[RFC 03/10] nfsd41: sunrpc: Added rpc server-side backchannel handling

Benny Halevy
2009-04-30T23:06:01Z

From: Rahul Iyer <iyer@netapp.com>

FIXME: bhalevy: write up commit message

Signed-off-by: Rahul Iyer <iyer@netapp.com>
Signed-off-by: Mike Sager <sager@netapp.com>
Signed-off-by: Marc Eshel <eshel@almaden.ibm.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>

When the call direction is a reply, copy the xid and call direction into the
req->rq_private_buf.head[0].iov_base otherwise rpc_verify_header returns
rpc_garbage.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
[get rid of CONFIG_NFSD_V4_1]
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
---
include/linux/sunrpc/clnt.h | 1 +
include/linux/sunrpc/svcsock.h | 1 +
include/linux/sunrpc/xprt.h | 2 +
net/sunrpc/clnt.c | 1 +
net/sunrpc/svcsock.c | 68 ++++++++++-
net/sunrpc/xprt.c | 41 ++++++-
net/sunrpc/xprtsock.c | 278 +++++++++++++++++++++++++++++++++++++++-
7 files changed, 381 insertions(+), 11 deletions(-)

diff --git a/include/linux/sunrpc/clnt.h b/include/linux/sunrpc/clnt.h
index c39a210..cf9a8ec 100644
--- a/include/linux/sunrpc/clnt.h
+++ b/include/linux/sunrpc/clnt.h
@@ -110,6 +110,7 @@ struct rpc_create_args {
rpc_authflavor_t authflavor;
unsigned long flags;
char *client_name;
+ struct svc_sock *bc_sock; /* NFSv4.1 backchannel */
};

/* Values for "flags" field */
diff --git a/include/linux/sunrpc/svcsock.h b/include/linux/sunrpc/svcsock.h
index 8271631..19228f4 100644
--- a/include/linux/sunrpc/svcsock.h
+++ b/include/linux/sunrpc/svcsock.h
@@ -28,6 +28,7 @@ struct svc_sock {
/* private TCP part */
u32 sk_reclen; /* length of record */
u32 sk_tcplen; /* current read length */
+ struct rpc_xprt *sk_bc_xprt; /* NFSv4.1 backchannel xprt */
};

/*
diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h
index 1758d9f..063a6a7 100644
--- a/include/linux/sunrpc/xprt.h
+++ b/include/linux/sunrpc/xprt.h
@@ -174,6 +174,7 @@ struct rpc_xprt {
spinlock_t reserve_lock; /* lock slot table */
u32 xid; /* Next XID value to use */
struct rpc_task * snd_task; /* Task blocked in send */
+ struct svc_sock *bc_sock; /* NFSv4.1 backchannel */
struct list_head recv;

struct {
@@ -197,6 +198,7 @@ struct xprt_create {
struct sockaddr * srcaddr; /* optional local address */
struct sockaddr * dstaddr; /* remote peer address */
size_t addrlen;
+ struct svc_sock *bc_sock; /* NFSv4.1 backchannel */
};

struct xprt_class {
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index 5abab09..3dc847f 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -266,6 +266,7 @@ struct rpc_clnt *rpc_create(struct rpc_create_args *args)
.srcaddr = args->saddress,
.dstaddr = args->address,
.addrlen = args->addrsize,
+ .bc_sock = args->bc_sock,
};
char servername[48];

diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index 4e6d406..619764e 100644
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -49,6 +49,7 @@
#include <linux/sunrpc/msg_prot.h>
#include <linux/sunrpc/svcsock.h>
#include <linux/sunrpc/stats.h>
+#include <linux/sunrpc/xprt.h>

#define RPCDBG_FACILITY RPCDBG_SVCXPRT

@@ -825,6 +826,7 @@ static int svc_tcp_recvfrom(struct svc_rqst *rqstp)
int len;
struct kvec *vec;
int pnum, vlen;
+ struct rpc_rqst *req = NULL;

dprintk("svc: tcp_recv %p data %d conn %d close %d\n",
svsk, test_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags),
@@ -891,12 +893,65 @@ static int svc_tcp_recvfrom(struct svc_rqst *rqstp)
len = svsk->sk_reclen;
set_bit(XPT_DATA, &svsk->sk_xprt.xpt_flags);

