release/src-rt-6.x/linux/linux-2.6/fs/dlm/user.c

   1 /*
   2  * Copyright (C) 2006-2007 Red Hat, Inc.  All rights reserved.
   3  *
   4  * This copyrighted material is made available to anyone wishing to use,
   5  * modify, copy, or redistribute it subject to the terms and conditions
   6  * of the GNU General Public License v.2.
   7  */
   8
   9 #include <linux/miscdevice.h>
  10 #include <linux/init.h>
  11 #include <linux/wait.h>
  12 #include <linux/module.h>
  13 #include <linux/file.h>
  14 #include <linux/fs.h>
  15 #include <linux/poll.h>
  16 #include <linux/signal.h>
  17 #include <linux/spinlock.h>
  18 #include <linux/dlm.h>
  19 #include <linux/dlm_device.h>
  20
  21 #include "dlm_internal.h"
  22 #include "lockspace.h"
  23 #include "lock.h"
  24 #include "lvb_table.h"
  25 #include "user.h"
  26
  27 static const char *name_prefix="dlm";
  28 static struct miscdevice ctl_device;
  29 static const struct file_operations device_fops;
  30
  31 #ifdef CONFIG_COMPAT
  32
  33 struct dlm_lock_params32 {
  34         __u8 mode;
  35         __u8 namelen;
  36         __u16 flags;
  37         __u32 lkid;
  38         __u32 parent;
  39
  40         __u32 castparam;
  41         __u32 castaddr;
  42         __u32 bastparam;
  43         __u32 bastaddr;
  44         __u32 lksb;
  45
  46         char lvb[DLM_USER_LVB_LEN];
  47         char name[0];
  48 };
  49
  50 struct dlm_write_request32 {
  51         __u32 version[3];
  52         __u8 cmd;
  53         __u8 is64bit;
  54         __u8 unused[2];
  55
  56         union  {
  57                 struct dlm_lock_params32 lock;
  58                 struct dlm_lspace_params lspace;
  59                 struct dlm_purge_params purge;
  60         } i;
  61 };
  62
  63 struct dlm_lksb32 {
  64         __u32 sb_status;
  65         __u32 sb_lkid;
  66         __u8 sb_flags;
  67         __u32 sb_lvbptr;
  68 };
  69
  70 struct dlm_lock_result32 {
  71         __u32 length;
  72         __u32 user_astaddr;
  73         __u32 user_astparam;
  74         __u32 user_lksb;
  75         struct dlm_lksb32 lksb;
  76         __u8 bast_mode;
  77         __u8 unused[3];
  78         /* Offsets may be zero if no data is present */
  79         __u32 lvb_offset;
  80 };
  81
  82 static void compat_input(struct dlm_write_request *kb,
  83                          struct dlm_write_request32 *kb32)
  84 {
  85         kb->version[0] = kb32->version[0];
  86         kb->version[1] = kb32->version[1];
  87         kb->version[2] = kb32->version[2];
  88
  89         kb->cmd = kb32->cmd;
  90         kb->is64bit = kb32->is64bit;
  91         if (kb->cmd == DLM_USER_CREATE_LOCKSPACE ||
  92             kb->cmd == DLM_USER_REMOVE_LOCKSPACE) {
  93                 kb->i.lspace.flags = kb32->i.lspace.flags;
  94                 kb->i.lspace.minor = kb32->i.lspace.minor;
  95                 strcpy(kb->i.lspace.name, kb32->i.lspace.name);
  96         } else if (kb->cmd == DLM_USER_PURGE) {
  97                 kb->i.purge.nodeid = kb32->i.purge.nodeid;
  98                 kb->i.purge.pid = kb32->i.purge.pid;
  99         } else {
 100                 kb->i.lock.mode = kb32->i.lock.mode;
 101                 kb->i.lock.namelen = kb32->i.lock.namelen;
 102                 kb->i.lock.flags = kb32->i.lock.flags;
 103                 kb->i.lock.lkid = kb32->i.lock.lkid;
 104                 kb->i.lock.parent = kb32->i.lock.parent;
