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 struct workqueue_struct *gfs2_delete_workqueue;
  67 static LIST_HEAD(lru_list);
  68 static atomic_t lru_count = ATOMIC_INIT(0);
  69 static DEFINE_SPINLOCK(lru_lock);
  70
  71 #define GFS2_GL_HASH_SHIFT      15
  72 #define GFS2_GL_HASH_SIZE       (1 << GFS2_GL_HASH_SHIFT)
  73 #define GFS2_GL_HASH_MASK       (GFS2_GL_HASH_SIZE - 1)
  74
  75 static struct gfs2_gl_hash_bucket gl_hash_table[GFS2_GL_HASH_SIZE];
  76 static struct dentry *gfs2_root;
  77
  78 /*
  79  * Despite what you might think, the numbers below are not arbitrary :-)
  80  * They are taken from the ipv4 routing hash code, which is well tested
  81  * and thus should be nearly optimal. Later on we might tweek the numbers
  82  * but for now this should be fine.
  83  *
  84  * The reason for putting the locks in a separate array from the list heads
  85  * is that we can have fewer locks than list heads and save memory. We use
  86  * the same hash function for both, but with a different hash mask.
  87  */
  88 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) || \
  89         defined(CONFIG_PROVE_LOCKING)
  90
  91 #ifdef CONFIG_LOCKDEP
  92 # define GL_HASH_LOCK_SZ        256
  93 #else
  94 # if NR_CPUS >= 32
  95 #  define GL_HASH_LOCK_SZ       4096
  96 # elif NR_CPUS >= 16
  97 #  define GL_HASH_LOCK_SZ       2048
  98 # elif NR_CPUS >= 8
  99 #  define GL_HASH_LOCK_SZ       1024
 100 # elif NR_CPUS >= 4
 101 #  define GL_HASH_LOCK_SZ       512
 102 # else
 103 #  define GL_HASH_LOCK_SZ       256
 104 # endif
 105 #endif
 106
 107 /* We never want more locks than chains */
 108 #if GFS2_GL_HASH_SIZE < GL_HASH_LOCK_SZ
 109 # undef GL_HASH_LOCK_SZ
 110 # define GL_HASH_LOCK_SZ GFS2_GL_HASH_SIZE
 111 #endif
 112
 113 static rwlock_t gl_hash_locks[GL_HASH_LOCK_SZ];
 114
 115 static inline rwlock_t *gl_lock_addr(unsigned int x)
 116 {
 117         return &gl_hash_locks[x & (GL_HASH_LOCK_SZ-1)];
 118 }
 119 #else /* not SMP, so no spinlocks required */
 120 static inline rwlock_t *gl_lock_addr(unsigned int x)
 121 {
 122         return NULL;
 123 }
 124 #endif
 125
 126 /**
 127  * gl_hash() - Turn glock number into hash bucket number
 128  * @lock: The glock number
 129  *
 130  * Returns: The number of the corresponding hash bucket
 131  */
 132
 133 static unsigned int gl_hash(const struct gfs2_sbd *sdp,
 134                             const struct lm_lockname *name)
 135 {
 136         unsigned int h;
 137
 138         h = jhash(&name->ln_number, sizeof(u64), 0);
 139         h = jhash(&name->ln_type, sizeof(unsigned int), h);
 140         h = jhash(&sdp, sizeof(struct gfs2_sbd *), h);
 141         h &= GFS2_GL_HASH_MASK;
 142
 143         return h;
 144 }
 145
 146 /**
 147  * glock_free() - Perform a few checks and then release struct gfs2_glock
 148  * @gl: The glock to release
 149  *
 150  * Also calls lock module to release its internal structure for this glock.
 151  *
 152  */
 153
 154 static void glock_free(struct gfs2_glock *gl)
 155 {
 156         struct gfs2_sbd *sdp = gl->gl_sbd;
 157         struct inode *aspace = gl->gl_aspace;
 158
 159         if (aspace)
 160                 gfs2_aspace_put(aspace);
 161         trace_gfs2_glock_put(gl);
 162         sdp->sd_lockstruct.ls_ops->lm_put_lock(gfs2_glock_cachep, gl);
 163 }
 164
 165 /**
 166  * gfs2_glock_hold() - increment reference count on glock
 167  * @gl: The glock to hold
 168  *
 169  */
 170
 171 void gfs2_glock_hold(struct gfs2_glock *gl)
 172 {
 173         GLOCK_BUG_ON(gl, atomic_read(&gl->gl_ref) == 0);
 174         atomic_inc(&gl->gl_ref);
 175 }
 176
 177 /**
 178  * demote_ok - Check to see if it's ok to unlock a glock
 179  * @gl: the glock
 180  *
 181  * Returns: 1 if it's ok
 182  */
 183
 184 static int demote_ok(const struct gfs2_glock *gl)
 185 {
 186         const struct gfs2_glock_operations *glops = gl->gl_ops;
 187
 188         if (gl->gl_state == LM_ST_UNLOCKED)
 189                 return 0;
 190         if (!list_empty(&gl->gl_holders))
 191                 return 0;
 192         if (glops->go_demote_ok)
 193                 return glops->go_demote_ok(gl);
 194         return 1;
 195 }
 196
 197 /**
 198  * gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
 199  * @gl: the glock
 200  *
 201  */
 202
 203 static void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
 204 {
 205         int may_reclaim;
 206         may_reclaim = (demote_ok(gl) &&
 207                        (atomic_read(&gl->gl_ref) == 1 ||
 208                         (gl->gl_name.ln_type == LM_TYPE_INODE &&
 209                          atomic_read(&gl->gl_ref) <= 2)));
 210         spin_lock(&lru_lock);
 211         if (list_empty(&gl->gl_lru) && may_reclaim) {
 212                 list_add_tail(&gl->gl_lru, &lru_list);
 213                 atomic_inc(&lru_count);
 214         }
 215         spin_unlock(&lru_lock);
 216 }
 217
 218 /**
 219  * gfs2_glock_put_nolock() - Decrement reference count on glock
 220  * @gl: The glock to put
 221  *
 222  * This function should only be used if the caller has its own reference
 223  * to the glock, in addition to the one it is dropping.
