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         if (gl->gl_state == LM_ST_UNLOCKED)
 147                 return 0;
 148         if (!list_empty(&gl->gl_holders))
 149                 return 0;
 150         if (glops->go_demote_ok)
 151                 return glops->go_demote_ok(gl);
 152         return 1;
 153 }
 154
 155
 156 void gfs2_glock_add_to_lru(struct gfs2_glock *gl)
 157 {
 158         spin_lock(&lru_lock);
 159
 160         if (!list_empty(&gl->gl_lru))
 161                 list_del_init(&gl->gl_lru);
 162         else
 163                 atomic_inc(&lru_count);
 164
 165         list_add_tail(&gl->gl_lru, &lru_list);
 166         set_bit(GLF_LRU, &gl->gl_flags);
 167         spin_unlock(&lru_lock);
 168 }
 169
 170 static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
 171 {
 172         spin_lock(&lru_lock);
 173         if (!list_empty(&gl->gl_lru)) {
 174                 list_del_init(&gl->gl_lru);
 175                 atomic_dec(&lru_count);
 176                 clear_bit(GLF_LRU, &gl->gl_flags);
 177         }
 178         spin_unlock(&lru_lock);
 179 }
 180
 181 /**
 182  * __gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
 183  * @gl: the glock
 184  *
 185  * If the glock is demotable, then we add it (or move it) to the end
 186  * of the glock LRU list.
 187  */
 188
 189 static void __gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
 190 {
 191         if (demote_ok(gl))
 192                 gfs2_glock_add_to_lru(gl);
 193 }
 194
 195 /**
 196  * gfs2_glock_put_nolock() - Decrement reference count on glock
 197  * @gl: The glock to put
 198  *
 199  * This function should only be used if the caller has its own reference
 200  * to the glock, in addition to the one it is dropping.
 201  */
 202
 203 void gfs2_glock_put_nolock(struct gfs2_glock *gl)
 204 {
 205         if (atomic_dec_and_test(&gl->gl_ref))
 206                 GLOCK_BUG_ON(gl, 1);
 207 }
 208
 209 /**
 210  * gfs2_glock_put() - Decrement reference count on glock
 211  * @gl: The glock to put
 212  *
 213  */
 214
 215 void gfs2_glock_put(struct gfs2_glock *gl)
 216 {
 217         struct gfs2_sbd *sdp = gl->gl_sbd;
 218         struct address_space *mapping = gfs2_glock2aspace(gl);
 219
 220         if (atomic_dec_and_test(&gl->gl_ref)) {
 221                 spin_lock_bucket(gl->gl_hash);
 222                 hlist_bl_del_rcu(&gl->gl_list);
 223                 spin_unlock_bucket(gl->gl_hash);
 224                 gfs2_glock_remove_from_lru(gl);
 225                 GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
 226                 GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
 227                 trace_gfs2_glock_put(gl);
 228                 sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
 229         }
 230 }
 231
 232 /**
 233  * search_bucket() - Find struct gfs2_glock by lock number
 234  * @bucket: the bucket to search
 235  * @name: The lock name
 236  *
 237  * Returns: NULL, or the struct gfs2_glock with the requested number
 238  */
 239
 240 static struct gfs2_glock *search_bucket(unsigned int hash,
 241                                         const struct gfs2_sbd *sdp,
 242                                         const struct lm_lockname *name)
 243 {
 244         struct gfs2_glock *gl;
 245         struct hlist_bl_node *h;
 246
 247         hlist_bl_for_each_entry_rcu(gl, h, &gl_hash_table[hash], gl_list) {
 248                 if (!lm_name_equal(&gl->gl_name, name))
 249                         continue;
 250                 if (gl->gl_sbd != sdp)
 251                         continue;
 252                 if (atomic_inc_not_zero(&gl->gl_ref))
 253                         return gl;
 254         }
 255
 256         return NULL;
 257 }
 258
 259 /**
 260  * may_grant - check if its ok to grant a new lock
 261  * @gl: The glock
 262  * @gh: The lock request which we wish to grant
 263  *
 264  * Returns: true if its ok to grant the lock
 265  */
 266
 267 static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
 268 {
 269         const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
 270         if ((gh->gh_state == LM_ST_EXCLUSIVE ||
 271              gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
 272                 return 0;
 273         if (gl->gl_state == gh->gh_state)
 274                 return 1;
 275         if (gh->gh_flags & GL_EXACT)
 276                 return 0;
 277         if (gl->gl_state == LM_ST_EXCLUSIVE) {
 278                 if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
 279                         return 1;
 280                 if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
 281                         return 1;
 282         }
 283         if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
 284                 return 1;
 285         return 0;
 286 }
 287
 288 static void gfs2_holder_wake(struct gfs2_holder *gh)
 289 {
 290         clear_bit(HIF_WAIT, &gh->gh_iflags);
 291         smp_mb__after_clear_bit();
 292         wake_up_bit(&gh->gh_iflags, HIF_WAIT);
 293 }
 294
 295 /**
 296  * do_error - Something unexpected has happened during a lock request
 297  *
 298  */
 299
 300 static inline void do_error(struct gfs2_glock *gl, const int ret)
 301 {
 302         struct gfs2_holder *gh, *tmp;
 303
 304         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 305                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 306                         continue;
 307                 if (ret & LM_OUT_ERROR)
 308                         gh->gh_error = -EIO;
 309                 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
 310                         gh->gh_error = GLR_TRYFAILED;
 311                 else
 312                         continue;
 313                 list_del_init(&gh->gh_list);
 314                 trace_gfs2_glock_queue(gh, 0);
 315                 gfs2_holder_wake(gh);
 316         }
 317 }
 318
 319 /**
 320  * do_promote - promote as many requests as possible on the current queue
 321  * @gl: The glock
 322  *
 323  * Returns: 1 if there is a blocked holder at the head of the list, or 2
 324  *          if a type specific operation is underway.
