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
  30 #include "gfs2.h"
  31 #include "incore.h"
  32 #include "glock.h"
  33 #include "glops.h"
  34 #include "inode.h"
  35 #include "lops.h"
  36 #include "meta_io.h"
  37 #include "quota.h"
  38 #include "super.h"
  39 #include "util.h"
  40 #include "bmap.h"
  41 #define CREATE_TRACE_POINTS
  42 #include "trace_gfs2.h"
  43
  44 struct gfs2_gl_hash_bucket {
  45         struct hlist_head hb_list;
  46 };
  47
  48 struct gfs2_glock_iter {
  49         int hash;                       /* hash bucket index         */
  50         struct gfs2_sbd *sdp;           /* incore superblock         */
  51         struct gfs2_glock *gl;          /* current glock struct      */
  52         char string[512];               /* scratch space             */
  53 };
  54
  55 typedef void (*glock_examiner) (struct gfs2_glock * gl);
  56
  57 static int gfs2_dump_lockstate(struct gfs2_sbd *sdp);
  58 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl);
  59 #define GLOCK_BUG_ON(gl,x) do { if (unlikely(x)) { __dump_glock(NULL, gl); BUG(); } } while(0)
  60 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
  61
  62 static struct dentry *gfs2_root;
  63 static struct workqueue_struct *glock_workqueue;
  64 struct workqueue_struct *gfs2_delete_workqueue;
  65 static LIST_HEAD(lru_list);
  66 static atomic_t lru_count = ATOMIC_INIT(0);
  67 static DEFINE_SPINLOCK(lru_lock);
  68
  69 #define GFS2_GL_HASH_SHIFT      15
  70 #define GFS2_GL_HASH_SIZE       (1 << GFS2_GL_HASH_SHIFT)
  71 #define GFS2_GL_HASH_MASK       (GFS2_GL_HASH_SIZE - 1)
  72
  73 static struct gfs2_gl_hash_bucket gl_hash_table[GFS2_GL_HASH_SIZE];
  74 static struct dentry *gfs2_root;
  75
  76 /*
  77  * Despite what you might think, the numbers below are not arbitrary :-)
  78  * They are taken from the ipv4 routing hash code, which is well tested
  79  * and thus should be nearly optimal. Later on we might tweek the numbers
  80  * but for now this should be fine.
  81  *
  82  * The reason for putting the locks in a separate array from the list heads
  83  * is that we can have fewer locks than list heads and save memory. We use
  84  * the same hash function for both, but with a different hash mask.
  85  */
  86 #if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK) || \
  87         defined(CONFIG_PROVE_LOCKING)
  88
  89 #ifdef CONFIG_LOCKDEP
  90 # define GL_HASH_LOCK_SZ        256
  91 #else
  92 # if NR_CPUS >= 32
  93 #  define GL_HASH_LOCK_SZ       4096
  94 # elif NR_CPUS >= 16
  95 #  define GL_HASH_LOCK_SZ       2048
  96 # elif NR_CPUS >= 8
  97 #  define GL_HASH_LOCK_SZ       1024
  98 # elif NR_CPUS >= 4
  99 #  define GL_HASH_LOCK_SZ       512
 100 # else
 101 #  define GL_HASH_LOCK_SZ       256
 102 # endif
 103 #endif
 104
 105 /* We never want more locks than chains */
 106 #if GFS2_GL_HASH_SIZE < GL_HASH_LOCK_SZ
 107 # undef GL_HASH_LOCK_SZ
 108 # define GL_HASH_LOCK_SZ GFS2_GL_HASH_SIZE
 109 #endif
 110
 111 static rwlock_t gl_hash_locks[GL_HASH_LOCK_SZ];
 112
 113 static inline rwlock_t *gl_lock_addr(unsigned int x)
 114 {
 115         return &gl_hash_locks[x & (GL_HASH_LOCK_SZ-1)];
 116 }
 117 #else /* not SMP, so no spinlocks required */
 118 static inline rwlock_t *gl_lock_addr(unsigned int x)
 119 {
 120         return NULL;
 121 }
 122 #endif
 123
 124 /**
 125  * gl_hash() - Turn glock number into hash bucket number
 126  * @lock: The glock number
 127  *
 128  * Returns: The number of the corresponding hash bucket
 129  */
 130
 131 static unsigned int gl_hash(const struct gfs2_sbd *sdp,
 132                             const struct lm_lockname *name)
 133 {
 134         unsigned int h;
 135
 136         h = jhash(&name->ln_number, sizeof(u64), 0);
 137         h = jhash(&name->ln_type, sizeof(unsigned int), h);
 138         h = jhash(&sdp, sizeof(struct gfs2_sbd *), h);
 139         h &= GFS2_GL_HASH_MASK;
 140
 141         return h;
 142 }
 143
 144 /**
 145  * glock_free() - Perform a few checks and then release struct gfs2_glock
 146  * @gl: The glock to release
 147  *
 148  * Also calls lock module to release its internal structure for this glock.
 149  *
 150  */
 151
 152 static void glock_free(struct gfs2_glock *gl)
 153 {
 154         struct gfs2_sbd *sdp = gl->gl_sbd;
 155         struct address_space *mapping = gfs2_glock2aspace(gl);
 156         struct kmem_cache *cachep = gfs2_glock_cachep;
 157
 158         GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
 159         trace_gfs2_glock_put(gl);
 160         if (mapping)
 161                 cachep = gfs2_glock_aspace_cachep;
 162         sdp->sd_lockstruct.ls_ops->lm_put_lock(cachep, gl);
 163 }
 164
 165 /**
 166  * gfs2_glock_hold() - increment reference count on glock
 167  * @gl: The glock to hold
 168  *
 169  */
 170
 171 void gfs2_glock_hold(struct gfs2_glock *gl)
 172 {
 173         GLOCK_BUG_ON(gl, atomic_read(&gl->gl_ref) == 0);
 174         atomic_inc(&gl->gl_ref);
 175 }
 176
 177 /**
 178  * demote_ok - Check to see if it's ok to unlock a glock
 179  * @gl: the glock
 180  *
 181  * Returns: 1 if it's ok
 182  */
 183
 184 static int demote_ok(const struct gfs2_glock *gl)
 185 {
 186         const struct gfs2_glock_operations *glops = gl->gl_ops;
 187
 188         if (gl->gl_state == LM_ST_UNLOCKED)
 189                 return 0;
 190         if (!list_empty(&gl->gl_holders))
 191                 return 0;
 192         if (glops->go_demote_ok)
 193                 return glops->go_demote_ok(gl);
 194         return 1;
 195 }
 196
 197 /**
 198  * gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
 199  * @gl: the glock
 200  *
 201  */
 202
 203 static void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
 204 {
 205         int may_reclaim;
 206         may_reclaim = (demote_ok(gl) &&
 207                        (atomic_read(&gl->gl_ref) == 1 ||
 208                         (gl->gl_name.ln_type == LM_TYPE_INODE &&
 209                          atomic_read(&gl->gl_ref) <= 2)));
 210         spin_lock(&lru_lock);
 211         if (list_empty(&gl->gl_lru) && may_reclaim) {
 212                 list_add_tail(&gl->gl_lru, &lru_list);
 213                 atomic_inc(&lru_count);
 214         }
 215         spin_unlock(&lru_lock);
 216 }
 217
 218 /**
 219  * gfs2_glock_put_nolock() - Decrement reference count on glock
 220  * @gl: The glock to put
 221  *
 222  * This function should only be used if the caller has its own reference
 223  * to the glock, in addition to the one it is dropping.
