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             glops == &gfs2_meta_glops) {
 316                 gl->gl_aspace = gfs2_aspace_get(sdp);
 317                 if (!gl->gl_aspace) {
 318                         error = -ENOMEM;
 319                         goto fail;
 320                 }
 321         }
 322
 323         error = gfs2_lm_get_lock(sdp, &name, &gl->gl_lock);
 324         if (error)
 325                 goto fail_aspace;
 326
 327         write_lock(&bucket->hb_lock);
 328         tmp = search_bucket(bucket, &name);
 329         if (tmp) {
 330                 write_unlock(&bucket->hb_lock);
 331                 glock_free(gl);
 332                 gl = tmp;
 333         } else {
 334                 list_add_tail(&gl->gl_list, &bucket->hb_list);
 335                 write_unlock(&bucket->hb_lock);
 336         }
 337
 338         *glp = gl;
 339
 340         return 0;
 341
 342  fail_aspace:
 343         if (gl->gl_aspace)
 344                 gfs2_aspace_put(gl->gl_aspace);
 345
 346  fail:
 347         kmem_cache_free(gfs2_glock_cachep, gl);
 348
 349         return error;
 350 }
 351
 352 /**
 353  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
 354  * @gl: the glock
 355  * @state: the state we're requesting
 356  * @flags: the modifier flags
 357  * @gh: the holder structure
 358  *
 359  */
 360
 361 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
 362                       struct gfs2_holder *gh)
 363 {
 364         INIT_LIST_HEAD(&gh->gh_list);
 365         gh->gh_gl = gl;
 366         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 367         gh->gh_owner = current;
 368         gh->gh_state = state;
 369         gh->gh_flags = flags;
 370         gh->gh_error = 0;
 371         gh->gh_iflags = 0;
 372         init_completion(&gh->gh_wait);
 373
 374         if (gh->gh_state == LM_ST_EXCLUSIVE)
 375                 gh->gh_flags |= GL_LOCAL_EXCL;
 376
 377         gfs2_glock_hold(gl);
 378 }
 379
 380 /**
 381  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
 382  * @state: the state we're requesting
 383  * @flags: the modifier flags
 384  * @gh: the holder structure
 385  *
 386  * Don't mess with the glock.
 387  *
 388  */
 389
 390 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
 391 {
 392         gh->gh_state = state;
 393         gh->gh_flags = flags;
 394         if (gh->gh_state == LM_ST_EXCLUSIVE)
 395                 gh->gh_flags |= GL_LOCAL_EXCL;
 396
 397         gh->gh_iflags &= 1 << HIF_ALLOCED;
 398         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 399 }
 400
 401 /**
 402  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 403  * @gh: the holder structure
 404  *
 405  */
 406
 407 void gfs2_holder_uninit(struct gfs2_holder *gh)
 408 {
 409         gfs2_glock_put(gh->gh_gl);
 410         gh->gh_gl = NULL;
 411         gh->gh_ip = 0;
 412 }
 413
 414 /**
 415  * gfs2_holder_get - get a struct gfs2_holder structure
 416  * @gl: the glock
 417  * @state: the state we're requesting
 418  * @flags: the modifier flags
 419  * @gfp_flags: __GFP_NOFAIL
 420  *
 421  * Figure out how big an impact this function has.  Either:
 422  * 1) Replace it with a cache of structures hanging off the struct gfs2_sbd
 423  * 2) Leave it like it is
 424  *
 425  * Returns: the holder structure, NULL on ENOMEM
 426  */
 427
 428 static struct gfs2_holder *gfs2_holder_get(struct gfs2_glock *gl,
 429                                            unsigned int state,
 430                                            int flags, gfp_t gfp_flags)
 431 {
 432         struct gfs2_holder *gh;
 433
 434         gh = kmalloc(sizeof(struct gfs2_holder), gfp_flags);
 435         if (!gh)
 436                 return NULL;
 437
 438         gfs2_holder_init(gl, state, flags, gh);
 439         set_bit(HIF_ALLOCED, &gh->gh_iflags);
 440         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 441         return gh;
 442 }
 443
 444 /**
 445  * gfs2_holder_put - get rid of a struct gfs2_holder structure
 446  * @gh: the holder structure
 447  *
 448  */
 449
 450 static void gfs2_holder_put(struct gfs2_holder *gh)
 451 {
 452         gfs2_holder_uninit(gh);
 453         kfree(gh);
 454 }
 455
 456 /**
 457  * rq_mutex - process a mutex request in the queue
 458  * @gh: the glock holder
 459  *
 460  * Returns: 1 if the queue is blocked
 461  */
 462
 463 static int rq_mutex(struct gfs2_holder *gh)
 464 {
 465         struct gfs2_glock *gl = gh->gh_gl;
 466
 467         list_del_init(&gh->gh_list);
 468         /*  gh->gh_error never examined.  */
 469         set_bit(GLF_LOCK, &gl->gl_flags);
 470         complete(&gh->gh_wait);
 471
 472         return 1;
 473 }
 474
 475 /**
 476  * rq_promote - process a promote request in the queue
 477  * @gh: the glock holder
 478  *
 479  * Acquire a new inter-node lock, or change a lock state to more restrictive.
 480  *
 481  * Returns: 1 if the queue is blocked
 482  */
 483
 484 static int rq_promote(struct gfs2_holder *gh)
 485 {
 486         struct gfs2_glock *gl = gh->gh_gl;
 487         struct gfs2_sbd *sdp = gl->gl_sbd;
 488         struct gfs2_glock_operations *glops = gl->gl_ops;
 489
 490         if (!relaxed_state_ok(gl->gl_state, gh->gh_state, gh->gh_flags)) {
 491                 if (list_empty(&gl->gl_holders)) {
 492                         gl->gl_req_gh = gh;
 493                         set_bit(GLF_LOCK, &gl->gl_flags);
 494                         spin_unlock(&gl->gl_spin);
 495
 496                         if (atomic_read(&sdp->sd_reclaim_count) >
 497                             gfs2_tune_get(sdp, gt_reclaim_limit) &&
 498                             !(gh->gh_flags & LM_FLAG_PRIORITY)) {
 499                                 gfs2_reclaim_glock(sdp);
 500                                 gfs2_reclaim_glock(sdp);
 501                         }
 502
 503                         glops->go_xmote_th(gl, gh->gh_state,
 504                                            gh->gh_flags);
 505
 506                         spin_lock(&gl->gl_spin);
 507                 }
 508                 return 1;
 509         }
 510
 511         if (list_empty(&gl->gl_holders)) {
 512                 set_bit(HIF_FIRST, &gh->gh_iflags);
 513                 set_bit(GLF_LOCK, &gl->gl_flags);
 514         } else {
 515                 struct gfs2_holder *next_gh;
 516                 if (gh->gh_flags & GL_LOCAL_EXCL)
 517                         return 1;
 518                 next_gh = list_entry(gl->gl_holders.next, struct gfs2_holder,
 519                                      gh_list);
 520                 if (next_gh->gh_flags & GL_LOCAL_EXCL)
 521                          return 1;
 522         }
 523
 524         list_move_tail(&gh->gh_list, &gl->gl_holders);
 525         gh->gh_error = 0;
 526         set_bit(HIF_HOLDER, &gh->gh_iflags);
 527
 528         complete(&gh->gh_wait);
 529
 530         return 0;
 531 }
 532
 533 /**
 534  * rq_demote - process a demote request in the queue
 535  * @gh: the glock holder
 536  *
 537  * Returns: 1 if the queue is blocked
 538  */
 539
 540 static int rq_demote(struct gfs2_holder *gh)
 541 {
 542         struct gfs2_glock *gl = gh->gh_gl;
 543         struct gfs2_glock_operations *glops = gl->gl_ops;
 544
 545         if (!list_empty(&gl->gl_holders))
 546                 return 1;
 547
 548         if (gl->gl_state == gh->gh_state || gl->gl_state == LM_ST_UNLOCKED) {
 549                 list_del_init(&gh->gh_list);
 550                 gh->gh_error = 0;
 551                 spin_unlock(&gl->gl_spin);
 552                 if (test_bit(HIF_DEALLOC, &gh->gh_iflags))
 553                         gfs2_holder_put(gh);
 554                 else
 555                         complete(&gh->gh_wait);
 556                 spin_lock(&gl->gl_spin);
 557         } else {
 558                 gl->gl_req_gh = gh;
 559                 set_bit(GLF_LOCK, &gl->gl_flags);
 560                 spin_unlock(&gl->gl_spin);
 561
