/**
* xprt_rdma_alloc_slot - allocate an rpc_rqst
* @xprt: controlling RPC transport
* @task: RPC task requesting a fresh rpc_rqst
*
* tk_status values:
* %0 if task->tk_rqstp points to a fresh rpc_rqst
* %-EAGAIN if no rpc_rqst is available; queued on backlog
*/
static void
xprt_rdma_alloc_slot(struct rpc_xprt *xprt, struct rpc_task *task)
{
struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
struct rpcrdma_req *req;
req = rpcrdma_buffer_get(&r_xprt->rx_buf);
if (!req)
goto out_sleep;
task->tk_rqstp = &req->rl_slot;
task->tk_status = 0;
return;
out_sleep:
rpc_sleep_on(&xprt->backlog, task, NULL);
task->tk_status = -EAGAIN;
}
/*
* The RDMA allocate/free functions need the task structure as a place
* to hide the struct rpcrdma_req, which is necessary for the actual send/recv
* sequence.
*
* The RPC layer allocates both send and receive buffers in the same call
* (rq_send_buf and rq_rcv_buf are both part of a single contiguous buffer).
* We may register rq_rcv_buf when using reply chunks.
*/
static void *
xprt_rdma_allocate(struct rpc_task *task, size_t size)
{
struct rpc_xprt *xprt = task->tk_rqstp->rq_xprt;
struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
struct rpcrdma_regbuf *rb;
struct rpcrdma_req *req;
size_t min_size;
gfp_t flags;
req = rpcrdma_buffer_get(&r_xprt->rx_buf);
if (req == NULL)
return NULL;
flags = GFP_NOIO | __GFP_NOWARN;
if (RPC_IS_SWAPPER(task))
flags = __GFP_MEMALLOC | GFP_NOWAIT | __GFP_NOWARN;
if (req->rl_rdmabuf == NULL)
goto out_rdmabuf;
if (req->rl_sendbuf == NULL)
goto out_sendbuf;
if (size > req->rl_sendbuf->rg_size)
goto out_sendbuf;
out:
dprintk("RPC: %s: size %zd, request 0x%p\n", __func__, size, req);
req->rl_connect_cookie = 0; /* our reserved value */
return req->rl_sendbuf->rg_base;
out_rdmabuf:
min_size = RPCRDMA_INLINE_WRITE_THRESHOLD(task->tk_rqstp);
rb = rpcrdma_alloc_regbuf(&r_xprt->rx_ia, min_size, flags);
if (IS_ERR(rb))
goto out_fail;
req->rl_rdmabuf = rb;
out_sendbuf:
/* XDR encoding and RPC/RDMA marshaling of this request has not
* yet occurred. Thus a lower bound is needed to prevent buffer
* overrun during marshaling.
*
* RPC/RDMA marshaling may choose to send payload bearing ops
* inline, if the result is smaller than the inline threshold.
* The value of the "size" argument accounts for header
* requirements but not for the payload in these cases.
*
* Likewise, allocate enough space to receive a reply up to the
* size of the inline threshold.
*
* It's unlikely that both the send header and the received
* reply will be large, but slush is provided here to allow
* flexibility when marshaling.
*/
min_size = RPCRDMA_INLINE_READ_THRESHOLD(task->tk_rqstp);
min_size += RPCRDMA_INLINE_WRITE_THRESHOLD(task->tk_rqstp);
if (size < min_size)
size = min_size;
rb = rpcrdma_alloc_regbuf(&r_xprt->rx_ia, size, flags);
if (IS_ERR(rb))
goto out_fail;
rb->rg_owner = req;
r_xprt->rx_stats.hardway_register_count += size;
rpcrdma_free_regbuf(&r_xprt->rx_ia, req->rl_sendbuf);
req->rl_sendbuf = rb;
goto out;
out_fail:
rpcrdma_buffer_put(req);
r_xprt->rx_stats.failed_marshal_count++;
return NULL;
}
