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_promote - promote as many requests as possible on the current queue
 332  * @gl: The glock
 333  *
 334  * Returns: 1 if there is a blocked holder at the head of the list, or 2
 335  *          if a type specific operation is underway.
 336  */
 337
 338 static int do_promote(struct gfs2_glock *gl)
 339 __releases(&gl->gl_spin)
 340 __acquires(&gl->gl_spin)
 341 {
 342         const struct gfs2_glock_operations *glops = gl->gl_ops;
 343         struct gfs2_holder *gh, *tmp;
 344         int ret;
 345
 346 restart:
 347         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 348                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 349                         continue;
 350                 if (may_grant(gl, gh)) {
 351                         if (gh->gh_list.prev == &gl->gl_holders &&
 352                             glops->go_lock) {
 353                                 spin_unlock(&gl->gl_spin);
 354                                 /* FIXME: eliminate this eventually */
 355                                 ret = glops->go_lock(gh);
 356                                 spin_lock(&gl->gl_spin);
 357                                 if (ret) {
 358                                         if (ret == 1)
 359                                                 return 2;
 360                                         gh->gh_error = ret;
 361                                         list_del_init(&gh->gh_list);
 362                                         trace_gfs2_glock_queue(gh, 0);
 363                                         gfs2_holder_wake(gh);
 364                                         goto restart;
 365                                 }
 366                                 set_bit(HIF_HOLDER, &gh->gh_iflags);
 367                                 trace_gfs2_promote(gh, 1);
 368                                 gfs2_holder_wake(gh);
 369                                 goto restart;
 370                         }
 371                         set_bit(HIF_HOLDER, &gh->gh_iflags);
 372                         trace_gfs2_promote(gh, 0);
 373                         gfs2_holder_wake(gh);
 374                         continue;
 375                 }
 376                 if (gh->gh_list.prev == &gl->gl_holders)
 377                         return 1;
 378                 break;
 379         }
 380         return 0;
 381 }
 382
 383 /**
 384  * do_error - Something unexpected has happened during a lock request
 385  *
 386  */
 387
 388 static inline void do_error(struct gfs2_glock *gl, const int ret)
 389 {
 390         struct gfs2_holder *gh, *tmp;
 391
 392         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 393                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 394                         continue;
 395                 if (ret & LM_OUT_ERROR)
 396                         gh->gh_error = -EIO;
 397                 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
 398                         gh->gh_error = GLR_TRYFAILED;
 399                 else
 400                         continue;
 401                 list_del_init(&gh->gh_list);
 402                 trace_gfs2_glock_queue(gh, 0);
 403                 gfs2_holder_wake(gh);
 404         }
 405 }
 406
 407 /**
 408  * find_first_waiter - find the first gh that's waiting for the glock
 409  * @gl: the glock
 410  */
 411
 412 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
 413 {
 414         struct gfs2_holder *gh;
 415
 416         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
 417                 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
 418                         return gh;
 419         }
 420         return NULL;
 421 }
 422
 423 /**
 424  * state_change - record that the glock is now in a different state
 425  * @gl: the glock
 426  * @new_state the new state
 427  *
 428  */
 429
 430 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 431 {
 432         int held1, held2;
 433
 434         held1 = (gl->gl_state != LM_ST_UNLOCKED);
 435         held2 = (new_state != LM_ST_UNLOCKED);
 436
 437         if (held1 != held2) {
 438                 if (held2)
 439                         gfs2_glock_hold(gl);
 440                 else
 441                         gfs2_glock_put_nolock(gl);
 442         }
 443
 444         gl->gl_state = new_state;
 445         gl->gl_tchange = jiffies;
 446 }
 447
 448 static void gfs2_demote_wake(struct gfs2_glock *gl)
 449 {
 450         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 451         clear_bit(GLF_DEMOTE, &gl->gl_flags);
 452         smp_mb__after_clear_bit();
 453         wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
 454 }
 455
 456 /**
 457  * finish_xmote - The DLM has replied to one of our lock requests
 458  * @gl: The glock
 459  * @ret: The status from the DLM
 460  *
 461  */
 462
 463 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
 464 {
 465         const struct gfs2_glock_operations *glops = gl->gl_ops;
 466         struct gfs2_holder *gh;
 467         unsigned state = ret & LM_OUT_ST_MASK;
 468         int rv;
 469
 470         spin_lock(&gl->gl_spin);
 471         trace_gfs2_glock_state_change(gl, state);
 472         state_change(gl, state);
 473         gh = find_first_waiter(gl);
 474
 475         /* Demote to UN request arrived during demote to SH or DF */
 476         if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
 477             state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
 478                 gl->gl_target = LM_ST_UNLOCKED;
 479
 480         /* Check for state != intended state */
 481         if (unlikely(state != gl->gl_target)) {
 482                 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
 483                         /* move to back of queue and try next entry */
 484                         if (ret & LM_OUT_CANCELED) {
 485                                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
 486                                         list_move_tail(&gh->gh_list, &gl->gl_holders);
 487                                 gh = find_first_waiter(gl);
 488                                 gl->gl_target = gh->gh_state;
 489                                 goto retry;
 490                         }
 491                         /* Some error or failed "try lock" - report it */
 492                         if ((ret & LM_OUT_ERROR) ||
 493                             (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 494                                 gl->gl_target = gl->gl_state;
 495                                 do_error(gl, ret);
 496                                 goto out;
 497                         }
 498                 }
 499                 switch(state) {
 500                 /* Unlocked due to conversion deadlock, try again */
 501                 case LM_ST_UNLOCKED:
 502 retry:
 503                         do_xmote(gl, gh, gl->gl_target);
 504                         break;
 505                 /* Conversion fails, unlock and try again */
 506                 case LM_ST_SHARED:
 507                 case LM_ST_DEFERRED:
 508                         do_xmote(gl, gh, LM_ST_UNLOCKED);
 509                         break;
 510                 default: /* Everything else */
 511                         printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
 512                         GLOCK_BUG_ON(gl, 1);
 513                 }
 514                 spin_unlock(&gl->gl_spin);
 515                 return;
 516         }
 517
 518         /* Fast path - we got what we asked for */
 519         if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
 520                 gfs2_demote_wake(gl);
 521         if (state != LM_ST_UNLOCKED) {
 522                 if (glops->go_xmote_bh) {
 523                         spin_unlock(&gl->gl_spin);
 524                         rv = glops->go_xmote_bh(gl, gh);
 525                         spin_lock(&gl->gl_spin);
 526                         if (rv) {
 527                                 do_error(gl, rv);
 528                                 goto out;
 529                         }
 530                 }
 531                 rv = do_promote(gl);
 532                 if (rv == 2)
 533                         goto out_locked;
 534         }
 535 out:
 536         clear_bit(GLF_LOCK, &gl->gl_flags);
 537 out_locked:
 538         spin_unlock(&gl->gl_spin);
 539 }
 540
 541 static unsigned int gfs2_lm_lock(struct gfs2_sbd *sdp, void *lock,
 542                                  unsigned int req_state,
 543                                  unsigned int flags)
 544 {
 545         int ret = LM_OUT_ERROR;
 546
 547         if (!sdp->sd_lockstruct.ls_ops->lm_lock)
 548                 return req_state == LM_ST_UNLOCKED ? 0 : req_state;
 549
 550         if (likely(!test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 551                 ret = sdp->sd_lockstruct.ls_ops->lm_lock(lock,
 552                                                          req_state, flags);
 553         return ret;
 554 }
 555
 556 /**
 557  * do_xmote - Calls the DLM to change the state of a lock
 558  * @gl: The lock state
 559  * @gh: The holder (only for promotes)
 560  * @target: The target lock state
 561  *
 562  */
 563
 564 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
 565 __releases(&gl->gl_spin)
 566 __acquires(&gl->gl_spin)
 567 {
 568         const struct gfs2_glock_operations *glops = gl->gl_ops;
 569         struct gfs2_sbd *sdp = gl->gl_sbd;
 570         unsigned int lck_flags = gh ? gh->gh_flags : 0;
 571         int ret;
 572
 573         lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
 574                       LM_FLAG_PRIORITY);
 575         BUG_ON(gl->gl_state == target);
 576         BUG_ON(gl->gl_state == gl->gl_target);
 577         if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
 578             glops->go_inval) {
 579                 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 580                 do_error(gl, 0); /* Fail queued try locks */
 581         }
 582         spin_unlock(&gl->gl_spin);
 583         if (glops->go_xmote_th)
 584                 glops->go_xmote_th(gl);
 585         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 586                 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
 587         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 588
 589         gfs2_glock_hold(gl);
 590         if (target != LM_ST_UNLOCKED && (gl->gl_state == LM_ST_SHARED ||
 591             gl->gl_state == LM_ST_DEFERRED) &&
 592             !(lck_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 593                 lck_flags |= LM_FLAG_TRY_1CB;
 594         ret = gfs2_lm_lock(sdp, gl, target, lck_flags);
 595
 596         if (!(ret & LM_OUT_ASYNC)) {
 597                 finish_xmote(gl, ret);
 598                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 599                         gfs2_glock_put(gl);
 600         } else {
 601                 GLOCK_BUG_ON(gl, ret != LM_OUT_ASYNC);
 602         }
 603         spin_lock(&gl->gl_spin);
 604 }
 605
 606 /**
 607  * find_first_holder - find the first "holder" gh
 608  * @gl: the glock
 609  */
 610
 611 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
 612 {
 613         struct gfs2_holder *gh;
 614
 615         if (!list_empty(&gl->gl_holders)) {
 616                 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 617                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 618                         return gh;
 619         }
 620         return NULL;
 621 }
 622
 623 /**
 624  * run_queue - do all outstanding tasks related to a glock
 625  * @gl: The glock in question
 626  * @nonblock: True if we must not block in run_queue
 627  *
 628  */
 629
 630 static void run_queue(struct gfs2_glock *gl, const int nonblock)
 631 __releases(&gl->gl_spin)
 632 __acquires(&gl->gl_spin)
 633 {
 634         struct gfs2_holder *gh = NULL;
 635         int ret;
 636
 637         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 638                 return;
 639
 640         GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
 641
 642         if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
 643             gl->gl_demote_state != gl->gl_state) {
 644                 if (find_first_holder(gl))
 645                         goto out_unlock;
 646                 if (nonblock)
 647                         goto out_sched;
 648                 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
 649                 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
 650                 gl->gl_target = gl->gl_demote_state;
 651         } else {
 652                 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
 653                         gfs2_demote_wake(gl);
 654                 ret = do_promote(gl);
 655                 if (ret == 0)
 656                         goto out_unlock;
 657                 if (ret == 2)
 658                         goto out;
 659                 gh = find_first_waiter(gl);
 660                 gl->gl_target = gh->gh_state;
 661                 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 662                         do_error(gl, 0); /* Fail queued try locks */
 663         }
 664         do_xmote(gl, gh, gl->gl_target);
 665 out:
 666         return;
 667
 668 out_sched:
 669         clear_bit(GLF_LOCK, &gl->gl_flags);
 670         smp_mb__after_clear_bit();
 671         gfs2_glock_hold(gl);
 672         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 673                 gfs2_glock_put_nolock(gl);
 674         return;
 675
 676 out_unlock:
 677         clear_bit(GLF_LOCK, &gl->gl_flags);
 678         smp_mb__after_clear_bit();
 679         return;
 680 }
 681
 682 static void delete_work_func(struct work_struct *work)
 683 {
 684         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
 685         struct gfs2_sbd *sdp = gl->gl_sbd;
 686         struct gfs2_inode *ip = NULL;
 687         struct inode *inode;
 688         u64 no_addr = 0;
 689
 690         spin_lock(&gl->gl_spin);
 691         ip = (struct gfs2_inode *)gl->gl_object;
 692         if (ip)
 693                 no_addr = ip->i_no_addr;
 694         spin_unlock(&gl->gl_spin);
 695         if (ip) {
 696                 inode = gfs2_ilookup(sdp->sd_vfs, no_addr);
 697                 if (inode) {
 698                         d_prune_aliases(inode);
 699                         iput(inode);
 700                 }
 701         }
 702         gfs2_glock_put(gl);
 703 }
 704
 705 static void glock_work_func(struct work_struct *work)
 706 {
 707         unsigned long delay = 0;
 708         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
 709         struct gfs2_holder *gh;
 710         int drop_ref = 0;
 711
 712         if (unlikely(test_bit(GLF_FROZEN, &gl->gl_flags))) {
 713                 spin_lock(&gl->gl_spin);
 714                 gh = find_first_waiter(gl);
 715                 if (gh && (gh->gh_flags & LM_FLAG_NOEXP) &&
 716                     test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
 717                         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
 718                 spin_unlock(&gl->gl_spin);
 719         }
 720
 721         if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
 722                 finish_xmote(gl, gl->gl_reply);
 723                 drop_ref = 1;
 724         }
 725         spin_lock(&gl->gl_spin);
 726         if (test_and_clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
 727             gl->gl_state != LM_ST_UNLOCKED &&
 728             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
 729                 unsigned long holdtime, now = jiffies;
 730                 holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
 731                 if (time_before(now, holdtime))
 732                         delay = holdtime - now;
 733                 set_bit(delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE, &gl->gl_flags);
 734         }
 735         run_queue(gl, 0);
 736         spin_unlock(&gl->gl_spin);
 737         if (!delay ||
 738             queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
 739                 gfs2_glock_put(gl);
 740         if (drop_ref)
 741                 gfs2_glock_put(gl);
 742 }
 743
 744 /**
 745  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
 746  * @sdp: The GFS2 superblock
 747  * @number: the lock number
 748  * @glops: The glock_operations to use
 749  * @create: If 0, don't create the glock if it doesn't exist
 750  * @glp: the glock is returned here
 751  *
 752  * This does not lock a glock, just finds/creates structures for one.
