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_put_nolock() - Decrement reference count on glock
 190 * @gl: The glock to put
 191 *
 192 * This function should only be used if the caller has its own reference
 193 * to the glock, in addition to the one it is dropping.
 194 */
 195
 196void gfs2_glock_put_nolock(struct gfs2_glock *gl)
 197{
 198        if (atomic_dec_and_test(&gl->gl_ref))
 199                GLOCK_BUG_ON(gl, 1);
 200}
 201
 202/**
 203 * gfs2_glock_put() - Decrement reference count on glock
 204 * @gl: The glock to put
 205 *
 206 */
 207
 208void gfs2_glock_put(struct gfs2_glock *gl)
 209{
 210        struct gfs2_sbd *sdp = gl->gl_sbd;
 211        struct address_space *mapping = gfs2_glock2aspace(gl);
 212
 213        if (atomic_dec_and_lock(&gl->gl_ref, &lru_lock)) {
 214                __gfs2_glock_remove_from_lru(gl);
 215                spin_unlock(&lru_lock);
 216                spin_lock_bucket(gl->gl_hash);
 217                hlist_bl_del_rcu(&gl->gl_list);
 218                spin_unlock_bucket(gl->gl_hash);
 219                GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
 220                GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
 221                trace_gfs2_glock_put(gl);
 222                sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
 223        }
 224}
 225
 226/**
 227 * search_bucket() - Find struct gfs2_glock by lock number
 228 * @bucket: the bucket to search
 229 * @name: The lock name
 230 *
 231 * Returns: NULL, or the struct gfs2_glock with the requested number
 232 */
 233
 234static struct gfs2_glock *search_bucket(unsigned int hash,
 235                                        const struct gfs2_sbd *sdp,
 236                                        const struct lm_lockname *name)
 237{
 238        struct gfs2_glock *gl;
 239        struct hlist_bl_node *h;
 240
 241        hlist_bl_for_each_entry_rcu(gl, h, &gl_hash_table[hash], gl_list) {
 242                if (!lm_name_equal(&gl->gl_name, name))
 243                        continue;
 244                if (gl->gl_sbd != sdp)
 245                        continue;
 246                if (atomic_inc_not_zero(&gl->gl_ref))
 247                        return gl;
 248        }
 249
 250        return NULL;
 251}
 252
 253/**
 254 * may_grant - check if its ok to grant a new lock
 255 * @gl: The glock
 256 * @gh: The lock request which we wish to grant
 257 *
 258 * Returns: true if its ok to grant the lock
 259 */
 260
 261static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
 262{
 263        const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
 264        if ((gh->gh_state == LM_ST_EXCLUSIVE ||
 265             gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
 266                return 0;
 267        if (gl->gl_state == gh->gh_state)
 268                return 1;
 269        if (gh->gh_flags & GL_EXACT)
 270                return 0;
 271        if (gl->gl_state == LM_ST_EXCLUSIVE) {
 272                if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
 273                        return 1;
 274                if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
 275                        return 1;
 276        }
 277        if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
 278                return 1;
 279        return 0;
 280}
 281
 282static void gfs2_holder_wake(struct gfs2_holder *gh)
 283{
 284        clear_bit(HIF_WAIT, &gh->gh_iflags);
 285        smp_mb__after_clear_bit();
 286        wake_up_bit(&gh->gh_iflags, HIF_WAIT);
 287}
 288
 289/**
 290 * do_error - Something unexpected has happened during a lock request
 291 *
 292 */
 293
 294static inline void do_error(struct gfs2_glock *gl, const int ret)
 295{
 296        struct gfs2_holder *gh, *tmp;
 297
 298        list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 299                if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 300                        continue;
 301                if (ret & LM_OUT_ERROR)
 302                        gh->gh_error = -EIO;
 303                else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
 304                        gh->gh_error = GLR_TRYFAILED;
 305                else
 306                        continue;
 307                list_del_init(&gh->gh_list);
 308                trace_gfs2_glock_queue(gh, 0);
 309                gfs2_holder_wake(gh);
 310        }
 311}
 312
 313/**
 314 * do_promote - promote as many requests as possible on the current queue
 315 * @gl: The glock
 316 * 
 317 * Returns: 1 if there is a blocked holder at the head of the list, or 2
 318 *          if a type specific operation is underway.
 319 */
 320
 321static int do_promote(struct gfs2_glock *gl)
 322__releases(&gl->gl_spin)
 323__acquires(&gl->gl_spin)
 324{
 325        const struct gfs2_glock_operations *glops = gl->gl_ops;
 326        struct gfs2_holder *gh, *tmp;
 327        int ret;
 328
 329restart:
 330        list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 331                if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 332                        continue;
 333                if (may_grant(gl, gh)) {
 334                        if (gh->gh_list.prev == &gl->gl_holders &&
 335                            glops->go_lock) {
 336                                spin_unlock(&gl->gl_spin);
 337                                /* FIXME: eliminate this eventually */
 338                                ret = glops->go_lock(gh);
 339                                spin_lock(&gl->gl_spin);
 340                                if (ret) {
 341                                        if (ret == 1)
 342                                                return 2;
 343                                        gh->gh_error = ret;
 344                                        list_del_init(&gh->gh_list);
 345                                        trace_gfs2_glock_queue(gh, 0);
 346                                        gfs2_holder_wake(gh);
 347                                        goto restart;
 348                                }
 349                                set_bit(HIF_HOLDER, &gh->gh_iflags);
 350                                trace_gfs2_promote(gh, 1);
 351                                gfs2_holder_wake(gh);
 352                                goto restart;
 353                        }
 354                        set_bit(HIF_HOLDER, &gh->gh_iflags);
 355                        trace_gfs2_promote(gh, 0);
 356                        gfs2_holder_wake(gh);
 357                        continue;
 358                }
 359                if (gh->gh_list.prev == &gl->gl_holders)
 360                        return 1;
 361                do_error(gl, 0);
 362                break;
 363        }
 364        return 0;
 365}
 366
 367/**
 368 * find_first_waiter - find the first gh that's waiting for the glock
 369 * @gl: the glock
 370 */
 371
 372static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
 373{
 374        struct gfs2_holder *gh;
 375
 376        list_for_each_entry(gh, &gl->gl_holders, gh_list) {
 377                if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
 378                        return gh;
 379        }
 380        return NULL;
 381}
 382
 383/**
 384 * state_change - record that the glock is now in a different state
 385 * @gl: the glock
 386 * @new_state the new state
 387 *
 388 */
 389
 390static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 391{
 392        int held1, held2;
 393
 394        held1 = (gl->gl_state != LM_ST_UNLOCKED);
 395        held2 = (new_state != LM_ST_UNLOCKED);
 396
 397        if (held1 != held2) {
 398                if (held2)
 399                        gfs2_glock_hold(gl);
 400                else
 401                        gfs2_glock_put_nolock(gl);
 402        }
 403        if (held1 && held2 && list_empty(&gl->gl_holders))
 404                clear_bit(GLF_QUEUED, &gl->gl_flags);
 405
 406        if (new_state != gl->gl_target)
 407                /* shorten our minimum hold time */
 408                gl->gl_hold_time = max(gl->gl_hold_time - GL_GLOCK_HOLD_DECR,
 409                                       GL_GLOCK_MIN_HOLD);
 410        gl->gl_state = new_state;
 411        gl->gl_tchange = jiffies;
 412}
 413
 414static void gfs2_demote_wake(struct gfs2_glock *gl)
 415{
 416        gl->gl_demote_state = LM_ST_EXCLUSIVE;
 417        clear_bit(GLF_DEMOTE, &gl->gl_flags);
 418        smp_mb__after_clear_bit();
 419        wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
 420}
 421
 422/**
 423 * finish_xmote - The DLM has replied to one of our lock requests
 424 * @gl: The glock
 425 * @ret: The status from the DLM
 426 *
 427 */
 428
 429static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
 430{
 431        const struct gfs2_glock_operations *glops = gl->gl_ops;
 432        struct gfs2_holder *gh;
 433        unsigned state = ret & LM_OUT_ST_MASK;
 434        int rv;
 435
 436        spin_lock(&gl->gl_spin);
 437        trace_gfs2_glock_state_change(gl, state);
 438        state_change(gl, state);
 439        gh = find_first_waiter(gl);
 440
 441        /* Demote to UN request arrived during demote to SH or DF */
 442        if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
 443            state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
 444                gl->gl_target = LM_ST_UNLOCKED;
 445
 446        /* Check for state != intended state */
 447        if (unlikely(state != gl->gl_target)) {
 448                if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
 449                        /* move to back of queue and try next entry */
 450                        if (ret & LM_OUT_CANCELED) {
 451                                if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