 224  */
 225
 226 void gfs2_glock_put_nolock(struct gfs2_glock *gl)
 227 {
 228         if (atomic_dec_and_test(&gl->gl_ref))
 229                 GLOCK_BUG_ON(gl, 1);
 230         gfs2_glock_schedule_for_reclaim(gl);
 231 }
 232
 233 /**
 234  * gfs2_glock_put() - Decrement reference count on glock
 235  * @gl: The glock to put
 236  *
 237  */
 238
 239 int gfs2_glock_put(struct gfs2_glock *gl)
 240 {
 241         int rv = 0;
 242
 243         write_lock(gl_lock_addr(gl->gl_hash));
 244         if (atomic_dec_and_lock(&gl->gl_ref, &lru_lock)) {
 245                 hlist_del(&gl->gl_list);
 246                 if (!list_empty(&gl->gl_lru)) {
 247                         list_del_init(&gl->gl_lru);
 248                         atomic_dec(&lru_count);
 249                 }
 250                 spin_unlock(&lru_lock);
 251                 write_unlock(gl_lock_addr(gl->gl_hash));
 252                 GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
 253                 glock_free(gl);
 254                 rv = 1;
 255                 goto out;
 256         }
 257         spin_lock(&gl->gl_spin);
 258         gfs2_glock_schedule_for_reclaim(gl);
 259         spin_unlock(&gl->gl_spin);
 260         write_unlock(gl_lock_addr(gl->gl_hash));
 261 out:
 262         return rv;
 263 }
 264
 265 /**
 266  * search_bucket() - Find struct gfs2_glock by lock number
 267  * @bucket: the bucket to search
 268  * @name: The lock name
 269  *
 270  * Returns: NULL, or the struct gfs2_glock with the requested number
 271  */
 272
 273 static struct gfs2_glock *search_bucket(unsigned int hash,
 274                                         const struct gfs2_sbd *sdp,
 275                                         const struct lm_lockname *name)
 276 {
 277         struct gfs2_glock *gl;
 278         struct hlist_node *h;
 279
 280         hlist_for_each_entry(gl, h, &gl_hash_table[hash].hb_list, gl_list) {
 281                 if (!lm_name_equal(&gl->gl_name, name))
 282                         continue;
 283                 if (gl->gl_sbd != sdp)
 284                         continue;
 285
 286                 atomic_inc(&gl->gl_ref);
 287
 288                 return gl;
 289         }
 290
 291         return NULL;
 292 }
 293
 294 /**
 295  * may_grant - check if its ok to grant a new lock
 296  * @gl: The glock
 297  * @gh: The lock request which we wish to grant
 298  *
 299  * Returns: true if its ok to grant the lock
 300  */
 301
 302 static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
 303 {
 304         const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
 305         if ((gh->gh_state == LM_ST_EXCLUSIVE ||
 306              gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
 307                 return 0;
 308         if (gl->gl_state == gh->gh_state)
 309                 return 1;
 310         if (gh->gh_flags & GL_EXACT)
 311                 return 0;
 312         if (gl->gl_state == LM_ST_EXCLUSIVE) {
 313                 if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
 314                         return 1;
 315                 if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
 316                         return 1;
 317         }
 318         if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
 319                 return 1;
 320         return 0;
 321 }
 322
 323 static void gfs2_holder_wake(struct gfs2_holder *gh)
 324 {
 325         clear_bit(HIF_WAIT, &gh->gh_iflags);
 326         smp_mb__after_clear_bit();
 327         wake_up_bit(&gh->gh_iflags, HIF_WAIT);
 328 }
 329
 330 /**
 331  * do_error - Something unexpected has happened during a lock request
 332  *
 333  */
 334
 335 static inline void do_error(struct gfs2_glock *gl, const int ret)
 336 {
 337         struct gfs2_holder *gh, *tmp;
 338
 339         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 340                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 341                         continue;
 342                 if (ret & LM_OUT_ERROR)
 343                         gh->gh_error = -EIO;
 344                 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
 345                         gh->gh_error = GLR_TRYFAILED;
 346                 else
 347                         continue;
 348                 list_del_init(&gh->gh_list);
 349                 trace_gfs2_glock_queue(gh, 0);
 350                 gfs2_holder_wake(gh);
 351         }
 352 }
 353
 354 /**
 355  * do_promote - promote as many requests as possible on the current queue
 356  * @gl: The glock
 357  *
 358  * Returns: 1 if there is a blocked holder at the head of the list, or 2
 359  *          if a type specific operation is underway.
 360  */
 361
 362 static int do_promote(struct gfs2_glock *gl)
 363 __releases(&gl->gl_spin)
 364 __acquires(&gl->gl_spin)
 365 {
 366         const struct gfs2_glock_operations *glops = gl->gl_ops;
 367         struct gfs2_holder *gh, *tmp;
 368         int ret;
 369
 370 restart:
 371         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 372                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 373                         continue;
 374                 if (may_grant(gl, gh)) {
 375                         if (gh->gh_list.prev == &gl->gl_holders &&
 376                             glops->go_lock) {
 377                                 spin_unlock(&gl->gl_spin);
 378                                 /* FIXME: eliminate this eventually */
 379                                 ret = glops->go_lock(gh);
 380                                 spin_lock(&gl->gl_spin);
 381                                 if (ret) {
 382                                         if (ret == 1)
 383                                                 return 2;
 384                                         gh->gh_error = ret;
 385                                         list_del_init(&gh->gh_list);
 386                                         trace_gfs2_glock_queue(gh, 0);
 387                                         gfs2_holder_wake(gh);
 388                                         goto restart;
 389                                 }
 390                                 set_bit(HIF_HOLDER, &gh->gh_iflags);
 391                                 trace_gfs2_promote(gh, 1);
 392                                 gfs2_holder_wake(gh);
 393                                 goto restart;
 394                         }
 395                         set_bit(HIF_HOLDER, &gh->gh_iflags);
 396                         trace_gfs2_promote(gh, 0);
 397                         gfs2_holder_wake(gh);
 398                         continue;
 399                 }
 400                 if (gh->gh_list.prev == &gl->gl_holders)
 401                         return 1;
 402                 do_error(gl, 0);
 403                 break;
 404         }
 405         return 0;
 406 }
 407
 408 /**
 409  * find_first_waiter - find the first gh that's waiting for the glock
 410  * @gl: the glock
 411  */
 412
 413 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
 414 {
 415         struct gfs2_holder *gh;
 416
 417         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
 418                 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
 419                         return gh;
 420         }
 421         return NULL;
 422 }
 423
 424 /**
 425  * state_change - record that the glock is now in a different state
 426  * @gl: the glock
 427  * @new_state the new state
 428  *
 429  */
 430
 431 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 432 {
 433         int held1, held2;
 434
 435         held1 = (gl->gl_state != LM_ST_UNLOCKED);
 436         held2 = (new_state != LM_ST_UNLOCKED);
 437
 438         if (held1 != held2) {
 439                 if (held2)
 440                         gfs2_glock_hold(gl);
 441                 else
 442                         gfs2_glock_put_nolock(gl);
 443         }
 444
 445         gl->gl_state = new_state;
 446         gl->gl_tchange = jiffies;
 447 }
 448
 449 static void gfs2_demote_wake(struct gfs2_glock *gl)
 450 {
 451         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 452         clear_bit(GLF_DEMOTE, &gl->gl_flags);
 453         smp_mb__after_clear_bit();
 454         wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
 455 }
 456
 457 /**
 458  * finish_xmote - The DLM has replied to one of our lock requests
 459  * @gl: The glock
 460  * @ret: The status from the DLM
 461  *
 462  */
 463
 464 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
 465 {
 466         const struct gfs2_glock_operations *glops = gl->gl_ops;
 467         struct gfs2_holder *gh;
 468         unsigned state = ret & LM_OUT_ST_MASK;
 469         int rv;
 470
 471         spin_lock(&gl->gl_spin);
 472         trace_gfs2_glock_state_change(gl, state);
 473         state_change(gl, state);
 474         gh = find_first_waiter(gl);
 475
 476         /* Demote to UN request arrived during demote to SH or DF */
 477         if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
 478             state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
 479                 gl->gl_target = LM_ST_UNLOCKED;
 480
 481         /* Check for state != intended state */
 482         if (unlikely(state != gl->gl_target)) {
 483                 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
 484                         /* move to back of queue and try next entry */
 485                         if (ret & LM_OUT_CANCELED) {
 486                                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
 487                                         list_move_tail(&gh->gh_list, &gl->gl_holders);
 488                                 gh = find_first_waiter(gl);
 489                                 gl->gl_target = gh->gh_state;
 490                                 goto retry;
 491                         }
