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         spin_lock(&lru_lock);
 173         if (!list_empty(&gl->gl_lru)) {
 174                 list_del_init(&gl->gl_lru);
 175                 atomic_dec(&lru_count);
 176                 clear_bit(GLF_LRU, &gl->gl_flags);
 177         }
 178         spin_unlock(&lru_lock);
 179 }
 180
 181 /**
 182  * __gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
 183  * @gl: the glock
 184  *
 185  * If the glock is demotable, then we add it (or move it) to the end
 186  * of the glock LRU list.
 187  */
 188
 189 static void __gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
 190 {
 191         if (demote_ok(gl))
 192                 gfs2_glock_add_to_lru(gl);
 193 }
 194
 195 /**
 196  * gfs2_glock_put_nolock() - Decrement reference count on glock
 197  * @gl: The glock to put
 198  *
 199  * This function should only be used if the caller has its own reference
 200  * to the glock, in addition to the one it is dropping.
 201  */
 202
 203 void gfs2_glock_put_nolock(struct gfs2_glock *gl)
 204 {
 205         if (atomic_dec_and_test(&gl->gl_ref))
 206                 GLOCK_BUG_ON(gl, 1);
 207 }
 208
 209 /**
 210  * gfs2_glock_put() - Decrement reference count on glock
 211  * @gl: The glock to put
 212  *
 213  */
 214
 215 void gfs2_glock_put(struct gfs2_glock *gl)
 216 {
 217         struct gfs2_sbd *sdp = gl->gl_sbd;
 218         struct address_space *mapping = gfs2_glock2aspace(gl);
 219
 220         if (atomic_dec_and_test(&gl->gl_ref)) {
 221                 spin_lock_bucket(gl->gl_hash);
 222                 hlist_bl_del_rcu(&gl->gl_list);
 223                 spin_unlock_bucket(gl->gl_hash);
 224                 gfs2_glock_remove_from_lru(gl);
 225                 GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
 226                 GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
 227                 trace_gfs2_glock_put(gl);
 228                 sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
 229         }
 230 }
 231
 232 /**
 233  * search_bucket() - Find struct gfs2_glock by lock number
 234  * @bucket: the bucket to search
 235  * @name: The lock name
 236  *
 237  * Returns: NULL, or the struct gfs2_glock with the requested number
 238  */
 239
 240 static struct gfs2_glock *search_bucket(unsigned int hash,
 241                                         const struct gfs2_sbd *sdp,
 242                                         const struct lm_lockname *name)
 243 {
 244         struct gfs2_glock *gl;
 245         struct hlist_bl_node *h;
 246
 247         hlist_bl_for_each_entry_rcu(gl, h, &gl_hash_table[hash], gl_list) {
 248                 if (!lm_name_equal(&gl->gl_name, name))
 249                         continue;
 250                 if (gl->gl_sbd != sdp)
 251                         continue;
 252                 if (atomic_inc_not_zero(&gl->gl_ref))
 253                         return gl;
 254         }
 255
 256         return NULL;
 257 }
 258
 259 /**
 260  * may_grant - check if its ok to grant a new lock
 261  * @gl: The glock
 262  * @gh: The lock request which we wish to grant
 263  *
 264  * Returns: true if its ok to grant the lock
 265  */
 266
 267 static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
 268 {
 269         const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
 270         if ((gh->gh_state == LM_ST_EXCLUSIVE ||
 271              gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
 272                 return 0;
 273         if (gl->gl_state == gh->gh_state)
 274                 return 1;
 275         if (gh->gh_flags & GL_EXACT)
 276                 return 0;
 277         if (gl->gl_state == LM_ST_EXCLUSIVE) {
 278                 if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
 279                         return 1;
 280                 if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
 281                         return 1;
 282         }
 283         if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
 284                 return 1;
 285         return 0;
 286 }
 287
 288 static void gfs2_holder_wake(struct gfs2_holder *gh)
 289 {
 290         clear_bit(HIF_WAIT, &gh->gh_iflags);
 291         smp_mb__after_clear_bit();
 292         wake_up_bit(&gh->gh_iflags, HIF_WAIT);
 293 }
 294
 295 /**
 296  * do_error - Something unexpected has happened during a lock request
 297  *
 298  */
 299
 300 static inline void do_error(struct gfs2_glock *gl, const int ret)
 301 {
 302         struct gfs2_holder *gh, *tmp;
 303
 304         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 305                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 306                         continue;
 307                 if (ret & LM_OUT_ERROR)
 308                         gh->gh_error = -EIO;
 309                 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
 310                         gh->gh_error = GLR_TRYFAILED;
 311                 else
 312                         continue;
 313                 list_del_init(&gh->gh_list);
 314                 trace_gfs2_glock_queue(gh, 0);
 315                 gfs2_holder_wake(gh);
 316         }
 317 }
 318
 319 /**
 320  * do_promote - promote as many requests as possible on the current queue
 321  * @gl: The glock
 322  *
 323  * Returns: 1 if there is a blocked holder at the head of the list, or 2
 324  *          if a type specific operation is underway.
