linux/fs/gfs2/glock.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   4 * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
   5 */
   6
   7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   8
   9#include <linux/sched.h>
  10#include <linux/slab.h>
  11#include <linux/spinlock.h>
  12#include <linux/buffer_head.h>
  13#include <linux/delay.h>
  14#include <linux/sort.h>
  15#include <linux/hash.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 <linux/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#include <linux/list_sort.h>
  34#include <linux/lockref.h>
  35#include <linux/rhashtable.h>
  36
  37#include "gfs2.h"
  38#include "incore.h"
  39#include "glock.h"
  40#include "glops.h"
  41#include "inode.h"
  42#include "lops.h"
  43#include "meta_io.h"
  44#include "quota.h"
  45#include "super.h"
  46#include "util.h"
  47#include "bmap.h"
  48#define CREATE_TRACE_POINTS
  49#include "trace_gfs2.h"
  50
  51struct gfs2_glock_iter {
  52        struct gfs2_sbd *sdp;           /* incore superblock           */
  53        struct rhashtable_iter hti;     /* rhashtable iterator         */
  54        struct gfs2_glock *gl;          /* current glock struct        */
  55        loff_t last_pos;                /* last position               */
  56};
  57
  58typedef void (*glock_examiner) (struct gfs2_glock * gl);
  59
  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       BIT(GFS2_GL_HASH_SHIFT)
  71
  72static const struct rhashtable_params ht_parms = {
  73        .nelem_hint = GFS2_GL_HASH_SIZE * 3 / 4,
  74        .key_len = offsetofend(struct lm_lockname, ln_type),
  75        .key_offset = offsetof(struct gfs2_glock, gl_name),
  76        .head_offset = offsetof(struct gfs2_glock, gl_node),
  77};
  78
  79static struct rhashtable gl_hash_table;
  80
  81#define GLOCK_WAIT_TABLE_BITS 12
  82#define GLOCK_WAIT_TABLE_SIZE (1 << GLOCK_WAIT_TABLE_BITS)
  83static wait_queue_head_t glock_wait_table[GLOCK_WAIT_TABLE_SIZE] __cacheline_aligned;
  84
  85struct wait_glock_queue {
  86        struct lm_lockname *name;
  87        wait_queue_entry_t wait;
  88};
  89
  90static int glock_wake_function(wait_queue_entry_t *wait, unsigned int mode,
  91                               int sync, void *key)
  92{
  93        struct wait_glock_queue *wait_glock =
  94                container_of(wait, struct wait_glock_queue, wait);
  95        struct lm_lockname *wait_name = wait_glock->name;
  96        struct lm_lockname *wake_name = key;
  97
  98        if (wake_name->ln_sbd != wait_name->ln_sbd ||
  99            wake_name->ln_number != wait_name->ln_number ||
 100            wake_name->ln_type != wait_name->ln_type)
 101                return 0;
 102        return autoremove_wake_function(wait, mode, sync, key);
 103}
 104
 105static wait_queue_head_t *glock_waitqueue(struct lm_lockname *name)
 106{
 107        u32 hash = jhash2((u32 *)name, ht_parms.key_len / 4, 0);
 108
 109        return glock_wait_table + hash_32(hash, GLOCK_WAIT_TABLE_BITS);
 110}
 111
 112/**
 113 * wake_up_glock  -  Wake up waiters on a glock
 114 * @gl: the glock
 115 */
 116static void wake_up_glock(struct gfs2_glock *gl)
 117{
 118        wait_queue_head_t *wq = glock_waitqueue(&gl->gl_name);
 119
 120        if (waitqueue_active(wq))
 121                __wake_up(wq, TASK_NORMAL, 1, &gl->gl_name);
 122}
 123
 124static void gfs2_glock_dealloc(struct rcu_head *rcu)
 125{
 126        struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu);
 127
 128        kfree(gl->gl_lksb.sb_lvbptr);
 129        if (gl->gl_ops->go_flags & GLOF_ASPACE)
 130                kmem_cache_free(gfs2_glock_aspace_cachep, gl);
 131        else
 132                kmem_cache_free(gfs2_glock_cachep, gl);
 133}
 134
 135/**
 136 * glock_blocked_by_withdraw - determine if we can still use a glock
 137 * @gl: the glock
 138 *
 139 * We need to allow some glocks to be enqueued, dequeued, promoted, and demoted
 140 * when we're withdrawn. For example, to maintain metadata integrity, we should
 141 * disallow the use of inode and rgrp glocks when withdrawn. Other glocks, like
 142 * iopen or the transaction glocks may be safely used because none of their
 143 * metadata goes through the journal. So in general, we should disallow all
 144 * glocks that are journaled, and allow all the others. One exception is:
 145 * we need to allow our active journal to be promoted and demoted so others
 146 * may recover it and we can reacquire it when they're done.
 147 */
 148static bool glock_blocked_by_withdraw(struct gfs2_glock *gl)
 149{
 150        struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 151
 152        if (likely(!gfs2_withdrawn(sdp)))
 153                return false;
 154        if (gl->gl_ops->go_flags & GLOF_NONDISK)
 155                return false;
 156        if (!sdp->sd_jdesc ||
 157            gl->gl_name.ln_number == sdp->sd_jdesc->jd_no_addr)
 158                return false;
 159        return true;
 160}
 161
 162void gfs2_glock_free(struct gfs2_glock *gl)
 163{
 164        struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 165
 166        gfs2_glock_assert_withdraw(gl, atomic_read(&gl->gl_revokes) == 0);
 167        rhashtable_remove_fast(&gl_hash_table, &gl->gl_node, ht_parms);
 168        smp_mb();
 169        wake_up_glock(gl);
 170        call_rcu(&gl->gl_rcu, gfs2_glock_dealloc);
 171        if (atomic_dec_and_test(&sdp->sd_glock_disposal))
 172                wake_up(&sdp->sd_glock_wait);
 173}
 174
 175/**
 176 * gfs2_glock_hold() - increment reference count on glock
 177 * @gl: The glock to hold
 178 *
 179 */
 180
 181void gfs2_glock_hold(struct gfs2_glock *gl)
 182{
 183        GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
 184        lockref_get(&gl->gl_lockref);
 185}
 186
 187/**
 188 * demote_ok - Check to see if it's ok to unlock a glock
 189 * @gl: the glock
 190 *
 191 * Returns: 1 if it's ok
 192 */
 193
 194static int demote_ok(const struct gfs2_glock *gl)
 195{
 196        const struct gfs2_glock_operations *glops = gl->gl_ops;
 197
 198        if (gl->gl_state == LM_ST_UNLOCKED)
 199                return 0;
 200        if (!list_empty(&gl->gl_holders))
 201                return 0;
 202        if (glops->go_demote_ok)
 203                return glops->go_demote_ok(gl);
 204        return 1;
 205}
 206
 207
 208void gfs2_glock_add_to_lru(struct gfs2_glock *gl)
 209{
 210        if (!(gl->gl_ops->go_flags & GLOF_LRU))
 211                return;
 212
 213        spin_lock(&lru_lock);
 214
 215        list_del(&gl->gl_lru);
 216        list_add_tail(&gl->gl_lru, &lru_list);
 217
 218        if (!test_bit(GLF_LRU, &gl->gl_flags)) {
 219                set_bit(GLF_LRU, &gl->gl_flags);
 220                atomic_inc(&lru_count);
 221        }
 222
 223        spin_unlock(&lru_lock);
 224}
 225
 226static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
 227{
 228        if (!(gl->gl_ops->go_flags & GLOF_LRU))
 229                return;
 230
 231        spin_lock(&lru_lock);
 232        if (test_bit(GLF_LRU, &gl->gl_flags)) {
 233                list_del_init(&gl->gl_lru);
 234                atomic_dec(&lru_count);
 235                clear_bit(GLF_LRU, &gl->gl_flags);
 236        }
 237        spin_unlock(&lru_lock);
 238}
 239
 240/*
 241 * Enqueue the glock on the work queue.  Passes one glock reference on to the
 242 * work queue.
 243 */
 244static void __gfs2_glock_queue_work(struct gfs2_glock *gl, unsigned long delay) {
 245        if (!queue_delayed_work(glock_workqueue, &gl->gl_work, delay)) {
 246                /*
 247                 * We are holding the lockref spinlock, and the work was still
 248                 * queued above.  The queued work (glock_work_func) takes that
 249                 * spinlock before dropping its glock reference(s), so it
 250                 * cannot have dropped them in the meantime.
 251                 */
 252                GLOCK_BUG_ON(gl, gl->gl_lockref.count < 2);
 253                gl->gl_lockref.count--;
 254        }
 255}
 256
 257static void gfs2_glock_queue_work(struct gfs2_glock *gl, unsigned long delay) {
 258        spin_lock(&gl->gl_lockref.lock);
 259        __gfs2_glock_queue_work(gl, delay);
 260        spin_unlock(&gl->gl_lockref.lock);
 261}
 262
 263static void __gfs2_glock_put(struct gfs2_glock *gl)
 264{
 265        struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 266        struct address_space *mapping = gfs2_glock2aspace(gl);
 267
 268        lockref_mark_dead(&gl->gl_lockref);
 269
 270        gfs2_glock_remove_from_lru(gl);
 271        spin_unlock(&gl->gl_lockref.lock);
 272        GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
 273        if (mapping) {
 274                truncate_inode_pages_final(mapping);
 275                if (!gfs2_withdrawn(sdp))
 276                        GLOCK_BUG_ON(gl, !mapping_empty(mapping));
 277        }
 278        trace_gfs2_glock_put(gl);
 279        sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
 280}
 281
 282/*
 283 * Cause the glock to be put in work queue context.
 284 */
 285void gfs2_glock_queue_put(struct gfs2_glock *gl)
 286{
 287        gfs2_glock_queue_work(gl, 0);
 288}
 289
 290/**
 291 * gfs2_glock_put() - Decrement reference count on glock
 292 * @gl: The glock to put
 293 *
 294 */
 295
 296void gfs2_glock_put(struct gfs2_glock *gl)
 297{
 298        if (lockref_put_or_lock(&gl->gl_lockref))
 299                return;
 300
 301        __gfs2_glock_put(gl);
 302}
 303
 304/**
 305 * may_grant - check if its ok to grant a new lock
 306 * @gl: The glock
 307 * @gh: The lock request which we wish to grant
 308 *
 309 * Returns: true if its ok to grant the lock
 310 */
 311
 312static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
 313{
 314        const struct gfs2_holder *gh_head = list_first_entry(&gl->gl_holders, const struct gfs2_holder, gh_list);
 315
 316        if (gh != gh_head) {
 317                /**
 318                 * Here we make a special exception to grant holders who agree
 319                 * to share the EX lock with other holders who also have the
 320                 * bit set. If the original holder has the LM_FLAG_NODE_SCOPE bit
 321                 * is set, we grant more holders with the bit set.
