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: J. Bruce Fields <bfields@redhat.com>
diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c
index 18e5e8e..da872f9 100644
--- a/net/sunrpc/cache.c
+++ b/net/sunrpc/cache.c
@@ -509,17 +509,6 @@
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 @@
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;
@@ -585,44 +554,90 @@
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)) {
- __unhash_deferred_req(&sleeper.handle);
- 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;
}
+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 (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)) {
+ __unhash_deferred_req(&sleeper.handle);
+ 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
+ */
+ return -ETIMEDOUT;
+ }
+ /* 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;
+}
+
+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)
{
struct cache_deferred_req *dreq;