 492                         /* Some error or failed "try lock" - report it */
 493                         if ((ret & LM_OUT_ERROR) ||
 494                             (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 495                                 gl->gl_target = gl->gl_state;
 496                                 do_error(gl, ret);
 497                                 goto out;
 498                         }
 499                 }
 500                 switch(state) {
 501                 /* Unlocked due to conversion deadlock, try again */
 502                 case LM_ST_UNLOCKED:
 503 retry:
 504                         do_xmote(gl, gh, gl->gl_target);
 505                         break;
 506                 /* Conversion fails, unlock and try again */
 507                 case LM_ST_SHARED:
 508                 case LM_ST_DEFERRED:
 509                         do_xmote(gl, gh, LM_ST_UNLOCKED);
 510                         break;
 511                 default: /* Everything else */
 512                         printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
 513                         GLOCK_BUG_ON(gl, 1);
 514                 }
 515                 spin_unlock(&gl->gl_spin);
 516                 return;
 517         }
 518
 519         /* Fast path - we got what we asked for */
 520         if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
 521                 gfs2_demote_wake(gl);
 522         if (state != LM_ST_UNLOCKED) {
 523                 if (glops->go_xmote_bh) {
 524                         spin_unlock(&gl->gl_spin);
 525                         rv = glops->go_xmote_bh(gl, gh);
 526                         spin_lock(&gl->gl_spin);
 527                         if (rv) {
 528                                 do_error(gl, rv);
 529                                 goto out;
 530                         }
 531                 }
 532                 rv = do_promote(gl);
 533                 if (rv == 2)
 534                         goto out_locked;
 535         }
 536 out:
 537         clear_bit(GLF_LOCK, &gl->gl_flags);
 538 out_locked:
 539         spin_unlock(&gl->gl_spin);
 540 }
 541
 542 static unsigned int gfs2_lm_lock(struct gfs2_sbd *sdp, void *lock,
 543                                  unsigned int req_state,
 544                                  unsigned int flags)
 545 {
 546         int ret = LM_OUT_ERROR;
 547
 548         if (!sdp->sd_lockstruct.ls_ops->lm_lock)
 549                 return req_state == LM_ST_UNLOCKED ? 0 : req_state;
 550
 551         if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 552                 ret = sdp->sd_lockstruct.ls_ops->lm_lock(lock,
 553                                                          req_state, flags);
 554         return ret;
 555 }
 556
 557 /**
 558  * do_xmote - Calls the DLM to change the state of a lock
 559  * @gl: The lock state
 560  * @gh: The holder (only for promotes)
 561  * @target: The target lock state
 562  *
 563  */
 564
 565 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
 566 __releases(&gl->gl_spin)
 567 __acquires(&gl->gl_spin)
 568 {
 569         const struct gfs2_glock_operations *glops = gl->gl_ops;
 570         struct gfs2_sbd *sdp = gl->gl_sbd;
 571         unsigned int lck_flags = gh ? gh->gh_flags : 0;
 572         int ret;
 573
 574         lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
 575                       LM_FLAG_PRIORITY);
 576         BUG_ON(gl->gl_state == target);
 577         BUG_ON(gl->gl_state == gl->gl_target);
 578         if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
 579             glops->go_inval) {
 580                 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 581                 do_error(gl, 0); /* Fail queued try locks */
 582         }
 583         spin_unlock(&gl->gl_spin);
 584         if (glops->go_xmote_th)
 585                 glops->go_xmote_th(gl);
 586         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 587                 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
 588         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 589
 590         gfs2_glock_hold(gl);
 591         if (target != LM_ST_UNLOCKED && (gl->gl_state == LM_ST_SHARED ||
 592             gl->gl_state == LM_ST_DEFERRED) &&
 593             !(lck_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 594                 lck_flags |= LM_FLAG_TRY_1CB;
 595         ret = gfs2_lm_lock(sdp, gl, target, lck_flags);
 596
 597         if (!(ret & LM_OUT_ASYNC)) {
 598                 finish_xmote(gl, ret);
 599                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 600                         gfs2_glock_put(gl);
 601         } else {
 602                 GLOCK_BUG_ON(gl, ret != LM_OUT_ASYNC);
 603         }
 604         spin_lock(&gl->gl_spin);
 605 }
 606
 607 /**
 608  * find_first_holder - find the first "holder" gh
 609  * @gl: the glock
 610  */
 611
 612 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
 613 {
 614         struct gfs2_holder *gh;
 615
 616         if (!list_empty(&gl->gl_holders)) {
 617                 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 618                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 619                         return gh;
 620         }
 621         return NULL;
 622 }
 623
 624 /**
 625  * run_queue - do all outstanding tasks related to a glock
 626  * @gl: The glock in question
 627  * @nonblock: True if we must not block in run_queue
 628  *
 629  */
 630
 631 static void run_queue(struct gfs2_glock *gl, const int nonblock)
 632 __releases(&gl->gl_spin)
 633 __acquires(&gl->gl_spin)
 634 {
 635         struct gfs2_holder *gh = NULL;
 636         int ret;
 637
 638         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 639                 return;
 640
 641         GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
 642
 643         if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
 644             gl->gl_demote_state != gl->gl_state) {
 645                 if (find_first_holder(gl))
 646                         goto out_unlock;
 647                 if (nonblock)
 648                         goto out_sched;
 649                 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
 650                 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
 651                 gl->gl_target = gl->gl_demote_state;
 652         } else {
 653                 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
 654                         gfs2_demote_wake(gl);
 655                 ret = do_promote(gl);
 656                 if (ret == 0)
 657                         goto out_unlock;
 658                 if (ret == 2)
 659                         goto out;
 660                 gh = find_first_waiter(gl);
 661                 gl->gl_target = gh->gh_state;
 662                 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 663                         do_error(gl, 0); /* Fail queued try locks */
 664         }
 665         do_xmote(gl, gh, gl->gl_target);
 666 out:
 667         return;
 668
 669 out_sched:
 670         clear_bit(GLF_LOCK, &gl->gl_flags);
 671         smp_mb__after_clear_bit();
 672         gfs2_glock_hold(gl);
 673         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 674                 gfs2_glock_put_nolock(gl);
 675         return;
 676
 677 out_unlock:
 678         clear_bit(GLF_LOCK, &gl->gl_flags);
 679         smp_mb__after_clear_bit();
 680         return;
 681 }
 682
 683 static void delete_work_func(struct work_struct *work)
 684 {
 685         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
 686         struct gfs2_sbd *sdp = gl->gl_sbd;
 687         struct gfs2_inode *ip = NULL;
 688         struct inode *inode;
 689         u64 no_addr = 0;
 690
 691         spin_lock(&gl->gl_spin);
 692         ip = (struct gfs2_inode *)gl->gl_object;
 693         if (ip)
 694                 no_addr = ip->i_no_addr;
 695         spin_unlock(&gl->gl_spin);
 696         if (ip) {
 697                 inode = gfs2_ilookup(sdp->sd_vfs, no_addr);
 698                 if (inode) {
 699                         d_prune_aliases(inode);
 700                         iput(inode);
 701                 }
 702         }
 703         gfs2_glock_put(gl);
 704 }
 705
 706 static void glock_work_func(struct work_struct *work)
 707 {
 708         unsigned long delay = 0;
 709         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
 710         int drop_ref = 0;
 711
 712         if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
 713                 finish_xmote(gl, gl->gl_reply);
 714                 drop_ref = 1;
 715         }
 716         spin_lock(&gl->gl_spin);
 717         if (test_and_clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
 718             gl->gl_state != LM_ST_UNLOCKED &&
 719             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
 720                 unsigned long holdtime, now = jiffies;
 721                 holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
 722                 if (time_before(now, holdtime))
 723                         delay = holdtime - now;
 724                 set_bit(delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE, &gl->gl_flags);
 725         }
 726         run_queue(gl, 0);
 727         spin_unlock(&gl->gl_spin);
 728         if (!delay ||
 729             queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
 730                 gfs2_glock_put(gl);
 731         if (drop_ref)
 732                 gfs2_glock_put(gl);
 733 }
 734
 735 /**
 736  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
 737  * @sdp: The GFS2 superblock
 738  * @number: the lock number
 739  * @glops: The glock_operations to use
 740  * @create: If 0, don't create the glock if it doesn't exist
 741  * @glp: the glock is returned here
 742  *
 743  * This does not lock a glock, just finds/creates structures for one.