 322                 */
 323                if (gh_head->gh_state == LM_ST_EXCLUSIVE &&
 324                    (gh_head->gh_flags & LM_FLAG_NODE_SCOPE) &&
 325                    gh->gh_state == LM_ST_EXCLUSIVE &&
 326                    (gh->gh_flags & LM_FLAG_NODE_SCOPE))
 327                        return 1;
 328                if ((gh->gh_state == LM_ST_EXCLUSIVE ||
 329                     gh_head->gh_state == LM_ST_EXCLUSIVE))
 330                        return 0;
 331        }
 332        if (gl->gl_state == gh->gh_state)
 333                return 1;
 334        if (gh->gh_flags & GL_EXACT)
 335                return 0;
 336        if (gl->gl_state == LM_ST_EXCLUSIVE) {
 337                if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
 338                        return 1;
 339                if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
 340                        return 1;
 341        }
 342        if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
 343                return 1;
 344        return 0;
 345}
 346
 347static void gfs2_holder_wake(struct gfs2_holder *gh)
 348{
 349        clear_bit(HIF_WAIT, &gh->gh_iflags);
 350        smp_mb__after_atomic();
 351        wake_up_bit(&gh->gh_iflags, HIF_WAIT);
 352        if (gh->gh_flags & GL_ASYNC) {
 353                struct gfs2_sbd *sdp = gh->gh_gl->gl_name.ln_sbd;
 354
 355                wake_up(&sdp->sd_async_glock_wait);
 356        }
 357}
 358
 359/**
 360 * do_error - Something unexpected has happened during a lock request
 361 * @gl: The glock
 362 * @ret: The status from the DLM
 363 */
 364
 365static void do_error(struct gfs2_glock *gl, const int ret)
 366{
 367        struct gfs2_holder *gh, *tmp;
 368
 369        list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 370                if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 371                        continue;
 372                if (ret & LM_OUT_ERROR)
 373                        gh->gh_error = -EIO;
 374                else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
 375                        gh->gh_error = GLR_TRYFAILED;
 376                else
 377                        continue;
 378                list_del_init(&gh->gh_list);
 379                trace_gfs2_glock_queue(gh, 0);
 380                gfs2_holder_wake(gh);
 381        }
 382}
 383
 384/**
 385 * do_promote - promote as many requests as possible on the current queue
 386 * @gl: The glock
 387 * 
 388 * Returns: 1 if there is a blocked holder at the head of the list, or 2
 389 *          if a type specific operation is underway.
 390 */
 391
 392static int do_promote(struct gfs2_glock *gl)
 393__releases(&gl->gl_lockref.lock)
 394__acquires(&gl->gl_lockref.lock)
 395{
 396        const struct gfs2_glock_operations *glops = gl->gl_ops;
 397        struct gfs2_holder *gh, *tmp;
 398        int ret;
 399
 400restart:
 401        list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 402                if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 403                        continue;
 404                if (may_grant(gl, gh)) {
 405                        if (gh->gh_list.prev == &gl->gl_holders &&
 406                            glops->go_lock) {
 407                                spin_unlock(&gl->gl_lockref.lock);
 408                                /* FIXME: eliminate this eventually */
 409                                ret = glops->go_lock(gh);
 410                                spin_lock(&gl->gl_lockref.lock);
 411                                if (ret) {
 412                                        if (ret == 1)
 413                                                return 2;
 414                                        gh->gh_error = ret;
 415                                        list_del_init(&gh->gh_list);
 416                                        trace_gfs2_glock_queue(gh, 0);
 417                                        gfs2_holder_wake(gh);
 418                                        goto restart;
 419                                }
 420                                set_bit(HIF_HOLDER, &gh->gh_iflags);
 421                                trace_gfs2_promote(gh, 1);
 422                                gfs2_holder_wake(gh);
 423                                goto restart;
 424                        }
 425                        set_bit(HIF_HOLDER, &gh->gh_iflags);
 426                        trace_gfs2_promote(gh, 0);
 427                        gfs2_holder_wake(gh);
 428                        continue;
 429                }
 430                if (gh->gh_list.prev == &gl->gl_holders)
 431                        return 1;
 432                do_error(gl, 0);
 433                break;
 434        }
 435        return 0;
 436}
 437
 438/**
 439 * find_first_waiter - find the first gh that's waiting for the glock
 440 * @gl: the glock
 441 */
 442
 443static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
 444{
 445        struct gfs2_holder *gh;
 446
 447        list_for_each_entry(gh, &gl->gl_holders, gh_list) {
 448                if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
 449                        return gh;
 450        }
 451        return NULL;
 452}
 453
 454/**
 455 * state_change - record that the glock is now in a different state
 456 * @gl: the glock
 457 * @new_state: the new state
 458 */
 459
 460static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 461{
 462        int held1, held2;
 463
 464        held1 = (gl->gl_state != LM_ST_UNLOCKED);
 465        held2 = (new_state != LM_ST_UNLOCKED);
 466
 467        if (held1 != held2) {
 468                GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
 469                if (held2)
 470                        gl->gl_lockref.count++;
 471                else
 472                        gl->gl_lockref.count--;
 473        }
 474        if (new_state != gl->gl_target)
 475                /* shorten our minimum hold time */
 476                gl->gl_hold_time = max(gl->gl_hold_time - GL_GLOCK_HOLD_DECR,
 477                                       GL_GLOCK_MIN_HOLD);
 478        gl->gl_state = new_state;
 479        gl->gl_tchange = jiffies;
 480}
 481
 482static void gfs2_set_demote(struct gfs2_glock *gl)
 483{
 484        struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 485
 486        set_bit(GLF_DEMOTE, &gl->gl_flags);
 487        smp_mb();
 488        wake_up(&sdp->sd_async_glock_wait);
 489}
 490
 491static void gfs2_demote_wake(struct gfs2_glock *gl)
 492{
 493        gl->gl_demote_state = LM_ST_EXCLUSIVE;
 494        clear_bit(GLF_DEMOTE, &gl->gl_flags);
 495        smp_mb__after_atomic();
 496        wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
 497}
 498
 499/**
 500 * finish_xmote - The DLM has replied to one of our lock requests
 501 * @gl: The glock
 502 * @ret: The status from the DLM
 503 *
 504 */
 505
 506static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
 507{
 508        const struct gfs2_glock_operations *glops = gl->gl_ops;
 509        struct gfs2_holder *gh;
 510        unsigned state = ret & LM_OUT_ST_MASK;
 511        int rv;
 512
 513        spin_lock(&gl->gl_lockref.lock);
 514        trace_gfs2_glock_state_change(gl, state);
 515        state_change(gl, state);
 516        gh = find_first_waiter(gl);
 517
 518        /* Demote to UN request arrived during demote to SH or DF */
 519        if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
 520            state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
 521                gl->gl_target = LM_ST_UNLOCKED;
 522
 523        /* Check for state != intended state */
 524        if (unlikely(state != gl->gl_target)) {
 525                if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
 526                        /* move to back of queue and try next entry */
 527                        if (ret & LM_OUT_CANCELED) {
 528                                if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
 529                                        list_move_tail(&gh->gh_list, &gl->gl_holders);
 530                                gh = find_first_waiter(gl);
 531                                gl->gl_target = gh->gh_state;
 532                                goto retry;
 533                        }
 534                        /* Some error or failed "try lock" - report it */
 535                        if ((ret & LM_OUT_ERROR) ||
 536                            (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 537                                gl->gl_target = gl->gl_state;
 538                                do_error(gl, ret);
 539                                goto out;
 540                        }
 541                }
 542                switch(state) {
 543                /* Unlocked due to conversion deadlock, try again */
 544                case LM_ST_UNLOCKED:
 545retry:
 546                        do_xmote(gl, gh, gl->gl_target);
 547                        break;
 548                /* Conversion fails, unlock and try again */
 549                case LM_ST_SHARED:
 550                case LM_ST_DEFERRED:
 551                        do_xmote(gl, gh, LM_ST_UNLOCKED);
 552                        break;
 553                default: /* Everything else */
 554                        fs_err(gl->gl_name.ln_sbd, "wanted %u got %u\n",
 555                               gl->gl_target, state);
 556                        GLOCK_BUG_ON(gl, 1);
 557                }
 558                spin_unlock(&gl->gl_lockref.lock);
 559                return;
 560        }
 561
 562        /* Fast path - we got what we asked for */
 563        if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
 564                gfs2_demote_wake(gl);
 565        if (state != LM_ST_UNLOCKED) {
 566                if (glops->go_xmote_bh) {
 567                        spin_unlock(&gl->gl_lockref.lock);
 568                        rv = glops->go_xmote_bh(gl);
 569                        spin_lock(&gl->gl_lockref.lock);
 570                        if (rv) {
 571                                do_error(gl, rv);
 572                                goto out;
 573                        }
 574                }
 575                rv = do_promote(gl);
 576                if (rv == 2)
 577                        goto out_locked;
 578        }
 579out:
 580        clear_bit(GLF_LOCK, &gl->gl_flags);
 581out_locked:
 582        spin_unlock(&gl->gl_lockref.lock);
 583}
 584
 585static bool is_system_glock(struct gfs2_glock *gl)
 586{
 587        struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 588        struct gfs2_inode *m_ip = GFS2_I(sdp->sd_statfs_inode);
 589
 590        if (gl == m_ip->i_gl)
 591                return true;
 592        return false;
 593}
 594
 595/**
 596 * do_xmote - Calls the DLM to change the state of a lock
 597 * @gl: The lock state
 598 * @gh: The holder (only for promotes)
 599 * @target: The target lock state
 600 *
 601 */
 602
 603static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
 604__releases(&gl->gl_lockref.lock)
 605__acquires(&gl->gl_lockref.lock)
 606{
 607        const struct gfs2_glock_operations *glops = gl->gl_ops;
 608        struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 609        unsigned int lck_flags = (unsigned int)(gh ? gh->gh_flags : 0);
 610        int ret;
 611
 612        if (target != LM_ST_UNLOCKED && glock_blocked_by_withdraw(gl) &&
 613            gh && !(gh->gh_flags & LM_FLAG_NOEXP))
 614                return;
 615        lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
 616                      LM_FLAG_PRIORITY);
 617        GLOCK_BUG_ON(gl, gl->gl_state == target);
 618        GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
 619        if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
 620            glops->go_inval) {
 621                /*
 622                 * If another process is already doing the invalidate, let that
 623                 * finish first.  The glock state machine will get back to this
 624                 * holder again later.
 625                 */
 626                if (test_and_set_bit(GLF_INVALIDATE_IN_PROGRESS,
 627                                     &gl->gl_flags))
 628                        return;
 629                do_error(gl, 0); /* Fail queued try locks */
 630        }
 631        gl->gl_req = target;
 632        set_bit(GLF_BLOCKING, &gl->gl_flags);
 633        if ((gl->gl_req == LM_ST_UNLOCKED) ||
 634            (gl->gl_state == LM_ST_EXCLUSIVE) ||
 635            (lck_flags & (LM_FLAG_TRY|LM_FLAG_TRY_1CB)))
 636                clear_bit(GLF_BLOCKING, &gl->gl_flags);
 637        spin_unlock(&gl->gl_lockref.lock);
 638        if (glops->go_sync) {
 639                ret = glops->go_sync(gl);
 640                /* If we had a problem syncing (due to io errors or whatever,
 641                 * we should not invalidate the metadata or tell dlm to
 642                 * release the glock to other nodes.
 643                 */
 644                if (ret) {
 645                        if (cmpxchg(&sdp->sd_log_error, 0, ret)) {
 646                                fs_err(sdp, "Error %d syncing glock \n", ret);
 647                                gfs2_dump_glock(NULL, gl, true);
 648                        }
 649                        goto skip_inval;
 650                }
 651        }
 652        if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags)) {
 653                /*
 654                 * The call to go_sync should have cleared out the ail list.
