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nfsd: separate nfsd_last_thread() from nfsd_put()

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[ Upstream commit 9f28a971ee9fdf1bf8ce8c88b103f483be610277 ]

Now that the last nfsd thread is stopped by an explicit act of calling
svc_set_num_threads() with a count of zero, we only have a limited
number of places that can happen, and don't need to call
nfsd_last_thread() in nfsd_put()

So separate that out and call it at the two places where the number of
threads is set to zero.

Move the clearing of ->nfsd_serv and the call to svc_xprt_destroy_all()
into nfsd_last_thread(), as they are really part of the same action.

nfsd_put() is now a thin wrapper around svc_put(), so make it a static
inline.

nfsd_put() cannot be called after nfsd_last_thread(), so in a couple of
places we have to use svc_put() instead.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
NeilBrown 2023-07-31 16:48:32 +10:00 • committed by Ksawlii
parent 1ae4b794eb
commit b0701f7372
2 changed files with 25 additions and 34 deletions
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7
fs/nfsd/nfsd.h
View file

@ -96,7 +96,12 @@ int nfsd_pool_stats_open(struct inode *, struct file *);
int nfsd_pool_stats_release(struct inode *, struct file *);
void nfsd_shutdown_threads(struct net *net);
void nfsd_put(struct net *net);
static inline void nfsd_put(struct net *net)
{
struct nfsd_net *nn = net_generic(net, nfsd_net_id);
svc_put(nn->nfsd_serv);
}
bool i_am_nfsd(void);

52
fs/nfsd/nfssvc.c
View file

@ -529,9 +529,14 @@ static struct notifier_block nfsd_inet6addr_notifier = {
/* Only used under nfsd_mutex, so this atomic may be overkill: */
static atomic_t nfsd_notifier_refcount = ATOMIC_INIT(0);
static void nfsd_last_thread(struct svc_serv *serv, struct net *net)
static void nfsd_last_thread(struct net *net)
{
struct nfsd_net *nn = net_generic(net, nfsd_net_id);
struct svc_serv *serv = nn->nfsd_serv;
spin_lock(&nfsd_notifier_lock);
nn->nfsd_serv = NULL;
spin_unlock(&nfsd_notifier_lock);
/* check if the notifier still has clients */
if (atomic_dec_return(&nfsd_notifier_refcount) == 0) {
@ -541,6 +546,8 @@ static void nfsd_last_thread(struct svc_serv *serv, struct net *net)
#endif
}
svc_xprt_destroy_all(serv, net);
/*
* write_ports can create the server without actually starting
* any threads--if we get shut down before any threads are
@ -631,7 +638,8 @@ void nfsd_shutdown_threads(struct net *net)
svc_get(serv);
/* Kill outstanding nfsd threads */
svc_set_num_threads(serv, NULL, 0);
nfsd_put(net);
nfsd_last_thread(net);
svc_put(serv);
mutex_unlock(&nfsd_mutex);
}
@ -661,9 +669,6 @@ int nfsd_create_serv(struct net *net)
serv->sv_maxconn = nn->max_connections;
error = svc_bind(serv, net);
if (error < 0) {
/* NOT nfsd_put() as notifiers (see below) haven't
* been set up yet.
*/
svc_put(serv);
return error;
}
@ -706,29 +711,6 @@ int nfsd_get_nrthreads(int n, int *nthreads, struct net *net)
return 0;
}
/* This is the callback for kref_put() below.
* There is no code here as the first thing to be done is
* call svc_shutdown_net(), but we cannot get the 'net' from
* the kref. So do all the work when kref_put returns true.
*/
static void nfsd_noop(struct kref *ref)
{
}
void nfsd_put(struct net *net)
{
struct nfsd_net *nn = net_generic(net, nfsd_net_id);
if (kref_put(&nn->nfsd_serv->sv_refcnt, nfsd_noop)) {
svc_xprt_destroy_all(nn->nfsd_serv, net);
nfsd_last_thread(nn->nfsd_serv, net);
svc_destroy(&nn->nfsd_serv->sv_refcnt);
spin_lock(&nfsd_notifier_lock);
nn->nfsd_serv = NULL;
spin_unlock(&nfsd_notifier_lock);
}
}
int nfsd_set_nrthreads(int n, int *nthreads, struct net *net)
{
int i = 0;
@ -779,7 +761,7 @@ int nfsd_set_nrthreads(int n, int *nthreads, struct net *net)
if (err)
break;
}
nfsd_put(net);
svc_put(nn->nfsd_serv);
return err;
}
@ -794,6 +776,7 @@ nfsd_svc(int nrservs, struct net *net, const struct cred *cred)
int error;
bool nfsd_up_before;
struct nfsd_net *nn = net_generic(net, nfsd_net_id);
struct svc_serv *serv;
mutex_lock(&nfsd_mutex);
dprintk("nfsd: creating service\n");
@ -813,22 +796,25 @@ nfsd_svc(int nrservs, struct net *net, const struct cred *cred)
goto out;
nfsd_up_before = nn->nfsd_net_up;
serv = nn->nfsd_serv;
error = nfsd_startup_net(net, cred);
if (error)
goto out_put;
error = svc_set_num_threads(nn->nfsd_serv, NULL, nrservs);
error = svc_set_num_threads(serv, NULL, nrservs);
if (error)
goto out_shutdown;
error = nn->nfsd_serv->sv_nrthreads;
error = serv->sv_nrthreads;
if (error == 0)
nfsd_last_thread(net);
out_shutdown:
if (error < 0 && !nfsd_up_before)
nfsd_shutdown_net(net);
out_put:
/* Threads now hold service active */
if (xchg(&nn->keep_active, 0))
nfsd_put(net);
nfsd_put(net);
svc_put(serv);
svc_put(serv);
out:
mutex_unlock(&nfsd_mutex);
return error;