 562                 if (gh->gh_state == LM_ST_UNLOCKED ||
 563                     gl->gl_state != LM_ST_EXCLUSIVE)
 564                         glops->go_drop_th(gl);
 565                 else
 566                         glops->go_xmote_th(gl, gh->gh_state, gh->gh_flags);
 567
 568                 spin_lock(&gl->gl_spin);
 569         }
 570
 571         return 0;
 572 }
 573
 574 /**
 575  * rq_greedy - process a queued request to drop greedy status
 576  * @gh: the glock holder
 577  *
 578  * Returns: 1 if the queue is blocked
 579  */
 580
 581 static int rq_greedy(struct gfs2_holder *gh)
 582 {
 583         struct gfs2_glock *gl = gh->gh_gl;
 584
 585         list_del_init(&gh->gh_list);
 586         /*  gh->gh_error never examined.  */
 587         clear_bit(GLF_GREEDY, &gl->gl_flags);
 588         spin_unlock(&gl->gl_spin);
 589
 590         gfs2_holder_uninit(gh);
 591         kfree(container_of(gh, struct greedy, gr_gh));
 592
 593         spin_lock(&gl->gl_spin);
 594
 595         return 0;
 596 }
 597
 598 /**
 599  * run_queue - process holder structures on a glock
 600  * @gl: the glock
 601  *
 602  */
 603 static void run_queue(struct gfs2_glock *gl)
 604 {
 605         struct gfs2_holder *gh;
 606         int blocked = 1;
 607
 608         for (;;) {
 609                 if (test_bit(GLF_LOCK, &gl->gl_flags))
 610                         break;
 611
 612                 if (!list_empty(&gl->gl_waiters1)) {
 613                         gh = list_entry(gl->gl_waiters1.next,
 614                                         struct gfs2_holder, gh_list);
 615
 616                         if (test_bit(HIF_MUTEX, &gh->gh_iflags))
 617                                 blocked = rq_mutex(gh);
 618                         else
 619                                 gfs2_assert_warn(gl->gl_sbd, 0);
 620
 621                 } else if (!list_empty(&gl->gl_waiters2) &&
 622                            !test_bit(GLF_SKIP_WAITERS2, &gl->gl_flags)) {
 623                         gh = list_entry(gl->gl_waiters2.next,
 624                                         struct gfs2_holder, gh_list);
 625
 626                         if (test_bit(HIF_DEMOTE, &gh->gh_iflags))
 627                                 blocked = rq_demote(gh);
 628                         else if (test_bit(HIF_GREEDY, &gh->gh_iflags))
 629                                 blocked = rq_greedy(gh);
 630                         else
 631                                 gfs2_assert_warn(gl->gl_sbd, 0);
 632
 633                 } else if (!list_empty(&gl->gl_waiters3)) {
 634                         gh = list_entry(gl->gl_waiters3.next,
 635                                         struct gfs2_holder, gh_list);
 636
 637                         if (test_bit(HIF_PROMOTE, &gh->gh_iflags))
 638                                 blocked = rq_promote(gh);
 639                         else
 640                                 gfs2_assert_warn(gl->gl_sbd, 0);
 641
 642                 } else
 643                         break;
 644
 645                 if (blocked)
 646                         break;
 647         }
 648 }
 649
 650 /**
 651  * gfs2_glmutex_lock - acquire a local lock on a glock
 652  * @gl: the glock
 653  *
 654  * Gives caller exclusive access to manipulate a glock structure.
 655  */
 656
 657 static void gfs2_glmutex_lock(struct gfs2_glock *gl)
 658 {
 659         struct gfs2_holder gh;
 660
 661         gfs2_holder_init(gl, 0, 0, &gh);
 662         set_bit(HIF_MUTEX, &gh.gh_iflags);
 663
 664         spin_lock(&gl->gl_spin);
 665         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 666                 list_add_tail(&gh.gh_list, &gl->gl_waiters1);
 667         else {
 668                 gl->gl_owner = current;
 669                 gl->gl_ip = (unsigned long)__builtin_return_address(0);
 670                 complete(&gh.gh_wait);
 671         }
 672         spin_unlock(&gl->gl_spin);
 673
 674         wait_for_completion(&gh.gh_wait);
 675         gfs2_holder_uninit(&gh);
 676 }
 677
 678 /**
 679  * gfs2_glmutex_trylock - try to acquire a local lock on a glock
 680  * @gl: the glock
 681  *
 682  * Returns: 1 if the glock is acquired
 683  */
 684
 685 static int gfs2_glmutex_trylock(struct gfs2_glock *gl)
 686 {
 687         int acquired = 1;
 688
 689         spin_lock(&gl->gl_spin);
 690         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 691                 acquired = 0;
 692         else {
 693                 gl->gl_owner = current;
 694                 gl->gl_ip = (unsigned long)__builtin_return_address(0);
 695         }
 696         spin_unlock(&gl->gl_spin);
 697
 698         return acquired;
 699 }
 700
 701 /**
 702  * gfs2_glmutex_unlock - release a local lock on a glock
 703  * @gl: the glock
 704  *
 705  */
 706
 707 static void gfs2_glmutex_unlock(struct gfs2_glock *gl)
 708 {
 709         spin_lock(&gl->gl_spin);
 710         clear_bit(GLF_LOCK, &gl->gl_flags);
 711         gl->gl_owner = NULL;
 712         gl->gl_ip = 0;
 713         run_queue(gl);
 714         BUG_ON(!spin_is_locked(&gl->gl_spin));
 715         spin_unlock(&gl->gl_spin);
 716 }
 717
 718 /**
 719  * handle_callback - add a demote request to a lock's queue
 720  * @gl: the glock
 721  * @state: the state the caller wants us to change to
 722  *
 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,
 748                                          GFP_KERNEL | __GFP_NOFAIL),
 749                 set_bit(HIF_DEMOTE, &new_gh->gh_iflags);
 750                 set_bit(HIF_DEALLOC, &new_gh->gh_iflags);
 751
 752                 goto restart;
 753         }
 754
 755 out:
 756         spin_unlock(&gl->gl_spin);
 757
 758         if (new_gh)
 759                 gfs2_holder_put(new_gh);
 760 }
 761
 762 void gfs2_glock_inode_squish(struct inode *inode)
 763 {
 764         struct gfs2_holder gh;
 765         struct gfs2_glock *gl = GFS2_I(inode)->i_gl;
 766         gfs2_holder_init(gl, LM_ST_UNLOCKED, 0, &gh);
 767         set_bit(HIF_DEMOTE, &gh.gh_iflags);
 768         spin_lock(&gl->gl_spin);
 769         gfs2_assert(inode->i_sb->s_fs_info, list_empty(&gl->gl_holders));
 770         list_add_tail(&gh.gh_list, &gl->gl_waiters2);
 771         run_queue(gl);
 772         spin_unlock(&gl->gl_spin);
 773         gfs2_holder_uninit(&gh);
 774 }
 775
 776 /**
 777  * state_change - record that the glock is now in a different state
 778  * @gl: the glock
 779  * @new_state the new state
 780  *
 781  */
 782
 783 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 784 {
 785         int held1, held2;
 786
 787         held1 = (gl->gl_state != LM_ST_UNLOCKED);
 788         held2 = (new_state != LM_ST_UNLOCKED);
 789
 790         if (held1 != held2) {
 791                 if (held2)
 792                         gfs2_glock_hold(gl);
 793                 else
 794                         gfs2_glock_put(gl);
 795         }
 796
 797         gl->gl_state = new_state;
 798 }
 799
 800 /**
 801  * xmote_bh - Called after the lock module is done acquiring a lock
 802  * @gl: The glock in question
 803  * @ret: the int returned from the lock module
 804  *
 805  */
 806
 807 static void xmote_bh(struct gfs2_glock *gl, unsigned int ret)
 808 {
 809         struct gfs2_sbd *sdp = gl->gl_sbd;
 810         struct gfs2_glock_operations *glops = gl->gl_ops;
 811         struct gfs2_holder *gh = gl->gl_req_gh;
 812         int prev_state = gl->gl_state;
 813         int op_done = 1;
 814
 815         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
 816         gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
 817         gfs2_assert_warn(sdp, !(ret & LM_OUT_ASYNC));
 818
 819         state_change(gl, ret & LM_OUT_ST_MASK);
 820
 821         if (prev_state != LM_ST_UNLOCKED && !(ret & LM_OUT_CACHEABLE)) {
 822                 if (glops->go_inval)
 823                         glops->go_inval(gl, DIO_METADATA | DIO_DATA);
 824         } else if (gl->gl_state == LM_ST_DEFERRED) {
 825                 /* We might not want to do this here.
