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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/sched.h>
  13 #include <linux/slab.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/buffer_head.h>
  16 #include <linux/delay.h>
  17 #include <linux/sort.h>
  18 #include <linux/jhash.h>
  19 #include <linux/kallsyms.h>
  20 #include <linux/gfs2_ondisk.h>
  21 #include <linux/list.h>
  22 #include <linux/wait.h>
  23 #include <linux/module.h>
  24 #include <asm/uaccess.h>
  25 #include <linux/seq_file.h>
  26 #include <linux/debugfs.h>
  27 #include <linux/kthread.h>
  28 #include <linux/freezer.h>
  29 #include <linux/workqueue.h>
  30 #include <linux/jiffies.h>
  31 #include <linux/rcupdate.h>
  32 #include <linux/rculist_bl.h>
  33 #include <linux/bit_spinlock.h>
  34 #include <linux/percpu.h>
  35 #include <linux/list_sort.h>
  36 #include <linux/lockref.h>
  37 #include <linux/rhashtable.h>
  38
  39 #include "gfs2.h"
  40 #include "incore.h"
  41 #include "glock.h"
  42 #include "glops.h"
  43 #include "inode.h"
  44 #include "lops.h"
  45 #include "meta_io.h"
  46 #include "quota.h"
  47 #include "super.h"
  48 #include "util.h"
  49 #include "bmap.h"
  50 #define CREATE_TRACE_POINTS
  51 #include "trace_gfs2.h"
  52
  53 struct gfs2_glock_iter {
  54         struct gfs2_sbd *sdp;           /* incore superblock           */
  55         struct rhashtable_iter hti;     /* rhashtable iterator         */
  56         struct gfs2_glock *gl;          /* current glock struct        */
  57         loff_t last_pos;                /* last position               */
  58 };
  59
  60 typedef void (*glock_examiner) (struct gfs2_glock * gl);
  61
  62 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
  63
  64 static struct dentry *gfs2_root;
  65 static struct workqueue_struct *glock_workqueue;
  66 struct workqueue_struct *gfs2_delete_workqueue;
  67 static LIST_HEAD(lru_list);
  68 static atomic_t lru_count = ATOMIC_INIT(0);
  69 static DEFINE_SPINLOCK(lru_lock);
  70
  71 #define GFS2_GL_HASH_SHIFT      15
  72 #define GFS2_GL_HASH_SIZE       BIT(GFS2_GL_HASH_SHIFT)
  73
  74 static struct rhashtable_params ht_parms = {
  75         .nelem_hint = GFS2_GL_HASH_SIZE * 3 / 4,
  76         .key_len = sizeof(struct lm_lockname),
  77         .key_offset = offsetof(struct gfs2_glock, gl_name),
  78         .head_offset = offsetof(struct gfs2_glock, gl_node),
  79 };
  80
  81 static struct rhashtable gl_hash_table;
  82
  83 static void gfs2_glock_dealloc(struct rcu_head *rcu)
  84 {
  85         struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu);
  86
  87         if (gl->gl_ops->go_flags & GLOF_ASPACE) {
  88                 kmem_cache_free(gfs2_glock_aspace_cachep, gl);
  89         } else {
  90                 kfree(gl->gl_lksb.sb_lvbptr);
  91                 kmem_cache_free(gfs2_glock_cachep, gl);
  92         }
  93 }
  94
  95 void gfs2_glock_free(struct gfs2_glock *gl)
  96 {
  97         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
  98
  99         call_rcu(&gl->gl_rcu, gfs2_glock_dealloc);
 100         if (atomic_dec_and_test(&sdp->sd_glock_disposal))
 101                 wake_up(&sdp->sd_glock_wait);
 102 }
 103
 104 /**
 105  * gfs2_glock_hold() - increment reference count on glock
 106  * @gl: The glock to hold
 107  *
 108  */
 109
 110 static void gfs2_glock_hold(struct gfs2_glock *gl)
 111 {
 112         GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
 113         lockref_get(&gl->gl_lockref);
 114 }
 115
 116 /**
 117  * demote_ok - Check to see if it's ok to unlock a glock
 118  * @gl: the glock
 119  *
 120  * Returns: 1 if it's ok
 121  */
 122
 123 static int demote_ok(const struct gfs2_glock *gl)
 124 {
 125         const struct gfs2_glock_operations *glops = gl->gl_ops;
 126
 127         if (gl->gl_state == LM_ST_UNLOCKED)
 128                 return 0;
 129         if (!list_empty(&gl->gl_holders))
 130                 return 0;
 131         if (glops->go_demote_ok)
 132                 return glops->go_demote_ok(gl);
 133         return 1;
 134 }
 135
 136
 137 void gfs2_glock_add_to_lru(struct gfs2_glock *gl)
 138 {
 139         if (!(gl->gl_ops->go_flags & GLOF_LRU))
 140                 return;
 141
 142         spin_lock(&lru_lock);
 143
 144         list_del(&gl->gl_lru);
 145         list_add_tail(&gl->gl_lru, &lru_list);
 146
 147         if (!test_bit(GLF_LRU, &gl->gl_flags)) {
 148                 set_bit(GLF_LRU, &gl->gl_flags);
 149                 atomic_inc(&lru_count);
 150         }
 151
 152         spin_unlock(&lru_lock);
 153 }
 154
 155 static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
 156 {
 157         spin_lock(&lru_lock);
 158         if (test_bit(GLF_LRU, &gl->gl_flags)) {
 159                 list_del_init(&gl->gl_lru);
 160                 atomic_dec(&lru_count);
 161                 clear_bit(GLF_LRU, &gl->gl_flags);
 162         }
 163         spin_unlock(&lru_lock);
 164 }
 165
 166 /**
 167  * gfs2_glock_put() - Decrement reference count on glock
 168  * @gl: The glock to put
 169  *
 170  */
 171
 172 void gfs2_glock_put(struct gfs2_glock *gl)
 173 {
 174         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 175         struct address_space *mapping = gfs2_glock2aspace(gl);
 176
 177         if (lockref_put_or_lock(&gl->gl_lockref))
 178                 return;
 179
 180         lockref_mark_dead(&gl->gl_lockref);
 181
 182         gfs2_glock_remove_from_lru(gl);
 183         spin_unlock(&gl->gl_lockref.lock);
 184         rhashtable_remove_fast(&gl_hash_table, &gl->gl_node, ht_parms);
 185         GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
 186         GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
 187         trace_gfs2_glock_put(gl);
 188         sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
 189 }
 190
 191 /**
 192  * may_grant - check if its ok to grant a new lock
 193  * @gl: The glock
 194  * @gh: The lock request which we wish to grant
 195  *
 196  * Returns: true if its ok to grant the lock
 197  */
 198
 199 static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
 200 {
 201         const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
 202         if ((gh->gh_state == LM_ST_EXCLUSIVE ||
 203              gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
 204                 return 0;
 205         if (gl->gl_state == gh->gh_state)
 206                 return 1;
 207         if (gh->gh_flags & GL_EXACT)
 208                 return 0;
 209         if (gl->gl_state == LM_ST_EXCLUSIVE) {
 210                 if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
 211                         return 1;
 212                 if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
 213                         return 1;
 214         }
 215         if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
 216                 return 1;
 217         return 0;
 218 }
 219
 220 static void gfs2_holder_wake(struct gfs2_holder *gh)
 221 {
 222         clear_bit(HIF_WAIT, &gh->gh_iflags);
 223         smp_mb__after_atomic();
 224         wake_up_bit(&gh->gh_iflags, HIF_WAIT);
 225 }
 226
 227 /**
 228  * do_error - Something unexpected has happened during a lock request
 229  *
 230  */
 231
 232 static void do_error(struct gfs2_glock *gl, const int ret)
 233 {
 234         struct gfs2_holder *gh, *tmp;
 235
 236         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 237                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 238                         continue;
 239                 if (ret & LM_OUT_ERROR)
 240                         gh->gh_error = -EIO;
 241                 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
 242                         gh->gh_error = GLR_TRYFAILED;
 243                 else
 244                         continue;
 245                 list_del_init(&gh->gh_list);
 246                 trace_gfs2_glock_queue(gh, 0);
 247                 gfs2_holder_wake(gh);
 248         }
 249 }
 250
 251 /**
 252  * do_promote - promote as many requests as possible on the current queue
 253  * @gl: The glock
 254  *
 255  * Returns: 1 if there is a blocked holder at the head of the list, or 2
 256  *          if a type specific operation is underway.
