Adding upstream version 5.10.209.upstream/5.10.209upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1182 insertions, 0 deletions

diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
new file mode 100644
index 000000000..63f4d2067
--- /dev/null
+++ b/net/9p/trans_fd.c
@@ -0,0 +1,1182 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/fs/9p/trans_fd.c
+ *
+ * Fd transport layer.  Includes deprecated socket layer.
+ *
+ *  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/slab.h>
+#include <linux/seq_file.h>
+#include <net/9p/9p.h>
+#include <net/9p/client.h>
+#include <net/9p/transport.h>
+
+#include <linux/syscalls.h> /* killme */
+
+#define P9_PORT 564
+#define MAX_SOCK_BUF (64*1024)
+#define MAXPOLLWADDR	2
+
+static struct p9_trans_module p9_tcp_trans;
+static struct p9_trans_module p9_fd_trans;
+
+/**
+ * struct p9_fd_opts - per-transport options
+ * @rfd: file descriptor for reading (trans=fd)
+ * @wfd: file descriptor for writing (trans=fd)
+ * @port: port to connect to (trans=tcp)
+ *
+ */
+
+struct p9_fd_opts {
+	int rfd;
+	int wfd;
+	u16 port;
+	bool privport;
+};
+
+/*
+  * Option Parsing (code inspired by NFS code)
+  *  - a little lazy - parse all fd-transport options
+  */
+
+enum {
+	/* Options that take integer arguments */
+	Opt_port, Opt_rfdno, Opt_wfdno, Opt_err,
+	/* Options that take no arguments */
+	Opt_privport,
+};
+
+static const match_table_t tokens = {
+	{Opt_port, "port=%u"},
+	{Opt_rfdno, "rfdno=%u"},
+	{Opt_wfdno, "wfdno=%u"},
+	{Opt_privport, "privport"},
+	{Opt_err, NULL},
+};
+
+enum {
+	Rworksched = 1,		/* read work scheduled or running */
+	Rpending = 2,		/* can read */
+	Wworksched = 4,		/* write work scheduled or running */
+	Wpending = 8,		/* can write */
+};
+
+struct p9_poll_wait {
+	struct p9_conn *conn;
+	wait_queue_entry_t wait;
+	wait_queue_head_t *wait_addr;
+};
+
+/**
+ * struct p9_conn - fd mux connection state information
+ * @mux_list: list link for mux to manage multiple connections (?)
+ * @client: reference to client instance for this connection
+ * @err: error state
+ * @req_list: accounting for requests which have been sent
+ * @unsent_req_list: accounting for requests that haven't been sent
+ * @req: current request being processed (if any)
+ * @tmp_buf: temporary buffer to read in header
+ * @rc: temporary fcall for reading current frame
+ * @wpos: write position for current frame
+ * @wsize: amount of data to write for current frame
+ * @wbuf: current write buffer
+ * @poll_pending_link: pending links to be polled per conn
+ * @poll_wait: array of wait_q's for various worker threads
+ * @pt: poll state
+ * @rq: current read work
+ * @wq: current write work
+ * @wsched: ????
+ *
+ */
+
+struct p9_conn {
+	struct list_head mux_list;
+	struct p9_client *client;
+	int err;
+	struct list_head req_list;
+	struct list_head unsent_req_list;
+	struct p9_req_t *rreq;
+	struct p9_req_t *wreq;
+	char tmp_buf[P9_HDRSZ];
+	struct p9_fcall rc;
+	int wpos;
+	int wsize;
+	char *wbuf;
+	struct list_head poll_pending_link;
+	struct p9_poll_wait poll_wait[MAXPOLLWADDR];
+	poll_table pt;
+	struct work_struct rq;
+	struct work_struct wq;
+	unsigned long wsched;
+};
+
+/**
+ * struct p9_trans_fd - transport state
+ * @rd: reference to file to read from
+ * @wr: reference of file to write to
+ * @conn: connection state reference
+ *
+ */
+
+struct p9_trans_fd {
+	struct file *rd;
+	struct file *wr;
+	struct p9_conn conn;
+};
+
+static void p9_poll_workfn(struct work_struct *work);