 826                    Look at moving to the inode glops. */
 827                 if (glops->go_inval)
 828                         glops->go_inval(gl, DIO_DATA);
 829         }
 830
 831         /*  Deal with each possible exit condition  */
 832
 833         if (!gh)
 834                 gl->gl_stamp = jiffies;
 835
 836         else if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
 837                 spin_lock(&gl->gl_spin);
 838                 list_del_init(&gh->gh_list);
 839                 gh->gh_error = -EIO;
 840                 spin_unlock(&gl->gl_spin);
 841
 842         } else if (test_bit(HIF_DEMOTE, &gh->gh_iflags)) {
 843                 spin_lock(&gl->gl_spin);
 844                 list_del_init(&gh->gh_list);
 845                 if (gl->gl_state == gh->gh_state ||
 846                     gl->gl_state == LM_ST_UNLOCKED)
 847                         gh->gh_error = 0;
 848                 else {
 849                         if (gfs2_assert_warn(sdp, gh->gh_flags &
 850                                         (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) == -1)
 851                                 fs_warn(sdp, "ret = 0x%.8X\n", ret);
 852                         gh->gh_error = GLR_TRYFAILED;
 853                 }
 854                 spin_unlock(&gl->gl_spin);
 855
 856                 if (ret & LM_OUT_CANCELED)
 857                         handle_callback(gl, LM_ST_UNLOCKED); /* Lame */
 858
 859         } else if (ret & LM_OUT_CANCELED) {
 860                 spin_lock(&gl->gl_spin);
 861                 list_del_init(&gh->gh_list);
 862                 gh->gh_error = GLR_CANCELED;
 863                 spin_unlock(&gl->gl_spin);
 864
 865         } else if (relaxed_state_ok(gl->gl_state, gh->gh_state, gh->gh_flags)) {
 866                 spin_lock(&gl->gl_spin);
 867                 list_move_tail(&gh->gh_list, &gl->gl_holders);
 868                 gh->gh_error = 0;
 869                 set_bit(HIF_HOLDER, &gh->gh_iflags);
 870                 spin_unlock(&gl->gl_spin);
 871
 872                 set_bit(HIF_FIRST, &gh->gh_iflags);
 873
 874                 op_done = 0;
 875
 876         } else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
 877                 spin_lock(&gl->gl_spin);
 878                 list_del_init(&gh->gh_list);
 879                 gh->gh_error = GLR_TRYFAILED;
 880                 spin_unlock(&gl->gl_spin);
 881
 882         } else {
 883                 if (gfs2_assert_withdraw(sdp, 0) == -1)
 884                         fs_err(sdp, "ret = 0x%.8X\n", ret);
 885         }
 886
 887         if (glops->go_xmote_bh)
 888                 glops->go_xmote_bh(gl);
 889
 890         if (op_done) {
 891                 spin_lock(&gl->gl_spin);
 892                 gl->gl_req_gh = NULL;
 893                 gl->gl_req_bh = NULL;
 894                 clear_bit(GLF_LOCK, &gl->gl_flags);
 895                 run_queue(gl);
 896                 spin_unlock(&gl->gl_spin);
 897         }
 898
 899         gfs2_glock_put(gl);
 900
 901         if (gh) {
 902                 if (test_bit(HIF_DEALLOC, &gh->gh_iflags))
 903                         gfs2_holder_put(gh);
 904                 else
 905                         complete(&gh->gh_wait);
 906         }
 907 }
 908
 909 /**
 910  * gfs2_glock_xmote_th - Call into the lock module to acquire or change a glock
 911  * @gl: The glock in question
 912  * @state: the requested state
 913  * @flags: modifier flags to the lock call
 914  *
 915  */
 916
 917 void gfs2_glock_xmote_th(struct gfs2_glock *gl, unsigned int state, int flags)
 918 {
 919         struct gfs2_sbd *sdp = gl->gl_sbd;
 920         struct gfs2_glock_operations *glops = gl->gl_ops;
 921         int lck_flags = flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB |
 922                                  LM_FLAG_NOEXP | LM_FLAG_ANY |
 923                                  LM_FLAG_PRIORITY);
 924         unsigned int lck_ret;
 925
 926         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
 927         gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
 928         gfs2_assert_warn(sdp, state != LM_ST_UNLOCKED);
 929         gfs2_assert_warn(sdp, state != gl->gl_state);
 930
 931         if (gl->gl_state == LM_ST_EXCLUSIVE) {
 932                 if (glops->go_sync)
 933                         glops->go_sync(gl,
 934                                        DIO_METADATA | DIO_DATA | DIO_RELEASE);
 935         }
 936
 937         gfs2_glock_hold(gl);
 938         gl->gl_req_bh = xmote_bh;
 939
 940         lck_ret = gfs2_lm_lock(sdp, gl->gl_lock, gl->gl_state, state,
 941                                lck_flags);
 942
 943         if (gfs2_assert_withdraw(sdp, !(lck_ret & LM_OUT_ERROR)))
 944                 return;
 945
 946         if (lck_ret & LM_OUT_ASYNC)
 947                 gfs2_assert_warn(sdp, lck_ret == LM_OUT_ASYNC);
 948         else
 949                 xmote_bh(gl, lck_ret);
 950 }
 951
 952 /**
 953  * drop_bh - Called after a lock module unlock completes
 954  * @gl: the glock
 955  * @ret: the return status
 956  *
 957  * Doesn't wake up the process waiting on the struct gfs2_holder (if any)
 958  * Doesn't drop the reference on the glock the top half took out
 959  *
 960  */
 961
 962 static void drop_bh(struct gfs2_glock *gl, unsigned int ret)
 963 {
 964         struct gfs2_sbd *sdp = gl->gl_sbd;
 965         struct gfs2_glock_operations *glops = gl->gl_ops;
 966         struct gfs2_holder *gh = gl->gl_req_gh;
 967
 968         clear_bit(GLF_PREFETCH, &gl->gl_flags);
 969
 970         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
 971         gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
 972         gfs2_assert_warn(sdp, !ret);
 973
 974         state_change(gl, LM_ST_UNLOCKED);
 975
 976         if (glops->go_inval)
 977                 glops->go_inval(gl, DIO_METADATA | DIO_DATA);
 978
 979         if (gh) {
 980                 spin_lock(&gl->gl_spin);
 981                 list_del_init(&gh->gh_list);
 982                 gh->gh_error = 0;
 983                 spin_unlock(&gl->gl_spin);
 984         }
 985
 986         if (glops->go_drop_bh)
 987                 glops->go_drop_bh(gl);
 988
 989         spin_lock(&gl->gl_spin);
 990         gl->gl_req_gh = NULL;
 991         gl->gl_req_bh = NULL;
 992         clear_bit(GLF_LOCK, &gl->gl_flags);
 993         run_queue(gl);
 994         spin_unlock(&gl->gl_spin);
 995
 996         gfs2_glock_put(gl);
 997
 998         if (gh) {
 999                 if (test_bit(HIF_DEALLOC, &gh->gh_iflags))
1000                         gfs2_holder_put(gh);
1001                 else
1002                         complete(&gh->gh_wait);
1003         }
1004 }
1005
1006 /**
1007  * gfs2_glock_drop_th - call into the lock module to unlock a lock
1008  * @gl: the glock
1009  *
1010  */
1011
1012 void gfs2_glock_drop_th(struct gfs2_glock *gl)
1013 {
1014         struct gfs2_sbd *sdp = gl->gl_sbd;
1015         struct gfs2_glock_operations *glops = gl->gl_ops;
1016         unsigned int ret;
1017
1018         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
1019         gfs2_assert_warn(sdp, queue_empty(gl, &gl->gl_holders));
1020         gfs2_assert_warn(sdp, gl->gl_state != LM_ST_UNLOCKED);
1021
1022         if (gl->gl_state == LM_ST_EXCLUSIVE) {
1023                 if (glops->go_sync)
1024                         glops->go_sync(gl,
1025                                        DIO_METADATA | DIO_DATA | DIO_RELEASE);
1026         }
1027
1028         gfs2_glock_hold(gl);
1029         gl->gl_req_bh = drop_bh;
1030
1031         ret = gfs2_lm_unlock(sdp, gl->gl_lock, gl->gl_state);
1032
1033         if (gfs2_assert_withdraw(sdp, !(ret & LM_OUT_ERROR)))
1034                 return;
1035
1036         if (!ret)
1037                 drop_bh(gl, ret);
1038         else
1039                 gfs2_assert_warn(sdp, ret == LM_OUT_ASYNC);
1040 }
1041
1042 /**
1043  * do_cancels - cancel requests for locks stuck waiting on an expire flag
1044  * @gh: the LM_FLAG_PRIORITY holder waiting to acquire the lock
1045  *
1046  * Don't cancel GL_NOCANCEL requests.
