linux_dsm_epyc7002/net/9p/trans_rdma.c
Thomas Gleixner 1f32761322 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 188
Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license version 2 as
  published by the free software foundation this program is
  distributed in the hope that it will be useful but without any
  warranty without even the implied warranty of merchantability or
  fitness for a particular purpose see the gnu general public license
  for more details you should have received a copy of the gnu general
  public license along with this program if not write to free software
  foundation 51 franklin street fifth floor boston ma 02111 1301 usa

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 27 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Reviewed-by: Steve Winslow <swinslow@gmail.com>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190528170026.981318839@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-30 11:29:21 -07:00

771 lines
18 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* linux/fs/9p/trans_rdma.c
*
* RDMA transport layer based on the trans_fd.c implementation.
*
* Copyright (C) 2008 by Tom Tucker <tom@opengridcomputing.com>
* Copyright (C) 2006 by Russ Cox <rsc@swtch.com>
* Copyright (C) 2004-2005 by Latchesar Ionkov <lucho@ionkov.net>
* Copyright (C) 2004-2008 by Eric Van Hensbergen <ericvh@gmail.com>
* Copyright (C) 1997-2002 by Ron Minnich <rminnich@sarnoff.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/in.h>
#include <linux/module.h>
#include <linux/net.h>
#include <linux/ipv6.h>
#include <linux/kthread.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/un.h>
#include <linux/uaccess.h>
#include <linux/inet.h>
#include <linux/idr.h>
#include <linux/file.h>
#include <linux/parser.h>
#include <linux/semaphore.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <net/9p/9p.h>
#include <net/9p/client.h>
#include <net/9p/transport.h>
#include <rdma/ib_verbs.h>
#include <rdma/rdma_cm.h>
#define P9_PORT 5640
#define P9_RDMA_SQ_DEPTH 32
#define P9_RDMA_RQ_DEPTH 32
#define P9_RDMA_SEND_SGE 4
#define P9_RDMA_RECV_SGE 4
#define P9_RDMA_IRD 0
#define P9_RDMA_ORD 0
#define P9_RDMA_TIMEOUT 30000 /* 30 seconds */
#define P9_RDMA_MAXSIZE (1024*1024) /* 1MB */
/**
* struct p9_trans_rdma - RDMA transport instance
*
* @state: tracks the transport state machine for connection setup and tear down
* @cm_id: The RDMA CM ID
* @pd: Protection Domain pointer
* @qp: Queue Pair pointer
* @cq: Completion Queue pointer
* @timeout: Number of uSecs to wait for connection management events
* @privport: Whether a privileged port may be used
* @port: The port to use
* @sq_depth: The depth of the Send Queue
* @sq_sem: Semaphore for the SQ
* @rq_depth: The depth of the Receive Queue.
* @rq_sem: Semaphore for the RQ
* @excess_rc : Amount of posted Receive Contexts without a pending request.
* See rdma_request()
* @addr: The remote peer's address
* @req_lock: Protects the active request list
* @cm_done: Completion event for connection management tracking
*/
struct p9_trans_rdma {
enum {
P9_RDMA_INIT,
P9_RDMA_ADDR_RESOLVED,
P9_RDMA_ROUTE_RESOLVED,
P9_RDMA_CONNECTED,
P9_RDMA_FLUSHING,
