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Commit 1a390689 authored by Al Viro's avatar Al Viro
Browse files

[PATCH] reduce stack footprint in namespace.c 



A lot of places misuse struct nameidata when they need struct path.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 3085354d

fs/namespace.c

+37 −35
Original line number Diff line number Diff line
@@ -155,15 +155,15 @@ static void __touch_mnt_namespace(struct mnt_namespace *ns) 
	}

}



static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd)

static void detach_mnt(struct vfsmount *mnt, struct path *old_path)

{

	old_nd->path.dentry = mnt->mnt_mountpoint;

	old_nd->path.mnt = mnt->mnt_parent;

	old_path->dentry = mnt->mnt_mountpoint;

	old_path->mnt = mnt->mnt_parent;

	mnt->mnt_parent = mnt;

	mnt->mnt_mountpoint = mnt->mnt_root;

	list_del_init(&mnt->mnt_child);

	list_del_init(&mnt->mnt_hash);

	old_nd->path.dentry->d_mounted--;

	old_path->dentry->d_mounted--;

}



void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry,
@@ -174,12 +174,12 @@ void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, 
	dentry->d_mounted++;

}



static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd)

static void attach_mnt(struct vfsmount *mnt, struct path *path)

{

	mnt_set_mountpoint(nd->path.mnt, nd->path.dentry, mnt);

	mnt_set_mountpoint(path->mnt, path->dentry, mnt);

	list_add_tail(&mnt->mnt_hash, mount_hashtable +

			hash(nd->path.mnt, nd->path.dentry));

	list_add_tail(&mnt->mnt_child, &nd->path.mnt->mnt_mounts);

			hash(path->mnt, path->dentry));

	list_add_tail(&mnt->mnt_child, &path->mnt->mnt_mounts);

}



/*
@@ -744,7 +744,7 @@ struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, 
					int flag)

{

	struct vfsmount *res, *p, *q, *r, *s;

	struct nameidata nd;

	struct path path;



	if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt))

		return NULL;
@@ -769,14 +769,14 @@ struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, 
				q = q->mnt_parent;

			}

			p = s;

			nd.path.mnt = q;

			nd.path.dentry = p->mnt_mountpoint;

			path.mnt = q;

			path.dentry = p->mnt_mountpoint;

			q = clone_mnt(p, p->mnt_root, flag);

			if (!q)

				goto Enomem;

			spin_lock(&vfsmount_lock);

			list_add_tail(&q->mnt_list, &res->mnt_list);

			attach_mnt(q, &nd);

			attach_mnt(q, &path);

			spin_unlock(&vfsmount_lock);

		}

	}
@@ -876,11 +876,11 @@ void drop_collected_mounts(struct vfsmount *mnt) 
 * in allocations.

 */

static int attach_recursive_mnt(struct vfsmount *source_mnt,

			struct nameidata *nd, struct nameidata *parent_nd)

			struct path *path, struct path *parent_path)

{

	LIST_HEAD(tree_list);

	struct vfsmount *dest_mnt = nd->path.mnt;

	struct dentry *dest_dentry = nd->path.dentry;

	struct vfsmount *dest_mnt = path->mnt;

	struct dentry *dest_dentry = path->dentry;

	struct vfsmount *child, *p;



	if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list))
@@ -892,9 +892,9 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt, 
	}



	spin_lock(&vfsmount_lock);

	if (parent_nd) {

		detach_mnt(source_mnt, parent_nd);

		attach_mnt(source_mnt, nd);

	if (parent_path) {

		detach_mnt(source_mnt, parent_path);

		attach_mnt(source_mnt, path);

		touch_mnt_namespace(current->nsproxy->mnt_ns);

	} else {

		mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt);
@@ -930,7 +930,7 @@ static int graft_tree(struct vfsmount *mnt, struct nameidata *nd) 


	err = -ENOENT;

	if (IS_ROOT(nd->path.dentry) || !d_unhashed(nd->path.dentry))

		err = attach_recursive_mnt(mnt, nd, NULL);

		err = attach_recursive_mnt(mnt, &nd->path, NULL);

out_unlock:

	mutex_unlock(&nd->path.dentry->d_inode->i_mutex);

	if (!err)
@@ -1059,7 +1059,8 @@ static inline int tree_contains_unbindable(struct vfsmount *mnt) 
 */

static noinline int do_move_mount(struct nameidata *nd, char *old_name)

