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         gfs2_holder_uninit(&gh);
 775 }
 776
 777 /**
 778  * state_change - record that the glock is now in a different state
 779  * @gl: the glock
 780  * @new_state the new state
 781  *
 782  */
 783
 784 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 785 {
 786         int held1, held2;
 787
 788         held1 = (gl->gl_state != LM_ST_UNLOCKED);
 789         held2 = (new_state != LM_ST_UNLOCKED);
 790
 791         if (held1 != held2) {
 792                 if (held2)
 793                         gfs2_glock_hold(gl);
 794                 else
 795                         gfs2_glock_put(gl);
 796         }
 797
 798         gl->gl_state = new_state;
 799 }
 800
 801 /**
 802  * xmote_bh - Called after the lock module is done acquiring a lock
 803  * @gl: The glock in question
 804  * @ret: the int returned from the lock module
 805  *
 806  */
 807
 808 static void xmote_bh(struct gfs2_glock *gl, unsigned int ret)
 809 {
 810         struct gfs2_sbd *sdp = gl->gl_sbd;
 811         struct gfs2_glock_operations *glops = gl->gl_ops;
 812         struct gfs2_holder *gh = gl->gl_req_gh;
 813         int prev_state = gl->gl_state;
 814         int op_done = 1;
 815
 816         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
 817         gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
 818         gfs2_assert_warn(sdp, !(ret & LM_OUT_ASYNC));
 819
 820         state_change(gl, ret & LM_OUT_ST_MASK);
 821
 822         if (prev_state != LM_ST_UNLOCKED && !(ret & LM_OUT_CACHEABLE)) {
 823                 if (glops->go_inval)
 824                         glops->go_inval(gl, DIO_METADATA | DIO_DATA);
 825         } else if (gl->gl_state == LM_ST_DEFERRED) {
 826                 /* We might not want to do this here.
 827                    Look at moving to the inode glops. */
 828                 if (glops->go_inval)
 829                         glops->go_inval(gl, DIO_DATA);
 830         }
 831
 832         /*  Deal with each possible exit condition  */
 833
 834         if (!gh)
 835                 gl->gl_stamp = jiffies;
 836
 837         else if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
 838                 spin_lock(&gl->gl_spin);
 839                 list_del_init(&gh->gh_list);
 840                 gh->gh_error = -EIO;
 841                 spin_unlock(&gl->gl_spin);
 842
 843         } else if (test_bit(HIF_DEMOTE, &gh->gh_iflags)) {
 844                 spin_lock(&gl->gl_spin);
 845                 list_del_init(&gh->gh_list);
 846                 if (gl->gl_state == gh->gh_state ||
 847                     gl->gl_state == LM_ST_UNLOCKED)
 848                         gh->gh_error = 0;
 849                 else {
 850                         if (gfs2_assert_warn(sdp, gh->gh_flags &
 851                                         (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) == -1)
 852                                 fs_warn(sdp, "ret = 0x%.8X\n", ret);
 853                         gh->gh_error = GLR_TRYFAILED;
 854                 }
 855                 spin_unlock(&gl->gl_spin);
 856
 857                 if (ret & LM_OUT_CANCELED)
 858                         handle_callback(gl, LM_ST_UNLOCKED); /* Lame */
 859
 860         } else if (ret & LM_OUT_CANCELED) {
 861                 spin_lock(&gl->gl_spin);
 862                 list_del_init(&gh->gh_list);
 863                 gh->gh_error = GLR_CANCELED;
 864                 spin_unlock(&gl->gl_spin);
 865
 866         } else if (relaxed_state_ok(gl->gl_state, gh->gh_state, gh->gh_flags)) {
 867                 spin_lock(&gl->gl_spin);
 868                 list_move_tail(&gh->gh_list, &gl->gl_holders);
 869                 gh->gh_error = 0;
 870                 set_bit(HIF_HOLDER, &gh->gh_iflags);
 871                 spin_unlock(&gl->gl_spin);
 872
 873                 set_bit(HIF_FIRST, &gh->gh_iflags);
 874
 875                 op_done = 0;
 876
 877         } else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
 878                 spin_lock(&gl->gl_spin);
 879                 list_del_init(&gh->gh_list);
 880                 gh->gh_error = GLR_TRYFAILED;
 881                 spin_unlock(&gl->gl_spin);
 882
 883         } else {
 884                 if (gfs2_assert_withdraw(sdp, 0) == -1)
 885                         fs_err(sdp, "ret = 0x%.8X\n", ret);
 886         }
 887
 888         if (glops->go_xmote_bh)
 889                 glops->go_xmote_bh(gl);
 890
 891         if (op_done) {
 892                 spin_lock(&gl->gl_spin);
 893                 gl->gl_req_gh = NULL;
 894                 gl->gl_req_bh = NULL;
 895                 clear_bit(GLF_LOCK, &gl->gl_flags);
 896                 run_queue(gl);
 897                 spin_unlock(&gl->gl_spin);
 898         }
 899
 900         gfs2_glock_put(gl);
 901
 902         if (gh) {
 903                 if (test_bit(HIF_DEALLOC, &gh->gh_iflags))
 904                         gfs2_holder_put(gh);
 905                 else
 906                         complete(&gh->gh_wait);
 907         }
 908 }
 909
 910 /**
 911  * gfs2_glock_xmote_th - Call into the lock module to acquire or change a glock
 912  * @gl: The glock in question
 913  * @state: the requested state
 914  * @flags: modifier flags to the lock call
 915  *
 916  */
 917
 918 void gfs2_glock_xmote_th(struct gfs2_glock *gl, unsigned int state, int flags)
 919 {
 920         struct gfs2_sbd *sdp = gl->gl_sbd;
 921         struct gfs2_glock_operations *glops = gl->gl_ops;
 922         int lck_flags = flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB |
 923                                  LM_FLAG_NOEXP | LM_FLAG_ANY |
 924                                  LM_FLAG_PRIORITY);
 925         unsigned int lck_ret;
 926
 927         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
 928         gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
 929         gfs2_assert_warn(sdp, state != LM_ST_UNLOCKED);
 930         gfs2_assert_warn(sdp, state != gl->gl_state);
 931
 932         if (gl->gl_state == LM_ST_EXCLUSIVE) {
 933                 if (glops->go_sync)
 934                         glops->go_sync(gl,
 935                                        DIO_METADATA | DIO_DATA | DIO_RELEASE);
 936         }
 937
 938         gfs2_glock_hold(gl);
 939         gl->gl_req_bh = xmote_bh;
 940
 941         lck_ret = gfs2_lm_lock(sdp, gl->gl_lock, gl->gl_state, state,
 942                                lck_flags);
 943
 944         if (gfs2_assert_withdraw(sdp, !(lck_ret & LM_OUT_ERROR)))
 945                 return;
 946
 947         if (lck_ret & LM_OUT_ASYNC)
 948                 gfs2_assert_warn(sdp, lck_ret == LM_OUT_ASYNC);
 949         else
 950                 xmote_bh(gl, lck_ret);
 951 }
 952
 953 /**
 954  * drop_bh - Called after a lock module unlock completes
 955  * @gl: the glock
 956  * @ret: the return status
 957  *
 958  * Doesn't wake up the process waiting on the struct gfs2_holder (if any)
 959  * Doesn't drop the reference on the glock the top half took out
 960  *
 961  */
 962
 963 static void drop_bh(struct gfs2_glock *gl, unsigned int ret)
 964 {
 965         struct gfs2_sbd *sdp = gl->gl_sbd;
 966         struct gfs2_glock_operations *glops = gl->gl_ops;
 967         struct gfs2_holder *gh = gl->gl_req_gh;
 968
 969         clear_bit(GLF_PREFETCH, &gl->gl_flags);
 970
 971         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
 972         gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
 973         gfs2_assert_warn(sdp, !ret);
 974
 975         state_change(gl, LM_ST_UNLOCKED);
 976
 977         if (glops->go_inval)
 978                 glops->go_inval(gl, DIO_METADATA | DIO_DATA);
 979
 980         if (gh) {
 981                 spin_lock(&gl->gl_spin);
 982                 list_del_init(&gh->gh_list);
 983                 gh->gh_error = 0;
 984                 spin_unlock(&gl->gl_spin);
 985         }
 986
 987         if (glops->go_drop_bh)
 988                 glops->go_drop_bh(gl);
 989
 990         spin_lock(&gl->gl_spin);
 991         gl->gl_req_gh = NULL;
 992         gl->gl_req_bh = NULL;
 993         clear_bit(GLF_LOCK, &gl->gl_flags);
 994         run_queue(gl);
 995         spin_unlock(&gl->gl_spin);
 996
 997         gfs2_glock_put(gl);
 998
 999         if (gh) {
1000                 if (test_bit(HIF_DEALLOC, &gh->gh_iflags))
1001                         gfs2_holder_put(gh);
1002                 else
1003                         complete(&gh->gh_wait);
1004         }
1005 }
1006
1007 /**
1008  * gfs2_glock_drop_th - call into the lock module to unlock a lock
1009  * @gl: the glock
1010  *
1011  */
1012
1013 void gfs2_glock_drop_th(struct gfs2_glock *gl)
1014 {
1015         struct gfs2_sbd *sdp = gl->gl_sbd;
1016         struct gfs2_glock_operations *glops = gl->gl_ops;
1017         unsigned int ret;
1018
1019         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
1020         gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
1021         gfs2_assert_warn(sdp, gl->gl_state != LM_ST_UNLOCKED);
1022
1023         if (gl->gl_state == LM_ST_EXCLUSIVE) {
1024                 if (glops->go_sync)
1025                         glops->go_sync(gl,
1026                                        DIO_METADATA | DIO_DATA | DIO_RELEASE);
1027         }
1028
1029         gfs2_glock_hold(gl);
1030         gl->gl_req_bh = drop_bh;
1031
1032         ret = gfs2_lm_unlock(sdp, gl->gl_lock, gl->gl_state);
1033
1034         if (gfs2_assert_withdraw(sdp, !(ret & LM_OUT_ERROR)))
1035                 return;
1036
1037         if (!ret)
1038                 drop_bh(gl, ret);
1039         else
1040                 gfs2_assert_warn(sdp, ret == LM_OUT_ASYNC);
1041 }
1042
1043 /**
1044  * do_cancels - cancel requests for locks stuck waiting on an expire flag
1045  * @gh: the LM_FLAG_PRIORITY holder waiting to acquire the lock
1046  *
1047  * Don't cancel GL_NOCANCEL requests.
1048  */
1049
1050 static void do_cancels(struct gfs2_holder *gh)
1051 {
1052         struct gfs2_glock *gl = gh->gh_gl;
1053
1054         spin_lock(&gl->gl_spin);
1055
1056         while (gl->gl_req_gh != gh &&
1057                !test_bit(HIF_HOLDER, &gh->gh_iflags) &&
1058                !list_empty(&gh->gh_list)) {
1059                 if (gl->gl_req_bh &&
1060                     !(gl->gl_req_gh &&
1061                       (gl->gl_req_gh->gh_flags & GL_NOCANCEL))) {
1062                         spin_unlock(&gl->gl_spin);
1063                         gfs2_lm_cancel(gl->gl_sbd, gl->gl_lock);
1064                         msleep(100);
1065                         spin_lock(&gl->gl_spin);
1066                 } else {
1067                         spin_unlock(&gl->gl_spin);
1068                         msleep(100);
1069                         spin_lock(&gl->gl_spin);
1070                 }
1071         }
1072
1073         spin_unlock(&gl->gl_spin);
1074 }
1075
1076 /**
1077  * glock_wait_internal - wait on a glock acquisition
1078  * @gh: the glock holder
1079  *
1080  * Returns: 0 on success
1081  */
1082
1083 static int glock_wait_internal(struct gfs2_holder *gh)
1084 {
1085         struct gfs2_glock *gl = gh->gh_gl;
1086         struct gfs2_sbd *sdp = gl->gl_sbd;
1087         struct gfs2_glock_operations *glops = gl->gl_ops;
1088
1089         if (test_bit(HIF_ABORTED, &gh->gh_iflags))
1090                 return -EIO;
1091
1092         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
1093                 spin_lock(&gl->gl_spin);
1094                 if (gl->gl_req_gh != gh &&
1095                     !test_bit(HIF_HOLDER, &gh->gh_iflags) &&
1096                     !list_empty(&gh->gh_list)) {
1097                         list_del_init(&gh->gh_list);
1098                         gh->gh_error = GLR_TRYFAILED;
1099                         run_queue(gl);
1100                         spin_unlock(&gl->gl_spin);
1101                         return gh->gh_error;
1102                 }
1103                 spin_unlock(&gl->gl_spin);
1104         }
1105
1106         if (gh->gh_flags & LM_FLAG_PRIORITY)
1107                 do_cancels(gh);
1108
1109         wait_for_completion(&gh->gh_wait);
1110
1111         if (gh->gh_error)
1112                 return gh->gh_error;
1113
1114         gfs2_assert_withdraw(sdp, test_bit(HIF_HOLDER, &gh->gh_iflags));
1115         gfs2_assert_withdraw(sdp, relaxed_state_ok(gl->gl_state,
1116                                                    gh->gh_state,
1117                                                    gh->gh_flags));
1118
1119         if (test_bit(HIF_FIRST, &gh->gh_iflags)) {
1120                 gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
1121
1122                 if (glops->go_lock) {
1123                         gh->gh_error = glops->go_lock(gh);
1124                         if (gh->gh_error) {
1125                                 spin_lock(&gl->gl_spin);
1126                                 list_del_init(&gh->gh_list);