P9_RDMA_CLOSING,
P9_RDMA_CLOSED,
} state;
struct rdma_cm_id *cm_id;
struct ib_pd *pd;
struct ib_qp *qp;
struct ib_cq *cq;
long timeout;
bool privport;
u16 port;
int sq_depth;
struct semaphore sq_sem;
int rq_depth;
struct semaphore rq_sem;
atomic_t excess_rc;
struct sockaddr_in addr;
spinlock_t req_lock;
struct completion cm_done;
};
/**
* p9_rdma_context - Keeps track of in-process WR
*
* @busa: Bus address to unmap when the WR completes
* @req: Keeps track of requests (send)
* @rc: Keepts track of replies (receive)
*/
struct p9_rdma_req;
struct p9_rdma_context {
struct ib_cqe cqe;
dma_addr_t busa;
union {
struct p9_req_t *req;
struct p9_fcall rc;
};
};
/**
* p9_rdma_opts - Collection of mount options
* @port: port of connection
* @sq_depth: The requested depth of the SQ. This really doesn't need
* to be any deeper than the number of threads used in the client
* @rq_depth: The depth of the RQ. Should be greater than or equal to SQ depth
* @timeout: Time to wait in msecs for CM events
*/
struct p9_rdma_opts {
short port;
bool privport;
int sq_depth;
int rq_depth;
long timeout;
};
/*
* Option Parsing (code inspired by NFS code)
*/
enum {
/* Options that take integer arguments */
Opt_port, Opt_rq_depth, Opt_sq_depth, Opt_timeout,
/* Options that take no argument */
Opt_privport,
Opt_err,
};
static match_table_t tokens = {
{Opt_port, "port=%u"},
{Opt_sq_depth, "sq=%u"},
{Opt_rq_depth, "rq=%u"},
{Opt_timeout, "timeout=%u"},
{Opt_privport, "privport"},
{Opt_err, NULL},
};
static int p9_rdma_show_options(struct seq_file *m, struct p9_client *clnt)
{
struct p9_trans_rdma *rdma = clnt->trans;
if (rdma->port != P9_PORT)
seq_printf(m, ",port=%u", rdma->port);
if (rdma->sq_depth != P9_RDMA_SQ_DEPTH)
seq_printf(m, ",sq=%u", rdma->sq_depth);
if (rdma->rq_depth != P9_RDMA_RQ_DEPTH)
seq_printf(m, ",rq=%u", rdma->rq_depth);
if (rdma->timeout != P9_RDMA_TIMEOUT)
seq_printf(m, ",timeout=%lu", rdma->timeout);
if (rdma->privport)
seq_puts(m, ",privport");
return 0;
}
/**
* parse_opts - parse mount options into rdma options structure
* @params: options string passed from mount
* @opts: rdma transport-specific structure to parse options into
*
* Returns 0 upon success, -ERRNO upon failure
*/
static int parse_opts(char *params, struct p9_rdma_opts *opts)
{
char *p;
substring_t args[MAX_OPT_ARGS];
int option;
char *options, *tmp_options;
opts->port = P9_PORT;
opts->sq_depth = P9_RDMA_SQ_DEPTH;
opts->rq_depth = P9_RDMA_RQ_DEPTH;
opts->timeout = P9_RDMA_TIMEOUT;
opts->privport = false;
if (!params)
return 0;
tmp_options = kstrdup(params, GFP_KERNEL);
if (!tmp_options) {
p9_debug(P9_DEBUG_ERROR,
"failed to allocate copy of option string\n");
return -ENOMEM;
}
options = tmp_options;
while ((p = strsep(&options, ",")) != NULL) {
int token;
int r;
if (!*p)
continue;
token = match_token(p, tokens, args);
if ((token != Opt_err) && (token != Opt_privport)) {
r = match_int(&args[0], &option);
if (r < 0) {
p9_debug(P9_DEBUG_ERROR,
"integer field, but no integer?\n");
continue;
}
}
switch (token) {
case Opt_port:
opts->port = option;
break;
case Opt_sq_depth:
opts->sq_depth = option;
break;
case Opt_rq_depth:
opts->rq_depth = option;
break;
case Opt_timeout:
