/**
* @brief Decrement the call path refcnt on a cache entry.
*
* We assert req->rq_u1 now points to the corresonding duplicate request
* cache entry (dv).
*
* In the common case, a refcnt of 0 indicates that dv is cached. If
* also dv->state == DUPREQ_DELETED, the request entry has been discarded
* and should be destroyed here.
*
* @param[in] req The svc_req structure.
* @param[in] func The function descriptor for this request type
*/
void nfs_dupreq_rele(struct svc_req *req, const nfs_function_desc_t *func)
{
dupreq_entry_t *dv = (dupreq_entry_t *) req->rq_u1;
/* no-cache cleanup */
if (dv == (void *)DUPREQ_NOCACHE) {
LogFullDebug(COMPONENT_DUPREQ, "releasing no-cache res %p",
req->rq_u2);
func->free_function(req->rq_u2);
free_nfs_res(req->rq_u2);
goto out;
}
pthread_mutex_lock(&dv->mtx);
LogFullDebug(COMPONENT_DUPREQ,
"releasing dv=%p xid=%u on DRC=%p state=%s, " "refcnt=%d",
dv, dv->hin.tcp.rq_xid, dv->hin.drc,
dupreq_state_table[dv->state], dv->refcnt);
(dv->refcnt)--;
if (dv->refcnt == 0) {
if (dv->state == DUPREQ_DELETED) {
pthread_mutex_unlock(&dv->mtx);
/* deep free */
nfs_dupreq_free_dupreq(dv);
return;
}
}
pthread_mutex_unlock(&dv->mtx);
out:
/* dispose RPC header */
if (req->rq_auth)
SVCAUTH_RELEASE(req->rq_auth, req);
/* XXX */
if (req->rq_rtaddr.len)
mem_free(req->rq_rtaddr.buf, req->rq_rtaddr.len);
(void)free_rpc_msg(req->rq_msg);
return;
}
/**
* @brief Start a duplicate request transaction
*
* Finds any matching request entry in the cache, if one exists, else
* creates one in the START state. On any non-error return, the refcnt
* of the corresponding entry is incremented.
*
* @param[in] reqnfs The NFS request data
* @param[in] req The request to be cached
*
* @retval DUPREQ_SUCCESS if successful.
* @retval DUPREQ_INSERT_MALLOC_ERROR if an error occured during insertion.
*/
dupreq_status_t nfs_dupreq_start(nfs_request_t *reqnfs,
struct svc_req *req)
{
dupreq_status_t status = DUPREQ_SUCCESS;
dupreq_entry_t *dv, *dk = NULL;
bool release_dk = true;
nfs_res_t *res = NULL;
drc_t *drc;
/* Disabled? */
if (nfs_param.core_param.drc.disabled) {
req->rq_u1 = (void *)DUPREQ_NOCACHE;
res = alloc_nfs_res();
goto out;
}
req->rq_u1 = (void *)DUPREQ_BAD_ADDR1;
req->rq_u2 = (void *)DUPREQ_BAD_ADDR1;
drc = nfs_dupreq_get_drc(req);
if (!drc) {
status = DUPREQ_INSERT_MALLOC_ERROR;
goto out;
}
switch (drc->type) {
case DRC_TCP_V4:
if (reqnfs->funcdesc->service_function == nfs4_Compound) {
if (!nfs_dupreq_v4_cacheable(reqnfs)) {
/* for such requests, we merely thread
* the request through for later
* cleanup--all v41 caching is handled
* by the v41 slot reply cache */
req->rq_u1 = (void *)DUPREQ_NOCACHE;
res = alloc_nfs_res();
goto out;
}
}
break;
default:
/* likewise for other protocol requests we may not or choose not
* to cache */
if (!(reqnfs->funcdesc->dispatch_behaviour & CAN_BE_DUP)) {
req->rq_u1 = (void *)DUPREQ_NOCACHE;
res = alloc_nfs_res();
goto out;
}
break;
}
dk = alloc_dupreq();
if (dk == NULL) {
release_dk = false;
status = DUPREQ_ERROR;
goto release_dk;
}
dk->hin.drc = drc; /* trans. call path ref to dv */
switch (drc->type) {
case DRC_TCP_V4:
case DRC_TCP_V3:
dk->hin.tcp.rq_xid = req->rq_xid;
/* XXX needed? */
dk->hin.rq_prog = req->rq_prog;
dk->hin.rq_vers = req->rq_vers;
dk->hin.rq_proc = req->rq_proc;
break;
case DRC_UDP_V234:
dk->hin.tcp.rq_xid = req->rq_xid;
if (unlikely(!copy_xprt_addr(&dk->hin.addr, req->rq_xprt))) {
status = DUPREQ_INSERT_MALLOC_ERROR;
goto release_dk;
}
dk->hin.rq_prog = req->rq_prog;
dk->hin.rq_vers = req->rq_vers;
dk->hin.rq_proc = req->rq_proc;
break;
default:
/* error */
status = DUPREQ_ERROR;
goto release_dk;
}
/* TI-RPC computed checksum */
dk->hk = req->rq_cksum;
dk->state = DUPREQ_START;
dk->timestamp = time(NULL);
{
struct opr_rbtree_node *nv;
struct rbtree_x_part *t =
rbtx_partition_of_scalar(&drc->xt, dk->hk);
PTHREAD_MUTEX_lock(&t->mtx); /* partition lock */
nv = rbtree_x_cached_lookup(&drc->xt, t, &dk->rbt_k, dk->hk);
if (nv) {
/* cached request */
dv = opr_containerof(nv, dupreq_entry_t, rbt_k);
PTHREAD_MUTEX_lock(&dv->mtx);
if (unlikely(dv->state == DUPREQ_START)) {
status = DUPREQ_BEING_PROCESSED;