+ /*
+ * We have enough data for the whole tcp record. Let's try and read the
+ * first 8 bytes to get the xid and the call direction. We can use this
+ * to figure out if this is a call or a reply to a callback. If
+ * sk_reclen is < 8 (xid and calldir), then this is a malformed packet.
+ * In that case, don't bother with the calldir and just read the data.
+ * It will be rejected in svc_process.
+ */
+
vec = rqstp->rq_vec;
vec[0] = rqstp->rq_arg.head[0];
vlen = PAGE_SIZE;
+
+ if (len >= 8) {
+ u32 *p;
+ u32 xid;
+ u32 calldir;
+
+ len = svc_recvfrom(rqstp, vec, 1, 8);
+ if (len < 0)
+ goto error;
+
+ p = (u32 *)rqstp->rq_arg.head[0].iov_base;
+ xid = *p++;
+ calldir = *p;
+
+ if (calldir) {
+ /* REPLY */
+ if (svsk->sk_bc_xprt)
+ req = xprt_lookup_rqst(svsk->sk_bc_xprt, xid);
+ if (req) {
+ memcpy(&req->rq_private_buf, &req->rq_rcv_buf,
+ sizeof(struct xdr_buf));
+ /* copy the xid and call direction */
+ memcpy(req->rq_private_buf.head[0].iov_base,
+ rqstp->rq_arg.head[0].iov_base, 8);
+ vec[0] = req->rq_private_buf.head[0];
+ } else
+ printk(KERN_NOTICE
+ "%s: Got unrecognized reply: "
+ "calldir 0x%x sk_bc_xprt %p xid %08x\n",
+ __func__, ntohl(calldir),
+ svsk->sk_bc_xprt, xid);
+ }
+
+ if (!calldir || !req)
+ vec[0] = rqstp->rq_arg.head[0];
+
+ vec[0].iov_base += 8;
+ vec[0].iov_len -= 8;
+ len = svsk->sk_reclen - 8;
+ vlen -= 8;
+ }
+
pnum = 1;
while (vlen < len) {
- vec[pnum].iov_base = page_address(rqstp->rq_pages[pnum]);
+ vec[pnum].iov_base = (req) ?
+ page_address(req->rq_private_buf.pages[pnum - 1]) :
+ page_address(rqstp->rq_pages[pnum]);
vec[pnum].iov_len = PAGE_SIZE;
pnum++;
vlen += PAGE_SIZE;
@@ -908,6 +963,16 @@ static int svc_tcp_recvfrom(struct svc_rqst *rqstp)
if (len < 0)
goto error;

+ /*
+ * Account for the 8 bytes we read earlier
+ */
+ len += 8;
+
+ if (req) {
+ xprt_complete_rqst(req->rq_task, len);
+ len = 0;
+ goto out;
+ }
dprintk("svc: TCP complete record (%d bytes)\n", len);
rqstp->rq_arg.len = len;
rqstp->rq_arg.page_base = 0;
@@ -921,6 +986,7 @@ static int svc_tcp_recvfrom(struct svc_rqst *rqstp)
rqstp->rq_xprt_ctxt = NULL;
rqstp->rq_prot = IPPROTO_TCP;

+out:
/* Reset TCP read info */
svsk->sk_reclen = 0;
svsk->sk_tcplen = 0;
diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
index a0bfe53..03f175e 100644
--- a/net/sunrpc/xprt.c
+++ b/net/sunrpc/xprt.c
@@ -1015,6 +1015,27 @@ void xprt_release(struct rpc_task *task)
spin_unlock(&xprt->reserve_lock);
}

