return list_entry(p->mnt_slave_list.next, struct mount, mnt_slave);
}
+static inline struct mount *last_slave(struct mount *p)
+{
+ return list_entry(p->mnt_slave_list.prev, struct mount, mnt_slave);
+}
+
static inline struct mount *next_slave(struct mount *p)
{
return list_entry(p->mnt_slave.next, struct mount, mnt_slave);
}
}
+static struct mount *skip_propagation_subtree(struct mount *m,
+ struct mount *origin)
+{
+ /*
+ * Advance m such that propagation_next will not return
+ * the slaves of m.
+ */
+ if (!IS_MNT_NEW(m) && !list_empty(&m->mnt_slave_list))
+ m = last_slave(m);
+
+ return m;
+}
+
static struct mount *next_group(struct mount *m, struct mount *origin)
{
while (1) {
/* all accesses are serialized by namespace_sem */
static struct user_namespace *user_ns;
-static struct mount *last_dest, *last_source, *dest_master;
+static struct mount *last_dest, *first_source, *last_source, *dest_master;
static struct mountpoint *mp;
static struct hlist_head *list;
+static inline bool peers(struct mount *m1, struct mount *m2)
+{
+ return m1->mnt_group_id == m2->mnt_group_id && m1->mnt_group_id;
+}
+
static int propagate_one(struct mount *m)
{
struct mount *child;
/* skip if mountpoint isn't covered by it */
if (!is_subdir(mp->m_dentry, m->mnt.mnt_root))
return 0;
- if (m->mnt_group_id == last_dest->mnt_group_id) {
+ if (peers(m, last_dest)) {
type = CL_MAKE_SHARED;
} else {
struct mount *n, *p;
+ bool done;
for (n = m; ; n = p) {
p = n->mnt_master;
- if (p == dest_master || IS_MNT_MARKED(p)) {
- while (last_dest->mnt_master != p) {
- last_source = last_source->mnt_master;
- last_dest = last_source->mnt_parent;
- }
- if (n->mnt_group_id != last_dest->mnt_group_id) {
- last_source = last_source->mnt_master;
- last_dest = last_source->mnt_parent;
- }
+ if (p == dest_master || IS_MNT_MARKED(p))
break;
- }
}
+ do {
+ struct mount *parent = last_source->mnt_parent;
+ if (last_source == first_source)
+ break;
+ done = parent->mnt_master == p;
+ if (done && peers(n, parent))
+ break;
+ last_source = last_source->mnt_master;
+ } while (!done);
+
type = CL_SLAVE;
/* beginning of peer group among the slaves? */
if (IS_MNT_SHARED(m))
read_sequnlock_excl(&mount_lock);
}
hlist_add_head(&child->mnt_hash, list);
- return 0;
+ return count_mounts(m->mnt_ns, child);
}
/*
*/
user_ns = current->nsproxy->mnt_ns->user_ns;
last_dest = dest_mnt;
+ first_source = source_mnt;
last_source = source_mnt;
mp = dest_mp;
list = tree_list;
return ret;
}
+static struct mount *find_topper(struct mount *mnt)
+{
+ /* If there is exactly one mount covering mnt completely return it. */
+ struct mount *child;
+
+ if (!list_is_singular(&mnt->mnt_mounts))
+ return NULL;
+
+ child = list_first_entry(&mnt->mnt_mounts, struct mount, mnt_child);
+ if (child->mnt_mountpoint != mnt->mnt.mnt_root)
+ return NULL;
+
+ return child;
+}
+
/*
* return true if the refcount is greater than count
*/
*/
int propagate_mount_busy(struct mount *mnt, int refcnt)
{
- struct mount *m, *child;
+ struct mount *m, *child, *topper;
struct mount *parent = mnt->mnt_parent;
- int ret = 0;
if (mnt == parent)
return do_refcount_check(mnt, refcnt);
for (m = propagation_next(parent, parent); m;
m = propagation_next(m, parent)) {
- child = __lookup_mnt_last(&m->mnt, mnt->mnt_mountpoint);
- if (child && list_empty(&child->mnt_mounts) &&
- (ret = do_refcount_check(child, 1)))
- break;
+ int count = 1;
+ child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint);
+ if (!child)
+ continue;
+
+ /* Is there exactly one mount on the child that covers
+ * it completely whose reference should be ignored?
