fs/lockd/svclock.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * linux/fs/lockd/svclock.c
   4  *
   5  * Handling of server-side locks, mostly of the blocked variety.
   6  * This is the ugliest part of lockd because we tread on very thin ice.
   7  * GRANT and CANCEL calls may get stuck, meet in mid-flight, etc.
   8  * IMNSHO introducing the grant callback into the NLM protocol was one
   9  * of the worst ideas Sun ever had. Except maybe for the idea of doing
  10  * NFS file locking at all.
  11  *
  12  * I'm trying hard to avoid race conditions by protecting most accesses
  13  * to a file's list of blocked locks through a semaphore. The global
  14  * list of blocked locks is not protected in this fashion however.
  15  * Therefore, some functions (such as the RPC callback for the async grant
  16  * call) move blocked locks towards the head of the list *while some other
  17  * process might be traversing it*. This should not be a problem in
  18  * practice, because this will only cause functions traversing the list
  19  * to visit some blocks twice.
  20  *
  21  * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
  22  */
  23
  24 #include <linux/types.h>
  25 #include <linux/slab.h>
  26 #include <linux/errno.h>
  27 #include <linux/kernel.h>
  28 #include <linux/sched.h>
  29 #include <linux/sunrpc/clnt.h>
  30 #include <linux/sunrpc/svc_xprt.h>
  31 #include <linux/lockd/nlm.h>
  32 #include <linux/lockd/lockd.h>
  33 #include <linux/exportfs.h>
  34
  35 #define NLMDBG_FACILITY         NLMDBG_SVCLOCK
  36
  37 #ifdef CONFIG_LOCKD_V4
  38 #define nlm_deadlock    nlm4_deadlock
  39 #else
  40 #define nlm_deadlock    nlm_lck_denied
  41 #endif
  42
  43 static void nlmsvc_release_block(struct nlm_block *block);
  44 static void     nlmsvc_insert_block(struct nlm_block *block, unsigned long);
  45 static void     nlmsvc_remove_block(struct nlm_block *block);
  46
  47 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock);
  48 static void nlmsvc_freegrantargs(struct nlm_rqst *call);
  49 static const struct rpc_call_ops nlmsvc_grant_ops;
  50
  51 /*
  52  * The list of blocked locks to retry
  53  */
  54 static LIST_HEAD(nlm_blocked);
  55 static DEFINE_SPINLOCK(nlm_blocked_lock);
  56
  57 #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
  58 static const char *nlmdbg_cookie2a(const struct nlm_cookie *cookie)
  59 {
  60         /*
  61          * We can get away with a static buffer because this is only called
  62          * from lockd, which is single-threaded.
  63          */
  64         static char buf[2*NLM_MAXCOOKIELEN+1];
  65         unsigned int i, len = sizeof(buf);
  66         char *p = buf;
  67
  68         len--;  /* allow for trailing \0 */
  69         if (len < 3)
  70                 return "???";
  71         for (i = 0 ; i < cookie->len ; i++) {
  72                 if (len < 2) {
  73                         strcpy(p-3, "...");
  74                         break;
  75                 }
  76                 sprintf(p, "%02x", cookie->data[i]);
  77                 p += 2;
  78                 len -= 2;
  79         }
  80         *p = '\0';
  81
  82         return buf;
  83 }
  84 #endif
  85
  86 /*
  87  * Insert a blocked lock into the global list
  88  */
  89 static void
  90 nlmsvc_insert_block_locked(struct nlm_block *block, unsigned long when)
  91 {
  92         struct nlm_block *b;
  93         struct list_head *pos;
  94
  95         dprintk("lockd: nlmsvc_insert_block(%p, %ld)\n", block, when);
  96         if (list_empty(&block->b_list)) {
  97                 kref_get(&block->b_count);
  98         } else {
  99                 list_del_init(&block->b_list);
 100         }
 101
 102         pos = &nlm_blocked;
 103         if (when != NLM_NEVER) {
 104                 if ((when += jiffies) == NLM_NEVER)
 105                         when ++;
 106                 list_for_each(pos, &nlm_blocked) {
 107                         b = list_entry(pos, struct nlm_block, b_list);
 108                         if (time_after(b->b_when,when) || b->b_when == NLM_NEVER)
 109                                 break;
 110                 }
 111                 /* On normal exit from the loop, pos == &nlm_blocked,
 112                  * so we will be adding to the end of the list - good
 113                  */
 114         }
 115
 116         list_add_tail(&block->b_list, pos);
 117         block->b_when = when;
 118 }
 119
 120 static void nlmsvc_insert_block(struct nlm_block *block, unsigned long when)
 121 {
 122         spin_lock(&nlm_blocked_lock);
 123         nlmsvc_insert_block_locked(block, when);
 124         spin_unlock(&nlm_blocked_lock);
 125 }
 126
 127 /*
 128  * Remove a block from the global list
 129  */
 130 static inline void
 131 nlmsvc_remove_block(struct nlm_block *block)
 132 {
 133         spin_lock(&nlm_blocked_lock);
 134         if (!list_empty(&block->b_list)) {
 135                 list_del_init(&block->b_list);
 136                 spin_unlock(&nlm_blocked_lock);
 137                 nlmsvc_release_block(block);
 138                 return;
 139         }
 140         spin_unlock(&nlm_blocked_lock);
 141 }
 142
 143 /*