+/*
+ * The autoclose function for the back channel
+ *
+ * The callback channel should never close the channel,
+ * let the forechannel do that.
+ */
+static void bc_autoclose(struct work_struct *work)
+{
+ return;
+}
+
+
+/*
+ * The autodisconnect routine for the back channel. We never disconnect
+ */
+static void
+bc_init_autodisconnect(unsigned long data)
+{
+ return;
+}
+
/**
* xprt_create_transport - create an RPC transport
* @args: rpc transport creation arguments
@@ -1051,9 +1072,16 @@ found:

INIT_LIST_HEAD(&xprt->free);
INIT_LIST_HEAD(&xprt->recv);
- INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
- setup_timer(&xprt->timer, xprt_init_autodisconnect,
- (unsigned long)xprt);
+ if (args->bc_sock) {
+ INIT_WORK(&xprt->task_cleanup, bc_autoclose);
+ setup_timer(&xprt->timer, bc_init_autodisconnect,
+ (unsigned long)xprt);
+ } else {
+ INIT_WORK(&xprt->task_cleanup, xprt_autoclose);
+ setup_timer(&xprt->timer, xprt_init_autodisconnect,
+ (unsigned long)xprt);
+ }
+
xprt->last_used = jiffies;
xprt->cwnd = RPC_INITCWND;
xprt->bind_index = 0;
@@ -1073,6 +1101,13 @@ found:
dprintk("RPC: created transport %p with %u slots\n", xprt,
xprt->max_reqs);

+ /*
+ * Since we don't want connections for the backchannel, we set
+ * the xprt status to connected
+ */
+ if (args->bc_sock)
+ xprt_set_connected(xprt);
+
return xprt;
}

diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
index d40ff50..067d205 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -32,6 +32,7 @@
#include <linux/tcp.h>
#include <linux/sunrpc/clnt.h>
#include <linux/sunrpc/sched.h>
+#include <linux/sunrpc/svcsock.h>
#include <linux/sunrpc/xprtsock.h>
#include <linux/file.h>

@@ -1966,6 +1967,219 @@ static void xs_tcp_print_stats(struct rpc_xprt *xprt, struct seq_file *seq)
xprt->stat.bklog_u);
}