 452                                        list_move_tail(&gh->gh_list, &gl->gl_holders);
 453                                gh = find_first_waiter(gl);
 454                                gl->gl_target = gh->gh_state;
 455                                goto retry;
 456                        }
 457                        /* Some error or failed "try lock" - report it */
 458                        if ((ret & LM_OUT_ERROR) ||
 459                            (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 460                                gl->gl_target = gl->gl_state;
 461                                do_error(gl, ret);
 462                                goto out;
 463                        }
 464                }
 465                switch(state) {
 466                /* Unlocked due to conversion deadlock, try again */
 467                case LM_ST_UNLOCKED:
 468retry:
 469                        do_xmote(gl, gh, gl->gl_target);
 470                        break;
 471                /* Conversion fails, unlock and try again */
 472                case LM_ST_SHARED:
 473                case LM_ST_DEFERRED:
 474                        do_xmote(gl, gh, LM_ST_UNLOCKED);
 475                        break;
 476                default: /* Everything else */
 477                        printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
 478                        GLOCK_BUG_ON(gl, 1);
 479                }
 480                spin_unlock(&gl->gl_spin);
 481                return;
 482        }
 483
 484        /* Fast path - we got what we asked for */
 485        if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
 486                gfs2_demote_wake(gl);
 487        if (state != LM_ST_UNLOCKED) {
 488                if (glops->go_xmote_bh) {
 489                        spin_unlock(&gl->gl_spin);
 490                        rv = glops->go_xmote_bh(gl, gh);
 491                        spin_lock(&gl->gl_spin);
 492                        if (rv) {
 493                                do_error(gl, rv);
 494                                goto out;
 495                        }
 496                }
 497                rv = do_promote(gl);
 498                if (rv == 2)
 499                        goto out_locked;
 500        }
 501out:
 502        clear_bit(GLF_LOCK, &gl->gl_flags);
 503out_locked:
 504        spin_unlock(&gl->gl_spin);
 505}
 506
 507/**
 508 * do_xmote - Calls the DLM to change the state of a lock
 509 * @gl: The lock state
 510 * @gh: The holder (only for promotes)
 511 * @target: The target lock state
 512 *
 513 */
 514
 515static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
 516__releases(&gl->gl_spin)
 517__acquires(&gl->gl_spin)
 518{
 519        const struct gfs2_glock_operations *glops = gl->gl_ops;
 520        struct gfs2_sbd *sdp = gl->gl_sbd;
 521        unsigned int lck_flags = gh ? gh->gh_flags : 0;
 522        int ret;
 523
 524        lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
 525                      LM_FLAG_PRIORITY);
 526        GLOCK_BUG_ON(gl, gl->gl_state == target);
 527        GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
 528        if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
 529            glops->go_inval) {
 530                set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 531                do_error(gl, 0); /* Fail queued try locks */
 532        }
 533        gl->gl_req = target;
 534        set_bit(GLF_BLOCKING, &gl->gl_flags);
 535        if ((gl->gl_req == LM_ST_UNLOCKED) ||
 536            (gl->gl_state == LM_ST_EXCLUSIVE) ||
 537            (lck_flags & (LM_FLAG_TRY|LM_FLAG_TRY_1CB)))
 538                clear_bit(GLF_BLOCKING, &gl->gl_flags);
 539        spin_unlock(&gl->gl_spin);
 540        if (glops->go_xmote_th)
 541                glops->go_xmote_th(gl);
 542        if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 543                glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
 544        clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 545
 546        gfs2_glock_hold(gl);
 547        if (sdp->sd_lockstruct.ls_ops->lm_lock) {
 548                /* lock_dlm */
 549                ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
 550                GLOCK_BUG_ON(gl, ret);
 551        } else { /* lock_nolock */
 552                finish_xmote(gl, target);
 553                if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 554                        gfs2_glock_put(gl);
 555        }
 556
 557        spin_lock(&gl->gl_spin);
 558}
 559
 560/**
 561 * find_first_holder - find the first "holder" gh
 562 * @gl: the glock
 563 */
 564
 565static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
 566{
 567        struct gfs2_holder *gh;
 568
 569        if (!list_empty(&gl->gl_holders)) {
 570                gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 571                if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 572                        return gh;
 573        }
 574        return NULL;
 575}
 576
 577/**
 578 * run_queue - do all outstanding tasks related to a glock
 579 * @gl: The glock in question
 580 * @nonblock: True if we must not block in run_queue
 581 *
 582 */
 583
 584static void run_queue(struct gfs2_glock *gl, const int nonblock)
 585__releases(&gl->gl_spin)
 586__acquires(&gl->gl_spin)
 587{
 588        struct gfs2_holder *gh = NULL;
 589        int ret;
 590
 591        if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 592                return;
 593
 594        GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
 595
 596        if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
 597            gl->gl_demote_state != gl->gl_state) {
 598                if (find_first_holder(gl))
 599                        goto out_unlock;
 600                if (nonblock)
 601                        goto out_sched;
 602                set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
 603                GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
 604                gl->gl_target = gl->gl_demote_state;
 605        } else {
 606                if (test_bit(GLF_DEMOTE, &gl->gl_flags))
 607                        gfs2_demote_wake(gl);
 608                ret = do_promote(gl);
 609                if (ret == 0)
 610                        goto out_unlock;
 611                if (ret == 2)
 612                        goto out;
 613                gh = find_first_waiter(gl);
 614                gl->gl_target = gh->gh_state;
 615                if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 616                        do_error(gl, 0); /* Fail queued try locks */
 617        }
 618        do_xmote(gl, gh, gl->gl_target);
 619out:
 620        return;
 621
 622out_sched:
 623        clear_bit(GLF_LOCK, &gl->gl_flags);
 624        smp_mb__after_clear_bit();
 625        gfs2_glock_hold(gl);
 626        if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 627                gfs2_glock_put_nolock(gl);
 628        return;
 629
 630out_unlock:
 631        clear_bit(GLF_LOCK, &gl->gl_flags);
 632        smp_mb__after_clear_bit();
 633        return;
 634}
 635
 636static void delete_work_func(struct work_struct *work)
 637{
 638        struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
 639        struct gfs2_sbd *sdp = gl->gl_sbd;
 640        struct gfs2_inode *ip;
 641        struct inode *inode;
 642        u64 no_addr = gl->gl_name.ln_number;
 643
 644        ip = gl->gl_object;
 645        /* Note: Unsafe to dereference ip as we don't hold right refs/locks */
 646
 647        if (ip)
 648                inode = gfs2_ilookup(sdp->sd_vfs, no_addr, 1);
 649        else
 650                inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
 651        if (inode && !IS_ERR(inode)) {
 652                d_prune_aliases(inode);
 653                iput(inode);
 654        }
 655        gfs2_glock_put(gl);
 656}
 657
 658static void glock_work_func(struct work_struct *work)
 659{
 660        unsigned long delay = 0;
 661        struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
 662        int drop_ref = 0;
 663
 664        if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
 665                finish_xmote(gl, gl->gl_reply);
 666                drop_ref = 1;
 667        }
 668        spin_lock(&gl->gl_spin);
 669        if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
 670            gl->gl_state != LM_ST_UNLOCKED &&
 671            gl->gl_demote_state != LM_ST_EXCLUSIVE) {
 672                unsigned long holdtime, now = jiffies;
 673
 674                holdtime = gl->gl_tchange + gl->gl_hold_time;
 675                if (time_before(now, holdtime))
 676                        delay = holdtime - now;
 677
 678                if (!delay) {
 679                        clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
 680                        set_bit(GLF_DEMOTE, &gl->gl_flags);
 681                }
 682        }
 683        run_queue(gl, 0);
 684        spin_unlock(&gl->gl_spin);
 685        if (!delay)
 686                gfs2_glock_put(gl);
 687        else {
 688                if (gl->gl_name.ln_type != LM_TYPE_INODE)
 689                        delay = 0;
 690                if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
 691                        gfs2_glock_put(gl);
 692        }
 693        if (drop_ref)
 694                gfs2_glock_put(gl);
 695}
 696
 697/**
 698 * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
 699 * @sdp: The GFS2 superblock
 700 * @number: the lock number
 701 * @glops: The glock_operations to use
 702 * @create: If 0, don't create the glock if it doesn't exist
 703 * @glp: the glock is returned here
 704 *
 705 * This does not lock a glock, just finds/creates structures for one.