 744  *
 745  * Returns: errno
 746  */
 747
 748 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 749                    const struct gfs2_glock_operations *glops, int create,
 750                    struct gfs2_glock **glp)
 751 {
 752         struct super_block *s = sdp->sd_vfs;
 753         struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
 754         struct gfs2_glock *gl, *tmp;
 755         unsigned int hash = gl_hash(sdp, &name);
 756         struct address_space *mapping;
 757
 758         read_lock(gl_lock_addr(hash));
 759         gl = search_bucket(hash, sdp, &name);
 760         read_unlock(gl_lock_addr(hash));
 761
 762         *glp = gl;
 763         if (gl)
 764                 return 0;
 765         if (!create)
 766                 return -ENOENT;
 767
 768         if (glops->go_flags & GLOF_ASPACE)
 769                 gl = kmem_cache_alloc(gfs2_glock_aspace_cachep, GFP_KERNEL);
 770         else
 771                 gl = kmem_cache_alloc(gfs2_glock_cachep, GFP_KERNEL);
 772         if (!gl)
 773                 return -ENOMEM;
 774
 775         atomic_inc(&sdp->sd_glock_disposal);
 776         gl->gl_flags = 0;
 777         gl->gl_name = name;
 778         atomic_set(&gl->gl_ref, 1);
 779         gl->gl_state = LM_ST_UNLOCKED;
 780         gl->gl_target = LM_ST_UNLOCKED;
 781         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 782         gl->gl_hash = hash;
 783         gl->gl_ops = glops;
 784         snprintf(gl->gl_strname, GDLM_STRNAME_BYTES, "%8x%16llx", name.ln_type, (unsigned long long)number);
 785         memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
 786         gl->gl_lksb.sb_lvbptr = gl->gl_lvb;
 787         gl->gl_tchange = jiffies;
 788         gl->gl_object = NULL;
 789         gl->gl_sbd = sdp;
 790         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
 791         INIT_WORK(&gl->gl_delete, delete_work_func);
 792
 793         mapping = gfs2_glock2aspace(gl);
 794         if (mapping) {
 795                 mapping->a_ops = &gfs2_meta_aops;
 796                 mapping->host = s->s_bdev->bd_inode;
 797                 mapping->flags = 0;
 798                 mapping_set_gfp_mask(mapping, GFP_NOFS);
 799                 mapping->assoc_mapping = NULL;
 800                 mapping->backing_dev_info = s->s_bdi;
 801                 mapping->writeback_index = 0;
 802         }
 803
 804         write_lock(gl_lock_addr(hash));
 805         tmp = search_bucket(hash, sdp, &name);
 806         if (tmp) {
 807                 write_unlock(gl_lock_addr(hash));
 808                 glock_free(gl);
 809                 gl = tmp;
 810         } else {
 811                 hlist_add_head(&gl->gl_list, &gl_hash_table[hash].hb_list);
 812                 write_unlock(gl_lock_addr(hash));
 813         }
 814
 815         *glp = gl;
 816
 817         return 0;
 818 }
 819
 820 /**
 821  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
 822  * @gl: the glock
 823  * @state: the state we're requesting
 824  * @flags: the modifier flags
 825  * @gh: the holder structure
 826  *
 827  */
 828
 829 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
 830                       struct gfs2_holder *gh)
 831 {
 832         INIT_LIST_HEAD(&gh->gh_list);
 833         gh->gh_gl = gl;
 834         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 835         gh->gh_owner_pid = get_pid(task_pid(current));
 836         gh->gh_state = state;
 837         gh->gh_flags = flags;
 838         gh->gh_error = 0;
 839         gh->gh_iflags = 0;
 840         gfs2_glock_hold(gl);
 841 }
 842
 843 /**
 844  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
 845  * @state: the state we're requesting
 846  * @flags: the modifier flags
 847  * @gh: the holder structure
 848  *
 849  * Don't mess with the glock.
 850  *
 851  */
 852
 853 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
 854 {
 855         gh->gh_state = state;
 856         gh->gh_flags = flags;
 857         gh->gh_iflags = 0;
 858         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 859         if (gh->gh_owner_pid)
 860                 put_pid(gh->gh_owner_pid);
 861         gh->gh_owner_pid = get_pid(task_pid(current));
 862 }
 863
 864 /**
 865  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 866  * @gh: the holder structure
 867  *
 868  */
 869
 870 void gfs2_holder_uninit(struct gfs2_holder *gh)
 871 {
 872         put_pid(gh->gh_owner_pid);
 873         gfs2_glock_put(gh->gh_gl);
 874         gh->gh_gl = NULL;
 875         gh->gh_ip = 0;
 876 }
 877
 878 /**
 879  * gfs2_glock_holder_wait
 880  * @word: unused
 881  *
 882  * This function and gfs2_glock_demote_wait both show up in the WCHAN
 883  * field. Thus I've separated these otherwise identical functions in
 884  * order to be more informative to the user.
 885  */
 886
 887 static int gfs2_glock_holder_wait(void *word)
 888 {
 889         schedule();
 890         return 0;
 891 }
 892
 893 static int gfs2_glock_demote_wait(void *word)
 894 {
 895         schedule();
 896         return 0;
 897 }
 898
 899 static void wait_on_holder(struct gfs2_holder *gh)
 900 {
 901         might_sleep();
 902         wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
 903 }
 904
 905 static void wait_on_demote(struct gfs2_glock *gl)
 906 {
 907         might_sleep();
 908         wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
 909 }
 910
 911 /**
 912  * handle_callback - process a demote request
 913  * @gl: the glock
 914  * @state: the state the caller wants us to change to
 915  *
 916  * There are only two requests that we are going to see in actual
 917  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
 918  */
 919
 920 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
 921                             unsigned long delay)
 922 {
 923         int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
 924
 925         set_bit(bit, &gl->gl_flags);
 926         if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
 927                 gl->gl_demote_state = state;
 928                 gl->gl_demote_time = jiffies;
 929         } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
 930                         gl->gl_demote_state != state) {
 931                 gl->gl_demote_state = LM_ST_UNLOCKED;
 932         }
 933         if (gl->gl_ops->go_callback)
 934                 gl->gl_ops->go_callback(gl);
 935         trace_gfs2_demote_rq(gl);
 936 }
 937
 938 /**
 939  * gfs2_glock_wait - wait on a glock acquisition
 940  * @gh: the glock holder
 941  *
 942  * Returns: 0 on success
 943  */
 944
 945 int gfs2_glock_wait(struct gfs2_holder *gh)
 946 {
 947         wait_on_holder(gh);
 948         return gh->gh_error;
 949 }
 950
 951 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
 952 {
 953         va_list args;
 954
 955         va_start(args, fmt);
 956         if (seq) {
 957                 struct gfs2_glock_iter *gi = seq->private;
 958                 vsprintf(gi->string, fmt, args);
 959                 seq_printf(seq, gi->string);
 960         } else {
 961                 printk(KERN_ERR " ");
 962                 vprintk(fmt, args);
 963         }
 964         va_end(args);
 965 }
 966
 967 /**
 968  * add_to_queue - Add a holder to the wait queue (but look for recursion)
 969  * @gh: the holder structure to add
 970  *
 971  * Eventually we should move the recursive locking trap to a
 972  * debugging option or something like that. This is the fast
 973  * path and needs to have the minimum number of distractions.