 105                 kb->i.lock.castparam = (void *)(long)kb32->i.lock.castparam;
 106                 kb->i.lock.castaddr = (void *)(long)kb32->i.lock.castaddr;
 107                 kb->i.lock.bastparam = (void *)(long)kb32->i.lock.bastparam;
 108                 kb->i.lock.bastaddr = (void *)(long)kb32->i.lock.bastaddr;
 109                 kb->i.lock.lksb = (void *)(long)kb32->i.lock.lksb;
 110                 memcpy(kb->i.lock.lvb, kb32->i.lock.lvb, DLM_USER_LVB_LEN);
 111                 memcpy(kb->i.lock.name, kb32->i.lock.name, kb->i.lock.namelen);
 112         }
 113 }
 114
 115 static void compat_output(struct dlm_lock_result *res,
 116                           struct dlm_lock_result32 *res32)
 117 {
 118         res32->user_astaddr = (__u32)(long)res->user_astaddr;
 119         res32->user_astparam = (__u32)(long)res->user_astparam;
 120         res32->user_lksb = (__u32)(long)res->user_lksb;
 121         res32->bast_mode = res->bast_mode;
 122
 123         res32->lvb_offset = res->lvb_offset;
 124         res32->length = res->length;
 125
 126         res32->lksb.sb_status = res->lksb.sb_status;
 127         res32->lksb.sb_flags = res->lksb.sb_flags;
 128         res32->lksb.sb_lkid = res->lksb.sb_lkid;
 129         res32->lksb.sb_lvbptr = (__u32)(long)res->lksb.sb_lvbptr;
 130 }
 131 #endif
 132
 133 /* we could possibly check if the cancel of an orphan has resulted in the lkb
 134    being removed and then remove that lkb from the orphans list and free it */
 135
 136 void dlm_user_add_ast(struct dlm_lkb *lkb, int type)
 137 {
 138         struct dlm_ls *ls;
 139         struct dlm_user_args *ua;
 140         struct dlm_user_proc *proc;
 141         int eol = 0, ast_type;
 142
 143         if (lkb->lkb_flags & (DLM_IFL_ORPHAN | DLM_IFL_DEAD))
 144                 return;
 145
 146         ls = lkb->lkb_resource->res_ls;
 147         mutex_lock(&ls->ls_clear_proc_locks);
 148
 149         /* If ORPHAN/DEAD flag is set, it means the process is dead so an ast
 150            can't be delivered.  For ORPHAN's, dlm_clear_proc_locks() freed
 151            lkb->ua so we can't try to use it.  This second check is necessary
 152            for cases where a completion ast is received for an operation that
 153            began before clear_proc_locks did its cancel/unlock. */
 154
 155         if (lkb->lkb_flags & (DLM_IFL_ORPHAN | DLM_IFL_DEAD))
 156                 goto out;
 157
 158         DLM_ASSERT(lkb->lkb_astparam, dlm_print_lkb(lkb););
 159         ua = (struct dlm_user_args *)lkb->lkb_astparam;
 160         proc = ua->proc;
 161
 162         if (type == AST_BAST && ua->bastaddr == NULL)
 163                 goto out;
 164
 165         spin_lock(&proc->asts_spin);
 166
 167         ast_type = lkb->lkb_ast_type;
 168         lkb->lkb_ast_type |= type;
 169
 170         if (!ast_type) {
 171                 kref_get(&lkb->lkb_ref);
 172                 list_add_tail(&lkb->lkb_astqueue, &proc->asts);
 173                 wake_up_interruptible(&proc->wait);
 174         }
 175         if (type == AST_COMP && (ast_type & AST_COMP))
 176                 log_debug(ls, "ast overlap %x status %x %x",
 177                           lkb->lkb_id, ua->lksb.sb_status, lkb->lkb_flags);
 178
 179         /* Figure out if this lock is at the end of its life and no longer
 180            available for the application to use.  The lkb still exists until
 181            the final ast is read.  A lock becomes EOL in three situations:
