fs/gfs2/glock.c

   1 /*
   2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   3  * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
   4  *
   5  * This copyrighted material is made available to anyone wishing to use,
   6  * modify, copy, or redistribute it subject to the terms and conditions
   7  * of the GNU General Public License v.2.
   8  */
   9
  10 #include <linux/sched.h>
  11 #include <linux/slab.h>
  12 #include <linux/spinlock.h>
  13 #include <linux/completion.h>
  14 #include <linux/buffer_head.h>
  15 #include <linux/delay.h>
  16 #include <linux/sort.h>
  17 #include <linux/jhash.h>
  18 #include <linux/kref.h>
  19 #include <linux/kallsyms.h>
  20 #include <linux/gfs2_ondisk.h>
  21 #include <asm/uaccess.h>
  22
  23 #include "gfs2.h"
  24 #include "lm_interface.h"
  25 #include "incore.h"
  26 #include "glock.h"
  27 #include "glops.h"
  28 #include "inode.h"
  29 #include "lm.h"
  30 #include "lops.h"
  31 #include "meta_io.h"
  32 #include "quota.h"
  33 #include "super.h"
  34 #include "util.h"
  35
  36 /*  Must be kept in sync with the beginning of struct gfs2_glock  */
  37 struct glock_plug {
  38         struct list_head gl_list;
  39         unsigned long gl_flags;
  40 };
  41
  42 struct greedy {
  43         struct gfs2_holder gr_gh;
  44         struct work_struct gr_work;
  45 };
  46
  47 typedef void (*glock_examiner) (struct gfs2_glock * gl);
  48
  49 static int gfs2_dump_lockstate(struct gfs2_sbd *sdp);
  50 static int dump_glock(struct gfs2_glock *gl);
  51
  52 /**
  53  * relaxed_state_ok - is a requested lock compatible with the current lock mode?
  54  * @actual: the current state of the lock
  55  * @requested: the lock state that was requested by the caller
  56  * @flags: the modifier flags passed in by the caller
  57  *
  58  * Returns: 1 if the locks are compatible, 0 otherwise
  59  */
  60
  61 static inline int relaxed_state_ok(unsigned int actual, unsigned requested,
  62                                    int flags)
  63 {
  64         if (actual == requested)
  65                 return 1;
  66
  67         if (flags & GL_EXACT)
  68                 return 0;
  69
  70         if (actual == LM_ST_EXCLUSIVE && requested == LM_ST_SHARED)
  71                 return 1;
  72
  73         if (actual != LM_ST_UNLOCKED && (flags & LM_FLAG_ANY))
  74                 return 1;
  75
  76         return 0;
  77 }
  78
  79 /**
  80  * gl_hash() - Turn glock number into hash bucket number
  81  * @lock: The glock number
  82  *
  83  * Returns: The number of the corresponding hash bucket
  84  */
  85
  86 static unsigned int gl_hash(struct lm_lockname *name)
  87 {
  88         unsigned int h;
  89
  90         h = jhash(&name->ln_number, sizeof(uint64_t), 0);
  91         h = jhash(&name->ln_type, sizeof(unsigned int), h);
  92         h &= GFS2_GL_HASH_MASK;
  93
  94         return h;
  95 }
  96
  97 /**
  98  * glock_free() - Perform a few checks and then release struct gfs2_glock
  99  * @gl: The glock to release
 100  *
 101  * Also calls lock module to release its internal structure for this glock.
 102  *
 103  */
 104
 105 static void glock_free(struct gfs2_glock *gl)
 106 {
 107         struct gfs2_sbd *sdp = gl->gl_sbd;
 108         struct inode *aspace = gl->gl_aspace;
 109
 110         gfs2_lm_put_lock(sdp, gl->gl_lock);
 111
 112         if (aspace)
 113                 gfs2_aspace_put(aspace);
 114
 115         kmem_cache_free(gfs2_glock_cachep, gl);
 116 }
 117
 118 /**
 119  * gfs2_glock_hold() - increment reference count on glock
 120  * @gl: The glock to hold
 121  *
 122  */
 123
 124 void gfs2_glock_hold(struct gfs2_glock *gl)
 125 {
 126         kref_get(&gl->gl_ref);
 127 }
 128
 129 /* All work is done after the return from kref_put() so we
 130    can release the write_lock before the free. */
 131
 132 static void kill_glock(struct kref *kref)
 133 {
 134         struct gfs2_glock *gl = container_of(kref, struct gfs2_glock, gl_ref);
 135         struct gfs2_sbd *sdp = gl->gl_sbd;
 136
 137         gfs2_assert(sdp, gl->gl_state == LM_ST_UNLOCKED);
 138         gfs2_assert(sdp, list_empty(&gl->gl_reclaim));
 139         gfs2_assert(sdp, list_empty(&gl->gl_holders));
 140         gfs2_assert(sdp, list_empty(&gl->gl_waiters1));
 141         gfs2_assert(sdp, list_empty(&gl->gl_waiters2));
 142         gfs2_assert(sdp, list_empty(&gl->gl_waiters3));
 143 }
 144
 145 /**
 146  * gfs2_glock_put() - Decrement reference count on glock
 147  * @gl: The glock to put
 148  *
 149  */
 150
 151 int gfs2_glock_put(struct gfs2_glock *gl)
 152 {
 153         struct gfs2_sbd *sdp = gl->gl_sbd;
 154         struct gfs2_gl_hash_bucket *bucket = gl->gl_bucket;
 155         int rv = 0;
 156
 157         mutex_lock(&sdp->sd_invalidate_inodes_mutex);
 158
 159         write_lock(&bucket->hb_lock);
 160         if (kref_put(&gl->gl_ref, kill_glock)) {
 161                 list_del_init(&gl->gl_list);
 162                 write_unlock(&bucket->hb_lock);
 163                 BUG_ON(spin_is_locked(&gl->gl_spin));
 164                 glock_free(gl);
 165                 rv = 1;
 166                 goto out;
 167         }
 168         write_unlock(&bucket->hb_lock);
 169  out:
 170         mutex_unlock(&sdp->sd_invalidate_inodes_mutex);
 171         return rv;
 172 }
 173
 174 /**
 175  * queue_empty - check to see if a glock's queue is empty
 176  * @gl: the glock
 177  * @head: the head of the queue to check
 178  *
 179  * This function protects the list in the event that a process already
 180  * has a holder on the list and is adding a second holder for itself.
 181  * The glmutex lock is what generally prevents processes from working
 182  * on the same glock at once, but the special case of adding a second
 183  * holder for yourself ("recursive" locking) doesn't involve locking
 184  * glmutex, making the spin lock necessary.
 185  *
 186  * Returns: 1 if the queue is empty
 187  */
 188
 189 static inline int queue_empty(struct gfs2_glock *gl, struct list_head *head)
 190 {
 191         int empty;
 192         spin_lock(&gl->gl_spin);
 193         empty = list_empty(head);
 194         spin_unlock(&gl->gl_spin);
 195         return empty;
 196 }
 197
 198 /**
 199  * search_bucket() - Find struct gfs2_glock by lock number
 200  * @bucket: the bucket to search
 201  * @name: The lock name
 202  *
 203  * Returns: NULL, or the struct gfs2_glock with the requested number
 204  */
 205
 206 static struct gfs2_glock *search_bucket(struct gfs2_gl_hash_bucket *bucket,
 207                                         struct lm_lockname *name)
 208 {
 209         struct gfs2_glock *gl;
 210
 211         list_for_each_entry(gl, &bucket->hb_list, gl_list) {
 212                 if (test_bit(GLF_PLUG, &gl->gl_flags))
 213                         continue;
 214                 if (!lm_name_equal(&gl->gl_name, name))
 215                         continue;
 216
 217                 kref_get(&gl->gl_ref);
 218
 219                 return gl;
 220         }
 221
 222         return NULL;
 223 }
 224
 225 /**
 226  * gfs2_glock_find() - Find glock by lock number
 227  * @sdp: The GFS2 superblock
 228  * @name: The lock name
 229  *
 230  * Returns: NULL, or the struct gfs2_glock with the requested number
 231  */
 232
 233 static struct gfs2_glock *gfs2_glock_find(struct gfs2_sbd *sdp,
 234                                           struct lm_lockname *name)
 235 {
 236         struct gfs2_gl_hash_bucket *bucket = &sdp->sd_gl_hash[gl_hash(name)];
 237         struct gfs2_glock *gl;
 238
 239         read_lock(&bucket->hb_lock);
 240         gl = search_bucket(bucket, name);
 241         read_unlock(&bucket->hb_lock);
 242
 243         return gl;
 244 }
 245
 246 /**
 247  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
 248  * @sdp: The GFS2 superblock
 249  * @number: the lock number
 250  * @glops: The glock_operations to use
 251  * @create: If 0, don't create the glock if it doesn't exist
 252  * @glp: the glock is returned here
 253  *
 254  * This does not lock a glock, just finds/creates structures for one.
