git.oblomov.eu Git - linux-2.6/blob - fs/gfs2/glock.c

   1 /*
   2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   3  * Copyright (C) 2004-2008 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/buffer_head.h>
  14 #include <linux/delay.h>
  15 #include <linux/sort.h>
  16 #include <linux/jhash.h>
  17 #include <linux/kallsyms.h>
  18 #include <linux/gfs2_ondisk.h>
  19 #include <linux/list.h>
  20 #include <linux/wait.h>
  21 #include <linux/module.h>
  22 #include <linux/rwsem.h>
  23 #include <asm/uaccess.h>
  24 #include <linux/seq_file.h>
  25 #include <linux/debugfs.h>
  26 #include <linux/kthread.h>
  27 #include <linux/freezer.h>
  28 #include <linux/workqueue.h>
  29 #include <linux/jiffies.h>
  30
  31 #include "gfs2.h"
  32 #include "incore.h"
  33 #include "glock.h"
  34 #include "glops.h"
  35 #include "inode.h"
  36 #include "lops.h"
  37 #include "meta_io.h"
  38 #include "quota.h"
  39 #include "super.h"
  40 #include "util.h"
  41 #include "bmap.h"
  42 #define CREATE_TRACE_POINTS
  43 #include "trace_gfs2.h"
  44
  45 struct gfs2_gl_hash_bucket {
  46         struct hlist_head hb_list;
  47 };
  48
  49 struct gfs2_glock_iter {
  50         int hash;                       /* hash bucket index         */
  51         struct gfs2_sbd *sdp;           /* incore superblock         */
  52         struct gfs2_glock *gl;          /* current glock struct      */
  53         char string[512];               /* scratch space             */
  54 };
  55
  56 typedef void (*glock_examiner) (struct gfs2_glock * gl);
  57
  58 static int gfs2_dump_lockstate(struct gfs2_sbd *sdp);
  59 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl);
  60 #define GLOCK_BUG_ON(gl,x) do { if (unlikely(x)) { __dump_glock(NULL, gl); BUG(); } } while(0)
  61 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
  62
  63 static DECLARE_RWSEM(gfs2_umount_flush_sem);
  64 static struct dentry *gfs2_root;
  65 static struct workqueue_struct *glock_workqueue;
  66 static LIST_HEAD(lru_list);
  67 static atomic_t lru_count = ATOMIC_INIT(0);
  68 static DEFINE_SPINLOCK(lru_lock);
  69
  70 #define GFS2_GL_HASH_SHIFT      15
  71 #define GFS2_GL_HASH_SIZE       (1 << GFS2_GL_HASH_SHIFT)
  72 #define GFS2_GL_HASH_MASK       (GFS2_GL_HASH_SIZE - 1)
  73
  74 static struct gfs2_gl_hash_bucket gl_hash_table[GFS2_GL_HASH_SIZE];
  75 static struct dentry *gfs2_root;
  76
  77 /*
  78  * Despite what you might think, the numbers below are not arbitrary :-)
  79  * They are taken from the ipv4 routing hash code, which is well tested
  80  * and thus should be nearly optimal. Later on we might tweek the numbers
  81  * but for now this should be fine.
  82  *
  83  * The reason for putting the locks in a separate array from the list heads
  84  * is that we can have fewer locks than list heads and save memory. We use
  85  * the same hash function for both, but with a different hash mask.
  86  */
  87 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) || \
  88         defined(CONFIG_PROVE_LOCKING)
  89
  90 #ifdef CONFIG_LOCKDEP
  91 # define GL_HASH_LOCK_SZ        256
  92 #else
  93 # if NR_CPUS >= 32
  94 #  define GL_HASH_LOCK_SZ       4096
  95 # elif NR_CPUS >= 16
  96 #  define GL_HASH_LOCK_SZ       2048
  97 # elif NR_CPUS >= 8
  98 #  define GL_HASH_LOCK_SZ       1024
  99 # elif NR_CPUS >= 4
 100 #  define GL_HASH_LOCK_SZ       512
 101 # else
 102 #  define GL_HASH_LOCK_SZ       256
 103 # endif
 104 #endif
 105
 106 /* We never want more locks than chains */
 107 #if GFS2_GL_HASH_SIZE < GL_HASH_LOCK_SZ
 108 # undef GL_HASH_LOCK_SZ
 109 # define GL_HASH_LOCK_SZ GFS2_GL_HASH_SIZE
 110 #endif
 111
 112 static rwlock_t gl_hash_locks[GL_HASH_LOCK_SZ];
 113
 114 static inline rwlock_t *gl_lock_addr(unsigned int x)
 115 {
 116         return &gl_hash_locks[x & (GL_HASH_LOCK_SZ-1)];
 117 }
 118 #else /* not SMP, so no spinlocks required */
 119 static inline rwlock_t *gl_lock_addr(unsigned int x)
 120 {
 121         return NULL;
 122 }
 123 #endif
 124
 125 /**
 126  * gl_hash() - Turn glock number into hash bucket number
 127  * @lock: The glock number
 128  *
 129  * Returns: The number of the corresponding hash bucket
 130  */
 131
 132 static unsigned int gl_hash(const struct gfs2_sbd *sdp,
 133                             const struct lm_lockname *name)
 134 {
 135         unsigned int h;
 136
 137         h = jhash(&name->ln_number, sizeof(u64), 0);
 138         h = jhash(&name->ln_type, sizeof(unsigned int), h);
 139         h = jhash(&sdp, sizeof(struct gfs2_sbd *), h);
 140         h &= GFS2_GL_HASH_MASK;
 141
 142         return h;
 143 }
 144
 145 /**
 146  * glock_free() - Perform a few checks and then release struct gfs2_glock
 147  * @gl: The glock to release
 148  *
 149  * Also calls lock module to release its internal structure for this glock.
