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 version 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/kallsyms.h>
  19 #include <linux/gfs2_ondisk.h>
  20 #include <linux/list.h>
  21 #include <linux/lm_interface.h>
  22 #include <linux/wait.h>
  23 #include <linux/rwsem.h>
  24 #include <asm/uaccess.h>
  25
  26 #include "gfs2.h"
  27 #include "incore.h"
  28 #include "glock.h"
  29 #include "glops.h"
  30 #include "inode.h"
  31 #include "lm.h"
  32 #include "lops.h"
  33 #include "meta_io.h"
  34 #include "quota.h"
  35 #include "super.h"
  36 #include "util.h"
  37
  38 struct gfs2_gl_hash_bucket {
  39         struct hlist_head hb_list;
  40 };
  41
  42 typedef void (*glock_examiner) (struct gfs2_glock * gl);
  43
  44 static int gfs2_dump_lockstate(struct gfs2_sbd *sdp);
  45 static int dump_glock(struct gfs2_glock *gl);
  46 static int dump_inode(struct gfs2_inode *ip);
  47 static void gfs2_glock_xmote_th(struct gfs2_holder *gh);
  48 static void gfs2_glock_drop_th(struct gfs2_glock *gl);
  49 static DECLARE_RWSEM(gfs2_umount_flush_sem);
  50
  51 #define GFS2_GL_HASH_SHIFT      15
  52 #define GFS2_GL_HASH_SIZE       (1 << GFS2_GL_HASH_SHIFT)
  53 #define GFS2_GL_HASH_MASK       (GFS2_GL_HASH_SIZE - 1)
  54
  55 static struct gfs2_gl_hash_bucket gl_hash_table[GFS2_GL_HASH_SIZE];
  56
  57 /*
  58  * Despite what you might think, the numbers below are not arbitrary :-)
  59  * They are taken from the ipv4 routing hash code, which is well tested
  60  * and thus should be nearly optimal. Later on we might tweek the numbers
  61  * but for now this should be fine.
  62  *
  63  * The reason for putting the locks in a separate array from the list heads
  64  * is that we can have fewer locks than list heads and save memory. We use
  65  * the same hash function for both, but with a different hash mask.
  66  */
  67 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) || \
  68         defined(CONFIG_PROVE_LOCKING)
  69
  70 #ifdef CONFIG_LOCKDEP
  71 # define GL_HASH_LOCK_SZ        256
  72 #else
  73 # if NR_CPUS >= 32
  74 #  define GL_HASH_LOCK_SZ       4096
  75 # elif NR_CPUS >= 16
  76 #  define GL_HASH_LOCK_SZ       2048
  77 # elif NR_CPUS >= 8
  78 #  define GL_HASH_LOCK_SZ       1024
  79 # elif NR_CPUS >= 4
  80 #  define GL_HASH_LOCK_SZ       512
  81 # else
  82 #  define GL_HASH_LOCK_SZ       256
  83 # endif
  84 #endif
  85
  86 /* We never want more locks than chains */
  87 #if GFS2_GL_HASH_SIZE < GL_HASH_LOCK_SZ
  88 # undef GL_HASH_LOCK_SZ
  89 # define GL_HASH_LOCK_SZ GFS2_GL_HASH_SIZE
  90 #endif
  91
  92 static rwlock_t gl_hash_locks[GL_HASH_LOCK_SZ];
  93
  94 static inline rwlock_t *gl_lock_addr(unsigned int x)
  95 {
  96         return &gl_hash_locks[x & (GL_HASH_LOCK_SZ-1)];
  97 }
  98 #else /* not SMP, so no spinlocks required */
  99 static inline rwlock_t *gl_lock_addr(unsigned int x)
 100 {
 101         return NULL;
 102 }
 103 #endif
 104
 105 /**
 106  * relaxed_state_ok - is a requested lock compatible with the current lock mode?
 107  * @actual: the current state of the lock
 108  * @requested: the lock state that was requested by the caller
 109  * @flags: the modifier flags passed in by the caller
 110  *
 111  * Returns: 1 if the locks are compatible, 0 otherwise
 112  */
 113
 114 static inline int relaxed_state_ok(unsigned int actual, unsigned requested,
 115                                    int flags)
 116 {
 117         if (actual == requested)
 118                 return 1;
 119
 120         if (flags & GL_EXACT)
 121                 return 0;
 122
 123         if (actual == LM_ST_EXCLUSIVE && requested == LM_ST_SHARED)
 124                 return 1;
 125
 126         if (actual != LM_ST_UNLOCKED && (flags & LM_FLAG_ANY))
 127                 return 1;
 128
 129         return 0;
 130 }
 131
 132 /**
 133  * gl_hash() - Turn glock number into hash bucket number
 134  * @lock: The glock number
 135  *
 136  * Returns: The number of the corresponding hash bucket
 137  */
 138
 139 static unsigned int gl_hash(const struct gfs2_sbd *sdp,
 140                             const struct lm_lockname *name)
 141 {
 142         unsigned int h;
 143
 144         h = jhash(&name->ln_number, sizeof(u64), 0);
 145         h = jhash(&name->ln_type, sizeof(unsigned int), h);
 146         h = jhash(&sdp, sizeof(struct gfs2_sbd *), h);
 147         h &= GFS2_GL_HASH_MASK;
 148
 149         return h;
 150 }
 151
 152 /**
 153  * glock_free() - Perform a few checks and then release struct gfs2_glock
 154  * @gl: The glock to release
 155  *
 156  * Also calls lock module to release its internal structure for this glock.
 157  *
 158  */
 159
 160 static void glock_free(struct gfs2_glock *gl)
 161 {
 162         struct gfs2_sbd *sdp = gl->gl_sbd;
 163         struct inode *aspace = gl->gl_aspace;
 164
 165         gfs2_lm_put_lock(sdp, gl->gl_lock);
 166
 167         if (aspace)
 168                 gfs2_aspace_put(aspace);
 169
 170         kmem_cache_free(gfs2_glock_cachep, gl);
 171 }
 172
 173 /**
 174  * gfs2_glock_hold() - increment reference count on glock
 175  * @gl: The glock to hold
 176  *
 177  */
 178
 179 void gfs2_glock_hold(struct gfs2_glock *gl)
 180 {
 181         atomic_inc(&gl->gl_ref);
 182 }
 183
 184 /**
 185  * gfs2_glock_put() - Decrement reference count on glock
 186  * @gl: The glock to put
 187  *
 188  */
 189
 190 int gfs2_glock_put(struct gfs2_glock *gl)
 191 {
 192         int rv = 0;
 193         struct gfs2_sbd *sdp = gl->gl_sbd;
 194
 195         write_lock(gl_lock_addr(gl->gl_hash));
 196         if (atomic_dec_and_test(&gl->gl_ref)) {
 197                 hlist_del(&gl->gl_list);
 198                 write_unlock(gl_lock_addr(gl->gl_hash));
 199                 BUG_ON(spin_is_locked(&gl->gl_spin));
 200                 gfs2_assert(sdp, gl->gl_state == LM_ST_UNLOCKED);
 201                 gfs2_assert(sdp, list_empty(&gl->gl_reclaim));
 202                 gfs2_assert(sdp, list_empty(&gl->gl_holders));
 203                 gfs2_assert(sdp, list_empty(&gl->gl_waiters1));
 204                 gfs2_assert(sdp, list_empty(&gl->gl_waiters2));
 205                 gfs2_assert(sdp, list_empty(&gl->gl_waiters3));
 206                 glock_free(gl);
 207                 rv = 1;
 208                 goto out;
 209         }
 210         write_unlock(gl_lock_addr(gl->gl_hash));
 211 out:
 212         return rv;
 213 }
 214
 215 /**
 216  * search_bucket() - Find struct gfs2_glock by lock number
 217  * @bucket: the bucket to search
 218  * @name: The lock name
 219  *
 220  * Returns: NULL, or the struct gfs2_glock with the requested number
 221  */
 222
 223 static struct gfs2_glock *search_bucket(unsigned int hash,
 224                                         const struct gfs2_sbd *sdp,
 225                                         const struct lm_lockname *name)
 226 {
 227         struct gfs2_glock *gl;
 228         struct hlist_node *h;
 229
 230         hlist_for_each_entry(gl, h, &gl_hash_table[hash].hb_list, gl_list) {
 231                 if (!lm_name_equal(&gl->gl_name, name))
 232                         continue;
 233                 if (gl->gl_sbd != sdp)
 234                         continue;
 235
 236                 atomic_inc(&gl->gl_ref);
 237
 238                 return gl;
 239         }
 240
 241         return NULL;
 242 }
 243
 244 /**
 245  * gfs2_glock_find() - Find glock by lock number
 246  * @sdp: The GFS2 superblock
 247  * @name: The lock name
 248  *
 249  * Returns: NULL, or the struct gfs2_glock with the requested number
 250  */
 251
 252 static struct gfs2_glock *gfs2_glock_find(const struct gfs2_sbd *sdp,
 253                                           const struct lm_lockname *name)
 254 {
 255         unsigned int hash = gl_hash(sdp, name);
 256         struct gfs2_glock *gl;
 257
 258         read_lock(gl_lock_addr(hash));
 259         gl = search_bucket(hash, sdp, name);
 260         read_unlock(gl_lock_addr(hash));
 261
 262         return gl;
 263 }
 264
 265 /**
 266  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
 267  * @sdp: The GFS2 superblock
 268  * @number: the lock number
 269  * @glops: The glock_operations to use
 270  * @create: If 0, don't create the glock if it doesn't exist
 271  * @glp: the glock is returned here
 272  *
 273  * This does not lock a glock, just finds/creates structures for one.