1047  */
1048
1049 static void do_cancels(struct gfs2_holder *gh)
1050 {
1051         struct gfs2_glock *gl = gh->gh_gl;
1052
1053         spin_lock(&gl->gl_spin);
1054
1055         while (gl->gl_req_gh != gh &&
1056                !test_bit(HIF_HOLDER, &gh->gh_iflags) &&
1057                !list_empty(&gh->gh_list)) {
1058                 if (gl->gl_req_bh &&
1059                     !(gl->gl_req_gh &&
1060                       (gl->gl_req_gh->gh_flags & GL_NOCANCEL))) {
1061                         spin_unlock(&gl->gl_spin);
1062                         gfs2_lm_cancel(gl->gl_sbd, gl->gl_lock);
1063                         msleep(100);
1064                         spin_lock(&gl->gl_spin);
1065                 } else {
1066                         spin_unlock(&gl->gl_spin);
1067                         msleep(100);
1068                         spin_lock(&gl->gl_spin);
1069                 }
1070         }
1071
1072         spin_unlock(&gl->gl_spin);
1073 }
1074
1075 /**
1076  * glock_wait_internal - wait on a glock acquisition
1077  * @gh: the glock holder
1078  *
1079  * Returns: 0 on success
1080  */
1081
1082 static int glock_wait_internal(struct gfs2_holder *gh)
1083 {
1084         struct gfs2_glock *gl = gh->gh_gl;
1085         struct gfs2_sbd *sdp = gl->gl_sbd;
1086         struct gfs2_glock_operations *glops = gl->gl_ops;
1087
1088         if (test_bit(HIF_ABORTED, &gh->gh_iflags))
1089                 return -EIO;
1090
1091         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
1092                 spin_lock(&gl->gl_spin);
1093                 if (gl->gl_req_gh != gh &&
1094                     !test_bit(HIF_HOLDER, &gh->gh_iflags) &&
1095                     !list_empty(&gh->gh_list)) {
1096                         list_del_init(&gh->gh_list);
1097                         gh->gh_error = GLR_TRYFAILED;
1098                         run_queue(gl);
1099                         spin_unlock(&gl->gl_spin);
1100                         return gh->gh_error;
1101                 }
1102                 spin_unlock(&gl->gl_spin);
1103         }
1104
1105         if (gh->gh_flags & LM_FLAG_PRIORITY)
1106                 do_cancels(gh);
1107
1108         wait_for_completion(&gh->gh_wait);
1109
1110         if (gh->gh_error)
1111                 return gh->gh_error;
1112
1113         gfs2_assert_withdraw(sdp, test_bit(HIF_HOLDER, &gh->gh_iflags));
1114         gfs2_assert_withdraw(sdp, relaxed_state_ok(gl->gl_state,
1115                                                    gh->gh_state,
1116                                                    gh->gh_flags));
1117
1118         if (test_bit(HIF_FIRST, &gh->gh_iflags)) {
1119                 gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
1120
1121                 if (glops->go_lock) {
1122                         gh->gh_error = glops->go_lock(gh);
1123                         if (gh->gh_error) {
1124                                 spin_lock(&gl->gl_spin);
1125                                 list_del_init(&gh->gh_list);
1126                                 spin_unlock(&gl->gl_spin);
1127                         }
1128                 }
1129
1130                 spin_lock(&gl->gl_spin);
1131                 gl->gl_req_gh = NULL;
1132                 gl->gl_req_bh = NULL;
1133                 clear_bit(GLF_LOCK, &gl->gl_flags);
1134                 run_queue(gl);
1135                 spin_unlock(&gl->gl_spin);
1136         }
1137
1138         return gh->gh_error;
1139 }
1140
1141 static inline struct gfs2_holder *
1142 find_holder_by_owner(struct list_head *head, struct task_struct *owner)
1143 {
1144         struct gfs2_holder *gh;
1145
1146         list_for_each_entry(gh, head, gh_list) {
1147                 if (gh->gh_owner == owner)
1148                         return gh;
1149         }
1150
1151         return NULL;
1152 }
1153
1154 /**
1155  * add_to_queue - Add a holder to the wait queue (but look for recursion)
1156  * @gh: the holder structure to add
1157  *
1158  */
1159
1160 static void add_to_queue(struct gfs2_holder *gh)
1161 {
1162         struct gfs2_glock *gl = gh->gh_gl;
1163         struct gfs2_holder *existing;
1164
1165         BUG_ON(!gh->gh_owner);
1166
1167         existing = find_holder_by_owner(&gl->gl_holders, gh->gh_owner);
1168         if (existing) {
1169                 print_symbol(KERN_WARNING "original: %s\n", existing->gh_ip);
1170                 print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
1171                 BUG();
1172         }
1173
1174         existing = find_holder_by_owner(&gl->gl_waiters3, gh->gh_owner);
1175         if (existing) {
1176                 print_symbol(KERN_WARNING "original: %s\n", existing->gh_ip);
1177                 print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
1178                 BUG();
1179         }
1180
1181         if (gh->gh_flags & LM_FLAG_PRIORITY)
1182                 list_add(&gh->gh_list, &gl->gl_waiters3);
1183         else
1184                 list_add_tail(&gh->gh_list, &gl->gl_waiters3);
1185 }
1186
1187 /**
1188  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1189  * @gh: the holder structure
1190  *
1191  * if (gh->gh_flags & GL_ASYNC), this never returns an error
1192  *
1193  * Returns: 0, GLR_TRYFAILED, or errno on failure
1194  */
1195
1196 int gfs2_glock_nq(struct gfs2_holder *gh)
1197 {
1198         struct gfs2_glock *gl = gh->gh_gl;
1199         struct gfs2_sbd *sdp = gl->gl_sbd;
1200         int error = 0;
1201
1202 restart:
1203         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
1204                 set_bit(HIF_ABORTED, &gh->gh_iflags);
1205                 return -EIO;
1206         }
1207
1208         set_bit(HIF_PROMOTE, &gh->gh_iflags);
1209
1210         spin_lock(&gl->gl_spin);
1211         add_to_queue(gh);
1212         run_queue(gl);
1213         spin_unlock(&gl->gl_spin);
1214
1215         if (!(gh->gh_flags & GL_ASYNC)) {
1216                 error = glock_wait_internal(gh);
1217                 if (error == GLR_CANCELED) {
1218                         msleep(100);
1219                         goto restart;
1220                 }
1221         }
1222
1223         clear_bit(GLF_PREFETCH, &gl->gl_flags);
1224
1225         if (error == GLR_TRYFAILED && (gh->gh_flags & GL_DUMP))
1226                 dump_glock(gl);
1227
1228         return error;
1229 }
1230
1231 /**
1232  * gfs2_glock_poll - poll to see if an async request has been completed
1233  * @gh: the holder
1234  *
1235  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1236  */
1237
1238 int gfs2_glock_poll(struct gfs2_holder *gh)
1239 {
1240         struct gfs2_glock *gl = gh->gh_gl;
1241         int ready = 0;
1242
1243         spin_lock(&gl->gl_spin);
1244
1245         if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1246                 ready = 1;
1247         else if (list_empty(&gh->gh_list)) {
1248                 if (gh->gh_error == GLR_CANCELED) {
1249                         spin_unlock(&gl->gl_spin);
1250                         msleep(100);
1251                         if (gfs2_glock_nq(gh))
1252                                 return 1;
1253                         return 0;
1254                 } else
1255                         ready = 1;
1256         }
1257
1258         spin_unlock(&gl->gl_spin);
1259
1260         return ready;
1261 }
1262
1263 /**
1264  * gfs2_glock_wait - wait for a lock acquisition that ended in a GLR_ASYNC
1265  * @gh: the holder structure
1266  *
1267  * Returns: 0, GLR_TRYFAILED, or errno on failure
1268  */
1269