 655                 * If there are still items, we have a problem. We ought to
 656                 * withdraw, but we can't because the withdraw code also uses
 657                 * glocks. Warn about the error, dump the glock, then fall
 658                 * through and wait for logd to do the withdraw for us.
 659                 */
 660                if ((atomic_read(&gl->gl_ail_count) != 0) &&
 661                    (!cmpxchg(&sdp->sd_log_error, 0, -EIO))) {
 662                        gfs2_glock_assert_warn(gl,
 663                                               !atomic_read(&gl->gl_ail_count));
 664                        gfs2_dump_glock(NULL, gl, true);
 665                }
 666                glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
 667                clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 668        }
 669
 670skip_inval:
 671        gfs2_glock_hold(gl);
 672        /*
 673         * Check for an error encountered since we called go_sync and go_inval.
 674         * If so, we can't withdraw from the glock code because the withdraw
 675         * code itself uses glocks (see function signal_our_withdraw) to
 676         * change the mount to read-only. Most importantly, we must not call
 677         * dlm to unlock the glock until the journal is in a known good state
 678         * (after journal replay) otherwise other nodes may use the object
 679         * (rgrp or dinode) and then later, journal replay will corrupt the
 680         * file system. The best we can do here is wait for the logd daemon
 681         * to see sd_log_error and withdraw, and in the meantime, requeue the
 682         * work for later.
 683         *
 684         * We make a special exception for some system glocks, such as the
 685         * system statfs inode glock, which needs to be granted before the
 686         * gfs2_quotad daemon can exit, and that exit needs to finish before
 687         * we can unmount the withdrawn file system.
 688         *
 689         * However, if we're just unlocking the lock (say, for unmount, when
 690         * gfs2_gl_hash_clear calls clear_glock) and recovery is complete
 691         * then it's okay to tell dlm to unlock it.
 692         */
 693        if (unlikely(sdp->sd_log_error && !gfs2_withdrawn(sdp)))
 694                gfs2_withdraw_delayed(sdp);
 695        if (glock_blocked_by_withdraw(gl) &&
 696            (target != LM_ST_UNLOCKED ||
 697             test_bit(SDF_WITHDRAW_RECOVERY, &sdp->sd_flags))) {
 698                if (!is_system_glock(gl)) {
 699                        gfs2_glock_queue_work(gl, GL_GLOCK_DFT_HOLD);
 700                        goto out;
 701                } else {
 702                        clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 703                }
 704        }
 705
 706        if (sdp->sd_lockstruct.ls_ops->lm_lock) {
 707                /* lock_dlm */
 708                ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
 709                if (ret == -EINVAL && gl->gl_target == LM_ST_UNLOCKED &&
 710                    target == LM_ST_UNLOCKED &&
 711                    test_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags)) {
 712                        finish_xmote(gl, target);
 713                        gfs2_glock_queue_work(gl, 0);
 714                } else if (ret) {
 715                        fs_err(sdp, "lm_lock ret %d\n", ret);
 716                        GLOCK_BUG_ON(gl, !gfs2_withdrawn(sdp));
 717                }
 718        } else { /* lock_nolock */
 719                finish_xmote(gl, target);
 720                gfs2_glock_queue_work(gl, 0);
 721        }
 722out:
 723        spin_lock(&gl->gl_lockref.lock);
 724}
 725
 726/**
 727 * find_first_holder - find the first "holder" gh
 728 * @gl: the glock
 729 */
 730
 731static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
 732{
 733        struct gfs2_holder *gh;
 734
 735        if (!list_empty(&gl->gl_holders)) {
 736                gh = list_first_entry(&gl->gl_holders, struct gfs2_holder, gh_list);
 737                if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 738                        return gh;
 739        }
 740        return NULL;
 741}
 742
 743/**
 744 * run_queue - do all outstanding tasks related to a glock
 745 * @gl: The glock in question
 746 * @nonblock: True if we must not block in run_queue
 747 *
 748 */
 749
 750static void run_queue(struct gfs2_glock *gl, const int nonblock)
 751__releases(&gl->gl_lockref.lock)
 752__acquires(&gl->gl_lockref.lock)
 753{
 754        struct gfs2_holder *gh = NULL;
 755        int ret;
 756
 757        if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 758                return;
 759
 760        GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
 761
 762        if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
 763            gl->gl_demote_state != gl->gl_state) {
 764                if (find_first_holder(gl))
 765                        goto out_unlock;
 766                if (nonblock)
 767                        goto out_sched;
 768                set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
 769                GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
 770                gl->gl_target = gl->gl_demote_state;
 771        } else {
 772                if (test_bit(GLF_DEMOTE, &gl->gl_flags))
 773                        gfs2_demote_wake(gl);
 774                ret = do_promote(gl);
 775                if (ret == 0)
 776                        goto out_unlock;
 777                if (ret == 2)
 778                        goto out;
 779                gh = find_first_waiter(gl);
 780                gl->gl_target = gh->gh_state;
 781                if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 782                        do_error(gl, 0); /* Fail queued try locks */
 783        }
 784        do_xmote(gl, gh, gl->gl_target);
 785out:
 786        return;
 787
 788out_sched:
 789        clear_bit(GLF_LOCK, &gl->gl_flags);
 790        smp_mb__after_atomic();
 791        gl->gl_lockref.count++;
 792        __gfs2_glock_queue_work(gl, 0);
 793        return;
 794
 795out_unlock:
 796        clear_bit(GLF_LOCK, &gl->gl_flags);
 797        smp_mb__after_atomic();
 798        return;
 799}
 800
 801void gfs2_inode_remember_delete(struct gfs2_glock *gl, u64 generation)
 802{
 803        struct gfs2_inode_lvb *ri = (void *)gl->gl_lksb.sb_lvbptr;
 804
 805        if (ri->ri_magic == 0)
 806                ri->ri_magic = cpu_to_be32(GFS2_MAGIC);
 807        if (ri->ri_magic == cpu_to_be32(GFS2_MAGIC))
 808                ri->ri_generation_deleted = cpu_to_be64(generation);
 809}
 810
 811bool gfs2_inode_already_deleted(struct gfs2_glock *gl, u64 generation)
 812{
 813        struct gfs2_inode_lvb *ri = (void *)gl->gl_lksb.sb_lvbptr;
 814
 815        if (ri->ri_magic != cpu_to_be32(GFS2_MAGIC))
 816                return false;
 817        return generation <= be64_to_cpu(ri->ri_generation_deleted);
 818}
 819
 820static void gfs2_glock_poke(struct gfs2_glock *gl)
 821{
 822        int flags = LM_FLAG_TRY_1CB | LM_FLAG_ANY | GL_SKIP;
 823        struct gfs2_holder gh;
 824        int error;
 825
 826        gfs2_holder_init(gl, LM_ST_SHARED, flags, &gh);
 827        error = gfs2_glock_nq(&gh);
 828        if (!error)
 829                gfs2_glock_dq(&gh);
 830        gfs2_holder_uninit(&gh);
 831}
 832
 833static bool gfs2_try_evict(struct gfs2_glock *gl)
 834{
 835        struct gfs2_inode *ip;
 836        bool evicted = false;
 837
 838        /*
 839         * If there is contention on the iopen glock and we have an inode, try
 840         * to grab and release the inode so that it can be evicted.  This will
 841         * allow the remote node to go ahead and delete the inode without us
 842         * having to do it, which will avoid rgrp glock thrashing.
 843         *
 844         * The remote node is likely still holding the corresponding inode
 845         * glock, so it will run before we get to verify that the delete has
 846         * happened below.
 847         */
 848        spin_lock(&gl->gl_lockref.lock);
 849        ip = gl->gl_object;
 850        if (ip && !igrab(&ip->i_inode))
 851                ip = NULL;
 852        spin_unlock(&gl->gl_lockref.lock);
 853        if (ip) {
 854                struct gfs2_glock *inode_gl = NULL;
 855
 856                gl->gl_no_formal_ino = ip->i_no_formal_ino;
 857                set_bit(GIF_DEFERRED_DELETE, &ip->i_flags);
 858                d_prune_aliases(&ip->i_inode);
 859                iput(&ip->i_inode);
 860
 861                /* If the inode was evicted, gl->gl_object will now be NULL. */
 862                spin_lock(&gl->gl_lockref.lock);
 863                ip = gl->gl_object;
 864                if (ip) {
 865                        inode_gl = ip->i_gl;
 866                        lockref_get(&inode_gl->gl_lockref);
 867                        clear_bit(GIF_DEFERRED_DELETE, &ip->i_flags);
 868                }
 869                spin_unlock(&gl->gl_lockref.lock);
 870                if (inode_gl) {
 871                        gfs2_glock_poke(inode_gl);
 872                        gfs2_glock_put(inode_gl);
 873                }
 874                evicted = !ip;
 875        }
 876        return evicted;
 877}
 878
 879static void delete_work_func(struct work_struct *work)
 880{
 881        struct delayed_work *dwork = to_delayed_work(work);
 882        struct gfs2_glock *gl = container_of(dwork, struct gfs2_glock, gl_delete);
 883        struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 884        struct inode *inode;
 885        u64 no_addr = gl->gl_name.ln_number;
 886
 887        spin_lock(&gl->gl_lockref.lock);
 888        clear_bit(GLF_PENDING_DELETE, &gl->gl_flags);
 889        spin_unlock(&gl->gl_lockref.lock);
 890
 891        if (test_bit(GLF_DEMOTE, &gl->gl_flags)) {
 892                /*
 893                 * If we can evict the inode, give the remote node trying to
 894                 * delete the inode some time before verifying that the delete
 895                 * has happened.  Otherwise, if we cause contention on the inode glock
 896                 * immediately, the remote node will think that we still have
 897                 * the inode in use, and so it will give up waiting.
 898                 *
 899                 * If we can't evict the inode, signal to the remote node that
 900                 * the inode is still in use.  We'll later try to delete the
 901                 * inode locally in gfs2_evict_inode.
 902                 *
 903                 * FIXME: We only need to verify that the remote node has
 904                 * deleted the inode because nodes before this remote delete
 905                 * rework won't cooperate.  At a later time, when we no longer
 906                 * care about compatibility with such nodes, we can skip this
 907                 * step entirely.
 908                 */
 909                if (gfs2_try_evict(gl)) {
 910                        if (gfs2_queue_delete_work(gl, 5 * HZ))
 911                                return;
 912                }
 913                goto out;
 914        }
 915
 916        inode = gfs2_lookup_by_inum(sdp, no_addr, gl->gl_no_formal_ino,
 917                                    GFS2_BLKST_UNLINKED);
 918        if (!IS_ERR_OR_NULL(inode)) {
 919                d_prune_aliases(inode);
 920                iput(inode);
 921        }
 922out:
 923        gfs2_glock_put(gl);
 924}
 925
 926static void glock_work_func(struct work_struct *work)
 927{
 928        unsigned long delay = 0;
 929        struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
 930        unsigned int drop_refs = 1;
 931
 932        if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
 933                finish_xmote(gl, gl->gl_reply);
 934                drop_refs++;
 935        }
 936        spin_lock(&gl->gl_lockref.lock);
 937        if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
 938            gl->gl_state != LM_ST_UNLOCKED &&
 939            gl->gl_demote_state != LM_ST_EXCLUSIVE) {
 940                unsigned long holdtime, now = jiffies;
 941
 942                holdtime = gl->gl_tchange + gl->gl_hold_time;
 943                if (time_before(now, holdtime))
 944                        delay = holdtime - now;
 945
 946                if (!delay) {
 947                        clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
 948                        gfs2_set_demote(gl);
 949                }
 950        }
 951        run_queue(gl, 0);
 952        if (delay) {
 953                /* Keep one glock reference for the work we requeue. */
 954                drop_refs--;
 955                if (gl->gl_name.ln_type != LM_TYPE_INODE)
 956                        delay = 0;
 957                __gfs2_glock_queue_work(gl, delay);
 958        }
 959
 960        /*
 961         * Drop the remaining glock references manually here. (Mind that
 962         * __gfs2_glock_queue_work depends on the lockref spinlock begin held
 963         * here as well.)
