Commit da025cdb authored by Al Viro's avatar Al Viro
Browse files

propagate_umount(): only surviving overmounts should be reparented 



... as the comments in reparent() clearly say.  As it is, we reparent
*all* overmounts of the mounts being taken out, including those that
are taken out themselves.  It's not only a potentially massive slowdown
(on a pathological setup we might end up with O(N^2) time for N mounts
being kicked out), it can end up with incorrect ->overmount in the
surviving mounts.

Fixes: f0d0ba19 "Rewrite of propagate_umount()"
Reviewed-by: default avatarChristian Brauner <brauner@kernel.org>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 0ddfb62f

fs/pnode.c

+4 −3
Original line number Diff line number Diff line
@@ -637,10 +637,11 @@ void propagate_umount(struct list_head *set) 
	}



	// now to_umount consists of all acceptable candidates

	// deal with reparenting of remaining overmounts on those

	// deal with reparenting of surviving overmounts on those

	list_for_each_entry(m, &to_umount, mnt_list) {

		if (m->overmount)

			reparent(m->overmount);

		struct mount *over = m->overmount;

		if (over && !will_be_unmounted(over))

			reparent(over);

	}



	// and fold them into the set