Weird behaviour of mount_unionfs with executables

[Dario Freni]

Hi everybody, I'm working on rewriting FreeSBIE toolkit for my Summer
of Code project. Before that, I'm trying to adapt actual scripts with
latest -current (expecially ppc). I noticed a weird behaviour of
unionfs either in i386 and ppc. Under FreeSBIE, we use to mount memory
file systems over compressed ones via unionfs. Under -current,
whenever I recall an rwx file, it is correctly executed the first
time, then it is copied to the upper layer (why? I haven't modified it
yet) with wrong permission, so it is unexecutable.

sberta:/home/satu/tmp# kldload geom_uzip
sberta:/home/satu/tmp# mdconfig -a -t vnode -f usr.uzip
md0
sberta:/home/satu/tmp# ll /dev/md0*
crw-r-----  1 root  operator   11,  98 Jul  1 12:48 /dev/md0
crw-r-----  1 root  operator   11,  99 Jul  1 12:48 /dev/md0.uzip
sberta:/home/satu/tmp# mount -r /dev/md0.uzip compressedusr/

sberta:/home/satu/tmp# mdmfs -S -s 32m -M md mdmfs/
sberta:/home/satu/tmp# mtree -PUdr -p mdmfs/ < FreeSBIE.usr.dirs 
[..snip, reconstructing the directory tree with right permissions..]

sberta:/home/satu/tmp# mount_unionfs mdmfs/ compressedusr/

sberta:/home/satu/tmp# cd compressedusr/bin/
sberta:/home/satu/tmp/compressedusr/bin# ll w
-r-xr-xr-x  2 root  wheel  11416 Jun 22 23:35 w
sberta:/home/satu/tmp/compressedusr/bin# ./w
 2:26PM  up 1 day,  1:38, 9 users, load averages: 3.49, 3.12, 2.26
USER             TTY      FROM              LOGIN@  IDLE WHAT
[...]
sberta:/home/satu/tmp/compressedusr/bin# ll w
-rw-r--r--  1 root  wheel  11416 Jul  2 14:26 w
sberta:/home/satu/tmp/compressedusr/bin# ./w
./w: Permission denied.

I'm also afraid that copying files to the upper layer also when
they're not modified could fill up our mfs entirely. I'm almost sure
there's a totally different behaviour under RELENG_5, as we haven't
encountered such problems.


-- 
Dario Freni (saturnero at freesbie.org)
FreeSBIE developer (http://www.freesbie.org)
GPG Public key at http://www.saturnero.net/saturnero.asc
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