 706 *
 707 * Returns: errno
 708 */
 709
 710int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 711                   const struct gfs2_glock_operations *glops, int create,
 712                   struct gfs2_glock **glp)
 713{
 714        struct super_block *s = sdp->sd_vfs;
 715        struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
 716        struct gfs2_glock *gl, *tmp;
 717        unsigned int hash = gl_hash(sdp, &name);
 718        struct address_space *mapping;
 719        struct kmem_cache *cachep;
 720
 721        rcu_read_lock();
 722        gl = search_bucket(hash, sdp, &name);
 723        rcu_read_unlock();
 724
 725        *glp = gl;
 726        if (gl)
 727                return 0;
 728        if (!create)
 729                return -ENOENT;
 730
 731        if (glops->go_flags & GLOF_ASPACE)
 732                cachep = gfs2_glock_aspace_cachep;
 733        else
 734                cachep = gfs2_glock_cachep;
 735        gl = kmem_cache_alloc(cachep, GFP_KERNEL);
 736        if (!gl)
 737                return -ENOMEM;
 738
 739        atomic_inc(&sdp->sd_glock_disposal);
 740        gl->gl_sbd = sdp;
 741        gl->gl_flags = 0;
 742        gl->gl_name = name;
 743        atomic_set(&gl->gl_ref, 1);
 744        gl->gl_state = LM_ST_UNLOCKED;
 745        gl->gl_target = LM_ST_UNLOCKED;
 746        gl->gl_demote_state = LM_ST_EXCLUSIVE;
 747        gl->gl_hash = hash;
 748        gl->gl_ops = glops;
 749        gl->gl_dstamp = ktime_set(0, 0);
 750        preempt_disable();
 751        /* We use the global stats to estimate the initial per-glock stats */
 752        gl->gl_stats = this_cpu_ptr(sdp->sd_lkstats)->lkstats[glops->go_type];
 753        preempt_enable();
 754        gl->gl_stats.stats[GFS2_LKS_DCOUNT] = 0;
 755        gl->gl_stats.stats[GFS2_LKS_QCOUNT] = 0;
 756        memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
 757        memset(gl->gl_lvb, 0, 32 * sizeof(char));
 758        gl->gl_lksb.sb_lvbptr = gl->gl_lvb;
 759        gl->gl_tchange = jiffies;
 760        gl->gl_object = NULL;
 761        gl->gl_hold_time = GL_GLOCK_DFT_HOLD;
 762        INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
 763        INIT_WORK(&gl->gl_delete, delete_work_func);
 764
 765        mapping = gfs2_glock2aspace(gl);
 766        if (mapping) {
 767                mapping->a_ops = &gfs2_meta_aops;
 768                mapping->host = s->s_bdev->bd_inode;
 769                mapping->flags = 0;
 770                mapping_set_gfp_mask(mapping, GFP_NOFS);
 771                mapping->assoc_mapping = NULL;
 772                mapping->backing_dev_info = s->s_bdi;
 773                mapping->writeback_index = 0;
 774        }
 775
 776        spin_lock_bucket(hash);
 777        tmp = search_bucket(hash, sdp, &name);
 778        if (tmp) {
 779                spin_unlock_bucket(hash);
 780                kmem_cache_free(cachep, gl);
 781                atomic_dec(&sdp->sd_glock_disposal);
 782                gl = tmp;
 783        } else {
 784                hlist_bl_add_head_rcu(&gl->gl_list, &gl_hash_table[hash]);
 785                spin_unlock_bucket(hash);
 786        }
 787
 788        *glp = gl;
 789
 790        return 0;
 791}
 792
 793/**
 794 * gfs2_holder_init - initialize a struct gfs2_holder in the default way
 795 * @gl: the glock
 796 * @state: the state we're requesting
 797 * @flags: the modifier flags
 798 * @gh: the holder structure
 799 *
 800 */
 801
 802void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
 803                      struct gfs2_holder *gh)
 804{
 805        INIT_LIST_HEAD(&gh->gh_list);
 806        gh->gh_gl = gl;
 807        gh->gh_ip = (unsigned long)__builtin_return_address(0);
 808        gh->gh_owner_pid = get_pid(task_pid(current));
 809        gh->gh_state = state;
 810        gh->gh_flags = flags;
 811        gh->gh_error = 0;
 812        gh->gh_iflags = 0;
 813        gfs2_glock_hold(gl);
 814}
 815
 816/**
 817 * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
 818 * @state: the state we're requesting
 819 * @flags: the modifier flags
 820 * @gh: the holder structure
 821 *
 822 * Don't mess with the glock.
 823 *
 824 */
 825
 826void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
 827{
 828        gh->gh_state = state;
 829        gh->gh_flags = flags;
 830        gh->gh_iflags = 0;
 831        gh->gh_ip = (unsigned long)__builtin_return_address(0);
 832        if (gh->gh_owner_pid)
 833                put_pid(gh->gh_owner_pid);
 834        gh->gh_owner_pid = get_pid(task_pid(current));
 835}
 836
 837/**
 838 * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 839 * @gh: the holder structure
 840 *
 841 */
 842
 843void gfs2_holder_uninit(struct gfs2_holder *gh)
 844{
 845        put_pid(gh->gh_owner_pid);
 846        gfs2_glock_put(gh->gh_gl);
 847        gh->gh_gl = NULL;
 848        gh->gh_ip = 0;
 849}
 850
 851/**
 852 * gfs2_glock_holder_wait
 853 * @word: unused
 854 *
 855 * This function and gfs2_glock_demote_wait both show up in the WCHAN
 856 * field. Thus I've separated these otherwise identical functions in
 857 * order to be more informative to the user.