 224  */
 225
 226 void gfs2_glock_put_nolock(struct gfs2_glock *gl)
 227 {
 228         if (atomic_dec_and_test(&gl->gl_ref))
 229                 GLOCK_BUG_ON(gl, 1);
 230         gfs2_glock_schedule_for_reclaim(gl);
 231 }
 232
 233 /**
 234  * gfs2_glock_put() - Decrement reference count on glock
 235  * @gl: The glock to put
 236  *
 237  */
 238
 239 int gfs2_glock_put(struct gfs2_glock *gl)
 240 {
 241         int rv = 0;
 242
 243         write_lock(gl_lock_addr(gl->gl_hash));
 244         if (atomic_dec_and_lock(&gl->gl_ref, &lru_lock)) {
 245                 hlist_del(&gl->gl_list);
 246                 if (!list_empty(&gl->gl_lru)) {
 247                         list_del_init(&gl->gl_lru);
 248                         atomic_dec(&lru_count);
 249                 }
 250                 spin_unlock(&lru_lock);
 251                 write_unlock(gl_lock_addr(gl->gl_hash));
 252                 GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
 253                 glock_free(gl);
 254                 rv = 1;
 255                 goto out;
 256         }
 257         spin_lock(&gl->gl_spin);
 258         gfs2_glock_schedule_for_reclaim(gl);
 259         spin_unlock(&gl->gl_spin);
 260         write_unlock(gl_lock_addr(gl->gl_hash));
 261 out:
 262         return rv;
 263 }
 264
 265 /**
 266  * search_bucket() - Find struct gfs2_glock by lock number
 267  * @bucket: the bucket to search
 268  * @name: The lock name
 269  *
 270  * Returns: NULL, or the struct gfs2_glock with the requested number
 271  */
 272
 273 static struct gfs2_glock *search_bucket(unsigned int hash,
 274                                         const struct gfs2_sbd *sdp,
 275                                         const struct lm_lockname *name)
 276 {
 277         struct gfs2_glock *gl;
 278         struct hlist_node *h;
 279
 280         hlist_for_each_entry(gl, h, &gl_hash_table[hash].hb_list, gl_list) {
 281                 if (!lm_name_equal(&gl->gl_name, name))
 282                         continue;
 283                 if (gl->gl_sbd != sdp)
 284                         continue;
 285
 286                 atomic_inc(&gl->gl_ref);
 287
 288                 return gl;
 289         }
 290
 291         return NULL;
 292 }
 293
 294 /**
 295  * may_grant - check if its ok to grant a new lock
 296  * @gl: The glock
 297  * @gh: The lock request which we wish to grant
 298  *
 299  * Returns: true if its ok to grant the lock
 300  */
 301
 302 static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
 303 {
 304         const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
 305         if ((gh->gh_state == LM_ST_EXCLUSIVE ||
 306              gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
 307                 return 0;
 308         if (gl->gl_state == gh->gh_state)
 309                 return 1;
 310         if (gh->gh_flags & GL_EXACT)
 311                 return 0;
 312         if (gl->gl_state == LM_ST_EXCLUSIVE) {
 313                 if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
 314                         return 1;
 315                 if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
 316                         return 1;
 317         }
 318         if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
 319                 return 1;
 320         return 0;
 321 }
 322
 323 static void gfs2_holder_wake(struct gfs2_holder *gh)
 324 {
 325         clear_bit(HIF_WAIT, &gh->gh_iflags);
 326         smp_mb__after_clear_bit();
 327         wake_up_bit(&gh->gh_iflags, HIF_WAIT);
 328 }
 329
 330 /**
 331  * do_promote - promote as many requests as possible on the current queue
 332  * @gl: The glock
 333  *
 334  * Returns: 1 if there is a blocked holder at the head of the list, or 2
 335  *          if a type specific operation is underway.
 336  */
 337
 338 static int do_promote(struct gfs2_glock *gl)
 339 __releases(&gl->gl_spin)
 340 __acquires(&gl->gl_spin)
 341 {
 342         const struct gfs2_glock_operations *glops = gl->gl_ops;
 343         struct gfs2_holder *gh, *tmp;
 344         int ret;
 345
 346 restart:
 347         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 348                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 349                         continue;
 350                 if (may_grant(gl, gh)) {
 351                         if (gh->gh_list.prev == &gl->gl_holders &&
 352                             glops->go_lock) {
 353                                 spin_unlock(&gl->gl_spin);
 354                                 /* FIXME: eliminate this eventually */
 355                                 ret = glops->go_lock(gh);
 356                                 spin_lock(&gl->gl_spin);
 357                                 if (ret) {
 358                                         if (ret == 1)
 359                                                 return 2;
 360                                         gh->gh_error = ret;
 361                                         list_del_init(&gh->gh_list);
 362                                         trace_gfs2_glock_queue(gh, 0);
 363                                         gfs2_holder_wake(gh);
 364                                         goto restart;
 365                                 }
 366                                 set_bit(HIF_HOLDER, &gh->gh_iflags);
 367                                 trace_gfs2_promote(gh, 1);
 368                                 gfs2_holder_wake(gh);
 369                                 goto restart;
 370                         }
 371                         set_bit(HIF_HOLDER, &gh->gh_iflags);
 372                         trace_gfs2_promote(gh, 0);
 373                         gfs2_holder_wake(gh);
 374                         continue;
 375                 }
 376                 if (gh->gh_list.prev == &gl->gl_holders)
 377                         return 1;
 378                 break;
 379         }
 380         return 0;
 381 }
 382
 383 /**
 384  * do_error - Something unexpected has happened during a lock request
 385  *
 386  */
 387
 388 static inline void do_error(struct gfs2_glock *gl, const int ret)
 389 {
 390         struct gfs2_holder *gh, *tmp;
 391
 392         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 393                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 394                         continue;
 395                 if (ret & LM_OUT_ERROR)
 396                         gh->gh_error = -EIO;
 397                 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
 398                         gh->gh_error = GLR_TRYFAILED;
 399                 else
 400                         continue;
 401                 list_del_init(&gh->gh_list);
 402                 trace_gfs2_glock_queue(gh, 0);
 403                 gfs2_holder_wake(gh);
 404         }
 405 }
 406
 407 /**
 408  * find_first_waiter - find the first gh that's waiting for the glock
 409  * @gl: the glock
 410  */
 411
 412 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
 413 {
 414         struct gfs2_holder *gh;
 415
 416         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
 417                 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
 418                         return gh;
 419         }
 420         return NULL;
 421 }
 422
 423 /**
 424  * state_change - record that the glock is now in a different state
 425  * @gl: the glock
 426  * @new_state the new state
 427  *
 428  */
 429
 430 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 431 {
 432         int held1, held2;
 433
 434         held1 = (gl->gl_state != LM_ST_UNLOCKED);
 435         held2 = (new_state != LM_ST_UNLOCKED);
 436
 437         if (held1 != held2) {
 438                 if (held2)
 439                         gfs2_glock_hold(gl);
 440                 else
 441                         gfs2_glock_put_nolock(gl);
 442         }
 443
 444         gl->gl_state = new_state;
 445         gl->gl_tchange = jiffies;
 446 }
 447
 448 static void gfs2_demote_wake(struct gfs2_glock *gl)
 449 {
 450         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 451         clear_bit(GLF_DEMOTE, &gl->gl_flags);
 452         smp_mb__after_clear_bit();
 453         wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
 454 }
 455
 456 /**
 457  * finish_xmote - The DLM has replied to one of our lock requests
 458  * @gl: The glock
 459  * @ret: The status from the DLM
 460  *
 461  */
 462
 463 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
 464 {
 465         const struct gfs2_glock_operations *glops = gl->gl_ops;
 466         struct gfs2_holder *gh;
 467         unsigned state = ret & LM_OUT_ST_MASK;
 468         int rv;
 469
 470         spin_lock(&gl->gl_spin);
 471         trace_gfs2_glock_state_change(gl, state);
 472         state_change(gl, state);
 473         gh = find_first_waiter(gl);
 474
 475         /* Demote to UN request arrived during demote to SH or DF */
 476         if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
 477             state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
 478                 gl->gl_target = LM_ST_UNLOCKED;
 479
 480         /* Check for state != intended state */
 481         if (unlikely(state != gl->gl_target)) {
 482                 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
 483                         /* move to back of queue and try next entry */
 484                         if (ret & LM_OUT_CANCELED) {
 485                                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
 486                                         list_move_tail(&gh->gh_list, &gl->gl_holders);
 487                                 gh = find_first_waiter(gl);
 488                                 gl->gl_target = gh->gh_state;
 489                                 goto retry;
 490                         }
 491                         /* Some error or failed "try lock" - report it */
