* Author : Ram Pai (linuxram@us.ibm.com)
*
*/
-#include <linux/namespace.h>
+#include <linux/mnt_namespace.h>
#include <linux/mount.h>
#include <linux/fs.h>
+#include "internal.h"
#include "pnode.h"
/* return the next shared peer mount of @p */
return list_entry(p->mnt_share.next, struct vfsmount, mnt_share);
}
+static inline struct vfsmount *first_slave(struct vfsmount *p)
+{
+ return list_entry(p->mnt_slave_list.next, struct vfsmount, mnt_slave);
+}
+
+static inline struct vfsmount *next_slave(struct vfsmount *p)
+{
+ return list_entry(p->mnt_slave.next, struct vfsmount, mnt_slave);
+}
+
+/*
+ * Return true if path is reachable from root
+ *
+ * namespace_sem is held, and mnt is attached
+ */
+static bool is_path_reachable(struct vfsmount *mnt, struct dentry *dentry,
+ const struct path *root)
+{
+ while (mnt != root->mnt && mnt->mnt_parent != mnt) {
+ dentry = mnt->mnt_mountpoint;
+ mnt = mnt->mnt_parent;
+ }
+ return mnt == root->mnt && is_subdir(dentry, root->dentry);
+}
+
+static struct vfsmount *get_peer_under_root(struct vfsmount *mnt,
+ struct mnt_namespace *ns,
+ const struct path *root)
+{
+ struct vfsmount *m = mnt;
+
+ do {
+ /* Check the namespace first for optimization */
+ if (m->mnt_ns == ns && is_path_reachable(m, m->mnt_root, root))
+ return m;
+
+ m = next_peer(m);
+ } while (m != mnt);
+
+ return NULL;
+}
+
+/*
+ * Get ID of closest dominating peer group having a representative
+ * under the given root.
+ *
+ * Caller must hold namespace_sem
+ */
+int get_dominating_id(struct vfsmount *mnt, const struct path *root)
+{
+ struct vfsmount *m;
+
+ for (m = mnt->mnt_master; m != NULL; m = m->mnt_master) {
+ struct vfsmount *d = get_peer_under_root(m, mnt->mnt_ns, root);
+ if (d)
+ return d->mnt_group_id;
+ }
+
+ return 0;
+}
+
+static int do_make_slave(struct vfsmount *mnt)
+{
+ struct vfsmount *peer_mnt = mnt, *master = mnt->mnt_master;
+ struct vfsmount *slave_mnt;
+
+ /*
+ * slave 'mnt' to a peer mount that has the
+ * same root dentry. If none is available than
+ * slave it to anything that is available.
+ */
+ while ((peer_mnt = next_peer(peer_mnt)) != mnt &&
+ peer_mnt->mnt_root != mnt->mnt_root) ;
+
+ if (peer_mnt == mnt) {
+ peer_mnt = next_peer(mnt);
+ if (peer_mnt == mnt)
+ peer_mnt = NULL;
+ }
+ if (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);
+ } else {
+ struct list_head *p = &mnt->mnt_slave_list;
+ while (!list_empty(p)) {
+ slave_mnt = list_first_entry(p,
+ struct vfsmount, mnt_slave);
+ list_del_init(&slave_mnt->mnt_slave);
+ slave_mnt->mnt_master = NULL;
+ }
+ }
+ mnt->mnt_master = master;
+ CLEAR_MNT_SHARED(mnt);
+ return 0;
+}
+
void change_mnt_propagation(struct vfsmount *mnt, int type)
{
if (type == MS_SHARED) {
set_mnt_shared(mnt);
- } else {
- list_del_init(&mnt->mnt_share);
- mnt->mnt_flags &= ~MNT_PNODE_MASK;
+ return;
+ }
+ do_make_slave(mnt);
+ if (type != MS_SLAVE) {
+ list_del_init(&mnt->mnt_slave);
+ mnt->mnt_master = NULL;
+ if (type == MS_UNBINDABLE)
+ mnt->mnt_flags |= MNT_UNBINDABLE;
+ else
+ mnt->mnt_flags &= ~MNT_UNBINDABLE;
}
}
static struct vfsmount *propagation_next(struct vfsmount *m,
struct vfsmount *origin)
{
- m = next_peer(m);
- if (m == origin)
- return NULL;
- return m;
+ /* 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 vfsmount *next;
+ struct vfsmount *master = m->mnt_master;
+
+ if (master == origin->mnt_master) {
