1 files changed, 1050 insertions, 0 deletions

diff --git a/net/9p/mux.c b/net/9p/mux.c
new file mode 100644
index 000000000000..c3aa87bc8b97
--- /dev/null
+++ b/net/9p/mux.c
@@ -0,0 +1,1050 @@
+/*
+ * net/9p/mux.c
+ *
+ * Protocol Multiplexer
+ *
+ *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
+ *  Copyright (C) 2004-2005 by Latchesar Ionkov <lucho@ionkov.net>
+ *
+ *  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
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/poll.h>
+#include <linux/kthread.h>
+#include <linux/idr.h>
+#include <linux/mutex.h>
+#include <net/9p/9p.h>
+#include <net/9p/transport.h>
+#include <net/9p/conn.h>
+
+#define ERREQFLUSH      1
+#define SCHED_TIMEOUT   10
+#define MAXPOLLWADDR    2
+
+enum {
+        Rworksched = 1,         /* read work scheduled or running */
+        Rpending = 2,           /* can read */
+        Wworksched = 4,         /* write work scheduled or running */
+        Wpending = 8,           /* can write */
+};
+
+enum {
+        None,
+        Flushing,
+        Flushed,
+};
+
+struct p9_mux_poll_task;
+
+struct p9_req {
+        spinlock_t lock; /* protect request structure */
+        int tag;
+        struct p9_fcall *tcall;
+        struct p9_fcall *rcall;
+        int err;
+        p9_conn_req_callback cb;
+        void *cba;
+        int flush;
+        struct list_head req_list;
+};
+
+struct p9_conn {
+        spinlock_t lock; /* protect lock structure */
+        struct list_head mux_list;
+        struct p9_mux_poll_task *poll_task;
+        int msize;
+        unsigned char *extended;
+        struct p9_transport *trans;
+        struct p9_idpool *tagpool;
+        int err;
+        wait_queue_head_t equeue;
+        struct list_head req_list;
+        struct list_head unsent_req_list;
+        struct p9_fcall *rcall;
+        int rpos;
+        char *rbuf;
+        int wpos;
+        int wsize;
+        char *wbuf;
+        wait_queue_t poll_wait[MAXPOLLWADDR];
+        wait_queue_head_t *poll_waddr[MAXPOLLWADDR];
+        poll_table pt;
+        struct work_struct rq;
+        struct work_struct wq;
+        unsigned long wsched;
+};
+
+struct p9_mux_poll_task {
+        struct task_struct *task;
+        struct list_head mux_list;
+        int muxnum;
+};
+
+struct p9_mux_rpc {
+        struct p9_conn *m;
+        int err;
+        struct p9_fcall *tcall;
+        struct p9_fcall *rcall;
+        wait_queue_head_t wqueue;
+};
+
+static int p9_poll_proc(void *);
+static void p9_read_work(struct work_struct *work);
+static void p9_write_work(struct work_struct *work);
+static void p9_pollwait(struct file *filp, wait_queue_head_t *wait_address,
+                          poll_table * p);
+static u16 p9_mux_get_tag(struct p9_conn *);
+static void p9_mux_put_tag(struct p9_conn *, u16);
+
+static DEFINE_MUTEX(p9_mux_task_lock);
+static struct workqueue_struct *p9_mux_wq;
+
+static int p9_mux_num;
+static int p9_mux_poll_task_num;
+static struct p9_mux_poll_task p9_mux_poll_tasks[100];
+
+int p9_mux_global_init(void)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(p9_mux_poll_tasks); i++)
+                p9_mux_poll_tasks[i].task = NULL;
+
+        p9_mux_wq = create_workqueue("v9fs");
+        if (!p9_mux_wq) {
+                printk(KERN_WARNING "v9fs: mux: creating workqueue failed\n");
+                return -ENOMEM;
+        }
+
+        return 0;
+}
+
+void p9_mux_global_exit(void)
+{
+        destroy_workqueue(p9_mux_wq);
+}
+
+/**
+ * p9_mux_calc_poll_procs - calculates the number of polling procs
+ * based on the number of mounted v9fs filesystems.
+ *
+ * The current implementation returns sqrt of the number of mounts.