 492                         if ((ret & LM_OUT_ERROR) ||
 493                             (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 494                                 gl->gl_target = gl->gl_state;
 495                                 do_error(gl, ret);
 496                                 goto out;
 497                         }
 498                 }
 499                 switch(state) {
 500                 /* Unlocked due to conversion deadlock, try again */
 501                 case LM_ST_UNLOCKED:
 502 retry:
 503                         do_xmote(gl, gh, gl->gl_target);
 504                         break;
 505                 /* Conversion fails, unlock and try again */
 506                 case LM_ST_SHARED:
 507                 case LM_ST_DEFERRED:
 508                         do_xmote(gl, gh, LM_ST_UNLOCKED);
 509                         break;
 510                 default: /* Everything else */
 511                         printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
 512                         GLOCK_BUG_ON(gl, 1);
 513                 }
 514                 spin_unlock(&gl->gl_spin);
 515                 return;
 516         }
 517
 518         /* Fast path - we got what we asked for */
 519         if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
 520                 gfs2_demote_wake(gl);
 521         if (state != LM_ST_UNLOCKED) {
 522                 if (glops->go_xmote_bh) {
 523                         spin_unlock(&gl->gl_spin);
 524                         rv = glops->go_xmote_bh(gl, gh);
 525                         spin_lock(&gl->gl_spin);
 526                         if (rv) {
 527                                 do_error(gl, rv);
 528                                 goto out;
 529                         }
 530                 }
 531                 rv = do_promote(gl);
 532                 if (rv == 2)
 533                         goto out_locked;
 534         }
 535 out:
 536         clear_bit(GLF_LOCK, &gl->gl_flags);
 537 out_locked:
 538         spin_unlock(&gl->gl_spin);
 539 }
 540
 541 static unsigned int gfs2_lm_lock(struct gfs2_sbd *sdp, void *lock,
 542                                  unsigned int req_state,
 543                                  unsigned int flags)
 544 {
 545         int ret = LM_OUT_ERROR;
 546
 547         if (!sdp->sd_lockstruct.ls_ops->lm_lock)
 548                 return req_state == LM_ST_UNLOCKED ? 0 : req_state;
 549
 550         if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 551                 ret = sdp->sd_lockstruct.ls_ops->lm_lock(lock,
 552                                                          req_state, flags);
 553         return ret;
 554 }
 555
 556 /**
 557  * do_xmote - Calls the DLM to change the state of a lock
 558  * @gl: The lock state
 559  * @gh: The holder (only for promotes)
 560  * @target: The target lock state
 561  *
 562  */
 563
 564 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
 565 __releases(&gl->gl_spin)
 566 __acquires(&gl->gl_spin)
 567 {
 568         const struct gfs2_glock_operations *glops = gl->gl_ops;
 569         struct gfs2_sbd *sdp = gl->gl_sbd;
 570         unsigned int lck_flags = gh ? gh->gh_flags : 0;
 571         int ret;
 572
 573         lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
 574                       LM_FLAG_PRIORITY);
 575         BUG_ON(gl->gl_state == target);
 576         BUG_ON(gl->gl_state == gl->gl_target);
 577         if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
 578             glops->go_inval) {
 579                 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 580                 do_error(gl, 0); /* Fail queued try locks */
 581         }
 582         spin_unlock(&gl->gl_spin);
 583         if (glops->go_xmote_th)
 584                 glops->go_xmote_th(gl);
 585         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 586                 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
 587         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 588
 589         gfs2_glock_hold(gl);
 590         if (target != LM_ST_UNLOCKED && (gl->gl_state == LM_ST_SHARED ||
 591             gl->gl_state == LM_ST_DEFERRED) &&
 592             !(lck_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 593                 lck_flags |= LM_FLAG_TRY_1CB;
 594         ret = gfs2_lm_lock(sdp, gl, target, lck_flags);
 595
 596         if (!(ret & LM_OUT_ASYNC)) {
 597                 finish_xmote(gl, ret);
 598                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 599                         gfs2_glock_put(gl);
 600         } else {
 601                 GLOCK_BUG_ON(gl, ret != LM_OUT_ASYNC);
 602         }
 603         spin_lock(&gl->gl_spin);
 604 }
 605
 606 /**
 607  * find_first_holder - find the first "holder" gh
 608  * @gl: the glock
 609  */
 610
 611 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
 612 {
 613         struct gfs2_holder *gh;
 614
 615         if (!list_empty(&gl->gl_holders)) {
 616                 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 617                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 618                         return gh;
 619         }
 620         return NULL;
 621 }
 622
 623 /**
 624  * run_queue - do all outstanding tasks related to a glock
 625  * @gl: The glock in question
 626  * @nonblock: True if we must not block in run_queue
 627  *
 628  */
 629
 630 static void run_queue(struct gfs2_glock *gl, const int nonblock)
 631 __releases(&gl->gl_spin)
 632 __acquires(&gl->gl_spin)
 633 {
 634         struct gfs2_holder *gh = NULL;
 635         int ret;
 636
 637         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 638                 return;
 639
 640         GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
 641
 642         if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
 643             gl->gl_demote_state != gl->gl_state) {
 644                 if (find_first_holder(gl))
 645                         goto out_unlock;
 646                 if (nonblock)
 647                         goto out_sched;
 648                 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
 649                 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
 650                 gl->gl_target = gl->gl_demote_state;
 651         } else {
 652                 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
 653                         gfs2_demote_wake(gl);
 654                 ret = do_promote(gl);
 655                 if (ret == 0)
 656                         goto out_unlock;
 657                 if (ret == 2)
 658                         goto out;
 659                 gh = find_first_waiter(gl);
 660                 gl->gl_target = gh->gh_state;
 661                 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 662                         do_error(gl, 0); /* Fail queued try locks */
 663         }
 664         do_xmote(gl, gh, gl->gl_target);
 665 out:
 666         return;
 667
 668 out_sched:
 669         clear_bit(GLF_LOCK, &gl->gl_flags);
 670         smp_mb__after_clear_bit();
 671         gfs2_glock_hold(gl);
 672         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 673                 gfs2_glock_put_nolock(gl);
 674         return;
 675
 676 out_unlock:
 677         clear_bit(GLF_LOCK, &gl->gl_flags);
 678         smp_mb__after_clear_bit();
 679         return;
 680 }
 681
 682 static void delete_work_func(struct work_struct *work)
 683 {
 684         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
 685         struct gfs2_sbd *sdp = gl->gl_sbd;
 686         struct gfs2_inode *ip = NULL;
 687         struct inode *inode;
 688         u64 no_addr = 0;
 689
 690         spin_lock(&gl->gl_spin);
 691         ip = (struct gfs2_inode *)gl->gl_object;
 692         if (ip)
 693                 no_addr = ip->i_no_addr;
 694         spin_unlock(&gl->gl_spin);
 695         if (ip) {
 696                 inode = gfs2_ilookup(sdp->sd_vfs, no_addr);
 697                 if (inode) {
 698                         d_prune_aliases(inode);
 699                         iput(inode);
 700                 }
 701         }
 702         gfs2_glock_put(gl);
 703 }
 704
 705 static void glock_work_func(struct work_struct *work)
 706 {
 707         unsigned long delay = 0;
 708         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
 709         int drop_ref = 0;
 710
 711         if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
 712                 finish_xmote(gl, gl->gl_reply);
 713                 drop_ref = 1;
 714         }
 715         down_read(&gfs2_umount_flush_sem);
 716         spin_lock(&gl->gl_spin);
 717         if (test_and_clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
 718             gl->gl_state != LM_ST_UNLOCKED &&
 719             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
 720                 unsigned long holdtime, now = jiffies;
 721                 holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
 722                 if (time_before(now, holdtime))
 723                         delay = holdtime - now;
 724                 set_bit(delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE, &gl->gl_flags);
 725         }
 726         run_queue(gl, 0);
 727         spin_unlock(&gl->gl_spin);
 728         up_read(&gfs2_umount_flush_sem);
 729         if (!delay ||
 730             queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
 731                 gfs2_glock_put(gl);
 732         if (drop_ref)
 733                 gfs2_glock_put(gl);
 734 }
 735
 736 /**
 737  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
 738  * @sdp: The GFS2 superblock
 739  * @number: the lock number
 740  * @glops: The glock_operations to use
 741  * @create: If 0, don't create the glock if it doesn't exist
 742  * @glp: the glock is returned here
 743  *
 744  * This does not lock a glock, just finds/creates structures for one.