 257  */
 258
 259 static int do_promote(struct gfs2_glock *gl)
 260 __releases(&gl->gl_lockref.lock)
 261 __acquires(&gl->gl_lockref.lock)
 262 {
 263         const struct gfs2_glock_operations *glops = gl->gl_ops;
 264         struct gfs2_holder *gh, *tmp;
 265         int ret;
 266
 267 restart:
 268         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 269                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 270                         continue;
 271                 if (may_grant(gl, gh)) {
 272                         if (gh->gh_list.prev == &gl->gl_holders &&
 273                             glops->go_lock) {
 274                                 spin_unlock(&gl->gl_lockref.lock);
 275                                 /* FIXME: eliminate this eventually */
 276                                 ret = glops->go_lock(gh);
 277                                 spin_lock(&gl->gl_lockref.lock);
 278                                 if (ret) {
 279                                         if (ret == 1)
 280                                                 return 2;
 281                                         gh->gh_error = ret;
 282                                         list_del_init(&gh->gh_list);
 283                                         trace_gfs2_glock_queue(gh, 0);
 284                                         gfs2_holder_wake(gh);
 285                                         goto restart;
 286                                 }
 287                                 set_bit(HIF_HOLDER, &gh->gh_iflags);
 288                                 trace_gfs2_promote(gh, 1);
 289                                 gfs2_holder_wake(gh);
 290                                 goto restart;
 291                         }
 292                         set_bit(HIF_HOLDER, &gh->gh_iflags);
 293                         trace_gfs2_promote(gh, 0);
 294                         gfs2_holder_wake(gh);
 295                         continue;
 296                 }
 297                 if (gh->gh_list.prev == &gl->gl_holders)
 298                         return 1;
 299                 do_error(gl, 0);
 300                 break;
 301         }
 302         return 0;
 303 }
 304
 305 /**
 306  * find_first_waiter - find the first gh that's waiting for the glock
 307  * @gl: the glock
 308  */
 309
 310 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
 311 {
 312         struct gfs2_holder *gh;
 313
 314         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
 315                 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
 316                         return gh;
 317         }
 318         return NULL;
 319 }
 320
 321 /**
 322  * state_change - record that the glock is now in a different state
 323  * @gl: the glock
 324  * @new_state the new state
 325  *
 326  */
 327
 328 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 329 {
 330         int held1, held2;
 331
 332         held1 = (gl->gl_state != LM_ST_UNLOCKED);
 333         held2 = (new_state != LM_ST_UNLOCKED);
 334
 335         if (held1 != held2) {
 336                 GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
 337                 if (held2)
 338                         gl->gl_lockref.count++;
 339                 else
 340                         gl->gl_lockref.count--;
 341         }
 342         if (held1 && held2 && list_empty(&gl->gl_holders))
 343                 clear_bit(GLF_QUEUED, &gl->gl_flags);
 344
 345         if (new_state != gl->gl_target)
 346                 /* shorten our minimum hold time */
 347                 gl->gl_hold_time = max(gl->gl_hold_time - GL_GLOCK_HOLD_DECR,
 348                                        GL_GLOCK_MIN_HOLD);
 349         gl->gl_state = new_state;
 350         gl->gl_tchange = jiffies;
 351 }
 352
 353 static void gfs2_demote_wake(struct gfs2_glock *gl)
 354 {
 355         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 356         clear_bit(GLF_DEMOTE, &gl->gl_flags);
 357         smp_mb__after_atomic();
 358         wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
 359 }
 360
 361 /**
 362  * finish_xmote - The DLM has replied to one of our lock requests
 363  * @gl: The glock
 364  * @ret: The status from the DLM
 365  *
 366  */
 367
 368 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
 369 {
 370         const struct gfs2_glock_operations *glops = gl->gl_ops;
 371         struct gfs2_holder *gh;
 372         unsigned state = ret & LM_OUT_ST_MASK;
 373         int rv;
 374
 375         spin_lock(&gl->gl_lockref.lock);
 376         trace_gfs2_glock_state_change(gl, state);
 377         state_change(gl, state);
 378         gh = find_first_waiter(gl);
 379
 380         /* Demote to UN request arrived during demote to SH or DF */
 381         if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
 382             state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
 383                 gl->gl_target = LM_ST_UNLOCKED;
 384
 385         /* Check for state != intended state */
 386         if (unlikely(state != gl->gl_target)) {
 387                 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
 388                         /* move to back of queue and try next entry */
 389                         if (ret & LM_OUT_CANCELED) {
 390                                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
 391                                         list_move_tail(&gh->gh_list, &gl->gl_holders);
 392                                 gh = find_first_waiter(gl);
 393                                 gl->gl_target = gh->gh_state;
 394                                 goto retry;
 395                         }
 396                         /* Some error or failed "try lock" - report it */
 397                         if ((ret & LM_OUT_ERROR) ||
 398                             (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 399                                 gl->gl_target = gl->gl_state;
 400                                 do_error(gl, ret);
 401                                 goto out;
 402                         }
 403                 }
 404                 switch(state) {
 405                 /* Unlocked due to conversion deadlock, try again */
 406                 case LM_ST_UNLOCKED:
 407 retry:
 408                         do_xmote(gl, gh, gl->gl_target);
 409                         break;
 410                 /* Conversion fails, unlock and try again */
 411                 case LM_ST_SHARED:
 412                 case LM_ST_DEFERRED:
 413                         do_xmote(gl, gh, LM_ST_UNLOCKED);
 414                         break;
 415                 default: /* Everything else */
 416                         pr_err("wanted %u got %u\n", gl->gl_target, state);
 417                         GLOCK_BUG_ON(gl, 1);
 418                 }
 419                 spin_unlock(&gl->gl_lockref.lock);
 420                 return;
 421         }
 422
 423         /* Fast path - we got what we asked for */
 424         if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
 425                 gfs2_demote_wake(gl);
 426         if (state != LM_ST_UNLOCKED) {
 427                 if (glops->go_xmote_bh) {
 428                         spin_unlock(&gl->gl_lockref.lock);
 429                         rv = glops->go_xmote_bh(gl, gh);
 430                         spin_lock(&gl->gl_lockref.lock);
 431                         if (rv) {
 432                                 do_error(gl, rv);
 433                                 goto out;
 434                         }
 435                 }
 436                 rv = do_promote(gl);
 437                 if (rv == 2)
 438                         goto out_locked;
 439         }
 440 out:
 441         clear_bit(GLF_LOCK, &gl->gl_flags);
 442 out_locked:
 443         spin_unlock(&gl->gl_lockref.lock);
 444 }
 445
 446 /**
 447  * do_xmote - Calls the DLM to change the state of a lock
 448  * @gl: The lock state
 449  * @gh: The holder (only for promotes)
 450  * @target: The target lock state
 451  *
 452  */
 453
 454 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
 455 __releases(&gl->gl_lockref.lock)
 456 __acquires(&gl->gl_lockref.lock)
 457 {
 458         const struct gfs2_glock_operations *glops = gl->gl_ops;
 459         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 460         unsigned int lck_flags = (unsigned int)(gh ? gh->gh_flags : 0);
 461         int ret;
 462
 463         lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
 464                       LM_FLAG_PRIORITY);
 465         GLOCK_BUG_ON(gl, gl->gl_state == target);
 466         GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
 467         if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
 468             glops->go_inval) {
 469                 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 470                 do_error(gl, 0); /* Fail queued try locks */
 471         }
 472         gl->gl_req = target;
 473         set_bit(GLF_BLOCKING, &gl->gl_flags);
 474         if ((gl->gl_req == LM_ST_UNLOCKED) ||
 475             (gl->gl_state == LM_ST_EXCLUSIVE) ||
 476             (lck_flags & (LM_FLAG_TRY|LM_FLAG_TRY_1CB)))
 477                 clear_bit(GLF_BLOCKING, &gl->gl_flags);
 478         spin_unlock(&gl->gl_lockref.lock);
 479         if (glops->go_sync)
 480                 glops->go_sync(gl);
 481         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 482                 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
 483         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 484
 485         gfs2_glock_hold(gl);
 486         if (sdp->sd_lockstruct.ls_ops->lm_lock) {
 487                 /* lock_dlm */
 488                 ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
 489                 if (ret == -EINVAL && gl->gl_target == LM_ST_UNLOCKED &&
 490                     target == LM_ST_UNLOCKED &&
 491                     test_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags)) {
 492                         finish_xmote(gl, target);
 493                         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 494                                 gfs2_glock_put(gl);
 495                 }
 496                 else if (ret) {
 497                         pr_err("lm_lock ret %d\n", ret);
 498                         GLOCK_BUG_ON(gl, 1);
 499                 }
 500         } else { /* lock_nolock */
 501                 finish_xmote(gl, target);
 502                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 503                         gfs2_glock_put(gl);
 504         }
 505
 506         spin_lock(&gl->gl_lockref.lock);
 507 }
 508
 509 /**
 510  * find_first_holder - find the first "holder" gh
 511  * @gl: the glock