 964         */
 965        gl->gl_lockref.count -= drop_refs;
 966        if (!gl->gl_lockref.count) {
 967                __gfs2_glock_put(gl);
 968                return;
 969        }
 970        spin_unlock(&gl->gl_lockref.lock);
 971}
 972
 973static struct gfs2_glock *find_insert_glock(struct lm_lockname *name,
 974                                            struct gfs2_glock *new)
 975{
 976        struct wait_glock_queue wait;
 977        wait_queue_head_t *wq = glock_waitqueue(name);
 978        struct gfs2_glock *gl;
 979
 980        wait.name = name;
 981        init_wait(&wait.wait);
 982        wait.wait.func = glock_wake_function;
 983
 984again:
 985        prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
 986        rcu_read_lock();
 987        if (new) {
 988                gl = rhashtable_lookup_get_insert_fast(&gl_hash_table,
 989                        &new->gl_node, ht_parms);
 990                if (IS_ERR(gl))
 991                        goto out;
 992        } else {
 993                gl = rhashtable_lookup_fast(&gl_hash_table,
 994                        name, ht_parms);
 995        }
 996        if (gl && !lockref_get_not_dead(&gl->gl_lockref)) {
 997                rcu_read_unlock();
 998                schedule();
 999                goto again;
1000        }
1001out:
1002        rcu_read_unlock();
1003        finish_wait(wq, &wait.wait);
1004        return gl;
1005}
1006
1007/**
1008 * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
1009 * @sdp: The GFS2 superblock
1010 * @number: the lock number
1011 * @glops: The glock_operations to use
1012 * @create: If 0, don't create the glock if it doesn't exist
1013 * @glp: the glock is returned here
1014 *
1015 * This does not lock a glock, just finds/creates structures for one.
1016 *
1017 * Returns: errno
1018 */
1019
1020int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
1021                   const struct gfs2_glock_operations *glops, int create,
1022                   struct gfs2_glock **glp)
1023{
1024        struct super_block *s = sdp->sd_vfs;
1025        struct lm_lockname name = { .ln_number = number,
1026                                    .ln_type = glops->go_type,
1027                                    .ln_sbd = sdp };
1028        struct gfs2_glock *gl, *tmp;
1029        struct address_space *mapping;
1030        struct kmem_cache *cachep;
1031        int ret = 0;
1032
1033        gl = find_insert_glock(&name, NULL);
1034        if (gl) {
1035                *glp = gl;
1036                return 0;
1037        }
1038        if (!create)
1039                return -ENOENT;
1040
1041        if (glops->go_flags & GLOF_ASPACE)
1042                cachep = gfs2_glock_aspace_cachep;
1043        else
1044                cachep = gfs2_glock_cachep;
1045        gl = kmem_cache_alloc(cachep, GFP_NOFS);
1046        if (!gl)
1047                return -ENOMEM;
1048
1049        memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
1050
1051        if (glops->go_flags & GLOF_LVB) {
1052                gl->gl_lksb.sb_lvbptr = kzalloc(GDLM_LVB_SIZE, GFP_NOFS);
1053                if (!gl->gl_lksb.sb_lvbptr) {
1054                        kmem_cache_free(cachep, gl);
1055                        return -ENOMEM;
1056                }
1057        }
1058
1059        atomic_inc(&sdp->sd_glock_disposal);
1060        gl->gl_node.next = NULL;
1061        gl->gl_flags = 0;
1062        gl->gl_name = name;
1063        lockdep_set_subclass(&gl->gl_lockref.lock, glops->go_subclass);
1064        gl->gl_lockref.count = 1;
1065        gl->gl_state = LM_ST_UNLOCKED;
1066        gl->gl_target = LM_ST_UNLOCKED;
1067        gl->gl_demote_state = LM_ST_EXCLUSIVE;
1068        gl->gl_ops = glops;
1069        gl->gl_dstamp = 0;
1070        preempt_disable();
1071        /* We use the global stats to estimate the initial per-glock stats */
1072        gl->gl_stats = this_cpu_ptr(sdp->sd_lkstats)->lkstats[glops->go_type];
1073        preempt_enable();
1074        gl->gl_stats.stats[GFS2_LKS_DCOUNT] = 0;
1075        gl->gl_stats.stats[GFS2_LKS_QCOUNT] = 0;
1076        gl->gl_tchange = jiffies;
1077        gl->gl_object = NULL;
1078        gl->gl_hold_time = GL_GLOCK_DFT_HOLD;
1079        INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
1080        if (gl->gl_name.ln_type == LM_TYPE_IOPEN)
1081                INIT_DELAYED_WORK(&gl->gl_delete, delete_work_func);
1082
1083        mapping = gfs2_glock2aspace(gl);
1084        if (mapping) {
1085                mapping->a_ops = &gfs2_meta_aops;
1086                mapping->host = s->s_bdev->bd_inode;
1087                mapping->flags = 0;
1088                mapping_set_gfp_mask(mapping, GFP_NOFS);
1089                mapping->private_data = NULL;
1090                mapping->writeback_index = 0;
1091        }
1092
1093        tmp = find_insert_glock(&name, gl);
1094        if (!tmp) {
1095                *glp = gl;
1096                goto out;
1097        }
1098        if (IS_ERR(tmp)) {
1099                ret = PTR_ERR(tmp);
1100                goto out_free;
1101        }
1102        *glp = tmp;
1103
1104out_free:
1105        kfree(gl->gl_lksb.sb_lvbptr);
1106        kmem_cache_free(cachep, gl);
1107        if (atomic_dec_and_test(&sdp->sd_glock_disposal))
1108                wake_up(&sdp->sd_glock_wait);
1109
1110out:
1111        return ret;
1112}
1113
1114/**
1115 * gfs2_holder_init - initialize a struct gfs2_holder in the default way
1116 * @gl: the glock
1117 * @state: the state we're requesting
1118 * @flags: the modifier flags
1119 * @gh: the holder structure
1120 *
1121 */
1122
1123void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, u16 flags,
1124                      struct gfs2_holder *gh)
1125{
1126        INIT_LIST_HEAD(&gh->gh_list);
1127        gh->gh_gl = gl;
1128        gh->gh_ip = _RET_IP_;
1129        gh->gh_owner_pid = get_pid(task_pid(current));
1130        gh->gh_state = state;
1131        gh->gh_flags = flags;
1132        gh->gh_error = 0;
1133        gh->gh_iflags = 0;
1134        gfs2_glock_hold(gl);
1135}
1136
1137/**
1138 * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
1139 * @state: the state we're requesting
1140 * @flags: the modifier flags
1141 * @gh: the holder structure
1142 *
1143 * Don't mess with the glock.
1144 *
1145 */
1146
1147void gfs2_holder_reinit(unsigned int state, u16 flags, struct gfs2_holder *gh)
1148{
1149        gh->gh_state = state;
1150        gh->gh_flags = flags;
1151        gh->gh_iflags = 0;
1152        gh->gh_ip = _RET_IP_;
1153        put_pid(gh->gh_owner_pid);
1154        gh->gh_owner_pid = get_pid(task_pid(current));
1155}
1156
1157/**
1158 * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
1159 * @gh: the holder structure
1160 *
1161 */
1162
1163void gfs2_holder_uninit(struct gfs2_holder *gh)
1164{
1165        put_pid(gh->gh_owner_pid);
1166        gfs2_glock_put(gh->gh_gl);
1167        gfs2_holder_mark_uninitialized(gh);
1168        gh->gh_ip = 0;
1169}
1170
1171static void gfs2_glock_update_hold_time(struct gfs2_glock *gl,
1172                                        unsigned long start_time)
1173{
1174        /* Have we waited longer that a second? */
1175        if (time_after(jiffies, start_time + HZ)) {
1176                /* Lengthen the minimum hold time. */
1177                gl->gl_hold_time = min(gl->gl_hold_time + GL_GLOCK_HOLD_INCR,
1178                                       GL_GLOCK_MAX_HOLD);
1179        }
1180}
1181
1182/**
1183 * gfs2_glock_wait - wait on a glock acquisition
1184 * @gh: the glock holder
1185 *
1186 * Returns: 0 on success
1187 */
1188
1189int gfs2_glock_wait(struct gfs2_holder *gh)
1190{
1191        unsigned long start_time = jiffies;
1192
1193        might_sleep();
1194        wait_on_bit(&gh->gh_iflags, HIF_WAIT, TASK_UNINTERRUPTIBLE);
1195        gfs2_glock_update_hold_time(gh->gh_gl, start_time);
1196        return gh->gh_error;
1197}
1198
1199static int glocks_pending(unsigned int num_gh, struct gfs2_holder *ghs)
1200{
1201        int i;
1202
1203        for (i = 0; i < num_gh; i++)
1204                if (test_bit(HIF_WAIT, &ghs[i].gh_iflags))
1205                        return 1;
1206        return 0;
1207}
1208
1209/**
1210 * gfs2_glock_async_wait - wait on multiple asynchronous glock acquisitions
1211 * @num_gh: the number of holders in the array
1212 * @ghs: the glock holder array
1213 *
1214 * Returns: 0 on success, meaning all glocks have been granted and are held.
1215 *          -ESTALE if the request timed out, meaning all glocks were released,
1216 *          and the caller should retry the operation.
1217 */
1218
1219int gfs2_glock_async_wait(unsigned int num_gh, struct gfs2_holder *ghs)
1220{
1221        struct gfs2_sbd *sdp = ghs[0].gh_gl->gl_name.ln_sbd;
1222        int i, ret = 0, timeout = 0;
1223        unsigned long start_time = jiffies;
1224        bool keep_waiting;
1225
1226        might_sleep();
1227        /*
1228         * Total up the (minimum hold time * 2) of all glocks and use that to
1229         * determine the max amount of time we should wait.
1230         */
1231        for (i = 0; i < num_gh; i++)
1232                timeout += ghs[i].gh_gl->gl_hold_time << 1;
1233
1234wait_for_dlm:
1235        if (!wait_event_timeout(sdp->sd_async_glock_wait,
1236                                !glocks_pending(num_gh, ghs), timeout))
1237                ret = -ESTALE; /* request timed out. */
1238
1239        /*
1240         * If dlm granted all our requests, we need to adjust the glock
1241         * minimum hold time values according to how long we waited.
1242         *
1243         * If our request timed out, we need to repeatedly release any held
1244         * glocks we acquired thus far to allow dlm to acquire the remaining
1245         * glocks without deadlocking.  We cannot currently cancel outstanding
1246         * glock acquisitions.
1247         *
1248         * The HIF_WAIT bit tells us which requests still need a response from
1249         * dlm.
1250         *
1251         * If dlm sent us any errors, we return the first error we find.