 745  *
 746  * Returns: errno
 747  */
 748
 749 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 750                    const struct gfs2_glock_operations *glops, int create,
 751                    struct gfs2_glock **glp)
 752 {
 753         struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
 754         struct gfs2_glock *gl, *tmp;
 755         unsigned int hash = gl_hash(sdp, &name);
 756         int error;
 757
 758         read_lock(gl_lock_addr(hash));
 759         gl = search_bucket(hash, sdp, &name);
 760         read_unlock(gl_lock_addr(hash));
 761
 762         *glp = gl;
 763         if (gl)
 764                 return 0;
 765         if (!create)
 766                 return -ENOENT;
 767
 768         gl = kmem_cache_alloc(gfs2_glock_cachep, GFP_KERNEL);
 769         if (!gl)
 770                 return -ENOMEM;
 771
 772         atomic_inc(&sdp->sd_glock_disposal);
 773         gl->gl_flags = 0;
 774         gl->gl_name = name;
 775         atomic_set(&gl->gl_ref, 1);
 776         gl->gl_state = LM_ST_UNLOCKED;
 777         gl->gl_target = LM_ST_UNLOCKED;
 778         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 779         gl->gl_hash = hash;
 780         gl->gl_ops = glops;
 781         snprintf(gl->gl_strname, GDLM_STRNAME_BYTES, "%8x%16llx", name.ln_type, (unsigned long long)number);
 782         memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
 783         gl->gl_lksb.sb_lvbptr = gl->gl_lvb;
 784         gl->gl_tchange = jiffies;
 785         gl->gl_object = NULL;
 786         gl->gl_sbd = sdp;
 787         gl->gl_aspace = NULL;
 788         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
 789         INIT_WORK(&gl->gl_delete, delete_work_func);
 790
 791         /* If this glock protects actual on-disk data or metadata blocks,
 792            create a VFS inode to manage the pages/buffers holding them. */
 793         if (glops == &gfs2_inode_glops || glops == &gfs2_rgrp_glops) {
 794                 gl->gl_aspace = gfs2_aspace_get(sdp);
 795                 if (!gl->gl_aspace) {
 796                         error = -ENOMEM;
 797                         goto fail;
 798                 }
 799         }
 800
 801         write_lock(gl_lock_addr(hash));
 802         tmp = search_bucket(hash, sdp, &name);
 803         if (tmp) {
 804                 write_unlock(gl_lock_addr(hash));
 805                 glock_free(gl);
 806                 gl = tmp;
 807         } else {
 808                 hlist_add_head(&gl->gl_list, &gl_hash_table[hash].hb_list);
 809                 write_unlock(gl_lock_addr(hash));
 810         }
 811
 812         *glp = gl;
 813
 814         return 0;
 815
 816 fail:
 817         kmem_cache_free(gfs2_glock_cachep, gl);
 818         return error;
 819 }
 820
 821 /**
 822  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
 823  * @gl: the glock
 824  * @state: the state we're requesting
 825  * @flags: the modifier flags
 826  * @gh: the holder structure
 827  *
 828  */
 829
 830 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
 831                       struct gfs2_holder *gh)
 832 {
 833         INIT_LIST_HEAD(&gh->gh_list);
 834         gh->gh_gl = gl;
 835         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 836         gh->gh_owner_pid = get_pid(task_pid(current));
 837         gh->gh_state = state;
 838         gh->gh_flags = flags;
 839         gh->gh_error = 0;
 840         gh->gh_iflags = 0;
 841         gfs2_glock_hold(gl);
 842 }
 843
 844 /**
 845  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
 846  * @state: the state we're requesting
 847  * @flags: the modifier flags
 848  * @gh: the holder structure
 849  *
 850  * Don't mess with the glock.
 851  *
 852  */
 853
 854 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
 855 {
 856         gh->gh_state = state;
 857         gh->gh_flags = flags;
 858         gh->gh_iflags = 0;
 859         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 860 }
 861
 862 /**
 863  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 864  * @gh: the holder structure
 865  *
 866  */
 867
 868 void gfs2_holder_uninit(struct gfs2_holder *gh)
 869 {
 870         put_pid(gh->gh_owner_pid);
 871         gfs2_glock_put(gh->gh_gl);
 872         gh->gh_gl = NULL;
 873         gh->gh_ip = 0;
 874 }
 875
 876 /**
 877  * gfs2_glock_holder_wait
 878  * @word: unused
 879  *
 880  * This function and gfs2_glock_demote_wait both show up in the WCHAN
 881  * field. Thus I've separated these otherwise identical functions in
 882  * order to be more informative to the user.
 883  */
 884
 885 static int gfs2_glock_holder_wait(void *word)
 886 {
 887         schedule();
 888         return 0;
 889 }
 890
 891 static int gfs2_glock_demote_wait(void *word)
 892 {
 893         schedule();
 894         return 0;
 895 }
 896
 897 static void wait_on_holder(struct gfs2_holder *gh)
 898 {
 899         might_sleep();
 900         wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
 901 }
 902
 903 static void wait_on_demote(struct gfs2_glock *gl)
 904 {
 905         might_sleep();
 906         wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
 907 }
 908
 909 /**
 910  * handle_callback - process a demote request
 911  * @gl: the glock
 912  * @state: the state the caller wants us to change to
 913  *
 914  * There are only two requests that we are going to see in actual
 915  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
 916  */
 917
 918 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
 919                             unsigned long delay)
 920 {
 921         int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
 922
 923         set_bit(bit, &gl->gl_flags);
 924         if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
 925                 gl->gl_demote_state = state;
 926                 gl->gl_demote_time = jiffies;
 927         } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
 928                         gl->gl_demote_state != state) {
 929                 gl->gl_demote_state = LM_ST_UNLOCKED;
 930         }
 931         if (gl->gl_ops->go_callback)
 932                 gl->gl_ops->go_callback(gl);
 933         trace_gfs2_demote_rq(gl);
 934 }
 935
 936 /**
 937  * gfs2_glock_wait - wait on a glock acquisition
 938  * @gh: the glock holder
 939  *
 940  * Returns: 0 on success
 941  */
 942
 943 int gfs2_glock_wait(struct gfs2_holder *gh)
 944 {
 945         wait_on_holder(gh);
 946         return gh->gh_error;
 947 }
 948
 949 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
 950 {
 951         va_list args;
 952
 953         va_start(args, fmt);
 954         if (seq) {
 955                 struct gfs2_glock_iter *gi = seq->private;
 956                 vsprintf(gi->string, fmt, args);
 957                 seq_printf(seq, gi->string);
 958         } else {
 959                 printk(KERN_ERR " ");
 960                 vprintk(fmt, args);
 961         }
 962         va_end(args);
 963 }
 964
 965 /**
 966  * add_to_queue - Add a holder to the wait queue (but look for recursion)
 967  * @gh: the holder structure to add
 968  *
 969  * Eventually we should move the recursive locking trap to a
 970  * debugging option or something like that. This is the fast
 971  * path and needs to have the minimum number of distractions.
