Commit 3211af11 authored by J. Bruce Fields's avatar J. Bruce Fields
Browse files

svcrpc: cache deferral cleanup 



Attempt to make obvious the first-try-sleeping-then-try-deferral logic
by putting that logic into a top-level function that calls helpers.

Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent 6610f720

net/sunrpc/cache.c

+79 −64
Original line number Diff line number Diff line
@@ -509,17 +509,6 @@ 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 void __unhash_deferred_req(struct cache_deferred_req *dreq)

{

	list_del_init(&dreq->recent);
@@ -537,29 +526,9 @@ static void __hash_deferred_req(struct cache_deferred_req *dreq, struct cache_he 
	list_add(&dreq->hash, &cache_defer_hash[hash]);

}



static int cache_defer_req(struct cache_req *req, struct cache_head *item)

static int setup_deferral(struct cache_deferred_req *dreq, struct cache_head *item)

{

	struct cache_deferred_req *dreq, *discard;

	struct thread_deferred_req sleeper;



	if (cache_defer_cnt >= DFR_MAX) {

		/* too much in the cache, randomly drop this one,

		 * or continue and drop the oldest below

		 */

		if (net_random()&1)

			return -ENOMEM;

	}

	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;

	struct cache_deferred_req *discard;



	dreq->item = item;
@@ -585,8 +554,34 @@ static int cache_defer_req(struct cache_req *req, struct cache_head *item) 
		cache_revisit_request(item);

		return -EAGAIN;

	}

	return 0;

}



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_wait_req(struct cache_req *req, struct cache_head *item)

{

	struct thread_deferred_req sleeper;

	struct cache_deferred_req *dreq = &sleeper.handle;

	int ret;



	sleeper.completion = COMPLETION_INITIALIZER_ONSTACK(sleeper.completion);

	dreq->revisit = cache_restart_thread;



	ret = setup_deferral(dreq, item);

	if (ret)

		return ret;



	if (dreq == &sleeper.handle) {

	if (wait_for_completion_interruptible_timeout(

		    &sleeper.completion, req->thread_wait) <= 0) {

		/* The completion wasn't completed, so we need
@@ -610,8 +605,7 @@ static int cache_defer_req(struct cache_req *req, struct cache_head *item) 
		/* item is still pending, try request

		 * deferral

		 */

			dreq = req->defer(req);

			goto retry;

		return -ETIMEDOUT;

	}

	/* only return success if we actually deferred the

	 * request.  In this case we waited until it was
@@ -620,7 +614,28 @@ static int cache_defer_req(struct cache_req *req, struct cache_head *item) 
	 */

	return -EEXIST;

}

	return 0;



static int cache_defer_req(struct cache_req *req, struct cache_head *item)

{

	struct cache_deferred_req *dreq;

	int ret;



	if (cache_defer_cnt >= DFR_MAX) {

		/* too much in the cache, randomly drop this one,

		 * or continue and drop the oldest

		 */

		if (net_random()&1)

			return -ENOMEM;

	}

	if (req->thread_wait) {

		ret = cache_wait_req(req, item);

		if (ret != -ETIMEDOUT)

			return ret;

	}

	dreq = req->defer(req);

	if (dreq == NULL)

		return -ENOMEM;

	return setup_deferral(dreq, item);

}



static void cache_revisit_request(struct cache_head *item)