 753  *
 754  * Returns: errno
 755  */
 756
 757 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 758                    const struct gfs2_glock_operations *glops, int create,
 759                    struct gfs2_glock **glp)
 760 {
 761         struct super_block *s = sdp->sd_vfs;
 762         struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
 763         struct gfs2_glock *gl, *tmp;
 764         unsigned int hash = gl_hash(sdp, &name);
 765         struct address_space *mapping;
 766
 767         read_lock(gl_lock_addr(hash));
 768         gl = search_bucket(hash, sdp, &name);
 769         read_unlock(gl_lock_addr(hash));
 770
 771         *glp = gl;
 772         if (gl)
 773                 return 0;
 774         if (!create)
 775                 return -ENOENT;
 776
 777         if (glops->go_flags & GLOF_ASPACE)
 778                 gl = kmem_cache_alloc(gfs2_glock_aspace_cachep, GFP_KERNEL);
 779         else
 780                 gl = kmem_cache_alloc(gfs2_glock_cachep, GFP_KERNEL);
 781         if (!gl)
 782                 return -ENOMEM;
 783
 784         atomic_inc(&sdp->sd_glock_disposal);
 785         gl->gl_flags = 0;
 786         gl->gl_name = name;
 787         atomic_set(&gl->gl_ref, 1);
 788         gl->gl_state = LM_ST_UNLOCKED;
 789         gl->gl_target = LM_ST_UNLOCKED;
 790         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 791         gl->gl_hash = hash;
 792         gl->gl_ops = glops;
 793         snprintf(gl->gl_strname, GDLM_STRNAME_BYTES, "%8x%16llx", name.ln_type, (unsigned long long)number);
 794         memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
 795         gl->gl_lksb.sb_lvbptr = gl->gl_lvb;
 796         gl->gl_tchange = jiffies;
 797         gl->gl_object = NULL;
 798         gl->gl_sbd = sdp;
 799         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
 800         INIT_WORK(&gl->gl_delete, delete_work_func);
 801
 802         mapping = gfs2_glock2aspace(gl);
 803         if (mapping) {
 804                 mapping->a_ops = &gfs2_meta_aops;
 805                 mapping->host = s->s_bdev->bd_inode;
 806                 mapping->flags = 0;
 807                 mapping_set_gfp_mask(mapping, GFP_NOFS);
 808                 mapping->assoc_mapping = NULL;
 809                 mapping->backing_dev_info = s->s_bdi;
 810                 mapping->writeback_index = 0;
 811         }
 812
 813         write_lock(gl_lock_addr(hash));
 814         tmp = search_bucket(hash, sdp, &name);
 815         if (tmp) {
 816                 write_unlock(gl_lock_addr(hash));
 817                 glock_free(gl);
 818                 gl = tmp;
 819         } else {
 820                 hlist_add_head(&gl->gl_list, &gl_hash_table[hash].hb_list);
 821                 write_unlock(gl_lock_addr(hash));
 822         }
 823
 824         *glp = gl;
 825
 826         return 0;
 827 }
 828
 829 /**
 830  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
 831  * @gl: the glock
 832  * @state: the state we're requesting
 833  * @flags: the modifier flags
 834  * @gh: the holder structure
 835  *
 836  */
 837
 838 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
 839                       struct gfs2_holder *gh)
 840 {
 841         INIT_LIST_HEAD(&gh->gh_list);
 842         gh->gh_gl = gl;
 843         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 844         gh->gh_owner_pid = get_pid(task_pid(current));
 845         gh->gh_state = state;
 846         gh->gh_flags = flags;
 847         gh->gh_error = 0;
 848         gh->gh_iflags = 0;
 849         gfs2_glock_hold(gl);
 850 }
 851
 852 /**
 853  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
 854  * @state: the state we're requesting
 855  * @flags: the modifier flags
 856  * @gh: the holder structure
 857  *
 858  * Don't mess with the glock.
 859  *
 860  */
 861
 862 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
 863 {
 864         gh->gh_state = state;
 865         gh->gh_flags = flags;
 866         gh->gh_iflags = 0;
 867         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 868         if (gh->gh_owner_pid)
 869                 put_pid(gh->gh_owner_pid);
 870         gh->gh_owner_pid = get_pid(task_pid(current));
 871 }
 872
 873 /**
 874  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 875  * @gh: the holder structure
 876  *
 877  */
 878
 879 void gfs2_holder_uninit(struct gfs2_holder *gh)
 880 {
 881         put_pid(gh->gh_owner_pid);
 882         gfs2_glock_put(gh->gh_gl);
 883         gh->gh_gl = NULL;
 884         gh->gh_ip = 0;
 885 }
 886
 887 /**
 888  * gfs2_glock_holder_wait
 889  * @word: unused
 890  *
 891  * This function and gfs2_glock_demote_wait both show up in the WCHAN
 892  * field. Thus I've separated these otherwise identical functions in
 893  * order to be more informative to the user.
