fs/gfs2/glock.c

   1 /*
   2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   3  * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
   4  *
   5  * This copyrighted material is made available to anyone wishing to use,
   6  * modify, copy, or redistribute it subject to the terms and conditions
   7  * of the GNU General Public License version 2.
   8  */
   9
  10 #include <linux/sched.h>
  11 #include <linux/slab.h>
  12 #include <linux/spinlock.h>
  13 #include <linux/buffer_head.h>
  14 #include <linux/delay.h>
  15 #include <linux/sort.h>
  16 #include <linux/jhash.h>
  17 #include <linux/kallsyms.h>
  18 #include <linux/gfs2_ondisk.h>
  19 #include <linux/list.h>
  20 #include <linux/wait.h>
  21 #include <linux/module.h>
  22 #include <asm/uaccess.h>
  23 #include <linux/seq_file.h>
  24 #include <linux/debugfs.h>
  25 #include <linux/kthread.h>
  26 #include <linux/freezer.h>
  27 #include <linux/workqueue.h>
  28 #include <linux/jiffies.h>
  29 #include <linux/rcupdate.h>
  30 #include <linux/rculist_bl.h>
  31 #include <linux/bit_spinlock.h>
  32 #include <linux/percpu.h>
  33
  34 #include "gfs2.h"
  35 #include "incore.h"
  36 #include "glock.h"
  37 #include "glops.h"
  38 #include "inode.h"
  39 #include "lops.h"
  40 #include "meta_io.h"
  41 #include "quota.h"
  42 #include "super.h"
  43 #include "util.h"
  44 #include "bmap.h"
  45 #define CREATE_TRACE_POINTS
  46 #include "trace_gfs2.h"
  47
  48 struct gfs2_glock_iter {
  49         int hash;                       /* hash bucket index           */
  50         unsigned nhash;                 /* Index within current bucket */
  51         struct gfs2_sbd *sdp;           /* incore superblock           */
  52         struct gfs2_glock *gl;          /* current glock struct        */
  53         loff_t last_pos;                /* last position               */
  54 };
  55
  56 typedef void (*glock_examiner) (struct gfs2_glock * gl);
  57
  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 hlist_bl_head gl_hash_table[GFS2_GL_HASH_SIZE];
  74 static struct dentry *gfs2_root;
  75
  76 /**
  77  * gl_hash() - Turn glock number into hash bucket number
  78  * @lock: The glock number
  79  *
  80  * Returns: The number of the corresponding hash bucket
  81  */
  82
  83 static unsigned int gl_hash(const struct gfs2_sbd *sdp,
  84                             const struct lm_lockname *name)
  85 {
  86         unsigned int h;
  87
  88         h = jhash(&name->ln_number, sizeof(u64), 0);
  89         h = jhash(&name->ln_type, sizeof(unsigned int), h);
  90         h = jhash(&sdp, sizeof(struct gfs2_sbd *), h);
  91         h &= GFS2_GL_HASH_MASK;
  92
  93         return h;
  94 }
  95
  96 static inline void spin_lock_bucket(unsigned int hash)
  97 {
  98         hlist_bl_lock(&gl_hash_table[hash]);
  99 }
 100
 101 static inline void spin_unlock_bucket(unsigned int hash)
 102 {
 103         hlist_bl_unlock(&gl_hash_table[hash]);
 104 }
 105
 106 static void gfs2_glock_dealloc(struct rcu_head *rcu)
 107 {
 108         struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu);
 109
 110         if (gl->gl_ops->go_flags & GLOF_ASPACE)
 111                 kmem_cache_free(gfs2_glock_aspace_cachep, gl);
 112         else
 113                 kmem_cache_free(gfs2_glock_cachep, gl);
 114 }
 115
 116 void gfs2_glock_free(struct gfs2_glock *gl)
 117 {
 118         struct gfs2_sbd *sdp = gl->gl_sbd;
 119
 120         call_rcu(&gl->gl_rcu, gfs2_glock_dealloc);
 121         if (atomic_dec_and_test(&sdp->sd_glock_disposal))
 122                 wake_up(&sdp->sd_glock_wait);
 123 }
 124
 125 /**
 126  * gfs2_glock_hold() - increment reference count on glock
 127  * @gl: The glock to hold
 128  *
 129  */
 130
 131 void gfs2_glock_hold(struct gfs2_glock *gl)
 132 {
 133         GLOCK_BUG_ON(gl, atomic_read(&gl->gl_ref) == 0);
 134         atomic_inc(&gl->gl_ref);
 135 }
 136
 137 /**
 138  * demote_ok - Check to see if it's ok to unlock a glock
 139  * @gl: the glock
 140  *
 141  * Returns: 1 if it's ok
 142  */
 143
 144 static int demote_ok(const struct gfs2_glock *gl)
 145 {
 146         const struct gfs2_glock_operations *glops = gl->gl_ops;
 147
 148         if (gl->gl_state == LM_ST_UNLOCKED)
 149                 return 0;
 150         if (!list_empty(&gl->gl_holders))
 151                 return 0;
 152         if (glops->go_demote_ok)
 153                 return glops->go_demote_ok(gl);
 154         return 1;
 155 }
 156
 157
 158 void gfs2_glock_add_to_lru(struct gfs2_glock *gl)
 159 {
 160         spin_lock(&lru_lock);
 161
 162         if (!list_empty(&gl->gl_lru))
 163                 list_del_init(&gl->gl_lru);
 164         else
 165                 atomic_inc(&lru_count);
 166
 167         list_add_tail(&gl->gl_lru, &lru_list);
 168         set_bit(GLF_LRU, &gl->gl_flags);
 169         spin_unlock(&lru_lock);
 170 }
 171
 172 static void __gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
 173 {
 174         if (!list_empty(&gl->gl_lru)) {
 175                 list_del_init(&gl->gl_lru);
 176                 atomic_dec(&lru_count);
 177                 clear_bit(GLF_LRU, &gl->gl_flags);
 178         }
 179 }
 180
 181 static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
 182 {
 183         spin_lock(&lru_lock);
 184         __gfs2_glock_remove_from_lru(gl);
 185         spin_unlock(&lru_lock);
 186 }
 187
 188 /**
 189  * __gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
 190  * @gl: the glock
 191  *
 192  * If the glock is demotable, then we add it (or move it) to the end
 193  * of the glock LRU list.
 194  */
 195
 196 static void __gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
 197 {
 198         if (demote_ok(gl))
 199                 gfs2_glock_add_to_lru(gl);
 200 }
 201
 202 /**
 203  * gfs2_glock_put_nolock() - Decrement reference count on glock
 204  * @gl: The glock to put
 205  *
 206  * This function should only be used if the caller has its own reference
 207  * to the glock, in addition to the one it is dropping.