1270 int gfs2_glock_wait(struct gfs2_holder *gh)
1271 {
1272         int error;
1273
1274         error = glock_wait_internal(gh);
1275         if (error == GLR_CANCELED) {
1276                 msleep(100);
1277                 gh->gh_flags &= ~GL_ASYNC;
1278                 error = gfs2_glock_nq(gh);
1279         }
1280
1281         return error;
1282 }
1283
1284 /**
1285  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1286  * @gh: the glock holder
1287  *
1288  */
1289
1290 void gfs2_glock_dq(struct gfs2_holder *gh)
1291 {
1292         struct gfs2_glock *gl = gh->gh_gl;
1293         struct gfs2_glock_operations *glops = gl->gl_ops;
1294
1295         if (gh->gh_flags & GL_SYNC)
1296                 set_bit(GLF_SYNC, &gl->gl_flags);
1297
1298         if (gh->gh_flags & GL_NOCACHE)
1299                 handle_callback(gl, LM_ST_UNLOCKED);
1300
1301         gfs2_glmutex_lock(gl);
1302
1303         spin_lock(&gl->gl_spin);
1304         list_del_init(&gh->gh_list);
1305
1306         if (list_empty(&gl->gl_holders)) {
1307                 spin_unlock(&gl->gl_spin);
1308
1309                 if (glops->go_unlock)
1310                         glops->go_unlock(gh);
1311
1312                 if (test_bit(GLF_SYNC, &gl->gl_flags)) {
1313                         if (glops->go_sync)
1314                                 glops->go_sync(gl, DIO_METADATA | DIO_DATA);
1315                 }
1316
1317                 gl->gl_stamp = jiffies;
1318
1319                 spin_lock(&gl->gl_spin);
1320         }
1321
1322         clear_bit(GLF_LOCK, &gl->gl_flags);
1323         run_queue(gl);
1324         spin_unlock(&gl->gl_spin);
1325 }
1326
1327 /**
1328  * gfs2_glock_prefetch - Try to prefetch a glock
1329  * @gl: the glock
1330  * @state: the state to prefetch in
1331  * @flags: flags passed to go_xmote_th()
1332  *
1333  */
1334
1335 static void gfs2_glock_prefetch(struct gfs2_glock *gl, unsigned int state,
1336                                 int flags)
1337 {
1338         struct gfs2_glock_operations *glops = gl->gl_ops;
1339
1340         spin_lock(&gl->gl_spin);
1341
1342         if (test_bit(GLF_LOCK, &gl->gl_flags) ||
1343             !list_empty(&gl->gl_holders) ||
1344             !list_empty(&gl->gl_waiters1) ||
1345             !list_empty(&gl->gl_waiters2) ||
1346             !list_empty(&gl->gl_waiters3) ||
1347             relaxed_state_ok(gl->gl_state, state, flags)) {
1348                 spin_unlock(&gl->gl_spin);
1349                 return;
1350         }
1351
1352         set_bit(GLF_PREFETCH, &gl->gl_flags);
1353         set_bit(GLF_LOCK, &gl->gl_flags);
1354         spin_unlock(&gl->gl_spin);
1355
1356         glops->go_xmote_th(gl, state, flags);
1357 }
1358
1359 static void greedy_work(void *data)
1360 {
1361         struct greedy *gr = data;
1362         struct gfs2_holder *gh = &gr->gr_gh;
1363         struct gfs2_glock *gl = gh->gh_gl;
1364         struct gfs2_glock_operations *glops = gl->gl_ops;
1365
1366         clear_bit(GLF_SKIP_WAITERS2, &gl->gl_flags);
1367
1368         if (glops->go_greedy)
1369                 glops->go_greedy(gl);
1370
1371         spin_lock(&gl->gl_spin);
1372
1373         if (list_empty(&gl->gl_waiters2)) {
1374                 clear_bit(GLF_GREEDY, &gl->gl_flags);
1375                 spin_unlock(&gl->gl_spin);
1376                 gfs2_holder_uninit(gh);
1377                 kfree(gr);
1378         } else {
1379                 gfs2_glock_hold(gl);
1380                 list_add_tail(&gh->gh_list, &gl->gl_waiters2);
1381                 run_queue(gl);
1382                 spin_unlock(&gl->gl_spin);
1383                 gfs2_glock_put(gl);
1384         }
1385 }
1386
1387 /**
1388  * gfs2_glock_be_greedy -
1389  * @gl:
1390  * @time:
1391  *
1392  * Returns: 0 if go_greedy will be called, 1 otherwise
1393  */
1394
1395 int gfs2_glock_be_greedy(struct gfs2_glock *gl, unsigned int time)
1396 {
1397         struct greedy *gr;
1398         struct gfs2_holder *gh;
1399
1400         if (!time || gl->gl_sbd->sd_args.ar_localcaching ||
1401             test_and_set_bit(GLF_GREEDY, &gl->gl_flags))
1402                 return 1;
1403
1404         gr = kmalloc(sizeof(struct greedy), GFP_KERNEL);
1405         if (!gr) {
1406                 clear_bit(GLF_GREEDY, &gl->gl_flags);
1407                 return 1;
1408         }
1409         gh = &gr->gr_gh;
1410
1411         gfs2_holder_init(gl, 0, 0, gh);
1412         set_bit(HIF_GREEDY, &gh->gh_iflags);
1413         INIT_WORK(&gr->gr_work, greedy_work, gr);
1414
1415         set_bit(GLF_SKIP_WAITERS2, &gl->gl_flags);
1416         schedule_delayed_work(&gr->gr_work, time);
1417
1418         return 0;
1419 }
1420
1421 /**
1422  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1423  * @gh: the holder structure
1424  *
1425  */
1426
1427 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1428 {
1429         gfs2_glock_dq(gh);
1430         gfs2_holder_uninit(gh);
1431 }
1432
1433 /**
1434  * gfs2_glock_nq_num - acquire a glock based on lock number
1435  * @sdp: the filesystem
1436  * @number: the lock number
1437  * @glops: the glock operations for the type of glock
1438  * @state: the state to acquire the glock in
1439  * @flags: modifier flags for the aquisition
1440  * @gh: the struct gfs2_holder
1441  *
1442  * Returns: errno
1443  */
1444
1445 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, uint64_t number,
1446                       struct gfs2_glock_operations *glops, unsigned int state,
1447                       int flags, struct gfs2_holder *gh)
1448 {
1449         struct gfs2_glock *gl;
1450         int error;
1451
1452         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1453         if (!error) {
1454                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1455                 gfs2_glock_put(gl);
1456         }
1457
1458         return error;
1459 }
1460
1461 /**
1462  * glock_compare - Compare two struct gfs2_glock structures for sorting
1463  * @arg_a: the first structure
1464  * @arg_b: the second structure
1465  *
1466  */
1467
1468 static int glock_compare(const void *arg_a, const void *arg_b)
1469 {
1470         struct gfs2_holder *gh_a = *(struct gfs2_holder **)arg_a;
1471         struct gfs2_holder *gh_b = *(struct gfs2_holder **)arg_b;
1472         struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1473         struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1474         int ret = 0;
1475
1476         if (a->ln_number > b->ln_number)
1477                 ret = 1;
1478         else if (a->ln_number < b->ln_number)
1479                 ret = -1;
1480         else {
1481                 if (gh_a->gh_state == LM_ST_SHARED &&
1482                     gh_b->gh_state == LM_ST_EXCLUSIVE)
1483                         ret = 1;
1484                 else if (!(gh_a->gh_flags & GL_LOCAL_EXCL) &&
1485                          (gh_b->gh_flags & GL_LOCAL_EXCL))
1486                         ret = 1;
1487         }
1488
1489         return ret;
1490 }
1491
1492 /**
1493  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1494  * @num_gh: the number of structures
1495  * @ghs: an array of struct gfs2_holder structures
1496  *
1497  * Returns: 0 on success (all glocks acquired),
1498  *          errno on failure (no glocks acquired)
1499  */
1500
1501 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1502                      struct gfs2_holder **p)
1503 {
1504         unsigned int x;
1505         int error = 0;
1506
1507         for (x = 0; x < num_gh; x++)
1508                 p[x] = &ghs[x];
1509