 325  */
 326
 327 static int do_promote(struct gfs2_glock *gl)
 328 __releases(&gl->gl_spin)
 329 __acquires(&gl->gl_spin)
 330 {
 331         const struct gfs2_glock_operations *glops = gl->gl_ops;
 332         struct gfs2_holder *gh, *tmp;
 333         int ret;
 334
 335 restart:
 336         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 337                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 338                         continue;
 339                 if (may_grant(gl, gh)) {
 340                         if (gh->gh_list.prev == &gl->gl_holders &&
 341                             glops->go_lock) {
 342                                 spin_unlock(&gl->gl_spin);
 343                                 /* FIXME: eliminate this eventually */
 344                                 ret = glops->go_lock(gh);
 345                                 spin_lock(&gl->gl_spin);
 346                                 if (ret) {
 347                                         if (ret == 1)
 348                                                 return 2;
 349                                         gh->gh_error = ret;
 350                                         list_del_init(&gh->gh_list);
 351                                         trace_gfs2_glock_queue(gh, 0);
 352                                         gfs2_holder_wake(gh);
 353                                         goto restart;
 354                                 }
 355                                 set_bit(HIF_HOLDER, &gh->gh_iflags);
 356                                 trace_gfs2_promote(gh, 1);
 357                                 gfs2_holder_wake(gh);
 358                                 goto restart;
 359                         }
 360                         set_bit(HIF_HOLDER, &gh->gh_iflags);
 361                         trace_gfs2_promote(gh, 0);
 362                         gfs2_holder_wake(gh);
 363                         continue;
 364                 }
 365                 if (gh->gh_list.prev == &gl->gl_holders)
 366                         return 1;
 367                 do_error(gl, 0);
 368                 break;
 369         }
 370         return 0;
 371 }
 372
 373 /**
 374  * find_first_waiter - find the first gh that's waiting for the glock
 375  * @gl: the glock
 376  */
 377
 378 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
 379 {
 380         struct gfs2_holder *gh;
 381
 382         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
 383                 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
 384                         return gh;
 385         }
 386         return NULL;
 387 }
 388
 389 /**
 390  * state_change - record that the glock is now in a different state
 391  * @gl: the glock
 392  * @new_state the new state
 393  *
 394  */
 395
 396 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 397 {
 398         int held1, held2;
 399
 400         held1 = (gl->gl_state != LM_ST_UNLOCKED);
 401         held2 = (new_state != LM_ST_UNLOCKED);
 402
 403         if (held1 != held2) {
 404                 if (held2)
 405                         gfs2_glock_hold(gl);
 406                 else
 407                         gfs2_glock_put_nolock(gl);
 408         }
 409         if (held1 && held2 && list_empty(&gl->gl_holders))
 410                 clear_bit(GLF_QUEUED, &gl->gl_flags);
 411
 412         gl->gl_state = new_state;
 413         gl->gl_tchange = jiffies;
 414 }
 415
 416 static void gfs2_demote_wake(struct gfs2_glock *gl)
 417 {
 418         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 419         clear_bit(GLF_DEMOTE, &gl->gl_flags);
 420         smp_mb__after_clear_bit();
 421         wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
 422 }
 423
 424 /**
 425  * finish_xmote - The DLM has replied to one of our lock requests
 426  * @gl: The glock
 427  * @ret: The status from the DLM
 428  *
 429  */
 430
 431 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
 432 {
 433         const struct gfs2_glock_operations *glops = gl->gl_ops;
 434         struct gfs2_holder *gh;
 435         unsigned state = ret & LM_OUT_ST_MASK;
 436         int rv;
 437
 438         spin_lock(&gl->gl_spin);
 439         trace_gfs2_glock_state_change(gl, state);
 440         state_change(gl, state);
 441         gh = find_first_waiter(gl);
 442
 443         /* Demote to UN request arrived during demote to SH or DF */
 444         if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
 445             state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
 446                 gl->gl_target = LM_ST_UNLOCKED;
 447
 448         /* Check for state != intended state */
 449         if (unlikely(state != gl->gl_target)) {
 450                 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
 451                         /* move to back of queue and try next entry */
 452                         if (ret & LM_OUT_CANCELED) {
 453                                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
 454                                         list_move_tail(&gh->gh_list, &gl->gl_holders);
 455                                 gh = find_first_waiter(gl);
 456                                 gl->gl_target = gh->gh_state;
 457                                 goto retry;
 458                         }
 459                         /* Some error or failed "try lock" - report it */
 460                         if ((ret & LM_OUT_ERROR) ||
 461                             (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 462                                 gl->gl_target = gl->gl_state;
 463                                 do_error(gl, ret);
 464                                 goto out;
 465                         }
 466                 }
 467                 switch(state) {
 468                 /* Unlocked due to conversion deadlock, try again */
 469                 case LM_ST_UNLOCKED:
 470 retry:
 471                         do_xmote(gl, gh, gl->gl_target);
 472                         break;
 473                 /* Conversion fails, unlock and try again */
 474                 case LM_ST_SHARED:
 475                 case LM_ST_DEFERRED:
 476                         do_xmote(gl, gh, LM_ST_UNLOCKED);
 477                         break;
 478                 default: /* Everything else */
 479                         printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
 480                         GLOCK_BUG_ON(gl, 1);
 481                 }
 482                 spin_unlock(&gl->gl_spin);
 483                 return;
 484         }
 485
 486         /* Fast path - we got what we asked for */
 487         if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
 488                 gfs2_demote_wake(gl);
 489         if (state != LM_ST_UNLOCKED) {
 490                 if (glops->go_xmote_bh) {
 491                         spin_unlock(&gl->gl_spin);
 492                         rv = glops->go_xmote_bh(gl, gh);
 493                         spin_lock(&gl->gl_spin);
 494                         if (rv) {
 495                                 do_error(gl, rv);
 496                                 goto out;
 497                         }
 498                 }
 499                 rv = do_promote(gl);
 500                 if (rv == 2)
 501                         goto out_locked;
 502         }
 503 out:
 504         clear_bit(GLF_LOCK, &gl->gl_flags);
 505 out_locked:
 506         spin_unlock(&gl->gl_spin);
 507 }
 508
 509 /**
 510  * do_xmote - Calls the DLM to change the state of a lock
 511  * @gl: The lock state
 512  * @gh: The holder (only for promotes)
 513  * @target: The target lock state
 514  *
 515  */
 516
 517 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
 518 __releases(&gl->gl_spin)
 519 __acquires(&gl->gl_spin)
 520 {
 521         const struct gfs2_glock_operations *glops = gl->gl_ops;
 522         struct gfs2_sbd *sdp = gl->gl_sbd;
 523         unsigned int lck_flags = gh ? gh->gh_flags : 0;
 524         int ret;
 525
 526         lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
 527                       LM_FLAG_PRIORITY);
 528         GLOCK_BUG_ON(gl, gl->gl_state == target);
 529         GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
 530         if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
 531             glops->go_inval) {
 532                 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 533                 do_error(gl, 0); /* Fail queued try locks */
 534         }
 535         gl->gl_req = target;
 536         spin_unlock(&gl->gl_spin);
 537         if (glops->go_xmote_th)
 538                 glops->go_xmote_th(gl);
 539         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 540                 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
 541         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 542
 543         gfs2_glock_hold(gl);
 544         if (sdp->sd_lockstruct.ls_ops->lm_lock) {
 545                 /* lock_dlm */
 546                 ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
 547                 GLOCK_BUG_ON(gl, ret);
 548         } else { /* lock_nolock */
 549                 finish_xmote(gl, target);