 208  */
 209
 210 void gfs2_glock_put_nolock(struct gfs2_glock *gl)
 211 {
 212         if (atomic_dec_and_test(&gl->gl_ref))
 213                 GLOCK_BUG_ON(gl, 1);
 214 }
 215
 216 /**
 217  * gfs2_glock_put() - Decrement reference count on glock
 218  * @gl: The glock to put
 219  *
 220  */
 221
 222 void gfs2_glock_put(struct gfs2_glock *gl)
 223 {
 224         struct gfs2_sbd *sdp = gl->gl_sbd;
 225         struct address_space *mapping = gfs2_glock2aspace(gl);
 226
 227         if (atomic_dec_and_lock(&gl->gl_ref, &lru_lock)) {
 228                 __gfs2_glock_remove_from_lru(gl);
 229                 spin_unlock(&lru_lock);
 230                 spin_lock_bucket(gl->gl_hash);
 231                 hlist_bl_del_rcu(&gl->gl_list);
 232                 spin_unlock_bucket(gl->gl_hash);
 233                 GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
 234                 GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
 235                 trace_gfs2_glock_put(gl);
 236                 sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
 237         }
 238 }
 239
 240 /**
 241  * search_bucket() - Find struct gfs2_glock by lock number
 242  * @bucket: the bucket to search
 243  * @name: The lock name
 244  *
 245  * Returns: NULL, or the struct gfs2_glock with the requested number
 246  */
 247
 248 static struct gfs2_glock *search_bucket(unsigned int hash,
 249                                         const struct gfs2_sbd *sdp,
 250                                         const struct lm_lockname *name)
 251 {
 252         struct gfs2_glock *gl;
 253         struct hlist_bl_node *h;
 254
 255         hlist_bl_for_each_entry_rcu(gl, h, &gl_hash_table[hash], gl_list) {
 256                 if (!lm_name_equal(&gl->gl_name, name))
 257                         continue;
 258                 if (gl->gl_sbd != sdp)
 259                         continue;
 260                 if (atomic_inc_not_zero(&gl->gl_ref))
 261                         return gl;
 262         }
 263
 264         return NULL;
 265 }
 266
 267 /**
 268  * may_grant - check if its ok to grant a new lock
 269  * @gl: The glock
 270  * @gh: The lock request which we wish to grant
 271  *
 272  * Returns: true if its ok to grant the lock
 273  */
 274
 275 static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
 276 {
 277         const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
 278         if ((gh->gh_state == LM_ST_EXCLUSIVE ||
 279              gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
 280                 return 0;
 281         if (gl->gl_state == gh->gh_state)
 282                 return 1;
 283         if (gh->gh_flags & GL_EXACT)
 284                 return 0;
 285         if (gl->gl_state == LM_ST_EXCLUSIVE) {
 286                 if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
 287                         return 1;
 288                 if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
 289                         return 1;
 290         }
 291         if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
 292                 return 1;
 293         return 0;
 294 }
 295
 296 static void gfs2_holder_wake(struct gfs2_holder *gh)
 297 {
 298         clear_bit(HIF_WAIT, &gh->gh_iflags);
 299         smp_mb__after_clear_bit();
 300         wake_up_bit(&gh->gh_iflags, HIF_WAIT);
 301 }
 302
 303 /**
 304  * do_error - Something unexpected has happened during a lock request
 305  *
 306  */
 307
 308 static inline void do_error(struct gfs2_glock *gl, const int ret)
 309 {
 310         struct gfs2_holder *gh, *tmp;
 311
 312         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 313                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 314                         continue;
 315                 if (ret & LM_OUT_ERROR)
 316                         gh->gh_error = -EIO;
 317                 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
 318                         gh->gh_error = GLR_TRYFAILED;
 319                 else
 320                         continue;
 321                 list_del_init(&gh->gh_list);
 322                 trace_gfs2_glock_queue(gh, 0);
 323                 gfs2_holder_wake(gh);
 324         }
 325 }
 326
 327 /**
 328  * do_promote - promote as many requests as possible on the current queue
 329  * @gl: The glock
 330  *
 331  * Returns: 1 if there is a blocked holder at the head of the list, or 2
 332  *          if a type specific operation is underway.
 333  */
 334
 335 static int do_promote(struct gfs2_glock *gl)
 336 __releases(&gl->gl_spin)
 337 __acquires(&gl->gl_spin)
 338 {
 339         const struct gfs2_glock_operations *glops = gl->gl_ops;
 340         struct gfs2_holder *gh, *tmp;
 341         int ret;
 342
 343 restart:
 344         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 345                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 346                         continue;
 347                 if (may_grant(gl, gh)) {
 348                         if (gh->gh_list.prev == &gl->gl_holders &&
 349                             glops->go_lock) {
 350                                 spin_unlock(&gl->gl_spin);
 351                                 /* FIXME: eliminate this eventually */
 352                                 ret = glops->go_lock(gh);
 353                                 spin_lock(&gl->gl_spin);
 354                                 if (ret) {
 355                                         if (ret == 1)
 356                                                 return 2;
 357                                         gh->gh_error = ret;
 358                                         list_del_init(&gh->gh_list);
 359                                         trace_gfs2_glock_queue(gh, 0);
 360                                         gfs2_holder_wake(gh);
 361                                         goto restart;
 362                                 }
 363                                 set_bit(HIF_HOLDER, &gh->gh_iflags);
 364                                 trace_gfs2_promote(gh, 1);
 365                                 gfs2_holder_wake(gh);
 366                                 goto restart;
 367                         }
 368                         set_bit(HIF_HOLDER, &gh->gh_iflags);
 369                         trace_gfs2_promote(gh, 0);
 370                         gfs2_holder_wake(gh);
 371                         continue;
 372                 }
 373                 if (gh->gh_list.prev == &gl->gl_holders)
 374                         return 1;
 375                 do_error(gl, 0);
 376                 break;
 377         }
 378         return 0;
 379 }
 380
 381 /**
 382  * find_first_waiter - find the first gh that's waiting for the glock
 383  * @gl: the glock
 384  */
 385
 386 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
 387 {
 388         struct gfs2_holder *gh;
 389
 390         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
 391                 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
 392                         return gh;
 393         }
 394         return NULL;
 395 }
 396
 397 /**
 398  * state_change - record that the glock is now in a different state
 399  * @gl: the glock
 400  * @new_state the new state
 401  *
 402  */
 403
 404 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 405 {
 406         int held1, held2;
 407
 408         held1 = (gl->gl_state != LM_ST_UNLOCKED);
 409         held2 = (new_state != LM_ST_UNLOCKED);
 410
 411         if (held1 != held2) {
 412                 if (held2)
 413                         gfs2_glock_hold(gl);
 414                 else
 415                         gfs2_glock_put_nolock(gl);
 416         }
 417         if (held1 && held2 && list_empty(&gl->gl_holders))
 418                 clear_bit(GLF_QUEUED, &gl->gl_flags);
 419
 420         if (new_state != gl->gl_target)
 421                 /* shorten our minimum hold time */
 422                 gl->gl_hold_time = max(gl->gl_hold_time - GL_GLOCK_HOLD_DECR,
 423                                        GL_GLOCK_MIN_HOLD);
 424         gl->gl_state = new_state;
 425         gl->gl_tchange = jiffies;
 426 }
 427
 428 static void gfs2_demote_wake(struct gfs2_glock *gl)
 429 {
 430         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 431         clear_bit(GLF_DEMOTE, &gl->gl_flags);
 432         smp_mb__after_clear_bit();
 433         wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
 434 }
 435
 436 /**
 437  * finish_xmote - The DLM has replied to one of our lock requests
 438  * @gl: The glock
 439  * @ret: The status from the DLM
 440  *
 441  */
 442
 443 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
 444 {
 445         const struct gfs2_glock_operations *glops = gl->gl_ops;
 446         struct gfs2_holder *gh;
 447         unsigned state = ret & LM_OUT_ST_MASK;
 448         int rv;
 449
 450         spin_lock(&gl->gl_spin);
 451         trace_gfs2_glock_state_change(gl, state);
 452         state_change(gl, state);
 453         gh = find_first_waiter(gl);
 454
 455         /* Demote to UN request arrived during demote to SH or DF */
 456         if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
 457             state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
 458                 gl->gl_target = LM_ST_UNLOCKED;
 459
 460         /* Check for state != intended state */
 461         if (unlikely(state != gl->gl_target)) {
 462                 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
 463                         /* move to back of queue and try next entry */
 464                         if (ret & LM_OUT_CANCELED) {
 465                                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
 466                                         list_move_tail(&gh->gh_list, &gl->gl_holders);
 467                                 gh = find_first_waiter(gl);