 972  *
 973  */
 974
 975 static inline void add_to_queue(struct gfs2_holder *gh)
 976 __releases(&gl->gl_spin)
 977 __acquires(&gl->gl_spin)
 978 {
 979         struct gfs2_glock *gl = gh->gh_gl;
 980         struct gfs2_sbd *sdp = gl->gl_sbd;
 981         struct list_head *insert_pt = NULL;
 982         struct gfs2_holder *gh2;
 983         int try_lock = 0;
 984
 985         BUG_ON(gh->gh_owner_pid == NULL);
 986         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
 987                 BUG();
 988
 989         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
 990                 if (test_bit(GLF_LOCK, &gl->gl_flags))
 991                         try_lock = 1;
 992                 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 993                         goto fail;
 994         }
 995
 996         list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
 997                 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
 998                     (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
 999                         goto trap_recursive;
1000                 if (try_lock &&
1001                     !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
1002                     !may_grant(gl, gh)) {
1003 fail:
1004                         gh->gh_error = GLR_TRYFAILED;
1005                         gfs2_holder_wake(gh);
1006                         return;
1007                 }
1008                 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
1009                         continue;
1010                 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
1011                         insert_pt = &gh2->gh_list;
1012         }
1013         if (likely(insert_pt == NULL)) {
1014                 list_add_tail(&gh->gh_list, &gl->gl_holders);
1015                 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
1016                         goto do_cancel;
1017                 return;
1018         }
1019         trace_gfs2_glock_queue(gh, 1);
1020         list_add_tail(&gh->gh_list, insert_pt);
1021 do_cancel:
1022         gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
1023         if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
1024                 spin_unlock(&gl->gl_spin);
1025                 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
1026                         sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
1027                 spin_lock(&gl->gl_spin);
1028         }
1029         return;
1030
1031 trap_recursive:
1032         print_symbol(KERN_ERR "original: %s\n", gh2->gh_ip);
1033         printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
1034         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1035                gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
1036         print_symbol(KERN_ERR "new: %s\n", gh->gh_ip);
1037         printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
1038         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1039                gh->gh_gl->gl_name.ln_type, gh->gh_state);
1040         __dump_glock(NULL, gl);
1041         BUG();
1042 }
1043
1044 /**
1045  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1046  * @gh: the holder structure
1047  *
1048  * if (gh->gh_flags & GL_ASYNC), this never returns an error
1049  *
1050  * Returns: 0, GLR_TRYFAILED, or errno on failure
1051  */
1052
1053 int gfs2_glock_nq(struct gfs2_holder *gh)
1054 {
1055         struct gfs2_glock *gl = gh->gh_gl;
1056         struct gfs2_sbd *sdp = gl->gl_sbd;
1057         int error = 0;
1058
1059         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
1060                 return -EIO;
1061
1062         spin_lock(&gl->gl_spin);
1063         add_to_queue(gh);
1064         run_queue(gl, 1);
1065         spin_unlock(&gl->gl_spin);
1066
1067         if (!(gh->gh_flags & GL_ASYNC))
1068                 error = gfs2_glock_wait(gh);
1069
1070         return error;
1071 }
1072
1073 /**
1074  * gfs2_glock_poll - poll to see if an async request has been completed
1075  * @gh: the holder
1076  *
1077  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1078  */
1079
1080 int gfs2_glock_poll(struct gfs2_holder *gh)
1081 {
1082         return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1083 }
1084
1085 /**
1086  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1087  * @gh: the glock holder
1088  *
1089  */
1090
1091 void gfs2_glock_dq(struct gfs2_holder *gh)
1092 {
1093         struct gfs2_glock *gl = gh->gh_gl;
1094         const struct gfs2_glock_operations *glops = gl->gl_ops;
1095         unsigned delay = 0;
1096         int fast_path = 0;
1097
1098         spin_lock(&gl->gl_spin);
1099         if (gh->gh_flags & GL_NOCACHE)
1100                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1101
1102         list_del_init(&gh->gh_list);
1103         if (find_first_holder(gl) == NULL) {
1104                 if (glops->go_unlock) {
1105                         GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1106                         spin_unlock(&gl->gl_spin);
1107                         glops->go_unlock(gh);
1108                         spin_lock(&gl->gl_spin);
1109                         clear_bit(GLF_LOCK, &gl->gl_flags);
1110                 }
1111                 if (list_empty(&gl->gl_holders) &&
1112                     !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1113                     !test_bit(GLF_DEMOTE, &gl->gl_flags))
1114                         fast_path = 1;
1115         }
1116         trace_gfs2_glock_queue(gh, 0);
1117         spin_unlock(&gl->gl_spin);
1118         if (likely(fast_path))
1119                 return;
1120
1121         gfs2_glock_hold(gl);
1122         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1123             !test_bit(GLF_DEMOTE, &gl->gl_flags))
1124                 delay = gl->gl_ops->go_min_hold_time;
1125         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1126                 gfs2_glock_put(gl);
1127 }
1128
1129 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1130 {
1131         struct gfs2_glock *gl = gh->gh_gl;
1132         gfs2_glock_dq(gh);
1133         wait_on_demote(gl);
1134 }
1135
1136 /**
1137  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1138  * @gh: the holder structure
1139  *
1140  */
1141
1142 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1143 {
1144         gfs2_glock_dq(gh);
1145         gfs2_holder_uninit(gh);
1146 }
1147
1148 /**
1149  * gfs2_glock_nq_num - acquire a glock based on lock number
1150  * @sdp: the filesystem
1151  * @number: the lock number
1152  * @glops: the glock operations for the type of glock
1153  * @state: the state to acquire the glock in
1154  * @flags: modifier flags for the aquisition
1155  * @gh: the struct gfs2_holder
1156  *
1157  * Returns: errno
1158  */
1159
1160 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1161                       const struct gfs2_glock_operations *glops,
1162                       unsigned int state, int flags, struct gfs2_holder *gh)
1163 {
1164         struct gfs2_glock *gl;
1165         int error;
1166
1167         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1168         if (!error) {
1169                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1170                 gfs2_glock_put(gl);
1171         }
1172
1173         return error;
1174 }
1175
1176 /**
1177  * glock_compare - Compare two struct gfs2_glock structures for sorting
1178  * @arg_a: the first structure
1179  * @arg_b: the second structure
1180  *
1181  */
1182
1183 static int glock_compare(const void *arg_a, const void *arg_b)
1184 {
1185         const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1186         const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1187         const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1188         const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1189
1190         if (a->ln_number > b->ln_number)
1191                 return 1;
1192         if (a->ln_number < b->ln_number)
1193                 return -1;
1194         BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1195         return 0;
1196 }
1197
1198 /**
1199  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1200  * @num_gh: the number of structures
1201  * @ghs: an array of struct gfs2_holder structures
1202  *
1203  * Returns: 0 on success (all glocks acquired),
1204  *          errno on failure (no glocks acquired)
1205  */
1206
1207 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1208                      struct gfs2_holder **p)
1209 {
1210         unsigned int x;
1211         int error = 0;
1212
1213         for (x = 0; x < num_gh; x++)
1214                 p[x] = &ghs[x];
1215
1216         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1217
1218         for (x = 0; x < num_gh; x++) {
1219                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1220
1221                 error = gfs2_glock_nq(p[x]);
1222                 if (error) {
1223                         while (x--)
1224                                 gfs2_glock_dq(p[x]);
1225                         break;
1226                 }
1227         }
1228
1229         return error;
1230 }
1231
1232 /**
1233  * gfs2_glock_nq_m - acquire multiple glocks
1234  * @num_gh: the number of structures
1235  * @ghs: an array of struct gfs2_holder structures