1252         */
1253        keep_waiting = false;
1254        for (i = 0; i < num_gh; i++) {
1255                /* Skip holders we have already dequeued below. */
1256                if (!gfs2_holder_queued(&ghs[i]))
1257                        continue;
1258                /* Skip holders with a pending DLM response. */
1259                if (test_bit(HIF_WAIT, &ghs[i].gh_iflags)) {
1260                        keep_waiting = true;
1261                        continue;
1262                }
1263
1264                if (test_bit(HIF_HOLDER, &ghs[i].gh_iflags)) {
1265                        if (ret == -ESTALE)
1266                                gfs2_glock_dq(&ghs[i]);
1267                        else
1268                                gfs2_glock_update_hold_time(ghs[i].gh_gl,
1269                                                            start_time);
1270                }
1271                if (!ret)
1272                        ret = ghs[i].gh_error;
1273        }
1274
1275        if (keep_waiting)
1276                goto wait_for_dlm;
1277
1278        /*
1279         * At this point, we've either acquired all locks or released them all.
1280         */
1281        return ret;
1282}
1283
1284/**
1285 * handle_callback - process a demote request
1286 * @gl: the glock
1287 * @state: the state the caller wants us to change to
1288 * @delay: zero to demote immediately; otherwise pending demote
1289 * @remote: true if this came from a different cluster node
1290 *
1291 * There are only two requests that we are going to see in actual
1292 * practise: LM_ST_SHARED and LM_ST_UNLOCKED
1293 */
1294
1295static void handle_callback(struct gfs2_glock *gl, unsigned int state,
1296                            unsigned long delay, bool remote)
1297{
1298        if (delay)
1299                set_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
1300        else
1301                gfs2_set_demote(gl);
1302        if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
1303                gl->gl_demote_state = state;
1304                gl->gl_demote_time = jiffies;
1305        } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
1306                        gl->gl_demote_state != state) {
1307                gl->gl_demote_state = LM_ST_UNLOCKED;
1308        }
1309        if (gl->gl_ops->go_callback)
1310                gl->gl_ops->go_callback(gl, remote);
1311        trace_gfs2_demote_rq(gl, remote);
1312}
1313
1314void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
1315{
1316        struct va_format vaf;
1317        va_list args;
1318
1319        va_start(args, fmt);
1320
1321        if (seq) {
1322                seq_vprintf(seq, fmt, args);
1323        } else {
1324                vaf.fmt = fmt;
1325                vaf.va = &args;
1326
1327                pr_err("%pV", &vaf);
1328        }
1329
1330        va_end(args);
1331}
1332
1333/**
1334 * add_to_queue - Add a holder to the wait queue (but look for recursion)
1335 * @gh: the holder structure to add
1336 *
1337 * Eventually we should move the recursive locking trap to a
1338 * debugging option or something like that. This is the fast
1339 * path and needs to have the minimum number of distractions.
1340 * 
1341 */
1342
1343static inline void add_to_queue(struct gfs2_holder *gh)
1344__releases(&gl->gl_lockref.lock)
1345__acquires(&gl->gl_lockref.lock)
1346{
1347        struct gfs2_glock *gl = gh->gh_gl;
1348        struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
1349        struct list_head *insert_pt = NULL;
1350        struct gfs2_holder *gh2;
1351        int try_futile = 0;
1352
1353        GLOCK_BUG_ON(gl, gh->gh_owner_pid == NULL);
1354        if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
1355                GLOCK_BUG_ON(gl, true);
1356
1357        if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
1358                if (test_bit(GLF_LOCK, &gl->gl_flags))
1359                        try_futile = !may_grant(gl, gh);
1360                if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
1361                        goto fail;
1362        }
1363
1364        list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
1365                if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
1366                    (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
1367                        goto trap_recursive;
1368                if (try_futile &&
1369                    !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
1370fail:
1371                        gh->gh_error = GLR_TRYFAILED;
1372                        gfs2_holder_wake(gh);
1373                        return;
1374                }
1375                if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
1376                        continue;
1377                if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
1378                        insert_pt = &gh2->gh_list;
1379        }
1380        trace_gfs2_glock_queue(gh, 1);
1381        gfs2_glstats_inc(gl, GFS2_LKS_QCOUNT);
1382        gfs2_sbstats_inc(gl, GFS2_LKS_QCOUNT);
1383        if (likely(insert_pt == NULL)) {
1384                list_add_tail(&gh->gh_list, &gl->gl_holders);
1385                if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
1386                        goto do_cancel;
1387                return;
1388        }
1389        list_add_tail(&gh->gh_list, insert_pt);
1390do_cancel:
1391        gh = list_first_entry(&gl->gl_holders, struct gfs2_holder, gh_list);
1392        if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
1393                spin_unlock(&gl->gl_lockref.lock);
1394                if (sdp->sd_lockstruct.ls_ops->lm_cancel)
1395                        sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
1396                spin_lock(&gl->gl_lockref.lock);
1397        }
1398        return;
1399
1400trap_recursive:
1401        fs_err(sdp, "original: %pSR\n", (void *)gh2->gh_ip);
1402        fs_err(sdp, "pid: %d\n", pid_nr(gh2->gh_owner_pid));
1403        fs_err(sdp, "lock type: %d req lock state : %d\n",
1404               gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
1405        fs_err(sdp, "new: %pSR\n", (void *)gh->gh_ip);
1406        fs_err(sdp, "pid: %d\n", pid_nr(gh->gh_owner_pid));
1407        fs_err(sdp, "lock type: %d req lock state : %d\n",
1408               gh->gh_gl->gl_name.ln_type, gh->gh_state);
1409        gfs2_dump_glock(NULL, gl, true);
1410        BUG();
1411}
1412
1413/**
1414 * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1415 * @gh: the holder structure
1416 *
1417 * if (gh->gh_flags & GL_ASYNC), this never returns an error
1418 *
1419 * Returns: 0, GLR_TRYFAILED, or errno on failure
1420 */
1421
1422int gfs2_glock_nq(struct gfs2_holder *gh)
1423{
1424        struct gfs2_glock *gl = gh->gh_gl;
1425        int error = 0;
1426
1427        if (glock_blocked_by_withdraw(gl) && !(gh->gh_flags & LM_FLAG_NOEXP))
1428                return -EIO;
1429
1430        if (test_bit(GLF_LRU, &gl->gl_flags))
1431                gfs2_glock_remove_from_lru(gl);
1432
1433        spin_lock(&gl->gl_lockref.lock);
1434        add_to_queue(gh);
1435        if (unlikely((LM_FLAG_NOEXP & gh->gh_flags) &&
1436                     test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))) {
1437                set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1438                gl->gl_lockref.count++;
1439                __gfs2_glock_queue_work(gl, 0);
1440        }
1441        run_queue(gl, 1);
1442        spin_unlock(&gl->gl_lockref.lock);
1443
1444        if (!(gh->gh_flags & GL_ASYNC))
1445                error = gfs2_glock_wait(gh);
1446
1447        return error;
1448}
1449
1450/**
1451 * gfs2_glock_poll - poll to see if an async request has been completed
1452 * @gh: the holder
1453 *
1454 * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1455 */
1456
1457int gfs2_glock_poll(struct gfs2_holder *gh)
1458{
1459        return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1460}
1461
1462/**
1463 * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1464 * @gh: the glock holder
1465 *
1466 */
1467
1468void gfs2_glock_dq(struct gfs2_holder *gh)
1469{
1470        struct gfs2_glock *gl = gh->gh_gl;
1471        struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
1472        unsigned delay = 0;
1473        int fast_path = 0;
1474
1475        spin_lock(&gl->gl_lockref.lock);
1476        /*
1477         * If we're in the process of file system withdraw, we cannot just
1478         * dequeue any glocks until our journal is recovered, lest we
1479         * introduce file system corruption. We need two exceptions to this
1480         * rule: We need to allow unlocking of nondisk glocks and the glock
1481         * for our own journal that needs recovery.
1482         */
1483        if (test_bit(SDF_WITHDRAW_RECOVERY, &sdp->sd_flags) &&
1484            glock_blocked_by_withdraw(gl) &&
1485            gh->gh_gl != sdp->sd_jinode_gl) {
1486                sdp->sd_glock_dqs_held++;
1487                spin_unlock(&gl->gl_lockref.lock);
1488                might_sleep();
1489                wait_on_bit(&sdp->sd_flags, SDF_WITHDRAW_RECOVERY,
1490                            TASK_UNINTERRUPTIBLE);
1491                spin_lock(&gl->gl_lockref.lock);
1492        }
1493        if (gh->gh_flags & GL_NOCACHE)
1494                handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1495
1496        list_del_init(&gh->gh_list);
1497        clear_bit(HIF_HOLDER, &gh->gh_iflags);
1498        if (find_first_holder(gl) == NULL) {
1499                if (list_empty(&gl->gl_holders) &&
1500                    !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1501                    !test_bit(GLF_DEMOTE, &gl->gl_flags))
1502                        fast_path = 1;
1503        }
1504        if (!test_bit(GLF_LFLUSH, &gl->gl_flags) && demote_ok(gl))
1505                gfs2_glock_add_to_lru(gl);
1506
1507        trace_gfs2_glock_queue(gh, 0);
1508        if (unlikely(!fast_path)) {
1509                gl->gl_lockref.count++;
1510                if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1511                    !test_bit(GLF_DEMOTE, &gl->gl_flags) &&
1512                    gl->gl_name.ln_type == LM_TYPE_INODE)
1513                        delay = gl->gl_hold_time;
1514                __gfs2_glock_queue_work(gl, delay);
1515        }
1516        spin_unlock(&gl->gl_lockref.lock);
1517}
1518
1519void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1520{
1521        struct gfs2_glock *gl = gh->gh_gl;
1522        gfs2_glock_dq(gh);
1523        might_sleep();
1524        wait_on_bit(&gl->gl_flags, GLF_DEMOTE, TASK_UNINTERRUPTIBLE);
1525}
1526
1527/**
1528 * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1529 * @gh: the holder structure
1530 *
1531 */
1532
1533void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1534{
1535        gfs2_glock_dq(gh);
1536        gfs2_holder_uninit(gh);
1537}
1538
1539/**
1540 * gfs2_glock_nq_num - acquire a glock based on lock number
1541 * @sdp: the filesystem
1542 * @number: the lock number
1543 * @glops: the glock operations for the type of glock
1544 * @state: the state to acquire the glock in
1545 * @flags: modifier flags for the acquisition
1546 * @gh: the struct gfs2_holder
1547 *
1548 * Returns: errno
1549 */
1550
1551int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1552                      const struct gfs2_glock_operations *glops,
