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/completion.h>
  14 #include <linux/buffer_head.h>
  15 #include <linux/delay.h>
  16 #include <linux/sort.h>
  17 #include <linux/jhash.h>
  18 #include <linux/kallsyms.h>
  19 #include <linux/gfs2_ondisk.h>
  20 #include <linux/list.h>
  21 #include <linux/lm_interface.h>
  22 #include <linux/wait.h>
  23 #include <linux/module.h>
  24 #include <linux/rwsem.h>
  25 #include <asm/uaccess.h>
  26 #include <linux/seq_file.h>
  27 #include <linux/debugfs.h>
  28 #include <linux/kthread.h>
  29 #include <linux/freezer.h>
  30 #include <linux/workqueue.h>
  31 #include <linux/jiffies.h>
  32
  33 #include "gfs2.h"
  34 #include "incore.h"
  35 #include "glock.h"
  36 #include "glops.h"
  37 #include "inode.h"
  38 #include "lops.h"
  39 #include "meta_io.h"
  40 #include "quota.h"
  41 #include "super.h"
  42 #include "util.h"
  43
  44 struct gfs2_gl_hash_bucket {
  45         struct hlist_head hb_list;
  46 };
  47
  48 struct gfs2_glock_iter {
  49         int hash;                       /* hash bucket index         */
  50         struct gfs2_sbd *sdp;           /* incore superblock         */
  51         struct gfs2_glock *gl;          /* current glock struct      */
  52         char string[512];               /* scratch space             */
  53 };
  54
  55 typedef void (*glock_examiner) (struct gfs2_glock * gl);
  56
  57 static int gfs2_dump_lockstate(struct gfs2_sbd *sdp);
  58 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl);
  59 #define GLOCK_BUG_ON(gl,x) do { if (unlikely(x)) { __dump_glock(NULL, gl); BUG(); } } while(0)
  60 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
  61
  62 static DECLARE_RWSEM(gfs2_umount_flush_sem);
  63 static struct dentry *gfs2_root;
  64 static struct task_struct *scand_process;
  65 static unsigned int scand_secs = 5;
  66 static struct workqueue_struct *glock_workqueue;
  67
  68 #define GFS2_GL_HASH_SHIFT      15
  69 #define GFS2_GL_HASH_SIZE       (1 << GFS2_GL_HASH_SHIFT)
  70 #define GFS2_GL_HASH_MASK       (GFS2_GL_HASH_SIZE - 1)
  71
  72 static struct gfs2_gl_hash_bucket gl_hash_table[GFS2_GL_HASH_SIZE];
  73 static struct dentry *gfs2_root;
  74
  75 /*
  76  * Despite what you might think, the numbers below are not arbitrary :-)
  77  * They are taken from the ipv4 routing hash code, which is well tested
  78  * and thus should be nearly optimal. Later on we might tweek the numbers
  79  * but for now this should be fine.
  80  *
  81  * The reason for putting the locks in a separate array from the list heads
  82  * is that we can have fewer locks than list heads and save memory. We use
  83  * the same hash function for both, but with a different hash mask.
  84  */
  85 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) || \
  86         defined(CONFIG_PROVE_LOCKING)
  87
  88 #ifdef CONFIG_LOCKDEP
  89 # define GL_HASH_LOCK_SZ        256
  90 #else
  91 # if NR_CPUS >= 32
  92 #  define GL_HASH_LOCK_SZ       4096
  93 # elif NR_CPUS >= 16
  94 #  define GL_HASH_LOCK_SZ       2048
  95 # elif NR_CPUS >= 8
  96 #  define GL_HASH_LOCK_SZ       1024
  97 # elif NR_CPUS >= 4
  98 #  define GL_HASH_LOCK_SZ       512
  99 # else
 100 #  define GL_HASH_LOCK_SZ       256
 101 # endif
 102 #endif
 103
 104 /* We never want more locks than chains */
 105 #if GFS2_GL_HASH_SIZE < GL_HASH_LOCK_SZ
 106 # undef GL_HASH_LOCK_SZ
 107 # define GL_HASH_LOCK_SZ GFS2_GL_HASH_SIZE
 108 #endif
 109
 110 static rwlock_t gl_hash_locks[GL_HASH_LOCK_SZ];
 111
 112 static inline rwlock_t *gl_lock_addr(unsigned int x)
 113 {
 114         return &gl_hash_locks[x & (GL_HASH_LOCK_SZ-1)];
 115 }
 116 #else /* not SMP, so no spinlocks required */
 117 static inline rwlock_t *gl_lock_addr(unsigned int x)
 118 {
 119         return NULL;
 120 }
 121 #endif
 122
 123 /**
 124  * gl_hash() - Turn glock number into hash bucket number
 125  * @lock: The glock number
 126  *
 127  * Returns: The number of the corresponding hash bucket
 128  */
 129
 130 static unsigned int gl_hash(const struct gfs2_sbd *sdp,
 131                             const struct lm_lockname *name)
 132 {
 133         unsigned int h;
 134
 135         h = jhash(&name->ln_number, sizeof(u64), 0);
 136         h = jhash(&name->ln_type, sizeof(unsigned int), h);
 137         h = jhash(&sdp, sizeof(struct gfs2_sbd *), h);
 138         h &= GFS2_GL_HASH_MASK;
 139
 140         return h;
 141 }
 142
 143 /**
 144  * glock_free() - Perform a few checks and then release struct gfs2_glock
 145  * @gl: The glock to release
 146  *
 147  * Also calls lock module to release its internal structure for this glock.
 148  *
 149  */
 150
 151 static void glock_free(struct gfs2_glock *gl)
 152 {
 153         struct gfs2_sbd *sdp = gl->gl_sbd;
 154         struct inode *aspace = gl->gl_aspace;
 155
 156         if (sdp->sd_lockstruct.ls_ops->lm_put_lock)
 157                 sdp->sd_lockstruct.ls_ops->lm_put_lock(gl->gl_lock);
 158
 159         if (aspace)
 160                 gfs2_aspace_put(aspace);
 161
 162         kmem_cache_free(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 static void gfs2_glock_hold(struct gfs2_glock *gl)
 172 {
 173         atomic_inc(&gl->gl_ref);
 174 }
 175
 176 /**
 177  * gfs2_glock_put() - Decrement reference count on glock
 178  * @gl: The glock to put
 179  *
 180  */
 181
 182 int gfs2_glock_put(struct gfs2_glock *gl)
 183 {
 184         int rv = 0;
 185
 186         write_lock(gl_lock_addr(gl->gl_hash));
 187         if (atomic_dec_and_test(&gl->gl_ref)) {
 188                 hlist_del(&gl->gl_list);
 189                 write_unlock(gl_lock_addr(gl->gl_hash));
 190                 GLOCK_BUG_ON(gl, gl->gl_state != LM_ST_UNLOCKED);
 191                 GLOCK_BUG_ON(gl, !list_empty(&gl->gl_reclaim));
 192                 GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
 193                 glock_free(gl);
 194                 rv = 1;
 195                 goto out;
 196         }
 197         write_unlock(gl_lock_addr(gl->gl_hash));
 198 out:
 199         return rv;
 200 }
 201
 202 /**
 203  * search_bucket() - Find struct gfs2_glock by lock number
 204  * @bucket: the bucket to search
 205  * @name: The lock name
 206  *
 207  * Returns: NULL, or the struct gfs2_glock with the requested number
 208  */
 209
 210 static struct gfs2_glock *search_bucket(unsigned int hash,
 211                                         const struct gfs2_sbd *sdp,
 212                                         const struct lm_lockname *name)
 213 {
 214         struct gfs2_glock *gl;
 215         struct hlist_node *h;
 216
 217         hlist_for_each_entry(gl, h, &gl_hash_table[hash].hb_list, gl_list) {
 218                 if (!lm_name_equal(&gl->gl_name, name))
 219                         continue;
 220                 if (gl->gl_sbd != sdp)
 221                         continue;
 222
 223                 atomic_inc(&gl->gl_ref);
 224
 225                 return gl;
 226         }
 227
 228         return NULL;
 229 }
 230
 231 /**
 232  * gfs2_glock_find() - Find glock by lock number
 233  * @sdp: The GFS2 superblock
 234  * @name: The lock name
 235  *
 236  * Returns: NULL, or the struct gfs2_glock with the requested number
 237  */
 238
 239 static struct gfs2_glock *gfs2_glock_find(const struct gfs2_sbd *sdp,
 240                                           const struct lm_lockname *name)
 241 {
 242         unsigned int hash = gl_hash(sdp, name);
 243         struct gfs2_glock *gl;
 244
 245         read_lock(gl_lock_addr(hash));
 246         gl = search_bucket(hash, sdp, name);
 247         read_unlock(gl_lock_addr(hash));
 248
 249         return gl;
 250 }
 251
 252 /**
 253  * may_grant - check if its ok to grant a new lock
 254  * @gl: The glock
 255  * @gh: The lock request which we wish to grant
 256  *
 257  * Returns: true if its ok to grant the lock
 258  */
 259
 260 static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
 261 {
 262         const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
 263         if ((gh->gh_state == LM_ST_EXCLUSIVE ||
 264              gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
 265                 return 0;
 266         if (gl->gl_state == gh->gh_state)
 267                 return 1;
 268         if (gh->gh_flags & GL_EXACT)
 269                 return 0;
 270         if (gl->gl_state == LM_ST_EXCLUSIVE) {
 271                 if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
 272                         return 1;
 273                 if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
 274                         return 1;
 275         }
 276         if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
 277                 return 1;
 278         return 0;
 279 }
 280
 281 static void gfs2_holder_wake(struct gfs2_holder *gh)
 282 {
 283         clear_bit(HIF_WAIT, &gh->gh_iflags);
 284         smp_mb__after_clear_bit();
 285         wake_up_bit(&gh->gh_iflags, HIF_WAIT);
 286 }
 287
 288 /**
 289  * do_promote - promote as many requests as possible on the current queue
 290  * @gl: The glock
 291  *
 292  * Returns: true if there is a blocked holder at the head of the list
 293  */
 294
 295 static int do_promote(struct gfs2_glock *gl)
 296 {
 297         const struct gfs2_glock_operations *glops = gl->gl_ops;
 298         struct gfs2_holder *gh, *tmp;
 299         int ret;
 300
 301 restart:
 302         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 303                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 304                         continue;
 305                 if (may_grant(gl, gh)) {
 306                         if (gh->gh_list.prev == &gl->gl_holders &&
 307                             glops->go_lock) {
 308                                 spin_unlock(&gl->gl_spin);
 309                                 /* FIXME: eliminate this eventually */
 310                                 ret = glops->go_lock(gh);
 311                                 spin_lock(&gl->gl_spin);
 312                                 if (ret) {
 313                                         gh->gh_error = ret;
 314                                         list_del_init(&gh->gh_list);
 315                                         gfs2_holder_wake(gh);
 316                                         goto restart;
 317                                 }
 318                                 set_bit(HIF_HOLDER, &gh->gh_iflags);
 319                                 gfs2_holder_wake(gh);
 320                                 goto restart;
 321                         }
 322                         set_bit(HIF_HOLDER, &gh->gh_iflags);
 323                         gfs2_holder_wake(gh);
 324                         continue;
 325                 }
 326                 if (gh->gh_list.prev == &gl->gl_holders)
 327                         return 1;
 328                 break;
 329         }
 330         return 0;
 331 }
 332
 333 /**
 334  * do_error - Something unexpected has happened during a lock request
 335  *
 336  */
 337
 338 static inline void do_error(struct gfs2_glock *gl, const int ret)
 339 {
 340         struct gfs2_holder *gh, *tmp;
 341
 342         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 343                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 344                         continue;
 345                 if (ret & LM_OUT_ERROR)
 346                         gh->gh_error = -EIO;
 347                 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
 348                         gh->gh_error = GLR_TRYFAILED;
 349                 else
 350                         continue;
 351                 list_del_init(&gh->gh_list);
 352                 gfs2_holder_wake(gh);
 353         }
 354 }
 355
 356 /**
 357  * find_first_waiter - find the first gh that's waiting for the glock
 358  * @gl: the glock
 359  */
 360
 361 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
 362 {
 363         struct gfs2_holder *gh;
 364
 365         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
 366                 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
 367                         return gh;
 368         }
 369         return NULL;
 370 }
 371
 372 /**
 373  * state_change - record that the glock is now in a different state
 374  * @gl: the glock
 375  * @new_state the new state
 376  *
 377  */
 378
 379 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 380 {
 381         int held1, held2;
 382
 383         held1 = (gl->gl_state != LM_ST_UNLOCKED);
 384         held2 = (new_state != LM_ST_UNLOCKED);
 385
 386         if (held1 != held2) {
 387                 if (held2)
 388                         gfs2_glock_hold(gl);
 389                 else
 390                         gfs2_glock_put(gl);
 391         }
 392
 393         gl->gl_state = new_state;
 394         gl->gl_tchange = jiffies;
 395 }
 396
 397 static void gfs2_demote_wake(struct gfs2_glock *gl)
 398 {
 399         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 400         clear_bit(GLF_DEMOTE, &gl->gl_flags);
 401         smp_mb__after_clear_bit();
 402         wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
 403 }
 404
 405 /**
 406  * finish_xmote - The DLM has replied to one of our lock requests
 407  * @gl: The glock
 408  * @ret: The status from the DLM
 409  *
 410  */
 411
 412 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
 413 {
 414         const struct gfs2_glock_operations *glops = gl->gl_ops;
 415         struct gfs2_holder *gh;
 416         unsigned state = ret & LM_OUT_ST_MASK;
 417
 418         spin_lock(&gl->gl_spin);
 419         state_change(gl, state);
 420         gh = find_first_waiter(gl);
 421
 422         /* Demote to UN request arrived during demote to SH or DF */
 423         if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
 424             state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
 425                 gl->gl_target = LM_ST_UNLOCKED;
 426
 427         /* Check for state != intended state */
 428         if (unlikely(state != gl->gl_target)) {
 429                 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
 430                         /* move to back of queue and try next entry */
 431                         if (ret & LM_OUT_CANCELED) {
 432                                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
 433                                         list_move_tail(&gh->gh_list, &gl->gl_holders);
 434                                 gh = find_first_waiter(gl);
 435                                 gl->gl_target = gh->gh_state;
 436                                 goto retry;
 437                         }
 438                         /* Some error or failed "try lock" - report it */
 439                         if ((ret & LM_OUT_ERROR) ||
 440                             (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 441                                 gl->gl_target = gl->gl_state;
 442                                 do_error(gl, ret);
 443                                 goto out;
 444                         }
 445                 }
 446                 switch(state) {
 447                 /* Unlocked due to conversion deadlock, try again */
 448                 case LM_ST_UNLOCKED:
 449 retry:
 450                         do_xmote(gl, gh, gl->gl_target);
 451                         break;
 452                 /* Conversion fails, unlock and try again */
 453                 case LM_ST_SHARED:
 454                 case LM_ST_DEFERRED:
 455                         do_xmote(gl, gh, LM_ST_UNLOCKED);
 456                         break;
 457                 default: /* Everything else */
 458                         printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
 459                         GLOCK_BUG_ON(gl, 1);
 460                 }
 461                 spin_unlock(&gl->gl_spin);
 462                 gfs2_glock_put(gl);
 463                 return;
 464         }
 465
 466         /* Fast path - we got what we asked for */
 467         if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
 468                 gfs2_demote_wake(gl);
 469         if (state != LM_ST_UNLOCKED) {
 470                 if (glops->go_xmote_bh) {
 471                         int rv;
 472                         spin_unlock(&gl->gl_spin);
 473                         rv = glops->go_xmote_bh(gl, gh);
 474                         if (rv == -EAGAIN)
 475                                 return;
 476                         spin_lock(&gl->gl_spin);
 477                         if (rv) {
 478                                 do_error(gl, rv);
 479                                 goto out;
 480                         }
 481                 }
 482                 do_promote(gl);
 483         }
 484 out:
 485         clear_bit(GLF_LOCK, &gl->gl_flags);
 486         spin_unlock(&gl->gl_spin);
 487         gfs2_glock_put(gl);
 488 }
 489
 490 static unsigned int gfs2_lm_lock(struct gfs2_sbd *sdp, void *lock,
 491                                  unsigned int cur_state, unsigned int req_state,
 492                                  unsigned int flags)
 493 {
 494         int ret = LM_OUT_ERROR;
 495
 496         if (!sdp->sd_lockstruct.ls_ops->lm_lock)
 497                 return req_state == LM_ST_UNLOCKED ? 0 : req_state;
 498
 499         if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 500                 ret = sdp->sd_lockstruct.ls_ops->lm_lock(lock, cur_state,
 501                                                          req_state, flags);
 502         return ret;
 503 }
 504
 505 /**
 506  * do_xmote - Calls the DLM to change the state of a lock
 507  * @gl: The lock state
 508  * @gh: The holder (only for promotes)
 509  * @target: The target lock state
 510  *
 511  */
 512
 513 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
 514 {
 515         const struct gfs2_glock_operations *glops = gl->gl_ops;
 516         struct gfs2_sbd *sdp = gl->gl_sbd;
 517         unsigned int lck_flags = gh ? gh->gh_flags : 0;
 518         int ret;
 519
 520         lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
 521                       LM_FLAG_PRIORITY);
 522         BUG_ON(gl->gl_state == target);
 523         BUG_ON(gl->gl_state == gl->gl_target);
 524         if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
