diff options
author | J. Bruce Fields <bfields@redhat.com> | 2010-08-26 16:56:23 -0400 |
---|---|---|
committer | J. Bruce Fields <bfields@redhat.com> | 2010-09-07 20:20:31 -0400 |
commit | 3211af1119174fbe8b676422b74870cdd51d7314 (patch) | |
tree | d5ad448787a9f32cb30aed6c43bc1bbbac77c600 /net/sunrpc/cache.c | |
parent | 6610f720e9e8103c22d1f1ccf8fbb695550a571f (diff) |
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>
Diffstat (limited to 'net/sunrpc/cache.c')
-rw-r--r-- | net/sunrpc/cache.c | 143 |
1 files changed, 79 insertions, 64 deletions
diff --git a/net/sunrpc/cache.c b/net/sunrpc/cache.c index 18e5e8e6f622..da872f9fe1e0 100644 --- a/net/sunrpc/cache.c +++ b/net/sunrpc/cache.c @@ -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; @@ -585,42 +554,88 @@ static int cache_defer_req(struct cache_req *req, struct cache_head *item) cache_revisit_request(item); return -EAGAIN; } + return 0; +} - 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 +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. */ - dreq = req->defer(req); - goto retry; + spin_unlock(&cache_defer_lock); + wait_for_completion(&sleeper.completion); } - /* 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. + } + if (test_bit(CACHE_PENDING, &item->flags)) { + /* item is still pending, try request + * deferral */ - return -EEXIST; + return -ETIMEDOUT; } - return 0; + /* 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) |