 325  */
 326
 327 static int do_promote(struct gfs2_glock *gl)
 328 __releases(&gl->gl_spin)
 329 __acquires(&gl->gl_spin)
 330 {
 331         const struct gfs2_glock_operations *glops = gl->gl_ops;
 332         struct gfs2_holder *gh, *tmp;
 333         int ret;
 334
 335 restart:
 336         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 337                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 338                         continue;
 339                 if (may_grant(gl, gh)) {
 340                         if (gh->gh_list.prev == &gl->gl_holders &&
 341                             glops->go_lock) {
 342                                 spin_unlock(&gl->gl_spin);
 343                                 /* FIXME: eliminate this eventually */
 344                                 ret = glops->go_lock(gh);
 345                                 spin_lock(&gl->gl_spin);
 346                                 if (ret) {
 347                                         if (ret == 1)
 348                                                 return 2;
 349                                         gh->gh_error = ret;
 350                                         list_del_init(&gh->gh_list);
 351                                         trace_gfs2_glock_queue(gh, 0);
 352                                         gfs2_holder_wake(gh);
 353                                         goto restart;
 354                                 }
 355                                 set_bit(HIF_HOLDER, &gh->gh_iflags);
 356                                 trace_gfs2_promote(gh, 1);
 357                                 gfs2_holder_wake(gh);
 358                                 goto restart;
 359                         }
 360                         set_bit(HIF_HOLDER, &gh->gh_iflags);
 361                         trace_gfs2_promote(gh, 0);
 362                         gfs2_holder_wake(gh);
 363                         continue;
 364                 }
 365                 if (gh->gh_list.prev == &gl->gl_holders)
 366                         return 1;
 367                 do_error(gl, 0);
 368                 break;
 369         }
 370         return 0;
 371 }
 372
 373 /**
 374  * find_first_waiter - find the first gh that's waiting for the glock
 375  * @gl: the glock
 376  */
 377
 378 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
 379 {
 380         struct gfs2_holder *gh;
 381
 382         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
 383                 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
 384                         return gh;
 385         }
 386         return NULL;
 387 }
 388
 389 /**
 390  * state_change - record that the glock is now in a different state
 391  * @gl: the glock
 392  * @new_state the new state
 393  *
 394  */
 395
 396 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 397 {
 398         int held1, held2;
 399
 400         held1 = (gl->gl_state != LM_ST_UNLOCKED);
 401         held2 = (new_state != LM_ST_UNLOCKED);
 402
 403         if (held1 != held2) {
 404                 if (held2)
 405                         gfs2_glock_hold(gl);
 406                 else
 407                         gfs2_glock_put_nolock(gl);
 408         }
 409         if (held1 && held2 && list_empty(&gl->gl_holders))
 410                 clear_bit(GLF_QUEUED, &gl->gl_flags);
 411
 412         if (new_state != gl->gl_target)
 413                 /* shorten our minimum hold time */
 414                 gl->gl_hold_time = max(gl->gl_hold_time - GL_GLOCK_HOLD_DECR,
 415                                        GL_GLOCK_MIN_HOLD);
 416         gl->gl_state = new_state;
 417         gl->gl_tchange = jiffies;
 418 }
 419
 420 static void gfs2_demote_wake(struct gfs2_glock *gl)
 421 {
 422         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 423         clear_bit(GLF_DEMOTE, &gl->gl_flags);
 424         smp_mb__after_clear_bit();
 425         wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
 426 }
 427
 428 /**
 429  * finish_xmote - The DLM has replied to one of our lock requests
 430  * @gl: The glock
 431  * @ret: The status from the DLM
 432  *
 433  */
 434
 435 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
 436 {
 437         const struct gfs2_glock_operations *glops = gl->gl_ops;
 438         struct gfs2_holder *gh;
 439         unsigned state = ret & LM_OUT_ST_MASK;
 440         int rv;
 441
 442         spin_lock(&gl->gl_spin);
 443         trace_gfs2_glock_state_change(gl, state);
 444         state_change(gl, state);
 445         gh = find_first_waiter(gl);
 446
 447         /* Demote to UN request arrived during demote to SH or DF */
 448         if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
 449             state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
 450                 gl->gl_target = LM_ST_UNLOCKED;
 451
 452         /* Check for state != intended state */
 453         if (unlikely(state != gl->gl_target)) {
 454                 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
 455                         /* move to back of queue and try next entry */
 456                         if (ret & LM_OUT_CANCELED) {
 457                                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
 458                                         list_move_tail(&gh->gh_list, &gl->gl_holders);
 459                                 gh = find_first_waiter(gl);
 460                                 gl->gl_target = gh->gh_state;
 461                                 goto retry;
 462                         }
 463                         /* Some error or failed "try lock" - report it */
 464                         if ((ret & LM_OUT_ERROR) ||
 465                             (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 466                                 gl->gl_target = gl->gl_state;
 467                                 do_error(gl, ret);
 468                                 goto out;
 469                         }
 470                 }
 471                 switch(state) {
 472                 /* Unlocked due to conversion deadlock, try again */
 473                 case LM_ST_UNLOCKED:
 474 retry:
 475                         do_xmote(gl, gh, gl->gl_target);
 476                         break;
 477                 /* Conversion fails, unlock and try again */
 478                 case LM_ST_SHARED:
 479                 case LM_ST_DEFERRED:
 480                         do_xmote(gl, gh, LM_ST_UNLOCKED);
 481                         break;
 482                 default: /* Everything else */
 483                         printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
 484                         GLOCK_BUG_ON(gl, 1);
 485                 }
 486                 spin_unlock(&gl->gl_spin);
 487                 return;
 488         }
 489
 490         /* Fast path - we got what we asked for */
 491         if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
 492                 gfs2_demote_wake(gl);
 493         if (state != LM_ST_UNLOCKED) {
 494                 if (glops->go_xmote_bh) {
 495                         spin_unlock(&gl->gl_spin);
 496                         rv = glops->go_xmote_bh(gl, gh);
 497                         spin_lock(&gl->gl_spin);
 498                         if (rv) {
 499                                 do_error(gl, rv);
 500                                 goto out;
 501                         }
 502                 }
 503                 rv = do_promote(gl);
 504                 if (rv == 2)
 505                         goto out_locked;
 506         }
 507 out:
 508         clear_bit(GLF_LOCK, &gl->gl_flags);
 509 out_locked:
 510         spin_unlock(&gl->gl_spin);
 511 }
 512
 513 /**
 514  * do_xmote - Calls the DLM to change the state of a lock
 515  * @gl: The lock state
 516  * @gh: The holder (only for promotes)
 517  * @target: The target lock state
 518  *
 519  */
 520
 521 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
 522 __releases(&gl->gl_spin)
 523 __acquires(&gl->gl_spin)
 524 {
 525         const struct gfs2_glock_operations *glops = gl->gl_ops;
 526         struct gfs2_sbd *sdp = gl->gl_sbd;
 527         unsigned int lck_flags = gh ? gh->gh_flags : 0;
 528         int ret;
 529
 530         lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
 531                       LM_FLAG_PRIORITY);
 532         GLOCK_BUG_ON(gl, gl->gl_state == target);
 533         GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
 534         if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
 535             glops->go_inval) {
 536                 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 537                 do_error(gl, 0); /* Fail queued try locks */
 538         }
 539         gl->gl_req = target;
 540         spin_unlock(&gl->gl_spin);
 541         if (glops->go_xmote_th)
 542                 glops->go_xmote_th(gl);
 543         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 544                 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
 545         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 546
 547         gfs2_glock_hold(gl);
 548         if (sdp->sd_lockstruct.ls_ops->lm_lock) {
 549                 /* lock_dlm */
 550                 ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
 551                 GLOCK_BUG_ON(gl, ret);
 552         } else { /* lock_nolock */
 553                 finish_xmote(gl, target);