 182              1. a noqueue request fails with EAGAIN
 183              2. an unlock completes with EUNLOCK
 184              3. a cancel of a waiting request completes with ECANCEL
 185            An EOL lock needs to be removed from the process's list of locks.
 186            And we can't allow any new operation on an EOL lock.  This is
 187            not related to the lifetime of the lkb struct which is managed
 188            entirely by refcount. */
 189
 190         if (type == AST_COMP &&
 191             lkb->lkb_grmode == DLM_LOCK_IV &&
 192             ua->lksb.sb_status == -EAGAIN)
 193                 eol = 1;
 194         else if (ua->lksb.sb_status == -DLM_EUNLOCK ||
 195             (ua->lksb.sb_status == -DLM_ECANCEL &&
 196              lkb->lkb_grmode == DLM_LOCK_IV))
 197                 eol = 1;
 198         if (eol) {
 199                 lkb->lkb_ast_type &= ~AST_BAST;
 200                 lkb->lkb_flags |= DLM_IFL_ENDOFLIFE;
 201         }
 202
 203         /* We want to copy the lvb to userspace when the completion
 204            ast is read if the status is 0, the lock has an lvb and
 205            lvb_ops says we should.  We could probably have set_lvb_lock()
 206            set update_user_lvb instead and not need old_mode */
 207
 208         if ((lkb->lkb_ast_type & AST_COMP) &&
 209             (lkb->lkb_lksb->sb_status == 0) &&
 210             lkb->lkb_lksb->sb_lvbptr &&
 211             dlm_lvb_operations[ua->old_mode + 1][lkb->lkb_grmode + 1])
 212                 ua->update_user_lvb = 1;
 213         else
 214                 ua->update_user_lvb = 0;
 215
 216         spin_unlock(&proc->asts_spin);
 217
 218         if (eol) {
 219                 spin_lock(&ua->proc->locks_spin);
 220                 if (!list_empty(&lkb->lkb_ownqueue)) {
 221                         list_del_init(&lkb->lkb_ownqueue);
 222                         dlm_put_lkb(lkb);
 223                 }
 224                 spin_unlock(&ua->proc->locks_spin);
 225         }
 226  out:
 227         mutex_unlock(&ls->ls_clear_proc_locks);
 228 }
 229
 230 static int device_user_lock(struct dlm_user_proc *proc,
 231                             struct dlm_lock_params *params)
 232 {
 233         struct dlm_ls *ls;
 234         struct dlm_user_args *ua;
 235         int error = -ENOMEM;
 236
 237         ls = dlm_find_lockspace_local(proc->lockspace);
 238         if (!ls)
 239                 return -ENOENT;
 240
 241         if (!params->castaddr || !params->lksb) {
 242                 error = -EINVAL;
 243                 goto out;
 244         }
 245
 246         ua = kzalloc(sizeof(struct dlm_user_args), GFP_KERNEL);
 247         if (!ua)
 248                 goto out;
 249         ua->proc = proc;
 250         ua->user_lksb = params->lksb;
 251         ua->castparam = params->castparam;
 252         ua->castaddr = params->castaddr;
 253         ua->bastparam = params->bastparam;
 254         ua->bastaddr = params->bastaddr;
 255
 256         if (params->flags & DLM_LKF_CONVERT)
 257                 error = dlm_user_convert(ls, ua,
 258                                          params->mode, params->flags,
 259                                          params->lkid, params->lvb);
 260         else {
 261                 error = dlm_user_request(ls, ua,
 262                                          params->mode, params->flags,
 263                                          params->name, params->namelen,
 264                                          params->parent);
 265                 if (!error)
 266                         error = ua->lksb.sb_lkid;
 267         }
 268  out:
 269         dlm_put_lockspace(ls);
 270         return error;
 271 }
 272
 273 static int device_user_unlock(struct dlm_user_proc *proc,
 274                               struct dlm_lock_params *params)
 275 {
 276         struct dlm_ls *ls;
 277         struct dlm_user_args *ua;
 278         int error = -ENOMEM;
 279