1510         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1511
1512         for (x = 0; x < num_gh; x++) {
1513                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1514
1515                 error = gfs2_glock_nq(p[x]);
1516                 if (error) {
1517                         while (x--)
1518                                 gfs2_glock_dq(p[x]);
1519                         break;
1520                 }
1521         }
1522
1523         return error;
1524 }
1525
1526 /**
1527  * gfs2_glock_nq_m - acquire multiple glocks
1528  * @num_gh: the number of structures
1529  * @ghs: an array of struct gfs2_holder structures
1530  *
1531  * Figure out how big an impact this function has.  Either:
1532  * 1) Replace this code with code that calls gfs2_glock_prefetch()
1533  * 2) Forget async stuff and just call nq_m_sync()
1534  * 3) Leave it like it is
1535  *
1536  * Returns: 0 on success (all glocks acquired),
1537  *          errno on failure (no glocks acquired)
1538  */
1539
1540 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1541 {
1542         int *e;
1543         unsigned int x;
1544         int borked = 0, serious = 0;
1545         int error = 0;
1546
1547         if (!num_gh)
1548                 return 0;
1549
1550         if (num_gh == 1) {
1551                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1552                 return gfs2_glock_nq(ghs);
1553         }
1554
1555         e = kcalloc(num_gh, sizeof(struct gfs2_holder *), GFP_KERNEL);
1556         if (!e)
1557                 return -ENOMEM;
1558
1559         for (x = 0; x < num_gh; x++) {
1560                 ghs[x].gh_flags |= LM_FLAG_TRY | GL_ASYNC;
1561                 error = gfs2_glock_nq(&ghs[x]);
1562                 if (error) {
1563                         borked = 1;
1564                         serious = error;
1565                         num_gh = x;
1566                         break;
1567                 }
1568         }
1569
1570         for (x = 0; x < num_gh; x++) {
1571                 error = e[x] = glock_wait_internal(&ghs[x]);
1572                 if (error) {
1573                         borked = 1;
1574                         if (error != GLR_TRYFAILED && error != GLR_CANCELED)
1575                                 serious = error;
1576                 }
1577         }
1578
1579         if (!borked) {
1580                 kfree(e);
1581                 return 0;
1582         }
1583
1584         for (x = 0; x < num_gh; x++)
1585                 if (!e[x])
1586                         gfs2_glock_dq(&ghs[x]);
1587
1588         if (serious)
1589                 error = serious;
1590         else {
1591                 for (x = 0; x < num_gh; x++)
1592                         gfs2_holder_reinit(ghs[x].gh_state, ghs[x].gh_flags,
1593                                           &ghs[x]);
1594                 error = nq_m_sync(num_gh, ghs, (struct gfs2_holder **)e);
1595         }
1596
1597         kfree(e);
1598
1599         return error;
1600 }
1601
1602 /**
1603  * gfs2_glock_dq_m - release multiple glocks
1604  * @num_gh: the number of structures
1605  * @ghs: an array of struct gfs2_holder structures
1606  *
1607  */
1608
1609 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1610 {
1611         unsigned int x;
1612
1613         for (x = 0; x < num_gh; x++)
1614                 gfs2_glock_dq(&ghs[x]);
1615 }
1616
1617 /**
1618  * gfs2_glock_dq_uninit_m - release multiple glocks
1619  * @num_gh: the number of structures
1620  * @ghs: an array of struct gfs2_holder structures
1621  *
1622  */
1623
1624 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1625 {
1626         unsigned int x;
1627
1628         for (x = 0; x < num_gh; x++)
1629                 gfs2_glock_dq_uninit(&ghs[x]);
1630 }
1631
1632 /**
1633  * gfs2_glock_prefetch_num - prefetch a glock based on lock number
1634  * @sdp: the filesystem
1635  * @number: the lock number
1636  * @glops: the glock operations for the type of glock
1637  * @state: the state to acquire the glock in
1638  * @flags: modifier flags for the aquisition
1639  *
1640  * Returns: errno
1641  */
1642
1643 void gfs2_glock_prefetch_num(struct gfs2_sbd *sdp, uint64_t number,
1644                              struct gfs2_glock_operations *glops,
1645                              unsigned int state, int flags)
1646 {
1647         struct gfs2_glock *gl;
1648         int error;
1649
1650         if (atomic_read(&sdp->sd_reclaim_count) <
1651             gfs2_tune_get(sdp, gt_reclaim_limit)) {
1652                 error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1653                 if (!error) {
1654                         gfs2_glock_prefetch(gl, state, flags);
1655                         gfs2_glock_put(gl);
1656                 }
1657         }
1658 }
1659
1660 /**
1661  * gfs2_lvb_hold - attach a LVB from a glock
1662  * @gl: The glock in question
1663  *
1664  */
1665
1666 int gfs2_lvb_hold(struct gfs2_glock *gl)
1667 {
1668         int error;
1669
1670         gfs2_glmutex_lock(gl);
1671
1672         if (!atomic_read(&gl->gl_lvb_count)) {
1673                 error = gfs2_lm_hold_lvb(gl->gl_sbd, gl->gl_lock, &gl->gl_lvb);
1674                 if (error) {
1675                         gfs2_glmutex_unlock(gl);
1676                         return error;
1677                 }
1678                 gfs2_glock_hold(gl);
1679         }
1680         atomic_inc(&gl->gl_lvb_count);
1681
1682         gfs2_glmutex_unlock(gl);
1683
1684         return 0;
1685 }
1686
1687 /**
1688  * gfs2_lvb_unhold - detach a LVB from a glock
1689  * @gl: The glock in question
1690  *
1691  */
1692
1693 void gfs2_lvb_unhold(struct gfs2_glock *gl)
1694 {
1695         gfs2_glock_hold(gl);
1696         gfs2_glmutex_lock(gl);
1697
1698         gfs2_assert(gl->gl_sbd, atomic_read(&gl->gl_lvb_count) > 0);
1699         if (atomic_dec_and_test(&gl->gl_lvb_count)) {
1700                 gfs2_lm_unhold_lvb(gl->gl_sbd, gl->gl_lock, gl->gl_lvb);
1701                 gl->gl_lvb = NULL;
1702                 gfs2_glock_put(gl);
1703         }
1704
1705         gfs2_glmutex_unlock(gl);
1706         gfs2_glock_put(gl);
1707 }
1708
1709 #if 0
1710 void gfs2_lvb_sync(struct gfs2_glock *gl)
1711 {
1712         gfs2_glmutex_lock(gl);
1713
1714         gfs2_assert(gl->gl_sbd, atomic_read(&gl->gl_lvb_count));
1715         if (!gfs2_assert_warn(gl->gl_sbd, gfs2_glock_is_held_excl(gl)))
1716                 gfs2_lm_sync_lvb(gl->gl_sbd, gl->gl_lock, gl->gl_lvb);
1717
1718         gfs2_glmutex_unlock(gl);
1719 }
1720 #endif  /*  0  */
1721
1722 static void blocking_cb(struct gfs2_sbd *sdp, struct lm_lockname *name,
1723                         unsigned int state)
1724 {
1725         struct gfs2_glock *gl;
1726
1727         gl = gfs2_glock_find(sdp, name);
1728         if (!gl)
1729                 return;
1730
1731         if (gl->gl_ops->go_callback)
1732                 gl->gl_ops->go_callback(gl, state);
1733         handle_callback(gl, state);
1734
1735         spin_lock(&gl->gl_spin);
1736         run_queue(gl);
1737         spin_unlock(&gl->gl_spin);
1738
1739         gfs2_glock_put(gl);
1740 }
1741
1742 /**
1743  * gfs2_glock_cb - Callback used by locking module
1744  * @fsdata: Pointer to the superblock
1745  * @type: Type of callback
1746  * @data: Type dependent data pointer
1747  *
1748  * Called by the locking module when it wants to tell us something.
1749  * Either we need to drop a lock, one of our ASYNC requests completed, or
1750  * a journal from another client needs to be recovered.
