NFS client locks sometimes not removed from server (reproducable)

[Frank van Maarseveen <frankvm@frankvm.com>]

[-- Attachment #1: Type: text/plain, Size: 1084 bytes --]

Client and server are the same. Kernels tried: 2.6.19, 2.6.20 and
2.6.20.1 + http://client.linux-nfs.org/Linux-2.6.x/2.6.20/linux-2.6.20-NFS_ALL.dif

kernel compiled with gcc version 3.4.6 (Debian 3.4.6-4)

/proc/mounts says:

server:/mnt /net/server/mnt nfs rw,nosuid,nodev,vers=3,rsize=32768,wsize=32768,hard,proto=udp,timeo=11,retrans=2,sec=sys,addr=server 0 0


cd /net/server/mnt
mkdir t
cd t
 (save lck.c and locktest attachments here)
gcc -o lck lck.c
./locktest


When the script terminates:
-	ls -li lck-filename
		(remember the inode #)
-	ps wwwuax|grep lck
		(there should not be any running)
-	cat /proc/locks
		(inode appears not locked)
-	ssh server cat /proc/locks
		(inode appears locked!)

Trying the same against a tru64 server shows similar symptoms (the file
can no longer be locked. tru64 has no /proc/locks of course).

A possibly related issue: when the client is shut down it says

	lockd_down: lockd failed to exit, clearing pid

when the client reboots (rpc.statd?) the server seems to remove the
corresponding locks which is a smart thing to do.

-- 
Frank

[-- Attachment #2: lck.c --]
[-- Type: text/plain, Size: 1514 bytes --]

#include <stdio.h>
#include <ctype.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <stdarg.h>
#include <stdlib.h>

void die(const char *fmt, ...) __attribute__((format(printf, 1, 2), noreturn));
void die(const char *fmt, ...)
{
	va_list	ap;

	va_start(ap, fmt);
	fprintf(stderr, "lck: ");
	vfprintf(stderr, fmt, ap);
	va_end(ap);
	exit(1);
}

int main(int argc, char **argv)
{
	struct flock flock = {0};
	int i, d, locktime, cmd;
	const char *name;

	flock.l_type = F_WRLCK;		/* -w */
	flock.l_whence = SEEK_SET;
	cmd = F_SETLKW;			/* no -t */
	name = NULL;
	locktime = 10;
	for (i = 1; i < argc; ++i) {
		if (strcmp(argv[i], "-r") == 0)
			flock.l_type = F_RDLCK;		/* lock for N readers */
		else if (strcmp(argv[i], "-w") == 0)
			flock.l_type = F_WRLCK;		/* lock for 1 writer */
		else if (strcmp(argv[i], "-t") == 0)
			cmd = F_SETLK;			/* test for a lock, don't wait */
		else if (argv[i][0] == '-')
			die("Usage: lck [-r|-w] [-t] [<filename> [<locktime>]]\n");
		else if (name && isdigit(argv[i][0]))
			locktime = atoi(argv[i]);	/* after acquiring lock, wait locktime seconds */
		else
			name = argv[i];
	}
	if (!name)
		name = "lck-filename";
	d = open(name, O_RDWR|O_CREAT, 0666);
	if (d == -1)
		die("open %s: %s\n", name, strerror(errno));
	if (fcntl(d, cmd, &flock) == -1)
		die("fcntl: %s\n", strerror(errno));
	printf("locked...");
	fflush(NULL);
	sleep(locktime);
	if (close(d))
		die("close: %s\n", strerror(errno));
	printf("unlocked.\n");
	return 0;
}

[-- Attachment #3: locktest --]
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#!/bin/sh

trap ' exit ' 1 2 3 15
trap ' fuser -k $lck ; rm -f $lck ' 0

lck=`mktemp -t lckXXXXXX`
cp lck $lck
chmod +x $lck

rm -f lck-filename

function f1()
{
	while :
	do
		$lck lck-filename 1
		sleep 1
	done
}

function f2()
{
	while :
	do
		$lck lck-filename 0
	done
}

function f3()
{
	while :
	do
		$lck -r lck-filename 0
	done
}

function f4()
{
	while :
	do
		$lck -r -t lck-filename 0
	done
}

while :
do
	( f1 & f2 & f3 & f4 ) 9<$lck  &
	sleep 5
	fuser -k $lck
	sleep 2
	echo -n write lock test:
	lck -t lck-filename 0 || exit
done

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