 144  * Find a block for a given lock
 145  */
 146 static struct nlm_block *
 147 nlmsvc_lookup_block(struct nlm_file *file, struct nlm_lock *lock)
 148 {
 149         struct nlm_block        *block;
 150         struct file_lock        *fl;
 151
 152         dprintk("lockd: nlmsvc_lookup_block f=%p pd=%d %Ld-%Ld ty=%d\n",
 153                                 file, lock->fl.c.flc_pid,
 154                                 (long long)lock->fl.fl_start,
 155                                 (long long)lock->fl.fl_end,
 156                                 lock->fl.c.flc_type);
 157         spin_lock(&nlm_blocked_lock);
 158         list_for_each_entry(block, &nlm_blocked, b_list) {
 159                 fl = &block->b_call->a_args.lock.fl;
 160                 dprintk("lockd: check f=%p pd=%d %Ld-%Ld ty=%d cookie=%s\n",
 161                                 block->b_file, fl->c.flc_pid,
 162                                 (long long)fl->fl_start,
 163                                 (long long)fl->fl_end, fl->c.flc_type,
 164                                 nlmdbg_cookie2a(&block->b_call->a_args.cookie));
 165                 if (block->b_file == file && nlm_compare_locks(fl, &lock->fl)) {
 166                         kref_get(&block->b_count);
 167                         spin_unlock(&nlm_blocked_lock);
 168                         return block;
 169                 }
 170         }
 171         spin_unlock(&nlm_blocked_lock);
 172
 173         return NULL;
 174 }
 175
 176 static inline int nlm_cookie_match(struct nlm_cookie *a, struct nlm_cookie *b)
 177 {
 178         if (a->len != b->len)
 179                 return 0;
 180         if (memcmp(a->data, b->data, a->len))
 181                 return 0;
 182         return 1;
 183 }
 184
 185 /*
 186  * Find a block with a given NLM cookie.
 187  */
 188 static inline struct nlm_block *
 189 nlmsvc_find_block(struct nlm_cookie *cookie)
 190 {
 191         struct nlm_block *block;
 192
 193         spin_lock(&nlm_blocked_lock);
 194         list_for_each_entry(block, &nlm_blocked, b_list) {
 195                 if (nlm_cookie_match(&block->b_call->a_args.cookie,cookie))
 196                         goto found;
 197         }
 198         spin_unlock(&nlm_blocked_lock);
 199
 200         return NULL;
 201
 202 found:
 203         dprintk("nlmsvc_find_block(%s): block=%p\n", nlmdbg_cookie2a(cookie), block);
 204         kref_get(&block->b_count);
 205         spin_unlock(&nlm_blocked_lock);
 206         return block;
 207 }
 208
 209 /*
 210  * Create a block and initialize it.
 211  *
 212  * Note: we explicitly set the cookie of the grant reply to that of
 213  * the blocked lock request. The spec explicitly mentions that the client
 214  * should _not_ rely on the callback containing the same cookie as the
 215  * request, but (as I found out later) that's because some implementations
 216  * do just this. Never mind the standards comittees, they support our
 217  * logging industries.
 218  *
 219  * 10 years later: I hope we can safely ignore these old and broken
 220  * clients by now. Let's fix this so we can uniquely identify an incoming
 221  * GRANTED_RES message by cookie, without having to rely on the client's IP
 222  * address. --okir
 223  */
 224 static struct nlm_block *
 225 nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host,
 226                     struct nlm_file *file, struct nlm_lock *lock,
 227                     struct nlm_cookie *cookie)
 228 {
 229         struct nlm_block        *block;
 230         struct nlm_rqst         *call = NULL;
 231
 232         call = nlm_alloc_call(host);
 233         if (call == NULL)
 234                 return NULL;
 235
 236         /* Allocate memory for block, and initialize arguments */
 237         block = kzalloc(sizeof(*block), GFP_KERNEL);
 238         if (block == NULL)
 239                 goto failed;
 240         kref_init(&block->b_count);
 241         INIT_LIST_HEAD(&block->b_list);
 242         INIT_LIST_HEAD(&block->b_flist);
 243
 244         if (!nlmsvc_setgrantargs(call, lock))
 245                 goto failed_free;
 246
 247         /* Set notifier function for VFS, and init args */
 248         call->a_args.lock.fl.c.flc_flags |= FL_SLEEP;
 249         call->a_args.lock.fl.fl_lmops = &nlmsvc_lock_operations;
 250         nlmclnt_next_cookie(&call->a_args.cookie);
 251
 252         dprintk("lockd: created block %p...\n", block);
 253
 254         /* Create and initialize the block */
 255         block->b_daemon = rqstp->rq_server;
 256         block->b_host   = host;
 257         block->b_file   = file;
 258         file->f_count++;
 259
 260         /* Add to file's list of blocks */
 261         list_add(&block->b_flist, &file->f_blocks);
 262
 263         /* Set up RPC arguments for callback */
 264         block->b_call = call;
 265         call->a_flags   = RPC_TASK_ASYNC;
 266         call->a_block = block;
 267
 268         return block;
 269
 270 failed_free:
 271         kfree(block);
 272 failed:
 273         nlmsvc_release_call(call);
 274         return NULL;
 275 }
 276
 277 /*
 278  * Delete a block.
 279  * It is the caller's responsibility to check whether the file
 280  * can be closed hereafter.