+
+static DEFINE_SPINLOCK(p9_poll_lock);
+static LIST_HEAD(p9_poll_pending_list);
+static DECLARE_WORK(p9_poll_work, p9_poll_workfn);
+
+static unsigned int p9_ipport_resv_min = P9_DEF_MIN_RESVPORT;
+static unsigned int p9_ipport_resv_max = P9_DEF_MAX_RESVPORT;
+
+static void p9_mux_poll_stop(struct p9_conn *m)
+{
+	unsigned long flags;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(m->poll_wait); i++) {
+		struct p9_poll_wait *pwait = &m->poll_wait[i];
+
+		if (pwait->wait_addr) {
+			remove_wait_queue(pwait->wait_addr, &pwait->wait);
+			pwait->wait_addr = NULL;
+		}
+	}
+
+	spin_lock_irqsave(&p9_poll_lock, flags);
+	list_del_init(&m->poll_pending_link);
+	spin_unlock_irqrestore(&p9_poll_lock, flags);
+
+	flush_work(&p9_poll_work);
+}
+
+/**
+ * p9_conn_cancel - cancel all pending requests with error
+ * @m: mux data
+ * @err: error code
+ *
+ */
+
+static void p9_conn_cancel(struct p9_conn *m, int err)
+{
+	struct p9_req_t *req, *rtmp;
+	LIST_HEAD(cancel_list);
+
+	p9_debug(P9_DEBUG_ERROR, "mux %p err %d\n", m, err);
+
+	spin_lock(&m->client->lock);
+
+	if (m->err) {
+		spin_unlock(&m->client->lock);
+		return;
+	}
+
+	m->err = err;
+
+	list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
+		list_move(&req->req_list, &cancel_list);
+		req->status = REQ_STATUS_ERROR;
+	}
+	list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
+		list_move(&req->req_list, &cancel_list);
+		req->status = REQ_STATUS_ERROR;
+	}
+
+	spin_unlock(&m->client->lock);
+
+	list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
+		p9_debug(P9_DEBUG_ERROR, "call back req %p\n", req);
+		list_del(&req->req_list);
+		if (!req->t_err)
+			req->t_err = err;
+		p9_client_cb(m->client, req, REQ_STATUS_ERROR);
+	}
+}
+
+static __poll_t
+p9_fd_poll(struct p9_client *client, struct poll_table_struct *pt, int *err)
+{
+	__poll_t ret;
+	struct p9_trans_fd *ts = NULL;
+
+	if (client && client->status == Connected)
+		ts = client->trans;
+
+	if (!ts) {
+		if (err)
+			*err = -EREMOTEIO;
+		return EPOLLERR;
+	}
+
+	ret = vfs_poll(ts->rd, pt);
+	if (ts->rd != ts->wr)
+		ret = (ret & ~EPOLLOUT) | (vfs_poll(ts->wr, pt) & ~EPOLLIN);
+	return ret;
+}
+
+/**
+ * p9_fd_read- read from a fd
+ * @client: client instance
+ * @v: buffer to receive data into
+ * @len: size of receive buffer
+ *
+ */
+
+static int p9_fd_read(struct p9_client *client, void *v, int len)
+{
+	int ret;
+	struct p9_trans_fd *ts = NULL;
+	loff_t pos;
+
+	if (client && client->status != Disconnected)
+		ts = client->trans;
+
+	if (!ts)
+		return -EREMOTEIO;
+
+	if (!(ts->rd->f_flags & O_NONBLOCK))
+		p9_debug(P9_DEBUG_ERROR, "blocking read ...\n");
+
+	pos = ts->rd->f_pos;
+	ret = kernel_read(ts->rd, v, len, &pos);
+	if (ret <= 0 && ret != -ERESTARTSYS && ret != -EAGAIN)
+		client->status = Disconnected;
+	return ret;
+}
+
+/**
+ * p9_read_work - called when there is some data to be read from a transport
+ * @work: container of work to be done
+ *
+ */
+
+static void p9_read_work(struct work_struct *work)
+{
+	__poll_t n;
+	int err;
+	struct p9_conn *m;
+
+	m = container_of(work, struct p9_conn, rq);
+
+	if (m->err < 0)
+		return;
+
+	p9_debug(P9_DEBUG_TRANS, "start mux %p pos %zd\n", m, m->rc.offset);
+
+	if (!m->rc.sdata) {
+		m->rc.sdata = m->tmp_buf;
+		m->rc.offset = 0;
+		m->rc.capacity = P9_HDRSZ; /* start by reading header */
+	}
+
+	clear_bit(Rpending, &m->wsched);
+	p9_debug(P9_DEBUG_TRANS, "read mux %p pos %zd size: %zd = %zd\n",
+		 m, m->rc.offset, m->rc.capacity,
