fs/gfs2/glock.c

   1 /*
   2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   3  * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
   4  *
   5  * This copyrighted material is made available to anyone wishing to use,
   6  * modify, copy, or redistribute it subject to the terms and conditions
   7  * of the GNU General Public License version 2.
   8  */
   9
  10 #include <linux/sched.h>
  11 #include <linux/slab.h>
  12 #include <linux/spinlock.h>
  13 #include <linux/buffer_head.h>
  14 #include <linux/delay.h>
  15 #include <linux/sort.h>
  16 #include <linux/jhash.h>
  17 #include <linux/kallsyms.h>
  18 #include <linux/gfs2_ondisk.h>
  19 #include <linux/list.h>
  20 #include <linux/wait.h>
  21 #include <linux/module.h>
  22 #include <asm/uaccess.h>
  23 #include <linux/seq_file.h>
  24 #include <linux/debugfs.h>
  25 #include <linux/kthread.h>
  26 #include <linux/freezer.h>
  27 #include <linux/workqueue.h>
  28 #include <linux/jiffies.h>
  29 #include <linux/rcupdate.h>
  30 #include <linux/rculist_bl.h>
  31 #include <linux/bit_spinlock.h>
  32
  33 #include "gfs2.h"
  34 #include "incore.h"
  35 #include "glock.h"
  36 #include "glops.h"
  37 #include "inode.h"
  38 #include "lops.h"
  39 #include "meta_io.h"
  40 #include "quota.h"
  41 #include "super.h"
  42 #include "util.h"
  43 #include "bmap.h"
  44 #define CREATE_TRACE_POINTS
  45 #include "trace_gfs2.h"
  46
  47 struct gfs2_glock_iter {
  48         int hash;                       /* hash bucket index         */
  49         struct gfs2_sbd *sdp;           /* incore superblock         */
  50         struct gfs2_glock *gl;          /* current glock struct      */
  51         char string[512];               /* scratch space             */
  52 };
  53
  54 typedef void (*glock_examiner) (struct gfs2_glock * gl);
  55
  56 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl);
  57 #define GLOCK_BUG_ON(gl,x) do { if (unlikely(x)) { __dump_glock(NULL, gl); BUG(); } } while(0)
  58 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
  59
  60 static struct dentry *gfs2_root;
  61 static struct workqueue_struct *glock_workqueue;
  62 struct workqueue_struct *gfs2_delete_workqueue;
  63 static LIST_HEAD(lru_list);
  64 static atomic_t lru_count = ATOMIC_INIT(0);
  65 static DEFINE_SPINLOCK(lru_lock);
  66
  67 #define GFS2_GL_HASH_SHIFT      15
  68 #define GFS2_GL_HASH_SIZE       (1 << GFS2_GL_HASH_SHIFT)
  69 #define GFS2_GL_HASH_MASK       (GFS2_GL_HASH_SIZE - 1)
  70
  71 static struct hlist_bl_head gl_hash_table[GFS2_GL_HASH_SIZE];
  72 static struct dentry *gfs2_root;
  73
  74 /**
  75  * gl_hash() - Turn glock number into hash bucket number
  76  * @lock: The glock number
  77  *
  78  * Returns: The number of the corresponding hash bucket
  79  */
  80
  81 static unsigned int gl_hash(const struct gfs2_sbd *sdp,
  82                             const struct lm_lockname *name)
  83 {
  84         unsigned int h;
  85
  86         h = jhash(&name->ln_number, sizeof(u64), 0);
  87         h = jhash(&name->ln_type, sizeof(unsigned int), h);
  88         h = jhash(&sdp, sizeof(struct gfs2_sbd *), h);
  89         h &= GFS2_GL_HASH_MASK;
  90
  91         return h;
  92 }
  93
  94 static inline void spin_lock_bucket(unsigned int hash)
  95 {
  96         hlist_bl_lock(&gl_hash_table[hash]);
  97 }
  98
  99 static inline void spin_unlock_bucket(unsigned int hash)
 100 {
 101         hlist_bl_unlock(&gl_hash_table[hash]);
 102 }
 103
 104 static void gfs2_glock_dealloc(struct rcu_head *rcu)
 105 {
 106         struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu);
 107
 108         if (gl->gl_ops->go_flags & GLOF_ASPACE)
 109                 kmem_cache_free(gfs2_glock_aspace_cachep, gl);
 110         else
 111                 kmem_cache_free(gfs2_glock_cachep, gl);
 112 }
 113
 114 void gfs2_glock_free(struct gfs2_glock *gl)
 115 {
 116         struct gfs2_sbd *sdp = gl->gl_sbd;
 117
 118         call_rcu(&gl->gl_rcu, gfs2_glock_dealloc);
 119         if (atomic_dec_and_test(&sdp->sd_glock_disposal))
 120                 wake_up(&sdp->sd_glock_wait);
 121 }
 122
 123 /**
 124  * gfs2_glock_hold() - increment reference count on glock
 125  * @gl: The glock to hold
 126  *
 127  */
 128
 129 void gfs2_glock_hold(struct gfs2_glock *gl)
 130 {
 131         GLOCK_BUG_ON(gl, atomic_read(&gl->gl_ref) == 0);
 132         atomic_inc(&gl->gl_ref);
 133 }
 134
 135 /**
 136  * demote_ok - Check to see if it's ok to unlock a glock
 137  * @gl: the glock
 138  *
 139  * Returns: 1 if it's ok
 140  */
 141
 142 static int demote_ok(const struct gfs2_glock *gl)
 143 {
 144         const struct gfs2_glock_operations *glops = gl->gl_ops;
 145
 146         /* assert_spin_locked(&gl->gl_spin); */
 147
 148         if (gl->gl_state == LM_ST_UNLOCKED)
 149                 return 0;
 150         if (test_bit(GLF_LFLUSH, &gl->gl_flags))
 151                 return 0;
 152         if ((gl->gl_name.ln_type != LM_TYPE_INODE) &&
 153             !list_empty(&gl->gl_holders))
 154                 return 0;
 155         if (glops->go_demote_ok)
 156                 return glops->go_demote_ok(gl);
 157         return 1;
 158 }
 159
 160
 161 /**
 162  * __gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
 163  * @gl: the glock
 164  *
 165  * If the glock is demotable, then we add it (or move it) to the end
 166  * of the glock LRU list.
 167  */
 168
 169 static void __gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
 170 {
 171         if (demote_ok(gl)) {
 172                 spin_lock(&lru_lock);
 173
 174                 if (!list_empty(&gl->gl_lru))
 175                         list_del_init(&gl->gl_lru);
 176                 else
 177                         atomic_inc(&lru_count);
 178
 179                 list_add_tail(&gl->gl_lru, &lru_list);
 180                 spin_unlock(&lru_lock);
 181         }
 182 }
 183
 184 void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
 185 {
 186         spin_lock(&gl->gl_spin);
 187         __gfs2_glock_schedule_for_reclaim(gl);
 188         spin_unlock(&gl->gl_spin);
 189 }
 190
 191 /**
 192  * gfs2_glock_put_nolock() - Decrement reference count on glock
 193  * @gl: The glock to put
 194  *
 195  * This function should only be used if the caller has its own reference
 196  * to the glock, in addition to the one it is dropping.
 197  */
 198
 199 void gfs2_glock_put_nolock(struct gfs2_glock *gl)
 200 {
 201         if (atomic_dec_and_test(&gl->gl_ref))
 202                 GLOCK_BUG_ON(gl, 1);
 203 }
 204
 205 /**
 206  * gfs2_glock_put() - Decrement reference count on glock
 207  * @gl: The glock to put
 208  *
 209  */
 210
 211 void gfs2_glock_put(struct gfs2_glock *gl)
 212 {
 213         struct gfs2_sbd *sdp = gl->gl_sbd;
 214         struct address_space *mapping = gfs2_glock2aspace(gl);
 215
 216         if (atomic_dec_and_test(&gl->gl_ref)) {
 217                 spin_lock_bucket(gl->gl_hash);
 218                 hlist_bl_del_rcu(&gl->gl_list);
 219                 spin_unlock_bucket(gl->gl_hash);
 220                 spin_lock(&lru_lock);
 221                 if (!list_empty(&gl->gl_lru)) {
 222                         list_del_init(&gl->gl_lru);
 223                         atomic_dec(&lru_count);
 224                 }
 225                 spin_unlock(&lru_lock);
 226                 GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
 227                 GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
 228                 trace_gfs2_glock_put(gl);
 229                 sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
 230         }
 231 }
 232
 233 /**
 234  * search_bucket() - Find struct gfs2_glock by lock number
 235  * @bucket: the bucket to search
 236  * @name: The lock name
 237  *
 238  * Returns: NULL, or the struct gfs2_glock with the requested number
 239  */
 240
 241 static struct gfs2_glock *search_bucket(unsigned int hash,
 242                                         const struct gfs2_sbd *sdp,
 243                                         const struct lm_lockname *name)
 244 {
 245         struct gfs2_glock *gl;
 246         struct hlist_bl_node *h;
 247
 248         hlist_bl_for_each_entry_rcu(gl, h, &gl_hash_table[hash], gl_list) {
 249                 if (!lm_name_equal(&gl->gl_name, name))
 250                         continue;
 251                 if (gl->gl_sbd != sdp)
 252                         continue;
 253                 if (atomic_inc_not_zero(&gl->gl_ref))
 254                         return gl;
 255         }
 256
 257         return NULL;
 258 }
 259
 260 /**
 261  * may_grant - check if its ok to grant a new lock
 262  * @gl: The glock
 263  * @gh: The lock request which we wish to grant
 264  *
 265  * Returns: true if its ok to grant the lock
 266  */
 267
 268 static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
 269 {
 270         const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
 271         if ((gh->gh_state == LM_ST_EXCLUSIVE ||
 272              gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
 273                 return 0;
 274         if (gl->gl_state == gh->gh_state)
 275                 return 1;
 276         if (gh->gh_flags & GL_EXACT)
 277                 return 0;
 278         if (gl->gl_state == LM_ST_EXCLUSIVE) {
 279                 if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
 280                         return 1;
 281                 if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
 282                         return 1;
 283         }
 284         if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
 285                 return 1;
 286         return 0;
 287 }
 288
 289 static void gfs2_holder_wake(struct gfs2_holder *gh)
 290 {
 291         clear_bit(HIF_WAIT, &gh->gh_iflags);
 292         smp_mb__after_clear_bit();
 293         wake_up_bit(&gh->gh_iflags, HIF_WAIT);
 294 }
 295
 296 /**
 297  * do_error - Something unexpected has happened during a lock request
 298  *
 299  */
 300
 301 static inline void do_error(struct gfs2_glock *gl, const int ret)
 302 {
 303         struct gfs2_holder *gh, *tmp;
 304
 305         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 306                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 307                         continue;
 308                 if (ret & LM_OUT_ERROR)
 309                         gh->gh_error = -EIO;
 310                 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
 311                         gh->gh_error = GLR_TRYFAILED;
 312                 else
 313                         continue;
 314                 list_del_init(&gh->gh_list);
 315                 trace_gfs2_glock_queue(gh, 0);
 316                 gfs2_holder_wake(gh);
 317         }
 318 }
 319
 320 /**
 321  * do_promote - promote as many requests as possible on the current queue
 322  * @gl: The glock
 323  *
 324  * Returns: 1 if there is a blocked holder at the head of the list, or 2
 325  *          if a type specific operation is underway.
 326  */
 327
 328 static int do_promote(struct gfs2_glock *gl)
 329 __releases(&gl->gl_spin)
 330 __acquires(&gl->gl_spin)
 331 {
 332         const struct gfs2_glock_operations *glops = gl->gl_ops;
 333         struct gfs2_holder *gh, *tmp;
 334         int ret;
 335
 336 restart:
 337         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 338                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 339                         continue;
 340                 if (may_grant(gl, gh)) {
 341                         if (gh->gh_list.prev == &gl->gl_holders &&
 342                             glops->go_lock) {
 343                                 spin_unlock(&gl->gl_spin);
 344                                 /* FIXME: eliminate this eventually */
 345                                 ret = glops->go_lock(gh);
 346                                 spin_lock(&gl->gl_spin);
 347                                 if (ret) {
 348                                         if (ret == 1)
 349                                                 return 2;
 350                                         gh->gh_error = ret;
 351                                         list_del_init(&gh->gh_list);
 352                                         trace_gfs2_glock_queue(gh, 0);
 353                                         gfs2_holder_wake(gh);
 354                                         goto restart;
 355                                 }
 356                                 set_bit(HIF_HOLDER, &gh->gh_iflags);
 357                                 trace_gfs2_promote(gh, 1);
 358                                 gfs2_holder_wake(gh);
 359                                 goto restart;
 360                         }
 361                         set_bit(HIF_HOLDER, &gh->gh_iflags);
 362                         trace_gfs2_promote(gh, 0);
 363                         gfs2_holder_wake(gh);
 364                         continue;
 365                 }
 366                 if (gh->gh_list.prev == &gl->gl_holders)
 367                         return 1;
 368                 do_error(gl, 0);
 369                 break;
 370         }
 371         return 0;
 372 }
 373
 374 /**
 375  * find_first_waiter - find the first gh that's waiting for the glock
 376  * @gl: the glock
 377  */
 378
 379 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
 380 {
 381         struct gfs2_holder *gh;
 382
 383         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
 384                 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
 385                         return gh;
 386         }
 387         return NULL;
 388 }
 389
 390 /**
 391  * state_change - record that the glock is now in a different state
 392  * @gl: the glock
 393  * @new_state the new state
 394  *
 395  */
 396
 397 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 398 {
 399         int held1, held2;
 400
 401         held1 = (gl->gl_state != LM_ST_UNLOCKED);
 402         held2 = (new_state != LM_ST_UNLOCKED);
 403
 404         if (held1 != held2) {
 405                 if (held2)
 406                         gfs2_glock_hold(gl);
 407                 else
 408                         gfs2_glock_put_nolock(gl);
 409         }
 410         if (held1 && held2 && list_empty(&gl->gl_holders))
 411                 clear_bit(GLF_QUEUED, &gl->gl_flags);
 412
 413         gl->gl_state = new_state;
 414         gl->gl_tchange = jiffies;
 415 }
 416
 417 static void gfs2_demote_wake(struct gfs2_glock *gl)
 418 {
 419         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 420         clear_bit(GLF_DEMOTE, &gl->gl_flags);
 421         smp_mb__after_clear_bit();
 422         wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
 423 }
 424
 425 /**
 426  * finish_xmote - The DLM has replied to one of our lock requests
 427  * @gl: The glock
 428  * @ret: The status from the DLM
 429  *
 430  */
 431
 432 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
 433 {
 434         const struct gfs2_glock_operations *glops = gl->gl_ops;
 435         struct gfs2_holder *gh;
 436         unsigned state = ret & LM_OUT_ST_MASK;
 437         int rv;
 438
 439         spin_lock(&gl->gl_spin);
 440         trace_gfs2_glock_state_change(gl, state);
 441         state_change(gl, state);
 442         gh = find_first_waiter(gl);
 443
 444         /* Demote to UN request arrived during demote to SH or DF */
 445         if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
 446             state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
 447                 gl->gl_target = LM_ST_UNLOCKED;
 448
 449         /* Check for state != intended state */
 450         if (unlikely(state != gl->gl_target)) {
 451                 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
 452                         /* move to back of queue and try next entry */
 453                         if (ret & LM_OUT_CANCELED) {
 454                                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
