fs/afs/flock.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* AFS file locking support
   3  *
   4  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #include "internal.h"
   9
  10 #define AFS_LOCK_GRANTED        0
  11 #define AFS_LOCK_PENDING        1
  12 #define AFS_LOCK_YOUR_TRY       2
  13
  14 struct workqueue_struct *afs_lock_manager;
  15
  16 static void afs_next_locker(struct afs_vnode *vnode, int error);
  17 static void afs_fl_copy_lock(struct file_lock *new, struct file_lock *fl);
  18 static void afs_fl_release_private(struct file_lock *fl);
  19
  20 static const struct file_lock_operations afs_lock_ops = {
  21         .fl_copy_lock           = afs_fl_copy_lock,
  22         .fl_release_private     = afs_fl_release_private,
  23 };
  24
  25 static inline void afs_set_lock_state(struct afs_vnode *vnode, enum afs_lock_state state)
  26 {
  27         _debug("STATE %u -> %u", vnode->lock_state, state);
  28         vnode->lock_state = state;
  29 }
  30
  31 static atomic_t afs_file_lock_debug_id;
  32
  33 /*
  34  * if the callback is broken on this vnode, then the lock may now be available
  35  */
  36 void afs_lock_may_be_available(struct afs_vnode *vnode)
  37 {
  38         _enter("{%llx:%llu}", vnode->fid.vid, vnode->fid.vnode);
  39
  40         spin_lock(&vnode->lock);
  41         if (vnode->lock_state == AFS_VNODE_LOCK_WAITING_FOR_CB)
  42                 afs_next_locker(vnode, 0);
  43         trace_afs_flock_ev(vnode, NULL, afs_flock_callback_break, 0);
  44         spin_unlock(&vnode->lock);
  45 }
  46
  47 /*
  48  * the lock will time out in 5 minutes unless we extend it, so schedule
  49  * extension in a bit less than that time
  50  */
  51 static void afs_schedule_lock_extension(struct afs_vnode *vnode)
  52 {
  53         ktime_t expires_at, now, duration;
  54         u64 duration_j;
  55
  56         expires_at = ktime_add_ms(vnode->locked_at, AFS_LOCKWAIT * 1000 / 2);
  57         now = ktime_get_real();
  58         duration = ktime_sub(expires_at, now);
  59         if (duration <= 0)
  60                 duration_j = 0;
  61         else
  62                 duration_j = nsecs_to_jiffies(ktime_to_ns(duration));
  63
  64         queue_delayed_work(afs_lock_manager, &vnode->lock_work, duration_j);
  65 }
  66
  67 /*
  68  * In the case of successful completion of a lock operation, record the time
  69  * the reply appeared and start the lock extension timer.
  70  */
  71 void afs_lock_op_done(struct afs_call *call)
  72 {
  73         struct afs_vnode *vnode = call->lvnode;
  74
  75         if (call->error == 0) {
  76                 spin_lock(&vnode->lock);
  77                 trace_afs_flock_ev(vnode, NULL, afs_flock_timestamp, 0);
  78                 vnode->locked_at = call->reply_time;
  79                 afs_schedule_lock_extension(vnode);
  80                 spin_unlock(&vnode->lock);
  81         }
  82 }
  83
  84 /*
  85  * grant one or more locks (readlocks are allowed to jump the queue if the
  86  * first lock in the queue is itself a readlock)
  87  * - the caller must hold the vnode lock
  88  */
  89 static void afs_grant_locks(struct afs_vnode *vnode)
  90 {
  91         struct file_lock *p, *_p;
  92         bool exclusive = (vnode->lock_type == AFS_LOCK_WRITE);
  93
  94         list_for_each_entry_safe(p, _p, &vnode->pending_locks, fl_u.afs.link) {
  95                 if (!exclusive && p->fl_type == F_WRLCK)
  96                         continue;
  97
  98                 list_move_tail(&p->fl_u.afs.link, &vnode->granted_locks);
  99                 p->fl_u.afs.state = AFS_LOCK_GRANTED;
 100                 trace_afs_flock_op(vnode, p, afs_flock_op_grant);
 101                 wake_up(&p->fl_wait);
 102         }
 103 }
 104
 105 /*
 106  * If an error is specified, reject every pending lock that matches the
 107  * authentication and type of the lock we failed to get.  If there are any
 108  * remaining lockers, try to wake up one of them to have a go.