} else {
/* satisfy req from the DRC, incref,
extend window */
res = dv->res;
PTHREAD_MUTEX_lock(&drc->mtx);
drc_inc_retwnd(drc);
PTHREAD_MUTEX_unlock(&drc->mtx);
status = DUPREQ_EXISTS;
(dv->refcnt)++;
}
LogDebug(COMPONENT_DUPREQ,
"dupreq hit dk=%p, dk xid=%u cksum %" PRIu64
" state=%s", dk, dk->hin.tcp.rq_xid, dk->hk,
dupreq_state_table[dk->state]);
req->rq_u1 = dv;
PTHREAD_MUTEX_unlock(&dv->mtx);
} else {
/* new request */
res = req->rq_u2 = dk->res = alloc_nfs_res();
(void)rbtree_x_cached_insert(&drc->xt, t, &dk->rbt_k,
dk->hk);
(dk->refcnt)++;
/* add to q tail */
PTHREAD_MUTEX_lock(&drc->mtx);
TAILQ_INSERT_TAIL(&drc->dupreq_q, dk, fifo_q);
++(drc->size);
PTHREAD_MUTEX_unlock(&drc->mtx);
req->rq_u1 = dk;
release_dk = false;
dv = dk;
}
PTHREAD_MUTEX_unlock(&t->mtx);
}
LogFullDebug(COMPONENT_DUPREQ,
"starting dv=%p xid=%u on DRC=%p state=%s, status=%s, refcnt=%d",
dv, dk->hin.tcp.rq_xid, drc,
dupreq_state_table[dv->state], dupreq_status_table[status],
dv->refcnt);
release_dk:
if (release_dk)
nfs_dupreq_free_dupreq(dk);
nfs_dupreq_put_drc(req->rq_xprt, drc, DRC_FLAG_NONE); /* dk ref */
out:
if (res)
reqnfs->res_nfs = req->rq_u2 = res;
return status;
}
/**
* @brief Completes a request in the cache
*
* Completes a cache insertion operation begun in nfs_dupreq_start.
* The refcnt of the corresponding duplicate request entry is unchanged
* (ie, the caller must still call nfs_dupreq_rele).
*
* In contrast with the prior DRC implementation, completing a request
* in the current implementation may under normal conditions cause one
* or more cached requests to be retired. Requests are retired in the
* order they were inserted. The primary retire algorithm is a high
* water mark, and a windowing heuristic. One or more requests will be
* retired if the water mark/timeout is exceeded, and if a no duplicate
* requests have been found in the cache in a configurable window of
* immediately preceding requests. A timeout may supplement the water mark,
* in future.
*
* req->rq_u1 has either a magic value, or points to a duplicate request
* cache entry allocated in nfs_dupreq_start.
*
* @param[in] req The request
* @param[in] res_nfs The response
*
* @return DUPREQ_SUCCESS if successful.
* @return DUPREQ_INSERT_MALLOC_ERROR if an error occured.
*/
dupreq_status_t nfs_dupreq_finish(struct svc_req *req, nfs_res_t *res_nfs)
{
dupreq_entry_t *ov = NULL, *dv = (dupreq_entry_t *)req->rq_u1;
dupreq_status_t status = DUPREQ_SUCCESS;
struct rbtree_x_part *t;
drc_t *drc = NULL;
/* do nothing if req is marked no-cache */
if (dv == (void *)DUPREQ_NOCACHE)
goto out;
/* do nothing if nfs_dupreq_start failed completely */
if (dv == (void *)DUPREQ_BAD_ADDR1)
goto out;
PTHREAD_MUTEX_lock(&dv->mtx);
dv->res = res_nfs;
dv->timestamp = time(NULL);
dv->state = DUPREQ_COMPLETE;
drc = dv->hin.drc;
PTHREAD_MUTEX_unlock(&dv->mtx);
/* cond. remove from q head */
PTHREAD_MUTEX_lock(&drc->mtx);
LogFullDebug(COMPONENT_DUPREQ,
"completing dv=%p xid=%u on DRC=%p state=%s, status=%s, refcnt=%d",
dv, dv->hin.tcp.rq_xid, drc,
dupreq_state_table[dv->state], dupreq_status_table[status],
dv->refcnt);
/* ok, do the new retwnd calculation here. then, put drc only if
* we retire an entry */
if (drc_should_retire(drc)) {
/* again: */
ov = TAILQ_FIRST(&drc->dupreq_q);
if (likely(ov)) {
/* finished request count against retwnd */
drc_dec_retwnd(drc);
/* check refcnt */
if (ov->refcnt > 0) {
/* ov still in use, apparently */
goto unlock;
}
/* remove q entry */
TAILQ_REMOVE(&drc->dupreq_q, ov, fifo_q);
--(drc->size);
/* remove dict entry */
t = rbtx_partition_of_scalar(&drc->xt, ov->hk);
/* interlock */
PTHREAD_MUTEX_unlock(&drc->mtx);
PTHREAD_MUTEX_lock(&t->mtx); /* partition lock */
rbtree_x_cached_remove(&drc->xt, t, &ov->rbt_k, ov->hk);
PTHREAD_MUTEX_unlock(&t->mtx);
LogDebug(COMPONENT_DUPREQ,
"retiring ov=%p xid=%u on DRC=%p state=%s, status=%s, refcnt=%d",
ov, ov->hin.tcp.rq_xid,
ov->hin.drc, dupreq_state_table[dv->state],
dupreq_status_table[status], ov->refcnt);
/* deep free ov */
nfs_dupreq_free_dupreq(ov);
goto out;
}
}
unlock:
PTHREAD_MUTEX_unlock(&drc->mtx);
out:
return status;
}