1127                                 spin_unlock(&gl->gl_spin);
1128                         }
1129                 }
1130
1131                 spin_lock(&gl->gl_spin);
1132                 gl->gl_req_gh = NULL;
1133                 gl->gl_req_bh = NULL;
1134                 clear_bit(GLF_LOCK, &gl->gl_flags);
1135                 run_queue(gl);
1136                 spin_unlock(&gl->gl_spin);
1137         }
1138
1139         return gh->gh_error;
1140 }
1141
1142 static inline struct gfs2_holder *
1143 find_holder_by_owner(struct list_head *head, struct task_struct *owner)
1144 {
1145         struct gfs2_holder *gh;
1146
1147         list_for_each_entry(gh, head, gh_list) {
1148                 if (gh->gh_owner == owner)
1149                         return gh;
1150         }
1151
1152         return NULL;
1153 }
1154
1155 /**
1156  * add_to_queue - Add a holder to the wait queue (but look for recursion)
1157  * @gh: the holder structure to add
1158  *
1159  */
1160
1161 static void add_to_queue(struct gfs2_holder *gh)
1162 {
1163         struct gfs2_glock *gl = gh->gh_gl;
1164         struct gfs2_holder *existing;
1165
1166         BUG_ON(!gh->gh_owner);
1167
1168         existing = find_holder_by_owner(&gl->gl_holders, gh->gh_owner);
1169         if (existing) {
1170                 print_symbol(KERN_WARNING "original: %s\n", existing->gh_ip);
1171                 print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
1172                 BUG();
1173         }
1174
1175         existing = find_holder_by_owner(&gl->gl_waiters3, gh->gh_owner);
1176         if (existing) {
1177                 print_symbol(KERN_WARNING "original: %s\n", existing->gh_ip);
1178                 print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
1179                 BUG();
1180         }
1181
1182         if (gh->gh_flags & LM_FLAG_PRIORITY)
1183                 list_add(&gh->gh_list, &gl->gl_waiters3);
1184         else
1185                 list_add_tail(&gh->gh_list, &gl->gl_waiters3);
1186 }
1187
1188 /**
1189  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1190  * @gh: the holder structure
1191  *
1192  * if (gh->gh_flags & GL_ASYNC), this never returns an error
1193  *
1194  * Returns: 0, GLR_TRYFAILED, or errno on failure
1195  */
1196
1197 int gfs2_glock_nq(struct gfs2_holder *gh)
1198 {
1199         struct gfs2_glock *gl = gh->gh_gl;
1200         struct gfs2_sbd *sdp = gl->gl_sbd;
1201         int error = 0;
1202
1203 restart:
1204         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
1205                 set_bit(HIF_ABORTED, &gh->gh_iflags);
1206                 return -EIO;
1207         }
1208
1209         set_bit(HIF_PROMOTE, &gh->gh_iflags);
1210
1211         spin_lock(&gl->gl_spin);
1212         add_to_queue(gh);
1213         run_queue(gl);
1214         spin_unlock(&gl->gl_spin);
1215
1216         if (!(gh->gh_flags & GL_ASYNC)) {
1217                 error = glock_wait_internal(gh);
1218                 if (error == GLR_CANCELED) {
1219                         msleep(100);
1220                         goto restart;
1221                 }
1222         }
1223
1224         clear_bit(GLF_PREFETCH, &gl->gl_flags);
1225
1226         if (error == GLR_TRYFAILED && (gh->gh_flags & GL_DUMP))
1227                 dump_glock(gl);
1228
1229         return error;
1230 }
1231
1232 /**
1233  * gfs2_glock_poll - poll to see if an async request has been completed
1234  * @gh: the holder
1235  *
1236  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1237  */
1238
1239 int gfs2_glock_poll(struct gfs2_holder *gh)
1240 {
1241         struct gfs2_glock *gl = gh->gh_gl;
1242         int ready = 0;
1243
1244         spin_lock(&gl->gl_spin);
1245
1246         if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1247                 ready = 1;
1248         else if (list_empty(&gh->gh_list)) {
1249                 if (gh->gh_error == GLR_CANCELED) {
1250                         spin_unlock(&gl->gl_spin);
1251                         msleep(100);
1252                         if (gfs2_glock_nq(gh))
1253                                 return 1;
1254                         return 0;
1255                 } else
1256                         ready = 1;
1257         }
1258
1259         spin_unlock(&gl->gl_spin);
1260
1261         return ready;
1262 }
1263
1264 /**
1265  * gfs2_glock_wait - wait for a lock acquisition that ended in a GLR_ASYNC
1266  * @gh: the holder structure
1267  *
1268  * Returns: 0, GLR_TRYFAILED, or errno on failure
1269  */
1270
1271 int gfs2_glock_wait(struct gfs2_holder *gh)
1272 {
1273         int error;
1274
1275         error = glock_wait_internal(gh);
1276         if (error == GLR_CANCELED) {
1277                 msleep(100);
1278                 gh->gh_flags &= ~GL_ASYNC;
1279                 error = gfs2_glock_nq(gh);
1280         }
1281
1282         return error;
1283 }
1284
1285 /**
1286  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1287  * @gh: the glock holder
1288  *
1289  */
1290
1291 void gfs2_glock_dq(struct gfs2_holder *gh)
1292 {
1293         struct gfs2_glock *gl = gh->gh_gl;
1294         struct gfs2_glock_operations *glops = gl->gl_ops;
1295
1296         if (gh->gh_flags & GL_SYNC)
1297                 set_bit(GLF_SYNC, &gl->gl_flags);
1298
1299         if (gh->gh_flags & GL_NOCACHE)
1300                 handle_callback(gl, LM_ST_UNLOCKED);
1301
1302         gfs2_glmutex_lock(gl);
1303
1304         spin_lock(&gl->gl_spin);
1305         list_del_init(&gh->gh_list);
1306
1307         if (list_empty(&gl->gl_holders)) {
1308                 spin_unlock(&gl->gl_spin);
1309
1310                 if (glops->go_unlock)
1311                         glops->go_unlock(gh);
1312
1313                 if (test_bit(GLF_SYNC, &gl->gl_flags)) {
1314                         if (glops->go_sync)
1315                                 glops->go_sync(gl, DIO_METADATA | DIO_DATA);
1316                 }
1317
1318                 gl->gl_stamp = jiffies;
1319
1320                 spin_lock(&gl->gl_spin);
1321         }
1322
1323         clear_bit(GLF_LOCK, &gl->gl_flags);
1324         run_queue(gl);
1325         spin_unlock(&gl->gl_spin);
1326 }
1327
1328 /**
1329  * gfs2_glock_prefetch - Try to prefetch a glock
1330  * @gl: the glock
1331  * @state: the state to prefetch in
1332  * @flags: flags passed to go_xmote_th()
1333  *
1334  */
1335
1336 static void gfs2_glock_prefetch(struct gfs2_glock *gl, unsigned int state,
1337                                 int flags)
1338 {
