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Commit 2763d119 authored by Al Viro's avatar Al Viro
Browse files

get rid of detach_mnt() 



Lift getting the original mount (dentry is actually not needed at all)
of the mountpoint into the callers - to do_move_mount() and pivot_root()
level.  That simplifies the cleanup in those and allows to get saner
arguments for attach_mnt_recursive().

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 4edbe133

fs/namespace.c

+28 −34
Original line number Diff line number Diff line
@@ -820,16 +820,6 @@ static struct mountpoint *unhash_mnt(struct mount *mnt) 
	return mp;

}



/*

 * vfsmount lock must be held for write

 */

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

{

	old_path->dentry = dget(mnt->mnt_mountpoint);

	old_path->mnt = &mnt->mnt_parent->mnt;

	put_mountpoint(unhash_mnt(mnt));

}



/*

 * vfsmount lock must be held for write

 */
@@ -2045,7 +2035,7 @@ int count_mounts(struct mnt_namespace *ns, struct mount *mnt) 
static int attach_recursive_mnt(struct mount *source_mnt,

			struct mount *dest_mnt,

			struct mountpoint *dest_mp,

			struct path *parent_path)

			bool moving)

{

	struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns;

	HLIST_HEAD(tree_list);
@@ -2063,7 +2053,7 @@ static int attach_recursive_mnt(struct mount *source_mnt, 
		return PTR_ERR(smp);



	/* Is there space to add these mounts to the mount namespace? */

	if (!parent_path) {

	if (!moving) {

		err = count_mounts(ns, source_mnt);

		if (err)

			goto out;
@@ -2082,8 +2072,8 @@ static int attach_recursive_mnt(struct mount *source_mnt, 
	} else {

		lock_mount_hash();

	}

	if (parent_path) {

		detach_mnt(source_mnt, parent_path);

	if (moving) {

		unhash_mnt(source_mnt);

		attach_mnt(source_mnt, dest_mnt, dest_mp);

		touch_mnt_namespace(source_mnt->mnt_ns);

	} else {
@@ -2181,7 +2171,7 @@ static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp) 
	      d_is_dir(mnt->mnt.mnt_root))

		return -ENOTDIR;



	return attach_recursive_mnt(mnt, p, mp, NULL);

	return attach_recursive_mnt(mnt, p, mp, false);

}



/*
@@ -2574,11 +2564,11 @@ static bool check_for_nsfs_mounts(struct mount *subtree) 


static int do_move_mount(struct path *old_path, struct path *new_path)

{

	struct path parent_path = {.mnt = NULL, .dentry = NULL};

	struct mnt_namespace *ns;

	struct mount *p;

	struct mount *old;

	struct mountpoint *mp;

	struct mount *parent;

	struct mountpoint *mp, *old_mp;

	int err;

	bool attached;
@@ -2588,7 +2578,9 @@ static int do_move_mount(struct path *old_path, struct path *new_path) 


	old = real_mount(old_path->mnt);

	p = real_mount(new_path->mnt);

	parent = old->mnt_parent;

	attached = mnt_has_parent(old);

	old_mp = old->mnt_mp;

	ns = old->mnt_ns;



	err = -EINVAL;
@@ -2616,7 +2608,7 @@ static int do_move_mount(struct path *old_path, struct path *new_path) 
	/*

	 * Don't move a mount residing in a shared parent.

	 */

	if (attached && IS_MNT_SHARED(old->mnt_parent))

	if (attached && IS_MNT_SHARED(parent))

		goto out;

	/*

	 * Don't move a mount tree containing unbindable mounts to a destination
@@ -2632,18 +2624,21 @@ static int do_move_mount(struct path *old_path, struct path *new_path) 
			goto out;



	err = attach_recursive_mnt(old, real_mount(new_path->mnt), mp,

				   attached ? &parent_path : NULL);

				   attached);

	if (err)

		goto out;



	/* if the mount is moved, it should no longer be expire

	 * automatically */

	list_del_init(&old->mnt_expire);

	if (attached)

		put_mountpoint(old_mp);

out:

	unlock_mount(mp);

	if (!err) {

		path_put(&parent_path);

		if (!attached)

		if (attached)

			mntput_no_expire(parent);

		else

			free_mnt_ns(ns);

	}

	return err;
@@ -3586,8 +3581,8 @@ EXPORT_SYMBOL(path_is_under); 
SYSCALL_DEFINE2(pivot_root, const char __user *, new_root,

		const char __user *, put_old)

{

	struct path new, old, parent_path, root_parent, root;

	struct mount *new_mnt, *root_mnt, *old_mnt;

	struct path new, old, root;

	struct mount *new_mnt, *root_mnt, *old_mnt, *root_parent, *ex_parent;

	struct mountpoint *old_mp, *root_mp;

	int error;
@@ -3616,9 +3611,11 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, 
	new_mnt = real_mount(new.mnt);

	root_mnt = real_mount(root.mnt);

	old_mnt = real_mount(old.mnt);

	ex_parent = new_mnt->mnt_parent;

	root_parent = root_mnt->mnt_parent;

	if (IS_MNT_SHARED(old_mnt) ||

		IS_MNT_SHARED(new_mnt->mnt_parent) ||

		IS_MNT_SHARED(root_mnt->mnt_parent))

		IS_MNT_SHARED(ex_parent) ||

		IS_MNT_SHARED(root_parent))

		goto out4;

	if (!check_mnt(root_mnt) || !check_mnt(new_mnt))

		goto out4;
@@ -3635,7 +3632,6 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, 
		goto out4; /* not a mountpoint */

	if (!mnt_has_parent(root_mnt))

		goto out4; /* not attached */

	root_mp = root_mnt->mnt_mp;

	if (new.mnt->mnt_root != new.dentry)

		goto out4; /* not a mountpoint */

	if (!mnt_has_parent(new_mnt))
@@ -3646,10 +3642,9 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, 
	/* make certain new is below the root */

	if (!is_path_reachable(new_mnt, new.dentry, &root))

		goto out4;

	root_mp->m_count++; /* pin it so it won't go away */

	lock_mount_hash();

	detach_mnt(new_mnt, &parent_path);

	detach_mnt(root_mnt, &root_parent);

	umount_mnt(new_mnt);

	root_mp = unhash_mnt(root_mnt);  /* we'll need its mountpoint */

	if (root_mnt->mnt.mnt_flags & MNT_LOCKED) {

		new_mnt->mnt.mnt_flags |= MNT_LOCKED;

		root_mnt->mnt.mnt_flags &= ~MNT_LOCKED;
@@ -3657,7 +3652,8 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, 
	/* mount old root on put_old */

	attach_mnt(root_mnt, old_mnt, old_mp);

	/* mount new_root on / */

	attach_mnt(new_mnt, real_mount(root_parent.mnt), root_mp);

	attach_mnt(new_mnt, root_parent, root_mp);

	mnt_add_count(root_parent, -1);

	touch_mnt_namespace(current->nsproxy->mnt_ns);

	/* A moved mount should not expire automatically */

	list_del_init(&new_mnt->mnt_expire);
@@ -3667,10 +3663,8 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, 
	error = 0;

out4:

	unlock_mount(old_mp);

	if (!error) {

		path_put(&root_parent);

		path_put(&parent_path);

	}

	if (!error)

		mntput_no_expire(ex_parent);

out3:

	path_put(&root);

out2: