linux/fs/gfs2/glock.c
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   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
  48struct 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
  56typedef void (*glock_examiner) (struct gfs2_glock * gl);
  57
  58static 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)
  60static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
  61
  62static struct dentry *gfs2_root;
  63static struct workqueue_struct *glock_workqueue;
  64struct workqueue_struct *gfs2_delete_workqueue;
  65static LIST_HEAD(lru_list);
  66static atomic_t lru_count = ATOMIC_INIT(0);
  67static 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
  73static struct hlist_bl_head gl_hash_table[GFS2_GL_HASH_SIZE];
  74static 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
  83static 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
  96static inline void spin_lock_bucket(unsigned int hash)
  97{
  98        hlist_bl_lock(&gl_hash_table[hash]);
  99}
 100
 101static inline void spin_unlock_bucket(unsigned int hash)
 102{
 103        hlist_bl_unlock(&gl_hash_table[hash]);
 104}
 105
 106static 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
 116void 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
 131void 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
 144static 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
 158void 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
 172static 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
 181static 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
 196static 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
 210void 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
 222void 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
 248static 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
 275static 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
 296static 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
 308static 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
 335static 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
 343restart:
 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
 386static 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
 404static 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
 428static 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
 443static 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:
 482retry:
 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        }
 515out:
 516        clear_bit(GLF_LOCK, &gl->gl_flags);
 517out_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
 529static 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
 579static 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
 598static 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);
 633out:
 634        return;
 635
 636out_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
 644out_unlock:
 645        clear_bit(GLF_LOCK, &gl->gl_flags);
 646        smp_mb__after_clear_bit();
 647        return;
 648}
 649
 650static 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
 672static 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
 724int 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
 816void 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
 840void 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
 857void 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
 874static int gfs2_glock_holder_wait(void *word)
 875{
 876        schedule();
 877        return 0;
 878}
 879
 880static int gfs2_glock_demote_wait(void *word)
 881{
 882        schedule();
 883        return 0;
 884}
 885
 886static 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
 899static 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
 914static 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
 939int gfs2_glock_wait(struct gfs2_holder *gh)
 940{
 941        wait_on_holder(gh);
 942        return gh->gh_error;
 943}
 944
 945void 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
 974static 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)) {
1002fail:
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);
1023do_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
1033trap_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
1055int 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
1088int 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
1099void 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
1140void 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
1153void 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
1171int 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
1194static 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
1218static 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
1253int 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
1288void 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
1301void 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
1307void 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
1341static 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
1369void 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
1393static 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);
1441out:
1442        return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
1443}
1444
1445static 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
1458static 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
1474static 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
1491static 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
1507static 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
1526void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1527{
1528        glock_hash_walk(thaw_glock, sdp);
1529}
1530
1531static 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
1540static 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
1553void 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
1561void 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
1575static 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
1590static 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
1627static 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
1644static 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
1699static 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);
1729out:
1730        return error;
1731}
1732
1733static 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
1751static 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
1765static 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
1778static 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
1806int __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
1830void gfs2_glock_exit(void)
1831{
1832        unregister_shrinker(&glock_shrinker);
1833        destroy_workqueue(glock_workqueue);
1834        destroy_workqueue(gfs2_delete_workqueue);
1835}
1836
1837static 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
1843static 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
1849static 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
1881static 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
1903static 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
1916static 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
1925static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1926{
1927        return dump_glock(seq, iter_ptr);
1928}
1929
1930static 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
1941static 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
1954static void gfs2_sbstats_seq_stop(struct seq_file *seq, void *iter_ptr)
1955{
1956        preempt_enable();
1957}
1958
1959static 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
1966static 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
1973static 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
1982static 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
1997static 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
2012static 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
2024static 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
2032static 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
2040static 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
2048int 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;
2075fail:
2076        gfs2_delete_debugfs_file(sdp);
2077        return -ENOMEM;
2078}
2079
2080void 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
2100int gfs2_register_debugfs(void)
2101{
2102        gfs2_root = debugfs_create_dir("gfs2", NULL);
2103        return gfs2_root ? 0 : -ENOMEM;
2104}
2105
2106void gfs2_unregister_debugfs(void)
2107{
2108        debugfs_remove(gfs2_root);
2109        gfs2_root = NULL;
2110}
2111
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