 894  */
 895
 896 static int gfs2_glock_holder_wait(void *word)
 897 {
 898         schedule();
 899         return 0;
 900 }
 901
 902 static int gfs2_glock_demote_wait(void *word)
 903 {
 904         schedule();
 905         return 0;
 906 }
 907
 908 static void wait_on_holder(struct gfs2_holder *gh)
 909 {
 910         might_sleep();
 911         wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
 912 }
 913
 914 static void wait_on_demote(struct gfs2_glock *gl)
 915 {
 916         might_sleep();
 917         wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
 918 }
 919
 920 /**
 921  * handle_callback - process a demote request
 922  * @gl: the glock
 923  * @state: the state the caller wants us to change to
 924  *
 925  * There are only two requests that we are going to see in actual
 926  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
 927  */
 928
 929 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
 930                             unsigned long delay)
 931 {
 932         int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
 933
 934         set_bit(bit, &gl->gl_flags);
 935         if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
 936                 gl->gl_demote_state = state;
 937                 gl->gl_demote_time = jiffies;
 938         } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
 939                         gl->gl_demote_state != state) {
 940                 gl->gl_demote_state = LM_ST_UNLOCKED;
 941         }
 942         if (gl->gl_ops->go_callback)
 943                 gl->gl_ops->go_callback(gl);
 944         trace_gfs2_demote_rq(gl);
 945 }
 946
 947 /**
 948  * gfs2_glock_wait - wait on a glock acquisition
 949  * @gh: the glock holder
 950  *
 951  * Returns: 0 on success
 952  */
 953
 954 int gfs2_glock_wait(struct gfs2_holder *gh)
 955 {
 956         wait_on_holder(gh);
 957         return gh->gh_error;
 958 }
 959
 960 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
 961 {
 962         va_list args;
 963
 964         va_start(args, fmt);
 965         if (seq) {
 966                 struct gfs2_glock_iter *gi = seq->private;
 967                 vsprintf(gi->string, fmt, args);
 968                 seq_printf(seq, gi->string);
 969         } else {
 970                 printk(KERN_ERR " ");
 971                 vprintk(fmt, args);
 972         }
 973         va_end(args);
 974 }
 975
 976 /**
 977  * add_to_queue - Add a holder to the wait queue (but look for recursion)
 978  * @gh: the holder structure to add
 979  *
 980  * Eventually we should move the recursive locking trap to a
 981  * debugging option or something like that. This is the fast
 982  * path and needs to have the minimum number of distractions.
 983  *
 984  */
 985
 986 static inline void add_to_queue(struct gfs2_holder *gh)
 987 __releases(&gl->gl_spin)
 988 __acquires(&gl->gl_spin)
 989 {
 990         struct gfs2_glock *gl = gh->gh_gl;
 991         struct gfs2_sbd *sdp = gl->gl_sbd;
 992         struct list_head *insert_pt = NULL;
 993         struct gfs2_holder *gh2;
 994         int try_lock = 0;
 995
 996         BUG_ON(gh->gh_owner_pid == NULL);
 997         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
 998                 BUG();
 999
1000         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
1001                 if (test_bit(GLF_LOCK, &gl->gl_flags))
1002                         try_lock = 1;
1003                 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
1004                         goto fail;
1005         }
1006
1007         list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
1008                 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
1009                     (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
1010                         goto trap_recursive;
1011                 if (try_lock &&
1012                     !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
1013                     !may_grant(gl, gh)) {
1014 fail:
1015                         gh->gh_error = GLR_TRYFAILED;
1016                         gfs2_holder_wake(gh);
1017                         return;
1018                 }
1019                 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
1020                         continue;
1021                 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
1022                         insert_pt = &gh2->gh_list;
1023         }
1024         if (likely(insert_pt == NULL)) {
1025                 list_add_tail(&gh->gh_list, &gl->gl_holders);
1026                 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
1027                         goto do_cancel;
1028                 return;
1029         }
1030         trace_gfs2_glock_queue(gh, 1);
1031         list_add_tail(&gh->gh_list, insert_pt);
1032 do_cancel:
1033         gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
1034         if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
1035                 spin_unlock(&gl->gl_spin);
1036                 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
1037                         sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
1038                 spin_lock(&gl->gl_spin);
1039         }
1040         return;
1041
1042 trap_recursive:
1043         print_symbol(KERN_ERR "original: %s\n", gh2->gh_ip);
1044         printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
1045         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1046                gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
1047         print_symbol(KERN_ERR "new: %s\n", gh->gh_ip);
1048         printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
1049         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1050                gh->gh_gl->gl_name.ln_type, gh->gh_state);
1051         __dump_glock(NULL, gl);
1052         BUG();
1053 }
1054
1055 /**
1056  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1057  * @gh: the holder structure
1058  *
1059  * if (gh->gh_flags & GL_ASYNC), this never returns an error
1060  *
1061  * Returns: 0, GLR_TRYFAILED, or errno on failure
1062  */
1063
1064 int gfs2_glock_nq(struct gfs2_holder *gh)
1065 {
1066         struct gfs2_glock *gl = gh->gh_gl;
1067         struct gfs2_sbd *sdp = gl->gl_sbd;
1068         int error = 0;
1069
1070         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
1071                 return -EIO;
1072
1073         spin_lock(&gl->gl_spin);
1074         add_to_queue(gh);
1075         run_queue(gl, 1);
1076         spin_unlock(&gl->gl_spin);
1077
1078         if (!(gh->gh_flags & GL_ASYNC))
1079                 error = gfs2_glock_wait(gh);
1080
1081         return error;
1082 }
1083
1084 /**
1085  * gfs2_glock_poll - poll to see if an async request has been completed
1086  * @gh: the holder
1087  *
1088  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1089  */
1090
1091 int gfs2_glock_poll(struct gfs2_holder *gh)
1092 {
1093         return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1094 }
1095
1096 /**
