fs/9p/mux.c

   1 /*
   2  * linux/fs/9p/mux.c
   3  *
   4  * Protocol Multiplexer
   5  *
   6  *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
   7  *  Copyright (C) 2004-2005 by Latchesar Ionkov <lucho@ionkov.net>
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License version 2
  11  *  as published by the Free Software Foundation.
  12  *
  13  *  This program is distributed in the hope that it will be useful,
  14  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  *  GNU General Public License for more details.
  17  *
  18  *  You should have received a copy of the GNU General Public License
  19  *  along with this program; if not, write to:
  20  *  Free Software Foundation
  21  *  51 Franklin Street, Fifth Floor
  22  *  Boston, MA  02111-1301  USA
  23  *
  24  */
  25
  26 #include <linux/module.h>
  27 #include <linux/errno.h>
  28 #include <linux/fs.h>
  29 #include <linux/poll.h>
  30 #include <linux/kthread.h>
  31 #include <linux/idr.h>
  32 #include <linux/mutex.h>
  33
  34 #include "debug.h"
  35 #include "v9fs.h"
  36 #include "9p.h"
  37 #include "conv.h"
  38 #include "transport.h"
  39 #include "mux.h"
  40
  41 #define ERREQFLUSH      1
  42 #define SCHED_TIMEOUT   10
  43 #define MAXPOLLWADDR    2
  44
  45 enum {
  46         Rworksched = 1,         /* read work scheduled or running */
  47         Rpending = 2,           /* can read */
  48         Wworksched = 4,         /* write work scheduled or running */
  49         Wpending = 8,           /* can write */
  50 };
  51
  52 enum {
  53         None,
  54         Flushing,
  55         Flushed,
  56 };
  57
  58 struct v9fs_mux_poll_task;
  59
  60 struct v9fs_req {
  61         spinlock_t lock;
  62         int tag;
  63         struct v9fs_fcall *tcall;
  64         struct v9fs_fcall *rcall;
  65         int err;
  66         v9fs_mux_req_callback cb;
  67         void *cba;
  68         int flush;
  69         struct list_head req_list;
  70 };
  71
  72 struct v9fs_mux_data {
  73         spinlock_t lock;
  74         struct list_head mux_list;
  75         struct v9fs_mux_poll_task *poll_task;
  76         int msize;
  77         unsigned char *extended;
  78         struct v9fs_transport *trans;
  79         struct v9fs_idpool tagpool;
  80         int err;
  81         wait_queue_head_t equeue;
  82         struct list_head req_list;
  83         struct list_head unsent_req_list;
  84         struct v9fs_fcall *rcall;
  85         int rpos;
  86         char *rbuf;
  87         int wpos;
  88         int wsize;
  89         char *wbuf;
  90         wait_queue_t poll_wait[MAXPOLLWADDR];
  91         wait_queue_head_t *poll_waddr[MAXPOLLWADDR];
  92         poll_table pt;
  93         struct work_struct rq;
  94         struct work_struct wq;
  95         unsigned long wsched;
  96 };
  97
  98 struct v9fs_mux_poll_task {
  99         struct task_struct *task;
 100         struct list_head mux_list;
 101         int muxnum;
 102 };
 103
 104 struct v9fs_mux_rpc {
 105         struct v9fs_mux_data *m;
 106         int err;
 107         struct v9fs_fcall *tcall;
 108         struct v9fs_fcall *rcall;
 109         wait_queue_head_t wqueue;
 110 };
 111
 112 static int v9fs_poll_proc(void *);
 113 static void v9fs_read_work(struct work_struct *work);
 114 static void v9fs_write_work(struct work_struct *work);
 115 static void v9fs_pollwait(struct file *filp, wait_queue_head_t * wait_address,
 116                           poll_table * p);
 117 static u16 v9fs_mux_get_tag(struct v9fs_mux_data *);
 118 static void v9fs_mux_put_tag(struct v9fs_mux_data *, u16);
 119
 120 static DEFINE_MUTEX(v9fs_mux_task_lock);
 121 static struct workqueue_struct *v9fs_mux_wq;
 122
 123 static int v9fs_mux_num;
 124 static int v9fs_mux_poll_task_num;
 125 static struct v9fs_mux_poll_task v9fs_mux_poll_tasks[100];
 126
 127 int v9fs_mux_global_init(void)
 128 {
 129         int i;
 130
 131         for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++)
 132                 v9fs_mux_poll_tasks[i].task = NULL;
 133
 134         v9fs_mux_wq = create_workqueue("v9fs");
 135         if (!v9fs_mux_wq)
 136                 return -ENOMEM;
 137
 138         return 0;
 139 }
 140
 141 void v9fs_mux_global_exit(void)
 142 {
 143         destroy_workqueue(v9fs_mux_wq);
 144 }
 145
 146 /**
 147  * v9fs_mux_calc_poll_procs - calculates the number of polling procs
 148  * based on the number of mounted v9fs filesystems.