 455                                         list_move_tail(&gh->gh_list, &gl->gl_holders);
 456                                 gh = find_first_waiter(gl);
 457                                 gl->gl_target = gh->gh_state;
 458                                 goto retry;
 459                         }
 460                         /* Some error or failed "try lock" - report it */
 461                         if ((ret & LM_OUT_ERROR) ||
 462                             (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 463                                 gl->gl_target = gl->gl_state;
 464                                 do_error(gl, ret);
 465                                 goto out;
 466                         }
 467                 }
 468                 switch(state) {
 469                 /* Unlocked due to conversion deadlock, try again */
 470                 case LM_ST_UNLOCKED:
 471 retry:
 472                         do_xmote(gl, gh, gl->gl_target);
 473                         break;
 474                 /* Conversion fails, unlock and try again */
 475                 case LM_ST_SHARED:
 476                 case LM_ST_DEFERRED:
 477                         do_xmote(gl, gh, LM_ST_UNLOCKED);
 478                         break;
 479                 default: /* Everything else */
 480                         printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
 481                         GLOCK_BUG_ON(gl, 1);
 482                 }
 483                 spin_unlock(&gl->gl_spin);
 484                 return;
 485         }
 486
 487         /* Fast path - we got what we asked for */
 488         if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
 489                 gfs2_demote_wake(gl);
 490         if (state != LM_ST_UNLOCKED) {
 491                 if (glops->go_xmote_bh) {
 492                         spin_unlock(&gl->gl_spin);
 493                         rv = glops->go_xmote_bh(gl, gh);
 494                         spin_lock(&gl->gl_spin);
 495                         if (rv) {
 496                                 do_error(gl, rv);
 497                                 goto out;
 498                         }
 499                 }
 500                 rv = do_promote(gl);
 501                 if (rv == 2)
 502                         goto out_locked;
 503         }
 504 out:
 505         clear_bit(GLF_LOCK, &gl->gl_flags);
 506 out_locked:
 507         spin_unlock(&gl->gl_spin);
 508 }
 509
 510 /**
 511  * do_xmote - Calls the DLM to change the state of a lock
 512  * @gl: The lock state
 513  * @gh: The holder (only for promotes)
 514  * @target: The target lock state
 515  *
 516  */
 517
 518 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
 519 __releases(&gl->gl_spin)
 520 __acquires(&gl->gl_spin)
 521 {
 522         const struct gfs2_glock_operations *glops = gl->gl_ops;
 523         struct gfs2_sbd *sdp = gl->gl_sbd;
 524         unsigned int lck_flags = gh ? gh->gh_flags : 0;
 525         int ret;
 526
 527         lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
 528                       LM_FLAG_PRIORITY);
 529         GLOCK_BUG_ON(gl, gl->gl_state == target);
 530         GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
 531         if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
 532             glops->go_inval) {
 533                 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 534                 do_error(gl, 0); /* Fail queued try locks */
 535         }
 536         gl->gl_req = target;
 537         spin_unlock(&gl->gl_spin);
 538         if (glops->go_xmote_th)
 539                 glops->go_xmote_th(gl);
 540         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 541                 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
 542         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 543
 544         gfs2_glock_hold(gl);
 545         if (target != LM_ST_UNLOCKED && (gl->gl_state == LM_ST_SHARED ||
 546             gl->gl_state == LM_ST_DEFERRED) &&
 547             !(lck_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 548                 lck_flags |= LM_FLAG_TRY_1CB;
 549
 550         if (sdp->sd_lockstruct.ls_ops->lm_lock) {
 551                 /* lock_dlm */
 552                 ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
 553                 GLOCK_BUG_ON(gl, ret);
 554         } else { /* lock_nolock */
 555                 finish_xmote(gl, target);
 556                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 557                         gfs2_glock_put(gl);
 558         }
 559
 560         spin_lock(&gl->gl_spin);
 561 }
 562
 563 /**
 564  * find_first_holder - find the first "holder" gh
 565  * @gl: the glock
 566  */
 567
 568 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
 569 {
 570         struct gfs2_holder *gh;
 571
 572         if (!list_empty(&gl->gl_holders)) {
 573                 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 574                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 575                         return gh;
 576         }
 577         return NULL;
 578 }
 579
 580 /**
 581  * run_queue - do all outstanding tasks related to a glock
 582  * @gl: The glock in question
 583  * @nonblock: True if we must not block in run_queue
 584  *
 585  */
 586
 587 static void run_queue(struct gfs2_glock *gl, const int nonblock)
 588 __releases(&gl->gl_spin)
 589 __acquires(&gl->gl_spin)
 590 {
 591         struct gfs2_holder *gh = NULL;
 592         int ret;
 593
 594         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 595                 return;
 596
 597         GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
 598
 599         if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
 600             gl->gl_demote_state != gl->gl_state) {
 601                 if (find_first_holder(gl))
 602                         goto out_unlock;
 603                 if (nonblock)
 604                         goto out_sched;
 605                 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
 606                 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
 607                 gl->gl_target = gl->gl_demote_state;
 608         } else {
 609                 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
 610                         gfs2_demote_wake(gl);
 611                 ret = do_promote(gl);
 612                 if (ret == 0)
 613                         goto out_unlock;
 614                 if (ret == 2)
 615                         goto out;
 616                 gh = find_first_waiter(gl);
 617                 gl->gl_target = gh->gh_state;
 618                 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 619                         do_error(gl, 0); /* Fail queued try locks */
 620         }
 621         do_xmote(gl, gh, gl->gl_target);
 622 out:
 623         return;
 624
 625 out_sched:
 626         clear_bit(GLF_LOCK, &gl->gl_flags);
 627         smp_mb__after_clear_bit();
 628         gfs2_glock_hold(gl);
 629         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 630                 gfs2_glock_put_nolock(gl);
 631         return;
 632
 633 out_unlock:
 634         clear_bit(GLF_LOCK, &gl->gl_flags);
 635         smp_mb__after_clear_bit();
 636         return;
 637 }
 638
 639 static void delete_work_func(struct work_struct *work)
 640 {
 641         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
 642         struct gfs2_sbd *sdp = gl->gl_sbd;
 643         struct gfs2_inode *ip;
 644         struct inode *inode;
 645         u64 no_addr = gl->gl_name.ln_number;
 646
 647         ip = gl->gl_object;
 648         /* Note: Unsafe to dereference ip as we don't hold right refs/locks */
 649
 650         if (ip)
 651                 inode = gfs2_ilookup(sdp->sd_vfs, no_addr);
 652         else
 653                 inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
 654         if (inode && !IS_ERR(inode)) {
 655                 d_prune_aliases(inode);
 656                 iput(inode);
 657         }
 658         gfs2_glock_put(gl);
 659 }
 660
 661 static void glock_work_func(struct work_struct *work)
 662 {
 663         unsigned long delay = 0;
 664         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
 665         int drop_ref = 0;
 666
 667         if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
 668                 finish_xmote(gl, gl->gl_reply);
 669                 drop_ref = 1;
 670         }
 671         spin_lock(&gl->gl_spin);
 672         if (test_and_clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
 673             gl->gl_state != LM_ST_UNLOCKED &&
 674             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
 675                 unsigned long holdtime, now = jiffies;
 676                 holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
 677                 if (time_before(now, holdtime))
 678                         delay = holdtime - now;
 679                 set_bit(delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE, &gl->gl_flags);
 680         }
 681         run_queue(gl, 0);
 682         spin_unlock(&gl->gl_spin);
 683         if (!delay ||
 684             queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
 685                 gfs2_glock_put(gl);
 686         if (drop_ref)
 687                 gfs2_glock_put(gl);
 688 }
 689
 690 /**
 691  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
 692  * @sdp: The GFS2 superblock
 693  * @number: the lock number
 694  * @glops: The glock_operations to use
 695  * @create: If 0, don't create the glock if it doesn't exist
 696  * @glp: the glock is returned here
 697  *
 698  * This does not lock a glock, just finds/creates structures for one.