 150  *
 151  */
 152
 153 static void glock_free(struct gfs2_glock *gl)
 154 {
 155         struct gfs2_sbd *sdp = gl->gl_sbd;
 156         struct inode *aspace = gl->gl_aspace;
 157
 158         if (aspace)
 159                 gfs2_aspace_put(aspace);
 160         trace_gfs2_glock_put(gl);
 161         sdp->sd_lockstruct.ls_ops->lm_put_lock(gfs2_glock_cachep, gl);
 162 }
 163
 164 /**
 165  * gfs2_glock_hold() - increment reference count on glock
 166  * @gl: The glock to hold
 167  *
 168  */
 169
 170 static void gfs2_glock_hold(struct gfs2_glock *gl)
 171 {
 172         GLOCK_BUG_ON(gl, atomic_read(&gl->gl_ref) == 0);
 173         atomic_inc(&gl->gl_ref);
 174 }
 175
 176 /**
 177  * gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
 178  * @gl: the glock
 179  *
 180  */
 181
 182 static void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
 183 {
 184         spin_lock(&lru_lock);
 185         if (list_empty(&gl->gl_lru) && gl->gl_state != LM_ST_UNLOCKED) {
 186                 list_add_tail(&gl->gl_lru, &lru_list);
 187                 atomic_inc(&lru_count);
 188         }
 189         spin_unlock(&lru_lock);
 190 }
 191
 192 /**
 193  * gfs2_glock_put() - Decrement reference count on glock
 194  * @gl: The glock to put
 195  *
 196  */
 197
 198 int gfs2_glock_put(struct gfs2_glock *gl)
 199 {
 200         int rv = 0;
 201
 202         write_lock(gl_lock_addr(gl->gl_hash));
 203         if (atomic_dec_and_test(&gl->gl_ref)) {
 204                 hlist_del(&gl->gl_list);
 205                 write_unlock(gl_lock_addr(gl->gl_hash));
 206                 spin_lock(&lru_lock);
 207                 if (!list_empty(&gl->gl_lru)) {
 208                         list_del_init(&gl->gl_lru);
 209                         atomic_dec(&lru_count);
 210                 }
 211                 spin_unlock(&lru_lock);
 212                 GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
 213                 glock_free(gl);
 214                 rv = 1;
 215                 goto out;
 216         }
 217         /* 1 for being hashed, 1 for having state != LM_ST_UNLOCKED */
 218         if (atomic_read(&gl->gl_ref) == 2)
 219                 gfs2_glock_schedule_for_reclaim(gl);
 220         write_unlock(gl_lock_addr(gl->gl_hash));
 221 out:
 222         return rv;
 223 }
 224
 225 /**
 226  * search_bucket() - Find struct gfs2_glock by lock number
 227  * @bucket: the bucket to search
 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 *search_bucket(unsigned int hash,
 234                                         const struct gfs2_sbd *sdp,
 235                                         const struct lm_lockname *name)
 236 {
 237         struct gfs2_glock *gl;
 238         struct hlist_node *h;
 239
 240         hlist_for_each_entry(gl, h, &gl_hash_table[hash].hb_list, gl_list) {
 241                 if (!lm_name_equal(&gl->gl_name, name))
 242                         continue;
 243                 if (gl->gl_sbd != sdp)
 244                         continue;
 245
 246                 atomic_inc(&gl->gl_ref);
 247
 248                 return gl;
 249         }
 250
 251         return NULL;
 252 }
 253
 254 /**
 255  * may_grant - check if its ok to grant a new lock
 256  * @gl: The glock
 257  * @gh: The lock request which we wish to grant
 258  *
 259  * Returns: true if its ok to grant the lock
 260  */
 261
 262 static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
 263 {
 264         const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
 265         if ((gh->gh_state == LM_ST_EXCLUSIVE ||
 266              gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
 267                 return 0;
 268         if (gl->gl_state == gh->gh_state)
 269                 return 1;
 270         if (gh->gh_flags & GL_EXACT)
 271                 return 0;
 272         if (gl->gl_state == LM_ST_EXCLUSIVE) {
 273                 if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
 274                         return 1;
 275                 if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
 276                         return 1;
 277         }
 278         if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
 279                 return 1;
 280         return 0;
 281 }
 282
 283 static void gfs2_holder_wake(struct gfs2_holder *gh)
 284 {
 285         clear_bit(HIF_WAIT, &gh->gh_iflags);
 286         smp_mb__after_clear_bit();
 287         wake_up_bit(&gh->gh_iflags, HIF_WAIT);
 288 }
 289
 290 /**
 291  * do_promote - promote as many requests as possible on the current queue
 292  * @gl: The glock
 293  *
 294  * Returns: 1 if there is a blocked holder at the head of the list, or 2
 295  *          if a type specific operation is underway.
 296  */
 297
 298 static int do_promote(struct gfs2_glock *gl)
 299 __releases(&gl->gl_spin)
 300 __acquires(&gl->gl_spin)
 301 {
 302         const struct gfs2_glock_operations *glops = gl->gl_ops;
 303         struct gfs2_holder *gh, *tmp;
 304         int ret;
 305
 306 restart:
 307         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 308                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 309                         continue;
 310                 if (may_grant(gl, gh)) {
 311                         if (gh->gh_list.prev == &gl->gl_holders &&
 312                             glops->go_lock) {
 313                                 spin_unlock(&gl->gl_spin);
 314                                 /* FIXME: eliminate this eventually */
 315                                 ret = glops->go_lock(gh);
 316                                 spin_lock(&gl->gl_spin);
 317                                 if (ret) {
 318                                         if (ret == 1)
 319                                                 return 2;
 320                                         gh->gh_error = ret;
 321                                         list_del_init(&gh->gh_list);
 322                                         trace_gfs2_glock_queue(gh, 0);
 323                                         gfs2_holder_wake(gh);
 324                                         goto restart;
 325                                 }
 326                                 set_bit(HIF_HOLDER, &gh->gh_iflags);
 327                                 trace_gfs2_promote(gh, 1);
 328                                 gfs2_holder_wake(gh);
 329                                 goto restart;
 330                         }
 331                         set_bit(HIF_HOLDER, &gh->gh_iflags);
 332                         trace_gfs2_promote(gh, 0);
 333                         gfs2_holder_wake(gh);
 334                         continue;
 335                 }
 336                 if (gh->gh_list.prev == &gl->gl_holders)
 337                         return 1;
 338                 break;
 339         }
 340         return 0;
 341 }
 342
 343 /**
 344  * do_error - Something unexpected has happened during a lock request
 345  *
 346  */
 347
 348 static inline void do_error(struct gfs2_glock *gl, const int ret)
 349 {
 350         struct gfs2_holder *gh, *tmp;
 351
 352         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 353                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 354                         continue;
 355                 if (ret & LM_OUT_ERROR)
 356                         gh->gh_error = -EIO;
 357                 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
 358                         gh->gh_error = GLR_TRYFAILED;
 359                 else
 360                         continue;
 361                 list_del_init(&gh->gh_list);
 362                 trace_gfs2_glock_queue(gh, 0);
 363                 gfs2_holder_wake(gh);
 364         }
 365 }
 366
 367 /**
 368  * find_first_waiter - find the first gh that's waiting for the glock
 369  * @gl: the glock
 370  */
 371
 372 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
 373 {
 374         struct gfs2_holder *gh;
 375
 376         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
 377                 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
 378                         return gh;
 379         }
 380         return NULL;
 381 }
 382
 383 /**
 384  * state_change - record that the glock is now in a different state
 385  * @gl: the glock
 386  * @new_state the new state
 387  *
 388  */
 389
 390 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 391 {
 392         int held1, held2;
 393
 394         held1 = (gl->gl_state != LM_ST_UNLOCKED);
 395         held2 = (new_state != LM_ST_UNLOCKED);
 396
 397         if (held1 != held2) {
 398                 if (held2)
 399                         gfs2_glock_hold(gl);
 400                 else
 401                         gfs2_glock_put(gl);
 402         }
 403
 404         gl->gl_state = new_state;
 405         gl->gl_tchange = jiffies;
 406 }
 407
 408 static void gfs2_demote_wake(struct gfs2_glock *gl)
 409 {
 410         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 411         clear_bit(GLF_DEMOTE, &gl->gl_flags);
 412         smp_mb__after_clear_bit();
 413         wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
 414 }
 415
 416 /**
 417  * finish_xmote - The DLM has replied to one of our lock requests
 418  * @gl: The glock
 419  * @ret: The status from the DLM
 420  *
 421  */
 422
 423 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
 424 {
 425         const struct gfs2_glock_operations *glops = gl->gl_ops;
 426         struct gfs2_holder *gh;
 427         unsigned state = ret & LM_OUT_ST_MASK;
 428         int rv;
 429
 430         spin_lock(&gl->gl_spin);
 431         trace_gfs2_glock_state_change(gl, state);
 432         state_change(gl, state);
 433         gh = find_first_waiter(gl);
 434
 435         /* Demote to UN request arrived during demote to SH or DF */
 436         if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
 437             state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