1097  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1098  * @gh: the glock holder
1099  *
1100  */
1101
1102 void gfs2_glock_dq(struct gfs2_holder *gh)
1103 {
1104         struct gfs2_glock *gl = gh->gh_gl;
1105         const struct gfs2_glock_operations *glops = gl->gl_ops;
1106         unsigned delay = 0;
1107         int fast_path = 0;
1108
1109         spin_lock(&gl->gl_spin);
1110         if (gh->gh_flags & GL_NOCACHE)
1111                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1112
1113         list_del_init(&gh->gh_list);
1114         if (find_first_holder(gl) == NULL) {
1115                 if (glops->go_unlock) {
1116                         GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1117                         spin_unlock(&gl->gl_spin);
1118                         glops->go_unlock(gh);
1119                         spin_lock(&gl->gl_spin);
1120                         clear_bit(GLF_LOCK, &gl->gl_flags);
1121                 }
1122                 if (list_empty(&gl->gl_holders) &&
1123                     !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1124                     !test_bit(GLF_DEMOTE, &gl->gl_flags))
1125                         fast_path = 1;
1126         }
1127         trace_gfs2_glock_queue(gh, 0);
1128         spin_unlock(&gl->gl_spin);
1129         if (likely(fast_path))
1130                 return;
1131
1132         gfs2_glock_hold(gl);
1133         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1134             !test_bit(GLF_DEMOTE, &gl->gl_flags))
1135                 delay = gl->gl_ops->go_min_hold_time;
1136         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1137                 gfs2_glock_put(gl);
1138 }
1139
1140 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1141 {
1142         struct gfs2_glock *gl = gh->gh_gl;
1143         gfs2_glock_dq(gh);
1144         wait_on_demote(gl);
1145 }
1146
1147 /**
1148  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1149  * @gh: the holder structure
1150  *
1151  */
1152
1153 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1154 {
1155         gfs2_glock_dq(gh);
1156         gfs2_holder_uninit(gh);
1157 }
1158
1159 /**
1160  * gfs2_glock_nq_num - acquire a glock based on lock number
1161  * @sdp: the filesystem
1162  * @number: the lock number
1163  * @glops: the glock operations for the type of glock
1164  * @state: the state to acquire the glock in
1165  * @flags: modifier flags for the aquisition
1166  * @gh: the struct gfs2_holder
1167  *
1168  * Returns: errno
1169  */
1170
1171 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1172                       const struct gfs2_glock_operations *glops,
1173                       unsigned int state, int flags, struct gfs2_holder *gh)
1174 {
1175         struct gfs2_glock *gl;
1176         int error;
1177
1178         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1179         if (!error) {
1180                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1181                 gfs2_glock_put(gl);
1182         }
1183
1184         return error;
1185 }
1186
1187 /**
1188  * glock_compare - Compare two struct gfs2_glock structures for sorting
1189  * @arg_a: the first structure
1190  * @arg_b: the second structure
1191  *
1192  */
1193
1194 static int glock_compare(const void *arg_a, const void *arg_b)
1195 {
1196         const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1197         const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1198         const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1199         const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1200
1201         if (a->ln_number > b->ln_number)
1202                 return 1;
1203         if (a->ln_number < b->ln_number)
1204                 return -1;
1205         BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1206         return 0;
1207 }
1208
1209 /**
1210  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1211  * @num_gh: the number of structures
1212  * @ghs: an array of struct gfs2_holder structures
1213  *
1214  * Returns: 0 on success (all glocks acquired),
1215  *          errno on failure (no glocks acquired)
1216  */
1217
1218 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1219                      struct gfs2_holder **p)
1220 {
1221         unsigned int x;
1222         int error = 0;
1223
1224         for (x = 0; x < num_gh; x++)
1225                 p[x] = &ghs[x];
1226
1227         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1228
1229         for (x = 0; x < num_gh; x++) {
1230                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1231
1232                 error = gfs2_glock_nq(p[x]);
1233                 if (error) {
1234                         while (x--)
1235                                 gfs2_glock_dq(p[x]);
1236                         break;
1237                 }
1238         }
1239
1240         return error;
1241 }
1242
1243 /**
1244  * gfs2_glock_nq_m - acquire multiple glocks
1245  * @num_gh: the number of structures
1246  * @ghs: an array of struct gfs2_holder structures
1247  *
1248  *
1249  * Returns: 0 on success (all glocks acquired),
1250  *          errno on failure (no glocks acquired)
1251  */
1252
1253 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1254 {
1255         struct gfs2_holder *tmp[4];
1256         struct gfs2_holder **pph = tmp;
1257         int error = 0;
1258
1259         switch(num_gh) {
1260         case 0:
1261                 return 0;
1262         case 1:
1263                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1264                 return gfs2_glock_nq(ghs);
1265         default:
1266                 if (num_gh <= 4)
1267                         break;
1268                 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1269                 if (!pph)
1270                         return -ENOMEM;
1271         }
1272
1273         error = nq_m_sync(num_gh, ghs, pph);
1274
1275         if (pph != tmp)
1276                 kfree(pph);
1277
1278         return error;
1279 }
1280
1281 /**
1282  * gfs2_glock_dq_m - release multiple glocks
1283  * @num_gh: the number of structures
1284  * @ghs: an array of struct gfs2_holder structures
1285  *
1286  */
1287
1288 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1289 {
1290         unsigned int x;
1291
1292         for (x = 0; x < num_gh; x++)
1293                 gfs2_glock_dq(&ghs[x]);
1294 }
1295
1296 /**
1297  * gfs2_glock_dq_uninit_m - release multiple glocks
1298  * @num_gh: the number of structures
1299  * @ghs: an array of struct gfs2_holder structures
1300  *
1301  */
1302
1303 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1304 {
1305         unsigned int x;
1306
1307         for (x = 0; x < num_gh; x++)
1308                 gfs2_glock_dq_uninit(&ghs[x]);
1309 }
1310
1311 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1312 {
1313         unsigned long delay = 0;
1314         unsigned long holdtime;
1315         unsigned long now = jiffies;
1316
1317         gfs2_glock_hold(gl);