 149  *
 150  * The current implementation returns sqrt of the number of mounts.
 151  */
 152 static int v9fs_mux_calc_poll_procs(int muxnum)
 153 {
 154         int n;
 155
 156         if (v9fs_mux_poll_task_num)
 157                 n = muxnum / v9fs_mux_poll_task_num +
 158                     (muxnum % v9fs_mux_poll_task_num ? 1 : 0);
 159         else
 160                 n = 1;
 161
 162         if (n > ARRAY_SIZE(v9fs_mux_poll_tasks))
 163                 n = ARRAY_SIZE(v9fs_mux_poll_tasks);
 164
 165         return n;
 166 }
 167
 168 static int v9fs_mux_poll_start(struct v9fs_mux_data *m)
 169 {
 170         int i, n;
 171         struct v9fs_mux_poll_task *vpt, *vptlast;
 172         struct task_struct *pproc;
 173
 174         dprintk(DEBUG_MUX, "mux %p muxnum %d procnum %d\n", m, v9fs_mux_num,
 175                 v9fs_mux_poll_task_num);
 176         mutex_lock(&v9fs_mux_task_lock);
 177
 178         n = v9fs_mux_calc_poll_procs(v9fs_mux_num + 1);
 179         if (n > v9fs_mux_poll_task_num) {
 180                 for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++) {
 181                         if (v9fs_mux_poll_tasks[i].task == NULL) {
 182                                 vpt = &v9fs_mux_poll_tasks[i];
 183                                 dprintk(DEBUG_MUX, "create proc %p\n", vpt);
 184                                 pproc = kthread_create(v9fs_poll_proc, vpt,
 185                                                    "v9fs-poll");
 186
 187                                 if (!IS_ERR(pproc)) {
 188                                         vpt->task = pproc;
 189                                         INIT_LIST_HEAD(&vpt->mux_list);
 190                                         vpt->muxnum = 0;
 191                                         v9fs_mux_poll_task_num++;
 192                                         wake_up_process(vpt->task);
 193                                 }
 194                                 break;
 195                         }
 196                 }
 197
 198                 if (i >= ARRAY_SIZE(v9fs_mux_poll_tasks))
 199                         dprintk(DEBUG_ERROR, "warning: no free poll slots\n");
 200         }
 201
 202         n = (v9fs_mux_num + 1) / v9fs_mux_poll_task_num +
 203             ((v9fs_mux_num + 1) % v9fs_mux_poll_task_num ? 1 : 0);
 204
 205         vptlast = NULL;
 206         for (i = 0; i < ARRAY_SIZE(v9fs_mux_poll_tasks); i++) {
 207                 vpt = &v9fs_mux_poll_tasks[i];
 208                 if (vpt->task != NULL) {
 209                         vptlast = vpt;
 210                         if (vpt->muxnum < n) {
 211                                 dprintk(DEBUG_MUX, "put in proc %d\n", i);
 212                                 list_add(&m->mux_list, &vpt->mux_list);
 213                                 vpt->muxnum++;
 214                                 m->poll_task = vpt;
 215                                 memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 216                                 init_poll_funcptr(&m->pt, v9fs_pollwait);
 217                                 break;
 218                         }
 219                 }
 220         }
 221
 222         if (i >= ARRAY_SIZE(v9fs_mux_poll_tasks)) {
 223                 if (vptlast == NULL)
 224                         return -ENOMEM;
 225
 226                 dprintk(DEBUG_MUX, "put in proc %d\n", i);
 227                 list_add(&m->mux_list, &vptlast->mux_list);
 228                 vptlast->muxnum++;
 229                 m->poll_task = vptlast;
 230                 memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 231                 init_poll_funcptr(&m->pt, v9fs_pollwait);
 232         }
 233
 234         v9fs_mux_num++;
 235         mutex_unlock(&v9fs_mux_task_lock);
 236
 237         return 0;
 238 }
 239
 240 static void v9fs_mux_poll_stop(struct v9fs_mux_data *m)
 241 {
 242         int i;
 243         struct v9fs_mux_poll_task *vpt;
 244
 245         mutex_lock(&v9fs_mux_task_lock);
 246         vpt = m->poll_task;
 247         list_del(&m->mux_list);
 248         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
 249                 if (m->poll_waddr[i] != NULL) {
 250                         remove_wait_queue(m->poll_waddr[i], &m->poll_wait[i]);
 251                         m->poll_waddr[i] = NULL;
 252                 }
 253         }
 254         vpt->muxnum--;
 255         if (!vpt->muxnum) {
 256                 dprintk(DEBUG_MUX, "destroy proc %p\n", vpt);
 257                 send_sig(SIGKILL, vpt->task, 1);
 258                 vpt->task = NULL;
 259                 v9fs_mux_poll_task_num--;
 260         }
 261         v9fs_mux_num--;
 262         mutex_unlock(&v9fs_mux_task_lock);
 263 }
 264
 265 /**
 266  * v9fs_mux_init - allocate and initialize the per-session mux data
 267  * Creates the polling task if this is the first session.