 974  *
 975  */
 976
 977 static inline void add_to_queue(struct gfs2_holder *gh)
 978 __releases(&gl->gl_spin)
 979 __acquires(&gl->gl_spin)
 980 {
 981         struct gfs2_glock *gl = gh->gh_gl;
 982         struct gfs2_sbd *sdp = gl->gl_sbd;
 983         struct list_head *insert_pt = NULL;
 984         struct gfs2_holder *gh2;
 985         int try_lock = 0;
 986
 987         BUG_ON(gh->gh_owner_pid == NULL);
 988         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
 989                 BUG();
 990
 991         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
 992                 if (test_bit(GLF_LOCK, &gl->gl_flags))
 993                         try_lock = 1;
 994                 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 995                         goto fail;
 996         }
 997
 998         list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
 999                 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
1000                     (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
1001                         goto trap_recursive;
1002                 if (try_lock &&
1003                     !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
1004                     !may_grant(gl, gh)) {
1005 fail:
1006                         gh->gh_error = GLR_TRYFAILED;
1007                         gfs2_holder_wake(gh);
1008                         return;
1009                 }
1010                 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
1011                         continue;
1012                 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
1013                         insert_pt = &gh2->gh_list;
1014         }
1015         if (likely(insert_pt == NULL)) {
1016                 list_add_tail(&gh->gh_list, &gl->gl_holders);
1017                 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
1018                         goto do_cancel;
1019                 return;
1020         }
1021         trace_gfs2_glock_queue(gh, 1);
1022         list_add_tail(&gh->gh_list, insert_pt);
1023 do_cancel:
1024         gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
1025         if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
1026                 spin_unlock(&gl->gl_spin);
1027                 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
1028                         sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
1029                 spin_lock(&gl->gl_spin);
1030         }
1031         return;
1032
1033 trap_recursive:
1034         print_symbol(KERN_ERR "original: %s\n", gh2->gh_ip);
1035         printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
1036         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1037                gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
1038         print_symbol(KERN_ERR "new: %s\n", gh->gh_ip);
1039         printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
1040         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1041                gh->gh_gl->gl_name.ln_type, gh->gh_state);
1042         __dump_glock(NULL, gl);
1043         BUG();
1044 }
1045
1046 /**
1047  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1048  * @gh: the holder structure
1049  *
1050  * if (gh->gh_flags & GL_ASYNC), this never returns an error
1051  *
1052  * Returns: 0, GLR_TRYFAILED, or errno on failure
1053  */
1054
1055 int gfs2_glock_nq(struct gfs2_holder *gh)
1056 {
1057         struct gfs2_glock *gl = gh->gh_gl;
1058         struct gfs2_sbd *sdp = gl->gl_sbd;
1059         int error = 0;
1060
1061         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
1062                 return -EIO;
1063
1064         spin_lock(&gl->gl_spin);
1065         add_to_queue(gh);
1066         if ((LM_FLAG_NOEXP & gh->gh_flags) &&
1067             test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1068                 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1069         run_queue(gl, 1);
1070         spin_unlock(&gl->gl_spin);
1071
1072         if (!(gh->gh_flags & GL_ASYNC))
1073                 error = gfs2_glock_wait(gh);
1074
1075         return error;
1076 }
1077
1078 /**
1079  * gfs2_glock_poll - poll to see if an async request has been completed
1080  * @gh: the holder
1081  *
1082  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1083  */
1084
1085 int gfs2_glock_poll(struct gfs2_holder *gh)
1086 {
1087         return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1088 }
1089
1090 /**
1091  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1092  * @gh: the glock holder
1093  *
1094  */
1095
1096 void gfs2_glock_dq(struct gfs2_holder *gh)
1097 {
1098         struct gfs2_glock *gl = gh->gh_gl;
1099         const struct gfs2_glock_operations *glops = gl->gl_ops;
1100         unsigned delay = 0;
1101         int fast_path = 0;
1102
1103         spin_lock(&gl->gl_spin);
1104         if (gh->gh_flags & GL_NOCACHE)
1105                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1106
1107         list_del_init(&gh->gh_list);
1108         if (find_first_holder(gl) == NULL) {
1109                 if (glops->go_unlock) {
1110                         GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1111                         spin_unlock(&gl->gl_spin);
1112                         glops->go_unlock(gh);
1113                         spin_lock(&gl->gl_spin);
1114                         clear_bit(GLF_LOCK, &gl->gl_flags);
1115                 }
1116                 if (list_empty(&gl->gl_holders) &&
1117                     !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1118                     !test_bit(GLF_DEMOTE, &gl->gl_flags))
1119                         fast_path = 1;
1120         }
1121         trace_gfs2_glock_queue(gh, 0);
1122         spin_unlock(&gl->gl_spin);
1123         if (likely(fast_path))
1124                 return;
1125
1126         gfs2_glock_hold(gl);
1127         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1128             !test_bit(GLF_DEMOTE, &gl->gl_flags))
1129                 delay = gl->gl_ops->go_min_hold_time;
1130         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1131                 gfs2_glock_put(gl);
1132 }
1133
1134 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1135 {
1136         struct gfs2_glock *gl = gh->gh_gl;
1137         gfs2_glock_dq(gh);
1138         wait_on_demote(gl);
1139 }
1140
1141 /**
1142  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1143  * @gh: the holder structure
1144  *
1145  */
1146
1147 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1148 {
1149         gfs2_glock_dq(gh);
1150         gfs2_holder_uninit(gh);
1151 }
1152
1153 /**
1154  * gfs2_glock_nq_num - acquire a glock based on lock number
1155  * @sdp: the filesystem
1156  * @number: the lock number
1157  * @glops: the glock operations for the type of glock
1158  * @state: the state to acquire the glock in
1159  * @flags: modifier flags for the aquisition
1160  * @gh: the struct gfs2_holder
1161  *
1162  * Returns: errno
1163  */
1164
1165 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1166                       const struct gfs2_glock_operations *glops,
1167                       unsigned int state, int flags, struct gfs2_holder *gh)
1168 {
1169         struct gfs2_glock *gl;
1170         int error;
1171
1172         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1173         if (!error) {
1174                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1175                 gfs2_glock_put(gl);
1176         }
1177
1178         return error;
1179 }
1180
1181 /**
1182  * glock_compare - Compare two struct gfs2_glock structures for sorting
1183  * @arg_a: the first structure
1184  * @arg_b: the second structure
1185  *
1186  */
1187
1188 static int glock_compare(const void *arg_a, const void *arg_b)
1189 {
1190         const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1191         const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1192         const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1193         const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1194
1195         if (a->ln_number > b->ln_number)
1196                 return 1;
1197         if (a->ln_number < b->ln_number)
1198                 return -1;
1199         BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1200         return 0;
1201 }
1202
1203 /**
1204  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1205  * @num_gh: the number of structures
1206  * @ghs: an array of struct gfs2_holder structures
1207  *
1208  * Returns: 0 on success (all glocks acquired),
1209  *          errno on failure (no glocks acquired)
1210  */
1211
1212 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1213                      struct gfs2_holder **p)