 274  *
 275  * Returns: errno
 276  */
 277
 278 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 279                    const struct gfs2_glock_operations *glops, int create,
 280                    struct gfs2_glock **glp)
 281 {
 282         struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
 283         struct gfs2_glock *gl, *tmp;
 284         unsigned int hash = gl_hash(sdp, &name);
 285         int error;
 286
 287         read_lock(gl_lock_addr(hash));
 288         gl = search_bucket(hash, sdp, &name);
 289         read_unlock(gl_lock_addr(hash));
 290
 291         if (gl || !create) {
 292                 *glp = gl;
 293                 return 0;
 294         }
 295
 296         gl = kmem_cache_alloc(gfs2_glock_cachep, GFP_KERNEL);
 297         if (!gl)
 298                 return -ENOMEM;
 299
 300         gl->gl_flags = 0;
 301         gl->gl_name = name;
 302         atomic_set(&gl->gl_ref, 1);
 303         gl->gl_state = LM_ST_UNLOCKED;
 304         gl->gl_hash = hash;
 305         gl->gl_owner = NULL;
 306         gl->gl_ip = 0;
 307         gl->gl_ops = glops;
 308         gl->gl_req_gh = NULL;
 309         gl->gl_req_bh = NULL;
 310         gl->gl_vn = 0;
 311         gl->gl_stamp = jiffies;
 312         gl->gl_object = NULL;
 313         gl->gl_sbd = sdp;
 314         gl->gl_aspace = NULL;
 315         lops_init_le(&gl->gl_le, &gfs2_glock_lops);
 316
 317         /* If this glock protects actual on-disk data or metadata blocks,
 318            create a VFS inode to manage the pages/buffers holding them. */
 319         if (glops == &gfs2_inode_glops || glops == &gfs2_rgrp_glops) {
 320                 gl->gl_aspace = gfs2_aspace_get(sdp);
 321                 if (!gl->gl_aspace) {
 322                         error = -ENOMEM;
 323                         goto fail;
 324                 }
 325         }
 326
 327         error = gfs2_lm_get_lock(sdp, &name, &gl->gl_lock);
 328         if (error)
 329                 goto fail_aspace;
 330
 331         write_lock(gl_lock_addr(hash));
 332         tmp = search_bucket(hash, sdp, &name);
 333         if (tmp) {
 334                 write_unlock(gl_lock_addr(hash));
 335                 glock_free(gl);
 336                 gl = tmp;
 337         } else {
 338                 hlist_add_head(&gl->gl_list, &gl_hash_table[hash].hb_list);
 339                 write_unlock(gl_lock_addr(hash));
 340         }
 341
 342         *glp = gl;
 343
 344         return 0;
 345
 346 fail_aspace:
 347         if (gl->gl_aspace)
 348                 gfs2_aspace_put(gl->gl_aspace);
 349 fail:
 350         kmem_cache_free(gfs2_glock_cachep, gl);
 351         return error;
 352 }
 353
 354 /**
 355  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
 356  * @gl: the glock
 357  * @state: the state we're requesting
 358  * @flags: the modifier flags
 359  * @gh: the holder structure
 360  *
 361  */
 362
 363 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
 364                       struct gfs2_holder *gh)
 365 {
 366         INIT_LIST_HEAD(&gh->gh_list);
 367         gh->gh_gl = gl;
 368         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 369         gh->gh_owner = current;
 370         gh->gh_state = state;
 371         gh->gh_flags = flags;
 372         gh->gh_error = 0;
 373         gh->gh_iflags = 0;
 374         gfs2_glock_hold(gl);
 375 }
 376
 377 /**
 378  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
 379  * @state: the state we're requesting
 380  * @flags: the modifier flags
 381  * @gh: the holder structure
 382  *
 383  * Don't mess with the glock.
 384  *
 385  */
 386
 387 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
 388 {
 389         gh->gh_state = state;
 390         gh->gh_flags = flags;
 391         gh->gh_iflags &= 1 << HIF_ALLOCED;
 392         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 393 }
 394
 395 /**
 396  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 397  * @gh: the holder structure
 398  *
 399  */
 400
 401 void gfs2_holder_uninit(struct gfs2_holder *gh)
 402 {
 403         gfs2_glock_put(gh->gh_gl);
 404         gh->gh_gl = NULL;
 405         gh->gh_ip = 0;
 406 }
 407
 408 /**
 409  * gfs2_holder_get - get a struct gfs2_holder structure
 410  * @gl: the glock
 411  * @state: the state we're requesting
 412  * @flags: the modifier flags
 413  * @gfp_flags:
 414  *
 415  * Figure out how big an impact this function has.  Either:
 416  * 1) Replace it with a cache of structures hanging off the struct gfs2_sbd
 417  * 2) Leave it like it is
 418  *
 419  * Returns: the holder structure, NULL on ENOMEM
 420  */
 421
 422 static struct gfs2_holder *gfs2_holder_get(struct gfs2_glock *gl,
 423                                            unsigned int state,
 424                                            int flags, gfp_t gfp_flags)
 425 {
 426         struct gfs2_holder *gh;
 427
 428         gh = kmalloc(sizeof(struct gfs2_holder), gfp_flags);
 429         if (!gh)
 430                 return NULL;
 431
 432         gfs2_holder_init(gl, state, flags, gh);
 433         set_bit(HIF_ALLOCED, &gh->gh_iflags);
 434         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 435         return gh;
 436 }
 437
 438 /**
 439  * gfs2_holder_put - get rid of a struct gfs2_holder structure
 440  * @gh: the holder structure
 441  *
 442  */
 443
 444 static void gfs2_holder_put(struct gfs2_holder *gh)
 445 {
 446         gfs2_holder_uninit(gh);
 447         kfree(gh);
 448 }
 449
 450 static void gfs2_holder_dispose_or_wake(struct gfs2_holder *gh)
 451 {
 452         if (test_bit(HIF_DEALLOC, &gh->gh_iflags)) {
 453                 gfs2_holder_put(gh);
 454                 return;
 455         }
 456         clear_bit(HIF_WAIT, &gh->gh_iflags);
 457         smp_mb();
 458         wake_up_bit(&gh->gh_iflags, HIF_WAIT);
 459 }
 460
 461 static int holder_wait(void *word)
 462 {
 463         schedule();
 464         return 0;
 465 }
 466
 467 static void wait_on_holder(struct gfs2_holder *gh)
 468 {
 469         might_sleep();
 470         wait_on_bit(&gh->gh_iflags, HIF_WAIT, holder_wait, TASK_UNINTERRUPTIBLE);
 471 }
 472
 473 /**
 474  * rq_mutex - process a mutex request in the queue
 475  * @gh: the glock holder
 476  *
 477  * Returns: 1 if the queue is blocked
 478  */
 479
 480 static int rq_mutex(struct gfs2_holder *gh)
 481 {
 482         struct gfs2_glock *gl = gh->gh_gl;
 483
 484         list_del_init(&gh->gh_list);
 485         /*  gh->gh_error never examined.  */
 486         set_bit(GLF_LOCK, &gl->gl_flags);
 487         clear_bit(HIF_WAIT, &gh->gh_iflags);
 488         smp_mb();
 489         wake_up_bit(&gh->gh_iflags, HIF_WAIT);
 490
 491         return 1;
 492 }
 493
 494 /**
 495  * rq_promote - process a promote request in the queue
 496  * @gh: the glock holder
 497  *
 498  * Acquire a new inter-node lock, or change a lock state to more restrictive.