 525             glops->go_inval) {
 526                 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 527                 do_error(gl, 0); /* Fail queued try locks */
 528         }
 529         spin_unlock(&gl->gl_spin);
 530         if (glops->go_xmote_th)
 531                 glops->go_xmote_th(gl);
 532         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 533                 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
 534         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 535
 536         gfs2_glock_hold(gl);
 537         if (target != LM_ST_UNLOCKED && (gl->gl_state == LM_ST_SHARED ||
 538             gl->gl_state == LM_ST_DEFERRED) &&
 539             !(lck_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 540                 lck_flags |= LM_FLAG_TRY_1CB;
 541         ret = gfs2_lm_lock(sdp, gl->gl_lock, gl->gl_state, target, lck_flags);
 542
 543         if (!(ret & LM_OUT_ASYNC)) {
 544                 finish_xmote(gl, ret);
 545                 gfs2_glock_hold(gl);
 546                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 547                         gfs2_glock_put(gl);
 548         } else {
 549                 GLOCK_BUG_ON(gl, ret != LM_OUT_ASYNC);
 550         }
 551         spin_lock(&gl->gl_spin);
 552 }
 553
 554 /**
 555  * find_first_holder - find the first "holder" gh
 556  * @gl: the glock
 557  */
 558
 559 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
 560 {
 561         struct gfs2_holder *gh;
 562
 563         if (!list_empty(&gl->gl_holders)) {
 564                 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 565                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 566                         return gh;
 567         }
 568         return NULL;
 569 }
 570
 571 /**
 572  * run_queue - do all outstanding tasks related to a glock
 573  * @gl: The glock in question
 574  * @nonblock: True if we must not block in run_queue
 575  *
 576  */
 577
 578 static void run_queue(struct gfs2_glock *gl, const int nonblock)
 579 {
 580         struct gfs2_holder *gh = NULL;
 581
 582         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 583                 return;
 584
 585         GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
 586
 587         if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
 588             gl->gl_demote_state != gl->gl_state) {
 589                 if (find_first_holder(gl))
 590                         goto out;
 591                 if (nonblock)
 592                         goto out_sched;
 593                 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
 594                 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
 595                 gl->gl_target = gl->gl_demote_state;
 596         } else {
 597                 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
 598                         gfs2_demote_wake(gl);
 599                 if (do_promote(gl) == 0)
 600                         goto out;
 601                 gh = find_first_waiter(gl);
 602                 gl->gl_target = gh->gh_state;
 603                 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 604                         do_error(gl, 0); /* Fail queued try locks */
 605         }
 606         do_xmote(gl, gh, gl->gl_target);
 607         return;
 608
 609 out_sched:
 610         gfs2_glock_hold(gl);
 611         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 612                 gfs2_glock_put(gl);
 613 out:
 614         clear_bit(GLF_LOCK, &gl->gl_flags);
 615 }
 616
 617 static void glock_work_func(struct work_struct *work)
 618 {
 619         unsigned long delay = 0;
 620         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
 621
 622         if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags))
 623                 finish_xmote(gl, gl->gl_reply);
 624         spin_lock(&gl->gl_spin);
 625         if (test_and_clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
 626             gl->gl_state != LM_ST_UNLOCKED &&
 627             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
 628                 unsigned long holdtime, now = jiffies;
 629                 holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
 630                 if (time_before(now, holdtime))
 631                         delay = holdtime - now;
 632                 set_bit(delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE, &gl->gl_flags);
 633         }
 634         run_queue(gl, 0);
 635         spin_unlock(&gl->gl_spin);
 636         if (!delay ||
 637             queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
 638                 gfs2_glock_put(gl);
 639 }
 640
 641 static int gfs2_lm_get_lock(struct gfs2_sbd *sdp, struct lm_lockname *name,
 642                      void **lockp)
 643 {
 644         int error = -EIO;
 645         if (!sdp->sd_lockstruct.ls_ops->lm_get_lock)
 646                 return 0;
 647         if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 648                 error = sdp->sd_lockstruct.ls_ops->lm_get_lock(
 649                                 sdp->sd_lockstruct.ls_lockspace, name, lockp);
 650         return error;
 651 }
 652
 653 /**
 654  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
 655  * @sdp: The GFS2 superblock
 656  * @number: the lock number
 657  * @glops: The glock_operations to use
 658  * @create: If 0, don't create the glock if it doesn't exist
 659  * @glp: the glock is returned here
 660  *
 661  * This does not lock a glock, just finds/creates structures for one.
 662  *
 663  * Returns: errno
 664  */
 665
 666 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 667                    const struct gfs2_glock_operations *glops, int create,
 668                    struct gfs2_glock **glp)
 669 {
 670         struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
 671         struct gfs2_glock *gl, *tmp;
 672         unsigned int hash = gl_hash(sdp, &name);
 673         int error;
 674
 675         read_lock(gl_lock_addr(hash));
 676         gl = search_bucket(hash, sdp, &name);
 677         read_unlock(gl_lock_addr(hash));
 678
 679         if (gl || !create) {
 680                 *glp = gl;
 681                 return 0;
 682         }
 683
 684         gl = kmem_cache_alloc(gfs2_glock_cachep, GFP_KERNEL);
 685         if (!gl)
 686                 return -ENOMEM;
 687
 688         gl->gl_flags = 0;
 689         gl->gl_name = name;
 690         atomic_set(&gl->gl_ref, 1);
 691         gl->gl_state = LM_ST_UNLOCKED;
 692         gl->gl_target = LM_ST_UNLOCKED;
 693         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 694         gl->gl_hash = hash;
 695         gl->gl_ops = glops;
 696         gl->gl_stamp = jiffies;
 697         gl->gl_tchange = jiffies;
 698         gl->gl_object = NULL;
 699         gl->gl_sbd = sdp;
 700         gl->gl_aspace = NULL;
 701         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
 702
 703         /* If this glock protects actual on-disk data or metadata blocks,
 704            create a VFS inode to manage the pages/buffers holding them. */
 705         if (glops == &gfs2_inode_glops || glops == &gfs2_rgrp_glops) {
 706                 gl->gl_aspace = gfs2_aspace_get(sdp);
 707                 if (!gl->gl_aspace) {
 708                         error = -ENOMEM;
 709                         goto fail;
 710                 }
 711         }
 712
 713         error = gfs2_lm_get_lock(sdp, &name, &gl->gl_lock);
 714         if (error)
 715                 goto fail_aspace;
 716
 717         write_lock(gl_lock_addr(hash));
 718         tmp = search_bucket(hash, sdp, &name);
 719         if (tmp) {
 720                 write_unlock(gl_lock_addr(hash));
 721                 glock_free(gl);
 722                 gl = tmp;
 723         } else {
 724                 hlist_add_head(&gl->gl_list, &gl_hash_table[hash].hb_list);
 725                 write_unlock(gl_lock_addr(hash));
 726         }
 727
 728         *glp = gl;
 729
 730         return 0;
 731
 732 fail_aspace:
 733         if (gl->gl_aspace)
 734                 gfs2_aspace_put(gl->gl_aspace);
 735 fail:
 736         kmem_cache_free(gfs2_glock_cachep, gl);
 737         return error;
 738 }
 739
 740 /**
 741  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
 742  * @gl: the glock
 743  * @state: the state we're requesting
 744  * @flags: the modifier flags
 745  * @gh: the holder structure
 746  *
 747  */
 748
 749 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
 750                       struct gfs2_holder *gh)
 751 {
 752         INIT_LIST_HEAD(&gh->gh_list);
 753         gh->gh_gl = gl;
 754         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 755         gh->gh_owner_pid = get_pid(task_pid(current));
 756         gh->gh_state = state;
 757         gh->gh_flags = flags;
 758         gh->gh_error = 0;
 759         gh->gh_iflags = 0;
 760         gfs2_glock_hold(gl);
 761 }
 762
 763 /**
 764  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
 765  * @state: the state we're requesting
 766  * @flags: the modifier flags
 767  * @gh: the holder structure
 768  *
 769  * Don't mess with the glock.