opts->timeout = option;
break;
case Opt_privport:
opts->privport = true;
break;
default:
continue;
}
}
/* RQ must be at least as large as the SQ */
opts->rq_depth = max(opts->rq_depth, opts->sq_depth);
kfree(tmp_options);
return 0;
}
static int
p9_cm_event_handler(struct rdma_cm_id *id, struct rdma_cm_event *event)
{
struct p9_client *c = id->context;
struct p9_trans_rdma *rdma = c->trans;
switch (event->event) {
case RDMA_CM_EVENT_ADDR_RESOLVED:
BUG_ON(rdma->state != P9_RDMA_INIT);
rdma->state = P9_RDMA_ADDR_RESOLVED;
break;
case RDMA_CM_EVENT_ROUTE_RESOLVED:
BUG_ON(rdma->state != P9_RDMA_ADDR_RESOLVED);
rdma->state = P9_RDMA_ROUTE_RESOLVED;
break;
case RDMA_CM_EVENT_ESTABLISHED:
BUG_ON(rdma->state != P9_RDMA_ROUTE_RESOLVED);
rdma->state = P9_RDMA_CONNECTED;
break;
case RDMA_CM_EVENT_DISCONNECTED:
if (rdma)
rdma->state = P9_RDMA_CLOSED;
c->status = Disconnected;
break;
case RDMA_CM_EVENT_TIMEWAIT_EXIT:
break;
case RDMA_CM_EVENT_ADDR_CHANGE:
case RDMA_CM_EVENT_ROUTE_ERROR:
case RDMA_CM_EVENT_DEVICE_REMOVAL:
case RDMA_CM_EVENT_MULTICAST_JOIN:
case RDMA_CM_EVENT_MULTICAST_ERROR:
case RDMA_CM_EVENT_REJECTED:
case RDMA_CM_EVENT_CONNECT_REQUEST:
case RDMA_CM_EVENT_CONNECT_RESPONSE:
case RDMA_CM_EVENT_CONNECT_ERROR:
case RDMA_CM_EVENT_ADDR_ERROR:
case RDMA_CM_EVENT_UNREACHABLE:
c->status = Disconnected;
rdma_disconnect(rdma->cm_id);
break;
default:
BUG();
}
complete(&rdma->cm_done);
return 0;
}
static void
recv_done(struct ib_cq *cq, struct ib_wc *wc)
{
struct p9_client *client = cq->cq_context;
struct p9_trans_rdma *rdma = client->trans;
struct p9_rdma_context *c =
container_of(wc->wr_cqe, struct p9_rdma_context, cqe);
struct p9_req_t *req;
int err = 0;
int16_t tag;
req = NULL;
ib_dma_unmap_single(rdma->cm_id->device, c->busa, client->msize,
DMA_FROM_DEVICE);
if (wc->status != IB_WC_SUCCESS)
goto err_out;
c->rc.size = wc->byte_len;
err = p9_parse_header(&c->rc, NULL, NULL, &tag, 1);
if (err)
goto err_out;
req = p9_tag_lookup(client, tag);
if (!req)
goto err_out;
/* Check that we have not yet received a reply for this request.
*/
if (unlikely(req->rc.sdata)) {
pr_err("Duplicate reply for request %d", tag);
goto err_out;
}
req->rc.size = c->rc.size;
req->rc.sdata = c->rc.sdata;
p9_client_cb(client, req, REQ_STATUS_RCVD);
out:
up(&rdma->rq_sem);
kfree(c);
return;
err_out:
p9_debug(P9_DEBUG_ERROR, "req %p err %d status %d\n",
req, err, wc->status);
rdma->state = P9_RDMA_FLUSHING;
client->status = Disconnected;
goto out;
}
static void
send_done(struct ib_cq *cq, struct ib_wc *wc)
{
struct p9_client *client = cq->cq_context;
struct p9_trans_rdma *rdma = client->trans;
struct p9_rdma_context *c =
container_of(wc->wr_cqe, struct p9_rdma_context, cqe);
ib_dma_unmap_single(rdma->cm_id->device,
c->busa, c->req->tc.size,
DMA_TO_DEVICE);
up(&rdma->sq_sem);
p9_req_put(c->req);
kfree(c);
}
static void qp_event_handler(struct ib_event *event, void *context)
{
p9_debug(P9_DEBUG_ERROR, "QP event %d context %p\n",
event->event, context);
}
static void rdma_destroy_trans(struct p9_trans_rdma *rdma)
{
if (!rdma)
return;
if (rdma->qp && !IS_ERR(rdma->qp))
ib_destroy_qp(rdma->qp);
if (rdma->pd && !IS_ERR(rdma->pd))
ib_dealloc_pd(rdma->pd);
