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                 send_sig(SIGKILL, vpt->task, 1);
 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         allow_signal(SIGKILL);
 442         while (!kthread_should_stop()) {
 443                 set_current_state(TASK_INTERRUPTIBLE);
 444                 if (signal_pending(current))
 445                         break;
 446
 447                 list_for_each_entry_safe(m, mtmp, &vpt->mux_list, mux_list) {
 448                         v9fs_poll_mux(m);
 449                 }
 450
 451                 dprintk(DEBUG_MUX, "sleeping...\n");
 452                 schedule_timeout(SCHED_TIMEOUT * HZ);
 453         }
 454
 455         __set_current_state(TASK_RUNNING);
 456         dprintk(DEBUG_MUX, "finish\n");
 457         return 0;
 458 }
 459
 460 /**
 461  * v9fs_write_work - called when a transport can send some data
 462  */
 463 static void v9fs_write_work(struct work_struct *work)
 464 {
 465         int n, err;
 466         struct v9fs_mux_data *m;
 467         struct v9fs_req *req;
 468
 469         m = container_of(work, struct v9fs_mux_data, wq);
 470
 471         if (m->err < 0) {
 472                 clear_bit(Wworksched, &m->wsched);
 473                 return;
 474         }
 475
 476         if (!m->wsize) {
 477                 if (list_empty(&m->unsent_req_list)) {
 478                         clear_bit(Wworksched, &m->wsched);
 479                         return;
 480                 }
 481
 482                 spin_lock(&m->lock);
 483 again:
 484                 req = list_entry(m->unsent_req_list.next, struct v9fs_req,
 485                                req_list);
 486                 list_move_tail(&req->req_list, &m->req_list);
 487                 if (req->err == ERREQFLUSH)
 488                         goto again;
 489
 490                 m->wbuf = req->tcall->sdata;
 491                 m->wsize = req->tcall->size;
 492                 m->wpos = 0;
 493                 dump_data(m->wbuf, m->wsize);
 494                 spin_unlock(&m->lock);
 495         }
 496
 497         dprintk(DEBUG_MUX, "mux %p pos %d size %d\n", m, m->wpos, m->wsize);
 498         clear_bit(Wpending, &m->wsched);
 499         err = m->trans->write(m->trans, m->wbuf + m->wpos, m->wsize - m->wpos);
 500         dprintk(DEBUG_MUX, "mux %p sent %d bytes\n", m, err);
 501         if (err == -EAGAIN) {
 502                 clear_bit(Wworksched, &m->wsched);
 503                 return;
 504         }
 505
 506         if (err <= 0)
 507                 goto error;
 508
 509         m->wpos += err;
 510         if (m->wpos == m->wsize)
 511                 m->wpos = m->wsize = 0;
 512
 513         if (m->wsize == 0 && !list_empty(&m->unsent_req_list)) {
 514                 if (test_and_clear_bit(Wpending, &m->wsched))
 515                         n = POLLOUT;
 516                 else
 517                         n = m->trans->poll(m->trans, NULL);
 518
 519                 if (n & POLLOUT) {
 520                         dprintk(DEBUG_MUX, "schedule write work mux %p\n", m);
 521                         queue_work(v9fs_mux_wq, &m->wq);
 522                 } else
 523                         clear_bit(Wworksched, &m->wsched);
 524         } else
 525                 clear_bit(Wworksched, &m->wsched);
 526
 527         return;
 528
 529       error:
 530         v9fs_mux_cancel(m, err);
 531         clear_bit(Wworksched, &m->wsched);
 532 }
 533
 534 static void process_request(struct v9fs_mux_data *m, struct v9fs_req *req)
 535 {
 536         int ecode;
 537         struct v9fs_str *ename;
 538
 539         if (!req->err && req->rcall->id == RERROR) {
 540                 ecode = req->rcall->params.rerror.errno;
 541                 ename = &req->rcall->params.rerror.error;
 542
 543                 dprintk(DEBUG_MUX, "Rerror %.*s\n", ename->len, ename->str);
 544
 545                 if (*m->extended)
 546                         req->err = -ecode;
 547
 548                 if (!req->err) {
 549                         req->err = v9fs_errstr2errno(ename->str, ename->len);
 550
 551                         if (!req->err) {        /* string match failed */