 280         ls = dlm_find_lockspace_local(proc->lockspace);
 281         if (!ls)
 282                 return -ENOENT;
 283
 284         ua = kzalloc(sizeof(struct dlm_user_args), GFP_KERNEL);
 285         if (!ua)
 286                 goto out;
 287         ua->proc = proc;
 288         ua->user_lksb = params->lksb;
 289         ua->castparam = params->castparam;
 290         ua->castaddr = params->castaddr;
 291
 292         if (params->flags & DLM_LKF_CANCEL)
 293                 error = dlm_user_cancel(ls, ua, params->flags, params->lkid);
 294         else
 295                 error = dlm_user_unlock(ls, ua, params->flags, params->lkid,
 296                                         params->lvb);
 297  out:
 298         dlm_put_lockspace(ls);
 299         return error;
 300 }
 301
 302 static int create_misc_device(struct dlm_ls *ls, char *name)
 303 {
 304         int error, len;
 305
 306         error = -ENOMEM;
 307         len = strlen(name) + strlen(name_prefix) + 2;
 308         ls->ls_device.name = kzalloc(len, GFP_KERNEL);
 309         if (!ls->ls_device.name)
 310                 goto fail;
 311
 312         snprintf((char *)ls->ls_device.name, len, "%s_%s", name_prefix,
 313                  name);
 314         ls->ls_device.fops = &device_fops;
 315         ls->ls_device.minor = MISC_DYNAMIC_MINOR;
 316
 317         error = misc_register(&ls->ls_device);
 318         if (error) {
 319                 kfree(ls->ls_device.name);
 320         }
 321 fail:
 322         return error;
 323 }
 324
 325 static int device_user_purge(struct dlm_user_proc *proc,
 326                              struct dlm_purge_params *params)
 327 {
 328         struct dlm_ls *ls;
 329         int error;
 330
 331         ls = dlm_find_lockspace_local(proc->lockspace);
 332         if (!ls)
 333                 return -ENOENT;
 334
 335         error = dlm_user_purge(ls, proc, params->nodeid, params->pid);
 336
 337         dlm_put_lockspace(ls);
 338         return error;
 339 }
 340
 341 static int device_create_lockspace(struct dlm_lspace_params *params)
 342 {
 343         dlm_lockspace_t *lockspace;
 344         struct dlm_ls *ls;
 345         int error;
 346
 347         if (!capable(CAP_SYS_ADMIN))
 348                 return -EPERM;
 349
 350         error = dlm_new_lockspace(params->name, strlen(params->name),
 351                                   &lockspace, 0, DLM_USER_LVB_LEN);
 352         if (error)
 353                 return error;
 354
 355         ls = dlm_find_lockspace_local(lockspace);
 356         if (!ls)
 357                 return -ENOENT;
 358
 359         error = create_misc_device(ls, params->name);
 360         dlm_put_lockspace(ls);
 361
 362         if (error)
 363                 dlm_release_lockspace(lockspace, 0);
 364         else
 365                 error = ls->ls_device.minor;
 366
 367         return error;
 368 }
 369
 370 static int device_remove_lockspace(struct dlm_lspace_params *params)
 371 {
 372         dlm_lockspace_t *lockspace;
 373         struct dlm_ls *ls;
 374         int error, force = 0;
 375
 376         if (!capable(CAP_SYS_ADMIN))
 377                 return -EPERM;
 378
 379         ls = dlm_find_lockspace_device(params->minor);
 380         if (!ls)
 381                 return -ENOENT;
 382
 383         /* Deregister the misc device first, so we don't have
 384          * a device that's not attached to a lockspace. If
 385          * dlm_release_lockspace fails then we can recreate it
 386          */
 387         error = misc_deregister(&ls->ls_device);
 388         if (error) {
 389                 dlm_put_lockspace(ls);
 390                 goto out;
 391         }
 392         kfree(ls->ls_device.name);
 393
 394         if (params->flags & DLM_USER_LSFLG_FORCEFREE)
 395                 force = 2;
 396
 397         lockspace = ls->ls_local_handle;
 398
 399         /* dlm_release_lockspace waits for references to go to zero,