 550                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 551                         gfs2_glock_put(gl);
 552         }
 553
 554         spin_lock(&gl->gl_spin);
 555 }
 556
 557 /**
 558  * find_first_holder - find the first "holder" gh
 559  * @gl: the glock
 560  */
 561
 562 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
 563 {
 564         struct gfs2_holder *gh;
 565
 566         if (!list_empty(&gl->gl_holders)) {
 567                 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 568                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 569                         return gh;
 570         }
 571         return NULL;
 572 }
 573
 574 /**
 575  * run_queue - do all outstanding tasks related to a glock
 576  * @gl: The glock in question
 577  * @nonblock: True if we must not block in run_queue
 578  *
 579  */
 580
 581 static void run_queue(struct gfs2_glock *gl, const int nonblock)
 582 __releases(&gl->gl_spin)
 583 __acquires(&gl->gl_spin)
 584 {
 585         struct gfs2_holder *gh = NULL;
 586         int ret;
 587
 588         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 589                 return;
 590
 591         GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
 592
 593         if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
 594             gl->gl_demote_state != gl->gl_state) {
 595                 if (find_first_holder(gl))
 596                         goto out_unlock;
 597                 if (nonblock)
 598                         goto out_sched;
 599                 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
 600                 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
 601                 gl->gl_target = gl->gl_demote_state;
 602         } else {
 603                 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
 604                         gfs2_demote_wake(gl);
 605                 ret = do_promote(gl);
 606                 if (ret == 0)
 607                         goto out_unlock;
 608                 if (ret == 2)
 609                         goto out;
 610                 gh = find_first_waiter(gl);
 611                 gl->gl_target = gh->gh_state;
 612                 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 613                         do_error(gl, 0); /* Fail queued try locks */
 614         }
 615         do_xmote(gl, gh, gl->gl_target);
 616 out:
 617         return;
 618
 619 out_sched:
 620         clear_bit(GLF_LOCK, &gl->gl_flags);
 621         smp_mb__after_clear_bit();
 622         gfs2_glock_hold(gl);
 623         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 624                 gfs2_glock_put_nolock(gl);
 625         return;
 626
 627 out_unlock:
 628         clear_bit(GLF_LOCK, &gl->gl_flags);
 629         smp_mb__after_clear_bit();
 630         return;
 631 }
 632
 633 static void delete_work_func(struct work_struct *work)
 634 {
 635         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
 636         struct gfs2_sbd *sdp = gl->gl_sbd;
 637         struct gfs2_inode *ip;
 638         struct inode *inode;
 639         u64 no_addr = gl->gl_name.ln_number;
 640
 641         ip = gl->gl_object;
 642         /* Note: Unsafe to dereference ip as we don't hold right refs/locks */
 643
 644         if (ip)
 645                 inode = gfs2_ilookup(sdp->sd_vfs, no_addr, 1);
 646         else
 647                 inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
 648         if (inode && !IS_ERR(inode)) {
 649                 d_prune_aliases(inode);
 650                 iput(inode);
 651         }
 652         gfs2_glock_put(gl);
 653 }
 654
 655 static void glock_work_func(struct work_struct *work)
 656 {
 657         unsigned long delay = 0;
 658         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
 659         int drop_ref = 0;
 660
 661         if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
 662                 finish_xmote(gl, gl->gl_reply);
 663                 drop_ref = 1;
 664         }
 665         spin_lock(&gl->gl_spin);
 666         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
 667             gl->gl_state != LM_ST_UNLOCKED &&
 668             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
 669                 unsigned long holdtime, now = jiffies;
 670
 671                 holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
 672                 if (time_before(now, holdtime))
 673                         delay = holdtime - now;
 674
 675                 if (!delay) {
 676                         clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
 677                         set_bit(GLF_DEMOTE, &gl->gl_flags);
 678                 }
 679         }
 680         run_queue(gl, 0);
 681         spin_unlock(&gl->gl_spin);
 682         if (!delay ||
 683             queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
 684                 gfs2_glock_put(gl);
 685         if (drop_ref)
 686                 gfs2_glock_put(gl);
 687 }
 688
 689 /**
 690  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
 691  * @sdp: The GFS2 superblock
 692  * @number: the lock number
 693  * @glops: The glock_operations to use
 694  * @create: If 0, don't create the glock if it doesn't exist
 695  * @glp: the glock is returned here
 696  *
 697  * This does not lock a glock, just finds/creates structures for one.
 698  *
 699  * Returns: errno
 700  */
 701
 702 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 703                    const struct gfs2_glock_operations *glops, int create,
 704                    struct gfs2_glock **glp)
 705 {
 706         struct super_block *s = sdp->sd_vfs;
 707         struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
 708         struct gfs2_glock *gl, *tmp;
 709         unsigned int hash = gl_hash(sdp, &name);
 710         struct address_space *mapping;
 711         struct kmem_cache *cachep;
 712
 713         rcu_read_lock();
 714         gl = search_bucket(hash, sdp, &name);
 715         rcu_read_unlock();
 716
 717         *glp = gl;
 718         if (gl)
 719                 return 0;
 720         if (!create)
 721                 return -ENOENT;
 722
 723         if (glops->go_flags & GLOF_ASPACE)
 724                 cachep = gfs2_glock_aspace_cachep;
 725         else
 726                 cachep = gfs2_glock_cachep;
 727         gl = kmem_cache_alloc(cachep, GFP_KERNEL);
 728         if (!gl)
 729                 return -ENOMEM;
 730
 731         atomic_inc(&sdp->sd_glock_disposal);
 732         gl->gl_flags = 0;
 733         gl->gl_name = name;
 734         atomic_set(&gl->gl_ref, 1);
 735         gl->gl_state = LM_ST_UNLOCKED;
 736         gl->gl_target = LM_ST_UNLOCKED;
 737         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 738         gl->gl_hash = hash;
 739         gl->gl_ops = glops;
 740         snprintf(gl->gl_strname, GDLM_STRNAME_BYTES, "%8x%16llx", name.ln_type, (unsigned long long)number);
 741         memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
 742         gl->gl_lksb.sb_lvbptr = gl->gl_lvb;
 743         gl->gl_tchange = jiffies;
 744         gl->gl_object = NULL;
 745         gl->gl_sbd = sdp;
 746         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
 747         INIT_WORK(&gl->gl_delete, delete_work_func);
 748
 749         mapping = gfs2_glock2aspace(gl);
 750         if (mapping) {
 751                 mapping->a_ops = &gfs2_meta_aops;
 752                 mapping->host = s->s_bdev->bd_inode;
 753                 mapping->flags = 0;
 754                 mapping_set_gfp_mask(mapping, GFP_NOFS);
 755                 mapping->assoc_mapping = NULL;
 756                 mapping->backing_dev_info = s->s_bdi;
 757                 mapping->writeback_index = 0;
 758         }
 759
 760         spin_lock_bucket(hash);
 761         tmp = search_bucket(hash, sdp, &name);
 762         if (tmp) {
 763                 spin_unlock_bucket(hash);
 764                 kmem_cache_free(cachep, gl);
 765                 atomic_dec(&sdp->sd_glock_disposal);
 766                 gl = tmp;
 767         } else {
 768                 hlist_bl_add_head_rcu(&gl->gl_list, &gl_hash_table[hash]);
 769                 spin_unlock_bucket(hash);
 770         }
 771
 772         *glp = gl;
 773
 774         return 0;
 775 }
 776
 777 /**
 778  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
 779  * @gl: the glock
 780  * @state: the state we're requesting
 781  * @flags: the modifier flags
 782  * @gh: the holder structure
 783  *
 784  */
 785
 786 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
 787                       struct gfs2_holder *gh)
 788 {
 789         INIT_LIST_HEAD(&gh->gh_list);
 790         gh->gh_gl = gl;
 791         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 792         gh->gh_owner_pid = get_pid(task_pid(current));
 793         gh->gh_state = state;
 794         gh->gh_flags = flags;
 795         gh->gh_error = 0;
 796         gh->gh_iflags = 0;
 797         gfs2_glock_hold(gl);
 798 }
 799
 800 /**
 801  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
 802  * @state: the state we're requesting
 803  * @flags: the modifier flags
 804  * @gh: the holder structure
 805  *
 806  * Don't mess with the glock.