1236  *
1237  *
1238  * Returns: 0 on success (all glocks acquired),
1239  *          errno on failure (no glocks acquired)
1240  */
1241
1242 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1243 {
1244         struct gfs2_holder *tmp[4];
1245         struct gfs2_holder **pph = tmp;
1246         int error = 0;
1247
1248         switch(num_gh) {
1249         case 0:
1250                 return 0;
1251         case 1:
1252                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1253                 return gfs2_glock_nq(ghs);
1254         default:
1255                 if (num_gh <= 4)
1256                         break;
1257                 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1258                 if (!pph)
1259                         return -ENOMEM;
1260         }
1261
1262         error = nq_m_sync(num_gh, ghs, pph);
1263
1264         if (pph != tmp)
1265                 kfree(pph);
1266
1267         return error;
1268 }
1269
1270 /**
1271  * gfs2_glock_dq_m - release multiple glocks
1272  * @num_gh: the number of structures
1273  * @ghs: an array of struct gfs2_holder structures
1274  *
1275  */
1276
1277 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1278 {
1279         unsigned int x;
1280
1281         for (x = 0; x < num_gh; x++)
1282                 gfs2_glock_dq(&ghs[x]);
1283 }
1284
1285 /**
1286  * gfs2_glock_dq_uninit_m - release multiple glocks
1287  * @num_gh: the number of structures
1288  * @ghs: an array of struct gfs2_holder structures
1289  *
1290  */
1291
1292 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1293 {
1294         unsigned int x;
1295
1296         for (x = 0; x < num_gh; x++)
1297                 gfs2_glock_dq_uninit(&ghs[x]);
1298 }
1299
1300 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1301 {
1302         unsigned long delay = 0;
1303         unsigned long holdtime;
1304         unsigned long now = jiffies;
1305
1306         gfs2_glock_hold(gl);
1307         holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
1308         if (time_before(now, holdtime))
1309                 delay = holdtime - now;
1310         if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1311                 delay = gl->gl_ops->go_min_hold_time;
1312
1313         spin_lock(&gl->gl_spin);
1314         handle_callback(gl, state, delay);
1315         spin_unlock(&gl->gl_spin);
1316         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1317                 gfs2_glock_put(gl);
1318 }
1319
1320 /**
1321  * gfs2_glock_complete - Callback used by locking
1322  * @gl: Pointer to the glock
1323  * @ret: The return value from the dlm
1324  *
1325  */
1326
1327 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1328 {
1329         struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
1330         gl->gl_reply = ret;
1331         if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_flags))) {
1332                 struct gfs2_holder *gh;
1333                 spin_lock(&gl->gl_spin);
1334                 gh = find_first_waiter(gl);
1335                 if ((!(gh && (gh->gh_flags & LM_FLAG_NOEXP)) &&
1336                      (gl->gl_target != LM_ST_UNLOCKED)) ||
1337                     ((ret & ~LM_OUT_ST_MASK) != 0))
1338                         set_bit(GLF_FROZEN, &gl->gl_flags);
1339                 spin_unlock(&gl->gl_spin);
1340                 if (test_bit(GLF_FROZEN, &gl->gl_flags))
1341                         return;
1342         }
1343         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1344         gfs2_glock_hold(gl);
1345         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1346                 gfs2_glock_put(gl);
1347 }
1348
1349
1350 static int gfs2_shrink_glock_memory(int nr, gfp_t gfp_mask)
1351 {
1352         struct gfs2_glock *gl;
1353         int may_demote;
1354         int nr_skipped = 0;
1355         LIST_HEAD(skipped);
1356
1357         if (nr == 0)
1358                 goto out;
1359
1360         if (!(gfp_mask & __GFP_FS))
1361                 return -1;
1362
1363         spin_lock(&lru_lock);
1364         while(nr && !list_empty(&lru_list)) {
1365                 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1366                 list_del_init(&gl->gl_lru);
1367                 atomic_dec(&lru_count);
1368
1369                 /* Test for being demotable */
1370                 if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1371                         gfs2_glock_hold(gl);
1372                         spin_unlock(&lru_lock);
1373                         spin_lock(&gl->gl_spin);
1374                         may_demote = demote_ok(gl);
1375                         if (may_demote) {
1376                                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1377                                 nr--;
1378                         }
1379                         clear_bit(GLF_LOCK, &gl->gl_flags);
1380                         smp_mb__after_clear_bit();
1381                         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1382                                 gfs2_glock_put_nolock(gl);
1383                         spin_unlock(&gl->gl_spin);
1384                         spin_lock(&lru_lock);
1385                         continue;
1386                 }
1387                 nr_skipped++;
1388                 list_add(&gl->gl_lru, &skipped);
1389         }
1390         list_splice(&skipped, &lru_list);
1391         atomic_add(nr_skipped, &lru_count);
1392         spin_unlock(&lru_lock);
1393 out:
1394         return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
1395 }
1396
1397 static struct shrinker glock_shrinker = {
1398         .shrink = gfs2_shrink_glock_memory,
1399         .seeks = DEFAULT_SEEKS,
1400 };
1401
1402 /**
1403  * examine_bucket - Call a function for glock in a hash bucket
1404  * @examiner: the function
1405  * @sdp: the filesystem
1406  * @bucket: the bucket
1407  *
1408  * Returns: 1 if the bucket has entries
1409  */
1410
1411 static int examine_bucket(glock_examiner examiner, struct gfs2_sbd *sdp,
1412                           unsigned int hash)
1413 {
1414         struct gfs2_glock *gl, *prev = NULL;
1415         int has_entries = 0;
1416         struct hlist_head *head = &gl_hash_table[hash].hb_list;
1417
1418         read_lock(gl_lock_addr(hash));
1419         /* Can't use hlist_for_each_entry - don't want prefetch here */
1420         if (hlist_empty(head))
1421                 goto out;
1422         gl = list_entry(head->first, struct gfs2_glock, gl_list);
1423         while(1) {
1424                 if (!sdp || gl->gl_sbd == sdp) {
1425                         gfs2_glock_hold(gl);
1426                         read_unlock(gl_lock_addr(hash));
1427                         if (prev)
1428                                 gfs2_glock_put(prev);
1429                         prev = gl;
1430                         examiner(gl);
1431                         has_entries = 1;
1432                         read_lock(gl_lock_addr(hash));
1433                 }
1434                 if (gl->gl_list.next == NULL)
1435                         break;
1436                 gl = list_entry(gl->gl_list.next, struct gfs2_glock, gl_list);
1437         }
1438 out:
1439         read_unlock(gl_lock_addr(hash));
1440         if (prev)
1441                 gfs2_glock_put(prev);
1442         cond_resched();
1443         return has_entries;
1444 }
1445
1446
1447 /**
1448  * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1449  * @gl: The glock to thaw
1450  *
1451  * N.B. When we freeze a glock, we leave a ref to the glock outstanding,
1452  * so this has to result in the ref count being dropped by one.
1453  */
1454
1455 static void thaw_glock(struct gfs2_glock *gl)
1456 {
1457         if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1458                 return;
1459         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1460         gfs2_glock_hold(gl);
1461         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1462                 gfs2_glock_put(gl);
1463 }
1464
1465 /**
1466  * clear_glock - look at a glock and see if we can free it from glock cache
1467  * @gl: the glock to look at
1468  *
1469  */
1470
1471 static void clear_glock(struct gfs2_glock *gl)
1472 {
1473         spin_lock(&lru_lock);
1474         if (!list_empty(&gl->gl_lru)) {
1475                 list_del_init(&gl->gl_lru);
1476                 atomic_dec(&lru_count);
1477         }
1478         spin_unlock(&lru_lock);
1479
1480         spin_lock(&gl->gl_spin);
1481         if (find_first_holder(gl) == NULL && gl->gl_state != LM_ST_UNLOCKED)
1482                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1483         spin_unlock(&gl->gl_spin);
1484         gfs2_glock_hold(gl);
1485         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1486                 gfs2_glock_put(gl);
1487 }
1488
1489 /**
1490  * gfs2_glock_thaw - Thaw any frozen glocks
1491  * @sdp: The super block
1492  *
1493  */
1494
1495 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1496 {
1497         unsigned x;
1498
1499         for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1500                 examine_bucket(thaw_glock, sdp, x);
1501 }
1502
1503 /**
1504  * gfs2_gl_hash_clear - Empty out the glock hash table
1505  * @sdp: the filesystem
1506  * @wait: wait until it's all gone
1507  *
1508  * Called when unmounting the filesystem.