 400            so all processes will need to close their device for the ls
 401            before the release will procede */
 402
 403         dlm_put_lockspace(ls);
 404         error = dlm_release_lockspace(lockspace, force);
 405         if (error)
 406                 create_misc_device(ls, ls->ls_name);
 407  out:
 408         return error;
 409 }
 410
 411 /* Check the user's version matches ours */
 412 static int check_version(struct dlm_write_request *req)
 413 {
 414         if (req->version[0] != DLM_DEVICE_VERSION_MAJOR ||
 415             (req->version[0] == DLM_DEVICE_VERSION_MAJOR &&
 416              req->version[1] > DLM_DEVICE_VERSION_MINOR)) {
 417
 418                 printk(KERN_DEBUG "dlm: process %s (%d) version mismatch "
 419                        "user (%d.%d.%d) kernel (%d.%d.%d)\n",
 420                        current->comm,
 421                        current->pid,
 422                        req->version[0],
 423                        req->version[1],
 424                        req->version[2],
 425                        DLM_DEVICE_VERSION_MAJOR,
 426                        DLM_DEVICE_VERSION_MINOR,
 427                        DLM_DEVICE_VERSION_PATCH);
 428                 return -EINVAL;
 429         }
 430         return 0;
 431 }
 432
 433 /*
 434  * device_write
 435  *
 436  *   device_user_lock
 437  *     dlm_user_request -> request_lock
 438  *     dlm_user_convert -> convert_lock
 439  *
 440  *   device_user_unlock
 441  *     dlm_user_unlock -> unlock_lock
 442  *     dlm_user_cancel -> cancel_lock
 443  *
 444  *   device_create_lockspace
 445  *     dlm_new_lockspace
 446  *
 447  *   device_remove_lockspace
 448  *     dlm_release_lockspace
 449  */
 450
 451 /* a write to a lockspace device is a lock or unlock request, a write
 452    to the control device is to create/remove a lockspace */
 453
 454 static ssize_t device_write(struct file *file, const char __user *buf,
 455                             size_t count, loff_t *ppos)
 456 {
 457         struct dlm_user_proc *proc = file->private_data;
 458         struct dlm_write_request *kbuf;
 459         sigset_t tmpsig, allsigs;
 460         int error;
 461
 462 #ifdef CONFIG_COMPAT
 463         if (count < sizeof(struct dlm_write_request32))
 464 #else
 465         if (count < sizeof(struct dlm_write_request))
 466 #endif
 467                 return -EINVAL;
 468
 469         kbuf = kmalloc(count, GFP_KERNEL);
 470         if (!kbuf)
 471                 return -ENOMEM;
 472
 473         if (copy_from_user(kbuf, buf, count)) {
 474                 error = -EFAULT;
 475                 goto out_free;
 476         }
 477
 478         if (check_version(kbuf)) {
 479                 error = -EBADE;
 480                 goto out_free;
 481         }
 482
 483 #ifdef CONFIG_COMPAT
 484         if (!kbuf->is64bit) {
 485                 struct dlm_write_request32 *k32buf;
 486                 k32buf = (struct dlm_write_request32 *)kbuf;
 487                 kbuf = kmalloc(count + (sizeof(struct dlm_write_request) -
 488                                sizeof(struct dlm_write_request32)), GFP_KERNEL);
 489                 if (!kbuf)
 490                         return -ENOMEM;
 491
 492                 if (proc)
 493                         set_bit(DLM_PROC_FLAGS_COMPAT, &proc->flags);
 494                 compat_input(kbuf, k32buf);
 495                 kfree(k32buf);
 496         }
 497 #endif
 498
 499         /* do we really need this? can a write happen after a close? */
 500         if ((kbuf->cmd == DLM_USER_LOCK || kbuf->cmd == DLM_USER_UNLOCK) &&
 501             test_bit(DLM_PROC_FLAGS_CLOSING, &proc->flags))
 502                 return -EINVAL;
 503
 504         sigfillset(&allsigs);
 505         sigprocmask(SIG_BLOCK, &allsigs, &tmpsig);
 506
 507         error = -EINVAL;
 508
 509         switch (kbuf->cmd)
 510         {
 511         case DLM_USER_LOCK:
 512                 if (!proc) {