 468                                 gl->gl_target = gh->gh_state;
 469                                 goto retry;
 470                         }
 471                         /* Some error or failed "try lock" - report it */
 472                         if ((ret & LM_OUT_ERROR) ||
 473                             (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 474                                 gl->gl_target = gl->gl_state;
 475                                 do_error(gl, ret);
 476                                 goto out;
 477                         }
 478                 }
 479                 switch(state) {
 480                 /* Unlocked due to conversion deadlock, try again */
 481                 case LM_ST_UNLOCKED:
 482 retry:
 483                         do_xmote(gl, gh, gl->gl_target);
 484                         break;
 485                 /* Conversion fails, unlock and try again */
 486                 case LM_ST_SHARED:
 487                 case LM_ST_DEFERRED:
 488                         do_xmote(gl, gh, LM_ST_UNLOCKED);
 489                         break;
 490                 default: /* Everything else */
 491                         printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
 492                         GLOCK_BUG_ON(gl, 1);
 493                 }
 494                 spin_unlock(&gl->gl_spin);
 495                 return;
 496         }
 497
 498         /* Fast path - we got what we asked for */
 499         if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
 500                 gfs2_demote_wake(gl);
 501         if (state != LM_ST_UNLOCKED) {
 502                 if (glops->go_xmote_bh) {
 503                         spin_unlock(&gl->gl_spin);
 504                         rv = glops->go_xmote_bh(gl, gh);
 505                         spin_lock(&gl->gl_spin);
 506                         if (rv) {
 507                                 do_error(gl, rv);
 508                                 goto out;
 509                         }
 510                 }
 511                 rv = do_promote(gl);
 512                 if (rv == 2)
 513                         goto out_locked;
 514         }
 515 out:
 516         clear_bit(GLF_LOCK, &gl->gl_flags);
 517 out_locked:
 518         spin_unlock(&gl->gl_spin);
 519 }
 520
 521 /**
 522  * do_xmote - Calls the DLM to change the state of a lock
 523  * @gl: The lock state
 524  * @gh: The holder (only for promotes)
 525  * @target: The target lock state
 526  *
 527  */
 528
 529 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
 530 __releases(&gl->gl_spin)
 531 __acquires(&gl->gl_spin)
 532 {
 533         const struct gfs2_glock_operations *glops = gl->gl_ops;
 534         struct gfs2_sbd *sdp = gl->gl_sbd;
 535         unsigned int lck_flags = gh ? gh->gh_flags : 0;
 536         int ret;
 537
 538         lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
 539                       LM_FLAG_PRIORITY);
 540         GLOCK_BUG_ON(gl, gl->gl_state == target);
 541         GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
 542         if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
 543             glops->go_inval) {
 544                 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 545                 do_error(gl, 0); /* Fail queued try locks */
 546         }
 547         gl->gl_req = target;
 548         set_bit(GLF_BLOCKING, &gl->gl_flags);
 549         if ((gl->gl_req == LM_ST_UNLOCKED) ||
 550             (gl->gl_state == LM_ST_EXCLUSIVE) ||
 551             (lck_flags & (LM_FLAG_TRY|LM_FLAG_TRY_1CB)))
 552                 clear_bit(GLF_BLOCKING, &gl->gl_flags);
 553         spin_unlock(&gl->gl_spin);
 554         if (glops->go_xmote_th)
 555                 glops->go_xmote_th(gl);
 556         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 557                 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
 558         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 559
 560         gfs2_glock_hold(gl);
 561         if (sdp->sd_lockstruct.ls_ops->lm_lock) {
 562                 /* lock_dlm */
 563                 ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
 564                 GLOCK_BUG_ON(gl, ret);
 565         } else { /* lock_nolock */
 566                 finish_xmote(gl, target);
 567                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 568                         gfs2_glock_put(gl);
 569         }
 570
 571         spin_lock(&gl->gl_spin);
 572 }
 573
 574 /**
 575  * find_first_holder - find the first "holder" gh
 576  * @gl: the glock
 577  */
 578
 579 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
 580 {
 581         struct gfs2_holder *gh;
 582
 583         if (!list_empty(&gl->gl_holders)) {
 584                 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 585                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 586                         return gh;
 587         }
 588         return NULL;
 589 }
 590
 591 /**
 592  * run_queue - do all outstanding tasks related to a glock
 593  * @gl: The glock in question
 594  * @nonblock: True if we must not block in run_queue
 595  *
 596  */
 597
 598 static void run_queue(struct gfs2_glock *gl, const int nonblock)
 599 __releases(&gl->gl_spin)
 600 __acquires(&gl->gl_spin)
 601 {
 602         struct gfs2_holder *gh = NULL;
 603         int ret;
 604
 605         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 606                 return;
 607
 608         GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
 609
 610         if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
 611             gl->gl_demote_state != gl->gl_state) {
 612                 if (find_first_holder(gl))
 613                         goto out_unlock;
 614                 if (nonblock)
 615                         goto out_sched;
 616                 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
 617                 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
 618                 gl->gl_target = gl->gl_demote_state;
 619         } else {
 620                 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
 621                         gfs2_demote_wake(gl);
 622                 ret = do_promote(gl);
 623                 if (ret == 0)
 624                         goto out_unlock;
 625                 if (ret == 2)
 626                         goto out;
 627                 gh = find_first_waiter(gl);
 628                 gl->gl_target = gh->gh_state;
 629                 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 630                         do_error(gl, 0); /* Fail queued try locks */
 631         }
 632         do_xmote(gl, gh, gl->gl_target);
 633 out:
 634         return;
 635
 636 out_sched:
 637         clear_bit(GLF_LOCK, &gl->gl_flags);
 638         smp_mb__after_clear_bit();
 639         gfs2_glock_hold(gl);
 640         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 641                 gfs2_glock_put_nolock(gl);
 642         return;
 643
 644 out_unlock:
 645         clear_bit(GLF_LOCK, &gl->gl_flags);
 646         smp_mb__after_clear_bit();
 647         return;
 648 }
 649
 650 static void delete_work_func(struct work_struct *work)
 651 {
 652         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
 653         struct gfs2_sbd *sdp = gl->gl_sbd;
 654         struct gfs2_inode *ip;
 655         struct inode *inode;
 656         u64 no_addr = gl->gl_name.ln_number;
 657
 658         ip = gl->gl_object;
 659         /* Note: Unsafe to dereference ip as we don't hold right refs/locks */
 660
 661         if (ip)
 662                 inode = gfs2_ilookup(sdp->sd_vfs, no_addr, 1);
 663         else
 664                 inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
 665         if (inode && !IS_ERR(inode)) {
 666                 d_prune_aliases(inode);
 667                 iput(inode);
 668         }
 669         gfs2_glock_put(gl);
 670 }
 671
 672 static void glock_work_func(struct work_struct *work)
 673 {
 674         unsigned long delay = 0;
 675         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
 676         int drop_ref = 0;
 677
 678         if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
 679                 finish_xmote(gl, gl->gl_reply);
 680                 drop_ref = 1;
 681         }
 682         spin_lock(&gl->gl_spin);
 683         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
 684             gl->gl_state != LM_ST_UNLOCKED &&
 685             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
 686                 unsigned long holdtime, now = jiffies;
 687
 688                 holdtime = gl->gl_tchange + gl->gl_hold_time;
 689                 if (time_before(now, holdtime))
 690                         delay = holdtime - now;
 691
 692                 if (!delay) {
 693                         clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
 694                         set_bit(GLF_DEMOTE, &gl->gl_flags);
 695                 }
 696         }
 697         run_queue(gl, 0);
 698         spin_unlock(&gl->gl_spin);
 699         if (!delay)
 700                 gfs2_glock_put(gl);
 701         else {
 702                 if (gl->gl_name.ln_type != LM_TYPE_INODE)
 703                         delay = 0;
 704                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
 705                         gfs2_glock_put(gl);
 706         }
 707         if (drop_ref)
 708                 gfs2_glock_put(gl);
 709 }
 710
 711 /**
 712  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
 713  * @sdp: The GFS2 superblock
 714  * @number: the lock number
 715  * @glops: The glock_operations to use
 716  * @create: If 0, don't create the glock if it doesn't exist
 717  * @glp: the glock is returned here
 718  *
 719  * This does not lock a glock, just finds/creates structures for one.