 281  */
 282 static int nlmsvc_unlink_block(struct nlm_block *block)
 283 {
 284         int status;
 285         dprintk("lockd: unlinking block %p...\n", block);
 286
 287         /* Remove block from list */
 288         status = locks_delete_block(&block->b_call->a_args.lock.fl);
 289         nlmsvc_remove_block(block);
 290         return status;
 291 }
 292
 293 static void nlmsvc_free_block(struct kref *kref)
 294 {
 295         struct nlm_block *block = container_of(kref, struct nlm_block, b_count);
 296         struct nlm_file         *file = block->b_file;
 297
 298         dprintk("lockd: freeing block %p...\n", block);
 299
 300         /* Remove block from file's list of blocks */
 301         list_del_init(&block->b_flist);
 302         mutex_unlock(&file->f_mutex);
 303
 304         nlmsvc_freegrantargs(block->b_call);
 305         nlmsvc_release_call(block->b_call);
 306         nlm_release_file(block->b_file);
 307         kfree(block);
 308 }
 309
 310 static void nlmsvc_release_block(struct nlm_block *block)
 311 {
 312         if (block != NULL)
 313                 kref_put_mutex(&block->b_count, nlmsvc_free_block, &block->b_file->f_mutex);
 314 }
 315
 316 /*
 317  * Loop over all blocks and delete blocks held by
 318  * a matching host.
 319  */
 320 void nlmsvc_traverse_blocks(struct nlm_host *host,
 321                         struct nlm_file *file,
 322                         nlm_host_match_fn_t match)
 323 {
 324         struct nlm_block *block, *next;
 325
 326 restart:
 327         mutex_lock(&file->f_mutex);
 328         spin_lock(&nlm_blocked_lock);
 329         list_for_each_entry_safe(block, next, &file->f_blocks, b_flist) {
 330                 if (!match(block->b_host, host))
 331                         continue;
 332                 /* Do not destroy blocks that are not on
 333                  * the global retry list - why? */
 334                 if (list_empty(&block->b_list))
 335                         continue;
 336                 kref_get(&block->b_count);
 337                 spin_unlock(&nlm_blocked_lock);
 338                 mutex_unlock(&file->f_mutex);
 339                 nlmsvc_unlink_block(block);
 340                 nlmsvc_release_block(block);
 341                 goto restart;
 342         }
 343         spin_unlock(&nlm_blocked_lock);
 344         mutex_unlock(&file->f_mutex);
 345 }
 346
 347 static struct nlm_lockowner *
 348 nlmsvc_get_lockowner(struct nlm_lockowner *lockowner)
 349 {
 350         refcount_inc(&lockowner->count);
 351         return lockowner;
 352 }
 353
 354 void nlmsvc_put_lockowner(struct nlm_lockowner *lockowner)
 355 {
 356         if (!refcount_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
 357                 return;
 358         list_del(&lockowner->list);
 359         spin_unlock(&lockowner->host->h_lock);
 360         nlmsvc_release_host(lockowner->host);
 361         kfree(lockowner);
 362 }
 363
 364 static struct nlm_lockowner *__nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
 365 {
 366         struct nlm_lockowner *lockowner;
 367         list_for_each_entry(lockowner, &host->h_lockowners, list) {
 368                 if (lockowner->pid != pid)
 369                         continue;
 370                 return nlmsvc_get_lockowner(lockowner);
 371         }
 372         return NULL;
 373 }
 374
 375 static struct nlm_lockowner *nlmsvc_find_lockowner(struct nlm_host *host, pid_t pid)
 376 {
 377         struct nlm_lockowner *res, *new = NULL;
 378
 379         spin_lock(&host->h_lock);
 380         res = __nlmsvc_find_lockowner(host, pid);
 381
 382         if (res == NULL) {
 383                 spin_unlock(&host->h_lock);
 384                 new = kmalloc(sizeof(*res), GFP_KERNEL);
 385                 spin_lock(&host->h_lock);
 386                 res = __nlmsvc_find_lockowner(host, pid);
 387                 if (res == NULL && new != NULL) {
 388                         res = new;
 389                         /* fs/locks.c will manage the refcount through lock_ops */
 390                         refcount_set(&new->count, 1);
 391                         new->pid = pid;
 392                         new->host = nlm_get_host(host);
 393                         list_add(&new->list, &host->h_lockowners);
 394                         new = NULL;
 395                 }
 396         }
 397
 398         spin_unlock(&host->h_lock);
 399         kfree(new);
 400         return res;
 401 }
 402
 403 void
 404 nlmsvc_release_lockowner(struct nlm_lock *lock)
 405 {
 406         if (lock->fl.c.flc_owner)
 407                 nlmsvc_put_lockowner(lock->fl.c.flc_owner);
 408 }
 409
 410 void nlmsvc_locks_init_private(struct file_lock *fl, struct nlm_host *host,
 411                                                 pid_t pid)
 412 {
 413         fl->c.flc_owner = nlmsvc_find_lockowner(host, pid);
 414 }
 415
 416 /*
 417  * Initialize arguments for GRANTED call. The nlm_rqst structure
 418  * has been cleared already.