 512  */
 513
 514 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
 515 {
 516         struct gfs2_holder *gh;
 517
 518         if (!list_empty(&gl->gl_holders)) {
 519                 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 520                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 521                         return gh;
 522         }
 523         return NULL;
 524 }
 525
 526 /**
 527  * run_queue - do all outstanding tasks related to a glock
 528  * @gl: The glock in question
 529  * @nonblock: True if we must not block in run_queue
 530  *
 531  */
 532
 533 static void run_queue(struct gfs2_glock *gl, const int nonblock)
 534 __releases(&gl->gl_lockref.lock)
 535 __acquires(&gl->gl_lockref.lock)
 536 {
 537         struct gfs2_holder *gh = NULL;
 538         int ret;
 539
 540         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 541                 return;
 542
 543         GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
 544
 545         if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
 546             gl->gl_demote_state != gl->gl_state) {
 547                 if (find_first_holder(gl))
 548                         goto out_unlock;
 549                 if (nonblock)
 550                         goto out_sched;
 551                 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
 552                 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
 553                 gl->gl_target = gl->gl_demote_state;
 554         } else {
 555                 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
 556                         gfs2_demote_wake(gl);
 557                 ret = do_promote(gl);
 558                 if (ret == 0)
 559                         goto out_unlock;
 560                 if (ret == 2)
 561                         goto out;
 562                 gh = find_first_waiter(gl);
 563                 gl->gl_target = gh->gh_state;
 564                 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 565                         do_error(gl, 0); /* Fail queued try locks */
 566         }
 567         do_xmote(gl, gh, gl->gl_target);
 568 out:
 569         return;
 570
 571 out_sched:
 572         clear_bit(GLF_LOCK, &gl->gl_flags);
 573         smp_mb__after_atomic();
 574         gl->gl_lockref.count++;
 575         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 576                 gl->gl_lockref.count--;
 577         return;
 578
 579 out_unlock:
 580         clear_bit(GLF_LOCK, &gl->gl_flags);
 581         smp_mb__after_atomic();
 582         return;
 583 }
 584
 585 static void delete_work_func(struct work_struct *work)
 586 {
 587         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
 588         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 589         struct inode *inode;
 590         u64 no_addr = gl->gl_name.ln_number;
 591
 592         /* If someone's using this glock to create a new dinode, the block must
 593            have been freed by another node, then re-used, in which case our
 594            iopen callback is too late after the fact. Ignore it. */
 595         if (test_bit(GLF_INODE_CREATING, &gl->gl_flags))
 596                 goto out;
 597
 598         inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
 599         if (inode && !IS_ERR(inode)) {
 600                 d_prune_aliases(inode);
 601                 iput(inode);
 602         }
 603 out:
 604         gfs2_glock_put(gl);
 605 }
 606
 607 static void glock_work_func(struct work_struct *work)
 608 {
 609         unsigned long delay = 0;
 610         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
 611         int drop_ref = 0;
 612
 613         if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
 614                 finish_xmote(gl, gl->gl_reply);
 615                 drop_ref = 1;
 616         }
 617         spin_lock(&gl->gl_lockref.lock);
 618         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
 619             gl->gl_state != LM_ST_UNLOCKED &&
 620             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
 621                 unsigned long holdtime, now = jiffies;
 622
 623                 holdtime = gl->gl_tchange + gl->gl_hold_time;
 624                 if (time_before(now, holdtime))
 625                         delay = holdtime - now;
 626
 627                 if (!delay) {
 628                         clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
 629                         set_bit(GLF_DEMOTE, &gl->gl_flags);
 630                 }
 631         }
 632         run_queue(gl, 0);
 633         spin_unlock(&gl->gl_lockref.lock);
 634         if (!delay)
 635                 gfs2_glock_put(gl);
 636         else {
 637                 if (gl->gl_name.ln_type != LM_TYPE_INODE)
 638                         delay = 0;
 639                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
 640                         gfs2_glock_put(gl);
 641         }
 642         if (drop_ref)
 643                 gfs2_glock_put(gl);
 644 }
 645
 646 /**
 647  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
 648  * @sdp: The GFS2 superblock
 649  * @number: the lock number
 650  * @glops: The glock_operations to use
 651  * @create: If 0, don't create the glock if it doesn't exist
 652  * @glp: the glock is returned here
 653  *
 654  * This does not lock a glock, just finds/creates structures for one.
 655  *
 656  * Returns: errno
 657  */
 658
 659 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 660                    const struct gfs2_glock_operations *glops, int create,
 661                    struct gfs2_glock **glp)
 662 {
 663         struct super_block *s = sdp->sd_vfs;
 664         struct lm_lockname name = { .ln_number = number,
 665                                     .ln_type = glops->go_type,
 666                                     .ln_sbd = sdp };
 667         struct gfs2_glock *gl, *tmp = NULL;
 668         struct address_space *mapping;
 669         struct kmem_cache *cachep;
 670         int ret, tries = 0;
 671
 672         rcu_read_lock();
 673         gl = rhashtable_lookup_fast(&gl_hash_table, &name, ht_parms);
 674         if (gl && !lockref_get_not_dead(&gl->gl_lockref))
 675                 gl = NULL;
 676         rcu_read_unlock();
 677
 678         *glp = gl;
 679         if (gl)
 680                 return 0;
 681         if (!create)
 682                 return -ENOENT;
 683
 684         if (glops->go_flags & GLOF_ASPACE)
 685                 cachep = gfs2_glock_aspace_cachep;
 686         else
 687                 cachep = gfs2_glock_cachep;
 688         gl = kmem_cache_alloc(cachep, GFP_NOFS);
 689         if (!gl)
 690                 return -ENOMEM;
 691
 692         memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
 693
 694         if (glops->go_flags & GLOF_LVB) {
 695                 gl->gl_lksb.sb_lvbptr = kzalloc(GFS2_MIN_LVB_SIZE, GFP_NOFS);
 696                 if (!gl->gl_lksb.sb_lvbptr) {
 697                         kmem_cache_free(cachep, gl);
 698                         return -ENOMEM;
 699                 }
 700         }
 701
 702         atomic_inc(&sdp->sd_glock_disposal);
 703         gl->gl_node.next = NULL;
 704         gl->gl_flags = 0;
 705         gl->gl_name = name;
 706         gl->gl_lockref.count = 1;
 707         gl->gl_state = LM_ST_UNLOCKED;
 708         gl->gl_target = LM_ST_UNLOCKED;
 709         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 710         gl->gl_ops = glops;
 711         gl->gl_dstamp = ktime_set(0, 0);
 712         preempt_disable();
 713         /* We use the global stats to estimate the initial per-glock stats */
 714         gl->gl_stats = this_cpu_ptr(sdp->sd_lkstats)->lkstats[glops->go_type];
 715         preempt_enable();
 716         gl->gl_stats.stats[GFS2_LKS_DCOUNT] = 0;
 717         gl->gl_stats.stats[GFS2_LKS_QCOUNT] = 0;
 718         gl->gl_tchange = jiffies;
 719         gl->gl_object = NULL;
 720         gl->gl_hold_time = GL_GLOCK_DFT_HOLD;
 721         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
 722         INIT_WORK(&gl->gl_delete, delete_work_func);
 723
 724         mapping = gfs2_glock2aspace(gl);
 725         if (mapping) {
 726                 mapping->a_ops = &gfs2_meta_aops;
 727                 mapping->host = s->s_bdev->bd_inode;
 728                 mapping->flags = 0;
 729                 mapping_set_gfp_mask(mapping, GFP_NOFS);
 730                 mapping->private_data = NULL;
 731                 mapping->writeback_index = 0;
 732         }
 733
 734 again:
 735         ret = rhashtable_lookup_insert_fast(&gl_hash_table, &gl->gl_node,
 736                                             ht_parms);
 737         if (ret == 0) {
 738                 *glp = gl;
 739                 return 0;
 740         }
 741
 742         if (ret == -EEXIST) {
 743                 ret = 0;
 744                 rcu_read_lock();
 745                 tmp = rhashtable_lookup_fast(&gl_hash_table, &name, ht_parms);
 746                 if (tmp == NULL || !lockref_get_not_dead(&tmp->gl_lockref)) {
 747                         if (++tries < 100) {
 748                                 rcu_read_unlock();
 749                                 cond_resched();
 750                                 goto again;
 751                         }
 752                         tmp = NULL;
 753                         ret = -ENOMEM;
 754                 }
 755                 rcu_read_unlock();
 756         } else {
 757                 WARN_ON_ONCE(ret);
 758         }
 759         kfree(gl->gl_lksb.sb_lvbptr);
 760         kmem_cache_free(cachep, gl);
 761         if (atomic_dec_and_test(&sdp->sd_glock_disposal))
 762                 wake_up(&sdp->sd_glock_wait);
 763         *glp = tmp;
 764
 765         return ret;
 766 }
 767
 768 /**
 769  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
 770  * @gl: the glock
 771  * @state: the state we're requesting
 772  * @flags: the modifier flags
 773  * @gh: the holder structure
 774  *
 775  */
 776
 777 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, u16 flags,
 778                       struct gfs2_holder *gh)
 779 {
 780         INIT_LIST_HEAD(&gh->gh_list);
 781         gh->gh_gl = gl;
 782         gh->gh_ip = _RET_IP_;
 783         gh->gh_owner_pid = get_pid(task_pid(current));
 784         gh->gh_state = state;
 785         gh->gh_flags = flags;
 786         gh->gh_error = 0;
 787         gh->gh_iflags = 0;
 788         gfs2_glock_hold(gl);
 789 }
 790
 791 /**
 792  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
 793  * @state: the state we're requesting
 794  * @flags: the modifier flags
 795  * @gh: the holder structure
 796  *
 797  * Don't mess with the glock.