 699  *
 700  * Returns: errno
 701  */
 702
 703 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 704                    const struct gfs2_glock_operations *glops, int create,
 705                    struct gfs2_glock **glp)
 706 {
 707         struct super_block *s = sdp->sd_vfs;
 708         struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
 709         struct gfs2_glock *gl, *tmp;
 710         unsigned int hash = gl_hash(sdp, &name);
 711         struct address_space *mapping;
 712         struct kmem_cache *cachep;
 713
 714         rcu_read_lock();
 715         gl = search_bucket(hash, sdp, &name);
 716         rcu_read_unlock();
 717
 718         *glp = gl;
 719         if (gl)
 720                 return 0;
 721         if (!create)
 722                 return -ENOENT;
 723
 724         if (glops->go_flags & GLOF_ASPACE)
 725                 cachep = gfs2_glock_aspace_cachep;
 726         else
 727                 cachep = gfs2_glock_cachep;
 728         gl = kmem_cache_alloc(cachep, GFP_KERNEL);
 729         if (!gl)
 730                 return -ENOMEM;
 731
 732         atomic_inc(&sdp->sd_glock_disposal);
 733         gl->gl_flags = 0;
 734         gl->gl_name = name;
 735         atomic_set(&gl->gl_ref, 1);
 736         gl->gl_state = LM_ST_UNLOCKED;
 737         gl->gl_target = LM_ST_UNLOCKED;
 738         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 739         gl->gl_hash = hash;
 740         gl->gl_ops = glops;
 741         snprintf(gl->gl_strname, GDLM_STRNAME_BYTES, "%8x%16llx", name.ln_type, (unsigned long long)number);
 742         memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
 743         gl->gl_lksb.sb_lvbptr = gl->gl_lvb;
 744         gl->gl_tchange = jiffies;
 745         gl->gl_object = NULL;
 746         gl->gl_sbd = sdp;
 747         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
 748         INIT_WORK(&gl->gl_delete, delete_work_func);
 749
 750         mapping = gfs2_glock2aspace(gl);
 751         if (mapping) {
 752                 mapping->a_ops = &gfs2_meta_aops;
 753                 mapping->host = s->s_bdev->bd_inode;
 754                 mapping->flags = 0;
 755                 mapping_set_gfp_mask(mapping, GFP_NOFS);
 756                 mapping->assoc_mapping = NULL;
 757                 mapping->backing_dev_info = s->s_bdi;
 758                 mapping->writeback_index = 0;
 759         }
 760
 761         spin_lock_bucket(hash);
 762         tmp = search_bucket(hash, sdp, &name);
 763         if (tmp) {
 764                 spin_unlock_bucket(hash);
 765                 kmem_cache_free(cachep, gl);
 766                 atomic_dec(&sdp->sd_glock_disposal);
 767                 gl = tmp;
 768         } else {
 769                 hlist_bl_add_head_rcu(&gl->gl_list, &gl_hash_table[hash]);
 770                 spin_unlock_bucket(hash);
 771         }
 772
 773         *glp = gl;
 774
 775         return 0;
 776 }
 777
 778 /**
 779  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
 780  * @gl: the glock
 781  * @state: the state we're requesting
 782  * @flags: the modifier flags
 783  * @gh: the holder structure
 784  *
 785  */
 786
 787 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
 788                       struct gfs2_holder *gh)
 789 {
 790         INIT_LIST_HEAD(&gh->gh_list);
 791         gh->gh_gl = gl;
 792         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 793         gh->gh_owner_pid = get_pid(task_pid(current));
 794         gh->gh_state = state;
 795         gh->gh_flags = flags;
 796         gh->gh_error = 0;
 797         gh->gh_iflags = 0;
 798         gfs2_glock_hold(gl);
 799 }
 800
 801 /**
 802  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
 803  * @state: the state we're requesting
 804  * @flags: the modifier flags
 805  * @gh: the holder structure
 806  *
 807  * Don't mess with the glock.
 808  *
 809  */
 810
 811 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
 812 {
 813         gh->gh_state = state;
 814         gh->gh_flags = flags;
 815         gh->gh_iflags = 0;
 816         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 817         if (gh->gh_owner_pid)
 818                 put_pid(gh->gh_owner_pid);
 819         gh->gh_owner_pid = get_pid(task_pid(current));
 820 }
 821
 822 /**
 823  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 824  * @gh: the holder structure
 825  *
 826  */
 827
 828 void gfs2_holder_uninit(struct gfs2_holder *gh)
 829 {
 830         put_pid(gh->gh_owner_pid);
 831         gfs2_glock_put(gh->gh_gl);
 832         gh->gh_gl = NULL;
 833         gh->gh_ip = 0;
 834 }
 835
 836 /**
 837  * gfs2_glock_holder_wait
 838  * @word: unused
 839  *
 840  * This function and gfs2_glock_demote_wait both show up in the WCHAN
 841  * field. Thus I've separated these otherwise identical functions in
 842  * order to be more informative to the user.
 843  */
 844
 845 static int gfs2_glock_holder_wait(void *word)
 846 {
 847         schedule();
 848         return 0;
 849 }
 850
 851 static int gfs2_glock_demote_wait(void *word)
 852 {
 853         schedule();
 854         return 0;
 855 }
 856
 857 static void wait_on_holder(struct gfs2_holder *gh)
 858 {
 859         might_sleep();
 860         wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
 861 }
 862
 863 static void wait_on_demote(struct gfs2_glock *gl)
 864 {
 865         might_sleep();
 866         wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
 867 }
 868
 869 /**
 870  * handle_callback - process a demote request
 871  * @gl: the glock
 872  * @state: the state the caller wants us to change to
 873  *
 874  * There are only two requests that we are going to see in actual
 875  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
 876  */
 877
 878 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
 879                             unsigned long delay)
 880 {
 881         int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
 882
 883         set_bit(bit, &gl->gl_flags);
 884         if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
 885                 gl->gl_demote_state = state;
 886                 gl->gl_demote_time = jiffies;
 887         } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
 888                         gl->gl_demote_state != state) {
 889                 gl->gl_demote_state = LM_ST_UNLOCKED;
 890         }
 891         if (gl->gl_ops->go_callback)
 892                 gl->gl_ops->go_callback(gl);
 893         trace_gfs2_demote_rq(gl);
 894 }
 895
 896 /**
 897  * gfs2_glock_wait - wait on a glock acquisition
 898  * @gh: the glock holder
 899  *
 900  * Returns: 0 on success
 901  */
 902
 903 int gfs2_glock_wait(struct gfs2_holder *gh)
 904 {
 905         wait_on_holder(gh);
 906         return gh->gh_error;
 907 }
 908
 909 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
 910 {
 911         struct va_format vaf;
 912         va_list args;
 913
 914         va_start(args, fmt);
 915
 916         if (seq) {
 917                 struct gfs2_glock_iter *gi = seq->private;
 918                 vsprintf(gi->string, fmt, args);
 919                 seq_printf(seq, gi->string);
 920         } else {
 921                 vaf.fmt = fmt;
 922                 vaf.va = &args;
 923
 924                 printk(KERN_ERR " %pV", &vaf);
 925         }
 926
 927         va_end(args);
 928 }
 929
 930 /**
 931  * add_to_queue - Add a holder to the wait queue (but look for recursion)
 932  * @gh: the holder structure to add
 933  *
 934  * Eventually we should move the recursive locking trap to a
 935  * debugging option or something like that. This is the fast
 936  * path and needs to have the minimum number of distractions.