1751  */
1752
1753 void gfs2_glock_cb(lm_fsdata_t *fsdata, unsigned int type, void *data)
1754 {
1755         struct gfs2_sbd *sdp = (struct gfs2_sbd *)fsdata;
1756
1757         switch (type) {
1758         case LM_CB_NEED_E:
1759                 blocking_cb(sdp, data, LM_ST_UNLOCKED);
1760                 return;
1761
1762         case LM_CB_NEED_D:
1763                 blocking_cb(sdp, data, LM_ST_DEFERRED);
1764                 return;
1765
1766         case LM_CB_NEED_S:
1767                 blocking_cb(sdp, data, LM_ST_SHARED);
1768                 return;
1769
1770         case LM_CB_ASYNC: {
1771                 struct lm_async_cb *async = data;
1772                 struct gfs2_glock *gl;
1773
1774                 gl = gfs2_glock_find(sdp, &async->lc_name);
1775                 if (gfs2_assert_warn(sdp, gl))
1776                         return;
1777                 if (!gfs2_assert_warn(sdp, gl->gl_req_bh))
1778                         gl->gl_req_bh(gl, async->lc_ret);
1779                 gfs2_glock_put(gl);
1780                 return;
1781         }
1782
1783         case LM_CB_NEED_RECOVERY:
1784                 gfs2_jdesc_make_dirty(sdp, *(unsigned int *)data);
1785                 if (sdp->sd_recoverd_process)
1786                         wake_up_process(sdp->sd_recoverd_process);
1787                 return;
1788
1789         case LM_CB_DROPLOCKS:
1790                 gfs2_gl_hash_clear(sdp, NO_WAIT);
1791                 gfs2_quota_scan(sdp);
1792                 return;
1793
1794         default:
1795                 gfs2_assert_warn(sdp, 0);
1796                 return;
1797         }
1798 }
1799
1800 /**
1801  * gfs2_iopen_go_callback - Try to kick the inode/vnode associated with an
1802  *                          iopen glock from memory
1803  * @io_gl: the iopen glock
1804  * @state: the state into which the glock should be put
1805  *
1806  */
1807
1808 void gfs2_iopen_go_callback(struct gfs2_glock *io_gl, unsigned int state)
1809 {
1810
1811         if (state != LM_ST_UNLOCKED)
1812                 return;
1813         /* FIXME: remove this? */
1814 }
1815
1816 /**
1817  * demote_ok - Check to see if it's ok to unlock a glock
1818  * @gl: the glock
1819  *
1820  * Returns: 1 if it's ok
1821  */
1822
1823 static int demote_ok(struct gfs2_glock *gl)
1824 {
1825         struct gfs2_sbd *sdp = gl->gl_sbd;
1826         struct gfs2_glock_operations *glops = gl->gl_ops;
1827         int demote = 1;
1828
1829         if (test_bit(GLF_STICKY, &gl->gl_flags))
1830                 demote = 0;
1831         else if (test_bit(GLF_PREFETCH, &gl->gl_flags))
1832                 demote = time_after_eq(jiffies,
1833                                     gl->gl_stamp +
1834                                     gfs2_tune_get(sdp, gt_prefetch_secs) * HZ);
1835         else if (glops->go_demote_ok)
1836                 demote = glops->go_demote_ok(gl);
1837
1838         return demote;
1839 }
1840
1841 /**
1842  * gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
1843  * @gl: the glock
1844  *
1845  */
1846
1847 void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
1848 {
1849         struct gfs2_sbd *sdp = gl->gl_sbd;
1850
1851         spin_lock(&sdp->sd_reclaim_lock);
1852         if (list_empty(&gl->gl_reclaim)) {
1853                 gfs2_glock_hold(gl);
1854                 list_add(&gl->gl_reclaim, &sdp->sd_reclaim_list);
1855                 atomic_inc(&sdp->sd_reclaim_count);
1856         }
1857         spin_unlock(&sdp->sd_reclaim_lock);
1858
1859         wake_up(&sdp->sd_reclaim_wq);
1860 }
1861
1862 /**
1863  * gfs2_reclaim_glock - process the next glock on the filesystem's reclaim list
1864  * @sdp: the filesystem
1865  *
1866  * Called from gfs2_glockd() glock reclaim daemon, or when promoting a
1867  * different glock and we notice that there are a lot of glocks in the
1868  * reclaim list.
1869  *
1870  */
1871
1872 void gfs2_reclaim_glock(struct gfs2_sbd *sdp)
1873 {
1874         struct gfs2_glock *gl;
1875
1876         spin_lock(&sdp->sd_reclaim_lock);
1877         if (list_empty(&sdp->sd_reclaim_list)) {
1878                 spin_unlock(&sdp->sd_reclaim_lock);
1879                 return;
1880         }
1881         gl = list_entry(sdp->sd_reclaim_list.next,
1882                         struct gfs2_glock, gl_reclaim);
1883         list_del_init(&gl->gl_reclaim);
1884         spin_unlock(&sdp->sd_reclaim_lock);
1885
1886         atomic_dec(&sdp->sd_reclaim_count);
1887         atomic_inc(&sdp->sd_reclaimed);
1888
1889         if (gfs2_glmutex_trylock(gl)) {
1890                 if (queue_empty(gl, &gl->gl_holders) &&
1891                     gl->gl_state != LM_ST_UNLOCKED &&
1892                     demote_ok(gl))
1893                         handle_callback(gl, LM_ST_UNLOCKED);
1894                 gfs2_glmutex_unlock(gl);
1895         }
1896
1897         gfs2_glock_put(gl);
1898 }
1899
1900 /**
1901  * examine_bucket - Call a function for glock in a hash bucket
1902  * @examiner: the function
1903  * @sdp: the filesystem
1904  * @bucket: the bucket
1905  *
1906  * Returns: 1 if the bucket has entries
1907  */
1908
1909 static int examine_bucket(glock_examiner examiner, struct gfs2_sbd *sdp,
1910                           struct gfs2_gl_hash_bucket *bucket)
1911 {
1912         struct glock_plug plug;
1913         struct list_head *tmp;
1914         struct gfs2_glock *gl;
1915         int entries;
1916
1917         /* Add "plug" to end of bucket list, work back up list from there */
1918         memset(&plug.gl_flags, 0, sizeof(unsigned long));
1919         set_bit(GLF_PLUG, &plug.gl_flags);
1920
1921         write_lock(&bucket->hb_lock);
1922         list_add(&plug.gl_list, &bucket->hb_list);
1923         write_unlock(&bucket->hb_lock);
1924
1925         for (;;) {
1926                 write_lock(&bucket->hb_lock);
1927
1928                 for (;;) {
1929                         tmp = plug.gl_list.next;
1930
1931                         if (tmp == &bucket->hb_list) {
1932                                 list_del(&plug.gl_list);
1933                                 entries = !list_empty(&bucket->hb_list);
1934                                 write_unlock(&bucket->hb_lock);
1935                                 return entries;
1936                         }
1937                         gl = list_entry(tmp, struct gfs2_glock, gl_list);
1938
1939                         /* Move plug up list */
1940                         list_move(&plug.gl_list, &gl->gl_list);
1941
1942                         if (test_bit(GLF_PLUG, &gl->gl_flags))
1943                                 continue;
1944
1945                         /* examiner() must glock_put() */
1946                         gfs2_glock_hold(gl);
1947
1948                         break;
1949                 }
1950
1951                 write_unlock(&bucket->hb_lock);
1952
1953                 examiner(gl);
1954         }
1955 }
1956
1957 /**
1958  * scan_glock - look at a glock and see if we can reclaim it
1959  * @gl: the glock to look at
1960  *
1961  */
1962
1963 static void scan_glock(struct gfs2_glock *gl)
1964 {
1965         if (gfs2_glmutex_trylock(gl)) {
1966                 if (gl->gl_ops == &gfs2_inode_glops) {
1967                         struct gfs2_inode *ip = gl->gl_object;
1968                         if (ip)
1969                                 goto out_schedule;
1970                 }
1971                 if (queue_empty(gl, &gl->gl_holders) &&
1972                     gl->gl_state != LM_ST_UNLOCKED &&
1973                     demote_ok(gl))
1974                         goto out_schedule;
1975
1976                 gfs2_glmutex_unlock(gl);
1977         }
1978
1979         gfs2_glock_put(gl);
1980
1981         return;
1982
1983  out_schedule:
1984         gfs2_glmutex_unlock(gl);
1985         gfs2_glock_schedule_for_reclaim(gl);
1986         gfs2_glock_put(gl);
1987 }
1988
1989 /**
1990  * gfs2_scand_internal - Look for glocks and inodes to toss from memory
1991  * @sdp: the filesystem
1992  *
1993  */
1994
1995 void gfs2_scand_internal(struct gfs2_sbd *sdp)
1996 {
1997         unsigned int x;
1998
1999         for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
2000                 examine_bucket(scan_glock, sdp, &sdp->sd_gl_hash[x]);
2001                 cond_resched();
2002         }
2003 }
2004
2005 /**
2006  * clear_glock - look at a glock and see if we can free it from glock cache
2007  * @gl: the glock to look at
2008  *
2009  */
2010
2011 static void clear_glock(struct gfs2_glock *gl)
2012 {
2013         struct gfs2_sbd *sdp = gl->gl_sbd;
2014         int released;
2015
2016         spin_lock(&sdp->sd_reclaim_lock);
2017         if (!list_empty(&gl->gl_reclaim)) {
2018                 list_del_init(&gl->gl_reclaim);
2019                 atomic_dec(&sdp->sd_reclaim_count);
2020                 spin_unlock(&sdp->sd_reclaim_lock);
2021                 released = gfs2_glock_put(gl);
2022                 gfs2_assert(sdp, !released);
2023         } else {
2024                 spin_unlock(&sdp->sd_reclaim_lock);
2025         }
2026
2027         if (gfs2_glmutex_trylock(gl)) {
2028                 if (queue_empty(gl, &gl->gl_holders) &&
2029                     gl->gl_state != LM_ST_UNLOCKED)
2030                         handle_callback(gl, LM_ST_UNLOCKED);
2031
2032                 gfs2_glmutex_unlock(gl);
2033         }
2034
2035         gfs2_glock_put(gl);
2036 }
2037
2038 /**
2039  * gfs2_gl_hash_clear - Empty out the glock hash table
2040  * @sdp: the filesystem
2041  * @wait: wait until it's all gone
2042  *
2043  * Called when unmounting the filesystem, or when inter-node lock manager
2044  * requests DROPLOCKS because it is running out of capacity.