 858 */
 859
 860static int gfs2_glock_holder_wait(void *word)
 861{
 862        schedule();
 863        return 0;
 864}
 865
 866static int gfs2_glock_demote_wait(void *word)
 867{
 868        schedule();
 869        return 0;
 870}
 871
 872/**
 873 * gfs2_glock_wait - wait on a glock acquisition
 874 * @gh: the glock holder
 875 *
 876 * Returns: 0 on success
 877 */
 878
 879int gfs2_glock_wait(struct gfs2_holder *gh)
 880{
 881        unsigned long time1 = jiffies;
 882
 883        might_sleep();
 884        wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
 885        if (time_after(jiffies, time1 + HZ)) /* have we waited > a second? */
 886                /* Lengthen the minimum hold time. */
 887                gh->gh_gl->gl_hold_time = min(gh->gh_gl->gl_hold_time +
 888                                              GL_GLOCK_HOLD_INCR,
 889                                              GL_GLOCK_MAX_HOLD);
 890        return gh->gh_error;
 891}
 892
 893/**
 894 * handle_callback - process a demote request
 895 * @gl: the glock
 896 * @state: the state the caller wants us to change to
 897 *
 898 * There are only two requests that we are going to see in actual
 899 * practise: LM_ST_SHARED and LM_ST_UNLOCKED
 900 */
 901
 902static void handle_callback(struct gfs2_glock *gl, unsigned int state,
 903                            unsigned long delay)
 904{
 905        int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
 906
 907        set_bit(bit, &gl->gl_flags);
 908        if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
 909                gl->gl_demote_state = state;
 910                gl->gl_demote_time = jiffies;
 911        } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
 912                        gl->gl_demote_state != state) {
 913                gl->gl_demote_state = LM_ST_UNLOCKED;
 914        }
 915        if (gl->gl_ops->go_callback)
 916                gl->gl_ops->go_callback(gl);
 917        trace_gfs2_demote_rq(gl);
 918}
 919
 920void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
 921{
 922        struct va_format vaf;
 923        va_list args;
 924
 925        va_start(args, fmt);
 926
 927        if (seq) {
 928                seq_vprintf(seq, fmt, args);
 929        } else {
 930                vaf.fmt = fmt;
 931                vaf.va = &args;
 932
 933                printk(KERN_ERR " %pV", &vaf);
 934        }
 935
 936        va_end(args);
 937}
 938
 939/**
 940 * add_to_queue - Add a holder to the wait queue (but look for recursion)
 941 * @gh: the holder structure to add
 942 *
 943 * Eventually we should move the recursive locking trap to a
 944 * debugging option or something like that. This is the fast
 945 * path and needs to have the minimum number of distractions.
 946 * 
 947 */
 948
 949static inline void add_to_queue(struct gfs2_holder *gh)
 950__releases(&gl->gl_spin)
 951__acquires(&gl->gl_spin)
 952{
 953        struct gfs2_glock *gl = gh->gh_gl;
 954        struct gfs2_sbd *sdp = gl->gl_sbd;
 955        struct list_head *insert_pt = NULL;
 956        struct gfs2_holder *gh2;
 957        int try_futile = 0;
 958
 959        BUG_ON(gh->gh_owner_pid == NULL);
 960        if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
 961                BUG();
 962
 963        if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
 964                if (test_bit(GLF_LOCK, &gl->gl_flags))
 965                        try_futile = !may_grant(gl, gh);
 966                if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 967                        goto fail;
 968        }
 969
 970        list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
 971                if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
 972                    (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
 973                        goto trap_recursive;
 974                if (try_futile &&
 975                    !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 976fail:
 977                        gh->gh_error = GLR_TRYFAILED;
 978                        gfs2_holder_wake(gh);
 979                        return;
 980                }
 981                if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
 982                        continue;
 983                if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
 984                        insert_pt = &gh2->gh_list;
 985        }
 986        set_bit(GLF_QUEUED, &gl->gl_flags);
 987        trace_gfs2_glock_queue(gh, 1);
 988        gfs2_glstats_inc(gl, GFS2_LKS_QCOUNT);
 989        gfs2_sbstats_inc(gl, GFS2_LKS_QCOUNT);
 990        if (likely(insert_pt == NULL)) {
 991                list_add_tail(&gh->gh_list, &gl->gl_holders);
 992                if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
 993                        goto do_cancel;
 994                return;
 995        }
 996        list_add_tail(&gh->gh_list, insert_pt);
 997do_cancel:
 998        gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 999        if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
1000                spin_unlock(&gl->gl_spin);
1001                if (sdp->sd_lockstruct.ls_ops->lm_cancel)
1002                        sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
1003                spin_lock(&gl->gl_spin);
1004        }
1005        return;
1006
1007trap_recursive:
1008        print_symbol(KERN_ERR "original: %s\n", gh2->gh_ip);
1009        printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
1010        printk(KERN_ERR "lock type: %d req lock state : %d\n",
1011               gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
1012        print_symbol(KERN_ERR "new: %s\n", gh->gh_ip);
1013        printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
1014        printk(KERN_ERR "lock type: %d req lock state : %d\n",
1015               gh->gh_gl->gl_name.ln_type, gh->gh_state);
1016        __dump_glock(NULL, gl);
1017        BUG();
1018}
1019
1020/**
1021 * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1022 * @gh: the holder structure
1023 *
1024 * if (gh->gh_flags & GL_ASYNC), this never returns an error
1025 *
1026 * Returns: 0, GLR_TRYFAILED, or errno on failure
1027 */
1028
1029int gfs2_glock_nq(struct gfs2_holder *gh)
1030{
1031        struct gfs2_glock *gl = gh->gh_gl;
1032        struct gfs2_sbd *sdp = gl->gl_sbd;
1033        int error = 0;
1034
1035        if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
1036                return -EIO;
1037
1038        if (test_bit(GLF_LRU, &gl->gl_flags))
1039                gfs2_glock_remove_from_lru(gl);
1040
1041        spin_lock(&gl->gl_spin);
1042        add_to_queue(gh);
1043        if ((LM_FLAG_NOEXP & gh->gh_flags) &&
1044            test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1045                set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1046        run_queue(gl, 1);
1047        spin_unlock(&gl->gl_spin);
1048
1049        if (!(gh->gh_flags & GL_ASYNC))
1050                error = gfs2_glock_wait(gh);
1051
1052        return error;
1053}
1054
1055/**
1056 * gfs2_glock_poll - poll to see if an async request has been completed
1057 * @gh: the holder
1058 *
1059 * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1060 */
1061
1062int gfs2_glock_poll(struct gfs2_holder *gh)
1063{
1064        return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1065}
1066
1067/**
1068 * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1069 * @gh: the glock holder
1070 *
1071 */
1072
1073void gfs2_glock_dq(struct gfs2_holder *gh)
1074{
1075        struct gfs2_glock *gl = gh->gh_gl;
1076        const struct gfs2_glock_operations *glops = gl->gl_ops;
1077        unsigned delay = 0;
1078        int fast_path = 0;
1079
1080        spin_lock(&gl->gl_spin);
1081        if (gh->gh_flags & GL_NOCACHE)
1082                handle_callback(gl, LM_ST_UNLOCKED, 0);
1083
1084        list_del_init(&gh->gh_list);
1085        if (find_first_holder(gl) == NULL) {
1086                if (glops->go_unlock) {
1087                        GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1088                        spin_unlock(&gl->gl_spin);
1089                        glops->go_unlock(gh);