 268  *
 269  * @trans - transport structure
 270  * @msize - maximum message size
 271  * @extended - pointer to the extended flag
 272  */
 273 struct v9fs_mux_data *v9fs_mux_init(struct v9fs_transport *trans, int msize,
 274                                     unsigned char *extended)
 275 {
 276         int i, n;
 277         struct v9fs_mux_data *m, *mtmp;
 278
 279         dprintk(DEBUG_MUX, "transport %p msize %d\n", trans, msize);
 280         m = kmalloc(sizeof(struct v9fs_mux_data), GFP_KERNEL);
 281         if (!m)
 282                 return ERR_PTR(-ENOMEM);
 283
 284         spin_lock_init(&m->lock);
 285         INIT_LIST_HEAD(&m->mux_list);
 286         m->msize = msize;
 287         m->extended = extended;
 288         m->trans = trans;
 289         idr_init(&m->tagpool.pool);
 290         init_MUTEX(&m->tagpool.lock);
 291         m->err = 0;
 292         init_waitqueue_head(&m->equeue);
 293         INIT_LIST_HEAD(&m->req_list);
 294         INIT_LIST_HEAD(&m->unsent_req_list);
 295         m->rcall = NULL;
 296         m->rpos = 0;
 297         m->rbuf = NULL;
 298         m->wpos = m->wsize = 0;
 299         m->wbuf = NULL;
 300         INIT_WORK(&m->rq, v9fs_read_work);
 301         INIT_WORK(&m->wq, v9fs_write_work);
 302         m->wsched = 0;
 303         memset(&m->poll_waddr, 0, sizeof(m->poll_waddr));
 304         m->poll_task = NULL;
 305         n = v9fs_mux_poll_start(m);
 306         if (n)
 307                 return ERR_PTR(n);
 308
 309         n = trans->poll(trans, &m->pt);
 310         if (n & POLLIN) {
 311                 dprintk(DEBUG_MUX, "mux %p can read\n", m);
 312                 set_bit(Rpending, &m->wsched);
 313         }
 314
 315         if (n & POLLOUT) {
 316                 dprintk(DEBUG_MUX, "mux %p can write\n", m);
 317                 set_bit(Wpending, &m->wsched);
 318         }
 319
 320         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++) {
 321                 if (IS_ERR(m->poll_waddr[i])) {
 322                         v9fs_mux_poll_stop(m);
 323                         mtmp = (void *)m->poll_waddr;   /* the error code */
 324                         kfree(m);
 325                         m = mtmp;
 326                         break;
 327                 }
 328         }
 329
 330         return m;
 331 }
 332
 333 /**
 334  * v9fs_mux_destroy - cancels all pending requests and frees mux resources
 335  */
 336 void v9fs_mux_destroy(struct v9fs_mux_data *m)
 337 {
 338         dprintk(DEBUG_MUX, "mux %p prev %p next %p\n", m,
 339                 m->mux_list.prev, m->mux_list.next);
 340         v9fs_mux_cancel(m, -ECONNRESET);
 341
 342         if (!list_empty(&m->req_list)) {
 343                 /* wait until all processes waiting on this session exit */
 344                 dprintk(DEBUG_MUX, "mux %p waiting for empty request queue\n",
 345                         m);
 346                 wait_event_timeout(m->equeue, (list_empty(&m->req_list)), 5000);
 347                 dprintk(DEBUG_MUX, "mux %p request queue empty: %d\n", m,
 348                         list_empty(&m->req_list));
 349         }
 350
 351         v9fs_mux_poll_stop(m);
 352         m->trans = NULL;
 353
 354         kfree(m);
 355 }
 356
 357 /**
 358  * v9fs_pollwait - called by files poll operation to add v9fs-poll task
 359  *      to files wait queue
 360  */
 361 static void
 362 v9fs_pollwait(struct file *filp, wait_queue_head_t * wait_address,
 363               poll_table * p)
 364 {
 365         int i;
 366         struct v9fs_mux_data *m;
 367
 368         m = container_of(p, struct v9fs_mux_data, pt);
 369         for(i = 0; i < ARRAY_SIZE(m->poll_waddr); i++)
 370                 if (m->poll_waddr[i] == NULL)
 371                         break;
 372
 373         if (i >= ARRAY_SIZE(m->poll_waddr)) {
 374                 dprintk(DEBUG_ERROR, "not enough wait_address slots\n");
 375                 return;
 376         }
 377
 378         m->poll_waddr[i] = wait_address;
 379
 380         if (!wait_address) {
 381                 dprintk(DEBUG_ERROR, "no wait_address\n");
 382                 m->poll_waddr[i] = ERR_PTR(-EIO);
 383                 return;
 384         }
 385
 386         init_waitqueue_entry(&m->poll_wait[i], m->poll_task->task);
 387         add_wait_queue(wait_address, &m->poll_wait[i]);
 388 }
 389
 390 /**
 391  * v9fs_poll_mux - polls a mux and schedules read or write works if necessary
 392  */
 393 static void v9fs_poll_mux(struct v9fs_mux_data *m)
 394 {
 395         int n;
