_UNPRIVILEGED;
249 child = copy_tree(last_source, last_source->mnt.mnt_root, type);
250 if (IS_ERR(child))
251 return PTR_ERR(child);
Eric W. Biederman8486a782014-10-07 16:22:52 -0700252 child->mnt.mnt_flags &= ~MNT_LOCKED;
Al Virof2ebb3a2014-02-27 09:35:45 -0500253 mnt_set_mountpoint(m, mp, child);
254 last_dest = m;
255 last_source = child;
256 if (m->mnt_master != dest_master) {
257 read_seqlock_excl(&mount_lock);
258 SET_MNT_MARK(m->mnt_master);
259 read_sequnlock_excl(&mount_lock);
260 }
261 hlist_add_head(&child->mnt_hash, list);
262 return 0;
Ram Paib90fa9a2005-11-07 17:19:50 -0500263}
264
265/*
266 * mount 'source_mnt' under the destination 'dest_mnt' at
267 * dentry 'dest_dentry'. And propagate that mount to
268 * all the peer and slave mounts of 'dest_mnt'.
269 * Link all the new mounts into a propagation tree headed at
270 * source_mnt. Also link all the new mounts using ->mnt_list
271 * headed at source_mnt's ->mnt_list
272 *
273 * @dest_mnt: destination mount.
274 * @dest_dentry: destination dentry.
275 * @source_mnt: source mount.
276 * @tree_list : list of heads of trees to be attached.
277 */
Al Viro84d17192013-03-15 10:53:28 -0400278int propagate_mnt(struct mount *dest_mnt, struct mountpoint *dest_mp,
Al Viro38129a12014-03-20 21:10:51 -0400279 struct mount *source_mnt, struct hlist_head *tree_list)
Ram Paib90fa9a2005-11-07 17:19:50 -0500280{
Al Virof2ebb3a2014-02-27 09:35:45 -0500281 struct mount *m, *n;
Ram Paib90fa9a2005-11-07 17:19:50 -0500282 int ret = 0;
Ram Paib90fa9a2005-11-07 17:19:50 -0500283
Al Virof2ebb3a2014-02-27 09:35:45 -0500284 /*
285 * we don't want to bother passing tons of arguments to
286 * propagate_one(); everything is serialized by namespace_sem,
287 * so globals will do just fine.
288 */
289 user_ns = current->nsproxy->mnt_ns->user_ns;
290 last_dest = dest_mnt;
Eric W. Biederman5ec08112016-05-05 09:29:29 -0500291 first_source = source_mnt;
Al Virof2ebb3a2014-02-27 09:35:45 -0500292 last_source = source_mnt;
293 mp = dest_mp;
294 list = tree_list;
295 dest_master = dest_mnt->mnt_master;
Ram Paib90fa9a2005-11-07 17:19:50 -0500296
Al Virof2ebb3a2014-02-27 09:35:45 -0500297 /* all peers of dest_mnt, except dest_mnt itself */
298 for (n = next_peer(dest_mnt); n != dest_mnt; n = next_peer(n)) {
299 ret = propagate_one(n);
300 if (ret)
Ram Paib90fa9a2005-11-07 17:19:50 -0500301 goto out;
Al Virof2ebb3a2014-02-27 09:35:45 -0500302 }
Ram Paib90fa9a2005-11-07 17:19:50 -0500303
Al Virof2ebb3a2014-02-27 09:35:45 -0500304 /* all slave groups */
305 for (m = next_group(dest_mnt, dest_mnt); m;
306 m = next_group(m, dest_mnt)) {
307 /* everything in that slave group */
308 n = m;
309 do {
310 ret = propagate_one(n);
311 if (ret)
312 goto out;
313 n = next_peer(n);
314 } while (n != m);
Ram Paib90fa9a2005-11-07 17:19:50 -0500315 }
316out:
Al Virof2ebb3a2014-02-27 09:35:45 -0500317 read_seqlock_excl(&mount_lock);
318 hlist_for_each_entry(n, tree_list, mnt_hash) {
319 m = n->mnt_parent;
320 if (m->mnt_master != dest_mnt->mnt_master)
321 CLEAR_MNT_MARK(m->mnt_master);
Ram Paib90fa9a2005-11-07 17:19:50 -0500322 }
Al Virof2ebb3a2014-02-27 09:35:45 -0500323 read_sequnlock_excl(&mount_lock);
Ram Paib90fa9a2005-11-07 17:19:50 -0500324 return ret;
325}
Ram Paia05964f2005-11-07 17:20:17 -0500326
327/*
328 * return true if the refcount is greater than count
329 */
Al Viro1ab59732011-11-24 21:35:16 -0500330static inline int do_refcount_check(struct mount *mnt, int count)
Ram Paia05964f2005-11-07 17:20:17 -0500331{
Al Viroaba809cf2013-09-28 23:10:55 -0400332 return mnt_get_count(mnt) > count;
Ram Paia05964f2005-11-07 17:20:17 -0500333}
334
335/*
336 * check if the mount 'mnt' can be unmounted successfully.