2045  */
2046
2047 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp, int wait)
2048 {
2049         unsigned long t;
2050         unsigned int x;
2051         int cont;
2052
2053         t = jiffies;
2054
2055         for (;;) {
2056                 cont = 0;
2057
2058                 for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
2059                         if (examine_bucket(clear_glock, sdp,
2060                                            &sdp->sd_gl_hash[x]))
2061                                 cont = 1;
2062
2063                 if (!wait || !cont)
2064                         break;
2065
2066                 if (time_after_eq(jiffies,
2067                                   t + gfs2_tune_get(sdp, gt_stall_secs) * HZ)) {
2068                         fs_warn(sdp, "Unmount seems to be stalled. "
2069                                      "Dumping lock state...\n");
2070                         gfs2_dump_lockstate(sdp);
2071                         t = jiffies;
2072                 }
2073
2074                 /* invalidate_inodes() requires that the sb inodes list
2075                    not change, but an async completion callback for an
2076                    unlock can occur which does glock_put() which
2077                    can call iput() which will change the sb inodes list.
2078                    invalidate_inodes_mutex prevents glock_put()'s during
2079                    an invalidate_inodes() */
2080
2081                 mutex_lock(&sdp->sd_invalidate_inodes_mutex);
2082                 invalidate_inodes(sdp->sd_vfs);
2083                 mutex_unlock(&sdp->sd_invalidate_inodes_mutex);
2084                 msleep(10);
2085         }
2086 }
2087
2088 /*
2089  *  Diagnostic routines to help debug distributed deadlock
2090  */
2091
2092 /**
2093  * dump_holder - print information about a glock holder
2094  * @str: a string naming the type of holder
2095  * @gh: the glock holder
2096  *
2097  * Returns: 0 on success, -ENOBUFS when we run out of space
2098  */
2099
2100 static int dump_holder(char *str, struct gfs2_holder *gh)
2101 {
2102         unsigned int x;
2103         int error = -ENOBUFS;
2104
2105         printk(KERN_INFO "  %s\n", str);
2106         printk(KERN_INFO "    owner = %ld\n",
2107                    (gh->gh_owner) ? (long)gh->gh_owner->pid : -1);
2108         printk(KERN_INFO "    gh_state = %u\n", gh->gh_state);
2109         printk(KERN_INFO "    gh_flags =");
2110         for (x = 0; x < 32; x++)
2111                 if (gh->gh_flags & (1 << x))
2112                         printk(" %u", x);
2113         printk(" \n");
2114         printk(KERN_INFO "    error = %d\n", gh->gh_error);
2115         printk(KERN_INFO "    gh_iflags =");
2116         for (x = 0; x < 32; x++)
2117                 if (test_bit(x, &gh->gh_iflags))
2118                         printk(" %u", x);
2119         printk(" \n");
2120         print_symbol(KERN_INFO "    initialized at: %s\n", gh->gh_ip);
2121
2122         error = 0;
2123
2124         return error;
2125 }
2126
2127 /**
2128  * dump_inode - print information about an inode
2129  * @ip: the inode
2130  *
2131  * Returns: 0 on success, -ENOBUFS when we run out of space
2132  */
2133
2134 static int dump_inode(struct gfs2_inode *ip)
2135 {
2136         unsigned int x;
2137         int error = -ENOBUFS;
2138
2139         printk(KERN_INFO "  Inode:\n");
2140         printk(KERN_INFO "    num = %llu %llu\n",
2141                     (unsigned long long)ip->i_num.no_formal_ino,
2142                     (unsigned long long)ip->i_num.no_addr);
2143         printk(KERN_INFO "    type = %u\n", IF2DT(ip->i_di.di_mode));
2144         printk(KERN_INFO "    i_flags =");
2145         for (x = 0; x < 32; x++)
2146                 if (test_bit(x, &ip->i_flags))
2147                         printk(" %u", x);
2148         printk(" \n");
2149
2150         error = 0;
2151
2152         return error;
2153 }
2154
2155 /**
2156  * dump_glock - print information about a glock
2157  * @gl: the glock
2158  * @count: where we are in the buffer
2159  *
2160  * Returns: 0 on success, -ENOBUFS when we run out of space
2161  */
2162
2163 static int dump_glock(struct gfs2_glock *gl)
2164 {
2165         struct gfs2_holder *gh;
2166         unsigned int x;
2167         int error = -ENOBUFS;
2168
2169         spin_lock(&gl->gl_spin);
2170
2171         printk(KERN_INFO "Glock (%u, %llu)\n", gl->gl_name.ln_type,
2172                (unsigned long long)gl->gl_name.ln_number);
2173         printk(KERN_INFO "  gl_flags =");
2174         for (x = 0; x < 32; x++)
2175                 if (test_bit(x, &gl->gl_flags))
2176                         printk(" %u", x);
2177         printk(" \n");
2178         printk(KERN_INFO "  gl_ref = %d\n", atomic_read(&gl->gl_ref.refcount));
2179         printk(KERN_INFO "  gl_state = %u\n", gl->gl_state);
2180         printk(KERN_INFO "  gl_owner = %s\n", gl->gl_owner->comm);
2181         print_symbol(KERN_INFO "  gl_ip = %s\n", gl->gl_ip);
2182         printk(KERN_INFO "  req_gh = %s\n", (gl->gl_req_gh) ? "yes" : "no");
2183         printk(KERN_INFO "  req_bh = %s\n", (gl->gl_req_bh) ? "yes" : "no");
2184         printk(KERN_INFO "  lvb_count = %d\n", atomic_read(&gl->gl_lvb_count));
2185         printk(KERN_INFO "  object = %s\n", (gl->gl_object) ? "yes" : "no");
2186         printk(KERN_INFO "  le = %s\n",
2187                    (list_empty(&gl->gl_le.le_list)) ? "no" : "yes");
2188         printk(KERN_INFO "  reclaim = %s\n",
2189                     (list_empty(&gl->gl_reclaim)) ? "no" : "yes");
2190         if (gl->gl_aspace)
2191                 printk(KERN_INFO "  aspace = %lu\n",
2192                             gl->gl_aspace->i_mapping->nrpages);
2193         else
2194                 printk(KERN_INFO "  aspace = no\n");
2195         printk(KERN_INFO "  ail = %d\n", atomic_read(&gl->gl_ail_count));
2196         if (gl->gl_req_gh) {
2197                 error = dump_holder("Request", gl->gl_req_gh);
2198                 if (error)
2199                         goto out;
2200         }
2201         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
2202                 error = dump_holder("Holder", gh);
2203                 if (error)
2204                         goto out;
2205         }
2206         list_for_each_entry(gh, &gl->gl_waiters1, gh_list) {
2207                 error = dump_holder("Waiter1", gh);
2208                 if (error)
2209                         goto out;
2210         }
2211         list_for_each_entry(gh, &gl->gl_waiters2, gh_list) {
2212                 error = dump_holder("Waiter2", gh);
2213                 if (error)
2214                         goto out;
2215         }
2216         list_for_each_entry(gh, &gl->gl_waiters3, gh_list) {
2217                 error = dump_holder("Waiter3", gh);
2218                 if (error)
2219                         goto out;
2220         }
2221         if (gl->gl_ops == &gfs2_inode_glops && gl->gl_object) {
2222                 if (!test_bit(GLF_LOCK, &gl->gl_flags) &&
2223                     list_empty(&gl->gl_holders)) {
2224                         error = dump_inode(gl->gl_object);
2225                         if (error)
2226                                 goto out;
2227                 } else {
2228                         error = -ENOBUFS;
2229                         printk(KERN_INFO "  Inode: busy\n");
2230                 }
2231         }
2232
2233         error = 0;
2234
2235  out:
2236         spin_unlock(&gl->gl_spin);
2237
2238         return error;
2239 }
2240
2241 /**
2242  * gfs2_dump_lockstate - print out the current lockstate
2243  * @sdp: the filesystem
2244  * @ub: the buffer to copy the information into
2245  *
2246  * If @ub is NULL, dump the lockstate to the console.
2247  *
2248  */
2249
2250 static int gfs2_dump_lockstate(struct gfs2_sbd *sdp)
2251 {
2252         struct gfs2_gl_hash_bucket *bucket;
2253         struct gfs2_glock *gl;
2254         unsigned int x;
2255         int error = 0;
2256
2257         for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
2258                 bucket = &sdp->sd_gl_hash[x];
2259
2260                 read_lock(&bucket->hb_lock);
2261
2262                 list_for_each_entry(gl, &bucket->hb_list, gl_list) {
2263                         if (test_bit(GLF_PLUG, &gl->gl_flags))
2264                                 continue;
2265
2266                         error = dump_glock(gl);
2267                         if (error)
2268                                 break;
2269                 }
2270
2271                 read_unlock(&bucket->hb_lock);
2272
2273                 if (error)
2274                         break;
2275         }
2276
2277
2278         return error;
2279 }
2280