 396
 397         if (m->err < 0)
 398                 return;
 399
 400         n = m->trans->poll(m->trans, NULL);
 401         if (n < 0 || n & (POLLERR | POLLHUP | POLLNVAL)) {
 402                 dprintk(DEBUG_MUX, "error mux %p err %d\n", m, n);
 403                 if (n >= 0)
 404                         n = -ECONNRESET;
 405                 v9fs_mux_cancel(m, n);
 406         }
 407
 408         if (n & POLLIN) {
 409                 set_bit(Rpending, &m->wsched);
 410                 dprintk(DEBUG_MUX, "mux %p can read\n", m);
 411                 if (!test_and_set_bit(Rworksched, &m->wsched)) {
 412                         dprintk(DEBUG_MUX, "schedule read work mux %p\n", m);
 413                         queue_work(v9fs_mux_wq, &m->rq);
 414                 }
 415         }
 416
 417         if (n & POLLOUT) {
 418                 set_bit(Wpending, &m->wsched);
 419                 dprintk(DEBUG_MUX, "mux %p can write\n", m);
 420                 if ((m->wsize || !list_empty(&m->unsent_req_list))
 421                     && !test_and_set_bit(Wworksched, &m->wsched)) {
 422                         dprintk(DEBUG_MUX, "schedule write work mux %p\n", m);
 423                         queue_work(v9fs_mux_wq, &m->wq);
 424                 }
 425         }
 426 }
 427
 428 /**
 429  * v9fs_poll_proc - polls all v9fs transports for new events and queues
 430  *      the appropriate work to the work queue
 431  */
 432 static int v9fs_poll_proc(void *a)
 433 {
 434         struct v9fs_mux_data *m, *mtmp;
 435         struct v9fs_mux_poll_task *vpt;
 436
 437         vpt = a;
 438         dprintk(DEBUG_MUX, "start %p %p\n", current, vpt);
 439         allow_signal(SIGKILL);
 440         while (!kthread_should_stop()) {
 441                 set_current_state(TASK_INTERRUPTIBLE);
 442                 if (signal_pending(current))
 443                         break;
 444
 445                 list_for_each_entry_safe(m, mtmp, &vpt->mux_list, mux_list) {
 446                         v9fs_poll_mux(m);
 447                 }
 448
 449                 dprintk(DEBUG_MUX, "sleeping...\n");
 450                 schedule_timeout(SCHED_TIMEOUT * HZ);
 451         }
 452
 453         __set_current_state(TASK_RUNNING);
 454         dprintk(DEBUG_MUX, "finish\n");
 455         return 0;
 456 }
 457
 458 /**
 459  * v9fs_write_work - called when a transport can send some data
 460  */
 461 static void v9fs_write_work(struct work_struct *work)
 462 {
 463         int n, err;
 464         struct v9fs_mux_data *m;
 465         struct v9fs_req *req;
 466
 467         m = container_of(work, struct v9fs_mux_data, wq);
 468
 469         if (m->err < 0) {
 470                 clear_bit(Wworksched, &m->wsched);
 471                 return;
 472         }
 473
 474         if (!m->wsize) {
 475                 if (list_empty(&m->unsent_req_list)) {
 476                         clear_bit(Wworksched, &m->wsched);
 477                         return;
 478                 }
 479
 480                 spin_lock(&m->lock);
 481 again:
 482                 req = list_entry(m->unsent_req_list.next, struct v9fs_req,
 483                                req_list);
 484                 list_move_tail(&req->req_list, &m->req_list);
 485                 if (req->err == ERREQFLUSH)
 486                         goto again;
 487
 488                 m->wbuf = req->tcall->sdata;
 489                 m->wsize = req->tcall->size;
 490                 m->wpos = 0;
 491                 dump_data(m->wbuf, m->wsize);
 492                 spin_unlock(&m->lock);
 493         }
 494
 495         dprintk(DEBUG_MUX, "mux %p pos %d size %d\n", m, m->wpos, m->wsize);
 496         clear_bit(Wpending, &m->wsched);
 497         err = m->trans->write(m->trans, m->wbuf + m->wpos, m->wsize - m->wpos);
 498         dprintk(DEBUG_MUX, "mux %p sent %d bytes\n", m, err);
 499         if (err == -EAGAIN) {
 500                 clear_bit(Wworksched, &m->wsched);
 501                 return;
 502         }
 503
 504         if (err <= 0)
 505                 goto error;
 506
 507         m->wpos += err;
 508         if (m->wpos == m->wsize)
 509                 m->wpos = m->wsize = 0;
 510
 511         if (m->wsize == 0 && !list_empty(&m->unsent_req_list)) {
 512                 if (test_and_clear_bit(Wpending, &m->wsched))
 513                         n = POLLOUT;
 514                 else
 515                         n = m->trans->poll(m->trans, NULL);
 516
 517                 if (n & POLLOUT) {
