[unionfs][patch] improvements of the unionfs - Problem Report, kern/91010

[Danny Braniss]

> Masanori OZAWA wrote:
> [...]
> 
> Nice work! This is just a "works for me". In only find some issues with
> permissions that were already present in the previous implementation of
> unionfs. Some of them are partially corrected in the "useful" copymode.
> I mailed the details to the author.

the following will hang the kernel:
	root is mounted nfs,
	/etc is unionfs'ed so:
	from /etc/rc.initdiskless:
		...
		# Create a generic memory disk
		#
		mount_md() {
		    /sbin/mdmfs -i 4096 -s $1 -M md $2
		}
		kldload unionfs
		mount_md 4096 /.etc
		mount_unionfs /.etc /etc
		...
	and now:
		cd /etc
		mv some-file somefile
and now the system is stuck.
this behaviour is also present in the unpatched unionfs, but would be nice
if it can be fixed.

	danny
ps: see http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/84107