+ */
+static int p9_mux_calc_poll_procs(int muxnum)
+{
+        int n;
+
+        if (p9_mux_poll_task_num)
+                n = muxnum / p9_mux_poll_task_num +
+                    (muxnum % p9_mux_poll_task_num ? 1 : 0);
+        else
+                n = 1;
+
+        if (n > ARRAY_SIZE(p9_mux_poll_tasks))
+                n = ARRAY_SIZE(p9_mux_poll_tasks);
+
+        return n;
+}
+
+static int p9_mux_poll_start(struct p9_conn *m)
+{
+        int i, n;
+        struct p9_mux_poll_task *vpt, *vptlast;
+        struct task_struct *pproc;
+
+        P9_DPRINTK(P9_DEBUG_MUX, "mux %p muxnum %d procnum %d\n", m, p9_mux_num,
+                p9_mux_poll_task_num);
+        mutex_lock(&p9_mux_task_lock);
+
+        n = p9_mux_calc_poll_procs(p9_mux_num + 1);
+        if (n > p9_mux_poll_task_num) {
+                for (i = 0; i < ARRAY_SIZE(p9_mux_poll_tasks); i++) {
+                        if (p9_mux_poll_tasks[i].task == NULL) {
+                                vpt = &p9_mux_poll_tasks[i];
+                                P9_DPRINTK(P9_DEBUG_MUX, "create proc %p\n",
+                                                                        vpt);
+                                pproc = kthread_create(p9_poll_proc, vpt,
+                                                                "v9fs-poll");
+
+                                if (!IS_ERR(pproc)) {
+                                        vpt->task = pproc;
+                                        INIT_LIST_HEAD(&vpt->mux_list);
+                                        vpt->muxnum = 0;
+                                        p9_mux_poll_task_num++;
+                                        wake_up_process(vpt->task);
+                                }
+                                break;
+                        }
+                }
+
+                if (i >= ARRAY_SIZE(p9_mux_poll_tasks))
+                        P9_DPRINTK(P9_DEBUG_ERROR,
+                                        "warning: no free poll slots\n");
+        }
+
+        n = (p9_mux_num + 1) / p9_mux_poll_task_num +
+            ((p9_mux_num + 1) % p9_mux_poll_task_num ? 1 : 0);
+
+        vptlast = NULL;
+        for (i = 0; i < ARRAY_SIZE(p9_mux_poll_tasks); i++) {
+                vpt = &p9_mux_poll_tasks[i];
+                if (vpt->task != NULL) {
+                        vptlast = vpt;
+                        if (vpt->muxnum < n) {
+                                P9_DPRINTK(P9_DEBUG_MUX, "put in proc %d\n", i);
+                                list_add(&m->mux_list, &vpt->mux_list);
+                                vpt->muxnum++;
+                                m->poll_task = vpt;
+                                memset(&m->poll_waddr, 0,
+                                                        sizeof(m->poll_waddr));
+                                init_poll_funcptr(&m->pt, p9_pollwait);
+                                break;
+                        }
+                }
+        }
+
+        if (i >= ARRAY_SIZE(p9_mux_poll_tasks)) {
+                if (vptlast == NULL)
+                        return -ENOMEM;
+
+                P9_DPRINTK(P9_DEBUG_MUX, "put in proc %d\n", i);
+                list_add(&m->mux_list, &vptlast->mux_list);
+                vptlast->muxnum++;
+                m->poll_task = vptlast;
+                memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
+                init_poll_funcptr(&m->pt, p9_pollwait);
+        }
+
+        p9_mux_num++;
+        mutex_unlock(&p9_mux_task_lock);
+
+        return 0;
+}
+
+static void p9_mux_poll_stop(struct p9_conn *m)
+{
+        int i;
+        struct p9_mux_poll_task *vpt;
+
+        mutex_lock(&p9_mux_task_lock);
+        vpt = m->poll_task;
+        list_del(&m->mux_list);
+        for (i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
+                if (m->poll_waddr[i] != NULL) {
+                        remove_wait_queue(m->poll_waddr[i], &m->poll_wait[i]);
+                        m->poll_waddr[i] = NULL;
+                }
+        }
+        vpt->muxnum--;
+        if (!vpt->muxnum) {
+                P9_DPRINTK(P9_DEBUG_MUX, "destroy proc %p\n", vpt);
+                kthread_stop(vpt->task);
+                vpt->task = NULL;
+                p9_mux_poll_task_num--;
+        }
+        p9_mux_num--;
+        mutex_unlock(&p9_mux_task_lock);
+}
+
+/**
+ * p9_conn_create - allocate and initialize the per-session mux data
+ * Creates the polling task if this is the first session.
