xprtrdma's backward direction send and receive buffers are the same
size as the forechannel's inline threshold, and must be pre-
registered.
The consumer has no control over which receive buffer the adapter
chooses to catch an incoming backwards-direction call. Any receive
buffer can be used for either a forward reply or a backward call.
Thus both types of RPC message must all be the same size.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
net/sunrpc/xprtrdma/Makefile | 1
net/sunrpc/xprtrdma/backchannel.c | 204 +++++++++++++++++++++++++++++++++++++
net/sunrpc/xprtrdma/transport.c | 7 +
net/sunrpc/xprtrdma/verbs.c | 92 ++++++++++++++---
net/sunrpc/xprtrdma/xprt_rdma.h | 20 ++++
5 files changed, 309 insertions(+), 15 deletions(-)
create mode 100644 net/sunrpc/xprtrdma/backchannel.c
diff --git a/net/sunrpc/xprtrdma/Makefile b/net/sunrpc/xprtrdma/Makefile
index 48913de..33f99d3 100644
--- a/net/sunrpc/xprtrdma/Makefile
+++ b/net/sunrpc/xprtrdma/Makefile
@@ -5,3 +5,4 @@ rpcrdma-y := transport.o rpc_rdma.o verbs.o \
svc_rdma.o svc_rdma_transport.o \
svc_rdma_marshal.o svc_rdma_sendto.o svc_rdma_recvfrom.o \
module.o
+rpcrdma-$(CONFIG_SUNRPC_BACKCHANNEL) += backchannel.o
diff --git a/net/sunrpc/xprtrdma/backchannel.c b/net/sunrpc/xprtrdma/backchannel.c
new file mode 100644
index 0000000..c0a42ad
--- /dev/null
+++ b/net/sunrpc/xprtrdma/backchannel.c
@@ -0,0 +1,204 @@
+/*
+ * Copyright (c) 2015 Oracle. All rights reserved.
+ *
+ * Support for backward direction RPCs on RPC/RDMA.
+ */
+
+#include <linux/module.h>
+
+#include "xprt_rdma.h"
+
+#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
+# define RPCDBG_FACILITY RPCDBG_TRANS
+#endif
+
+static void rpcrdma_bc_free_rqst(struct rpcrdma_xprt *r_xprt,
+ struct rpc_rqst *rqst)
+{
+ struct rpcrdma_buffer *buf = &r_xprt->rx_buf;
+ struct rpcrdma_req *req = rpcr_to_rdmar(rqst);
+
+ spin_lock(&buf->rb_reqslock);
+ list_del(&req->rl_all);
+ spin_unlock(&buf->rb_reqslock);
+
+ rpcrdma_destroy_req(&r_xprt->rx_ia, req);
+
+ kfree(rqst);
+}
+
+static int rpcrdma_bc_setup_rqst(struct rpcrdma_xprt *r_xprt,
+ struct rpc_rqst *rqst)
+{
+ struct rpcrdma_ia *ia = &r_xprt->rx_ia;
+ struct rpcrdma_regbuf *rb;
+ struct rpcrdma_req *req;
+ struct xdr_buf *buf;
+ size_t size;
+
+ req = rpcrdma_create_req(r_xprt);
+ if (!req)
+ return -ENOMEM;
+ req->rl_backchannel = true;
+
+ size = RPCRDMA_INLINE_WRITE_THRESHOLD(rqst);
+ rb = rpcrdma_alloc_regbuf(ia, size, GFP_KERNEL);
+ if (IS_ERR(rb))
+ goto out_fail;
+ req->rl_rdmabuf = rb;
+
+ size += RPCRDMA_INLINE_READ_THRESHOLD(rqst);
+ rb = rpcrdma_alloc_regbuf(ia, size, GFP_KERNEL);
+ if (IS_ERR(rb))
+ goto out_fail;
+ rb->rg_owner = req;
+ req->rl_sendbuf = rb;
+ /* so that rpcr_to_rdmar works when receiving a request */