1553                      unsigned int state, u16 flags, struct gfs2_holder *gh)
1554{
1555        struct gfs2_glock *gl;
1556        int error;
1557
1558        error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1559        if (!error) {
1560                error = gfs2_glock_nq_init(gl, state, flags, gh);
1561                gfs2_glock_put(gl);
1562        }
1563
1564        return error;
1565}
1566
1567/**
1568 * glock_compare - Compare two struct gfs2_glock structures for sorting
1569 * @arg_a: the first structure
1570 * @arg_b: the second structure
1571 *
1572 */
1573
1574static int glock_compare(const void *arg_a, const void *arg_b)
1575{
1576        const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1577        const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1578        const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1579        const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1580
1581        if (a->ln_number > b->ln_number)
1582                return 1;
1583        if (a->ln_number < b->ln_number)
1584                return -1;
1585        BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1586        return 0;
1587}
1588
1589/**
1590 * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1591 * @num_gh: the number of structures
1592 * @ghs: an array of struct gfs2_holder structures
1593 * @p: placeholder for the holder structure to pass back
1594 *
1595 * Returns: 0 on success (all glocks acquired),
1596 *          errno on failure (no glocks acquired)
1597 */
1598
1599static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1600                     struct gfs2_holder **p)
1601{
1602        unsigned int x;
1603        int error = 0;
1604
1605        for (x = 0; x < num_gh; x++)
1606                p[x] = &ghs[x];
1607
1608        sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1609
1610        for (x = 0; x < num_gh; x++) {
1611                p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1612
1613                error = gfs2_glock_nq(p[x]);
1614                if (error) {
1615                        while (x--)
1616                                gfs2_glock_dq(p[x]);
1617                        break;
1618                }
1619        }
1620
1621        return error;
1622}
1623
1624/**
1625 * gfs2_glock_nq_m - acquire multiple glocks
1626 * @num_gh: the number of structures
1627 * @ghs: an array of struct gfs2_holder structures
1628 *
1629 *
1630 * Returns: 0 on success (all glocks acquired),
1631 *          errno on failure (no glocks acquired)
1632 */
1633
1634int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1635{
1636        struct gfs2_holder *tmp[4];
1637        struct gfs2_holder **pph = tmp;
1638        int error = 0;
1639
1640        switch(num_gh) {
1641        case 0:
1642                return 0;
1643        case 1:
1644                ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1645                return gfs2_glock_nq(ghs);
1646        default:
1647                if (num_gh <= 4)
1648                        break;
1649                pph = kmalloc_array(num_gh, sizeof(struct gfs2_holder *),
1650                                    GFP_NOFS);
1651                if (!pph)
1652                        return -ENOMEM;
1653        }
1654
1655        error = nq_m_sync(num_gh, ghs, pph);
1656
1657        if (pph != tmp)
1658                kfree(pph);
1659
1660        return error;
1661}
1662
1663/**
1664 * gfs2_glock_dq_m - release multiple glocks
1665 * @num_gh: the number of structures
1666 * @ghs: an array of struct gfs2_holder structures
1667 *
1668 */
1669
1670void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1671{
1672        while (num_gh--)
1673                gfs2_glock_dq(&ghs[num_gh]);
1674}
1675
1676void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1677{
1678        unsigned long delay = 0;
1679        unsigned long holdtime;
1680        unsigned long now = jiffies;
1681
1682        gfs2_glock_hold(gl);
1683        spin_lock(&gl->gl_lockref.lock);
1684        holdtime = gl->gl_tchange + gl->gl_hold_time;
1685        if (!list_empty(&gl->gl_holders) &&
1686            gl->gl_name.ln_type == LM_TYPE_INODE) {
1687                if (time_before(now, holdtime))
1688                        delay = holdtime - now;
1689                if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1690                        delay = gl->gl_hold_time;
1691        }
1692        handle_callback(gl, state, delay, true);
1693        __gfs2_glock_queue_work(gl, delay);
1694        spin_unlock(&gl->gl_lockref.lock);
1695}
1696
1697/**
1698 * gfs2_should_freeze - Figure out if glock should be frozen
1699 * @gl: The glock in question
1700 *
1701 * Glocks are not frozen if (a) the result of the dlm operation is
1702 * an error, (b) the locking operation was an unlock operation or
1703 * (c) if there is a "noexp" flagged request anywhere in the queue
1704 *
1705 * Returns: 1 if freezing should occur, 0 otherwise
1706 */
1707
1708static int gfs2_should_freeze(const struct gfs2_glock *gl)
1709{
1710        const struct gfs2_holder *gh;
1711
1712        if (gl->gl_reply & ~LM_OUT_ST_MASK)
1713                return 0;
1714        if (gl->gl_target == LM_ST_UNLOCKED)
1715                return 0;
1716
1717        list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1718                if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1719                        continue;
1720                if (LM_FLAG_NOEXP & gh->gh_flags)
1721                        return 0;
1722        }
1723
1724        return 1;
1725}
1726
1727/**
1728 * gfs2_glock_complete - Callback used by locking
1729 * @gl: Pointer to the glock
1730 * @ret: The return value from the dlm
1731 *
1732 * The gl_reply field is under the gl_lockref.lock lock so that it is ok
1733 * to use a bitfield shared with other glock state fields.
1734 */
1735
1736void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1737{
1738        struct lm_lockstruct *ls = &gl->gl_name.ln_sbd->sd_lockstruct;
1739
1740        spin_lock(&gl->gl_lockref.lock);
1741        gl->gl_reply = ret;
1742
1743        if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags))) {
1744                if (gfs2_should_freeze(gl)) {
1745                        set_bit(GLF_FROZEN, &gl->gl_flags);
1746                        spin_unlock(&gl->gl_lockref.lock);
1747                        return;
1748                }
1749        }
1750
1751        gl->gl_lockref.count++;
1752        set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1753        __gfs2_glock_queue_work(gl, 0);
1754        spin_unlock(&gl->gl_lockref.lock);
1755}
1756
1757static int glock_cmp(void *priv, const struct list_head *a,
1758                     const struct list_head *b)
1759{
1760        struct gfs2_glock *gla, *glb;
1761
1762        gla = list_entry(a, struct gfs2_glock, gl_lru);
1763        glb = list_entry(b, struct gfs2_glock, gl_lru);
1764
1765        if (gla->gl_name.ln_number > glb->gl_name.ln_number)
1766                return 1;
1767        if (gla->gl_name.ln_number < glb->gl_name.ln_number)
1768                return -1;
1769
1770        return 0;
1771}
1772
1773/**
1774 * gfs2_dispose_glock_lru - Demote a list of glocks
1775 * @list: The list to dispose of
1776 *
1777 * Disposing of glocks may involve disk accesses, so that here we sort
1778 * the glocks by number (i.e. disk location of the inodes) so that if
1779 * there are any such accesses, they'll be sent in order (mostly).
1780 *
1781 * Must be called under the lru_lock, but may drop and retake this
1782 * lock. While the lru_lock is dropped, entries may vanish from the
1783 * list, but no new entries will appear on the list (since it is
1784 * private)
1785 */
1786
1787static void gfs2_dispose_glock_lru(struct list_head *list)
1788__releases(&lru_lock)
1789__acquires(&lru_lock)
1790{
1791        struct gfs2_glock *gl;
1792
1793        list_sort(NULL, list, glock_cmp);
1794
1795        while(!list_empty(list)) {
1796                gl = list_first_entry(list, struct gfs2_glock, gl_lru);
1797                list_del_init(&gl->gl_lru);
1798                clear_bit(GLF_LRU, &gl->gl_flags);
1799                if (!spin_trylock(&gl->gl_lockref.lock)) {
1800add_back_to_lru:
1801                        list_add(&gl->gl_lru, &lru_list);
1802                        set_bit(GLF_LRU, &gl->gl_flags);
1803                        atomic_inc(&lru_count);
1804                        continue;
1805                }
1806                if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1807                        spin_unlock(&gl->gl_lockref.lock);
1808                        goto add_back_to_lru;
1809                }
1810                gl->gl_lockref.count++;
1811                if (demote_ok(gl))
1812                        handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1813                WARN_ON(!test_and_clear_bit(GLF_LOCK, &gl->gl_flags));
1814                __gfs2_glock_queue_work(gl, 0);
1815                spin_unlock(&gl->gl_lockref.lock);
1816                cond_resched_lock(&lru_lock);
1817        }
1818}
1819
1820/**
1821 * gfs2_scan_glock_lru - Scan the LRU looking for locks to demote
1822 * @nr: The number of entries to scan
1823 *
1824 * This function selects the entries on the LRU which are able to
1825 * be demoted, and then kicks off the process by calling
1826 * gfs2_dispose_glock_lru() above.
1827 */
1828
1829static long gfs2_scan_glock_lru(int nr)
1830{
1831        struct gfs2_glock *gl;
1832        LIST_HEAD(skipped);
1833        LIST_HEAD(dispose);
1834        long freed = 0;
1835
1836        spin_lock(&lru_lock);
1837        while ((nr-- >= 0) && !list_empty(&lru_list)) {
1838                gl = list_first_entry(&lru_list, struct gfs2_glock, gl_lru);
1839
1840                /* Test for being demotable */
1841                if (!test_bit(GLF_LOCK, &gl->gl_flags)) {
1842                        list_move(&gl->gl_lru, &dispose);
1843                        atomic_dec(&lru_count);
1844                        freed++;
1845                        continue;
1846                }
1847
1848                list_move(&gl->gl_lru, &skipped);
1849        }
1850        list_splice(&skipped, &lru_list);
1851        if (!list_empty(&dispose))
1852                gfs2_dispose_glock_lru(&dispose);
1853        spin_unlock(&lru_lock);
1854
1855        return freed;
1856}
1857
1858static unsigned long gfs2_glock_shrink_scan(struct shrinker *shrink,
1859                                            struct shrink_control *sc)
1860{
1861        if (!(sc->gfp_mask & __GFP_FS))
1862                return SHRINK_STOP;
1863        return gfs2_scan_glock_lru(sc->nr_to_scan);
1864}
1865
1866static unsigned long gfs2_glock_shrink_count(struct shrinker *shrink,
1867                                             struct shrink_control *sc)
1868{
1869        return vfs_pressure_ratio(atomic_read(&lru_count));
1870}
1871
1872static struct shrinker glock_shrinker = {
1873        .seeks = DEFAULT_SEEKS,
1874        .count_objects = gfs2_glock_shrink_count,
1875        .scan_objects = gfs2_glock_shrink_scan,
1876};
1877
1878/**
1879 * glock_hash_walk - Call a function for glock in a hash bucket
1880 * @examiner: the function
1881 * @sdp: the filesystem
1882 *
1883 * Note that the function can be called multiple times on the same
1884 * object.  So the user must ensure that the function can cope with
1885 * that.