 937  *
 938  */
 939
 940 static inline void add_to_queue(struct gfs2_holder *gh)
 941 __releases(&gl->gl_spin)
 942 __acquires(&gl->gl_spin)
 943 {
 944         struct gfs2_glock *gl = gh->gh_gl;
 945         struct gfs2_sbd *sdp = gl->gl_sbd;
 946         struct list_head *insert_pt = NULL;
 947         struct gfs2_holder *gh2;
 948         int try_lock = 0;
 949
 950         BUG_ON(gh->gh_owner_pid == NULL);
 951         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
 952                 BUG();
 953
 954         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
 955                 if (test_bit(GLF_LOCK, &gl->gl_flags))
 956                         try_lock = 1;
 957                 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 958                         goto fail;
 959         }
 960
 961         list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
 962                 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
 963                     (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
 964                         goto trap_recursive;
 965                 if (try_lock &&
 966                     !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
 967                     !may_grant(gl, gh)) {
 968 fail:
 969                         gh->gh_error = GLR_TRYFAILED;
 970                         gfs2_holder_wake(gh);
 971                         return;
 972                 }
 973                 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
 974                         continue;
 975                 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
 976                         insert_pt = &gh2->gh_list;
 977         }
 978         set_bit(GLF_QUEUED, &gl->gl_flags);
 979         trace_gfs2_glock_queue(gh, 1);
 980         if (likely(insert_pt == NULL)) {
 981                 list_add_tail(&gh->gh_list, &gl->gl_holders);
 982                 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
 983                         goto do_cancel;
 984                 return;
 985         }
 986         list_add_tail(&gh->gh_list, insert_pt);
 987 do_cancel:
 988         gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 989         if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
 990                 spin_unlock(&gl->gl_spin);
 991                 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
 992                         sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
 993                 spin_lock(&gl->gl_spin);
 994         }
 995         return;
 996
 997 trap_recursive:
 998         print_symbol(KERN_ERR "original: %s\n", gh2->gh_ip);
 999         printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
1000         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1001                gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
1002         print_symbol(KERN_ERR "new: %s\n", gh->gh_ip);
1003         printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
1004         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1005                gh->gh_gl->gl_name.ln_type, gh->gh_state);
1006         __dump_glock(NULL, gl);
1007         BUG();
1008 }
1009
1010 /**
1011  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1012  * @gh: the holder structure
1013  *
1014  * if (gh->gh_flags & GL_ASYNC), this never returns an error
1015  *
1016  * Returns: 0, GLR_TRYFAILED, or errno on failure
1017  */
1018
1019 int gfs2_glock_nq(struct gfs2_holder *gh)
1020 {
1021         struct gfs2_glock *gl = gh->gh_gl;
1022         struct gfs2_sbd *sdp = gl->gl_sbd;
1023         int error = 0;
1024
1025         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
1026                 return -EIO;
1027
1028         spin_lock(&gl->gl_spin);
1029         add_to_queue(gh);
1030         if ((LM_FLAG_NOEXP & gh->gh_flags) &&
1031             test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1032                 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1033         run_queue(gl, 1);
1034         spin_unlock(&gl->gl_spin);
1035
1036         if (!(gh->gh_flags & GL_ASYNC))
1037                 error = gfs2_glock_wait(gh);
1038
1039         return error;
1040 }
1041
1042 /**
1043  * gfs2_glock_poll - poll to see if an async request has been completed
1044  * @gh: the holder
1045  *
1046  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1047  */
1048
1049 int gfs2_glock_poll(struct gfs2_holder *gh)
1050 {
1051         return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1052 }
1053
1054 /**
1055  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1056  * @gh: the glock holder
1057  *
1058  */
1059
1060 void gfs2_glock_dq(struct gfs2_holder *gh)
1061 {
1062         struct gfs2_glock *gl = gh->gh_gl;
1063         const struct gfs2_glock_operations *glops = gl->gl_ops;
1064         unsigned delay = 0;
1065         int fast_path = 0;
1066
1067         spin_lock(&gl->gl_spin);
1068         if (gh->gh_flags & GL_NOCACHE)
1069                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1070
1071         list_del_init(&gh->gh_list);
1072         if (find_first_holder(gl) == NULL) {
1073                 if (glops->go_unlock) {
1074                         GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1075                         spin_unlock(&gl->gl_spin);
1076                         glops->go_unlock(gh);
1077                         spin_lock(&gl->gl_spin);
1078                         clear_bit(GLF_LOCK, &gl->gl_flags);
1079                 }
1080                 if (list_empty(&gl->gl_holders) &&
1081                     !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1082                     !test_bit(GLF_DEMOTE, &gl->gl_flags))
1083                         fast_path = 1;
1084         }
1085         __gfs2_glock_schedule_for_reclaim(gl);
1086         trace_gfs2_glock_queue(gh, 0);
1087         spin_unlock(&gl->gl_spin);
1088         if (likely(fast_path))
1089                 return;
1090
1091         gfs2_glock_hold(gl);
1092         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1093             !test_bit(GLF_DEMOTE, &gl->gl_flags))
1094                 delay = gl->gl_ops->go_min_hold_time;
1095         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1096                 gfs2_glock_put(gl);
1097 }
1098
1099 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1100 {
1101         struct gfs2_glock *gl = gh->gh_gl;
1102         gfs2_glock_dq(gh);
1103         wait_on_demote(gl);
1104 }
1105
1106 /**
1107  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1108  * @gh: the holder structure
1109  *
1110  */
1111
1112 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1113 {
1114         gfs2_glock_dq(gh);
1115         gfs2_holder_uninit(gh);
1116 }
1117
1118 /**
1119  * gfs2_glock_nq_num - acquire a glock based on lock number
1120  * @sdp: the filesystem
1121  * @number: the lock number
1122  * @glops: the glock operations for the type of glock
1123  * @state: the state to acquire the glock in
1124  * @flags: modifier flags for the acquisition
1125  * @gh: the struct gfs2_holder
1126  *
1127  * Returns: errno
1128  */
1129
1130 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1131                       const struct gfs2_glock_operations *glops,
1132                       unsigned int state, int flags, struct gfs2_holder *gh)
1133 {
1134         struct gfs2_glock *gl;
1135         int error;
1136
1137         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1138         if (!error) {
1139                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1140                 gfs2_glock_put(gl);
1141         }
1142
1143         return error;
1144 }
1145
1146 /**
1147  * glock_compare - Compare two struct gfs2_glock structures for sorting
1148  * @arg_a: the first structure
1149  * @arg_b: the second structure
1150  *
1151  */
1152
1153 static int glock_compare(const void *arg_a, const void *arg_b)
1154 {
1155         const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1156         const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1157         const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1158         const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1159
1160         if (a->ln_number > b->ln_number)
1161                 return 1;
1162         if (a->ln_number < b->ln_number)
1163                 return -1;
1164         BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1165         return 0;
1166 }
1167
1168 /**
1169  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1170  * @num_gh: the number of structures
1171  * @ghs: an array of struct gfs2_holder structures
1172  *
1173  * Returns: 0 on success (all glocks acquired),
1174  *          errno on failure (no glocks acquired)
1175  */
1176
1177 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1178                      struct gfs2_holder **p)