 255  *
 256  * Returns: errno
 257  */
 258
 259 int gfs2_glock_get(struct gfs2_sbd *sdp, uint64_t number,
 260                    struct gfs2_glock_operations *glops, int create,
 261                    struct gfs2_glock **glp)
 262 {
 263         struct lm_lockname name;
 264         struct gfs2_glock *gl, *tmp;
 265         struct gfs2_gl_hash_bucket *bucket;
 266         int error;
 267
 268         name.ln_number = number;
 269         name.ln_type = glops->go_type;
 270         bucket = &sdp->sd_gl_hash[gl_hash(&name)];
 271
 272         read_lock(&bucket->hb_lock);
 273         gl = search_bucket(bucket, &name);
 274         read_unlock(&bucket->hb_lock);
 275
 276         if (gl || !create) {
 277                 *glp = gl;
 278                 return 0;
 279         }
 280
 281         gl = kmem_cache_alloc(gfs2_glock_cachep, GFP_KERNEL);
 282         if (!gl)
 283                 return -ENOMEM;
 284
 285         memset(gl, 0, sizeof(struct gfs2_glock));
 286
 287         INIT_LIST_HEAD(&gl->gl_list);
 288         gl->gl_name = name;
 289         kref_init(&gl->gl_ref);
 290
 291         spin_lock_init(&gl->gl_spin);
 292
 293         gl->gl_state = LM_ST_UNLOCKED;
 294         gl->gl_owner = NULL;
 295         gl->gl_ip = 0;
 296         INIT_LIST_HEAD(&gl->gl_holders);
 297         INIT_LIST_HEAD(&gl->gl_waiters1);
 298         INIT_LIST_HEAD(&gl->gl_waiters2);
 299         INIT_LIST_HEAD(&gl->gl_waiters3);
 300
 301         gl->gl_ops = glops;
 302
 303         gl->gl_bucket = bucket;
 304         INIT_LIST_HEAD(&gl->gl_reclaim);
 305
 306         gl->gl_sbd = sdp;
 307
 308         lops_init_le(&gl->gl_le, &gfs2_glock_lops);
 309         INIT_LIST_HEAD(&gl->gl_ail_list);
 310
 311         /* If this glock protects actual on-disk data or metadata blocks,
 312            create a VFS inode to manage the pages/buffers holding them. */
 313         if (glops == &gfs2_inode_glops ||
 314             glops == &gfs2_rgrp_glops) {
 315                 gl->gl_aspace = gfs2_aspace_get(sdp);
 316                 if (!gl->gl_aspace) {
 317                         error = -ENOMEM;
 318                         goto fail;
 319                 }
 320         }
 321
 322         error = gfs2_lm_get_lock(sdp, &name, &gl->gl_lock);
 323         if (error)
 324                 goto fail_aspace;
 325
 326         write_lock(&bucket->hb_lock);
 327         tmp = search_bucket(bucket, &name);
 328         if (tmp) {
 329                 write_unlock(&bucket->hb_lock);
 330                 glock_free(gl);
 331                 gl = tmp;
 332         } else {
 333                 list_add_tail(&gl->gl_list, &bucket->hb_list);
 334                 write_unlock(&bucket->hb_lock);
 335         }
 336
 337         *glp = gl;
 338
 339         return 0;
 340
 341  fail_aspace:
 342         if (gl->gl_aspace)
 343                 gfs2_aspace_put(gl->gl_aspace);
 344
 345  fail:
 346         kmem_cache_free(gfs2_glock_cachep, gl);
 347
 348         return error;
 349 }
 350
 351 /**
 352  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
 353  * @gl: the glock
 354  * @state: the state we're requesting
 355  * @flags: the modifier flags
 356  * @gh: the holder structure
 357  *
 358  */
 359
 360 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
 361                       struct gfs2_holder *gh)
 362 {
 363         INIT_LIST_HEAD(&gh->gh_list);
 364         gh->gh_gl = gl;
 365         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 366         gh->gh_owner = current;
 367         gh->gh_state = state;
 368         gh->gh_flags = flags;
 369         gh->gh_error = 0;
 370         gh->gh_iflags = 0;
 371         init_completion(&gh->gh_wait);
 372
 373         if (gh->gh_state == LM_ST_EXCLUSIVE)
 374                 gh->gh_flags |= GL_LOCAL_EXCL;
 375
 376         gfs2_glock_hold(gl);
 377 }
 378
 379 /**
 380  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
 381  * @state: the state we're requesting
 382  * @flags: the modifier flags
 383  * @gh: the holder structure
 384  *
 385  * Don't mess with the glock.
 386  *
 387  */
 388
 389 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
 390 {
 391         gh->gh_state = state;
 392         gh->gh_flags = flags;
 393         if (gh->gh_state == LM_ST_EXCLUSIVE)
 394                 gh->gh_flags |= GL_LOCAL_EXCL;
 395
 396         gh->gh_iflags &= 1 << HIF_ALLOCED;
 397         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 398 }
 399
 400 /**
 401  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 402  * @gh: the holder structure
 403  *
 404  */
 405
 406 void gfs2_holder_uninit(struct gfs2_holder *gh)
 407 {
 408         gfs2_glock_put(gh->gh_gl);
 409         gh->gh_gl = NULL;
 410         gh->gh_ip = 0;
 411 }
 412
 413 /**
 414  * gfs2_holder_get - get a struct gfs2_holder structure
 415  * @gl: the glock
 416  * @state: the state we're requesting
 417  * @flags: the modifier flags
 418  * @gfp_flags:
 419  *
 420  * Figure out how big an impact this function has.  Either:
 421  * 1) Replace it with a cache of structures hanging off the struct gfs2_sbd
 422  * 2) Leave it like it is
 423  *
 424  * Returns: the holder structure, NULL on ENOMEM
 425  */
 426
 427 static struct gfs2_holder *gfs2_holder_get(struct gfs2_glock *gl,
 428                                            unsigned int state,
 429                                            int flags, gfp_t gfp_flags)
 430 {
 431         struct gfs2_holder *gh;
 432
 433         gh = kmalloc(sizeof(struct gfs2_holder), gfp_flags);
 434         if (!gh)
 435                 return NULL;
 436
 437         gfs2_holder_init(gl, state, flags, gh);
 438         set_bit(HIF_ALLOCED, &gh->gh_iflags);
 439         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 440         return gh;
 441 }
 442
 443 /**
 444  * gfs2_holder_put - get rid of a struct gfs2_holder structure
 445  * @gh: the holder structure
 446  *
 447  */
 448
 449 static void gfs2_holder_put(struct gfs2_holder *gh)
 450 {
 451         gfs2_holder_uninit(gh);
 452         kfree(gh);
 453 }
 454
 455 /**
 456  * rq_mutex - process a mutex request in the queue
 457  * @gh: the glock holder
 458  *
 459  * Returns: 1 if the queue is blocked
 460  */
 461
 462 static int rq_mutex(struct gfs2_holder *gh)
 463 {
 464         struct gfs2_glock *gl = gh->gh_gl;
 465
 466         list_del_init(&gh->gh_list);
 467         /*  gh->gh_error never examined.  */
 468         set_bit(GLF_LOCK, &gl->gl_flags);
 469         complete(&gh->gh_wait);
 470
 471         return 1;
 472 }
 473
 474 /**
 475  * rq_promote - process a promote request in the queue
 476  * @gh: the glock holder
 477  *
 478  * Acquire a new inter-node lock, or change a lock state to more restrictive.
 479  *
 480  * Returns: 1 if the queue is blocked
 481  */
 482
 483 static int rq_promote(struct gfs2_holder *gh)
 484 {
 485         struct gfs2_glock *gl = gh->gh_gl;
 486         struct gfs2_sbd *sdp = gl->gl_sbd;
 487         struct gfs2_glock_operations *glops = gl->gl_ops;
 488
 489         if (!relaxed_state_ok(gl->gl_state, gh->gh_state, gh->gh_flags)) {
 490                 if (list_empty(&gl->gl_holders)) {
 491                         gl->gl_req_gh = gh;
 492                         set_bit(GLF_LOCK, &gl->gl_flags);
 493                         spin_unlock(&gl->gl_spin);
 494
 495                         if (atomic_read(&sdp->sd_reclaim_count) >
 496                             gfs2_tune_get(sdp, gt_reclaim_limit) &&
 497                             !(gh->gh_flags & LM_FLAG_PRIORITY)) {
 498                                 gfs2_reclaim_glock(sdp);
 499                                 gfs2_reclaim_glock(sdp);
 500                         }
 501
 502                         glops->go_xmote_th(gl, gh->gh_state,
 503                                            gh->gh_flags);
 504
 505                         spin_lock(&gl->gl_spin);
 506                 }
 507                 return 1;
 508         }
 509
 510         if (list_empty(&gl->gl_holders)) {
 511                 set_bit(HIF_FIRST, &gh->gh_iflags);
 512                 set_bit(GLF_LOCK, &gl->gl_flags);
 513         } else {
 514                 struct gfs2_holder *next_gh;
 515                 if (gh->gh_flags & GL_LOCAL_EXCL)
 516                         return 1;
 517                 next_gh = list_entry(gl->gl_holders.next, struct gfs2_holder,
 518                                      gh_list);
 519                 if (next_gh->gh_flags & GL_LOCAL_EXCL)
 520                          return 1;
 521         }
 522
 523         list_move_tail(&gh->gh_list, &gl->gl_holders);
 524         gh->gh_error = 0;
 525         set_bit(HIF_HOLDER, &gh->gh_iflags);
 526
 527         complete(&gh->gh_wait);
 528
 529         return 0;
 530 }
 531
 532 /**
 533  * rq_demote - process a demote request in the queue
 534  * @gh: the glock holder
 535  *
 536  * Returns: 1 if the queue is blocked
 537  */
 538
 539 static int rq_demote(struct gfs2_holder *gh)
 540 {
 541         struct gfs2_glock *gl = gh->gh_gl;
 542         struct gfs2_glock_operations *glops = gl->gl_ops;
 543
 544         if (!list_empty(&gl->gl_holders))
 545                 return 1;
 546
 547         if (gl->gl_state == gh->gh_state || gl->gl_state == LM_ST_UNLOCKED) {
 548                 list_del_init(&gh->gh_list);
 549                 gh->gh_error = 0;
 550                 spin_unlock(&gl->gl_spin);
 551                 if (test_bit(HIF_DEALLOC, &gh->gh_iflags))
 552                         gfs2_holder_put(gh);
 553                 else
 554                         complete(&gh->gh_wait);
 555                 spin_lock(&gl->gl_spin);
 556         } else {
 557                 gl->gl_req_gh = gh;
 558                 set_bit(GLF_LOCK, &gl->gl_flags);
 559                 spin_unlock(&gl->gl_spin);
 560
 561                 if (gh->gh_state == LM_ST_UNLOCKED ||
 562                     gl->gl_state != LM_ST_EXCLUSIVE)
 563                         glops->go_drop_th(gl);
 564                 else
 565                         glops->go_xmote_th(gl, gh->gh_state, gh->gh_flags);
 566
 567                 spin_lock(&gl->gl_spin);
 568         }
 569
 570         return 0;
 571 }
 572
 573 /**
 574  * rq_greedy - process a queued request to drop greedy status
 575  * @gh: the glock holder
 576  *
 577  * Returns: 1 if the queue is blocked
 578  */
 579
 580 static int rq_greedy(struct gfs2_holder *gh)
 581 {
 582         struct gfs2_glock *gl = gh->gh_gl;
 583
 584         list_del_init(&gh->gh_list);
 585         /*  gh->gh_error never examined.  */
 586         clear_bit(GLF_GREEDY, &gl->gl_flags);
 587         spin_unlock(&gl->gl_spin);
 588
 589         gfs2_holder_uninit(gh);
 590         kfree(container_of(gh, struct greedy, gr_gh));
 591
 592         spin_lock(&gl->gl_spin);
 593
 594         return 0;
 595 }
 596
 597 /**
 598  * run_queue - process holder structures on a glock
 599  * @gl: the glock
 600  *
 601  */
 602 static void run_queue(struct gfs2_glock *gl)
 603 {
 604         struct gfs2_holder *gh;
 605         int blocked = 1;
 606
 607         for (;;) {
 608                 if (test_bit(GLF_LOCK, &gl->gl_flags))
 609                         break;
 610
 611                 if (!list_empty(&gl->gl_waiters1)) {
 612                         gh = list_entry(gl->gl_waiters1.next,
 613                                         struct gfs2_holder, gh_list);
 614
 615                         if (test_bit(HIF_MUTEX, &gh->gh_iflags))
 616                                 blocked = rq_mutex(gh);
 617                         else
 618                                 gfs2_assert_warn(gl->gl_sbd, 0);
 619
 620                 } else if (!list_empty(&gl->gl_waiters2) &&
 621                            !test_bit(GLF_SKIP_WAITERS2, &gl->gl_flags)) {
 622                         gh = list_entry(gl->gl_waiters2.next,
 623                                         struct gfs2_holder, gh_list);
 624
 625                         if (test_bit(HIF_DEMOTE, &gh->gh_iflags))
 626                                 blocked = rq_demote(gh);
 627                         else if (test_bit(HIF_GREEDY, &gh->gh_iflags))
 628                                 blocked = rq_greedy(gh);
 629                         else
 630                                 gfs2_assert_warn(gl->gl_sbd, 0);
 631
 632                 } else if (!list_empty(&gl->gl_waiters3)) {
 633                         gh = list_entry(gl->gl_waiters3.next,
 634                                         struct gfs2_holder, gh_list);
 635
 636                         if (test_bit(HIF_PROMOTE, &gh->gh_iflags))
 637                                 blocked = rq_promote(gh);
 638                         else
 639                                 gfs2_assert_warn(gl->gl_sbd, 0);
 640
 641                 } else
 642                         break;
 643
 644                 if (blocked)
 645                         break;
 646         }
 647 }
 648
 649 /**
 650  * gfs2_glmutex_lock - acquire a local lock on a glock
 651  * @gl: the glock
 652  *
 653  * Gives caller exclusive access to manipulate a glock structure.
