static struct mount *get_source(struct mount *dest,
struct mount *last_dest,
struct mount *last_src,
int *type)
{
struct mount *p_last_src = NULL;
struct mount *p_last_dest = NULL;
while (last_dest != dest->mnt_master) {
p_last_dest = last_dest;
p_last_src = last_src;
last_dest = last_dest->mnt_master;
last_src = last_src->mnt_master;
}
if (p_last_dest) {
do {
p_last_dest = next_peer(p_last_dest);
} while (IS_MNT_NEW(p_last_dest));
if (dest == p_last_dest) {
*type = CL_MAKE_SHARED;
return p_last_src;
}
}
*type = CL_SLAVE;
if (IS_MNT_SHARED(dest))
*type |= CL_MAKE_SHARED;
return last_src;
}
/*
* return the source mount to be used for cloning
*
* @dest the current destination mount
* @last_dest the last seen destination mount
* @last_src the last seen source mount
* @type return CL_SLAVE if the new mount has to be
* cloned as a slave.
*/
static struct vfsmount *get_source(struct vfsmount *dest,
struct vfsmount *last_dest,
struct vfsmount *last_src,
int *type)
{
struct vfsmount *p_last_src = NULL;
struct vfsmount *p_last_dest = NULL;
while (last_dest != dest->mnt_master) {
p_last_dest = last_dest;
p_last_src = last_src;
last_dest = last_dest->mnt_master;
last_src = last_src->mnt_master;
}
if (p_last_dest) {
do {
p_last_dest = next_peer(p_last_dest);
} while (IS_MNT_NEW(p_last_dest));
/* is that a peer of the earlier? */
if (dest == p_last_dest) {
*type = CL_MAKE_SHARED;
return p_last_src;
}
}
/* slave of the earlier, then */
*type = CL_SLAVE;
/* beginning of peer group among the slaves? */
if (IS_MNT_SHARED(dest))
*type |= CL_MAKE_SHARED;
return last_src;
}
static struct mount *next_group(struct mount *m, struct mount *origin)
{
while (1) {
while (1) {
struct mount *next;
if (!IS_MNT_NEW(m) && !list_empty(&m->mnt_slave_list))
return first_slave(m);
next = next_peer(m);
if (m->mnt_group_id == origin->mnt_group_id) {
if (next == origin)
return NULL;
} else if (m->mnt_slave.next != &next->mnt_slave)
break;
m = next;
}
/* m is the last peer */
while (1) {
struct mount *master = m->mnt_master;
if (m->mnt_slave.next != &master->mnt_slave_list)
return next_slave(m);
m = next_peer(master);
if (master->mnt_group_id == origin->mnt_group_id)
break;
if (master->mnt_slave.next == &m->mnt_slave)
break;
m = master;
}
if (m == origin)
return NULL;
}
}
/*
* mount 'source_mnt' under the destination 'dest_mnt' at
* dentry 'dest_dentry'. And propagate that mount to
* all the peer and slave mounts of 'dest_mnt'.
* Link all the new mounts into a propagation tree headed at
* source_mnt. Also link all the new mounts using ->mnt_list
* headed at source_mnt's ->mnt_list
*
* @dest_mnt: destination mount.
* @dest_dentry: destination dentry.
* @source_mnt: source mount.
* @tree_list : list of heads of trees to be attached.
*/
int propagate_mnt(struct mount *dest_mnt, struct mountpoint *dest_mp,
struct mount *source_mnt, struct hlist_head *tree_list)
{
struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns;
struct mount *m, *child;
int ret = 0;
struct mount *prev_dest_mnt = dest_mnt;
struct mount *prev_src_mnt = source_mnt;
HLIST_HEAD(tmp_list);
for (m = propagation_next(dest_mnt, dest_mnt); m;
m = propagation_next(m, dest_mnt)) {
int type;
struct mount *source;
if (IS_MNT_NEW(m))
continue;
source = get_source(m, prev_dest_mnt, prev_src_mnt, &type);
/* Notice when we are propagating across user namespaces */
if (m->mnt_ns->user_ns != user_ns)
type |= CL_UNPRIVILEGED;
child = copy_tree(source, source->mnt.mnt_root, type);
if (IS_ERR(child)) {
ret = PTR_ERR(child);
tmp_list = *tree_list;
tmp_list.first->pprev = &tmp_list.first;
INIT_HLIST_HEAD(tree_list);
goto out;
}
if (is_subdir(dest_mp->m_dentry, m->mnt.mnt_root)) {
mnt_set_mountpoint(m, dest_mp, child);
hlist_add_head(&child->mnt_hash, tree_list);
} else {
/*
* This can happen if the parent mount was bind mounted
* on some subdirectory of a shared/slave mount.