 798  *
 799  */
 800
 801 void gfs2_holder_reinit(unsigned int state, u16 flags, struct gfs2_holder *gh)
 802 {
 803         gh->gh_state = state;
 804         gh->gh_flags = flags;
 805         gh->gh_iflags = 0;
 806         gh->gh_ip = _RET_IP_;
 807         put_pid(gh->gh_owner_pid);
 808         gh->gh_owner_pid = get_pid(task_pid(current));
 809 }
 810
 811 /**
 812  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 813  * @gh: the holder structure
 814  *
 815  */
 816
 817 void gfs2_holder_uninit(struct gfs2_holder *gh)
 818 {
 819         put_pid(gh->gh_owner_pid);
 820         gfs2_glock_put(gh->gh_gl);
 821         gfs2_holder_mark_uninitialized(gh);
 822         gh->gh_ip = 0;
 823 }
 824
 825 /**
 826  * gfs2_glock_wait - wait on a glock acquisition
 827  * @gh: the glock holder
 828  *
 829  * Returns: 0 on success
 830  */
 831
 832 int gfs2_glock_wait(struct gfs2_holder *gh)
 833 {
 834         unsigned long time1 = jiffies;
 835
 836         might_sleep();
 837         wait_on_bit(&gh->gh_iflags, HIF_WAIT, TASK_UNINTERRUPTIBLE);
 838         if (time_after(jiffies, time1 + HZ)) /* have we waited > a second? */
 839                 /* Lengthen the minimum hold time. */
 840                 gh->gh_gl->gl_hold_time = min(gh->gh_gl->gl_hold_time +
 841                                               GL_GLOCK_HOLD_INCR,
 842                                               GL_GLOCK_MAX_HOLD);
 843         return gh->gh_error;
 844 }
 845
 846 /**
 847  * handle_callback - process a demote request
 848  * @gl: the glock
 849  * @state: the state the caller wants us to change to
 850  *
 851  * There are only two requests that we are going to see in actual
 852  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
 853  */
 854
 855 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
 856                             unsigned long delay, bool remote)
 857 {
 858         int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
 859
 860         set_bit(bit, &gl->gl_flags);
 861         if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
 862                 gl->gl_demote_state = state;
 863                 gl->gl_demote_time = jiffies;
 864         } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
 865                         gl->gl_demote_state != state) {
 866                 gl->gl_demote_state = LM_ST_UNLOCKED;
 867         }
 868         if (gl->gl_ops->go_callback)
 869                 gl->gl_ops->go_callback(gl, remote);
 870         trace_gfs2_demote_rq(gl, remote);
 871 }
 872
 873 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
 874 {
 875         struct va_format vaf;
 876         va_list args;
 877
 878         va_start(args, fmt);
 879
 880         if (seq) {
 881                 seq_vprintf(seq, fmt, args);
 882         } else {
 883                 vaf.fmt = fmt;
 884                 vaf.va = &args;
 885
 886                 pr_err("%pV", &vaf);
 887         }
 888
 889         va_end(args);
 890 }
 891
 892 /**
 893  * add_to_queue - Add a holder to the wait queue (but look for recursion)
 894  * @gh: the holder structure to add
 895  *
 896  * Eventually we should move the recursive locking trap to a
 897  * debugging option or something like that. This is the fast
 898  * path and needs to have the minimum number of distractions.
 899  *
 900  */
 901
 902 static inline void add_to_queue(struct gfs2_holder *gh)
 903 __releases(&gl->gl_lockref.lock)
 904 __acquires(&gl->gl_lockref.lock)
 905 {
 906         struct gfs2_glock *gl = gh->gh_gl;
 907         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 908         struct list_head *insert_pt = NULL;
 909         struct gfs2_holder *gh2;
 910         int try_futile = 0;
 911
 912         BUG_ON(gh->gh_owner_pid == NULL);
 913         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
 914                 BUG();
 915
 916         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
 917                 if (test_bit(GLF_LOCK, &gl->gl_flags))
 918                         try_futile = !may_grant(gl, gh);
 919                 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 920                         goto fail;
 921         }
 922
 923         list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
 924                 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
 925                     (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
 926                         goto trap_recursive;
 927                 if (try_futile &&
 928                     !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 929 fail:
 930                         gh->gh_error = GLR_TRYFAILED;
 931                         gfs2_holder_wake(gh);
 932                         return;
 933                 }
 934                 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
 935                         continue;
 936                 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
 937                         insert_pt = &gh2->gh_list;
 938         }
 939         set_bit(GLF_QUEUED, &gl->gl_flags);
 940         trace_gfs2_glock_queue(gh, 1);
 941         gfs2_glstats_inc(gl, GFS2_LKS_QCOUNT);
 942         gfs2_sbstats_inc(gl, GFS2_LKS_QCOUNT);
 943         if (likely(insert_pt == NULL)) {
 944                 list_add_tail(&gh->gh_list, &gl->gl_holders);
 945                 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
 946                         goto do_cancel;
 947                 return;
 948         }
 949         list_add_tail(&gh->gh_list, insert_pt);
 950 do_cancel:
 951         gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 952         if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
 953                 spin_unlock(&gl->gl_lockref.lock);
 954                 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
 955                         sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
 956                 spin_lock(&gl->gl_lockref.lock);
 957         }
 958         return;
 959
 960 trap_recursive:
 961         pr_err("original: %pSR\n", (void *)gh2->gh_ip);
 962         pr_err("pid: %d\n", pid_nr(gh2->gh_owner_pid));
 963         pr_err("lock type: %d req lock state : %d\n",
 964                gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
 965         pr_err("new: %pSR\n", (void *)gh->gh_ip);
 966         pr_err("pid: %d\n", pid_nr(gh->gh_owner_pid));
 967         pr_err("lock type: %d req lock state : %d\n",
 968                gh->gh_gl->gl_name.ln_type, gh->gh_state);
 969         gfs2_dump_glock(NULL, gl);
 970         BUG();
 971 }
 972
 973 /**
 974  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
 975  * @gh: the holder structure
 976  *
 977  * if (gh->gh_flags & GL_ASYNC), this never returns an error
 978  *
 979  * Returns: 0, GLR_TRYFAILED, or errno on failure
 980  */
 981
 982 int gfs2_glock_nq(struct gfs2_holder *gh)
 983 {
 984         struct gfs2_glock *gl = gh->gh_gl;
 985         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 986         int error = 0;
 987
 988         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
 989                 return -EIO;
 990
 991         if (test_bit(GLF_LRU, &gl->gl_flags))
 992                 gfs2_glock_remove_from_lru(gl);
 993
 994         spin_lock(&gl->gl_lockref.lock);
 995         add_to_queue(gh);
 996         if (unlikely((LM_FLAG_NOEXP & gh->gh_flags) &&
 997                      test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))) {
 998                 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
 999                 gl->gl_lockref.count++;
1000                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1001                         gl->gl_lockref.count--;
1002         }
1003         run_queue(gl, 1);
1004         spin_unlock(&gl->gl_lockref.lock);
1005
1006         if (!(gh->gh_flags & GL_ASYNC))
1007                 error = gfs2_glock_wait(gh);
1008
1009         return error;
1010 }
1011
1012 /**
1013  * gfs2_glock_poll - poll to see if an async request has been completed
1014  * @gh: the holder
1015  *
1016  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1017  */
1018
1019 int gfs2_glock_poll(struct gfs2_holder *gh)
1020 {
1021         return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1022 }
1023
1024 /**
1025  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1026  * @gh: the glock holder
1027  *
1028  */
1029
1030 void gfs2_glock_dq(struct gfs2_holder *gh)
1031 {
1032         struct gfs2_glock *gl = gh->gh_gl;
1033         const struct gfs2_glock_operations *glops = gl->gl_ops;
1034         unsigned delay = 0;
1035         int fast_path = 0;
1036
1037         spin_lock(&gl->gl_lockref.lock);
1038         if (gh->gh_flags & GL_NOCACHE)
1039                 handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1040
1041         list_del_init(&gh->gh_list);
1042         clear_bit(HIF_HOLDER, &gh->gh_iflags);
1043         if (find_first_holder(gl) == NULL) {
1044                 if (glops->go_unlock) {
1045                         GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1046                         spin_unlock(&gl->gl_lockref.lock);
1047                         glops->go_unlock(gh);
1048                         spin_lock(&gl->gl_lockref.lock);
1049                         clear_bit(GLF_LOCK, &gl->gl_flags);
1050                 }
1051                 if (list_empty(&gl->gl_holders) &&