+ *
+ * @trans - transport structure
+ * @msize - maximum message size
+ * @extended - pointer to the extended flag
+ */
+struct p9_conn *p9_conn_create(struct p9_transport *trans, int msize,
+                                    unsigned char *extended)
+{
+        int i, n;
+        struct p9_conn *m, *mtmp;
+
+        P9_DPRINTK(P9_DEBUG_MUX, "transport %p msize %d\n", trans, msize);
+        m = kmalloc(sizeof(struct p9_conn), GFP_KERNEL);
+        if (!m)
+                return ERR_PTR(-ENOMEM);
+
+        spin_lock_init(&m->lock);
+        INIT_LIST_HEAD(&m->mux_list);
+        m->msize = msize;
+        m->extended = extended;
+        m->trans = trans;
+        m->tagpool = p9_idpool_create();
+        if (!m->tagpool) {
+                kfree(m);
+                return ERR_PTR(PTR_ERR(m->tagpool));
+        }
+
+        m->err = 0;
+        init_waitqueue_head(&m->equeue);
+        INIT_LIST_HEAD(&m->req_list);
+        INIT_LIST_HEAD(&m->unsent_req_list);
+        m->rcall = NULL;
+        m->rpos = 0;
+        m->rbuf = NULL;
+        m->wpos = m->wsize = 0;
+        m->wbuf = NULL;
+        INIT_WORK(&m->rq, p9_read_work);
+        INIT_WORK(&m->wq, p9_write_work);
+        m->wsched = 0;
+        memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
+        m->poll_task = NULL;
+        n = p9_mux_poll_start(m);
+        if (n)
+                return ERR_PTR(n);
+
+        n = trans->poll(trans, &m->pt);
+        if (n & POLLIN) {
+                P9_DPRINTK(P9_DEBUG_MUX, "mux %p can read\n", m);
+                set_bit(Rpending, &m->wsched);
+        }
+
+        if (n & POLLOUT) {
+                P9_DPRINTK(P9_DEBUG_MUX, "mux %p can write\n", m);
+                set_bit(Wpending, &m->wsched);
+        }
+
+        for (i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
+                if (IS_ERR(m->poll_waddr[i])) {
+                        p9_mux_poll_stop(m);
+                        mtmp = (void *)m->poll_waddr;   /* the error code */
+                        kfree(m);
+                        m = mtmp;
+                        break;
+                }
+        }
+
+        return m;
+}
+EXPORT_SYMBOL(p9_conn_create);
+
+/**
+ * p9_mux_destroy - cancels all pending requests and frees mux resources
+ */
+void p9_conn_destroy(struct p9_conn *m)
+{
+        P9_DPRINTK(P9_DEBUG_MUX, "mux %p prev %p next %p\n", m,
+                m->mux_list.prev, m->mux_list.next);
+        p9_conn_cancel(m, -ECONNRESET);
+
+        if (!list_empty(&m->req_list)) {
+                /* wait until all processes waiting on this session exit */
+                P9_DPRINTK(P9_DEBUG_MUX,
+                        "mux %p waiting for empty request queue\n", m);
+                wait_event_timeout(m->equeue, (list_empty(&m->req_list)), 5000);
+                P9_DPRINTK(P9_DEBUG_MUX, "mux %p request queue empty: %d\n", m,
+                        list_empty(&m->req_list));
+        }
+
+        p9_mux_poll_stop(m);
+        m->trans = NULL;
+        p9_idpool_destroy(m->tagpool);
+        kfree(m);
+}
+EXPORT_SYMBOL(p9_conn_destroy);
+
+/**
+ * p9_pollwait - 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)
+{
+        int i;
+        struct p9_conn *m;
+
+        m = container_of(p, struct p9_conn, pt);
+        for (i = 0; i < ARRAY_SIZE(m->poll_waddr); i++)
+                if (m->poll_waddr[i] == NULL)
+                        break;
+
+        if (i >= ARRAY_SIZE(m->poll_waddr)) {
+                P9_DPRINTK(P9_DEBUG_ERROR, "not enough wait_address slots\n");
+                return;
+        }
+
+        m->poll_waddr[i] = wait_address;
+
+        if (!wait_address) {
+                P9_DPRINTK(P9_DEBUG_ERROR, "no wait_address\n");
+                m->poll_waddr[i] = ERR_PTR(-EIO);
+                return;
+        }
+
+        init_waitqueue_entry(&m->poll_wait[i], m->poll_task->task);
+        add_wait_queue(wait_address, &m->poll_wait[i]);
+}
+
+/**
+ * p9_poll_mux - polls a mux and schedules read or write works if necessary
+ */
+static void p9_poll_mux(struct p9_conn *m)