 109  */
 110 static void afs_next_locker(struct afs_vnode *vnode, int error)
 111 {
 112         struct file_lock *p, *_p, *next = NULL;
 113         struct key *key = vnode->lock_key;
 114         unsigned int fl_type = F_RDLCK;
 115
 116         _enter("");
 117
 118         if (vnode->lock_type == AFS_LOCK_WRITE)
 119                 fl_type = F_WRLCK;
 120
 121         list_for_each_entry_safe(p, _p, &vnode->pending_locks, fl_u.afs.link) {
 122                 if (error &&
 123                     p->fl_type == fl_type &&
 124                     afs_file_key(p->fl_file) == key) {
 125                         list_del_init(&p->fl_u.afs.link);
 126                         p->fl_u.afs.state = error;
 127                         wake_up(&p->fl_wait);
 128                 }
 129
 130                 /* Select the next locker to hand off to. */
 131                 if (next &&
 132                     (next->fl_type == F_WRLCK || p->fl_type == F_RDLCK))
 133                         continue;
 134                 next = p;
 135         }
 136
 137         vnode->lock_key = NULL;
 138         key_put(key);
 139
 140         if (next) {
 141                 afs_set_lock_state(vnode, AFS_VNODE_LOCK_SETTING);
 142                 next->fl_u.afs.state = AFS_LOCK_YOUR_TRY;
 143                 trace_afs_flock_op(vnode, next, afs_flock_op_wake);
 144                 wake_up(&next->fl_wait);
 145         } else {
 146                 afs_set_lock_state(vnode, AFS_VNODE_LOCK_NONE);
 147                 trace_afs_flock_ev(vnode, NULL, afs_flock_no_lockers, 0);
 148         }
 149
 150         _leave("");
 151 }
 152
 153 /*
 154  * Kill off all waiters in the the pending lock queue due to the vnode being
 155  * deleted.
 156  */
 157 static void afs_kill_lockers_enoent(struct afs_vnode *vnode)
 158 {
 159         struct file_lock *p;
 160
 161         afs_set_lock_state(vnode, AFS_VNODE_LOCK_DELETED);
 162
 163         while (!list_empty(&vnode->pending_locks)) {
 164                 p = list_entry(vnode->pending_locks.next,
 165                                struct file_lock, fl_u.afs.link);
 166                 list_del_init(&p->fl_u.afs.link);
 167                 p->fl_u.afs.state = -ENOENT;
 168                 wake_up(&p->fl_wait);
 169         }
 170
 171         key_put(vnode->lock_key);
 172         vnode->lock_key = NULL;
 173 }
 174
 175 /*
 176  * Get a lock on a file
 177  */
 178 static int afs_set_lock(struct afs_vnode *vnode, struct key *key,
 179                         afs_lock_type_t type)
 180 {
 181         struct afs_status_cb *scb;
 182         struct afs_fs_cursor fc;
 183         int ret;
 184
 185         _enter("%s{%llx:%llu.%u},%x,%u",
 186                vnode->volume->name,
 187                vnode->fid.vid,
 188                vnode->fid.vnode,
 189                vnode->fid.unique,
 190                key_serial(key), type);
 191
 192         scb = kzalloc(sizeof(struct afs_status_cb), GFP_KERNEL);
 193         if (!scb)
 194                 return -ENOMEM;
 195
 196         ret = -ERESTARTSYS;
 197         if (afs_begin_vnode_operation(&fc, vnode, key, true)) {
 198                 while (afs_select_fileserver(&fc)) {
 199                         fc.cb_break = afs_calc_vnode_cb_break(vnode);
 200                         afs_fs_set_lock(&fc, type, scb);
 201                 }
 202
 203                 afs_check_for_remote_deletion(&fc, vnode);
 204                 afs_vnode_commit_status(&fc, vnode, fc.cb_break, NULL, scb);
 205                 ret = afs_end_vnode_operation(&fc);
 206         }
 207
 208         kfree(scb);
 209         _leave(" = %d", ret);
 210         return ret;
 211 }
 212
 213 /*
 214  * Extend a lock on a file
 215  */
 216 static int afs_extend_lock(struct afs_vnode *vnode, struct key *key)
 217 {
 218         struct afs_status_cb *scb;
 219         struct afs_fs_cursor fc;
 220         int ret;
 221
 222         _enter("%s{%llx:%llu.%u},%x",
 223                vnode->volume->name,
 224                vnode->fid.vid,
 225                vnode->fid.vnode,
 226                vnode->fid.unique,