 720  *
 721  * Returns: errno
 722  */
 723
 724 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 725                    const struct gfs2_glock_operations *glops, int create,
 726                    struct gfs2_glock **glp)
 727 {
 728         struct super_block *s = sdp->sd_vfs;
 729         struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
 730         struct gfs2_glock *gl, *tmp;
 731         unsigned int hash = gl_hash(sdp, &name);
 732         struct address_space *mapping;
 733         struct kmem_cache *cachep;
 734
 735         rcu_read_lock();
 736         gl = search_bucket(hash, sdp, &name);
 737         rcu_read_unlock();
 738
 739         *glp = gl;
 740         if (gl)
 741                 return 0;
 742         if (!create)
 743                 return -ENOENT;
 744
 745         if (glops->go_flags & GLOF_ASPACE)
 746                 cachep = gfs2_glock_aspace_cachep;
 747         else
 748                 cachep = gfs2_glock_cachep;
 749         gl = kmem_cache_alloc(cachep, GFP_KERNEL);
 750         if (!gl)
 751                 return -ENOMEM;
 752
 753         atomic_inc(&sdp->sd_glock_disposal);
 754         gl->gl_sbd = sdp;
 755         gl->gl_flags = 0;
 756         gl->gl_name = name;
 757         atomic_set(&gl->gl_ref, 1);
 758         gl->gl_state = LM_ST_UNLOCKED;
 759         gl->gl_target = LM_ST_UNLOCKED;
 760         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 761         gl->gl_hash = hash;
 762         gl->gl_ops = glops;
 763         gl->gl_dstamp = ktime_set(0, 0);
 764         preempt_disable();
 765         /* We use the global stats to estimate the initial per-glock stats */
 766         gl->gl_stats = this_cpu_ptr(sdp->sd_lkstats)->lkstats[glops->go_type];
 767         preempt_enable();
 768         gl->gl_stats.stats[GFS2_LKS_DCOUNT] = 0;
 769         gl->gl_stats.stats[GFS2_LKS_QCOUNT] = 0;
 770         memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
 771         memset(gl->gl_lvb, 0, 32 * sizeof(char));
 772         gl->gl_lksb.sb_lvbptr = gl->gl_lvb;
 773         gl->gl_tchange = jiffies;
 774         gl->gl_object = NULL;
 775         gl->gl_hold_time = GL_GLOCK_DFT_HOLD;
 776         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
 777         INIT_WORK(&gl->gl_delete, delete_work_func);
 778
 779         mapping = gfs2_glock2aspace(gl);
 780         if (mapping) {
 781                 mapping->a_ops = &gfs2_meta_aops;
 782                 mapping->host = s->s_bdev->bd_inode;
 783                 mapping->flags = 0;
 784                 mapping_set_gfp_mask(mapping, GFP_NOFS);
 785                 mapping->assoc_mapping = NULL;
 786                 mapping->backing_dev_info = s->s_bdi;
 787                 mapping->writeback_index = 0;
 788         }
 789
 790         spin_lock_bucket(hash);
 791         tmp = search_bucket(hash, sdp, &name);
 792         if (tmp) {
 793                 spin_unlock_bucket(hash);
 794                 kmem_cache_free(cachep, gl);
 795                 atomic_dec(&sdp->sd_glock_disposal);
 796                 gl = tmp;
 797         } else {
 798                 hlist_bl_add_head_rcu(&gl->gl_list, &gl_hash_table[hash]);
 799                 spin_unlock_bucket(hash);
 800         }
 801
 802         *glp = gl;
 803
 804         return 0;
 805 }
 806
 807 /**
 808  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
 809  * @gl: the glock
 810  * @state: the state we're requesting
 811  * @flags: the modifier flags
 812  * @gh: the holder structure
 813  *
 814  */
 815
 816 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
 817                       struct gfs2_holder *gh)
 818 {
 819         INIT_LIST_HEAD(&gh->gh_list);
 820         gh->gh_gl = gl;
 821         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 822         gh->gh_owner_pid = get_pid(task_pid(current));
 823         gh->gh_state = state;
 824         gh->gh_flags = flags;
 825         gh->gh_error = 0;
 826         gh->gh_iflags = 0;
 827         gfs2_glock_hold(gl);
 828 }
 829
 830 /**
 831  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
 832  * @state: the state we're requesting
 833  * @flags: the modifier flags
 834  * @gh: the holder structure
 835  *
 836  * Don't mess with the glock.
 837  *
 838  */
 839
 840 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
 841 {
 842         gh->gh_state = state;
 843         gh->gh_flags = flags;
 844         gh->gh_iflags = 0;
 845         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 846         if (gh->gh_owner_pid)
 847                 put_pid(gh->gh_owner_pid);
 848         gh->gh_owner_pid = get_pid(task_pid(current));
 849 }
 850
 851 /**
 852  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 853  * @gh: the holder structure
 854  *
 855  */
 856
 857 void gfs2_holder_uninit(struct gfs2_holder *gh)
 858 {
 859         put_pid(gh->gh_owner_pid);
 860         gfs2_glock_put(gh->gh_gl);
 861         gh->gh_gl = NULL;
 862         gh->gh_ip = 0;
 863 }
 864
 865 /**
 866  * gfs2_glock_holder_wait
 867  * @word: unused
 868  *
 869  * This function and gfs2_glock_demote_wait both show up in the WCHAN
 870  * field. Thus I've separated these otherwise identical functions in
 871  * order to be more informative to the user.
 872  */
 873
 874 static int gfs2_glock_holder_wait(void *word)
 875 {
 876         schedule();
 877         return 0;
 878 }
 879
 880 static int gfs2_glock_demote_wait(void *word)
 881 {
 882         schedule();
 883         return 0;
 884 }
 885
 886 static void wait_on_holder(struct gfs2_holder *gh)
 887 {
 888         unsigned long time1 = jiffies;
 889
 890         might_sleep();
 891         wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
 892         if (time_after(jiffies, time1 + HZ)) /* have we waited > a second? */
 893                 /* Lengthen the minimum hold time. */
 894                 gh->gh_gl->gl_hold_time = min(gh->gh_gl->gl_hold_time +
 895                                               GL_GLOCK_HOLD_INCR,
 896                                               GL_GLOCK_MAX_HOLD);
 897 }
 898
 899 static void wait_on_demote(struct gfs2_glock *gl)
 900 {
 901         might_sleep();
 902         wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
 903 }
 904
 905 /**
 906  * handle_callback - process a demote request
 907  * @gl: the glock
 908  * @state: the state the caller wants us to change to
 909  *
 910  * There are only two requests that we are going to see in actual
 911  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
 912  */
 913
 914 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
 915                             unsigned long delay)
 916 {
 917         int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
 918
 919         set_bit(bit, &gl->gl_flags);
 920         if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
 921                 gl->gl_demote_state = state;
 922                 gl->gl_demote_time = jiffies;
 923         } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
 924                         gl->gl_demote_state != state) {
 925                 gl->gl_demote_state = LM_ST_UNLOCKED;
 926         }
 927         if (gl->gl_ops->go_callback)
 928                 gl->gl_ops->go_callback(gl);
 929         trace_gfs2_demote_rq(gl);
 930 }
 931
 932 /**
 933  * gfs2_glock_wait - wait on a glock acquisition
 934  * @gh: the glock holder
 935  *
 936  * Returns: 0 on success
 937  */
 938
 939 int gfs2_glock_wait(struct gfs2_holder *gh)
 940 {
 941         wait_on_holder(gh);
 942         return gh->gh_error;
 943 }
 944
 945 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
 946 {
 947         struct va_format vaf;
 948         va_list args;
 949
 950         va_start(args, fmt);
 951
 952         if (seq) {
 953                 seq_vprintf(seq, fmt, args);
 954         } else {
 955                 vaf.fmt = fmt;
 956                 vaf.va = &args;
 957
 958                 printk(KERN_ERR " %pV", &vaf);
 959         }
 960
 961         va_end(args);
 962 }
 963
 964 /**
 965  * add_to_queue - Add a holder to the wait queue (but look for recursion)
 966  * @gh: the holder structure to add
 967  *
 968  * Eventually we should move the recursive locking trap to a
 969  * debugging option or something like that. This is the fast
 970  * path and needs to have the minimum number of distractions.