 554                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 555                         gfs2_glock_put(gl);
 556         }
 557
 558         spin_lock(&gl->gl_spin);
 559 }
 560
 561 /**
 562  * find_first_holder - find the first "holder" gh
 563  * @gl: the glock
 564  */
 565
 566 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
 567 {
 568         struct gfs2_holder *gh;
 569
 570         if (!list_empty(&gl->gl_holders)) {
 571                 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 572                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 573                         return gh;
 574         }
 575         return NULL;
 576 }
 577
 578 /**
 579  * run_queue - do all outstanding tasks related to a glock
 580  * @gl: The glock in question
 581  * @nonblock: True if we must not block in run_queue
 582  *
 583  */
 584
 585 static void run_queue(struct gfs2_glock *gl, const int nonblock)
 586 __releases(&gl->gl_spin)
 587 __acquires(&gl->gl_spin)
 588 {
 589         struct gfs2_holder *gh = NULL;
 590         int ret;
 591
 592         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 593                 return;
 594
 595         GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
 596
 597         if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
 598             gl->gl_demote_state != gl->gl_state) {
 599                 if (find_first_holder(gl))
 600                         goto out_unlock;
 601                 if (nonblock)
 602                         goto out_sched;
 603                 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
 604                 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
 605                 gl->gl_target = gl->gl_demote_state;
 606         } else {
 607                 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
 608                         gfs2_demote_wake(gl);
 609                 ret = do_promote(gl);
 610                 if (ret == 0)
 611                         goto out_unlock;
 612                 if (ret == 2)
 613                         goto out;
 614                 gh = find_first_waiter(gl);
 615                 gl->gl_target = gh->gh_state;
 616                 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 617                         do_error(gl, 0); /* Fail queued try locks */
 618         }
 619         do_xmote(gl, gh, gl->gl_target);
 620 out:
 621         return;
 622
 623 out_sched:
 624         clear_bit(GLF_LOCK, &gl->gl_flags);
 625         smp_mb__after_clear_bit();
 626         gfs2_glock_hold(gl);
 627         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 628                 gfs2_glock_put_nolock(gl);
 629         return;
 630
 631 out_unlock:
 632         clear_bit(GLF_LOCK, &gl->gl_flags);
 633         smp_mb__after_clear_bit();
 634         return;
 635 }
 636
 637 static void delete_work_func(struct work_struct *work)
 638 {
 639         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
 640         struct gfs2_sbd *sdp = gl->gl_sbd;
 641         struct gfs2_inode *ip;
 642         struct inode *inode;
 643         u64 no_addr = gl->gl_name.ln_number;
 644
 645         ip = gl->gl_object;
 646         /* Note: Unsafe to dereference ip as we don't hold right refs/locks */
 647
 648         if (ip)
 649                 inode = gfs2_ilookup(sdp->sd_vfs, no_addr, 1);
 650         else
 651                 inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
 652         if (inode && !IS_ERR(inode)) {
 653                 d_prune_aliases(inode);
 654                 iput(inode);
 655         }
 656         gfs2_glock_put(gl);
 657 }
 658
 659 static void glock_work_func(struct work_struct *work)
 660 {
 661         unsigned long delay = 0;
 662         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
 663         int drop_ref = 0;
 664
 665         if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
 666                 finish_xmote(gl, gl->gl_reply);
 667                 drop_ref = 1;
 668         }
 669         spin_lock(&gl->gl_spin);
 670         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
 671             gl->gl_state != LM_ST_UNLOCKED &&
 672             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
 673                 unsigned long holdtime, now = jiffies;
 674
 675                 holdtime = gl->gl_tchange + gl->gl_hold_time;
 676                 if (time_before(now, holdtime))
 677                         delay = holdtime - now;
 678
 679                 if (!delay) {
 680                         clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
 681                         set_bit(GLF_DEMOTE, &gl->gl_flags);
 682                 }
 683         }
 684         run_queue(gl, 0);
 685         spin_unlock(&gl->gl_spin);
 686         if (!delay)
 687                 gfs2_glock_put(gl);
 688         else {
 689                 if (gl->gl_name.ln_type != LM_TYPE_INODE)
 690                         delay = 0;
 691                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
 692                         gfs2_glock_put(gl);
 693         }
 694         if (drop_ref)
 695                 gfs2_glock_put(gl);
 696 }
 697
 698 /**
 699  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
 700  * @sdp: The GFS2 superblock
 701  * @number: the lock number
 702  * @glops: The glock_operations to use
 703  * @create: If 0, don't create the glock if it doesn't exist
 704  * @glp: the glock is returned here
 705  *
 706  * This does not lock a glock, just finds/creates structures for one.
 707  *
 708  * Returns: errno
 709  */
 710
 711 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 712                    const struct gfs2_glock_operations *glops, int create,
 713                    struct gfs2_glock **glp)
 714 {
 715         struct super_block *s = sdp->sd_vfs;
 716         struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
 717         struct gfs2_glock *gl, *tmp;
 718         unsigned int hash = gl_hash(sdp, &name);
 719         struct address_space *mapping;
 720         struct kmem_cache *cachep;
 721
 722         rcu_read_lock();
 723         gl = search_bucket(hash, sdp, &name);
 724         rcu_read_unlock();
 725
 726         *glp = gl;
 727         if (gl)
 728                 return 0;
 729         if (!create)
 730                 return -ENOENT;
 731
 732         if (glops->go_flags & GLOF_ASPACE)
 733                 cachep = gfs2_glock_aspace_cachep;
 734         else
 735                 cachep = gfs2_glock_cachep;
 736         gl = kmem_cache_alloc(cachep, GFP_KERNEL);
 737         if (!gl)
 738                 return -ENOMEM;
 739
 740         atomic_inc(&sdp->sd_glock_disposal);
 741         gl->gl_flags = 0;
 742         gl->gl_name = name;
 743         atomic_set(&gl->gl_ref, 1);
 744         gl->gl_state = LM_ST_UNLOCKED;
 745         gl->gl_target = LM_ST_UNLOCKED;
 746         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 747         gl->gl_hash = hash;
 748         gl->gl_ops = glops;
 749         snprintf(gl->gl_strname, GDLM_STRNAME_BYTES, "%8x%16llx", name.ln_type, (unsigned long long)number);
 750         memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
 751         gl->gl_lksb.sb_lvbptr = gl->gl_lvb;
 752         gl->gl_tchange = jiffies;
 753         gl->gl_object = NULL;
 754         gl->gl_sbd = sdp;
 755         gl->gl_hold_time = GL_GLOCK_DFT_HOLD;
 756         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
 757         INIT_WORK(&gl->gl_delete, delete_work_func);
 758
 759         mapping = gfs2_glock2aspace(gl);
 760         if (mapping) {
 761                 mapping->a_ops = &gfs2_meta_aops;
 762                 mapping->host = s->s_bdev->bd_inode;
 763                 mapping->flags = 0;
 764                 mapping_set_gfp_mask(mapping, GFP_NOFS);
 765                 mapping->assoc_mapping = NULL;
 766                 mapping->backing_dev_info = s->s_bdi;
 767                 mapping->writeback_index = 0;
 768         }
 769
 770         spin_lock_bucket(hash);
 771         tmp = search_bucket(hash, sdp, &name);
 772         if (tmp) {
 773                 spin_unlock_bucket(hash);
 774                 kmem_cache_free(cachep, gl);
 775                 atomic_dec(&sdp->sd_glock_disposal);
 776                 gl = tmp;
 777         } else {
 778                 hlist_bl_add_head_rcu(&gl->gl_list, &gl_hash_table[hash]);
 779                 spin_unlock_bucket(hash);
 780         }
 781
 782         *glp = gl;
 783
 784         return 0;
 785 }
 786
 787 /**
 788  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
 789  * @gl: the glock
 790  * @state: the state we're requesting
 791  * @flags: the modifier flags
 792  * @gh: the holder structure
 793  *
 794  */
 795
 796 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
 797                       struct gfs2_holder *gh)
 798 {
 799         INIT_LIST_HEAD(&gh->gh_list);
 800         gh->gh_gl = gl;
 801         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 802         gh->gh_owner_pid = get_pid(task_pid(current));
 803         gh->gh_state = state;
 804         gh->gh_flags = flags;
 805         gh->gh_error = 0;
 806         gh->gh_iflags = 0;
 807         gfs2_glock_hold(gl);
 808 }
 809
 810 /**
 811  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
 812  * @state: the state we're requesting
 813  * @flags: the modifier flags
 814  * @gh: the holder structure
 815  *
 816  * Don't mess with the glock.
