[NFS] Problems with crossmnt since 1.2.1

[NFS] Problems with crossmnt since 1.2.1

[Iustin Pop]

Hi,

Since nfs-utils 1.2.1, there are some problems with crossmnt usage. See
Debian bug http://bugs.debian.org/567546, but in short the problem seems
to be that sub-mounts (/a/b) take the top-level mount (/a) options
instead of their own, due to a bug in how mountd generates the crossmnt
subexports.

I checked that reverting the write_secinfo changes in commit
bc0a6ab03089fc1ea4fea26ed9635c2cc918b01b fix the issue, but that might
only be a side effect, not the actual cause.

A short test:
- have /a and /a/b exported, with different flags (e.g. ro on /a, rw on
  /a/b)
- restart the mountd, clear exports, etc.
- try a mount on the client of /a/b, it gets readonly
- umount & remount, it's now r/w
- however, clearing the kernel export table (exportfs -f), makes the
  next mount again get read-only 

Disabling crossmnt fixes the issue completely, so I would venture to
guess that the subexports creation code has some issue, but I don't know
enough of this to be able to debug it.

thanks,
iustin

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