1509  */
1510
1511 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1512 {
1513         unsigned long t;
1514         unsigned int x;
1515         int cont;
1516
1517         t = jiffies;
1518
1519         for (;;) {
1520                 cont = 0;
1521                 for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
1522                         if (examine_bucket(clear_glock, sdp, x))
1523                                 cont = 1;
1524                 }
1525
1526                 if (!cont)
1527                         break;
1528
1529                 if (time_after_eq(jiffies,
1530                                   t + gfs2_tune_get(sdp, gt_stall_secs) * HZ)) {
1531                         fs_warn(sdp, "Unmount seems to be stalled. "
1532                                      "Dumping lock state...\n");
1533                         gfs2_dump_lockstate(sdp);
1534                         t = jiffies;
1535                 }
1536
1537                 down_write(&gfs2_umount_flush_sem);
1538                 invalidate_inodes(sdp->sd_vfs);
1539                 up_write(&gfs2_umount_flush_sem);
1540                 msleep(10);
1541         }
1542         flush_workqueue(glock_workqueue);
1543         wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
1544         gfs2_dump_lockstate(sdp);
1545 }
1546
1547 void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1548 {
1549         struct gfs2_glock *gl = ip->i_gl;
1550         int ret;
1551
1552         ret = gfs2_truncatei_resume(ip);
1553         gfs2_assert_withdraw(gl->gl_sbd, ret == 0);
1554
1555         spin_lock(&gl->gl_spin);
1556         clear_bit(GLF_LOCK, &gl->gl_flags);
1557         run_queue(gl, 1);
1558         spin_unlock(&gl->gl_spin);
1559 }
1560
1561 static const char *state2str(unsigned state)
1562 {
1563         switch(state) {
1564         case LM_ST_UNLOCKED:
1565                 return "UN";
1566         case LM_ST_SHARED:
1567                 return "SH";
1568         case LM_ST_DEFERRED:
1569                 return "DF";
1570         case LM_ST_EXCLUSIVE:
1571                 return "EX";
1572         }
1573         return "??";
1574 }
1575
1576 static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags)
1577 {
1578         char *p = buf;
1579         if (flags & LM_FLAG_TRY)
1580                 *p++ = 't';
1581         if (flags & LM_FLAG_TRY_1CB)
1582                 *p++ = 'T';
1583         if (flags & LM_FLAG_NOEXP)
1584                 *p++ = 'e';
1585         if (flags & LM_FLAG_ANY)
1586                 *p++ = 'A';
1587         if (flags & LM_FLAG_PRIORITY)
1588                 *p++ = 'p';
1589         if (flags & GL_ASYNC)
1590                 *p++ = 'a';
1591         if (flags & GL_EXACT)
1592                 *p++ = 'E';
1593         if (flags & GL_NOCACHE)
1594                 *p++ = 'c';
1595         if (test_bit(HIF_HOLDER, &iflags))
1596                 *p++ = 'H';
1597         if (test_bit(HIF_WAIT, &iflags))
1598                 *p++ = 'W';
1599         if (test_bit(HIF_FIRST, &iflags))
1600                 *p++ = 'F';
1601         *p = 0;
1602         return buf;
1603 }
1604
1605 /**
1606  * dump_holder - print information about a glock holder
1607  * @seq: the seq_file struct
1608  * @gh: the glock holder
1609  *
1610  * Returns: 0 on success, -ENOBUFS when we run out of space
1611  */
1612
1613 static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1614 {
1615         struct task_struct *gh_owner = NULL;
1616         char buffer[KSYM_SYMBOL_LEN];
1617         char flags_buf[32];
1618
1619         sprint_symbol(buffer, gh->gh_ip);
1620         if (gh->gh_owner_pid)
1621                 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1622         gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %s\n",
1623                   state2str(gh->gh_state),
1624                   hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1625                   gh->gh_error,
1626                   gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1627                   gh_owner ? gh_owner->comm : "(ended)", buffer);
1628         return 0;
1629 }
1630
1631 static const char *gflags2str(char *buf, const unsigned long *gflags)
1632 {
1633         char *p = buf;
1634         if (test_bit(GLF_LOCK, gflags))
1635                 *p++ = 'l';
1636         if (test_bit(GLF_DEMOTE, gflags))
1637                 *p++ = 'D';
1638         if (test_bit(GLF_PENDING_DEMOTE, gflags))
1639                 *p++ = 'd';
1640         if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1641                 *p++ = 'p';
1642         if (test_bit(GLF_DIRTY, gflags))
1643                 *p++ = 'y';
1644         if (test_bit(GLF_LFLUSH, gflags))
1645                 *p++ = 'f';
1646         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1647                 *p++ = 'i';
1648         if (test_bit(GLF_REPLY_PENDING, gflags))
1649                 *p++ = 'r';
1650         if (test_bit(GLF_INITIAL, gflags))
1651                 *p++ = 'I';
1652         if (test_bit(GLF_FROZEN, gflags))
1653                 *p++ = 'F';
1654         *p = 0;
1655         return buf;
1656 }
1657
1658 /**
1659  * __dump_glock - print information about a glock
1660  * @seq: The seq_file struct
1661  * @gl: the glock
1662  *
1663  * The file format is as follows:
1664  * One line per object, capital letters are used to indicate objects
1665  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1666  * other objects are indented by a single space and follow the glock to
1667  * which they are related. Fields are indicated by lower case letters
1668  * followed by a colon and the field value, except for strings which are in
1669  * [] so that its possible to see if they are composed of spaces for
1670  * example. The field's are n = number (id of the object), f = flags,
1671  * t = type, s = state, r = refcount, e = error, p = pid.
1672  *
1673  * Returns: 0 on success, -ENOBUFS when we run out of space
1674  */
1675
1676 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1677 {
1678         const struct gfs2_glock_operations *glops = gl->gl_ops;
1679         unsigned long long dtime;
1680         const struct gfs2_holder *gh;
1681         char gflags_buf[32];
1682         int error = 0;
1683
1684         dtime = jiffies - gl->gl_demote_time;
1685         dtime *= 1000000/HZ; /* demote time in uSec */
1686         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1687                 dtime = 0;
1688         gfs2_print_dbg(seq, "G:  s:%s n:%u/%llu f:%s t:%s d:%s/%llu a:%d r:%d\n",
1689                   state2str(gl->gl_state),
1690                   gl->gl_name.ln_type,
1691                   (unsigned long long)gl->gl_name.ln_number,
1692                   gflags2str(gflags_buf, &gl->gl_flags),
1693                   state2str(gl->gl_target),
1694                   state2str(gl->gl_demote_state), dtime,
1695                   atomic_read(&gl->gl_ail_count),
1696                   atomic_read(&gl->gl_ref));
1697
1698         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1699                 error = dump_holder(seq, gh);
1700                 if (error)
1701                         goto out;
1702         }
1703         if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1704                 error = glops->go_dump(seq, gl);
1705 out:
1706         return error;
1707 }
1708
1709 static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1710 {
1711         int ret;
1712         spin_lock(&gl->gl_spin);
1713         ret = __dump_glock(seq, gl);
1714         spin_unlock(&gl->gl_spin);
1715         return ret;
1716 }
1717
1718 /**
1719  * gfs2_dump_lockstate - print out the current lockstate
1720  * @sdp: the filesystem
1721  * @ub: the buffer to copy the information into
1722  *
1723  * If @ub is NULL, dump the lockstate to the console.
