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