1339         struct gfs2_glock_operations *glops = gl->gl_ops;
1340
1341         spin_lock(&gl->gl_spin);
1342
1343         if (test_bit(GLF_LOCK, &gl->gl_flags) ||
1344             !list_empty(&gl->gl_holders) ||
1345             !list_empty(&gl->gl_waiters1) ||
1346             !list_empty(&gl->gl_waiters2) ||
1347             !list_empty(&gl->gl_waiters3) ||
1348             relaxed_state_ok(gl->gl_state, state, flags)) {
1349                 spin_unlock(&gl->gl_spin);
1350                 return;
1351         }
1352
1353         set_bit(GLF_PREFETCH, &gl->gl_flags);
1354         set_bit(GLF_LOCK, &gl->gl_flags);
1355         spin_unlock(&gl->gl_spin);
1356
1357         glops->go_xmote_th(gl, state, flags);
1358 }
1359
1360 static void greedy_work(void *data)
1361 {
1362         struct greedy *gr = data;
1363         struct gfs2_holder *gh = &gr->gr_gh;
1364         struct gfs2_glock *gl = gh->gh_gl;
1365         struct gfs2_glock_operations *glops = gl->gl_ops;
1366
1367         clear_bit(GLF_SKIP_WAITERS2, &gl->gl_flags);
1368
1369         if (glops->go_greedy)
1370                 glops->go_greedy(gl);
1371
1372         spin_lock(&gl->gl_spin);
1373
1374         if (list_empty(&gl->gl_waiters2)) {
1375                 clear_bit(GLF_GREEDY, &gl->gl_flags);
1376                 spin_unlock(&gl->gl_spin);
1377                 gfs2_holder_uninit(gh);
1378                 kfree(gr);
1379         } else {
1380                 gfs2_glock_hold(gl);
1381                 list_add_tail(&gh->gh_list, &gl->gl_waiters2);
1382                 run_queue(gl);
1383                 spin_unlock(&gl->gl_spin);
1384                 gfs2_glock_put(gl);
1385         }
1386 }
1387
1388 /**
1389  * gfs2_glock_be_greedy -
1390  * @gl:
1391  * @time:
1392  *
1393  * Returns: 0 if go_greedy will be called, 1 otherwise
1394  */
1395
1396 int gfs2_glock_be_greedy(struct gfs2_glock *gl, unsigned int time)
1397 {
1398         struct greedy *gr;
1399         struct gfs2_holder *gh;
1400
1401         if (!time || gl->gl_sbd->sd_args.ar_localcaching ||
1402             test_and_set_bit(GLF_GREEDY, &gl->gl_flags))
1403                 return 1;
1404
1405         gr = kmalloc(sizeof(struct greedy), GFP_KERNEL);
1406         if (!gr) {
1407                 clear_bit(GLF_GREEDY, &gl->gl_flags);
1408                 return 1;
1409         }
1410         gh = &gr->gr_gh;
1411
1412         gfs2_holder_init(gl, 0, 0, gh);
1413         set_bit(HIF_GREEDY, &gh->gh_iflags);
1414         INIT_WORK(&gr->gr_work, greedy_work, gr);
1415
1416         set_bit(GLF_SKIP_WAITERS2, &gl->gl_flags);
1417         schedule_delayed_work(&gr->gr_work, time);
1418
1419         return 0;
1420 }
1421
1422 /**
1423  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1424  * @gh: the holder structure
1425  *
1426  */
1427
1428 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1429 {
1430         gfs2_glock_dq(gh);
1431         gfs2_holder_uninit(gh);
1432 }
1433
1434 /**
1435  * gfs2_glock_nq_num - acquire a glock based on lock number
1436  * @sdp: the filesystem
1437  * @number: the lock number
1438  * @glops: the glock operations for the type of glock
1439  * @state: the state to acquire the glock in
1440  * @flags: modifier flags for the aquisition
1441  * @gh: the struct gfs2_holder
1442  *
1443  * Returns: errno
1444  */
1445
1446 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, uint64_t number,
1447                       struct gfs2_glock_operations *glops, unsigned int state,
1448                       int flags, struct gfs2_holder *gh)
1449 {
1450         struct gfs2_glock *gl;
1451         int error;
1452
1453         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1454         if (!error) {
1455                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1456                 gfs2_glock_put(gl);
1457         }
1458
1459         return error;
1460 }
1461
1462 /**
1463  * glock_compare - Compare two struct gfs2_glock structures for sorting
1464  * @arg_a: the first structure
1465  * @arg_b: the second structure
1466  *
1467  */
1468
1469 static int glock_compare(const void *arg_a, const void *arg_b)
1470 {
1471         struct gfs2_holder *gh_a = *(struct gfs2_holder **)arg_a;
1472         struct gfs2_holder *gh_b = *(struct gfs2_holder **)arg_b;
1473         struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1474         struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1475         int ret = 0;
1476
1477         if (a->ln_number > b->ln_number)
1478                 ret = 1;
1479         else if (a->ln_number < b->ln_number)
1480                 ret = -1;
1481         else {
1482                 if (gh_a->gh_state == LM_ST_SHARED &&
1483                     gh_b->gh_state == LM_ST_EXCLUSIVE)
1484                         ret = 1;
1485                 else if (!(gh_a->gh_flags & GL_LOCAL_EXCL) &&
1486                          (gh_b->gh_flags & GL_LOCAL_EXCL))
1487                         ret = 1;
1488         }
1489
1490         return ret;
1491 }
1492
1493 /**
1494  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1495  * @num_gh: the number of structures
1496  * @ghs: an array of struct gfs2_holder structures
1497  *
1498  * Returns: 0 on success (all glocks acquired),
1499  *          errno on failure (no glocks acquired)
1500  */
1501
1502 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1503                      struct gfs2_holder **p)
1504 {
1505         unsigned int x;
1506         int error = 0;
1507
1508         for (x = 0; x < num_gh; x++)
1509                 p[x] = &ghs[x];
1510
1511         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1512
1513         for (x = 0; x < num_gh; x++) {
1514                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1515
1516                 error = gfs2_glock_nq(p[x]);
1517                 if (error) {
1518                         while (x--)
1519                                 gfs2_glock_dq(p[x]);
1520                         break;
1521                 }
1522         }
1523
1524         return error;
1525 }
1526
1527 /**
1528  * gfs2_glock_nq_m - acquire multiple glocks
1529  * @num_gh: the number of structures
1530  * @ghs: an array of struct gfs2_holder structures
1531  *
1532  * Figure out how big an impact this function has.  Either:
1533  * 1) Replace this code with code that calls gfs2_glock_prefetch()
1534  * 2) Forget async stuff and just call nq_m_sync()
1535  * 3) Leave it like it is
1536  *
1537  * Returns: 0 on success (all glocks acquired),