 499  *
 500  * Returns: 1 if the queue is blocked
 501  */
 502
 503 static int rq_promote(struct gfs2_holder *gh)
 504 {
 505         struct gfs2_glock *gl = gh->gh_gl;
 506         struct gfs2_sbd *sdp = gl->gl_sbd;
 507
 508         if (!relaxed_state_ok(gl->gl_state, gh->gh_state, gh->gh_flags)) {
 509                 if (list_empty(&gl->gl_holders)) {
 510                         gl->gl_req_gh = gh;
 511                         set_bit(GLF_LOCK, &gl->gl_flags);
 512                         spin_unlock(&gl->gl_spin);
 513
 514                         if (atomic_read(&sdp->sd_reclaim_count) >
 515                             gfs2_tune_get(sdp, gt_reclaim_limit) &&
 516                             !(gh->gh_flags & LM_FLAG_PRIORITY)) {
 517                                 gfs2_reclaim_glock(sdp);
 518                                 gfs2_reclaim_glock(sdp);
 519                         }
 520
 521                         gfs2_glock_xmote_th(gh);
 522                         spin_lock(&gl->gl_spin);
 523                 }
 524                 return 1;
 525         }
 526
 527         if (list_empty(&gl->gl_holders)) {
 528                 set_bit(HIF_FIRST, &gh->gh_iflags);
 529                 set_bit(GLF_LOCK, &gl->gl_flags);
 530         } else {
 531                 struct gfs2_holder *next_gh;
 532                 if (gh->gh_state == LM_ST_EXCLUSIVE)
 533                         return 1;
 534                 next_gh = list_entry(gl->gl_holders.next, struct gfs2_holder,
 535                                      gh_list);
 536                 if (next_gh->gh_state == LM_ST_EXCLUSIVE)
 537                          return 1;
 538         }
 539
 540         list_move_tail(&gh->gh_list, &gl->gl_holders);
 541         gh->gh_error = 0;
 542         set_bit(HIF_HOLDER, &gh->gh_iflags);
 543
 544         gfs2_holder_dispose_or_wake(gh);
 545
 546         return 0;
 547 }
 548
 549 /**
 550  * rq_demote - process a demote request in the queue
 551  * @gh: the glock holder
 552  *
 553  * Returns: 1 if the queue is blocked
 554  */
 555
 556 static int rq_demote(struct gfs2_holder *gh)
 557 {
 558         struct gfs2_glock *gl = gh->gh_gl;
 559
 560         if (!list_empty(&gl->gl_holders))
 561                 return 1;
 562
 563         if (gl->gl_state == gh->gh_state || gl->gl_state == LM_ST_UNLOCKED) {
 564                 list_del_init(&gh->gh_list);
 565                 gh->gh_error = 0;
 566                 spin_unlock(&gl->gl_spin);
 567                 gfs2_holder_dispose_or_wake(gh);
 568                 spin_lock(&gl->gl_spin);
 569         } else {
 570                 gl->gl_req_gh = gh;
 571                 set_bit(GLF_LOCK, &gl->gl_flags);
 572                 spin_unlock(&gl->gl_spin);
 573
 574                 if (gh->gh_state == LM_ST_UNLOCKED ||
 575                     gl->gl_state != LM_ST_EXCLUSIVE)
 576                         gfs2_glock_drop_th(gl);
 577                 else
 578                         gfs2_glock_xmote_th(gh);
 579
 580                 spin_lock(&gl->gl_spin);
 581         }
 582
 583         return 0;
 584 }
 585
 586 /**
 587  * run_queue - process holder structures on a glock
 588  * @gl: the glock
 589  *
 590  */
 591 static void run_queue(struct gfs2_glock *gl)
 592 {
 593         struct gfs2_holder *gh;
 594         int blocked = 1;
 595
 596         for (;;) {
 597                 if (test_bit(GLF_LOCK, &gl->gl_flags))
 598                         break;
 599
 600                 if (!list_empty(&gl->gl_waiters1)) {
 601                         gh = list_entry(gl->gl_waiters1.next,
 602                                         struct gfs2_holder, gh_list);
 603
 604                         if (test_bit(HIF_MUTEX, &gh->gh_iflags))
 605                                 blocked = rq_mutex(gh);
 606                         else
 607                                 gfs2_assert_warn(gl->gl_sbd, 0);
 608
 609                 } else if (!list_empty(&gl->gl_waiters2) &&
 610                            !test_bit(GLF_SKIP_WAITERS2, &gl->gl_flags)) {
 611                         gh = list_entry(gl->gl_waiters2.next,
 612                                         struct gfs2_holder, gh_list);
 613
 614                         if (test_bit(HIF_DEMOTE, &gh->gh_iflags))
 615                                 blocked = rq_demote(gh);
 616                         else
 617                                 gfs2_assert_warn(gl->gl_sbd, 0);
 618
 619                 } else if (!list_empty(&gl->gl_waiters3)) {
 620                         gh = list_entry(gl->gl_waiters3.next,
 621                                         struct gfs2_holder, gh_list);
 622
 623                         if (test_bit(HIF_PROMOTE, &gh->gh_iflags))
 624                                 blocked = rq_promote(gh);
 625                         else
 626                                 gfs2_assert_warn(gl->gl_sbd, 0);
 627
 628                 } else
 629                         break;
 630
 631                 if (blocked)
 632                         break;
 633         }
 634 }
 635
 636 /**
 637  * gfs2_glmutex_lock - acquire a local lock on a glock
 638  * @gl: the glock
 639  *
 640  * Gives caller exclusive access to manipulate a glock structure.
 641  */
 642
 643 static void gfs2_glmutex_lock(struct gfs2_glock *gl)
 644 {
 645         struct gfs2_holder gh;
 646
 647         gfs2_holder_init(gl, 0, 0, &gh);
 648         set_bit(HIF_MUTEX, &gh.gh_iflags);
 649         if (test_and_set_bit(HIF_WAIT, &gh.gh_iflags))
 650                 BUG();
 651
 652         spin_lock(&gl->gl_spin);
 653         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
 654                 list_add_tail(&gh.gh_list, &gl->gl_waiters1);
 655         } else {
 656                 gl->gl_owner = current;
 657                 gl->gl_ip = (unsigned long)__builtin_return_address(0);
 658                 clear_bit(HIF_WAIT, &gh.gh_iflags);
 659                 smp_mb();
 660                 wake_up_bit(&gh.gh_iflags, HIF_WAIT);
 661         }
 662         spin_unlock(&gl->gl_spin);
 663
 664         wait_on_holder(&gh);
 665         gfs2_holder_uninit(&gh);
 666 }
 667
 668 /**
 669  * gfs2_glmutex_trylock - try to acquire a local lock on a glock
 670  * @gl: the glock
 671  *
 672  * Returns: 1 if the glock is acquired
 673  */
 674
 675 static int gfs2_glmutex_trylock(struct gfs2_glock *gl)
 676 {
 677         int acquired = 1;
 678
 679         spin_lock(&gl->gl_spin);
 680         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
 681                 acquired = 0;
 682         } else {
 683                 gl->gl_owner = current;
 684                 gl->gl_ip = (unsigned long)__builtin_return_address(0);
 685         }
 686         spin_unlock(&gl->gl_spin);
 687
 688         return acquired;
 689 }
 690
 691 /**
 692  * gfs2_glmutex_unlock - release a local lock on a glock
 693  * @gl: the glock
 694  *
 695  */
 696
 697 static void gfs2_glmutex_unlock(struct gfs2_glock *gl)
 698 {
 699         spin_lock(&gl->gl_spin);
 700         clear_bit(GLF_LOCK, &gl->gl_flags);
 701         gl->gl_owner = NULL;
 702         gl->gl_ip = 0;
 703         run_queue(gl);
 704         BUG_ON(!spin_is_locked(&gl->gl_spin));
 705         spin_unlock(&gl->gl_spin);
 706 }
 707
 708 /**
 709  * handle_callback - add a demote request to a lock's queue
 710  * @gl: the glock
 711  * @state: the state the caller wants us to change to
 712  *
 713  * Note: This may fail sliently if we are out of memory.
 714  */
 715
 716 static void handle_callback(struct gfs2_glock *gl, unsigned int state)
 717 {
 718         struct gfs2_holder *gh, *new_gh = NULL;
 719
 720 restart:
 721         spin_lock(&gl->gl_spin);
 722
 723         list_for_each_entry(gh, &gl->gl_waiters2, gh_list) {
 724                 if (test_bit(HIF_DEMOTE, &gh->gh_iflags) &&
 725                     gl->gl_req_gh != gh) {
 726                         if (gh->gh_state != state)
 727                                 gh->gh_state = LM_ST_UNLOCKED;
 728                         goto out;
 729                 }
 730         }
 731
 732         if (new_gh) {
 733                 list_add_tail(&new_gh->gh_list, &gl->gl_waiters2);
 734                 new_gh = NULL;
 735         } else {
 736                 spin_unlock(&gl->gl_spin);
 737
 738                 new_gh = gfs2_holder_get(gl, state, LM_FLAG_TRY, GFP_NOFS);
 739                 if (!new_gh)
 740                         return;
 741                 set_bit(HIF_DEMOTE, &new_gh->gh_iflags);
 742                 set_bit(HIF_DEALLOC, &new_gh->gh_iflags);
 743                 set_bit(HIF_WAIT, &new_gh->gh_iflags);
 744
 745                 goto restart;
 746         }
 747
 748 out:
 749         spin_unlock(&gl->gl_spin);
 750
 751         if (new_gh)
 752                 gfs2_holder_put(new_gh);
 753 }
 754
 755 /**
 756  * state_change - record that the glock is now in a different state
 757  * @gl: the glock
 758  * @new_state the new state
 759  *
 760  */
 761
 762 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 763 {
 764         int held1, held2;
 765
 766         held1 = (gl->gl_state != LM_ST_UNLOCKED);
 767         held2 = (new_state != LM_ST_UNLOCKED);
 768
 769         if (held1 != held2) {
 770                 if (held2)
 771                         gfs2_glock_hold(gl);
 772                 else
 773                         gfs2_glock_put(gl);
 774         }
 775
 776         gl->gl_state = new_state;
 777 }
 778
 779 /**
 780  * xmote_bh - Called after the lock module is done acquiring a lock
 781  * @gl: The glock in question
 782  * @ret: the int returned from the lock module
 783  *
 784  */
 785
 786 static void xmote_bh(struct gfs2_glock *gl, unsigned int ret)
 787 {
 788         struct gfs2_sbd *sdp = gl->gl_sbd;
 789         const struct gfs2_glock_operations *glops = gl->gl_ops;
 790         struct gfs2_holder *gh = gl->gl_req_gh;
 791         int prev_state = gl->gl_state;
 792         int op_done = 1;
 793
 794         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
 795         gfs2_assert_warn(sdp, list_empty(&gl->gl_holders));
 796         gfs2_assert_warn(sdp, !(ret & LM_OUT_ASYNC));
 797
 798         state_change(gl, ret & LM_OUT_ST_MASK);
 799
 800         if (prev_state != LM_ST_UNLOCKED && !(ret & LM_OUT_CACHEABLE)) {
 801                 if (glops->go_inval)
 802                         glops->go_inval(gl, DIO_METADATA);
 803         } else if (gl->gl_state == LM_ST_DEFERRED) {
 804                 /* We might not want to do this here.
