Re: nfsd, rmtab, failover, and stale filehandles

["J. Bruce Fields" <bfields@fieldses.org>]

On Thu, May 06, 2004 at 02:53:11PM -0700, Garrick Staples wrote:
> I'm at a total loss.  Everything I'm reading tells me that all I need to ensure
> is that fs device names are the same on both servers so that the generated
> filehandles are the same, and that I need to move all lines matching
> ":$mountpoint:" in rmtab to the new server.  The former is done since I'm using
> persistant device numbers with lvm.  The latter shouldn't be needed because I'm
> using the "new" proc interface with 2.6.5.
> 
> rmtab definitly doesn't do any noticable difference.  I can add random text
> and blank it out with no noticable difference on the clients.
> 
> Is this a client problem?  The clients are all 2.4.24 and 2.4.26.
> 
> All clients and servers are using vanilla kernels.

I'm assuming /etc/exports is the same, and that the nfsd filesystem is
mounted (probably on /proc/fs/nfs/) and mountd is running without
complaint on the server that you're failing over to?

The kernel uses upcalls to mountd in part to construct the filehandles,
and nfserr_stale could be returned if those upcalls weren't working.
You can see the contents of the caches that hold the result of those
upcalls with something like

for i in `find /proc/net/rpc -name "content"`; do echo -e "\n$i:"; cat $i; done

Maybe the output from that (after a failed failover) would be
enlightening.

Hmm, also, could you try recompiling mountd with the following patch
applied?

--Bruce Fields


mountd needs to make sure that its internal state is synchronized with
etab before responding to kernel upcalls.


 utils/mountd/cache.c |    6 ++++++
 1 files changed, 6 insertions(+)

diff -puN utils/mountd/cache.c~upcall_export_check utils/mountd/cache.c
--- nfs-utils-1.0.6/utils/mountd/cache.c~upcall_export_check	2004-01-26 18:43:51.000000000 -0500
+++ nfs-utils-1.0.6-bfields/utils/mountd/cache.c	2004-01-26 18:43:51.000000000 -0500
@@ -67,6 +67,8 @@ void auth_unix_ip(FILE *f)
 	if (inet_aton(ipaddr, &addr)==0)
 		return;
 
+	auth_reload();
+
 	/* addr is a valid, interesting address, find the domain name... */
 	client = client_compose(addr);
 
@@ -138,6 +140,8 @@ void nfsd_fh(FILE *f)
 		break;
 	}
 
+	auth_reload();
+
 	/* Now determine export point for this fsid/domain */
 	for (i=0 ; i < MCL_MAXTYPES; i++) {
 		for (exp = exportlist[i]; exp; exp = exp->m_next) {
@@ -236,6 +240,8 @@ void nfsd_export(FILE *f)
 	if (qword_get(&cp, path, strlen(lbuf)) <= 0)
 		goto out;
 
+	auth_reload();
+
 	/* now find flags for this export point in this domain */
 	for (i=0 ; i < MCL_MAXTYPES; i++) {
 		for (exp = exportlist[i]; exp; exp = exp->m_next) {

_


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