1886 */
1887
1888static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
1889{
1890        struct gfs2_glock *gl;
1891        struct rhashtable_iter iter;
1892
1893        rhashtable_walk_enter(&gl_hash_table, &iter);
1894
1895        do {
1896                rhashtable_walk_start(&iter);
1897
1898                while ((gl = rhashtable_walk_next(&iter)) && !IS_ERR(gl))
1899                        if (gl->gl_name.ln_sbd == sdp &&
1900                            lockref_get_not_dead(&gl->gl_lockref))
1901                                examiner(gl);
1902
1903                rhashtable_walk_stop(&iter);
1904        } while (cond_resched(), gl == ERR_PTR(-EAGAIN));
1905
1906        rhashtable_walk_exit(&iter);
1907}
1908
1909bool gfs2_queue_delete_work(struct gfs2_glock *gl, unsigned long delay)
1910{
1911        bool queued;
1912
1913        spin_lock(&gl->gl_lockref.lock);
1914        queued = queue_delayed_work(gfs2_delete_workqueue,
1915                                    &gl->gl_delete, delay);
1916        if (queued)
1917                set_bit(GLF_PENDING_DELETE, &gl->gl_flags);
1918        spin_unlock(&gl->gl_lockref.lock);
1919        return queued;
1920}
1921
1922void gfs2_cancel_delete_work(struct gfs2_glock *gl)
1923{
1924        if (cancel_delayed_work_sync(&gl->gl_delete)) {
1925                clear_bit(GLF_PENDING_DELETE, &gl->gl_flags);
1926                gfs2_glock_put(gl);
1927        }
1928}
1929
1930bool gfs2_delete_work_queued(const struct gfs2_glock *gl)
1931{
1932        return test_bit(GLF_PENDING_DELETE, &gl->gl_flags);
1933}
1934
1935static void flush_delete_work(struct gfs2_glock *gl)
1936{
1937        if (gl->gl_name.ln_type == LM_TYPE_IOPEN) {
1938                if (cancel_delayed_work(&gl->gl_delete)) {
1939                        queue_delayed_work(gfs2_delete_workqueue,
1940                                           &gl->gl_delete, 0);
1941                }
1942        }
1943        gfs2_glock_queue_work(gl, 0);
1944}
1945
1946void gfs2_flush_delete_work(struct gfs2_sbd *sdp)
1947{
1948        glock_hash_walk(flush_delete_work, sdp);
1949        flush_workqueue(gfs2_delete_workqueue);
1950}
1951
1952/**
1953 * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1954 * @gl: The glock to thaw
1955 *
1956 */
1957
1958static void thaw_glock(struct gfs2_glock *gl)
1959{
1960        if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags)) {
1961                gfs2_glock_put(gl);
1962                return;
1963        }
1964        set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1965        gfs2_glock_queue_work(gl, 0);
1966}
1967
1968/**
1969 * clear_glock - look at a glock and see if we can free it from glock cache
1970 * @gl: the glock to look at
1971 *
1972 */
1973
1974static void clear_glock(struct gfs2_glock *gl)
1975{
1976        gfs2_glock_remove_from_lru(gl);
1977
1978        spin_lock(&gl->gl_lockref.lock);
1979        if (gl->gl_state != LM_ST_UNLOCKED)
1980                handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1981        __gfs2_glock_queue_work(gl, 0);
1982        spin_unlock(&gl->gl_lockref.lock);
1983}
1984
1985/**
1986 * gfs2_glock_thaw - Thaw any frozen glocks
1987 * @sdp: The super block
1988 *
1989 */
1990
1991void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1992{
1993        glock_hash_walk(thaw_glock, sdp);
1994}
1995
1996static void dump_glock(struct seq_file *seq, struct gfs2_glock *gl, bool fsid)
1997{
1998        spin_lock(&gl->gl_lockref.lock);
1999        gfs2_dump_glock(seq, gl, fsid);
2000        spin_unlock(&gl->gl_lockref.lock);
2001}
2002
2003static void dump_glock_func(struct gfs2_glock *gl)
2004{
2005        dump_glock(NULL, gl, true);
2006}
2007
2008/**
2009 * gfs2_gl_hash_clear - Empty out the glock hash table
2010 * @sdp: the filesystem
2011 *
2012 * Called when unmounting the filesystem.
2013 */
2014
2015void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
2016{
2017        set_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags);
2018        flush_workqueue(glock_workqueue);
2019        glock_hash_walk(clear_glock, sdp);
2020        flush_workqueue(glock_workqueue);
2021        wait_event_timeout(sdp->sd_glock_wait,
2022                           atomic_read(&sdp->sd_glock_disposal) == 0,
2023                           HZ * 600);
2024        glock_hash_walk(dump_glock_func, sdp);
2025}
2026
2027void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
2028{
2029        struct gfs2_glock *gl = ip->i_gl;
2030        int ret;
2031
2032        ret = gfs2_truncatei_resume(ip);
2033        gfs2_glock_assert_withdraw(gl, ret == 0);
2034
2035        spin_lock(&gl->gl_lockref.lock);
2036        clear_bit(GLF_LOCK, &gl->gl_flags);
2037        run_queue(gl, 1);
2038        spin_unlock(&gl->gl_lockref.lock);
2039}
2040
2041static const char *state2str(unsigned state)
2042{
2043        switch(state) {
2044        case LM_ST_UNLOCKED:
2045                return "UN";
2046        case LM_ST_SHARED:
2047                return "SH";
2048        case LM_ST_DEFERRED:
2049                return "DF";
2050        case LM_ST_EXCLUSIVE:
2051                return "EX";
2052        }
2053        return "??";
2054}
2055
2056static const char *hflags2str(char *buf, u16 flags, unsigned long iflags)
2057{
2058        char *p = buf;
2059        if (flags & LM_FLAG_TRY)
2060                *p++ = 't';
2061        if (flags & LM_FLAG_TRY_1CB)
2062                *p++ = 'T';
2063        if (flags & LM_FLAG_NOEXP)
2064                *p++ = 'e';
2065        if (flags & LM_FLAG_ANY)
2066                *p++ = 'A';
2067        if (flags & LM_FLAG_PRIORITY)
2068                *p++ = 'p';
2069        if (flags & LM_FLAG_NODE_SCOPE)
2070                *p++ = 'n';
2071        if (flags & GL_ASYNC)
2072                *p++ = 'a';
2073        if (flags & GL_EXACT)
2074                *p++ = 'E';
2075        if (flags & GL_NOCACHE)
2076                *p++ = 'c';
2077        if (test_bit(HIF_HOLDER, &iflags))
2078                *p++ = 'H';
2079        if (test_bit(HIF_WAIT, &iflags))
2080                *p++ = 'W';
2081        if (test_bit(HIF_FIRST, &iflags))
2082                *p++ = 'F';
2083        *p = 0;
2084        return buf;
2085}
2086
2087/**
2088 * dump_holder - print information about a glock holder
2089 * @seq: the seq_file struct
2090 * @gh: the glock holder
2091 * @fs_id_buf: pointer to file system id (if requested)
2092 *
2093 */
2094
2095static void dump_holder(struct seq_file *seq, const struct gfs2_holder *gh,
2096                        const char *fs_id_buf)
2097{
2098        struct task_struct *gh_owner = NULL;
2099        char flags_buf[32];
2100
2101        rcu_read_lock();
2102        if (gh->gh_owner_pid)
2103                gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
2104        gfs2_print_dbg(seq, "%s H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
2105                       fs_id_buf, state2str(gh->gh_state),
2106                       hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
2107                       gh->gh_error,
2108                       gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
2109                       gh_owner ? gh_owner->comm : "(ended)",
2110                       (void *)gh->gh_ip);
2111        rcu_read_unlock();
2112}
2113
2114static const char *gflags2str(char *buf, const struct gfs2_glock *gl)
2115{
2116        const unsigned long *gflags = &gl->gl_flags;
2117        char *p = buf;
2118
2119        if (test_bit(GLF_LOCK, gflags))
2120                *p++ = 'l';
2121        if (test_bit(GLF_DEMOTE, gflags))
2122                *p++ = 'D';
2123        if (test_bit(GLF_PENDING_DEMOTE, gflags))
2124                *p++ = 'd';
2125        if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
2126                *p++ = 'p';
2127        if (test_bit(GLF_DIRTY, gflags))
2128                *p++ = 'y';
2129        if (test_bit(GLF_LFLUSH, gflags))
2130                *p++ = 'f';
2131        if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
2132                *p++ = 'i';
2133        if (test_bit(GLF_REPLY_PENDING, gflags))
2134                *p++ = 'r';
2135        if (test_bit(GLF_INITIAL, gflags))
2136                *p++ = 'I';
2137        if (test_bit(GLF_FROZEN, gflags))
2138                *p++ = 'F';
2139        if (!list_empty(&gl->gl_holders))
2140                *p++ = 'q';
2141        if (test_bit(GLF_LRU, gflags))
2142                *p++ = 'L';
2143        if (gl->gl_object)
2144                *p++ = 'o';
2145        if (test_bit(GLF_BLOCKING, gflags))
2146                *p++ = 'b';
2147        if (test_bit(GLF_PENDING_DELETE, gflags))
2148                *p++ = 'P';
2149        if (test_bit(GLF_FREEING, gflags))
2150                *p++ = 'x';
2151        *p = 0;
2152        return buf;
2153}
2154
2155/**
2156 * gfs2_dump_glock - print information about a glock
2157 * @seq: The seq_file struct
2158 * @gl: the glock
2159 * @fsid: If true, also dump the file system id
2160 *
2161 * The file format is as follows:
2162 * One line per object, capital letters are used to indicate objects
2163 * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
2164 * other objects are indented by a single space and follow the glock to
2165 * which they are related. Fields are indicated by lower case letters
2166 * followed by a colon and the field value, except for strings which are in
2167 * [] so that its possible to see if they are composed of spaces for
2168 * example. The field's are n = number (id of the object), f = flags,
2169 * t = type, s = state, r = refcount, e = error, p = pid.