+ */
+ topper = find_topper(child);
+ if (topper)
+ count += 1;
+ else if (!list_empty(&child->mnt_mounts))
+ continue;
+
+ if (do_refcount_check(child, count))
+ return 1;
}
- return ret;
+ return 0;
}
/*
for (m = propagation_next(parent, parent); m;
m = propagation_next(m, parent)) {
- child = __lookup_mnt_last(&m->mnt, mnt->mnt_mountpoint);
+ child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint);
if (child)
child->mnt.mnt_flags &= ~MNT_LOCKED;
}
}
-/*
- * Mark all mounts that the MNT_LOCKED logic will allow to be unmounted.
- */
-static void mark_umount_candidates(struct mount *mnt)
+static void umount_one(struct mount *mnt, struct list_head *to_umount)
{
- struct mount *parent = mnt->mnt_parent;
- struct mount *m;
-
- BUG_ON(parent == mnt);
-
- for (m = propagation_next(parent, parent); m;
- m = propagation_next(m, parent)) {
- struct mount *child = __lookup_mnt_last(&m->mnt,
- mnt->mnt_mountpoint);
- if (child && (!IS_MNT_LOCKED(child) || IS_MNT_MARKED(m))) {
- SET_MNT_MARK(child);
- }
- }
+ CLEAR_MNT_MARK(mnt);
+ mnt->mnt.mnt_flags |= MNT_UMOUNT;
+ list_del_init(&mnt->mnt_child);
+ list_del_init(&mnt->mnt_umounting);
+ list_move_tail(&mnt->mnt_list, to_umount);
}
/*
* NOTE: unmounting 'mnt' naturally propagates to all other mounts its
* parent propagates to.
*/
-static void __propagate_umount(struct mount *mnt)
+static bool __propagate_umount(struct mount *mnt,
+ struct list_head *to_umount,
+ struct list_head *to_restore)
{
- struct mount *parent = mnt->mnt_parent;
- struct mount *m;
-
- BUG_ON(parent == mnt);
+ bool progress = false;
+ struct mount *child;
- for (m = propagation_next(parent, parent); m;
- m = propagation_next(m, parent)) {
+ /*
+ * The state of the parent won't change if this mount is
+ * already unmounted or marked as without children.
+ */
+ if (mnt->mnt.mnt_flags & (MNT_UMOUNT | MNT_MARKED))
+ goto out;
- struct mount *child = __lookup_mnt_last(&m->mnt,
- mnt->mnt_mountpoint);
- /*
- * umount the child only if the child has no children
- * and the child is marked safe to unmount.
- */
- if (!child || !IS_MNT_MARKED(child))
+ /* Verify topper is the only grandchild that has not been
+ * speculatively unmounted.
