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 <asm/uaccess.h>
  23 #include <linux/seq_file.h>
  24 #include <linux/debugfs.h>
  25 #include <linux/kthread.h>
  26 #include <linux/freezer.h>
  27 #include <linux/workqueue.h>
  28 #include <linux/jiffies.h>
  29 #include <linux/rcupdate.h>
  30 #include <linux/rculist_bl.h>
  31 #include <linux/bit_spinlock.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 #include "bmap.h"
  44 #define CREATE_TRACE_POINTS
  45 #include "trace_gfs2.h"
  46
  47 struct gfs2_glock_iter {
  48         int hash;                       /* hash bucket index         */
  49         struct gfs2_sbd *sdp;           /* incore superblock         */
  50         struct gfs2_glock *gl;          /* current glock struct      */
  51         char string[512];               /* scratch space             */
  52 };
  53
  54 typedef void (*glock_examiner) (struct gfs2_glock * gl);
  55
  56 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl);
  57 #define GLOCK_BUG_ON(gl,x) do { if (unlikely(x)) { __dump_glock(NULL, gl); BUG(); } } while(0)
  58 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
  59
  60 static struct dentry *gfs2_root;
  61 static struct workqueue_struct *glock_workqueue;
  62 struct workqueue_struct *gfs2_delete_workqueue;
  63 static LIST_HEAD(lru_list);
  64 static atomic_t lru_count = ATOMIC_INIT(0);
  65 static DEFINE_SPINLOCK(lru_lock);
  66
  67 #define GFS2_GL_HASH_SHIFT      15
  68 #define GFS2_GL_HASH_SIZE       (1 << GFS2_GL_HASH_SHIFT)
  69 #define GFS2_GL_HASH_MASK       (GFS2_GL_HASH_SIZE - 1)
  70
  71 static struct hlist_bl_head gl_hash_table[GFS2_GL_HASH_SIZE];
  72 static struct dentry *gfs2_root;
  73
  74 /**
  75  * gl_hash() - Turn glock number into hash bucket number
  76  * @lock: The glock number
  77  *
  78  * Returns: The number of the corresponding hash bucket
  79  */
  80
  81 static unsigned int gl_hash(const struct gfs2_sbd *sdp,
  82                             const struct lm_lockname *name)
  83 {
  84         unsigned int h;
  85
  86         h = jhash(&name->ln_number, sizeof(u64), 0);
  87         h = jhash(&name->ln_type, sizeof(unsigned int), h);
  88         h = jhash(&sdp, sizeof(struct gfs2_sbd *), h);
  89         h &= GFS2_GL_HASH_MASK;
  90
  91         return h;
  92 }
  93
  94 static inline void spin_lock_bucket(unsigned int hash)
  95 {
  96         hlist_bl_lock(&gl_hash_table[hash]);
  97 }
  98
  99 static inline void spin_unlock_bucket(unsigned int hash)
 100 {
 101         hlist_bl_unlock(&gl_hash_table[hash]);
 102 }
 103
 104 static void gfs2_glock_dealloc(struct rcu_head *rcu)
 105 {
 106         struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu);
 107
 108         if (gl->gl_ops->go_flags & GLOF_ASPACE)
 109                 kmem_cache_free(gfs2_glock_aspace_cachep, gl);
 110         else
 111                 kmem_cache_free(gfs2_glock_cachep, gl);
 112 }
 113
 114 void gfs2_glock_free(struct gfs2_glock *gl)
 115 {
 116         struct gfs2_sbd *sdp = gl->gl_sbd;
 117
 118         call_rcu(&gl->gl_rcu, gfs2_glock_dealloc);
 119         if (atomic_dec_and_test(&sdp->sd_glock_disposal))
 120                 wake_up(&sdp->sd_glock_wait);
 121 }
 122
 123 /**
 124  * gfs2_glock_hold() - increment reference count on glock
 125  * @gl: The glock to hold
 126  *
 127  */
 128
 129 void gfs2_glock_hold(struct gfs2_glock *gl)
 130 {
 131         GLOCK_BUG_ON(gl, atomic_read(&gl->gl_ref) == 0);
 132         atomic_inc(&gl->gl_ref);
 133 }
 134
 135 /**
 136  * demote_ok - Check to see if it's ok to unlock a glock
 137  * @gl: the glock
 138  *
 139  * Returns: 1 if it's ok
 140  */
 141
 142 static int demote_ok(const struct gfs2_glock *gl)
 143 {
 144         const struct gfs2_glock_operations *glops = gl->gl_ops;
 145
 146         if (gl->gl_state == LM_ST_UNLOCKED)
 147                 return 0;
 148         if (!list_empty(&gl->gl_holders))
 149                 return 0;
 150         if (glops->go_demote_ok)
 151                 return glops->go_demote_ok(gl);
 152         return 1;
 153 }
 154
 155
 156 void gfs2_glock_add_to_lru(struct gfs2_glock *gl)
 157 {
 158         spin_lock(&lru_lock);
 159
 160         if (!list_empty(&gl->gl_lru))
 161                 list_del_init(&gl->gl_lru);
 162         else
 163                 atomic_inc(&lru_count);
 164
 165         list_add_tail(&gl->gl_lru, &lru_list);
 166         set_bit(GLF_LRU, &gl->gl_flags);
 167         spin_unlock(&lru_lock);
 168 }
 169
 170 static void __gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
 171 {
 172         if (!list_empty(&gl->gl_lru)) {
 173                 list_del_init(&gl->gl_lru);
 174                 atomic_dec(&lru_count);
 175                 clear_bit(GLF_LRU, &gl->gl_flags);
 176         }
 177 }
 178
 179 static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
 180 {
 181         spin_lock(&lru_lock);
 182         __gfs2_glock_remove_from_lru(gl);
 183         spin_unlock(&lru_lock);
 184 }
 185
 186 /**
 187  * __gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
 188  * @gl: the glock
 189  *
 190  * If the glock is demotable, then we add it (or move it) to the end
 191  * of the glock LRU list.
 192  */
 193
 194 static void __gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
 195 {
 196         if (demote_ok(gl))
 197                 gfs2_glock_add_to_lru(gl);
 198 }
 199
 200 /**
 201  * gfs2_glock_put_nolock() - Decrement reference count on glock
 202  * @gl: The glock to put
 203  *
 204  * This function should only be used if the caller has its own reference
 205  * to the glock, in addition to the one it is dropping.
