On 20/7/22 09:54, Al Viro wrote:
On Mon, Jul 11, 2022 at 11:37:46AM +0800, Ian Kent wrote:+static int do_mount_in_use_check(struct mount *mnt, int cnt) +{ + struct mount *topper; + + /* Is there exactly one mount on the child that covers + * it completely? + */ + topper = find_topper(mnt); + if (topper) { + int topper_cnt = topper->mnt_mounts_cnt + 1; + + /* Open file or pwd within singular mount? */ + if (do_refcount_check(topper, topper_cnt)) + return 1;Whatever the hell for? umount(2) will be able to slide the underlying mount from under the topper, whatever the refcount of topper might have been.
My thinking was that a process could have set a working directory (or opened a descriptor) and some later change to an autofs map resulted in it being mounted on. It's irrelevant now with your suggested simpler approach, ;) Ian