 552                                 PRINT_FCALL_ERROR("unknown error", req->rcall);
 553                         }
 554
 555                         if (!req->err)
 556                                 req->err = -ESERVERFAULT;
 557                 }
 558         } else if (req->tcall && req->rcall->id != req->tcall->id + 1) {
 559                 dprintk(DEBUG_ERROR, "fcall mismatch: expected %d, got %d\n",
 560                         req->tcall->id + 1, req->rcall->id);
 561                 if (!req->err)
 562                         req->err = -EIO;
 563         }
 564 }
 565
 566 /**
 567  * v9fs_read_work - called when there is some data to be read from a transport
 568  */
 569 static void v9fs_read_work(struct work_struct *work)
 570 {
 571         int n, err;
 572         struct v9fs_mux_data *m;
 573         struct v9fs_req *req, *rptr, *rreq;
 574         struct v9fs_fcall *rcall;
 575         char *rbuf;
 576
 577         m = container_of(work, struct v9fs_mux_data, rq);
 578
 579         if (m->err < 0)
 580                 return;
 581
 582         rcall = NULL;
 583         dprintk(DEBUG_MUX, "start mux %p pos %d\n", m, m->rpos);
 584
 585         if (!m->rcall) {
 586                 m->rcall =
 587                     kmalloc(sizeof(struct v9fs_fcall) + m->msize, GFP_KERNEL);
 588                 if (!m->rcall) {
 589                         err = -ENOMEM;
 590                         goto error;
 591                 }
 592
 593                 m->rbuf = (char *)m->rcall + sizeof(struct v9fs_fcall);
 594                 m->rpos = 0;
 595         }
 596
 597         clear_bit(Rpending, &m->wsched);
 598         err = m->trans->read(m->trans, m->rbuf + m->rpos, m->msize - m->rpos);
 599         dprintk(DEBUG_MUX, "mux %p got %d bytes\n", m, err);
 600         if (err == -EAGAIN) {
 601                 clear_bit(Rworksched, &m->wsched);
 602                 return;
 603         }
 604
 605         if (err <= 0)
 606                 goto error;
 607
 608         m->rpos += err;
 609         while (m->rpos > 4) {
 610                 n = le32_to_cpu(*(__le32 *) m->rbuf);
 611                 if (n >= m->msize) {
 612                         dprintk(DEBUG_ERROR,
 613                                 "requested packet size too big: %d\n", n);
 614                         err = -EIO;
 615                         goto error;
 616                 }
 617
 618                 if (m->rpos < n)
 619                         break;
 620
 621                 dump_data(m->rbuf, n);
 622                 err =
 623                     v9fs_deserialize_fcall(m->rbuf, n, m->rcall, *m->extended);
 624                 if (err < 0) {
 625                         goto error;
 626                 }
 627
 628                 if ((v9fs_debug_level&DEBUG_FCALL) == DEBUG_FCALL) {
 629                         char buf[150];
 630
 631                         v9fs_printfcall(buf, sizeof(buf), m->rcall,
 632                                 *m->extended);
 633                         printk(KERN_NOTICE ">>> %p %s\n", m, buf);
 634                 }
 635
 636                 rcall = m->rcall;
 637                 rbuf = m->rbuf;
 638                 if (m->rpos > n) {
 639                         m->rcall = kmalloc(sizeof(struct v9fs_fcall) + m->msize,
 640                                            GFP_KERNEL);
 641                         if (!m->rcall) {
 642                                 err = -ENOMEM;
 643                                 goto error;
 644                         }
 645
 646                         m->rbuf = (char *)m->rcall + sizeof(struct v9fs_fcall);
 647                         memmove(m->rbuf, rbuf + n, m->rpos - n);
 648                         m->rpos -= n;
 649                 } else {
 650                         m->rcall = NULL;
 651                         m->rbuf = NULL;
 652                         m->rpos = 0;
 653                 }
 654
 655                 dprintk(DEBUG_MUX, "mux %p fcall id %d tag %d\n", m, rcall->id,
 656                         rcall->tag);
 657
 658                 req = NULL;
 659                 spin_lock(&m->lock);