 805                    Look at moving to the inode glops. */
 806                 if (glops->go_inval)
 807                         glops->go_inval(gl, 0);
 808         }
 809
 810         /*  Deal with each possible exit condition  */
 811
 812         if (!gh)
 813                 gl->gl_stamp = jiffies;
 814         else if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
 815                 spin_lock(&gl->gl_spin);
 816                 list_del_init(&gh->gh_list);
 817                 gh->gh_error = -EIO;
 818                 spin_unlock(&gl->gl_spin);
 819         } else if (test_bit(HIF_DEMOTE, &gh->gh_iflags)) {
 820                 spin_lock(&gl->gl_spin);
 821                 list_del_init(&gh->gh_list);
 822                 if (gl->gl_state == gh->gh_state ||
 823                     gl->gl_state == LM_ST_UNLOCKED) {
 824                         gh->gh_error = 0;
 825                 } else {
 826                         if (gfs2_assert_warn(sdp, gh->gh_flags &
 827                                         (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) == -1)
 828                                 fs_warn(sdp, "ret = 0x%.8X\n", ret);
 829                         gh->gh_error = GLR_TRYFAILED;
 830                 }
 831                 spin_unlock(&gl->gl_spin);
 832
 833                 if (ret & LM_OUT_CANCELED)
 834                         handle_callback(gl, LM_ST_UNLOCKED);
 835
 836         } else if (ret & LM_OUT_CANCELED) {
 837                 spin_lock(&gl->gl_spin);
 838                 list_del_init(&gh->gh_list);
 839                 gh->gh_error = GLR_CANCELED;
 840                 spin_unlock(&gl->gl_spin);
 841
 842         } else if (relaxed_state_ok(gl->gl_state, gh->gh_state, gh->gh_flags)) {
 843                 spin_lock(&gl->gl_spin);
 844                 list_move_tail(&gh->gh_list, &gl->gl_holders);
 845                 gh->gh_error = 0;
 846                 set_bit(HIF_HOLDER, &gh->gh_iflags);
 847                 spin_unlock(&gl->gl_spin);
 848
 849                 set_bit(HIF_FIRST, &gh->gh_iflags);
 850
 851                 op_done = 0;
 852
 853         } else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
 854                 spin_lock(&gl->gl_spin);
 855                 list_del_init(&gh->gh_list);
 856                 gh->gh_error = GLR_TRYFAILED;
 857                 spin_unlock(&gl->gl_spin);
 858
 859         } else {
 860                 if (gfs2_assert_withdraw(sdp, 0) == -1)
 861                         fs_err(sdp, "ret = 0x%.8X\n", ret);
 862         }
 863
 864         if (glops->go_xmote_bh)
 865                 glops->go_xmote_bh(gl);
 866
 867         if (op_done) {
 868                 spin_lock(&gl->gl_spin);
 869                 gl->gl_req_gh = NULL;
 870                 gl->gl_req_bh = NULL;
 871                 clear_bit(GLF_LOCK, &gl->gl_flags);
 872                 run_queue(gl);
 873                 spin_unlock(&gl->gl_spin);
 874         }
 875
 876         gfs2_glock_put(gl);
 877
 878         if (gh)
 879                 gfs2_holder_dispose_or_wake(gh);
 880 }
 881
 882 /**
 883  * gfs2_glock_xmote_th - Call into the lock module to acquire or change a glock
 884  * @gl: The glock in question
 885  * @state: the requested state
 886  * @flags: modifier flags to the lock call
 887  *
 888  */
 889
 890 void gfs2_glock_xmote_th(struct gfs2_holder *gh)
 891 {
 892         struct gfs2_glock *gl = gh->gh_gl;
 893         struct gfs2_sbd *sdp = gl->gl_sbd;
 894         int flags = gh->gh_flags;
 895         unsigned state = gh->gh_state;
 896         const struct gfs2_glock_operations *glops = gl->gl_ops;
 897         int lck_flags = flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB |
 898                                  LM_FLAG_NOEXP | LM_FLAG_ANY |
 899                                  LM_FLAG_PRIORITY);
 900         unsigned int lck_ret;
 901
 902         if (glops->go_xmote_th)
 903                 glops->go_xmote_th(gl);
 904
 905         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
 906         gfs2_assert_warn(sdp, list_empty(&gl->gl_holders));
 907         gfs2_assert_warn(sdp, state != LM_ST_UNLOCKED);
 908         gfs2_assert_warn(sdp, state != gl->gl_state);
 909
 910         gfs2_glock_hold(gl);
 911         gl->gl_req_bh = xmote_bh;
 912
 913         lck_ret = gfs2_lm_lock(sdp, gl->gl_lock, gl->gl_state, state, lck_flags);
 914
 915         if (gfs2_assert_withdraw(sdp, !(lck_ret & LM_OUT_ERROR)))
 916                 return;
 917
 918         if (lck_ret & LM_OUT_ASYNC)
 919                 gfs2_assert_warn(sdp, lck_ret == LM_OUT_ASYNC);
 920         else
 921                 xmote_bh(gl, lck_ret);
 922 }
 923
 924 /**
 925  * drop_bh - Called after a lock module unlock completes
 926  * @gl: the glock
 927  * @ret: the return status
 928  *
 929  * Doesn't wake up the process waiting on the struct gfs2_holder (if any)
 930  * Doesn't drop the reference on the glock the top half took out
 931  *
 932  */
 933
 934 static void drop_bh(struct gfs2_glock *gl, unsigned int ret)
 935 {
 936         struct gfs2_sbd *sdp = gl->gl_sbd;
 937         const struct gfs2_glock_operations *glops = gl->gl_ops;
 938         struct gfs2_holder *gh = gl->gl_req_gh;
 939
 940         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
 941         gfs2_assert_warn(sdp, list_empty(&gl->gl_holders));
 942         gfs2_assert_warn(sdp, !ret);
 943
 944         state_change(gl, LM_ST_UNLOCKED);
 945
 946         if (glops->go_inval)
 947                 glops->go_inval(gl, DIO_METADATA);
 948
 949         if (gh) {
 950                 spin_lock(&gl->gl_spin);
 951                 list_del_init(&gh->gh_list);
 952                 gh->gh_error = 0;
 953                 spin_unlock(&gl->gl_spin);
 954         }
 955
 956         if (glops->go_drop_bh)
 957                 glops->go_drop_bh(gl);
 958
 959         spin_lock(&gl->gl_spin);
 960         gl->gl_req_gh = NULL;
 961         gl->gl_req_bh = NULL;
 962         clear_bit(GLF_LOCK, &gl->gl_flags);
 963         run_queue(gl);
 964         spin_unlock(&gl->gl_spin);
 965
 966         gfs2_glock_put(gl);
 967
 968         if (gh)
 969                 gfs2_holder_dispose_or_wake(gh);
 970 }
 971
 972 /**
 973  * gfs2_glock_drop_th - call into the lock module to unlock a lock
 974  * @gl: the glock
 975  *
 976  */
 977
 978 static void gfs2_glock_drop_th(struct gfs2_glock *gl)
 979 {
 980         struct gfs2_sbd *sdp = gl->gl_sbd;
 981         const struct gfs2_glock_operations *glops = gl->gl_ops;
 982         unsigned int ret;
 983
 984         if (glops->go_drop_th)
 985                 glops->go_drop_th(gl);
 986
 987         gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
 988         gfs2_assert_warn(sdp, list_empty(&gl->gl_holders));
 989         gfs2_assert_warn(sdp, gl->gl_state != LM_ST_UNLOCKED);
 990
 991         gfs2_glock_hold(gl);
 992         gl->gl_req_bh = drop_bh;
 993
 994         ret = gfs2_lm_unlock(sdp, gl->gl_lock, gl->gl_state);
 995
 996         if (gfs2_assert_withdraw(sdp, !(ret & LM_OUT_ERROR)))
 997                 return;
 998
 999         if (!ret)
1000                 drop_bh(gl, ret);
1001         else
1002                 gfs2_assert_warn(sdp, ret == LM_OUT_ASYNC);
1003 }
1004
1005 /**
1006  * do_cancels - cancel requests for locks stuck waiting on an expire flag
1007  * @gh: the LM_FLAG_PRIORITY holder waiting to acquire the lock
1008  *
1009  * Don't cancel GL_NOCANCEL requests.
