Commit e257039f authored by Al Viro's avatar Al Viro
Browse files

mount_setattr(): clean the control flow and calling conventions 



separate the "cleanup" and "apply" codepaths (they have almost no overlap),
fold the "cleanup" into "prepare" (which eliminates the need of ->revert)
and make loops more idiomatic.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 87bb5b60

fs/namespace.c

+40 −42
Original line number Diff line number Diff line
@@ -82,7 +82,6 @@ struct mount_kattr { 
	unsigned int lookup_flags;

	bool recurse;

	struct user_namespace *mnt_userns;

	struct mount *revert;

};



/* /sys/fs */
@@ -4014,34 +4013,41 @@ static inline bool mnt_allow_writers(const struct mount_kattr *kattr, 


static int mount_setattr_prepare(struct mount_kattr *kattr, struct mount *mnt)

{

	struct mount *m = mnt;



	do {

		int err = -EPERM;

		unsigned int flags;



		kattr->revert = m;

	struct mount *m;

	int err;



		flags = recalc_flags(kattr, m);

		if (!can_change_locked_flags(m, flags))

			return err;

	for (m = mnt; m; m = next_mnt(m, mnt)) {

		if (!can_change_locked_flags(m, recalc_flags(kattr, m))) {

			err = -EPERM;

			break;

		}



		err = can_idmap_mount(kattr, m);

		if (err)

			return err;



		if (mnt_allow_writers(kattr, m))

			continue;

			break;



		if (!mnt_allow_writers(kattr, m)) {

			err = mnt_hold_writers(m);

			if (err)

			return err;

	} while (kattr->recurse && (m = next_mnt(m, mnt)));

				break;

		}



	kattr->revert = NULL;

		if (!kattr->recurse)

			return 0;

	}



	if (err) {

		struct mount *p;



		for (p = mnt; p != m; p = next_mnt(p, mnt)) {

			/* If we had to hold writers unblock them. */

			if (p->mnt.mnt_flags & MNT_WRITE_HOLD)

				mnt_unhold_writers(p);

		}

	}

	return err;

}



static void do_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt)

{

	struct user_namespace *mnt_userns, *old_mnt_userns;
@@ -4067,35 +4073,26 @@ static void do_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt) 
		put_user_ns(old_mnt_userns);

}



static void mount_setattr_finish(struct mount_kattr *kattr, struct mount *mnt)

static void mount_setattr_commit(struct mount_kattr *kattr, struct mount *mnt)

{

	struct mount *m = mnt;

	struct mount *m;



	do {

		if (!kattr->revert) {

	for (m = mnt; m; m = next_mnt(m, mnt)) {

		unsigned int flags;



		do_idmap_mount(kattr, m);

		flags = recalc_flags(kattr, m);

		WRITE_ONCE(m->mnt.mnt_flags, flags);

		}



		/* If we had to hold writers unblock them. */

		if (m->mnt.mnt_flags & MNT_WRITE_HOLD)

			mnt_unhold_writers(m);



		if (!kattr->revert && kattr->propagation)

		if (kattr->propagation)

			change_mnt_propagation(m, kattr->propagation);



		/*

		 * On failure, only cleanup until we found the first mount

		 * we failed to handle.

		 */

		if (kattr->revert == m)

			return;

	} while (kattr->recurse && (m = next_mnt(m, mnt)));



	if (!kattr->revert)

		if (!kattr->recurse)

			break;

	}

	touch_mnt_namespace(mnt->mnt_ns);

}
@@ -4144,7 +4141,8 @@ static int do_mount_setattr(struct path *path, struct mount_kattr *kattr) 
	 * changes and if we failed we clean up.

	 */

	err = mount_setattr_prepare(kattr, mnt);

	mount_setattr_finish(kattr, mnt);

	if (!err)

		mount_setattr_commit(kattr, mnt);



out:

	unlock_mount_hash();