 206  */
 207
 208 void gfs2_glock_put_nolock(struct gfs2_glock *gl)
 209 {
 210         if (atomic_dec_and_test(&gl->gl_ref))
 211                 GLOCK_BUG_ON(gl, 1);
 212 }
 213
 214 /**
 215  * gfs2_glock_put() - Decrement reference count on glock
 216  * @gl: The glock to put
 217  *
 218  */
 219
 220 void gfs2_glock_put(struct gfs2_glock *gl)
 221 {
 222         struct gfs2_sbd *sdp = gl->gl_sbd;
 223         struct address_space *mapping = gfs2_glock2aspace(gl);
 224
 225         if (atomic_dec_and_lock(&gl->gl_ref, &lru_lock)) {
 226                 __gfs2_glock_remove_from_lru(gl);
 227                 spin_unlock(&lru_lock);
 228                 spin_lock_bucket(gl->gl_hash);
 229                 hlist_bl_del_rcu(&gl->gl_list);
 230                 spin_unlock_bucket(gl->gl_hash);
 231                 GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
 232                 GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
 233                 trace_gfs2_glock_put(gl);
 234                 sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
 235         }
 236 }
 237
 238 /**
 239  * search_bucket() - Find struct gfs2_glock by lock number
 240  * @bucket: the bucket to search
 241  * @name: The lock name
 242  *
 243  * Returns: NULL, or the struct gfs2_glock with the requested number
 244  */
 245
 246 static struct gfs2_glock *search_bucket(unsigned int hash,
 247                                         const struct gfs2_sbd *sdp,
 248                                         const struct lm_lockname *name)
 249 {
 250         struct gfs2_glock *gl;
 251         struct hlist_bl_node *h;
 252
 253         hlist_bl_for_each_entry_rcu(gl, h, &gl_hash_table[hash], gl_list) {
 254                 if (!lm_name_equal(&gl->gl_name, name))
 255                         continue;
 256                 if (gl->gl_sbd != sdp)
 257                         continue;
 258                 if (atomic_inc_not_zero(&gl->gl_ref))
 259                         return gl;
 260         }
 261
 262         return NULL;
 263 }
 264
 265 /**
 266  * may_grant - check if its ok to grant a new lock
 267  * @gl: The glock
 268  * @gh: The lock request which we wish to grant
 269  *
 270  * Returns: true if its ok to grant the lock
 271  */
 272
 273 static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
 274 {
 275         const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
 276         if ((gh->gh_state == LM_ST_EXCLUSIVE ||
 277              gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
 278                 return 0;
 279         if (gl->gl_state == gh->gh_state)
 280                 return 1;
 281         if (gh->gh_flags & GL_EXACT)
 282                 return 0;
 283         if (gl->gl_state == LM_ST_EXCLUSIVE) {
 284                 if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
 285                         return 1;
 286                 if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
 287                         return 1;
 288         }
 289         if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
 290                 return 1;
 291         return 0;
 292 }
 293
 294 static void gfs2_holder_wake(struct gfs2_holder *gh)
 295 {
 296         clear_bit(HIF_WAIT, &gh->gh_iflags);
 297         smp_mb__after_clear_bit();
 298         wake_up_bit(&gh->gh_iflags, HIF_WAIT);
 299 }
 300
 301 /**
 302  * do_error - Something unexpected has happened during a lock request
 303  *
 304  */
 305
 306 static inline void do_error(struct gfs2_glock *gl, const int ret)
 307 {
 308         struct gfs2_holder *gh, *tmp;
 309
 310         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 311                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 312                         continue;
 313                 if (ret & LM_OUT_ERROR)
 314                         gh->gh_error = -EIO;
 315                 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
 316                         gh->gh_error = GLR_TRYFAILED;
 317                 else
 318                         continue;
 319                 list_del_init(&gh->gh_list);
 320                 trace_gfs2_glock_queue(gh, 0);
 321                 gfs2_holder_wake(gh);
 322         }
 323 }
 324
 325 /**
 326  * do_promote - promote as many requests as possible on the current queue
 327  * @gl: The glock
 328  *
 329  * Returns: 1 if there is a blocked holder at the head of the list, or 2
 330  *          if a type specific operation is underway.
 331  */
 332
 333 static int do_promote(struct gfs2_glock *gl)
 334 __releases(&gl->gl_spin)
 335 __acquires(&gl->gl_spin)
 336 {
 337         const struct gfs2_glock_operations *glops = gl->gl_ops;
 338         struct gfs2_holder *gh, *tmp;
 339         int ret;
 340
 341 restart:
 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 (may_grant(gl, gh)) {
 346                         if (gh->gh_list.prev == &gl->gl_holders &&
 347                             glops->go_lock) {
 348                                 spin_unlock(&gl->gl_spin);
 349                                 /* FIXME: eliminate this eventually */
 350                                 ret = glops->go_lock(gh);
 351                                 spin_lock(&gl->gl_spin);
 352                                 if (ret) {
 353                                         if (ret == 1)
 354                                                 return 2;
 355                                         gh->gh_error = ret;
 356                                         list_del_init(&gh->gh_list);
 357                                         trace_gfs2_glock_queue(gh, 0);
 358                                         gfs2_holder_wake(gh);
 359                                         goto restart;
 360                                 }
 361                                 set_bit(HIF_HOLDER, &gh->gh_iflags);
 362                                 trace_gfs2_promote(gh, 1);
 363                                 gfs2_holder_wake(gh);
 364                                 goto restart;
 365                         }
 366                         set_bit(HIF_HOLDER, &gh->gh_iflags);
 367                         trace_gfs2_promote(gh, 0);
 368                         gfs2_holder_wake(gh);
 369                         continue;
 370                 }
 371                 if (gh->gh_list.prev == &gl->gl_holders)
 372                         return 1;
 373                 do_error(gl, 0);
 374                 break;
 375         }
 376         return 0;
 377 }
 378
 379 /**
 380  * find_first_waiter - find the first gh that's waiting for the glock
 381  * @gl: the glock
 382  */
 383
 384 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
 385 {
 386         struct gfs2_holder *gh;
 387
 388         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
 389                 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
 390                         return gh;
 391         }
 392         return NULL;
 393 }
 394
 395 /**
 396  * state_change - record that the glock is now in a different state
 397  * @gl: the glock
 398  * @new_state the new state
 399  *
 400  */
 401
 402 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 403 {
 404         int held1, held2;
 405
 406         held1 = (gl->gl_state != LM_ST_UNLOCKED);
 407         held2 = (new_state != LM_ST_UNLOCKED);
 408
 409         if (held1 != held2) {
 410                 if (held2)
 411                         gfs2_glock_hold(gl);
 412                 else
 413                         gfs2_glock_put_nolock(gl);
 414         }
 415         if (held1 && held2 && list_empty(&gl->gl_holders))
 416                 clear_bit(GLF_QUEUED, &gl->gl_flags);
 417
 418         if (new_state != gl->gl_target)
 419                 /* shorten our minimum hold time */
 420                 gl->gl_hold_time = max(gl->gl_hold_time - GL_GLOCK_HOLD_DECR,
 421                                        GL_GLOCK_MIN_HOLD);
 422         gl->gl_state = new_state;
 423         gl->gl_tchange = jiffies;
 424 }
 425
 426 static void gfs2_demote_wake(struct gfs2_glock *gl)
 427 {
 428         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 429         clear_bit(GLF_DEMOTE, &gl->gl_flags);
 430         smp_mb__after_clear_bit();
 431         wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
 432 }
 433
 434 /**
 435  * finish_xmote - The DLM has replied to one of our lock requests
 436  * @gl: The glock
 437  * @ret: The status from the DLM
 438  *
 439  */
 440
 441 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
 442 {
 443         const struct gfs2_glock_operations *glops = gl->gl_ops;
 444         struct gfs2_holder *gh;
 445         unsigned state = ret & LM_OUT_ST_MASK;
 446         int rv;
 447
 448         spin_lock(&gl->gl_spin);
 449         trace_gfs2_glock_state_change(gl, state);
 450         state_change(gl, state);
 451         gh = find_first_waiter(gl);
 452
 453         /* Demote to UN request arrived during demote to SH or DF */
 454         if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
 455             state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
 456                 gl->gl_target = LM_ST_UNLOCKED;
 457
 458         /* Check for state != intended state */
 459         if (unlikely(state != gl->gl_target)) {
 460                 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
 461                         /* move to back of queue and try next entry */
 462                         if (ret & LM_OUT_CANCELED) {
 463                                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
 464                                         list_move_tail(&gh->gh_list, &gl->gl_holders);
 465                                 gh = find_first_waiter(gl);
 466                                 gl->gl_target = gh->gh_state;
 467                                 goto retry;
 468                         }
 469                         /* Some error or failed "try lock" - report it */
 470                         if ((ret & LM_OUT_ERROR) ||
 471                             (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 472                                 gl->gl_target = gl->gl_state;
 473                                 do_error(gl, ret);
 474                                 goto out;
 475                         }
 476                 }
 477                 switch(state) {
 478                 /* Unlocked due to conversion deadlock, try again */
 479                 case LM_ST_UNLOCKED:
 480 retry:
 481                         do_xmote(gl, gh, gl->gl_target);
 482                         break;
 483                 /* Conversion fails, unlock and try again */
 484                 case LM_ST_SHARED:
 485                 case LM_ST_DEFERRED:
 486                         do_xmote(gl, gh, LM_ST_UNLOCKED);
 487                         break;
 488                 default: /* Everything else */
 489                         printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
 490                         GLOCK_BUG_ON(gl, 1);
 491                 }
 492                 spin_unlock(&gl->gl_spin);
 493                 return;
 494         }
 495
 496         /* Fast path - we got what we asked for */
 497         if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
 498                 gfs2_demote_wake(gl);
 499         if (state != LM_ST_UNLOCKED) {
 500                 if (glops->go_xmote_bh) {
 501                         spin_unlock(&gl->gl_spin);
 502                         rv = glops->go_xmote_bh(gl, gh);
 503                         spin_lock(&gl->gl_spin);
 504                         if (rv) {
 505                                 do_error(gl, rv);
 506                                 goto out;
 507                         }
 508                 }
 509                 rv = do_promote(gl);
 510                 if (rv == 2)
 511                         goto out_locked;
 512         }
 513 out:
 514         clear_bit(GLF_LOCK, &gl->gl_flags);
 515 out_locked:
 516         spin_unlock(&gl->gl_spin);
 517 }
 518
 519 /**
 520  * do_xmote - Calls the DLM to change the state of a lock
 521  * @gl: The lock state
 522  * @gh: The holder (only for promotes)
 523  * @target: The target lock state
 524  *
 525  */
 526
 527 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
 528 __releases(&gl->gl_spin)
 529 __acquires(&gl->gl_spin)
 530 {
 531         const struct gfs2_glock_operations *glops = gl->gl_ops;
 532         struct gfs2_sbd *sdp = gl->gl_sbd;
 533         unsigned int lck_flags = gh ? gh->gh_flags : 0;
 534         int ret;
 535
 536         lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
 537                       LM_FLAG_PRIORITY);
 538         GLOCK_BUG_ON(gl, gl->gl_state == target);
 539         GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
 540         if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
 541             glops->go_inval) {
 542                 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 543                 do_error(gl, 0); /* Fail queued try locks */
 544         }
 545         gl->gl_req = target;
 546         spin_unlock(&gl->gl_spin);
 547         if (glops->go_xmote_th)
 548                 glops->go_xmote_th(gl);
 549         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 550                 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
 551         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 552
 553         gfs2_glock_hold(gl);
 554         if (sdp->sd_lockstruct.ls_ops->lm_lock) {
 555                 /* lock_dlm */
 556                 ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
 557                 GLOCK_BUG_ON(gl, ret);
 558         } else { /* lock_nolock */
 559                 finish_xmote(gl, target);
 560                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 561                         gfs2_glock_put(gl);
 562         }
 563
 564         spin_lock(&gl->gl_spin);
 565 }
 566
 567 /**
 568  * find_first_holder - find the first "holder" gh
 569  * @gl: the glock
 570  */
 571
 572 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
 573 {
 574         struct gfs2_holder *gh;
 575
 576         if (!list_empty(&gl->gl_holders)) {
 577                 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 578                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 579                         return gh;
 580         }
 581         return NULL;
 582 }
 583
 584 /**
 585  * run_queue - do all outstanding tasks related to a glock
 586  * @gl: The glock in question
 587  * @nonblock: True if we must not block in run_queue
 588  *
 589  */
 590
 591 static void run_queue(struct gfs2_glock *gl, const int nonblock)
 592 __releases(&gl->gl_spin)
 593 __acquires(&gl->gl_spin)
 594 {
 595         struct gfs2_holder *gh = NULL;
 596         int ret;
 597
 598         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 599                 return;
 600
 601         GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
 602
 603         if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
 604             gl->gl_demote_state != gl->gl_state) {
 605                 if (find_first_holder(gl))
 606                         goto out_unlock;
 607                 if (nonblock)
 608                         goto out_sched;
 609                 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
 610                 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
 611                 gl->gl_target = gl->gl_demote_state;
 612         } else {
 613                 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
 614                         gfs2_demote_wake(gl);
 615                 ret = do_promote(gl);
 616                 if (ret == 0)
 617                         goto out_unlock;
 618                 if (ret == 2)
 619                         goto out;
 620                 gh = find_first_waiter(gl);
 621                 gl->gl_target = gh->gh_state;
 622                 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 623                         do_error(gl, 0); /* Fail queued try locks */
 624         }
 625         do_xmote(gl, gh, gl->gl_target);
 626 out:
 627         return;
 628
 629 out_sched:
 630         clear_bit(GLF_LOCK, &gl->gl_flags);
 631         smp_mb__after_clear_bit();
 632         gfs2_glock_hold(gl);
 633         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 634                 gfs2_glock_put_nolock(gl);
 635         return;
 636
 637 out_unlock:
 638         clear_bit(GLF_LOCK, &gl->gl_flags);
 639         smp_mb__after_clear_bit();
 640         return;
 641 }
 642
 643 static void delete_work_func(struct work_struct *work)
 644 {
 645         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
 646         struct gfs2_sbd *sdp = gl->gl_sbd;
 647         struct gfs2_inode *ip;
 648         struct inode *inode;
 649         u64 no_addr = gl->gl_name.ln_number;
 650
 651         ip = gl->gl_object;
 652         /* Note: Unsafe to dereference ip as we don't hold right refs/locks */
 653
 654         if (ip)
 655                 inode = gfs2_ilookup(sdp->sd_vfs, no_addr, 1);
 656         else
 657                 inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
 658         if (inode && !IS_ERR(inode)) {
 659                 d_prune_aliases(inode);
 660                 iput(inode);
 661         }
 662         gfs2_glock_put(gl);
 663 }
 664
 665 static void glock_work_func(struct work_struct *work)
 666 {
 667         unsigned long delay = 0;
 668         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
 669         int drop_ref = 0;
 670
 671         if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
 672                 finish_xmote(gl, gl->gl_reply);
 673                 drop_ref = 1;
 674         }
 675         spin_lock(&gl->gl_spin);
 676         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
 677             gl->gl_state != LM_ST_UNLOCKED &&
 678             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
 679                 unsigned long holdtime, now = jiffies;
 680
 681                 holdtime = gl->gl_tchange + gl->gl_hold_time;
 682                 if (time_before(now, holdtime))
 683                         delay = holdtime - now;
 684
 685                 if (!delay) {
 686                         clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
 687                         set_bit(GLF_DEMOTE, &gl->gl_flags);
 688                 }
 689         }
 690         run_queue(gl, 0);
 691         spin_unlock(&gl->gl_spin);
 692         if (!delay)
 693                 gfs2_glock_put(gl);
 694         else {
 695                 if (gl->gl_name.ln_type != LM_TYPE_INODE)
 696                         delay = 0;
 697                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
 698                         gfs2_glock_put(gl);
 699         }
 700         if (drop_ref)
 701                 gfs2_glock_put(gl);
 702 }
 703
 704 /**
 705  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
 706  * @sdp: The GFS2 superblock
 707  * @number: the lock number
 708  * @glops: The glock_operations to use
 709  * @create: If 0, don't create the glock if it doesn't exist
 710  * @glp: the glock is returned here
 711  *
 712  * This does not lock a glock, just finds/creates structures for one.