 513                         log_print("no locking on control device");
 514                         goto out_sig;
 515                 }
 516                 error = device_user_lock(proc, &kbuf->i.lock);
 517                 break;
 518
 519         case DLM_USER_UNLOCK:
 520                 if (!proc) {
 521                         log_print("no locking on control device");
 522                         goto out_sig;
 523                 }
 524                 error = device_user_unlock(proc, &kbuf->i.lock);
 525                 break;
 526
 527         case DLM_USER_CREATE_LOCKSPACE:
 528                 if (proc) {
 529                         log_print("create/remove only on control device");
 530                         goto out_sig;
 531                 }
 532                 error = device_create_lockspace(&kbuf->i.lspace);
 533                 break;
 534
 535         case DLM_USER_REMOVE_LOCKSPACE:
 536                 if (proc) {
 537                         log_print("create/remove only on control device");
 538                         goto out_sig;
 539                 }
 540                 error = device_remove_lockspace(&kbuf->i.lspace);
 541                 break;
 542
 543         case DLM_USER_PURGE:
 544                 if (!proc) {
 545                         log_print("no locking on control device");
 546                         goto out_sig;
 547                 }
 548                 error = device_user_purge(proc, &kbuf->i.purge);
 549                 break;
 550
 551         default:
 552                 log_print("Unknown command passed to DLM device : %d\n",
 553                           kbuf->cmd);
 554         }
 555
 556  out_sig:
 557         sigprocmask(SIG_SETMASK, &tmpsig, NULL);
 558         recalc_sigpending();
 559  out_free:
 560         kfree(kbuf);
 561         return error;
 562 }
 563
 564 /* Every process that opens the lockspace device has its own "proc" structure
 565    hanging off the open file that's used to keep track of locks owned by the
 566    process and asts that need to be delivered to the process. */
 567
 568 static int device_open(struct inode *inode, struct file *file)
 569 {
 570         struct dlm_user_proc *proc;
 571         struct dlm_ls *ls;
 572
 573         ls = dlm_find_lockspace_device(iminor(inode));
 574         if (!ls)
 575                 return -ENOENT;
 576
 577         proc = kzalloc(sizeof(struct dlm_user_proc), GFP_KERNEL);
 578         if (!proc) {
 579                 dlm_put_lockspace(ls);
 580                 return -ENOMEM;
 581         }
 582
 583         proc->lockspace = ls->ls_local_handle;
 584         INIT_LIST_HEAD(&proc->asts);
 585         INIT_LIST_HEAD(&proc->locks);
 586         INIT_LIST_HEAD(&proc->unlocking);
 587         spin_lock_init(&proc->asts_spin);
 588         spin_lock_init(&proc->locks_spin);
 589         init_waitqueue_head(&proc->wait);
 590         file->private_data = proc;
 591
 592         return 0;
 593 }
 594
 595 static int device_close(struct inode *inode, struct file *file)
 596 {
 597         struct dlm_user_proc *proc = file->private_data;
 598         struct dlm_ls *ls;
 599         sigset_t tmpsig, allsigs;
 600
 601         ls = dlm_find_lockspace_local(proc->lockspace);
 602         if (!ls)
 603                 return -ENOENT;
 604
 605         sigfillset(&allsigs);
 606         sigprocmask(SIG_BLOCK, &allsigs, &tmpsig);
 607
 608         set_bit(DLM_PROC_FLAGS_CLOSING, &proc->flags);
 609
 610         dlm_clear_proc_locks(ls, proc);
 611
 612         /* at this point no more lkb's should exist for this lockspace,
 613            so there's no chance of dlm_user_add_ast() being called and
 614            looking for lkb->ua->proc */
 615
 616         kfree(proc);
 617         file->private_data = NULL;
 618
 619         dlm_put_lockspace(ls);
 620         dlm_put_lockspace(ls);  /* for the find in device_open() */
 621
 622         /* FIXME: AUTOFREE: if this ls is no longer used do