 518                         dprintk(DEBUG_MUX, "schedule write work mux %p\n", m);
 519                         queue_work(v9fs_mux_wq, &m->wq);
 520                 } else
 521                         clear_bit(Wworksched, &m->wsched);
 522         } else
 523                 clear_bit(Wworksched, &m->wsched);
 524
 525         return;
 526
 527       error:
 528         v9fs_mux_cancel(m, err);
 529         clear_bit(Wworksched, &m->wsched);
 530 }
 531
 532 static void process_request(struct v9fs_mux_data *m, struct v9fs_req *req)
 533 {
 534         int ecode;
 535         struct v9fs_str *ename;
 536
 537         if (!req->err && req->rcall->id == RERROR) {
 538                 ecode = req->rcall->params.rerror.errno;
 539                 ename = &req->rcall->params.rerror.error;
 540
 541                 dprintk(DEBUG_MUX, "Rerror %.*s\n", ename->len, ename->str);
 542
 543                 if (*m->extended)
 544                         req->err = -ecode;
 545
 546                 if (!req->err) {
 547                         req->err = v9fs_errstr2errno(ename->str, ename->len);
 548
 549                         if (!req->err) {        /* string match failed */
 550                                 PRINT_FCALL_ERROR("unknown error", req->rcall);
 551                         }
 552
 553                         if (!req->err)
 554                                 req->err = -ESERVERFAULT;
 555                 }
 556         } else if (req->tcall && req->rcall->id != req->tcall->id + 1) {
 557                 dprintk(DEBUG_ERROR, "fcall mismatch: expected %d, got %d\n",
 558                         req->tcall->id + 1, req->rcall->id);
 559                 if (!req->err)
 560                         req->err = -EIO;
 561         }
 562 }
 563
 564 /**
 565  * v9fs_read_work - called when there is some data to be read from a transport
 566  */
 567 static void v9fs_read_work(struct work_struct *work)
 568 {
 569         int n, err;
 570         struct v9fs_mux_data *m;
 571         struct v9fs_req *req, *rptr, *rreq;
 572         struct v9fs_fcall *rcall;
 573         char *rbuf;
 574
 575         m = container_of(work, struct v9fs_mux_data, rq);
 576
 577         if (m->err < 0)
 578                 return;
 579
 580         rcall = NULL;
 581         dprintk(DEBUG_MUX, "start mux %p pos %d\n", m, m->rpos);
 582
 583         if (!m->rcall) {
 584                 m->rcall =
 585                     kmalloc(sizeof(struct v9fs_fcall) + m->msize, GFP_KERNEL);
 586                 if (!m->rcall) {
 587                         err = -ENOMEM;
 588                         goto error;
 589                 }
 590
 591                 m->rbuf = (char *)m->rcall + sizeof(struct v9fs_fcall);
 592                 m->rpos = 0;
 593         }
 594
 595         clear_bit(Rpending, &m->wsched);
 596         err = m->trans->read(m->trans, m->rbuf + m->rpos, m->msize - m->rpos);
 597         dprintk(DEBUG_MUX, "mux %p got %d bytes\n", m, err);
 598         if (err == -EAGAIN) {
 599                 clear_bit(Rworksched, &m->wsched);
 600                 return;
 601         }
 602
 603         if (err <= 0)
 604                 goto error;
 605
 606         m->rpos += err;
 607         while (m->rpos > 4) {
 608                 n = le32_to_cpu(*(__le32 *) m->rbuf);
 609                 if (n >= m->msize) {
 610                         dprintk(DEBUG_ERROR,
 611                                 "requested packet size too big: %d\n", n);
 612                         err = -EIO;
 613                         goto error;
 614                 }
 615
 616                 if (m->rpos < n)
 617                         break;
 618
 619                 dump_data(m->rbuf, n);
 620                 err =
 621                     v9fs_deserialize_fcall(m->rbuf, n, m->rcall, *m->extended);
 622                 if (err < 0) {
 623                         goto error;
 624                 }
 625
 626                 if ((v9fs_debug_level&DEBUG_FCALL) == DEBUG_FCALL) {
 627                         char buf[150];
 628
 629                         v9fs_printfcall(buf, sizeof(buf), m->rcall,
 630                                 *m->extended);
 631                         printk(KERN_NOTICE ">>> %p %s\n", m, buf);
 632                 }
 633
 634                 rcall = m->rcall;
 635                 rbuf = m->rbuf;
 636                 if (m->rpos > n) {
 637                         m->rcall = kmalloc(sizeof(struct v9fs_fcall) + m->msize,
 638                                            GFP_KERNEL);