 713  *
 714  * Returns: errno
 715  */
 716
 717 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 718                    const struct gfs2_glock_operations *glops, int create,
 719                    struct gfs2_glock **glp)
 720 {
 721         struct super_block *s = sdp->sd_vfs;
 722         struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
 723         struct gfs2_glock *gl, *tmp;
 724         unsigned int hash = gl_hash(sdp, &name);
 725         struct address_space *mapping;
 726         struct kmem_cache *cachep;
 727
 728         rcu_read_lock();
 729         gl = search_bucket(hash, sdp, &name);
 730         rcu_read_unlock();
 731
 732         *glp = gl;
 733         if (gl)
 734                 return 0;
 735         if (!create)
 736                 return -ENOENT;
 737
 738         if (glops->go_flags & GLOF_ASPACE)
 739                 cachep = gfs2_glock_aspace_cachep;
 740         else
 741                 cachep = gfs2_glock_cachep;
 742         gl = kmem_cache_alloc(cachep, GFP_KERNEL);
 743         if (!gl)
 744                 return -ENOMEM;
 745
 746         atomic_inc(&sdp->sd_glock_disposal);
 747         gl->gl_flags = 0;
 748         gl->gl_name = name;
 749         atomic_set(&gl->gl_ref, 1);
 750         gl->gl_state = LM_ST_UNLOCKED;
 751         gl->gl_target = LM_ST_UNLOCKED;
 752         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 753         gl->gl_hash = hash;
 754         gl->gl_ops = glops;
 755         snprintf(gl->gl_strname, GDLM_STRNAME_BYTES, "%8x%16llx", name.ln_type, (unsigned long long)number);
 756         memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
 757         gl->gl_lksb.sb_lvbptr = gl->gl_lvb;
 758         gl->gl_tchange = jiffies;
 759         gl->gl_object = NULL;
 760         gl->gl_sbd = sdp;
 761         gl->gl_hold_time = GL_GLOCK_DFT_HOLD;
 762         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
 763         INIT_WORK(&gl->gl_delete, delete_work_func);
 764
 765         mapping = gfs2_glock2aspace(gl);
 766         if (mapping) {
 767                 mapping->a_ops = &gfs2_meta_aops;
 768                 mapping->host = s->s_bdev->bd_inode;
 769                 mapping->flags = 0;
 770                 mapping_set_gfp_mask(mapping, GFP_NOFS);
 771                 mapping->assoc_mapping = NULL;
 772                 mapping->backing_dev_info = s->s_bdi;
 773                 mapping->writeback_index = 0;
 774         }
 775
 776         spin_lock_bucket(hash);
 777         tmp = search_bucket(hash, sdp, &name);
 778         if (tmp) {
 779                 spin_unlock_bucket(hash);
 780                 kmem_cache_free(cachep, gl);
 781                 atomic_dec(&sdp->sd_glock_disposal);
 782                 gl = tmp;
 783         } else {
 784                 hlist_bl_add_head_rcu(&gl->gl_list, &gl_hash_table[hash]);
 785                 spin_unlock_bucket(hash);
 786         }
 787
 788         *glp = gl;
 789
 790         return 0;
 791 }
 792
 793 /**
 794  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
 795  * @gl: the glock
 796  * @state: the state we're requesting
 797  * @flags: the modifier flags
 798  * @gh: the holder structure
 799  *
 800  */
 801
 802 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
 803                       struct gfs2_holder *gh)
 804 {
 805         INIT_LIST_HEAD(&gh->gh_list);
 806         gh->gh_gl = gl;
 807         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 808         gh->gh_owner_pid = get_pid(task_pid(current));
 809         gh->gh_state = state;
 810         gh->gh_flags = flags;
 811         gh->gh_error = 0;
 812         gh->gh_iflags = 0;
 813         gfs2_glock_hold(gl);
 814 }
 815
 816 /**
 817  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
 818  * @state: the state we're requesting
 819  * @flags: the modifier flags
 820  * @gh: the holder structure
 821  *
 822  * Don't mess with the glock.
 823  *
 824  */
 825
 826 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
 827 {
 828         gh->gh_state = state;
 829         gh->gh_flags = flags;
 830         gh->gh_iflags = 0;
 831         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 832         if (gh->gh_owner_pid)
 833                 put_pid(gh->gh_owner_pid);
 834         gh->gh_owner_pid = get_pid(task_pid(current));
 835 }
 836
 837 /**
 838  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 839  * @gh: the holder structure
 840  *
 841  */
 842
 843 void gfs2_holder_uninit(struct gfs2_holder *gh)
 844 {
 845         put_pid(gh->gh_owner_pid);
 846         gfs2_glock_put(gh->gh_gl);
 847         gh->gh_gl = NULL;
 848         gh->gh_ip = 0;
 849 }
 850
 851 /**
 852  * gfs2_glock_holder_wait
 853  * @word: unused
 854  *
 855  * This function and gfs2_glock_demote_wait both show up in the WCHAN
 856  * field. Thus I've separated these otherwise identical functions in
 857  * order to be more informative to the user.