+		 m->rc.capacity - m->rc.offset);
+	err = p9_fd_read(m->client, m->rc.sdata + m->rc.offset,
+			 m->rc.capacity - m->rc.offset);
+	p9_debug(P9_DEBUG_TRANS, "mux %p got %d bytes\n", m, err);
+	if (err == -EAGAIN)
+		goto end_clear;
+
+	if (err <= 0)
+		goto error;
+
+	m->rc.offset += err;
+
+	/* header read in */
+	if ((!m->rreq) && (m->rc.offset == m->rc.capacity)) {
+		p9_debug(P9_DEBUG_TRANS, "got new header\n");
+
+		/* Header size */
+		m->rc.size = P9_HDRSZ;
+		err = p9_parse_header(&m->rc, &m->rc.size, NULL, NULL, 0);
+		if (err) {
+			p9_debug(P9_DEBUG_ERROR,
+				 "error parsing header: %d\n", err);
+			goto error;
+		}
+
+		if (m->rc.size >= m->client->msize) {
+			p9_debug(P9_DEBUG_ERROR,
+				 "requested packet size too big: %d\n",
+				 m->rc.size);
+			err = -EIO;
+			goto error;
+		}
+
+		p9_debug(P9_DEBUG_TRANS,
+			 "mux %p pkt: size: %d bytes tag: %d\n",
+			 m, m->rc.size, m->rc.tag);
+
+		m->rreq = p9_tag_lookup(m->client, m->rc.tag);
+		if (!m->rreq || (m->rreq->status != REQ_STATUS_SENT)) {
+			p9_debug(P9_DEBUG_ERROR, "Unexpected packet tag %d\n",
+				 m->rc.tag);
+			err = -EIO;
+			goto error;
+		}
+
+		if (!m->rreq->rc.sdata) {
+			p9_debug(P9_DEBUG_ERROR,
+				 "No recv fcall for tag %d (req %p), disconnecting!\n",
+				 m->rc.tag, m->rreq);
+			m->rreq = NULL;
+			err = -EIO;
+			goto error;
+		}
+		m->rc.sdata = m->rreq->rc.sdata;
+		memcpy(m->rc.sdata, m->tmp_buf, m->rc.capacity);
+		m->rc.capacity = m->rc.size;
+	}
+
+	/* packet is read in
+	 * not an else because some packets (like clunk) have no payload
+	 */
+	if ((m->rreq) && (m->rc.offset == m->rc.capacity)) {
+		p9_debug(P9_DEBUG_TRANS, "got new packet\n");
+		m->rreq->rc.size = m->rc.offset;
+		spin_lock(&m->client->lock);
+		if (m->rreq->status == REQ_STATUS_SENT) {
+			list_del(&m->rreq->req_list);
+			p9_client_cb(m->client, m->rreq, REQ_STATUS_RCVD);
+		} else if (m->rreq->status == REQ_STATUS_FLSHD) {
+			/* Ignore replies associated with a cancelled request. */
+			p9_debug(P9_DEBUG_TRANS,
+				 "Ignore replies associated with a cancelled request\n");
+		} else {
+			spin_unlock(&m->client->lock);
+			p9_debug(P9_DEBUG_ERROR,
+				 "Request tag %d errored out while we were reading the reply\n",
+				 m->rc.tag);
+			err = -EIO;
+			goto error;
+		}
+		spin_unlock(&m->client->lock);
+		m->rc.sdata = NULL;
+		m->rc.offset = 0;
+		m->rc.capacity = 0;
+		p9_req_put(m->rreq);
+		m->rreq = NULL;
+	}
+
+end_clear:
+	clear_bit(Rworksched, &m->wsched);
+
+	if (!list_empty(&m->req_list)) {
+		if (test_and_clear_bit(Rpending, &m->wsched))
+			n = EPOLLIN;
+		else
+			n = p9_fd_poll(m->client, NULL, NULL);
+
+		if ((n & EPOLLIN) && !test_and_set_bit(Rworksched, &m->wsched)) {
+			p9_debug(P9_DEBUG_TRANS, "sched read work %p\n", m);
+			schedule_work(&m->rq);
+		}
+	}
+
+	return;
+error:
+	p9_conn_cancel(m, err);
+	clear_bit(Rworksched, &m->wsched);
+}
+
+/**
+ * p9_fd_write - write to a socket
+ * @client: client instance
+ * @v: buffer to send data from
+ * @len: size of send buffer
+ *
+ */
+
+static int p9_fd_write(struct p9_client *client, void *v, int len)
+{
+	ssize_t ret;
+	struct p9_trans_fd *ts = NULL;
+
+	if (client && client->status != Disconnected)
+		ts = client->trans;
+
+	if (!ts)
+		return -EREMOTEIO;
+
+	if (!(ts->wr->f_flags & O_NONBLOCK))
+		p9_debug(P9_DEBUG_ERROR, "blocking write ...\n");
+
+	ret = kernel_write(ts->wr, v, len, &ts->wr->f_pos);
+	if (ret <= 0 && ret != -ERESTARTSYS && ret != -EAGAIN)