 639                         if (!m->rcall) {
 640                                 err = -ENOMEM;
 641                                 goto error;
 642                         }
 643
 644                         m->rbuf = (char *)m->rcall + sizeof(struct v9fs_fcall);
 645                         memmove(m->rbuf, rbuf + n, m->rpos - n);
 646                         m->rpos -= n;
 647                 } else {
 648                         m->rcall = NULL;
 649                         m->rbuf = NULL;
 650                         m->rpos = 0;
 651                 }
 652
 653                 dprintk(DEBUG_MUX, "mux %p fcall id %d tag %d\n", m, rcall->id,
 654                         rcall->tag);
 655
 656                 req = NULL;
 657                 spin_lock(&m->lock);
 658                 list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
 659                         if (rreq->tag == rcall->tag) {
 660                                 req = rreq;
 661                                 if (req->flush != Flushing)
 662                                         list_del(&req->req_list);
 663                                 break;
 664                         }
 665                 }
 666                 spin_unlock(&m->lock);
 667
 668                 if (req) {
 669                         req->rcall = rcall;
 670                         process_request(m, req);
 671
 672                         if (req->flush != Flushing) {
 673                                 if (req->cb)
 674                                         (*req->cb) (req, req->cba);
 675                                 else
 676                                         kfree(req->rcall);
 677
 678                                 wake_up(&m->equeue);
 679                         }
 680                 } else {
 681                         if (err >= 0 && rcall->id != RFLUSH)
 682                                 dprintk(DEBUG_ERROR,
 683                                         "unexpected response mux %p id %d tag %d\n",
 684                                         m, rcall->id, rcall->tag);
 685                         kfree(rcall);
 686                 }
 687         }
 688
 689         if (!list_empty(&m->req_list)) {
 690                 if (test_and_clear_bit(Rpending, &m->wsched))
 691                         n = POLLIN;
 692                 else
 693                         n = m->trans->poll(m->trans, NULL);
 694
 695                 if (n & POLLIN) {
 696                         dprintk(DEBUG_MUX, "schedule read work mux %p\n", m);
 697                         queue_work(v9fs_mux_wq, &m->rq);
 698                 } else
 699                         clear_bit(Rworksched, &m->wsched);
 700         } else
 701                 clear_bit(Rworksched, &m->wsched);
 702
 703         return;
 704
 705       error:
 706         v9fs_mux_cancel(m, err);
 707         clear_bit(Rworksched, &m->wsched);
 708 }
 709
 710 /**
 711  * v9fs_send_request - send 9P request
 712  * The function can sleep until the request is scheduled for sending.
 713  * The function can be interrupted. Return from the function is not
 714  * a guarantee that the request is sent successfully. Can return errors
 715  * that can be retrieved by PTR_ERR macros.
 716  *
 717  * @m: mux data
 718  * @tc: request to be sent
 719  * @cb: callback function to call when response is received
 720  * @cba: parameter to pass to the callback function
 721  */
 722 static struct v9fs_req *v9fs_send_request(struct v9fs_mux_data *m,
 723                                           struct v9fs_fcall *tc,
 724                                           v9fs_mux_req_callback cb, void *cba)
 725 {
 726         int n;
 727         struct v9fs_req *req;
 728
 729         dprintk(DEBUG_MUX, "mux %p task %p tcall %p id %d\n", m, current,
 730                 tc, tc->id);
 731         if (m->err < 0)
 732                 return ERR_PTR(m->err);
 733
 734         req = kmalloc(sizeof(struct v9fs_req), GFP_KERNEL);
 735         if (!req)
 736                 return ERR_PTR(-ENOMEM);
 737
 738         if (tc->id == TVERSION)
 739                 n = V9FS_NOTAG;
 740         else
 741                 n = v9fs_mux_get_tag(m);
 742
 743         if (n < 0)
 744                 return ERR_PTR(-ENOMEM);
 745
 746         v9fs_set_tag(tc, n);
 747         if ((v9fs_debug_level&DEBUG_FCALL) == DEBUG_FCALL) {
 748                 char buf[150];
 749
 750                 v9fs_printfcall(buf, sizeof(buf), tc, *m->extended);
 751                 printk(KERN_NOTICE "<<< %p %s\n", m, buf);