1538  *          errno on failure (no glocks acquired)
1539  */
1540
1541 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1542 {
1543         int *e;
1544         unsigned int x;
1545         int borked = 0, serious = 0;
1546         int error = 0;
1547
1548         if (!num_gh)
1549                 return 0;
1550
1551         if (num_gh == 1) {
1552                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1553                 return gfs2_glock_nq(ghs);
1554         }
1555
1556         e = kcalloc(num_gh, sizeof(struct gfs2_holder *), GFP_KERNEL);
1557         if (!e)
1558                 return -ENOMEM;
1559
1560         for (x = 0; x < num_gh; x++) {
1561                 ghs[x].gh_flags |= LM_FLAG_TRY | GL_ASYNC;
1562                 error = gfs2_glock_nq(&ghs[x]);
1563                 if (error) {
1564                         borked = 1;
1565                         serious = error;
1566                         num_gh = x;
1567                         break;
1568                 }
1569         }
1570
1571         for (x = 0; x < num_gh; x++) {
1572                 error = e[x] = glock_wait_internal(&ghs[x]);
1573                 if (error) {
1574                         borked = 1;
1575                         if (error != GLR_TRYFAILED && error != GLR_CANCELED)
1576                                 serious = error;
1577                 }
1578         }
1579
1580         if (!borked) {
1581                 kfree(e);
1582                 return 0;
1583         }
1584
1585         for (x = 0; x < num_gh; x++)
1586                 if (!e[x])
1587                         gfs2_glock_dq(&ghs[x]);
1588
1589         if (serious)
1590                 error = serious;
1591         else {
1592                 for (x = 0; x < num_gh; x++)
1593                         gfs2_holder_reinit(ghs[x].gh_state, ghs[x].gh_flags,
1594                                           &ghs[x]);
1595                 error = nq_m_sync(num_gh, ghs, (struct gfs2_holder **)e);
1596         }
1597
1598         kfree(e);
1599
1600         return error;
1601 }
1602
1603 /**
1604  * gfs2_glock_dq_m - release multiple glocks
1605  * @num_gh: the number of structures
1606  * @ghs: an array of struct gfs2_holder structures
1607  *
1608  */
1609
1610 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1611 {
1612         unsigned int x;
1613
1614         for (x = 0; x < num_gh; x++)
1615                 gfs2_glock_dq(&ghs[x]);
1616 }
1617
1618 /**
1619  * gfs2_glock_dq_uninit_m - release multiple glocks
1620  * @num_gh: the number of structures
1621  * @ghs: an array of struct gfs2_holder structures
1622  *
1623  */
1624
1625 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1626 {
1627         unsigned int x;
1628
1629         for (x = 0; x < num_gh; x++)
1630                 gfs2_glock_dq_uninit(&ghs[x]);
1631 }
1632
1633 /**
1634  * gfs2_glock_prefetch_num - prefetch a glock based on lock number
1635  * @sdp: the filesystem
1636  * @number: the lock number
1637  * @glops: the glock operations for the type of glock
1638  * @state: the state to acquire the glock in
1639  * @flags: modifier flags for the aquisition
1640  *
1641  * Returns: errno
1642  */
1643
1644 void gfs2_glock_prefetch_num(struct gfs2_sbd *sdp, uint64_t number,
1645                              struct gfs2_glock_operations *glops,
1646                              unsigned int state, int flags)
1647 {
1648         struct gfs2_glock *gl;
1649         int error;
1650
1651         if (atomic_read(&sdp->sd_reclaim_count) <
1652             gfs2_tune_get(sdp, gt_reclaim_limit)) {
1653                 error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1654                 if (!error) {
1655                         gfs2_glock_prefetch(gl, state, flags);
1656                         gfs2_glock_put(gl);
1657                 }
1658         }
1659 }
1660
1661 /**
1662  * gfs2_lvb_hold - attach a LVB from a glock
1663  * @gl: The glock in question
1664  *
1665  */
1666
1667 int gfs2_lvb_hold(struct gfs2_glock *gl)
1668 {
1669         int error;
1670
1671         gfs2_glmutex_lock(gl);
1672
1673         if (!atomic_read(&gl->gl_lvb_count)) {
1674                 error = gfs2_lm_hold_lvb(gl->gl_sbd, gl->gl_lock, &gl->gl_lvb);
1675                 if (error) {
1676                         gfs2_glmutex_unlock(gl);
1677                         return error;
1678                 }
1679                 gfs2_glock_hold(gl);
1680         }
1681         atomic_inc(&gl->gl_lvb_count);
1682
1683         gfs2_glmutex_unlock(gl);
1684
1685         return 0;
1686 }
1687
1688 /**
1689  * gfs2_lvb_unhold - detach a LVB from a glock
1690  * @gl: The glock in question
1691  *
1692  */
1693
1694 void gfs2_lvb_unhold(struct gfs2_glock *gl)
1695 {
1696         gfs2_glock_hold(gl);
1697         gfs2_glmutex_lock(gl);
1698
1699         gfs2_assert(gl->gl_sbd, atomic_read(&gl->gl_lvb_count) > 0);
1700         if (atomic_dec_and_test(&gl->gl_lvb_count)) {
1701                 gfs2_lm_unhold_lvb(gl->gl_sbd, gl->gl_lock, gl->gl_lvb);
1702                 gl->gl_lvb = NULL;
1703                 gfs2_glock_put(gl);
1704         }
1705
1706         gfs2_glmutex_unlock(gl);
1707         gfs2_glock_put(gl);
1708 }
1709
1710 #if 0
1711 void gfs2_lvb_sync(struct gfs2_glock *gl)
1712 {
1713         gfs2_glmutex_lock(gl);
1714
1715         gfs2_assert(gl->gl_sbd, atomic_read(&gl->gl_lvb_count));
1716         if (!gfs2_assert_warn(gl->gl_sbd, gfs2_glock_is_held_excl(gl)))
1717                 gfs2_lm_sync_lvb(gl->gl_sbd, gl->gl_lock, gl->gl_lvb);
1718
1719         gfs2_glmutex_unlock(gl);
1720 }
1721 #endif  /*  0  */
1722
1723 static void blocking_cb(struct gfs2_sbd *sdp, struct lm_lockname *name,
1724                         unsigned int state)
1725 {
1726         struct gfs2_glock *gl;
1727
1728         gl = gfs2_glock_find(sdp, name);
1729         if (!gl)
1730                 return;
1731
1732         if (gl->gl_ops->go_callback)
1733                 gl->gl_ops->go_callback(gl, state);
1734         handle_callback(gl, state);
1735
1736         spin_lock(&gl->gl_spin);
1737         run_queue(gl);
1738         spin_unlock(&gl->gl_spin);
1739
1740         gfs2_glock_put(gl);
1741 }
1742
1743 /**
1744  * gfs2_glock_cb - Callback used by locking module
1745  * @fsdata: Pointer to the superblock
1746  * @type: Type of callback
1747  * @data: Type dependent data pointer
1748  *
1749  * Called by the locking module when it wants to tell us something.