+{
+        int n;
+
+        if (m->err < 0)
+                return;
+
+        n = m->trans->poll(m->trans, NULL);
+        if (n < 0 || n & (POLLERR | POLLHUP | POLLNVAL)) {
+                P9_DPRINTK(P9_DEBUG_MUX, "error mux %p err %d\n", m, n);
+                if (n >= 0)
+                        n = -ECONNRESET;
+                p9_conn_cancel(m, n);
+        }
+
+        if (n & POLLIN) {
+                set_bit(Rpending, &m->wsched);
+                P9_DPRINTK(P9_DEBUG_MUX, "mux %p can read\n", m);
+                if (!test_and_set_bit(Rworksched, &m->wsched)) {
+                        P9_DPRINTK(P9_DEBUG_MUX, "schedule read work %p\n", m);
+                        queue_work(p9_mux_wq, &m->rq);
+                }
+        }
+
+        if (n & POLLOUT) {
+                set_bit(Wpending, &m->wsched);
+                P9_DPRINTK(P9_DEBUG_MUX, "mux %p can write\n", m);
+                if ((m->wsize || !list_empty(&m->unsent_req_list))
+                    && !test_and_set_bit(Wworksched, &m->wsched)) {
+                        P9_DPRINTK(P9_DEBUG_MUX, "schedule write work %p\n", m);
+                        queue_work(p9_mux_wq, &m->wq);
+                }
+        }
+}
+
+/**
+ * p9_poll_proc - polls all v9fs transports for new events and queues
+ *      the appropriate work to the work queue
+ */
+static int p9_poll_proc(void *a)
+{
+        struct p9_conn *m, *mtmp;
+        struct p9_mux_poll_task *vpt;
+
+        vpt = a;
+        P9_DPRINTK(P9_DEBUG_MUX, "start %p %p\n", current, vpt);
+        while (!kthread_should_stop()) {
+                set_current_state(TASK_INTERRUPTIBLE);
+
+                list_for_each_entry_safe(m, mtmp, &vpt->mux_list, mux_list) {
+                        p9_poll_mux(m);
+                }
+
+                P9_DPRINTK(P9_DEBUG_MUX, "sleeping...\n");
+                schedule_timeout(SCHED_TIMEOUT * HZ);
+        }
+
+        __set_current_state(TASK_RUNNING);
+        P9_DPRINTK(P9_DEBUG_MUX, "finish\n");
+        return 0;
+}
+
+/**
+ * p9_write_work - called when a transport can send some data
+ */
+static void p9_write_work(struct work_struct *work)
+{
+        int n, err;
+        struct p9_conn *m;
+        struct p9_req *req;
+
+        m = container_of(work, struct p9_conn, wq);
+
+        if (m->err < 0) {
+                clear_bit(Wworksched, &m->wsched);
+                return;
+        }
+
+        if (!m->wsize) {
+                if (list_empty(&m->unsent_req_list)) {
+                        clear_bit(Wworksched, &m->wsched);
+                        return;
+                }
+
+                spin_lock(&m->lock);
+again:
+                req = list_entry(m->unsent_req_list.next, struct p9_req,
+                               req_list);
+                list_move_tail(&req->req_list, &m->req_list);
+                if (req->err == ERREQFLUSH)
+                        goto again;
+
+                m->wbuf = req->tcall->sdata;
+                m->wsize = req->tcall->size;
+                m->wpos = 0;
+                spin_unlock(&m->lock);
+        }
+
+        P9_DPRINTK(P9_DEBUG_MUX, "mux %p pos %d size %d\n", m, m->wpos,
+                                                                m->wsize);
+        clear_bit(Wpending, &m->wsched);
+        err = m->trans->write(m->trans, m->wbuf + m->wpos, m->wsize - m->wpos);
+        P9_DPRINTK(P9_DEBUG_MUX, "mux %p sent %d bytes\n", m, err);
+        if (err == -EAGAIN) {
+                clear_bit(Wworksched, &m->wsched);
+                return;
+        }
+
+        if (err <= 0)
+                goto error;
+
+        m->wpos += err;
+        if (m->wpos == m->wsize)
+                m->wpos = m->wsize = 0;
+
+        if (m->wsize == 0 && !list_empty(&m->unsent_req_list)) {
+                if (test_and_clear_bit(Wpending, &m->wsched))
+                        n = POLLOUT;
+                else
+                        n = m->trans->poll(m->trans, NULL);
+
+                if (n & POLLOUT) {
+                        P9_DPRINTK(P9_DEBUG_MUX, "schedule write work %p\n", m);
