nfsd_mutex is used for two quite different things:
1/ it prevents races when start/stoping global resources:
the filecache and the v4 state table
2/ it prevents races for per-netns config, typically
ensure config changes are synchronised w.r.t. server
startup/shutdown.
This patch splits out the first used. A subsequent patch improves the
second.
"nfsd_users" is replaced by a simple bool that records if global
initialisation has completed. If not a new mutex (nfsd_startup_mutex)
is taken, the check is repeated, and if needed the initialisation is
done.
Cleanup is now left to module unload (nfsd_exit()) so there is no
possibility of races with server shutdown.
This replaces NFSD_FILE_CACHE_UP which is effective just a flag which
says nfsd_users is non-zero.
We no longer need to clear the filecache stats because all nfsd-local
memory is effectively cleared on unload.
Signed-off-by: NeilBrown <neil@xxxxxxxxxx>
---
fs/nfsd/export.c | 6 ----
fs/nfsd/filecache.c | 75 ++++++++++-----------------------------------
fs/nfsd/nfsctl.c | 5 +++
fs/nfsd/nfsd.h | 2 ++
fs/nfsd/nfssvc.c | 34 ++++++++++----------
5 files changed, 40 insertions(+), 82 deletions(-)
diff --git a/fs/nfsd/export.c b/fs/nfsd/export.c
index cadfc2bae60e..1ea3d72ef5c9 100644
--- a/fs/nfsd/export.c
+++ b/fs/nfsd/export.c
@@ -243,13 +243,7 @@ static struct cache_head *expkey_alloc(void)
static void expkey_flush(void)
{
- /*
- * Take the nfsd_mutex here to ensure that the file cache is not
- * destroyed while we're in the middle of flushing.
- */
- mutex_lock(&nfsd_mutex);
nfsd_file_cache_purge(current->nsproxy->net_ns);
- mutex_unlock(&nfsd_mutex);
}
static const struct cache_detail svc_expkey_cache_template = {
diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index e108b6c705b4..bd636d0bc05a 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -50,8 +50,6 @@
#define NFSD_LAUNDRETTE_DELAY (2 * HZ)
-#define NFSD_FILE_CACHE_UP (0)
-
/* We only care about NFSD_MAY_READ/WRITE for this cache */
#define NFSD_FILE_MAY_MASK (NFSD_MAY_READ|NFSD_MAY_WRITE|NFSD_MAY_LOCALIO)
@@ -70,7 +68,6 @@ struct nfsd_fcache_disposal {
static struct kmem_cache *nfsd_file_slab;
static struct kmem_cache *nfsd_file_mark_slab;
static struct list_lru nfsd_file_lru;
-static unsigned long nfsd_file_flags;
static struct fsnotify_group *nfsd_file_fsnotify_group;
static struct delayed_work nfsd_filecache_laundrette;
static struct rhltable nfsd_file_rhltable
@@ -112,9 +109,9 @@ static const struct rhashtable_params nfsd_file_rhash_params = {
static void
nfsd_file_schedule_laundrette(void)
{
- if (test_bit(NFSD_FILE_CACHE_UP, &nfsd_file_flags))
- queue_delayed_work(system_unbound_wq, &nfsd_filecache_laundrette,
- NFSD_LAUNDRETTE_DELAY);
+ queue_delayed_work(system_unbound_wq,
+ &nfsd_filecache_laundrette,
+ NFSD_LAUNDRETTE_DELAY);
}
static void
@@ -795,10 +792,6 @@ nfsd_file_cache_init(void)
{
int ret;
- lockdep_assert_held(&nfsd_mutex);
- if (test_and_set_bit(NFSD_FILE_CACHE_UP, &nfsd_file_flags) == 1)
- return 0;
-
ret = rhltable_init(&nfsd_file_rhltable, &nfsd_file_rhash_params);
if (ret)
goto out;
@@ -853,8 +846,6 @@ nfsd_file_cache_init(void)
INIT_DELAYED_WORK(&nfsd_filecache_laundrette, nfsd_file_gc_worker);
out:
- if (ret)
- clear_bit(NFSD_FILE_CACHE_UP, &nfsd_file_flags);
return ret;
out_notifier:
lease_unregister_notifier(&nfsd_file_lease_notifier);
@@ -872,15 +863,15 @@ nfsd_file_cache_init(void)
}
/**
- * __nfsd_file_cache_purge: clean out the cache for shutdown
+ * nfsd_file_cache_purge: clean out the cache for shutdown
* @net: net-namespace to shut down the cache (may be NULL)
*
* Walk the nfsd_file cache and close out any that match @net. If @net is NULL,
* then close out everything. Called when an nfsd instance is being shut down,
* and when the exports table is flushed.