 817  *
 818  */
 819
 820 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
 821 {
 822         gh->gh_state = state;
 823         gh->gh_flags = flags;
 824         gh->gh_iflags = 0;
 825         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 826         if (gh->gh_owner_pid)
 827                 put_pid(gh->gh_owner_pid);
 828         gh->gh_owner_pid = get_pid(task_pid(current));
 829 }
 830
 831 /**
 832  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 833  * @gh: the holder structure
 834  *
 835  */
 836
 837 void gfs2_holder_uninit(struct gfs2_holder *gh)
 838 {
 839         put_pid(gh->gh_owner_pid);
 840         gfs2_glock_put(gh->gh_gl);
 841         gh->gh_gl = NULL;
 842         gh->gh_ip = 0;
 843 }
 844
 845 /**
 846  * gfs2_glock_holder_wait
 847  * @word: unused
 848  *
 849  * This function and gfs2_glock_demote_wait both show up in the WCHAN
 850  * field. Thus I've separated these otherwise identical functions in
 851  * order to be more informative to the user.
 852  */
 853
 854 static int gfs2_glock_holder_wait(void *word)
 855 {
 856         schedule();
 857         return 0;
 858 }
 859
 860 static int gfs2_glock_demote_wait(void *word)
 861 {
 862         schedule();
 863         return 0;
 864 }
 865
 866 static void wait_on_holder(struct gfs2_holder *gh)
 867 {
 868         unsigned long time1 = jiffies;
 869
 870         might_sleep();
 871         wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
 872         if (time_after(jiffies, time1 + HZ)) /* have we waited > a second? */
 873                 /* Lengthen the minimum hold time. */
 874                 gh->gh_gl->gl_hold_time = min(gh->gh_gl->gl_hold_time +
 875                                               GL_GLOCK_HOLD_INCR,
 876                                               GL_GLOCK_MAX_HOLD);
 877 }
 878
 879 static void wait_on_demote(struct gfs2_glock *gl)
 880 {
 881         might_sleep();
 882         wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
 883 }
 884
 885 /**
 886  * handle_callback - process a demote request
 887  * @gl: the glock
 888  * @state: the state the caller wants us to change to
 889  *
 890  * There are only two requests that we are going to see in actual
 891  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
 892  */
 893
 894 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
 895                             unsigned long delay)
 896 {
 897         int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
 898
 899         set_bit(bit, &gl->gl_flags);
 900         if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
 901                 gl->gl_demote_state = state;
 902                 gl->gl_demote_time = jiffies;
 903         } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
 904                         gl->gl_demote_state != state) {
 905                 gl->gl_demote_state = LM_ST_UNLOCKED;
 906         }
 907         if (gl->gl_ops->go_callback)
 908                 gl->gl_ops->go_callback(gl);
 909         trace_gfs2_demote_rq(gl);
 910 }
 911
 912 /**
 913  * gfs2_glock_wait - wait on a glock acquisition
 914  * @gh: the glock holder
 915  *
 916  * Returns: 0 on success
 917  */
 918
 919 int gfs2_glock_wait(struct gfs2_holder *gh)
 920 {
 921         wait_on_holder(gh);
 922         return gh->gh_error;
 923 }
 924
 925 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
 926 {
 927         struct va_format vaf;
 928         va_list args;
 929
 930         va_start(args, fmt);
 931
 932         if (seq) {
 933                 struct gfs2_glock_iter *gi = seq->private;
 934                 vsprintf(gi->string, fmt, args);
 935                 seq_printf(seq, gi->string);
 936         } else {
 937                 vaf.fmt = fmt;
 938                 vaf.va = &args;
 939
 940                 printk(KERN_ERR " %pV", &vaf);
 941         }
 942
 943         va_end(args);
 944 }
 945
 946 /**
 947  * add_to_queue - Add a holder to the wait queue (but look for recursion)
 948  * @gh: the holder structure to add
 949  *
 950  * Eventually we should move the recursive locking trap to a
 951  * debugging option or something like that. This is the fast
 952  * path and needs to have the minimum number of distractions.