+                        queue_work(p9_mux_wq, &m->wq);
+                } else
+                        clear_bit(Wworksched, &m->wsched);
+        } else
+                clear_bit(Wworksched, &m->wsched);
+
+        return;
+
+error:
+        p9_conn_cancel(m, err);
+        clear_bit(Wworksched, &m->wsched);
+}
+
+static void process_request(struct p9_conn *m, struct p9_req *req)
+{
+        int ecode;
+        struct p9_str *ename;
+
+        if (!req->err && req->rcall->id == P9_RERROR) {
+                ecode = req->rcall->params.rerror.errno;
+                ename = &req->rcall->params.rerror.error;
+
+                P9_DPRINTK(P9_DEBUG_MUX, "Rerror %.*s\n", ename->len,
+                                                                ename->str);
+
+                if (*m->extended)
+                        req->err = -ecode;
+
+                if (!req->err) {
+                        req->err = p9_errstr2errno(ename->str, ename->len);
+
+                        if (!req->err) {        /* string match failed */
+                                PRINT_FCALL_ERROR("unknown error", req->rcall);
+                        }
+
+                        if (!req->err)
+                                req->err = -ESERVERFAULT;
+                }
+        } else if (req->tcall && req->rcall->id != req->tcall->id + 1) {
+                P9_DPRINTK(P9_DEBUG_ERROR,
+                                "fcall mismatch: expected %d, got %d\n",
+                                req->tcall->id + 1, req->rcall->id);
+                if (!req->err)
+                        req->err = -EIO;
+        }
+}
+
+/**
+ * p9_read_work - called when there is some data to be read from a transport
+ */
+static void p9_read_work(struct work_struct *work)
+{
+        int n, err;
+        struct p9_conn *m;
+        struct p9_req *req, *rptr, *rreq;
+        struct p9_fcall *rcall;
+        char *rbuf;
+
+        m = container_of(work, struct p9_conn, rq);
+
+        if (m->err < 0)
+                return;
+
+        rcall = NULL;
+        P9_DPRINTK(P9_DEBUG_MUX, "start mux %p pos %d\n", m, m->rpos);
+
+        if (!m->rcall) {
+                m->rcall =
+                    kmalloc(sizeof(struct p9_fcall) + m->msize, GFP_KERNEL);
+                if (!m->rcall) {
+                        err = -ENOMEM;
+                        goto error;
+                }
+
+                m->rbuf = (char *)m->rcall + sizeof(struct p9_fcall);
+                m->rpos = 0;
+        }
+
+        clear_bit(Rpending, &m->wsched);
+        err = m->trans->read(m->trans, m->rbuf + m->rpos, m->msize - m->rpos);
+        P9_DPRINTK(P9_DEBUG_MUX, "mux %p got %d bytes\n", m, err);
+        if (err == -EAGAIN) {
+                clear_bit(Rworksched, &m->wsched);
+                return;
+        }
+
+        if (err <= 0)
+                goto error;
+
+        m->rpos += err;
+        while (m->rpos > 4) {
+                n = le32_to_cpu(*(__le32 *) m->rbuf);
+                if (n >= m->msize) {
+                        P9_DPRINTK(P9_DEBUG_ERROR,
+                                "requested packet size too big: %d\n", n);
+                        err = -EIO;
+                        goto error;
+                }
+
+                if (m->rpos < n)
+                        break;
+
+                err =
+                    p9_deserialize_fcall(m->rbuf, n, m->rcall, *m->extended);
+                if (err < 0) {
+                        goto error;
+                }
+
+#ifdef CONFIG_NET_9P_DEBUG
+                if ((p9_debug_level&P9_DEBUG_FCALL) == P9_DEBUG_FCALL) {
+                        char buf[150];
+
+                        p9_printfcall(buf, sizeof(buf), m->rcall,
+                                *m->extended);
+                        printk(KERN_NOTICE ">>> %p %s\n", m, buf);
+                }
+#endif
+
+                rcall = m->rcall;
+                rbuf = m->rbuf;
+                if (m->rpos > n) {
+                        m->rcall = kmalloc(sizeof(struct p9_fcall) + m->msize,