+		client->status = Disconnected;
+	return ret;
+}
+
+/**
+ * p9_write_work - called when a transport can send some data
+ * @work: container for work to be done
+ *
+ */
+
+static void p9_write_work(struct work_struct *work)
+{
+	__poll_t n;
+	int err;
+	struct p9_conn *m;
+	struct p9_req_t *req;
+
+	m = container_of(work, struct p9_conn, wq);
+
+	if (m->err < 0) {
+		clear_bit(Wworksched, &m->wsched);
+		return;
+	}
+
+	if (!m->wsize) {
+		spin_lock(&m->client->lock);
+		if (list_empty(&m->unsent_req_list)) {
+			clear_bit(Wworksched, &m->wsched);
+			spin_unlock(&m->client->lock);
+			return;
+		}
+
+		req = list_entry(m->unsent_req_list.next, struct p9_req_t,
+			       req_list);
+		req->status = REQ_STATUS_SENT;
+		p9_debug(P9_DEBUG_TRANS, "move req %p\n", req);
+		list_move_tail(&req->req_list, &m->req_list);
+
+		m->wbuf = req->tc.sdata;
+		m->wsize = req->tc.size;
+		m->wpos = 0;
+		p9_req_get(req);
+		m->wreq = req;
+		spin_unlock(&m->client->lock);
+	}
+
+	p9_debug(P9_DEBUG_TRANS, "mux %p pos %d size %d\n",
+		 m, m->wpos, m->wsize);
+	clear_bit(Wpending, &m->wsched);
+	err = p9_fd_write(m->client, m->wbuf + m->wpos, m->wsize - m->wpos);
+	p9_debug(P9_DEBUG_TRANS, "mux %p sent %d bytes\n", m, err);
+	if (err == -EAGAIN)
+		goto end_clear;
+
+
+	if (err < 0)
+		goto error;
+	else if (err == 0) {
+		err = -EREMOTEIO;
+		goto error;
+	}
+
+	m->wpos += err;
+	if (m->wpos == m->wsize) {
+		m->wpos = m->wsize = 0;
+		p9_req_put(m->wreq);
+		m->wreq = NULL;
+	}
+
+end_clear:
+	clear_bit(Wworksched, &m->wsched);
+
+	if (m->wsize || !list_empty(&m->unsent_req_list)) {
+		if (test_and_clear_bit(Wpending, &m->wsched))
+			n = EPOLLOUT;
+		else
+			n = p9_fd_poll(m->client, NULL, NULL);
+
+		if ((n & EPOLLOUT) &&
+		   !test_and_set_bit(Wworksched, &m->wsched)) {
+			p9_debug(P9_DEBUG_TRANS, "sched write work %p\n", m);
+			schedule_work(&m->wq);
+		}
+	}
+
+	return;
+
+error:
+	p9_conn_cancel(m, err);
+	clear_bit(Wworksched, &m->wsched);
+}
+
+static int p9_pollwake(wait_queue_entry_t *wait, unsigned int mode, int sync, void *key)
+{
+	struct p9_poll_wait *pwait =
+		container_of(wait, struct p9_poll_wait, wait);
+	struct p9_conn *m = pwait->conn;
+	unsigned long flags;
+
+	spin_lock_irqsave(&p9_poll_lock, flags);
+	if (list_empty(&m->poll_pending_link))
+		list_add_tail(&m->poll_pending_link, &p9_poll_pending_list);
+	spin_unlock_irqrestore(&p9_poll_lock, flags);
+
+	schedule_work(&p9_poll_work);
+	return 1;
+}
+
+/**
+ * p9_pollwait - add poll task to the wait queue
+ * @filp: file pointer being polled
+ * @wait_address: wait_q to block on
+ * @p: poll state
+ *
+ * called by files poll operation to add v9fs-poll task to files wait queue
+ */
+
+static void
+p9_pollwait(struct file *filp, wait_queue_head_t *wait_address, poll_table *p)
+{
+	struct p9_conn *m = container_of(p, struct p9_conn, pt);
+	struct p9_poll_wait *pwait = NULL;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(m->poll_wait); i++) {
+		if (m->poll_wait[i].wait_addr == NULL) {
+			pwait = &m->poll_wait[i];
+			break;
+		}
+	}
+
+	if (!pwait) {
+		p9_debug(P9_DEBUG_ERROR, "not enough wait_address slots\n");
+		return;
+	}
+
+	pwait->conn = m;
+	pwait->wait_addr = wait_address;
+	init_waitqueue_func_entry(&pwait->wait, p9_pollwake);
+	add_wait_queue(wait_address, &pwait->wait);
+}
+
+/**
+ * p9_conn_create - initialize the per-session mux data
+ * @client: client instance
+ *
+ * Note: Creates the polling task if this is the first session.