 660                 list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
 661                         if (rreq->tag == rcall->tag) {
 662                                 req = rreq;
 663                                 if (req->flush != Flushing)
 664                                         list_del(&req->req_list);
 665                                 break;
 666                         }
 667                 }
 668                 spin_unlock(&m->lock);
 669
 670                 if (req) {
 671                         req->rcall = rcall;
 672                         process_request(m, req);
 673
 674                         if (req->flush != Flushing) {
 675                                 if (req->cb)
 676                                         (*req->cb) (req, req->cba);
 677                                 else
 678                                         kfree(req->rcall);
 679
 680                                 wake_up(&m->equeue);
 681                         }
 682                 } else {
 683                         if (err >= 0 && rcall->id != RFLUSH)
 684                                 dprintk(DEBUG_ERROR,
 685                                         "unexpected response mux %p id %d tag %d\n",
 686                                         m, rcall->id, rcall->tag);
 687                         kfree(rcall);
 688                 }
 689         }
 690
 691         if (!list_empty(&m->req_list)) {
 692                 if (test_and_clear_bit(Rpending, &m->wsched))
 693                         n = POLLIN;
 694                 else
 695                         n = m->trans->poll(m->trans, NULL);
 696
 697                 if (n & POLLIN) {
 698                         dprintk(DEBUG_MUX, "schedule read work mux %p\n", m);
 699                         queue_work(v9fs_mux_wq, &m->rq);
 700                 } else
 701                         clear_bit(Rworksched, &m->wsched);
 702         } else
 703                 clear_bit(Rworksched, &m->wsched);
 704
 705         return;
 706
 707       error:
 708         v9fs_mux_cancel(m, err);
 709         clear_bit(Rworksched, &m->wsched);
 710 }
 711
 712 /**
 713  * v9fs_send_request - send 9P request
 714  * The function can sleep until the request is scheduled for sending.
 715  * The function can be interrupted. Return from the function is not
 716  * a guarantee that the request is sent successfully. Can return errors
 717  * that can be retrieved by PTR_ERR macros.
 718  *
 719  * @m: mux data
 720  * @tc: request to be sent
 721  * @cb: callback function to call when response is received
 722  * @cba: parameter to pass to the callback function
 723  */
 724 static struct v9fs_req *v9fs_send_request(struct v9fs_mux_data *m,
 725                                           struct v9fs_fcall *tc,
 726                                           v9fs_mux_req_callback cb, void *cba)
 727 {
 728         int n;
 729         struct v9fs_req *req;
 730
 731         dprintk(DEBUG_MUX, "mux %p task %p tcall %p id %d\n", m, current,
 732                 tc, tc->id);
 733         if (m->err < 0)
 734                 return ERR_PTR(m->err);
 735
 736         req = kmalloc(sizeof(struct v9fs_req), GFP_KERNEL);
 737         if (!req)
 738                 return ERR_PTR(-ENOMEM);
 739
 740         if (tc->id == TVERSION)
 741                 n = V9FS_NOTAG;
 742         else
 743                 n = v9fs_mux_get_tag(m);
 744
 745         if (n < 0)
 746                 return ERR_PTR(-ENOMEM);
 747
 748         v9fs_set_tag(tc, n);
 749         if ((v9fs_debug_level&DEBUG_FCALL) == DEBUG_FCALL) {
 750                 char buf[150];
 751
 752                 v9fs_printfcall(buf, sizeof(buf), tc, *m->extended);
 753                 printk(KERN_NOTICE "<<< %p %s\n", m, buf);
 754         }
 755
 756         spin_lock_init(&req->lock);
 757         req->tag = n;
 758         req->tcall = tc;
 759         req->rcall = NULL;
 760         req->err = 0;
 761         req->cb = cb;
 762         req->cba = cba;
 763         req->flush = None;
 764
 765         spin_lock(&m->lock);
 766         list_add_tail(&req->req_list, &m->unsent_req_list);