+                                           GFP_KERNEL);
+                        if (!m->rcall) {
+                                err = -ENOMEM;
+                                goto error;
+                        }
+
+                        m->rbuf = (char *)m->rcall + sizeof(struct p9_fcall);
+                        memmove(m->rbuf, rbuf + n, m->rpos - n);
+                        m->rpos -= n;
+                } else {
+                        m->rcall = NULL;
+                        m->rbuf = NULL;
+                        m->rpos = 0;
+                }
+
+                P9_DPRINTK(P9_DEBUG_MUX, "mux %p fcall id %d tag %d\n", m,
+                                                        rcall->id, rcall->tag);
+
+                req = NULL;
+                spin_lock(&m->lock);
+                list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
+                        if (rreq->tag == rcall->tag) {
+                                req = rreq;
+                                if (req->flush != Flushing)
+                                        list_del(&req->req_list);
+                                break;
+                        }
+                }
+                spin_unlock(&m->lock);
+
+                if (req) {
+                        req->rcall = rcall;
+                        process_request(m, req);
+
+                        if (req->flush != Flushing) {
+                                if (req->cb)
+                                        (*req->cb) (req, req->cba);
+                                else
+                                        kfree(req->rcall);
+
+                                wake_up(&m->equeue);
+                        }
+                } else {
+                        if (err >= 0 && rcall->id != P9_RFLUSH)
+                                P9_DPRINTK(P9_DEBUG_ERROR,
+                                  "unexpected response mux %p id %d tag %d\n",
+                                  m, rcall->id, rcall->tag);
+                        kfree(rcall);
+                }
+        }
+
+        if (!list_empty(&m->req_list)) {
+                if (test_and_clear_bit(Rpending, &m->wsched))
+                        n = POLLIN;
+                else
+                        n = m->trans->poll(m->trans, NULL);
+
+                if (n & POLLIN) {
+                        P9_DPRINTK(P9_DEBUG_MUX, "schedule read work %p\n", m);
+                        queue_work(p9_mux_wq, &m->rq);
+                } else
+                        clear_bit(Rworksched, &m->wsched);
+        } else
+                clear_bit(Rworksched, &m->wsched);
+
+        return;
+
+error:
+        p9_conn_cancel(m, err);
+        clear_bit(Rworksched, &m->wsched);
+}
+
+/**
+ * p9_send_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. Can return errors
+ * that can be retrieved by PTR_ERR macros.
+ *
+ * @m: mux data
+ * @tc: request to be sent
+ * @cb: callback function to call when response is received
+ * @cba: parameter to pass to the callback function
+ */
+static struct p9_req *p9_send_request(struct p9_conn *m,
+                                          struct p9_fcall *tc,
+                                          p9_conn_req_callback cb, void *cba)
+{
+        int n;
+        struct p9_req *req;
+
+        P9_DPRINTK(P9_DEBUG_MUX, "mux %p task %p tcall %p id %d\n", m, current,
+                tc, tc->id);
+        if (m->err < 0)
+                return ERR_PTR(m->err);
+
+        req = kmalloc(sizeof(struct p9_req), GFP_KERNEL);
+        if (!req)
+                return ERR_PTR(-ENOMEM);
+
+        if (tc->id == P9_TVERSION)
+                n = P9_NOTAG;
+        else
+                n = p9_mux_get_tag(m);
+
+        if (n < 0)
+                return ERR_PTR(-ENOMEM);
+
+        p9_set_tag(tc, n);
+
+#ifdef CONFIG_NET_9P_DEBUG
+        if ((p9_debug_level&P9_DEBUG_FCALL) == P9_DEBUG_FCALL) {
+                char buf[150];
+
+                p9_printfcall(buf, sizeof(buf), tc, *m->extended);
+                printk(KERN_NOTICE "<<< %p %s\n", m, buf);