 858  */
 859
 860 static int gfs2_glock_holder_wait(void *word)
 861 {
 862         schedule();
 863         return 0;
 864 }
 865
 866 static int gfs2_glock_demote_wait(void *word)
 867 {
 868         schedule();
 869         return 0;
 870 }
 871
 872 static void wait_on_holder(struct gfs2_holder *gh)
 873 {
 874         unsigned long time1 = jiffies;
 875
 876         might_sleep();
 877         wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
 878         if (time_after(jiffies, time1 + HZ)) /* have we waited > a second? */
 879                 /* Lengthen the minimum hold time. */
 880                 gh->gh_gl->gl_hold_time = min(gh->gh_gl->gl_hold_time +
 881                                               GL_GLOCK_HOLD_INCR,
 882                                               GL_GLOCK_MAX_HOLD);
 883 }
 884
 885 static void wait_on_demote(struct gfs2_glock *gl)
 886 {
 887         might_sleep();
 888         wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
 889 }
 890
 891 /**
 892  * handle_callback - process a demote request
 893  * @gl: the glock
 894  * @state: the state the caller wants us to change to
 895  *
 896  * There are only two requests that we are going to see in actual
 897  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
 898  */
 899
 900 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
 901                             unsigned long delay)
 902 {
 903         int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
 904
 905         set_bit(bit, &gl->gl_flags);
 906         if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
 907                 gl->gl_demote_state = state;
 908                 gl->gl_demote_time = jiffies;
 909         } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
 910                         gl->gl_demote_state != state) {
 911                 gl->gl_demote_state = LM_ST_UNLOCKED;
 912         }
 913         if (gl->gl_ops->go_callback)
 914                 gl->gl_ops->go_callback(gl);
 915         trace_gfs2_demote_rq(gl);
 916 }
 917
 918 /**
 919  * gfs2_glock_wait - wait on a glock acquisition
 920  * @gh: the glock holder
 921  *
 922  * Returns: 0 on success
 923  */
 924
 925 int gfs2_glock_wait(struct gfs2_holder *gh)
 926 {
 927         wait_on_holder(gh);
 928         return gh->gh_error;
 929 }
 930
 931 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
 932 {
 933         struct va_format vaf;
 934         va_list args;
 935
 936         va_start(args, fmt);
 937
 938         if (seq) {
 939                 struct gfs2_glock_iter *gi = seq->private;
 940                 vsprintf(gi->string, fmt, args);
 941                 seq_printf(seq, gi->string);
 942         } else {
 943                 vaf.fmt = fmt;
 944                 vaf.va = &args;
 945
 946                 printk(KERN_ERR " %pV", &vaf);
 947         }
 948
 949         va_end(args);
 950 }
 951
 952 /**
 953  * add_to_queue - Add a holder to the wait queue (but look for recursion)
 954  * @gh: the holder structure to add
 955  *
 956  * Eventually we should move the recursive locking trap to a
 957  * debugging option or something like that. This is the fast
 958  * path and needs to have the minimum number of distractions.
 959  *
 960  */
 961
 962 static inline void add_to_queue(struct gfs2_holder *gh)
 963 __releases(&gl->gl_spin)
 964 __acquires(&gl->gl_spin)
 965 {
 966         struct gfs2_glock *gl = gh->gh_gl;
 967         struct gfs2_sbd *sdp = gl->gl_sbd;
 968         struct list_head *insert_pt = NULL;
 969         struct gfs2_holder *gh2;
 970         int try_lock = 0;
 971
 972         BUG_ON(gh->gh_owner_pid == NULL);
 973         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
 974                 BUG();
 975
 976         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
 977                 if (test_bit(GLF_LOCK, &gl->gl_flags))
 978                         try_lock = 1;
 979                 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 980                         goto fail;
 981         }
 982
 983         list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
 984                 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
 985                     (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
 986                         goto trap_recursive;
 987                 if (try_lock &&
 988                     !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
 989                     !may_grant(gl, gh)) {
 990 fail:
 991                         gh->gh_error = GLR_TRYFAILED;
 992                         gfs2_holder_wake(gh);
 993                         return;
 994                 }
 995                 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
 996                         continue;
 997                 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
 998                         insert_pt = &gh2->gh_list;
 999         }
1000         set_bit(GLF_QUEUED, &gl->gl_flags);
1001         trace_gfs2_glock_queue(gh, 1);
1002         if (likely(insert_pt == NULL)) {
1003                 list_add_tail(&gh->gh_list, &gl->gl_holders);
1004                 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
1005                         goto do_cancel;
1006                 return;
1007         }
1008         list_add_tail(&gh->gh_list, insert_pt);
1009 do_cancel:
1010         gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
1011         if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
1012                 spin_unlock(&gl->gl_spin);
1013                 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
1014                         sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
1015                 spin_lock(&gl->gl_spin);
1016         }
1017         return;
1018
1019 trap_recursive:
1020         print_symbol(KERN_ERR "original: %s\n", gh2->gh_ip);
1021         printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
1022         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1023                gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
1024         print_symbol(KERN_ERR "new: %s\n", gh->gh_ip);
1025         printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
1026         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1027                gh->gh_gl->gl_name.ln_type, gh->gh_state);
1028         __dump_glock(NULL, gl);
1029         BUG();
1030 }
1031
1032 /**
1033  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1034  * @gh: the holder structure
1035  *
1036  * if (gh->gh_flags & GL_ASYNC), this never returns an error
1037  *
1038  * Returns: 0, GLR_TRYFAILED, or errno on failure
1039  */
1040
1041 int gfs2_glock_nq(struct gfs2_holder *gh)
1042 {
1043         struct gfs2_glock *gl = gh->gh_gl;
1044         struct gfs2_sbd *sdp = gl->gl_sbd;
1045         int error = 0;
1046
1047         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
1048                 return -EIO;
1049
1050         if (test_bit(GLF_LRU, &gl->gl_flags))
1051                 gfs2_glock_remove_from_lru(gl);
1052
1053         spin_lock(&gl->gl_spin);
1054         add_to_queue(gh);
1055         if ((LM_FLAG_NOEXP & gh->gh_flags) &&
1056             test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1057                 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1058         run_queue(gl, 1);
1059         spin_unlock(&gl->gl_spin);
1060
1061         if (!(gh->gh_flags & GL_ASYNC))
1062                 error = gfs2_glock_wait(gh);
1063
1064         return error;
1065 }
1066
1067 /**
1068  * gfs2_glock_poll - poll to see if an async request has been completed
1069  * @gh: the holder
1070  *
1071  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1072  */
1073
1074 int gfs2_glock_poll(struct gfs2_holder *gh)
1075 {
1076         return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1077 }
1078
1079 /**
1080  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1081  * @gh: the glock holder
1082  *
1083  */
1084
1085 void gfs2_glock_dq(struct gfs2_holder *gh)
1086 {
1087         struct gfs2_glock *gl = gh->gh_gl;
1088         const struct gfs2_glock_operations *glops = gl->gl_ops;
1089         unsigned delay = 0;
1090         int fast_path = 0;
1091
1092         spin_lock(&gl->gl_spin);
1093         if (gh->gh_flags & GL_NOCACHE)
1094                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1095
1096         list_del_init(&gh->gh_list);
1097         if (find_first_holder(gl) == NULL) {
