[Unionfs] union of nfs ro and tmpfs rw yielding EROFS

[Brian J. Murrell]

On Fri, 2006-03-03 at 17:34 +0900, hooanon05 at yahoo.co.jp wrote:
> "Brian J. Murrell":
> > I am using unionfs 1.1.3 with 2.6.9 (RHEL4 2.6.9-22.0.2 base) to try to
> > get a writable overlay to a read-only shared NFS root filesystem.  The
> > problem I seem to be having is even though I have a RW branch specifed
> > to the left of the RO branch, I'm still getting EROFS trying to create a
> > file for example.
> 
> It seems the same problem which is posted a few days ago.
> Check out the mail archive by the subject "Is this bug?" and you will
> find a patch.

Hrm.  That patch kinda works.  It allows me to create a file in the root
of the unionfs and the file shows up in the RW branch, but if I try to
create a file in a subdirectory, EROFS still:

# cat /proc/mounts
10.8.0.8:/mnt/boots/boulder/generic-node /sysroot-ro nfs ro,v3,rsize=32768,wsize=32768,hard,udp,nolock,addr=10.8.0.8 0 0
none /sysroot-rw tmpfs rw 0 0
unionfs /sysroot unionfs rw,dirs=/sysroot-rw=rw:/sysroot-ro=ro,debug=0,delete=whiteout,copyup=preserve 0 0

# ls -l /sysroot/foo
ls: /sysroot/foo: No such file or directory
# ls -l /sysroot-rw/foo
ls: /sysroot-rw/foo: No such file or directory
# busybox touch /sysroot/foo
# ls -l /sysroot-rw
-rw-r--r--    1 0        0               0 Mar  3 10:52 foo
# ls -l /sysroot/foo
-rw-r--r--    1 0        0               0 Mar  3 10:52 foo
# busybox touch /sysroot/usr/foo
touch: /sysroot/usr/foo: Read-only file system
# busybox touch /sysroot/lib/foo
touch: /sysroot/lib/foo: Read-only file system

Any more ideas?

b.

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