337 * @mnt: the mount to be checked for unmount
338 * NOTE: unmounting 'mnt' would naturally propagate to all
339 * other mounts its parent propagates to.
340 * Check if any of these mounts that **do not have submounts**
341 * have more references than 'refcnt'. If so return busy.
Nick Piggin99b7db72010-08-18 04:37:39 +1000342 *
Nick Pigginb3e19d92011-01-07 17:50:11 +1100343 * vfsmount lock must be held for write
Ram Paia05964f2005-11-07 17:20:17 -0500344 */
Al Viro1ab59732011-11-24 21:35:16 -0500345int propagate_mount_busy(struct mount *mnt, int refcnt)
Ram Paia05964f2005-11-07 17:20:17 -0500346{
Al Viroc9371352011-11-24 23:56:26 -0500347 struct mount *m, *child;
Al Viro0714a532011-11-24 22:19:58 -0500348 struct mount *parent = mnt->mnt_parent;
Ram Paia05964f2005-11-07 17:20:17 -0500349 int ret = 0;
350
Al Viro0714a532011-11-24 22:19:58 -0500351 if (mnt == parent)
Ram Paia05964f2005-11-07 17:20:17 -0500352 return do_refcount_check(mnt, refcnt);
353
354 /*
355 * quickly check if the current mount can be unmounted.
356 * If not, we don't have to go checking for all other
357 * mounts
358 */
Al Viro6b41d532011-11-24 23:24:33 -0500359 if (!list_empty(&mnt->mnt_mounts) || do_refcount_check(mnt, refcnt))
Ram Paia05964f2005-11-07 17:20:17 -0500360 return 1;
361
Al Viroc9371352011-11-24 23:56:26 -0500362 for (m = propagation_next(parent, parent); m;
363 m = propagation_next(m, parent)) {
Al Viro474279d2013-10-01 16:11:26 -0400364 child = __lookup_mnt_last(&m->mnt, mnt->mnt_mountpoint);
Al Viro6b41d532011-11-24 23:24:33 -0500365 if (child && list_empty(&child->mnt_mounts) &&
Al Viro1ab59732011-11-24 21:35:16 -0500366 (ret = do_refcount_check(child, 1)))
Ram Paia05964f2005-11-07 17:20:17 -0500367 break;
368 }
369 return ret;
370}
371
372/*
Eric W. Biederman5d884572015-01-03 05:39:35 -0600373 * Clear MNT_LOCKED when it can be shown to be safe.
374 *
375 * mount_lock lock must be held for write
376 */
377void propagate_mount_unlock(struct mount *mnt)
378{
379 struct mount *parent = mnt->mnt_parent;
380 struct mount *m, *child;
381
382 BUG_ON(parent == mnt);
383
384 for (m = propagation_next(parent, parent); m;
385 m = propagation_next(m, parent)) {
386 child = __lookup_mnt_last(&m->mnt, mnt->mnt_mountpoint);
387 if (child)
388 child->mnt.mnt_flags &= ~MNT_LOCKED;
389 }
390}
391
392/*
Eric W. Biederman0c56fe32015-01-05 13:38:04 -0600393 * Mark all mounts that the MNT_LOCKED logic will allow to be unmounted.
