SUMMARY: LOFS and getwd(3)

From: Mario Nigrovic (
Date: Fri Nov 22 1991 - 20:25:14 CST

Hello again.

I broadcast out this request a few days back:

           I use LOFS mounts to make my server appear to be the same as
        my clients (ie /usr is read-only, etc). But working in LOFS
        directories sometimes confuses getwd(3). This mostly screws up
        find(1), but I have seen shell scripts not function also. Tar
        becomes useless.
           The error message is always the same:
                getwd: read error in ..
           This has forced me to (gasp) use self-referential NFS mounts
        on my server for everything except /usr things which need to be
        mounted before NFS service comes up.
           Are LOFS mounts a bad idea? Is there an easy fix? Is there
        any fix at all?

And received responses from several people:!mdl@uunet (J. Matt Landrum)
        Jay Plett <!jay@uunet>
        Dan Razzell <!razzell@uunet>
        Dan Razzell <!razzell@uunet>!jon@uunet (Jon Stone)!vasey@uunet (Ron Vasey)
        trdlnk!mike@uunet (Michael Sullivan)

But no one else had seen my problem. Some thought that LOFS mounts work just fine
(at least under 4.1.1b which is what I have), others suggested using the

Since several people reported that LOFS works just fine, I dug deeper... I
discovered that I can do a /bin/pwd from /usr (which is mounted -t lo -ro). Then
I tried again from /usr/share, which is mounted -t lo -o rw under /usr, which
is also mounted -t lo -o rw. THAT's where the problem still lies.

This limitation is a far sight better than the old problems under 4.1, but I'm
still going to file a bug report on it. We'll see what happens.

As far as self-referential NFS mounts, I got no negative responses, but nobody
responded with performance differences. It seems to me that they are a good
idea, especially since LOFS mounts seem to be ... iffy? I just wish that /usr
could be self-NFS mounted so we could lose LOFS altogether.


Mario Nigrovic Mario@WDC.SPS.MOT.COM
Motorola Western MCU Design Center (602) 821-4264

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