 419  */
 420 static int nlmsvc_setgrantargs(struct nlm_rqst *call, struct nlm_lock *lock)
 421 {
 422         locks_copy_lock(&call->a_args.lock.fl, &lock->fl);
 423         memcpy(&call->a_args.lock.fh, &lock->fh, sizeof(call->a_args.lock.fh));
 424         call->a_args.lock.caller = utsname()->nodename;
 425         call->a_args.lock.oh.len = lock->oh.len;
 426
 427         /* set default data area */
 428         call->a_args.lock.oh.data = call->a_owner;
 429         call->a_args.lock.svid = ((struct nlm_lockowner *) lock->fl.c.flc_owner)->pid;
 430
 431         if (lock->oh.len > NLMCLNT_OHSIZE) {
 432                 void *data = kmalloc(lock->oh.len, GFP_KERNEL);
 433                 if (!data)
 434                         return 0;
 435                 call->a_args.lock.oh.data = (u8 *) data;
 436         }
 437
 438         memcpy(call->a_args.lock.oh.data, lock->oh.data, lock->oh.len);
 439         return 1;
 440 }
 441
 442 static void nlmsvc_freegrantargs(struct nlm_rqst *call)
 443 {
 444         if (call->a_args.lock.oh.data != call->a_owner)
 445                 kfree(call->a_args.lock.oh.data);
 446
 447         locks_release_private(&call->a_args.lock.fl);
 448 }
 449
 450 /*
 451  * Deferred lock request handling for non-blocking lock
 452  */
 453 static __be32
 454 nlmsvc_defer_lock_rqst(struct svc_rqst *rqstp, struct nlm_block *block)
 455 {
 456         __be32 status = nlm_lck_denied_nolocks;
 457
 458         block->b_flags |= B_QUEUED;
 459
 460         nlmsvc_insert_block(block, NLM_TIMEOUT);
 461
 462         block->b_cache_req = &rqstp->rq_chandle;
 463         if (rqstp->rq_chandle.defer) {
 464                 block->b_deferred_req =
 465                         rqstp->rq_chandle.defer(block->b_cache_req);
 466                 if (block->b_deferred_req != NULL)
 467                         status = nlm_drop_reply;
 468         }
 469         dprintk("lockd: nlmsvc_defer_lock_rqst block %p flags %d status %d\n",
 470                 block, block->b_flags, ntohl(status));
 471
 472         return status;
 473 }
 474
 475 /*
 476  * Attempt to establish a lock, and if it can't be granted, block it
 477  * if required.
 478  */
 479 __be32
 480 nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file,
 481             struct nlm_host *host, struct nlm_lock *lock, int wait,
 482             struct nlm_cookie *cookie, int reclaim)
 483 {
 484         struct inode            *inode = nlmsvc_file_inode(file);
 485         struct nlm_block        *block = NULL;
 486         int                     error;
 487         int                     mode;
 488         int                     async_block = 0;
 489         __be32                  ret;
 490
 491         dprintk("lockd: nlmsvc_lock(%s/%ld, ty=%d, pi=%d, %Ld-%Ld, bl=%d)\n",
 492                                 inode->i_sb->s_id, inode->i_ino,
 493                                 lock->fl.c.flc_type,
 494                                 lock->fl.c.flc_pid,
 495                                 (long long)lock->fl.fl_start,
 496                                 (long long)lock->fl.fl_end,
 497                                 wait);
 498
 499         if (!exportfs_lock_op_is_async(inode->i_sb->s_export_op)) {
 500                 async_block = wait;
 501                 wait = 0;
 502         }
 503
 504         /* Lock file against concurrent access */
 505         mutex_lock(&file->f_mutex);
 506         /* Get existing block (in case client is busy-waiting)
 507          * or create new block
 508          */
 509         block = nlmsvc_lookup_block(file, lock);
 510         if (block == NULL) {
 511                 block = nlmsvc_create_block(rqstp, host, file, lock, cookie);
 512                 ret = nlm_lck_denied_nolocks;
 513                 if (block == NULL)
 514                         goto out;
 515                 lock = &block->b_call->a_args.lock;
 516         } else
 517                 lock->fl.c.flc_flags &= ~FL_SLEEP;
 518
 519         if (block->b_flags & B_QUEUED) {
 520                 dprintk("lockd: nlmsvc_lock deferred block %p flags %d\n",
 521                                                         block, block->b_flags);
 522                 if (block->b_granted) {
 523                         nlmsvc_unlink_block(block);
 524                         ret = nlm_granted;
 525                         goto out;
 526                 }
 527                 if (block->b_flags & B_TIMED_OUT) {
 528                         nlmsvc_unlink_block(block);
 529                         ret = nlm_lck_denied;
 530                         goto out;
 531                 }
 532                 ret = nlm_drop_reply;
 533                 goto out;
 534         }
 535
 536         if (locks_in_grace(SVC_NET(rqstp)) && !reclaim) {
 537                 ret = nlm_lck_denied_grace_period;
 538                 goto out;
 539         }
 540         if (reclaim && !locks_in_grace(SVC_NET(rqstp))) {
 541                 ret = nlm_lck_denied_grace_period;
 542                 goto out;
 543         }
 544
 545         spin_lock(&nlm_blocked_lock);
 546         /*
 547          * If this is a lock request for an already pending
 548          * lock request we return nlm_lck_blocked without calling
 549          * vfs_lock_file() again. Otherwise we have two pending
 550          * requests on the underlaying ->lock() implementation but
 551          * only one nlm_block to being granted by lm_grant().