1750  * Either we need to drop a lock, one of our ASYNC requests completed, or
1751  * a journal from another client needs to be recovered.
1752  */
1753
1754 void gfs2_glock_cb(lm_fsdata_t *fsdata, unsigned int type, void *data)
1755 {
1756         struct gfs2_sbd *sdp = (struct gfs2_sbd *)fsdata;
1757
1758         switch (type) {
1759         case LM_CB_NEED_E:
1760                 blocking_cb(sdp, data, LM_ST_UNLOCKED);
1761                 return;
1762
1763         case LM_CB_NEED_D:
1764                 blocking_cb(sdp, data, LM_ST_DEFERRED);
1765                 return;
1766
1767         case LM_CB_NEED_S:
1768                 blocking_cb(sdp, data, LM_ST_SHARED);
1769                 return;
1770
1771         case LM_CB_ASYNC: {
1772                 struct lm_async_cb *async = data;
1773                 struct gfs2_glock *gl;
1774
1775                 gl = gfs2_glock_find(sdp, &async->lc_name);
1776                 if (gfs2_assert_warn(sdp, gl))
1777                         return;
1778                 if (!gfs2_assert_warn(sdp, gl->gl_req_bh))
1779                         gl->gl_req_bh(gl, async->lc_ret);
1780                 gfs2_glock_put(gl);
1781                 return;
1782         }
1783
1784         case LM_CB_NEED_RECOVERY:
1785                 gfs2_jdesc_make_dirty(sdp, *(unsigned int *)data);
1786                 if (sdp->sd_recoverd_process)
1787                         wake_up_process(sdp->sd_recoverd_process);
1788                 return;
1789
1790         case LM_CB_DROPLOCKS:
1791                 gfs2_gl_hash_clear(sdp, NO_WAIT);
1792                 gfs2_quota_scan(sdp);
1793                 return;
1794
1795         default:
1796                 gfs2_assert_warn(sdp, 0);
1797                 return;
1798         }
1799 }
1800
1801 /**
1802  * gfs2_iopen_go_callback - Try to kick the inode/vnode associated with an
1803  *                          iopen glock from memory
1804  * @io_gl: the iopen glock
1805  * @state: the state into which the glock should be put
1806  *
1807  */
1808
1809 void gfs2_iopen_go_callback(struct gfs2_glock *io_gl, unsigned int state)
1810 {
1811
1812         if (state != LM_ST_UNLOCKED)
1813                 return;
1814         /* FIXME: remove this? */
1815 }
1816
1817 /**
1818  * demote_ok - Check to see if it's ok to unlock a glock
1819  * @gl: the glock
1820  *
1821  * Returns: 1 if it's ok
1822  */
1823
1824 static int demote_ok(struct gfs2_glock *gl)
1825 {
1826         struct gfs2_sbd *sdp = gl->gl_sbd;
1827         struct gfs2_glock_operations *glops = gl->gl_ops;
1828         int demote = 1;
1829
1830         if (test_bit(GLF_STICKY, &gl->gl_flags))
1831                 demote = 0;
1832         else if (test_bit(GLF_PREFETCH, &gl->gl_flags))
1833                 demote = time_after_eq(jiffies,
1834                                     gl->gl_stamp +
1835                                     gfs2_tune_get(sdp, gt_prefetch_secs) * HZ);
1836         else if (glops->go_demote_ok)
1837                 demote = glops->go_demote_ok(gl);
1838
1839         return demote;
1840 }
1841
1842 /**
1843  * gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
1844  * @gl: the glock
1845  *
1846  */
1847
1848 void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
1849 {
1850         struct gfs2_sbd *sdp = gl->gl_sbd;
1851
1852         spin_lock(&sdp->sd_reclaim_lock);
1853         if (list_empty(&gl->gl_reclaim)) {
1854                 gfs2_glock_hold(gl);
1855                 list_add(&gl->gl_reclaim, &sdp->sd_reclaim_list);
1856                 atomic_inc(&sdp->sd_reclaim_count);
1857         }
1858         spin_unlock(&sdp->sd_reclaim_lock);
1859
1860         wake_up(&sdp->sd_reclaim_wq);
1861 }
1862
1863 /**
1864  * gfs2_reclaim_glock - process the next glock on the filesystem's reclaim list
1865  * @sdp: the filesystem
1866  *
1867  * Called from gfs2_glockd() glock reclaim daemon, or when promoting a
1868  * different glock and we notice that there are a lot of glocks in the
1869  * reclaim list.