 770  *
 771  */
 772
 773 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
 774 {
 775         gh->gh_state = state;
 776         gh->gh_flags = flags;
 777         gh->gh_iflags = 0;
 778         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 779 }
 780
 781 /**
 782  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 783  * @gh: the holder structure
 784  *
 785  */
 786
 787 void gfs2_holder_uninit(struct gfs2_holder *gh)
 788 {
 789         put_pid(gh->gh_owner_pid);
 790         gfs2_glock_put(gh->gh_gl);
 791         gh->gh_gl = NULL;
 792         gh->gh_ip = 0;
 793 }
 794
 795 static int just_schedule(void *word)
 796 {
 797         schedule();
 798         return 0;
 799 }
 800
 801 static void wait_on_holder(struct gfs2_holder *gh)
 802 {
 803         might_sleep();
 804         wait_on_bit(&gh->gh_iflags, HIF_WAIT, just_schedule, TASK_UNINTERRUPTIBLE);
 805 }
 806
 807 static void wait_on_demote(struct gfs2_glock *gl)
 808 {
 809         might_sleep();
 810         wait_on_bit(&gl->gl_flags, GLF_DEMOTE, just_schedule, TASK_UNINTERRUPTIBLE);
 811 }
 812
 813 /**
 814  * handle_callback - process a demote request
 815  * @gl: the glock
 816  * @state: the state the caller wants us to change to
 817  *
 818  * There are only two requests that we are going to see in actual
 819  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
 820  */
 821
 822 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
 823                             int remote, unsigned long delay)
 824 {
 825         int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
 826
 827         set_bit(bit, &gl->gl_flags);
 828         if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
 829                 gl->gl_demote_state = state;
 830                 gl->gl_demote_time = jiffies;
 831                 if (remote && gl->gl_ops->go_type == LM_TYPE_IOPEN &&
 832                     gl->gl_object)
 833                         gfs2_glock_schedule_for_reclaim(gl);
 834         } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
 835                         gl->gl_demote_state != state) {
 836                 gl->gl_demote_state = LM_ST_UNLOCKED;
 837         }
 838 }
 839
 840 /**
 841  * gfs2_glock_wait - wait on a glock acquisition
 842  * @gh: the glock holder
 843  *
 844  * Returns: 0 on success
 845  */
 846
 847 int gfs2_glock_wait(struct gfs2_holder *gh)
 848 {
 849         wait_on_holder(gh);
 850         return gh->gh_error;
 851 }
 852
 853 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
 854 {
 855         va_list args;
 856
 857         va_start(args, fmt);
 858         if (seq) {
 859                 struct gfs2_glock_iter *gi = seq->private;
 860                 vsprintf(gi->string, fmt, args);
 861                 seq_printf(seq, gi->string);
 862         } else {
 863                 printk(KERN_ERR " ");
 864                 vprintk(fmt, args);
 865         }
 866         va_end(args);
 867 }
 868
 869 /**
 870  * add_to_queue - Add a holder to the wait queue (but look for recursion)
 871  * @gh: the holder structure to add
 872  *
 873  * Eventually we should move the recursive locking trap to a
 874  * debugging option or something like that. This is the fast
 875  * path and needs to have the minimum number of distractions.
 876  *
 877  */
 878
 879 static inline void add_to_queue(struct gfs2_holder *gh)
 880 {
 881         struct gfs2_glock *gl = gh->gh_gl;
 882         struct gfs2_sbd *sdp = gl->gl_sbd;
 883         struct list_head *insert_pt = NULL;
 884         struct gfs2_holder *gh2;
 885         int try_lock = 0;
 886
 887         BUG_ON(gh->gh_owner_pid == NULL);
 888         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
 889                 BUG();
 890
 891         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
 892                 if (test_bit(GLF_LOCK, &gl->gl_flags))
 893                         try_lock = 1;
 894                 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 895                         goto fail;
 896         }
 897
 898         list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
 899                 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
 900                     (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
 901                         goto trap_recursive;
 902                 if (try_lock &&
 903                     !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
 904                     !may_grant(gl, gh)) {
 905 fail:
 906                         gh->gh_error = GLR_TRYFAILED;
 907                         gfs2_holder_wake(gh);
 908                         return;
 909                 }
 910                 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
 911                         continue;
 912                 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
 913                         insert_pt = &gh2->gh_list;
 914         }
 915         if (likely(insert_pt == NULL)) {
 916                 list_add_tail(&gh->gh_list, &gl->gl_holders);
 917                 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
 918                         goto do_cancel;
 919                 return;
 920         }
 921         list_add_tail(&gh->gh_list, insert_pt);
 922 do_cancel:
 923         gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 924         if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
 925                 spin_unlock(&gl->gl_spin);
 926                 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
 927                         sdp->sd_lockstruct.ls_ops->lm_cancel(gl->gl_lock);
 928                 spin_lock(&gl->gl_spin);
 929         }
 930         return;
 931
 932 trap_recursive:
 933         print_symbol(KERN_ERR "original: %s\n", gh2->gh_ip);
 934         printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
 935         printk(KERN_ERR "lock type: %d req lock state : %d\n",
 936                gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
 937         print_symbol(KERN_ERR "new: %s\n", gh->gh_ip);
 938         printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
 939         printk(KERN_ERR "lock type: %d req lock state : %d\n",
 940                gh->gh_gl->gl_name.ln_type, gh->gh_state);
 941         __dump_glock(NULL, gl);
 942         BUG();
 943 }
 944
 945 /**
 946  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
 947  * @gh: the holder structure
 948  *
 949  * if (gh->gh_flags & GL_ASYNC), this never returns an error
 950  *
 951  * Returns: 0, GLR_TRYFAILED, or errno on failure
 952  */
 953
 954 int gfs2_glock_nq(struct gfs2_holder *gh)
 955 {
 956         struct gfs2_glock *gl = gh->gh_gl;
 957         struct gfs2_sbd *sdp = gl->gl_sbd;
 958         int error = 0;
 959
 960         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 961                 return -EIO;
 962
 963         spin_lock(&gl->gl_spin);
 964         add_to_queue(gh);
 965         run_queue(gl, 1);
 966         spin_unlock(&gl->gl_spin);
 967
 968         if (!(gh->gh_flags & GL_ASYNC))
 969                 error = gfs2_glock_wait(gh);
 970
 971         return error;
 972 }
 973
 974 /**
 975  * gfs2_glock_poll - poll to see if an async request has been completed
 976  * @gh: the holder
 977  *
 978  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
 979  */
 980
 981 int gfs2_glock_poll(struct gfs2_holder *gh)
 982 {
 983         return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
 984 }
 985
 986 /**
 987  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
 988  * @gh: the glock holder
 989  *
 990  */
 991
 992 void gfs2_glock_dq(struct gfs2_holder *gh)
 993 {
 994         struct gfs2_glock *gl = gh->gh_gl;
 995         const struct gfs2_glock_operations *glops = gl->gl_ops;
 996         unsigned delay = 0;
 997         int fast_path = 0;
 998
 999         spin_lock(&gl->gl_spin);
1000         if (gh->gh_flags & GL_NOCACHE)
1001                 handle_callback(gl, LM_ST_UNLOCKED, 0, 0);
1002
1003         list_del_init(&gh->gh_list);
1004         if (find_first_holder(gl) == NULL) {
1005                 if (glops->go_unlock) {
1006                         GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1007                         spin_unlock(&gl->gl_spin);
1008                         glops->go_unlock(gh);
1009                         spin_lock(&gl->gl_spin);
1010                         clear_bit(GLF_LOCK, &gl->gl_flags);
1011                 }
1012                 gl->gl_stamp = jiffies;