 552          */
 553         if (exportfs_lock_op_is_async(inode->i_sb->s_export_op) &&
 554             !list_empty(&block->b_list)) {
 555                 spin_unlock(&nlm_blocked_lock);
 556                 ret = nlm_lck_blocked;
 557                 goto out;
 558         }
 559
 560         /* Append to list of blocked */
 561         nlmsvc_insert_block_locked(block, NLM_NEVER);
 562         spin_unlock(&nlm_blocked_lock);
 563
 564         if (!wait)
 565                 lock->fl.c.flc_flags &= ~FL_SLEEP;
 566         mode = lock_to_openmode(&lock->fl);
 567         error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
 568         lock->fl.c.flc_flags &= ~FL_SLEEP;
 569
 570         dprintk("lockd: vfs_lock_file returned %d\n", error);
 571         switch (error) {
 572                 case 0:
 573                         nlmsvc_remove_block(block);
 574                         ret = nlm_granted;
 575                         goto out;
 576                 case -EAGAIN:
 577                         if (!wait)
 578                                 nlmsvc_remove_block(block);
 579                         ret = async_block ? nlm_lck_blocked : nlm_lck_denied;
 580                         goto out;
 581                 case FILE_LOCK_DEFERRED:
 582                         if (wait)
 583                                 break;
 584                         /* Filesystem lock operation is in progress
 585                            Add it to the queue waiting for callback */
 586                         ret = nlmsvc_defer_lock_rqst(rqstp, block);
 587                         goto out;
 588                 case -EDEADLK:
 589                         nlmsvc_remove_block(block);
 590                         ret = nlm_deadlock;
 591                         goto out;
 592                 default:                        /* includes ENOLCK */
 593                         nlmsvc_remove_block(block);
 594                         ret = nlm_lck_denied_nolocks;
 595                         goto out;
 596         }
 597
 598         ret = nlm_lck_blocked;
 599 out:
 600         mutex_unlock(&file->f_mutex);
 601         nlmsvc_release_block(block);
 602         dprintk("lockd: nlmsvc_lock returned %u\n", ret);
 603         return ret;
 604 }
 605
 606 /*
 607  * Test for presence of a conflicting lock.
 608  */
 609 __be32
 610 nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 611                 struct nlm_host *host, struct nlm_lock *lock,
 612                 struct nlm_lock *conflock, struct nlm_cookie *cookie)
 613 {
 614         int                     error;
 615         int                     mode;
 616         __be32                  ret;
 617
 618         dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
 619                                 nlmsvc_file_inode(file)->i_sb->s_id,
 620                                 nlmsvc_file_inode(file)->i_ino,
 621                                 lock->fl.c.flc_type,
 622                                 (long long)lock->fl.fl_start,
 623                                 (long long)lock->fl.fl_end);
 624
 625         if (locks_in_grace(SVC_NET(rqstp))) {
 626                 ret = nlm_lck_denied_grace_period;
 627                 goto out;
 628         }
 629
 630         mode = lock_to_openmode(&lock->fl);
 631         error = vfs_test_lock(file->f_file[mode], &lock->fl);
 632         if (error) {
 633                 /* We can't currently deal with deferred test requests */
 634                 if (error == FILE_LOCK_DEFERRED)
 635                         WARN_ON_ONCE(1);
 636
 637                 ret = nlm_lck_denied_nolocks;
 638                 goto out;
 639         }
 640
 641         if (lock->fl.c.flc_type == F_UNLCK) {
 642                 ret = nlm_granted;
 643                 goto out;
 644         }
 645
 646         dprintk("lockd: conflicting lock(ty=%d, %Ld-%Ld)\n",
 647                 lock->fl.c.flc_type, (long long)lock->fl.fl_start,
 648                 (long long)lock->fl.fl_end);
 649         conflock->caller = "somehost";  /* FIXME */
 650         conflock->len = strlen(conflock->caller);
 651         conflock->oh.len = 0;           /* don't return OH info */
 652         conflock->svid = lock->fl.c.flc_pid;
 653         conflock->fl.c.flc_type = lock->fl.c.flc_type;
 654         conflock->fl.fl_start = lock->fl.fl_start;
 655         conflock->fl.fl_end = lock->fl.fl_end;
 656         locks_release_private(&lock->fl);
 657
 658         ret = nlm_lck_denied;
 659 out:
 660         return ret;
 661 }
 662
 663 /*
 664  * Remove a lock.
 665  * This implies a CANCEL call: We send a GRANT_MSG, the client replies
 666  * with a GRANT_RES call which gets lost, and calls UNLOCK immediately
 667  * afterwards. In this case the block will still be there, and hence
 668  * must be removed.