+/*
+ * The connect worker for the backchannel
+ * This should never be called as we should never need to connect
+ */
+static void bc_connect_worker(struct work_struct *work)
+{
+ BUG();
+}
+
+/*
+ * The set_port routine of the rpc_xprt_ops. This is related to the portmapper
+ * and should never be called
+ */
+
+static void bc_set_port(struct rpc_xprt *xprt, unsigned short port)
+{
+ BUG();
+}
+
+/*
+ * The connect routine for the backchannel rpc_xprt ops
+ * Again, should never be called!
+ */
+
+static void bc_connect(struct rpc_task *task)
+{
+ BUG();
+}
+
+struct rpc_buffer {
+ size_t len;
+ char data[];
+};
+/*
+ * Allocate a bunch of pages for a scratch buffer for the rpc code. The reason
+ * we allocate pages instead doing a kmalloc like rpc_malloc is because we want
+ * to use the server side send routines.
+ */
+void *bc_malloc(struct rpc_task *task, size_t size)
+{
+ struct page *page;
+ struct rpc_buffer *buf;
+
+ BUG_ON(size > PAGE_SIZE - sizeof(struct rpc_buffer));
+ page = alloc_page(GFP_KERNEL);
+
+ if (!page)
+ return NULL;
+
+ buf = page_address(page);
+ buf->len = PAGE_SIZE;
+
+ return buf->data;
+}
+
+/*
+ * Free the space allocated in the bc_alloc routine
+ */
+void bc_free(void *buffer)
+{
+ struct rpc_buffer *buf;
+
+ if (!buffer)
+ return;
+
+ buf = container_of(buffer, struct rpc_buffer, data);
+ free_pages((unsigned long)buf, get_order(buf->len));
+}
+
+/*
+ * Use the svc_sock to send the callback. Must be called with svsk->sk_mutex
+ * held. Borrows heavily from svc_tcp_sendto and xs_tcp_semd_request.
+ */
+static int bc_sendto(struct rpc_rqst *req)
+{
+ int total_len;
+ int len;
+ int size;
+ int result;
+ struct xdr_buf *xbufp = &req->rq_snd_buf;
+ struct page **pages = xbufp->pages;
+ unsigned int flags = MSG_MORE;
+ unsigned int pglen = xbufp->page_len;
+ size_t base = xbufp->page_base;
+ struct rpc_xprt *xprt = req->rq_xprt;
+ struct sock_xprt *transport =
+ container_of(xprt, struct sock_xprt, xprt);
+ struct socket *sock = transport->sock;
+
+ total_len = xbufp->len;
+
+ /*
+ * Set up the rpc header and record marker stuff
+ */
+ xs_encode_tcp_record_marker(xbufp);
+
+ /*
+ * The RPC message is divided into 3 pieces:
+ * - The header: This is what most of the smaller RPC messages consist
+ * of. Often the whole message is in this.
+ *
+ * - xdr->pages: This is a list of pages that contain data, for
+ * example in a write request or while using rpcsec gss
+ *
+ * - The tail: This is the rest of the rpc message
+ *
+ * First we send the header, then the pages and then finally the tail.
+ * The code borrows heavily from svc_sendto.
+ */
+
+ /*
+ * Send the head
+ */
+ if (total_len == xbufp->head[0].iov_len)
+ flags = 0;
+
+ len = sock->ops->sendpage(sock, virt_to_page(xbufp->head[0].iov_base),
+ (unsigned long)xbufp->head[0].iov_base & ~PAGE_MASK,
+ xbufp->head[0].iov_len, flags);
+
+ if (len != xbufp->head[0].iov_len)
+ goto out;
+
+ /*
+ * send page data
+ *
+ * Check the amount of data to be sent. If it is less than the
+ * remaining page, then send it else send the current page
+ */
+
+ size = PAGE_SIZE - base < pglen ? PAGE_SIZE - base : pglen;
+ while (pglen > 0) {
+ if (total_len == size)
+ flags = 0;
+ result = sock->ops->sendpage(sock, *pages, base, size, flags);
+ if (result > 0)
+ len += result;
+ if (result != size)
+ goto out;
+ total_len -= size;
+ pglen -= size;
+ size = PAGE_SIZE < pglen ? PAGE_SIZE : pglen;
+ base = 0;
+ pages++;
+ }
+ /*
+ * send tail
+ */
+ if (xbufp->tail[0].iov_len) {
+ result = sock->ops->sendpage(sock,
+ xbufp->tail[0].iov_base,
+ (unsigned long)xbufp->tail[0].iov_base & ~PAGE_MASK,
+ xbufp->tail[0].iov_len,
+ 0);
+
+ if (result > 0)
+ len += result;
+ }
+out:
+ if (len != xbufp->len)
+ printk(KERN_NOTICE "Error sending entire callback!\n");
+
+ return len;
+}
+
+/*
+ * The send routine. Borrows from svc_send
+ */
+static int bc_send_request(struct rpc_task *task)
+{
+ struct rpc_rqst *req = task->tk_rqstp;
+ struct rpc_xprt *bc_xprt = req->rq_xprt;
+ struct svc_xprt *xprt;
+ struct svc_sock *svsk;
+ u32 len;
+
+ dprintk("sending request with xid: %08x\n", ntohl(req->rq_xid));
+ /*
+ * Get the server socket associated with this callback xprt
+ */
+ svsk = bc_xprt->bc_sock;
+ xprt = &svsk->sk_xprt;
+
+ mutex_lock(&xprt->xpt_mutex);
+ if (test_bit(XPT_DEAD, &xprt->xpt_flags))
+ len = -ENOTCONN;
+ else
+ len = bc_sendto(req);
+ mutex_unlock(&xprt->xpt_mutex);
+
+ return 0;
+
+}
+
+/*
+ * The close routine. Since this is client initiated, we do nothing
+ */
+
+static void bc_close(struct rpc_xprt *xprt)
+{
+ return;
+}
+
+/*
+ * The xprt destroy routine. Again, because this connection is client
+ * initiated, we do nothing
+ */
+
+static void bc_destroy(struct rpc_xprt *xprt)
+{
+ return;
+}
+
static struct rpc_xprt_ops xs_udp_ops = {
.set_buffer_size = xs_udp_set_buffer_size,
.reserve_xprt = xprt_reserve_xprt_cong,
@@ -1999,6 +2213,24 @@ static struct rpc_xprt_ops xs_tcp_ops = {
.print_stats = xs_tcp_print_stats,
};

