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List:       freebsd-jail
Subject:    Patch for FreeBSD 6.2 fstat(1) to support unionfs (at least a
From:       lists () c0mplx ! org (Kurt Jaeger)
Date:       2007-08-12 12:24:39
Message-ID: 20070812122433.GA68970 () home ! c0mplx ! org
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Hi!

fstat(1) from FreeBSD 6.2 can not display information about files which
reside in a unionfs[1], as can be seen in this example[2]:

USER     CMD          PID   FD MOUNT      INUM MODE         SZ|DV R/W
pi       less       31028 root -         -  ?(unionfs)    -
pi       less       31028   wd -         -  ?(unionfs)    -
pi       less       31028 jail -         -  ?(unionfs)    -
pi       less       31028 text -         -  ?(unionfs)    -
pi       less       31028    0 /vserv/vserv3.nepustil.net/dev    109 crw--w----   \
ttyp5 rw pi       less       31028    1 /vserv/vserv3.nepustil.net/dev    109 \
crw--w----   ttyp5 rw pi       less       31028    2 /vserv/vserv3.nepustil.net/dev   \
109 crw--w----   ttyp5 rw pi       less       31028    3 \
/vserv/vserv3.nepustil.net/dev    109 crw--w----   ttyp5  r pi       less       31028 \
4 -         -  ?(unionfs)    -

This patch[3] fixes it, as can be seen in this other example[4]:

USER     CMD          PID   FD MOUNT      INUM MODE         SZ|DV R/W
pi       less       31028 root /vserv/vserv3.nepustil.net 4804764 drwxrwxr-x     512  \
r  unionupper /usr     pi       less       31028   wd /vserv/vserv3.nepustil.net \
5042109 drwx------    1536  r  unionupper /usr     pi       less       31028 jail \
/vserv/vserv3.nepustil.net 4804764 drwxrwxr-x     512  r  unionupper /usr     pi      \
less       31028 text /vserv/vserv3.nepustil.net 5159119 -r-xr-xr-x  109300  r  \
unionlower /usr     pi       less       31028    0 /vserv/vserv3.nepustil.net/dev    \
109 crw--w----   ttyp5 rw pi       less       31028    1 \
/vserv/vserv3.nepustil.net/dev    109 crw--w----   ttyp5 rw pi       less       31028 \
2 /vserv/vserv3.nepustil.net/dev    109 crw--w----   ttyp5 rw pi       less       \
31028    3 /vserv/vserv3.nepustil.net/dev    109 crw--w----   ttyp5  r pi       less  \
31028    4 /vserv/vserv3.nepustil.net 5042526 -rw-------     702  r  unionupper /usr  \


The filesytems involved:

f6# df [...]
Filesystem                     1K-blocks     Used    Avail Capacity  Mounted on
/dev/ad0s1e                     43938150 20634736 19788362    51%    /usr
[...]
<below>:/vserv/template/stage2  87876300 64572886 19788362    77%    \
/vserv/vserv3.nepustil.net devfs                                  1        1        0 \
100%    /vserv/vserv3.nepustil.net/dev [...]

were mounted with the following command:

/sbin/mount -t unionfs -o noatime,below,copymode=transparent /vserv/template/stage2 \
                /vserv/vserv3.nepustil.net
/sbin/mount_devfs devfs /vserv/vserv3.nepustil.net

How to apply:

cd /tmp/
fetch http://c0mplx.org/src/fstat-unionfs-patch/patch-20070812
cd /usr
patch < /tmp/patch-20070812
cd /usr/src/usr.bin/fstat/
make install

TODO: support other filesystems besides UFS as lower filesystems
  
[1] http://people.freebsd.org/~daichi/unionfs/
[2] http://c0mplx.org/src/fstat-unionfs-patch/before
[3] http://c0mplx.org/src/fstat-unionfs-patch/patch-20070812
[4] http://c0mplx.org/src/fstat-unionfs-patch/after

See also: http://c0mplx.org/src/fstat-unionfs-patch/

-- 
pi@c0mplx.org           +49 171 3101372                        13 years to go !


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