1052                     !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1053                     !test_bit(GLF_DEMOTE, &gl->gl_flags))
1054                         fast_path = 1;
1055         }
1056         if (!test_bit(GLF_LFLUSH, &gl->gl_flags) && demote_ok(gl))
1057                 gfs2_glock_add_to_lru(gl);
1058
1059         trace_gfs2_glock_queue(gh, 0);
1060         spin_unlock(&gl->gl_lockref.lock);
1061         if (likely(fast_path))
1062                 return;
1063
1064         gfs2_glock_hold(gl);
1065         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1066             !test_bit(GLF_DEMOTE, &gl->gl_flags) &&
1067             gl->gl_name.ln_type == LM_TYPE_INODE)
1068                 delay = gl->gl_hold_time;
1069         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1070                 gfs2_glock_put(gl);
1071 }
1072
1073 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1074 {
1075         struct gfs2_glock *gl = gh->gh_gl;
1076         gfs2_glock_dq(gh);
1077         might_sleep();
1078         wait_on_bit(&gl->gl_flags, GLF_DEMOTE, TASK_UNINTERRUPTIBLE);
1079 }
1080
1081 /**
1082  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1083  * @gh: the holder structure
1084  *
1085  */
1086
1087 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1088 {
1089         gfs2_glock_dq(gh);
1090         gfs2_holder_uninit(gh);
1091 }
1092
1093 /**
1094  * gfs2_glock_nq_num - acquire a glock based on lock number
1095  * @sdp: the filesystem
1096  * @number: the lock number
1097  * @glops: the glock operations for the type of glock
1098  * @state: the state to acquire the glock in
1099  * @flags: modifier flags for the acquisition
1100  * @gh: the struct gfs2_holder
1101  *
1102  * Returns: errno
1103  */
1104
1105 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1106                       const struct gfs2_glock_operations *glops,
1107                       unsigned int state, u16 flags, struct gfs2_holder *gh)
1108 {
1109         struct gfs2_glock *gl;
1110         int error;
1111
1112         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1113         if (!error) {
1114                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1115                 gfs2_glock_put(gl);
1116         }
1117
1118         return error;
1119 }
1120
1121 /**
1122  * glock_compare - Compare two struct gfs2_glock structures for sorting
1123  * @arg_a: the first structure
1124  * @arg_b: the second structure
1125  *
1126  */
1127
1128 static int glock_compare(const void *arg_a, const void *arg_b)
1129 {
1130         const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1131         const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1132         const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1133         const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1134
1135         if (a->ln_number > b->ln_number)
1136                 return 1;
1137         if (a->ln_number < b->ln_number)
1138                 return -1;
1139         BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1140         return 0;
1141 }
1142
1143 /**
1144  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1145  * @num_gh: the number of structures
1146  * @ghs: an array of struct gfs2_holder structures
1147  *
1148  * Returns: 0 on success (all glocks acquired),
1149  *          errno on failure (no glocks acquired)
1150  */
1151
1152 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1153                      struct gfs2_holder **p)
1154 {
1155         unsigned int x;
1156         int error = 0;
1157
1158         for (x = 0; x < num_gh; x++)
1159                 p[x] = &ghs[x];
1160
1161         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1162
1163         for (x = 0; x < num_gh; x++) {
1164                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1165
1166                 error = gfs2_glock_nq(p[x]);
1167                 if (error) {
1168                         while (x--)
1169                                 gfs2_glock_dq(p[x]);
1170                         break;
1171                 }
1172         }
1173
1174         return error;
1175 }
1176
1177 /**
1178  * gfs2_glock_nq_m - acquire multiple glocks
1179  * @num_gh: the number of structures
1180  * @ghs: an array of struct gfs2_holder structures
1181  *
1182  *
1183  * Returns: 0 on success (all glocks acquired),
1184  *          errno on failure (no glocks acquired)
1185  */
1186
1187 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1188 {
1189         struct gfs2_holder *tmp[4];
1190         struct gfs2_holder **pph = tmp;
1191         int error = 0;
1192
1193         switch(num_gh) {
1194         case 0:
1195                 return 0;
1196         case 1:
1197                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1198                 return gfs2_glock_nq(ghs);
1199         default:
1200                 if (num_gh <= 4)
1201                         break;
1202                 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1203                 if (!pph)
1204                         return -ENOMEM;
1205         }
1206
1207         error = nq_m_sync(num_gh, ghs, pph);
1208
1209         if (pph != tmp)
1210                 kfree(pph);
1211
1212         return error;
1213 }
1214
1215 /**
1216  * gfs2_glock_dq_m - release multiple glocks
1217  * @num_gh: the number of structures
1218  * @ghs: an array of struct gfs2_holder structures
1219  *
1220  */
1221
1222 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1223 {
1224         while (num_gh--)
1225                 gfs2_glock_dq(&ghs[num_gh]);
1226 }
1227
1228 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1229 {
1230         unsigned long delay = 0;
1231         unsigned long holdtime;
1232         unsigned long now = jiffies;
1233
1234         gfs2_glock_hold(gl);
1235         holdtime = gl->gl_tchange + gl->gl_hold_time;
1236         if (test_bit(GLF_QUEUED, &gl->gl_flags) &&
1237             gl->gl_name.ln_type == LM_TYPE_INODE) {
1238                 if (time_before(now, holdtime))
1239                         delay = holdtime - now;
1240                 if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1241                         delay = gl->gl_hold_time;
1242         }
1243
1244         spin_lock(&gl->gl_lockref.lock);
1245         handle_callback(gl, state, delay, true);
1246         spin_unlock(&gl->gl_lockref.lock);
1247         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1248                 gfs2_glock_put(gl);
1249 }
1250
1251 /**
1252  * gfs2_should_freeze - Figure out if glock should be frozen
1253  * @gl: The glock in question
1254  *
1255  * Glocks are not frozen if (a) the result of the dlm operation is
1256  * an error, (b) the locking operation was an unlock operation or
1257  * (c) if there is a "noexp" flagged request anywhere in the queue
1258  *
1259  * Returns: 1 if freezing should occur, 0 otherwise
1260  */
1261
1262 static int gfs2_should_freeze(const struct gfs2_glock *gl)
1263 {
1264         const struct gfs2_holder *gh;
1265
1266         if (gl->gl_reply & ~LM_OUT_ST_MASK)
1267                 return 0;
1268         if (gl->gl_target == LM_ST_UNLOCKED)
1269                 return 0;
1270
1271         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1272                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1273                         continue;
1274                 if (LM_FLAG_NOEXP & gh->gh_flags)
1275                         return 0;
1276         }
1277
1278         return 1;
1279 }
1280
1281 /**
1282  * gfs2_glock_complete - Callback used by locking
1283  * @gl: Pointer to the glock
1284  * @ret: The return value from the dlm
1285  *
1286  * The gl_reply field is under the gl_lockref.lock lock so that it is ok
1287  * to use a bitfield shared with other glock state fields.
1288  */
1289
1290 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1291 {
1292         struct lm_lockstruct *ls = &gl->gl_name.ln_sbd->sd_lockstruct;
1293
1294         spin_lock(&gl->gl_lockref.lock);
1295         gl->gl_reply = ret;
1296
1297         if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags))) {
1298                 if (gfs2_should_freeze(gl)) {
1299                         set_bit(GLF_FROZEN, &gl->gl_flags);
1300                         spin_unlock(&gl->gl_lockref.lock);
1301                         return;
1302                 }
1303         }
1304
1305         gl->gl_lockref.count++;
1306         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1307         spin_unlock(&gl->gl_lockref.lock);
1308
1309         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1310                 gfs2_glock_put(gl);
1311 }
1312
1313 static int glock_cmp(void *priv, struct list_head *a, struct list_head *b)
1314 {
1315         struct gfs2_glock *gla, *glb;
1316
1317         gla = list_entry(a, struct gfs2_glock, gl_lru);
1318         glb = list_entry(b, struct gfs2_glock, gl_lru);
1319
1320         if (gla->gl_name.ln_number > glb->gl_name.ln_number)
1321                 return 1;
1322         if (gla->gl_name.ln_number < glb->gl_name.ln_number)
1323                 return -1;
1324
1325         return 0;
1326 }
1327
1328 /**
1329  * gfs2_dispose_glock_lru - Demote a list of glocks
1330  * @list: The list to dispose of
1331  *
1332  * Disposing of glocks may involve disk accesses, so that here we sort
1333  * the glocks by number (i.e. disk location of the inodes) so that if
1334  * there are any such accesses, they'll be sent in order (mostly).