 953  *
 954  */
 955
 956 static inline void add_to_queue(struct gfs2_holder *gh)
 957 __releases(&gl->gl_spin)
 958 __acquires(&gl->gl_spin)
 959 {
 960         struct gfs2_glock *gl = gh->gh_gl;
 961         struct gfs2_sbd *sdp = gl->gl_sbd;
 962         struct list_head *insert_pt = NULL;
 963         struct gfs2_holder *gh2;
 964         int try_lock = 0;
 965
 966         BUG_ON(gh->gh_owner_pid == NULL);
 967         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
 968                 BUG();
 969
 970         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
 971                 if (test_bit(GLF_LOCK, &gl->gl_flags))
 972                         try_lock = 1;
 973                 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 974                         goto fail;
 975         }
 976
 977         list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
 978                 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
 979                     (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
 980                         goto trap_recursive;
 981                 if (try_lock &&
 982                     !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
 983                     !may_grant(gl, gh)) {
 984 fail:
 985                         gh->gh_error = GLR_TRYFAILED;
 986                         gfs2_holder_wake(gh);
 987                         return;
 988                 }
 989                 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
 990                         continue;
 991                 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
 992                         insert_pt = &gh2->gh_list;
 993         }
 994         set_bit(GLF_QUEUED, &gl->gl_flags);
 995         trace_gfs2_glock_queue(gh, 1);
 996         if (likely(insert_pt == NULL)) {
 997                 list_add_tail(&gh->gh_list, &gl->gl_holders);
 998                 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
 999                         goto do_cancel;
1000                 return;
1001         }
1002         list_add_tail(&gh->gh_list, insert_pt);
1003 do_cancel:
1004         gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
1005         if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
1006                 spin_unlock(&gl->gl_spin);
1007                 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
1008                         sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
1009                 spin_lock(&gl->gl_spin);
1010         }
1011         return;
1012
1013 trap_recursive:
1014         print_symbol(KERN_ERR "original: %s\n", gh2->gh_ip);
1015         printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
1016         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1017                gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
1018         print_symbol(KERN_ERR "new: %s\n", gh->gh_ip);
1019         printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
1020         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1021                gh->gh_gl->gl_name.ln_type, gh->gh_state);
1022         __dump_glock(NULL, gl);
1023         BUG();
1024 }
1025
1026 /**
1027  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1028  * @gh: the holder structure
1029  *
1030  * if (gh->gh_flags & GL_ASYNC), this never returns an error
1031  *
1032  * Returns: 0, GLR_TRYFAILED, or errno on failure
1033  */
1034
1035 int gfs2_glock_nq(struct gfs2_holder *gh)
1036 {
1037         struct gfs2_glock *gl = gh->gh_gl;
1038         struct gfs2_sbd *sdp = gl->gl_sbd;
1039         int error = 0;
1040
1041         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
1042                 return -EIO;
1043
1044         if (test_bit(GLF_LRU, &gl->gl_flags))
1045                 gfs2_glock_remove_from_lru(gl);
1046
1047         spin_lock(&gl->gl_spin);
1048         add_to_queue(gh);
1049         if ((LM_FLAG_NOEXP & gh->gh_flags) &&
1050             test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1051                 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1052         run_queue(gl, 1);
1053         spin_unlock(&gl->gl_spin);
1054
1055         if (!(gh->gh_flags & GL_ASYNC))
1056                 error = gfs2_glock_wait(gh);
1057
1058         return error;
1059 }
1060
1061 /**
1062  * gfs2_glock_poll - poll to see if an async request has been completed
1063  * @gh: the holder
1064  *
1065  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1066  */
1067
1068 int gfs2_glock_poll(struct gfs2_holder *gh)
1069 {
1070         return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1071 }
1072
1073 /**
1074  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1075  * @gh: the glock holder
1076  *
1077  */
1078
1079 void gfs2_glock_dq(struct gfs2_holder *gh)
1080 {
1081         struct gfs2_glock *gl = gh->gh_gl;
1082         const struct gfs2_glock_operations *glops = gl->gl_ops;
1083         unsigned delay = 0;
1084         int fast_path = 0;
1085
1086         spin_lock(&gl->gl_spin);
1087         if (gh->gh_flags & GL_NOCACHE)
1088                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1089
1090         list_del_init(&gh->gh_list);
1091         if (find_first_holder(gl) == NULL) {
1092                 if (glops->go_unlock) {
1093                         GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1094                         spin_unlock(&gl->gl_spin);
1095                         glops->go_unlock(gh);
1096                         spin_lock(&gl->gl_spin);
1097                         clear_bit(GLF_LOCK, &gl->gl_flags);
1098                 }
1099                 if (list_empty(&gl->gl_holders) &&
1100                     !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1101                     !test_bit(GLF_DEMOTE, &gl->gl_flags))
1102                         fast_path = 1;
1103         }
1104         if (!test_bit(GLF_LFLUSH, &gl->gl_flags))
1105                 __gfs2_glock_schedule_for_reclaim(gl);
1106         trace_gfs2_glock_queue(gh, 0);
1107         spin_unlock(&gl->gl_spin);
1108         if (likely(fast_path))
1109                 return;
1110
1111         gfs2_glock_hold(gl);
1112         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1113             !test_bit(GLF_DEMOTE, &gl->gl_flags) &&
1114             gl->gl_name.ln_type == LM_TYPE_INODE)
1115                 delay = gl->gl_hold_time;
1116         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1117                 gfs2_glock_put(gl);
1118 }
1119
1120 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1121 {
1122         struct gfs2_glock *gl = gh->gh_gl;
1123         gfs2_glock_dq(gh);
1124         wait_on_demote(gl);
1125 }
1126
1127 /**
1128  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1129  * @gh: the holder structure
1130  *
1131  */
1132
1133 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1134 {
1135         gfs2_glock_dq(gh);
1136         gfs2_holder_uninit(gh);
1137 }
1138
1139 /**
1140  * gfs2_glock_nq_num - acquire a glock based on lock number
1141  * @sdp: the filesystem
1142  * @number: the lock number
1143  * @glops: the glock operations for the type of glock
1144  * @state: the state to acquire the glock in
1145  * @flags: modifier flags for the acquisition
1146  * @gh: the struct gfs2_holder
1147  *
1148  * Returns: errno
1149  */
1150
1151 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1152                       const struct gfs2_glock_operations *glops,
1153                       unsigned int state, int flags, struct gfs2_holder *gh)
1154 {
1155         struct gfs2_glock *gl;
1156         int error;
1157
1158         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1159         if (!error) {
1160                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1161                 gfs2_glock_put(gl);
1162         }
1163
1164         return error;
1165 }
1166
1167 /**
1168  * glock_compare - Compare two struct gfs2_glock structures for sorting
1169  * @arg_a: the first structure
1170  * @arg_b: the second structure
1171  *
1172  */
1173
1174 static int glock_compare(const void *arg_a, const void *arg_b)
1175 {
1176         const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1177         const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1178         const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1179         const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1180
1181         if (a->ln_number > b->ln_number)
1182                 return 1;
1183         if (a->ln_number < b->ln_number)
1184                 return -1;
1185         BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1186         return 0;
1187 }
1188
1189 /**
1190  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1191  * @num_gh: the number of structures
1192  * @ghs: an array of struct gfs2_holder structures
1193  *
1194  * Returns: 0 on success (all glocks acquired),
1195  *          errno on failure (no glocks acquired)
1196  */
1197
1198 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1199                      struct gfs2_holder **p)