 654  */
 655
 656 static void gfs2_glmutex_lock(struct gfs2_glock *gl)
 657 {
 658         struct gfs2_holder gh;
 659
 660         gfs2_holder_init(gl, 0, 0, &gh);
 661         set_bit(HIF_MUTEX, &gh.gh_iflags);
 662
 663         spin_lock(&gl->gl_spin);
 664         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 665                 list_add_tail(&gh.gh_list, &gl->gl_waiters1);
 666         else {
 667                 gl->gl_owner = current;
 668                 gl->gl_ip = (unsigned long)__builtin_return_address(0);
 669                 complete(&gh.gh_wait);
 670         }
 671         spin_unlock(&gl->gl_spin);
 672
 673         wait_for_completion(&gh.gh_wait);
 674         gfs2_holder_uninit(&gh);
 675 }
 676
 677 /**
 678  * gfs2_glmutex_trylock - try to acquire a local lock on a glock
 679  * @gl: the glock
 680  *
 681  * Returns: 1 if the glock is acquired
 682  */
 683
 684 static int gfs2_glmutex_trylock(struct gfs2_glock *gl)
 685 {
 686         int acquired = 1;
 687
 688         spin_lock(&gl->gl_spin);
 689         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 690                 acquired = 0;
 691         else {
 692                 gl->gl_owner = current;
 693                 gl->gl_ip = (unsigned long)__builtin_return_address(0);
 694         }
 695         spin_unlock(&gl->gl_spin);
 696
 697         return acquired;
 698 }
 699
 700 /**
 701  * gfs2_glmutex_unlock - release a local lock on a glock
 702  * @gl: the glock
 703  *
 704  */
 705
 706 static void gfs2_glmutex_unlock(struct gfs2_glock *gl)
 707 {
 708         spin_lock(&gl->gl_spin);
 709         clear_bit(GLF_LOCK, &gl->gl_flags);
 710         gl->gl_owner = NULL;
 711         gl->gl_ip = 0;
 712         run_queue(gl);
 713         BUG_ON(!spin_is_locked(&gl->gl_spin));
 714         spin_unlock(&gl->gl_spin);
 715 }
 716
 717 /**
 718  * handle_callback - add a demote request to a lock's queue
 719  * @gl: the glock
 720  * @state: the state the caller wants us to change to
 721  *
 722  * Note: This may fail sliently if we are out of memory.
 723  */
 724
 725 static void handle_callback(struct gfs2_glock *gl, unsigned int state)
 726 {
 727         struct gfs2_holder *gh, *new_gh = NULL;
 728
 729 restart:
 730         spin_lock(&gl->gl_spin);
 731
 732         list_for_each_entry(gh, &gl->gl_waiters2, gh_list) {
 733                 if (test_bit(HIF_DEMOTE, &gh->gh_iflags) &&
 734                     gl->gl_req_gh != gh) {
 735                         if (gh->gh_state != state)
 736                                 gh->gh_state = LM_ST_UNLOCKED;
 737                         goto out;
 738                 }
 739         }
 740
 741         if (new_gh) {
 742                 list_add_tail(&new_gh->gh_list, &gl->gl_waiters2);
 743                 new_gh = NULL;
 744         } else {
 745                 spin_unlock(&gl->gl_spin);
 746
 747                 new_gh = gfs2_holder_get(gl, state, LM_FLAG_TRY, GFP_KERNEL);
 748                 if (!new_gh)
 749                         return;
 750                 set_bit(HIF_DEMOTE, &new_gh->gh_iflags);
 751                 set_bit(HIF_DEALLOC, &new_gh->gh_iflags);
 752
 753                 goto restart;
 754         }
 755
 756 out:
 757         spin_unlock(&gl->gl_spin);
 758
 759         if (new_gh)
 760                 gfs2_holder_put(new_gh);
 761 }
 762
 763 void gfs2_glock_inode_squish(struct inode *inode)
 764 {
 765         struct gfs2_holder gh;
 766         struct gfs2_glock *gl = GFS2_I(inode)->i_gl;
 767         gfs2_holder_init(gl, LM_ST_UNLOCKED, 0, &gh);
 768         set_bit(HIF_DEMOTE, &gh.gh_iflags);
 769         spin_lock(&gl->gl_spin);
 770         gfs2_assert(inode->i_sb->s_fs_info, list_empty(&gl->gl_holders));
 771         list_add_tail(&gh.gh_list, &gl->gl_waiters2);
 772         run_queue(gl);
 773         spin_unlock(&gl->gl_spin);
 774         wait_for_completion(&gh.gh_wait);
 775         gfs2_holder_uninit(&gh);
 776 }
 777
 778 /**
 779  * state_change - record that the glock is now in a different state
 780  * @gl: the glock
 781  * @new_state the new state
 782  *
 783  */
 784
 785 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 786 {
 787         int held1, held2;
 788
 789         held1 = (gl->gl_state != LM_ST_UNLOCKED);
 790         held2 = (new_state != LM_ST_UNLOCKED);
 791
 792         if (held1 != held2) {
 793                 if (held2)
 794                         gfs2_glock_hold(gl);
 795                 else
 796                         gfs2_glock_put(gl);
 797         }
 798
 799         gl->gl_state = new_state;
 800 }
 801
 802 /**
 803  * xmote_bh - Called after the lock module is done acquiring a lock
 804  * @gl: The glock in question
 805  * @ret: the int returned from the lock module
 806  *
 807  */
 808
 809 static void xmote_bh(struct gfs2_glock *gl, unsigned int ret)
 810 {
 811         struct gfs2_sbd *sdp = gl->gl_sbd;
 812         struct gfs2_glock_operations *glops = gl->gl_ops;
 813         struct gfs2_holder *gh = gl->gl_req_gh;
 814         int prev_state = gl->gl_state;
 815         int op_done = 1;
 816
 817         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
 818         gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
 819         gfs2_assert_warn(sdp, !(ret & LM_OUT_ASYNC));
 820
 821         state_change(gl, ret & LM_OUT_ST_MASK);
 822
 823         if (prev_state != LM_ST_UNLOCKED && !(ret & LM_OUT_CACHEABLE)) {
 824                 if (glops->go_inval)
 825                         glops->go_inval(gl, DIO_METADATA | DIO_DATA);
 826         } else if (gl->gl_state == LM_ST_DEFERRED) {
 827                 /* We might not want to do this here.