 767         spin_unlock(&m->lock);
 768
 769         if (test_and_clear_bit(Wpending, &m->wsched))
 770                 n = POLLOUT;
 771         else
 772                 n = m->trans->poll(m->trans, NULL);
 773
 774         if (n & POLLOUT && !test_and_set_bit(Wworksched, &m->wsched))
 775                 queue_work(v9fs_mux_wq, &m->wq);
 776
 777         return req;
 778 }
 779
 780 static void v9fs_mux_free_request(struct v9fs_mux_data *m, struct v9fs_req *req)
 781 {
 782         v9fs_mux_put_tag(m, req->tag);
 783         kfree(req);
 784 }
 785
 786 static void v9fs_mux_flush_cb(struct v9fs_req *freq, void *a)
 787 {
 788         v9fs_mux_req_callback cb;
 789         int tag;
 790         struct v9fs_mux_data *m;
 791         struct v9fs_req *req, *rreq, *rptr;
 792
 793         m = a;
 794         dprintk(DEBUG_MUX, "mux %p tc %p rc %p err %d oldtag %d\n", m,
 795                 freq->tcall, freq->rcall, freq->err,
 796                 freq->tcall->params.tflush.oldtag);
 797
 798         spin_lock(&m->lock);
 799         cb = NULL;
 800         tag = freq->tcall->params.tflush.oldtag;
 801         req = NULL;
 802         list_for_each_entry_safe(rreq, rptr, &m->req_list, req_list) {
 803                 if (rreq->tag == tag) {
 804                         req = rreq;
 805                         list_del(&req->req_list);
 806                         break;
 807                 }
 808         }
 809         spin_unlock(&m->lock);
 810
 811         if (req) {
 812                 spin_lock(&req->lock);
 813                 req->flush = Flushed;
 814                 spin_unlock(&req->lock);
 815
 816                 if (req->cb)
 817                         (*req->cb) (req, req->cba);
 818                 else
 819                         kfree(req->rcall);
 820
 821                 wake_up(&m->equeue);
 822         }
 823
 824         kfree(freq->tcall);
 825         kfree(freq->rcall);
 826         v9fs_mux_free_request(m, freq);
 827 }
 828
 829 static int
 830 v9fs_mux_flush_request(struct v9fs_mux_data *m, struct v9fs_req *req)
 831 {
 832         struct v9fs_fcall *fc;
 833         struct v9fs_req *rreq, *rptr;
 834
 835         dprintk(DEBUG_MUX, "mux %p req %p tag %d\n", m, req, req->tag);
 836
 837         /* if a response was received for a request, do nothing */
 838         spin_lock(&req->lock);
 839         if (req->rcall || req->err) {
 840                 spin_unlock(&req->lock);
 841                 dprintk(DEBUG_MUX, "mux %p req %p response already received\n", m, req);
 842                 return 0;
 843         }
 844
 845         req->flush = Flushing;
 846         spin_unlock(&req->lock);
 847
 848         spin_lock(&m->lock);
 849         /* if the request is not sent yet, just remove it from the list */
 850         list_for_each_entry_safe(rreq, rptr, &m->unsent_req_list, req_list) {
 851                 if (rreq->tag == req->tag) {
 852                         dprintk(DEBUG_MUX, "mux %p req %p request is not sent yet\n", m, req);
 853                         list_del(&rreq->req_list);
 854                         req->flush = Flushed;
 855                         spin_unlock(&m->lock);
 856                         if (req->cb)
 857                                 (*req->cb) (req, req->cba);
 858                         return 0;
 859                 }
 860         }
 861         spin_unlock(&m->lock);
 862
 863         clear_thread_flag(TIF_SIGPENDING);
 864         fc = v9fs_create_tflush(req->tag);
 865         v9fs_send_request(m, fc, v9fs_mux_flush_cb, m);
 866         return 1;
 867 }
 868
 869 static void
 870 v9fs_mux_rpc_cb(struct v9fs_req *req, void *a)
 871 {
 872         struct v9fs_mux_rpc *r;
 873
 874         dprintk(DEBUG_MUX, "req %p r %p\n", req, a);
 875         r = a;
 876         r->rcall = req->rcall;
 877         r->err = req->err;
 878
 879         if (req->flush!=None && !req->err)
 880                 r->err = -ERESTARTSYS;
 881
 882         wake_up(&r->wqueue);
 883 }
 884
 885 /**
 886  * v9fs_mux_rpc - sends 9P request and waits until a response is available.
 887  *      The function can be interrupted.