1179 {
1180         unsigned int x;
1181         int error = 0;
1182
1183         for (x = 0; x < num_gh; x++)
1184                 p[x] = &ghs[x];
1185
1186         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1187
1188         for (x = 0; x < num_gh; x++) {
1189                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1190
1191                 error = gfs2_glock_nq(p[x]);
1192                 if (error) {
1193                         while (x--)
1194                                 gfs2_glock_dq(p[x]);
1195                         break;
1196                 }
1197         }
1198
1199         return error;
1200 }
1201
1202 /**
1203  * gfs2_glock_nq_m - acquire multiple glocks
1204  * @num_gh: the number of structures
1205  * @ghs: an array of struct gfs2_holder structures
1206  *
1207  *
1208  * Returns: 0 on success (all glocks acquired),
1209  *          errno on failure (no glocks acquired)
1210  */
1211
1212 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1213 {
1214         struct gfs2_holder *tmp[4];
1215         struct gfs2_holder **pph = tmp;
1216         int error = 0;
1217
1218         switch(num_gh) {
1219         case 0:
1220                 return 0;
1221         case 1:
1222                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1223                 return gfs2_glock_nq(ghs);
1224         default:
1225                 if (num_gh <= 4)
1226                         break;
1227                 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1228                 if (!pph)
1229                         return -ENOMEM;
1230         }
1231
1232         error = nq_m_sync(num_gh, ghs, pph);
1233
1234         if (pph != tmp)
1235                 kfree(pph);
1236
1237         return error;
1238 }
1239
1240 /**
1241  * gfs2_glock_dq_m - release multiple glocks
1242  * @num_gh: the number of structures
1243  * @ghs: an array of struct gfs2_holder structures
1244  *
1245  */
1246
1247 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1248 {
1249         while (num_gh--)
1250                 gfs2_glock_dq(&ghs[num_gh]);
1251 }
1252
1253 /**
1254  * gfs2_glock_dq_uninit_m - release multiple glocks
1255  * @num_gh: the number of structures
1256  * @ghs: an array of struct gfs2_holder structures
1257  *
1258  */
1259
1260 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1261 {
1262         while (num_gh--)
1263                 gfs2_glock_dq_uninit(&ghs[num_gh]);
1264 }
1265
1266 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1267 {
1268         unsigned long delay = 0;
1269         unsigned long holdtime;
1270         unsigned long now = jiffies;
1271
1272         gfs2_glock_hold(gl);
1273         holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
1274         if (test_bit(GLF_QUEUED, &gl->gl_flags)) {
1275                 if (time_before(now, holdtime))
1276                         delay = holdtime - now;
1277                 if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1278                         delay = gl->gl_ops->go_min_hold_time;
1279         }
1280
1281         spin_lock(&gl->gl_spin);
1282         handle_callback(gl, state, delay);
1283         spin_unlock(&gl->gl_spin);
1284         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1285                 gfs2_glock_put(gl);
1286 }
1287
1288 /**
1289  * gfs2_should_freeze - Figure out if glock should be frozen
1290  * @gl: The glock in question
1291  *
1292  * Glocks are not frozen if (a) the result of the dlm operation is
1293  * an error, (b) the locking operation was an unlock operation or
1294  * (c) if there is a "noexp" flagged request anywhere in the queue
1295  *
1296  * Returns: 1 if freezing should occur, 0 otherwise
1297  */
1298
1299 static int gfs2_should_freeze(const struct gfs2_glock *gl)
1300 {
1301         const struct gfs2_holder *gh;
1302
1303         if (gl->gl_reply & ~LM_OUT_ST_MASK)
1304                 return 0;
1305         if (gl->gl_target == LM_ST_UNLOCKED)
1306                 return 0;
1307
1308         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1309                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1310                         continue;
1311                 if (LM_FLAG_NOEXP & gh->gh_flags)
1312                         return 0;
1313         }
1314
1315         return 1;
1316 }
1317
1318 /**
1319  * gfs2_glock_complete - Callback used by locking
1320  * @gl: Pointer to the glock
1321  * @ret: The return value from the dlm
1322  *
1323  * The gl_reply field is under the gl_spin lock so that it is ok
1324  * to use a bitfield shared with other glock state fields.
1325  */
1326
1327 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1328 {
1329         struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
1330
1331         spin_lock(&gl->gl_spin);
1332         gl->gl_reply = ret;
1333
1334         if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_flags))) {
1335                 if (gfs2_should_freeze(gl)) {
1336                         set_bit(GLF_FROZEN, &gl->gl_flags);
1337                         spin_unlock(&gl->gl_spin);
1338                         return;
1339                 }
1340         }
1341
1342         spin_unlock(&gl->gl_spin);
1343         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1344         smp_wmb();
1345         gfs2_glock_hold(gl);
1346         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1347                 gfs2_glock_put(gl);
1348 }
1349
1350
1351 static int gfs2_shrink_glock_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask)
1352 {
1353         struct gfs2_glock *gl;
1354         int may_demote;
1355         int nr_skipped = 0;
1356         LIST_HEAD(skipped);
1357
1358         if (nr == 0)
1359                 goto out;
1360
1361         if (!(gfp_mask & __GFP_FS))
1362                 return -1;
1363
1364         spin_lock(&lru_lock);
1365         while(nr && !list_empty(&lru_list)) {
1366                 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1367                 list_del_init(&gl->gl_lru);
1368                 atomic_dec(&lru_count);
1369
1370                 /* Test for being demotable */
1371                 if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1372                         gfs2_glock_hold(gl);
1373                         spin_unlock(&lru_lock);
1374                         spin_lock(&gl->gl_spin);
1375                         may_demote = demote_ok(gl);
1376                         if (may_demote) {
1377                                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1378                                 nr--;
1379                         }
1380                         clear_bit(GLF_LOCK, &gl->gl_flags);
1381                         smp_mb__after_clear_bit();
1382                         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1383                                 gfs2_glock_put_nolock(gl);
1384                         spin_unlock(&gl->gl_spin);
1385                         spin_lock(&lru_lock);
1386                         continue;
1387                 }
1388                 nr_skipped++;
1389                 list_add(&gl->gl_lru, &skipped);
1390         }
1391         list_splice(&skipped, &lru_list);
1392         atomic_add(nr_skipped, &lru_count);
1393         spin_unlock(&lru_lock);
1394 out:
1395         return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
1396 }
1397
1398 static struct shrinker glock_shrinker = {
1399         .shrink = gfs2_shrink_glock_memory,
1400         .seeks = DEFAULT_SEEKS,
1401 };
1402
1403 /**
1404  * examine_bucket - Call a function for glock in a hash bucket
1405  * @examiner: the function
1406  * @sdp: the filesystem
1407  * @bucket: the bucket
1408  *
1409  */
1410
1411 static void examine_bucket(glock_examiner examiner, const struct gfs2_sbd *sdp,
1412                           unsigned int hash)
1413 {
1414         struct gfs2_glock *gl;
1415         struct hlist_bl_head *head = &gl_hash_table[hash];
1416         struct hlist_bl_node *pos;
1417
1418         rcu_read_lock();
1419         hlist_bl_for_each_entry_rcu(gl, pos, head, gl_list) {
1420                 if ((gl->gl_sbd == sdp) && atomic_read(&gl->gl_ref))
1421                         examiner(gl);
1422         }
1423         rcu_read_unlock();
1424         cond_resched();
1425 }
1426
1427 static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
1428 {
1429         unsigned x;
1430
1431         for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1432                 examine_bucket(examiner, sdp, x);
1433 }
1434
1435
1436 /**
1437  * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1438  * @gl: The glock to thaw
1439  *
1440  * N.B. When we freeze a glock, we leave a ref to the glock outstanding,
1441  * so this has to result in the ref count being dropped by one.