 438                 gl->gl_target = LM_ST_UNLOCKED;
 439
 440         /* Check for state != intended state */
 441         if (unlikely(state != gl->gl_target)) {
 442                 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
 443                         /* move to back of queue and try next entry */
 444                         if (ret & LM_OUT_CANCELED) {
 445                                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
 446                                         list_move_tail(&gh->gh_list, &gl->gl_holders);
 447                                 gh = find_first_waiter(gl);
 448                                 gl->gl_target = gh->gh_state;
 449                                 goto retry;
 450                         }
 451                         /* Some error or failed "try lock" - report it */
 452                         if ((ret & LM_OUT_ERROR) ||
 453                             (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 454                                 gl->gl_target = gl->gl_state;
 455                                 do_error(gl, ret);
 456                                 goto out;
 457                         }
 458                 }
 459                 switch(state) {
 460                 /* Unlocked due to conversion deadlock, try again */
 461                 case LM_ST_UNLOCKED:
 462 retry:
 463                         do_xmote(gl, gh, gl->gl_target);
 464                         break;
 465                 /* Conversion fails, unlock and try again */
 466                 case LM_ST_SHARED:
 467                 case LM_ST_DEFERRED:
 468                         do_xmote(gl, gh, LM_ST_UNLOCKED);
 469                         break;
 470                 default: /* Everything else */
 471                         printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
 472                         GLOCK_BUG_ON(gl, 1);
 473                 }
 474                 spin_unlock(&gl->gl_spin);
 475                 gfs2_glock_put(gl);
 476                 return;
 477         }
 478
 479         /* Fast path - we got what we asked for */
 480         if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
 481                 gfs2_demote_wake(gl);
 482         if (state != LM_ST_UNLOCKED) {
 483                 if (glops->go_xmote_bh) {
 484                         spin_unlock(&gl->gl_spin);
 485                         rv = glops->go_xmote_bh(gl, gh);
 486                         if (rv == -EAGAIN)
 487                                 return;
 488                         spin_lock(&gl->gl_spin);
 489                         if (rv) {
 490                                 do_error(gl, rv);
 491                                 goto out;
 492                         }
 493                 }
 494                 rv = do_promote(gl);
 495                 if (rv == 2)
 496                         goto out_locked;
 497         }
 498 out:
 499         clear_bit(GLF_LOCK, &gl->gl_flags);
 500 out_locked:
 501         spin_unlock(&gl->gl_spin);
 502         gfs2_glock_put(gl);
 503 }
 504
 505 static unsigned int gfs2_lm_lock(struct gfs2_sbd *sdp, void *lock,
 506                                  unsigned int req_state,
 507                                  unsigned int flags)
 508 {
 509         int ret = LM_OUT_ERROR;
 510
 511         if (!sdp->sd_lockstruct.ls_ops->lm_lock)
 512                 return req_state == LM_ST_UNLOCKED ? 0 : req_state;
 513
 514         if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 515                 ret = sdp->sd_lockstruct.ls_ops->lm_lock(lock,
 516                                                          req_state, flags);
 517         return ret;
 518 }
 519
 520 /**
 521  * do_xmote - Calls the DLM to change the state of a lock
 522  * @gl: The lock state
 523  * @gh: The holder (only for promotes)
 524  * @target: The target lock state
 525  *
 526  */
 527
 528 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
 529 __releases(&gl->gl_spin)
 530 __acquires(&gl->gl_spin)
 531 {
 532         const struct gfs2_glock_operations *glops = gl->gl_ops;
 533         struct gfs2_sbd *sdp = gl->gl_sbd;
 534         unsigned int lck_flags = gh ? gh->gh_flags : 0;
 535         int ret;
 536
 537         lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
 538                       LM_FLAG_PRIORITY);
 539         BUG_ON(gl->gl_state == target);
 540         BUG_ON(gl->gl_state == gl->gl_target);
 541         if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
 542             glops->go_inval) {
 543                 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 544                 do_error(gl, 0); /* Fail queued try locks */
 545         }
 546         spin_unlock(&gl->gl_spin);
 547         if (glops->go_xmote_th)
 548                 glops->go_xmote_th(gl);
 549         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 550                 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
 551         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 552
 553         gfs2_glock_hold(gl);
 554         if (target != LM_ST_UNLOCKED && (gl->gl_state == LM_ST_SHARED ||
 555             gl->gl_state == LM_ST_DEFERRED) &&
 556             !(lck_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 557                 lck_flags |= LM_FLAG_TRY_1CB;
 558         ret = gfs2_lm_lock(sdp, gl, target, lck_flags);
 559
 560         if (!(ret & LM_OUT_ASYNC)) {
 561                 finish_xmote(gl, ret);
 562                 gfs2_glock_hold(gl);
 563                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 564                         gfs2_glock_put(gl);
 565         } else {
 566                 GLOCK_BUG_ON(gl, ret != LM_OUT_ASYNC);
 567         }
 568         spin_lock(&gl->gl_spin);
 569 }
 570
 571 /**
 572  * find_first_holder - find the first "holder" gh
 573  * @gl: the glock
 574  */
 575
 576 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
 577 {
 578         struct gfs2_holder *gh;
 579
 580         if (!list_empty(&gl->gl_holders)) {
 581                 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 582                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 583                         return gh;
 584         }
 585         return NULL;
 586 }
 587
 588 /**
 589  * run_queue - do all outstanding tasks related to a glock
 590  * @gl: The glock in question
 591  * @nonblock: True if we must not block in run_queue
 592  *
 593  */
 594
 595 static void run_queue(struct gfs2_glock *gl, const int nonblock)
 596 __releases(&gl->gl_spin)
 597 __acquires(&gl->gl_spin)
 598 {
 599         struct gfs2_holder *gh = NULL;
 600         int ret;
 601
 602         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 603                 return;
 604
 605         GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
 606
 607         if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
 608             gl->gl_demote_state != gl->gl_state) {
 609                 if (find_first_holder(gl))
 610                         goto out_unlock;
 611                 if (nonblock)
 612                         goto out_sched;
 613                 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
 614                 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
 615                 gl->gl_target = gl->gl_demote_state;
 616         } else {
 617                 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
 618                         gfs2_demote_wake(gl);
 619                 ret = do_promote(gl);
 620                 if (ret == 0)
 621                         goto out_unlock;
 622                 if (ret == 2)
 623                         goto out;
 624                 gh = find_first_waiter(gl);
 625                 gl->gl_target = gh->gh_state;
 626                 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 627                         do_error(gl, 0); /* Fail queued try locks */
 628         }
 629         do_xmote(gl, gh, gl->gl_target);
 630 out:
 631         return;
 632
 633 out_sched:
 634         gfs2_glock_hold(gl);
 635         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 636                 gfs2_glock_put(gl);
 637 out_unlock:
 638         clear_bit(GLF_LOCK, &gl->gl_flags);
 639         goto out;
 640 }
 641
 642 static void glock_work_func(struct work_struct *work)
 643 {
 644         unsigned long delay = 0;
 645         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
 646
 647         if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags))
 648                 finish_xmote(gl, gl->gl_reply);
 649         down_read(&gfs2_umount_flush_sem);
 650         spin_lock(&gl->gl_spin);
 651         if (test_and_clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
 652             gl->gl_state != LM_ST_UNLOCKED &&
 653             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
 654                 unsigned long holdtime, now = jiffies;
 655                 holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
 656                 if (time_before(now, holdtime))
 657                         delay = holdtime - now;
 658                 set_bit(delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE, &gl->gl_flags);
 659         }
 660         run_queue(gl, 0);
 661         spin_unlock(&gl->gl_spin);
 662         up_read(&gfs2_umount_flush_sem);
 663         if (!delay ||
 664             queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
 665                 gfs2_glock_put(gl);
 666 }
 667
 668 /**
 669  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
 670  * @sdp: The GFS2 superblock
 671  * @number: the lock number
 672  * @glops: The glock_operations to use
 673  * @create: If 0, don't create the glock if it doesn't exist
 674  * @glp: the glock is returned here
 675  *
 676  * This does not lock a glock, just finds/creates structures for one.