1335  *
1336  * Must be called under the lru_lock, but may drop and retake this
1337  * lock. While the lru_lock is dropped, entries may vanish from the
1338  * list, but no new entries will appear on the list (since it is
1339  * private)
1340  */
1341
1342 static void gfs2_dispose_glock_lru(struct list_head *list)
1343 __releases(&lru_lock)
1344 __acquires(&lru_lock)
1345 {
1346         struct gfs2_glock *gl;
1347
1348         list_sort(NULL, list, glock_cmp);
1349
1350         while(!list_empty(list)) {
1351                 gl = list_entry(list->next, struct gfs2_glock, gl_lru);
1352                 list_del_init(&gl->gl_lru);
1353                 clear_bit(GLF_LRU, &gl->gl_flags);
1354                 if (!spin_trylock(&gl->gl_lockref.lock)) {
1355 add_back_to_lru:
1356                         list_add(&gl->gl_lru, &lru_list);
1357                         set_bit(GLF_LRU, &gl->gl_flags);
1358                         atomic_inc(&lru_count);
1359                         continue;
1360                 }
1361                 if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1362                         spin_unlock(&gl->gl_lockref.lock);
1363                         goto add_back_to_lru;
1364                 }
1365                 gl->gl_lockref.count++;
1366                 if (demote_ok(gl))
1367                         handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1368                 WARN_ON(!test_and_clear_bit(GLF_LOCK, &gl->gl_flags));
1369                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1370                         gl->gl_lockref.count--;
1371                 spin_unlock(&gl->gl_lockref.lock);
1372                 cond_resched_lock(&lru_lock);
1373         }
1374 }
1375
1376 /**
1377  * gfs2_scan_glock_lru - Scan the LRU looking for locks to demote
1378  * @nr: The number of entries to scan
1379  *
1380  * This function selects the entries on the LRU which are able to
1381  * be demoted, and then kicks off the process by calling
1382  * gfs2_dispose_glock_lru() above.
1383  */
1384
1385 static long gfs2_scan_glock_lru(int nr)
1386 {
1387         struct gfs2_glock *gl;
1388         LIST_HEAD(skipped);
1389         LIST_HEAD(dispose);
1390         long freed = 0;
1391
1392         spin_lock(&lru_lock);
1393         while ((nr-- >= 0) && !list_empty(&lru_list)) {
1394                 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1395
1396                 /* Test for being demotable */
1397                 if (!test_bit(GLF_LOCK, &gl->gl_flags)) {
1398                         list_move(&gl->gl_lru, &dispose);
1399                         atomic_dec(&lru_count);
1400                         freed++;
1401                         continue;
1402                 }
1403
1404                 list_move(&gl->gl_lru, &skipped);
1405         }
1406         list_splice(&skipped, &lru_list);
1407         if (!list_empty(&dispose))
1408                 gfs2_dispose_glock_lru(&dispose);
1409         spin_unlock(&lru_lock);
1410
1411         return freed;
1412 }
1413
1414 static unsigned long gfs2_glock_shrink_scan(struct shrinker *shrink,
1415                                             struct shrink_control *sc)
1416 {
1417         if (!(sc->gfp_mask & __GFP_FS))
1418                 return SHRINK_STOP;
1419         return gfs2_scan_glock_lru(sc->nr_to_scan);
1420 }
1421
1422 static unsigned long gfs2_glock_shrink_count(struct shrinker *shrink,
1423                                              struct shrink_control *sc)
1424 {
1425         return vfs_pressure_ratio(atomic_read(&lru_count));
1426 }
1427
1428 static struct shrinker glock_shrinker = {
1429         .seeks = DEFAULT_SEEKS,
1430         .count_objects = gfs2_glock_shrink_count,
1431         .scan_objects = gfs2_glock_shrink_scan,
1432 };
1433
1434 /**
1435  * examine_bucket - Call a function for glock in a hash bucket
1436  * @examiner: the function
1437  * @sdp: the filesystem
1438  * @bucket: the bucket
1439  *
1440  * Note that the function can be called multiple times on the same
1441  * object.  So the user must ensure that the function can cope with
1442  * that.
1443  */
1444
1445 static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
1446 {
1447         struct gfs2_glock *gl;
1448         struct rhashtable_iter iter;
1449
1450         rhashtable_walk_enter(&gl_hash_table, &iter);
1451
1452         do {
1453                 gl = ERR_PTR(rhashtable_walk_start(&iter));
1454                 if (gl)
1455                         continue;
1456
1457                 while ((gl = rhashtable_walk_next(&iter)) && !IS_ERR(gl))
1458                         if ((gl->gl_name.ln_sbd == sdp) &&
1459                             lockref_get_not_dead(&gl->gl_lockref))
1460                                 examiner(gl);
1461
1462                 rhashtable_walk_stop(&iter);
1463         } while (cond_resched(), gl == ERR_PTR(-EAGAIN));
1464
1465         rhashtable_walk_exit(&iter);
1466 }
1467
1468 /**
1469  * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1470  * @gl: The glock to thaw
1471  *
1472  */
1473
1474 static void thaw_glock(struct gfs2_glock *gl)
1475 {
1476         if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1477                 goto out;
1478         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1479         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0) {
1480 out:
1481                 gfs2_glock_put(gl);
1482         }
1483 }
1484
1485 /**
1486  * clear_glock - look at a glock and see if we can free it from glock cache
1487  * @gl: the glock to look at
1488  *
1489  */
1490
1491 static void clear_glock(struct gfs2_glock *gl)
1492 {
1493         gfs2_glock_remove_from_lru(gl);
1494
1495         spin_lock(&gl->gl_lockref.lock);
1496         if (gl->gl_state != LM_ST_UNLOCKED)
1497                 handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1498         spin_unlock(&gl->gl_lockref.lock);
1499         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1500                 gfs2_glock_put(gl);
1501 }
1502
1503 /**
1504  * gfs2_glock_thaw - Thaw any frozen glocks
1505  * @sdp: The super block
1506  *
1507  */
1508
1509 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1510 {
1511         glock_hash_walk(thaw_glock, sdp);
1512 }
1513
1514 static void dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1515 {
1516         spin_lock(&gl->gl_lockref.lock);
1517         gfs2_dump_glock(seq, gl);
1518         spin_unlock(&gl->gl_lockref.lock);
1519 }
1520
1521 static void dump_glock_func(struct gfs2_glock *gl)
1522 {
1523         dump_glock(NULL, gl);
1524 }
1525
1526 /**
1527  * gfs2_gl_hash_clear - Empty out the glock hash table
1528  * @sdp: the filesystem
1529  * @wait: wait until it's all gone
1530  *
1531  * Called when unmounting the filesystem.