 888  * @m: mux data
 889  * @tc: request to be sent
 890  * @rc: pointer where a pointer to the response is stored
 891  */
 892 int
 893 v9fs_mux_rpc(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
 894              struct v9fs_fcall **rc)
 895 {
 896         int err, sigpending;
 897         unsigned long flags;
 898         struct v9fs_req *req;
 899         struct v9fs_mux_rpc r;
 900
 901         r.err = 0;
 902         r.tcall = tc;
 903         r.rcall = NULL;
 904         r.m = m;
 905         init_waitqueue_head(&r.wqueue);
 906
 907         if (rc)
 908                 *rc = NULL;
 909
 910         sigpending = 0;
 911         if (signal_pending(current)) {
 912                 sigpending = 1;
 913                 clear_thread_flag(TIF_SIGPENDING);
 914         }
 915
 916         req = v9fs_send_request(m, tc, v9fs_mux_rpc_cb, &r);
 917         if (IS_ERR(req)) {
 918                 err = PTR_ERR(req);
 919                 dprintk(DEBUG_MUX, "error %d\n", err);
 920                 return err;
 921         }
 922
 923         err = wait_event_interruptible(r.wqueue, r.rcall != NULL || r.err < 0);
 924         if (r.err < 0)
 925                 err = r.err;
 926
 927         if (err == -ERESTARTSYS && m->trans->status == Connected && m->err == 0) {
 928                 if (v9fs_mux_flush_request(m, req)) {
 929                         /* wait until we get response of the flush message */
 930                         do {
 931                                 clear_thread_flag(TIF_SIGPENDING);
 932                                 err = wait_event_interruptible(r.wqueue,
 933                                         r.rcall || r.err);
 934                         } while (!r.rcall && !r.err && err==-ERESTARTSYS &&
 935                                 m->trans->status==Connected && !m->err);
 936
 937                         err = -ERESTARTSYS;
 938                 }
 939                 sigpending = 1;
 940         }
 941
 942         if (sigpending) {
 943                 spin_lock_irqsave(&current->sighand->siglock, flags);
 944                 recalc_sigpending();
 945                 spin_unlock_irqrestore(&current->sighand->siglock, flags);
 946         }
 947
 948         if (rc)
 949                 *rc = r.rcall;
 950         else
 951                 kfree(r.rcall);
 952
 953         v9fs_mux_free_request(m, req);
 954         if (err > 0)
 955                 err = -EIO;
 956
 957         return err;
 958 }
 959
 960 #if 0
 961 /**
 962  * v9fs_mux_rpcnb - sends 9P request without waiting for response.
 963  * @m: mux data
 964  * @tc: request to be sent
 965  * @cb: callback function to be called when response arrives
 966  * @cba: value to pass to the callback function
 967  */
 968 int v9fs_mux_rpcnb(struct v9fs_mux_data *m, struct v9fs_fcall *tc,
 969                    v9fs_mux_req_callback cb, void *a)
 970 {
 971         int err;
 972         struct v9fs_req *req;
 973
 974         req = v9fs_send_request(m, tc, cb, a);
 975         if (IS_ERR(req)) {
 976                 err = PTR_ERR(req);
 977                 dprintk(DEBUG_MUX, "error %d\n", err);
 978                 return PTR_ERR(req);
 979         }
 980
 981         dprintk(DEBUG_MUX, "mux %p tc %p tag %d\n", m, tc, req->tag);
 982         return 0;
 983 }
 984 #endif  /*  0  */
 985
 986 /**
 987  * v9fs_mux_cancel - cancel all pending requests with error
 988  * @m: mux data
 989  * @err: error code
 990  */
 991 void v9fs_mux_cancel(struct v9fs_mux_data *m, int err)
 992 {
 993         struct v9fs_req *req, *rtmp;
 994         LIST_HEAD(cancel_list);
 995
 996         dprintk(DEBUG_ERROR, "mux %p err %d\n", m, err);
 997         m->err = err;
 998         spin_lock(&m->lock);
 999         list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
1000                 list_move(&req->req_list, &cancel_list);
1001         }
1002         list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
1003                 list_move(&req->req_list, &cancel_list);
1004         }
1005         spin_unlock(&m->lock);
1006
1007         list_for_each_entry_safe(req, rtmp, &cancel_list, req_list) {
1008                 list_del(&req->req_list);
1009                 if (!req->err)
1010                         req->err = err;
1011
1012                 if (req->cb)
1013                         (*req->cb) (req, req->cba);
1014                 else
1015                         kfree(req->rcall);
1016         }
1017
1018         wake_up(&m->equeue);
1019 }
1020
1021 static u16 v9fs_mux_get_tag(struct v9fs_mux_data *m)
1022 {
1023         int tag;
1024
1025         tag = v9fs_get_idpool(&m->tagpool);
1026         if (tag < 0)
1027                 return V9FS_NOTAG;
1028         else
1029                 return (u16) tag;
1030 }
1031
1032 static void v9fs_mux_put_tag(struct v9fs_mux_data *m, u16 tag)
1033 {
1034         if (tag != V9FS_NOTAG && v9fs_check_idpool(tag, &m->tagpool))
1035                 v9fs_put_idpool(tag, &m->tagpool);
1036 }