 971  *
 972  */
 973
 974 static inline void add_to_queue(struct gfs2_holder *gh)
 975 __releases(&gl->gl_spin)
 976 __acquires(&gl->gl_spin)
 977 {
 978         struct gfs2_glock *gl = gh->gh_gl;
 979         struct gfs2_sbd *sdp = gl->gl_sbd;
 980         struct list_head *insert_pt = NULL;
 981         struct gfs2_holder *gh2;
 982         int try_lock = 0;
 983
 984         BUG_ON(gh->gh_owner_pid == NULL);
 985         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
 986                 BUG();
 987
 988         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
 989                 if (test_bit(GLF_LOCK, &gl->gl_flags))
 990                         try_lock = 1;
 991                 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 992                         goto fail;
 993         }
 994
 995         list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
 996                 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
 997                     (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
 998                         goto trap_recursive;
 999                 if (try_lock &&
1000                     !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
1001                     !may_grant(gl, gh)) {
1002 fail:
1003                         gh->gh_error = GLR_TRYFAILED;
1004                         gfs2_holder_wake(gh);
1005                         return;
1006                 }
1007                 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
1008                         continue;
1009                 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
1010                         insert_pt = &gh2->gh_list;
1011         }
1012         set_bit(GLF_QUEUED, &gl->gl_flags);
1013         trace_gfs2_glock_queue(gh, 1);
1014         gfs2_glstats_inc(gl, GFS2_LKS_QCOUNT);
1015         gfs2_sbstats_inc(gl, GFS2_LKS_QCOUNT);
1016         if (likely(insert_pt == NULL)) {
1017                 list_add_tail(&gh->gh_list, &gl->gl_holders);
1018                 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
1019                         goto do_cancel;
1020                 return;
1021         }
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         if (test_bit(GLF_LRU, &gl->gl_flags))
1065                 gfs2_glock_remove_from_lru(gl);
1066
1067         spin_lock(&gl->gl_spin);
1068         add_to_queue(gh);
1069         if ((LM_FLAG_NOEXP & gh->gh_flags) &&
1070             test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1071                 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1072         run_queue(gl, 1);
1073         spin_unlock(&gl->gl_spin);
1074
1075         if (!(gh->gh_flags & GL_ASYNC))
1076                 error = gfs2_glock_wait(gh);
1077
1078         return error;
1079 }
1080
1081 /**
1082  * gfs2_glock_poll - poll to see if an async request has been completed
1083  * @gh: the holder
1084  *
1085  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1086  */
1087
1088 int gfs2_glock_poll(struct gfs2_holder *gh)
1089 {
1090         return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1091 }
1092
1093 /**
1094  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1095  * @gh: the glock holder
1096  *
1097  */
1098
1099 void gfs2_glock_dq(struct gfs2_holder *gh)
1100 {
1101         struct gfs2_glock *gl = gh->gh_gl;
1102         const struct gfs2_glock_operations *glops = gl->gl_ops;
1103         unsigned delay = 0;
1104         int fast_path = 0;
1105
1106         spin_lock(&gl->gl_spin);
1107         if (gh->gh_flags & GL_NOCACHE)
1108                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1109
1110         list_del_init(&gh->gh_list);
1111         if (find_first_holder(gl) == NULL) {
1112                 if (glops->go_unlock) {
1113                         GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1114                         spin_unlock(&gl->gl_spin);
1115                         glops->go_unlock(gh);
1116                         spin_lock(&gl->gl_spin);
1117                         clear_bit(GLF_LOCK, &gl->gl_flags);
1118                 }
1119                 if (list_empty(&gl->gl_holders) &&
1120                     !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1121                     !test_bit(GLF_DEMOTE, &gl->gl_flags))
1122                         fast_path = 1;
1123         }
1124         if (!test_bit(GLF_LFLUSH, &gl->gl_flags))
1125                 __gfs2_glock_schedule_for_reclaim(gl);
1126         trace_gfs2_glock_queue(gh, 0);
1127         spin_unlock(&gl->gl_spin);
1128         if (likely(fast_path))
1129                 return;
1130
1131         gfs2_glock_hold(gl);
1132         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1133             !test_bit(GLF_DEMOTE, &gl->gl_flags) &&
1134             gl->gl_name.ln_type == LM_TYPE_INODE)
1135                 delay = gl->gl_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 acquisition
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         while (num_gh--)
1291                 gfs2_glock_dq(&ghs[num_gh]);
1292 }
1293
1294 /**
1295  * gfs2_glock_dq_uninit_m - release multiple glocks
1296  * @num_gh: the number of structures
1297  * @ghs: an array of struct gfs2_holder structures
1298  *
1299  */
1300
1301 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1302 {
1303         while (num_gh--)
1304                 gfs2_glock_dq_uninit(&ghs[num_gh]);
1305 }
1306
1307 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1308 {
1309         unsigned long delay = 0;
1310         unsigned long holdtime;
1311         unsigned long now = jiffies;
1312
1313         gfs2_glock_hold(gl);
1314         holdtime = gl->gl_tchange + gl->gl_hold_time;
1315         if (test_bit(GLF_QUEUED, &gl->gl_flags) &&
1316             gl->gl_name.ln_type == LM_TYPE_INODE) {
1317                 if (time_before(now, holdtime))
1318                         delay = holdtime - now;
1319                 if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1320                         delay = gl->gl_hold_time;
1321         }
1322
1323         spin_lock(&gl->gl_spin);
1324         handle_callback(gl, state, delay);
1325         spin_unlock(&gl->gl_spin);
1326         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1327                 gfs2_glock_put(gl);
1328 }
1329
1330 /**
1331  * gfs2_should_freeze - Figure out if glock should be frozen
1332  * @gl: The glock in question
1333  *
1334  * Glocks are not frozen if (a) the result of the dlm operation is
1335  * an error, (b) the locking operation was an unlock operation or
1336  * (c) if there is a "noexp" flagged request anywhere in the queue
1337  *
1338  * Returns: 1 if freezing should occur, 0 otherwise
1339  */
1340
1341 static int gfs2_should_freeze(const struct gfs2_glock *gl)
1342 {
1343         const struct gfs2_holder *gh;
1344
1345         if (gl->gl_reply & ~LM_OUT_ST_MASK)
1346                 return 0;
1347         if (gl->gl_target == LM_ST_UNLOCKED)
1348                 return 0;
1349
1350         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1351                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1352                         continue;
1353                 if (LM_FLAG_NOEXP & gh->gh_flags)
1354                         return 0;
1355         }
1356
1357         return 1;
1358 }
1359
1360 /**
1361  * gfs2_glock_complete - Callback used by locking
1362  * @gl: Pointer to the glock
1363  * @ret: The return value from the dlm
1364  *
1365  * The gl_reply field is under the gl_spin lock so that it is ok
1366  * to use a bitfield shared with other glock state fields.
1367  */
1368
1369 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1370 {
1371         struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
1372
1373         spin_lock(&gl->gl_spin);
1374         gl->gl_reply = ret;
1375
1376         if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags))) {
1377                 if (gfs2_should_freeze(gl)) {
1378                         set_bit(GLF_FROZEN, &gl->gl_flags);
1379                         spin_unlock(&gl->gl_spin);
1380                         return;
1381                 }
1382         }
1383
1384         spin_unlock(&gl->gl_spin);
1385         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1386         smp_wmb();
1387         gfs2_glock_hold(gl);
1388         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1389                 gfs2_glock_put(gl);
1390 }
1391
1392
1393 static int gfs2_shrink_glock_memory(struct shrinker *shrink,
1394                                     struct shrink_control *sc)
1395 {
1396         struct gfs2_glock *gl;
1397         int may_demote;
1398         int nr_skipped = 0;
1399         int nr = sc->nr_to_scan;
1400         gfp_t gfp_mask = sc->gfp_mask;
1401         LIST_HEAD(skipped);
1402
1403         if (nr == 0)
1404                 goto out;
1405
1406         if (!(gfp_mask & __GFP_FS))
1407                 return -1;
1408
1409         spin_lock(&lru_lock);
1410         while(nr && !list_empty(&lru_list)) {
1411                 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1412                 list_del_init(&gl->gl_lru);
1413                 clear_bit(GLF_LRU, &gl->gl_flags);
1414                 atomic_dec(&lru_count);
1415
1416                 /* Test for being demotable */
1417                 if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1418                         gfs2_glock_hold(gl);
1419                         spin_unlock(&lru_lock);
1420                         spin_lock(&gl->gl_spin);
1421                         may_demote = demote_ok(gl);
1422                         if (may_demote) {
1423                                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1424                                 nr--;
1425                         }
1426                         clear_bit(GLF_LOCK, &gl->gl_flags);
1427                         smp_mb__after_clear_bit();
1428                         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1429                                 gfs2_glock_put_nolock(gl);
1430                         spin_unlock(&gl->gl_spin);
1431                         spin_lock(&lru_lock);
1432                         continue;
1433                 }
1434                 nr_skipped++;
1435                 list_add(&gl->gl_lru, &skipped);
1436                 set_bit(GLF_LRU, &gl->gl_flags);
1437         }
1438         list_splice(&skipped, &lru_list);
1439         atomic_add(nr_skipped, &lru_count);
1440         spin_unlock(&lru_lock);
1441 out:
1442         return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
1443 }
1444
1445 static struct shrinker glock_shrinker = {
1446         .shrink = gfs2_shrink_glock_memory,
1447         .seeks = DEFAULT_SEEKS,
1448 };
1449
1450 /**
1451  * examine_bucket - Call a function for glock in a hash bucket
1452  * @examiner: the function
1453  * @sdp: the filesystem
1454  * @bucket: the bucket
1455  *
1456  */
1457
1458 static void examine_bucket(glock_examiner examiner, const struct gfs2_sbd *sdp,
1459                           unsigned int hash)
1460 {
1461         struct gfs2_glock *gl;
1462         struct hlist_bl_head *head = &gl_hash_table[hash];
1463         struct hlist_bl_node *pos;
1464
1465         rcu_read_lock();
1466         hlist_bl_for_each_entry_rcu(gl, pos, head, gl_list) {
1467                 if ((gl->gl_sbd == sdp) && atomic_read(&gl->gl_ref))
1468                         examiner(gl);
1469         }
1470         rcu_read_unlock();
1471         cond_resched();
1472 }
1473
1474 static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
1475 {
1476         unsigned x;
1477
1478         for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1479                 examine_bucket(examiner, sdp, x);
1480 }
1481
1482
1483 /**
1484  * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1485  * @gl: The glock to thaw
1486  *
1487  * N.B. When we freeze a glock, we leave a ref to the glock outstanding,
1488  * so this has to result in the ref count being dropped by one.