 669  */
 670 __be32
 671 nlmsvc_unlock(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
 672 {
 673         int     error = 0;
 674
 675         dprintk("lockd: nlmsvc_unlock(%s/%ld, pi=%d, %Ld-%Ld)\n",
 676                                 nlmsvc_file_inode(file)->i_sb->s_id,
 677                                 nlmsvc_file_inode(file)->i_ino,
 678                                 lock->fl.c.flc_pid,
 679                                 (long long)lock->fl.fl_start,
 680                                 (long long)lock->fl.fl_end);
 681
 682         /* First, cancel any lock that might be there */
 683         nlmsvc_cancel_blocked(net, file, lock);
 684
 685         lock->fl.c.flc_type = F_UNLCK;
 686         lock->fl.c.flc_file = file->f_file[O_RDONLY];
 687         if (lock->fl.c.flc_file)
 688                 error = vfs_lock_file(lock->fl.c.flc_file, F_SETLK,
 689                                         &lock->fl, NULL);
 690         lock->fl.c.flc_file = file->f_file[O_WRONLY];
 691         if (lock->fl.c.flc_file)
 692                 error |= vfs_lock_file(lock->fl.c.flc_file, F_SETLK,
 693                                         &lock->fl, NULL);
 694
 695         return (error < 0)? nlm_lck_denied_nolocks : nlm_granted;
 696 }
 697
 698 /*
 699  * Cancel a previously blocked request.
 700  *
 701  * A cancel request always overrides any grant that may currently
 702  * be in progress.
 703  * The calling procedure must check whether the file can be closed.
 704  */
 705 __be32
 706 nlmsvc_cancel_blocked(struct net *net, struct nlm_file *file, struct nlm_lock *lock)
 707 {
 708         struct nlm_block        *block;
 709         int status = 0;
 710         int mode;
 711
 712         dprintk("lockd: nlmsvc_cancel(%s/%ld, pi=%d, %Ld-%Ld)\n",
 713                                 nlmsvc_file_inode(file)->i_sb->s_id,
 714                                 nlmsvc_file_inode(file)->i_ino,
 715                                 lock->fl.c.flc_pid,
 716                                 (long long)lock->fl.fl_start,
 717                                 (long long)lock->fl.fl_end);
 718
 719         if (locks_in_grace(net))
 720                 return nlm_lck_denied_grace_period;
 721
 722         mutex_lock(&file->f_mutex);
 723         block = nlmsvc_lookup_block(file, lock);
 724         mutex_unlock(&file->f_mutex);
 725         if (block != NULL) {
 726                 struct file_lock *fl = &block->b_call->a_args.lock.fl;
 727
 728                 mode = lock_to_openmode(fl);
 729                 vfs_cancel_lock(block->b_file->f_file[mode], fl);
 730                 status = nlmsvc_unlink_block(block);
 731                 nlmsvc_release_block(block);
 732         }
 733         return status ? nlm_lck_denied : nlm_granted;
 734 }
 735
 736 /*
 737  * This is a callback from the filesystem for VFS file lock requests.
 738  * It will be used if lm_grant is defined and the filesystem can not
 739  * respond to the request immediately.
 740  * For SETLK or SETLKW request it will get the local posix lock.
 741  * In all cases it will move the block to the head of nlm_blocked q where
 742  * nlmsvc_retry_blocked() can send back a reply for SETLKW or revisit the
 743  * deferred rpc for GETLK and SETLK.
 744  */
 745 static void
 746 nlmsvc_update_deferred_block(struct nlm_block *block, int result)
 747 {
 748         block->b_flags |= B_GOT_CALLBACK;
 749         if (result == 0)
 750                 block->b_granted = 1;
 751         else
 752                 block->b_flags |= B_TIMED_OUT;
 753 }
 754
 755 static int nlmsvc_grant_deferred(struct file_lock *fl, int result)
 756 {
 757         struct nlm_block *block;
 758         int rc = -ENOENT;
 759
 760         spin_lock(&nlm_blocked_lock);
 761         list_for_each_entry(block, &nlm_blocked, b_list) {
 762                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
 763                         dprintk("lockd: nlmsvc_notify_blocked block %p flags %d\n",
 764                                                         block, block->b_flags);
 765                         if (block->b_flags & B_QUEUED) {
 766                                 if (block->b_flags & B_TIMED_OUT) {
 767                                         rc = -ENOLCK;
 768                                         break;
 769                                 }
 770                                 nlmsvc_update_deferred_block(block, result);
 771                         } else if (result == 0)
 772                                 block->b_granted = 1;
 773
 774                         nlmsvc_insert_block_locked(block, 0);
 775                         svc_wake_up(block->b_daemon);
 776                         rc = 0;
 777                         break;
 778                 }
 779         }
 780         spin_unlock(&nlm_blocked_lock);
 781         if (rc == -ENOENT)
 782                 printk(KERN_WARNING "lockd: grant for unknown block\n");
 783         return rc;
 784 }
 785
 786 /*
 787  * Unblock a blocked lock request. This is a callback invoked from the
 788  * VFS layer when a lock on which we blocked is removed.
 789  *
 790  * This function doesn't grant the blocked lock instantly, but rather moves
 791  * the block to the head of nlm_blocked where it can be picked up by lockd.