1442  */
1443
1444 static void thaw_glock(struct gfs2_glock *gl)
1445 {
1446         if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1447                 return;
1448         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1449         gfs2_glock_hold(gl);
1450         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1451                 gfs2_glock_put(gl);
1452 }
1453
1454 /**
1455  * clear_glock - look at a glock and see if we can free it from glock cache
1456  * @gl: the glock to look at
1457  *
1458  */
1459
1460 static void clear_glock(struct gfs2_glock *gl)
1461 {
1462         spin_lock(&lru_lock);
1463         if (!list_empty(&gl->gl_lru)) {
1464                 list_del_init(&gl->gl_lru);
1465                 atomic_dec(&lru_count);
1466         }
1467         spin_unlock(&lru_lock);
1468
1469         spin_lock(&gl->gl_spin);
1470         if (gl->gl_state != LM_ST_UNLOCKED)
1471                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1472         spin_unlock(&gl->gl_spin);
1473         gfs2_glock_hold(gl);
1474         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1475                 gfs2_glock_put(gl);
1476 }
1477
1478 /**
1479  * gfs2_glock_thaw - Thaw any frozen glocks
1480  * @sdp: The super block
1481  *
1482  */
1483
1484 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1485 {
1486         glock_hash_walk(thaw_glock, sdp);
1487 }
1488
1489 static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1490 {
1491         int ret;
1492         spin_lock(&gl->gl_spin);
1493         ret = __dump_glock(seq, gl);
1494         spin_unlock(&gl->gl_spin);
1495         return ret;
1496 }
1497
1498 static void dump_glock_func(struct gfs2_glock *gl)
1499 {
1500         dump_glock(NULL, gl);
1501 }
1502
1503 /**
1504  * gfs2_gl_hash_clear - Empty out the glock hash table
1505  * @sdp: the filesystem
1506  * @wait: wait until it's all gone
1507  *
1508  * Called when unmounting the filesystem.
1509  */
1510
1511 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1512 {
1513         glock_hash_walk(clear_glock, sdp);
1514         flush_workqueue(glock_workqueue);
1515         wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
1516         glock_hash_walk(dump_glock_func, sdp);
1517 }
1518
1519 void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1520 {
1521         struct gfs2_glock *gl = ip->i_gl;
1522         int ret;
1523
1524         ret = gfs2_truncatei_resume(ip);
1525         gfs2_assert_withdraw(gl->gl_sbd, ret == 0);
1526
1527         spin_lock(&gl->gl_spin);
1528         clear_bit(GLF_LOCK, &gl->gl_flags);
1529         run_queue(gl, 1);
1530         spin_unlock(&gl->gl_spin);
1531 }
1532
1533 static const char *state2str(unsigned state)
1534 {
1535         switch(state) {
1536         case LM_ST_UNLOCKED:
1537                 return "UN";
1538         case LM_ST_SHARED:
1539                 return "SH";
1540         case LM_ST_DEFERRED:
1541                 return "DF";
1542         case LM_ST_EXCLUSIVE:
1543                 return "EX";
1544         }
1545         return "??";
1546 }
1547
1548 static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags)
1549 {
1550         char *p = buf;
1551         if (flags & LM_FLAG_TRY)
1552                 *p++ = 't';
1553         if (flags & LM_FLAG_TRY_1CB)
1554                 *p++ = 'T';
1555         if (flags & LM_FLAG_NOEXP)
1556                 *p++ = 'e';
1557         if (flags & LM_FLAG_ANY)
1558                 *p++ = 'A';
1559         if (flags & LM_FLAG_PRIORITY)
1560                 *p++ = 'p';
1561         if (flags & GL_ASYNC)
1562                 *p++ = 'a';
1563         if (flags & GL_EXACT)
1564                 *p++ = 'E';
1565         if (flags & GL_NOCACHE)
1566                 *p++ = 'c';
1567         if (test_bit(HIF_HOLDER, &iflags))
1568                 *p++ = 'H';
1569         if (test_bit(HIF_WAIT, &iflags))
1570                 *p++ = 'W';
1571         if (test_bit(HIF_FIRST, &iflags))
1572                 *p++ = 'F';
1573         *p = 0;
1574         return buf;
1575 }
1576
1577 /**
1578  * dump_holder - print information about a glock holder
1579  * @seq: the seq_file struct
1580  * @gh: the glock holder
1581  *
1582  * Returns: 0 on success, -ENOBUFS when we run out of space
1583  */
1584
1585 static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1586 {
1587         struct task_struct *gh_owner = NULL;
1588         char flags_buf[32];
1589
1590         if (gh->gh_owner_pid)
1591                 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1592         gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
1593                        state2str(gh->gh_state),
1594                        hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1595                        gh->gh_error,
1596                        gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1597                        gh_owner ? gh_owner->comm : "(ended)",
1598                        (void *)gh->gh_ip);
1599         return 0;
1600 }
1601
1602 static const char *gflags2str(char *buf, const unsigned long *gflags)
1603 {
1604         char *p = buf;
1605         if (test_bit(GLF_LOCK, gflags))
1606                 *p++ = 'l';
1607         if (test_bit(GLF_DEMOTE, gflags))
1608                 *p++ = 'D';
1609         if (test_bit(GLF_PENDING_DEMOTE, gflags))
1610                 *p++ = 'd';
1611         if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1612                 *p++ = 'p';
1613         if (test_bit(GLF_DIRTY, gflags))
1614                 *p++ = 'y';
1615         if (test_bit(GLF_LFLUSH, gflags))
1616                 *p++ = 'f';
1617         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1618                 *p++ = 'i';
1619         if (test_bit(GLF_REPLY_PENDING, gflags))
1620                 *p++ = 'r';
1621         if (test_bit(GLF_INITIAL, gflags))
1622                 *p++ = 'I';
1623         if (test_bit(GLF_FROZEN, gflags))
1624                 *p++ = 'F';
1625         if (test_bit(GLF_QUEUED, gflags))
1626                 *p++ = 'q';
1627         *p = 0;
1628         return buf;
1629 }
1630
1631 /**
1632  * __dump_glock - print information about a glock
1633  * @seq: The seq_file struct
1634  * @gl: the glock
1635  *
1636  * The file format is as follows:
1637  * One line per object, capital letters are used to indicate objects
1638  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1639  * other objects are indented by a single space and follow the glock to
1640  * which they are related. Fields are indicated by lower case letters
1641  * followed by a colon and the field value, except for strings which are in
1642  * [] so that its possible to see if they are composed of spaces for
1643  * example. The field's are n = number (id of the object), f = flags,
1644  * t = type, s = state, r = refcount, e = error, p = pid.
