Al Viro 12487f3067 follow_dotdot{,_rcu}(): massage loops
The logics in both of them is the same:
	while true
		if in process' root	// uncommon
			break
		if *not* in mount root	// normal case
			find the parent
			return
		if at absolute root	// very uncommon
			break
		move to underlying mountpoint
	report that we are in root

Pull the common path out of the loop:
	if in process' root		// uncommon
		goto in_root
	if unlikely(in mount root)
		while true
			if at absolute root
				goto in_root
			move to underlying mountpoint
			if in process' root
				goto in_root
			if in mount root
				break;
	find the parent	// we are not in mount root
	return
in_root:
	report that we are in root

The reason for that transformation is that we get to keep the
common path straight *and* get a separate block for "move
through underlying mountpoints", which will allow to sanitize
NO_XDEV handling there.  What's more, the pared-down loops
will be easier to deal with - in particular, non-RCU case
has no need to grab mount_lock and rewriting it to the
form that wouldn't do that is a non-trivial change.  Better
do that with less stuff getting in the way...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2020-04-02 01:09:19 -04:00
..
2019-09-27 15:10:34 -07:00
2020-02-03 17:03:42 +00:00
2019-09-19 09:42:37 -07:00
2019-11-11 09:21:59 -05:00
2019-09-19 09:42:37 -07:00
2020-02-05 05:28:20 +00:00
2020-02-07 17:50:21 -08:00
\n
2020-01-30 15:37:41 -08:00
2019-09-19 09:42:37 -07:00
2020-01-14 13:28:28 -08:00
2020-02-07 14:39:38 +09:00
2019-11-30 10:44:49 -08:00
2019-08-07 21:51:47 -04:00
2020-01-29 19:38:34 -08:00
2020-02-07 14:48:35 -05:00
2020-02-07 14:48:35 -05:00
2020-02-06 06:33:17 +00:00
2020-02-08 13:44:41 -08:00
2020-02-09 15:51:46 -08:00
2020-02-09 15:51:46 -08:00
2020-04-02 01:09:19 -04:00
2020-02-04 11:45:21 +00:00
2019-12-08 14:37:36 +01:00