+ */
+
+static void p9_conn_create(struct p9_client *client)
+{
+	__poll_t n;
+	struct p9_trans_fd *ts = client->trans;
+	struct p9_conn *m = &ts->conn;
+
+	p9_debug(P9_DEBUG_TRANS, "client %p msize %d\n", client, client->msize);
+
+	INIT_LIST_HEAD(&m->mux_list);
+	m->client = client;
+
+	INIT_LIST_HEAD(&m->req_list);
+	INIT_LIST_HEAD(&m->unsent_req_list);
+	INIT_WORK(&m->rq, p9_read_work);
+	INIT_WORK(&m->wq, p9_write_work);
+	INIT_LIST_HEAD(&m->poll_pending_link);
+	init_poll_funcptr(&m->pt, p9_pollwait);
+
+	n = p9_fd_poll(client, &m->pt, NULL);
+	if (n & EPOLLIN) {
+		p9_debug(P9_DEBUG_TRANS, "mux %p can read\n", m);
+		set_bit(Rpending, &m->wsched);
+	}
+
+	if (n & EPOLLOUT) {
+		p9_debug(P9_DEBUG_TRANS, "mux %p can write\n", m);
+		set_bit(Wpending, &m->wsched);
+	}
+}
+
+/**
+ * p9_poll_mux - polls a mux and schedules read or write works if necessary
+ * @m: connection to poll
+ *
+ */
+
+static void p9_poll_mux(struct p9_conn *m)
+{
+	__poll_t n;
+	int err = -ECONNRESET;
+
+	if (m->err < 0)
+		return;
+
+	n = p9_fd_poll(m->client, NULL, &err);
+	if (n & (EPOLLERR | EPOLLHUP | EPOLLNVAL)) {
+		p9_debug(P9_DEBUG_TRANS, "error mux %p err %d\n", m, n);
+		p9_conn_cancel(m, err);
+	}
+
+	if (n & EPOLLIN) {
+		set_bit(Rpending, &m->wsched);
+		p9_debug(P9_DEBUG_TRANS, "mux %p can read\n", m);
+		if (!test_and_set_bit(Rworksched, &m->wsched)) {
+			p9_debug(P9_DEBUG_TRANS, "sched read work %p\n", m);
+			schedule_work(&m->rq);
+		}
+	}
+
+	if (n & EPOLLOUT) {
+		set_bit(Wpending, &m->wsched);
+		p9_debug(P9_DEBUG_TRANS, "mux %p can write\n", m);
+		if ((m->wsize || !list_empty(&m->unsent_req_list)) &&
+		    !test_and_set_bit(Wworksched, &m->wsched)) {
+			p9_debug(P9_DEBUG_TRANS, "sched write work %p\n", m);
+			schedule_work(&m->wq);
+		}
+	}
+}
+
+/**
+ * p9_fd_request - send 9P request
+ * The function can sleep until the request is scheduled for sending.
+ * The function can be interrupted. Return from the function is not
+ * a guarantee that the request is sent successfully.
+ *
+ * @client: client instance
+ * @req: request to be sent
+ *
+ */
+
+static int p9_fd_request(struct p9_client *client, struct p9_req_t *req)
+{
+	__poll_t n;
+	struct p9_trans_fd *ts = client->trans;
+	struct p9_conn *m = &ts->conn;
+
+	p9_debug(P9_DEBUG_TRANS, "mux %p task %p tcall %p id %d\n",
+		 m, current, &req->tc, req->tc.id);
+	if (m->err < 0)
+		return m->err;
+
+	spin_lock(&client->lock);
+	req->status = REQ_STATUS_UNSENT;
+	list_add_tail(&req->req_list, &m->unsent_req_list);
+	spin_unlock(&client->lock);
+
+	if (test_and_clear_bit(Wpending, &m->wsched))
+		n = EPOLLOUT;
+	else
+		n = p9_fd_poll(m->client, NULL, NULL);
+
+	if (n & EPOLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
+		schedule_work(&m->wq);
+
+	return 0;
+}
+
+static int p9_fd_cancel(struct p9_client *client, struct p9_req_t *req)
+{
+	int ret = 1;
+
+	p9_debug(P9_DEBUG_TRANS, "client %p req %p\n", client, req);
+
+	spin_lock(&client->lock);
+
+	if (req->status == REQ_STATUS_UNSENT) {
+		list_del(&req->req_list);
+		req->status = REQ_STATUS_FLSHD;
+		p9_req_put(req);
+		ret = 0;
+	}
+	spin_unlock(&client->lock);
+
+	return ret;
+}
+
+static int p9_fd_cancelled(struct p9_client *client, struct p9_req_t *req)
+{
+	p9_debug(P9_DEBUG_TRANS, "client %p req %p\n", client, req);
+
+	spin_lock(&client->lock);
+	/* Ignore cancelled request if message has been received
+	 * before lock.