*/
hlist_add_head(&child->mnt_hash, &tmp_list);
}
prev_dest_mnt = m;
prev_src_mnt = child;
}
out:
lock_mount_hash();
while (!hlist_empty(&tmp_list)) {
child = hlist_entry(tmp_list.first, struct mount, mnt_hash);
umount_tree(child, 0);
}
unlock_mount_hash();
return ret;
}
/*
* mount 'source_mnt' under the destination 'dest_mnt' at
* dentry 'dest_dentry'. And propagate that mount to
* all the peer and slave mounts of 'dest_mnt'.
* Link all the new mounts into a propagation tree headed at
* source_mnt. Also link all the new mounts using ->mnt_list
* headed at source_mnt's ->mnt_list
*
* @dest_mnt: destination mount.
* @dest_dentry: destination dentry.
* @source_mnt: source mount.
* @tree_list : list of heads of trees to be attached.
*/
int propagate_mnt(struct mount *dest_mnt, struct dentry *dest_dentry,
struct mount *source_mnt, struct list_head *tree_list)
{
struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns;
struct mount *m, *child;
int ret = 0;
struct mount *prev_dest_mnt = dest_mnt;
struct mount *prev_src_mnt = source_mnt;
LIST_HEAD(tmp_list);
LIST_HEAD(umount_list);
for (m = propagation_next(dest_mnt, dest_mnt); m;
m = propagation_next(m, dest_mnt)) {
int type;
struct mount *source;
if (IS_MNT_NEW(m))
continue;
source = get_source(m, prev_dest_mnt, prev_src_mnt, &type);
/* Notice when we are propagating across user namespaces */
if (m->mnt_ns->user_ns != user_ns)
type |= CL_UNPRIVILEGED;
child = copy_tree(source, source->mnt.mnt_root, type);
if (IS_ERR(child)) {
ret = PTR_ERR(child);
list_splice(tree_list, tmp_list.prev);
goto out;
}
if (is_subdir(dest_dentry, m->mnt.mnt_root)) {
mnt_set_mountpoint(m, dest_dentry, child);
list_add_tail(&child->mnt_hash, tree_list);
} else {
/*
* This can happen if the parent mount was bind mounted
* on some subdirectory of a shared/slave mount.
*/
list_add_tail(&child->mnt_hash, &tmp_list);
}
prev_dest_mnt = m;
prev_src_mnt = child;
}
out:
br_write_lock(&vfsmount_lock);
while (!list_empty(&tmp_list)) {
child = list_first_entry(&tmp_list, struct mount, mnt_hash);
umount_tree(child, 0, &umount_list);
}
br_write_unlock(&vfsmount_lock);
release_mounts(&umount_list);
return ret;
}
static int propagate_one(struct mount *m)
{
struct mount *child;
int type;
/* skip ones added by this propagate_mnt() */
if (IS_MNT_NEW(m))
return 0;
/* 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) {
type = CL_MAKE_SHARED;
} else {
struct mount *n, *p;
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;
}
break;
}
}
type = CL_SLAVE;
/* beginning of peer group among the slaves? */
if (IS_MNT_SHARED(m))
type |= CL_MAKE_SHARED;
}
/* Notice when we are propagating across user namespaces */
if (m->mnt_ns->user_ns != user_ns)
type |= CL_UNPRIVILEGED;
child = copy_tree(last_source, last_source->mnt.mnt_root, type);
if (IS_ERR(child))
return PTR_ERR(child);
child->mnt.mnt_flags &= ~MNT_LOCKED;
mnt_set_mountpoint(m, mp, child);
last_dest = m;
last_source = child;
if (m->mnt_master != dest_master) {
read_seqlock_excl(&mount_lock);
SET_MNT_MARK(m->mnt_master);
read_sequnlock_excl(&mount_lock);
}
hlist_add_head(&child->mnt_hash, list);
return 0;
}
/*
* mount 'source_mnt' under the destination 'dest_mnt' at
* dentry 'dest_dentry'. And propagate that mount to
* all the peer and slave mounts of 'dest_mnt'.
* Link all the new mounts into a propagation tree headed at
* source_mnt. Also link all the new mounts using ->mnt_list
* headed at source_mnt's ->mnt_list
*
* @dest_mnt: destination mount.
* @dest_dentry: destination dentry.
* @source_mnt: source mount.
* @tree_list : list of heads of trees to be attached.
*/
int propagate_mnt(struct vfsmount *dest_mnt, struct dentry *dest_dentry,
struct vfsmount *source_mnt, struct list_head *tree_list)
{
struct vfsmount *m, *child;
int ret = 0;
struct vfsmount *prev_dest_mnt = dest_mnt;
struct vfsmount *prev_src_mnt = source_mnt;
LIST_HEAD(tmp_list);
LIST_HEAD(umount_list);
for (m = propagation_next(dest_mnt, dest_mnt); m;
m = propagation_next(m, dest_mnt)) {
int type;
struct vfsmount *source;
if (IS_MNT_NEW(m))
continue;
source = get_source(m, prev_dest_mnt, prev_src_mnt, &type);
if (!(child = copy_tree(source, source->mnt_root, type))) {
ret = -ENOMEM;
list_splice(tree_list, tmp_list.prev);
goto out;
}
if (is_subdir(dest_dentry, m->mnt_root)) {
mnt_set_mountpoint(m, dest_dentry, child);
list_add_tail(&child->mnt_hash, tree_list);
} else {
/*
* This can happen if the parent mount was bind mounted
* on some subdirectory of a shared/slave mount.
*/
list_add_tail(&child->mnt_hash, &tmp_list);
}
prev_dest_mnt = m;
prev_src_mnt = child;
}
out:
spin_lock(&vfsmount_lock);
while (!list_empty(&tmp_list)) {
child = list_entry(tmp_list.next, struct vfsmount, mnt_hash);
list_del_init(&child->mnt_hash);
umount_tree(child, 0, &umount_list);
}
spin_unlock(&vfsmount_lock);
release_mounts(&umount_list);
return ret;
}
int propagate_mnt(struct mount *dest_mnt, struct dentry *dest_dentry,
struct mount *source_mnt, struct list_head *tree_list)
{
struct mount *m, *child;
int ret = 0;
struct mount *prev_dest_mnt = dest_mnt;
struct mount *prev_src_mnt = source_mnt;
LIST_HEAD(tmp_list);
LIST_HEAD(umount_list);
for (m = propagation_next(dest_mnt, dest_mnt); m;
m = propagation_next(m, dest_mnt)) {
int type;
struct mount *source;
if (IS_MNT_NEW(m))
continue;
source = get_source(m, prev_dest_mnt, prev_src_mnt, &type);
if (!(child = copy_tree(source, source->mnt.mnt_root, type))) {
ret = -ENOMEM;
list_splice(tree_list, tmp_list.prev);
goto out;
}
if (is_subdir(dest_dentry, m->mnt.mnt_root)) {
mnt_set_mountpoint(m, dest_dentry, child);
list_add_tail(&child->mnt_hash, tree_list);
} else {
list_add_tail(&child->mnt_hash, &tmp_list);
}
prev_dest_mnt = m;
prev_src_mnt = child;
}
out:
br_write_lock(vfsmount_lock);
while (!list_empty(&tmp_list)) {
child = list_first_entry(&tmp_list, struct mount, mnt_hash);
umount_tree(child, 0, &umount_list);
}
br_write_unlock(vfsmount_lock);
release_mounts(&umount_list);
return ret;
}
/*
* get the next mount in the propagation tree.
* @m: the mount seen last
* @origin: the original mount from where the tree walk initiated
*
* Note that peer groups form contiguous segments of slave lists.
* We rely on that in get_source() to be able to find out if
* vfsmount found while iterating with propagation_next() is
* a peer of one we'd found earlier.
*/
static struct mount *propagation_next(struct mount *m,
struct mount *origin)
{
/* are there any slaves of this mount? */
if (!IS_MNT_NEW(m) && !list_empty(&m->mnt_slave_list))
return first_slave(m);
while (1) {
struct mount *master = m->mnt_master;
if (master == origin->mnt_master) {
struct mount *next = next_peer(m);
return (next == origin) ? NULL : next;
} else if (m->mnt_slave.next != &master->mnt_slave_list)
return next_slave(m);
/* back at master */
m = master;
}
}