 227                key_serial(key));
 228
 229         scb = kzalloc(sizeof(struct afs_status_cb), GFP_KERNEL);
 230         if (!scb)
 231                 return -ENOMEM;
 232
 233         ret = -ERESTARTSYS;
 234         if (afs_begin_vnode_operation(&fc, vnode, key, false)) {
 235                 while (afs_select_current_fileserver(&fc)) {
 236                         fc.cb_break = afs_calc_vnode_cb_break(vnode);
 237                         afs_fs_extend_lock(&fc, scb);
 238                 }
 239
 240                 afs_check_for_remote_deletion(&fc, vnode);
 241                 afs_vnode_commit_status(&fc, vnode, fc.cb_break, NULL, scb);
 242                 ret = afs_end_vnode_operation(&fc);
 243         }
 244
 245         kfree(scb);
 246         _leave(" = %d", ret);
 247         return ret;
 248 }
 249
 250 /*
 251  * Release a lock on a file
 252  */
 253 static int afs_release_lock(struct afs_vnode *vnode, struct key *key)
 254 {
 255         struct afs_status_cb *scb;
 256         struct afs_fs_cursor fc;
 257         int ret;
 258
 259         _enter("%s{%llx:%llu.%u},%x",
 260                vnode->volume->name,
 261                vnode->fid.vid,
 262                vnode->fid.vnode,
 263                vnode->fid.unique,
 264                key_serial(key));
 265
 266         scb = kzalloc(sizeof(struct afs_status_cb), GFP_KERNEL);
 267         if (!scb)
 268                 return -ENOMEM;
 269
 270         ret = -ERESTARTSYS;
 271         if (afs_begin_vnode_operation(&fc, vnode, key, false)) {
 272                 while (afs_select_current_fileserver(&fc)) {
 273                         fc.cb_break = afs_calc_vnode_cb_break(vnode);
 274                         afs_fs_release_lock(&fc, scb);
 275                 }
 276
 277                 afs_check_for_remote_deletion(&fc, vnode);
 278                 afs_vnode_commit_status(&fc, vnode, fc.cb_break, NULL, scb);
 279                 ret = afs_end_vnode_operation(&fc);
 280         }
 281
 282         kfree(scb);
 283         _leave(" = %d", ret);
 284         return ret;
 285 }
 286
 287 /*
 288  * do work for a lock, including:
 289  * - probing for a lock we're waiting on but didn't get immediately
 290  * - extending a lock that's close to timing out
 291  */
 292 void afs_lock_work(struct work_struct *work)
 293 {
 294         struct afs_vnode *vnode =
 295                 container_of(work, struct afs_vnode, lock_work.work);
 296         struct key *key;
 297         int ret;
 298
 299         _enter("{%llx:%llu}", vnode->fid.vid, vnode->fid.vnode);
 300
 301         spin_lock(&vnode->lock);
 302
 303 again:
 304         _debug("wstate %u for %p", vnode->lock_state, vnode);
 305         switch (vnode->lock_state) {
 306         case AFS_VNODE_LOCK_NEED_UNLOCK:
 307                 afs_set_lock_state(vnode, AFS_VNODE_LOCK_UNLOCKING);
 308                 trace_afs_flock_ev(vnode, NULL, afs_flock_work_unlocking, 0);
 309                 spin_unlock(&vnode->lock);
 310
 311                 /* attempt to release the server lock; if it fails, we just
 312                  * wait 5 minutes and it'll expire anyway */
 313                 ret = afs_release_lock(vnode, vnode->lock_key);
 314                 if (ret < 0 && vnode->lock_state != AFS_VNODE_LOCK_DELETED) {
 315                         trace_afs_flock_ev(vnode, NULL, afs_flock_release_fail,
 316                                            ret);
 317                         printk(KERN_WARNING "AFS:"
 318                                " Failed to release lock on {%llx:%llx} error %d\n",
 319                                vnode->fid.vid, vnode->fid.vnode, ret);
 320                 }
 321
 322                 spin_lock(&vnode->lock);
 323                 if (ret == -ENOENT)
 324                         afs_kill_lockers_enoent(vnode);
 325                 else
 326                         afs_next_locker(vnode, 0);
 327                 spin_unlock(&vnode->lock);
 328                 return;
 329
 330         /* If we've already got a lock, then it must be time to extend that
 331          * lock as AFS locks time out after 5 minutes.