 807  *
 808  */
 809
 810 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
 811 {
 812         gh->gh_state = state;
 813         gh->gh_flags = flags;
 814         gh->gh_iflags = 0;
 815         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 816         if (gh->gh_owner_pid)
 817                 put_pid(gh->gh_owner_pid);
 818         gh->gh_owner_pid = get_pid(task_pid(current));
 819 }
 820
 821 /**
 822  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 823  * @gh: the holder structure
 824  *
 825  */
 826
 827 void gfs2_holder_uninit(struct gfs2_holder *gh)
 828 {
 829         put_pid(gh->gh_owner_pid);
 830         gfs2_glock_put(gh->gh_gl);
 831         gh->gh_gl = NULL;
 832         gh->gh_ip = 0;
 833 }
 834
 835 /**
 836  * gfs2_glock_holder_wait
 837  * @word: unused
 838  *
 839  * This function and gfs2_glock_demote_wait both show up in the WCHAN
 840  * field. Thus I've separated these otherwise identical functions in
 841  * order to be more informative to the user.
 842  */
 843
 844 static int gfs2_glock_holder_wait(void *word)
 845 {
 846         schedule();
 847         return 0;
 848 }
 849
 850 static int gfs2_glock_demote_wait(void *word)
 851 {
 852         schedule();
 853         return 0;
 854 }
 855
 856 static void wait_on_holder(struct gfs2_holder *gh)
 857 {
 858         might_sleep();
 859         wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
 860 }
 861
 862 static void wait_on_demote(struct gfs2_glock *gl)
 863 {
 864         might_sleep();
 865         wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
 866 }
 867
 868 /**
 869  * handle_callback - process a demote request
 870  * @gl: the glock
 871  * @state: the state the caller wants us to change to
 872  *
 873  * There are only two requests that we are going to see in actual
 874  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
 875  */
 876
 877 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
 878                             unsigned long delay)
 879 {
 880         int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
 881
 882         set_bit(bit, &gl->gl_flags);
 883         if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
 884                 gl->gl_demote_state = state;
 885                 gl->gl_demote_time = jiffies;
 886         } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
 887                         gl->gl_demote_state != state) {
 888                 gl->gl_demote_state = LM_ST_UNLOCKED;
 889         }
 890         if (gl->gl_ops->go_callback)
 891                 gl->gl_ops->go_callback(gl);
 892         trace_gfs2_demote_rq(gl);
 893 }
 894
 895 /**
 896  * gfs2_glock_wait - wait on a glock acquisition
 897  * @gh: the glock holder
 898  *
 899  * Returns: 0 on success
 900  */
 901
 902 int gfs2_glock_wait(struct gfs2_holder *gh)
 903 {
 904         wait_on_holder(gh);
 905         return gh->gh_error;
 906 }
 907
 908 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
 909 {
 910         struct va_format vaf;
 911         va_list args;
 912
 913         va_start(args, fmt);
 914
 915         if (seq) {
 916                 struct gfs2_glock_iter *gi = seq->private;
 917                 vsprintf(gi->string, fmt, args);
 918                 seq_printf(seq, gi->string);
 919         } else {
 920                 vaf.fmt = fmt;
 921                 vaf.va = &args;
 922
 923                 printk(KERN_ERR " %pV", &vaf);
 924         }
 925
 926         va_end(args);
 927 }
 928
 929 /**
 930  * add_to_queue - Add a holder to the wait queue (but look for recursion)
 931  * @gh: the holder structure to add
 932  *
 933  * Eventually we should move the recursive locking trap to a
 934  * debugging option or something like that. This is the fast
 935  * path and needs to have the minimum number of distractions.