+ rqst->rq_buffer = (void *)req->rl_sendbuf->rg_base;
+
+ buf = &rqst->rq_snd_buf;
+ buf->head[0].iov_base = rqst->rq_buffer;
+ buf->head[0].iov_len = 0;
+ buf->tail[0].iov_base = NULL;
+ buf->tail[0].iov_len = 0;
+ buf->page_len = 0;
+ buf->len = 0;
+ buf->buflen = size;
+
+ return 0;
+
+out_fail:
+ rpcrdma_bc_free_rqst(r_xprt, rqst);
+ return -ENOMEM;
+}
+
+/* Allocate and add receive buffers to the rpcrdma_buffer's existing
+ * list of rep's. These are released when the transport is destroyed. */
+static int rpcrdma_bc_setup_reps(struct rpcrdma_xprt *r_xprt,
+ unsigned int count)
+{
+ struct rpcrdma_buffer *buffers = &r_xprt->rx_buf;
+ struct rpcrdma_rep *rep;
+ unsigned long flags;
+ int rc = 0;
+
+ while (count--) {
+ rep = rpcrdma_create_rep(r_xprt);
+ if (IS_ERR(rep)) {
+ pr_err("RPC: %s: reply buffer alloc failed\n",
+ __func__);
+ rc = PTR_ERR(rep);
+ break;
+ }
+
+ spin_lock_irqsave(&buffers->rb_lock, flags);
+ list_add(&rep->rr_list, &buffers->rb_recv_bufs);
+ spin_unlock_irqrestore(&buffers->rb_lock, flags);
+ }
+
+ return rc;
+}
+
+/**
+ * xprt_rdma_bc_setup - Pre-allocate resources for handling backchannel requests
+ * @xprt: transport associated with these backchannel resources
+ * @reqs: number of concurrent incoming requests to expect
+ *
+ * Returns 0 on success; otherwise a negative errno
+ */
+int xprt_rdma_bc_setup(struct rpc_xprt *xprt, unsigned int reqs)
+{
+ struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
+ struct rpcrdma_buffer *buffer = &r_xprt->rx_buf;
+ struct rpc_rqst *rqst;
+ unsigned int i;
+ int rc;
+
+ /* The backchannel reply path returns each rpc_rqst to the
+ * bc_pa_list _after_ the reply is sent. If the server is
+ * faster than the client, it can send another backward
+ * direction request before the rpc_rqst is returned to the
+ * list. The client rejects the request in this case.
+ *
+ * Twice as many rpc_rqsts are prepared to ensure there is
+ * always an rpc_rqst available as soon as a reply is sent.
+ */
+ for (i = 0; i < (reqs << 1); i++) {
+ rqst = kzalloc(sizeof(*rqst), GFP_KERNEL);
+ if (!rqst) {
+ pr_err("RPC: %s: Failed to create bc rpc_rqst\n",
+ __func__);
+ goto out_free;
+ }
+
+ rqst->rq_xprt = &r_xprt->rx_xprt;
+ INIT_LIST_HEAD(&rqst->rq_list);
+ INIT_LIST_HEAD(&rqst->rq_bc_list);
+
+ if (rpcrdma_bc_setup_rqst(r_xprt, rqst))
+ goto out_free;
+
+ spin_lock_bh(&xprt->bc_pa_lock);
+ list_add(&rqst->rq_bc_pa_list, &xprt->bc_pa_list);
+ spin_unlock_bh(&xprt->bc_pa_lock);
+ }
+
+ rc = rpcrdma_bc_setup_reps(r_xprt, reqs);
+ if (rc)
+ goto out_free;
+
+ rc = rpcrdma_ep_post_extra_recv(r_xprt, reqs);
+ if (rc)
+ goto out_free;
+
+ buffer->rb_bc_srv_max_requests = reqs;
+ request_module("svcrdma");
+
+ return 0;
+
+out_free:
+ xprt_rdma_bc_destroy(xprt, reqs);