1013                 if (list_empty(&gl->gl_holders) &&
1014                     !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1015                     !test_bit(GLF_DEMOTE, &gl->gl_flags))
1016                         fast_path = 1;
1017         }
1018         spin_unlock(&gl->gl_spin);
1019         if (likely(fast_path))
1020                 return;
1021
1022         gfs2_glock_hold(gl);
1023         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1024             !test_bit(GLF_DEMOTE, &gl->gl_flags))
1025                 delay = gl->gl_ops->go_min_hold_time;
1026         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1027                 gfs2_glock_put(gl);
1028 }
1029
1030 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1031 {
1032         struct gfs2_glock *gl = gh->gh_gl;
1033         gfs2_glock_dq(gh);
1034         wait_on_demote(gl);
1035 }
1036
1037 /**
1038  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1039  * @gh: the holder structure
1040  *
1041  */
1042
1043 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1044 {
1045         gfs2_glock_dq(gh);
1046         gfs2_holder_uninit(gh);
1047 }
1048
1049 /**
1050  * gfs2_glock_nq_num - acquire a glock based on lock number
1051  * @sdp: the filesystem
1052  * @number: the lock number
1053  * @glops: the glock operations for the type of glock
1054  * @state: the state to acquire the glock in
1055  * @flags: modifier flags for the aquisition
1056  * @gh: the struct gfs2_holder
1057  *
1058  * Returns: errno
1059  */
1060
1061 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1062                       const struct gfs2_glock_operations *glops,
1063                       unsigned int state, int flags, struct gfs2_holder *gh)
1064 {
1065         struct gfs2_glock *gl;
1066         int error;
1067
1068         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1069         if (!error) {
1070                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1071                 gfs2_glock_put(gl);
1072         }
1073
1074         return error;
1075 }
1076
1077 /**
1078  * glock_compare - Compare two struct gfs2_glock structures for sorting
1079  * @arg_a: the first structure
1080  * @arg_b: the second structure
1081  *
1082  */
1083
1084 static int glock_compare(const void *arg_a, const void *arg_b)
1085 {
1086         const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1087         const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1088         const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1089         const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1090
1091         if (a->ln_number > b->ln_number)
1092                 return 1;
1093         if (a->ln_number < b->ln_number)
1094                 return -1;
1095         BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1096         return 0;
1097 }
1098
1099 /**
1100  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1101  * @num_gh: the number of structures
1102  * @ghs: an array of struct gfs2_holder structures
1103  *
1104  * Returns: 0 on success (all glocks acquired),
1105  *          errno on failure (no glocks acquired)
1106  */
1107
1108 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1109                      struct gfs2_holder **p)
1110 {
1111         unsigned int x;
1112         int error = 0;
1113
1114         for (x = 0; x < num_gh; x++)
1115                 p[x] = &ghs[x];
1116
1117         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1118
1119         for (x = 0; x < num_gh; x++) {
1120                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1121
1122                 error = gfs2_glock_nq(p[x]);
1123                 if (error) {
1124                         while (x--)
1125                                 gfs2_glock_dq(p[x]);
1126                         break;
1127                 }
1128         }
1129
1130         return error;
1131 }
1132
1133 /**
1134  * gfs2_glock_nq_m - acquire multiple glocks
1135  * @num_gh: the number of structures
1136  * @ghs: an array of struct gfs2_holder structures
1137  *
1138  *
1139  * Returns: 0 on success (all glocks acquired),
1140  *          errno on failure (no glocks acquired)
1141  */
1142
1143 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1144 {
1145         struct gfs2_holder *tmp[4];
1146         struct gfs2_holder **pph = tmp;
1147         int error = 0;
1148
1149         switch(num_gh) {
1150         case 0:
1151                 return 0;
1152         case 1:
1153                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1154                 return gfs2_glock_nq(ghs);
1155         default:
1156                 if (num_gh <= 4)
1157                         break;
1158                 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1159                 if (!pph)
1160                         return -ENOMEM;
1161         }
1162
1163         error = nq_m_sync(num_gh, ghs, pph);
1164
1165         if (pph != tmp)
1166                 kfree(pph);
1167
1168         return error;
1169 }
1170
1171 /**
1172  * gfs2_glock_dq_m - release multiple glocks
1173  * @num_gh: the number of structures
1174  * @ghs: an array of struct gfs2_holder structures
1175  *
1176  */
1177
1178 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1179 {
1180         unsigned int x;
1181
1182         for (x = 0; x < num_gh; x++)
1183                 gfs2_glock_dq(&ghs[x]);
1184 }
1185
1186 /**
1187  * gfs2_glock_dq_uninit_m - release multiple glocks
1188  * @num_gh: the number of structures
1189  * @ghs: an array of struct gfs2_holder structures
1190  *
1191  */
1192
1193 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1194 {
1195         unsigned int x;
1196
1197         for (x = 0; x < num_gh; x++)
1198                 gfs2_glock_dq_uninit(&ghs[x]);
1199 }
1200
1201 static int gfs2_lm_hold_lvb(struct gfs2_sbd *sdp, void *lock, char **lvbp)
1202 {
1203         int error = -EIO;
1204         if (!sdp->sd_lockstruct.ls_ops->lm_hold_lvb)
1205                 return 0;
1206         if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
1207                 error = sdp->sd_lockstruct.ls_ops->lm_hold_lvb(lock, lvbp);
1208         return error;
1209 }
1210
1211 /**
1212  * gfs2_lvb_hold - attach a LVB from a glock
1213  * @gl: The glock in question
1214  *
1215  */
1216
1217 int gfs2_lvb_hold(struct gfs2_glock *gl)
1218 {
1219         int error;
1220
1221         if (!atomic_read(&gl->gl_lvb_count)) {
1222                 error = gfs2_lm_hold_lvb(gl->gl_sbd, gl->gl_lock, &gl->gl_lvb);
1223                 if (error)
1224                         return error;
1225                 gfs2_glock_hold(gl);
1226         }
1227         atomic_inc(&gl->gl_lvb_count);
1228
1229         return 0;
1230 }
1231
1232 /**
1233  * gfs2_lvb_unhold - detach a LVB from a glock
1234  * @gl: The glock in question
1235  *
1236  */
1237
1238 void gfs2_lvb_unhold(struct gfs2_glock *gl)
1239 {
1240         struct gfs2_sbd *sdp = gl->gl_sbd;
1241
1242         gfs2_glock_hold(gl);
1243         gfs2_assert(gl->gl_sbd, atomic_read(&gl->gl_lvb_count) > 0);
1244         if (atomic_dec_and_test(&gl->gl_lvb_count)) {
1245                 if (sdp->sd_lockstruct.ls_ops->lm_unhold_lvb)
1246                         sdp->sd_lockstruct.ls_ops->lm_unhold_lvb(gl->gl_lock, gl->gl_lvb);
1247                 gl->gl_lvb = NULL;
1248                 gfs2_glock_put(gl);
1249         }
1250         gfs2_glock_put(gl);
1251 }
1252
1253 static void blocking_cb(struct gfs2_sbd *sdp, struct lm_lockname *name,
1254                         unsigned int state)
1255 {
1256         struct gfs2_glock *gl;
1257         unsigned long delay = 0;
1258         unsigned long holdtime;
1259         unsigned long now = jiffies;
1260
1261         gl = gfs2_glock_find(sdp, name);
1262         if (!gl)
1263                 return;
1264
1265         holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
1266         if (time_before(now, holdtime))
1267                 delay = holdtime - now;
1268
1269         spin_lock(&gl->gl_spin);
1270         handle_callback(gl, state, 1, delay);
1271         spin_unlock(&gl->gl_spin);
1272         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1273                 gfs2_glock_put(gl);
1274 }
1275
1276 /**
1277  * gfs2_glock_cb - Callback used by locking module
1278  * @sdp: Pointer to the superblock
1279  * @type: Type of callback
1280  * @data: Type dependent data pointer
1281  *
1282  * Called by the locking module when it wants to tell us something.
