5 files changed, 106 insertions, 118 deletions

diff --git a/fs/mount.h b/fs/mount.h
index a14f762b3f29..4a42fc68f4cc 100644
--- a/fs/mount.h
+++ b/fs/mount.h
@@ -8,19 +8,13 @@
 struct mnt_namespace {
 	struct ns_common	ns;
 	struct mount *	root;
-	/*
-	 * Traversal and modification of .list is protected by either
-	 * - taking namespace_sem for write, OR
-	 * - taking namespace_sem for read AND taking .ns_lock.
-	 */
-	struct list_head	list;
-	spinlock_t		ns_lock;
+	struct rb_root		mounts; /* Protected by namespace_sem */
 	struct user_namespace	*user_ns;
 	struct ucounts		*ucounts;
 	u64			seq;	/* Sequence number to prevent loops */
 	wait_queue_head_t poll;
 	u64 event;
-	unsigned int		mounts; /* # of mounts in the namespace */
+	unsigned int		nr_mounts; /* # of mounts in the namespace */
 	unsigned int		pending_mounts;
 } __randomize_layout;
 
@@ -55,7 +49,10 @@ struct mount {
 	struct list_head mnt_child;	/* and going through their mnt_child */
 	struct list_head mnt_instance;	/* mount instance on sb->s_mounts */
 	const char *mnt_devname;	/* Name of device e.g. /dev/dsk/hda1 */
-	struct list_head mnt_list;
+	union {
+		struct rb_node mnt_node;	/* Under ns->mounts */
+		struct list_head mnt_list;
+	};
 	struct list_head mnt_expire;	/* link in fs-specific expiry list */
 	struct list_head mnt_share;	/* circular list of shared mounts */
 	struct list_head mnt_slave_list;/* list of slave mounts */
@@ -128,7 +125,6 @@ struct proc_mounts {
 	struct mnt_namespace *ns;
 	struct path root;
 	int (*show)(struct seq_file *, struct vfsmount *);
-	struct mount cursor;
 };
 
 extern const struct seq_operations mounts_op;
@@ -147,4 +143,12 @@ static inline bool is_anon_ns(struct mnt_namespace *ns)
 	return ns->seq == 0;
 }
 
+static inline void move_from_ns(struct mount *mnt, struct list_head *dt_list)
+{
+	WARN_ON(!(mnt->mnt.mnt_flags & MNT_ONRB));
+	mnt->mnt.mnt_flags &= ~MNT_ONRB;
+	rb_erase(&mnt->mnt_node, &mnt->mnt_ns->mounts);
+	list_add_tail(&mnt->mnt_list, dt_list);
+}
+
 extern void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor);
diff --git a/fs/namespace.c b/fs/namespace.c
index 0bcba81402b5..bbe94096e262 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -734,21 +734,6 @@ struct vfsmount *lookup_mnt(const struct path *path)
 	return m;
 }
 
-static inline void lock_ns_list(struct mnt_namespace *ns)
-{
-	spin_lock(&ns->ns_lock);
-}
-
-static inline void unlock_ns_list(struct mnt_namespace *ns)
-{
-	spin_unlock(&ns->ns_lock);
-}
-
-static inline bool mnt_is_cursor(struct mount *mnt)
-{
-	return mnt->mnt.mnt_flags & MNT_CURSOR;
-}
-
 /*
  * __is_local_mountpoint - Test to see if dentry is a mountpoint in the
  *                         current mount namespace.
@@ -767,19 +752,15 @@ static inline bool mnt_is_cursor(struct mount *mnt)
 bool __is_local_mountpoint(struct dentry *dentry)
 {
 	struct mnt_namespace *ns = current->nsproxy->mnt_ns;
-	struct mount *mnt;
+	struct mount *mnt, *n;
 	bool is_covered = false;
 
 	down_read(&namespace_sem);
-	lock_ns_list(ns);
-	list_for_each_entry(mnt, &ns->list, mnt_list) {
-		if (mnt_is_cursor(mnt))
-			continue;
+	rbtree_postorder_for_each_entry_safe(mnt, n, &ns->mounts, mnt_node) {
 		is_covered = (mnt->mnt_mountpoint == dentry);
 		if (is_covered)
 			break;
 	}
-	unlock_ns_list(ns);
 	up_read(&namespace_sem);
 
 	return is_covered;
@@ -1026,6 +1007,30 @@ void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct m
 	mnt_add_count(old_parent, -1);
 }
 
+static inline struct mount *node_to_mount(struct rb_node *node)
+{
+	return rb_entry(node, struct mount, mnt_node);
+}
+
+static void mnt_add_to_ns(struct mnt_namespace *ns, struct mount *mnt)
+{
+	struct rb_node **link = &ns->mounts.rb_node;
+	struct rb_node *parent = NULL;
+
+	WARN_ON(mnt->mnt.mnt_flags & MNT_ONRB);
+	mnt->mnt_ns = ns;
+	while (*link) {
+		parent = *link;
+		if (mnt->mnt_id_unique < node_to_mount(parent)->mnt_id_unique)
+			link = &parent->rb_left;
+		else
+			link = &parent->rb_right;
+	}
+	rb_link_node(&mnt->mnt_node, parent, link);
+	rb_insert_color(&mnt->mnt_node, &ns->mounts);
+	mnt->mnt.mnt_flags |= MNT_ONRB;
+}
+
 /*
  * vfsmount lock must be held for write
  */
@@ -1039,12 +1044,13 @@ static void commit_tree(struct mount *mnt)
 	BUG_ON(parent == mnt);
 
 	list_add_tail(&head, &mnt->mnt_list);
-	list_for_each_entry(m, &head, mnt_list)
-		m->mnt_ns = n;
+	while (!list_empty(&head)) {
+		m = list_first_entry(&head, typeof(*m), mnt_list);
+		list_del(&m->mnt_list);
 
-	list_splice(&head, n->list.prev);
-
-	n->mounts += n->pending_mounts;
+		mnt_add_to_ns(n, m);
+	}
+	n->nr_mounts += n->pending_mounts;
 	n->pending_mounts = 0;
 
 	__attach_mnt(mnt, parent);
@@ -1192,7 +1198,7 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
 	}
 
 	mnt->mnt.mnt_flags = old->mnt.mnt_flags;
-	mnt->mnt.mnt_flags &= ~(MNT_WRITE_HOLD|MNT_MARKED|MNT_INTERNAL);
+	mnt->mnt.mnt_flags &= ~(MNT_WRITE_HOLD|MNT_MARKED|MNT_INTERNAL|MNT_ONRB);
 
 	atomic_inc(&sb->s_active);
 	mnt->mnt.mnt_idmap = mnt_idmap_get(mnt_idmap(&old->mnt));
@@ -1417,65 +1423,57 @@ struct vfsmount *mnt_clone_internal(const struct path *path)
 	return &p->mnt;
 }
 
-#ifdef CONFIG_PROC_FS
-static struct mount *mnt_list_next(struct mnt_namespace *ns,
-				   struct list_head *p)
+/*
+ * Returns the mount which either has the specified mnt_id, or has the next
+ * smallest id afer the specified one.
+ */
+static struct mount *mnt_find_id_at(struct mnt_namespace *ns, u64 mnt_id)
 {
-	struct mount *mnt, *ret = NULL;
+	struct rb_node *node = ns->mounts.rb_node;
+	struct mount *ret = NULL;
 
-	lock_ns_list(ns);
-	list_for_each_continue(p, &ns->list) {
-		mnt = list_entry(p, typeof(*mnt), mnt_list);
-		if (!mnt_is_cursor(mnt)) {
-			ret = mnt;
-			break;
+	while (node) {
+		struct mount *m = node_to_mount(node);
+
+		if (mnt_id <= m->mnt_id_unique) {
+			ret = node_to_mount(node);
+			if (mnt_id == m->mnt_id_unique)
+				break;
+			node = node->rb_left;
+		} else {
+			node = node->rb_right;
 		}
 	}
-	unlock_ns_list(ns);
-
 	return ret;
 }
 
+#ifdef CONFIG_PROC_FS
+
 /* iterator; we want it to have access to namespace_sem, thus here... */
 static void *m_start(struct seq_file *m, loff_t *pos)
 {
 	struct proc_mounts *p = m->private;
-	struct list_head *prev;
 
 	down_read(&namespace_sem);
-	if (!*pos) {
-		prev = &p->ns->list;
-	} else {
-		prev = &p->cursor.mnt_list;
 
-		/* Read after we'd reached the end? */
-		if (list_empty(prev))
-			return NULL;
-	}
-
-	return mnt_list_next(p->ns, prev);
+	return mnt_find_id_at(p->ns, *pos);
 }
 
 static void *m_next(struct seq_file *m, void *v, loff_t *pos)
 {
-	struct proc_mounts *p = m->private;
-	struct mount *mnt = v;
+	struct mount *next = NULL, *mnt = v;
+	struct rb_node *node = rb_next(&mnt->mnt_node);
 
 	++*pos;
-	return mnt_list_next(p->ns, &mnt->mnt_list);
+	if (node) {
+		next = node_to_mount(node);
+		*pos = next->mnt_id_unique;
+	}
+	return next;
 }
 
 static void m_stop(struct seq_file *m, void *v)
 {
-	struct proc_mounts *p = m->private;
-	struct mount *mnt = v;
-
-	lock_ns_list(p->ns);
-	if (mnt)
-		list_move_tail(&p->cursor.mnt_list, &mnt->mnt_list);
-	else
-		list_del_init(&p->cursor.mnt_list);
-	unlock_ns_list(p->ns);
 	up_read(&namespace_sem);
 }
 
@@ -1493,14 +1491,6 @@ const struct seq_operations mounts_op = {
 	.show	= m_show,
 };
 
-void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor)
-{
-	down_read(&namespace_sem);
-	lock_ns_list(ns);
-	list_del(&cursor->mnt_list);
-	unlock_ns_list(ns);
-	up_read(&namespace_sem);
-}
 #endif  /* CONFIG_PROC_FS */
 
 /**
@@ -1642,7 +1632,10 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
 	/* Gather the mounts to umount */
 	for (p = mnt; p; p = next_mnt(p, mnt)) {
 		p->mnt.mnt_flags |= MNT_UMOUNT;
-		list_move(&p->mnt_list, &tmp_list);
+		if (p->mnt.mnt_flags & MNT_ONRB)
+			move_from_ns(p, &tmp_list);
+		else
+			list_move(&p->mnt_list, &tmp_list);
 	}
 
 	/* Hide the mounts from mnt_mounts */
@@ -1662,7 +1655,7 @@ static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
 		list_del_init(&p->mnt_list);
 		ns = p->mnt_ns;
 		if (ns) {
-			ns->mounts--;
+			ns->nr_mounts--;
 			__touch_mnt_namespace(ns);
 		}
 		p->mnt_ns = NULL;
@@ -1788,14 +1781,16 @@ static int do_umount(struct mount *mnt, int flags)
 
 	event++;
 	if (flags & MNT_DETACH) {
-		if (!list_empty(&mnt->mnt_list))
+		if (mnt->mnt.mnt_flags & MNT_ONRB ||
+		    !list_empty(&mnt->mnt_list))
 			umount_tree(mnt, UMOUNT_PROPAGATE);
 		retval = 0;
 	} else {
 		shrink_submounts(mnt);
 		retval = -EBUSY;
 		if (!propagate_mount_busy(mnt, 2)) {
-			if (!list_empty(&mnt->mnt_list))
+			if (mnt->mnt.mnt_flags & MNT_ONRB ||
+			    !list_empty(&mnt->mnt_list))
 				umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC);
 			retval = 0;
 		}
@@ -2213,9 +2208,9 @@ int count_mounts(struct mnt_namespace *ns, struct mount *mnt)
 	unsigned int mounts = 0;
 	struct mount *p;
 
-	if (ns->mounts >= max)
+	if (ns->nr_mounts >= max)
 		return -ENOSPC;
-	max -= ns->mounts;
+	max -= ns->nr_mounts;
 	if (ns->pending_mounts >= max)
 		return -ENOSPC;
 	max -= ns->pending_mounts;
@@ -2359,8 +2354,12 @@ static int attach_recursive_mnt(struct mount *source_mnt,
 		touch_mnt_namespace(source_mnt->mnt_ns);
 	} else {
 		if (source_mnt->mnt_ns) {
+			LIST_HEAD(head);
+
 			/* move from anon - the caller will destroy */
-			list_del_init(&source_mnt->mnt_ns->list);
+			for (p = source_mnt; p; p = next_mnt(p, source_mnt))
+				move_from_ns(p, &head);
+			list_del_init(&head);
 		}
 		if (beneath)
 			mnt_set_mountpoint_beneath(source_mnt, top_mnt, smp);
@@ -2671,11 +2670,10 @@ static struct file *open_detached_copy(struct path *path, bool recursive)
 
 	lock_mount_hash();
 	for (p = mnt; p; p = next_mnt(p, mnt)) {
-		p->mnt_ns = ns;
-		ns->mounts++;
+		mnt_add_to_ns(ns, p);
+		ns->nr_mounts++;
 	}
 	ns->root = mnt;
-	list_add_tail(&ns->list, &mnt->mnt_list);
 	mntget(&mnt->mnt);
 	unlock_mount_hash();
 	namespace_unlock();
@@ -3738,9 +3736,8 @@ static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns, bool a
 	if (!anon)
 		new_ns->seq = atomic64_add_return(1, &mnt_ns_seq);
 	refcount_set(&new_ns->ns.count, 1);
-	INIT_LIST_HEAD(&new_ns->list);
+	new_ns->mounts = RB_ROOT;
 	init_waitqueue_head(&new_ns->poll);
-	spin_lock_init(&new_ns->ns_lock);
 	new_ns->user_ns = get_user_ns(user_ns);
 	new_ns->ucounts = ucounts;
 	return new_ns;
@@ -3787,7 +3784,6 @@ struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
 		unlock_mount_hash();
 	}
 	new_ns->root = new;
-	list_add_tail(&new_ns->list, &new->mnt_list);
 
 	/*
 	 * Second pass: switch the tsk->fs->* elements and mark new vfsmounts
@@ -3797,8 +3793,8 @@ struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns,
 	p = old;
 	q = new;
 	while (p) {
-		q->mnt_ns = new_ns;
-		new_ns->mounts++;
+		mnt_add_to_ns(new_ns, q);
+		new_ns->nr_mounts++;
 		if (new_fs) {
 			if (&p->mnt == new_fs->root.mnt) {
 				new_fs->root.mnt = mntget(&q->mnt);
@@ -3840,10 +3836,9 @@ struct dentry *mount_subtree(struct vfsmount *m, const char *name)
 		mntput(m);
 		return ERR_CAST(ns);
 	}
-	mnt->mnt_ns = ns;
 	ns->root = mnt;
-	ns->mounts++;
-	list_add(&mnt->mnt_list, &ns->list);
+	ns->nr_mounts++;
+	mnt_add_to_ns(ns, mnt);
 
 	err = vfs_path_lookup(m->mnt_root, m,
 			name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path);
@@ -4021,10 +4016,9 @@ SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags,
 		goto err_path;
 	}
 	mnt = real_mount(newmount.mnt);
-	mnt->mnt_ns = ns;
 	ns->root = mnt;
-	ns->mounts = 1;
-	list_add(&mnt->mnt_list, &ns->list);
+	ns->nr_mounts = 1;
+	mnt_add_to_ns(ns, mnt);
 	mntget(newmount.mnt);
 
 	/* Attach to an apparent O_PATH fd with a note that we need to unmount
@@ -4695,10 +4689,9 @@ static void __init init_mount_tree(void)
 	if (IS_ERR(ns))
 		panic("Can't allocate initial namespace");
 	m = real_mount(mnt);
-	m->mnt_ns = ns;
 	ns->root = m;
-	ns->mounts = 1;
-	list_add(&m->mnt_list, &ns->list);
+	ns->nr_mounts = 1;
+	mnt_add_to_ns(ns, m);
 	init_task.nsproxy->mnt_ns = ns;
 	get_mnt_ns(ns);
 
@@ -4825,18 +4818,14 @@ static bool mnt_already_visible(struct mnt_namespace *ns,
 				int *new_mnt_flags)
 {
 	int new_flags = *new_mnt_flags;
-	struct mount *mnt;
+	struct mount *mnt, *n;
 	bool visible = false;
 
 	down_read(&namespace_sem);
-	lock_ns_list(ns);
-	list_for_each_entry(mnt, &ns->list, mnt_list) {
+	rbtree_postorder_for_each_entry_safe(mnt, n, &ns->mounts, mnt_node) {
 		struct mount *child;
 		int mnt_flags;
 
-		if (mnt_is_cursor(mnt))
-			continue;
-
 		if (mnt->mnt.mnt_sb->s_type != sb->s_type)
 			continue;
 
@@ -4884,7 +4873,6 @@ static bool mnt_already_visible(struct mnt_namespace *ns,
 	next:	;
 	}
 found:
-	unlock_ns_list(ns);
 	up_read(&namespace_sem);
 	return visible;
 }
diff --git a/fs/pnode.c b/fs/pnode.c
index e4d0340393d5..a799e0315cc9 100644
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -468,7 +468,7 @@ static void umount_one(struct mount *mnt, struct list_head *to_umount)
 	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);
+	move_from_ns(mnt, to_umount);
 }
 
 /*
diff --git a/fs/proc_namespace.c b/fs/proc_namespace.c
index 250eb5bf7b52..73d2274d5f59 100644
--- a/fs/proc_namespace.c
+++ b/fs/proc_namespace.c
@@ -283,8 +283,6 @@ static int mounts_open_common(struct inode *inode, struct file *file,
 	p->ns = ns;
 	p->root = root;
 	p->show = show;
-	INIT_LIST_HEAD(&p->cursor.mnt_list);
-	p->cursor.mnt.mnt_flags = MNT_CURSOR;
 
 	return 0;
 
@@ -301,7 +299,6 @@ static int mounts_release(struct inode *inode, struct file *file)
 	struct seq_file *m = file->private_data;
 	struct proc_mounts *p = m->private;
 	path_put(&p->root);
-	mnt_cursor_del(p->ns, &p->cursor);
 	put_mnt_ns(p->ns);
 	return seq_release_private(inode, file);
 }
diff --git a/include/linux/mount.h b/include/linux/mount.h
index ac3dd2876197..c34c18b4e8f3 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -50,8 +50,7 @@ struct path;
 #define MNT_ATIME_MASK (MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME )
 
 #define MNT_INTERNAL_FLAGS (MNT_SHARED | MNT_WRITE_HOLD | MNT_INTERNAL | \
-			    MNT_DOOMED | MNT_SYNC_UMOUNT | MNT_MARKED | \
-			    MNT_CURSOR)
+			    MNT_DOOMED | MNT_SYNC_UMOUNT | MNT_MARKED | MNT_ONRB)
 
 #define MNT_INTERNAL	0x4000
 
@@ -65,7 +64,7 @@ struct path;
 #define MNT_SYNC_UMOUNT		0x2000000
 #define MNT_MARKED		0x4000000
 #define MNT_UMOUNT		0x8000000
-#define MNT_CURSOR		0x10000000
+#define MNT_ONRB		0x10000000
 
 struct vfsmount {
 	struct dentry *mnt_root;	/* root of the mounted tree */