1010  */
1011
1012 static void do_cancels(struct gfs2_holder *gh)
1013 {
1014         struct gfs2_glock *gl = gh->gh_gl;
1015
1016         spin_lock(&gl->gl_spin);
1017
1018         while (gl->gl_req_gh != gh &&
1019                !test_bit(HIF_HOLDER, &gh->gh_iflags) &&
1020                !list_empty(&gh->gh_list)) {
1021                 if (gl->gl_req_bh && !(gl->gl_req_gh &&
1022                                      (gl->gl_req_gh->gh_flags & GL_NOCANCEL))) {
1023                         spin_unlock(&gl->gl_spin);
1024                         gfs2_lm_cancel(gl->gl_sbd, gl->gl_lock);
1025                         msleep(100);
1026                         spin_lock(&gl->gl_spin);
1027                 } else {
1028                         spin_unlock(&gl->gl_spin);
1029                         msleep(100);
1030                         spin_lock(&gl->gl_spin);
1031                 }
1032         }
1033
1034         spin_unlock(&gl->gl_spin);
1035 }
1036
1037 /**
1038  * glock_wait_internal - wait on a glock acquisition
1039  * @gh: the glock holder
1040  *
1041  * Returns: 0 on success
1042  */
1043
1044 static int glock_wait_internal(struct gfs2_holder *gh)
1045 {
1046         struct gfs2_glock *gl = gh->gh_gl;
1047         struct gfs2_sbd *sdp = gl->gl_sbd;
1048         const struct gfs2_glock_operations *glops = gl->gl_ops;
1049
1050         if (test_bit(HIF_ABORTED, &gh->gh_iflags))
1051                 return -EIO;
1052
1053         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
1054                 spin_lock(&gl->gl_spin);
1055                 if (gl->gl_req_gh != gh &&
1056                     !test_bit(HIF_HOLDER, &gh->gh_iflags) &&
1057                     !list_empty(&gh->gh_list)) {
1058                         list_del_init(&gh->gh_list);
1059                         gh->gh_error = GLR_TRYFAILED;
1060                         run_queue(gl);
1061                         spin_unlock(&gl->gl_spin);
1062                         return gh->gh_error;
1063                 }
1064                 spin_unlock(&gl->gl_spin);
1065         }
1066
1067         if (gh->gh_flags & LM_FLAG_PRIORITY)
1068                 do_cancels(gh);
1069
1070         wait_on_holder(gh);
1071         if (gh->gh_error)
1072                 return gh->gh_error;
1073
1074         gfs2_assert_withdraw(sdp, test_bit(HIF_HOLDER, &gh->gh_iflags));
1075         gfs2_assert_withdraw(sdp, relaxed_state_ok(gl->gl_state, gh->gh_state,
1076                                                    gh->gh_flags));
1077
1078         if (test_bit(HIF_FIRST, &gh->gh_iflags)) {
1079                 gfs2_assert_warn(sdp, test_bit(GLF_LOCK, &gl->gl_flags));
1080
1081                 if (glops->go_lock) {
1082                         gh->gh_error = glops->go_lock(gh);
1083                         if (gh->gh_error) {
1084                                 spin_lock(&gl->gl_spin);
1085                                 list_del_init(&gh->gh_list);
1086                                 spin_unlock(&gl->gl_spin);
1087                         }
1088                 }
1089
1090                 spin_lock(&gl->gl_spin);
1091                 gl->gl_req_gh = NULL;
1092                 gl->gl_req_bh = NULL;
1093                 clear_bit(GLF_LOCK, &gl->gl_flags);
1094                 run_queue(gl);
1095                 spin_unlock(&gl->gl_spin);
1096         }
1097
1098         return gh->gh_error;
1099 }
1100
1101 static inline struct gfs2_holder *
1102 find_holder_by_owner(struct list_head *head, struct task_struct *owner)
1103 {
1104         struct gfs2_holder *gh;
1105
1106         list_for_each_entry(gh, head, gh_list) {
1107                 if (gh->gh_owner == owner)
1108                         return gh;
1109         }
1110
1111         return NULL;
1112 }
1113
1114 /**
1115  * add_to_queue - Add a holder to the wait queue (but look for recursion)
1116  * @gh: the holder structure to add
1117  *
1118  */
1119
1120 static void add_to_queue(struct gfs2_holder *gh)
1121 {
1122         struct gfs2_glock *gl = gh->gh_gl;
1123         struct gfs2_holder *existing;
1124
1125         BUG_ON(!gh->gh_owner);
1126         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
1127                 BUG();
1128
1129         existing = find_holder_by_owner(&gl->gl_holders, gh->gh_owner);
1130         if (existing) {
1131                 print_symbol(KERN_WARNING "original: %s\n", existing->gh_ip);
1132                 printk(KERN_INFO "pid : %d\n", existing->gh_owner->pid);
1133                 printk(KERN_INFO "lock type : %d lock state : %d\n",
1134                                 existing->gh_gl->gl_name.ln_type, existing->gh_gl->gl_state);
1135                 print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
1136                 printk(KERN_INFO "pid : %d\n", gh->gh_owner->pid);
1137                 printk(KERN_INFO "lock type : %d lock state : %d\n",
1138                                 gl->gl_name.ln_type, gl->gl_state);
1139                 BUG();
1140         }
1141
1142         existing = find_holder_by_owner(&gl->gl_waiters3, gh->gh_owner);
1143         if (existing) {
1144                 print_symbol(KERN_WARNING "original: %s\n", existing->gh_ip);
1145                 print_symbol(KERN_WARNING "new: %s\n", gh->gh_ip);
1146                 BUG();
1147         }
1148
1149         if (gh->gh_flags & LM_FLAG_PRIORITY)
1150                 list_add(&gh->gh_list, &gl->gl_waiters3);
1151         else
1152                 list_add_tail(&gh->gh_list, &gl->gl_waiters3);
1153 }
1154
1155 /**
1156  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1157  * @gh: the holder structure
1158  *
1159  * if (gh->gh_flags & GL_ASYNC), this never returns an error
1160  *
1161  * Returns: 0, GLR_TRYFAILED, or errno on failure
1162  */
1163
1164 int gfs2_glock_nq(struct gfs2_holder *gh)
1165 {
1166         struct gfs2_glock *gl = gh->gh_gl;
1167         struct gfs2_sbd *sdp = gl->gl_sbd;
1168         int error = 0;
1169
1170 restart:
1171         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags))) {
1172                 set_bit(HIF_ABORTED, &gh->gh_iflags);
1173                 return -EIO;
1174         }
1175
1176         set_bit(HIF_PROMOTE, &gh->gh_iflags);
1177
1178         spin_lock(&gl->gl_spin);
1179         add_to_queue(gh);
1180         run_queue(gl);
1181         spin_unlock(&gl->gl_spin);
1182
1183         if (!(gh->gh_flags & GL_ASYNC)) {
1184                 error = glock_wait_internal(gh);
1185                 if (error == GLR_CANCELED) {
1186                         msleep(100);
1187                         goto restart;
1188                 }
1189         }
1190
1191         return error;
1192 }
1193
1194 /**
1195  * gfs2_glock_poll - poll to see if an async request has been completed
1196  * @gh: the holder
1197  *
1198  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1199  */
1200
1201 int gfs2_glock_poll(struct gfs2_holder *gh)
1202 {
1203         struct gfs2_glock *gl = gh->gh_gl;
1204         int ready = 0;
1205
1206         spin_lock(&gl->gl_spin);
1207
1208         if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1209                 ready = 1;
1210         else if (list_empty(&gh->gh_list)) {
1211                 if (gh->gh_error == GLR_CANCELED) {
1212                         spin_unlock(&gl->gl_spin);
1213                         msleep(100);
1214                         if (gfs2_glock_nq(gh))
1215                                 return 1;
1216                         return 0;
1217                 } else
1218                         ready = 1;
1219         }
1220
1221         spin_unlock(&gl->gl_spin);
1222
1223         return ready;
1224 }
1225
1226 /**
1227  * gfs2_glock_wait - wait for a lock acquisition that ended in a GLR_ASYNC
1228  * @gh: the holder structure
1229  *
1230  * Returns: 0, GLR_TRYFAILED, or errno on failure
1231  */
1232
1233 int gfs2_glock_wait(struct gfs2_holder *gh)
1234 {
1235         int error;
1236
1237         error = glock_wait_internal(gh);
1238         if (error == GLR_CANCELED) {
1239                 msleep(100);
1240                 gh->gh_flags &= ~GL_ASYNC;
1241                 error = gfs2_glock_nq(gh);
1242         }
1243
1244         return error;
1245 }
1246
1247 /**
1248  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1249  * @gh: the glock holder
1250  *
1251  */
1252
1253 void gfs2_glock_dq(struct gfs2_holder *gh)
1254 {
1255         struct gfs2_glock *gl = gh->gh_gl;
1256         const struct gfs2_glock_operations *glops = gl->gl_ops;
1257
1258         if (gh->gh_flags & GL_NOCACHE)
1259                 handle_callback(gl, LM_ST_UNLOCKED);
1260
1261         gfs2_glmutex_lock(gl);
1262
1263         spin_lock(&gl->gl_spin);
1264         list_del_init(&gh->gh_list);
1265
1266         if (list_empty(&gl->gl_holders)) {