1283  * Either we need to drop a lock, one of our ASYNC requests completed, or
1284  * a journal from another client needs to be recovered.
1285  */
1286
1287 void gfs2_glock_cb(void *cb_data, unsigned int type, void *data)
1288 {
1289         struct gfs2_sbd *sdp = cb_data;
1290
1291         switch (type) {
1292         case LM_CB_NEED_E:
1293                 blocking_cb(sdp, data, LM_ST_UNLOCKED);
1294                 return;
1295
1296         case LM_CB_NEED_D:
1297                 blocking_cb(sdp, data, LM_ST_DEFERRED);
1298                 return;
1299
1300         case LM_CB_NEED_S:
1301                 blocking_cb(sdp, data, LM_ST_SHARED);
1302                 return;
1303
1304         case LM_CB_ASYNC: {
1305                 struct lm_async_cb *async = data;
1306                 struct gfs2_glock *gl;
1307
1308                 down_read(&gfs2_umount_flush_sem);
1309                 gl = gfs2_glock_find(sdp, &async->lc_name);
1310                 if (gfs2_assert_warn(sdp, gl))
1311                         return;
1312                 gl->gl_reply = async->lc_ret;
1313                 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1314                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1315                         gfs2_glock_put(gl);
1316                 up_read(&gfs2_umount_flush_sem);
1317                 return;
1318         }
1319
1320         case LM_CB_NEED_RECOVERY:
1321                 gfs2_jdesc_make_dirty(sdp, *(unsigned int *)data);
1322                 if (sdp->sd_recoverd_process)
1323                         wake_up_process(sdp->sd_recoverd_process);
1324                 return;
1325
1326         default:
1327                 gfs2_assert_warn(sdp, 0);
1328                 return;
1329         }
1330 }
1331
1332 /**
1333  * demote_ok - Check to see if it's ok to unlock a glock
1334  * @gl: the glock
1335  *
1336  * Returns: 1 if it's ok
1337  */
1338
1339 static int demote_ok(struct gfs2_glock *gl)
1340 {
1341         const struct gfs2_glock_operations *glops = gl->gl_ops;
1342         int demote = 1;
1343
1344         if (test_bit(GLF_STICKY, &gl->gl_flags))
1345                 demote = 0;
1346         else if (glops->go_demote_ok)
1347                 demote = glops->go_demote_ok(gl);
1348
1349         return demote;
1350 }
1351
1352 /**
1353  * gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
1354  * @gl: the glock
1355  *
1356  */
1357
1358 void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
1359 {
1360         struct gfs2_sbd *sdp = gl->gl_sbd;
1361
1362         spin_lock(&sdp->sd_reclaim_lock);
1363         if (list_empty(&gl->gl_reclaim)) {
1364                 gfs2_glock_hold(gl);
1365                 list_add(&gl->gl_reclaim, &sdp->sd_reclaim_list);
1366                 atomic_inc(&sdp->sd_reclaim_count);
1367                 spin_unlock(&sdp->sd_reclaim_lock);
1368                 wake_up(&sdp->sd_reclaim_wq);
1369         } else
1370                 spin_unlock(&sdp->sd_reclaim_lock);
1371 }
1372
1373 /**
1374  * gfs2_reclaim_glock - process the next glock on the filesystem's reclaim list
1375  * @sdp: the filesystem
1376  *
1377  * Called from gfs2_glockd() glock reclaim daemon, or when promoting a
1378  * different glock and we notice that there are a lot of glocks in the
1379  * reclaim list.
1380  *
1381  */
1382
1383 void gfs2_reclaim_glock(struct gfs2_sbd *sdp)
1384 {
1385         struct gfs2_glock *gl;
1386         int done_callback = 0;
1387
1388         spin_lock(&sdp->sd_reclaim_lock);
1389         if (list_empty(&sdp->sd_reclaim_list)) {
1390                 spin_unlock(&sdp->sd_reclaim_lock);
1391                 return;
1392         }
1393         gl = list_entry(sdp->sd_reclaim_list.next,
1394                         struct gfs2_glock, gl_reclaim);
1395         list_del_init(&gl->gl_reclaim);
1396         spin_unlock(&sdp->sd_reclaim_lock);
1397
1398         atomic_dec(&sdp->sd_reclaim_count);
1399         atomic_inc(&sdp->sd_reclaimed);
1400
1401         spin_lock(&gl->gl_spin);
1402         if (find_first_holder(gl) == NULL &&
1403             gl->gl_state != LM_ST_UNLOCKED && demote_ok(gl)) {
1404                 handle_callback(gl, LM_ST_UNLOCKED, 0, 0);
1405                 done_callback = 1;
1406         }
1407         spin_unlock(&gl->gl_spin);
1408         if (!done_callback ||
1409             queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1410                 gfs2_glock_put(gl);
1411 }
1412
1413 /**
1414  * examine_bucket - Call a function for glock in a hash bucket
1415  * @examiner: the function
1416  * @sdp: the filesystem
1417  * @bucket: the bucket
1418  *
1419  * Returns: 1 if the bucket has entries
1420  */
1421
1422 static int examine_bucket(glock_examiner examiner, struct gfs2_sbd *sdp,
1423                           unsigned int hash)
1424 {
1425         struct gfs2_glock *gl, *prev = NULL;
1426         int has_entries = 0;
1427         struct hlist_head *head = &gl_hash_table[hash].hb_list;
1428
1429         read_lock(gl_lock_addr(hash));
1430         /* Can't use hlist_for_each_entry - don't want prefetch here */
1431         if (hlist_empty(head))
1432                 goto out;
1433         gl = list_entry(head->first, struct gfs2_glock, gl_list);
1434         while(1) {
1435                 if (!sdp || gl->gl_sbd == sdp) {
1436                         gfs2_glock_hold(gl);
1437                         read_unlock(gl_lock_addr(hash));
1438                         if (prev)
1439                                 gfs2_glock_put(prev);
1440                         prev = gl;
1441                         examiner(gl);
1442                         has_entries = 1;
1443                         read_lock(gl_lock_addr(hash));
1444                 }
1445                 if (gl->gl_list.next == NULL)
1446                         break;
1447                 gl = list_entry(gl->gl_list.next, struct gfs2_glock, gl_list);
1448         }
1449 out:
1450         read_unlock(gl_lock_addr(hash));
1451         if (prev)
1452                 gfs2_glock_put(prev);
1453         cond_resched();
1454         return has_entries;
1455 }
1456
1457 /**
1458  * scan_glock - look at a glock and see if we can reclaim it
1459  * @gl: the glock to look at
1460  *
1461  */
1462
1463 static void scan_glock(struct gfs2_glock *gl)
1464 {
1465         if (gl->gl_ops == &gfs2_inode_glops && gl->gl_object)
1466                 return;
1467         if (test_bit(GLF_LOCK, &gl->gl_flags))
1468                 return;
1469
1470         spin_lock(&gl->gl_spin);
1471         if (find_first_holder(gl) == NULL &&
1472             gl->gl_state != LM_ST_UNLOCKED && demote_ok(gl))
1473                 gfs2_glock_schedule_for_reclaim(gl);
1474         spin_unlock(&gl->gl_spin);
1475 }
1476
1477 /**
1478  * clear_glock - look at a glock and see if we can free it from glock cache
1479  * @gl: the glock to look at
1480  *
1481  */
1482
1483 static void clear_glock(struct gfs2_glock *gl)
1484 {
1485         struct gfs2_sbd *sdp = gl->gl_sbd;
1486         int released;
1487
1488         spin_lock(&sdp->sd_reclaim_lock);
1489         if (!list_empty(&gl->gl_reclaim)) {
1490                 list_del_init(&gl->gl_reclaim);
1491                 atomic_dec(&sdp->sd_reclaim_count);
1492                 spin_unlock(&sdp->sd_reclaim_lock);
1493                 released = gfs2_glock_put(gl);
1494                 gfs2_assert(sdp, !released);
1495         } else {
1496                 spin_unlock(&sdp->sd_reclaim_lock);
1497         }
1498
1499         spin_lock(&gl->gl_spin);
1500         if (find_first_holder(gl) == NULL && gl->gl_state != LM_ST_UNLOCKED)
1501                 handle_callback(gl, LM_ST_UNLOCKED, 0, 0);
1502         spin_unlock(&gl->gl_spin);
1503         gfs2_glock_hold(gl);
1504         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1505                 gfs2_glock_put(gl);
1506 }
1507
1508 /**
1509  * gfs2_gl_hash_clear - Empty out the glock hash table
1510  * @sdp: the filesystem
1511  * @wait: wait until it's all gone
1512  *
1513  * Called when unmounting the filesystem.