+ */
+ list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) {
+ if (child->mnt_mountpoint == mnt->mnt.mnt_root)
continue;
- CLEAR_MNT_MARK(child);
- if (list_empty(&child->mnt_mounts)) {
- list_del_init(&child->mnt_child);
- child->mnt.mnt_flags |= MNT_UMOUNT;
- list_move_tail(&child->mnt_list, &mnt->mnt_list);
+ if (!list_empty(&child->mnt_umounting) && IS_MNT_MARKED(child))
+ continue;
+ /* Found a mounted child */
+ goto children;
+ }
+
+ /* Mark mounts that can be unmounted if not locked */
+ SET_MNT_MARK(mnt);
+ progress = true;
+
+ /* If a mount is without children and not locked umount it. */
+ if (!IS_MNT_LOCKED(mnt)) {
+ umount_one(mnt, to_umount);
+ } else {
+children:
+ list_move_tail(&mnt->mnt_umounting, to_restore);
+ }
+out:
+ return progress;
+}
+
+static void umount_list(struct list_head *to_umount,
+ struct list_head *to_restore)
+{
+ struct mount *mnt, *child, *tmp;
+ list_for_each_entry(mnt, to_umount, mnt_list) {
+ list_for_each_entry_safe(child, tmp, &mnt->mnt_mounts, mnt_child) {
+ /* topper? */
+ if (child->mnt_mountpoint == mnt->mnt.mnt_root)
+ list_move_tail(&child->mnt_umounting, to_restore);
+ else
+ umount_one(child, to_umount);
}
}
}
+static void restore_mounts(struct list_head *to_restore)
+{
+ /* Restore mounts to a clean working state */
+ while (!list_empty(to_restore)) {
+ struct mount *mnt, *parent;
+ struct mountpoint *mp;
+
+ mnt = list_first_entry(to_restore, struct mount, mnt_umounting);
+ CLEAR_MNT_MARK(mnt);
+ list_del_init(&mnt->mnt_umounting);
+
+ /* Should this mount be reparented? */
+ mp = mnt->mnt_mp;
+ parent = mnt->mnt_parent;
+ while (parent->mnt.mnt_flags & MNT_UMOUNT) {
+ mp = parent->mnt_mp;
+ parent = parent->mnt_parent;
+ }
+ if (parent != mnt->mnt_parent)
+ mnt_change_mountpoint(parent, mp, mnt);
+ }
+}
+
+static void cleanup_umount_visitations(struct list_head *visited)
+{
+ while (!list_empty(visited)) {
+ struct mount *mnt =
+ list_first_entry(visited, struct mount, mnt_umounting);
+ list_del_init(&mnt->mnt_umounting);
+ }
+}
+
/*
* collect all mounts that receive propagation from the mount in @list,
* and return these additional mounts in the same list.
int propagate_umount(struct list_head *list)
{
struct mount *mnt;
+ LIST_HEAD(to_restore);
+ LIST_HEAD(to_umount);
+ LIST_HEAD(visited);
+
+ /* Find candidates for unmounting */
+ list_for_each_entry_reverse(mnt, list, mnt_list) {
+ struct mount *parent = mnt->mnt_parent;
+ struct mount *m;
+
+ /*
+ * If this mount has already been visited it is known that it's
+ * entire peer group and all of their slaves in the propagation
+ * tree for the mountpoint has already been visited and there is
+ * no need to visit them again.
+ */
+ if (!list_empty(&mnt->mnt_umounting))
+ continue;
+
+ list_add_tail(&mnt->mnt_umounting, &visited);
+ for (m = propagation_next(parent, parent); m;
+ m = propagation_next(m, parent)) {
+ struct mount *child = __lookup_mnt(&m->mnt,
+ mnt->mnt_mountpoint);
+ if (!child)
+ continue;
+
+ if (!list_empty(&child->mnt_umounting)) {
+ /*
+ * If the child has already been visited it is
+ * know that it's entire peer group and all of
+ * their slaves in the propgation tree for the
+ * mountpoint has already been visited and there
+ * is no need to visit this subtree again.
+ */
+ m = skip_propagation_subtree(m, parent);
+ continue;
+ } else if (child->mnt.mnt_flags & MNT_UMOUNT) {
+ /*
+ * We have come accross an partially unmounted
+ * mount in list that has not been visited yet.
+ * Remember it has been visited and continue
+ * about our merry way.
+ */
+ list_add_tail(&child->mnt_umounting, &visited);
+ continue;
+ }
+
+ /* Check the child and parents while progress is made */
+ while (__propagate_umount(child,
+ &to_umount, &to_restore)) {
+ /* Is the parent a umount candidate? */
+ child = child->mnt_parent;
+ if (list_empty(&child->mnt_umounting))
+ break;
+ }
+ }
+ }
- list_for_each_entry_reverse(mnt, list, mnt_list)
- mark_umount_candidates(mnt);
+ umount_list(&to_umount, &to_restore);
+ restore_mounts(&to_restore);
+ cleanup_umount_visitations(&visited);
+ list_splice_tail(&to_umount, list);
- list_for_each_entry(mnt, list, mnt_list)
- __propagate_umount(mnt);
return 0;
}
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