 677  *
 678  * Returns: errno
 679  */
 680
 681 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 682                    const struct gfs2_glock_operations *glops, int create,
 683                    struct gfs2_glock **glp)
 684 {
 685         struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
 686         struct gfs2_glock *gl, *tmp;
 687         unsigned int hash = gl_hash(sdp, &name);
 688         int error;
 689
 690         read_lock(gl_lock_addr(hash));
 691         gl = search_bucket(hash, sdp, &name);
 692         read_unlock(gl_lock_addr(hash));
 693
 694         *glp = gl;
 695         if (gl)
 696                 return 0;
 697         if (!create)
 698                 return -ENOENT;
 699
 700         gl = kmem_cache_alloc(gfs2_glock_cachep, GFP_KERNEL);
 701         if (!gl)
 702                 return -ENOMEM;
 703
 704         gl->gl_flags = 0;
 705         gl->gl_name = name;
 706         atomic_set(&gl->gl_ref, 1);
 707         gl->gl_state = LM_ST_UNLOCKED;
 708         gl->gl_target = LM_ST_UNLOCKED;
 709         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 710         gl->gl_hash = hash;
 711         gl->gl_ops = glops;
 712         snprintf(gl->gl_strname, GDLM_STRNAME_BYTES, "%8x%16llx", name.ln_type, (unsigned long long)number);
 713         memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
 714         gl->gl_lksb.sb_lvbptr = gl->gl_lvb;
 715         gl->gl_tchange = jiffies;
 716         gl->gl_object = NULL;
 717         gl->gl_sbd = sdp;
 718         gl->gl_aspace = NULL;
 719         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
 720
 721         /* If this glock protects actual on-disk data or metadata blocks,
 722            create a VFS inode to manage the pages/buffers holding them. */
 723         if (glops == &gfs2_inode_glops || glops == &gfs2_rgrp_glops) {
 724                 gl->gl_aspace = gfs2_aspace_get(sdp);
 725                 if (!gl->gl_aspace) {
 726                         error = -ENOMEM;
 727                         goto fail;
 728                 }
 729         }
 730
 731         write_lock(gl_lock_addr(hash));
 732         tmp = search_bucket(hash, sdp, &name);
 733         if (tmp) {
 734                 write_unlock(gl_lock_addr(hash));
 735                 glock_free(gl);
 736                 gl = tmp;
 737         } else {
 738                 hlist_add_head(&gl->gl_list, &gl_hash_table[hash].hb_list);
 739                 write_unlock(gl_lock_addr(hash));
 740         }
 741
 742         *glp = gl;
 743
 744         return 0;
 745
 746 fail:
 747         kmem_cache_free(gfs2_glock_cachep, gl);
 748         return error;
 749 }
 750
 751 /**
 752  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
 753  * @gl: the glock
 754  * @state: the state we're requesting
 755  * @flags: the modifier flags
 756  * @gh: the holder structure
 757  *
 758  */
 759
 760 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
 761                       struct gfs2_holder *gh)
 762 {
 763         INIT_LIST_HEAD(&gh->gh_list);
 764         gh->gh_gl = gl;
 765         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 766         gh->gh_owner_pid = get_pid(task_pid(current));
 767         gh->gh_state = state;
 768         gh->gh_flags = flags;
 769         gh->gh_error = 0;
 770         gh->gh_iflags = 0;
 771         gfs2_glock_hold(gl);
 772 }
 773
 774 /**
 775  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
 776  * @state: the state we're requesting
 777  * @flags: the modifier flags
 778  * @gh: the holder structure
 779  *
 780  * Don't mess with the glock.
 781  *
 782  */
 783
 784 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
 785 {
 786         gh->gh_state = state;
 787         gh->gh_flags = flags;
 788         gh->gh_iflags = 0;
 789         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 790 }
 791
 792 /**
 793  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 794  * @gh: the holder structure
 795  *
 796  */
 797
 798 void gfs2_holder_uninit(struct gfs2_holder *gh)
 799 {
 800         put_pid(gh->gh_owner_pid);
 801         gfs2_glock_put(gh->gh_gl);
 802         gh->gh_gl = NULL;
 803         gh->gh_ip = 0;
 804 }
 805
 806 /**
 807  * gfs2_glock_holder_wait
 808  * @word: unused
 809  *
 810  * This function and gfs2_glock_demote_wait both show up in the WCHAN
 811  * field. Thus I've separated these otherwise identical functions in
 812  * order to be more informative to the user.
 813  */
 814
 815 static int gfs2_glock_holder_wait(void *word)
 816 {
 817         schedule();
 818         return 0;
 819 }
 820
 821 static int gfs2_glock_demote_wait(void *word)
 822 {
 823         schedule();
 824         return 0;
 825 }
 826
 827 static void wait_on_holder(struct gfs2_holder *gh)
 828 {
 829         might_sleep();
 830         wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
 831 }
 832
 833 static void wait_on_demote(struct gfs2_glock *gl)
 834 {
 835         might_sleep();
 836         wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
 837 }
 838
 839 /**
 840  * handle_callback - process a demote request
 841  * @gl: the glock
 842  * @state: the state the caller wants us to change to
 843  *
 844  * There are only two requests that we are going to see in actual
 845  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
 846  */
 847
 848 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
 849                             unsigned long delay)
 850 {
 851         int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
 852
 853         set_bit(bit, &gl->gl_flags);
 854         if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
 855                 gl->gl_demote_state = state;
 856                 gl->gl_demote_time = jiffies;
 857         } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
 858                         gl->gl_demote_state != state) {
 859                 gl->gl_demote_state = LM_ST_UNLOCKED;
 860         }
 861         trace_gfs2_demote_rq(gl);
 862 }
 863
 864 /**
 865  * gfs2_glock_wait - wait on a glock acquisition
 866  * @gh: the glock holder
 867  *
 868  * Returns: 0 on success
 869  */
 870
 871 int gfs2_glock_wait(struct gfs2_holder *gh)
 872 {
 873         wait_on_holder(gh);
 874         return gh->gh_error;
 875 }
 876
 877 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
 878 {
 879         va_list args;
 880
 881         va_start(args, fmt);
 882         if (seq) {
 883                 struct gfs2_glock_iter *gi = seq->private;
 884                 vsprintf(gi->string, fmt, args);
 885                 seq_printf(seq, gi->string);
 886         } else {
 887                 printk(KERN_ERR " ");
 888                 vprintk(fmt, args);
 889         }
 890         va_end(args);
 891 }
 892
 893 /**
 894  * add_to_queue - Add a holder to the wait queue (but look for recursion)
 895  * @gh: the holder structure to add
 896  *
 897  * Eventually we should move the recursive locking trap to a
 898  * debugging option or something like that. This is the fast
 899  * path and needs to have the minimum number of distractions.