1214 {
1215         unsigned int x;
1216         int error = 0;
1217
1218         for (x = 0; x < num_gh; x++)
1219                 p[x] = &ghs[x];
1220
1221         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1222
1223         for (x = 0; x < num_gh; x++) {
1224                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1225
1226                 error = gfs2_glock_nq(p[x]);
1227                 if (error) {
1228                         while (x--)
1229                                 gfs2_glock_dq(p[x]);
1230                         break;
1231                 }
1232         }
1233
1234         return error;
1235 }
1236
1237 /**
1238  * gfs2_glock_nq_m - acquire multiple glocks
1239  * @num_gh: the number of structures
1240  * @ghs: an array of struct gfs2_holder structures
1241  *
1242  *
1243  * Returns: 0 on success (all glocks acquired),
1244  *          errno on failure (no glocks acquired)
1245  */
1246
1247 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1248 {
1249         struct gfs2_holder *tmp[4];
1250         struct gfs2_holder **pph = tmp;
1251         int error = 0;
1252
1253         switch(num_gh) {
1254         case 0:
1255                 return 0;
1256         case 1:
1257                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1258                 return gfs2_glock_nq(ghs);
1259         default:
1260                 if (num_gh <= 4)
1261                         break;
1262                 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1263                 if (!pph)
1264                         return -ENOMEM;
1265         }
1266
1267         error = nq_m_sync(num_gh, ghs, pph);
1268
1269         if (pph != tmp)
1270                 kfree(pph);
1271
1272         return error;
1273 }
1274
1275 /**
1276  * gfs2_glock_dq_m - release multiple glocks
1277  * @num_gh: the number of structures
1278  * @ghs: an array of struct gfs2_holder structures
1279  *
1280  */
1281
1282 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1283 {
1284         unsigned int x;
1285
1286         for (x = 0; x < num_gh; x++)
1287                 gfs2_glock_dq(&ghs[x]);
1288 }
1289
1290 /**
1291  * gfs2_glock_dq_uninit_m - release multiple glocks
1292  * @num_gh: the number of structures
1293  * @ghs: an array of struct gfs2_holder structures
1294  *
1295  */
1296
1297 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1298 {
1299         unsigned int x;
1300
1301         for (x = 0; x < num_gh; x++)
1302                 gfs2_glock_dq_uninit(&ghs[x]);
1303 }
1304
1305 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1306 {
1307         unsigned long delay = 0;
1308         unsigned long holdtime;
1309         unsigned long now = jiffies;
1310
1311         gfs2_glock_hold(gl);
1312         holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
1313         if (time_before(now, holdtime))
1314                 delay = holdtime - now;
1315         if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1316                 delay = gl->gl_ops->go_min_hold_time;
1317
1318         spin_lock(&gl->gl_spin);
1319         handle_callback(gl, state, delay);
1320         spin_unlock(&gl->gl_spin);
1321         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1322                 gfs2_glock_put(gl);
1323 }
1324
1325 /**
1326  * gfs2_should_freeze - Figure out if glock should be frozen
1327  * @gl: The glock in question
1328  *
1329  * Glocks are not frozen if (a) the result of the dlm operation is
1330  * an error, (b) the locking operation was an unlock operation or
1331  * (c) if there is a "noexp" flagged request anywhere in the queue
1332  *
1333  * Returns: 1 if freezing should occur, 0 otherwise
1334  */
1335
1336 static int gfs2_should_freeze(const struct gfs2_glock *gl)
1337 {
1338         const struct gfs2_holder *gh;
1339
1340         if (gl->gl_reply & ~LM_OUT_ST_MASK)
1341                 return 0;
1342         if (gl->gl_target == LM_ST_UNLOCKED)
1343                 return 0;
1344
1345         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1346                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1347                         continue;
1348                 if (LM_FLAG_NOEXP & gh->gh_flags)
1349                         return 0;
1350         }
1351
1352         return 1;
1353 }
1354
1355 /**
1356  * gfs2_glock_complete - Callback used by locking
1357  * @gl: Pointer to the glock
1358  * @ret: The return value from the dlm
1359  *
1360  */
1361
1362 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1363 {
1364         struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
1365
1366         gl->gl_reply = ret;
1367
1368         if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_flags))) {
1369                 spin_lock(&gl->gl_spin);
1370                 if (gfs2_should_freeze(gl)) {
1371                         set_bit(GLF_FROZEN, &gl->gl_flags);
1372                         spin_unlock(&gl->gl_spin);
1373                         return;
1374                 }
1375                 spin_unlock(&gl->gl_spin);
1376         }
1377         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1378         gfs2_glock_hold(gl);
1379         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1380                 gfs2_glock_put(gl);
1381 }
1382
1383
1384 static int gfs2_shrink_glock_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask)
1385 {
1386         struct gfs2_glock *gl;
1387         int may_demote;
1388         int nr_skipped = 0;
1389         LIST_HEAD(skipped);
1390
1391         if (nr == 0)
1392                 goto out;
1393
1394         if (!(gfp_mask & __GFP_FS))
1395                 return -1;
1396
1397         spin_lock(&lru_lock);
1398         while(nr && !list_empty(&lru_list)) {
1399                 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1400                 list_del_init(&gl->gl_lru);
1401                 atomic_dec(&lru_count);
1402
1403                 /* Test for being demotable */
1404                 if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1405                         gfs2_glock_hold(gl);
1406                         spin_unlock(&lru_lock);
1407                         spin_lock(&gl->gl_spin);
1408                         may_demote = demote_ok(gl);
1409                         if (may_demote) {
1410                                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1411                                 nr--;
1412                         }
1413                         clear_bit(GLF_LOCK, &gl->gl_flags);
1414                         smp_mb__after_clear_bit();
1415                         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1416                                 gfs2_glock_put_nolock(gl);
1417                         spin_unlock(&gl->gl_spin);
1418                         spin_lock(&lru_lock);
1419                         continue;
1420                 }
1421                 nr_skipped++;
1422                 list_add(&gl->gl_lru, &skipped);
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  * Returns: 1 if the bucket has entries
1443  */
1444
1445 static int examine_bucket(glock_examiner examiner, struct gfs2_sbd *sdp,
1446                           unsigned int hash)
1447 {
1448         struct gfs2_glock *gl, *prev = NULL;
1449         int has_entries = 0;
1450         struct hlist_head *head = &gl_hash_table[hash].hb_list;
1451
1452         read_lock(gl_lock_addr(hash));
1453         /* Can't use hlist_for_each_entry - don't want prefetch here */
1454         if (hlist_empty(head))
1455                 goto out;
1456         gl = list_entry(head->first, struct gfs2_glock, gl_list);
1457         while(1) {
1458                 if (!sdp || gl->gl_sbd == sdp) {
1459                         gfs2_glock_hold(gl);
1460                         read_unlock(gl_lock_addr(hash));
1461                         if (prev)
1462                                 gfs2_glock_put(prev);
1463                         prev = gl;
1464                         examiner(gl);
1465                         has_entries = 1;
1466                         read_lock(gl_lock_addr(hash));
1467                 }
1468                 if (gl->gl_list.next == NULL)
1469                         break;
1470                 gl = list_entry(gl->gl_list.next, struct gfs2_glock, gl_list);
1471         }
1472 out:
1473         read_unlock(gl_lock_addr(hash));
1474         if (prev)
1475                 gfs2_glock_put(prev);
1476         cond_resched();
1477         return has_entries;
1478 }
1479
1480
1481 /**
1482  * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1483  * @gl: The glock to thaw
1484  *
1485  * N.B. When we freeze a glock, we leave a ref to the glock outstanding,
1486  * so this has to result in the ref count being dropped by one.