1645  *
1646  * Returns: 0 on success, -ENOBUFS when we run out of space
1647  */
1648
1649 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1650 {
1651         const struct gfs2_glock_operations *glops = gl->gl_ops;
1652         unsigned long long dtime;
1653         const struct gfs2_holder *gh;
1654         char gflags_buf[32];
1655         int error = 0;
1656
1657         dtime = jiffies - gl->gl_demote_time;
1658         dtime *= 1000000/HZ; /* demote time in uSec */
1659         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1660                 dtime = 0;
1661         gfs2_print_dbg(seq, "G:  s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d r:%d\n",
1662                   state2str(gl->gl_state),
1663                   gl->gl_name.ln_type,
1664                   (unsigned long long)gl->gl_name.ln_number,
1665                   gflags2str(gflags_buf, &gl->gl_flags),
1666                   state2str(gl->gl_target),
1667                   state2str(gl->gl_demote_state), dtime,
1668                   atomic_read(&gl->gl_ail_count),
1669                   atomic_read(&gl->gl_ref));
1670
1671         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1672                 error = dump_holder(seq, gh);
1673                 if (error)
1674                         goto out;
1675         }
1676         if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1677                 error = glops->go_dump(seq, gl);
1678 out:
1679         return error;
1680 }
1681
1682
1683
1684
1685 int __init gfs2_glock_init(void)
1686 {
1687         unsigned i;
1688         for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
1689                 INIT_HLIST_BL_HEAD(&gl_hash_table[i]);
1690         }
1691
1692         glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
1693                                           WQ_HIGHPRI | WQ_FREEZABLE, 0);
1694         if (IS_ERR(glock_workqueue))
1695                 return PTR_ERR(glock_workqueue);
1696         gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
1697                                                 WQ_MEM_RECLAIM | WQ_FREEZABLE,
1698                                                 0);
1699         if (IS_ERR(gfs2_delete_workqueue)) {
1700                 destroy_workqueue(glock_workqueue);
1701                 return PTR_ERR(gfs2_delete_workqueue);
1702         }
1703
1704         register_shrinker(&glock_shrinker);
1705
1706         return 0;
1707 }
1708
1709 void gfs2_glock_exit(void)
1710 {
1711         unregister_shrinker(&glock_shrinker);
1712         destroy_workqueue(glock_workqueue);
1713         destroy_workqueue(gfs2_delete_workqueue);
1714 }
1715
1716 static inline struct gfs2_glock *glock_hash_chain(unsigned hash)
1717 {
1718         return hlist_bl_entry(hlist_bl_first_rcu(&gl_hash_table[hash]),
1719                               struct gfs2_glock, gl_list);
1720 }
1721
1722 static inline struct gfs2_glock *glock_hash_next(struct gfs2_glock *gl)
1723 {
1724         return hlist_bl_entry(rcu_dereference(gl->gl_list.next),
1725                               struct gfs2_glock, gl_list);
1726 }
1727
1728 static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1729 {
1730         struct gfs2_glock *gl;
1731
1732         do {
1733                 gl = gi->gl;
1734                 if (gl) {
1735                         gi->gl = glock_hash_next(gl);
1736                 } else {
1737                         gi->gl = glock_hash_chain(gi->hash);
1738                 }
1739                 while (gi->gl == NULL) {
1740                         gi->hash++;
1741                         if (gi->hash >= GFS2_GL_HASH_SIZE) {
1742                                 rcu_read_unlock();
1743                                 return 1;
1744                         }
1745                         gi->gl = glock_hash_chain(gi->hash);
1746                 }
1747         /* Skip entries for other sb and dead entries */
1748         } while (gi->sdp != gi->gl->gl_sbd || atomic_read(&gi->gl->gl_ref) == 0);
1749
1750         return 0;
1751 }
1752
1753 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1754 {
1755         struct gfs2_glock_iter *gi = seq->private;
1756         loff_t n = *pos;
1757
1758         gi->hash = 0;
1759         rcu_read_lock();
1760
1761         do {
1762                 if (gfs2_glock_iter_next(gi))
1763                         return NULL;
1764         } while (n--);
1765
1766         return gi->gl;
1767 }
1768
1769 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1770                                  loff_t *pos)
1771 {
1772         struct gfs2_glock_iter *gi = seq->private;
1773
1774         (*pos)++;
1775
1776         if (gfs2_glock_iter_next(gi))
1777                 return NULL;
1778
1779         return gi->gl;
1780 }
1781
1782 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1783 {
1784         struct gfs2_glock_iter *gi = seq->private;
1785
1786         if (gi->gl)
1787                 rcu_read_unlock();
1788         gi->gl = NULL;
1789 }
1790
1791 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1792 {
1793         return dump_glock(seq, iter_ptr);
1794 }
1795
1796 static const struct seq_operations gfs2_glock_seq_ops = {
1797         .start = gfs2_glock_seq_start,
1798         .next  = gfs2_glock_seq_next,
1799         .stop  = gfs2_glock_seq_stop,
1800         .show  = gfs2_glock_seq_show,
1801 };
1802
1803 static int gfs2_debugfs_open(struct inode *inode, struct file *file)
1804 {
1805         int ret = seq_open_private(file, &gfs2_glock_seq_ops,
1806                                    sizeof(struct gfs2_glock_iter));
1807         if (ret == 0) {
1808                 struct seq_file *seq = file->private_data;
1809                 struct gfs2_glock_iter *gi = seq->private;
1810                 gi->sdp = inode->i_private;
1811         }
1812         return ret;
1813 }
1814
1815 static const struct file_operations gfs2_debug_fops = {
1816         .owner   = THIS_MODULE,
1817         .open    = gfs2_debugfs_open,
1818         .read    = seq_read,
1819         .llseek  = seq_lseek,
1820         .release = seq_release_private,
1821 };
1822
1823 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
1824 {
1825         sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
1826         if (!sdp->debugfs_dir)
1827                 return -ENOMEM;
1828         sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
1829                                                          S_IFREG | S_IRUGO,
1830                                                          sdp->debugfs_dir, sdp,
1831                                                          &gfs2_debug_fops);
1832         if (!sdp->debugfs_dentry_glocks)
1833                 return -ENOMEM;
1834
1835         return 0;
1836 }
1837
1838 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
1839 {
1840         if (sdp && sdp->debugfs_dir) {
1841                 if (sdp->debugfs_dentry_glocks) {
1842                         debugfs_remove(sdp->debugfs_dentry_glocks);
1843                         sdp->debugfs_dentry_glocks = NULL;
1844                 }
1845                 debugfs_remove(sdp->debugfs_dir);
1846                 sdp->debugfs_dir = NULL;
1847         }
1848 }
1849
1850 int gfs2_register_debugfs(void)
1851 {
1852         gfs2_root = debugfs_create_dir("gfs2", NULL);
1853         return gfs2_root ? 0 : -ENOMEM;
1854 }
1855
1856 void gfs2_unregister_debugfs(void)
1857 {
1858         debugfs_remove(gfs2_root);
1859         gfs2_root = NULL;
1860 }