+
+ pr_err("RPC: %s: setup backchannel transport failed\n", __func__);
+ return -ENOMEM;
+}
+
+/**
+ * xprt_rdma_bc_destroy - Release resources for handling backchannel requests
+ * @xprt: transport associated with these backchannel resources
+ * @reqs: number of incoming requests to destroy; ignored
+ */
+void xprt_rdma_bc_destroy(struct rpc_xprt *xprt, unsigned int reqs)
+{
+ struct rpcrdma_xprt *r_xprt = rpcx_to_rdmax(xprt);
+ struct rpc_rqst *rqst, *tmp;
+
+ spin_lock_bh(&xprt->bc_pa_lock);
+ list_for_each_entry_safe(rqst, tmp, &xprt->bc_pa_list, rq_bc_pa_list) {
+ list_del(&rqst->rq_bc_pa_list);
+ spin_unlock_bh(&xprt->bc_pa_lock);
+
+ rpcrdma_bc_free_rqst(r_xprt, rqst);
+
+ spin_lock_bh(&xprt->bc_pa_lock);
+ }
+ spin_unlock_bh(&xprt->bc_pa_lock);
+}
+
+/**
+ * xprt_rdma_bc_free_rqst - Release a backchannel rqst
+ * @rqst: request to release
+ */
+void xprt_rdma_bc_free_rqst(struct rpc_rqst *rqst)
+{
+ struct rpc_xprt *xprt = rqst->rq_xprt;
+
+ smp_mb__before_atomic();
+ WARN_ON_ONCE(!test_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state));
+ clear_bit(RPC_BC_PA_IN_USE, &rqst->rq_bc_pa_state);
+ smp_mb__after_atomic();
+
+ spin_lock_bh(&xprt->bc_pa_lock);
+ list_add_tail(&rqst->rq_bc_pa_list, &xprt->bc_pa_list);
+ spin_unlock_bh(&xprt->bc_pa_lock);
+}
diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
index e9e5ed7..e3871a6 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -705,7 +705,12 @@ static struct rpc_xprt_ops xprt_rdma_procs = {
.print_stats = xprt_rdma_print_stats,
.enable_swap = xprt_rdma_enable_swap,
.disable_swap = xprt_rdma_disable_swap,
- .inject_disconnect = xprt_rdma_inject_disconnect
+ .inject_disconnect = xprt_rdma_inject_disconnect,
+#if defined(CONFIG_SUNRPC_BACKCHANNEL)
+ .bc_setup = xprt_rdma_bc_setup,
+ .bc_free_rqst = xprt_rdma_bc_free_rqst,
+ .bc_destroy = xprt_rdma_bc_destroy,
+#endif
};
static struct xprt_class xprt_rdma = {
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index 8d99214..1e4a948 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -877,7 +877,22 @@ retry:
}
rc = ep->rep_connected;
} else {
+ struct rpcrdma_xprt *r_xprt;
+ unsigned int extras;
+
dprintk("RPC: %s: connected\n", __func__);
+
+ r_xprt = container_of(ia, struct rpcrdma_xprt, rx_ia);
+ extras = r_xprt->rx_buf.rb_bc_srv_max_requests;
+
+ if (extras) {
+ rc = rpcrdma_ep_post_extra_recv(r_xprt, extras);
+ if (rc)
+ pr_err("%s: could not post "
+ "extra receive buffers: %i\n",
+ __func__, rc);
+ rc = 0;
+ }
}
out:
@@ -914,20 +929,25 @@ rpcrdma_ep_disconnect(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
}
}
-static struct rpcrdma_req *
+struct rpcrdma_req *
rpcrdma_create_req(struct rpcrdma_xprt *r_xprt)
{
+ struct rpcrdma_buffer *buffer = &r_xprt->rx_buf;