 828                    Look at moving to the inode glops. */
 829                 if (glops->go_inval)
 830                         glops->go_inval(gl, DIO_DATA);
 831         }
 832
 833         /*  Deal with each possible exit condition  */
 834
 835         if (!gh)
 836                 gl->gl_stamp = jiffies;
 837
 838         else if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
 839                 spin_lock(&gl->gl_spin);
 840                 list_del_init(&gh->gh_list);
 841                 gh->gh_error = -EIO;
 842                 spin_unlock(&gl->gl_spin);
 843
 844         } else if (test_bit(HIF_DEMOTE, &gh->gh_iflags)) {
 845                 spin_lock(&gl->gl_spin);
 846                 list_del_init(&gh->gh_list);
 847                 if (gl->gl_state == gh->gh_state ||
 848                     gl->gl_state == LM_ST_UNLOCKED)
 849                         gh->gh_error = 0;
 850                 else {
 851                         if (gfs2_assert_warn(sdp, gh->gh_flags &
 852                                         (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) == -1)
 853                                 fs_warn(sdp, "ret = 0x%.8X\n", ret);
 854                         gh->gh_error = GLR_TRYFAILED;
 855                 }
 856                 spin_unlock(&gl->gl_spin);
 857
 858                 if (ret & LM_OUT_CANCELED)
 859                         handle_callback(gl, LM_ST_UNLOCKED); /* Lame */
 860
 861         } else if (ret & LM_OUT_CANCELED) {
 862                 spin_lock(&gl->gl_spin);
 863                 list_del_init(&gh->gh_list);
 864                 gh->gh_error = GLR_CANCELED;
 865                 spin_unlock(&gl->gl_spin);
 866
 867         } else if (relaxed_state_ok(gl->gl_state, gh->gh_state, gh->gh_flags)) {
 868                 spin_lock(&gl->gl_spin);
 869                 list_move_tail(&gh->gh_list, &gl->gl_holders);
 870                 gh->gh_error = 0;
 871                 set_bit(HIF_HOLDER, &gh->gh_iflags);
 872                 spin_unlock(&gl->gl_spin);
 873
 874                 set_bit(HIF_FIRST, &gh->gh_iflags);
 875
 876                 op_done = 0;
 877
 878         } else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
 879                 spin_lock(&gl->gl_spin);
 880                 list_del_init(&gh->gh_list);
 881                 gh->gh_error = GLR_TRYFAILED;
 882                 spin_unlock(&gl->gl_spin);
 883
 884         } else {
 885                 if (gfs2_assert_withdraw(sdp, 0) == -1)
 886                         fs_err(sdp, "ret = 0x%.8X\n", ret);
 887         }
 888
 889         if (glops->go_xmote_bh)
 890                 glops->go_xmote_bh(gl);
 891
 892         if (op_done) {
 893                 spin_lock(&gl->gl_spin);
 894                 gl->gl_req_gh = NULL;
 895                 gl->gl_req_bh = NULL;
 896                 clear_bit(GLF_LOCK, &gl->gl_flags);
 897                 run_queue(gl);
 898                 spin_unlock(&gl->gl_spin);
 899         }
 900
 901         gfs2_glock_put(gl);
 902
 903         if (gh) {
 904                 if (test_bit(HIF_DEALLOC, &gh->gh_iflags))
 905                         gfs2_holder_put(gh);
 906                 else
 907                         complete(&gh->gh_wait);
 908         }
 909 }
 910
 911 /**
 912  * gfs2_glock_xmote_th - Call into the lock module to acquire or change a glock
 913  * @gl: The glock in question
 914  * @state: the requested state
 915  * @flags: modifier flags to the lock call
 916  *
 917  */
 918
 919 void gfs2_glock_xmote_th(struct gfs2_glock *gl, unsigned int state, int flags)
 920 {
 921         struct gfs2_sbd *sdp = gl->gl_sbd;
 922         struct gfs2_glock_operations *glops = gl->gl_ops;
 923         int lck_flags = flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB |
 924                                  LM_FLAG_NOEXP | LM_FLAG_ANY |
 925                                  LM_FLAG_PRIORITY);
 926         unsigned int lck_ret;
 927
 928         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
 929         gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
 930         gfs2_assert_warn(sdp, state != LM_ST_UNLOCKED);
 931         gfs2_assert_warn(sdp, state != gl->gl_state);
 932
 933         if (gl->gl_state == LM_ST_EXCLUSIVE) {
 934                 if (glops->go_sync)
 935                         glops->go_sync(gl,
 936                                        DIO_METADATA | DIO_DATA | DIO_RELEASE);
 937         }
 938
 939         gfs2_glock_hold(gl);
 940         gl->gl_req_bh = xmote_bh;
 941
 942         lck_ret = gfs2_lm_lock(sdp, gl->gl_lock, gl->gl_state, state,
 943                                lck_flags);
 944
 945         if (gfs2_assert_withdraw(sdp, !(lck_ret & LM_OUT_ERROR)))
 946                 return;
 947
 948         if (lck_ret & LM_OUT_ASYNC)
 949                 gfs2_assert_warn(sdp, lck_ret == LM_OUT_ASYNC);
 950         else
 951                 xmote_bh(gl, lck_ret);
 952 }
 953
 954 /**
 955  * drop_bh - Called after a lock module unlock completes
 956  * @gl: the glock
 957  * @ret: the return status
 958  *
 959  * Doesn't wake up the process waiting on the struct gfs2_holder (if any)
 960  * Doesn't drop the reference on the glock the top half took out
 961  *
 962  */
 963
 964 static void drop_bh(struct gfs2_glock *gl, unsigned int ret)
 965 {
 966         struct gfs2_sbd *sdp = gl->gl_sbd;
 967         struct gfs2_glock_operations *glops = gl->gl_ops;
 968         struct gfs2_holder *gh = gl->gl_req_gh;
 969
 970         clear_bit(GLF_PREFETCH, &gl->gl_flags);
 971
 972         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
 973         gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
 974         gfs2_assert_warn(sdp, !ret);
 975
 976         state_change(gl, LM_ST_UNLOCKED);
 977
 978         if (glops->go_inval)
 979                 glops->go_inval(gl, DIO_METADATA | DIO_DATA);
 980
 981         if (gh) {
 982                 spin_lock(&gl->gl_spin);
 983                 list_del_init(&gh->gh_list);
 984                 gh->gh_error = 0;
 985                 spin_unlock(&gl->gl_spin);
 986         }
 987
 988         if (glops->go_drop_bh)
 989                 glops->go_drop_bh(gl);
 990
 991         spin_lock(&gl->gl_spin);
 992         gl->gl_req_gh = NULL;
 993         gl->gl_req_bh = NULL;
 994         clear_bit(GLF_LOCK, &gl->gl_flags);
 995         run_queue(gl);
 996         spin_unlock(&gl->gl_spin);
 997
 998         gfs2_glock_put(gl);
 999
1000         if (gh) {
1001                 if (test_bit(HIF_DEALLOC, &gh->gh_iflags))
1002                         gfs2_holder_put(gh);
1003                 else
1004                         complete(&gh->gh_wait);
1005         }
1006 }
1007
1008 /**
1009  * gfs2_glock_drop_th - call into the lock module to unlock a lock
1010  * @gl: the glock
1011  *
1012  */
1013
1014 void gfs2_glock_drop_th(struct gfs2_glock *gl)
1015 {
1016         struct gfs2_sbd *sdp = gl->gl_sbd;
1017         struct gfs2_glock_operations *glops = gl->gl_ops;
1018         unsigned int ret;
1019
1020         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
1021         gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
1022         gfs2_assert_warn(sdp, gl->gl_state != LM_ST_UNLOCKED);
1023
1024         if (gl->gl_state == LM_ST_EXCLUSIVE) {
1025                 if (glops->go_sync)
1026                         glops->go_sync(gl,
1027                                        DIO_METADATA | DIO_DATA | DIO_RELEASE);
1028         }
1029
1030         gfs2_glock_hold(gl);
1031         gl->gl_req_bh = drop_bh;
1032
1033         ret = gfs2_lm_unlock(sdp, gl->gl_lock, gl->gl_state);
1034
1035         if (gfs2_assert_withdraw(sdp, !(ret & LM_OUT_ERROR)))
1036                 return;
1037
1038         if (!ret)
1039                 drop_bh(gl, ret);
1040         else
1041                 gfs2_assert_warn(sdp, ret == LM_OUT_ASYNC);
1042 }
1043
1044 /**
1045  * do_cancels - cancel requests for locks stuck waiting on an expire flag
1046  * @gh: the LM_FLAG_PRIORITY holder waiting to acquire the lock
1047  *
1048  * Don't cancel GL_NOCANCEL requests.