1532  */
1533
1534 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1535 {
1536         set_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags);
1537         flush_workqueue(glock_workqueue);
1538         glock_hash_walk(clear_glock, sdp);
1539         flush_workqueue(glock_workqueue);
1540         wait_event_timeout(sdp->sd_glock_wait,
1541                            atomic_read(&sdp->sd_glock_disposal) == 0,
1542                            HZ * 600);
1543         glock_hash_walk(dump_glock_func, sdp);
1544 }
1545
1546 void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1547 {
1548         struct gfs2_glock *gl = ip->i_gl;
1549         int ret;
1550
1551         ret = gfs2_truncatei_resume(ip);
1552         gfs2_assert_withdraw(gl->gl_name.ln_sbd, ret == 0);
1553
1554         spin_lock(&gl->gl_lockref.lock);
1555         clear_bit(GLF_LOCK, &gl->gl_flags);
1556         run_queue(gl, 1);
1557         spin_unlock(&gl->gl_lockref.lock);
1558 }
1559
1560 static const char *state2str(unsigned state)
1561 {
1562         switch(state) {
1563         case LM_ST_UNLOCKED:
1564                 return "UN";
1565         case LM_ST_SHARED:
1566                 return "SH";
1567         case LM_ST_DEFERRED:
1568                 return "DF";
1569         case LM_ST_EXCLUSIVE:
1570                 return "EX";
1571         }
1572         return "??";
1573 }
1574
1575 static const char *hflags2str(char *buf, u16 flags, unsigned long iflags)
1576 {
1577         char *p = buf;
1578         if (flags & LM_FLAG_TRY)
1579                 *p++ = 't';
1580         if (flags & LM_FLAG_TRY_1CB)
1581                 *p++ = 'T';
1582         if (flags & LM_FLAG_NOEXP)
1583                 *p++ = 'e';
1584         if (flags & LM_FLAG_ANY)
1585                 *p++ = 'A';
1586         if (flags & LM_FLAG_PRIORITY)
1587                 *p++ = 'p';
1588         if (flags & GL_ASYNC)
1589                 *p++ = 'a';
1590         if (flags & GL_EXACT)
1591                 *p++ = 'E';
1592         if (flags & GL_NOCACHE)
1593                 *p++ = 'c';
1594         if (test_bit(HIF_HOLDER, &iflags))
1595                 *p++ = 'H';
1596         if (test_bit(HIF_WAIT, &iflags))
1597                 *p++ = 'W';
1598         if (test_bit(HIF_FIRST, &iflags))
1599                 *p++ = 'F';
1600         *p = 0;
1601         return buf;
1602 }
1603
1604 /**
1605  * dump_holder - print information about a glock holder
1606  * @seq: the seq_file struct
1607  * @gh: the glock holder
1608  *
1609  */
1610
1611 static void dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1612 {
1613         struct task_struct *gh_owner = NULL;
1614         char flags_buf[32];
1615
1616         rcu_read_lock();
1617         if (gh->gh_owner_pid)
1618                 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1619         gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
1620                        state2str(gh->gh_state),
1621                        hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1622                        gh->gh_error,
1623                        gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1624                        gh_owner ? gh_owner->comm : "(ended)",
1625                        (void *)gh->gh_ip);
1626         rcu_read_unlock();
1627 }
1628
1629 static const char *gflags2str(char *buf, const struct gfs2_glock *gl)
1630 {
1631         const unsigned long *gflags = &gl->gl_flags;
1632         char *p = buf;
1633
1634         if (test_bit(GLF_LOCK, gflags))
1635                 *p++ = 'l';
1636         if (test_bit(GLF_DEMOTE, gflags))
1637                 *p++ = 'D';
1638         if (test_bit(GLF_PENDING_DEMOTE, gflags))
1639                 *p++ = 'd';
1640         if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1641                 *p++ = 'p';
1642         if (test_bit(GLF_DIRTY, gflags))
1643                 *p++ = 'y';
1644         if (test_bit(GLF_LFLUSH, gflags))
1645                 *p++ = 'f';
1646         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1647                 *p++ = 'i';
1648         if (test_bit(GLF_REPLY_PENDING, gflags))
1649                 *p++ = 'r';
1650         if (test_bit(GLF_INITIAL, gflags))
1651                 *p++ = 'I';
1652         if (test_bit(GLF_FROZEN, gflags))
1653                 *p++ = 'F';
1654         if (test_bit(GLF_QUEUED, gflags))
1655                 *p++ = 'q';
1656         if (test_bit(GLF_LRU, gflags))
1657                 *p++ = 'L';
1658         if (gl->gl_object)
1659                 *p++ = 'o';
1660         if (test_bit(GLF_BLOCKING, gflags))
1661                 *p++ = 'b';
1662         *p = 0;
1663         return buf;
1664 }
1665
1666 /**
1667  * gfs2_dump_glock - print information about a glock
1668  * @seq: The seq_file struct
1669  * @gl: the glock
1670  *
1671  * The file format is as follows:
1672  * One line per object, capital letters are used to indicate objects
1673  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1674  * other objects are indented by a single space and follow the glock to
1675  * which they are related. Fields are indicated by lower case letters
1676  * followed by a colon and the field value, except for strings which are in
1677  * [] so that its possible to see if they are composed of spaces for
1678  * example. The field's are n = number (id of the object), f = flags,
1679  * t = type, s = state, r = refcount, e = error, p = pid.
1680  *
1681  */
1682
1683 void gfs2_dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1684 {
1685         const struct gfs2_glock_operations *glops = gl->gl_ops;
1686         unsigned long long dtime;
1687         const struct gfs2_holder *gh;
1688         char gflags_buf[32];
1689
1690         dtime = jiffies - gl->gl_demote_time;
1691         dtime *= 1000000/HZ; /* demote time in uSec */
1692         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1693                 dtime = 0;
1694         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",
1695                   state2str(gl->gl_state),
1696                   gl->gl_name.ln_type,
1697                   (unsigned long long)gl->gl_name.ln_number,
1698                   gflags2str(gflags_buf, gl),
1699                   state2str(gl->gl_target),
1700                   state2str(gl->gl_demote_state), dtime,
1701                   atomic_read(&gl->gl_ail_count),
1702                   atomic_read(&gl->gl_revokes),
1703                   (int)gl->gl_lockref.count, gl->gl_hold_time);
1704
1705         list_for_each_entry(gh, &gl->gl_holders, gh_list)
1706                 dump_holder(seq, gh);
1707
1708         if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1709                 glops->go_dump(seq, gl);
1710 }
1711
1712 static int gfs2_glstats_seq_show(struct seq_file *seq, void *iter_ptr)
1713 {
1714         struct gfs2_glock *gl = iter_ptr;
1715
1716         seq_printf(seq, "G: n:%u/%llx rtt:%llu/%llu rttb:%llu/%llu irt:%llu/%llu dcnt: %llu qcnt: %llu\n",
1717                    gl->gl_name.ln_type,
1718                    (unsigned long long)gl->gl_name.ln_number,
1719                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTT],
1720                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTVAR],
1721                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTB],
1722                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTVARB],
1723                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SIRT],
1724                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SIRTVAR],
1725                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_DCOUNT],
1726                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_QCOUNT]);
1727         return 0;
1728 }
1729
1730 static const char *gfs2_gltype[] = {
1731         "type",
1732         "reserved",
1733         "nondisk",
1734         "inode",
1735         "rgrp",
1736         "meta",
1737         "iopen",
1738         "flock",
1739         "plock",
1740         "quota",
1741         "journal",
1742 };
1743
1744 static const char *gfs2_stype[] = {
1745         [GFS2_LKS_SRTT]         = "srtt",
1746         [GFS2_LKS_SRTTVAR]      = "srttvar",
1747         [GFS2_LKS_SRTTB]        = "srttb",
1748         [GFS2_LKS_SRTTVARB]     = "srttvarb",
1749         [GFS2_LKS_SIRT]         = "sirt",
1750         [GFS2_LKS_SIRTVAR]      = "sirtvar",
1751         [GFS2_LKS_DCOUNT]       = "dlm",
1752         [GFS2_LKS_QCOUNT]       = "queue",
1753 };
1754
1755 #define GFS2_NR_SBSTATS (ARRAY_SIZE(gfs2_gltype) * ARRAY_SIZE(gfs2_stype))
1756
1757 static int gfs2_sbstats_seq_show(struct seq_file *seq, void *iter_ptr)
1758 {
1759         struct gfs2_sbd *sdp = seq->private;
1760         loff_t pos = *(loff_t *)iter_ptr;
1761         unsigned index = pos >> 3;
1762         unsigned subindex = pos & 0x07;
1763         int i;
1764
1765         if (index == 0 && subindex != 0)
1766                 return 0;
1767
1768         seq_printf(seq, "%-10s %8s:", gfs2_gltype[index],
1769                    (index == 0) ? "cpu": gfs2_stype[subindex]);
1770
1771         for_each_possible_cpu(i) {
1772                 const struct gfs2_pcpu_lkstats *lkstats = per_cpu_ptr(sdp->sd_lkstats, i);
1773
1774                 if (index == 0)
1775                         seq_printf(seq, " %15u", i);
1776                 else
1777                         seq_printf(seq, " %15llu", (unsigned long long)lkstats->
1778                                    lkstats[index - 1].stats[subindex]);
1779         }
1780         seq_putc(seq, '\n');
1781         return 0;
1782 }
1783
1784 int __init gfs2_glock_init(void)
1785 {
1786         int ret;
1787
1788         ret = rhashtable_init(&gl_hash_table, &ht_parms);
1789         if (ret < 0)
1790                 return ret;
1791
1792         glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
1793                                           WQ_HIGHPRI | WQ_FREEZABLE, 0);
1794         if (!glock_workqueue) {
1795                 rhashtable_destroy(&gl_hash_table);
1796                 return -ENOMEM;
1797         }
1798         gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
1799                                                 WQ_MEM_RECLAIM | WQ_FREEZABLE,
1800                                                 0);
1801         if (!gfs2_delete_workqueue) {
1802                 destroy_workqueue(glock_workqueue);
1803                 rhashtable_destroy(&gl_hash_table);
1804                 return -ENOMEM;
1805         }
1806
1807         ret = register_shrinker(&glock_shrinker);
1808         if (ret) {
1809                 destroy_workqueue(gfs2_delete_workqueue);
1810                 destroy_workqueue(glock_workqueue);
1811                 rhashtable_destroy(&gl_hash_table);
1812                 return ret;
1813         }
1814
1815         return 0;
1816 }
1817
1818 void gfs2_glock_exit(void)
1819 {
1820         unregister_shrinker(&glock_shrinker);
1821         rhashtable_destroy(&gl_hash_table);
1822         destroy_workqueue(glock_workqueue);
1823         destroy_workqueue(gfs2_delete_workqueue);
1824 }
1825
1826 static void gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1827 {
1828         while ((gi->gl = rhashtable_walk_next(&gi->hti))) {
1829                 if (IS_ERR(gi->gl)) {
1830                         if (PTR_ERR(gi->gl) == -EAGAIN)
1831                                 continue;
1832                         gi->gl = NULL;
1833                         return;
1834                 }
1835                 /* Skip entries for other sb and dead entries */
1836                 if (gi->sdp == gi->gl->gl_name.ln_sbd &&
1837                     !__lockref_is_dead(&gi->gl->gl_lockref))
1838                         return;
1839         }
1840 }
1841
1842 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1843 {
1844         struct gfs2_glock_iter *gi = seq->private;
1845         loff_t n = *pos;
1846
1847         rhashtable_walk_enter(&gl_hash_table, &gi->hti);
1848         if (rhashtable_walk_start(&gi->hti) != 0)
1849                 return NULL;
1850
1851         do {
1852                 gfs2_glock_iter_next(gi);
1853         } while (gi->gl && n--);
1854
1855         gi->last_pos = *pos;
1856
1857         return gi->gl;
1858 }
1859
1860 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1861                                  loff_t *pos)
1862 {
1863         struct gfs2_glock_iter *gi = seq->private;
1864
1865         (*pos)++;
1866         gi->last_pos = *pos;
1867         gfs2_glock_iter_next(gi);
1868
1869         return gi->gl;
1870 }
1871
1872 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1873 {
1874         struct gfs2_glock_iter *gi = seq->private;
1875
1876         gi->gl = NULL;
1877         rhashtable_walk_stop(&gi->hti);
1878         rhashtable_walk_exit(&gi->hti);
1879 }
1880
1881 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1882 {
1883         dump_glock(seq, iter_ptr);
1884         return 0;
1885 }
1886
1887 static void *gfs2_sbstats_seq_start(struct seq_file *seq, loff_t *pos)
1888 {
1889         preempt_disable();
1890         if (*pos >= GFS2_NR_SBSTATS)
1891                 return NULL;
1892         return pos;
1893 }
1894
1895 static void *gfs2_sbstats_seq_next(struct seq_file *seq, void *iter_ptr,
1896                                    loff_t *pos)
1897 {
1898         (*pos)++;
1899         if (*pos >= GFS2_NR_SBSTATS)
1900                 return NULL;
1901         return pos;
1902 }
1903
1904 static void gfs2_sbstats_seq_stop(struct seq_file *seq, void *iter_ptr)
1905 {
1906         preempt_enable();
1907 }
1908
1909 static const struct seq_operations gfs2_glock_seq_ops = {
1910         .start = gfs2_glock_seq_start,
1911         .next  = gfs2_glock_seq_next,
1912         .stop  = gfs2_glock_seq_stop,
1913         .show  = gfs2_glock_seq_show,
1914 };
1915
1916 static const struct seq_operations gfs2_glstats_seq_ops = {
1917         .start = gfs2_glock_seq_start,
1918         .next  = gfs2_glock_seq_next,
1919         .stop  = gfs2_glock_seq_stop,
1920         .show  = gfs2_glstats_seq_show,
1921 };
1922
1923 static const struct seq_operations gfs2_sbstats_seq_ops = {
1924         .start = gfs2_sbstats_seq_start,
1925         .next  = gfs2_sbstats_seq_next,
1926         .stop  = gfs2_sbstats_seq_stop,
1927         .show  = gfs2_sbstats_seq_show,
1928 };
1929
1930 #define GFS2_SEQ_GOODSIZE min(PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER, 65536UL)
1931
1932 static int gfs2_glocks_open(struct inode *inode, struct file *file)
1933 {
1934         int ret = seq_open_private(file, &gfs2_glock_seq_ops,
1935                                    sizeof(struct gfs2_glock_iter));
1936         if (ret == 0) {
1937                 struct seq_file *seq = file->private_data;
1938                 struct gfs2_glock_iter *gi = seq->private;
1939
1940                 gi->sdp = inode->i_private;
1941                 seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
1942                 if (seq->buf)
1943                         seq->size = GFS2_SEQ_GOODSIZE;
1944                 gi->gl = NULL;
1945         }
1946         return ret;
1947 }
1948
1949 static int gfs2_glocks_release(struct inode *inode, struct file *file)
1950 {
1951         struct seq_file *seq = file->private_data;
1952         struct gfs2_glock_iter *gi = seq->private;
1953
1954         gi->gl = NULL;
1955         return seq_release_private(inode, file);
1956 }
1957
1958 static int gfs2_glstats_open(struct inode *inode, struct file *file)
1959 {
1960         int ret = seq_open_private(file, &gfs2_glstats_seq_ops,
1961                                    sizeof(struct gfs2_glock_iter));
1962         if (ret == 0) {
1963                 struct seq_file *seq = file->private_data;
1964                 struct gfs2_glock_iter *gi = seq->private;
1965                 gi->sdp = inode->i_private;
1966                 seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
1967                 if (seq->buf)
1968                         seq->size = GFS2_SEQ_GOODSIZE;
1969                 gi->gl = NULL;
1970         }
1971         return ret;
1972 }
1973
1974 static int gfs2_sbstats_open(struct inode *inode, struct file *file)
1975 {
1976         int ret = seq_open(file, &gfs2_sbstats_seq_ops);
1977         if (ret == 0) {
1978                 struct seq_file *seq = file->private_data;
1979                 seq->private = inode->i_private;  /* sdp */
1980         }
1981         return ret;
1982 }
1983
1984 static const struct file_operations gfs2_glocks_fops = {
1985         .owner   = THIS_MODULE,
1986         .open    = gfs2_glocks_open,
1987         .read    = seq_read,
1988         .llseek  = seq_lseek,
1989         .release = gfs2_glocks_release,
1990 };
1991
1992 static const struct file_operations gfs2_glstats_fops = {
1993         .owner   = THIS_MODULE,
1994         .open    = gfs2_glstats_open,
1995         .read    = seq_read,
1996         .llseek  = seq_lseek,
1997         .release = gfs2_glocks_release,
1998 };
1999
2000 static const struct file_operations gfs2_sbstats_fops = {
2001         .owner   = THIS_MODULE,
2002         .open    = gfs2_sbstats_open,
2003         .read    = seq_read,
2004         .llseek  = seq_lseek,
2005         .release = seq_release,
2006 };
2007
2008 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
2009 {
2010         struct dentry *dent;
2011
2012         dent = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
2013         if (IS_ERR_OR_NULL(dent))
2014                 goto fail;
2015         sdp->debugfs_dir = dent;
2016
2017         dent = debugfs_create_file("glocks",
2018                                    S_IFREG | S_IRUGO,
2019                                    sdp->debugfs_dir, sdp,
2020                                    &gfs2_glocks_fops);
2021         if (IS_ERR_OR_NULL(dent))
2022                 goto fail;
2023         sdp->debugfs_dentry_glocks = dent;
2024
2025         dent = debugfs_create_file("glstats",
2026                                    S_IFREG | S_IRUGO,
2027                                    sdp->debugfs_dir, sdp,
2028                                    &gfs2_glstats_fops);
2029         if (IS_ERR_OR_NULL(dent))
2030                 goto fail;
2031         sdp->debugfs_dentry_glstats = dent;
2032
2033         dent = debugfs_create_file("sbstats",
2034                                    S_IFREG | S_IRUGO,
2035                                    sdp->debugfs_dir, sdp,
2036                                    &gfs2_sbstats_fops);
2037         if (IS_ERR_OR_NULL(dent))
2038                 goto fail;
2039         sdp->debugfs_dentry_sbstats = dent;
2040
2041         return 0;
2042 fail:
2043         gfs2_delete_debugfs_file(sdp);
2044         return dent ? PTR_ERR(dent) : -ENOMEM;
2045 }
2046
2047 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
2048 {
2049         if (sdp->debugfs_dir) {
2050                 if (sdp->debugfs_dentry_glocks) {
2051                         debugfs_remove(sdp->debugfs_dentry_glocks);
2052                         sdp->debugfs_dentry_glocks = NULL;
2053                 }
2054                 if (sdp->debugfs_dentry_glstats) {
2055                         debugfs_remove(sdp->debugfs_dentry_glstats);
2056                         sdp->debugfs_dentry_glstats = NULL;
2057                 }
2058                 if (sdp->debugfs_dentry_sbstats) {
2059                         debugfs_remove(sdp->debugfs_dentry_sbstats);
2060                         sdp->debugfs_dentry_sbstats = NULL;
2061                 }
2062                 debugfs_remove(sdp->debugfs_dir);
2063                 sdp->debugfs_dir = NULL;
2064         }
2065 }
2066
2067 int gfs2_register_debugfs(void)
2068 {
2069         gfs2_root = debugfs_create_dir("gfs2", NULL);
2070         if (IS_ERR(gfs2_root))
2071                 return PTR_ERR(gfs2_root);
2072         return gfs2_root ? 0 : -ENOMEM;
2073 }
2074
2075 void gfs2_unregister_debugfs(void)
2076 {
2077         debugfs_remove(gfs2_root);
2078         gfs2_root = NULL;
2079 }