1870  *
1871  */
1872
1873 void gfs2_reclaim_glock(struct gfs2_sbd *sdp)
1874 {
1875         struct gfs2_glock *gl;
1876
1877         spin_lock(&sdp->sd_reclaim_lock);
1878         if (list_empty(&sdp->sd_reclaim_list)) {
1879                 spin_unlock(&sdp->sd_reclaim_lock);
1880                 return;
1881         }
1882         gl = list_entry(sdp->sd_reclaim_list.next,
1883                         struct gfs2_glock, gl_reclaim);
1884         list_del_init(&gl->gl_reclaim);
1885         spin_unlock(&sdp->sd_reclaim_lock);
1886
1887         atomic_dec(&sdp->sd_reclaim_count);
1888         atomic_inc(&sdp->sd_reclaimed);
1889
1890         if (gfs2_glmutex_trylock(gl)) {
1891                 if (queue_empty(gl, &gl->gl_holders) &&
1892                     gl->gl_state != LM_ST_UNLOCKED &&
1893                     demote_ok(gl))
1894                         handle_callback(gl, LM_ST_UNLOCKED);
1895                 gfs2_glmutex_unlock(gl);
1896         }
1897
1898         gfs2_glock_put(gl);
1899 }
1900
1901 /**
1902  * examine_bucket - Call a function for glock in a hash bucket
1903  * @examiner: the function
1904  * @sdp: the filesystem
1905  * @bucket: the bucket
1906  *
1907  * Returns: 1 if the bucket has entries
1908  */
1909
1910 static int examine_bucket(glock_examiner examiner, struct gfs2_sbd *sdp,
1911                           struct gfs2_gl_hash_bucket *bucket)
1912 {
1913         struct glock_plug plug;
1914         struct list_head *tmp;
1915         struct gfs2_glock *gl;
1916         int entries;
1917
1918         /* Add "plug" to end of bucket list, work back up list from there */
1919         memset(&plug.gl_flags, 0, sizeof(unsigned long));
1920         set_bit(GLF_PLUG, &plug.gl_flags);
1921
1922         write_lock(&bucket->hb_lock);
1923         list_add(&plug.gl_list, &bucket->hb_list);
1924         write_unlock(&bucket->hb_lock);
1925
1926         for (;;) {
1927                 write_lock(&bucket->hb_lock);
1928
1929                 for (;;) {
1930                         tmp = plug.gl_list.next;
1931
1932                         if (tmp == &bucket->hb_list) {
1933                                 list_del(&plug.gl_list);
1934                                 entries = !list_empty(&bucket->hb_list);
1935                                 write_unlock(&bucket->hb_lock);
1936                                 return entries;
1937                         }
1938                         gl = list_entry(tmp, struct gfs2_glock, gl_list);
1939
1940                         /* Move plug up list */
1941                         list_move(&plug.gl_list, &gl->gl_list);
1942
1943                         if (test_bit(GLF_PLUG, &gl->gl_flags))
1944                                 continue;
1945
1946                         /* examiner() must glock_put() */
1947                         gfs2_glock_hold(gl);
1948
1949                         break;
1950                 }
1951
1952                 write_unlock(&bucket->hb_lock);
1953
1954                 examiner(gl);
1955         }
1956 }
1957
1958 /**
1959  * scan_glock - look at a glock and see if we can reclaim it
1960  * @gl: the glock to look at
1961  *
1962  */
1963
1964 static void scan_glock(struct gfs2_glock *gl)
1965 {
1966         if (gfs2_glmutex_trylock(gl)) {
1967                 if (gl->gl_ops == &gfs2_inode_glops)
1968                         goto out;
1969                 if (queue_empty(gl, &gl->gl_holders) &&
1970                     gl->gl_state != LM_ST_UNLOCKED &&
1971                     demote_ok(gl))
1972                         goto out_schedule;
1973 out:
1974                 gfs2_glmutex_unlock(gl);
1975         }
1976
1977         gfs2_glock_put(gl);
1978
1979         return;
1980
1981 out_schedule:
1982         gfs2_glmutex_unlock(gl);
1983         gfs2_glock_schedule_for_reclaim(gl);
1984         gfs2_glock_put(gl);
1985 }
1986
1987 /**
1988  * gfs2_scand_internal - Look for glocks and inodes to toss from memory
1989  * @sdp: the filesystem
1990  *
1991  */
1992
1993 void gfs2_scand_internal(struct gfs2_sbd *sdp)
1994 {
1995         unsigned int x;
1996
1997         for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
1998                 examine_bucket(scan_glock, sdp, &sdp->sd_gl_hash[x]);
1999                 cond_resched();
2000         }
2001 }
2002
2003 /**
2004  * clear_glock - look at a glock and see if we can free it from glock cache
2005  * @gl: the glock to look at
2006  *
2007  */
2008
2009 static void clear_glock(struct gfs2_glock *gl)
2010 {
2011         struct gfs2_sbd *sdp = gl->gl_sbd;
2012         int released;
2013
2014         spin_lock(&sdp->sd_reclaim_lock);
2015         if (!list_empty(&gl->gl_reclaim)) {
2016                 list_del_init(&gl->gl_reclaim);
2017                 atomic_dec(&sdp->sd_reclaim_count);
2018                 spin_unlock(&sdp->sd_reclaim_lock);
2019                 released = gfs2_glock_put(gl);
2020                 gfs2_assert(sdp, !released);
2021         } else {
2022                 spin_unlock(&sdp->sd_reclaim_lock);
2023         }
2024
2025         if (gfs2_glmutex_trylock(gl)) {
2026                 if (queue_empty(gl, &gl->gl_holders) &&
2027                     gl->gl_state != LM_ST_UNLOCKED)
2028                         handle_callback(gl, LM_ST_UNLOCKED);
2029
2030                 gfs2_glmutex_unlock(gl);
2031         }
2032
2033         gfs2_glock_put(gl);
2034 }
2035
2036 /**
2037  * gfs2_gl_hash_clear - Empty out the glock hash table
2038  * @sdp: the filesystem
2039  * @wait: wait until it's all gone
2040  *
2041  * Called when unmounting the filesystem, or when inter-node lock manager
2042  * requests DROPLOCKS because it is running out of capacity.
2043  */
2044
2045 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp, int wait)
2046 {
2047         unsigned long t;
2048         unsigned int x;
2049         int cont;
2050
2051         t = jiffies;
2052
2053         for (;;) {
2054                 cont = 0;
2055
2056                 for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
2057                         if (examine_bucket(clear_glock, sdp,
2058                                            &sdp->sd_gl_hash[x]))
2059                                 cont = 1;
2060
2061                 if (!wait || !cont)
2062                         break;
2063
2064                 if (time_after_eq(jiffies,
2065                                   t + gfs2_tune_get(sdp, gt_stall_secs) * HZ)) {
2066                         fs_warn(sdp, "Unmount seems to be stalled. "
2067                                      "Dumping lock state...\n");
2068                         gfs2_dump_lockstate(sdp);
2069                         t = jiffies;
2070                 }
2071
2072                 /* invalidate_inodes() requires that the sb inodes list
2073                    not change, but an async completion callback for an
2074                    unlock can occur which does glock_put() which
2075                    can call iput() which will change the sb inodes list.