 936  *
 937  */
 938
 939 static inline void add_to_queue(struct gfs2_holder *gh)
 940 __releases(&gl->gl_spin)
 941 __acquires(&gl->gl_spin)
 942 {
 943         struct gfs2_glock *gl = gh->gh_gl;
 944         struct gfs2_sbd *sdp = gl->gl_sbd;
 945         struct list_head *insert_pt = NULL;
 946         struct gfs2_holder *gh2;
 947         int try_lock = 0;
 948
 949         BUG_ON(gh->gh_owner_pid == NULL);
 950         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
 951                 BUG();
 952
 953         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
 954                 if (test_bit(GLF_LOCK, &gl->gl_flags))
 955                         try_lock = 1;
 956                 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 957                         goto fail;
 958         }
 959
 960         list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
 961                 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
 962                     (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
 963                         goto trap_recursive;
 964                 if (try_lock &&
 965                     !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
 966                     !may_grant(gl, gh)) {
 967 fail:
 968                         gh->gh_error = GLR_TRYFAILED;
 969                         gfs2_holder_wake(gh);
 970                         return;
 971                 }
 972                 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
 973                         continue;
 974                 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
 975                         insert_pt = &gh2->gh_list;
 976         }
 977         set_bit(GLF_QUEUED, &gl->gl_flags);
 978         trace_gfs2_glock_queue(gh, 1);
 979         if (likely(insert_pt == NULL)) {
 980                 list_add_tail(&gh->gh_list, &gl->gl_holders);
 981                 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
 982                         goto do_cancel;
 983                 return;
 984         }
 985         list_add_tail(&gh->gh_list, insert_pt);
 986 do_cancel:
 987         gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 988         if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
 989                 spin_unlock(&gl->gl_spin);
 990                 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
 991                         sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
 992                 spin_lock(&gl->gl_spin);
 993         }
 994         return;
 995
 996 trap_recursive:
 997         print_symbol(KERN_ERR "original: %s\n", gh2->gh_ip);
 998         printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
 999         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1000                gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
1001         print_symbol(KERN_ERR "new: %s\n", gh->gh_ip);
1002         printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
1003         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1004                gh->gh_gl->gl_name.ln_type, gh->gh_state);
1005         __dump_glock(NULL, gl);
1006         BUG();
1007 }
1008
1009 /**
1010  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1011  * @gh: the holder structure
1012  *
1013  * if (gh->gh_flags & GL_ASYNC), this never returns an error
1014  *
1015  * Returns: 0, GLR_TRYFAILED, or errno on failure
1016  */
1017
1018 int gfs2_glock_nq(struct gfs2_holder *gh)
1019 {
1020         struct gfs2_glock *gl = gh->gh_gl;
1021         struct gfs2_sbd *sdp = gl->gl_sbd;
1022         int error = 0;
1023
1024         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
1025                 return -EIO;
1026
1027         if (test_bit(GLF_LRU, &gl->gl_flags))
1028                 gfs2_glock_remove_from_lru(gl);
1029
1030         spin_lock(&gl->gl_spin);
1031         add_to_queue(gh);
1032         if ((LM_FLAG_NOEXP & gh->gh_flags) &&
1033             test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1034                 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1035         run_queue(gl, 1);
1036         spin_unlock(&gl->gl_spin);
1037
1038         if (!(gh->gh_flags & GL_ASYNC))
1039                 error = gfs2_glock_wait(gh);
1040
1041         return error;
1042 }
1043
1044 /**
1045  * gfs2_glock_poll - poll to see if an async request has been completed
1046  * @gh: the holder
1047  *
1048  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1049  */
1050
1051 int gfs2_glock_poll(struct gfs2_holder *gh)
1052 {
1053         return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1054 }
1055
1056 /**
1057  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1058  * @gh: the glock holder
1059  *
1060  */
1061
1062 void gfs2_glock_dq(struct gfs2_holder *gh)
1063 {
1064         struct gfs2_glock *gl = gh->gh_gl;
1065         const struct gfs2_glock_operations *glops = gl->gl_ops;
1066         unsigned delay = 0;
1067         int fast_path = 0;
1068
1069         spin_lock(&gl->gl_spin);
1070         if (gh->gh_flags & GL_NOCACHE)
1071                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1072
1073         list_del_init(&gh->gh_list);
1074         if (find_first_holder(gl) == NULL) {
1075                 if (glops->go_unlock) {
1076                         GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1077                         spin_unlock(&gl->gl_spin);
1078                         glops->go_unlock(gh);
1079                         spin_lock(&gl->gl_spin);
1080                         clear_bit(GLF_LOCK, &gl->gl_flags);
1081                 }
1082                 if (list_empty(&gl->gl_holders) &&
1083                     !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1084                     !test_bit(GLF_DEMOTE, &gl->gl_flags))
1085                         fast_path = 1;
1086         }
1087         if (!test_bit(GLF_LFLUSH, &gl->gl_flags))
1088                 __gfs2_glock_schedule_for_reclaim(gl);
1089         trace_gfs2_glock_queue(gh, 0);
1090         spin_unlock(&gl->gl_spin);
1091         if (likely(fast_path))
1092                 return;
1093
1094         gfs2_glock_hold(gl);
1095         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1096             !test_bit(GLF_DEMOTE, &gl->gl_flags))
1097                 delay = gl->gl_ops->go_min_hold_time;
1098         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1099                 gfs2_glock_put(gl);
1100 }
1101
1102 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1103 {
1104         struct gfs2_glock *gl = gh->gh_gl;
1105         gfs2_glock_dq(gh);
1106         wait_on_demote(gl);
1107 }
1108
1109 /**
1110  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1111  * @gh: the holder structure
1112  *
1113  */
1114
1115 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1116 {
1117         gfs2_glock_dq(gh);
1118         gfs2_holder_uninit(gh);
1119 }
1120
1121 /**
1122  * gfs2_glock_nq_num - acquire a glock based on lock number
1123  * @sdp: the filesystem
1124  * @number: the lock number
1125  * @glops: the glock operations for the type of glock
1126  * @state: the state to acquire the glock in
1127  * @flags: modifier flags for the acquisition
1128  * @gh: the struct gfs2_holder
1129  *
1130  * Returns: errno
1131  */
1132
1133 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1134                       const struct gfs2_glock_operations *glops,
1135                       unsigned int state, int flags, struct gfs2_holder *gh)
1136 {
1137         struct gfs2_glock *gl;
1138         int error;
1139
1140         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1141         if (!error) {
1142                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1143                 gfs2_glock_put(gl);
1144         }
1145
1146         return error;
1147 }
1148
1149 /**
1150  * glock_compare - Compare two struct gfs2_glock structures for sorting
1151  * @arg_a: the first structure
1152  * @arg_b: the second structure
1153  *
1154  */
1155
1156 static int glock_compare(const void *arg_a, const void *arg_b)
1157 {
1158         const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1159         const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1160         const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1161         const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1162
1163         if (a->ln_number > b->ln_number)
1164                 return 1;
1165         if (a->ln_number < b->ln_number)
1166                 return -1;
1167         BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1168         return 0;
1169 }
1170
1171 /**
1172  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1173  * @num_gh: the number of structures
1174  * @ghs: an array of struct gfs2_holder structures
1175  *
1176  * Returns: 0 on success (all glocks acquired),
1177  *          errno on failure (no glocks acquired)
1178  */
1179
1180 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1181                      struct gfs2_holder **p)