if (rdma->cq && !IS_ERR(rdma->cq))
ib_free_cq(rdma->cq);
if (rdma->cm_id && !IS_ERR(rdma->cm_id))
rdma_destroy_id(rdma->cm_id);
kfree(rdma);
}
static int
post_recv(struct p9_client *client, struct p9_rdma_context *c)
{
struct p9_trans_rdma *rdma = client->trans;
struct ib_recv_wr wr;
struct ib_sge sge;
c->busa = ib_dma_map_single(rdma->cm_id->device,
c->rc.sdata, client->msize,
DMA_FROM_DEVICE);
if (ib_dma_mapping_error(rdma->cm_id->device, c->busa))
goto error;
c->cqe.done = recv_done;
sge.addr = c->busa;
sge.length = client->msize;
sge.lkey = rdma->pd->local_dma_lkey;
wr.next = NULL;
wr.wr_cqe = &c->cqe;
wr.sg_list = &sge;
wr.num_sge = 1;
return ib_post_recv(rdma->qp, &wr, NULL);
error:
p9_debug(P9_DEBUG_ERROR, "EIO\n");
return -EIO;
}
static int rdma_request(struct p9_client *client, struct p9_req_t *req)
{
struct p9_trans_rdma *rdma = client->trans;
struct ib_send_wr wr;
struct ib_sge sge;
int err = 0;
unsigned long flags;
struct p9_rdma_context *c = NULL;
struct p9_rdma_context *rpl_context = NULL;
/* When an error occurs between posting the recv and the send,
* there will be a receive context posted without a pending request.
* Since there is no way to "un-post" it, we remember it and skip
* post_recv() for the next request.
* So here,
* see if we are this `next request' and need to absorb an excess rc.
* If yes, then drop and free our own, and do not recv_post().
**/
if (unlikely(atomic_read(&rdma->excess_rc) > 0)) {
if ((atomic_sub_return(1, &rdma->excess_rc) >= 0)) {
/* Got one! */
p9_fcall_fini(&req->rc);
req->rc.sdata = NULL;
goto dont_need_post_recv;
} else {
/* We raced and lost. */
atomic_inc(&rdma->excess_rc);
}
}
/* Allocate an fcall for the reply */
rpl_context = kmalloc(sizeof *rpl_context, GFP_NOFS);
if (!rpl_context) {
err = -ENOMEM;
goto recv_error;
}
rpl_context->rc.sdata = req->rc.sdata;
/*
* Post a receive buffer for this request. We need to ensure
* there is a reply buffer available for every outstanding
* request. A flushed request can result in no reply for an
* outstanding request, so we must keep a count to avoid
* overflowing the RQ.
*/
if (down_interruptible(&rdma->rq_sem)) {
err = -EINTR;
goto recv_error;
}
err = post_recv(client, rpl_context);
if (err) {
p9_debug(P9_DEBUG_ERROR, "POST RECV failed: %d\n", err);
goto recv_error;
}
/* remove posted receive buffer from request structure */
req->rc.sdata = NULL;
dont_need_post_recv:
/* Post the request */
c = kmalloc(sizeof *c, GFP_NOFS);
if (!c) {
err = -ENOMEM;
goto send_error;
}
c->req = req;
c->busa = ib_dma_map_single(rdma->cm_id->device,
c->req->tc.sdata, c->req->tc.size,
DMA_TO_DEVICE);
if (ib_dma_mapping_error(rdma->cm_id->device, c->busa)) {
err = -EIO;
goto send_error;
}
c->cqe.done = send_done;
sge.addr = c->busa;
sge.length = c->req->tc.size;
sge.lkey = rdma->pd->local_dma_lkey;
wr.next = NULL;
wr.wr_cqe = &c->cqe;
wr.opcode = IB_WR_SEND;
wr.send_flags = IB_SEND_SIGNALED;
wr.sg_list = &sge;
wr.num_sge = 1;
if (down_interruptible(&rdma->sq_sem)) {
err = -EINTR;
goto send_error;
}
/* Mark request as `sent' *before* we actually send it,
* because doing if after could erase the REQ_STATUS_RCVD
* status in case of a very fast reply.