2076                    invalidate_inodes_mutex prevents glock_put()'s during
2077                    an invalidate_inodes() */
2078
2079                 mutex_lock(&sdp->sd_invalidate_inodes_mutex);
2080                 invalidate_inodes(sdp->sd_vfs);
2081                 mutex_unlock(&sdp->sd_invalidate_inodes_mutex);
2082                 msleep(10);
2083         }
2084 }
2085
2086 /*
2087  *  Diagnostic routines to help debug distributed deadlock
2088  */
2089
2090 /**
2091  * dump_holder - print information about a glock holder
2092  * @str: a string naming the type of holder
2093  * @gh: the glock holder
2094  *
2095  * Returns: 0 on success, -ENOBUFS when we run out of space
2096  */
2097
2098 static int dump_holder(char *str, struct gfs2_holder *gh)
2099 {
2100         unsigned int x;
2101         int error = -ENOBUFS;
2102
2103         printk(KERN_INFO "  %s\n", str);
2104         printk(KERN_INFO "    owner = %ld\n",
2105                    (gh->gh_owner) ? (long)gh->gh_owner->pid : -1);
2106         printk(KERN_INFO "    gh_state = %u\n", gh->gh_state);
2107         printk(KERN_INFO "    gh_flags =");
2108         for (x = 0; x < 32; x++)
2109                 if (gh->gh_flags & (1 << x))
2110                         printk(" %u", x);
2111         printk(" \n");
2112         printk(KERN_INFO "    error = %d\n", gh->gh_error);
2113         printk(KERN_INFO "    gh_iflags =");
2114         for (x = 0; x < 32; x++)
2115                 if (test_bit(x, &gh->gh_iflags))
2116                         printk(" %u", x);
2117         printk(" \n");
2118         print_symbol(KERN_INFO "    initialized at: %s\n", gh->gh_ip);
2119
2120         error = 0;
2121
2122         return error;
2123 }
2124
2125 /**
2126  * dump_inode - print information about an inode
2127  * @ip: the inode
2128  *
2129  * Returns: 0 on success, -ENOBUFS when we run out of space
2130  */
2131
2132 static int dump_inode(struct gfs2_inode *ip)
2133 {
2134         unsigned int x;
2135         int error = -ENOBUFS;
2136
2137         printk(KERN_INFO "  Inode:\n");
2138         printk(KERN_INFO "    num = %llu %llu\n",
2139                     (unsigned long long)ip->i_num.no_formal_ino,
2140                     (unsigned long long)ip->i_num.no_addr);
2141         printk(KERN_INFO "    type = %u\n", IF2DT(ip->i_di.di_mode));
2142         printk(KERN_INFO "    i_flags =");
2143         for (x = 0; x < 32; x++)
2144                 if (test_bit(x, &ip->i_flags))
2145                         printk(" %u", x);
2146         printk(" \n");
2147
2148         error = 0;
2149
2150         return error;
2151 }
2152
2153 /**
2154  * dump_glock - print information about a glock
2155  * @gl: the glock
2156  * @count: where we are in the buffer
2157  *
2158  * Returns: 0 on success, -ENOBUFS when we run out of space
2159  */
2160
2161 static int dump_glock(struct gfs2_glock *gl)
2162 {
2163         struct gfs2_holder *gh;
2164         unsigned int x;
2165         int error = -ENOBUFS;
2166
2167         spin_lock(&gl->gl_spin);
2168
2169         printk(KERN_INFO "Glock (%u, %llu)\n", gl->gl_name.ln_type,
2170                (unsigned long long)gl->gl_name.ln_number);
2171         printk(KERN_INFO "  gl_flags =");
2172         for (x = 0; x < 32; x++)
2173                 if (test_bit(x, &gl->gl_flags))
2174                         printk(" %u", x);
2175         printk(" \n");
2176         printk(KERN_INFO "  gl_ref = %d\n", atomic_read(&gl->gl_ref.refcount));
2177         printk(KERN_INFO "  gl_state = %u\n", gl->gl_state);
2178         printk(KERN_INFO "  gl_owner = %s\n", gl->gl_owner->comm);
2179         print_symbol(KERN_INFO "  gl_ip = %s\n", gl->gl_ip);
2180         printk(KERN_INFO "  req_gh = %s\n", (gl->gl_req_gh) ? "yes" : "no");
2181         printk(KERN_INFO "  req_bh = %s\n", (gl->gl_req_bh) ? "yes" : "no");
2182         printk(KERN_INFO "  lvb_count = %d\n", atomic_read(&gl->gl_lvb_count));
2183         printk(KERN_INFO "  object = %s\n", (gl->gl_object) ? "yes" : "no");
2184         printk(KERN_INFO "  le = %s\n",
2185                    (list_empty(&gl->gl_le.le_list)) ? "no" : "yes");
2186         printk(KERN_INFO "  reclaim = %s\n",
2187                     (list_empty(&gl->gl_reclaim)) ? "no" : "yes");
2188         if (gl->gl_aspace)
2189                 printk(KERN_INFO "  aspace = %lu\n",
2190                             gl->gl_aspace->i_mapping->nrpages);
2191         else
2192                 printk(KERN_INFO "  aspace = no\n");
2193         printk(KERN_INFO "  ail = %d\n", atomic_read(&gl->gl_ail_count));
2194         if (gl->gl_req_gh) {
2195                 error = dump_holder("Request", gl->gl_req_gh);
2196                 if (error)
2197                         goto out;
2198         }
2199         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
2200                 error = dump_holder("Holder", gh);
2201                 if (error)
2202                         goto out;
2203         }
2204         list_for_each_entry(gh, &gl->gl_waiters1, gh_list) {
2205                 error = dump_holder("Waiter1", gh);
2206                 if (error)
2207                         goto out;
2208         }
2209         list_for_each_entry(gh, &gl->gl_waiters2, gh_list) {
2210                 error = dump_holder("Waiter2", gh);
2211                 if (error)
2212                         goto out;
2213         }
2214         list_for_each_entry(gh, &gl->gl_waiters3, gh_list) {
2215                 error = dump_holder("Waiter3", gh);
2216                 if (error)
2217                         goto out;
2218         }
2219         if (gl->gl_ops == &gfs2_inode_glops && gl->gl_object) {
2220                 if (!test_bit(GLF_LOCK, &gl->gl_flags) &&
2221                     list_empty(&gl->gl_holders)) {
2222                         error = dump_inode(gl->gl_object);
2223                         if (error)
2224                                 goto out;
2225                 } else {
2226                         error = -ENOBUFS;
2227                         printk(KERN_INFO "  Inode: busy\n");
2228                 }
2229         }
2230
2231         error = 0;
2232
2233  out:
2234         spin_unlock(&gl->gl_spin);
2235
2236         return error;
2237 }
2238
2239 /**
2240  * gfs2_dump_lockstate - print out the current lockstate
2241  * @sdp: the filesystem
2242  * @ub: the buffer to copy the information into
2243  *
2244  * If @ub is NULL, dump the lockstate to the console.
2245  *
2246  */
2247
2248 static int gfs2_dump_lockstate(struct gfs2_sbd *sdp)
2249 {
2250         struct gfs2_gl_hash_bucket *bucket;
2251         struct gfs2_glock *gl;
2252         unsigned int x;
2253         int error = 0;
2254
2255         for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
2256                 bucket = &sdp->sd_gl_hash[x];
2257
2258                 read_lock(&bucket->hb_lock);
2259
2260                 list_for_each_entry(gl, &bucket->hb_list, gl_list) {
2261                         if (test_bit(GLF_PLUG, &gl->gl_flags))
2262                                 continue;
2263
2264                         error = dump_glock(gl);
2265                         if (error)
2266                                 break;
2267                 }
2268
2269                 read_unlock(&bucket->hb_lock);
2270
2271                 if (error)
2272                         break;
2273         }
2274
2275
2276         return error;
2277 }
2278