1182 {
1183         unsigned int x;
1184         int error = 0;
1185
1186         for (x = 0; x < num_gh; x++)
1187                 p[x] = &ghs[x];
1188
1189         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1190
1191         for (x = 0; x < num_gh; x++) {
1192                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1193
1194                 error = gfs2_glock_nq(p[x]);
1195                 if (error) {
1196                         while (x--)
1197                                 gfs2_glock_dq(p[x]);
1198                         break;
1199                 }
1200         }
1201
1202         return error;
1203 }
1204
1205 /**
1206  * gfs2_glock_nq_m - acquire multiple glocks
1207  * @num_gh: the number of structures
1208  * @ghs: an array of struct gfs2_holder structures
1209  *
1210  *
1211  * Returns: 0 on success (all glocks acquired),
1212  *          errno on failure (no glocks acquired)
1213  */
1214
1215 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1216 {
1217         struct gfs2_holder *tmp[4];
1218         struct gfs2_holder **pph = tmp;
1219         int error = 0;
1220
1221         switch(num_gh) {
1222         case 0:
1223                 return 0;
1224         case 1:
1225                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1226                 return gfs2_glock_nq(ghs);
1227         default:
1228                 if (num_gh <= 4)
1229                         break;
1230                 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1231                 if (!pph)
1232                         return -ENOMEM;
1233         }
1234
1235         error = nq_m_sync(num_gh, ghs, pph);
1236
1237         if (pph != tmp)
1238                 kfree(pph);
1239
1240         return error;
1241 }
1242
1243 /**
1244  * gfs2_glock_dq_m - release multiple glocks
1245  * @num_gh: the number of structures
1246  * @ghs: an array of struct gfs2_holder structures
1247  *
1248  */
1249
1250 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1251 {
1252         while (num_gh--)
1253                 gfs2_glock_dq(&ghs[num_gh]);
1254 }
1255
1256 /**
1257  * gfs2_glock_dq_uninit_m - release multiple glocks
1258  * @num_gh: the number of structures
1259  * @ghs: an array of struct gfs2_holder structures
1260  *
1261  */
1262
1263 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1264 {
1265         while (num_gh--)
1266                 gfs2_glock_dq_uninit(&ghs[num_gh]);
1267 }
1268
1269 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1270 {
1271         unsigned long delay = 0;
1272         unsigned long holdtime;
1273         unsigned long now = jiffies;
1274
1275         gfs2_glock_hold(gl);
1276         holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
1277         if (test_bit(GLF_QUEUED, &gl->gl_flags)) {
1278                 if (time_before(now, holdtime))
1279                         delay = holdtime - now;
1280                 if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1281                         delay = gl->gl_ops->go_min_hold_time;
1282         }
1283
1284         spin_lock(&gl->gl_spin);
1285         handle_callback(gl, state, delay);
1286         spin_unlock(&gl->gl_spin);
1287         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1288                 gfs2_glock_put(gl);
1289 }
1290
1291 /**
1292  * gfs2_should_freeze - Figure out if glock should be frozen
1293  * @gl: The glock in question
1294  *
1295  * Glocks are not frozen if (a) the result of the dlm operation is
1296  * an error, (b) the locking operation was an unlock operation or
1297  * (c) if there is a "noexp" flagged request anywhere in the queue
1298  *
1299  * Returns: 1 if freezing should occur, 0 otherwise
1300  */
1301
1302 static int gfs2_should_freeze(const struct gfs2_glock *gl)
1303 {
1304         const struct gfs2_holder *gh;
1305
1306         if (gl->gl_reply & ~LM_OUT_ST_MASK)
1307                 return 0;
1308         if (gl->gl_target == LM_ST_UNLOCKED)
1309                 return 0;
1310
1311         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1312                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1313                         continue;
1314                 if (LM_FLAG_NOEXP & gh->gh_flags)
1315                         return 0;
1316         }
1317
1318         return 1;
1319 }
1320
1321 /**
1322  * gfs2_glock_complete - Callback used by locking
1323  * @gl: Pointer to the glock
1324  * @ret: The return value from the dlm
1325  *
1326  * The gl_reply field is under the gl_spin lock so that it is ok
1327  * to use a bitfield shared with other glock state fields.
1328  */
1329
1330 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1331 {
1332         struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
1333
1334         spin_lock(&gl->gl_spin);
1335         gl->gl_reply = ret;
1336
1337         if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_flags))) {
1338                 if (gfs2_should_freeze(gl)) {
1339                         set_bit(GLF_FROZEN, &gl->gl_flags);
1340                         spin_unlock(&gl->gl_spin);
1341                         return;
1342                 }
1343         }
1344
1345         spin_unlock(&gl->gl_spin);
1346         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1347         smp_wmb();
1348         gfs2_glock_hold(gl);
1349         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1350                 gfs2_glock_put(gl);
1351 }
1352
1353
1354 static int gfs2_shrink_glock_memory(struct shrinker *shrink,
1355                                     struct shrink_control *sc)
1356 {
1357         struct gfs2_glock *gl;
1358         int may_demote;
1359         int nr_skipped = 0;
1360         int nr = sc->nr_to_scan;
1361         gfp_t gfp_mask = sc->gfp_mask;
1362         LIST_HEAD(skipped);
1363
1364         if (nr == 0)
1365                 goto out;
1366
1367         if (!(gfp_mask & __GFP_FS))
1368                 return -1;
1369
1370         spin_lock(&lru_lock);
1371         while(nr && !list_empty(&lru_list)) {
1372                 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1373                 list_del_init(&gl->gl_lru);
1374                 clear_bit(GLF_LRU, &gl->gl_flags);
1375                 atomic_dec(&lru_count);
1376
1377                 /* Test for being demotable */
1378                 if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1379                         gfs2_glock_hold(gl);
1380                         spin_unlock(&lru_lock);
1381                         spin_lock(&gl->gl_spin);
1382                         may_demote = demote_ok(gl);
1383                         if (may_demote) {
1384                                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1385                                 nr--;
1386                         }
1387                         clear_bit(GLF_LOCK, &gl->gl_flags);
1388                         smp_mb__after_clear_bit();
1389                         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1390                                 gfs2_glock_put_nolock(gl);
1391                         spin_unlock(&gl->gl_spin);
1392                         spin_lock(&lru_lock);
1393                         continue;
1394                 }
1395                 nr_skipped++;
1396                 list_add(&gl->gl_lru, &skipped);
1397                 set_bit(GLF_LRU, &gl->gl_flags);
1398         }
1399         list_splice(&skipped, &lru_list);
1400         atomic_add(nr_skipped, &lru_count);
1401         spin_unlock(&lru_lock);
1402 out:
1403         return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
1404 }
1405
1406 static struct shrinker glock_shrinker = {
1407         .shrink = gfs2_shrink_glock_memory,
1408         .seeks = DEFAULT_SEEKS,
1409 };
1410
1411 /**
1412  * examine_bucket - Call a function for glock in a hash bucket
1413  * @examiner: the function
1414  * @sdp: the filesystem
1415  * @bucket: the bucket
1416  *
1417  */
1418
1419 static void examine_bucket(glock_examiner examiner, const struct gfs2_sbd *sdp,
1420                           unsigned int hash)
1421 {
1422         struct gfs2_glock *gl;
1423         struct hlist_bl_head *head = &gl_hash_table[hash];
1424         struct hlist_bl_node *pos;
1425
1426         rcu_read_lock();
1427         hlist_bl_for_each_entry_rcu(gl, pos, head, gl_list) {
1428                 if ((gl->gl_sbd == sdp) && atomic_read(&gl->gl_ref))
1429                         examiner(gl);
1430         }
1431         rcu_read_unlock();
1432         cond_resched();
1433 }
1434
1435 static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
1436 {
1437         unsigned x;
1438
1439         for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1440                 examine_bucket(examiner, sdp, x);
1441 }
1442
1443
1444 /**
1445  * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1446  * @gl: The glock to thaw
1447  *
1448  * N.B. When we freeze a glock, we leave a ref to the glock outstanding,
1449  * so this has to result in the ref count being dropped by one.