1318         holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
1319         if (time_before(now, holdtime))
1320                 delay = holdtime - now;
1321         if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1322                 delay = gl->gl_ops->go_min_hold_time;
1323
1324         spin_lock(&gl->gl_spin);
1325         handle_callback(gl, state, delay);
1326         spin_unlock(&gl->gl_spin);
1327         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1328                 gfs2_glock_put(gl);
1329 }
1330
1331 /**
1332  * gfs2_glock_complete - Callback used by locking
1333  * @gl: Pointer to the glock
1334  * @ret: The return value from the dlm
1335  *
1336  */
1337
1338 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1339 {
1340         struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
1341         gl->gl_reply = ret;
1342         if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_flags))) {
1343                 struct gfs2_holder *gh;
1344                 spin_lock(&gl->gl_spin);
1345                 gh = find_first_waiter(gl);
1346                 if ((!(gh && (gh->gh_flags & LM_FLAG_NOEXP)) &&
1347                      (gl->gl_target != LM_ST_UNLOCKED)) ||
1348                     ((ret & ~LM_OUT_ST_MASK) != 0))
1349                         set_bit(GLF_FROZEN, &gl->gl_flags);
1350                 spin_unlock(&gl->gl_spin);
1351                 if (test_bit(GLF_FROZEN, &gl->gl_flags))
1352                         return;
1353         }
1354         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1355         gfs2_glock_hold(gl);
1356         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1357                 gfs2_glock_put(gl);
1358 }
1359
1360
1361 static int gfs2_shrink_glock_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask)
1362 {
1363         struct gfs2_glock *gl;
1364         int may_demote;
1365         int nr_skipped = 0;
1366         LIST_HEAD(skipped);
1367
1368         if (nr == 0)
1369                 goto out;
1370
1371         if (!(gfp_mask & __GFP_FS))
1372                 return -1;
1373
1374         spin_lock(&lru_lock);
1375         while(nr && !list_empty(&lru_list)) {
1376                 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1377                 list_del_init(&gl->gl_lru);
1378                 atomic_dec(&lru_count);
1379
1380                 /* Test for being demotable */
1381                 if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1382                         gfs2_glock_hold(gl);
1383                         spin_unlock(&lru_lock);
1384                         spin_lock(&gl->gl_spin);
1385                         may_demote = demote_ok(gl);
1386                         if (may_demote) {
1387                                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1388                                 nr--;
1389                         }
1390                         clear_bit(GLF_LOCK, &gl->gl_flags);
1391                         smp_mb__after_clear_bit();
1392                         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1393                                 gfs2_glock_put_nolock(gl);
1394                         spin_unlock(&gl->gl_spin);
1395                         spin_lock(&lru_lock);
1396                         continue;
1397                 }
1398                 nr_skipped++;
1399                 list_add(&gl->gl_lru, &skipped);
1400         }
1401         list_splice(&skipped, &lru_list);
1402         atomic_add(nr_skipped, &lru_count);
1403         spin_unlock(&lru_lock);
1404 out:
1405         return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
1406 }
1407
1408 static struct shrinker glock_shrinker = {
1409         .shrink = gfs2_shrink_glock_memory,
1410         .seeks = DEFAULT_SEEKS,
1411 };
1412
1413 /**
1414  * examine_bucket - Call a function for glock in a hash bucket
1415  * @examiner: the function
1416  * @sdp: the filesystem
1417  * @bucket: the bucket
1418  *
1419  * Returns: 1 if the bucket has entries
1420  */
1421
1422 static int examine_bucket(glock_examiner examiner, struct gfs2_sbd *sdp,
1423                           unsigned int hash)
1424 {
1425         struct gfs2_glock *gl, *prev = NULL;
1426         int has_entries = 0;
1427         struct hlist_head *head = &gl_hash_table[hash].hb_list;
1428
1429         read_lock(gl_lock_addr(hash));
1430         /* Can't use hlist_for_each_entry - don't want prefetch here */
1431         if (hlist_empty(head))
1432                 goto out;
1433         gl = list_entry(head->first, struct gfs2_glock, gl_list);
1434         while(1) {
1435                 if (!sdp || gl->gl_sbd == sdp) {
1436                         gfs2_glock_hold(gl);
1437                         read_unlock(gl_lock_addr(hash));
1438                         if (prev)
1439                                 gfs2_glock_put(prev);
1440                         prev = gl;
1441                         examiner(gl);
1442                         has_entries = 1;
1443                         read_lock(gl_lock_addr(hash));
1444                 }
1445                 if (gl->gl_list.next == NULL)
1446                         break;
1447                 gl = list_entry(gl->gl_list.next, struct gfs2_glock, gl_list);
1448         }
1449 out:
1450         read_unlock(gl_lock_addr(hash));
1451         if (prev)
1452                 gfs2_glock_put(prev);
1453         cond_resched();
1454         return has_entries;
1455 }
1456
1457
1458 /**
1459  * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1460  * @gl: The glock to thaw
1461  *
1462  * N.B. When we freeze a glock, we leave a ref to the glock outstanding,
1463  * so this has to result in the ref count being dropped by one.
1464  */
1465
1466 static void thaw_glock(struct gfs2_glock *gl)
1467 {
1468         if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1469                 return;
1470         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1471         gfs2_glock_hold(gl);
1472         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1473                 gfs2_glock_put(gl);
1474 }
1475
1476 /**
1477  * clear_glock - look at a glock and see if we can free it from glock cache
1478  * @gl: the glock to look at
1479  *
1480  */
1481
1482 static void clear_glock(struct gfs2_glock *gl)
1483 {
1484         spin_lock(&lru_lock);
1485         if (!list_empty(&gl->gl_lru)) {
1486                 list_del_init(&gl->gl_lru);
1487                 atomic_dec(&lru_count);
1488         }
1489         spin_unlock(&lru_lock);
1490
1491         spin_lock(&gl->gl_spin);
1492         if (find_first_holder(gl) == NULL && 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         unsigned x;
1509
1510         for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1511                 examine_bucket(thaw_glock, sdp, x);
1512 }
1513
1514 /**
1515  * gfs2_gl_hash_clear - Empty out the glock hash table
1516  * @sdp: the filesystem
1517  * @wait: wait until it's all gone
1518  *
1519  * Called when unmounting the filesystem.