{

	struct nameidata old_nd, parent_nd;

	struct nameidata old_nd;

	struct path parent_path;

	struct vfsmount *p;

	int err = 0;

	if (!capable(CAP_SYS_ADMIN))
@@ -1114,7 +1115,7 @@ static noinline int do_move_mount(struct nameidata *nd, char *old_name) 
		if (p == old_nd.path.mnt)

			goto out1;



	err = attach_recursive_mnt(old_nd.path.mnt, nd, &parent_nd);

	err = attach_recursive_mnt(old_nd.path.mnt, &nd->path, &parent_path);

	if (err)

		goto out1;
@@ -1128,7 +1129,7 @@ static noinline int do_move_mount(struct nameidata *nd, char *old_name) 
out:

	up_write(&namespace_sem);

	if (!err)

		path_put(&parent_nd.path);

		path_put(&parent_path);

	path_put(&old_nd.path);

	return err;

}
@@ -1683,7 +1684,7 @@ void set_fs_pwd(struct fs_struct *fs, struct path *path) 
		path_put(&old_pwd);

}



static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd)

static void chroot_fs_refs(struct path *old_root, struct path *new_root)

{

	struct task_struct *g, *p;

	struct fs_struct *fs;
@@ -1695,12 +1696,12 @@ static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd) 
		if (fs) {

			atomic_inc(&fs->count);

			task_unlock(p);

			if (fs->root.dentry == old_nd->path.dentry

			    && fs->root.mnt == old_nd->path.mnt)

				set_fs_root(fs, &new_nd->path);

			if (fs->pwd.dentry == old_nd->path.dentry

			    && fs->pwd.mnt == old_nd->path.mnt)

				set_fs_pwd(fs, &new_nd->path);

			if (fs->root.dentry == old_root->dentry

			    && fs->root.mnt == old_root->mnt)

				set_fs_root(fs, new_root);

			if (fs->pwd.dentry == old_root->dentry

			    && fs->pwd.mnt == old_root->mnt)

				set_fs_pwd(fs, new_root);

			put_fs_struct(fs);

		} else

			task_unlock(p);
@@ -1737,7 +1738,8 @@ asmlinkage long sys_pivot_root(const char __user * new_root, 
			       const char __user * put_old)

{

	struct vfsmount *tmp;

	struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd;

	struct nameidata new_nd, old_nd, user_nd;

	struct path parent_path, root_parent;

	int error;



	if (!capable(CAP_SYS_ADMIN))
@@ -1811,19 +1813,19 @@ asmlinkage long sys_pivot_root(const char __user * new_root, 
			goto out3;

	} else if (!is_subdir(old_nd.path.dentry, new_nd.path.dentry))

		goto out3;

	detach_mnt(new_nd.path.mnt, &parent_nd);

	detach_mnt(new_nd.path.mnt, &parent_path);

	detach_mnt(user_nd.path.mnt, &root_parent);

	/* mount old root on put_old */

	attach_mnt(user_nd.path.mnt, &old_nd);

	attach_mnt(user_nd.path.mnt, &old_nd.path);

	/* mount new_root on / */

	attach_mnt(new_nd.path.mnt, &root_parent);

	touch_mnt_namespace(current->nsproxy->mnt_ns);

	spin_unlock(&vfsmount_lock);

	chroot_fs_refs(&user_nd, &new_nd);

	chroot_fs_refs(&user_nd.path, &new_nd.path);

	security_sb_post_pivotroot(&user_nd, &new_nd);

	error = 0;

	path_put(&root_parent.path);

	path_put(&parent_nd.path);

	path_put(&root_parent);

	path_put(&parent_path);

out2:

	mutex_unlock(&old_nd.path.dentry->d_inode->i_mutex);

	up_write(&namespace_sem);