net/9p/trans_fd.c:p9_trans_fd_init(): module_init functions should return 0 on success
[sfrench/cifs-2.6.git] / net / 9p / trans_fd.c
index 62332ed9da4afcd7e8b06577f0e4ec47d07ed171..f624dff76852f1881d266320f8ea1362c9a8eb1d 100644 (file)
@@ -5,7 +5,7 @@
  *
  *  Copyright (C) 2006 by Russ Cox <rsc@swtch.com>
  *  Copyright (C) 2004-2005 by Latchesar Ionkov <lucho@ionkov.net>
- *  Copyright (C) 2004-2007 by Eric Van Hensbergen <ericvh@gmail.com>
+ *  Copyright (C) 2004-2008 by Eric Van Hensbergen <ericvh@gmail.com>
  *  Copyright (C) 1997-2002 by Ron Minnich <rminnich@sarnoff.com>
  *
  *  This program is free software; you can redistribute it and/or modify
@@ -29,6 +29,7 @@
 #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>
@@ -42,7 +43,9 @@
 
 #define P9_PORT 564
 #define MAX_SOCK_BUF (64*1024)
-
+#define ERREQFLUSH     1
+#define SCHED_TIMEOUT  10
+#define MAXPOLLWADDR   2
 
 struct p9_fd_opts {
        int rfd;
@@ -53,6 +56,7 @@ struct p9_fd_opts {
 struct p9_trans_fd {
        struct file *rd;
        struct file *wr;
+       struct p9_conn *conn;
 };
 
 /*
@@ -72,6 +76,1026 @@ static match_table_t tokens = {
        {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 */
+};
+
+enum {
+       None,
+       Flushing,
+       Flushed,
+};
+
+struct p9_req;
+
+typedef void (*p9_conn_req_callback)(struct p9_req *req, void *a);
+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_mux_poll_task;
+
+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_trans *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 int p9_fd_write(struct p9_trans *trans, void *v, int len);
+static int p9_fd_read(struct p9_trans *trans, void *v, int len);
+
+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];
+
+static void p9_conn_destroy(struct p9_conn *);
+static unsigned int p9_fd_poll(struct p9_trans *trans,
+                                               struct poll_table_struct *pt);
+
+#ifdef P9_NONBLOCK
+static int p9_conn_rpcnb(struct p9_conn *m, struct p9_fcall *tc,
+       p9_conn_req_callback cb, void *a);
+#endif /* P9_NONBLOCK */
+
+static void p9_conn_cancel(struct p9_conn *m, int err);
+
+static 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;
+}
+
+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);
+}
+
+/**
+ * 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) {
+                       mutex_unlock(&p9_mux_task_lock);
+                       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 - extended flag
+ */
+static struct p9_conn *p9_conn_create(struct p9_trans *trans)
+{
+       int i, n;
+       struct p9_conn *m, *mtmp;
+
+       P9_DPRINTK(P9_DEBUG_MUX, "transport %p msize %d\n", trans,
+                                                               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 = trans->msize;
+       m->extended = trans->extended;
+       m->trans = trans;
+       m->tagpool = p9_idpool_create();
+       if (IS_ERR(m->tagpool)) {
+               mtmp = ERR_PTR(-ENOMEM);
+               kfree(m);
+               return mtmp;
+       }
+
+       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) {
+               kfree(m);
+               return ERR_PTR(n);
+       }
+
+       n = p9_fd_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;
+}
+
+/**
+ * p9_mux_destroy - cancels all pending requests and frees mux resources
+ */
+static 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);
+}
+
+/**
+ * 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 = p9_fd_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 = p9_fd_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;
+       else if (err == 0) {
+               err = -EREMOTEIO;
+               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 = p9_fd_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);
+
+                       /* string match failed */
+                       if (!req->err) {
+                               PRINT_FCALL_ERROR("unknown error", req->rcall);
+                               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 = p9_fd_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 = p9_fd_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 = p9_fd_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)
+{
+       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);
+       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_fd_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_fd_rpc(struct p9_trans *t, struct p9_fcall *tc, struct p9_fcall **rc)
+{
+       struct p9_trans_fd *p = t->priv;
+       struct p9_conn *m = p->conn;
+       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;
+}
+
+#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;
+}
+#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);
+}
+
 /**
  * v9fs_parse_options - parse mount options into session structure
  * @options: options string passed from mount
@@ -268,7 +1292,7 @@ end:
 }
 
 /**
- * p9_sock_close - shutdown socket
+ * p9_fd_close - shutdown socket
  * @trans: private socket structure
  *
  */
@@ -284,6 +1308,8 @@ static void p9_fd_close(struct p9_trans *trans)
        if (!ts)
                return;
 
+       p9_conn_destroy(ts->conn);
+
        trans->status = Disconnected;
        if (ts->rd)
                fput(ts->rd);
@@ -292,13 +1318,15 @@ static void p9_fd_close(struct p9_trans *trans)
        kfree(ts);
 }
 
-static struct p9_trans *p9_trans_create_tcp(const char *addr, char *args)
+static struct p9_trans *
+p9_trans_create_tcp(const char *addr, char *args, int msize, unsigned char dotu)
 {
        int err;
        struct p9_trans *trans;
        struct socket *csocket;
        struct sockaddr_in sin_server;
        struct p9_fd_opts opts;
+       struct p9_trans_fd *p;
 
        parse_opts(args, &opts);
 