+ 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;
+ }
+}
+
+/*
+ * 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;
+ *type = CL_PROPAGATION;
+
+ if (IS_MNT_SHARED(dest))
+ *type |= CL_MAKE_SHARED;
+
+ 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_SLAVE;
+ return last_src;
+ } else
+ return p_last_src;
}
/*
for (m = propagation_next(dest_mnt, dest_mnt); m;
m = propagation_next(m, dest_mnt)) {
- int type = CL_PROPAGATION;
+ int type;
+ struct vfsmount *source;
if (IS_MNT_NEW(m))
continue;
- if (IS_MNT_SHARED(m))
- type |= CL_MAKE_SHARED;
+ source = get_source(m, prev_dest_mnt, prev_src_mnt, &type);
- if (!(child = copy_tree(source_mnt, source_mnt->mnt_root,
- type))) {
+ if (!(child = copy_tree(source, source->mnt_root, type))) {
ret = -ENOMEM;
list_splice(tree_list, tmp_list.prev);
goto out;
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, &umount_list);
+ child = list_first_entry(&tmp_list, struct vfsmount, mnt_hash);
+ umount_tree(child, 0, &umount_list);
}
spin_unlock(&vfsmount_lock);
release_mounts(&umount_list);
return ret;
}
+
+/*
+ * return true if the refcount is greater than count
+ */
+static inline int do_refcount_check(struct vfsmount *mnt, int count)
+{
+ int mycount = atomic_read(&mnt->mnt_count) - mnt->mnt_ghosts;
+ return (mycount > count);
+}
+
+/*
+ * check if the mount 'mnt' can be unmounted successfully.
+ * @mnt: the mount to be checked for unmount
+ * NOTE: unmounting 'mnt' would naturally propagate to all
+ * other mounts its parent propagates to.
+ * Check if any of these mounts that **do not have submounts**
+ * have more references than 'refcnt'. If so return busy.
+ */
+int propagate_mount_busy(struct vfsmount *mnt, int refcnt)
+{
+ struct vfsmount *m, *child;
+ struct vfsmount *parent = mnt->mnt_parent;
+ int ret = 0;
+
+ if (mnt == parent)
+ return do_refcount_check(mnt, refcnt);
+
+ /*
+ * quickly check if the current mount can be unmounted.
+ * If not, we don't have to go checking for all other
+ * mounts
+ */
+ if (!list_empty(&mnt->mnt_mounts) || do_refcount_check(mnt, refcnt))
+ return 1;
+
+ for (m = propagation_next(parent, parent); m;
+ m = propagation_next(m, parent)) {
+ child = __lookup_mnt(m, mnt->mnt_mountpoint, 0);
+ if (child && list_empty(&child->mnt_mounts) &&
+ (ret = do_refcount_check(child, 1)))
+ break;
+ }
+ return ret;
+}
+
+/*
+ * NOTE: unmounting 'mnt' naturally propagates to all other mounts its
+ * parent propagates to.
+ */
+static void __propagate_umount(struct vfsmount *mnt)
+{
+ struct vfsmount *parent = mnt->mnt_parent;
+ struct vfsmount *m;
+
+ BUG_ON(parent == mnt);
+
+ for (m = propagation_next(parent, parent); m;
+ m = propagation_next(m, parent)) {
+
+ struct vfsmount *child = __lookup_mnt(m,
+ mnt->mnt_mountpoint, 0);
+ /*
+ * umount the child only if the child has no
+ * other children
+ */
+ if (child && list_empty(&child->mnt_mounts))
+ list_move_tail(&child->mnt_hash, &mnt->mnt_hash);
+ }
+}
+
+/*
+ * collect all mounts that receive propagation from the mount in @list,
+ * and return these additional mounts in the same list.
+ * @list: the list of mounts to be unmounted.
+ */
+int propagate_umount(struct list_head *list)
+{
+ struct vfsmount *mnt;
+
+ list_for_each_entry(mnt, list, mnt_hash)
+ __propagate_umount(mnt);
+ return 0;
+}
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff