vfs: now it can be done - make mnt_parent point to struct mount

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/dcache.c

@@ -2452,6 +2452,7 @@ static int prepend_path(const struct path *path,
 {
 	struct dentry *dentry = path->dentry;
 	struct vfsmount *vfsmnt = path->mnt;
+	struct mount *mnt = real_mount(vfsmnt);
 	bool slash = false;
 	int error = 0;
 
@@ -2460,12 +2461,12 @@ static int prepend_path(const struct path *path,
 		struct dentry * parent;
 
 		if (dentry == vfsmnt->mnt_root || IS_ROOT(dentry)) {
-			struct mount *mnt = real_mount(vfsmnt);
 			/* Global root? */
 			if (!mnt_has_parent(mnt))
 				goto global_root;
-			dentry = vfsmnt->mnt_mountpoint;
-			vfsmnt = mnt->mnt_parent;
+			dentry = mnt->mnt.mnt_mountpoint;
+			mnt = mnt->mnt_parent;
+			vfsmnt = &mnt->mnt;
 			continue;
 		}
 		parent = dentry->d_parent;

fs/mount.h

@@ -2,7 +2,7 @@
 
 struct mount {
 	struct list_head mnt_hash;
-	struct vfsmount *mnt_parent;
+	struct mount *mnt_parent;
 	struct vfsmount mnt;
 };
 
@@ -13,7 +13,7 @@ static inline struct mount *real_mount(struct vfsmount *mnt)
 
 static inline int mnt_has_parent(struct mount *mnt)
 {
-	return &mnt->mnt != mnt->mnt_parent;
+	return mnt != mnt->mnt_parent;
 }
 
 extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *, int);

fs/namei.c

@@ -677,36 +677,38 @@ follow_link(struct path *link, struct nameidata *nd, void **p)
 
 static int follow_up_rcu(struct path *path)
 {
-	struct vfsmount *parent;
+	struct mount *mnt = real_mount(path->mnt);
+	struct mount *parent;
 	struct dentry *mountpoint;
 
-	parent = real_mount(path->mnt)->mnt_parent;
-	if (parent == path->mnt)
+	parent = mnt->mnt_parent;
+	if (&parent->mnt == path->mnt)
 		return 0;
-	mountpoint = path->mnt->mnt_mountpoint;
+	mountpoint = mnt->mnt.mnt_mountpoint;
 	path->dentry = mountpoint;
-	path->mnt = parent;
+	path->mnt = &parent->mnt;
 	return 1;
 }
 
 int follow_up(struct path *path)
 {
-	struct vfsmount *parent;
+	struct mount *mnt = real_mount(path->mnt);
+	struct mount *parent;
 	struct dentry *mountpoint;
 
 	br_read_lock(vfsmount_lock);
-	parent = real_mount(path->mnt)->mnt_parent;
-	if (parent == path->mnt) {
+	parent = mnt->mnt_parent;
+	if (&parent->mnt == path->mnt) {
 		br_read_unlock(vfsmount_lock);
 		return 0;
 	}
-	mntget(parent);
-	mountpoint = dget(path->mnt->mnt_mountpoint);
+	mntget(&parent->mnt);
+	mountpoint = dget(mnt->mnt.mnt_mountpoint);
 	br_read_unlock(vfsmount_lock);
 	dput(path->dentry);
 	path->dentry = mountpoint;
 	mntput(path->mnt);
-	path->mnt = parent;
+	path->mnt = &parent->mnt;
 	return 1;
 }
 

fs/namespace.c

@@ -476,7 +476,7 @@ struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry,
 		if (tmp == head)
 			break;
 		p = list_entry(tmp, struct mount, mnt_hash);
-		if (p->mnt_parent == mnt && p->mnt.mnt_mountpoint == dentry) {
+		if (&p->mnt_parent->mnt == mnt && p->mnt.mnt_mountpoint == dentry) {
 			found = p;
 			break;
 		}
@@ -558,8 +558,8 @@ static void dentry_reset_mounted(struct dentry *dentry)
 static void detach_mnt(struct mount *mnt, struct path *old_path)
 {
 	old_path->dentry = mnt->mnt.mnt_mountpoint;
-	old_path->mnt = mnt->mnt_parent;
-	mnt->mnt_parent = &mnt->mnt;
+	old_path->mnt = &mnt->mnt_parent->mnt;
+	mnt->mnt_parent = mnt;
 	mnt->mnt.mnt_mountpoint = mnt->mnt.mnt_root;
 	list_del_init(&mnt->mnt.mnt_child);
 	list_del_init(&mnt->mnt_hash);
@@ -572,7 +572,7 @@ static void detach_mnt(struct mount *mnt, struct path *old_path)
 void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
 			struct mount *child_mnt)
 {
-	child_mnt->mnt_parent = mntget(mnt);
+	child_mnt->mnt_parent = real_mount(mntget(mnt));
 	child_mnt->mnt.mnt_mountpoint = dget(dentry);
 	spin_lock(&dentry->d_lock);
 	dentry->d_flags |= DCACHE_MOUNTED;
@@ -610,12 +610,12 @@ static inline void __mnt_make_shortterm(struct vfsmount *mnt)
  */
 static void commit_tree(struct mount *mnt)
 {
-	struct vfsmount *parent = mnt->mnt_parent;
+	struct mount *parent = mnt->mnt_parent;
 	struct vfsmount *m;
 	LIST_HEAD(head);
-	struct mnt_namespace *n = parent->mnt_ns;
+	struct mnt_namespace *n = parent->mnt.mnt_ns;
 
-	BUG_ON(parent == &mnt->mnt);
+	BUG_ON(parent == mnt);
 
 	list_add_tail(&head, &mnt->mnt.mnt_list);
 	list_for_each_entry(m, &head, mnt_list) {
@@ -626,8 +626,8 @@ static void commit_tree(struct mount *mnt)
 	list_splice(&head, n->list.prev);
 
 	list_add_tail(&mnt->mnt_hash, mount_hashtable +
-				hash(parent, mnt->mnt.mnt_mountpoint));
-	list_add_tail(&mnt->mnt.mnt_child, &parent->mnt_mounts);
+				hash(&parent->mnt, mnt->mnt.mnt_mountpoint));
+	list_add_tail(&mnt->mnt.mnt_child, &parent->mnt.mnt_mounts);
 	touch_mnt_namespace(n);
 }
 
@@ -639,9 +639,9 @@ static struct mount *next_mnt(struct mount *p, struct vfsmount *root)
 			if (&p->mnt == root)
 				return NULL;
 			next = p->mnt.mnt_child.next;
-			if (next != &p->mnt_parent->mnt_mounts)
+			if (next != &p->mnt_parent->mnt.mnt_mounts)
 				break;
-			p = real_mount(p->mnt_parent);
+			p = p->mnt_parent;
 		}
 	}
 	return list_entry(next, struct mount, mnt.mnt_child);
@@ -682,7 +682,7 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void
 	mnt->mnt.mnt_root = root;
 	mnt->mnt.mnt_sb = root->d_sb;
 	mnt->mnt.mnt_mountpoint = mnt->mnt.mnt_root;
-	mnt->mnt_parent = &mnt->mnt;
+	mnt->mnt_parent = mnt;
 	return &mnt->mnt;
 }
 EXPORT_SYMBOL_GPL(vfs_kern_mount);
@@ -710,7 +710,7 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root,
 		mnt->mnt.mnt_sb = sb;
 		mnt->mnt.mnt_root = dget(root);
 		mnt->mnt.mnt_mountpoint = mnt->mnt.mnt_root;
-		mnt->mnt_parent = &mnt->mnt;
+		mnt->mnt_parent = mnt;
 
 		if (flag & CL_SLAVE) {
 			list_add(&mnt->mnt.mnt_slave, &old->mnt.mnt_slave_list);
@@ -1027,7 +1027,7 @@ static int show_mountinfo(struct seq_file *m, void *v)
 	struct path root = p->root;
 	int err = 0;
 
-	seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, r->mnt_parent->mnt_id,
+	seq_printf(m, "%i %i %u:%u ", mnt->mnt_id, r->mnt_parent->mnt.mnt_id,
 		   MAJOR(sb->s_dev), MINOR(sb->s_dev));
 	if (sb->s_op->show_path)
 		err = sb->s_op->show_path(m, mnt);
@@ -1202,9 +1202,9 @@ void release_mounts(struct list_head *head)
 
 			br_write_lock(vfsmount_lock);
 			dentry = mnt->mnt.mnt_mountpoint;
-			m = mnt->mnt_parent;
+			m = &mnt->mnt_parent->mnt;
 			mnt->mnt.mnt_mountpoint = mnt->mnt.mnt_root;
-			mnt->mnt_parent = &mnt->mnt;
+			mnt->mnt_parent = mnt;
 			m->mnt_ghosts--;
 			br_write_unlock(vfsmount_lock);
 			dput(dentry);
@@ -1237,7 +1237,7 @@ void umount_tree(struct mount *mnt, int propagate, struct list_head *kill)
 		__mnt_make_shortterm(&p->mnt);
 		list_del_init(&p->mnt.mnt_child);
 		if (mnt_has_parent(p)) {
-			p->mnt_parent->mnt_ghosts++;
+			p->mnt_parent->mnt.mnt_ghosts++;
 			dentry_reset_mounted(p->mnt.mnt_mountpoint);
 		}
 		change_mnt_propagation(p, MS_PRIVATE);
@@ -1435,9 +1435,9 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry,
 				s = skip_mnt_tree(s);
 				continue;
 			}
-			while (p != real_mount(s->mnt_parent)) {
-				p = real_mount(p->mnt_parent);
-				q = real_mount(q->mnt_parent);
+			while (p != s->mnt_parent) {
+				p = p->mnt_parent;
+				q = q->mnt_parent;
 			}
 			p = s;
 			path.mnt = &q->mnt;
@@ -1899,7 +1899,7 @@ static int do_move_mount(struct path *path, char *old_name)
 	/*
 	 * Don't move a mount residing in a shared parent.
 	 */
-	if (IS_MNT_SHARED(old->mnt_parent))
+	if (IS_MNT_SHARED(&old->mnt_parent->mnt))
 		goto out1;
 	/*
 	 * Don't move a mount tree containing unbindable mounts to a destination
@@ -1909,7 +1909,7 @@ static int do_move_mount(struct path *path, char *old_name)
 	    tree_contains_unbindable(old))
 		goto out1;
 	err = -ELOOP;
-	for (p = real_mount(path->mnt); mnt_has_parent(p); p = real_mount(p->mnt_parent))
+	for (p = real_mount(path->mnt); mnt_has_parent(p); p = p->mnt_parent)
 		if (p == old)
 			goto out1;
 
@@ -2159,7 +2159,7 @@ static int select_submounts(struct mount *parent, struct list_head *graveyard)
 	 */
 	if (this_parent != parent) {
 		next = this_parent->mnt.mnt_child.next;
-		this_parent = real_mount(this_parent->mnt_parent);
+		this_parent = this_parent->mnt_parent;
 		goto resume;
 	}
 	return found;
@@ -2565,7 +2565,7 @@ bool is_path_reachable(struct mount *mnt, struct dentry *dentry,
 {
 	while (&mnt->mnt != root->mnt && mnt_has_parent(mnt)) {
 		dentry = mnt->mnt.mnt_mountpoint;
-		mnt = real_mount(mnt->mnt_parent);
+		mnt = mnt->mnt_parent;
 	}
 	return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry);
 }
@@ -2636,8 +2636,8 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,
 	new_mnt = real_mount(new.mnt);
 	root_mnt = real_mount(root.mnt);
 	if (IS_MNT_SHARED(old.mnt) ||
-		IS_MNT_SHARED(new_mnt->mnt_parent) ||
-		IS_MNT_SHARED(root_mnt->mnt_parent))
+		IS_MNT_SHARED(&new_mnt->mnt_parent->mnt) ||
+		IS_MNT_SHARED(&root_mnt->mnt_parent->mnt))
 		goto out4;
 	if (!check_mnt(root.mnt) || !check_mnt(new.mnt))
 		goto out4;

fs/pnode.c

@@ -292,10 +292,10 @@ int propagate_mount_busy(struct mount *mnt, int refcnt)
 {
 	struct vfsmount *m;
 	struct mount *child;
-	struct vfsmount *parent = mnt->mnt_parent;
+	struct mount *parent = mnt->mnt_parent;
 	int ret = 0;
 
-	if (&mnt->mnt == parent)
+	if (mnt == parent)
 		return do_refcount_check(mnt, refcnt);
 
 	/*
@@ -306,8 +306,8 @@ int propagate_mount_busy(struct mount *mnt, int refcnt)
 	if (!list_empty(&mnt->mnt.mnt_mounts) || do_refcount_check(mnt, refcnt))
 		return 1;
 
-	for (m = propagation_next(parent, parent); m;
-	     		m = propagation_next(m, parent)) {
+	for (m = propagation_next(&parent->mnt, &parent->mnt); m;
+	     		m = propagation_next(m, &parent->mnt)) {
 		child = __lookup_mnt(m, mnt->mnt.mnt_mountpoint, 0);
 		if (child && list_empty(&child->mnt.mnt_mounts) &&
 		    (ret = do_refcount_check(child, 1)))
@@ -322,13 +322,13 @@ int propagate_mount_busy(struct mount *mnt, int refcnt)
  */
 static void __propagate_umount(struct mount *mnt)
 {
-	struct vfsmount *parent = mnt->mnt_parent;
+	struct mount *parent = mnt->mnt_parent;
 	struct vfsmount *m;
 
-	BUG_ON(parent == &mnt->mnt);
+	BUG_ON(parent == mnt);
 
-	for (m = propagation_next(parent, parent); m;
-			m = propagation_next(m, parent)) {
+	for (m = propagation_next(&parent->mnt, &parent->mnt); m;
+			m = propagation_next(m, &parent->mnt)) {
 
 		struct mount *child = __lookup_mnt(m,
 					mnt->mnt.mnt_mountpoint, 0);