 623            device_remove_lockspace() */
 624
 625         sigprocmask(SIG_SETMASK, &tmpsig, NULL);
 626         recalc_sigpending();
 627
 628         return 0;
 629 }
 630
 631 static int copy_result_to_user(struct dlm_user_args *ua, int compat, int type,
 632                                int bmode, char __user *buf, size_t count)
 633 {
 634 #ifdef CONFIG_COMPAT
 635         struct dlm_lock_result32 result32;
 636 #endif
 637         struct dlm_lock_result result;
 638         void *resultptr;
 639         int error=0;
 640         int len;
 641         int struct_len;
 642
 643         memset(&result, 0, sizeof(struct dlm_lock_result));
 644         memcpy(&result.lksb, &ua->lksb, sizeof(struct dlm_lksb));
 645         result.user_lksb = ua->user_lksb;
 646
 647         /* FIXME: dlm1 provides for the user's bastparam/addr to not be updated
 648            in a conversion unless the conversion is successful.  See code
 649            in dlm_user_convert() for updating ua from ua_tmp.  OpenVMS, though,
 650            notes that a new blocking AST address and parameter are set even if
 651            the conversion fails, so maybe we should just do that. */
 652
 653         if (type == AST_BAST) {
 654                 result.user_astaddr = ua->bastaddr;
 655                 result.user_astparam = ua->bastparam;
 656                 result.bast_mode = bmode;
 657         } else {
 658                 result.user_astaddr = ua->castaddr;
 659                 result.user_astparam = ua->castparam;
 660         }
 661
 662 #ifdef CONFIG_COMPAT
 663         if (compat)
 664                 len = sizeof(struct dlm_lock_result32);
 665         else
 666 #endif
 667                 len = sizeof(struct dlm_lock_result);
 668         struct_len = len;
 669
 670         /* copy lvb to userspace if there is one, it's been updated, and
 671            the user buffer has space for it */
 672
 673         if (ua->update_user_lvb && ua->lksb.sb_lvbptr &&
 674             count >= len + DLM_USER_LVB_LEN) {
 675                 if (copy_to_user(buf+len, ua->lksb.sb_lvbptr,
 676                                  DLM_USER_LVB_LEN)) {
 677                         error = -EFAULT;
 678                         goto out;
 679                 }
 680
 681                 result.lvb_offset = len;
 682                 len += DLM_USER_LVB_LEN;
 683         }
 684
 685         result.length = len;
 686         resultptr = &result;
 687 #ifdef CONFIG_COMPAT
 688         if (compat) {
 689                 compat_output(&result, &result32);
 690                 resultptr = &result32;
 691         }
 692 #endif
 693
 694         if (copy_to_user(buf, resultptr, struct_len))
 695                 error = -EFAULT;
 696         else
 697                 error = len;
 698  out:
 699         return error;
 700 }
 701
 702 /* a read returns a single ast described in a struct dlm_lock_result */
 703
 704 static ssize_t device_read(struct file *file, char __user *buf, size_t count,
 705                            loff_t *ppos)
 706 {
 707         struct dlm_user_proc *proc = file->private_data;
 708         struct dlm_lkb *lkb;
 709         struct dlm_user_args *ua;
 710         DECLARE_WAITQUEUE(wait, current);
 711         int error, type=0, bmode=0, removed = 0;
 712
 713 #ifdef CONFIG_COMPAT
 714         if (count < sizeof(struct dlm_lock_result32))
 715 #else
 716         if (count < sizeof(struct dlm_lock_result))
 717 #endif
 718                 return -EINVAL;
 719
 720         /* do we really need this? can a read happen after a close? */
 721         if (test_bit(DLM_PROC_FLAGS_CLOSING, &proc->flags))
 722                 return -EINVAL;
 723
 724         spin_lock(&proc->asts_spin);
 725         if (list_empty(&proc->asts)) {
 726                 if (file->f_flags & O_NONBLOCK) {
 727                         spin_unlock(&proc->asts_spin);
 728                         return -EAGAIN;
 729                 }
 730
 731                 add_wait_queue(&proc->wait, &wait);