1090                        spin_lock(&gl->gl_spin);
1091                        clear_bit(GLF_LOCK, &gl->gl_flags);
1092                }
1093                if (list_empty(&gl->gl_holders) &&
1094                    !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1095                    !test_bit(GLF_DEMOTE, &gl->gl_flags))
1096                        fast_path = 1;
1097        }
1098        if (!test_bit(GLF_LFLUSH, &gl->gl_flags) && demote_ok(gl))
1099                gfs2_glock_add_to_lru(gl);
1100
1101        trace_gfs2_glock_queue(gh, 0);
1102        spin_unlock(&gl->gl_spin);
1103        if (likely(fast_path))
1104                return;
1105
1106        gfs2_glock_hold(gl);
1107        if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1108            !test_bit(GLF_DEMOTE, &gl->gl_flags) &&
1109            gl->gl_name.ln_type == LM_TYPE_INODE)
1110                delay = gl->gl_hold_time;
1111        if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1112                gfs2_glock_put(gl);
1113}
1114
1115void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1116{
1117        struct gfs2_glock *gl = gh->gh_gl;
1118        gfs2_glock_dq(gh);
1119        might_sleep();
1120        wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
1121}
1122
1123/**
1124 * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1125 * @gh: the holder structure
1126 *
1127 */
1128
1129void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1130{
1131        gfs2_glock_dq(gh);
1132        gfs2_holder_uninit(gh);
1133}
1134
1135/**
1136 * gfs2_glock_nq_num - acquire a glock based on lock number
1137 * @sdp: the filesystem
1138 * @number: the lock number
1139 * @glops: the glock operations for the type of glock
1140 * @state: the state to acquire the glock in
1141 * @flags: modifier flags for the acquisition
1142 * @gh: the struct gfs2_holder
1143 *
1144 * Returns: errno
1145 */
1146
1147int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1148                      const struct gfs2_glock_operations *glops,
1149                      unsigned int state, int flags, struct gfs2_holder *gh)
1150{
1151        struct gfs2_glock *gl;
1152        int error;
1153
1154        error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1155        if (!error) {
1156                error = gfs2_glock_nq_init(gl, state, flags, gh);
1157                gfs2_glock_put(gl);
1158        }
1159
1160        return error;
1161}
1162
1163/**
1164 * glock_compare - Compare two struct gfs2_glock structures for sorting
1165 * @arg_a: the first structure
1166 * @arg_b: the second structure
1167 *
1168 */
1169
1170static int glock_compare(const void *arg_a, const void *arg_b)
1171{
1172        const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1173        const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1174        const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1175        const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1176
1177        if (a->ln_number > b->ln_number)
1178                return 1;
1179        if (a->ln_number < b->ln_number)
1180                return -1;
1181        BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1182        return 0;
1183}
1184
1185/**
1186 * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1187 * @num_gh: the number of structures
1188 * @ghs: an array of struct gfs2_holder structures
1189 *
1190 * Returns: 0 on success (all glocks acquired),
1191 *          errno on failure (no glocks acquired)
1192 */
1193
1194static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1195                     struct gfs2_holder **p)
1196{
1197        unsigned int x;
1198        int error = 0;
1199
1200        for (x = 0; x < num_gh; x++)
1201                p[x] = &ghs[x];
1202
1203        sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1204
1205        for (x = 0; x < num_gh; x++) {
1206                p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1207
1208                error = gfs2_glock_nq(p[x]);
1209                if (error) {
1210                        while (x--)
1211                                gfs2_glock_dq(p[x]);
1212                        break;
1213                }
1214        }
1215
1216        return error;
1217}
1218
1219/**
1220 * gfs2_glock_nq_m - acquire multiple glocks
1221 * @num_gh: the number of structures
1222 * @ghs: an array of struct gfs2_holder structures
1223 *
1224 *
1225 * Returns: 0 on success (all glocks acquired),
1226 *          errno on failure (no glocks acquired)
1227 */
1228
1229int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1230{
1231        struct gfs2_holder *tmp[4];
1232        struct gfs2_holder **pph = tmp;
1233        int error = 0;
1234
1235        switch(num_gh) {
1236        case 0:
1237                return 0;
1238        case 1:
1239                ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1240                return gfs2_glock_nq(ghs);
1241        default:
1242                if (num_gh <= 4)
1243                        break;
1244                pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1245                if (!pph)
1246                        return -ENOMEM;
1247        }
1248
1249        error = nq_m_sync(num_gh, ghs, pph);
1250
1251        if (pph != tmp)
1252                kfree(pph);
1253
1254        return error;
1255}
1256
1257/**
1258 * gfs2_glock_dq_m - release multiple glocks
1259 * @num_gh: the number of structures
1260 * @ghs: an array of struct gfs2_holder structures
1261 *
1262 */
1263
1264void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1265{
1266        while (num_gh--)
1267                gfs2_glock_dq(&ghs[num_gh]);
1268}
1269
1270/**
1271 * gfs2_glock_dq_uninit_m - release multiple glocks
1272 * @num_gh: the number of structures
1273 * @ghs: an array of struct gfs2_holder structures
1274 *
1275 */
1276
1277void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1278{
1279        while (num_gh--)
1280                gfs2_glock_dq_uninit(&ghs[num_gh]);
1281}
1282
1283void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1284{
1285        unsigned long delay = 0;
1286        unsigned long holdtime;
1287        unsigned long now = jiffies;
1288
1289        gfs2_glock_hold(gl);
1290        holdtime = gl->gl_tchange + gl->gl_hold_time;
1291        if (test_bit(GLF_QUEUED, &gl->gl_flags) &&
1292            gl->gl_name.ln_type == LM_TYPE_INODE) {
1293                if (time_before(now, holdtime))
1294                        delay = holdtime - now;
1295                if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1296                        delay = gl->gl_hold_time;
1297        }
1298
1299        spin_lock(&gl->gl_spin);
1300        handle_callback(gl, state, delay);
1301        spin_unlock(&gl->gl_spin);
1302        if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1303                gfs2_glock_put(gl);
1304}
1305
1306/**
1307 * gfs2_should_freeze - Figure out if glock should be frozen
1308 * @gl: The glock in question
1309 *
1310 * Glocks are not frozen if (a) the result of the dlm operation is
1311 * an error, (b) the locking operation was an unlock operation or
1312 * (c) if there is a "noexp" flagged request anywhere in the queue
1313 *
1314 * Returns: 1 if freezing should occur, 0 otherwise
1315 */
1316
1317static int gfs2_should_freeze(const struct gfs2_glock *gl)
1318{
1319        const struct gfs2_holder *gh;
1320
1321        if (gl->gl_reply & ~LM_OUT_ST_MASK)
1322                return 0;
1323        if (gl->gl_target == LM_ST_UNLOCKED)
1324                return 0;
1325
1326        list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1327                if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1328                        continue;
1329                if (LM_FLAG_NOEXP & gh->gh_flags)
1330                        return 0;
1331        }
1332
1333        return 1;
1334}
1335
1336/**
1337 * gfs2_glock_complete - Callback used by locking
1338 * @gl: Pointer to the glock
1339 * @ret: The return value from the dlm
1340 *
1341 * The gl_reply field is under the gl_spin lock so that it is ok
1342 * to use a bitfield shared with other glock state fields.
1343 */
1344
1345void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1346{
1347        struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
1348
1349        spin_lock(&gl->gl_spin);
1350        gl->gl_reply = ret;
1351
1352        if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags))) {
1353                if (gfs2_should_freeze(gl)) {
1354                        set_bit(GLF_FROZEN, &gl->gl_flags);
1355                        spin_unlock(&gl->gl_spin);
1356                        return;
1357                }
1358        }
1359
1360        spin_unlock(&gl->gl_spin);
1361        set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1362        smp_wmb();
1363        gfs2_glock_hold(gl);
1364        if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1365                gfs2_glock_put(gl);
1366}
1367
1368
1369static int gfs2_shrink_glock_memory(struct shrinker *shrink,
1370                                    struct shrink_control *sc)
1371{
1372        struct gfs2_glock *gl;
1373        int may_demote;
1374        int nr_skipped = 0;
1375        int nr = sc->nr_to_scan;
1376        gfp_t gfp_mask = sc->gfp_mask;
1377        LIST_HEAD(skipped);
1378
1379        if (nr == 0)
1380                goto out;
1381
1382        if (!(gfp_mask & __GFP_FS))
1383                return -1;
1384
1385        spin_lock(&lru_lock);
1386        while(nr && !list_empty(&lru_list)) {
1387                gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1388                list_del_init(&gl->gl_lru);
1389                clear_bit(GLF_LRU, &gl->gl_flags);
1390                atomic_dec(&lru_count);
1391
1392                /* Test for being demotable */
1393                if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1394                        gfs2_glock_hold(gl);
1395                        spin_unlock(&lru_lock);
1396                        spin_lock(&gl->gl_spin);
1397                        may_demote = demote_ok(gl);
1398                        if (may_demote) {
1399                                handle_callback(gl, LM_ST_UNLOCKED, 0);
1400                                nr--;
1401                        }
1402                        clear_bit(GLF_LOCK, &gl->gl_flags);
1403                        smp_mb__after_clear_bit();
1404                        if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1405                                gfs2_glock_put_nolock(gl);
1406                        spin_unlock(&gl->gl_spin);
1407                        spin_lock(&lru_lock);
1408                        continue;
1409                }
1410                nr_skipped++;
1411                list_add(&gl->gl_lru, &skipped);
1412                set_bit(GLF_LRU, &gl->gl_flags);
1413        }
1414        list_splice(&skipped, &lru_list);
1415        atomic_add(nr_skipped, &lru_count);
1416        spin_unlock(&lru_lock);
1417out:
1418        return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
1419}
1420
1421static struct shrinker glock_shrinker = {
1422        .shrink = gfs2_shrink_glock_memory,
1423        .seeks = DEFAULT_SEEKS,
1424};
1425
1426/**
1427 * examine_bucket - Call a function for glock in a hash bucket
1428 * @examiner: the function
1429 * @sdp: the filesystem
1430 * @bucket: the bucket
1431 *
1432 */
1433
1434static void examine_bucket(glock_examiner examiner, const struct gfs2_sbd *sdp,
1435                          unsigned int hash)
1436{
1437        struct gfs2_glock *gl;
1438        struct hlist_bl_head *head = &gl_hash_table[hash];
1439        struct hlist_bl_node *pos;
1440
1441        rcu_read_lock();
1442        hlist_bl_for_each_entry_rcu(gl, pos, head, gl_list) {
1443                if ((gl->gl_sbd == sdp) && atomic_read(&gl->gl_ref))
1444                        examiner(gl);
1445        }
1446        rcu_read_unlock();
1447        cond_resched();
1448}
1449
1450static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
1451{
1452        unsigned x;
1453
1454        for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1455                examine_bucket(examiner, sdp, x);
1456}
1457
1458
1459/**
1460 * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1461 * @gl: The glock to thaw
1462 *
1463 * N.B. When we freeze a glock, we leave a ref to the glock outstanding,
1464 * so this has to result in the ref count being dropped by one.
1465 */
1466
1467static void thaw_glock(struct gfs2_glock *gl)
1468{
1469        if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1470                return;
1471        set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1472        gfs2_glock_hold(gl);
1473        if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1474                gfs2_glock_put(gl);
1475}
1476
1477/**
1478 * clear_glock - look at a glock and see if we can free it from glock cache
1479 * @gl: the glock to look at
1480 *
1481 */
1482
1483static void clear_glock(struct gfs2_glock *gl)
1484{
1485        gfs2_glock_remove_from_lru(gl);
1486
1487        spin_lock(&gl->gl_spin);
1488        if (gl->gl_state != LM_ST_UNLOCKED)
1489                handle_callback(gl, LM_ST_UNLOCKED, 0);
1490        spin_unlock(&gl->gl_spin);
1491        gfs2_glock_hold(gl);
1492        if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1493                gfs2_glock_put(gl);
1494}
1495
1496/**
1497 * gfs2_glock_thaw - Thaw any frozen glocks
1498 * @sdp: The super block
1499 *
1500 */
1501
1502void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1503{
1504        glock_hash_walk(thaw_glock, sdp);
1505}
1506
1507static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1508{
1509        int ret;
1510        spin_lock(&gl->gl_spin);
1511        ret = __dump_glock(seq, gl);
1512        spin_unlock(&gl->gl_spin);
1513        return ret;
1514}
1515
1516static void dump_glock_func(struct gfs2_glock *gl)
1517{
1518        dump_glock(NULL, gl);
1519}
1520
1521/**
1522 * gfs2_gl_hash_clear - Empty out the glock hash table
1523 * @sdp: the filesystem
1524 * @wait: wait until it's all gone
1525 *
1526 * Called when unmounting the filesystem.
1527 */
1528
1529void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1530{
1531        glock_hash_walk(clear_glock, sdp);
1532        flush_workqueue(glock_workqueue);
1533        wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
1534        glock_hash_walk(dump_glock_func, sdp);
1535}
1536
1537void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1538{
1539        struct gfs2_glock *gl = ip->i_gl;
1540        int ret;
1541
1542        ret = gfs2_truncatei_resume(ip);
1543        gfs2_assert_withdraw(gl->gl_sbd, ret == 0);
1544
1545        spin_lock(&gl->gl_spin);
1546        clear_bit(GLF_LOCK, &gl->gl_flags);
1547        run_queue(gl, 1);
1548        spin_unlock(&gl->gl_spin);
1549}
1550
1551static const char *state2str(unsigned state)
1552{
1553        switch(state) {
1554        case LM_ST_UNLOCKED:
1555                return "UN";
1556        case LM_ST_SHARED:
1557                return "SH";
1558        case LM_ST_DEFERRED:
1559                return "DF";
1560        case LM_ST_EXCLUSIVE:
1561                return "EX";
1562        }
1563        return "??";
1564}
1565
1566static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags)
1567{
1568        char *p = buf;
1569        if (flags & LM_FLAG_TRY)
1570                *p++ = 't';
1571        if (flags & LM_FLAG_TRY_1CB)
1572                *p++ = 'T';
1573        if (flags & LM_FLAG_NOEXP)
1574                *p++ = 'e';
1575        if (flags & LM_FLAG_ANY)
1576                *p++ = 'A';
1577        if (flags & LM_FLAG_PRIORITY)
1578                *p++ = 'p';
1579        if (flags & GL_ASYNC)
1580                *p++ = 'a';
1581        if (flags & GL_EXACT)
1582                *p++ = 'E';
1583        if (flags & GL_NOCACHE)
1584                *p++ = 'c';
1585        if (test_bit(HIF_HOLDER, &iflags))
1586                *p++ = 'H';
1587        if (test_bit(HIF_WAIT, &iflags))
1588                *p++ = 'W';
1589        if (test_bit(HIF_FIRST, &iflags))
1590                *p++ = 'F';
1591        *p = 0;
1592        return buf;
1593}
1594
1595/**
1596 * dump_holder - print information about a glock holder
1597 * @seq: the seq_file struct
1598 * @gh: the glock holder
1599 *
1600 * Returns: 0 on success, -ENOBUFS when we run out of space
1601 */
1602
1603static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1604{
1605        struct task_struct *gh_owner = NULL;
1606        char flags_buf[32];
1607
1608        if (gh->gh_owner_pid)
1609                gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1610        gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
1611                       state2str(gh->gh_state),
1612                       hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1613                       gh->gh_error,
1614                       gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1615                       gh_owner ? gh_owner->comm : "(ended)",
1616                       (void *)gh->gh_ip);
1617        return 0;
1618}
1619
1620static const char *gflags2str(char *buf, const struct gfs2_glock *gl)
1621{
1622        const unsigned long *gflags = &gl->gl_flags;
1623        char *p = buf;
1624
1625        if (test_bit(GLF_LOCK, gflags))
1626                *p++ = 'l';
1627        if (test_bit(GLF_DEMOTE, gflags))
1628                *p++ = 'D';
1629        if (test_bit(GLF_PENDING_DEMOTE, gflags))
1630                *p++ = 'd';
1631        if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1632                *p++ = 'p';
1633        if (test_bit(GLF_DIRTY, gflags))
1634                *p++ = 'y';
1635        if (test_bit(GLF_LFLUSH, gflags))
1636                *p++ = 'f';
1637        if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1638                *p++ = 'i';
1639        if (test_bit(GLF_REPLY_PENDING, gflags))
1640                *p++ = 'r';
1641        if (test_bit(GLF_INITIAL, gflags))
1642                *p++ = 'I';
1643        if (test_bit(GLF_FROZEN, gflags))
1644                *p++ = 'F';
1645        if (test_bit(GLF_QUEUED, gflags))
1646                *p++ = 'q';
1647        if (test_bit(GLF_LRU, gflags))
1648                *p++ = 'L';
1649        if (gl->gl_object)
1650                *p++ = 'o';
1651        if (test_bit(GLF_BLOCKING, gflags))
1652                *p++ = 'b';
1653        *p = 0;
1654        return buf;
1655}
1656
1657/**
1658 * __dump_glock - print information about a glock
1659 * @seq: The seq_file struct
1660 * @gl: the glock
1661 *
1662 * The file format is as follows:
1663 * One line per object, capital letters are used to indicate objects
1664 * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1665 * other objects are indented by a single space and follow the glock to
1666 * which they are related. Fields are indicated by lower case letters
1667 * followed by a colon and the field value, except for strings which are in
1668 * [] so that its possible to see if they are composed of spaces for
1669 * example. The field's are n = number (id of the object), f = flags,
1670 * t = type, s = state, r = refcount, e = error, p = pid.