 332          */
 333         case AFS_VNODE_LOCK_GRANTED:
 334                 _debug("extend");
 335
 336                 ASSERT(!list_empty(&vnode->granted_locks));
 337
 338                 key = key_get(vnode->lock_key);
 339                 afs_set_lock_state(vnode, AFS_VNODE_LOCK_EXTENDING);
 340                 trace_afs_flock_ev(vnode, NULL, afs_flock_work_extending, 0);
 341                 spin_unlock(&vnode->lock);
 342
 343                 ret = afs_extend_lock(vnode, key); /* RPC */
 344                 key_put(key);
 345
 346                 if (ret < 0) {
 347                         trace_afs_flock_ev(vnode, NULL, afs_flock_extend_fail,
 348                                            ret);
 349                         pr_warning("AFS: Failed to extend lock on {%llx:%llx} error %d\n",
 350                                    vnode->fid.vid, vnode->fid.vnode, ret);
 351                 }
 352
 353                 spin_lock(&vnode->lock);
 354
 355                 if (ret == -ENOENT) {
 356                         afs_kill_lockers_enoent(vnode);
 357                         spin_unlock(&vnode->lock);
 358                         return;
 359                 }
 360
 361                 if (vnode->lock_state != AFS_VNODE_LOCK_EXTENDING)
 362                         goto again;
 363                 afs_set_lock_state(vnode, AFS_VNODE_LOCK_GRANTED);
 364
 365                 if (ret != 0)
 366                         queue_delayed_work(afs_lock_manager, &vnode->lock_work,
 367                                            HZ * 10);
 368                 spin_unlock(&vnode->lock);
 369                 _leave(" [ext]");
 370                 return;
 371
 372         /* If we're waiting for a callback to indicate lock release, we can't
 373          * actually rely on this, so need to recheck at regular intervals.  The
 374          * problem is that the server might not notify us if the lock just
 375          * expires (say because a client died) rather than being explicitly
 376          * released.
 377          */
 378         case AFS_VNODE_LOCK_WAITING_FOR_CB:
 379                 _debug("retry");
 380                 afs_next_locker(vnode, 0);
 381                 spin_unlock(&vnode->lock);
 382                 return;
 383
 384         case AFS_VNODE_LOCK_DELETED:
 385                 afs_kill_lockers_enoent(vnode);
 386                 spin_unlock(&vnode->lock);
 387                 return;
 388
 389                 /* Fall through */
 390         default:
 391                 /* Looks like a lock request was withdrawn. */
 392                 spin_unlock(&vnode->lock);
 393                 _leave(" [no]");
 394                 return;
 395         }
 396 }
 397
 398 /*
 399  * pass responsibility for the unlocking of a vnode on the server to the
 400  * manager thread, lest a pending signal in the calling thread interrupt
 401  * AF_RXRPC
 402  * - the caller must hold the vnode lock
 403  */
 404 static void afs_defer_unlock(struct afs_vnode *vnode)
 405 {
 406         _enter("%u", vnode->lock_state);
 407
 408         if (list_empty(&vnode->granted_locks) &&
 409             (vnode->lock_state == AFS_VNODE_LOCK_GRANTED ||
 410              vnode->lock_state == AFS_VNODE_LOCK_EXTENDING)) {
 411                 cancel_delayed_work(&vnode->lock_work);
 412
 413                 afs_set_lock_state(vnode, AFS_VNODE_LOCK_NEED_UNLOCK);
 414                 trace_afs_flock_ev(vnode, NULL, afs_flock_defer_unlock, 0);
 415                 queue_delayed_work(afs_lock_manager, &vnode->lock_work, 0);
 416         }
 417 }
 418
 419 /*
 420  * Check that our view of the file metadata is up to date and check to see
 421  * whether we think that we have a locking permit.
 422  */
 423 static int afs_do_setlk_check(struct afs_vnode *vnode, struct key *key,
 424                               enum afs_flock_mode mode, afs_lock_type_t type)
 425 {
 426         afs_access_t access;
 427         int ret;
 428
 429         /* Make sure we've got a callback on this file and that our view of the
 430          * data version is up to date.
 431          */
 432         ret = afs_validate(vnode, key);
 433         if (ret < 0)
 434                 return ret;
 435
 436         /* Check the permission set to see if we're actually going to be
 437          * allowed to get a lock on this file.
 438          */
 439         ret = afs_check_permit(vnode, key, &access);
 440         if (ret < 0)
 441                 return ret;
 442
 443         /* At a rough estimation, you need LOCK, WRITE or INSERT perm to
 444          * read-lock a file and WRITE or INSERT perm to write-lock a file.
 445          *
 446          * We can't rely on the server to do this for us since if we want to
 447          * share a read lock that we already have, we won't go the server.