 732
 733         repeat:
 734                 set_current_state(TASK_INTERRUPTIBLE);
 735                 if (list_empty(&proc->asts) && !signal_pending(current)) {
 736                         spin_unlock(&proc->asts_spin);
 737                         schedule();
 738                         spin_lock(&proc->asts_spin);
 739                         goto repeat;
 740                 }
 741                 set_current_state(TASK_RUNNING);
 742                 remove_wait_queue(&proc->wait, &wait);
 743
 744                 if (signal_pending(current)) {
 745                         spin_unlock(&proc->asts_spin);
 746                         return -ERESTARTSYS;
 747                 }
 748         }
 749
 750         if (list_empty(&proc->asts)) {
 751                 spin_unlock(&proc->asts_spin);
 752                 return -EAGAIN;
 753         }
 754
 755         /* there may be both completion and blocking asts to return for
 756            the lkb, don't remove lkb from asts list unless no asts remain */
 757
 758         lkb = list_entry(proc->asts.next, struct dlm_lkb, lkb_astqueue);
 759
 760         if (lkb->lkb_ast_type & AST_COMP) {
 761                 lkb->lkb_ast_type &= ~AST_COMP;
 762                 type = AST_COMP;
 763         } else if (lkb->lkb_ast_type & AST_BAST) {
 764                 lkb->lkb_ast_type &= ~AST_BAST;
 765                 type = AST_BAST;
 766                 bmode = lkb->lkb_bastmode;
 767         }
 768
 769         if (!lkb->lkb_ast_type) {
 770                 list_del(&lkb->lkb_astqueue);
 771                 removed = 1;
 772         }
 773         spin_unlock(&proc->asts_spin);
 774
 775         ua = (struct dlm_user_args *)lkb->lkb_astparam;
 776         error = copy_result_to_user(ua,
 777                                 test_bit(DLM_PROC_FLAGS_COMPAT, &proc->flags),
 778                                 type, bmode, buf, count);
 779
 780         /* removes reference for the proc->asts lists added by
 781            dlm_user_add_ast() and may result in the lkb being freed */
 782         if (removed)
 783                 dlm_put_lkb(lkb);
 784
 785         return error;
 786 }
 787
 788 static unsigned int device_poll(struct file *file, poll_table *wait)
 789 {
 790         struct dlm_user_proc *proc = file->private_data;
 791
 792         poll_wait(file, &proc->wait, wait);
 793
 794         spin_lock(&proc->asts_spin);
 795         if (!list_empty(&proc->asts)) {
 796                 spin_unlock(&proc->asts_spin);
 797                 return POLLIN | POLLRDNORM;
 798         }
 799         spin_unlock(&proc->asts_spin);
 800         return 0;
 801 }
 802
 803 static int ctl_device_open(struct inode *inode, struct file *file)
 804 {
 805         file->private_data = NULL;
 806         return 0;
 807 }
 808
 809 static int ctl_device_close(struct inode *inode, struct file *file)
 810 {
 811         return 0;
 812 }
 813
 814 static const struct file_operations device_fops = {
 815         .open    = device_open,
 816         .release = device_close,
 817         .read    = device_read,
 818         .write   = device_write,
 819         .poll    = device_poll,
 820         .owner   = THIS_MODULE,
 821 };
 822
 823 static const struct file_operations ctl_device_fops = {
 824         .open    = ctl_device_open,
 825         .release = ctl_device_close,
 826         .write   = device_write,
 827         .owner   = THIS_MODULE,
 828 };
 829
 830 int dlm_user_init(void)
 831 {
 832         int error;
 833
 834         ctl_device.name = "dlm-control";
 835         ctl_device.fops = &ctl_device_fops;
 836         ctl_device.minor = MISC_DYNAMIC_MINOR;
 837
 838         error = misc_register(&ctl_device);
 839         if (error)
 840                 log_print("misc_register failed for control device");
 841
 842         return error;
 843 }
 844
 845 void dlm_user_exit(void)
 846 {
 847         misc_deregister(&ctl_device);
 848 }
 849