1671 *
1672 * Returns: 0 on success, -ENOBUFS when we run out of space
1673 */
1674
1675static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1676{
1677        const struct gfs2_glock_operations *glops = gl->gl_ops;
1678        unsigned long long dtime;
1679        const struct gfs2_holder *gh;
1680        char gflags_buf[32];
1681        int error = 0;
1682
1683        dtime = jiffies - gl->gl_demote_time;
1684        dtime *= 1000000/HZ; /* demote time in uSec */
1685        if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1686                dtime = 0;
1687        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",
1688                  state2str(gl->gl_state),
1689                  gl->gl_name.ln_type,
1690                  (unsigned long long)gl->gl_name.ln_number,
1691                  gflags2str(gflags_buf, gl),
1692                  state2str(gl->gl_target),
1693                  state2str(gl->gl_demote_state), dtime,
1694                  atomic_read(&gl->gl_ail_count),
1695                  atomic_read(&gl->gl_revokes),
1696                  atomic_read(&gl->gl_ref), gl->gl_hold_time);
1697
1698        list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1699                error = dump_holder(seq, gh);
1700                if (error)
1701                        goto out;
1702        }
1703        if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1704                error = glops->go_dump(seq, gl);
1705out:
1706        return error;
1707}
1708
1709static int gfs2_glstats_seq_show(struct seq_file *seq, void *iter_ptr)
1710{
1711        struct gfs2_glock *gl = iter_ptr;
1712
1713        seq_printf(seq, "G: n:%u/%llx rtt:%lld/%lld rttb:%lld/%lld irt:%lld/%lld dcnt: %lld qcnt: %lld\n",
1714                   gl->gl_name.ln_type,
1715                   (unsigned long long)gl->gl_name.ln_number,
1716                   (long long)gl->gl_stats.stats[GFS2_LKS_SRTT],
1717                   (long long)gl->gl_stats.stats[GFS2_LKS_SRTTVAR],
1718                   (long long)gl->gl_stats.stats[GFS2_LKS_SRTTB],
1719                   (long long)gl->gl_stats.stats[GFS2_LKS_SRTTVARB],
1720                   (long long)gl->gl_stats.stats[GFS2_LKS_SIRT],
1721                   (long long)gl->gl_stats.stats[GFS2_LKS_SIRTVAR],
1722                   (long long)gl->gl_stats.stats[GFS2_LKS_DCOUNT],
1723                   (long long)gl->gl_stats.stats[GFS2_LKS_QCOUNT]);
1724        return 0;
1725}
1726
1727static const char *gfs2_gltype[] = {
1728        "type",
1729        "reserved",
1730        "nondisk",
1731        "inode",
1732        "rgrp",
1733        "meta",
1734        "iopen",
1735        "flock",
1736        "plock",
1737        "quota",
1738        "journal",
1739};
1740
1741static const char *gfs2_stype[] = {
1742        [GFS2_LKS_SRTT]         = "srtt",
1743        [GFS2_LKS_SRTTVAR]      = "srttvar",
1744        [GFS2_LKS_SRTTB]        = "srttb",
1745        [GFS2_LKS_SRTTVARB]     = "srttvarb",
1746        [GFS2_LKS_SIRT]         = "sirt",
1747        [GFS2_LKS_SIRTVAR]      = "sirtvar",
1748        [GFS2_LKS_DCOUNT]       = "dlm",
1749        [GFS2_LKS_QCOUNT]       = "queue",
1750};
1751
1752#define GFS2_NR_SBSTATS (ARRAY_SIZE(gfs2_gltype) * ARRAY_SIZE(gfs2_stype))
1753
1754static int gfs2_sbstats_seq_show(struct seq_file *seq, void *iter_ptr)
1755{
1756        struct gfs2_glock_iter *gi = seq->private;
1757        struct gfs2_sbd *sdp = gi->sdp;
1758        unsigned index = gi->hash >> 3;
1759        unsigned subindex = gi->hash & 0x07;
1760        s64 value;
1761        int i;
1762
1763        if (index == 0 && subindex != 0)
1764                return 0;
1765
1766        seq_printf(seq, "%-10s %8s:", gfs2_gltype[index],
1767                   (index == 0) ? "cpu": gfs2_stype[subindex]);
1768
1769        for_each_possible_cpu(i) {
1770                const struct gfs2_pcpu_lkstats *lkstats = per_cpu_ptr(sdp->sd_lkstats, i);
1771                if (index == 0) {
1772                        value = i;
1773                } else {
1774                        value = lkstats->lkstats[index - 1].stats[subindex];
1775                }
1776                seq_printf(seq, " %15lld", (long long)value);
1777        }
1778        seq_putc(seq, '\n');
1779        return 0;
1780}
1781
1782int __init gfs2_glock_init(void)
1783{
1784        unsigned i;
1785        for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
1786                INIT_HLIST_BL_HEAD(&gl_hash_table[i]);
1787        }
1788
1789        glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
1790                                          WQ_HIGHPRI | WQ_FREEZABLE, 0);
1791        if (IS_ERR(glock_workqueue))
1792                return PTR_ERR(glock_workqueue);
1793        gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
1794                                                WQ_MEM_RECLAIM | WQ_FREEZABLE,
1795                                                0);
1796        if (IS_ERR(gfs2_delete_workqueue)) {
1797                destroy_workqueue(glock_workqueue);
1798                return PTR_ERR(gfs2_delete_workqueue);
1799        }
1800
1801        register_shrinker(&glock_shrinker);
1802
1803        return 0;
1804}
1805
1806void gfs2_glock_exit(void)
1807{
1808        unregister_shrinker(&glock_shrinker);
1809        destroy_workqueue(glock_workqueue);
1810        destroy_workqueue(gfs2_delete_workqueue);
1811}
1812
1813static inline struct gfs2_glock *glock_hash_chain(unsigned hash)
1814{
1815        return hlist_bl_entry(hlist_bl_first_rcu(&gl_hash_table[hash]),
1816                              struct gfs2_glock, gl_list);
1817}
1818
1819static inline struct gfs2_glock *glock_hash_next(struct gfs2_glock *gl)
1820{
1821        return hlist_bl_entry(rcu_dereference(gl->gl_list.next),
1822                              struct gfs2_glock, gl_list);
1823}
1824
1825static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1826{
1827        struct gfs2_glock *gl;
1828
1829        do {
1830                gl = gi->gl;
1831                if (gl) {
1832                        gi->gl = glock_hash_next(gl);
1833                        gi->nhash++;
1834                } else {
1835                        if (gi->hash >= GFS2_GL_HASH_SIZE) {
1836                                rcu_read_unlock();
1837                                return 1;
1838                        }
1839                        gi->gl = glock_hash_chain(gi->hash);
1840                        gi->nhash = 0;
1841                }
1842                while (gi->gl == NULL) {
1843                        gi->hash++;
1844                        if (gi->hash >= GFS2_GL_HASH_SIZE) {
1845                                rcu_read_unlock();
1846                                return 1;
1847                        }
1848                        gi->gl = glock_hash_chain(gi->hash);
1849                        gi->nhash = 0;
1850                }
1851        /* Skip entries for other sb and dead entries */
1852        } while (gi->sdp != gi->gl->gl_sbd || atomic_read(&gi->gl->gl_ref) == 0);
1853
1854        return 0;
1855}
1856
1857static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1858{
1859        struct gfs2_glock_iter *gi = seq->private;
1860        loff_t n = *pos;
1861
1862        if (gi->last_pos <= *pos)
1863                n = gi->nhash + (*pos - gi->last_pos);
1864        else
1865                gi->hash = 0;
1866
1867        gi->nhash = 0;
1868        rcu_read_lock();