1049  */
1050
1051 static void do_cancels(struct gfs2_holder *gh)
1052 {
1053         struct gfs2_glock *gl = gh->gh_gl;
1054
1055         spin_lock(&gl->gl_spin);
1056
1057         while (gl->gl_req_gh != gh &&
1058                !test_bit(HIF_HOLDER, &gh->gh_iflags) &&
1059                !list_empty(&gh->gh_list)) {
1060                 if (gl->gl_req_bh &&
1061                     !(gl->gl_req_gh &&
1062                       (gl->gl_req_gh->gh_flags & GL_NOCANCEL))) {
1063                         spin_unlock(&gl->gl_spin);
1064                         gfs2_lm_cancel(gl->gl_sbd, gl->gl_lock);
1065                         msleep(100);
1066                         spin_lock(&gl->gl_spin);
1067                 } else {
1068                         spin_unlock(&gl->gl_spin);
1069                         msleep(100);
1070                         spin_lock(&gl->gl_spin);
1071                 }
1072         }
1073
1074         spin_unlock(&gl->gl_spin);
1075 }
1076
1077 /**
1078  * glock_wait_internal - wait on a glock acquisition
1079  * @gh: the glock holder
1080  *
1081  * Returns: 0 on success
1082  */
1083
1084 static int glock_wait_internal(struct gfs2_holder *gh)
1085 {
1086         struct gfs2_glock *gl = gh->gh_gl;
1087         struct gfs2_sbd *sdp = gl->gl_sbd;
1088         struct gfs2_glock_operations *glops = gl->gl_ops;
1089
1090         if (test_bit(HIF_ABORTED, &gh->gh_iflags))
1091                 return -EIO;
1092
1093         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
1094                 spin_lock(&gl->gl_spin);
1095                 if (gl->gl_req_gh != gh &&
1096                     !test_bit(HIF_HOLDER, &gh->gh_iflags) &&
1097                     !list_empty(&gh->gh_list)) {
1098                         list_del_init(&gh->gh_list);
1099                         gh->gh_error = GLR_TRYFAILED;
1100                         run_queue(gl);
1101                         spin_unlock(&gl->gl_spin);
1102                         return gh->gh_error;
1103                 }
1104                 spin_unlock(&gl->gl_spin);
1105         }
1106
1107         if (gh->gh_flags & LM_FLAG_PRIORITY)
1108                 do_cancels(gh);
1109
1110         wait_for_completion(&gh->gh_wait);
1111
1112         if (gh->gh_error)
1113                 return gh->gh_error;
1114
1115         gfs2_assert_withdraw(sdp, test_bit(HIF_HOLDER, &gh->gh_iflags));
1116         gfs2_assert_withdraw(sdp, relaxed_state_ok(gl->gl_state,
1117                                                    gh->gh_state,
1118                                                    gh->gh_flags));
1119
1120         if (test_bit(HIF_FIRST, &gh->gh_iflags)) {
1121                 gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
1122
1123                 if (glops->go_lock) {
1124                         gh->gh_error = glops->go_lock(gh);
1125                         if (gh->gh_error) {
1126                                 spin_lock(&gl->gl_spin);
1127                                 list_del_init(&gh->gh_list);
1128                                 spin_unlock(&gl->gl_spin);
1129                         }
1130                 }
1131
1132                 spin_lock(&gl->gl_spin);
1133                 gl->gl_req_gh = NULL;
1134                 gl->gl_req_bh = NULL;
1135                 clear_bit(GLF_LOCK, &gl->gl_flags);
1136                 run_queue(gl);
1137                 spin_unlock(&gl->gl_spin);
1138         }
1139
1140         return gh->gh_error;
1141 }
1142
1143 static inline struct gfs2_holder *
1144 find_holder_by_owner(struct list_head *head, struct task_struct *owner)
1145 {
1146         struct gfs2_holder *gh;
1147
1148         list_for_each_entry(gh, head, gh_list) {
1149                 if (gh->gh_owner == owner)
1150                         return gh;
1151         }
1152
1153         return NULL;
1154 }
1155
1156 /**
1157  * add_to_queue - Add a holder to the wait queue (but look for recursion)
1158  * @gh: the holder structure to add
1159  *
1160  */
1161
1162 static void add_to_queue(struct gfs2_holder *gh)
1163 {
1164         struct gfs2_glock *gl = gh->gh_gl;
1165         struct gfs2_holder *existing;
1166
1167         BUG_ON(!gh->gh_owner);
1168
1169         existing = find_holder_by_owner(&gl->gl_holders, gh->gh_owner);
1170         if (existing) {
1171                 print_symbol(KERN_WARNING "original: %s\n", existing->gh_ip);
1172                 print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
1173                 BUG();
1174         }
1175
1176         existing = find_holder_by_owner(&gl->gl_waiters3, gh->gh_owner);
1177         if (existing) {
1178                 print_symbol(KERN_WARNING "original: %s\n", existing->gh_ip);
1179                 print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
1180                 BUG();
1181         }
1182
1183         if (gh->gh_flags & LM_FLAG_PRIORITY)
1184                 list_add(&gh->gh_list, &gl->gl_waiters3);
1185         else
1186                 list_add_tail(&gh->gh_list, &gl->gl_waiters3);
1187 }
1188
1189 /**
1190  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1191  * @gh: the holder structure
1192  *
1193  * if (gh->gh_flags & GL_ASYNC), this never returns an error
1194  *
1195  * Returns: 0, GLR_TRYFAILED, or errno on failure
1196  */
1197
1198 int gfs2_glock_nq(struct gfs2_holder *gh)
1199 {
1200         struct gfs2_glock *gl = gh->gh_gl;
1201         struct gfs2_sbd *sdp = gl->gl_sbd;
1202         int error = 0;
1203
1204 restart:
1205         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
1206                 set_bit(HIF_ABORTED, &gh->gh_iflags);
1207                 return -EIO;
1208         }
1209
1210         set_bit(HIF_PROMOTE, &gh->gh_iflags);
1211
1212         spin_lock(&gl->gl_spin);
1213         add_to_queue(gh);
1214         run_queue(gl);
1215         spin_unlock(&gl->gl_spin);
1216
1217         if (!(gh->gh_flags & GL_ASYNC)) {
1218                 error = glock_wait_internal(gh);
1219                 if (error == GLR_CANCELED) {
1220                         msleep(100);
1221                         goto restart;
1222                 }
1223         }
1224
1225         clear_bit(GLF_PREFETCH, &gl->gl_flags);
1226
1227         if (error == GLR_TRYFAILED && (gh->gh_flags & GL_DUMP))
1228                 dump_glock(gl);
1229
1230         return error;
1231 }
1232
1233 /**
1234  * gfs2_glock_poll - poll to see if an async request has been completed
1235  * @gh: the holder
1236  *
1237  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1238  */
1239
1240 int gfs2_glock_poll(struct gfs2_holder *gh)
1241 {
1242         struct gfs2_glock *gl = gh->gh_gl;
1243         int ready = 0;
1244
1245         spin_lock(&gl->gl_spin);
1246
1247         if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1248                 ready = 1;
1249         else if (list_empty(&gh->gh_list)) {
1250                 if (gh->gh_error == GLR_CANCELED) {
1251                         spin_unlock(&gl->gl_spin);
1252                         msleep(100);
1253                         if (gfs2_glock_nq(gh))
1254                                 return 1;
1255                         return 0;
1256                 } else
1257                         ready = 1;
1258         }
1259
1260         spin_unlock(&gl->gl_spin);
1261
1262         return ready;
1263 }
1264
1265 /**
1266  * gfs2_glock_wait - wait for a lock acquisition that ended in a GLR_ASYNC
1267  * @gh: the holder structure
1268  *
1269  * Returns: 0, GLR_TRYFAILED, or errno on failure
1270  */
1271
1272 int gfs2_glock_wait(struct gfs2_holder *gh)
1273 {
1274         int error;
1275
1276         error = glock_wait_internal(gh);
1277         if (error == GLR_CANCELED) {
1278                 msleep(100);
1279                 gh->gh_flags &= ~GL_ASYNC;
1280                 error = gfs2_glock_nq(gh);
1281         }
1282
1283         return error;
1284 }
1285
1286 /**
1287  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1288  * @gh: the glock holder
1289  *
1290  */
1291
1292 void gfs2_glock_dq(struct gfs2_holder *gh)
1293 {
1294         struct gfs2_glock *gl = gh->gh_gl;
1295         struct gfs2_glock_operations *glops = gl->gl_ops;
1296
1297         if (gh->gh_flags & GL_SYNC)
1298                 set_bit(GLF_SYNC, &gl->gl_flags);
1299
1300         if (gh->gh_flags & GL_NOCACHE)
1301                 handle_callback(gl, LM_ST_UNLOCKED);
1302
1303         gfs2_glmutex_lock(gl);
1304
1305         spin_lock(&gl->gl_spin);
1306         list_del_init(&gh->gh_list);
1307
1308         if (list_empty(&gl->gl_holders)) {
1309                 spin_unlock(&gl->gl_spin);
1310
1311                 if (glops->go_unlock)
1312                         glops->go_unlock(gh);
1313
1314                 if (test_bit(GLF_SYNC, &gl->gl_flags)) {
1315                         if (glops->go_sync)
1316                                 glops->go_sync(gl, DIO_METADATA | DIO_DATA);
1317                 }
1318
1319                 gl->gl_stamp = jiffies;
1320
1321                 spin_lock(&gl->gl_spin);
1322         }
1323
1324         clear_bit(GLF_LOCK, &gl->gl_flags);
1325         run_queue(gl);
1326         spin_unlock(&gl->gl_spin);
1327 }
1328
1329 /**
1330  * gfs2_glock_prefetch - Try to prefetch a glock
1331  * @gl: the glock
1332  * @state: the state to prefetch in
1333  * @flags: flags passed to go_xmote_th()
1334  *
1335  */
1336
1337 static void gfs2_glock_prefetch(struct gfs2_glock *gl, unsigned int state,
1338                                 int flags)
1339 {
1340         struct gfs2_glock_operations *glops = gl->gl_ops;
1341
1342         spin_lock(&gl->gl_spin);
1343
1344         if (test_bit(GLF_LOCK, &gl->gl_flags) ||
1345             !list_empty(&gl->gl_holders) ||
1346             !list_empty(&gl->gl_waiters1) ||
1347             !list_empty(&gl->gl_waiters2) ||
1348             !list_empty(&gl->gl_waiters3) ||
1349             relaxed_state_ok(gl->gl_state, state, flags)) {
1350                 spin_unlock(&gl->gl_spin);
1351                 return;
1352         }
1353
1354         set_bit(GLF_PREFETCH, &gl->gl_flags);
1355         set_bit(GLF_LOCK, &gl->gl_flags);
1356         spin_unlock(&gl->gl_spin);
1357
1358         glops->go_xmote_th(gl, state, flags);
1359 }
1360
1361 static void greedy_work(void *data)
1362 {
1363         struct greedy *gr = data;
1364         struct gfs2_holder *gh = &gr->gr_gh;
1365         struct gfs2_glock *gl = gh->gh_gl;
1366         struct gfs2_glock_operations *glops = gl->gl_ops;
1367
1368         clear_bit(GLF_SKIP_WAITERS2, &gl->gl_flags);
1369
1370         if (glops->go_greedy)
1371                 glops->go_greedy(gl);
1372
1373         spin_lock(&gl->gl_spin);
1374
1375         if (list_empty(&gl->gl_waiters2)) {
1376                 clear_bit(GLF_GREEDY, &gl->gl_flags);
1377                 spin_unlock(&gl->gl_spin);
1378                 gfs2_holder_uninit(gh);
1379                 kfree(gr);
1380         } else {
1381                 gfs2_glock_hold(gl);
1382                 list_add_tail(&gh->gh_list, &gl->gl_waiters2);
1383                 run_queue(gl);
1384                 spin_unlock(&gl->gl_spin);
1385                 gfs2_glock_put(gl);
1386         }
1387 }
1388
1389 /**
1390  * gfs2_glock_be_greedy -