1450  */
1451
1452 static void thaw_glock(struct gfs2_glock *gl)
1453 {
1454         if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1455                 return;
1456         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1457         gfs2_glock_hold(gl);
1458         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1459                 gfs2_glock_put(gl);
1460 }
1461
1462 /**
1463  * clear_glock - look at a glock and see if we can free it from glock cache
1464  * @gl: the glock to look at
1465  *
1466  */
1467
1468 static void clear_glock(struct gfs2_glock *gl)
1469 {
1470         gfs2_glock_remove_from_lru(gl);
1471
1472         spin_lock(&gl->gl_spin);
1473         if (gl->gl_state != LM_ST_UNLOCKED)
1474                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1475         spin_unlock(&gl->gl_spin);
1476         gfs2_glock_hold(gl);
1477         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1478                 gfs2_glock_put(gl);
1479 }
1480
1481 /**
1482  * gfs2_glock_thaw - Thaw any frozen glocks
1483  * @sdp: The super block
1484  *
1485  */
1486
1487 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1488 {
1489         glock_hash_walk(thaw_glock, sdp);
1490 }
1491
1492 static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1493 {
1494         int ret;
1495         spin_lock(&gl->gl_spin);
1496         ret = __dump_glock(seq, gl);
1497         spin_unlock(&gl->gl_spin);
1498         return ret;
1499 }
1500
1501 static void dump_glock_func(struct gfs2_glock *gl)
1502 {
1503         dump_glock(NULL, gl);
1504 }
1505
1506 /**
1507  * gfs2_gl_hash_clear - Empty out the glock hash table
1508  * @sdp: the filesystem
1509  * @wait: wait until it's all gone
1510  *
1511  * Called when unmounting the filesystem.
1512  */
1513
1514 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1515 {
1516         glock_hash_walk(clear_glock, sdp);
1517         flush_workqueue(glock_workqueue);
1518         wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
1519         glock_hash_walk(dump_glock_func, sdp);
1520 }
1521
1522 void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1523 {
1524         struct gfs2_glock *gl = ip->i_gl;
1525         int ret;
1526
1527         ret = gfs2_truncatei_resume(ip);
1528         gfs2_assert_withdraw(gl->gl_sbd, ret == 0);
1529
1530         spin_lock(&gl->gl_spin);
1531         clear_bit(GLF_LOCK, &gl->gl_flags);
1532         run_queue(gl, 1);
1533         spin_unlock(&gl->gl_spin);
1534 }
1535
1536 static const char *state2str(unsigned state)
1537 {
1538         switch(state) {
1539         case LM_ST_UNLOCKED:
1540                 return "UN";
1541         case LM_ST_SHARED:
1542                 return "SH";
1543         case LM_ST_DEFERRED:
1544                 return "DF";
1545         case LM_ST_EXCLUSIVE:
1546                 return "EX";
1547         }
1548         return "??";
1549 }
1550
1551 static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags)
1552 {
1553         char *p = buf;
1554         if (flags & LM_FLAG_TRY)
1555                 *p++ = 't';
1556         if (flags & LM_FLAG_TRY_1CB)
1557                 *p++ = 'T';
1558         if (flags & LM_FLAG_NOEXP)
1559                 *p++ = 'e';
1560         if (flags & LM_FLAG_ANY)
1561                 *p++ = 'A';
1562         if (flags & LM_FLAG_PRIORITY)
1563                 *p++ = 'p';
1564         if (flags & GL_ASYNC)
1565                 *p++ = 'a';
1566         if (flags & GL_EXACT)
1567                 *p++ = 'E';
1568         if (flags & GL_NOCACHE)
1569                 *p++ = 'c';
1570         if (test_bit(HIF_HOLDER, &iflags))
1571                 *p++ = 'H';
1572         if (test_bit(HIF_WAIT, &iflags))
1573                 *p++ = 'W';
1574         if (test_bit(HIF_FIRST, &iflags))
1575                 *p++ = 'F';
1576         *p = 0;
1577         return buf;
1578 }
1579
1580 /**
1581  * dump_holder - print information about a glock holder
1582  * @seq: the seq_file struct
1583  * @gh: the glock holder
1584  *
1585  * Returns: 0 on success, -ENOBUFS when we run out of space
1586  */
1587
1588 static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1589 {
1590         struct task_struct *gh_owner = NULL;
1591         char flags_buf[32];
1592
1593         if (gh->gh_owner_pid)
1594                 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1595         gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
1596                        state2str(gh->gh_state),
1597                        hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1598                        gh->gh_error,
1599                        gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1600                        gh_owner ? gh_owner->comm : "(ended)",
1601                        (void *)gh->gh_ip);
1602         return 0;
1603 }
1604
1605 static const char *gflags2str(char *buf, const struct gfs2_glock *gl)
1606 {
1607         const unsigned long *gflags = &gl->gl_flags;
1608         char *p = buf;
1609
1610         if (test_bit(GLF_LOCK, gflags))
1611                 *p++ = 'l';
1612         if (test_bit(GLF_DEMOTE, gflags))
1613                 *p++ = 'D';
1614         if (test_bit(GLF_PENDING_DEMOTE, gflags))
1615                 *p++ = 'd';
1616         if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1617                 *p++ = 'p';
1618         if (test_bit(GLF_DIRTY, gflags))
1619                 *p++ = 'y';
1620         if (test_bit(GLF_LFLUSH, gflags))
1621                 *p++ = 'f';
1622         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1623                 *p++ = 'i';
1624         if (test_bit(GLF_REPLY_PENDING, gflags))
1625                 *p++ = 'r';
1626         if (test_bit(GLF_INITIAL, gflags))
1627                 *p++ = 'I';
1628         if (test_bit(GLF_FROZEN, gflags))
1629                 *p++ = 'F';
1630         if (test_bit(GLF_QUEUED, gflags))
1631                 *p++ = 'q';
1632         if (test_bit(GLF_LRU, gflags))
1633                 *p++ = 'L';
1634         if (gl->gl_object)
1635                 *p++ = 'o';
1636         *p = 0;
1637         return buf;
1638 }
1639
1640 /**
1641  * __dump_glock - print information about a glock
1642  * @seq: The seq_file struct
1643  * @gl: the glock
1644  *
1645  * The file format is as follows:
1646  * One line per object, capital letters are used to indicate objects
1647  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1648  * other objects are indented by a single space and follow the glock to
1649  * which they are related. Fields are indicated by lower case letters
1650  * followed by a colon and the field value, except for strings which are in
1651  * [] so that its possible to see if they are composed of spaces for
1652  * example. The field's are n = number (id of the object), f = flags,
1653  * t = type, s = state, r = refcount, e = error, p = pid.