1520  */
1521
1522 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1523 {
1524         unsigned int x;
1525
1526         for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1527                 examine_bucket(clear_glock, sdp, x);
1528         flush_workqueue(glock_workqueue);
1529         wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
1530         gfs2_dump_lockstate(sdp);
1531 }
1532
1533 void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1534 {
1535         struct gfs2_glock *gl = ip->i_gl;
1536         int ret;
1537
1538         ret = gfs2_truncatei_resume(ip);
1539         gfs2_assert_withdraw(gl->gl_sbd, ret == 0);
1540
1541         spin_lock(&gl->gl_spin);
1542         clear_bit(GLF_LOCK, &gl->gl_flags);
1543         run_queue(gl, 1);
1544         spin_unlock(&gl->gl_spin);
1545 }
1546
1547 static const char *state2str(unsigned state)
1548 {
1549         switch(state) {
1550         case LM_ST_UNLOCKED:
1551                 return "UN";
1552         case LM_ST_SHARED:
1553                 return "SH";
1554         case LM_ST_DEFERRED:
1555                 return "DF";
1556         case LM_ST_EXCLUSIVE:
1557                 return "EX";
1558         }
1559         return "??";
1560 }
1561
1562 static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags)
1563 {
1564         char *p = buf;
1565         if (flags & LM_FLAG_TRY)
1566                 *p++ = 't';
1567         if (flags & LM_FLAG_TRY_1CB)
1568                 *p++ = 'T';
1569         if (flags & LM_FLAG_NOEXP)
1570                 *p++ = 'e';
1571         if (flags & LM_FLAG_ANY)
1572                 *p++ = 'A';
1573         if (flags & LM_FLAG_PRIORITY)
1574                 *p++ = 'p';
1575         if (flags & GL_ASYNC)
1576                 *p++ = 'a';
1577         if (flags & GL_EXACT)
1578                 *p++ = 'E';
1579         if (flags & GL_NOCACHE)
1580                 *p++ = 'c';
1581         if (test_bit(HIF_HOLDER, &iflags))
1582                 *p++ = 'H';
1583         if (test_bit(HIF_WAIT, &iflags))
1584                 *p++ = 'W';
1585         if (test_bit(HIF_FIRST, &iflags))
1586                 *p++ = 'F';
1587         *p = 0;
1588         return buf;
1589 }
1590
1591 /**
1592  * dump_holder - print information about a glock holder
1593  * @seq: the seq_file struct
1594  * @gh: the glock holder
1595  *
1596  * Returns: 0 on success, -ENOBUFS when we run out of space
1597  */
1598
1599 static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1600 {
1601         struct task_struct *gh_owner = NULL;
1602         char buffer[KSYM_SYMBOL_LEN];
1603         char flags_buf[32];
1604
1605         sprint_symbol(buffer, gh->gh_ip);
1606         if (gh->gh_owner_pid)
1607                 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1608         gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %s\n",
1609                   state2str(gh->gh_state),
1610                   hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1611                   gh->gh_error,
1612                   gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1613                   gh_owner ? gh_owner->comm : "(ended)", buffer);
1614         return 0;
1615 }
1616
1617 static const char *gflags2str(char *buf, const unsigned long *gflags)
1618 {
1619         char *p = buf;
1620         if (test_bit(GLF_LOCK, gflags))
1621                 *p++ = 'l';
1622         if (test_bit(GLF_DEMOTE, gflags))
1623                 *p++ = 'D';
1624         if (test_bit(GLF_PENDING_DEMOTE, gflags))
1625                 *p++ = 'd';
1626         if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1627                 *p++ = 'p';
1628         if (test_bit(GLF_DIRTY, gflags))
1629                 *p++ = 'y';
1630         if (test_bit(GLF_LFLUSH, gflags))
1631                 *p++ = 'f';
1632         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1633                 *p++ = 'i';
1634         if (test_bit(GLF_REPLY_PENDING, gflags))
1635                 *p++ = 'r';
1636         if (test_bit(GLF_INITIAL, gflags))
1637                 *p++ = 'I';
1638         if (test_bit(GLF_FROZEN, gflags))
1639                 *p++ = 'F';
1640         *p = 0;
1641         return buf;
1642 }
1643
1644 /**
1645  * __dump_glock - print information about a glock
1646  * @seq: The seq_file struct
1647  * @gl: the glock
1648  *
1649  * The file format is as follows:
1650  * One line per object, capital letters are used to indicate objects
1651  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1652  * other objects are indented by a single space and follow the glock to
1653  * which they are related. Fields are indicated by lower case letters
1654  * followed by a colon and the field value, except for strings which are in
1655  * [] so that its possible to see if they are composed of spaces for
1656  * example. The field's are n = number (id of the object), f = flags,
1657  * t = type, s = state, r = refcount, e = error, p = pid.
1658  *
1659  * Returns: 0 on success, -ENOBUFS when we run out of space
1660  */
1661
1662 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1663 {
1664         const struct gfs2_glock_operations *glops = gl->gl_ops;
1665         unsigned long long dtime;
1666         const struct gfs2_holder *gh;
1667         char gflags_buf[32];
1668         int error = 0;
1669
1670         dtime = jiffies - gl->gl_demote_time;
1671         dtime *= 1000000/HZ; /* demote time in uSec */
1672         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1673                 dtime = 0;
1674         gfs2_print_dbg(seq, "G:  s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d r:%d\n",
1675                   state2str(gl->gl_state),
1676                   gl->gl_name.ln_type,
1677                   (unsigned long long)gl->gl_name.ln_number,
1678                   gflags2str(gflags_buf, &gl->gl_flags),
1679                   state2str(gl->gl_target),
1680                   state2str(gl->gl_demote_state), dtime,
1681                   atomic_read(&gl->gl_ail_count),
1682                   atomic_read(&gl->gl_ref));
1683
1684         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1685                 error = dump_holder(seq, gh);
1686                 if (error)
1687                         goto out;
1688         }
1689         if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1690                 error = glops->go_dump(seq, gl);
1691 out:
1692         return error;
1693 }
1694
1695 static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1696 {
1697         int ret;
1698         spin_lock(&gl->gl_spin);
1699         ret = __dump_glock(seq, gl);
1700         spin_unlock(&gl->gl_spin);
1701         return ret;
1702 }
1703
1704 /**
1705  * gfs2_dump_lockstate - print out the current lockstate
1706  * @sdp: the filesystem
1707  * @ub: the buffer to copy the information into
1708  *
1709  * If @ub is NULL, dump the lockstate to the console.