+/*
+ * The rpc_xprt_ops for the server backchannel
+ */
+
+static struct rpc_xprt_ops bc_tcp_ops = {
+ .reserve_xprt = xprt_reserve_xprt,
+ .release_xprt = xprt_release_xprt,
+ .set_port = bc_set_port,
+ .connect = bc_connect,
+ .buf_alloc = bc_malloc,
+ .buf_free = bc_free,
+ .send_request = bc_send_request,
+ .set_retrans_timeout = xprt_set_retrans_timeout_def,
+ .close = bc_close,
+ .destroy = bc_destroy,
+ .print_stats = xs_tcp_print_stats,
+};
+
static struct rpc_xprt *xs_setup_xprt(struct xprt_create *args,
unsigned int slot_table_size)
{
@@ -2131,13 +2363,29 @@ static struct rpc_xprt *xs_setup_tcp(struct xprt_create *args)
xprt->tsh_size = sizeof(rpc_fraghdr) / sizeof(u32);
xprt->max_payload = RPC_MAX_FRAGMENT_SIZE;

- xprt->bind_timeout = XS_BIND_TO;
- xprt->connect_timeout = XS_TCP_CONN_TO;
- xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
- xprt->idle_timeout = XS_IDLE_DISC_TO;
+ if (args->bc_sock) {
+ /* backchannel */
+ xprt_set_bound(xprt);
+ INIT_DELAYED_WORK(&transport->connect_worker,
+ bc_connect_worker);
+ xprt->bind_timeout = 0;
+ xprt->connect_timeout = 0;
+ xprt->reestablish_timeout = 0;
+ xprt->idle_timeout = (~0);

- xprt->ops = &xs_tcp_ops;
- xprt->timeout = &xs_tcp_default_timeout;
+ /*
+ * The backchannel uses the same socket connection as the
+ * forechannel
+ */
+ xprt->bc_sock = args->bc_sock;
+ xprt->bc_sock->sk_bc_xprt = xprt;
+ transport->sock = xprt->bc_sock->sk_sock;
+ transport->inet = xprt->bc_sock->sk_sk;
+
+ xprt->ops = &bc_tcp_ops;
+
+ goto next;
+ }

switch (addr->sa_family) {
case AF_INET:
@@ -2145,13 +2393,29 @@ static struct rpc_xprt *xs_setup_tcp(struct xprt_create *args)
xprt_set_bound(xprt);

INIT_DELAYED_WORK(&transport->connect_worker, xs_tcp_connect_worker4);
- xs_format_ipv4_peer_addresses(xprt, "tcp", RPCBIND_NETID_TCP);
break;
case AF_INET6:
if (((struct sockaddr_in6 *)addr)->sin6_port != htons(0))
xprt_set_bound(xprt);

INIT_DELAYED_WORK(&transport->connect_worker, xs_tcp_connect_worker6);
+ break;
+ }
+ xprt->bind_timeout = XS_BIND_TO;
+ xprt->connect_timeout = XS_TCP_CONN_TO;
+ xprt->reestablish_timeout = XS_TCP_INIT_REEST_TO;
+ xprt->idle_timeout = XS_IDLE_DISC_TO;
+
+ xprt->ops = &xs_tcp_ops;
+
+next:
+ xprt->timeout = &xs_tcp_default_timeout;
+
+ switch (addr->sa_family) {
+ case AF_INET:
+ xs_format_ipv4_peer_addresses(xprt, "tcp", RPCBIND_NETID_TCP);
+ break;
+ case AF_INET6:
xs_format_ipv6_peer_addresses(xprt, "tcp", RPCBIND_NETID_TCP6);
break;
default:
--
1.6.2.1