linux/fs/nfs/callback.c
Jeff Layton 06e02d66fa NFS: don't let nfs_callback_svc exit on unexpected svc_recv errors (try #2)
When svc_recv returns an unexpected error, nfs_callback_svc will print a
warning and exit. This problematic for several reasons. In particular,
it will cause the reference counts for the thread to be wrong, and no
new thread will be started until all nfs4 mounts are unmounted.

Rather than exiting on error from svc_recv, have the thread do a 1s
sleep and then retry the loop. This is unlikely to cause any harm, and
if the error turns out to be something temporary then it may be able to
recover.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>
2008-04-23 16:13:42 -04:00

222 lines
5.2 KiB
C

/*
* linux/fs/nfs/callback.c
*
* Copyright (C) 2004 Trond Myklebust
*
* NFSv4 callback handling
*/
#include <linux/completion.h>
#include <linux/ip.h>
#include <linux/module.h>
#include <linux/smp_lock.h>
#include <linux/sunrpc/svc.h>
#include <linux/sunrpc/svcsock.h>
#include <linux/nfs_fs.h>
#include <linux/mutex.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <net/inet_sock.h>
#include "nfs4_fs.h"
#include "callback.h"
#include "internal.h"
#define NFSDBG_FACILITY NFSDBG_CALLBACK
struct nfs_callback_data {
unsigned int users;
struct svc_serv *serv;
struct task_struct *task;
};
static struct nfs_callback_data nfs_callback_info;
static DEFINE_MUTEX(nfs_callback_mutex);
static struct svc_program nfs4_callback_program;
unsigned int nfs_callback_set_tcpport;
unsigned short nfs_callback_tcpport;
static const int nfs_set_port_min = 0;
static const int nfs_set_port_max = 65535;
static int param_set_port(const char *val, struct kernel_param *kp)
{
char *endp;
int num = simple_strtol(val, &endp, 0);
if (endp == val || *endp || num < nfs_set_port_min || num > nfs_set_port_max)
return -EINVAL;
*((int *)kp->arg) = num;
return 0;
}
module_param_call(callback_tcpport, param_set_port, param_get_int,
&nfs_callback_set_tcpport, 0644);
/*
* This is the callback kernel thread.
*/
static int
nfs_callback_svc(void *vrqstp)
{
int err, preverr = 0;
struct svc_rqst *rqstp = vrqstp;
set_freezable();
/*
* FIXME: do we really need to run this under the BKL? If so, please
* add a comment about what it's intended to protect.
*/
lock_kernel();
while (!kthread_should_stop()) {
/*
* Listen for a request on the socket
*/
err = svc_recv(rqstp, MAX_SCHEDULE_TIMEOUT);
if (err == -EAGAIN || err == -EINTR) {
preverr = err;
continue;
}
if (err < 0) {
if (err != preverr) {
printk(KERN_WARNING "%s: unexpected error "
"from svc_recv (%d)\n", __func__, err);
preverr = err;
}
schedule_timeout_uninterruptible(HZ);
continue;
}
preverr = err;
svc_process(rqstp);
}
unlock_kernel();
nfs_callback_info.task = NULL;
svc_exit_thread(rqstp);
return 0;
}
/*
* Bring up the server process if it is not already up.
*/
int nfs_callback_up(void)
{
struct svc_serv *serv = NULL;
struct svc_rqst *rqstp;
int ret = 0;
lock_kernel();
mutex_lock(&nfs_callback_mutex);
if (nfs_callback_info.users++ || nfs_callback_info.task != NULL)
goto out;
serv = svc_create(&nfs4_callback_program, NFS4_CALLBACK_BUFSIZE, NULL);
ret = -ENOMEM;
if (!serv)
goto out_err;
ret = svc_create_xprt(serv, "tcp", nfs_callback_set_tcpport,
SVC_SOCK_ANONYMOUS);
if (ret <= 0)
goto out_err;
nfs_callback_tcpport = ret;
dprintk("Callback port = 0x%x\n", nfs_callback_tcpport);
rqstp = svc_prepare_thread(serv, &serv->sv_pools[0]);
if (IS_ERR(rqstp)) {
ret = PTR_ERR(rqstp);
goto out_err;
}
svc_sock_update_bufs(serv);
nfs_callback_info.serv = serv;
nfs_callback_info.task = kthread_run(nfs_callback_svc, rqstp,
"nfsv4-svc");
if (IS_ERR(nfs_callback_info.task)) {
ret = PTR_ERR(nfs_callback_info.task);
nfs_callback_info.serv = NULL;
nfs_callback_info.task = NULL;
svc_exit_thread(rqstp);
goto out_err;
}
out:
/*
* svc_create creates the svc_serv with sv_nrthreads == 1, and then
* svc_prepare_thread increments that. So we need to call svc_destroy
* on both success and failure so that the refcount is 1 when the
* thread exits.
*/
if (serv)
svc_destroy(serv);
mutex_unlock(&nfs_callback_mutex);
unlock_kernel();
return ret;
out_err:
dprintk("Couldn't create callback socket or server thread; err = %d\n",
ret);
nfs_callback_info.users--;
goto out;
}
/*
* Kill the server process if it is not already down.
*/
void nfs_callback_down(void)
{
lock_kernel();
mutex_lock(&nfs_callback_mutex);
nfs_callback_info.users--;
if (nfs_callback_info.users == 0 && nfs_callback_info.task != NULL)
kthread_stop(nfs_callback_info.task);
mutex_unlock(&nfs_callback_mutex);
unlock_kernel();
}
static int nfs_callback_authenticate(struct svc_rqst *rqstp)
{
struct nfs_client *clp;
RPC_IFDEBUG(char buf[RPC_MAX_ADDRBUFLEN]);
/* Don't talk to strangers */
clp = nfs_find_client(svc_addr(rqstp), 4);
if (clp == NULL)
return SVC_DROP;
dprintk("%s: %s NFSv4 callback!\n", __FUNCTION__,
svc_print_addr(rqstp, buf, sizeof(buf)));
nfs_put_client(clp);
switch (rqstp->rq_authop->flavour) {
case RPC_AUTH_NULL:
if (rqstp->rq_proc != CB_NULL)
return SVC_DENIED;
break;
case RPC_AUTH_UNIX:
break;
case RPC_AUTH_GSS:
/* FIXME: RPCSEC_GSS handling? */
default:
return SVC_DENIED;
}
return SVC_OK;
}
/*
* Define NFS4 callback program
*/
static struct svc_version *nfs4_callback_version[] = {
[1] = &nfs4_callback_version1,
};
static struct svc_stat nfs4_callback_stats;
static struct svc_program nfs4_callback_program = {
.pg_prog = NFS4_CALLBACK, /* RPC service number */
.pg_nvers = ARRAY_SIZE(nfs4_callback_version), /* Number of entries */
.pg_vers = nfs4_callback_version, /* version table */
.pg_name = "NFSv4 callback", /* service name */
.pg_class = "nfs", /* authentication class */
.pg_stats = &nfs4_callback_stats,
.pg_authenticate = nfs_callback_authenticate,
};