1098                 if (glops->go_unlock) {
1099                         GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1100                         spin_unlock(&gl->gl_spin);
1101                         glops->go_unlock(gh);
1102                         spin_lock(&gl->gl_spin);
1103                         clear_bit(GLF_LOCK, &gl->gl_flags);
1104                 }
1105                 if (list_empty(&gl->gl_holders) &&
1106                     !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1107                     !test_bit(GLF_DEMOTE, &gl->gl_flags))
1108                         fast_path = 1;
1109         }
1110         if (!test_bit(GLF_LFLUSH, &gl->gl_flags))
1111                 __gfs2_glock_schedule_for_reclaim(gl);
1112         trace_gfs2_glock_queue(gh, 0);
1113         spin_unlock(&gl->gl_spin);
1114         if (likely(fast_path))
1115                 return;
1116
1117         gfs2_glock_hold(gl);
1118         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1119             !test_bit(GLF_DEMOTE, &gl->gl_flags) &&
1120             gl->gl_name.ln_type == LM_TYPE_INODE)
1121                 delay = gl->gl_hold_time;
1122         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1123                 gfs2_glock_put(gl);
1124 }
1125
1126 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1127 {
1128         struct gfs2_glock *gl = gh->gh_gl;
1129         gfs2_glock_dq(gh);
1130         wait_on_demote(gl);
1131 }
1132
1133 /**
1134  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1135  * @gh: the holder structure
1136  *
1137  */
1138
1139 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1140 {
1141         gfs2_glock_dq(gh);
1142         gfs2_holder_uninit(gh);
1143 }
1144
1145 /**
1146  * gfs2_glock_nq_num - acquire a glock based on lock number
1147  * @sdp: the filesystem
1148  * @number: the lock number
1149  * @glops: the glock operations for the type of glock
1150  * @state: the state to acquire the glock in
1151  * @flags: modifier flags for the acquisition
1152  * @gh: the struct gfs2_holder
1153  *
1154  * Returns: errno
1155  */
1156
1157 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1158                       const struct gfs2_glock_operations *glops,
1159                       unsigned int state, int flags, struct gfs2_holder *gh)
1160 {
1161         struct gfs2_glock *gl;
1162         int error;
1163
1164         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1165         if (!error) {
1166                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1167                 gfs2_glock_put(gl);
1168         }
1169
1170         return error;
1171 }
1172
1173 /**
1174  * glock_compare - Compare two struct gfs2_glock structures for sorting
1175  * @arg_a: the first structure
1176  * @arg_b: the second structure
1177  *
1178  */
1179
1180 static int glock_compare(const void *arg_a, const void *arg_b)
1181 {
1182         const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1183         const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1184         const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1185         const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1186
1187         if (a->ln_number > b->ln_number)
1188                 return 1;
1189         if (a->ln_number < b->ln_number)
1190                 return -1;
1191         BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1192         return 0;
1193 }
1194
1195 /**
1196  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1197  * @num_gh: the number of structures
1198  * @ghs: an array of struct gfs2_holder structures
1199  *
1200  * Returns: 0 on success (all glocks acquired),
1201  *          errno on failure (no glocks acquired)
1202  */
1203
1204 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1205                      struct gfs2_holder **p)
1206 {
1207         unsigned int x;
1208         int error = 0;
1209
1210         for (x = 0; x < num_gh; x++)
1211                 p[x] = &ghs[x];
1212
1213         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1214
1215         for (x = 0; x < num_gh; x++) {
1216                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1217
1218                 error = gfs2_glock_nq(p[x]);
1219                 if (error) {
1220                         while (x--)
1221                                 gfs2_glock_dq(p[x]);
1222                         break;
1223                 }
1224         }
1225
1226         return error;
1227 }
1228
1229 /**
1230  * gfs2_glock_nq_m - acquire multiple glocks
1231  * @num_gh: the number of structures
1232  * @ghs: an array of struct gfs2_holder structures
1233  *
1234  *
1235  * Returns: 0 on success (all glocks acquired),
1236  *          errno on failure (no glocks acquired)
1237  */
1238
1239 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1240 {
1241         struct gfs2_holder *tmp[4];
1242         struct gfs2_holder **pph = tmp;
1243         int error = 0;
1244
1245         switch(num_gh) {
1246         case 0:
1247                 return 0;
1248         case 1:
1249                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1250                 return gfs2_glock_nq(ghs);
1251         default:
1252                 if (num_gh <= 4)
1253                         break;
1254                 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1255                 if (!pph)
1256                         return -ENOMEM;
1257         }
1258
1259         error = nq_m_sync(num_gh, ghs, pph);
1260
1261         if (pph != tmp)
1262                 kfree(pph);
1263
1264         return error;
1265 }
1266
1267 /**
1268  * gfs2_glock_dq_m - release multiple glocks
1269  * @num_gh: the number of structures
1270  * @ghs: an array of struct gfs2_holder structures
1271  *
1272  */
1273
1274 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1275 {
1276         while (num_gh--)
1277                 gfs2_glock_dq(&ghs[num_gh]);
1278 }
1279
1280 /**
1281  * gfs2_glock_dq_uninit_m - release multiple glocks
1282  * @num_gh: the number of structures
1283  * @ghs: an array of struct gfs2_holder structures
1284  *
1285  */
1286
1287 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1288 {
1289         while (num_gh--)
1290                 gfs2_glock_dq_uninit(&ghs[num_gh]);
1291 }
1292
1293 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1294 {
1295         unsigned long delay = 0;
1296         unsigned long holdtime;
1297         unsigned long now = jiffies;
1298
1299         gfs2_glock_hold(gl);
1300         holdtime = gl->gl_tchange + gl->gl_hold_time;
1301         if (test_bit(GLF_QUEUED, &gl->gl_flags) &&
1302             gl->gl_name.ln_type == LM_TYPE_INODE) {
1303                 if (time_before(now, holdtime))
1304                         delay = holdtime - now;
1305                 if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1306                         delay = gl->gl_hold_time;
1307         }
1308
1309         spin_lock(&gl->gl_spin);
1310         handle_callback(gl, state, delay);
1311         spin_unlock(&gl->gl_spin);
1312         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1313                 gfs2_glock_put(gl);
1314 }
1315
1316 /**
1317  * gfs2_should_freeze - Figure out if glock should be frozen
1318  * @gl: The glock in question
1319  *
1320  * Glocks are not frozen if (a) the result of the dlm operation is
1321  * an error, (b) the locking operation was an unlock operation or
1322  * (c) if there is a "noexp" flagged request anywhere in the queue
1323  *
1324  * Returns: 1 if freezing should occur, 0 otherwise
1325  */
1326
1327 static int gfs2_should_freeze(const struct gfs2_glock *gl)
1328 {
1329         const struct gfs2_holder *gh;
1330
1331         if (gl->gl_reply & ~LM_OUT_ST_MASK)
1332                 return 0;
1333         if (gl->gl_target == LM_ST_UNLOCKED)
1334                 return 0;
1335
1336         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1337                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1338                         continue;
1339                 if (LM_FLAG_NOEXP & gh->gh_flags)
1340                         return 0;
1341         }
1342
1343         return 1;
1344 }
1345
1346 /**
1347  * gfs2_glock_complete - Callback used by locking
1348  * @gl: Pointer to the glock
1349  * @ret: The return value from the dlm
1350  *
1351  * The gl_reply field is under the gl_spin lock so that it is ok
1352  * to use a bitfield shared with other glock state fields.