struct rpcrdma_req *req;
req = kzalloc(sizeof(*req), GFP_KERNEL);
if (req == NULL)
return ERR_PTR(-ENOMEM);
+ INIT_LIST_HEAD(&req->rl_free);
+ spin_lock(&buffer->rb_reqslock);
+ list_add(&req->rl_all, &buffer->rb_allreqs);
+ spin_unlock(&buffer->rb_reqslock);
req->rl_buffer = &r_xprt->rx_buf;
return req;
}
-static struct rpcrdma_rep *
+struct rpcrdma_rep *
rpcrdma_create_rep(struct rpcrdma_xprt *r_xprt)
{
struct rpcrdma_create_data_internal *cdata = &r_xprt->rx_data;
@@ -965,6 +985,7 @@ rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
int i, rc;
buf->rb_max_requests = r_xprt->rx_data.max_requests;
+ buf->rb_bc_srv_max_requests = 0;
spin_lock_init(&buf->rb_lock);
rc = ia->ri_ops->ro_init(r_xprt);
@@ -972,6 +993,8 @@ rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
goto out;
INIT_LIST_HEAD(&buf->rb_send_bufs);
+ INIT_LIST_HEAD(&buf->rb_allreqs);
+ spin_lock_init(&buf->rb_reqslock);
for (i = 0; i < buf->rb_max_requests; i++) {
struct rpcrdma_req *req;
@@ -982,6 +1005,7 @@ rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
rc = PTR_ERR(req);
goto out;
}
+ req->rl_backchannel = false;
list_add(&req->rl_free, &buf->rb_send_bufs);
}
@@ -1008,19 +1032,13 @@ out:
static void
rpcrdma_destroy_rep(struct rpcrdma_ia *ia, struct rpcrdma_rep *rep)
{
- if (!rep)
- return;
-
rpcrdma_free_regbuf(ia, rep->rr_rdmabuf);
kfree(rep);
}
-static void
+void
rpcrdma_destroy_req(struct rpcrdma_ia *ia, struct rpcrdma_req *req)
{
- if (!req)
- return;
-
rpcrdma_free_regbuf(ia, req->rl_sendbuf);
rpcrdma_free_regbuf(ia, req->rl_rdmabuf);
kfree(req);
@@ -1040,14 +1058,20 @@ rpcrdma_buffer_destroy(struct rpcrdma_buffer *buf)
rpcrdma_destroy_rep(ia, rep);
}
- while (!list_empty(&buf->rb_send_bufs)) {
- struct rpcrdma_req *req = list_entry(buf->rb_send_bufs.next,
+ spin_lock(&buf->rb_reqslock);
+ while (!list_empty(&buf->rb_allreqs)) {
+ struct rpcrdma_req *req = list_entry(buf->rb_allreqs.next,
struct rpcrdma_req,
- rl_free);
+ rl_all);
+
+ list_del(&req->rl_all);
+ spin_unlock(&buf->rb_reqslock);
- list_del(&req->rl_free);
rpcrdma_destroy_req(ia, req);
+
+ spin_lock(&buf->rb_reqslock);
}
+ spin_unlock(&buf->rb_reqslock);
ia->ri_ops->ro_destroy(buf);
}
@@ -1094,7 +1118,7 @@ rpcrdma_buffer_get_locked(struct rpcrdma_buffer *buf)
rep = list_first_entry(&buf->rb_recv_bufs,
struct rpcrdma_rep, rr_list);
- list_del(&rep->rr_list);
+ list_del_init(&rep->rr_list);
return rep;
}
@@ -1337,6 +1361,46 @@ rpcrdma_ep_post_recv(struct rpcrdma_ia *ia,
return rc;
}
+/**
+ * rpcrdma_bc_post_recv - Post buffers to catch incoming backchannel requests
+ * @r_xprt: transport associated with these backchannel resources
+ * @min_reqs: minimum number of incoming requests expected
+ *
+ * Returns zero if all requested buffers were posted, or a negative errno.