 448          */
 449         if (type == AFS_LOCK_READ) {
 450                 if (!(access & (AFS_ACE_INSERT | AFS_ACE_WRITE | AFS_ACE_LOCK)))
 451                         return -EACCES;
 452         } else {
 453                 if (!(access & (AFS_ACE_INSERT | AFS_ACE_WRITE)))
 454                         return -EACCES;
 455         }
 456
 457         return 0;
 458 }
 459
 460 /*
 461  * request a lock on a file on the server
 462  */
 463 static int afs_do_setlk(struct file *file, struct file_lock *fl)
 464 {
 465         struct inode *inode = locks_inode(file);
 466         struct afs_vnode *vnode = AFS_FS_I(inode);
 467         enum afs_flock_mode mode = AFS_FS_S(inode->i_sb)->flock_mode;
 468         afs_lock_type_t type;
 469         struct key *key = afs_file_key(file);
 470         bool partial, no_server_lock = false;
 471         int ret;
 472
 473         if (mode == afs_flock_mode_unset)
 474                 mode = afs_flock_mode_openafs;
 475
 476         _enter("{%llx:%llu},%llu-%llu,%u,%u",
 477                vnode->fid.vid, vnode->fid.vnode,
 478                fl->fl_start, fl->fl_end, fl->fl_type, mode);
 479
 480         fl->fl_ops = &afs_lock_ops;
 481         INIT_LIST_HEAD(&fl->fl_u.afs.link);
 482         fl->fl_u.afs.state = AFS_LOCK_PENDING;
 483
 484         partial = (fl->fl_start != 0 || fl->fl_end != OFFSET_MAX);
 485         type = (fl->fl_type == F_RDLCK) ? AFS_LOCK_READ : AFS_LOCK_WRITE;
 486         if (mode == afs_flock_mode_write && partial)
 487                 type = AFS_LOCK_WRITE;
 488
 489         ret = afs_do_setlk_check(vnode, key, mode, type);
 490         if (ret < 0)
 491                 return ret;
 492
 493         trace_afs_flock_op(vnode, fl, afs_flock_op_set_lock);
 494
 495         /* AFS3 protocol only supports full-file locks and doesn't provide any
 496          * method of upgrade/downgrade, so we need to emulate for partial-file
 497          * locks.
 498          *
 499          * The OpenAFS client only gets a server lock for a full-file lock and
 500          * keeps partial-file locks local.  Allow this behaviour to be emulated
 501          * (as the default).
 502          */
 503         if (mode == afs_flock_mode_local ||
 504             (partial && mode == afs_flock_mode_openafs)) {
 505                 no_server_lock = true;
 506                 goto skip_server_lock;
 507         }
 508
 509         spin_lock(&vnode->lock);
 510         list_add_tail(&fl->fl_u.afs.link, &vnode->pending_locks);
 511
 512         ret = -ENOENT;
 513         if (vnode->lock_state == AFS_VNODE_LOCK_DELETED)
 514                 goto error_unlock;
 515
 516         /* If we've already got a lock on the server then try to move to having
 517          * the VFS grant the requested lock.  Note that this means that other
 518          * clients may get starved out.
 519          */
 520         _debug("try %u", vnode->lock_state);
 521         if (vnode->lock_state == AFS_VNODE_LOCK_GRANTED) {
 522                 if (type == AFS_LOCK_READ) {
 523                         _debug("instant readlock");
 524                         list_move_tail(&fl->fl_u.afs.link, &vnode->granted_locks);
 525                         fl->fl_u.afs.state = AFS_LOCK_GRANTED;
 526                         goto vnode_is_locked_u;
 527                 }
 528
 529                 if (vnode->lock_type == AFS_LOCK_WRITE) {
 530                         _debug("instant writelock");
 531                         list_move_tail(&fl->fl_u.afs.link, &vnode->granted_locks);
 532                         fl->fl_u.afs.state = AFS_LOCK_GRANTED;
 533                         goto vnode_is_locked_u;
 534                 }
 535         }
 536
 537         if (vnode->lock_state == AFS_VNODE_LOCK_NONE &&
 538             !(fl->fl_flags & FL_SLEEP)) {
 539                 ret = -EAGAIN;
 540                 if (type == AFS_LOCK_READ) {
 541                         if (vnode->status.lock_count == -1)
 542                                 goto lock_is_contended; /* Write locked */
 543                 } else {
 544                         if (vnode->status.lock_count != 0)
 545                                 goto lock_is_contended; /* Locked */
 546                 }
 547         }
 548
 549         if (vnode->lock_state != AFS_VNODE_LOCK_NONE)
 550                 goto need_to_wait;
 551
 552 try_to_lock:
 553         /* We don't have a lock on this vnode and we aren't currently waiting
 554          * for one either, so ask the server for a lock.
 555          *
 556          * Note that we need to be careful if we get interrupted by a signal
 557          * after dispatching the request as we may still get the lock, even
 558          * though we don't wait for the reply (it's not too bad a problem - the
 559          * lock will expire in 5 mins anyway).