+        }
+#endif
+
+        spin_lock_init(&req->lock);
+        req->tag = n;
+        req->tcall = tc;
+        req->rcall = NULL;
+        req->err = 0;
+        req->cb = cb;
+        req->cba = cba;
+        req->flush = None;
+
+        spin_lock(&m->lock);
+        list_add_tail(&req->req_list, &m->unsent_req_list);
+        spin_unlock(&m->lock);
+
+        if (test_and_clear_bit(Wpending, &m->wsched))
+                n = POLLOUT;
+        else
+                n = m->trans->poll(m->trans, NULL);
+
+        if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
+                queue_work(p9_mux_wq, &m->wq);
+
+        return req;
+}
+
+static void p9_mux_free_request(struct p9_conn *m, struct p9_req *req)
+{
+        p9_mux_put_tag(m, req->tag);
+        kfree(req);
+}
+
+static void p9_mux_flush_cb(struct p9_req *freq, void *a)
+{
+        p9_conn_req_callback cb;
+        int tag;
+        struct p9_conn *m;
+        struct p9_req *req, *rreq, *rptr;
+
+        m = a;
+        P9_DPRINTK(P9_DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m,
+                freq->tcall, freq->rcall, freq->err,
+                freq->tcall->params.tflush.oldtag);
+
+        spin_lock(&m->lock);
+        cb = NULL;
+        tag = freq->tcall->params.tflush.oldtag;
+        req = NULL;
+        list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
+                if (rreq->tag == tag) {
+                        req = rreq;
+                        list_del(&req->req_list);
+                        break;
+                }
+        }
+        spin_unlock(&m->lock);
+
+        if (req) {
+                spin_lock(&req->lock);
+                req->flush = Flushed;
+                spin_unlock(&req->lock);
+
+                if (req->cb)
+                        (*req->cb) (req, req->cba);
+                else
+                        kfree(req->rcall);
+
+                wake_up(&m->equeue);
+        }
+
+        kfree(freq->tcall);
+        kfree(freq->rcall);
+        p9_mux_free_request(m, freq);
+}
+
+static int
+p9_mux_flush_request(struct p9_conn *m, struct p9_req *req)
+{
+        struct p9_fcall *fc;
+        struct p9_req *rreq, *rptr;
+
+        P9_DPRINTK(P9_DEBUG_MUX, "mux %p req %p tag %d\n", m, req, req->tag);
+
+        /* if a response was received for a request, do nothing */
+        spin_lock(&req->lock);
+        if (req->rcall || req->err) {
+                spin_unlock(&req->lock);
+                P9_DPRINTK(P9_DEBUG_MUX,
+                        "mux %p req %p response already received\n", m, req);
+                return 0;
+        }
+
+        req->flush = Flushing;
+        spin_unlock(&req->lock);
+
+        spin_lock(&m->lock);
+        /* if the request is not sent yet, just remove it from the list */
+        list_for_each_entry_safe(rreq, rptr, &m->unsent_req_list, req_list) {
+                if (rreq->tag == req->tag) {
+                        P9_DPRINTK(P9_DEBUG_MUX,
+                           "mux %p req %p request is not sent yet\n", m, req);
+                        list_del(&rreq->req_list);
+                        req->flush = Flushed;
+                        spin_unlock(&m->lock);
+                        if (req->cb)
+                                (*req->cb) (req, req->cba);
+                        return 0;
+                }
+        }
+        spin_unlock(&m->lock);
+
+        clear_thread_flag(TIF_SIGPENDING);
+        fc = p9_create_tflush(req->tag);
+        p9_send_request(m, fc, p9_mux_flush_cb, m);
+        return 1;
+}
+
+static void
+p9_conn_rpc_cb(struct p9_req *req, void *a)
+{
+        struct p9_mux_rpc *r;
+
+        P9_DPRINTK(P9_DEBUG_MUX, "req %p r %p\n", req, a);
+        r = a;
+        r->rcall = req->rcall;
+        r->err = req->err;
+
+        if (req->flush != None && !req->err)
+                r->err = -ERESTARTSYS;
+
+        wake_up(&r->wqueue);
+}
+
+/**
+ * p9_mux_rpc - sends 9P request and waits until a response is available.
+ *      The function can be interrupted.