1200 {
1201         unsigned int x;
1202         int error = 0;
1203
1204         for (x = 0; x < num_gh; x++)
1205                 p[x] = &ghs[x];
1206
1207         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1208
1209         for (x = 0; x < num_gh; x++) {
1210                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1211
1212                 error = gfs2_glock_nq(p[x]);
1213                 if (error) {
1214                         while (x--)
1215                                 gfs2_glock_dq(p[x]);
1216                         break;
1217                 }
1218         }
1219
1220         return error;
1221 }
1222
1223 /**
1224  * gfs2_glock_nq_m - acquire multiple glocks
1225  * @num_gh: the number of structures
1226  * @ghs: an array of struct gfs2_holder structures
1227  *
1228  *
1229  * Returns: 0 on success (all glocks acquired),
1230  *          errno on failure (no glocks acquired)
1231  */
1232
1233 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1234 {
1235         struct gfs2_holder *tmp[4];
1236         struct gfs2_holder **pph = tmp;
1237         int error = 0;
1238
1239         switch(num_gh) {
1240         case 0:
1241                 return 0;
1242         case 1:
1243                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1244                 return gfs2_glock_nq(ghs);
1245         default:
1246                 if (num_gh <= 4)
1247                         break;
1248                 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1249                 if (!pph)
1250                         return -ENOMEM;
1251         }
1252
1253         error = nq_m_sync(num_gh, ghs, pph);
1254
1255         if (pph != tmp)
1256                 kfree(pph);
1257
1258         return error;
1259 }
1260
1261 /**
1262  * gfs2_glock_dq_m - release multiple glocks
1263  * @num_gh: the number of structures
1264  * @ghs: an array of struct gfs2_holder structures
1265  *
1266  */
1267
1268 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1269 {
1270         while (num_gh--)
1271                 gfs2_glock_dq(&ghs[num_gh]);
1272 }
1273
1274 /**
1275  * gfs2_glock_dq_uninit_m - release multiple glocks
1276  * @num_gh: the number of structures
1277  * @ghs: an array of struct gfs2_holder structures
1278  *
1279  */
1280
1281 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1282 {
1283         while (num_gh--)
1284                 gfs2_glock_dq_uninit(&ghs[num_gh]);
1285 }
1286
1287 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1288 {
1289         unsigned long delay = 0;
1290         unsigned long holdtime;
1291         unsigned long now = jiffies;
1292
1293         gfs2_glock_hold(gl);
1294         holdtime = gl->gl_tchange + gl->gl_hold_time;
1295         if (test_bit(GLF_QUEUED, &gl->gl_flags) &&
1296             gl->gl_name.ln_type == LM_TYPE_INODE) {
1297                 if (time_before(now, holdtime))
1298                         delay = holdtime - now;
1299                 if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1300                         delay = gl->gl_hold_time;
1301         }
1302
1303         spin_lock(&gl->gl_spin);
1304         handle_callback(gl, state, delay);
1305         spin_unlock(&gl->gl_spin);
1306         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1307                 gfs2_glock_put(gl);
1308 }
1309
1310 /**
1311  * gfs2_should_freeze - Figure out if glock should be frozen
1312  * @gl: The glock in question
1313  *
1314  * Glocks are not frozen if (a) the result of the dlm operation is
1315  * an error, (b) the locking operation was an unlock operation or
1316  * (c) if there is a "noexp" flagged request anywhere in the queue
1317  *
1318  * Returns: 1 if freezing should occur, 0 otherwise
1319  */
1320
1321 static int gfs2_should_freeze(const struct gfs2_glock *gl)
1322 {
1323         const struct gfs2_holder *gh;
1324
1325         if (gl->gl_reply & ~LM_OUT_ST_MASK)
1326                 return 0;
1327         if (gl->gl_target == LM_ST_UNLOCKED)
1328                 return 0;
1329
1330         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1331                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1332                         continue;
1333                 if (LM_FLAG_NOEXP & gh->gh_flags)
1334                         return 0;
1335         }
1336
1337         return 1;
1338 }
1339
1340 /**
1341  * gfs2_glock_complete - Callback used by locking
1342  * @gl: Pointer to the glock
1343  * @ret: The return value from the dlm
1344  *
1345  * The gl_reply field is under the gl_spin lock so that it is ok
1346  * to use a bitfield shared with other glock state fields.
1347  */
1348
1349 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1350 {
1351         struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
1352
1353         spin_lock(&gl->gl_spin);
1354         gl->gl_reply = ret;
1355
1356         if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_flags))) {
1357                 if (gfs2_should_freeze(gl)) {
1358                         set_bit(GLF_FROZEN, &gl->gl_flags);
1359                         spin_unlock(&gl->gl_spin);
1360                         return;
1361                 }
1362         }
1363
1364         spin_unlock(&gl->gl_spin);
1365         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1366         smp_wmb();
1367         gfs2_glock_hold(gl);
1368         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1369                 gfs2_glock_put(gl);
1370 }
1371
1372
1373 static int gfs2_shrink_glock_memory(struct shrinker *shrink,
1374                                     struct shrink_control *sc)
1375 {
1376         struct gfs2_glock *gl;
1377         int may_demote;
1378         int nr_skipped = 0;
1379         int nr = sc->nr_to_scan;
1380         gfp_t gfp_mask = sc->gfp_mask;
1381         LIST_HEAD(skipped);
1382
1383         if (nr == 0)
1384                 goto out;
1385
1386         if (!(gfp_mask & __GFP_FS))
1387                 return -1;
1388
1389         spin_lock(&lru_lock);
1390         while(nr && !list_empty(&lru_list)) {
1391                 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1392                 list_del_init(&gl->gl_lru);
1393                 clear_bit(GLF_LRU, &gl->gl_flags);
1394                 atomic_dec(&lru_count);
1395
1396                 /* Test for being demotable */
1397                 if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1398                         gfs2_glock_hold(gl);
1399                         spin_unlock(&lru_lock);
1400                         spin_lock(&gl->gl_spin);
1401                         may_demote = demote_ok(gl);
1402                         if (may_demote) {
1403                                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1404                                 nr--;
1405                         }
1406                         clear_bit(GLF_LOCK, &gl->gl_flags);
1407                         smp_mb__after_clear_bit();
1408                         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1409                                 gfs2_glock_put_nolock(gl);
1410                         spin_unlock(&gl->gl_spin);
1411                         spin_lock(&lru_lock);
1412                         continue;
1413                 }
1414                 nr_skipped++;
1415                 list_add(&gl->gl_lru, &skipped);
1416                 set_bit(GLF_LRU, &gl->gl_flags);
1417         }
1418         list_splice(&skipped, &lru_list);
1419         atomic_add(nr_skipped, &lru_count);
1420         spin_unlock(&lru_lock);
1421 out:
1422         return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
1423 }
1424
1425 static struct shrinker glock_shrinker = {
1426         .shrink = gfs2_shrink_glock_memory,
1427         .seeks = DEFAULT_SEEKS,
1428 };
1429
1430 /**
1431  * examine_bucket - Call a function for glock in a hash bucket
1432  * @examiner: the function
1433  * @sdp: the filesystem
1434  * @bucket: the bucket
1435  *
1436  */
1437
1438 static void examine_bucket(glock_examiner examiner, const struct gfs2_sbd *sdp,
1439                           unsigned int hash)
1440 {
1441         struct gfs2_glock *gl;
1442         struct hlist_bl_head *head = &gl_hash_table[hash];
1443         struct hlist_bl_node *pos;
1444
1445         rcu_read_lock();
1446         hlist_bl_for_each_entry_rcu(gl, pos, head, gl_list) {
1447                 if ((gl->gl_sbd == sdp) && atomic_read(&gl->gl_ref))
1448                         examiner(gl);
1449         }
1450         rcu_read_unlock();
1451         cond_resched();
1452 }
1453
1454 static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
1455 {
1456         unsigned x;
1457
1458         for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1459                 examine_bucket(examiner, sdp, x);
1460 }
1461
1462
1463 /**
1464  * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1465  * @gl: The glock to thaw
1466  *
1467  * N.B. When we freeze a glock, we leave a ref to the glock outstanding,
1468  * so this has to result in the ref count being dropped by one.