 560          */
 561         trace_afs_flock_ev(vnode, fl, afs_flock_try_to_lock, 0);
 562         vnode->lock_key = key_get(key);
 563         vnode->lock_type = type;
 564         afs_set_lock_state(vnode, AFS_VNODE_LOCK_SETTING);
 565         spin_unlock(&vnode->lock);
 566
 567         ret = afs_set_lock(vnode, key, type); /* RPC */
 568
 569         spin_lock(&vnode->lock);
 570         switch (ret) {
 571         case -EKEYREJECTED:
 572         case -EKEYEXPIRED:
 573         case -EKEYREVOKED:
 574         case -EPERM:
 575         case -EACCES:
 576                 fl->fl_u.afs.state = ret;
 577                 trace_afs_flock_ev(vnode, fl, afs_flock_fail_perm, ret);
 578                 list_del_init(&fl->fl_u.afs.link);
 579                 afs_next_locker(vnode, ret);
 580                 goto error_unlock;
 581
 582         case -ENOENT:
 583                 fl->fl_u.afs.state = ret;
 584                 trace_afs_flock_ev(vnode, fl, afs_flock_fail_other, ret);
 585                 list_del_init(&fl->fl_u.afs.link);
 586                 afs_kill_lockers_enoent(vnode);
 587                 goto error_unlock;
 588
 589         default:
 590                 fl->fl_u.afs.state = ret;
 591                 trace_afs_flock_ev(vnode, fl, afs_flock_fail_other, ret);
 592                 list_del_init(&fl->fl_u.afs.link);
 593                 afs_next_locker(vnode, 0);
 594                 goto error_unlock;
 595
 596         case -EWOULDBLOCK:
 597                 /* The server doesn't have a lock-waiting queue, so the client
 598                  * will have to retry.  The server will break the outstanding
 599                  * callbacks on a file when a lock is released.
 600                  */
 601                 ASSERT(list_empty(&vnode->granted_locks));
 602                 ASSERTCMP(vnode->pending_locks.next, ==, &fl->fl_u.afs.link);
 603                 goto lock_is_contended;
 604
 605         case 0:
 606                 afs_set_lock_state(vnode, AFS_VNODE_LOCK_GRANTED);
 607                 trace_afs_flock_ev(vnode, fl, afs_flock_acquired, type);
 608                 afs_grant_locks(vnode);
 609                 goto vnode_is_locked_u;
 610         }
 611
 612 vnode_is_locked_u:
 613         spin_unlock(&vnode->lock);
 614 vnode_is_locked:
 615         /* the lock has been granted by the server... */
 616         ASSERTCMP(fl->fl_u.afs.state, ==, AFS_LOCK_GRANTED);
 617
 618 skip_server_lock:
 619         /* ... but the VFS still needs to distribute access on this client. */
 620         trace_afs_flock_ev(vnode, fl, afs_flock_vfs_locking, 0);
 621         ret = locks_lock_file_wait(file, fl);
 622         trace_afs_flock_ev(vnode, fl, afs_flock_vfs_lock, ret);
 623         if (ret < 0)
 624                 goto vfs_rejected_lock;
 625
 626         /* Again, make sure we've got a callback on this file and, again, make
 627          * sure that our view of the data version is up to date (we ignore
 628          * errors incurred here and deal with the consequences elsewhere).
 629          */
 630         afs_validate(vnode, key);
 631         _leave(" = 0");
 632         return 0;
 633
 634 lock_is_contended:
 635         if (!(fl->fl_flags & FL_SLEEP)) {
 636                 list_del_init(&fl->fl_u.afs.link);
 637                 afs_next_locker(vnode, 0);
 638                 ret = -EAGAIN;
 639                 goto error_unlock;
 640         }
 641
 642         afs_set_lock_state(vnode, AFS_VNODE_LOCK_WAITING_FOR_CB);
 643         trace_afs_flock_ev(vnode, fl, afs_flock_would_block, ret);
 644         queue_delayed_work(afs_lock_manager, &vnode->lock_work, HZ * 5);
 645
 646 need_to_wait:
 647         /* We're going to have to wait.  Either this client doesn't have a lock
 648          * on the server yet and we need to wait for a callback to occur, or
 649          * the client does have a lock on the server, but it's shared and we
 650          * need an exclusive lock.