*/
-static void
-__nfsd_file_cache_purge(struct net *net)
+void
+nfsd_file_cache_purge(struct net *net)
{
struct rhashtable_iter iter;
struct nfsd_file *nf;
@@ -950,19 +941,6 @@ nfsd_file_cache_start_net(struct net *net)
return nn->fcache_disposal ? 0 : -ENOMEM;
}
-/**
- * nfsd_file_cache_purge - Remove all cache items associated with @net
- * @net: target net namespace
- *
- */
-void
-nfsd_file_cache_purge(struct net *net)
-{
- lockdep_assert_held(&nfsd_mutex);
- if (test_bit(NFSD_FILE_CACHE_UP, &nfsd_file_flags) == 1)
- __nfsd_file_cache_purge(net);
-}
-
void
nfsd_file_cache_shutdown_net(struct net *net)
{
@@ -973,12 +951,6 @@ nfsd_file_cache_shutdown_net(struct net *net)
void
nfsd_file_cache_shutdown(void)
{
- int i;
-
- lockdep_assert_held(&nfsd_mutex);
- if (test_and_clear_bit(NFSD_FILE_CACHE_UP, &nfsd_file_flags) == 0)
- return;
-
lease_unregister_notifier(&nfsd_file_lease_notifier);
shrinker_free(nfsd_file_shrinker);
/*
@@ -986,7 +958,7 @@ nfsd_file_cache_shutdown(void)
* calling nfsd_file_cache_purge
*/
cancel_delayed_work_sync(&nfsd_filecache_laundrette);
- __nfsd_file_cache_purge(NULL);
+ nfsd_file_cache_purge(NULL);
list_lru_destroy(&nfsd_file_lru);
rcu_barrier();
fsnotify_put_group(nfsd_file_fsnotify_group);
@@ -997,15 +969,6 @@ nfsd_file_cache_shutdown(void)
kmem_cache_destroy(nfsd_file_mark_slab);
nfsd_file_mark_slab = NULL;
rhltable_destroy(&nfsd_file_rhltable);
-
- for_each_possible_cpu(i) {
- per_cpu(nfsd_file_cache_hits, i) = 0;
- per_cpu(nfsd_file_acquisitions, i) = 0;
- per_cpu(nfsd_file_allocations, i) = 0;
- per_cpu(nfsd_file_releases, i) = 0;
- per_cpu(nfsd_file_total_age, i) = 0;
- per_cpu(nfsd_file_evictions, i) = 0;
- }
}
static struct nfsd_file *
@@ -1345,23 +1308,17 @@ int nfsd_file_cache_stats_show(struct seq_file *m, void *v)
unsigned long hits = 0, acquisitions = 0;
unsigned int i, count = 0, buckets = 0;
unsigned long lru = 0, total_age = 0;
+ struct bucket_table *tbl;
+ struct rhashtable *ht;
- /* Serialize with server shutdown */
- mutex_lock(&nfsd_mutex);
- if (test_bit(NFSD_FILE_CACHE_UP, &nfsd_file_flags) == 1) {
- struct bucket_table *tbl;
- struct rhashtable *ht;
-
- lru = list_lru_count(&nfsd_file_lru);
+ lru = list_lru_count(&nfsd_file_lru);
- rcu_read_lock();
- ht = &nfsd_file_rhltable.ht;
- count = atomic_read(&ht->nelems);
- tbl = rht_dereference_rcu(ht->tbl, ht);
- buckets = tbl->size;
- rcu_read_unlock();
- }
- mutex_unlock(&nfsd_mutex);
+ rcu_read_lock();
+ ht = &nfsd_file_rhltable.ht;
+ count = atomic_read(&ht->nelems);
+ tbl = rht_dereference_rcu(ht->tbl, ht);
