From 89a26b3d295d35fefcc994cb0cf3817d0ff432d5 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Wed, 6 Aug 2014 13:44:24 -0400 Subject: [PATCH] nfsd: split DRC global spinlock into per-bucket locks Signed-off-by: Trond Myklebust Signed-off-by: J. Bruce Fields --- fs/nfsd/nfscache.c | 43 ++++++++++++++++++++----------------------- 1 file changed, 20 insertions(+), 23 deletions(-) diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c index dc909091349b..74603654b7f9 100644 --- a/fs/nfsd/nfscache.c +++ b/fs/nfsd/nfscache.c @@ -29,6 +29,7 @@ struct nfsd_drc_bucket { struct list_head lru_head; + spinlock_t cache_lock; }; static struct nfsd_drc_bucket *drc_hashtbl; @@ -79,7 +80,6 @@ static struct shrinker nfsd_reply_cache_shrinker = { * A cache entry is "single use" if c_state == RC_INPROG * Otherwise, it when accessing _prev or _next, the lock must be held. */ -static DEFINE_SPINLOCK(cache_lock); static DECLARE_DELAYED_WORK(cache_cleaner, cache_cleaner_func); /* @@ -154,11 +154,11 @@ nfsd_reply_cache_free_locked(struct svc_cacherep *rp) } static void -nfsd_reply_cache_free(struct svc_cacherep *rp) +nfsd_reply_cache_free(struct nfsd_drc_bucket *b, struct svc_cacherep *rp) { - spin_lock(&cache_lock); + spin_lock(&b->cache_lock); nfsd_reply_cache_free_locked(rp); - spin_unlock(&cache_lock); + spin_unlock(&b->cache_lock); } int nfsd_reply_cache_init(void) @@ -180,8 +180,10 @@ int nfsd_reply_cache_init(void) drc_hashtbl = kcalloc(hashsize, sizeof(*drc_hashtbl), GFP_KERNEL); if (!drc_hashtbl) goto out_nomem; - for (i = 0; i < hashsize; i++) + for (i = 0; i < hashsize; i++) { INIT_LIST_HEAD(&drc_hashtbl[i].lru_head); + spin_lock_init(&drc_hashtbl[i].cache_lock); + } drc_hashsize = hashsize; return 0; @@ -265,9 +267,13 @@ prune_cache_entries(void) for (i = 0; i < drc_hashsize; i++) { struct nfsd_drc_bucket *b = &drc_hashtbl[i]; + if (list_empty(&b->lru_head)) + continue; + spin_lock(&b->cache_lock); freed += prune_bucket(b); if (!list_empty(&b->lru_head)) cancel = false; + spin_unlock(&b->cache_lock); } /* @@ -282,9 +288,7 @@ prune_cache_entries(void) static void cache_cleaner_func(struct work_struct *unused) { - spin_lock(&cache_lock); prune_cache_entries(); - spin_unlock(&cache_lock); } static unsigned long @@ -296,12 +300,7 @@ nfsd_reply_cache_count(struct shrinker *shrink, struct shrink_control *sc) static unsigned long nfsd_reply_cache_scan(struct shrinker *shrink, struct shrink_control *sc) { - unsigned long freed; - - spin_lock(&cache_lock); - freed = prune_cache_entries(); - spin_unlock(&cache_lock); - return freed; + return prune_cache_entries(); } /* * Walk an xdr_buf and get a CRC for at most the first RC_CSUMLEN bytes @@ -426,14 +425,14 @@ nfsd_cache_lookup(struct svc_rqst *rqstp) * preallocate an entry. */ rp = nfsd_reply_cache_alloc(); - spin_lock(&cache_lock); + spin_lock(&b->cache_lock); if (likely(rp)) { atomic_inc(&num_drc_entries); drc_mem_usage += sizeof(*rp); } /* go ahead and prune the cache */ - prune_cache_entries(); + prune_bucket(b); found = nfsd_cache_search(b, rqstp, csum); if (found) { @@ -470,7 +469,7 @@ nfsd_cache_lookup(struct svc_rqst *rqstp) } rp->c_type = RC_NOCACHE; out: - spin_unlock(&cache_lock); + spin_unlock(&b->cache_lock); return rtn; found_entry: @@ -548,7 +547,7 @@ nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp) /* Don't cache excessive amounts of data and XDR failures */ if (!statp || len > (256 >> 2)) { - nfsd_reply_cache_free(rp); + nfsd_reply_cache_free(b, rp); return; } @@ -563,23 +562,23 @@ nfsd_cache_update(struct svc_rqst *rqstp, int cachetype, __be32 *statp) bufsize = len << 2; cachv->iov_base = kmalloc(bufsize, GFP_KERNEL); if (!cachv->iov_base) { - nfsd_reply_cache_free(rp); + nfsd_reply_cache_free(b, rp); return; } cachv->iov_len = bufsize; memcpy(cachv->iov_base, statp, bufsize); break; case RC_NOCACHE: - nfsd_reply_cache_free(rp); + nfsd_reply_cache_free(b, rp); return; } - spin_lock(&cache_lock); + spin_lock(&b->cache_lock); drc_mem_usage += bufsize; lru_put_end(b, rp); rp->c_secure = rqstp->rq_secure; rp->c_type = cachetype; rp->c_state = RC_DONE; - spin_unlock(&cache_lock); + spin_unlock(&b->cache_lock); return; } @@ -610,7 +609,6 @@ nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *data) */ 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", atomic_read(&num_drc_entries)); @@ -622,7 +620,6 @@ static int nfsd_reply_cache_stats_show(struct seq_file *m, void *v) seq_printf(m, "payload misses: %u\n", payload_misses); seq_printf(m, "longest chain len: %u\n", longest_chain); seq_printf(m, "cachesize at longest: %u\n", longest_chain_cachesize); - spin_unlock(&cache_lock); return 0; } -- 2.20.1