 752         }
 753
 754         spin_lock_init(&req->lock);
 755         req->tag = n;
 756         req->tcall = tc;
 757         req->rcall = NULL;
 758         req->err = 0;
 759         req->cb = cb;
 760         req->cba = cba;
 761         req->flush = None;
 762
 763         spin_lock(&m->lock);
 764         list_add_tail(&req->req_list, &m->unsent_req_list);
 765         spin_unlock(&m->lock);
 766
 767         if (test_and_clear_bit(Wpending, &m->wsched))
 768                 n = POLLOUT;
 769         else
 770                 n = m->trans->poll(m->trans, NULL);
 771
 772         if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
 773                 queue_work(v9fs_mux_wq, &m->wq);
 774
 775         return req;
 776 }
 777
 778 static void v9fs_mux_free_request(struct v9fs_mux_data *m, struct v9fs_req *req)
 779 {
 780         v9fs_mux_put_tag(m, req->tag);
 781         kfree(req);
 782 }
 783
 784 static void v9fs_mux_flush_cb(struct v9fs_req *freq, void *a)
 785 {
 786         v9fs_mux_req_callback cb;
 787         int tag;
 788         struct v9fs_mux_data *m;
 789         struct v9fs_req *req, *rreq, *rptr;
 790
 791         m = a;
 792         dprintk(DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m,
 793                 freq->tcall, freq->rcall, freq->err,
 794                 freq->tcall->params.tflush.oldtag);
 795
 796         spin_lock(&m->lock);
 797         cb = NULL;
 798         tag = freq->tcall->params.tflush.oldtag;
 799         req = NULL;
 800         list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
 801                 if (rreq->tag == tag) {
 802                         req = rreq;
 803                         list_del(&req->req_list);
 804                         break;
 805                 }
 806         }
 807         spin_unlock(&m->lock);
 808
 809         if (req) {
 810                 spin_lock(&req->lock);
 811                 req->flush = Flushed;
 812                 spin_unlock(&req->lock);
 813
 814                 if (req->cb)
 815                         (*req->cb) (req, req->cba);
 816                 else
 817                         kfree(req->rcall);
 818
 819                 wake_up(&m->equeue);
 820         }
 821
 822         kfree(freq->tcall);
 823         kfree(freq->rcall);
 824         v9fs_mux_free_request(m, freq);
 825 }
 826
 827 static int
 828 v9fs_mux_flush_request(struct v9fs_mux_data *m, struct v9fs_req *req)
 829 {
 830         struct v9fs_fcall *fc;
 831         struct v9fs_req *rreq, *rptr;
 832
 833         dprintk(DEBUG_MUX, "mux %p req %p tag %d\n", m, req, req->tag);
 834
 835         /* if a response was received for a request, do nothing */
 836         spin_lock(&req->lock);
 837         if (req->rcall || req->err) {
 838                 spin_unlock(&req->lock);
 839                 dprintk(DEBUG_MUX, "mux %p req %p response already received\n", m, req);
 840                 return 0;
 841         }
 842
 843         req->flush = Flushing;
 844         spin_unlock(&req->lock);
 845
 846         spin_lock(&m->lock);
 847         /* if the request is not sent yet, just remove it from the list */
 848         list_for_each_entry_safe(rreq, rptr, &m->unsent_req_list, req_list) {
 849                 if (rreq->tag == req->tag) {
 850                         dprintk(DEBUG_MUX, "mux %p req %p request is not sent yet\n", m, req);
 851                         list_del(&rreq->req_list);
 852                         req->flush = Flushed;
 853                         spin_unlock(&m->lock);
 854                         if (req->cb)
 855                                 (*req->cb) (req, req->cba);
 856                         return 0;
 857                 }
 858         }
 859         spin_unlock(&m->lock);
 860
 861         clear_thread_flag(TIF_SIGPENDING);
 862         fc = v9fs_create_tflush(req->tag);
 863         v9fs_send_request(m, fc, v9fs_mux_flush_cb, m);
 864         return 1;
 865 }
 866
 867 static void
 868 v9fs_mux_rpc_cb(struct v9fs_req *req, void *a)
 869 {
 870         struct v9fs_mux_rpc *r;
 871
 872         dprintk(DEBUG_MUX, "req %p r %p\n", req, a);
 873         r = a;
 874         r->rcall = req->rcall;
 875         r->err = req->err;
 876
 877         if (req->flush!=None && !req->err)
 878                 r->err = -ERESTARTSYS;
 879
 880         wake_up(&r->wqueue);
 881 }
 882
 883 /**
 884  * v9fs_mux_rpc - sends 9P request and waits until a response is available.
 885  *      The function can be interrupted.