 792  */
 793 static void
 794 nlmsvc_notify_blocked(struct file_lock *fl)
 795 {
 796         struct nlm_block        *block;
 797
 798         dprintk("lockd: VFS unblock notification for block %p\n", fl);
 799         spin_lock(&nlm_blocked_lock);
 800         list_for_each_entry(block, &nlm_blocked, b_list) {
 801                 if (nlm_compare_locks(&block->b_call->a_args.lock.fl, fl)) {
 802                         nlmsvc_insert_block_locked(block, 0);
 803                         spin_unlock(&nlm_blocked_lock);
 804                         svc_wake_up(block->b_daemon);
 805                         return;
 806                 }
 807         }
 808         spin_unlock(&nlm_blocked_lock);
 809         printk(KERN_WARNING "lockd: notification for unknown block!\n");
 810 }
 811
 812 static fl_owner_t nlmsvc_get_owner(fl_owner_t owner)
 813 {
 814         return nlmsvc_get_lockowner(owner);
 815 }
 816
 817 static void nlmsvc_put_owner(fl_owner_t owner)
 818 {
 819         nlmsvc_put_lockowner(owner);
 820 }
 821
 822 const struct lock_manager_operations nlmsvc_lock_operations = {
 823         .lm_notify = nlmsvc_notify_blocked,
 824         .lm_grant = nlmsvc_grant_deferred,
 825         .lm_get_owner = nlmsvc_get_owner,
 826         .lm_put_owner = nlmsvc_put_owner,
 827 };
 828
 829 /*
 830  * Try to claim a lock that was previously blocked.
 831  *
 832  * Note that we use both the RPC_GRANTED_MSG call _and_ an async
 833  * RPC thread when notifying the client. This seems like overkill...
 834  * Here's why:
 835  *  -   we don't want to use a synchronous RPC thread, otherwise
 836  *      we might find ourselves hanging on a dead portmapper.
 837  *  -   Some lockd implementations (e.g. HP) don't react to
 838  *      RPC_GRANTED calls; they seem to insist on RPC_GRANTED_MSG calls.
 839  */
 840 static void
 841 nlmsvc_grant_blocked(struct nlm_block *block)
 842 {
 843         struct nlm_file         *file = block->b_file;
 844         struct nlm_lock         *lock = &block->b_call->a_args.lock;
 845         int                     mode;
 846         int                     error;
 847         loff_t                  fl_start, fl_end;
 848
 849         dprintk("lockd: grant blocked lock %p\n", block);
 850
 851         kref_get(&block->b_count);
 852
 853         /* Unlink block request from list */
 854         nlmsvc_unlink_block(block);
 855
 856         /* If b_granted is true this means we've been here before.
 857          * Just retry the grant callback, possibly refreshing the RPC
 858          * binding */
 859         if (block->b_granted) {
 860                 nlm_rebind_host(block->b_host);
 861                 goto callback;
 862         }
 863
 864         /* Try the lock operation again */
 865         /* vfs_lock_file() can mangle fl_start and fl_end, but we need
 866          * them unchanged for the GRANT_MSG
 867          */
 868         lock->fl.c.flc_flags |= FL_SLEEP;
 869         fl_start = lock->fl.fl_start;
 870         fl_end = lock->fl.fl_end;
 871         mode = lock_to_openmode(&lock->fl);
 872         error = vfs_lock_file(file->f_file[mode], F_SETLK, &lock->fl, NULL);
 873         lock->fl.c.flc_flags &= ~FL_SLEEP;
 874         lock->fl.fl_start = fl_start;
 875         lock->fl.fl_end = fl_end;
 876
 877         switch (error) {
 878         case 0:
 879                 break;
 880         case FILE_LOCK_DEFERRED:
 881                 dprintk("lockd: lock still blocked error %d\n", error);
 882                 nlmsvc_insert_block(block, NLM_NEVER);
 883                 nlmsvc_release_block(block);
 884                 return;
 885         default:
 886                 printk(KERN_WARNING "lockd: unexpected error %d in %s!\n",
 887                                 -error, __func__);
 888                 nlmsvc_insert_block(block, 10 * HZ);
 889                 nlmsvc_release_block(block);
 890                 return;
 891         }
 892
 893 callback:
 894         /* Lock was granted by VFS. */
 895         dprintk("lockd: GRANTing blocked lock.\n");
 896         block->b_granted = 1;
 897
 898         /* keep block on the list, but don't reattempt until the RPC
 899          * completes or the submission fails
 900          */
 901         nlmsvc_insert_block(block, NLM_NEVER);
 902
 903         /* Call the client -- use a soft RPC task since nlmsvc_retry_blocked
 904          * will queue up a new one if this one times out
 905          */
 906         error = nlm_async_call(block->b_call, NLMPROC_GRANTED_MSG,
 907                                 &nlmsvc_grant_ops);
 908
 909         /* RPC submission failed, wait a bit and retry */
 910         if (error < 0)
 911                 nlmsvc_insert_block(block, 10 * HZ);
 912 }
 913
 914 /*
 915  * This is the callback from the RPC layer when the NLM_GRANTED_MSG
 916  * RPC call has succeeded or timed out.
 917  * Like all RPC callbacks, it is invoked by the rpciod process, so it
 918  * better not sleep. Therefore, we put the blocked lock on the nlm_blocked
 919  * chain once more in order to have it removed by lockd itself (which can
 920  * then sleep on the file semaphore without disrupting e.g. the nfs client).
 921  */
 922 static void nlmsvc_grant_callback(struct rpc_task *task, void *data)
 923 {
 924         struct nlm_rqst         *call = data;
 925         struct nlm_block        *block = call->a_block;
 926         unsigned long           timeout;
 927
 928         dprintk("lockd: GRANT_MSG RPC callback\n");
 929
 930         spin_lock(&nlm_blocked_lock);
 931         /* if the block is not on a list at this point then it has
 932          * been invalidated. Don't try to requeue it.
 933          *
 934          * FIXME: it's possible that the block is removed from the list
 935          * after this check but before the nlmsvc_insert_block. In that
 936          * case it will be added back. Perhaps we need better locking
 937          * for nlm_blocked?
