diff options
| -rw-r--r-- | include/linux/sunrpc/cache.h | 3 | ||||
| -rw-r--r-- | net/sunrpc/cache.c | 59 | ||||
| -rw-r--r-- | net/sunrpc/svc_xprt.c | 11 |
3 files changed, 72 insertions, 1 deletions
diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h index ece432b7f87f..52a7d7224e90 100644 --- a/include/linux/sunrpc/cache.h +++ b/include/linux/sunrpc/cache.h @@ -125,6 +125,9 @@ struct cache_detail { */ struct cache_req { struct cache_deferred_req *(*defer)(struct cache_req *req); + int thread_wait; /* How long (jiffies) we can block the + * current thread to wait for updates. + */ }; /* this must be embedded in a deferred_request that is being * delayed awaiting cache-fill diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c index 8dc121955fdc..2c5297f245b4 100644 --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -509,10 +509,22 @@ static LIST_HEAD(cache_defer_list); static struct list_head cache_defer_hash[DFR_HASHSIZE]; static int cache_defer_cnt; +struct thread_deferred_req { + struct cache_deferred_req handle; + struct completion completion; +}; +static void cache_restart_thread(struct cache_deferred_req *dreq, int too_many) +{ + struct thread_deferred_req *dr = + container_of(dreq, struct thread_deferred_req, handle); + complete(&dr->completion); +} + static int cache_defer_req(struct cache_req *req, struct cache_head *item) { struct cache_deferred_req *dreq, *discard; int hash = DFR_HASH(item); + struct thread_deferred_req sleeper; if (cache_defer_cnt >= DFR_MAX) { /* too much in the cache, randomly drop this one, @@ -521,7 +533,15 @@ static int cache_defer_req(struct cache_req *req, struct cache_head *item) if (net_random()&1) return -ENOMEM; } - dreq = req->defer(req); + if (req->thread_wait) { + dreq = &sleeper.handle; + sleeper.completion = + COMPLETION_INITIALIZER_ONSTACK(sleeper.completion); + dreq->revisit = cache_restart_thread; + } else + dreq = req->defer(req); + + retry: if (dreq == NULL) return -ENOMEM; @@ -555,6 +575,43 @@ static int cache_defer_req(struct cache_req *req, struct cache_head *item) cache_revisit_request(item); return -EAGAIN; } + + if (dreq == &sleeper.handle) { + if (wait_for_completion_interruptible_timeout( + &sleeper.completion, req->thread_wait) <= 0) { + /* The completion wasn't completed, so we need + * to clean up + */ + spin_lock(&cache_defer_lock); + if (!list_empty(&sleeper.handle.hash)) { + list_del_init(&sleeper.handle.recent); + list_del_init(&sleeper.handle.hash); + cache_defer_cnt--; + spin_unlock(&cache_defer_lock); + } else { + /* cache_revisit_request already removed + * this from the hash table, but hasn't + * called ->revisit yet. It will very soon + * and we need to wait for it. + */ + spin_unlock(&cache_defer_lock); + wait_for_completion(&sleeper.completion); + } + } + if (test_bit(CACHE_PENDING, &item->flags)) { + /* item is still pending, try request + * deferral + */ + dreq = req->defer(req); + goto retry; + } + /* only return success if we actually deferred the + * request. In this case we waited until it was + * answered so no deferral has happened - rather + * an answer already exists. + */ + return -EEXIST; + } return 0; } diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index cbc084939dd8..8ff6840866fa 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -651,6 +651,11 @@ int svc_recv(struct svc_rqst *rqstp, long timeout) if (signalled() || kthread_should_stop()) return -EINTR; + /* Normally we will wait up to 5 seconds for any required + * cache information to be provided. + */ + rqstp->rq_chandle.thread_wait = 5*HZ; + spin_lock_bh(&pool->sp_lock); xprt = svc_xprt_dequeue(pool); if (xprt) { @@ -658,6 +663,12 @@ int svc_recv(struct svc_rqst *rqstp, long timeout) svc_xprt_get(xprt); rqstp->rq_reserved = serv->sv_max_mesg; atomic_add(rqstp->rq_reserved, &xprt->xpt_reserved); + + /* As there is a shortage of threads and this request + * had to be queue, don't allow the thread to wait so + * long for cache updates. + */ + rqstp->rq_chandle.thread_wait = 1*HZ; } else { /* No data pending. Go to sleep */ svc_thread_enqueue(pool, rqstp); |