1391  * @gl:
1392  * @time:
1393  *
1394  * Returns: 0 if go_greedy will be called, 1 otherwise
1395  */
1396
1397 int gfs2_glock_be_greedy(struct gfs2_glock *gl, unsigned int time)
1398 {
1399         struct greedy *gr;
1400         struct gfs2_holder *gh;
1401
1402         if (!time || gl->gl_sbd->sd_args.ar_localcaching ||
1403             test_and_set_bit(GLF_GREEDY, &gl->gl_flags))
1404                 return 1;
1405
1406         gr = kmalloc(sizeof(struct greedy), GFP_KERNEL);
1407         if (!gr) {
1408                 clear_bit(GLF_GREEDY, &gl->gl_flags);
1409                 return 1;
1410         }
1411         gh = &gr->gr_gh;
1412
1413         gfs2_holder_init(gl, 0, 0, gh);
1414         set_bit(HIF_GREEDY, &gh->gh_iflags);
1415         INIT_WORK(&gr->gr_work, greedy_work, gr);
1416
1417         set_bit(GLF_SKIP_WAITERS2, &gl->gl_flags);
1418         schedule_delayed_work(&gr->gr_work, time);
1419
1420         return 0;
1421 }
1422
1423 /**
1424  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1425  * @gh: the holder structure
1426  *
1427  */
1428
1429 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1430 {
1431         gfs2_glock_dq(gh);
1432         gfs2_holder_uninit(gh);
1433 }
1434
1435 /**
1436  * gfs2_glock_nq_num - acquire a glock based on lock number
1437  * @sdp: the filesystem
1438  * @number: the lock number
1439  * @glops: the glock operations for the type of glock
1440  * @state: the state to acquire the glock in
1441  * @flags: modifier flags for the aquisition
1442  * @gh: the struct gfs2_holder
1443  *
1444  * Returns: errno
1445  */
1446
1447 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, uint64_t number,
1448                       struct gfs2_glock_operations *glops, unsigned int state,
1449                       int flags, struct gfs2_holder *gh)
1450 {
1451         struct gfs2_glock *gl;
1452         int error;
1453
1454         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1455         if (!error) {
1456                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1457                 gfs2_glock_put(gl);
1458         }
1459
1460         return error;
1461 }
1462
1463 /**
1464  * glock_compare - Compare two struct gfs2_glock structures for sorting
1465  * @arg_a: the first structure
1466  * @arg_b: the second structure
1467  *
1468  */
1469
1470 static int glock_compare(const void *arg_a, const void *arg_b)
1471 {
1472         struct gfs2_holder *gh_a = *(struct gfs2_holder **)arg_a;
1473         struct gfs2_holder *gh_b = *(struct gfs2_holder **)arg_b;
1474         struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1475         struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1476         int ret = 0;
1477
1478         if (a->ln_number > b->ln_number)
1479                 ret = 1;
1480         else if (a->ln_number < b->ln_number)
1481                 ret = -1;
1482         else {
1483                 if (gh_a->gh_state == LM_ST_SHARED &&
1484                     gh_b->gh_state == LM_ST_EXCLUSIVE)
1485                         ret = 1;
1486                 else if (!(gh_a->gh_flags & GL_LOCAL_EXCL) &&
1487                          (gh_b->gh_flags & GL_LOCAL_EXCL))
1488                         ret = 1;
1489         }
1490
1491         return ret;
1492 }
1493
1494 /**
1495  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1496  * @num_gh: the number of structures
1497  * @ghs: an array of struct gfs2_holder structures
1498  *
1499  * Returns: 0 on success (all glocks acquired),
1500  *          errno on failure (no glocks acquired)
1501  */
1502
1503 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1504                      struct gfs2_holder **p)
1505 {
1506         unsigned int x;
1507         int error = 0;
1508
1509         for (x = 0; x < num_gh; x++)
1510                 p[x] = &ghs[x];
1511
1512         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1513
1514         for (x = 0; x < num_gh; x++) {
1515                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1516
1517                 error = gfs2_glock_nq(p[x]);
1518                 if (error) {
1519                         while (x--)
1520                                 gfs2_glock_dq(p[x]);
1521                         break;
1522                 }
1523         }
1524
1525         return error;
1526 }
1527
1528 /**
1529  * gfs2_glock_nq_m - acquire multiple glocks
1530  * @num_gh: the number of structures
1531  * @ghs: an array of struct gfs2_holder structures
1532  *
1533  * Figure out how big an impact this function has.  Either:
1534  * 1) Replace this code with code that calls gfs2_glock_prefetch()
1535  * 2) Forget async stuff and just call nq_m_sync()
1536  * 3) Leave it like it is
1537  *
1538  * Returns: 0 on success (all glocks acquired),
1539  *          errno on failure (no glocks acquired)
1540  */
1541
1542 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1543 {
1544         int *e;
1545         unsigned int x;
1546         int borked = 0, serious = 0;
1547         int error = 0;
1548
1549         if (!num_gh)
1550                 return 0;
1551
1552         if (num_gh == 1) {
1553                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1554                 return gfs2_glock_nq(ghs);
1555         }
1556
1557         e = kcalloc(num_gh, sizeof(struct gfs2_holder *), GFP_KERNEL);
1558         if (!e)
1559                 return -ENOMEM;
1560
1561         for (x = 0; x < num_gh; x++) {
1562                 ghs[x].gh_flags |= LM_FLAG_TRY | GL_ASYNC;
1563                 error = gfs2_glock_nq(&ghs[x]);
1564                 if (error) {
1565                         borked = 1;
1566                         serious = error;
1567                         num_gh = x;
1568                         break;
1569                 }
1570         }
1571
1572         for (x = 0; x < num_gh; x++) {
1573                 error = e[x] = glock_wait_internal(&ghs[x]);
1574                 if (error) {
1575                         borked = 1;
1576                         if (error != GLR_TRYFAILED && error != GLR_CANCELED)
1577                                 serious = error;
1578                 }
1579         }
1580
1581         if (!borked) {
1582                 kfree(e);
1583                 return 0;
1584         }
1585
1586         for (x = 0; x < num_gh; x++)
1587                 if (!e[x])
1588                         gfs2_glock_dq(&ghs[x]);
1589
1590         if (serious)
1591                 error = serious;
1592         else {
1593                 for (x = 0; x < num_gh; x++)
1594                         gfs2_holder_reinit(ghs[x].gh_state, ghs[x].gh_flags,
1595                                           &ghs[x]);
1596                 error = nq_m_sync(num_gh, ghs, (struct gfs2_holder **)e);
1597         }
1598
1599         kfree(e);
1600
1601         return error;
1602 }
1603
1604 /**
1605  * gfs2_glock_dq_m - release multiple glocks
1606  * @num_gh: the number of structures
1607  * @ghs: an array of struct gfs2_holder structures
1608  *
1609  */
1610
1611 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1612 {
1613         unsigned int x;
1614
1615         for (x = 0; x < num_gh; x++)
1616                 gfs2_glock_dq(&ghs[x]);
1617 }
1618
1619 /**
1620  * gfs2_glock_dq_uninit_m - release multiple glocks
1621  * @num_gh: the number of structures
1622  * @ghs: an array of struct gfs2_holder structures
1623  *
1624  */
1625
1626 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1627 {
1628         unsigned int x;
1629
1630         for (x = 0; x < num_gh; x++)
1631                 gfs2_glock_dq_uninit(&ghs[x]);
1632 }
1633
1634 /**
1635  * gfs2_glock_prefetch_num - prefetch a glock based on lock number
1636  * @sdp: the filesystem
1637  * @number: the lock number
1638  * @glops: the glock operations for the type of glock
1639  * @state: the state to acquire the glock in
1640  * @flags: modifier flags for the aquisition
1641  *
1642  * Returns: errno
1643  */
1644
1645 void gfs2_glock_prefetch_num(struct gfs2_sbd *sdp, uint64_t number,
1646                              struct gfs2_glock_operations *glops,
1647                              unsigned int state, int flags)
1648 {
1649         struct gfs2_glock *gl;
1650         int error;
1651
1652         if (atomic_read(&sdp->sd_reclaim_count) <
1653             gfs2_tune_get(sdp, gt_reclaim_limit)) {
1654                 error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1655                 if (!error) {
1656                         gfs2_glock_prefetch(gl, state, flags);
1657                         gfs2_glock_put(gl);
1658                 }
1659         }
1660 }
1661
1662 /**
1663  * gfs2_lvb_hold - attach a LVB from a glock
1664  * @gl: The glock in question
1665  *
1666  */
1667
1668 int gfs2_lvb_hold(struct gfs2_glock *gl)
1669 {
1670         int error;
1671
1672         gfs2_glmutex_lock(gl);
1673
1674         if (!atomic_read(&gl->gl_lvb_count)) {
1675                 error = gfs2_lm_hold_lvb(gl->gl_sbd, gl->gl_lock, &gl->gl_lvb);
1676                 if (error) {
1677                         gfs2_glmutex_unlock(gl);
1678                         return error;
1679                 }
1680                 gfs2_glock_hold(gl);
1681         }
1682         atomic_inc(&gl->gl_lvb_count);
1683
1684         gfs2_glmutex_unlock(gl);
1685
1686         return 0;
1687 }
1688
1689 /**
1690  * gfs2_lvb_unhold - detach a LVB from a glock
1691  * @gl: The glock in question
1692  *
1693  */
1694
1695 void gfs2_lvb_unhold(struct gfs2_glock *gl)
1696 {
1697         gfs2_glock_hold(gl);
1698         gfs2_glmutex_lock(gl);
1699
1700         gfs2_assert(gl->gl_sbd, atomic_read(&gl->gl_lvb_count) > 0);
1701         if (atomic_dec_and_test(&gl->gl_lvb_count)) {
1702                 gfs2_lm_unhold_lvb(gl->gl_sbd, gl->gl_lock, gl->gl_lvb);
1703                 gl->gl_lvb = NULL;
1704                 gfs2_glock_put(gl);
1705         }
1706
1707         gfs2_glmutex_unlock(gl);
1708         gfs2_glock_put(gl);
1709 }
1710
1711 #if 0
1712 void gfs2_lvb_sync(struct gfs2_glock *gl)
1713 {
1714         gfs2_glmutex_lock(gl);
1715
1716         gfs2_assert(gl->gl_sbd, atomic_read(&gl->gl_lvb_count));
1717         if (!gfs2_assert_warn(gl->gl_sbd, gfs2_glock_is_held_excl(gl)))
1718                 gfs2_lm_sync_lvb(gl->gl_sbd, gl->gl_lock, gl->gl_lvb);
1719
1720         gfs2_glmutex_unlock(gl);
1721 }
1722 #endif  /*  0  */
1723
1724 static void blocking_cb(struct gfs2_sbd *sdp, struct lm_lockname *name,
1725                         unsigned int state)
1726 {
1727         struct gfs2_glock *gl;
1728
1729         gl = gfs2_glock_find(sdp, name);
1730         if (!gl)
1731                 return;
1732
1733         if (gl->gl_ops->go_callback)
1734                 gl->gl_ops->go_callback(gl, state);
1735         handle_callback(gl, state);
1736
1737         spin_lock(&gl->gl_spin);
1738         run_queue(gl);
1739         spin_unlock(&gl->gl_spin);
1740
1741         gfs2_glock_put(gl);
1742 }
1743
1744 /**
1745  * gfs2_glock_cb - Callback used by locking module
1746  * @fsdata: Pointer to the superblock
1747  * @type: Type of callback
1748  * @data: Type dependent data pointer
1749  *
1750  * Called by the locking module when it wants to tell us something.