2170 *
2171 */
2172
2173void gfs2_dump_glock(struct seq_file *seq, struct gfs2_glock *gl, bool fsid)
2174{
2175        const struct gfs2_glock_operations *glops = gl->gl_ops;
2176        unsigned long long dtime;
2177        const struct gfs2_holder *gh;
2178        char gflags_buf[32];
2179        struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
2180        char fs_id_buf[sizeof(sdp->sd_fsname) + 7];
2181        unsigned long nrpages = 0;
2182
2183        if (gl->gl_ops->go_flags & GLOF_ASPACE) {
2184                struct address_space *mapping = gfs2_glock2aspace(gl);
2185
2186                nrpages = mapping->nrpages;
2187        }
2188        memset(fs_id_buf, 0, sizeof(fs_id_buf));
2189        if (fsid && sdp) /* safety precaution */
2190                sprintf(fs_id_buf, "fsid=%s: ", sdp->sd_fsname);
2191        dtime = jiffies - gl->gl_demote_time;
2192        dtime *= 1000000/HZ; /* demote time in uSec */
2193        if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
2194                dtime = 0;
2195        gfs2_print_dbg(seq, "%sG:  s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d "
2196                       "v:%d r:%d m:%ld p:%lu\n",
2197                       fs_id_buf, state2str(gl->gl_state),
2198                       gl->gl_name.ln_type,
2199                       (unsigned long long)gl->gl_name.ln_number,
2200                       gflags2str(gflags_buf, gl),
2201                       state2str(gl->gl_target),
2202                       state2str(gl->gl_demote_state), dtime,
2203                       atomic_read(&gl->gl_ail_count),
2204                       atomic_read(&gl->gl_revokes),
2205                       (int)gl->gl_lockref.count, gl->gl_hold_time, nrpages);
2206
2207        list_for_each_entry(gh, &gl->gl_holders, gh_list)
2208                dump_holder(seq, gh, fs_id_buf);
2209
2210        if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
2211                glops->go_dump(seq, gl, fs_id_buf);
2212}
2213
2214static int gfs2_glstats_seq_show(struct seq_file *seq, void *iter_ptr)
2215{
2216        struct gfs2_glock *gl = iter_ptr;
2217
2218        seq_printf(seq, "G: n:%u/%llx rtt:%llu/%llu rttb:%llu/%llu irt:%llu/%llu dcnt: %llu qcnt: %llu\n",
2219                   gl->gl_name.ln_type,
2220                   (unsigned long long)gl->gl_name.ln_number,
2221                   (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTT],
2222                   (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTVAR],
2223                   (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTB],
2224                   (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTVARB],
2225                   (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SIRT],
2226                   (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SIRTVAR],
2227                   (unsigned long long)gl->gl_stats.stats[GFS2_LKS_DCOUNT],
2228                   (unsigned long long)gl->gl_stats.stats[GFS2_LKS_QCOUNT]);
2229        return 0;
2230}
2231
2232static const char *gfs2_gltype[] = {
2233        "type",
2234        "reserved",
2235        "nondisk",
2236        "inode",
2237        "rgrp",
2238        "meta",
2239        "iopen",
2240        "flock",
2241        "plock",
2242        "quota",
2243        "journal",
2244};
2245
2246static const char *gfs2_stype[] = {
2247        [GFS2_LKS_SRTT]         = "srtt",
2248        [GFS2_LKS_SRTTVAR]      = "srttvar",
2249        [GFS2_LKS_SRTTB]        = "srttb",
2250        [GFS2_LKS_SRTTVARB]     = "srttvarb",
2251        [GFS2_LKS_SIRT]         = "sirt",
2252        [GFS2_LKS_SIRTVAR]      = "sirtvar",
2253        [GFS2_LKS_DCOUNT]       = "dlm",
2254        [GFS2_LKS_QCOUNT]       = "queue",
2255};
2256
2257#define GFS2_NR_SBSTATS (ARRAY_SIZE(gfs2_gltype) * ARRAY_SIZE(gfs2_stype))
2258
2259static int gfs2_sbstats_seq_show(struct seq_file *seq, void *iter_ptr)
2260{
2261        struct gfs2_sbd *sdp = seq->private;
2262        loff_t pos = *(loff_t *)iter_ptr;
2263        unsigned index = pos >> 3;
2264        unsigned subindex = pos & 0x07;
2265        int i;
2266
2267        if (index == 0 && subindex != 0)
2268                return 0;
2269
2270        seq_printf(seq, "%-10s %8s:", gfs2_gltype[index],
2271                   (index == 0) ? "cpu": gfs2_stype[subindex]);
2272
2273        for_each_possible_cpu(i) {
2274                const struct gfs2_pcpu_lkstats *lkstats = per_cpu_ptr(sdp->sd_lkstats, i);
2275
2276                if (index == 0)
2277                        seq_printf(seq, " %15u", i);
2278                else
2279                        seq_printf(seq, " %15llu", (unsigned long long)lkstats->
2280                                   lkstats[index - 1].stats[subindex]);
2281        }
2282        seq_putc(seq, '\n');
2283        return 0;
2284}
2285
2286int __init gfs2_glock_init(void)
2287{
2288        int i, ret;
2289
2290        ret = rhashtable_init(&gl_hash_table, &ht_parms);
2291        if (ret < 0)
2292                return ret;
2293
2294        glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
2295                                          WQ_HIGHPRI | WQ_FREEZABLE, 0);
2296        if (!glock_workqueue) {
2297                rhashtable_destroy(&gl_hash_table);
2298                return -ENOMEM;
2299        }
2300        gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
2301                                                WQ_MEM_RECLAIM | WQ_FREEZABLE,
2302                                                0);
2303        if (!gfs2_delete_workqueue) {
2304                destroy_workqueue(glock_workqueue);
2305                rhashtable_destroy(&gl_hash_table);
2306                return -ENOMEM;
2307        }
2308
2309        ret = register_shrinker(&glock_shrinker);
2310        if (ret) {
2311                destroy_workqueue(gfs2_delete_workqueue);
2312                destroy_workqueue(glock_workqueue);
2313                rhashtable_destroy(&gl_hash_table);
2314                return ret;
2315        }
2316
2317        for (i = 0; i < GLOCK_WAIT_TABLE_SIZE; i++)
2318                init_waitqueue_head(glock_wait_table + i);
2319
2320        return 0;
2321}
2322
2323void gfs2_glock_exit(void)
2324{
2325        unregister_shrinker(&glock_shrinker);
2326        rhashtable_destroy(&gl_hash_table);
2327        destroy_workqueue(glock_workqueue);
2328        destroy_workqueue(gfs2_delete_workqueue);
2329}
2330
2331static void gfs2_glock_iter_next(struct gfs2_glock_iter *gi, loff_t n)
2332{
2333        struct gfs2_glock *gl = gi->gl;
2334
2335        if (gl) {
2336                if (n == 0)
2337                        return;
2338                if (!lockref_put_not_zero(&gl->gl_lockref))
2339                        gfs2_glock_queue_put(gl);
2340        }
2341        for (;;) {
2342                gl = rhashtable_walk_next(&gi->hti);
2343                if (IS_ERR_OR_NULL(gl)) {
2344                        if (gl == ERR_PTR(-EAGAIN)) {
2345                                n = 1;
2346                                continue;
2347                        }
2348                        gl = NULL;
2349                        break;
2350                }
2351                if (gl->gl_name.ln_sbd != gi->sdp)
2352                        continue;
2353                if (n <= 1) {
2354                        if (!lockref_get_not_dead(&gl->gl_lockref))
2355                                continue;
2356                        break;
2357                } else {
2358                        if (__lockref_is_dead(&gl->gl_lockref))
2359                                continue;
2360                        n--;
2361                }
2362        }
2363        gi->gl = gl;
2364}
2365
2366static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
2367        __acquires(RCU)
2368{
2369        struct gfs2_glock_iter *gi = seq->private;
2370        loff_t n;
2371
2372        /*
2373         * We can either stay where we are, skip to the next hash table
2374         * entry, or start from the beginning.
2375         */
2376        if (*pos < gi->last_pos) {
2377                rhashtable_walk_exit(&gi->hti);
2378                rhashtable_walk_enter(&gl_hash_table, &gi->hti);
2379                n = *pos + 1;
2380        } else {
2381                n = *pos - gi->last_pos;
2382        }
2383
2384        rhashtable_walk_start(&gi->hti);
2385
2386        gfs2_glock_iter_next(gi, n);
2387        gi->last_pos = *pos;
2388        return gi->gl;
2389}
2390
2391static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
2392                                 loff_t *pos)
2393{
2394        struct gfs2_glock_iter *gi = seq->private;
2395
2396        (*pos)++;
2397        gi->last_pos = *pos;
2398        gfs2_glock_iter_next(gi, 1);
2399        return gi->gl;
2400}
2401
2402static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
2403        __releases(RCU)
2404{
2405        struct gfs2_glock_iter *gi = seq->private;
2406
2407        rhashtable_walk_stop(&gi->hti);
2408}
2409
2410static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
2411{
2412        dump_glock(seq, iter_ptr, false);
2413        return 0;
2414}
2415
2416static void *gfs2_sbstats_seq_start(struct seq_file *seq, loff_t *pos)
2417{
2418        preempt_disable();
2419        if (*pos >= GFS2_NR_SBSTATS)
2420                return NULL;
2421        return pos;
2422}
2423
2424static void *gfs2_sbstats_seq_next(struct seq_file *seq, void *iter_ptr,
2425                                   loff_t *pos)
2426{
2427        (*pos)++;
2428        if (*pos >= GFS2_NR_SBSTATS)
2429                return NULL;
2430        return pos;
2431}
2432
2433static void gfs2_sbstats_seq_stop(struct seq_file *seq, void *iter_ptr)
2434{
2435        preempt_enable();
2436}
2437
2438static const struct seq_operations gfs2_glock_seq_ops = {
2439        .start = gfs2_glock_seq_start,
2440        .next  = gfs2_glock_seq_next,
2441        .stop  = gfs2_glock_seq_stop,
2442        .show  = gfs2_glock_seq_show,
2443};
2444
2445static const struct seq_operations gfs2_glstats_seq_ops = {
2446        .start = gfs2_glock_seq_start,
2447        .next  = gfs2_glock_seq_next,
2448        .stop  = gfs2_glock_seq_stop,
2449        .show  = gfs2_glstats_seq_show,
2450};
2451
2452static const struct seq_operations gfs2_sbstats_sops = {
2453        .start = gfs2_sbstats_seq_start,
2454        .next  = gfs2_sbstats_seq_next,
2455        .stop  = gfs2_sbstats_seq_stop,
2456        .show  = gfs2_sbstats_seq_show,
2457};
2458
2459#define GFS2_SEQ_GOODSIZE min(PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER, 65536UL)
2460
2461static int __gfs2_glocks_open(struct inode *inode, struct file *file,
2462                              const struct seq_operations *ops)
2463{
2464        int ret = seq_open_private(file, ops, sizeof(struct gfs2_glock_iter));
2465        if (ret == 0) {
2466                struct seq_file *seq = file->private_data;
2467                struct gfs2_glock_iter *gi = seq->private;
2468
2469                gi->sdp = inode->i_private;
2470                seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
2471                if (seq->buf)
2472                        seq->size = GFS2_SEQ_GOODSIZE;
2473                /*
2474                 * Initially, we are "before" the first hash table entry; the
2475                 * first call to rhashtable_walk_next gets us the first entry.
2476                 */
2477                gi->last_pos = -1;
2478                gi->gl = NULL;
2479                rhashtable_walk_enter(&gl_hash_table, &gi->hti);
2480        }
2481        return ret;
2482}
2483
2484static int gfs2_glocks_open(struct inode *inode, struct file *file)
2485{
2486        return __gfs2_glocks_open(inode, file, &gfs2_glock_seq_ops);
2487}
2488
2489static int gfs2_glocks_release(struct inode *inode, struct file *file)
2490{
2491        struct seq_file *seq = file->private_data;
2492        struct gfs2_glock_iter *gi = seq->private;
2493
2494        if (gi->gl)
2495                gfs2_glock_put(gi->gl);
2496        rhashtable_walk_exit(&gi->hti);
2497        return seq_release_private(inode, file);
2498}
2499
2500static int gfs2_glstats_open(struct inode *inode, struct file *file)
2501{
2502        return __gfs2_glocks_open(inode, file, &gfs2_glstats_seq_ops);
2503}
2504
2505static const struct file_operations gfs2_glocks_fops = {
2506        .owner   = THIS_MODULE,
2507        .open    = gfs2_glocks_open,
2508        .read    = seq_read,
2509        .llseek  = seq_lseek,
2510        .release = gfs2_glocks_release,
2511};
2512
2513static const struct file_operations gfs2_glstats_fops = {
2514        .owner   = THIS_MODULE,
2515        .open    = gfs2_glstats_open,
2516        .read    = seq_read,
2517        .llseek  = seq_lseek,
2518        .release = gfs2_glocks_release,
2519};
2520
2521DEFINE_SEQ_ATTRIBUTE(gfs2_sbstats);
2522
2523void gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
2524{
2525        sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
2526
2527        debugfs_create_file("glocks", S_IFREG | S_IRUGO, sdp->debugfs_dir, sdp,
2528                            &gfs2_glocks_fops);
2529
2530        debugfs_create_file("glstats", S_IFREG | S_IRUGO, sdp->debugfs_dir, sdp,
2531                            &gfs2_glstats_fops);
2532
2533        debugfs_create_file("sbstats", S_IFREG | S_IRUGO, sdp->debugfs_dir, sdp,
2534                            &gfs2_sbstats_fops);
2535}
2536
2537void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
2538{
2539        debugfs_remove_recursive(sdp->debugfs_dir);
2540        sdp->debugfs_dir = NULL;
2541}
2542
2543void gfs2_register_debugfs(void)
2544{
2545        gfs2_root = debugfs_create_dir("gfs2", NULL);
2546}
2547
2548void gfs2_unregister_debugfs(void)
2549{
2550        debugfs_remove(gfs2_root);
2551        gfs2_root = NULL;
2552}
2553
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