1469  */
1470
1471 static void thaw_glock(struct gfs2_glock *gl)
1472 {
1473         if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1474                 return;
1475         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1476         gfs2_glock_hold(gl);
1477         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1478                 gfs2_glock_put(gl);
1479 }
1480
1481 /**
1482  * clear_glock - look at a glock and see if we can free it from glock cache
1483  * @gl: the glock to look at
1484  *
1485  */
1486
1487 static void clear_glock(struct gfs2_glock *gl)
1488 {
1489         gfs2_glock_remove_from_lru(gl);
1490
1491         spin_lock(&gl->gl_spin);
1492         if (gl->gl_state != LM_ST_UNLOCKED)
1493                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1494         spin_unlock(&gl->gl_spin);
1495         gfs2_glock_hold(gl);
1496         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1497                 gfs2_glock_put(gl);
1498 }
1499
1500 /**
1501  * gfs2_glock_thaw - Thaw any frozen glocks
1502  * @sdp: The super block
1503  *
1504  */
1505
1506 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1507 {
1508         glock_hash_walk(thaw_glock, sdp);
1509 }
1510
1511 static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1512 {
1513         int ret;
1514         spin_lock(&gl->gl_spin);
1515         ret = __dump_glock(seq, gl);
1516         spin_unlock(&gl->gl_spin);
1517         return ret;
1518 }
1519
1520 static void dump_glock_func(struct gfs2_glock *gl)
1521 {
1522         dump_glock(NULL, gl);
1523 }
1524
1525 /**
1526  * gfs2_gl_hash_clear - Empty out the glock hash table
1527  * @sdp: the filesystem
1528  * @wait: wait until it's all gone
1529  *
1530  * Called when unmounting the filesystem.
1531  */
1532
1533 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1534 {
1535         glock_hash_walk(clear_glock, sdp);
1536         flush_workqueue(glock_workqueue);
1537         wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
1538         glock_hash_walk(dump_glock_func, sdp);
1539 }
1540
1541 void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1542 {
1543         struct gfs2_glock *gl = ip->i_gl;
1544         int ret;
1545
1546         ret = gfs2_truncatei_resume(ip);
1547         gfs2_assert_withdraw(gl->gl_sbd, ret == 0);
1548
1549         spin_lock(&gl->gl_spin);
1550         clear_bit(GLF_LOCK, &gl->gl_flags);
1551         run_queue(gl, 1);
1552         spin_unlock(&gl->gl_spin);
1553 }
1554
1555 static const char *state2str(unsigned state)
1556 {
1557         switch(state) {
1558         case LM_ST_UNLOCKED:
1559                 return "UN";
1560         case LM_ST_SHARED:
1561                 return "SH";
1562         case LM_ST_DEFERRED:
1563                 return "DF";
1564         case LM_ST_EXCLUSIVE:
1565                 return "EX";
1566         }
1567         return "??";
1568 }
1569
1570 static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags)
1571 {
1572         char *p = buf;
1573         if (flags & LM_FLAG_TRY)
1574                 *p++ = 't';
1575         if (flags & LM_FLAG_TRY_1CB)
1576                 *p++ = 'T';
1577         if (flags & LM_FLAG_NOEXP)
1578                 *p++ = 'e';
1579         if (flags & LM_FLAG_ANY)
1580                 *p++ = 'A';
1581         if (flags & LM_FLAG_PRIORITY)
1582                 *p++ = 'p';
1583         if (flags & GL_ASYNC)
1584                 *p++ = 'a';
1585         if (flags & GL_EXACT)
1586                 *p++ = 'E';
1587         if (flags & GL_NOCACHE)
1588                 *p++ = 'c';
1589         if (test_bit(HIF_HOLDER, &iflags))
1590                 *p++ = 'H';
1591         if (test_bit(HIF_WAIT, &iflags))
1592                 *p++ = 'W';
1593         if (test_bit(HIF_FIRST, &iflags))
1594                 *p++ = 'F';
1595         *p = 0;
1596         return buf;
1597 }
1598
1599 /**
1600  * dump_holder - print information about a glock holder
1601  * @seq: the seq_file struct
1602  * @gh: the glock holder
1603  *
1604  * Returns: 0 on success, -ENOBUFS when we run out of space
1605  */
1606
1607 static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1608 {
1609         struct task_struct *gh_owner = NULL;
1610         char flags_buf[32];
1611
1612         if (gh->gh_owner_pid)
1613                 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1614         gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
1615                        state2str(gh->gh_state),
1616                        hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1617                        gh->gh_error,
1618                        gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1619                        gh_owner ? gh_owner->comm : "(ended)",
1620                        (void *)gh->gh_ip);
1621         return 0;
1622 }
1623
1624 static const char *gflags2str(char *buf, const struct gfs2_glock *gl)
1625 {
1626         const unsigned long *gflags = &gl->gl_flags;
1627         char *p = buf;
1628
1629         if (test_bit(GLF_LOCK, gflags))
1630                 *p++ = 'l';
1631         if (test_bit(GLF_DEMOTE, gflags))
1632                 *p++ = 'D';
1633         if (test_bit(GLF_PENDING_DEMOTE, gflags))
1634                 *p++ = 'd';
1635         if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1636                 *p++ = 'p';
1637         if (test_bit(GLF_DIRTY, gflags))
1638                 *p++ = 'y';
1639         if (test_bit(GLF_LFLUSH, gflags))
1640                 *p++ = 'f';
1641         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1642                 *p++ = 'i';
1643         if (test_bit(GLF_REPLY_PENDING, gflags))
1644                 *p++ = 'r';
1645         if (test_bit(GLF_INITIAL, gflags))
1646                 *p++ = 'I';
1647         if (test_bit(GLF_FROZEN, gflags))
1648                 *p++ = 'F';
1649         if (test_bit(GLF_QUEUED, gflags))
1650                 *p++ = 'q';
1651         if (test_bit(GLF_LRU, gflags))
1652                 *p++ = 'L';
1653         if (gl->gl_object)
1654                 *p++ = 'o';
1655         *p = 0;
1656         return buf;
1657 }
1658
1659 /**
1660  * __dump_glock - print information about a glock
1661  * @seq: The seq_file struct
1662  * @gl: the glock
1663  *
1664  * The file format is as follows:
1665  * One line per object, capital letters are used to indicate objects
1666  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1667  * other objects are indented by a single space and follow the glock to
1668  * which they are related. Fields are indicated by lower case letters
1669  * followed by a colon and the field value, except for strings which are in
1670  * [] so that its possible to see if they are composed of spaces for
1671  * example. The field's are n = number (id of the object), f = flags,
1672  * t = type, s = state, r = refcount, e = error, p = pid.