1267                 spin_unlock(&gl->gl_spin);
1268
1269                 if (glops->go_unlock)
1270                         glops->go_unlock(gh);
1271
1272                 gl->gl_stamp = jiffies;
1273
1274                 spin_lock(&gl->gl_spin);
1275         }
1276
1277         clear_bit(GLF_LOCK, &gl->gl_flags);
1278         run_queue(gl);
1279         spin_unlock(&gl->gl_spin);
1280 }
1281
1282 /**
1283  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1284  * @gh: the holder structure
1285  *
1286  */
1287
1288 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1289 {
1290         gfs2_glock_dq(gh);
1291         gfs2_holder_uninit(gh);
1292 }
1293
1294 /**
1295  * gfs2_glock_nq_num - acquire a glock based on lock number
1296  * @sdp: the filesystem
1297  * @number: the lock number
1298  * @glops: the glock operations for the type of glock
1299  * @state: the state to acquire the glock in
1300  * @flags: modifier flags for the aquisition
1301  * @gh: the struct gfs2_holder
1302  *
1303  * Returns: errno
1304  */
1305
1306 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1307                       const struct gfs2_glock_operations *glops,
1308                       unsigned int state, int flags, struct gfs2_holder *gh)
1309 {
1310         struct gfs2_glock *gl;
1311         int error;
1312
1313         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1314         if (!error) {
1315                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1316                 gfs2_glock_put(gl);
1317         }
1318
1319         return error;
1320 }
1321
1322 /**
1323  * glock_compare - Compare two struct gfs2_glock structures for sorting
1324  * @arg_a: the first structure
1325  * @arg_b: the second structure
1326  *
1327  */
1328
1329 static int glock_compare(const void *arg_a, const void *arg_b)
1330 {
1331         const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1332         const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1333         const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1334         const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1335
1336         if (a->ln_number > b->ln_number)
1337                 return 1;
1338         if (a->ln_number < b->ln_number)
1339                 return -1;
1340         BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1341         return 0;
1342 }
1343
1344 /**
1345  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1346  * @num_gh: the number of structures
1347  * @ghs: an array of struct gfs2_holder structures
1348  *
1349  * Returns: 0 on success (all glocks acquired),
1350  *          errno on failure (no glocks acquired)
1351  */
1352
1353 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1354                      struct gfs2_holder **p)
1355 {
1356         unsigned int x;
1357         int error = 0;
1358
1359         for (x = 0; x < num_gh; x++)
1360                 p[x] = &ghs[x];
1361
1362         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1363
1364         for (x = 0; x < num_gh; x++) {
1365                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1366
1367                 error = gfs2_glock_nq(p[x]);
1368                 if (error) {
1369                         while (x--)
1370                                 gfs2_glock_dq(p[x]);
1371                         break;
1372                 }
1373         }
1374
1375         return error;
1376 }
1377
1378 /**
1379  * gfs2_glock_nq_m - acquire multiple glocks
1380  * @num_gh: the number of structures
1381  * @ghs: an array of struct gfs2_holder structures
1382  *
1383  * Figure out how big an impact this function has.  Either:
1384  * 1) Replace this code with code that calls gfs2_glock_prefetch()
1385  * 2) Forget async stuff and just call nq_m_sync()
1386  * 3) Leave it like it is
1387  *
1388  * Returns: 0 on success (all glocks acquired),
1389  *          errno on failure (no glocks acquired)
1390  */
1391
1392 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1393 {
1394         int *e;
1395         unsigned int x;
1396         int borked = 0, serious = 0;
1397         int error = 0;
1398
1399         if (!num_gh)
1400                 return 0;
1401
1402         if (num_gh == 1) {
1403                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1404                 return gfs2_glock_nq(ghs);
1405         }
1406
1407         e = kcalloc(num_gh, sizeof(struct gfs2_holder *), GFP_KERNEL);
1408         if (!e)
1409                 return -ENOMEM;
1410
1411         for (x = 0; x < num_gh; x++) {
1412                 ghs[x].gh_flags |= LM_FLAG_TRY | GL_ASYNC;
1413                 error = gfs2_glock_nq(&ghs[x]);
1414                 if (error) {
1415                         borked = 1;
1416                         serious = error;
1417                         num_gh = x;
1418                         break;
1419                 }
1420         }
1421
1422         for (x = 0; x < num_gh; x++) {
1423                 error = e[x] = glock_wait_internal(&ghs[x]);
1424                 if (error) {
1425                         borked = 1;
1426                         if (error != GLR_TRYFAILED && error != GLR_CANCELED)
1427                                 serious = error;
1428                 }
1429         }
1430
1431         if (!borked) {
1432                 kfree(e);
1433                 return 0;
1434         }
1435
1436         for (x = 0; x < num_gh; x++)
1437                 if (!e[x])
1438                         gfs2_glock_dq(&ghs[x]);
1439
1440         if (serious)
1441                 error = serious;
1442         else {
1443                 for (x = 0; x < num_gh; x++)
1444                         gfs2_holder_reinit(ghs[x].gh_state, ghs[x].gh_flags,
1445                                           &ghs[x]);
1446                 error = nq_m_sync(num_gh, ghs, (struct gfs2_holder **)e);
1447         }
1448
1449         kfree(e);
1450
1451         return error;
1452 }
1453
1454 /**
1455  * gfs2_glock_dq_m - release multiple glocks
1456  * @num_gh: the number of structures
1457  * @ghs: an array of struct gfs2_holder structures
1458  *
1459  */
1460
1461 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1462 {
1463         unsigned int x;
1464
1465         for (x = 0; x < num_gh; x++)
1466                 gfs2_glock_dq(&ghs[x]);
1467 }
1468
1469 /**
1470  * gfs2_glock_dq_uninit_m - release multiple glocks
1471  * @num_gh: the number of structures
1472  * @ghs: an array of struct gfs2_holder structures
1473  *
1474  */
1475
1476 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1477 {
1478         unsigned int x;
1479
1480         for (x = 0; x < num_gh; x++)
1481                 gfs2_glock_dq_uninit(&ghs[x]);
1482 }
1483
1484 /**
1485  * gfs2_lvb_hold - attach a LVB from a glock
1486  * @gl: The glock in question
1487  *
1488  */
1489
1490 int gfs2_lvb_hold(struct gfs2_glock *gl)
1491 {
1492         int error;
1493
1494         gfs2_glmutex_lock(gl);
1495
1496         if (!atomic_read(&gl->gl_lvb_count)) {
1497                 error = gfs2_lm_hold_lvb(gl->gl_sbd, gl->gl_lock, &gl->gl_lvb);
1498                 if (error) {
1499                         gfs2_glmutex_unlock(gl);
1500                         return error;
1501                 }
1502                 gfs2_glock_hold(gl);
1503         }
1504         atomic_inc(&gl->gl_lvb_count);
1505
1506         gfs2_glmutex_unlock(gl);
1507
1508         return 0;
1509 }
1510
1511 /**
1512  * gfs2_lvb_unhold - detach a LVB from a glock
1513  * @gl: The glock in question
1514  *
1515  */
1516
1517 void gfs2_lvb_unhold(struct gfs2_glock *gl)
1518 {
1519         gfs2_glock_hold(gl);
1520         gfs2_glmutex_lock(gl);
1521
1522         gfs2_assert(gl->gl_sbd, atomic_read(&gl->gl_lvb_count) > 0);
1523         if (atomic_dec_and_test(&gl->gl_lvb_count)) {
1524                 gfs2_lm_unhold_lvb(gl->gl_sbd, gl->gl_lock, gl->gl_lvb);
1525                 gl->gl_lvb = NULL;
1526                 gfs2_glock_put(gl);
1527         }
1528
1529         gfs2_glmutex_unlock(gl);
1530         gfs2_glock_put(gl);
1531 }
1532
1533 static void blocking_cb(struct gfs2_sbd *sdp, struct lm_lockname *name,
1534                         unsigned int state)
1535 {
1536         struct gfs2_glock *gl;
1537
1538         gl = gfs2_glock_find(sdp, name);
1539         if (!gl)
1540                 return;
1541
1542         handle_callback(gl, state);
1543
1544         spin_lock(&gl->gl_spin);
1545         run_queue(gl);
1546         spin_unlock(&gl->gl_spin);
1547
1548         gfs2_glock_put(gl);
1549 }
1550
1551 /**
1552  * gfs2_glock_cb - Callback used by locking module
1553  * @sdp: Pointer to the superblock
1554  * @type: Type of callback
1555  * @data: Type dependent data pointer
1556  *
1557  * Called by the locking module when it wants to tell us something.