+	 */
+	if (req->status == REQ_STATUS_RCVD) {
+		spin_unlock(&client->lock);
+		return 0;
+	}
+
+	/* we haven't received a response for oldreq,
+	 * remove it from the list.
+	 */
+	list_del(&req->req_list);
+	req->status = REQ_STATUS_FLSHD;
+	spin_unlock(&client->lock);
+	p9_req_put(req);
+
+	return 0;
+}
+
+static int p9_fd_show_options(struct seq_file *m, struct p9_client *clnt)
+{
+	if (clnt->trans_mod == &p9_tcp_trans) {
+		if (clnt->trans_opts.tcp.port != P9_PORT)
+			seq_printf(m, ",port=%u", clnt->trans_opts.tcp.port);
+	} else if (clnt->trans_mod == &p9_fd_trans) {
+		if (clnt->trans_opts.fd.rfd != ~0)
+			seq_printf(m, ",rfd=%u", clnt->trans_opts.fd.rfd);
+		if (clnt->trans_opts.fd.wfd != ~0)
+			seq_printf(m, ",wfd=%u", clnt->trans_opts.fd.wfd);
+	}
+	return 0;
+}
+
+/**
+ * parse_opts - parse mount options into p9_fd_opts structure
+ * @params: options string passed from mount
+ * @opts: fd transport-specific structure to parse options into
+ *
+ * Returns 0 upon success, -ERRNO upon failure
+ */
+
+static int parse_opts(char *params, struct p9_fd_opts *opts)
+{
+	char *p;
+	substring_t args[MAX_OPT_ARGS];
+	int option;
+	char *options, *tmp_options;
+
+	opts->port = P9_PORT;
+	opts->rfd = ~0;
+	opts->wfd = ~0;
+	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_rfdno:
+			opts->rfd = option;
+			break;
+		case Opt_wfdno:
+			opts->wfd = option;
+			break;
+		case Opt_privport:
+			opts->privport = true;
+			break;
+		default:
+			continue;
+		}
+	}
+
+	kfree(tmp_options);
+	return 0;
+}
+
+static int p9_fd_open(struct p9_client *client, int rfd, int wfd)
+{
+	struct p9_trans_fd *ts = kzalloc(sizeof(struct p9_trans_fd),
+					   GFP_KERNEL);
+	if (!ts)
+		return -ENOMEM;
+
+	ts->rd = fget(rfd);
+	if (!ts->rd)
+		goto out_free_ts;
+	if (!(ts->rd->f_mode & FMODE_READ))
+		goto out_put_rd;
+	/* Prevent workers from hanging on IO when fd is a pipe.
+	 * It's technically possible for userspace or concurrent mounts to
+	 * modify this flag concurrently, which will likely result in a
+	 * broken filesystem. However, just having bad flags here should
+	 * not crash the kernel or cause any other sort of bug, so mark this
+	 * particular data race as intentional so that tooling (like KCSAN)
+	 * can allow it and detect further problems.
+	 */
+	data_race(ts->rd->f_flags |= O_NONBLOCK);
+	ts->wr = fget(wfd);
+	if (!ts->wr)
+		goto out_put_rd;
+	if (!(ts->wr->f_mode & FMODE_WRITE))
+		goto out_put_wr;
+	data_race(ts->wr->f_flags |= O_NONBLOCK);
+
+	client->trans = ts;
+	client->status = Connected;
+
+	return 0;
+
+out_put_wr:
+	fput(ts->wr);
+out_put_rd:
+	fput(ts->rd);
+out_free_ts:
+	kfree(ts);
+	return -EIO;
+}
+
+static int p9_socket_open(struct p9_client *client, struct socket *csocket)
+{
+	struct p9_trans_fd *p;
+	struct file *file;
+
+	p = kzalloc(sizeof(struct p9_trans_fd), GFP_KERNEL);
+	if (!p) {
+		sock_release(csocket);
+		return -ENOMEM;
+	}
+
+	csocket->sk->sk_allocation = GFP_NOIO;
+	file = sock_alloc_file(csocket, 0, NULL);
+	if (IS_ERR(file)) {
+		pr_err("%s (%d): failed to map fd\n",
+		       __func__, task_pid_nr(current));
+		kfree(p);
+		return PTR_ERR(file);
+	}
+
+	get_file(file);
+	p->wr = p->rd = file;
+	client->trans = p;
+	client->status = Connected;
+
+	p->rd->f_flags |= O_NONBLOCK;
+
+	p9_conn_create(client);
+	return 0;
+}
+