 900  *
 901  */
 902
 903 static inline void add_to_queue(struct gfs2_holder *gh)
 904 __releases(&gl->gl_spin)
 905 __acquires(&gl->gl_spin)
 906 {
 907         struct gfs2_glock *gl = gh->gh_gl;
 908         struct gfs2_sbd *sdp = gl->gl_sbd;
 909         struct list_head *insert_pt = NULL;
 910         struct gfs2_holder *gh2;
 911         int try_lock = 0;
 912
 913         BUG_ON(gh->gh_owner_pid == NULL);
 914         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
 915                 BUG();
 916
 917         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
 918                 if (test_bit(GLF_LOCK, &gl->gl_flags))
 919                         try_lock = 1;
 920                 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 921                         goto fail;
 922         }
 923
 924         list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
 925                 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
 926                     (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
 927                         goto trap_recursive;
 928                 if (try_lock &&
 929                     !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
 930                     !may_grant(gl, gh)) {
 931 fail:
 932                         gh->gh_error = GLR_TRYFAILED;
 933                         gfs2_holder_wake(gh);
 934                         return;
 935                 }
 936                 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
 937                         continue;
 938                 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
 939                         insert_pt = &gh2->gh_list;
 940         }
 941         if (likely(insert_pt == NULL)) {
 942                 list_add_tail(&gh->gh_list, &gl->gl_holders);
 943                 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
 944                         goto do_cancel;
 945                 return;
 946         }
 947         trace_gfs2_glock_queue(gh, 1);
 948         list_add_tail(&gh->gh_list, insert_pt);
 949 do_cancel:
 950         gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 951         if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
 952                 spin_unlock(&gl->gl_spin);
 953                 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
 954                         sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
 955                 spin_lock(&gl->gl_spin);
 956         }
 957         return;
 958
 959 trap_recursive:
 960         print_symbol(KERN_ERR "original: %s\n", gh2->gh_ip);
 961         printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
 962         printk(KERN_ERR "lock type: %d req lock state : %d\n",
 963                gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
 964         print_symbol(KERN_ERR "new: %s\n", gh->gh_ip);
 965         printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
 966         printk(KERN_ERR "lock type: %d req lock state : %d\n",
 967                gh->gh_gl->gl_name.ln_type, gh->gh_state);
 968         __dump_glock(NULL, gl);
 969         BUG();
 970 }
 971
 972 /**
 973  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
 974  * @gh: the holder structure
 975  *
 976  * if (gh->gh_flags & GL_ASYNC), this never returns an error
 977  *
 978  * Returns: 0, GLR_TRYFAILED, or errno on failure
 979  */
 980
 981 int gfs2_glock_nq(struct gfs2_holder *gh)
 982 {
 983         struct gfs2_glock *gl = gh->gh_gl;
 984         struct gfs2_sbd *sdp = gl->gl_sbd;
 985         int error = 0;
 986
 987         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 988                 return -EIO;
 989
 990         spin_lock(&gl->gl_spin);
 991         add_to_queue(gh);
 992         run_queue(gl, 1);
 993         spin_unlock(&gl->gl_spin);
 994
 995         if (!(gh->gh_flags & GL_ASYNC))
 996                 error = gfs2_glock_wait(gh);
 997
 998         return error;
 999 }
1000
1001 /**
1002  * gfs2_glock_poll - poll to see if an async request has been completed
1003  * @gh: the holder
1004  *
1005  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1006  */
1007
1008 int gfs2_glock_poll(struct gfs2_holder *gh)
1009 {
1010         return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1011 }
1012
1013 /**
1014  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1015  * @gh: the glock holder
1016  *
1017  */
1018
1019 void gfs2_glock_dq(struct gfs2_holder *gh)
1020 {
1021         struct gfs2_glock *gl = gh->gh_gl;
1022         const struct gfs2_glock_operations *glops = gl->gl_ops;
1023         unsigned delay = 0;
1024         int fast_path = 0;
1025
1026         spin_lock(&gl->gl_spin);
1027         if (gh->gh_flags & GL_NOCACHE)
1028                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1029
1030         list_del_init(&gh->gh_list);
1031         if (find_first_holder(gl) == NULL) {
1032                 if (glops->go_unlock) {
1033                         GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1034                         spin_unlock(&gl->gl_spin);
1035                         glops->go_unlock(gh);
1036                         spin_lock(&gl->gl_spin);
1037                         clear_bit(GLF_LOCK, &gl->gl_flags);
1038                 }
1039                 if (list_empty(&gl->gl_holders) &&
1040                     !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1041                     !test_bit(GLF_DEMOTE, &gl->gl_flags))
1042                         fast_path = 1;
1043         }
1044         trace_gfs2_glock_queue(gh, 0);
1045         spin_unlock(&gl->gl_spin);
1046         if (likely(fast_path))
1047                 return;
1048
1049         gfs2_glock_hold(gl);
1050         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1051             !test_bit(GLF_DEMOTE, &gl->gl_flags))
1052                 delay = gl->gl_ops->go_min_hold_time;
1053         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1054                 gfs2_glock_put(gl);
1055 }
1056
1057 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1058 {
1059         struct gfs2_glock *gl = gh->gh_gl;
1060         gfs2_glock_dq(gh);
1061         wait_on_demote(gl);
1062 }
1063
1064 /**
1065  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1066  * @gh: the holder structure
1067  *
1068  */
1069
1070 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1071 {
1072         gfs2_glock_dq(gh);
1073         gfs2_holder_uninit(gh);
1074 }
1075
1076 /**
1077  * gfs2_glock_nq_num - acquire a glock based on lock number
1078  * @sdp: the filesystem
1079  * @number: the lock number
1080  * @glops: the glock operations for the type of glock
1081  * @state: the state to acquire the glock in
1082  * @flags: modifier flags for the aquisition
1083  * @gh: the struct gfs2_holder
1084  *
1085  * Returns: errno
1086  */
1087
1088 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1089                       const struct gfs2_glock_operations *glops,
1090                       unsigned int state, int flags, struct gfs2_holder *gh)
1091 {
1092         struct gfs2_glock *gl;
1093         int error;
1094
1095         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1096         if (!error) {
1097                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1098                 gfs2_glock_put(gl);
1099         }
1100
1101         return error;
1102 }
1103
1104 /**
1105  * glock_compare - Compare two struct gfs2_glock structures for sorting
1106  * @arg_a: the first structure
1107  * @arg_b: the second structure
1108  *
1109  */
1110
1111 static int glock_compare(const void *arg_a, const void *arg_b)
1112 {
1113         const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1114         const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1115         const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1116         const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1117
1118         if (a->ln_number > b->ln_number)
1119                 return 1;
1120         if (a->ln_number < b->ln_number)
1121                 return -1;
1122         BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1123         return 0;
1124 }
1125
1126 /**
1127  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1128  * @num_gh: the number of structures
1129  * @ghs: an array of struct gfs2_holder structures
1130  *
1131  * Returns: 0 on success (all glocks acquired),
1132  *          errno on failure (no glocks acquired)
1133  */
1134
1135 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1136                      struct gfs2_holder **p)
1137 {
1138         unsigned int x;
1139         int error = 0;
1140
1141         for (x = 0; x < num_gh; x++)
1142                 p[x] = &ghs[x];
1143
1144         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1145
1146         for (x = 0; x < num_gh; x++) {
1147                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1148
1149                 error = gfs2_glock_nq(p[x]);
1150                 if (error) {
1151                         while (x--)
