From 31e60f52224197dc989a82237905dfe643183f7c Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Wed, 6 Aug 2014 13:44:23 -0400 Subject: [PATCH] nfsd: convert num_drc_entries to an atomic_t ...so we can remove the spinlocking around it. Signed-off-by: Trond Myklebust Signed-off-by: J. Bruce Fields --- fs/nfsd/nfscache.c | 28 ++++++++++++---------------- 1 file changed, 12 insertions(+), 16 deletions(-) diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c index 8abec475f80f..dc909091349b 100644 --- a/fs/nfsd/nfscache.c +++ b/fs/nfsd/nfscache.c @@ -47,7 +47,7 @@ static unsigned int drc_hashsize; */ /* total number of entries */ -static unsigned int num_drc_entries; +static atomic_t num_drc_entries; /* cache misses due only to checksum comparison failures */ static unsigned int payload_misses; @@ -148,7 +148,7 @@ nfsd_reply_cache_free_locked(struct svc_cacherep *rp) kfree(rp->c_replvec.iov_base); } list_del(&rp->c_lru); - --num_drc_entries; + atomic_dec(&num_drc_entries); drc_mem_usage -= sizeof(*rp); kmem_cache_free(drc_slab, rp); } @@ -167,7 +167,7 @@ int nfsd_reply_cache_init(void) unsigned int i; max_drc_entries = nfsd_cache_size_limit(); - num_drc_entries = 0; + atomic_set(&num_drc_entries, 0); hashsize = nfsd_hashsize(max_drc_entries); maskbits = ilog2(hashsize); @@ -242,7 +242,7 @@ prune_bucket(struct nfsd_drc_bucket *b) */ if (rp->c_state == RC_INPROG) continue; - if (num_drc_entries <= max_drc_entries && + if (atomic_read(&num_drc_entries) <= max_drc_entries && time_before(jiffies, rp->c_timestamp + RC_EXPIRE)) break; nfsd_reply_cache_free_locked(rp); @@ -290,13 +290,7 @@ cache_cleaner_func(struct work_struct *unused) static unsigned long nfsd_reply_cache_count(struct shrinker *shrink, struct shrink_control *sc) { - unsigned long num; - - spin_lock(&cache_lock); - num = num_drc_entries; - spin_unlock(&cache_lock); - - return num; + return atomic_read(&num_drc_entries); } static unsigned long @@ -386,11 +380,12 @@ nfsd_cache_search(struct nfsd_drc_bucket *b, struct svc_rqst *rqstp, /* tally hash chain length stats */ if (entries > longest_chain) { longest_chain = entries; - longest_chain_cachesize = num_drc_entries; + longest_chain_cachesize = atomic_read(&num_drc_entries); } else if (entries == longest_chain) { /* prefer to keep the smallest cachesize possible here */ - longest_chain_cachesize = min(longest_chain_cachesize, - num_drc_entries); + longest_chain_cachesize = min_t(unsigned int, + longest_chain_cachesize, + atomic_read(&num_drc_entries)); } return ret; @@ -433,7 +428,7 @@ nfsd_cache_lookup(struct svc_rqst *rqstp) rp = nfsd_reply_cache_alloc(); spin_lock(&cache_lock); if (likely(rp)) { - ++num_drc_entries; + atomic_inc(&num_drc_entries); drc_mem_usage += sizeof(*rp); } @@ -617,7 +612,8 @@ static int nfsd_reply_cache_stats_show(struct seq_file *m, void *v) { spin_lock(&cache_lock); seq_printf(m, "max entries: %u\n", max_drc_entries); - seq_printf(m, "num entries: %u\n", num_drc_entries); + seq_printf(m, "num entries: %u\n", + atomic_read(&num_drc_entries)); seq_printf(m, "hash buckets: %u\n", 1 << maskbits); seq_printf(m, "mem usage: %u\n", drc_mem_usage); seq_printf(m, "cache hits: %u\n", nfsdstats.rchits); -- 2.20.1