[Please note that the email address given is not valid due to security reasons. Just reply to the gnats entry, and I'll follow it via the web interface.] Machine A is serving via NFS. When unmounting (probably also mounting) an unrelated file system on A, B will get a EPERM error if it is simultaneously accessing files on A via NFS. I have seen this behavior at least since 5.x, probably before. Fix: Unknown. How-To-Repeat: Do heavy NFS i/o from machine B to machine A, then unmount (mount) a file system on A. B will get an error.
Responsible Changed From-To: freebsd-bugs->freebsd-fs Over to maintainer(s).
This is a friendly reminder that some kind soul with knowledge of the relevant kernel parts look into this... the error can easily be reproduced. I just had it on a 7.4 system which did heavy reading from an 8.2 server. When I mounted something on the server, the client got a "Permission denied" reply. So, to recap the scenario: 7.4 NFS client 8.2 NFS server client mounts a fs from the server (via IPv4, might be interesting to look at http://www.freebsd.org/cgi/query-pr.cgi?pr=kern/151681, too, but that is unrelated) client does heavy i/o on the mounted fs server does a mount (on its side, in this case it was from an md device) --> error: client gets back some NFS error (in this case "permission denied")
This is fixed in more recent versions of FreeBSD by using the "-S" option on mountd. I am afraid FreeBSD7 will never be fixed. I am closing this, since it is a duplicate of 9619 and the fix is in more recent FreeBSD systems. *** This bug has been marked as a duplicate of bug 9619 ***
A commit references this bug: Author: rmacklem Date: Sun May 8 20:10:23 UTC 2016 New revision: 299242 URL: https://svnweb.freebsd.org/changeset/base/299242 Log: Make "-S" a default option for mountd. After a discussion on freebsd-fs@ there seemed to be a consensus that the "-S" option for mountd should become the default. Since the only known issue w.r.t. using "-S" was fixed by r299201, this commit adds "-S" to the default mountd_flags. Discussed on: freebsd-fs PR: 9619, 131342, 206855 MFC after: 2 weeks Relnotes: yes Changes: head/etc/defaults/rc.conf