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