*/
req->status = REQ_STATUS_SENT;
err = ib_post_send(rdma->qp, &wr, NULL);
if (err)
goto send_error;
/* Success */
return 0;
/* Handle errors that happened during or while preparing the send: */
send_error:
req->status = REQ_STATUS_ERROR;
kfree(c);
p9_debug(P9_DEBUG_ERROR, "Error %d in rdma_request()\n", err);
/* Ach.
* We did recv_post(), but not send. We have one recv_post in excess.
*/
atomic_inc(&rdma->excess_rc);
return err;
/* Handle errors that happened during or while preparing post_recv(): */
recv_error:
kfree(rpl_context);
spin_lock_irqsave(&rdma->req_lock, flags);
if (err != -EINTR && rdma->state < P9_RDMA_CLOSING) {
rdma->state = P9_RDMA_CLOSING;
spin_unlock_irqrestore(&rdma->req_lock, flags);
rdma_disconnect(rdma->cm_id);
} else
spin_unlock_irqrestore(&rdma->req_lock, flags);
return err;
}
static void rdma_close(struct p9_client *client)
{
struct p9_trans_rdma *rdma;
if (!client)
return;
rdma = client->trans;
if (!rdma)
return;
client->status = Disconnected;
rdma_disconnect(rdma->cm_id);
rdma_destroy_trans(rdma);
}
/**
* alloc_rdma - Allocate and initialize the rdma transport structure
* @opts: Mount options structure
*/
static struct p9_trans_rdma *alloc_rdma(struct p9_rdma_opts *opts)
{
struct p9_trans_rdma *rdma;
rdma = kzalloc(sizeof(struct p9_trans_rdma), GFP_KERNEL);
if (!rdma)
return NULL;
rdma->port = opts->port;
rdma->privport = opts->privport;
rdma->sq_depth = opts->sq_depth;
rdma->rq_depth = opts->rq_depth;
rdma->timeout = opts->timeout;
spin_lock_init(&rdma->req_lock);
init_completion(&rdma->cm_done);
sema_init(&rdma->sq_sem, rdma->sq_depth);
sema_init(&rdma->rq_sem, rdma->rq_depth);
atomic_set(&rdma->excess_rc, 0);
return rdma;
}
static int rdma_cancel(struct p9_client *client, struct p9_req_t *req)
{
/* Nothing to do here.
* We will take care of it (if we have to) in rdma_cancelled()
*/
return 1;
}
/* A request has been fully flushed without a reply.
* That means we have posted one buffer in excess.
*/
static int rdma_cancelled(struct p9_client *client, struct p9_req_t *req)
{
struct p9_trans_rdma *rdma = client->trans;
atomic_inc(&rdma->excess_rc);
return 0;
}
static int p9_rdma_bind_privport(struct p9_trans_rdma *rdma)
{
struct sockaddr_in cl = {
.sin_family = AF_INET,
.sin_addr.s_addr = htonl(INADDR_ANY),
};
int port, err = -EINVAL;
for (port = P9_DEF_MAX_RESVPORT; port >= P9_DEF_MIN_RESVPORT; port--) {
cl.sin_port = htons((ushort)port);
err = rdma_bind_addr(rdma->cm_id, (struct sockaddr *)&cl);
if (err != -EADDRINUSE)
break;
}
return err;
}
/**
* rdma_create_trans - Transport method for creating a transport instance
* @client: client instance
* @addr: IP address string
* @args: Mount options string
*/
static int
rdma_create_trans(struct p9_client *client, const char *addr, char *args)
{
int err;
struct p9_rdma_opts opts;
struct p9_trans_rdma *rdma;
struct rdma_conn_param conn_param;
struct ib_qp_init_attr qp_attr;
if (addr == NULL)
return -EINVAL;
/* Parse the transport specific mount options */
err = parse_opts(args, &opts);
if (err < 0)
return err;
/* Create and initialize the RDMA transport structure */
rdma = alloc_rdma(&opts);
if (!rdma)
return -ENOMEM;