1751  * Either we need to drop a lock, one of our ASYNC requests completed, or
1752  * a journal from another client needs to be recovered.
1753  */
1754
1755 void gfs2_glock_cb(lm_fsdata_t *fsdata, unsigned int type, void *data)
1756 {
1757         struct gfs2_sbd *sdp = (struct gfs2_sbd *)fsdata;
1758
1759         switch (type) {
1760         case LM_CB_NEED_E:
1761                 blocking_cb(sdp, data, LM_ST_UNLOCKED);
1762                 return;
1763
1764         case LM_CB_NEED_D:
1765                 blocking_cb(sdp, data, LM_ST_DEFERRED);
1766                 return;
1767
1768         case LM_CB_NEED_S:
1769                 blocking_cb(sdp, data, LM_ST_SHARED);
1770                 return;
1771
1772         case LM_CB_ASYNC: {
1773                 struct lm_async_cb *async = data;
1774                 struct gfs2_glock *gl;
1775
1776                 gl = gfs2_glock_find(sdp, &async->lc_name);
1777                 if (gfs2_assert_warn(sdp, gl))
1778                         return;
1779                 if (!gfs2_assert_warn(sdp, gl->gl_req_bh))
1780                         gl->gl_req_bh(gl, async->lc_ret);
1781                 gfs2_glock_put(gl);
1782                 return;
1783         }
1784
1785         case LM_CB_NEED_RECOVERY:
1786                 gfs2_jdesc_make_dirty(sdp, *(unsigned int *)data);
1787                 if (sdp->sd_recoverd_process)
1788                         wake_up_process(sdp->sd_recoverd_process);
1789                 return;
1790
1791         case LM_CB_DROPLOCKS:
1792                 gfs2_gl_hash_clear(sdp, NO_WAIT);
1793                 gfs2_quota_scan(sdp);
1794                 return;
1795
1796         default:
1797                 gfs2_assert_warn(sdp, 0);
1798                 return;
1799         }
1800 }
1801
1802 /**
1803  * gfs2_iopen_go_callback - Try to kick the inode/vnode associated with an
1804  *                          iopen glock from memory
1805  * @io_gl: the iopen glock
1806  * @state: the state into which the glock should be put
1807  *
1808  */
1809
1810 void gfs2_iopen_go_callback(struct gfs2_glock *io_gl, unsigned int state)
1811 {
1812
1813         if (state != LM_ST_UNLOCKED)
1814                 return;
1815         /* FIXME: remove this? */
1816 }
1817
1818 /**
1819  * demote_ok - Check to see if it's ok to unlock a glock
1820  * @gl: the glock
1821  *
1822  * Returns: 1 if it's ok
1823  */
1824
1825 static int demote_ok(struct gfs2_glock *gl)
1826 {
1827         struct gfs2_sbd *sdp = gl->gl_sbd;
1828         struct gfs2_glock_operations *glops = gl->gl_ops;
1829         int demote = 1;
1830
1831         if (test_bit(GLF_STICKY, &gl->gl_flags))
1832                 demote = 0;
1833         else if (test_bit(GLF_PREFETCH, &gl->gl_flags))
1834                 demote = time_after_eq(jiffies,
1835                                     gl->gl_stamp +
1836                                     gfs2_tune_get(sdp, gt_prefetch_secs) * HZ);
1837         else if (glops->go_demote_ok)
1838                 demote = glops->go_demote_ok(gl);
1839
1840         return demote;
1841 }
1842
1843 /**
1844  * gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
1845  * @gl: the glock
1846  *
1847  */
1848
1849 void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
1850 {
1851         struct gfs2_sbd *sdp = gl->gl_sbd;
1852
1853         spin_lock(&sdp->sd_reclaim_lock);
1854         if (list_empty(&gl->gl_reclaim)) {
1855                 gfs2_glock_hold(gl);
1856                 list_add(&gl->gl_reclaim, &sdp->sd_reclaim_list);
1857                 atomic_inc(&sdp->sd_reclaim_count);
1858         }
1859         spin_unlock(&sdp->sd_reclaim_lock);
1860
1861         wake_up(&sdp->sd_reclaim_wq);
1862 }
1863
1864 /**
1865  * gfs2_reclaim_glock - process the next glock on the filesystem's reclaim list
1866  * @sdp: the filesystem
1867  *
1868  * Called from gfs2_glockd() glock reclaim daemon, or when promoting a
1869  * different glock and we notice that there are a lot of glocks in the
1870  * reclaim list.
1871  *
1872  */
1873
1874 void gfs2_reclaim_glock(struct gfs2_sbd *sdp)
1875 {
1876         struct gfs2_glock *gl;
1877
1878         spin_lock(&sdp->sd_reclaim_lock);
1879         if (list_empty(&sdp->sd_reclaim_list)) {
1880                 spin_unlock(&sdp->sd_reclaim_lock);
1881                 return;
1882         }
1883         gl = list_entry(sdp->sd_reclaim_list.next,
1884                         struct gfs2_glock, gl_reclaim);
1885         list_del_init(&gl->gl_reclaim);
1886         spin_unlock(&sdp->sd_reclaim_lock);
1887
1888         atomic_dec(&sdp->sd_reclaim_count);
1889         atomic_inc(&sdp->sd_reclaimed);
1890
1891         if (gfs2_glmutex_trylock(gl)) {
1892                 if (queue_empty(gl, &gl->gl_holders) &&
1893                     gl->gl_state != LM_ST_UNLOCKED &&
1894                     demote_ok(gl))
1895                         handle_callback(gl, LM_ST_UNLOCKED);
1896                 gfs2_glmutex_unlock(gl);
1897         }
1898
1899         gfs2_glock_put(gl);
1900 }
1901
1902 /**
1903  * examine_bucket - Call a function for glock in a hash bucket
1904  * @examiner: the function
1905  * @sdp: the filesystem
1906  * @bucket: the bucket
1907  *
1908  * Returns: 1 if the bucket has entries
1909  */
1910
1911 static int examine_bucket(glock_examiner examiner, struct gfs2_sbd *sdp,
1912                           struct gfs2_gl_hash_bucket *bucket)
1913 {
1914         struct glock_plug plug;
1915         struct list_head *tmp;
1916         struct gfs2_glock *gl;
1917         int entries;
1918
1919         /* Add "plug" to end of bucket list, work back up list from there */
1920         memset(&plug.gl_flags, 0, sizeof(unsigned long));
1921         set_bit(GLF_PLUG, &plug.gl_flags);
1922
1923         write_lock(&bucket->hb_lock);
1924         list_add(&plug.gl_list, &bucket->hb_list);
1925         write_unlock(&bucket->hb_lock);
1926
1927         for (;;) {
1928                 write_lock(&bucket->hb_lock);
1929
1930                 for (;;) {
1931                         tmp = plug.gl_list.next;
1932
1933                         if (tmp == &bucket->hb_list) {
1934                                 list_del(&plug.gl_list);
1935                                 entries = !list_empty(&bucket->hb_list);
1936                                 write_unlock(&bucket->hb_lock);
1937                                 return entries;
1938                         }
1939                         gl = list_entry(tmp, struct gfs2_glock, gl_list);
1940
1941                         /* Move plug up list */
1942                         list_move(&plug.gl_list, &gl->gl_list);
1943
1944                         if (test_bit(GLF_PLUG, &gl->gl_flags))
1945                                 continue;
1946
1947                         /* examiner() must glock_put() */
1948                         gfs2_glock_hold(gl);
1949
1950                         break;
1951                 }
1952
1953                 write_unlock(&bucket->hb_lock);
1954
1955                 examiner(gl);
1956         }
1957 }
1958
1959 /**
1960  * scan_glock - look at a glock and see if we can reclaim it
1961  * @gl: the glock to look at
1962  *
1963  */
1964
1965 static void scan_glock(struct gfs2_glock *gl)
1966 {
1967         if (gfs2_glmutex_trylock(gl)) {
1968                 if (gl->gl_ops == &gfs2_inode_glops)
1969                         goto out;
1970                 if (queue_empty(gl, &gl->gl_holders) &&
1971                     gl->gl_state != LM_ST_UNLOCKED &&
1972                     demote_ok(gl))
1973                         goto out_schedule;
1974 out:
1975                 gfs2_glmutex_unlock(gl);
1976         }
1977
1978         gfs2_glock_put(gl);
1979
1980         return;
1981
1982 out_schedule:
1983         gfs2_glmutex_unlock(gl);
1984         gfs2_glock_schedule_for_reclaim(gl);
1985         gfs2_glock_put(gl);
1986 }
1987
1988 /**
1989  * gfs2_scand_internal - Look for glocks and inodes to toss from memory
1990  * @sdp: the filesystem
1991  *
1992  */
1993
1994 void gfs2_scand_internal(struct gfs2_sbd *sdp)
1995 {
1996         unsigned int x;
1997
1998         for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
1999                 examine_bucket(scan_glock, sdp, &sdp->sd_gl_hash[x]);
2000                 cond_resched();
2001         }
2002 }
2003
2004 /**
2005  * clear_glock - look at a glock and see if we can free it from glock cache
2006  * @gl: the glock to look at
2007  *
2008  */
2009
2010 static void clear_glock(struct gfs2_glock *gl)
2011 {
2012         struct gfs2_sbd *sdp = gl->gl_sbd;
2013         int released;
2014
2015         spin_lock(&sdp->sd_reclaim_lock);
2016         if (!list_empty(&gl->gl_reclaim)) {
2017                 list_del_init(&gl->gl_reclaim);
2018                 atomic_dec(&sdp->sd_reclaim_count);
2019                 spin_unlock(&sdp->sd_reclaim_lock);
2020                 released = gfs2_glock_put(gl);
2021                 gfs2_assert(sdp, !released);
2022         } else {
2023                 spin_unlock(&sdp->sd_reclaim_lock);
2024         }
2025
2026         if (gfs2_glmutex_trylock(gl)) {
2027                 if (queue_empty(gl, &gl->gl_holders) &&
2028                     gl->gl_state != LM_ST_UNLOCKED)
2029                         handle_callback(gl, LM_ST_UNLOCKED);
2030
2031                 gfs2_glmutex_unlock(gl);
2032         }
2033
2034         gfs2_glock_put(gl);
2035 }
2036
2037 /**
2038  * gfs2_gl_hash_clear - Empty out the glock hash table
2039  * @sdp: the filesystem
2040  * @wait: wait until it's all gone
2041  *
2042  * Called when unmounting the filesystem, or when inter-node lock manager
2043  * requests DROPLOCKS because it is running out of capacity.