1724  *
1725  */
1726
1727 static int gfs2_dump_lockstate(struct gfs2_sbd *sdp)
1728 {
1729         struct gfs2_glock *gl;
1730         struct hlist_node *h;
1731         unsigned int x;
1732         int error = 0;
1733
1734         for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
1735
1736                 read_lock(gl_lock_addr(x));
1737
1738                 hlist_for_each_entry(gl, h, &gl_hash_table[x].hb_list, gl_list) {
1739                         if (gl->gl_sbd != sdp)
1740                                 continue;
1741
1742                         error = dump_glock(NULL, gl);
1743                         if (error)
1744                                 break;
1745                 }
1746
1747                 read_unlock(gl_lock_addr(x));
1748
1749                 if (error)
1750                         break;
1751         }
1752
1753
1754         return error;
1755 }
1756
1757
1758 int __init gfs2_glock_init(void)
1759 {
1760         unsigned i;
1761         for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
1762                 INIT_HLIST_HEAD(&gl_hash_table[i].hb_list);
1763         }
1764 #ifdef GL_HASH_LOCK_SZ
1765         for(i = 0; i < GL_HASH_LOCK_SZ; i++) {
1766                 rwlock_init(&gl_hash_locks[i]);
1767         }
1768 #endif
1769
1770         glock_workqueue = create_workqueue("glock_workqueue");
1771         if (IS_ERR(glock_workqueue))
1772                 return PTR_ERR(glock_workqueue);
1773         gfs2_delete_workqueue = create_workqueue("delete_workqueue");
1774         if (IS_ERR(gfs2_delete_workqueue)) {
1775                 destroy_workqueue(glock_workqueue);
1776                 return PTR_ERR(gfs2_delete_workqueue);
1777         }
1778
1779         register_shrinker(&glock_shrinker);
1780
1781         return 0;
1782 }
1783
1784 void gfs2_glock_exit(void)
1785 {
1786         unregister_shrinker(&glock_shrinker);
1787         destroy_workqueue(glock_workqueue);
1788         destroy_workqueue(gfs2_delete_workqueue);
1789 }
1790
1791 static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1792 {
1793         struct gfs2_glock *gl;
1794
1795 restart:
1796         read_lock(gl_lock_addr(gi->hash));
1797         gl = gi->gl;
1798         if (gl) {
1799                 gi->gl = hlist_entry(gl->gl_list.next,
1800                                      struct gfs2_glock, gl_list);
1801         } else {
1802                 gi->gl = hlist_entry(gl_hash_table[gi->hash].hb_list.first,
1803                                      struct gfs2_glock, gl_list);
1804         }
1805         if (gi->gl)
1806                 gfs2_glock_hold(gi->gl);
1807         read_unlock(gl_lock_addr(gi->hash));
1808         if (gl)
1809                 gfs2_glock_put(gl);
1810         while (gi->gl == NULL) {
1811                 gi->hash++;
1812                 if (gi->hash >= GFS2_GL_HASH_SIZE)
1813                         return 1;
1814                 read_lock(gl_lock_addr(gi->hash));
1815                 gi->gl = hlist_entry(gl_hash_table[gi->hash].hb_list.first,
1816                                      struct gfs2_glock, gl_list);
1817                 if (gi->gl)
1818                         gfs2_glock_hold(gi->gl);
1819                 read_unlock(gl_lock_addr(gi->hash));
1820         }
1821
1822         if (gi->sdp != gi->gl->gl_sbd)
1823                 goto restart;
1824
1825         return 0;
1826 }
1827
1828 static void gfs2_glock_iter_free(struct gfs2_glock_iter *gi)
1829 {
1830         if (gi->gl)
1831                 gfs2_glock_put(gi->gl);
1832         gi->gl = NULL;
1833 }
1834
1835 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1836 {
1837         struct gfs2_glock_iter *gi = seq->private;
1838         loff_t n = *pos;
1839
1840         gi->hash = 0;
1841
1842         do {
1843                 if (gfs2_glock_iter_next(gi)) {
1844                         gfs2_glock_iter_free(gi);
1845                         return NULL;
1846                 }
1847         } while (n--);
1848
1849         return gi->gl;
1850 }
1851
1852 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1853                                  loff_t *pos)
1854 {
1855         struct gfs2_glock_iter *gi = seq->private;
1856
1857         (*pos)++;
1858
1859         if (gfs2_glock_iter_next(gi)) {
1860                 gfs2_glock_iter_free(gi);
1861                 return NULL;
1862         }
1863
1864         return gi->gl;
1865 }
1866
1867 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1868 {
1869         struct gfs2_glock_iter *gi = seq->private;
1870         gfs2_glock_iter_free(gi);
1871 }
1872
1873 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1874 {
1875         return dump_glock(seq, iter_ptr);
1876 }
1877
1878 static const struct seq_operations gfs2_glock_seq_ops = {
1879         .start = gfs2_glock_seq_start,
1880         .next  = gfs2_glock_seq_next,
1881         .stop  = gfs2_glock_seq_stop,
1882         .show  = gfs2_glock_seq_show,
1883 };
1884
1885 static int gfs2_debugfs_open(struct inode *inode, struct file *file)
1886 {
1887         int ret = seq_open_private(file, &gfs2_glock_seq_ops,
1888                                    sizeof(struct gfs2_glock_iter));
1889         if (ret == 0) {
1890                 struct seq_file *seq = file->private_data;
1891                 struct gfs2_glock_iter *gi = seq->private;
1892                 gi->sdp = inode->i_private;
1893         }
1894         return ret;
1895 }
1896
1897 static const struct file_operations gfs2_debug_fops = {
1898         .owner   = THIS_MODULE,
1899         .open    = gfs2_debugfs_open,
1900         .read    = seq_read,
1901         .llseek  = seq_lseek,
1902         .release = seq_release_private,
1903 };
1904
1905 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
1906 {
1907         sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
1908         if (!sdp->debugfs_dir)
1909                 return -ENOMEM;
1910         sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
1911                                                          S_IFREG | S_IRUGO,
1912                                                          sdp->debugfs_dir, sdp,
1913                                                          &gfs2_debug_fops);
1914         if (!sdp->debugfs_dentry_glocks)
1915                 return -ENOMEM;
1916
1917         return 0;
1918 }
1919
1920 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
1921 {
1922         if (sdp && sdp->debugfs_dir) {
1923                 if (sdp->debugfs_dentry_glocks) {
1924                         debugfs_remove(sdp->debugfs_dentry_glocks);
1925                         sdp->debugfs_dentry_glocks = NULL;
1926                 }
1927                 debugfs_remove(sdp->debugfs_dir);
1928                 sdp->debugfs_dir = NULL;
1929         }
1930 }
1931
1932 int gfs2_register_debugfs(void)
1933 {
1934         gfs2_root = debugfs_create_dir("gfs2", NULL);
1935         return gfs2_root ? 0 : -ENOMEM;
1936 }
1937
1938 void gfs2_unregister_debugfs(void)
1939 {
1940         debugfs_remove(gfs2_root);
1941         gfs2_root = NULL;
1942 }