 651          */
 652         spin_unlock(&vnode->lock);
 653
 654         trace_afs_flock_ev(vnode, fl, afs_flock_waiting, 0);
 655         ret = wait_event_interruptible(fl->fl_wait,
 656                                        fl->fl_u.afs.state != AFS_LOCK_PENDING);
 657         trace_afs_flock_ev(vnode, fl, afs_flock_waited, ret);
 658
 659         if (fl->fl_u.afs.state >= 0 && fl->fl_u.afs.state != AFS_LOCK_GRANTED) {
 660                 spin_lock(&vnode->lock);
 661
 662                 switch (fl->fl_u.afs.state) {
 663                 case AFS_LOCK_YOUR_TRY:
 664                         fl->fl_u.afs.state = AFS_LOCK_PENDING;
 665                         goto try_to_lock;
 666                 case AFS_LOCK_PENDING:
 667                         if (ret > 0) {
 668                                 /* We need to retry the lock.  We may not be
 669                                  * notified by the server if it just expired
 670                                  * rather than being released.
 671                                  */
 672                                 ASSERTCMP(vnode->lock_state, ==, AFS_VNODE_LOCK_WAITING_FOR_CB);
 673                                 afs_set_lock_state(vnode, AFS_VNODE_LOCK_SETTING);
 674                                 fl->fl_u.afs.state = AFS_LOCK_PENDING;
 675                                 goto try_to_lock;
 676                         }
 677                         goto error_unlock;
 678                 case AFS_LOCK_GRANTED:
 679                 default:
 680                         break;
 681                 }
 682
 683                 spin_unlock(&vnode->lock);
 684         }
 685
 686         if (fl->fl_u.afs.state == AFS_LOCK_GRANTED)
 687                 goto vnode_is_locked;
 688         ret = fl->fl_u.afs.state;
 689         goto error;
 690
 691 vfs_rejected_lock:
 692         /* The VFS rejected the lock we just obtained, so we have to discard
 693          * what we just got.  We defer this to the lock manager work item to
 694          * deal with.
 695          */
 696         _debug("vfs refused %d", ret);
 697         if (no_server_lock)
 698                 goto error;
 699         spin_lock(&vnode->lock);
 700         list_del_init(&fl->fl_u.afs.link);
 701         afs_defer_unlock(vnode);
 702
 703 error_unlock:
 704         spin_unlock(&vnode->lock);
 705 error:
 706         _leave(" = %d", ret);
 707         return ret;
 708 }
 709
 710 /*
 711  * unlock on a file on the server
 712  */
 713 static int afs_do_unlk(struct file *file, struct file_lock *fl)
 714 {
 715         struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
 716         int ret;
 717
 718         _enter("{%llx:%llu},%u", vnode->fid.vid, vnode->fid.vnode, fl->fl_type);
 719
 720         trace_afs_flock_op(vnode, fl, afs_flock_op_unlock);
 721
 722         /* Flush all pending writes before doing anything with locks. */
 723         vfs_fsync(file, 0);
 724
 725         ret = locks_lock_file_wait(file, fl);
 726         _leave(" = %d [%u]", ret, vnode->lock_state);
 727         return ret;
 728 }
 729
 730 /*
 731  * return information about a lock we currently hold, if indeed we hold one
 732  */
 733 static int afs_do_getlk(struct file *file, struct file_lock *fl)
 734 {
 735         struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
 736         struct key *key = afs_file_key(file);
 737         int ret, lock_count;
 738
 739         _enter("");
 740
 741         if (vnode->lock_state == AFS_VNODE_LOCK_DELETED)
 742                 return -ENOENT;
 743
 744         fl->fl_type = F_UNLCK;
 745
 746         /* check local lock records first */
 747         posix_test_lock(file, fl);
 748         if (fl->fl_type == F_UNLCK) {
 749                 /* no local locks; consult the server */
 750                 ret = afs_fetch_status(vnode, key, false, NULL);
 751                 if (ret < 0)
 752                         goto error;
 753
 754                 lock_count = READ_ONCE(vnode->status.lock_count);
 755                 if (lock_count != 0) {
 756                         if (lock_count > 0)
 757                                 fl->fl_type = F_RDLCK;
 758                         else
 759                                 fl->fl_type = F_WRLCK;
 760                         fl->fl_start = 0;
 761                         fl->fl_end = OFFSET_MAX;
 762                         fl->fl_pid = 0;
 763                 }
 764         }
 765
 766         ret = 0;
 767 error:
 768         _leave(" = %d [%hd]", ret, fl->fl_type);
 769         return ret;
 770 }
 771
 772 /*