1489  */
1490
1491 static void thaw_glock(struct gfs2_glock *gl)
1492 {
1493         if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1494                 return;
1495         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1496         gfs2_glock_hold(gl);
1497         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1498                 gfs2_glock_put(gl);
1499 }
1500
1501 /**
1502  * clear_glock - look at a glock and see if we can free it from glock cache
1503  * @gl: the glock to look at
1504  *
1505  */
1506
1507 static void clear_glock(struct gfs2_glock *gl)
1508 {
1509         gfs2_glock_remove_from_lru(gl);
1510
1511         spin_lock(&gl->gl_spin);
1512         if (gl->gl_state != LM_ST_UNLOCKED)
1513                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1514         spin_unlock(&gl->gl_spin);
1515         gfs2_glock_hold(gl);
1516         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1517                 gfs2_glock_put(gl);
1518 }
1519
1520 /**
1521  * gfs2_glock_thaw - Thaw any frozen glocks
1522  * @sdp: The super block
1523  *
1524  */
1525
1526 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1527 {
1528         glock_hash_walk(thaw_glock, sdp);
1529 }
1530
1531 static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1532 {
1533         int ret;
1534         spin_lock(&gl->gl_spin);
1535         ret = __dump_glock(seq, gl);
1536         spin_unlock(&gl->gl_spin);
1537         return ret;
1538 }
1539
1540 static void dump_glock_func(struct gfs2_glock *gl)
1541 {
1542         dump_glock(NULL, gl);
1543 }
1544
1545 /**
1546  * gfs2_gl_hash_clear - Empty out the glock hash table
1547  * @sdp: the filesystem
1548  * @wait: wait until it's all gone
1549  *
1550  * Called when unmounting the filesystem.
1551  */
1552
1553 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1554 {
1555         glock_hash_walk(clear_glock, sdp);
1556         flush_workqueue(glock_workqueue);
1557         wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
1558         glock_hash_walk(dump_glock_func, sdp);
1559 }
1560
1561 void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1562 {
1563         struct gfs2_glock *gl = ip->i_gl;
1564         int ret;
1565
1566         ret = gfs2_truncatei_resume(ip);
1567         gfs2_assert_withdraw(gl->gl_sbd, ret == 0);
1568
1569         spin_lock(&gl->gl_spin);
1570         clear_bit(GLF_LOCK, &gl->gl_flags);
1571         run_queue(gl, 1);
1572         spin_unlock(&gl->gl_spin);
1573 }
1574
1575 static const char *state2str(unsigned state)
1576 {
1577         switch(state) {
1578         case LM_ST_UNLOCKED:
1579                 return "UN";
1580         case LM_ST_SHARED:
1581                 return "SH";
1582         case LM_ST_DEFERRED:
1583                 return "DF";
1584         case LM_ST_EXCLUSIVE:
1585                 return "EX";
1586         }
1587         return "??";
1588 }
1589
1590 static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags)
1591 {
1592         char *p = buf;
1593         if (flags & LM_FLAG_TRY)
1594                 *p++ = 't';
1595         if (flags & LM_FLAG_TRY_1CB)
1596                 *p++ = 'T';
1597         if (flags & LM_FLAG_NOEXP)
1598                 *p++ = 'e';
1599         if (flags & LM_FLAG_ANY)
1600                 *p++ = 'A';
1601         if (flags & LM_FLAG_PRIORITY)
1602                 *p++ = 'p';
1603         if (flags & GL_ASYNC)
1604                 *p++ = 'a';
1605         if (flags & GL_EXACT)
1606                 *p++ = 'E';
1607         if (flags & GL_NOCACHE)
1608                 *p++ = 'c';
1609         if (test_bit(HIF_HOLDER, &iflags))
1610                 *p++ = 'H';
1611         if (test_bit(HIF_WAIT, &iflags))
1612                 *p++ = 'W';
1613         if (test_bit(HIF_FIRST, &iflags))
1614                 *p++ = 'F';
1615         *p = 0;
1616         return buf;
1617 }
1618
1619 /**
1620  * dump_holder - print information about a glock holder
1621  * @seq: the seq_file struct
1622  * @gh: the glock holder
1623  *
1624  * Returns: 0 on success, -ENOBUFS when we run out of space
1625  */
1626
1627 static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1628 {
1629         struct task_struct *gh_owner = NULL;
1630         char flags_buf[32];
1631
1632         if (gh->gh_owner_pid)
1633                 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1634         gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
1635                        state2str(gh->gh_state),
1636                        hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1637                        gh->gh_error,
1638                        gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1639                        gh_owner ? gh_owner->comm : "(ended)",
1640                        (void *)gh->gh_ip);
1641         return 0;
1642 }
1643
1644 static const char *gflags2str(char *buf, const struct gfs2_glock *gl)
1645 {
1646         const unsigned long *gflags = &gl->gl_flags;
1647         char *p = buf;
1648
1649         if (test_bit(GLF_LOCK, gflags))
1650                 *p++ = 'l';
1651         if (test_bit(GLF_DEMOTE, gflags))
1652                 *p++ = 'D';
1653         if (test_bit(GLF_PENDING_DEMOTE, gflags))
1654                 *p++ = 'd';
1655         if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1656                 *p++ = 'p';
1657         if (test_bit(GLF_DIRTY, gflags))
1658                 *p++ = 'y';
1659         if (test_bit(GLF_LFLUSH, gflags))
1660                 *p++ = 'f';
1661         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1662                 *p++ = 'i';
1663         if (test_bit(GLF_REPLY_PENDING, gflags))
1664                 *p++ = 'r';
1665         if (test_bit(GLF_INITIAL, gflags))
1666                 *p++ = 'I';
1667         if (test_bit(GLF_FROZEN, gflags))
1668                 *p++ = 'F';
1669         if (test_bit(GLF_QUEUED, gflags))
1670                 *p++ = 'q';
1671         if (test_bit(GLF_LRU, gflags))
1672                 *p++ = 'L';
1673         if (gl->gl_object)
1674                 *p++ = 'o';
1675         if (test_bit(GLF_BLOCKING, gflags))
1676                 *p++ = 'b';
1677         *p = 0;
1678         return buf;
1679 }
1680
1681 /**
1682  * __dump_glock - print information about a glock
1683  * @seq: The seq_file struct
1684  * @gl: the glock
1685  *
1686  * The file format is as follows:
1687  * One line per object, capital letters are used to indicate objects
1688  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1689  * other objects are indented by a single space and follow the glock to
1690  * which they are related. Fields are indicated by lower case letters
1691  * followed by a colon and the field value, except for strings which are in
1692  * [] so that its possible to see if they are composed of spaces for
1693  * example. The field's are n = number (id of the object), f = flags,
1694  * t = type, s = state, r = refcount, e = error, p = pid.