1152                                 gfs2_glock_dq(p[x]);
1153                         break;
1154                 }
1155         }
1156
1157         return error;
1158 }
1159
1160 /**
1161  * gfs2_glock_nq_m - acquire multiple glocks
1162  * @num_gh: the number of structures
1163  * @ghs: an array of struct gfs2_holder structures
1164  *
1165  *
1166  * Returns: 0 on success (all glocks acquired),
1167  *          errno on failure (no glocks acquired)
1168  */
1169
1170 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1171 {
1172         struct gfs2_holder *tmp[4];
1173         struct gfs2_holder **pph = tmp;
1174         int error = 0;
1175
1176         switch(num_gh) {
1177         case 0:
1178                 return 0;
1179         case 1:
1180                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1181                 return gfs2_glock_nq(ghs);
1182         default:
1183                 if (num_gh <= 4)
1184                         break;
1185                 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1186                 if (!pph)
1187                         return -ENOMEM;
1188         }
1189
1190         error = nq_m_sync(num_gh, ghs, pph);
1191
1192         if (pph != tmp)
1193                 kfree(pph);
1194
1195         return error;
1196 }
1197
1198 /**
1199  * gfs2_glock_dq_m - release multiple glocks
1200  * @num_gh: the number of structures
1201  * @ghs: an array of struct gfs2_holder structures
1202  *
1203  */
1204
1205 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1206 {
1207         unsigned int x;
1208
1209         for (x = 0; x < num_gh; x++)
1210                 gfs2_glock_dq(&ghs[x]);
1211 }
1212
1213 /**
1214  * gfs2_glock_dq_uninit_m - release multiple glocks
1215  * @num_gh: the number of structures
1216  * @ghs: an array of struct gfs2_holder structures
1217  *
1218  */
1219
1220 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1221 {
1222         unsigned int x;
1223
1224         for (x = 0; x < num_gh; x++)
1225                 gfs2_glock_dq_uninit(&ghs[x]);
1226 }
1227
1228 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1229 {
1230         unsigned long delay = 0;
1231         unsigned long holdtime;
1232         unsigned long now = jiffies;
1233
1234         gfs2_glock_hold(gl);
1235         holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
1236         if (time_before(now, holdtime))
1237                 delay = holdtime - now;
1238         if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1239                 delay = gl->gl_ops->go_min_hold_time;
1240
1241         spin_lock(&gl->gl_spin);
1242         handle_callback(gl, state, delay);
1243         spin_unlock(&gl->gl_spin);
1244         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1245                 gfs2_glock_put(gl);
1246 }
1247
1248 /**
1249  * gfs2_glock_complete - Callback used by locking
1250  * @gl: Pointer to the glock
1251  * @ret: The return value from the dlm
1252  *
1253  */
1254
1255 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1256 {
1257         struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
1258         gl->gl_reply = ret;
1259         if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_flags))) {
1260                 struct gfs2_holder *gh;
1261                 spin_lock(&gl->gl_spin);
1262                 gh = find_first_waiter(gl);
1263                 if ((!(gh && (gh->gh_flags & LM_FLAG_NOEXP)) &&
1264                      (gl->gl_target != LM_ST_UNLOCKED)) ||
1265                     ((ret & ~LM_OUT_ST_MASK) != 0))
1266                         set_bit(GLF_FROZEN, &gl->gl_flags);
1267                 spin_unlock(&gl->gl_spin);
1268                 if (test_bit(GLF_FROZEN, &gl->gl_flags))
1269                         return;
1270         }
1271         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1272         gfs2_glock_hold(gl);
1273         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1274                 gfs2_glock_put(gl);
1275 }
1276
1277 /**
1278  * demote_ok - Check to see if it's ok to unlock a glock
1279  * @gl: the glock
1280  *
1281  * Returns: 1 if it's ok
1282  */
1283
1284 static int demote_ok(const struct gfs2_glock *gl)
1285 {
1286         const struct gfs2_glock_operations *glops = gl->gl_ops;
1287
1288         if (gl->gl_state == LM_ST_UNLOCKED)
1289                 return 0;
1290         if (!list_empty(&gl->gl_holders))
1291                 return 0;
1292         if (glops->go_demote_ok)
1293                 return glops->go_demote_ok(gl);
1294         return 1;
1295 }
1296
1297
1298 static int gfs2_shrink_glock_memory(int nr, gfp_t gfp_mask)
1299 {
1300         struct gfs2_glock *gl;
1301         int may_demote;
1302         int nr_skipped = 0;
1303         int got_ref = 0;
1304         LIST_HEAD(skipped);
1305
1306         if (nr == 0)
1307                 goto out;
1308
1309         if (!(gfp_mask & __GFP_FS))
1310                 return -1;
1311
1312         spin_lock(&lru_lock);
1313         while(nr && !list_empty(&lru_list)) {
1314                 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1315                 list_del_init(&gl->gl_lru);
1316                 atomic_dec(&lru_count);
1317
1318                 /* Test for being demotable */
1319                 if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1320                         gfs2_glock_hold(gl);
1321                         got_ref = 1;
1322                         spin_unlock(&lru_lock);
1323                         spin_lock(&gl->gl_spin);
1324                         may_demote = demote_ok(gl);
1325                         spin_unlock(&gl->gl_spin);
1326                         clear_bit(GLF_LOCK, &gl->gl_flags);
1327                         if (may_demote) {
1328                                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1329                                 nr--;
1330                                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1331                                         gfs2_glock_put(gl);
1332                                 got_ref = 0;
1333                         }
1334                         spin_lock(&lru_lock);
1335                         if (may_demote)
1336                                 continue;
1337                 }
1338                 if (list_empty(&gl->gl_lru) &&
1339                     (atomic_read(&gl->gl_ref) <= (2 + got_ref))) {
1340                         nr_skipped++;
1341                         list_add(&gl->gl_lru, &skipped);
1342                 }
1343                 if (got_ref) {
1344                         spin_unlock(&lru_lock);
1345                         gfs2_glock_put(gl);
1346                         spin_lock(&lru_lock);
1347                         got_ref = 0;
1348                 }
1349         }
1350         list_splice(&skipped, &lru_list);
1351         atomic_add(nr_skipped, &lru_count);
1352         spin_unlock(&lru_lock);
1353 out:
1354         return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
1355 }
1356
1357 static struct shrinker glock_shrinker = {
1358         .shrink = gfs2_shrink_glock_memory,
1359         .seeks = DEFAULT_SEEKS,
1360 };
1361
1362 /**
1363  * examine_bucket - Call a function for glock in a hash bucket
1364  * @examiner: the function
1365  * @sdp: the filesystem
1366  * @bucket: the bucket
1367  *
1368  * Returns: 1 if the bucket has entries
1369  */
1370
1371 static int examine_bucket(glock_examiner examiner, struct gfs2_sbd *sdp,
1372                           unsigned int hash)
1373 {
1374         struct gfs2_glock *gl, *prev = NULL;
1375         int has_entries = 0;
1376         struct hlist_head *head = &gl_hash_table[hash].hb_list;
1377
1378         read_lock(gl_lock_addr(hash));
1379         /* Can't use hlist_for_each_entry - don't want prefetch here */
1380         if (hlist_empty(head))
1381                 goto out;
1382         gl = list_entry(head->first, struct gfs2_glock, gl_list);
1383         while(1) {
1384                 if (!sdp || gl->gl_sbd == sdp) {
1385                         gfs2_glock_hold(gl);
1386                         read_unlock(gl_lock_addr(hash));
1387                         if (prev)
1388                                 gfs2_glock_put(prev);
1389                         prev = gl;
1390                         examiner(gl);
1391                         has_entries = 1;
1392                         read_lock(gl_lock_addr(hash));
1393                 }
1394                 if (gl->gl_list.next == NULL)
1395                         break;
1396                 gl = list_entry(gl->gl_list.next, struct gfs2_glock, gl_list);
1397         }
1398 out:
1399         read_unlock(gl_lock_addr(hash));
1400         if (prev)
1401                 gfs2_glock_put(prev);
1402         cond_resched();
1403         return has_entries;
1404 }
1405
1406
1407 /**
1408  * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1409  * @gl: The glock to thaw
1410  *
1411  * N.B. When we freeze a glock, we leave a ref to the glock outstanding,
1412  * so this has to result in the ref count being dropped by one.