1353  */
1354
1355 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1356 {
1357         struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
1358
1359         spin_lock(&gl->gl_spin);
1360         gl->gl_reply = ret;
1361
1362         if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags))) {
1363                 if (gfs2_should_freeze(gl)) {
1364                         set_bit(GLF_FROZEN, &gl->gl_flags);
1365                         spin_unlock(&gl->gl_spin);
1366                         return;
1367                 }
1368         }
1369
1370         spin_unlock(&gl->gl_spin);
1371         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1372         smp_wmb();
1373         gfs2_glock_hold(gl);
1374         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1375                 gfs2_glock_put(gl);
1376 }
1377
1378
1379 static int gfs2_shrink_glock_memory(struct shrinker *shrink,
1380                                     struct shrink_control *sc)
1381 {
1382         struct gfs2_glock *gl;
1383         int may_demote;
1384         int nr_skipped = 0;
1385         int nr = sc->nr_to_scan;
1386         gfp_t gfp_mask = sc->gfp_mask;
1387         LIST_HEAD(skipped);
1388
1389         if (nr == 0)
1390                 goto out;
1391
1392         if (!(gfp_mask & __GFP_FS))
1393                 return -1;
1394
1395         spin_lock(&lru_lock);
1396         while(nr && !list_empty(&lru_list)) {
1397                 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1398                 list_del_init(&gl->gl_lru);
1399                 clear_bit(GLF_LRU, &gl->gl_flags);
1400                 atomic_dec(&lru_count);
1401
1402                 /* Test for being demotable */
1403                 if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1404                         gfs2_glock_hold(gl);
1405                         spin_unlock(&lru_lock);
1406                         spin_lock(&gl->gl_spin);
1407                         may_demote = demote_ok(gl);
1408                         if (may_demote) {
1409                                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1410                                 nr--;
1411                         }
1412                         clear_bit(GLF_LOCK, &gl->gl_flags);
1413                         smp_mb__after_clear_bit();
1414                         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1415                                 gfs2_glock_put_nolock(gl);
1416                         spin_unlock(&gl->gl_spin);
1417                         spin_lock(&lru_lock);
1418                         continue;
1419                 }
1420                 nr_skipped++;
1421                 list_add(&gl->gl_lru, &skipped);
1422                 set_bit(GLF_LRU, &gl->gl_flags);
1423         }
1424         list_splice(&skipped, &lru_list);
1425         atomic_add(nr_skipped, &lru_count);
1426         spin_unlock(&lru_lock);
1427 out:
1428         return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
1429 }
1430
1431 static struct shrinker glock_shrinker = {
1432         .shrink = gfs2_shrink_glock_memory,
1433         .seeks = DEFAULT_SEEKS,
1434 };
1435
1436 /**
1437  * examine_bucket - Call a function for glock in a hash bucket
1438  * @examiner: the function
1439  * @sdp: the filesystem
1440  * @bucket: the bucket
1441  *
1442  */
1443
1444 static void examine_bucket(glock_examiner examiner, const struct gfs2_sbd *sdp,
1445                           unsigned int hash)
1446 {
1447         struct gfs2_glock *gl;
1448         struct hlist_bl_head *head = &gl_hash_table[hash];
1449         struct hlist_bl_node *pos;
1450
1451         rcu_read_lock();
1452         hlist_bl_for_each_entry_rcu(gl, pos, head, gl_list) {
1453                 if ((gl->gl_sbd == sdp) && atomic_read(&gl->gl_ref))
1454                         examiner(gl);
1455         }
1456         rcu_read_unlock();
1457         cond_resched();
1458 }
1459
1460 static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
1461 {
1462         unsigned x;
1463
1464         for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1465                 examine_bucket(examiner, sdp, x);
1466 }
1467
1468
1469 /**
1470  * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1471  * @gl: The glock to thaw
1472  *
1473  * N.B. When we freeze a glock, we leave a ref to the glock outstanding,
1474  * so this has to result in the ref count being dropped by one.
1475  */
1476
1477 static void thaw_glock(struct gfs2_glock *gl)
1478 {
1479         if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1480                 return;
1481         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1482         gfs2_glock_hold(gl);
1483         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1484                 gfs2_glock_put(gl);
1485 }
1486
1487 /**
1488  * clear_glock - look at a glock and see if we can free it from glock cache
1489  * @gl: the glock to look at
1490  *
1491  */
1492
1493 static void clear_glock(struct gfs2_glock *gl)
1494 {
1495         gfs2_glock_remove_from_lru(gl);
1496
1497         spin_lock(&gl->gl_spin);
1498         if (gl->gl_state != LM_ST_UNLOCKED)
1499                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1500         spin_unlock(&gl->gl_spin);
1501         gfs2_glock_hold(gl);
1502         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1503                 gfs2_glock_put(gl);
1504 }
1505
1506 /**
1507  * gfs2_glock_thaw - Thaw any frozen glocks
1508  * @sdp: The super block
1509  *
1510  */
1511
1512 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1513 {
1514         glock_hash_walk(thaw_glock, sdp);
1515 }
1516
1517 static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1518 {
1519         int ret;
1520         spin_lock(&gl->gl_spin);
1521         ret = __dump_glock(seq, gl);
1522         spin_unlock(&gl->gl_spin);
1523         return ret;
1524 }
1525
1526 static void dump_glock_func(struct gfs2_glock *gl)
1527 {
1528         dump_glock(NULL, gl);
1529 }
1530
1531 /**
1532  * gfs2_gl_hash_clear - Empty out the glock hash table
1533  * @sdp: the filesystem
1534  * @wait: wait until it's all gone
1535  *
1536  * Called when unmounting the filesystem.
1537  */
1538
1539 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1540 {
1541         glock_hash_walk(clear_glock, sdp);
1542         flush_workqueue(glock_workqueue);
1543         wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
1544         glock_hash_walk(dump_glock_func, 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 flags_buf[32];
1617
1618         if (gh->gh_owner_pid)
1619                 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1620         gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
1621                        state2str(gh->gh_state),
1622                        hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1623                        gh->gh_error,
1624                        gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1625                        gh_owner ? gh_owner->comm : "(ended)",
1626                        (void *)gh->gh_ip);
1627         return 0;
1628 }
1629
1630 static const char *gflags2str(char *buf, const struct gfs2_glock *gl)
1631 {
1632         const unsigned long *gflags = &gl->gl_flags;
1633         char *p = buf;
1634
1635         if (test_bit(GLF_LOCK, gflags))
1636                 *p++ = 'l';
1637         if (test_bit(GLF_DEMOTE, gflags))
1638                 *p++ = 'D';
1639         if (test_bit(GLF_PENDING_DEMOTE, gflags))
1640                 *p++ = 'd';
1641         if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1642                 *p++ = 'p';
1643         if (test_bit(GLF_DIRTY, gflags))
1644                 *p++ = 'y';
1645         if (test_bit(GLF_LFLUSH, gflags))
1646                 *p++ = 'f';
1647         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1648                 *p++ = 'i';
1649         if (test_bit(GLF_REPLY_PENDING, gflags))
1650                 *p++ = 'r';
1651         if (test_bit(GLF_INITIAL, gflags))
1652                 *p++ = 'I';
1653         if (test_bit(GLF_FROZEN, gflags))
1654                 *p++ = 'F';
1655         if (test_bit(GLF_QUEUED, gflags))
1656                 *p++ = 'q';
1657         if (test_bit(GLF_LRU, gflags))
1658                 *p++ = 'L';
1659         if (gl->gl_object)
1660                 *p++ = 'o';
1661         *p = 0;
1662         return buf;
1663 }
1664
1665 /**
1666  * __dump_glock - print information about a glock
1667  * @seq: The seq_file struct
1668  * @gl: the glock
1669  *
1670  * The file format is as follows:
1671  * One line per object, capital letters are used to indicate objects
1672  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1673  * other objects are indented by a single space and follow the glock to
1674  * which they are related. Fields are indicated by lower case letters
1675  * followed by a colon and the field value, except for strings which are in
1676  * [] so that its possible to see if they are composed of spaces for
1677  * example. The field's are n = number (id of the object), f = flags,
1678  * t = type, s = state, r = refcount, e = error, p = pid.