1695  *
1696  * Returns: 0 on success, -ENOBUFS when we run out of space
1697  */
1698
1699 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1700 {
1701         const struct gfs2_glock_operations *glops = gl->gl_ops;
1702         unsigned long long dtime;
1703         const struct gfs2_holder *gh;
1704         char gflags_buf[32];
1705         int error = 0;
1706
1707         dtime = jiffies - gl->gl_demote_time;
1708         dtime *= 1000000/HZ; /* demote time in uSec */
1709         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1710                 dtime = 0;
1711         gfs2_print_dbg(seq, "G:  s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d v:%d r:%d m:%ld\n",
1712                   state2str(gl->gl_state),
1713                   gl->gl_name.ln_type,
1714                   (unsigned long long)gl->gl_name.ln_number,
1715                   gflags2str(gflags_buf, gl),
1716                   state2str(gl->gl_target),
1717                   state2str(gl->gl_demote_state), dtime,
1718                   atomic_read(&gl->gl_ail_count),
1719                   atomic_read(&gl->gl_revokes),
1720                   atomic_read(&gl->gl_ref), gl->gl_hold_time);
1721
1722         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1723                 error = dump_holder(seq, gh);
1724                 if (error)
1725                         goto out;
1726         }
1727         if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1728                 error = glops->go_dump(seq, gl);
1729 out:
1730         return error;
1731 }
1732
1733 static int gfs2_glstats_seq_show(struct seq_file *seq, void *iter_ptr)
1734 {
1735         struct gfs2_glock *gl = iter_ptr;
1736
1737         seq_printf(seq, "G: n:%u/%llx rtt:%lld/%lld rttb:%lld/%lld irt:%lld/%lld dcnt: %lld qcnt: %lld\n",
1738                    gl->gl_name.ln_type,
1739                    (unsigned long long)gl->gl_name.ln_number,
1740                    (long long)gl->gl_stats.stats[GFS2_LKS_SRTT],
1741                    (long long)gl->gl_stats.stats[GFS2_LKS_SRTTVAR],
1742                    (long long)gl->gl_stats.stats[GFS2_LKS_SRTTB],
1743                    (long long)gl->gl_stats.stats[GFS2_LKS_SRTTVARB],
1744                    (long long)gl->gl_stats.stats[GFS2_LKS_SIRT],
1745                    (long long)gl->gl_stats.stats[GFS2_LKS_SIRTVAR],
1746                    (long long)gl->gl_stats.stats[GFS2_LKS_DCOUNT],
1747                    (long long)gl->gl_stats.stats[GFS2_LKS_QCOUNT]);
1748         return 0;
1749 }
1750
1751 static const char *gfs2_gltype[] = {
1752         "type",
1753         "reserved",
1754         "nondisk",
1755         "inode",
1756         "rgrp",
1757         "meta",
1758         "iopen",
1759         "flock",
1760         "plock",
1761         "quota",
1762         "journal",
1763 };
1764
1765 static const char *gfs2_stype[] = {
1766         [GFS2_LKS_SRTT]         = "srtt",
1767         [GFS2_LKS_SRTTVAR]      = "srttvar",
1768         [GFS2_LKS_SRTTB]        = "srttb",
1769         [GFS2_LKS_SRTTVARB]     = "srttvarb",
1770         [GFS2_LKS_SIRT]         = "sirt",
1771         [GFS2_LKS_SIRTVAR]      = "sirtvar",
1772         [GFS2_LKS_DCOUNT]       = "dlm",
1773         [GFS2_LKS_QCOUNT]       = "queue",
1774 };
1775
1776 #define GFS2_NR_SBSTATS (ARRAY_SIZE(gfs2_gltype) * ARRAY_SIZE(gfs2_stype))
1777
1778 static int gfs2_sbstats_seq_show(struct seq_file *seq, void *iter_ptr)
1779 {
1780         struct gfs2_glock_iter *gi = seq->private;
1781         struct gfs2_sbd *sdp = gi->sdp;
1782         unsigned index = gi->hash >> 3;
1783         unsigned subindex = gi->hash & 0x07;
1784         s64 value;
1785         int i;
1786
1787         if (index == 0 && subindex != 0)
1788                 return 0;
1789
1790         seq_printf(seq, "%-10s %8s:", gfs2_gltype[index],
1791                    (index == 0) ? "cpu": gfs2_stype[subindex]);
1792
1793         for_each_possible_cpu(i) {
1794                 const struct gfs2_pcpu_lkstats *lkstats = per_cpu_ptr(sdp->sd_lkstats, i);
1795                 if (index == 0) {
1796                         value = i;
1797                 } else {
1798                         value = lkstats->lkstats[index - 1].stats[subindex];
1799                 }
1800                 seq_printf(seq, " %15lld", (long long)value);
1801         }
1802         seq_putc(seq, '\n');
1803         return 0;
1804 }
1805
1806 int __init gfs2_glock_init(void)
1807 {
1808         unsigned i;
1809         for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
1810                 INIT_HLIST_BL_HEAD(&gl_hash_table[i]);
1811         }
1812
1813         glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
1814                                           WQ_HIGHPRI | WQ_FREEZABLE, 0);
1815         if (IS_ERR(glock_workqueue))
1816                 return PTR_ERR(glock_workqueue);
1817         gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
1818                                                 WQ_MEM_RECLAIM | WQ_FREEZABLE,
1819                                                 0);
1820         if (IS_ERR(gfs2_delete_workqueue)) {
1821                 destroy_workqueue(glock_workqueue);
1822                 return PTR_ERR(gfs2_delete_workqueue);
1823         }
1824
1825         register_shrinker(&glock_shrinker);
1826
1827         return 0;
1828 }
1829
1830 void gfs2_glock_exit(void)
1831 {
1832         unregister_shrinker(&glock_shrinker);
1833         destroy_workqueue(glock_workqueue);
1834         destroy_workqueue(gfs2_delete_workqueue);
1835 }
1836
1837 static inline struct gfs2_glock *glock_hash_chain(unsigned hash)
1838 {
1839         return hlist_bl_entry(hlist_bl_first_rcu(&gl_hash_table[hash]),
1840                               struct gfs2_glock, gl_list);
1841 }
1842
1843 static inline struct gfs2_glock *glock_hash_next(struct gfs2_glock *gl)
1844 {
1845         return hlist_bl_entry(rcu_dereference(gl->gl_list.next),
1846                               struct gfs2_glock, gl_list);
1847 }
1848
1849 static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1850 {
1851         struct gfs2_glock *gl;
1852
1853         do {
1854                 gl = gi->gl;
1855                 if (gl) {
1856                         gi->gl = glock_hash_next(gl);
1857                         gi->nhash++;
1858                 } else {
1859                         if (gi->hash >= GFS2_GL_HASH_SIZE) {
1860                                 rcu_read_unlock();
1861                                 return 1;
1862                         }
1863                         gi->gl = glock_hash_chain(gi->hash);
1864                         gi->nhash = 0;
1865                 }
1866                 while (gi->gl == NULL) {
1867                         gi->hash++;
1868                         if (gi->hash >= GFS2_GL_HASH_SIZE) {
1869                                 rcu_read_unlock();
1870                                 return 1;
1871                         }
1872                         gi->gl = glock_hash_chain(gi->hash);
1873                         gi->nhash = 0;
1874                 }
1875         /* Skip entries for other sb and dead entries */
1876         } while (gi->sdp != gi->gl->gl_sbd || atomic_read(&gi->gl->gl_ref) == 0);
1877
1878         return 0;
1879 }
1880
1881 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1882 {
1883         struct gfs2_glock_iter *gi = seq->private;
1884         loff_t n = *pos;
1885
1886         if (gi->last_pos <= *pos)
1887                 n = gi->nhash + (*pos - gi->last_pos);
1888         else
1889                 gi->hash = 0;
1890
1891         gi->nhash = 0;
1892         rcu_read_lock();
1893
1894         do {
1895                 if (gfs2_glock_iter_next(gi))
1896                         return NULL;
1897         } while (n--);
1898
