SUNRPC: Support dynamic slot allocation for TCP connections
Allow the number of available slots to grow with the TCP window size.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index ea7b3c1..be85cf0 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -935,25 +935,66 @@
spin_unlock_bh(&xprt->transport_lock);
}
+static struct rpc_rqst *xprt_dynamic_alloc_slot(struct rpc_xprt *xprt, gfp_t gfp_flags)
+{
+ struct rpc_rqst *req = ERR_PTR(-EAGAIN);
+
+ if (!atomic_add_unless(&xprt->num_reqs, 1, xprt->max_reqs))
+ goto out;
+ req = kzalloc(sizeof(struct rpc_rqst), gfp_flags);
+ if (req != NULL)
+ goto out;
+ atomic_dec(&xprt->num_reqs);
+ req = ERR_PTR(-ENOMEM);
+out:
+ return req;
+}
+
+static bool xprt_dynamic_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
+{
+ if (atomic_add_unless(&xprt->num_reqs, -1, xprt->min_reqs)) {
+ kfree(req);
+ return true;
+ }
+ return false;
+}
+
static void xprt_alloc_slot(struct rpc_task *task)
{
struct rpc_xprt *xprt = task->tk_xprt;
+ struct rpc_rqst *req;
- task->tk_status = 0;
if (!list_empty(&xprt->free)) {
- struct rpc_rqst *req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
- list_del_init(&req->rq_list);
- task->tk_rqstp = req;
- xprt_request_init(task, xprt);
- return;
+ req = list_entry(xprt->free.next, struct rpc_rqst, rq_list);
+ list_del(&req->rq_list);
+ goto out_init_req;
}
- dprintk("RPC: waiting for request slot\n");
+ req = xprt_dynamic_alloc_slot(xprt, GFP_NOWAIT);
+ if (!IS_ERR(req))
+ goto out_init_req;
+ switch (PTR_ERR(req)) {
+ case -ENOMEM:
+ rpc_delay(task, HZ >> 2);
+ dprintk("RPC: dynamic allocation of request slot "
+ "failed! Retrying\n");
+ break;
+ case -EAGAIN:
+ rpc_sleep_on(&xprt->backlog, task, NULL);
+ dprintk("RPC: waiting for request slot\n");
+ }
task->tk_status = -EAGAIN;
- rpc_sleep_on(&xprt->backlog, task, NULL);
+ return;
+out_init_req:
+ task->tk_status = 0;
+ task->tk_rqstp = req;
+ xprt_request_init(task, xprt);
}
static void xprt_free_slot(struct rpc_xprt *xprt, struct rpc_rqst *req)
{
+ if (xprt_dynamic_free_slot(xprt, req))
+ return;
+
memset(req, 0, sizeof(*req)); /* mark unused */
spin_lock(&xprt->reserve_lock);
@@ -972,7 +1013,9 @@
}
}
-struct rpc_xprt *xprt_alloc(struct net *net, int size, int num_prealloc)
+struct rpc_xprt *xprt_alloc(struct net *net, size_t size,
+ unsigned int num_prealloc,
+ unsigned int max_alloc)
{
struct rpc_xprt *xprt;
struct rpc_rqst *req;
@@ -992,7 +1035,12 @@
}
if (i < num_prealloc)
goto out_free;
- xprt->max_reqs = num_prealloc;
+ if (max_alloc > num_prealloc)
+ xprt->max_reqs = max_alloc;
+ else
+ xprt->max_reqs = num_prealloc;
+ xprt->min_reqs = num_prealloc;
+ atomic_set(&xprt->num_reqs, num_prealloc);
return xprt;
@@ -1036,7 +1084,6 @@
if (!xprt_lock_write(xprt, task))
return;
- task->tk_status = -EIO;
spin_lock(&xprt->reserve_lock);
xprt_alloc_slot(task);
spin_unlock(&xprt->reserve_lock);
@@ -1057,6 +1104,7 @@
{
struct rpc_rqst *req = task->tk_rqstp;
+ INIT_LIST_HEAD(&req->rq_list);
req->rq_timeout = task->tk_client->cl_timeout->to_initval;
req->rq_task = task;
req->rq_xprt = xprt;