1679  *
1680  * Returns: 0 on success, -ENOBUFS when we run out of space
1681  */
1682
1683 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1684 {
1685         const struct gfs2_glock_operations *glops = gl->gl_ops;
1686         unsigned long long dtime;
1687         const struct gfs2_holder *gh;
1688         char gflags_buf[32];
1689         int error = 0;
1690
1691         dtime = jiffies - gl->gl_demote_time;
1692         dtime *= 1000000/HZ; /* demote time in uSec */
1693         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1694                 dtime = 0;
1695         gfs2_print_dbg(seq, "G:  s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d v:%d r:%d m:%ld\n",
1696                   state2str(gl->gl_state),
1697                   gl->gl_name.ln_type,
1698                   (unsigned long long)gl->gl_name.ln_number,
1699                   gflags2str(gflags_buf, gl),
1700                   state2str(gl->gl_target),
1701                   state2str(gl->gl_demote_state), dtime,
1702                   atomic_read(&gl->gl_ail_count),
1703                   atomic_read(&gl->gl_revokes),
1704                   atomic_read(&gl->gl_ref), gl->gl_hold_time);
1705
1706         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1707                 error = dump_holder(seq, gh);
1708                 if (error)
1709                         goto out;
1710         }
1711         if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1712                 error = glops->go_dump(seq, gl);
1713 out:
1714         return error;
1715 }
1716
1717
1718
1719
1720 int __init gfs2_glock_init(void)
1721 {
1722         unsigned i;
1723         for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
1724                 INIT_HLIST_BL_HEAD(&gl_hash_table[i]);
1725         }
1726
1727         glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
1728                                           WQ_HIGHPRI | WQ_FREEZABLE, 0);
1729         if (IS_ERR(glock_workqueue))
1730                 return PTR_ERR(glock_workqueue);
1731         gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
1732                                                 WQ_MEM_RECLAIM | WQ_FREEZABLE,
1733                                                 0);
1734         if (IS_ERR(gfs2_delete_workqueue)) {
1735                 destroy_workqueue(glock_workqueue);
1736                 return PTR_ERR(gfs2_delete_workqueue);
1737         }
1738
1739         register_shrinker(&glock_shrinker);
1740
1741         return 0;
1742 }
1743
1744 void gfs2_glock_exit(void)
1745 {
1746         unregister_shrinker(&glock_shrinker);
1747         destroy_workqueue(glock_workqueue);
1748         destroy_workqueue(gfs2_delete_workqueue);
1749 }
1750
1751 static inline struct gfs2_glock *glock_hash_chain(unsigned hash)
1752 {
1753         return hlist_bl_entry(hlist_bl_first_rcu(&gl_hash_table[hash]),
1754                               struct gfs2_glock, gl_list);
1755 }
1756
1757 static inline struct gfs2_glock *glock_hash_next(struct gfs2_glock *gl)
1758 {
1759         return hlist_bl_entry(rcu_dereference(gl->gl_list.next),
1760                               struct gfs2_glock, gl_list);
1761 }
1762
1763 static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1764 {
1765         struct gfs2_glock *gl;
1766
1767         do {
1768                 gl = gi->gl;
1769                 if (gl) {
1770                         gi->gl = glock_hash_next(gl);
1771                 } else {
1772                         gi->gl = glock_hash_chain(gi->hash);
1773                 }
1774                 while (gi->gl == NULL) {
1775                         gi->hash++;
1776                         if (gi->hash >= GFS2_GL_HASH_SIZE) {
1777                                 rcu_read_unlock();
1778                                 return 1;
1779                         }
1780                         gi->gl = glock_hash_chain(gi->hash);
1781                 }
1782         /* Skip entries for other sb and dead entries */
1783         } while (gi->sdp != gi->gl->gl_sbd || atomic_read(&gi->gl->gl_ref) == 0);
1784
1785         return 0;
1786 }
1787
1788 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1789 {
1790         struct gfs2_glock_iter *gi = seq->private;
1791         loff_t n = *pos;
1792
1793         gi->hash = 0;
1794         rcu_read_lock();
1795
1796         do {
1797                 if (gfs2_glock_iter_next(gi))
1798                         return NULL;
1799         } while (n--);
1800
1801         return gi->gl;
1802 }
1803
1804 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1805                                  loff_t *pos)
1806 {
1807         struct gfs2_glock_iter *gi = seq->private;
1808
1809         (*pos)++;
1810
1811         if (gfs2_glock_iter_next(gi))
1812                 return NULL;
1813
1814         return gi->gl;
1815 }
1816
1817 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1818 {
1819         struct gfs2_glock_iter *gi = seq->private;
1820
1821         if (gi->gl)
1822                 rcu_read_unlock();
1823         gi->gl = NULL;
1824 }
1825
1826 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1827 {
1828         return dump_glock(seq, iter_ptr);
1829 }
1830
1831 static const struct seq_operations gfs2_glock_seq_ops = {
1832         .start = gfs2_glock_seq_start,
1833         .next  = gfs2_glock_seq_next,
1834         .stop  = gfs2_glock_seq_stop,
1835         .show  = gfs2_glock_seq_show,
1836 };
1837
1838 static int gfs2_debugfs_open(struct inode *inode, struct file *file)
1839 {
1840         int ret = seq_open_private(file, &gfs2_glock_seq_ops,
1841                                    sizeof(struct gfs2_glock_iter));
1842         if (ret == 0) {
1843                 struct seq_file *seq = file->private_data;
1844                 struct gfs2_glock_iter *gi = seq->private;
1845                 gi->sdp = inode->i_private;
1846         }
1847         return ret;
1848 }
1849
1850 static const struct file_operations gfs2_debug_fops = {
1851         .owner   = THIS_MODULE,
1852         .open    = gfs2_debugfs_open,
1853         .read    = seq_read,
1854         .llseek  = seq_lseek,
1855         .release = seq_release_private,
1856 };
1857
1858 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
1859 {
1860         sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
1861         if (!sdp->debugfs_dir)
1862                 return -ENOMEM;
1863         sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
1864                                                          S_IFREG | S_IRUGO,
1865                                                          sdp->debugfs_dir, sdp,
1866                                                          &gfs2_debug_fops);
1867         if (!sdp->debugfs_dentry_glocks)
1868                 return -ENOMEM;
1869
1870         return 0;
1871 }
1872
1873 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
1874 {
1875         if (sdp && sdp->debugfs_dir) {
1876                 if (sdp->debugfs_dentry_glocks) {
1877                         debugfs_remove(sdp->debugfs_dentry_glocks);
1878                         sdp->debugfs_dentry_glocks = NULL;
1879                 }
1880                 debugfs_remove(sdp->debugfs_dir);
1881                 sdp->debugfs_dir = NULL;
1882         }
1883 }
1884
1885 int gfs2_register_debugfs(void)
1886 {
1887         gfs2_root = debugfs_create_dir("gfs2", NULL);
1888         return gfs2_root ? 0 : -ENOMEM;
1889 }
1890
1891 void gfs2_unregister_debugfs(void)
1892 {
1893         debugfs_remove(gfs2_root);
1894         gfs2_root = NULL;
1895 }