1514  */
1515
1516 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1517 {
1518         unsigned long t;
1519         unsigned int x;
1520         int cont;
1521
1522         t = jiffies;
1523
1524         for (;;) {
1525                 cont = 0;
1526                 for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
1527                         if (examine_bucket(clear_glock, sdp, x))
1528                                 cont = 1;
1529                 }
1530
1531                 if (!cont)
1532                         break;
1533
1534                 if (time_after_eq(jiffies,
1535                                   t + gfs2_tune_get(sdp, gt_stall_secs) * HZ)) {
1536                         fs_warn(sdp, "Unmount seems to be stalled. "
1537                                      "Dumping lock state...\n");
1538                         gfs2_dump_lockstate(sdp);
1539                         t = jiffies;
1540                 }
1541
1542                 down_write(&gfs2_umount_flush_sem);
1543                 invalidate_inodes(sdp->sd_vfs);
1544                 up_write(&gfs2_umount_flush_sem);
1545                 msleep(10);
1546         }
1547 }
1548
1549 static const char *state2str(unsigned state)
1550 {
1551         switch(state) {
1552         case LM_ST_UNLOCKED:
1553                 return "UN";
1554         case LM_ST_SHARED:
1555                 return "SH";
1556         case LM_ST_DEFERRED:
1557                 return "DF";
1558         case LM_ST_EXCLUSIVE:
1559                 return "EX";
1560         }
1561         return "??";
1562 }
1563
1564 static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags)
1565 {
1566         char *p = buf;
1567         if (flags & LM_FLAG_TRY)
1568                 *p++ = 't';
1569         if (flags & LM_FLAG_TRY_1CB)
1570                 *p++ = 'T';
1571         if (flags & LM_FLAG_NOEXP)
1572                 *p++ = 'e';
1573         if (flags & LM_FLAG_ANY)
1574                 *p++ = 'a';
1575         if (flags & LM_FLAG_PRIORITY)
1576                 *p++ = 'p';
1577         if (flags & GL_ASYNC)
1578                 *p++ = 'a';
1579         if (flags & GL_EXACT)
1580                 *p++ = 'E';
1581         if (flags & GL_ATIME)
1582                 *p++ = 'a';
1583         if (flags & GL_NOCACHE)
1584                 *p++ = 'c';
1585         if (test_bit(HIF_HOLDER, &iflags))
1586                 *p++ = 'H';
1587         if (test_bit(HIF_WAIT, &iflags))
1588                 *p++ = 'W';
1589         if (test_bit(HIF_FIRST, &iflags))
1590                 *p++ = 'F';
1591         *p = 0;
1592         return buf;
1593 }
1594
1595 /**
1596  * dump_holder - print information about a glock holder
1597  * @seq: the seq_file struct
1598  * @gh: the glock holder
1599  *
1600  * Returns: 0 on success, -ENOBUFS when we run out of space
1601  */
1602
1603 static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1604 {
1605         struct task_struct *gh_owner = NULL;
1606         char buffer[KSYM_SYMBOL_LEN];
1607         char flags_buf[32];
1608
1609         sprint_symbol(buffer, gh->gh_ip);
1610         if (gh->gh_owner_pid)
1611                 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1612         gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %s\n",
1613                   state2str(gh->gh_state),
1614                   hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1615                   gh->gh_error,
1616                   gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1617                   gh_owner ? gh_owner->comm : "(ended)", buffer);
1618         return 0;
1619 }
1620
1621 static const char *gflags2str(char *buf, const unsigned long *gflags)
1622 {
1623         char *p = buf;
1624         if (test_bit(GLF_LOCK, gflags))
1625                 *p++ = 'l';
1626         if (test_bit(GLF_STICKY, gflags))
1627                 *p++ = 's';
1628         if (test_bit(GLF_DEMOTE, gflags))
1629                 *p++ = 'D';
1630         if (test_bit(GLF_PENDING_DEMOTE, gflags))
1631                 *p++ = 'd';
1632         if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1633                 *p++ = 'p';
1634         if (test_bit(GLF_DIRTY, gflags))
1635                 *p++ = 'y';
1636         if (test_bit(GLF_LFLUSH, gflags))
1637                 *p++ = 'f';
1638         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1639                 *p++ = 'i';
1640         if (test_bit(GLF_REPLY_PENDING, gflags))
1641                 *p++ = 'r';
1642         *p = 0;
1643         return buf;
1644 }
1645
1646 /**
1647  * __dump_glock - print information about a glock
1648  * @seq: The seq_file struct
1649  * @gl: the glock
1650  *
1651  * The file format is as follows:
1652  * One line per object, capital letters are used to indicate objects
1653  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1654  * other objects are indented by a single space and follow the glock to
1655  * which they are related. Fields are indicated by lower case letters
1656  * followed by a colon and the field value, except for strings which are in
1657  * [] so that its possible to see if they are composed of spaces for
1658  * example. The field's are n = number (id of the object), f = flags,
1659  * t = type, s = state, r = refcount, e = error, p = pid.
1660  *
1661  * Returns: 0 on success, -ENOBUFS when we run out of space
1662  */
1663
1664 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1665 {
1666         const struct gfs2_glock_operations *glops = gl->gl_ops;
1667         unsigned long long dtime;
1668         const struct gfs2_holder *gh;
1669         char gflags_buf[32];
1670         int error = 0;
1671
1672         dtime = jiffies - gl->gl_demote_time;
1673         dtime *= 1000000/HZ; /* demote time in uSec */
1674         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1675                 dtime = 0;
1676         gfs2_print_dbg(seq, "G:  s:%s n:%u/%llu f:%s t:%s d:%s/%llu l:%d a:%d r:%d\n",
1677                   state2str(gl->gl_state),
1678                   gl->gl_name.ln_type,
1679                   (unsigned long long)gl->gl_name.ln_number,
1680                   gflags2str(gflags_buf, &gl->gl_flags),
1681                   state2str(gl->gl_target),
1682                   state2str(gl->gl_demote_state), dtime,
1683                   atomic_read(&gl->gl_lvb_count),
1684                   atomic_read(&gl->gl_ail_count),
1685                   atomic_read(&gl->gl_ref));
1686
1687         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1688                 error = dump_holder(seq, gh);
1689                 if (error)
1690                         goto out;
1691         }
1692         if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1693                 error = glops->go_dump(seq, gl);
1694 out:
1695         return error;
1696 }
1697
1698 static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1699 {
1700         int ret;
1701         spin_lock(&gl->gl_spin);
1702         ret = __dump_glock(seq, gl);
1703         spin_unlock(&gl->gl_spin);
1704         return ret;
1705 }
1706
1707 /**
1708  * gfs2_dump_lockstate - print out the current lockstate
1709  * @sdp: the filesystem
1710  * @ub: the buffer to copy the information into
1711  *
1712  * If @ub is NULL, dump the lockstate to the console.