+ * @m: mux data
+ * @tc: request to be sent
+ * @rc: pointer where a pointer to the response is stored
+ */
+int
+p9_conn_rpc(struct p9_conn *m, struct p9_fcall *tc,
+             struct p9_fcall **rc)
+{
+        int err, sigpending;
+        unsigned long flags;
+        struct p9_req *req;
+        struct p9_mux_rpc r;
+
+        r.err = 0;
+        r.tcall = tc;
+        r.rcall = NULL;
+        r.m = m;
+        init_waitqueue_head(&r.wqueue);
+
+        if (rc)
+                *rc = NULL;
+
+        sigpending = 0;
+        if (signal_pending(current)) {
+                sigpending = 1;
+                clear_thread_flag(TIF_SIGPENDING);
+        }
+
+        req = p9_send_request(m, tc, p9_conn_rpc_cb, &r);
+        if (IS_ERR(req)) {
+                err = PTR_ERR(req);
+                P9_DPRINTK(P9_DEBUG_MUX, "error %d\n", err);
+                return err;
+        }
+
+        err = wait_event_interruptible(r.wqueue, r.rcall != NULL || r.err < 0);
+        if (r.err < 0)
+                err = r.err;
+
+        if (err == -ERESTARTSYS && m->trans->status == Connected
+                                                        && m->err == 0) {
+                if (p9_mux_flush_request(m, req)) {
+                        /* wait until we get response of the flush message */
+                        do {
+                                clear_thread_flag(TIF_SIGPENDING);
+                                err = wait_event_interruptible(r.wqueue,
+                                        r.rcall || r.err);
+                        } while (!r.rcall && !r.err && err == -ERESTARTSYS &&
+                                m->trans->status == Connected && !m->err);
+
+                        err = -ERESTARTSYS;
+                }
+                sigpending = 1;
+        }
+
+        if (sigpending) {
+                spin_lock_irqsave(&current->sighand->siglock, flags);
+                recalc_sigpending();
+                spin_unlock_irqrestore(&current->sighand->siglock, flags);
+        }
+
+        if (rc)
+                *rc = r.rcall;
+        else
+                kfree(r.rcall);
+
+        p9_mux_free_request(m, req);
+        if (err > 0)
+                err = -EIO;
+
+        return err;
+}
+EXPORT_SYMBOL(p9_conn_rpc);
+
+#ifdef P9_NONBLOCK
+/**
+ * p9_conn_rpcnb - sends 9P request without waiting for response.
+ * @m: mux data
+ * @tc: request to be sent
+ * @cb: callback function to be called when response arrives
+ * @cba: value to pass to the callback function
+ */
+int p9_conn_rpcnb(struct p9_conn *m, struct p9_fcall *tc,
+                   p9_conn_req_callback cb, void *a)
+{
+        int err;
+        struct p9_req *req;
+
+        req = p9_send_request(m, tc, cb, a);
+        if (IS_ERR(req)) {
+                err = PTR_ERR(req);
+                P9_DPRINTK(P9_DEBUG_MUX, "error %d\n", err);
+                return PTR_ERR(req);
+        }
+
+        P9_DPRINTK(P9_DEBUG_MUX, "mux %p tc %p tag %d\n", m, tc, req->tag);
+        return 0;
+}
+EXPORT_SYMBOL(p9_conn_rpcnb);
+#endif /* P9_NONBLOCK */
+
+/**
+ * p9_conn_cancel - cancel all pending requests with error
+ * @m: mux data
+ * @err: error code
+ */
+void p9_conn_cancel(struct p9_conn *m, int err)
+{
+        struct p9_req *req, *rtmp;
+        LIST_HEAD(cancel_list);
+
+        P9_DPRINTK(P9_DEBUG_ERROR, "mux %p err %d\n", m, err);
+        m->err = err;
+        spin_lock(&m->lock);
+        list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
+                list_move(&req->req_list, &cancel_list);
+        }
+        list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
+                list_move(&req->req_list, &cancel_list);
+        }
+        spin_unlock(&m->lock);
+
+        list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
+                list_del(&req->req_list);
+                if (!req->err)
+                        req->err = err;
+
+                if (req->cb)
+                        (*req->cb) (req, req->cba);
+                else
+                        kfree(req->rcall);
+        }
+
+        wake_up(&m->equeue);
+}
+EXPORT_SYMBOL(p9_conn_cancel);
+
+static u16 p9_mux_get_tag(struct p9_conn *m)
+{
+        int tag;
+
+        tag = p9_idpool_get(m->tagpool);
+        if (tag < 0)
+                return P9_NOTAG;
+        else
+                return (u16) tag;
+}
+
+static void p9_mux_put_tag(struct p9_conn *m, u16 tag)
+{
+        if (tag != P9_NOTAG && p9_idpool_check(tag, m->tagpool))
+                p9_idpool_put(tag, m->tagpool);
+}