1558  * Either we need to drop a lock, one of our ASYNC requests completed, or
1559  * a journal from another client needs to be recovered.
1560  */
1561
1562 void gfs2_glock_cb(void *cb_data, unsigned int type, void *data)
1563 {
1564         struct gfs2_sbd *sdp = cb_data;
1565
1566         switch (type) {
1567         case LM_CB_NEED_E:
1568                 blocking_cb(sdp, data, LM_ST_UNLOCKED);
1569                 return;
1570
1571         case LM_CB_NEED_D:
1572                 blocking_cb(sdp, data, LM_ST_DEFERRED);
1573                 return;
1574
1575         case LM_CB_NEED_S:
1576                 blocking_cb(sdp, data, LM_ST_SHARED);
1577                 return;
1578
1579         case LM_CB_ASYNC: {
1580                 struct lm_async_cb *async = data;
1581                 struct gfs2_glock *gl;
1582
1583                 down_read(&gfs2_umount_flush_sem);
1584                 gl = gfs2_glock_find(sdp, &async->lc_name);
1585                 if (gfs2_assert_warn(sdp, gl))
1586                         return;
1587                 if (!gfs2_assert_warn(sdp, gl->gl_req_bh))
1588                         gl->gl_req_bh(gl, async->lc_ret);
1589                 gfs2_glock_put(gl);
1590                 up_read(&gfs2_umount_flush_sem);
1591                 return;
1592         }
1593
1594         case LM_CB_NEED_RECOVERY:
1595                 gfs2_jdesc_make_dirty(sdp, *(unsigned int *)data);
1596                 if (sdp->sd_recoverd_process)
1597                         wake_up_process(sdp->sd_recoverd_process);
1598                 return;
1599
1600         case LM_CB_DROPLOCKS:
1601                 gfs2_gl_hash_clear(sdp, NO_WAIT);
1602                 gfs2_quota_scan(sdp);
1603                 return;
1604
1605         default:
1606                 gfs2_assert_warn(sdp, 0);
1607                 return;
1608         }
1609 }
1610
1611 /**
1612  * demote_ok - Check to see if it's ok to unlock a glock
1613  * @gl: the glock
1614  *
1615  * Returns: 1 if it's ok
1616  */
1617
1618 static int demote_ok(struct gfs2_glock *gl)
1619 {
1620         const struct gfs2_glock_operations *glops = gl->gl_ops;
1621         int demote = 1;
1622
1623         if (test_bit(GLF_STICKY, &gl->gl_flags))
1624                 demote = 0;
1625         else if (glops->go_demote_ok)
1626                 demote = glops->go_demote_ok(gl);
1627
1628         return demote;
1629 }
1630
1631 /**
1632  * gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
1633  * @gl: the glock
1634  *
1635  */
1636
1637 void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
1638 {
1639         struct gfs2_sbd *sdp = gl->gl_sbd;
1640
1641         spin_lock(&sdp->sd_reclaim_lock);
1642         if (list_empty(&gl->gl_reclaim)) {
1643                 gfs2_glock_hold(gl);
1644                 list_add(&gl->gl_reclaim, &sdp->sd_reclaim_list);
1645                 atomic_inc(&sdp->sd_reclaim_count);
1646         }
1647         spin_unlock(&sdp->sd_reclaim_lock);
1648
1649         wake_up(&sdp->sd_reclaim_wq);
1650 }
1651
1652 /**
1653  * gfs2_reclaim_glock - process the next glock on the filesystem's reclaim list
1654  * @sdp: the filesystem
1655  *
1656  * Called from gfs2_glockd() glock reclaim daemon, or when promoting a
1657  * different glock and we notice that there are a lot of glocks in the
1658  * reclaim list.
1659  *
1660  */
1661
1662 void gfs2_reclaim_glock(struct gfs2_sbd *sdp)
1663 {
1664         struct gfs2_glock *gl;
1665
1666         spin_lock(&sdp->sd_reclaim_lock);
1667         if (list_empty(&sdp->sd_reclaim_list)) {
1668                 spin_unlock(&sdp->sd_reclaim_lock);
1669                 return;
1670         }
1671         gl = list_entry(sdp->sd_reclaim_list.next,
1672                         struct gfs2_glock, gl_reclaim);
1673         list_del_init(&gl->gl_reclaim);
1674         spin_unlock(&sdp->sd_reclaim_lock);
1675
1676         atomic_dec(&sdp->sd_reclaim_count);
1677         atomic_inc(&sdp->sd_reclaimed);
1678
1679         if (gfs2_glmutex_trylock(gl)) {
1680                 if (list_empty(&gl->gl_holders) &&
1681                     gl->gl_state != LM_ST_UNLOCKED && demote_ok(gl))
1682                         handle_callback(gl, LM_ST_UNLOCKED);
1683                 gfs2_glmutex_unlock(gl);
1684         }
1685
1686         gfs2_glock_put(gl);
1687 }
1688
1689 /**
1690  * examine_bucket - Call a function for glock in a hash bucket
1691  * @examiner: the function
1692  * @sdp: the filesystem
1693  * @bucket: the bucket
1694  *
1695  * Returns: 1 if the bucket has entries
1696  */
1697
1698 static int examine_bucket(glock_examiner examiner, struct gfs2_sbd *sdp,
1699                           unsigned int hash)
1700 {
1701         struct gfs2_glock *gl, *prev = NULL;
1702         int has_entries = 0;
1703         struct hlist_head *head = &gl_hash_table[hash].hb_list;
1704
1705         read_lock(gl_lock_addr(hash));
1706         /* Can't use hlist_for_each_entry - don't want prefetch here */
1707         if (hlist_empty(head))
1708                 goto out;
1709         gl = list_entry(head->first, struct gfs2_glock, gl_list);
1710         while(1) {
1711                 if (gl->gl_sbd == sdp) {
1712                         gfs2_glock_hold(gl);
1713                         read_unlock(gl_lock_addr(hash));
1714                         if (prev)
1715                                 gfs2_glock_put(prev);
1716                         prev = gl;
1717                         examiner(gl);
1718                         has_entries = 1;
1719                         read_lock(gl_lock_addr(hash));
1720                 }
1721                 if (gl->gl_list.next == NULL)
1722                         break;
1723                 gl = list_entry(gl->gl_list.next, struct gfs2_glock, gl_list);
1724         }
1725 out:
1726         read_unlock(gl_lock_addr(hash));
1727         if (prev)
1728                 gfs2_glock_put(prev);
1729         return has_entries;
1730 }
1731
1732 /**
1733  * scan_glock - look at a glock and see if we can reclaim it
1734  * @gl: the glock to look at
1735  *
1736  */
1737
1738 static void scan_glock(struct gfs2_glock *gl)
1739 {
1740         if (gl->gl_ops == &gfs2_inode_glops && gl->gl_object)
1741                 return;
1742
1743         if (gfs2_glmutex_trylock(gl)) {
1744                 if (list_empty(&gl->gl_holders) &&
1745                     gl->gl_state != LM_ST_UNLOCKED && demote_ok(gl))
1746                         goto out_schedule;
1747                 gfs2_glmutex_unlock(gl);
1748         }
1749         return;
1750
1751 out_schedule:
1752         gfs2_glmutex_unlock(gl);
1753         gfs2_glock_schedule_for_reclaim(gl);
1754 }
1755
1756 /**
1757  * gfs2_scand_internal - Look for glocks and inodes to toss from memory
1758  * @sdp: the filesystem
1759  *
1760  */
1761
1762 void gfs2_scand_internal(struct gfs2_sbd *sdp)
1763 {
1764         unsigned int x;
1765
1766         for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1767                 examine_bucket(scan_glock, sdp, x);
1768 }
1769
1770 /**
1771  * clear_glock - look at a glock and see if we can free it from glock cache
1772  * @gl: the glock to look at
1773  *
1774  */
1775
1776 static void clear_glock(struct gfs2_glock *gl)
1777 {
1778         struct gfs2_sbd *sdp = gl->gl_sbd;
1779         int released;
1780
1781         spin_lock(&sdp->sd_reclaim_lock);
1782         if (!list_empty(&gl->gl_reclaim)) {
1783                 list_del_init(&gl->gl_reclaim);
1784                 atomic_dec(&sdp->sd_reclaim_count);
1785                 spin_unlock(&sdp->sd_reclaim_lock);
1786                 released = gfs2_glock_put(gl);
1787                 gfs2_assert(sdp, !released);
1788         } else {
1789                 spin_unlock(&sdp->sd_reclaim_lock);
1790         }
1791
1792         if (gfs2_glmutex_trylock(gl)) {
1793                 if (list_empty(&gl->gl_holders) &&
1794                     gl->gl_state != LM_ST_UNLOCKED)
1795                         handle_callback(gl, LM_ST_UNLOCKED);
1796                 gfs2_glmutex_unlock(gl);
1797         }
1798 }
1799
1800 /**
1801  * gfs2_gl_hash_clear - Empty out the glock hash table
1802  * @sdp: the filesystem
1803  * @wait: wait until it's all gone
1804  *
1805  * Called when unmounting the filesystem, or when inter-node lock manager
1806  * requests DROPLOCKS because it is running out of capacity.