1487  */
1488
1489 static void thaw_glock(struct gfs2_glock *gl)
1490 {
1491         if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1492                 return;
1493         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1494         gfs2_glock_hold(gl);
1495         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1496                 gfs2_glock_put(gl);
1497 }
1498
1499 /**
1500  * clear_glock - look at a glock and see if we can free it from glock cache
1501  * @gl: the glock to look at
1502  *
1503  */
1504
1505 static void clear_glock(struct gfs2_glock *gl)
1506 {
1507         spin_lock(&lru_lock);
1508         if (!list_empty(&gl->gl_lru)) {
1509                 list_del_init(&gl->gl_lru);
1510                 atomic_dec(&lru_count);
1511         }
1512         spin_unlock(&lru_lock);
1513
1514         spin_lock(&gl->gl_spin);
1515         if (find_first_holder(gl) == NULL && gl->gl_state != LM_ST_UNLOCKED)
1516                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1517         spin_unlock(&gl->gl_spin);
1518         gfs2_glock_hold(gl);
1519         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1520                 gfs2_glock_put(gl);
1521 }
1522
1523 /**
1524  * gfs2_glock_thaw - Thaw any frozen glocks
1525  * @sdp: The super block
1526  *
1527  */
1528
1529 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1530 {
1531         unsigned x;
1532
1533         for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1534                 examine_bucket(thaw_glock, sdp, x);
1535 }
1536
1537 /**
1538  * gfs2_gl_hash_clear - Empty out the glock hash table
1539  * @sdp: the filesystem
1540  * @wait: wait until it's all gone
1541  *
1542  * Called when unmounting the filesystem.
1543  */
1544
1545 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1546 {
1547         unsigned int x;
1548
1549         for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1550                 examine_bucket(clear_glock, sdp, x);
1551         flush_workqueue(glock_workqueue);
1552         wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
1553         gfs2_dump_lockstate(sdp);
1554 }
1555
1556 void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1557 {
1558         struct gfs2_glock *gl = ip->i_gl;
1559         int ret;
1560
1561         ret = gfs2_truncatei_resume(ip);
1562         gfs2_assert_withdraw(gl->gl_sbd, ret == 0);
1563
1564         spin_lock(&gl->gl_spin);
1565         clear_bit(GLF_LOCK, &gl->gl_flags);
1566         run_queue(gl, 1);
1567         spin_unlock(&gl->gl_spin);
1568 }
1569
1570 static const char *state2str(unsigned state)
1571 {
1572         switch(state) {
1573         case LM_ST_UNLOCKED:
1574                 return "UN";
1575         case LM_ST_SHARED:
1576                 return "SH";
1577         case LM_ST_DEFERRED:
1578                 return "DF";
1579         case LM_ST_EXCLUSIVE:
1580                 return "EX";
1581         }
1582         return "??";
1583 }
1584
1585 static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags)
1586 {
1587         char *p = buf;
1588         if (flags & LM_FLAG_TRY)
1589                 *p++ = 't';
1590         if (flags & LM_FLAG_TRY_1CB)
1591                 *p++ = 'T';
1592         if (flags & LM_FLAG_NOEXP)
1593                 *p++ = 'e';
1594         if (flags & LM_FLAG_ANY)
1595                 *p++ = 'A';
1596         if (flags & LM_FLAG_PRIORITY)
1597                 *p++ = 'p';
1598         if (flags & GL_ASYNC)
1599                 *p++ = 'a';
1600         if (flags & GL_EXACT)
1601                 *p++ = 'E';
1602         if (flags & GL_NOCACHE)
1603                 *p++ = 'c';
1604         if (test_bit(HIF_HOLDER, &iflags))
1605                 *p++ = 'H';
1606         if (test_bit(HIF_WAIT, &iflags))
1607                 *p++ = 'W';
1608         if (test_bit(HIF_FIRST, &iflags))
1609                 *p++ = 'F';
1610         *p = 0;
1611         return buf;
1612 }
1613
1614 /**
1615  * dump_holder - print information about a glock holder
1616  * @seq: the seq_file struct
1617  * @gh: the glock holder
1618  *
1619  * Returns: 0 on success, -ENOBUFS when we run out of space
1620  */
1621
1622 static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1623 {
1624         struct task_struct *gh_owner = NULL;
1625         char buffer[KSYM_SYMBOL_LEN];
1626         char flags_buf[32];
1627
1628         sprint_symbol(buffer, gh->gh_ip);
1629         if (gh->gh_owner_pid)
1630                 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1631         gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %s\n",
1632                   state2str(gh->gh_state),
1633                   hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1634                   gh->gh_error,
1635                   gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1636                   gh_owner ? gh_owner->comm : "(ended)", buffer);
1637         return 0;
1638 }
1639
1640 static const char *gflags2str(char *buf, const unsigned long *gflags)
1641 {
1642         char *p = buf;
1643         if (test_bit(GLF_LOCK, gflags))
1644                 *p++ = 'l';
1645         if (test_bit(GLF_DEMOTE, gflags))
1646                 *p++ = 'D';
1647         if (test_bit(GLF_PENDING_DEMOTE, gflags))
1648                 *p++ = 'd';
1649         if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1650                 *p++ = 'p';
1651         if (test_bit(GLF_DIRTY, gflags))
1652                 *p++ = 'y';
1653         if (test_bit(GLF_LFLUSH, gflags))
1654                 *p++ = 'f';
1655         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1656                 *p++ = 'i';
1657         if (test_bit(GLF_REPLY_PENDING, gflags))
1658                 *p++ = 'r';
1659         if (test_bit(GLF_INITIAL, gflags))
1660                 *p++ = 'I';
1661         if (test_bit(GLF_FROZEN, gflags))
1662                 *p++ = 'F';
1663         *p = 0;
1664         return buf;
1665 }
1666
1667 /**
1668  * __dump_glock - print information about a glock
1669  * @seq: The seq_file struct
1670  * @gl: the glock
1671  *
1672  * The file format is as follows:
1673  * One line per object, capital letters are used to indicate objects
1674  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1675  * other objects are indented by a single space and follow the glock to
1676  * which they are related. Fields are indicated by lower case letters
1677  * followed by a colon and the field value, except for strings which are in
1678  * [] so that its possible to see if they are composed of spaces for
1679  * example. The field's are n = number (id of the object), f = flags,
1680  * t = type, s = state, r = refcount, e = error, p = pid.
1681  *
1682  * Returns: 0 on success, -ENOBUFS when we run out of space
1683  */
1684
1685 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1686 {
1687         const struct gfs2_glock_operations *glops = gl->gl_ops;
1688         unsigned long long dtime;
1689         const struct gfs2_holder *gh;
1690         char gflags_buf[32];
1691         int error = 0;
1692
1693         dtime = jiffies - gl->gl_demote_time;
1694         dtime *= 1000000/HZ; /* demote time in uSec */
1695         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1696                 dtime = 0;
1697         gfs2_print_dbg(seq, "G:  s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d r:%d\n",
1698                   state2str(gl->gl_state),
1699                   gl->gl_name.ln_type,
1700                   (unsigned long long)gl->gl_name.ln_number,
1701                   gflags2str(gflags_buf, &gl->gl_flags),
1702                   state2str(gl->gl_target),
1703                   state2str(gl->gl_demote_state), dtime,
1704                   atomic_read(&gl->gl_ail_count),
1705                   atomic_read(&gl->gl_ref));
1706
1707         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1708                 error = dump_holder(seq, gh);
1709                 if (error)
1710                         goto out;
1711         }
1712         if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1713                 error = glops->go_dump(seq, gl);
1714 out:
1715         return error;
1716 }
1717
1718 static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1719 {
1720         int ret;
1721         spin_lock(&gl->gl_spin);
1722         ret = __dump_glock(seq, gl);
1723         spin_unlock(&gl->gl_spin);
1724         return ret;
1725 }
1726
1727 /**
1728  * gfs2_dump_lockstate - print out the current lockstate
1729  * @sdp: the filesystem
1730  * @ub: the buffer to copy the information into
1731  *
1732  * If @ub is NULL, dump the lockstate to the console.