+/**
+ * p9_mux_destroy - cancels all pending requests of mux
+ * @m: mux to destroy
+ *
+ */
+
+static void p9_conn_destroy(struct p9_conn *m)
+{
+	p9_debug(P9_DEBUG_TRANS, "mux %p prev %p next %p\n",
+		 m, m->mux_list.prev, m->mux_list.next);
+
+	p9_mux_poll_stop(m);
+	cancel_work_sync(&m->rq);
+	if (m->rreq) {
+		p9_req_put(m->rreq);
+		m->rreq = NULL;
+	}
+	cancel_work_sync(&m->wq);
+	if (m->wreq) {
+		p9_req_put(m->wreq);
+		m->wreq = NULL;
+	}
+
+	p9_conn_cancel(m, -ECONNRESET);
+
+	m->client = NULL;
+}
+
+/**
+ * p9_fd_close - shutdown file descriptor transport
+ * @client: client instance
+ *
+ */
+
+static void p9_fd_close(struct p9_client *client)
+{
+	struct p9_trans_fd *ts;
+
+	if (!client)
+		return;
+
+	ts = client->trans;
+	if (!ts)
+		return;
+
+	client->status = Disconnected;
+
+	p9_conn_destroy(&ts->conn);
+
+	if (ts->rd)
+		fput(ts->rd);
+	if (ts->wr)
+		fput(ts->wr);
+
+	kfree(ts);
+}
+
+/*
+ * stolen from NFS - maybe should be made a generic function?
+ */
+static inline int valid_ipaddr4(const char *buf)
+{
+	int rc, count, in[4];
+
+	rc = sscanf(buf, "%d.%d.%d.%d", &in[0], &in[1], &in[2], &in[3]);
+	if (rc != 4)
+		return -EINVAL;
+	for (count = 0; count < 4; count++) {
+		if (in[count] > 255)
+			return -EINVAL;
+	}
+	return 0;
+}
+
+static int p9_bind_privport(struct socket *sock)
+{
+	struct sockaddr_in cl;
+	int port, err = -EINVAL;
+
+	memset(&cl, 0, sizeof(cl));
+	cl.sin_family = AF_INET;
+	cl.sin_addr.s_addr = htonl(INADDR_ANY);
+	for (port = p9_ipport_resv_max; port >= p9_ipport_resv_min; port--) {
+		cl.sin_port = htons((ushort)port);
+		err = kernel_bind(sock, (struct sockaddr *)&cl, sizeof(cl));
+		if (err != -EADDRINUSE)
+			break;
+	}
+	return err;
+}
+
+
+static int
+p9_fd_create_tcp(struct p9_client *client, const char *addr, char *args)
+{
+	int err;
+	struct socket *csocket;
+	struct sockaddr_in sin_server;
+	struct p9_fd_opts opts;
+
+	err = parse_opts(args, &opts);
+	if (err < 0)
+		return err;
+
+	if (addr == NULL || valid_ipaddr4(addr) < 0)
+		return -EINVAL;
+
+	csocket = NULL;
+
+	client->trans_opts.tcp.port = opts.port;
+	client->trans_opts.tcp.privport = opts.privport;
+	sin_server.sin_family = AF_INET;
+	sin_server.sin_addr.s_addr = in_aton(addr);
+	sin_server.sin_port = htons(opts.port);
+	err = __sock_create(current->nsproxy->net_ns, PF_INET,
+			    SOCK_STREAM, IPPROTO_TCP, &csocket, 1);
+	if (err) {
+		pr_err("%s (%d): problem creating socket\n",
+		       __func__, task_pid_nr(current));
+		return err;
+	}
+
+	if (opts.privport) {
+		err = p9_bind_privport(csocket);
+		if (err < 0) {
+			pr_err("%s (%d): problem binding to privport\n",
+			       __func__, task_pid_nr(current));
+			sock_release(csocket);
+			return err;
+		}
+	}
+
+	err = csocket->ops->connect(csocket,
+				    (struct sockaddr *)&sin_server,
+				    sizeof(struct sockaddr_in), 0);
+	if (err < 0) {
+		pr_err("%s (%d): problem connecting socket to %s\n",
+		       __func__, task_pid_nr(current), addr);
+		sock_release(csocket);
+		return err;
+	}
+
+	return p9_socket_open(client, csocket);
+}
+
+static int
+p9_fd_create_unix(struct p9_client *client, const char *addr, char *args)
+{
+	int err;
+	struct socket *csocket;
+	struct sockaddr_un sun_server;
+
+	csocket = NULL;
+
+	if (!addr || !strlen(addr))
+		return -EINVAL;
+