1899         gi->last_pos = *pos;
1900         return gi->gl;
1901 }
1902
1903 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1904                                  loff_t *pos)
1905 {
1906         struct gfs2_glock_iter *gi = seq->private;
1907
1908         (*pos)++;
1909         gi->last_pos = *pos;
1910         if (gfs2_glock_iter_next(gi))
1911                 return NULL;
1912
1913         return gi->gl;
1914 }
1915
1916 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1917 {
1918         struct gfs2_glock_iter *gi = seq->private;
1919
1920         if (gi->gl)
1921                 rcu_read_unlock();
1922         gi->gl = NULL;
1923 }
1924
1925 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1926 {
1927         return dump_glock(seq, iter_ptr);
1928 }
1929
1930 static void *gfs2_sbstats_seq_start(struct seq_file *seq, loff_t *pos)
1931 {
1932         struct gfs2_glock_iter *gi = seq->private;
1933
1934         gi->hash = *pos;
1935         if (*pos >= GFS2_NR_SBSTATS)
1936                 return NULL;
1937         preempt_disable();
1938         return SEQ_START_TOKEN;
1939 }
1940
1941 static void *gfs2_sbstats_seq_next(struct seq_file *seq, void *iter_ptr,
1942                                    loff_t *pos)
1943 {
1944         struct gfs2_glock_iter *gi = seq->private;
1945         (*pos)++;
1946         gi->hash++;
1947         if (gi->hash >= GFS2_NR_SBSTATS) {
1948                 preempt_enable();
1949                 return NULL;
1950         }
1951         return SEQ_START_TOKEN;
1952 }
1953
1954 static void gfs2_sbstats_seq_stop(struct seq_file *seq, void *iter_ptr)
1955 {
1956         preempt_enable();
1957 }
1958
1959 static const struct seq_operations gfs2_glock_seq_ops = {
1960         .start = gfs2_glock_seq_start,
1961         .next  = gfs2_glock_seq_next,
1962         .stop  = gfs2_glock_seq_stop,
1963         .show  = gfs2_glock_seq_show,
1964 };
1965
1966 static const struct seq_operations gfs2_glstats_seq_ops = {
1967         .start = gfs2_glock_seq_start,
1968         .next  = gfs2_glock_seq_next,
1969         .stop  = gfs2_glock_seq_stop,
1970         .show  = gfs2_glstats_seq_show,
1971 };
1972
1973 static const struct seq_operations gfs2_sbstats_seq_ops = {
1974         .start = gfs2_sbstats_seq_start,
1975         .next  = gfs2_sbstats_seq_next,
1976         .stop  = gfs2_sbstats_seq_stop,
1977         .show  = gfs2_sbstats_seq_show,
1978 };
1979
1980 #define GFS2_SEQ_GOODSIZE min(PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER, 65536UL)
1981
1982 static int gfs2_glocks_open(struct inode *inode, struct file *file)
1983 {
1984         int ret = seq_open_private(file, &gfs2_glock_seq_ops,
1985                                    sizeof(struct gfs2_glock_iter));
1986         if (ret == 0) {
1987                 struct seq_file *seq = file->private_data;
1988                 struct gfs2_glock_iter *gi = seq->private;
1989                 gi->sdp = inode->i_private;
1990                 seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
1991                 if (seq->buf)
1992                         seq->size = GFS2_SEQ_GOODSIZE;
1993         }
1994         return ret;
1995 }
1996
1997 static int gfs2_glstats_open(struct inode *inode, struct file *file)
1998 {
1999         int ret = seq_open_private(file, &gfs2_glstats_seq_ops,
2000                                    sizeof(struct gfs2_glock_iter));
2001         if (ret == 0) {
2002                 struct seq_file *seq = file->private_data;
2003                 struct gfs2_glock_iter *gi = seq->private;
2004                 gi->sdp = inode->i_private;
2005                 seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
2006                 if (seq->buf)
2007                         seq->size = GFS2_SEQ_GOODSIZE;
2008         }
2009         return ret;
2010 }
2011
2012 static int gfs2_sbstats_open(struct inode *inode, struct file *file)
2013 {
2014         int ret = seq_open_private(file, &gfs2_sbstats_seq_ops,
2015                                    sizeof(struct gfs2_glock_iter));
2016         if (ret == 0) {
2017                 struct seq_file *seq = file->private_data;
2018                 struct gfs2_glock_iter *gi = seq->private;
2019                 gi->sdp = inode->i_private;
2020         }
2021         return ret;
2022 }
2023
2024 static const struct file_operations gfs2_glocks_fops = {
2025         .owner   = THIS_MODULE,
2026         .open    = gfs2_glocks_open,
2027         .read    = seq_read,
2028         .llseek  = seq_lseek,
2029         .release = seq_release_private,
2030 };
2031
2032 static const struct file_operations gfs2_glstats_fops = {
2033         .owner   = THIS_MODULE,
2034         .open    = gfs2_glstats_open,
2035         .read    = seq_read,
2036         .llseek  = seq_lseek,
2037         .release = seq_release_private,
2038 };
2039
2040 static const struct file_operations gfs2_sbstats_fops = {
2041         .owner   = THIS_MODULE,
2042         .open    = gfs2_sbstats_open,
2043         .read    = seq_read,
2044         .llseek  = seq_lseek,
2045         .release = seq_release_private,
2046 };
2047
2048 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
2049 {
2050         sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
2051         if (!sdp->debugfs_dir)
2052                 return -ENOMEM;
2053         sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
2054                                                          S_IFREG | S_IRUGO,
2055                                                          sdp->debugfs_dir, sdp,
2056                                                          &gfs2_glocks_fops);
2057         if (!sdp->debugfs_dentry_glocks)
2058                 goto fail;
2059
2060         sdp->debugfs_dentry_glstats = debugfs_create_file("glstats",
2061                                                         S_IFREG | S_IRUGO,
2062                                                         sdp->debugfs_dir, sdp,
2063                                                         &gfs2_glstats_fops);
2064         if (!sdp->debugfs_dentry_glstats)
2065                 goto fail;
2066
2067         sdp->debugfs_dentry_sbstats = debugfs_create_file("sbstats",
2068                                                         S_IFREG | S_IRUGO,
2069                                                         sdp->debugfs_dir, sdp,
2070                                                         &gfs2_sbstats_fops);
2071         if (!sdp->debugfs_dentry_sbstats)
2072                 goto fail;
2073
2074         return 0;
2075 fail:
2076         gfs2_delete_debugfs_file(sdp);
2077         return -ENOMEM;
2078 }
2079
2080 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
2081 {
2082         if (sdp->debugfs_dir) {
2083                 if (sdp->debugfs_dentry_glocks) {
2084                         debugfs_remove(sdp->debugfs_dentry_glocks);
2085                         sdp->debugfs_dentry_glocks = NULL;
2086                 }
2087                 if (sdp->debugfs_dentry_glstats) {
2088                         debugfs_remove(sdp->debugfs_dentry_glstats);
2089                         sdp->debugfs_dentry_glstats = NULL;
2090                 }
2091                 if (sdp->debugfs_dentry_sbstats) {
2092                         debugfs_remove(sdp->debugfs_dentry_sbstats);
2093                         sdp->debugfs_dentry_sbstats = NULL;
2094                 }
2095                 debugfs_remove(sdp->debugfs_dir);
2096                 sdp->debugfs_dir = NULL;
2097         }
2098 }
2099
2100 int gfs2_register_debugfs(void)
2101 {
2102         gfs2_root = debugfs_create_dir("gfs2", NULL);
2103         return gfs2_root ? 0 : -ENOMEM;
2104 }
2105
2106 void gfs2_unregister_debugfs(void)
2107 {
2108         debugfs_remove(gfs2_root);
2109         gfs2_root = NULL;
2110 }