+ buckets = tbl->size;
+ rcu_read_unlock();
for_each_possible_cpu(i) {
hits += per_cpu(nfsd_file_cache_hits, i);
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index 6b0cad81b5fa..2a1e54af89e5 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c
@@ -2371,6 +2371,11 @@ static int __init init_nfsd(void)
static void __exit exit_nfsd(void)
{
+ if (nfsd_is_started()) {
+ nfs4_state_shutdown();
+ nfsd_file_cache_shutdown();
+ }
+
remove_proc_entry("fs/nfs/exports", NULL);
remove_proc_entry("fs/nfs", NULL);
genl_unregister_family(&nfsd_nl_family);
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 1bfd0b4e9af7..6c432133608f 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -80,6 +80,8 @@ extern const struct svc_version nfsd_version2, nfsd_version3, nfsd_version4;
extern struct mutex nfsd_mutex;
extern atomic_t nfsd_th_cnt; /* number of available threads */
+bool nfsd_is_started(void);
+
extern const struct seq_operations nfs_exports_op;
/*
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 82b0111ac469..0eb144426e95 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -270,40 +270,42 @@ static int nfsd_init_socks(struct net *net, const struct cred *cred)
return 0;
}
-static int nfsd_users = 0;
+static bool nfsd_started;
+static DEFINE_MUTEX(nfsd_startup_mutex);
+
+bool nfsd_is_started(void)
+{
+ return smp_load_acquire(&nfsd_started);
+}
static int nfsd_startup_generic(void)
{
- int ret;
+ int ret = 0;
- if (nfsd_users++)
+ if (nfsd_is_started())
return 0;
+ mutex_lock(&nfsd_startup_mutex);
+ if (nfsd_is_started())
+ goto out_unlock;
ret = nfsd_file_cache_init();
if (ret)
- goto dec_users;
+ goto out_unlock;
ret = nfs4_state_start();
if (ret)
goto out_file_cache;
+ smp_store_release(&nfsd_started, true);
+ mutex_unlock(&nfsd_startup_mutex);
return 0;
out_file_cache:
nfsd_file_cache_shutdown();
-dec_users:
- nfsd_users--;
+out_unlock:
+ mutex_unlock(&nfsd_startup_mutex);
return ret;
}
-static void nfsd_shutdown_generic(void)
-{
- if (--nfsd_users)
- return;
-
- nfs4_state_shutdown();
- nfsd_file_cache_shutdown();
-}
-
static bool nfsd_needs_lockd(struct nfsd_net *nn)
{
return nfsd_vers(nn, 2, NFSD_TEST) || nfsd_vers(nn, 3, NFSD_TEST);
@@ -416,7 +418,6 @@ static int nfsd_startup_net(struct net *net, const struct cred *cred)
nn->lockd_up = false;
}
out_socks:
- nfsd_shutdown_generic();
return ret;
}
@@ -443,7 +444,6 @@ static void nfsd_shutdown_net(struct net *net)
percpu_ref_exit(&nn->nfsd_net_ref);
nn->nfsd_net_up = false;
- nfsd_shutdown_generic();
}
static DEFINE_SPINLOCK(nfsd_notifier_lock);
--
2.49.0