 773  * manage POSIX locks on a file
 774  */
 775 int afs_lock(struct file *file, int cmd, struct file_lock *fl)
 776 {
 777         struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
 778         enum afs_flock_operation op;
 779         int ret;
 780
 781         _enter("{%llx:%llu},%d,{t=%x,fl=%x,r=%Ld:%Ld}",
 782                vnode->fid.vid, vnode->fid.vnode, cmd,
 783                fl->fl_type, fl->fl_flags,
 784                (long long) fl->fl_start, (long long) fl->fl_end);
 785
 786         /* AFS doesn't support mandatory locks */
 787         if (__mandatory_lock(&vnode->vfs_inode) && fl->fl_type != F_UNLCK)
 788                 return -ENOLCK;
 789
 790         if (IS_GETLK(cmd))
 791                 return afs_do_getlk(file, fl);
 792
 793         fl->fl_u.afs.debug_id = atomic_inc_return(&afs_file_lock_debug_id);
 794         trace_afs_flock_op(vnode, fl, afs_flock_op_lock);
 795
 796         if (fl->fl_type == F_UNLCK)
 797                 ret = afs_do_unlk(file, fl);
 798         else
 799                 ret = afs_do_setlk(file, fl);
 800
 801         switch (ret) {
 802         case 0:         op = afs_flock_op_return_ok; break;
 803         case -EAGAIN:   op = afs_flock_op_return_eagain; break;
 804         case -EDEADLK:  op = afs_flock_op_return_edeadlk; break;
 805         default:        op = afs_flock_op_return_error; break;
 806         }
 807         trace_afs_flock_op(vnode, fl, op);
 808         return ret;
 809 }
 810
 811 /*
 812  * manage FLOCK locks on a file
 813  */
 814 int afs_flock(struct file *file, int cmd, struct file_lock *fl)
 815 {
 816         struct afs_vnode *vnode = AFS_FS_I(locks_inode(file));
 817         enum afs_flock_operation op;
 818         int ret;
 819
 820         _enter("{%llx:%llu},%d,{t=%x,fl=%x}",
 821                vnode->fid.vid, vnode->fid.vnode, cmd,
 822                fl->fl_type, fl->fl_flags);
 823
 824         /*
 825          * No BSD flocks over NFS allowed.
 826          * Note: we could try to fake a POSIX lock request here by
 827          * using ((u32) filp | 0x80000000) or some such as the pid.
 828          * Not sure whether that would be unique, though, or whether
 829          * that would break in other places.
 830          */
 831         if (!(fl->fl_flags & FL_FLOCK))
 832                 return -ENOLCK;
 833
 834         fl->fl_u.afs.debug_id = atomic_inc_return(&afs_file_lock_debug_id);
 835         trace_afs_flock_op(vnode, fl, afs_flock_op_flock);
 836
 837         /* we're simulating flock() locks using posix locks on the server */
 838         if (fl->fl_type == F_UNLCK)
 839                 ret = afs_do_unlk(file, fl);
 840         else
 841                 ret = afs_do_setlk(file, fl);
 842
 843         switch (ret) {
 844         case 0:         op = afs_flock_op_return_ok; break;
 845         case -EAGAIN:   op = afs_flock_op_return_eagain; break;
 846         case -EDEADLK:  op = afs_flock_op_return_edeadlk; break;
 847         default:        op = afs_flock_op_return_error; break;
 848         }
 849         trace_afs_flock_op(vnode, fl, op);
 850         return ret;
 851 }
 852
 853 /*
 854  * the POSIX lock management core VFS code copies the lock record and adds the
 855  * copy into its own list, so we need to add that copy to the vnode's lock
 856  * queue in the same place as the original (which will be deleted shortly
 857  * after)
 858  */
 859 static void afs_fl_copy_lock(struct file_lock *new, struct file_lock *fl)
 860 {
 861         struct afs_vnode *vnode = AFS_FS_I(locks_inode(fl->fl_file));
 862
 863         _enter("");
 864
 865         new->fl_u.afs.debug_id = atomic_inc_return(&afs_file_lock_debug_id);
 866
 867         spin_lock(&vnode->lock);
 868         trace_afs_flock_op(vnode, new, afs_flock_op_copy_lock);
 869         list_add(&new->fl_u.afs.link, &fl->fl_u.afs.link);
 870         spin_unlock(&vnode->lock);
 871 }
 872
 873 /*
 874  * need to remove this lock from the vnode queue when it's removed from the
 875  * VFS's list
 876  */
 877 static void afs_fl_release_private(struct file_lock *fl)
 878 {
 879         struct afs_vnode *vnode = AFS_FS_I(locks_inode(fl->fl_file));
 880
 881         _enter("");
 882
 883         spin_lock(&vnode->lock);
 884
 885         trace_afs_flock_op(vnode, fl, afs_flock_op_release_lock);
 886         list_del_init(&fl->fl_u.afs.link);
 887         if (list_empty(&vnode->granted_locks))
 888                 afs_defer_unlock(vnode);
 889
 890         _debug("state %u for %p", vnode->lock_state, vnode);
 891         spin_unlock(&vnode->lock);
 892 }