1710  *
1711  */
1712
1713 static int gfs2_dump_lockstate(struct gfs2_sbd *sdp)
1714 {
1715         struct gfs2_glock *gl;
1716         struct hlist_node *h;
1717         unsigned int x;
1718         int error = 0;
1719
1720         for (x = 0; x < GFS2_GL_HASH_SIZE; x++) {
1721
1722                 read_lock(gl_lock_addr(x));
1723
1724                 hlist_for_each_entry(gl, h, &gl_hash_table[x].hb_list, gl_list) {
1725                         if (gl->gl_sbd != sdp)
1726                                 continue;
1727
1728                         error = dump_glock(NULL, gl);
1729                         if (error)
1730                                 break;
1731                 }
1732
1733                 read_unlock(gl_lock_addr(x));
1734
1735                 if (error)
1736                         break;
1737         }
1738
1739
1740         return error;
1741 }
1742
1743
1744 int __init gfs2_glock_init(void)
1745 {
1746         unsigned i;
1747         for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
1748                 INIT_HLIST_HEAD(&gl_hash_table[i].hb_list);
1749         }
1750 #ifdef GL_HASH_LOCK_SZ
1751         for(i = 0; i < GL_HASH_LOCK_SZ; i++) {
1752                 rwlock_init(&gl_hash_locks[i]);
1753         }
1754 #endif
1755
1756         glock_workqueue = create_workqueue("glock_workqueue");
1757         if (IS_ERR(glock_workqueue))
1758                 return PTR_ERR(glock_workqueue);
1759         gfs2_delete_workqueue = create_workqueue("delete_workqueue");
1760         if (IS_ERR(gfs2_delete_workqueue)) {
1761                 destroy_workqueue(glock_workqueue);
1762                 return PTR_ERR(gfs2_delete_workqueue);
1763         }
1764
1765         register_shrinker(&glock_shrinker);
1766
1767         return 0;
1768 }
1769
1770 void gfs2_glock_exit(void)
1771 {
1772         unregister_shrinker(&glock_shrinker);
1773         destroy_workqueue(glock_workqueue);
1774         destroy_workqueue(gfs2_delete_workqueue);
1775 }
1776
1777 static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1778 {
1779         struct gfs2_glock *gl;
1780
1781 restart:
1782         read_lock(gl_lock_addr(gi->hash));
1783         gl = gi->gl;
1784         if (gl) {
1785                 gi->gl = hlist_entry(gl->gl_list.next,
1786                                      struct gfs2_glock, gl_list);
1787         } else {
1788                 gi->gl = hlist_entry(gl_hash_table[gi->hash].hb_list.first,
1789                                      struct gfs2_glock, gl_list);
1790         }
1791         if (gi->gl)
1792                 gfs2_glock_hold(gi->gl);
1793         read_unlock(gl_lock_addr(gi->hash));
1794         if (gl)
1795                 gfs2_glock_put(gl);
1796         while (gi->gl == NULL) {
1797                 gi->hash++;
1798                 if (gi->hash >= GFS2_GL_HASH_SIZE)
1799                         return 1;
1800                 read_lock(gl_lock_addr(gi->hash));
1801                 gi->gl = hlist_entry(gl_hash_table[gi->hash].hb_list.first,
1802                                      struct gfs2_glock, gl_list);
1803                 if (gi->gl)
1804                         gfs2_glock_hold(gi->gl);
1805                 read_unlock(gl_lock_addr(gi->hash));
1806         }
1807
1808         if (gi->sdp != gi->gl->gl_sbd)
1809                 goto restart;
1810
1811         return 0;
1812 }
1813
1814 static void gfs2_glock_iter_free(struct gfs2_glock_iter *gi)
1815 {
1816         if (gi->gl)
1817                 gfs2_glock_put(gi->gl);
1818         gi->gl = NULL;
1819 }
1820
1821 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1822 {
1823         struct gfs2_glock_iter *gi = seq->private;
1824         loff_t n = *pos;
1825
1826         gi->hash = 0;
1827
1828         do {
1829                 if (gfs2_glock_iter_next(gi)) {
1830                         gfs2_glock_iter_free(gi);
1831                         return NULL;
1832                 }
1833         } while (n--);
1834
1835         return gi->gl;
1836 }
1837
1838 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1839                                  loff_t *pos)
1840 {
1841         struct gfs2_glock_iter *gi = seq->private;
1842
1843         (*pos)++;
1844
1845         if (gfs2_glock_iter_next(gi)) {
1846                 gfs2_glock_iter_free(gi);
1847                 return NULL;
1848         }
1849
1850         return gi->gl;
1851 }
1852
1853 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1854 {
1855         struct gfs2_glock_iter *gi = seq->private;
1856         gfs2_glock_iter_free(gi);
1857 }
1858
1859 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1860 {
1861         return dump_glock(seq, iter_ptr);
1862 }
1863
1864 static const struct seq_operations gfs2_glock_seq_ops = {
1865         .start = gfs2_glock_seq_start,
1866         .next  = gfs2_glock_seq_next,
1867         .stop  = gfs2_glock_seq_stop,
1868         .show  = gfs2_glock_seq_show,
1869 };
1870
1871 static int gfs2_debugfs_open(struct inode *inode, struct file *file)
1872 {
1873         int ret = seq_open_private(file, &gfs2_glock_seq_ops,
1874                                    sizeof(struct gfs2_glock_iter));
1875         if (ret == 0) {
1876                 struct seq_file *seq = file->private_data;
1877                 struct gfs2_glock_iter *gi = seq->private;
1878                 gi->sdp = inode->i_private;
1879         }
1880         return ret;
1881 }
1882
1883 static const struct file_operations gfs2_debug_fops = {
1884         .owner   = THIS_MODULE,
1885         .open    = gfs2_debugfs_open,
1886         .read    = seq_read,
1887         .llseek  = seq_lseek,
1888         .release = seq_release_private,
1889 };
1890
1891 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
1892 {
1893         sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
1894         if (!sdp->debugfs_dir)
1895                 return -ENOMEM;
1896         sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
1897                                                          S_IFREG | S_IRUGO,
1898                                                          sdp->debugfs_dir, sdp,
1899                                                          &gfs2_debug_fops);
1900         if (!sdp->debugfs_dentry_glocks)
1901                 return -ENOMEM;
1902
1903         return 0;
1904 }
1905
1906 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
1907 {
1908         if (sdp && sdp->debugfs_dir) {
1909                 if (sdp->debugfs_dentry_glocks) {
1910                         debugfs_remove(sdp->debugfs_dentry_glocks);
1911                         sdp->debugfs_dentry_glocks = NULL;
1912                 }
1913                 debugfs_remove(sdp->debugfs_dir);
1914                 sdp->debugfs_dir = NULL;
1915         }
1916 }
1917
1918 int gfs2_register_debugfs(void)
1919 {
1920         gfs2_root = debugfs_create_dir("gfs2", NULL);
1921         return gfs2_root ? 0 : -ENOMEM;
1922 }
1923
1924 void gfs2_unregister_debugfs(void)
1925 {
1926         debugfs_remove(gfs2_root);
1927         gfs2_root = NULL;
1928 }