1654  *
1655  * Returns: 0 on success, -ENOBUFS when we run out of space
1656  */
1657
1658 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1659 {
1660         const struct gfs2_glock_operations *glops = gl->gl_ops;
1661         unsigned long long dtime;
1662         const struct gfs2_holder *gh;
1663         char gflags_buf[32];
1664         int error = 0;
1665
1666         dtime = jiffies - gl->gl_demote_time;
1667         dtime *= 1000000/HZ; /* demote time in uSec */
1668         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1669                 dtime = 0;
1670         gfs2_print_dbg(seq, "G:  s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d v:%d r:%d\n",
1671                   state2str(gl->gl_state),
1672                   gl->gl_name.ln_type,
1673                   (unsigned long long)gl->gl_name.ln_number,
1674                   gflags2str(gflags_buf, gl),
1675                   state2str(gl->gl_target),
1676                   state2str(gl->gl_demote_state), dtime,
1677                   atomic_read(&gl->gl_ail_count),
1678                   atomic_read(&gl->gl_revokes),
1679                   atomic_read(&gl->gl_ref));
1680
1681         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1682                 error = dump_holder(seq, gh);
1683                 if (error)
1684                         goto out;
1685         }
1686         if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1687                 error = glops->go_dump(seq, gl);
1688 out:
1689         return error;
1690 }
1691
1692
1693
1694
1695 int __init gfs2_glock_init(void)
1696 {
1697         unsigned i;
1698         for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
1699                 INIT_HLIST_BL_HEAD(&gl_hash_table[i]);
1700         }
1701
1702         glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
1703                                           WQ_HIGHPRI | WQ_FREEZABLE, 0);
1704         if (IS_ERR(glock_workqueue))
1705                 return PTR_ERR(glock_workqueue);
1706         gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
1707                                                 WQ_MEM_RECLAIM | WQ_FREEZABLE,
1708                                                 0);
1709         if (IS_ERR(gfs2_delete_workqueue)) {
1710                 destroy_workqueue(glock_workqueue);
1711                 return PTR_ERR(gfs2_delete_workqueue);
1712         }
1713
1714         register_shrinker(&glock_shrinker);
1715
1716         return 0;
1717 }
1718
1719 void gfs2_glock_exit(void)
1720 {
1721         unregister_shrinker(&glock_shrinker);
1722         destroy_workqueue(glock_workqueue);
1723         destroy_workqueue(gfs2_delete_workqueue);
1724 }
1725
1726 static inline struct gfs2_glock *glock_hash_chain(unsigned hash)
1727 {
1728         return hlist_bl_entry(hlist_bl_first_rcu(&gl_hash_table[hash]),
1729                               struct gfs2_glock, gl_list);
1730 }
1731
1732 static inline struct gfs2_glock *glock_hash_next(struct gfs2_glock *gl)
1733 {
1734         return hlist_bl_entry(rcu_dereference(gl->gl_list.next),
1735                               struct gfs2_glock, gl_list);
1736 }
1737
1738 static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1739 {
1740         struct gfs2_glock *gl;
1741
1742         do {
1743                 gl = gi->gl;
1744                 if (gl) {
1745                         gi->gl = glock_hash_next(gl);
1746                 } else {
1747                         gi->gl = glock_hash_chain(gi->hash);
1748                 }
1749                 while (gi->gl == NULL) {
1750                         gi->hash++;
1751                         if (gi->hash >= GFS2_GL_HASH_SIZE) {
1752                                 rcu_read_unlock();
1753                                 return 1;
1754                         }
1755                         gi->gl = glock_hash_chain(gi->hash);
1756                 }
1757         /* Skip entries for other sb and dead entries */
1758         } while (gi->sdp != gi->gl->gl_sbd || atomic_read(&gi->gl->gl_ref) == 0);
1759
1760         return 0;
1761 }
1762
1763 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1764 {
1765         struct gfs2_glock_iter *gi = seq->private;
1766         loff_t n = *pos;
1767
1768         gi->hash = 0;
1769         rcu_read_lock();
1770
1771         do {
1772                 if (gfs2_glock_iter_next(gi))
1773                         return NULL;
1774         } while (n--);
1775
1776         return gi->gl;
1777 }
1778
1779 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1780                                  loff_t *pos)
1781 {
1782         struct gfs2_glock_iter *gi = seq->private;
1783
1784         (*pos)++;
1785
1786         if (gfs2_glock_iter_next(gi))
1787                 return NULL;
1788
1789         return gi->gl;
1790 }
1791
1792 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1793 {
1794         struct gfs2_glock_iter *gi = seq->private;
1795
1796         if (gi->gl)
1797                 rcu_read_unlock();
1798         gi->gl = NULL;
1799 }
1800
1801 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1802 {
1803         return dump_glock(seq, iter_ptr);
1804 }
1805
1806 static const struct seq_operations gfs2_glock_seq_ops = {
1807         .start = gfs2_glock_seq_start,
1808         .next  = gfs2_glock_seq_next,
1809         .stop  = gfs2_glock_seq_stop,
1810         .show  = gfs2_glock_seq_show,
1811 };
1812
1813 static int gfs2_debugfs_open(struct inode *inode, struct file *file)
1814 {
1815         int ret = seq_open_private(file, &gfs2_glock_seq_ops,
1816                                    sizeof(struct gfs2_glock_iter));
1817         if (ret == 0) {
1818                 struct seq_file *seq = file->private_data;
1819                 struct gfs2_glock_iter *gi = seq->private;
1820                 gi->sdp = inode->i_private;
1821         }
1822         return ret;
1823 }
1824
1825 static const struct file_operations gfs2_debug_fops = {
1826         .owner   = THIS_MODULE,
1827         .open    = gfs2_debugfs_open,
1828         .read    = seq_read,
1829         .llseek  = seq_lseek,
1830         .release = seq_release_private,
1831 };
1832
1833 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
1834 {
1835         sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
1836         if (!sdp->debugfs_dir)
1837                 return -ENOMEM;
1838         sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
1839                                                          S_IFREG | S_IRUGO,
1840                                                          sdp->debugfs_dir, sdp,
1841                                                          &gfs2_debug_fops);
1842         if (!sdp->debugfs_dentry_glocks)
1843                 return -ENOMEM;
1844
1845         return 0;
1846 }
1847
1848 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
1849 {
1850         if (sdp && sdp->debugfs_dir) {
1851                 if (sdp->debugfs_dentry_glocks) {
1852                         debugfs_remove(sdp->debugfs_dentry_glocks);
1853                         sdp->debugfs_dentry_glocks = NULL;
1854                 }
1855                 debugfs_remove(sdp->debugfs_dir);
1856                 sdp->debugfs_dir = NULL;
1857         }
1858 }
1859
1860 int gfs2_register_debugfs(void)
1861 {
1862         gfs2_root = debugfs_create_dir("gfs2", NULL);
1863         return gfs2_root ? 0 : -ENOMEM;
1864 }
1865
1866 void gfs2_unregister_debugfs(void)
1867 {
1868         debugfs_remove(gfs2_root);
1869         gfs2_root = NULL;
1870 }