394 */
395static void mark_umount_candidates(struct mount *mnt)
396{
397 struct mount *parent = mnt->mnt_parent;
398 struct mount *m;
399
400 BUG_ON(parent == mnt);
401
402 for (m = propagation_next(parent, parent); m;
403 m = propagation_next(m, parent)) {
404 struct mount *child = __lookup_mnt_last(&m->mnt,
405 mnt->mnt_mountpoint);
406 if (child && (!IS_MNT_LOCKED(child) || IS_MNT_MARKED(m))) {
407 SET_MNT_MARK(child);
408 }
409 }
410}
411
412/*
Ram Paia05964f2005-11-07 17:20:17 -0500413 * NOTE: unmounting 'mnt' naturally propagates to all other mounts its
414 * parent propagates to.
415 */
Al Viro61ef47b2011-11-24 18:25:28 -0500416static void __propagate_umount(struct mount *mnt)
Ram Paia05964f2005-11-07 17:20:17 -0500417{
Al Viro0714a532011-11-24 22:19:58 -0500418 struct mount *parent = mnt->mnt_parent;
Al Viroc9371352011-11-24 23:56:26 -0500419 struct mount *m;
Ram Paia05964f2005-11-07 17:20:17 -0500420
Al Viro0714a532011-11-24 22:19:58 -0500421 BUG_ON(parent == mnt);
Ram Paia05964f2005-11-07 17:20:17 -0500422
Al Viroc9371352011-11-24 23:56:26 -0500423 for (m = propagation_next(parent, parent); m;
424 m = propagation_next(m, parent)) {
Ram Paia05964f2005-11-07 17:20:17 -0500425
Al Viro474279d2013-10-01 16:11:26 -0400426 struct mount *child = __lookup_mnt_last(&m->mnt,
427 mnt->mnt_mountpoint);
Ram Paia05964f2005-11-07 17:20:17 -0500428 /*
Eric W. Biederman0c56fe32015-01-05 13:38:04 -0600429 * umount the child only if the child has no children
430 * and the child is marked safe to unmount.
Ram Paia05964f2005-11-07 17:20:17 -0500431 */
Eric W. Biederman0c56fe32015-01-05 13:38:04 -0600432 if (!child || !IS_MNT_MARKED(child))
433 continue;
434 CLEAR_MNT_MARK(child);
435 if (list_empty(&child->mnt_mounts)) {
Al Viro88b368f2014-08-18 15:09:26 -0400436 list_del_init(&child->mnt_child);
Eric W. Biederman590ce4b2014-12-22 18:30:08 -0600437 child->mnt.mnt_flags |= MNT_UMOUNT;
Eric W. Biedermanc003b262014-12-18 13:10:48 -0600438 list_move_tail(&child->mnt_list, &mnt->mnt_list);
Al Viro38129a12014-03-20 21:10:51 -0400439 }
Ram Paia05964f2005-11-07 17:20:17 -0500440 }
441}
442
443/*
444 * collect all mounts that receive propagation from the mount in @list,
445 * and return these additional mounts in the same list.
446 * @list: the list of mounts to be unmounted.
Nick Piggin99b7db72010-08-18 04:37:39 +1000447 *
448 * vfsmount lock must be held for write
Ram Paia05964f2005-11-07 17:20:17 -0500449 */
Eric W. Biedermanc003b262014-12-18 13:10:48 -0600450int propagate_umount(struct list_head *list)
Ram Paia05964f2005-11-07 17:20:17 -0500451{
Al Viro61ef47b2011-11-24 18:25:28 -0500452 struct mount *mnt;
Ram Paia05964f2005-11-07 17:20:17 -0500453
Eric W. Biederman0c56fe32015-01-05 13:38:04 -0600454 list_for_each_entry_reverse(mnt, list, mnt_list)
455 mark_umount_candidates(mnt);
456
Eric W. Biedermanc003b262014-12-18 13:10:48 -0600457 list_for_each_entry(mnt, list, mnt_list)
Ram Paia05964f2005-11-07 17:20:17 -0500458 __propagate_umount(mnt);
459 return 0;
460}