1413  */
1414
1415 static void thaw_glock(struct gfs2_glock *gl)
1416 {
1417         if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1418                 return;
1419         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1420         gfs2_glock_hold(gl);
1421         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1422                 gfs2_glock_put(gl);
1423 }
1424
1425 /**
1426  * clear_glock - look at a glock and see if we can free it from glock cache
1427  * @gl: the glock to look at
1428  *
1429  */
1430
1431 static void clear_glock(struct gfs2_glock *gl)
1432 {
1433         spin_lock(&lru_lock);
1434         if (!list_empty(&gl->gl_lru)) {
1435                 list_del_init(&gl->gl_lru);
1436                 atomic_dec(&lru_count);
1437         }
1438         spin_unlock(&lru_lock);
1439
1440         spin_lock(&gl->gl_spin);
1441         if (find_first_holder(gl) == NULL && gl->gl_state != LM_ST_UNLOCKED)
1442                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1443         spin_unlock(&gl->gl_spin);
1444         gfs2_glock_hold(gl);
1445         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1446                 gfs2_glock_put(gl);
1447 }
1448
1449 /**
1450  * gfs2_glock_thaw - Thaw any frozen glocks
1451  * @sdp: The super block
1452  *
1453  */
1454
1455 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1456 {
1457         unsigned x;
1458
1459         for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1460                 examine_bucket(thaw_glock, sdp, x);
1461 }
1462
1463 /**
1464  * gfs2_gl_hash_clear - Empty out the glock hash table
1465  * @sdp: the filesystem
1466  * @wait: wait until it's all gone
1467  *
1468  * Called when unmounting the filesystem.
1469  */
1470
1471 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1472 {
1473         unsigned long t;
1474         unsigned int x;
1475         int cont;
1476
1477         t = jiffies;
1478
1479         for (;;) {
1480                 cont = 0;
1481                 for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
1482                         if (examine_bucket(clear_glock, sdp, x))
1483                                 cont = 1;
1484                 }
1485
1486                 if (!cont)
1487                         break;
1488
1489                 if (time_after_eq(jiffies,
1490                                   t + gfs2_tune_get(sdp, gt_stall_secs) * HZ)) {
1491                         fs_warn(sdp, "Unmount seems to be stalled. "
1492                                      "Dumping lock state...\n");
1493                         gfs2_dump_lockstate(sdp);
1494                         t = jiffies;
1495                 }
1496
1497                 down_write(&gfs2_umount_flush_sem);
1498                 invalidate_inodes(sdp->sd_vfs);
1499                 up_write(&gfs2_umount_flush_sem);
1500                 msleep(10);
1501         }
1502 }
1503
1504 void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1505 {
1506         struct gfs2_glock *gl = ip->i_gl;
1507         int ret;
1508
1509         ret = gfs2_truncatei_resume(ip);
1510         gfs2_assert_withdraw(gl->gl_sbd, ret == 0);
1511
1512         spin_lock(&gl->gl_spin);
1513         clear_bit(GLF_LOCK, &gl->gl_flags);
1514         run_queue(gl, 1);
1515         spin_unlock(&gl->gl_spin);
1516 }
1517
1518 static const char *state2str(unsigned state)
1519 {
1520         switch(state) {
1521         case LM_ST_UNLOCKED:
1522                 return "UN";
1523         case LM_ST_SHARED:
1524                 return "SH";
1525         case LM_ST_DEFERRED:
1526                 return "DF";
1527         case LM_ST_EXCLUSIVE:
1528                 return "EX";
1529         }
1530         return "??";
1531 }
1532
1533 static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags)
1534 {
1535         char *p = buf;
1536         if (flags & LM_FLAG_TRY)
1537                 *p++ = 't';
1538         if (flags & LM_FLAG_TRY_1CB)
1539                 *p++ = 'T';
1540         if (flags & LM_FLAG_NOEXP)
1541                 *p++ = 'e';
1542         if (flags & LM_FLAG_ANY)
1543                 *p++ = 'A';
1544         if (flags & LM_FLAG_PRIORITY)
1545                 *p++ = 'p';
1546         if (flags & GL_ASYNC)
1547                 *p++ = 'a';
1548         if (flags & GL_EXACT)
1549                 *p++ = 'E';
1550         if (flags & GL_NOCACHE)
1551                 *p++ = 'c';
1552         if (test_bit(HIF_HOLDER, &iflags))
1553                 *p++ = 'H';
1554         if (test_bit(HIF_WAIT, &iflags))
1555                 *p++ = 'W';
1556         if (test_bit(HIF_FIRST, &iflags))
1557                 *p++ = 'F';
1558         *p = 0;
1559         return buf;
1560 }
1561
1562 /**
1563  * dump_holder - print information about a glock holder
1564  * @seq: the seq_file struct
1565  * @gh: the glock holder
1566  *
1567  * Returns: 0 on success, -ENOBUFS when we run out of space
1568  */
1569
1570 static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1571 {
1572         struct task_struct *gh_owner = NULL;
1573         char buffer[KSYM_SYMBOL_LEN];
1574         char flags_buf[32];
1575
1576         sprint_symbol(buffer, gh->gh_ip);
1577         if (gh->gh_owner_pid)
1578                 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1579         gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %s\n",
1580                   state2str(gh->gh_state),
1581                   hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1582                   gh->gh_error,
1583                   gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1584                   gh_owner ? gh_owner->comm : "(ended)", buffer);
1585         return 0;
1586 }
1587
1588 static const char *gflags2str(char *buf, const unsigned long *gflags)
1589 {
1590         char *p = buf;
1591         if (test_bit(GLF_LOCK, gflags))
1592                 *p++ = 'l';
1593         if (test_bit(GLF_DEMOTE, gflags))
1594                 *p++ = 'D';
1595         if (test_bit(GLF_PENDING_DEMOTE, gflags))
1596                 *p++ = 'd';
1597         if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1598                 *p++ = 'p';
1599         if (test_bit(GLF_DIRTY, gflags))
1600                 *p++ = 'y';
1601         if (test_bit(GLF_LFLUSH, gflags))
1602                 *p++ = 'f';
1603         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1604                 *p++ = 'i';
1605         if (test_bit(GLF_REPLY_PENDING, gflags))
1606                 *p++ = 'r';
1607         if (test_bit(GLF_INITIAL, gflags))
1608                 *p++ = 'I';
1609         if (test_bit(GLF_FROZEN, gflags))
1610                 *p++ = 'F';
1611         *p = 0;
1612         return buf;
1613 }
1614
1615 /**
1616  * __dump_glock - print information about a glock
1617  * @seq: The seq_file struct
1618  * @gl: the glock
1619  *
1620  * The file format is as follows:
1621  * One line per object, capital letters are used to indicate objects
1622  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1623  * other objects are indented by a single space and follow the glock to
1624  * which they are related. Fields are indicated by lower case letters
1625  * followed by a colon and the field value, except for strings which are in
1626  * [] so that its possible to see if they are composed of spaces for
1627  * example. The field's are n = number (id of the object), f = flags,
1628  * t = type, s = state, r = refcount, e = error, p = pid.