@@ -306,11 +1334,10 @@ static struct p9_trans *p9_trans_create_tcp(const char *addr, char *args)
        trans = kmalloc(sizeof(struct p9_trans), GFP_KERNEL);
        if (!trans)
                return ERR_PTR(-ENOMEM);
-
-       trans->write = p9_fd_write;
-       trans->read = p9_fd_read;
+       trans->msize = msize;
+       trans->extended = dotu;
+       trans->rpc = p9_fd_rpc;
        trans->close = p9_fd_close;
-       trans->poll = p9_fd_poll;
 
        sin_server.sin_family = AF_INET;
        sin_server.sin_addr.s_addr = in_aton(addr);
@@ -337,6 +1364,14 @@ static struct p9_trans *p9_trans_create_tcp(const char *addr, char *args)
        if (err < 0)
                goto error;
 
+       p = (struct p9_trans_fd *) trans->priv;
+       p->conn = p9_conn_create(trans);
+       if (IS_ERR(p->conn)) {
+               err = PTR_ERR(p->conn);
+               p->conn = NULL;
+               goto error;
+       }
+
        return trans;
 
 error:
@@ -347,22 +1382,23 @@ error:
        return ERR_PTR(err);
 }
 
-static struct p9_trans *p9_trans_create_unix(const char *addr, char *args)
+static struct p9_trans *
+p9_trans_create_unix(const char *addr, char *args, int msize,
+                                                       unsigned char dotu)
 {
        int err;
        struct socket *csocket;
        struct sockaddr_un sun_server;
        struct p9_trans *trans;
+       struct p9_trans_fd *p;
 
        csocket = NULL;
        trans = kmalloc(sizeof(struct p9_trans), GFP_KERNEL);
        if (!trans)
                return ERR_PTR(-ENOMEM);
 
-       trans->write = p9_fd_write;
-       trans->read = p9_fd_read;
+       trans->rpc = p9_fd_rpc;
        trans->close = p9_fd_close;
-       trans->poll = p9_fd_poll;
 
        if (strlen(addr) > UNIX_PATH_MAX) {
                P9_EPRINTK(KERN_ERR, "p9_trans_unix: address too long: %s\n",
@@ -387,6 +1423,16 @@ static struct p9_trans *p9_trans_create_unix(const char *addr, char *args)
        if (err < 0)
                goto error;
 
+       trans->msize = msize;
+       trans->extended = dotu;
+       p = (struct p9_trans_fd *) trans->priv;
+       p->conn = p9_conn_create(trans);
+       if (IS_ERR(p->conn)) {
+               err = PTR_ERR(p->conn);
+               p->conn = NULL;
+               goto error;
+       }
+
        return trans;
 
 error:
@@ -397,11 +1443,14 @@ error:
        return ERR_PTR(err);
 }
 
-static struct p9_trans *p9_trans_create_fd(const char *name, char *args)
+static struct p9_trans *
+p9_trans_create_fd(const char *name, char *args, int msize,
+                                                       unsigned char extended)
 {
        int err;
        struct p9_trans *trans;
        struct p9_fd_opts opts;
+       struct p9_trans_fd *p;
 
        parse_opts(args, &opts);
 
@@ -414,15 +1463,23 @@ static struct p9_trans *p9_trans_create_fd(const char *name, char *args)
        if (!trans)
                return ERR_PTR(-ENOMEM);
 
-       trans->write = p9_fd_write;
-       trans->read = p9_fd_read;
+       trans->rpc = p9_fd_rpc;
        trans->close = p9_fd_close;
-       trans->poll = p9_fd_poll;
 
        err = p9_fd_open(trans, opts.rfd, opts.wfd);
        if (err < 0)
                goto error;
 
+       trans->msize = msize;
+       trans->extended = extended;
+       p = (struct p9_trans_fd *) trans->priv;
+       p->conn = p9_conn_create(trans);
+       if (IS_ERR(p->conn)) {
+               err = PTR_ERR(p->conn);
+               p->conn = NULL;
+               goto error;
+       }
+
        return trans;
 
 error:
@@ -453,20 +1510,20 @@ static struct p9_trans_module p9_fd_trans = {
 
 static int __init p9_trans_fd_init(void)
 {
+       int ret = p9_mux_global_init();
+       if (ret) {
+               printk(KERN_WARNING "9p: starting mux failed\n");
+               return ret;
+       }
+
        v9fs_register_trans(&p9_tcp_trans);
        v9fs_register_trans(&p9_unix_trans);
        v9fs_register_trans(&p9_fd_trans);
 
-       return 1;
-}
-
-static void __exit p9_trans_fd_exit(void) {
-       printk(KERN_ERR "Removal of 9p transports not implemented\n");
-       BUG();
+       return 0;
 }
 
 module_init(p9_trans_fd_init);
-module_exit(p9_trans_fd_exit);
 
 MODULE_AUTHOR("Latchesar Ionkov <lucho@ionkov.net>");
 MODULE_AUTHOR("Eric Van Hensbergen <ericvh@gmail.com>");