 938          */
 939         if (list_empty(&block->b_list))
 940                 goto out;
 941
 942         /* Technically, we should down the file semaphore here. Since we
 943          * move the block towards the head of the queue only, no harm
 944          * can be done, though. */
 945         if (task->tk_status < 0) {
 946                 /* RPC error: Re-insert for retransmission */
 947                 timeout = 10 * HZ;
 948         } else {
 949                 /* Call was successful, now wait for client callback */
 950                 timeout = 60 * HZ;
 951         }
 952         nlmsvc_insert_block_locked(block, timeout);
 953         svc_wake_up(block->b_daemon);
 954 out:
 955         spin_unlock(&nlm_blocked_lock);
 956 }
 957
 958 /*
 959  * FIXME: nlmsvc_release_block() grabs a mutex.  This is not allowed for an
 960  * .rpc_release rpc_call_op
 961  */
 962 static void nlmsvc_grant_release(void *data)
 963 {
 964         struct nlm_rqst         *call = data;
 965         nlmsvc_release_block(call->a_block);
 966 }
 967
 968 static const struct rpc_call_ops nlmsvc_grant_ops = {
 969         .rpc_call_done = nlmsvc_grant_callback,
 970         .rpc_release = nlmsvc_grant_release,
 971 };
 972
 973 /*
 974  * We received a GRANT_RES callback. Try to find the corresponding
 975  * block.
 976  */
 977 void
 978 nlmsvc_grant_reply(struct nlm_cookie *cookie, __be32 status)
 979 {
 980         struct nlm_block        *block;
 981         struct file_lock        *fl;
 982         int                     error;
 983
 984         dprintk("grant_reply: looking for cookie %x, s=%d \n",
 985                 *(unsigned int *)(cookie->data), status);
 986         if (!(block = nlmsvc_find_block(cookie)))
 987                 return;
 988
 989         switch (status) {
 990         case nlm_lck_denied_grace_period:
 991                 /* Try again in a couple of seconds */
 992                 nlmsvc_insert_block(block, 10 * HZ);
 993                 break;
 994         case nlm_lck_denied:
 995                 /* Client doesn't want it, just unlock it */
 996                 nlmsvc_unlink_block(block);
 997                 fl = &block->b_call->a_args.lock.fl;
 998                 fl->c.flc_type = F_UNLCK;
 999                 error = vfs_lock_file(fl->c.flc_file, F_SETLK, fl, NULL);
1000                 if (error)
1001                         pr_warn("lockd: unable to unlock lock rejected by client!\n");
1002                 break;
1003         default:
1004                 /*
1005                  * Either it was accepted or the status makes no sense
1006                  * just unlink it either way.
1007                  */
1008                 nlmsvc_unlink_block(block);
1009         }
1010         nlmsvc_release_block(block);
1011 }
1012
1013 /* Helper function to handle retry of a deferred block.
1014  * If it is a blocking lock, call grant_blocked.
1015  * For a non-blocking lock or test lock, revisit the request.
1016  */
1017 static void
1018 retry_deferred_block(struct nlm_block *block)
1019 {
1020         if (!(block->b_flags & B_GOT_CALLBACK))
1021                 block->b_flags |= B_TIMED_OUT;
1022         nlmsvc_insert_block(block, NLM_TIMEOUT);
1023         dprintk("revisit block %p flags %d\n",  block, block->b_flags);
1024         if (block->b_deferred_req) {
1025                 block->b_deferred_req->revisit(block->b_deferred_req, 0);
1026                 block->b_deferred_req = NULL;
1027         }
1028 }
1029
1030 /*
1031  * Retry all blocked locks that have been notified. This is where lockd
1032  * picks up locks that can be granted, or grant notifications that must
1033  * be retransmitted.
1034  */
1035 void
1036 nlmsvc_retry_blocked(struct svc_rqst *rqstp)
1037 {
1038         unsigned long   timeout = MAX_SCHEDULE_TIMEOUT;
1039         struct nlm_block *block;
1040
1041         spin_lock(&nlm_blocked_lock);
1042         while (!list_empty(&nlm_blocked) && !svc_thread_should_stop(rqstp)) {
1043                 block = list_entry(nlm_blocked.next, struct nlm_block, b_list);
1044
1045                 if (block->b_when == NLM_NEVER)
1046                         break;
1047                 if (time_after(block->b_when, jiffies)) {
1048                         timeout = block->b_when - jiffies;
1049                         break;
1050                 }
1051                 spin_unlock(&nlm_blocked_lock);
1052
1053                 dprintk("nlmsvc_retry_blocked(%p, when=%ld)\n",
1054                         block, block->b_when);
1055                 if (block->b_flags & B_QUEUED) {
1056                         dprintk("nlmsvc_retry_blocked delete block (%p, granted=%d, flags=%d)\n",
1057                                 block, block->b_granted, block->b_flags);
1058                         retry_deferred_block(block);
1059                 } else
1060                         nlmsvc_grant_blocked(block);
1061                 spin_lock(&nlm_blocked_lock);
1062         }
1063         spin_unlock(&nlm_blocked_lock);
1064
1065         if (timeout < MAX_SCHEDULE_TIMEOUT)
1066                 mod_timer(&nlmsvc_retry, jiffies + timeout);
1067 }