static int do_make_slave(struct mount *mnt)
{
- struct mount *peer_mnt = mnt, *master = mnt->mnt_master;
- struct mount *slave_mnt;
+ struct mount *master, *slave_mnt;
- /*
- * slave 'mnt' to a peer mount that has the
- * same root dentry. If none is available then
- * slave it to anything that is available.
- */
- while ((peer_mnt = next_peer(peer_mnt)) != mnt &&
- peer_mnt->mnt.mnt_root != mnt->mnt.mnt_root) ;
-
- if (peer_mnt == mnt) {
- peer_mnt = next_peer(mnt);
- if (peer_mnt == mnt)
- peer_mnt = NULL;
- }
- if (mnt->mnt_group_id && IS_MNT_SHARED(mnt) &&
- list_empty(&mnt->mnt_share))
- mnt_release_group_id(mnt);
-
- list_del_init(&mnt->mnt_share);
- mnt->mnt_group_id = 0;
-
- if (peer_mnt)
- master = peer_mnt;
-
- if (master) {
- list_for_each_entry(slave_mnt, &mnt->mnt_slave_list, mnt_slave)
- slave_mnt->mnt_master = master;
- list_move(&mnt->mnt_slave, &master->mnt_slave_list);
- list_splice(&mnt->mnt_slave_list, master->mnt_slave_list.prev);
- INIT_LIST_HEAD(&mnt->mnt_slave_list);
+ if (list_empty(&mnt->mnt_share)) {
+ if (IS_MNT_SHARED(mnt)) {
+ mnt_release_group_id(mnt);
+ CLEAR_MNT_SHARED(mnt);
+ }
+ master = mnt->mnt_master;
+ if (!master) {
+ struct list_head *p = &mnt->mnt_slave_list;
+ while (!list_empty(p)) {
+ slave_mnt = list_first_entry(p,
+ struct mount, mnt_slave);
+ list_del_init(&slave_mnt->mnt_slave);
+ slave_mnt->mnt_master = NULL;
+ }
+ return 0;
+ }
} else {
- struct list_head *p = &mnt->mnt_slave_list;
- while (!list_empty(p)) {
- slave_mnt = list_first_entry(p,
- struct mount, mnt_slave);
- list_del_init(&slave_mnt->mnt_slave);
- slave_mnt->mnt_master = NULL;
+ struct mount *m;
+ /*
+ * slave 'mnt' to a peer mount that has the
+ * same root dentry. If none is available then
+ * slave it to anything that is available.
+ */
+ for (m = master = next_peer(mnt); m != mnt; m = next_peer(m)) {
+ if (m->mnt.mnt_root == mnt->mnt.mnt_root) {
+ master = m;
+ break;
+ }
}
+ list_del_init(&mnt->mnt_share);
+ mnt->mnt_group_id = 0;
+ CLEAR_MNT_SHARED(mnt);
}
+ list_for_each_entry(slave_mnt, &mnt->mnt_slave_list, mnt_slave)
+ slave_mnt->mnt_master = master;
+ list_move(&mnt->mnt_slave, &master->mnt_slave_list);
+ list_splice(&mnt->mnt_slave_list, master->mnt_slave_list.prev);
+ INIT_LIST_HEAD(&mnt->mnt_slave_list);
mnt->mnt_master = master;
- CLEAR_MNT_SHARED(mnt);
return 0;
}
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;
}
for (m = propagation_next(parent, parent); m;
m = propagation_next(m, parent)) {
- struct mount *child = __lookup_mnt_last(&m->mnt,
+ struct mount *child = __lookup_mnt(&m->mnt,
mnt->mnt_mountpoint);
- if (child && (!IS_MNT_LOCKED(child) || IS_MNT_MARKED(m))) {
+ if (!child || (child->mnt.mnt_flags & MNT_UMOUNT))
+ continue;
+ if (!IS_MNT_LOCKED(child) || IS_MNT_MARKED(m)) {
SET_MNT_MARK(child);
}
}
for (m = propagation_next(parent, parent); m;
m = propagation_next(m, parent)) {
-
- struct mount *child = __lookup_mnt_last(&m->mnt,
+ struct mount *topper;
+ struct mount *child = __lookup_mnt(&m->mnt,
mnt->mnt_mountpoint);
/*
* umount the child only if the child has no children
if (!child || !IS_MNT_MARKED(child))
continue;
CLEAR_MNT_MARK(child);
+
+ /* If there is exactly one mount covering all of child
+ * replace child with that mount.
+ */
+ topper = find_topper(child);
+ if (topper)
+ mnt_change_mountpoint(child->mnt_parent, child->mnt_mp,
+ topper);
+
if (list_empty(&child->mnt_mounts)) {
list_del_init(&child->mnt_child);
child->mnt.mnt_flags |= MNT_UMOUNT;