For an unprivileged subvolume iterator, append_to_search_stack() closes
cur_fd. On the first call to btrfs_util_subvolume_iterator_next(),
cur_fd is equal to the fd that was passed to
btrfs_util_create_subvolume_iterator_fd(). We're not supposed to close
that. We didn't notice it because it's more common to use it through
btrfs_util_create_subvolume_iterator(), which opens its own fd that
should be closed, and because the fd number is often reused internally
by the subvolume iterator.
pop_search_stack() already has a check to avoid closing the passed fd;
add the same check to append_to_search_stack(). Also add a regression
test.
Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
e3e10fc8c6