1869
1870        do {
1871                if (gfs2_glock_iter_next(gi))
1872                        return NULL;
1873        } while (n--);
1874
1875        gi->last_pos = *pos;
1876        return gi->gl;
1877}
1878
1879static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1880                                 loff_t *pos)
1881{
1882        struct gfs2_glock_iter *gi = seq->private;
1883
1884        (*pos)++;
1885        gi->last_pos = *pos;
1886        if (gfs2_glock_iter_next(gi))
1887                return NULL;
1888
1889        return gi->gl;
1890}
1891
1892static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1893{
1894        struct gfs2_glock_iter *gi = seq->private;
1895
1896        if (gi->gl)
1897                rcu_read_unlock();
1898        gi->gl = NULL;
1899}
1900
1901static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1902{
1903        return dump_glock(seq, iter_ptr);
1904}
1905
1906static void *gfs2_sbstats_seq_start(struct seq_file *seq, loff_t *pos)
1907{
1908        struct gfs2_glock_iter *gi = seq->private;
1909
1910        gi->hash = *pos;
1911        if (*pos >= GFS2_NR_SBSTATS)
1912                return NULL;
1913        preempt_disable();
1914        return SEQ_START_TOKEN;
1915}
1916
1917static void *gfs2_sbstats_seq_next(struct seq_file *seq, void *iter_ptr,
1918                                   loff_t *pos)
1919{
1920        struct gfs2_glock_iter *gi = seq->private;
1921        (*pos)++;
1922        gi->hash++;
1923        if (gi->hash >= GFS2_NR_SBSTATS) {
1924                preempt_enable();
1925                return NULL;
1926        }
1927        return SEQ_START_TOKEN;
1928}
1929
1930static void gfs2_sbstats_seq_stop(struct seq_file *seq, void *iter_ptr)
1931{
1932        preempt_enable();
1933}
1934
1935static const struct seq_operations gfs2_glock_seq_ops = {
1936        .start = gfs2_glock_seq_start,
1937        .next  = gfs2_glock_seq_next,
1938        .stop  = gfs2_glock_seq_stop,
1939        .show  = gfs2_glock_seq_show,
1940};
1941
1942static const struct seq_operations gfs2_glstats_seq_ops = {
1943        .start = gfs2_glock_seq_start,
1944        .next  = gfs2_glock_seq_next,
1945        .stop  = gfs2_glock_seq_stop,
1946        .show  = gfs2_glstats_seq_show,
1947};
1948
1949static const struct seq_operations gfs2_sbstats_seq_ops = {
1950        .start = gfs2_sbstats_seq_start,
1951        .next  = gfs2_sbstats_seq_next,
1952        .stop  = gfs2_sbstats_seq_stop,
1953        .show  = gfs2_sbstats_seq_show,
1954};
1955
1956#define GFS2_SEQ_GOODSIZE min(PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER, 65536UL)
1957
1958static int gfs2_glocks_open(struct inode *inode, struct file *file)
1959{
1960        int ret = seq_open_private(file, &gfs2_glock_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        }
1970        return ret;
1971}
1972
1973static int gfs2_glstats_open(struct inode *inode, struct file *file)
1974{
1975        int ret = seq_open_private(file, &gfs2_glstats_seq_ops,
1976                                   sizeof(struct gfs2_glock_iter));
1977        if (ret == 0) {
1978                struct seq_file *seq = file->private_data;
1979                struct gfs2_glock_iter *gi = seq->private;
1980                gi->sdp = inode->i_private;
1981                seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
1982                if (seq->buf)
1983                        seq->size = GFS2_SEQ_GOODSIZE;
1984        }
1985        return ret;
1986}
1987
1988static int gfs2_sbstats_open(struct inode *inode, struct file *file)
1989{
1990        int ret = seq_open_private(file, &gfs2_sbstats_seq_ops,
1991                                   sizeof(struct gfs2_glock_iter));
1992        if (ret == 0) {
1993                struct seq_file *seq = file->private_data;
1994                struct gfs2_glock_iter *gi = seq->private;
1995                gi->sdp = inode->i_private;
1996        }
1997        return ret;
1998}
1999
2000static const struct file_operations gfs2_glocks_fops = {
2001        .owner   = THIS_MODULE,
2002        .open    = gfs2_glocks_open,
2003        .read    = seq_read,
2004        .llseek  = seq_lseek,
2005        .release = seq_release_private,
2006};
2007
2008static const struct file_operations gfs2_glstats_fops = {
2009        .owner   = THIS_MODULE,
2010        .open    = gfs2_glstats_open,
2011        .read    = seq_read,
2012        .llseek  = seq_lseek,
2013        .release = seq_release_private,
2014};
2015
2016static const struct file_operations gfs2_sbstats_fops = {
2017        .owner   = THIS_MODULE,
2018        .open    = gfs2_sbstats_open,
2019        .read    = seq_read,
2020        .llseek  = seq_lseek,
2021        .release = seq_release_private,
2022};
2023
2024int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
2025{
2026        sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
2027        if (!sdp->debugfs_dir)
2028                return -ENOMEM;
2029        sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
2030                                                         S_IFREG | S_IRUGO,
2031                                                         sdp->debugfs_dir, sdp,
2032                                                         &gfs2_glocks_fops);
2033        if (!sdp->debugfs_dentry_glocks)
2034                goto fail;
2035
2036        sdp->debugfs_dentry_glstats = debugfs_create_file("glstats",
2037                                                        S_IFREG | S_IRUGO,
2038                                                        sdp->debugfs_dir, sdp,
2039                                                        &gfs2_glstats_fops);
2040        if (!sdp->debugfs_dentry_glstats)
2041                goto fail;
2042
2043        sdp->debugfs_dentry_sbstats = debugfs_create_file("sbstats",
2044                                                        S_IFREG | S_IRUGO,
2045                                                        sdp->debugfs_dir, sdp,
2046                                                        &gfs2_sbstats_fops);
2047        if (!sdp->debugfs_dentry_sbstats)
2048                goto fail;
2049
2050        return 0;
2051fail:
2052        gfs2_delete_debugfs_file(sdp);
2053        return -ENOMEM;
2054}
2055
2056void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
2057{
2058        if (sdp->debugfs_dir) {
2059                if (sdp->debugfs_dentry_glocks) {
2060                        debugfs_remove(sdp->debugfs_dentry_glocks);
2061                        sdp->debugfs_dentry_glocks = NULL;
2062                }
2063                if (sdp->debugfs_dentry_glstats) {
2064                        debugfs_remove(sdp->debugfs_dentry_glstats);
2065                        sdp->debugfs_dentry_glstats = NULL;
2066                }
2067                if (sdp->debugfs_dentry_sbstats) {
2068                        debugfs_remove(sdp->debugfs_dentry_sbstats);
2069                        sdp->debugfs_dentry_sbstats = NULL;
2070                }
2071                debugfs_remove(sdp->debugfs_dir);
2072                sdp->debugfs_dir = NULL;
2073        }
2074}
2075
2076int gfs2_register_debugfs(void)
2077{
2078        gfs2_root = debugfs_create_dir("gfs2", NULL);
2079        return gfs2_root ? 0 : -ENOMEM;
2080}
2081
2082void gfs2_unregister_debugfs(void)
2083{
2084        debugfs_remove(gfs2_root);
2085        gfs2_root = NULL;
2086}
2087
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