2044  */
2045
2046 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp, int wait)
2047 {
2048         unsigned long t;
2049         unsigned int x;
2050         int cont;
2051
2052         t = jiffies;
2053
2054         for (;;) {
2055                 cont = 0;
2056
2057                 for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
2058                         if (examine_bucket(clear_glock, sdp,
2059                                            &sdp->sd_gl_hash[x]))
2060                                 cont = 1;
2061
2062                 if (!wait || !cont)
2063                         break;
2064
2065                 if (time_after_eq(jiffies,
2066                                   t + gfs2_tune_get(sdp, gt_stall_secs) * HZ)) {
2067                         fs_warn(sdp, "Unmount seems to be stalled. "
2068                                      "Dumping lock state...\n");
2069                         gfs2_dump_lockstate(sdp);
2070                         t = jiffies;
2071                 }
2072
2073                 /* invalidate_inodes() requires that the sb inodes list
2074                    not change, but an async completion callback for an
2075                    unlock can occur which does glock_put() which
2076                    can call iput() which will change the sb inodes list.
2077                    invalidate_inodes_mutex prevents glock_put()'s during
2078                    an invalidate_inodes() */
2079
2080                 mutex_lock(&sdp->sd_invalidate_inodes_mutex);
2081                 invalidate_inodes(sdp->sd_vfs);
2082                 mutex_unlock(&sdp->sd_invalidate_inodes_mutex);
2083                 msleep(10);
2084         }
2085 }
2086
2087 /*
2088  *  Diagnostic routines to help debug distributed deadlock
2089  */
2090
2091 /**
2092  * dump_holder - print information about a glock holder
2093  * @str: a string naming the type of holder
2094  * @gh: the glock holder
2095  *
2096  * Returns: 0 on success, -ENOBUFS when we run out of space
2097  */
2098
2099 static int dump_holder(char *str, struct gfs2_holder *gh)
2100 {
2101         unsigned int x;
2102         int error = -ENOBUFS;
2103
2104         printk(KERN_INFO "  %s\n", str);
2105         printk(KERN_INFO "    owner = %ld\n",
2106                    (gh->gh_owner) ? (long)gh->gh_owner->pid : -1);
2107         printk(KERN_INFO "    gh_state = %u\n", gh->gh_state);
2108         printk(KERN_INFO "    gh_flags =");
2109         for (x = 0; x < 32; x++)
2110                 if (gh->gh_flags & (1 << x))
2111                         printk(" %u", x);
2112         printk(" \n");
2113         printk(KERN_INFO "    error = %d\n", gh->gh_error);
2114         printk(KERN_INFO "    gh_iflags =");
2115         for (x = 0; x < 32; x++)
2116                 if (test_bit(x, &gh->gh_iflags))
2117                         printk(" %u", x);
2118         printk(" \n");
2119         print_symbol(KERN_INFO "    initialized at: %s\n", gh->gh_ip);
2120
2121         error = 0;
2122
2123         return error;
2124 }
2125
2126 /**
2127  * dump_inode - print information about an inode
2128  * @ip: the inode
2129  *
2130  * Returns: 0 on success, -ENOBUFS when we run out of space
2131  */
2132
2133 static int dump_inode(struct gfs2_inode *ip)
2134 {
2135         unsigned int x;
2136         int error = -ENOBUFS;
2137
2138         printk(KERN_INFO "  Inode:\n");
2139         printk(KERN_INFO "    num = %llu %llu\n",
2140                     (unsigned long long)ip->i_num.no_formal_ino,
2141                     (unsigned long long)ip->i_num.no_addr);
2142         printk(KERN_INFO "    type = %u\n", IF2DT(ip->i_di.di_mode));
2143         printk(KERN_INFO "    i_flags =");
2144         for (x = 0; x < 32; x++)
2145                 if (test_bit(x, &ip->i_flags))
2146                         printk(" %u", x);
2147         printk(" \n");
2148
2149         error = 0;
2150
2151         return error;
2152 }
2153
2154 /**
2155  * dump_glock - print information about a glock
2156  * @gl: the glock
2157  * @count: where we are in the buffer
2158  *
2159  * Returns: 0 on success, -ENOBUFS when we run out of space
2160  */
2161
2162 static int dump_glock(struct gfs2_glock *gl)
2163 {
2164         struct gfs2_holder *gh;
2165         unsigned int x;
2166         int error = -ENOBUFS;
2167
2168         spin_lock(&gl->gl_spin);
2169
2170         printk(KERN_INFO "Glock (%u, %llu)\n", gl->gl_name.ln_type,
2171                (unsigned long long)gl->gl_name.ln_number);
2172         printk(KERN_INFO "  gl_flags =");
2173         for (x = 0; x < 32; x++)
2174                 if (test_bit(x, &gl->gl_flags))
2175                         printk(" %u", x);
2176         printk(" \n");
2177         printk(KERN_INFO "  gl_ref = %d\n", atomic_read(&gl->gl_ref.refcount));
2178         printk(KERN_INFO "  gl_state = %u\n", gl->gl_state);
2179         printk(KERN_INFO "  gl_owner = %s\n", gl->gl_owner->comm);
2180         print_symbol(KERN_INFO "  gl_ip = %s\n", gl->gl_ip);
2181         printk(KERN_INFO "  req_gh = %s\n", (gl->gl_req_gh) ? "yes" : "no");
2182         printk(KERN_INFO "  req_bh = %s\n", (gl->gl_req_bh) ? "yes" : "no");
2183         printk(KERN_INFO "  lvb_count = %d\n", atomic_read(&gl->gl_lvb_count));
2184         printk(KERN_INFO "  object = %s\n", (gl->gl_object) ? "yes" : "no");
2185         printk(KERN_INFO "  le = %s\n",
2186                    (list_empty(&gl->gl_le.le_list)) ? "no" : "yes");
2187         printk(KERN_INFO "  reclaim = %s\n",
2188                     (list_empty(&gl->gl_reclaim)) ? "no" : "yes");
2189         if (gl->gl_aspace)
2190                 printk(KERN_INFO "  aspace = %lu\n",
2191                             gl->gl_aspace->i_mapping->nrpages);
2192         else
2193                 printk(KERN_INFO "  aspace = no\n");
2194         printk(KERN_INFO "  ail = %d\n", atomic_read(&gl->gl_ail_count));
2195         if (gl->gl_req_gh) {
2196                 error = dump_holder("Request", gl->gl_req_gh);
2197                 if (error)
2198                         goto out;
2199         }
2200         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
2201                 error = dump_holder("Holder", gh);
2202                 if (error)
2203                         goto out;
2204         }
2205         list_for_each_entry(gh, &gl->gl_waiters1, gh_list) {
2206                 error = dump_holder("Waiter1", gh);
2207                 if (error)
2208                         goto out;
2209         }
2210         list_for_each_entry(gh, &gl->gl_waiters2, gh_list) {
2211                 error = dump_holder("Waiter2", gh);
2212                 if (error)
2213                         goto out;
2214         }
2215         list_for_each_entry(gh, &gl->gl_waiters3, gh_list) {
2216                 error = dump_holder("Waiter3", gh);
2217                 if (error)
2218                         goto out;
2219         }
2220         if (gl->gl_ops == &gfs2_inode_glops && gl->gl_object) {
2221                 if (!test_bit(GLF_LOCK, &gl->gl_flags) &&
2222                     list_empty(&gl->gl_holders)) {
2223                         error = dump_inode(gl->gl_object);
2224                         if (error)
2225                                 goto out;
2226                 } else {
2227                         error = -ENOBUFS;
2228                         printk(KERN_INFO "  Inode: busy\n");
2229                 }
2230         }
2231
2232         error = 0;
2233
2234  out:
2235         spin_unlock(&gl->gl_spin);
2236
2237         return error;
2238 }
2239
2240 /**
2241  * gfs2_dump_lockstate - print out the current lockstate
2242  * @sdp: the filesystem
2243  * @ub: the buffer to copy the information into
2244  *
2245  * If @ub is NULL, dump the lockstate to the console.
2246  *
2247  */
2248
2249 static int gfs2_dump_lockstate(struct gfs2_sbd *sdp)
2250 {
2251         struct gfs2_gl_hash_bucket *bucket;
2252         struct gfs2_glock *gl;
2253         unsigned int x;
2254         int error = 0;
2255
2256         for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
2257                 bucket = &sdp->sd_gl_hash[x];
2258
2259                 read_lock(&bucket->hb_lock);
2260
2261                 list_for_each_entry(gl, &bucket->hb_list, gl_list) {
2262                         if (test_bit(GLF_PLUG, &gl->gl_flags))
2263                                 continue;
2264
2265                         error = dump_glock(gl);
2266                         if (error)
2267                                 break;
2268                 }
2269
2270                 read_unlock(&bucket->hb_lock);
2271
2272                 if (error)
2273                         break;
2274         }
2275
2276
2277         return error;
2278 }
2279