Red Hat Bugzilla – Bug 867649
nfsd readdir cookies problematic for some 32-bit clients (Solaris, AIX)
Last modified: 2013-08-21 20:52:41 EDT
After upgrading a few of our Fedora hosts to Fedora 16, some of our older NFS clients have been having problems reading directories on mounted NFS exports. The common factor seems to be the 32-bitness of the client (user mode) software. E.g. a 32-bit build of a client program would have a problem but a 64-bit build of the same program on the same client would be ok. One client is Solaris 10 and the other is AIX 5.3.
The exports in question are ext3 filesystems with dir_index enabled (possibly relevant?). The NFS server is an x86_64 F16 system.
The symptom of the problem is a client program getting EOVERFLOW errors from readdir. I believe the cause of this is NFSv3 READDIR(PLUS) returning directory entry cookies that require all 64-bits instead of ones that fit into 32-bits. To test the theory, I built an nfsd.ko with this change:
diff -u -r vanilla-3.4/fs/nfsd/vfs.c linux-3.4.x86_64/fs/nfsd/vfs.c
--- vanilla-3.4/fs/nfsd/vfs.c 2012-05-20 15:29:13.000000000 -0700
+++ linux-3.4.x86_64/fs/nfsd/vfs.c 2012-10-15 13:05:42.000000000 -0700
@@ -799,9 +799,11 @@
host_err = ima_file_check(*filp, may_flags);
+#if 0 /* DANCY */
if (may_flags & NFSD_MAY_64BIT_COOKIE)
(*filp)->f_mode |= FMODE_64BITHASH;
(*filp)->f_mode |= FMODE_32BITHASH;
After that the older NFS clients were happy again.
You may find that this smells similar to the old problems between IRIX and the workaround of using the -32bitclients export option. It seems like Linux NFS server needs such an option now.
I would really like to see a fix for this before F16 support runs out. There have to be a lot of us out there that have these old AIX and Solaris machines. Thanks.
This is basically the same as the rhel bug 857525.
My own preference would be for an ext4 mount option, as that would also be useful for a couple userland applications (gluster and samba) running into similar trouble.
And, yes, for now you can turn off dir_index as a workaround.
(In reply to comment #2)
> This is basically the same as the rhel bug 857525.
Hmm. Indeed it is! You can't imagine mow much googling I did w/o finding matching complaints!
> My own preference would be for an ext4 mount option, as that would also be
> useful for a couple userland applications (gluster and samba) running into
> similar trouble.
For the record, we're suffering this problem against ext3 as well.
So how do we make the mount option happen? Who do we nag?
> And, yes, for now you can turn off dir_index as a workaround.
Nod. In which case I'll just stick w/ my module hack.
(In reply to comment #3)
> For the record, we're suffering this problem against ext3 as well.
> So how do we make the mount option happen? Who do we nag?
Probably the nfs and ext4 mailing lists: email@example.com and firstname.lastname@example.org. Probably you'd want to just present your problem and let people argue about the possible solution.
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I know this was closed out, but am trying to determine if there ever was a resolution. I have older Solaris 10 clients experiencing similar symptoms and have discovered that by creating file systems for NFS export on my RHEL6 machines with dir_index disabled that things work as expected.
Does this still need followed-up on? I'll throw something out on the linux-nfs list most likely as well and possibly open a support call with RH.