1629  *
1630  * Returns: 0 on success, -ENOBUFS when we run out of space
1631  */
1632
1633 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1634 {
1635         const struct gfs2_glock_operations *glops = gl->gl_ops;
1636         unsigned long long dtime;
1637         const struct gfs2_holder *gh;
1638         char gflags_buf[32];
1639         int error = 0;
1640
1641         dtime = jiffies - gl->gl_demote_time;
1642         dtime *= 1000000/HZ; /* demote time in uSec */
1643         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1644                 dtime = 0;
1645         gfs2_print_dbg(seq, "G:  s:%s n:%u/%llu f:%s t:%s d:%s/%llu a:%d r:%d\n",
1646                   state2str(gl->gl_state),
1647                   gl->gl_name.ln_type,
1648                   (unsigned long long)gl->gl_name.ln_number,
1649                   gflags2str(gflags_buf, &gl->gl_flags),
1650                   state2str(gl->gl_target),
1651                   state2str(gl->gl_demote_state), dtime,
1652                   atomic_read(&gl->gl_ail_count),
1653                   atomic_read(&gl->gl_ref));
1654
1655         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1656                 error = dump_holder(seq, gh);
1657                 if (error)
1658                         goto out;
1659         }
1660         if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1661                 error = glops->go_dump(seq, gl);
1662 out:
1663         return error;
1664 }
1665
1666 static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1667 {
1668         int ret;
1669         spin_lock(&gl->gl_spin);
1670         ret = __dump_glock(seq, gl);
1671         spin_unlock(&gl->gl_spin);
1672         return ret;
1673 }
1674
1675 /**
1676  * gfs2_dump_lockstate - print out the current lockstate
1677  * @sdp: the filesystem
1678  * @ub: the buffer to copy the information into
1679  *
1680  * If @ub is NULL, dump the lockstate to the console.
1681  *
1682  */
1683
1684 static int gfs2_dump_lockstate(struct gfs2_sbd *sdp)
1685 {
1686         struct gfs2_glock *gl;
1687         struct hlist_node *h;
1688         unsigned int x;
1689         int error = 0;
1690
1691         for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
1692
1693                 read_lock(gl_lock_addr(x));
1694
1695                 hlist_for_each_entry(gl, h, &gl_hash_table[x].hb_list, gl_list) {
1696                         if (gl->gl_sbd != sdp)
1697                                 continue;
1698
1699                         error = dump_glock(NULL, gl);
1700                         if (error)
1701                                 break;
1702                 }
1703
1704                 read_unlock(gl_lock_addr(x));
1705
1706                 if (error)
1707                         break;
1708         }
1709
1710
1711         return error;
1712 }
1713
1714
1715 int __init gfs2_glock_init(void)
1716 {
1717         unsigned i;
1718         for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
1719                 INIT_HLIST_HEAD(&gl_hash_table[i].hb_list);
1720         }
1721 #ifdef GL_HASH_LOCK_SZ
1722         for(i = 0; i < GL_HASH_LOCK_SZ; i++) {
1723                 rwlock_init(&gl_hash_locks[i]);
1724         }
1725 #endif
1726
1727         glock_workqueue = create_workqueue("glock_workqueue");
1728         if (IS_ERR(glock_workqueue))
1729                 return PTR_ERR(glock_workqueue);
1730
1731         register_shrinker(&glock_shrinker);
1732
1733         return 0;
1734 }
1735
1736 void gfs2_glock_exit(void)
1737 {
1738         unregister_shrinker(&glock_shrinker);
1739         destroy_workqueue(glock_workqueue);
1740 }
1741
1742 static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1743 {
1744         struct gfs2_glock *gl;
1745
1746 restart:
1747         read_lock(gl_lock_addr(gi->hash));
1748         gl = gi->gl;
1749         if (gl) {
1750                 gi->gl = hlist_entry(gl->gl_list.next,
1751                                      struct gfs2_glock, gl_list);
1752         } else {
1753                 gi->gl = hlist_entry(gl_hash_table[gi->hash].hb_list.first,
1754                                      struct gfs2_glock, gl_list);
1755         }
1756         if (gi->gl)
1757                 gfs2_glock_hold(gi->gl);
1758         read_unlock(gl_lock_addr(gi->hash));
1759         if (gl)
1760                 gfs2_glock_put(gl);
1761         while (gi->gl == NULL) {
1762                 gi->hash++;
1763                 if (gi->hash >= GFS2_GL_HASH_SIZE)
1764                         return 1;
1765                 read_lock(gl_lock_addr(gi->hash));
1766                 gi->gl = hlist_entry(gl_hash_table[gi->hash].hb_list.first,
1767                                      struct gfs2_glock, gl_list);
1768                 if (gi->gl)
1769                         gfs2_glock_hold(gi->gl);
1770                 read_unlock(gl_lock_addr(gi->hash));
1771         }
1772
1773         if (gi->sdp != gi->gl->gl_sbd)
1774                 goto restart;
1775
1776         return 0;
1777 }
1778
1779 static void gfs2_glock_iter_free(struct gfs2_glock_iter *gi)
1780 {
1781         if (gi->gl)
1782                 gfs2_glock_put(gi->gl);
1783         gi->gl = NULL;
1784 }
1785
1786 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1787 {
1788         struct gfs2_glock_iter *gi = seq->private;
1789         loff_t n = *pos;
1790
1791         gi->hash = 0;
1792
1793         do {
1794                 if (gfs2_glock_iter_next(gi)) {
1795                         gfs2_glock_iter_free(gi);
1796                         return NULL;
1797                 }
1798         } while (n--);
1799
1800         return gi->gl;
1801 }
1802
1803 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1804                                  loff_t *pos)
1805 {
1806         struct gfs2_glock_iter *gi = seq->private;
1807
1808         (*pos)++;
1809
1810         if (gfs2_glock_iter_next(gi)) {
1811                 gfs2_glock_iter_free(gi);
1812                 return NULL;
1813         }
1814
1815         return gi->gl;
1816 }
1817
1818 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1819 {
1820         struct gfs2_glock_iter *gi = seq->private;
1821         gfs2_glock_iter_free(gi);
1822 }
1823
1824 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1825 {
1826         return dump_glock(seq, iter_ptr);
1827 }
1828
1829 static const struct seq_operations gfs2_glock_seq_ops = {
1830         .start = gfs2_glock_seq_start,
1831         .next  = gfs2_glock_seq_next,
1832         .stop  = gfs2_glock_seq_stop,
1833         .show  = gfs2_glock_seq_show,
1834 };
1835
1836 static int gfs2_debugfs_open(struct inode *inode, struct file *file)
1837 {
1838         int ret = seq_open_private(file, &gfs2_glock_seq_ops,
1839                                    sizeof(struct gfs2_glock_iter));
1840         if (ret == 0) {
1841                 struct seq_file *seq = file->private_data;
1842                 struct gfs2_glock_iter *gi = seq->private;
1843                 gi->sdp = inode->i_private;
1844         }
1845         return ret;
1846 }
1847
1848 static const struct file_operations gfs2_debug_fops = {
1849         .owner   = THIS_MODULE,
1850         .open    = gfs2_debugfs_open,
1851         .read    = seq_read,
1852         .llseek  = seq_lseek,
1853         .release = seq_release_private,
1854 };
1855
1856 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
1857 {
1858         sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
1859         if (!sdp->debugfs_dir)
1860                 return -ENOMEM;
1861         sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
1862                                                          S_IFREG | S_IRUGO,
1863                                                          sdp->debugfs_dir, sdp,
1864                                                          &gfs2_debug_fops);
1865         if (!sdp->debugfs_dentry_glocks)
1866                 return -ENOMEM;
1867
1868         return 0;
1869 }
1870
1871 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
1872 {
1873         if (sdp && sdp->debugfs_dir) {
1874                 if (sdp->debugfs_dentry_glocks) {
1875                         debugfs_remove(sdp->debugfs_dentry_glocks);
1876                         sdp->debugfs_dentry_glocks = NULL;
1877                 }
1878                 debugfs_remove(sdp->debugfs_dir);
1879                 sdp->debugfs_dir = NULL;
1880         }
1881 }
1882
1883 int gfs2_register_debugfs(void)
1884 {
1885         gfs2_root = debugfs_create_dir("gfs2", NULL);
1886         return gfs2_root ? 0 : -ENOMEM;
1887 }
1888
1889 void gfs2_unregister_debugfs(void)
1890 {
1891         debugfs_remove(gfs2_root);
1892         gfs2_root = NULL;
1893 }