+	if (strlen(addr) >= UNIX_PATH_MAX) {
+		pr_err("%s (%d): address too long: %s\n",
+		       __func__, task_pid_nr(current), addr);
+		return -ENAMETOOLONG;
+	}
+
+	sun_server.sun_family = PF_UNIX;
+	strcpy(sun_server.sun_path, addr);
+	err = __sock_create(current->nsproxy->net_ns, PF_UNIX,
+			    SOCK_STREAM, 0, &csocket, 1);
+	if (err < 0) {
+		pr_err("%s (%d): problem creating socket\n",
+		       __func__, task_pid_nr(current));
+
+		return err;
+	}
+	err = csocket->ops->connect(csocket, (struct sockaddr *)&sun_server,
+			sizeof(struct sockaddr_un) - 1, 0);
+	if (err < 0) {
+		pr_err("%s (%d): problem connecting socket: %s: %d\n",
+		       __func__, task_pid_nr(current), addr, err);
+		sock_release(csocket);
+		return err;
+	}
+
+	return p9_socket_open(client, csocket);
+}
+
+static int
+p9_fd_create(struct p9_client *client, const char *addr, char *args)
+{
+	int err;
+	struct p9_fd_opts opts;
+
+	parse_opts(args, &opts);
+	client->trans_opts.fd.rfd = opts.rfd;
+	client->trans_opts.fd.wfd = opts.wfd;
+
+	if (opts.rfd == ~0 || opts.wfd == ~0) {
+		pr_err("Insufficient options for proto=fd\n");
+		return -ENOPROTOOPT;
+	}
+
+	err = p9_fd_open(client, opts.rfd, opts.wfd);
+	if (err < 0)
+		return err;
+
+	p9_conn_create(client);
+
+	return 0;
+}
+
+static struct p9_trans_module p9_tcp_trans = {
+	.name = "tcp",
+	.maxsize = MAX_SOCK_BUF,
+	.def = 0,
+	.create = p9_fd_create_tcp,
+	.close = p9_fd_close,
+	.request = p9_fd_request,
+	.cancel = p9_fd_cancel,
+	.cancelled = p9_fd_cancelled,
+	.show_options = p9_fd_show_options,
+	.owner = THIS_MODULE,
+};
+
+static struct p9_trans_module p9_unix_trans = {
+	.name = "unix",
+	.maxsize = MAX_SOCK_BUF,
+	.def = 0,
+	.create = p9_fd_create_unix,
+	.close = p9_fd_close,
+	.request = p9_fd_request,
+	.cancel = p9_fd_cancel,
+	.cancelled = p9_fd_cancelled,
+	.show_options = p9_fd_show_options,
+	.owner = THIS_MODULE,
+};
+
+static struct p9_trans_module p9_fd_trans = {
+	.name = "fd",
+	.maxsize = MAX_SOCK_BUF,
+	.def = 0,
+	.create = p9_fd_create,
+	.close = p9_fd_close,
+	.request = p9_fd_request,
+	.cancel = p9_fd_cancel,
+	.cancelled = p9_fd_cancelled,
+	.show_options = p9_fd_show_options,
+	.owner = THIS_MODULE,
+};
+
+/**
+ * p9_poll_workfn - poll worker thread
+ * @work: work queue
+ *
+ * polls all v9fs transports for new events and queues the appropriate
+ * work to the work queue
+ *
+ */
+
+static void p9_poll_workfn(struct work_struct *work)
+{
+	unsigned long flags;
+
+	p9_debug(P9_DEBUG_TRANS, "start %p\n", current);
+
+	spin_lock_irqsave(&p9_poll_lock, flags);
+	while (!list_empty(&p9_poll_pending_list)) {
+		struct p9_conn *conn = list_first_entry(&p9_poll_pending_list,
+							struct p9_conn,
+							poll_pending_link);
+		list_del_init(&conn->poll_pending_link);
+		spin_unlock_irqrestore(&p9_poll_lock, flags);
+
+		p9_poll_mux(conn);
+
+		spin_lock_irqsave(&p9_poll_lock, flags);
+	}
+	spin_unlock_irqrestore(&p9_poll_lock, flags);
+
+	p9_debug(P9_DEBUG_TRANS, "finish\n");
+}
+
+int p9_trans_fd_init(void)
+{
+	v9fs_register_trans(&p9_tcp_trans);
+	v9fs_register_trans(&p9_unix_trans);
+	v9fs_register_trans(&p9_fd_trans);
+
+	return 0;
+}
+
+void p9_trans_fd_exit(void)
+{
+	flush_work(&p9_poll_work);
+	v9fs_unregister_trans(&p9_tcp_trans);
+	v9fs_unregister_trans(&p9_unix_trans);
+	v9fs_unregister_trans(&p9_fd_trans);
+}