On Sun, 3 Aug 2014 13:06:03 -0400
Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx> wrote:
> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> ---
> fs/nfsd/nfscache.c | 43 ++++++++++++++++++++-----------------------
> 1 file changed, 20 insertions(+), 23 deletions(-)
>
nit: There are a number of comments in nfscache.c that refer to the
cache_lock. Those should be updated since this will make them terribly
confusing later.
> 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;
> }
>
Other than that, this looks good to me:
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
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