nfsd: protect concurrent access to nfsd stats counters
nfsd stats counters can be updated by concurrent nfsd threads without any
protection.
Convert some nfsd_stats and nfsd_net struct members to use percpu counters.
The longest_chain* members of struct nfsd_net remain unprotected.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c
index 80c90fc..96cdf77 100644
--- a/fs/nfsd/nfscache.c
+++ b/fs/nfsd/nfscache.c
@@ -121,14 +121,14 @@ nfsd_reply_cache_free_locked(struct nfsd_drc_bucket *b, struct svc_cacherep *rp,
struct nfsd_net *nn)
{
if (rp->c_type == RC_REPLBUFF && rp->c_replvec.iov_base) {
- nn->drc_mem_usage -= rp->c_replvec.iov_len;
+ nfsd_stats_drc_mem_usage_sub(nn, rp->c_replvec.iov_len);
kfree(rp->c_replvec.iov_base);
}
if (rp->c_state != RC_UNUSED) {
rb_erase(&rp->c_node, &b->rb_head);
list_del(&rp->c_lru);
atomic_dec(&nn->num_drc_entries);
- nn->drc_mem_usage -= sizeof(*rp);
+ nfsd_stats_drc_mem_usage_sub(nn, sizeof(*rp));
}
kmem_cache_free(drc_slab, rp);
}
@@ -154,6 +154,16 @@ void nfsd_drc_slab_free(void)
kmem_cache_destroy(drc_slab);
}
+static int nfsd_reply_cache_stats_init(struct nfsd_net *nn)
+{
+ return nfsd_percpu_counters_init(nn->counter, NFSD_NET_COUNTERS_NUM);
+}
+
+static void nfsd_reply_cache_stats_destroy(struct nfsd_net *nn)
+{
+ nfsd_percpu_counters_destroy(nn->counter, NFSD_NET_COUNTERS_NUM);
+}
+
int nfsd_reply_cache_init(struct nfsd_net *nn)
{
unsigned int hashsize;
@@ -165,12 +175,16 @@ int nfsd_reply_cache_init(struct nfsd_net *nn)
hashsize = nfsd_hashsize(nn->max_drc_entries);
nn->maskbits = ilog2(hashsize);
+ status = nfsd_reply_cache_stats_init(nn);
+ if (status)
+ goto out_nomem;
+
nn->nfsd_reply_cache_shrinker.scan_objects = nfsd_reply_cache_scan;
nn->nfsd_reply_cache_shrinker.count_objects = nfsd_reply_cache_count;
nn->nfsd_reply_cache_shrinker.seeks = 1;
status = register_shrinker(&nn->nfsd_reply_cache_shrinker);
if (status)
- goto out_nomem;
+ goto out_stats_destroy;
nn->drc_hashtbl = kvzalloc(array_size(hashsize,
sizeof(*nn->drc_hashtbl)), GFP_KERNEL);
@@ -186,6 +200,8 @@ int nfsd_reply_cache_init(struct nfsd_net *nn)
return 0;
out_shrinker:
unregister_shrinker(&nn->nfsd_reply_cache_shrinker);
+out_stats_destroy:
+ nfsd_reply_cache_stats_destroy(nn);
out_nomem:
printk(KERN_ERR "nfsd: failed to allocate reply cache\n");
return -ENOMEM;
@@ -196,6 +212,7 @@ void nfsd_reply_cache_shutdown(struct nfsd_net *nn)
struct svc_cacherep *rp;
unsigned int i;
+ nfsd_reply_cache_stats_destroy(nn);
unregister_shrinker(&nn->nfsd_reply_cache_shrinker);
for (i = 0; i < nn->drc_hashsize; i++) {
@@ -324,7 +341,7 @@ nfsd_cache_key_cmp(const struct svc_cacherep *key,
{
if (key->c_key.k_xid == rp->c_key.k_xid &&
key->c_key.k_csum != rp->c_key.k_csum) {
- ++nn->payload_misses;
+ nfsd_stats_payload_misses_inc(nn);
trace_nfsd_drc_mismatch(nn, key, rp);
}
@@ -407,7 +424,7 @@ int nfsd_cache_lookup(struct svc_rqst *rqstp)
rqstp->rq_cacherep = NULL;
if (type == RC_NOCACHE) {
- nfsdstats.rcnocache++;
+ nfsd_stats_rc_nocache_inc();
goto out;
}
@@ -429,12 +446,12 @@ int nfsd_cache_lookup(struct svc_rqst *rqstp)
goto found_entry;
}
- nfsdstats.rcmisses++;
+ nfsd_stats_rc_misses_inc();
rqstp->rq_cacherep = rp;
rp->c_state = RC_INPROG;
atomic_inc(&nn->num_drc_entries);
- nn->drc_mem_usage += sizeof(*rp);
+ nfsd_stats_drc_mem_usage_add(nn, sizeof(*rp));
/* go ahead and prune the cache */
prune_bucket(b, nn);
@@ -446,7 +463,7 @@ int nfsd_cache_lookup(struct svc_rqst *rqstp)
found_entry:
/* We found a matching entry which is either in progress or done. */
- nfsdstats.rchits++;
+ nfsd_stats_rc_hits_inc();
rtn = RC_DROPIT;
/* Request being processed */
@@ -548,7 +565,7 @@ void nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp)
return;
}
spin_lock(&b->cache_lock);
- nn->drc_mem_usage += bufsize;
+ nfsd_stats_drc_mem_usage_add(nn, bufsize);
lru_put_end(b, rp);
rp->c_secure = test_bit(RQ_SECURE, &rqstp->rq_flags);
rp->c_type = cachetype;
@@ -588,13 +605,18 @@ static int nfsd_reply_cache_stats_show(struct seq_file *m, void *v)
seq_printf(m, "max entries: %u\n", nn->max_drc_entries);
seq_printf(m, "num entries: %u\n",
- atomic_read(&nn->num_drc_entries));
+ atomic_read(&nn->num_drc_entries));
seq_printf(m, "hash buckets: %u\n", 1 << nn->maskbits);
- seq_printf(m, "mem usage: %u\n", nn->drc_mem_usage);
- seq_printf(m, "cache hits: %u\n", nfsdstats.rchits);
- seq_printf(m, "cache misses: %u\n", nfsdstats.rcmisses);
- seq_printf(m, "not cached: %u\n", nfsdstats.rcnocache);
- seq_printf(m, "payload misses: %u\n", nn->payload_misses);
+ seq_printf(m, "mem usage: %lld\n",
+ percpu_counter_sum_positive(&nn->counter[NFSD_NET_DRC_MEM_USAGE]));
+ seq_printf(m, "cache hits: %lld\n",
+ percpu_counter_sum_positive(&nfsdstats.counter[NFSD_STATS_RC_HITS]));
+ seq_printf(m, "cache misses: %lld\n",
+ percpu_counter_sum_positive(&nfsdstats.counter[NFSD_STATS_RC_MISSES]));
+ seq_printf(m, "not cached: %lld\n",
+ percpu_counter_sum_positive(&nfsdstats.counter[NFSD_STATS_RC_NOCACHE]));
+ seq_printf(m, "payload misses: %lld\n",
+ percpu_counter_sum_positive(&nn->counter[NFSD_NET_PAYLOAD_MISSES]));
seq_printf(m, "longest chain len: %u\n", nn->longest_chain);
seq_printf(m, "cachesize at longest: %u\n", nn->longest_chain_cachesize);
return 0;