+ */
+int
+rpcrdma_ep_post_extra_recv(struct rpcrdma_xprt *r_xprt, unsigned int count)
+{
+ struct rpcrdma_ia *ia = &r_xprt->rx_ia;
+ struct rpcrdma_ep *ep = &r_xprt->rx_ep;
+ struct rpcrdma_buffer *buffers = &r_xprt->rx_buf;
+ struct rpcrdma_rep *rep;
+ unsigned long flags;
+ int rc;
+
+ while (count--) {
+ rep = NULL;
+ spin_lock_irqsave(&buffers->rb_lock, flags);
+ if (!list_empty(&buffers->rb_recv_bufs))
+ rep = rpcrdma_buffer_get_locked(buffers);
+ spin_unlock_irqrestore(&buffers->rb_lock, flags);
+ if (!rep) {
+ pr_err("%s: no extra receive buffers\n", __func__);
+ return -ENOMEM;
+ }
+
+ rc = rpcrdma_ep_post_recv(ia, ep, rep);
+ if (rc) {
+ spin_lock_irqsave(&buffers->rb_lock, flags);
+ rpcrdma_buffer_put_locked(rep, buffers);
+ spin_unlock_irqrestore(&buffers->rb_lock, flags);
+ return rc;
+ }
+ }
+
+ return 0;
+}
+
/* How many chunk list items fit within our inline buffers?
*/
unsigned int
diff --git a/net/sunrpc/xprtrdma/xprt_rdma.h b/net/sunrpc/xprtrdma/xprt_rdma.h
index e6a358f..2ca0567 100644
--- a/net/sunrpc/xprtrdma/xprt_rdma.h
+++ b/net/sunrpc/xprtrdma/xprt_rdma.h
@@ -262,6 +262,9 @@ struct rpcrdma_req {
struct rpcrdma_regbuf *rl_rdmabuf;
struct rpcrdma_regbuf *rl_sendbuf;
struct rpcrdma_mr_seg rl_segments[RPCRDMA_MAX_SEGS];
+
+ struct list_head rl_all;
+ bool rl_backchannel;
};
static inline struct rpcrdma_req *
@@ -290,6 +293,10 @@ struct rpcrdma_buffer {
struct list_head rb_send_bufs;
struct list_head rb_recv_bufs;
u32 rb_max_requests;
+
+ u32 rb_bc_srv_max_requests;
+ spinlock_t rb_reqslock; /* protect rb_allreqs */
+ struct list_head rb_allreqs;
};
#define rdmab_to_ia(b) (&container_of((b), struct rpcrdma_xprt, rx_buf)->rx_ia)
@@ -410,6 +417,9 @@ int rpcrdma_ep_post_recv(struct rpcrdma_ia *, struct rpcrdma_ep *,
/*
* Buffer calls - xprtrdma/verbs.c
*/
+struct rpcrdma_req *rpcrdma_create_req(struct rpcrdma_xprt *);
+struct rpcrdma_rep *rpcrdma_create_rep(struct rpcrdma_xprt *);
+void rpcrdma_destroy_req(struct rpcrdma_ia *, struct rpcrdma_req *);
int rpcrdma_buffer_create(struct rpcrdma_xprt *);
void rpcrdma_buffer_destroy(struct rpcrdma_buffer *);
@@ -426,6 +436,7 @@ void rpcrdma_free_regbuf(struct rpcrdma_ia *,
struct rpcrdma_regbuf *);
unsigned int rpcrdma_max_segments(struct rpcrdma_xprt *);
+int rpcrdma_ep_post_extra_recv(struct rpcrdma_xprt *, unsigned int);
int frwr_alloc_recovery_wq(void);
void frwr_destroy_recovery_wq(void);
@@ -490,6 +501,15 @@ int rpcrdma_marshal_req(struct rpc_rqst *);
int xprt_rdma_init(void);
void xprt_rdma_cleanup(void);
+/* Backchannel calls - xprtrdma/backchannel.c
+ */
+#if defined(CONFIG_SUNRPC_BACKCHANNEL)
+int xprt_rdma_bc_setup(struct rpc_xprt *, unsigned int);
+int rpcrdma_bc_post_recv(struct rpcrdma_xprt *, unsigned int);
+void xprt_rdma_bc_free_rqst(struct rpc_rqst *);
+void xprt_rdma_bc_destroy(struct rpc_xprt *, unsigned int);
+#endif /* CONFIG_SUNRPC_BACKCHANNEL */
+
/* Temporary NFS request map cache. Created in svc_rdma.c */
extern struct kmem_cache *svc_rdma_map_cachep;
/* WR context cache. Created in svc_rdma.c */
--
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