1733  *
1734  */
1735
1736 static int gfs2_dump_lockstate(struct gfs2_sbd *sdp)
1737 {
1738         struct gfs2_glock *gl;
1739         struct hlist_node *h;
1740         unsigned int x;
1741         int error = 0;
1742
1743         for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
1744
1745                 read_lock(gl_lock_addr(x));
1746
1747                 hlist_for_each_entry(gl, h, &gl_hash_table[x].hb_list, gl_list) {
1748                         if (gl->gl_sbd != sdp)
1749                                 continue;
1750
1751                         error = dump_glock(NULL, gl);
1752                         if (error)
1753                                 break;
1754                 }
1755
1756                 read_unlock(gl_lock_addr(x));
1757
1758                 if (error)
1759                         break;
1760         }
1761
1762
1763         return error;
1764 }
1765
1766
1767 int __init gfs2_glock_init(void)
1768 {
1769         unsigned i;
1770         for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
1771                 INIT_HLIST_HEAD(&gl_hash_table[i].hb_list);
1772         }
1773 #ifdef GL_HASH_LOCK_SZ
1774         for(i = 0; i < GL_HASH_LOCK_SZ; i++) {
1775                 rwlock_init(&gl_hash_locks[i]);
1776         }
1777 #endif
1778
1779         glock_workqueue = create_workqueue("glock_workqueue");
1780         if (IS_ERR(glock_workqueue))
1781                 return PTR_ERR(glock_workqueue);
1782         gfs2_delete_workqueue = create_workqueue("delete_workqueue");
1783         if (IS_ERR(gfs2_delete_workqueue)) {
1784                 destroy_workqueue(glock_workqueue);
1785                 return PTR_ERR(gfs2_delete_workqueue);
1786         }
1787
1788         register_shrinker(&glock_shrinker);
1789
1790         return 0;
1791 }
1792
1793 void gfs2_glock_exit(void)
1794 {
1795         unregister_shrinker(&glock_shrinker);
1796         destroy_workqueue(glock_workqueue);
1797         destroy_workqueue(gfs2_delete_workqueue);
1798 }
1799
1800 static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1801 {
1802         struct gfs2_glock *gl;
1803
1804 restart:
1805         read_lock(gl_lock_addr(gi->hash));
1806         gl = gi->gl;
1807         if (gl) {
1808                 gi->gl = hlist_entry(gl->gl_list.next,
1809                                      struct gfs2_glock, gl_list);
1810         } else {
1811                 gi->gl = hlist_entry(gl_hash_table[gi->hash].hb_list.first,
1812                                      struct gfs2_glock, gl_list);
1813         }
1814         if (gi->gl)
1815                 gfs2_glock_hold(gi->gl);
1816         read_unlock(gl_lock_addr(gi->hash));
1817         if (gl)
1818                 gfs2_glock_put(gl);
1819         while (gi->gl == NULL) {
1820                 gi->hash++;
1821                 if (gi->hash >= GFS2_GL_HASH_SIZE)
1822                         return 1;
1823                 read_lock(gl_lock_addr(gi->hash));
1824                 gi->gl = hlist_entry(gl_hash_table[gi->hash].hb_list.first,
1825                                      struct gfs2_glock, gl_list);
1826                 if (gi->gl)
1827                         gfs2_glock_hold(gi->gl);
1828                 read_unlock(gl_lock_addr(gi->hash));
1829         }
1830
1831         if (gi->sdp != gi->gl->gl_sbd)
1832                 goto restart;
1833
1834         return 0;
1835 }
1836
1837 static void gfs2_glock_iter_free(struct gfs2_glock_iter *gi)
1838 {
1839         if (gi->gl)
1840                 gfs2_glock_put(gi->gl);
1841         gi->gl = NULL;
1842 }
1843
1844 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1845 {
1846         struct gfs2_glock_iter *gi = seq->private;
1847         loff_t n = *pos;
1848
1849         gi->hash = 0;
1850
1851         do {
1852                 if (gfs2_glock_iter_next(gi)) {
1853                         gfs2_glock_iter_free(gi);
1854                         return NULL;
1855                 }
1856         } while (n--);
1857
1858         return gi->gl;
1859 }
1860
1861 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1862                                  loff_t *pos)
1863 {
1864         struct gfs2_glock_iter *gi = seq->private;
1865
1866         (*pos)++;
1867
1868         if (gfs2_glock_iter_next(gi)) {
1869                 gfs2_glock_iter_free(gi);
1870                 return NULL;
1871         }
1872
1873         return gi->gl;
1874 }
1875
1876 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1877 {
1878         struct gfs2_glock_iter *gi = seq->private;
1879         gfs2_glock_iter_free(gi);
1880 }
1881
1882 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1883 {
1884         return dump_glock(seq, iter_ptr);
1885 }
1886
1887 static const struct seq_operations gfs2_glock_seq_ops = {
1888         .start = gfs2_glock_seq_start,
1889         .next  = gfs2_glock_seq_next,
1890         .stop  = gfs2_glock_seq_stop,
1891         .show  = gfs2_glock_seq_show,
1892 };
1893
1894 static int gfs2_debugfs_open(struct inode *inode, struct file *file)
1895 {
1896         int ret = seq_open_private(file, &gfs2_glock_seq_ops,
1897                                    sizeof(struct gfs2_glock_iter));
1898         if (ret == 0) {
1899                 struct seq_file *seq = file->private_data;
1900                 struct gfs2_glock_iter *gi = seq->private;
1901                 gi->sdp = inode->i_private;
1902         }
1903         return ret;
1904 }
1905
1906 static const struct file_operations gfs2_debug_fops = {
1907         .owner   = THIS_MODULE,
1908         .open    = gfs2_debugfs_open,
1909         .read    = seq_read,
1910         .llseek  = seq_lseek,
1911         .release = seq_release_private,
1912 };
1913
1914 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
1915 {
1916         sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
1917         if (!sdp->debugfs_dir)
1918                 return -ENOMEM;
1919         sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
1920                                                          S_IFREG | S_IRUGO,
1921                                                          sdp->debugfs_dir, sdp,
1922                                                          &gfs2_debug_fops);
1923         if (!sdp->debugfs_dentry_glocks)
1924                 return -ENOMEM;
1925
1926         return 0;
1927 }
1928
1929 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
1930 {
1931         if (sdp && sdp->debugfs_dir) {
1932                 if (sdp->debugfs_dentry_glocks) {
1933                         debugfs_remove(sdp->debugfs_dentry_glocks);
1934                         sdp->debugfs_dentry_glocks = NULL;
1935                 }
1936                 debugfs_remove(sdp->debugfs_dir);
1937                 sdp->debugfs_dir = NULL;
1938         }
1939 }
1940
1941 int gfs2_register_debugfs(void)
1942 {
1943         gfs2_root = debugfs_create_dir("gfs2", NULL);
1944         return gfs2_root ? 0 : -ENOMEM;
1945 }
1946
1947 void gfs2_unregister_debugfs(void)
1948 {
1949         debugfs_remove(gfs2_root);
1950         gfs2_root = NULL;
1951 }