/* Create the RDMA CM ID */
rdma->cm_id = rdma_create_id(&init_net, p9_cm_event_handler, client,
RDMA_PS_TCP, IB_QPT_RC);
if (IS_ERR(rdma->cm_id))
goto error;
/* Associate the client with the transport */
client->trans = rdma;
/* Bind to a privileged port if we need to */
if (opts.privport) {
err = p9_rdma_bind_privport(rdma);
if (err < 0) {
pr_err("%s (%d): problem binding to privport: %d\n",
__func__, task_pid_nr(current), -err);
goto error;
}
}
/* Resolve the server's address */
rdma->addr.sin_family = AF_INET;
rdma->addr.sin_addr.s_addr = in_aton(addr);
rdma->addr.sin_port = htons(opts.port);
err = rdma_resolve_addr(rdma->cm_id, NULL,
(struct sockaddr *)&rdma->addr,
rdma->timeout);
if (err)
goto error;
err = wait_for_completion_interruptible(&rdma->cm_done);
if (err || (rdma->state != P9_RDMA_ADDR_RESOLVED))
goto error;
/* Resolve the route to the server */
err = rdma_resolve_route(rdma->cm_id, rdma->timeout);
if (err)
goto error;
err = wait_for_completion_interruptible(&rdma->cm_done);
if (err || (rdma->state != P9_RDMA_ROUTE_RESOLVED))
goto error;
/* Create the Completion Queue */
rdma->cq = ib_alloc_cq(rdma->cm_id->device, client,
opts.sq_depth + opts.rq_depth + 1,
0, IB_POLL_SOFTIRQ);
if (IS_ERR(rdma->cq))
goto error;
/* Create the Protection Domain */
rdma->pd = ib_alloc_pd(rdma->cm_id->device, 0);
if (IS_ERR(rdma->pd))
goto error;
/* Create the Queue Pair */
memset(&qp_attr, 0, sizeof qp_attr);
qp_attr.event_handler = qp_event_handler;
qp_attr.qp_context = client;
qp_attr.cap.max_send_wr = opts.sq_depth;
qp_attr.cap.max_recv_wr = opts.rq_depth;
qp_attr.cap.max_send_sge = P9_RDMA_SEND_SGE;
qp_attr.cap.max_recv_sge = P9_RDMA_RECV_SGE;
qp_attr.sq_sig_type = IB_SIGNAL_REQ_WR;
qp_attr.qp_type = IB_QPT_RC;
qp_attr.send_cq = rdma->cq;
qp_attr.recv_cq = rdma->cq;
err = rdma_create_qp(rdma->cm_id, rdma->pd, &qp_attr);
if (err)
goto error;
rdma->qp = rdma->cm_id->qp;
/* Request a connection */
memset(&conn_param, 0, sizeof(conn_param));
conn_param.private_data = NULL;
conn_param.private_data_len = 0;
conn_param.responder_resources = P9_RDMA_IRD;
conn_param.initiator_depth = P9_RDMA_ORD;
err = rdma_connect(rdma->cm_id, &conn_param);
if (err)
goto error;
err = wait_for_completion_interruptible(&rdma->cm_done);
if (err || (rdma->state != P9_RDMA_CONNECTED))
goto error;
client->status = Connected;
return 0;
error:
rdma_destroy_trans(rdma);
return -ENOTCONN;
}
static struct p9_trans_module p9_rdma_trans = {
.name = "rdma",
.maxsize = P9_RDMA_MAXSIZE,
.def = 0,
.owner = THIS_MODULE,
.create = rdma_create_trans,
.close = rdma_close,
.request = rdma_request,
.cancel = rdma_cancel,
.cancelled = rdma_cancelled,
.show_options = p9_rdma_show_options,
};
/**
* p9_trans_rdma_init - Register the 9P RDMA transport driver
*/
static int __init p9_trans_rdma_init(void)
{
v9fs_register_trans(&p9_rdma_trans);
return 0;
}
static void __exit p9_trans_rdma_exit(void)
{
v9fs_unregister_trans(&p9_rdma_trans);
}
module_init(p9_trans_rdma_init);
module_exit(p9_trans_rdma_exit);
MODULE_AUTHOR("Tom Tucker <tom@opengridcomputing.com>");
MODULE_DESCRIPTION("RDMA Transport for 9P");
MODULE_LICENSE("Dual BSD/GPL");