1713  *
1714  */
1715
1716 static int gfs2_dump_lockstate(struct gfs2_sbd *sdp)
1717 {
1718         struct gfs2_glock *gl;
1719         struct hlist_node *h;
1720         unsigned int x;
1721         int error = 0;
1722
1723         for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
1724
1725                 read_lock(gl_lock_addr(x));
1726
1727                 hlist_for_each_entry(gl, h, &gl_hash_table[x].hb_list, gl_list) {
1728                         if (gl->gl_sbd != sdp)
1729                                 continue;
1730
1731                         error = dump_glock(NULL, gl);
1732                         if (error)
1733                                 break;
1734                 }
1735
1736                 read_unlock(gl_lock_addr(x));
1737
1738                 if (error)
1739                         break;
1740         }
1741
1742
1743         return error;
1744 }
1745
1746 /**
1747  * gfs2_scand - Look for cached glocks and inodes to toss from memory
1748  * @sdp: Pointer to GFS2 superblock
1749  *
1750  * One of these daemons runs, finding candidates to add to sd_reclaim_list.
1751  * See gfs2_glockd()
1752  */
1753
1754 static int gfs2_scand(void *data)
1755 {
1756         unsigned x;
1757         unsigned delay;
1758
1759         while (!kthread_should_stop()) {
1760                 for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1761                         examine_bucket(scan_glock, NULL, x);
1762                 if (freezing(current))
1763                         refrigerator();
1764                 delay = scand_secs;
1765                 if (delay < 1)
1766                         delay = 1;
1767                 schedule_timeout_interruptible(delay * HZ);
1768         }
1769
1770         return 0;
1771 }
1772
1773
1774
1775 int __init gfs2_glock_init(void)
1776 {
1777         unsigned i;
1778         for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
1779                 INIT_HLIST_HEAD(&gl_hash_table[i].hb_list);
1780         }
1781 #ifdef GL_HASH_LOCK_SZ
1782         for(i = 0; i < GL_HASH_LOCK_SZ; i++) {
1783                 rwlock_init(&gl_hash_locks[i]);
1784         }
1785 #endif
1786
1787         scand_process = kthread_run(gfs2_scand, NULL, "gfs2_scand");
1788         if (IS_ERR(scand_process))
1789                 return PTR_ERR(scand_process);
1790
1791         glock_workqueue = create_workqueue("glock_workqueue");
1792         if (IS_ERR(glock_workqueue)) {
1793                 kthread_stop(scand_process);
1794                 return PTR_ERR(glock_workqueue);
1795         }
1796
1797         return 0;
1798 }
1799
1800 void gfs2_glock_exit(void)
1801 {
1802         destroy_workqueue(glock_workqueue);
1803         kthread_stop(scand_process);
1804 }
1805
1806 module_param(scand_secs, uint, S_IRUGO|S_IWUSR);
1807 MODULE_PARM_DESC(scand_secs, "The number of seconds between scand runs");
1808
1809 static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1810 {
1811         struct gfs2_glock *gl;
1812
1813 restart:
1814         read_lock(gl_lock_addr(gi->hash));
1815         gl = gi->gl;
1816         if (gl) {
1817                 gi->gl = hlist_entry(gl->gl_list.next,
1818                                      struct gfs2_glock, gl_list);
1819                 if (gi->gl)
1820                         gfs2_glock_hold(gi->gl);
1821         }
1822         read_unlock(gl_lock_addr(gi->hash));
1823         if (gl)
1824                 gfs2_glock_put(gl);
1825         if (gl && gi->gl == NULL)
1826                 gi->hash++;
1827         while (gi->gl == NULL) {
1828                 if (gi->hash >= GFS2_GL_HASH_SIZE)
1829                         return 1;
1830                 read_lock(gl_lock_addr(gi->hash));
1831                 gi->gl = hlist_entry(gl_hash_table[gi->hash].hb_list.first,
1832                                      struct gfs2_glock, gl_list);
1833                 if (gi->gl)
1834                         gfs2_glock_hold(gi->gl);
1835                 read_unlock(gl_lock_addr(gi->hash));
1836                 gi->hash++;
1837         }
1838
1839         if (gi->sdp != gi->gl->gl_sbd)
1840                 goto restart;
1841
1842         return 0;
1843 }
1844
1845 static void gfs2_glock_iter_free(struct gfs2_glock_iter *gi)
1846 {
1847         if (gi->gl)
1848                 gfs2_glock_put(gi->gl);
1849         gi->gl = NULL;
1850 }
1851
1852 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1853 {
1854         struct gfs2_glock_iter *gi = seq->private;
1855         loff_t n = *pos;
1856
1857         gi->hash = 0;
1858
1859         do {
1860                 if (gfs2_glock_iter_next(gi)) {
1861                         gfs2_glock_iter_free(gi);
1862                         return NULL;
1863                 }
1864         } while (n--);
1865
1866         return gi->gl;
1867 }
1868
1869 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1870                                  loff_t *pos)
1871 {
1872         struct gfs2_glock_iter *gi = seq->private;
1873
1874         (*pos)++;
1875
1876         if (gfs2_glock_iter_next(gi)) {
1877                 gfs2_glock_iter_free(gi);
1878                 return NULL;
1879         }
1880
1881         return gi->gl;
1882 }
1883
1884 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1885 {
1886         struct gfs2_glock_iter *gi = seq->private;
1887         gfs2_glock_iter_free(gi);
1888 }
1889
1890 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1891 {
1892         return dump_glock(seq, iter_ptr);
1893 }
1894
1895 static const struct seq_operations gfs2_glock_seq_ops = {
1896         .start = gfs2_glock_seq_start,
1897         .next  = gfs2_glock_seq_next,
1898         .stop  = gfs2_glock_seq_stop,
1899         .show  = gfs2_glock_seq_show,
1900 };
1901
1902 static int gfs2_debugfs_open(struct inode *inode, struct file *file)
1903 {
1904         int ret = seq_open_private(file, &gfs2_glock_seq_ops,
1905                                    sizeof(struct gfs2_glock_iter));
1906         if (ret == 0) {
1907                 struct seq_file *seq = file->private_data;
1908                 struct gfs2_glock_iter *gi = seq->private;
1909                 gi->sdp = inode->i_private;
1910         }
1911         return ret;
1912 }
1913
1914 static const struct file_operations gfs2_debug_fops = {
1915         .owner   = THIS_MODULE,
1916         .open    = gfs2_debugfs_open,
1917         .read    = seq_read,
1918         .llseek  = seq_lseek,
1919         .release = seq_release_private,
1920 };
1921
1922 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
1923 {
1924         sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
1925         if (!sdp->debugfs_dir)
1926                 return -ENOMEM;
1927         sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
1928                                                          S_IFREG | S_IRUGO,
1929                                                          sdp->debugfs_dir, sdp,
1930                                                          &gfs2_debug_fops);
1931         if (!sdp->debugfs_dentry_glocks)
1932                 return -ENOMEM;
1933
1934         return 0;
1935 }
1936
1937 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
1938 {
1939         if (sdp && sdp->debugfs_dir) {
1940                 if (sdp->debugfs_dentry_glocks) {
1941                         debugfs_remove(sdp->debugfs_dentry_glocks);
1942                         sdp->debugfs_dentry_glocks = NULL;
1943                 }
1944                 debugfs_remove(sdp->debugfs_dir);
1945                 sdp->debugfs_dir = NULL;
1946         }
1947 }
1948
1949 int gfs2_register_debugfs(void)
1950 {
1951         gfs2_root = debugfs_create_dir("gfs2", NULL);
1952         return gfs2_root ? 0 : -ENOMEM;
1953 }
1954
1955 void gfs2_unregister_debugfs(void)
1956 {
1957         debugfs_remove(gfs2_root);
1958         gfs2_root = NULL;
1959 }