1673  *
1674  * Returns: 0 on success, -ENOBUFS when we run out of space
1675  */
1676
1677 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1678 {
1679         const struct gfs2_glock_operations *glops = gl->gl_ops;
1680         unsigned long long dtime;
1681         const struct gfs2_holder *gh;
1682         char gflags_buf[32];
1683         int error = 0;
1684
1685         dtime = jiffies - gl->gl_demote_time;
1686         dtime *= 1000000/HZ; /* demote time in uSec */
1687         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1688                 dtime = 0;
1689         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",
1690                   state2str(gl->gl_state),
1691                   gl->gl_name.ln_type,
1692                   (unsigned long long)gl->gl_name.ln_number,
1693                   gflags2str(gflags_buf, gl),
1694                   state2str(gl->gl_target),
1695                   state2str(gl->gl_demote_state), dtime,
1696                   atomic_read(&gl->gl_ail_count),
1697                   atomic_read(&gl->gl_revokes),
1698                   atomic_read(&gl->gl_ref), gl->gl_hold_time);
1699
1700         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1701                 error = dump_holder(seq, gh);
1702                 if (error)
1703                         goto out;
1704         }
1705         if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1706                 error = glops->go_dump(seq, gl);
1707 out:
1708         return error;
1709 }
1710
1711
1712
1713
1714 int __init gfs2_glock_init(void)
1715 {
1716         unsigned i;
1717         for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
1718                 INIT_HLIST_BL_HEAD(&gl_hash_table[i]);
1719         }
1720
1721         glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
1722                                           WQ_HIGHPRI | WQ_FREEZABLE, 0);
1723         if (IS_ERR(glock_workqueue))
1724                 return PTR_ERR(glock_workqueue);
1725         gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
1726                                                 WQ_MEM_RECLAIM | WQ_FREEZABLE,
1727                                                 0);
1728         if (IS_ERR(gfs2_delete_workqueue)) {
1729                 destroy_workqueue(glock_workqueue);
1730                 return PTR_ERR(gfs2_delete_workqueue);
1731         }
1732
1733         register_shrinker(&glock_shrinker);
1734
1735         return 0;
1736 }
1737
1738 void gfs2_glock_exit(void)
1739 {
1740         unregister_shrinker(&glock_shrinker);
1741         destroy_workqueue(glock_workqueue);
1742         destroy_workqueue(gfs2_delete_workqueue);
1743 }
1744
1745 static inline struct gfs2_glock *glock_hash_chain(unsigned hash)
1746 {
1747         return hlist_bl_entry(hlist_bl_first_rcu(&gl_hash_table[hash]),
1748                               struct gfs2_glock, gl_list);
1749 }
1750
1751 static inline struct gfs2_glock *glock_hash_next(struct gfs2_glock *gl)
1752 {
1753         return hlist_bl_entry(rcu_dereference(gl->gl_list.next),
1754                               struct gfs2_glock, gl_list);
1755 }
1756
1757 static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1758 {
1759         struct gfs2_glock *gl;
1760
1761         do {
1762                 gl = gi->gl;
1763                 if (gl) {
1764                         gi->gl = glock_hash_next(gl);
1765                 } else {
1766                         gi->gl = glock_hash_chain(gi->hash);
1767                 }
1768                 while (gi->gl == NULL) {
1769                         gi->hash++;
1770                         if (gi->hash >= GFS2_GL_HASH_SIZE) {
1771                                 rcu_read_unlock();
1772                                 return 1;
1773                         }
1774                         gi->gl = glock_hash_chain(gi->hash);
1775                 }
1776         /* Skip entries for other sb and dead entries */
1777         } while (gi->sdp != gi->gl->gl_sbd || atomic_read(&gi->gl->gl_ref) == 0);
1778
1779         return 0;
1780 }
1781
1782 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1783 {
1784         struct gfs2_glock_iter *gi = seq->private;
1785         loff_t n = *pos;
1786
1787         gi->hash = 0;
1788         rcu_read_lock();
1789
1790         do {
1791                 if (gfs2_glock_iter_next(gi))
1792                         return NULL;
1793         } while (n--);
1794
1795         return gi->gl;
1796 }
1797
1798 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1799                                  loff_t *pos)
1800 {
1801         struct gfs2_glock_iter *gi = seq->private;
1802
1803         (*pos)++;
1804
1805         if (gfs2_glock_iter_next(gi))
1806                 return NULL;
1807
1808         return gi->gl;
1809 }
1810
1811 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1812 {
1813         struct gfs2_glock_iter *gi = seq->private;
1814
1815         if (gi->gl)
1816                 rcu_read_unlock();
1817         gi->gl = NULL;
1818 }
1819
1820 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1821 {
1822         return dump_glock(seq, iter_ptr);
1823 }
1824
1825 static const struct seq_operations gfs2_glock_seq_ops = {
1826         .start = gfs2_glock_seq_start,
1827         .next  = gfs2_glock_seq_next,
1828         .stop  = gfs2_glock_seq_stop,
1829         .show  = gfs2_glock_seq_show,
1830 };
1831
1832 static int gfs2_debugfs_open(struct inode *inode, struct file *file)
1833 {
1834         int ret = seq_open_private(file, &gfs2_glock_seq_ops,
1835                                    sizeof(struct gfs2_glock_iter));
1836         if (ret == 0) {
1837                 struct seq_file *seq = file->private_data;
1838                 struct gfs2_glock_iter *gi = seq->private;
1839                 gi->sdp = inode->i_private;
1840         }
1841         return ret;
1842 }
1843
1844 static const struct file_operations gfs2_debug_fops = {
1845         .owner   = THIS_MODULE,
1846         .open    = gfs2_debugfs_open,
1847         .read    = seq_read,
1848         .llseek  = seq_lseek,
1849         .release = seq_release_private,
1850 };
1851
1852 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
1853 {
1854         sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
1855         if (!sdp->debugfs_dir)
1856                 return -ENOMEM;
1857         sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
1858                                                          S_IFREG | S_IRUGO,
1859                                                          sdp->debugfs_dir, sdp,
1860                                                          &gfs2_debug_fops);
1861         if (!sdp->debugfs_dentry_glocks)
1862                 return -ENOMEM;
1863
1864         return 0;
1865 }
1866
1867 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
1868 {
1869         if (sdp && sdp->debugfs_dir) {
1870                 if (sdp->debugfs_dentry_glocks) {
1871                         debugfs_remove(sdp->debugfs_dentry_glocks);
1872                         sdp->debugfs_dentry_glocks = NULL;
1873                 }
1874                 debugfs_remove(sdp->debugfs_dir);
1875                 sdp->debugfs_dir = NULL;
1876         }
1877 }
1878
1879 int gfs2_register_debugfs(void)
1880 {
1881         gfs2_root = debugfs_create_dir("gfs2", NULL);
1882         return gfs2_root ? 0 : -ENOMEM;
1883 }
1884
1885 void gfs2_unregister_debugfs(void)
1886 {
1887         debugfs_remove(gfs2_root);
1888         gfs2_root = NULL;
1889 }