 886  * @m: mux data
 887  * @tc: request to be sent
 888  * @rc: pointer where a pointer to the response is stored
 889  */
 890 int
 891 v9fs_mux_rpc(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
 892              struct v9fs_fcall **rc)
 893 {
 894         int err, sigpending;
 895         unsigned long flags;
 896         struct v9fs_req *req;
 897         struct v9fs_mux_rpc r;
 898
 899         r.err = 0;
 900         r.tcall = tc;
 901         r.rcall = NULL;
 902         r.m = m;
 903         init_waitqueue_head(&r.wqueue);
 904
 905         if (rc)
 906                 *rc = NULL;
 907
 908         sigpending = 0;
 909         if (signal_pending(current)) {
 910                 sigpending = 1;
 911                 clear_thread_flag(TIF_SIGPENDING);
 912         }
 913
 914         req = v9fs_send_request(m, tc, v9fs_mux_rpc_cb, &r);
 915         if (IS_ERR(req)) {
 916                 err = PTR_ERR(req);
 917                 dprintk(DEBUG_MUX, "error %d\n", err);
 918                 return err;
 919         }
 920
 921         err = wait_event_interruptible(r.wqueue, r.rcall != NULL || r.err < 0);
 922         if (r.err < 0)
 923                 err = r.err;
 924
 925         if (err == -ERESTARTSYS && m->trans->status == Connected && m->err == 0) {
 926                 if (v9fs_mux_flush_request(m, req)) {
 927                         /* wait until we get response of the flush message */
 928                         do {
 929                                 clear_thread_flag(TIF_SIGPENDING);
 930                                 err = wait_event_interruptible(r.wqueue,
 931                                         r.rcall || r.err);
 932                         } while (!r.rcall && !r.err && err==-ERESTARTSYS &&
 933                                 m->trans->status==Connected && !m->err);
 934
 935                         err = -ERESTARTSYS;
 936                 }
 937                 sigpending = 1;
 938         }
 939
 940         if (sigpending) {
 941                 spin_lock_irqsave(&current->sighand->siglock, flags);
 942                 recalc_sigpending();
 943                 spin_unlock_irqrestore(&current->sighand->siglock, flags);
 944         }
 945
 946         if (rc)
 947                 *rc = r.rcall;
 948         else
 949                 kfree(r.rcall);
 950
 951         v9fs_mux_free_request(m, req);
 952         if (err > 0)
 953                 err = -EIO;
 954
 955         return err;
 956 }
 957
 958 #if 0
 959 /**
 960  * v9fs_mux_rpcnb - sends 9P request without waiting for response.
 961  * @m: mux data
 962  * @tc: request to be sent
 963  * @cb: callback function to be called when response arrives
 964  * @cba: value to pass to the callback function
 965  */
 966 int v9fs_mux_rpcnb(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
 967                    v9fs_mux_req_callback cb, void *a)
 968 {
 969         int err;
 970         struct v9fs_req *req;
 971
 972         req = v9fs_send_request(m, tc, cb, a);
 973         if (IS_ERR(req)) {
 974                 err = PTR_ERR(req);
 975                 dprintk(DEBUG_MUX, "error %d\n", err);
 976                 return PTR_ERR(req);
 977         }
 978
 979         dprintk(DEBUG_MUX, "mux %p tc %p tag %d\n", m, tc, req->tag);
 980         return 0;
 981 }
 982 #endif  /*  0  */
 983
 984 /**
 985  * v9fs_mux_cancel - cancel all pending requests with error
 986  * @m: mux data
 987  * @err: error code
 988  */
 989 void v9fs_mux_cancel(struct v9fs_mux_data *m, int err)
 990 {
 991         struct v9fs_req *req, *rtmp;
 992         LIST_HEAD(cancel_list);
 993
 994         dprintk(DEBUG_ERROR, "mux %p err %d\n", m, err);
 995         m->err = err;
 996         spin_lock(&m->lock);
 997         list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
 998                 list_move(&req->req_list, &cancel_list);
 999         }
1000         list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
1001                 list_move(&req->req_list, &cancel_list);
1002         }
1003         spin_unlock(&m->lock);
1004
1005         list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
1006                 list_del(&req->req_list);
1007                 if (!req->err)
1008                         req->err = err;
1009
1010                 if (req->cb)
1011                         (*req->cb) (req, req->cba);
1012                 else
1013                         kfree(req->rcall);
1014         }
1015
1016         wake_up(&m->equeue);
1017 }
1018
1019 static u16 v9fs_mux_get_tag(struct v9fs_mux_data *m)
1020 {
1021         int tag;
1022
1023         tag = v9fs_get_idpool(&m->tagpool);
1024         if (tag < 0)
1025                 return V9FS_NOTAG;
1026         else
1027                 return (u16) tag;
1028 }
1029
1030 static void v9fs_mux_put_tag(struct v9fs_mux_data *m, u16 tag)
1031 {
1032         if (tag != V9FS_NOTAG && v9fs_check_idpool(tag, &m->tagpool))
1033                 v9fs_put_idpool(tag, &m->tagpool);
1034 }