1807  */
1808
1809 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp, int wait)
1810 {
1811         unsigned long t;
1812         unsigned int x;
1813         int cont;
1814
1815         t = jiffies;
1816
1817         for (;;) {
1818                 cont = 0;
1819                 for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
1820                         if (examine_bucket(clear_glock, sdp, x))
1821                                 cont = 1;
1822                 }
1823
1824                 if (!wait || !cont)
1825                         break;
1826
1827                 if (time_after_eq(jiffies,
1828                                   t + gfs2_tune_get(sdp, gt_stall_secs) * HZ)) {
1829                         fs_warn(sdp, "Unmount seems to be stalled. "
1830                                      "Dumping lock state...\n");
1831                         gfs2_dump_lockstate(sdp);
1832                         t = jiffies;
1833                 }
1834
1835                 down_write(&gfs2_umount_flush_sem);
1836                 invalidate_inodes(sdp->sd_vfs);
1837                 up_write(&gfs2_umount_flush_sem);
1838                 msleep(10);
1839         }
1840 }
1841
1842 /*
1843  *  Diagnostic routines to help debug distributed deadlock
1844  */
1845
1846 /**
1847  * dump_holder - print information about a glock holder
1848  * @str: a string naming the type of holder
1849  * @gh: the glock holder
1850  *
1851  * Returns: 0 on success, -ENOBUFS when we run out of space
1852  */
1853
1854 static int dump_holder(char *str, struct gfs2_holder *gh)
1855 {
1856         unsigned int x;
1857         int error = -ENOBUFS;
1858
1859         printk(KERN_INFO "  %s\n", str);
1860         printk(KERN_INFO "    owner = %ld\n",
1861                    (gh->gh_owner) ? (long)gh->gh_owner->pid : -1);
1862         printk(KERN_INFO "    gh_state = %u\n", gh->gh_state);
1863         printk(KERN_INFO "    gh_flags =");
1864         for (x = 0; x < 32; x++)
1865                 if (gh->gh_flags & (1 << x))
1866                         printk(" %u", x);
1867         printk(" \n");
1868         printk(KERN_INFO "    error = %d\n", gh->gh_error);
1869         printk(KERN_INFO "    gh_iflags =");
1870         for (x = 0; x < 32; x++)
1871                 if (test_bit(x, &gh->gh_iflags))
1872                         printk(" %u", x);
1873         printk(" \n");
1874         print_symbol(KERN_INFO "    initialized at: %s\n", gh->gh_ip);
1875
1876         error = 0;
1877
1878         return error;
1879 }
1880
1881 /**
1882  * dump_inode - print information about an inode
1883  * @ip: the inode
1884  *
1885  * Returns: 0 on success, -ENOBUFS when we run out of space
1886  */
1887
1888 static int dump_inode(struct gfs2_inode *ip)
1889 {
1890         unsigned int x;
1891         int error = -ENOBUFS;
1892
1893         printk(KERN_INFO "  Inode:\n");
1894         printk(KERN_INFO "    num = %llu %llu\n",
1895                     (unsigned long long)ip->i_num.no_formal_ino,
1896                     (unsigned long long)ip->i_num.no_addr);
1897         printk(KERN_INFO "    type = %u\n", IF2DT(ip->i_inode.i_mode));
1898         printk(KERN_INFO "    i_flags =");
1899         for (x = 0; x < 32; x++)
1900                 if (test_bit(x, &ip->i_flags))
1901                         printk(" %u", x);
1902         printk(" \n");
1903
1904         error = 0;
1905
1906         return error;
1907 }
1908
1909 /**
1910  * dump_glock - print information about a glock
1911  * @gl: the glock
1912  * @count: where we are in the buffer
1913  *
1914  * Returns: 0 on success, -ENOBUFS when we run out of space
1915  */
1916
1917 static int dump_glock(struct gfs2_glock *gl)
1918 {
1919         struct gfs2_holder *gh;
1920         unsigned int x;
1921         int error = -ENOBUFS;
1922
1923         spin_lock(&gl->gl_spin);
1924
1925         printk(KERN_INFO "Glock 0x%p (%u, %llu)\n", gl, gl->gl_name.ln_type,
1926                (unsigned long long)gl->gl_name.ln_number);
1927         printk(KERN_INFO "  gl_flags =");
1928         for (x = 0; x < 32; x++) {
1929                 if (test_bit(x, &gl->gl_flags))
1930                         printk(" %u", x);
1931         }
1932         printk(" \n");
1933         printk(KERN_INFO "  gl_ref = %d\n", atomic_read(&gl->gl_ref));
1934         printk(KERN_INFO "  gl_state = %u\n", gl->gl_state);
1935         printk(KERN_INFO "  gl_owner = %s\n", gl->gl_owner->comm);
1936         print_symbol(KERN_INFO "  gl_ip = %s\n", gl->gl_ip);
1937         printk(KERN_INFO "  req_gh = %s\n", (gl->gl_req_gh) ? "yes" : "no");
1938         printk(KERN_INFO "  req_bh = %s\n", (gl->gl_req_bh) ? "yes" : "no");
1939         printk(KERN_INFO "  lvb_count = %d\n", atomic_read(&gl->gl_lvb_count));
1940         printk(KERN_INFO "  object = %s\n", (gl->gl_object) ? "yes" : "no");
1941         printk(KERN_INFO "  le = %s\n",
1942                    (list_empty(&gl->gl_le.le_list)) ? "no" : "yes");
1943         printk(KERN_INFO "  reclaim = %s\n",
1944                     (list_empty(&gl->gl_reclaim)) ? "no" : "yes");
1945         if (gl->gl_aspace)
1946                 printk(KERN_INFO "  aspace = 0x%p nrpages = %lu\n", gl->gl_aspace,
1947                        gl->gl_aspace->i_mapping->nrpages);
1948         else
1949                 printk(KERN_INFO "  aspace = no\n");
1950         printk(KERN_INFO "  ail = %d\n", atomic_read(&gl->gl_ail_count));
1951         if (gl->gl_req_gh) {
1952                 error = dump_holder("Request", gl->gl_req_gh);
1953                 if (error)
1954                         goto out;
1955         }
1956         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1957                 error = dump_holder("Holder", gh);
1958                 if (error)
1959                         goto out;
1960         }
1961         list_for_each_entry(gh, &gl->gl_waiters1, gh_list) {
1962                 error = dump_holder("Waiter1", gh);
1963                 if (error)
1964                         goto out;
1965         }
1966         list_for_each_entry(gh, &gl->gl_waiters2, gh_list) {
1967                 error = dump_holder("Waiter2", gh);
1968                 if (error)
1969                         goto out;
1970         }
1971         list_for_each_entry(gh, &gl->gl_waiters3, gh_list) {
1972                 error = dump_holder("Waiter3", gh);
1973                 if (error)
1974                         goto out;
1975         }
1976         if (gl->gl_ops == &gfs2_inode_glops && gl->gl_object) {
1977                 if (!test_bit(GLF_LOCK, &gl->gl_flags) &&
1978                     list_empty(&gl->gl_holders)) {
1979                         error = dump_inode(gl->gl_object);
1980                         if (error)
1981                                 goto out;
1982                 } else {
1983                         error = -ENOBUFS;
1984                         printk(KERN_INFO "  Inode: busy\n");
1985                 }
1986         }
1987
1988         error = 0;
1989
1990 out:
1991         spin_unlock(&gl->gl_spin);
1992         return error;
1993 }
1994
1995 /**
1996  * gfs2_dump_lockstate - print out the current lockstate
1997  * @sdp: the filesystem
1998  * @ub: the buffer to copy the information into
1999  *
2000  * If @ub is NULL, dump the lockstate to the console.
2001  *
2002  */
2003
2004 static int gfs2_dump_lockstate(struct gfs2_sbd *sdp)
2005 {
2006         struct gfs2_glock *gl;
2007         struct hlist_node *h;
2008         unsigned int x;
2009         int error = 0;
2010
2011         for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
2012
2013                 read_lock(gl_lock_addr(x));
2014
2015                 hlist_for_each_entry(gl, h, &gl_hash_table[x].hb_list, gl_list) {
2016                         if (gl->gl_sbd != sdp)
2017                                 continue;
2018
2019                         error = dump_glock(gl);
2020                         if (error)
2021                                 break;
2022                 }
2023
2024                 read_unlock(gl_lock_addr(x));
2025
2026                 if (error)
2027                         break;
2028         }
2029
2030
2031         return error;
2032 }
2033
2034 int __init gfs2_glock_init(void)
2035 {
2036         unsigned i;
2037         for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
2038                 INIT_HLIST_HEAD(&gl_hash_table[i].hb_list);
2039         }
2040 #ifdef GL_HASH_LOCK_SZ
2041         for(i = 0; i < GL_HASH_LOCK_SZ; i++) {
2042                 rwlock_init(&gl_hash_locks[i]);
2043         }
2044 #endif
2045         return 0;
2046 }
2047