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TOMOYO Linux Cross Reference
Linux/fs/gfs2/glock.c

Version: ~ [ linux-5.13-rc1 ] ~ [ linux-5.12.2 ] ~ [ linux-5.11.19 ] ~ [ linux-5.10.35 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.117 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.190 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.232 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.268 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.268 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  1 /*
  2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
  3  * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
  4  *
  5  * This copyrighted material is made available to anyone wishing to use,
  6  * modify, copy, or redistribute it subject to the terms and conditions
  7  * of the GNU General Public License version 2.
  8  */
  9 
 10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 11 
 12 #include <linux/sched.h>
 13 #include <linux/slab.h>
 14 #include <linux/spinlock.h>
 15 #include <linux/buffer_head.h>
 16 #include <linux/delay.h>
 17 #include <linux/sort.h>
 18 #include <linux/jhash.h>
 19 #include <linux/kallsyms.h>
 20 #include <linux/gfs2_ondisk.h>
 21 #include <linux/list.h>
 22 #include <linux/wait.h>
 23 #include <linux/module.h>
 24 #include <asm/uaccess.h>
 25 #include <linux/seq_file.h>
 26 #include <linux/debugfs.h>
 27 #include <linux/kthread.h>
 28 #include <linux/freezer.h>
 29 #include <linux/workqueue.h>
 30 #include <linux/jiffies.h>
 31 #include <linux/rcupdate.h>
 32 #include <linux/rculist_bl.h>
 33 #include <linux/bit_spinlock.h>
 34 #include <linux/percpu.h>
 35 #include <linux/list_sort.h>
 36 #include <linux/lockref.h>
 37 #include <linux/rhashtable.h>
 38 
 39 #include "gfs2.h"
 40 #include "incore.h"
 41 #include "glock.h"
 42 #include "glops.h"
 43 #include "inode.h"
 44 #include "lops.h"
 45 #include "meta_io.h"
 46 #include "quota.h"
 47 #include "super.h"
 48 #include "util.h"
 49 #include "bmap.h"
 50 #define CREATE_TRACE_POINTS
 51 #include "trace_gfs2.h"
 52 
 53 struct gfs2_glock_iter {
 54         struct gfs2_sbd *sdp;           /* incore superblock           */
 55         struct rhashtable_iter hti;     /* rhashtable iterator         */
 56         struct gfs2_glock *gl;          /* current glock struct        */
 57         loff_t last_pos;                /* last position               */
 58 };
 59 
 60 typedef void (*glock_examiner) (struct gfs2_glock * gl);
 61 
 62 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
 63 
 64 static struct dentry *gfs2_root;
 65 static struct workqueue_struct *glock_workqueue;
 66 struct workqueue_struct *gfs2_delete_workqueue;
 67 static LIST_HEAD(lru_list);
 68 static atomic_t lru_count = ATOMIC_INIT(0);
 69 static DEFINE_SPINLOCK(lru_lock);
 70 
 71 #define GFS2_GL_HASH_SHIFT      15
 72 #define GFS2_GL_HASH_SIZE       (1 << GFS2_GL_HASH_SHIFT)
 73 
 74 static struct rhashtable_params ht_parms = {
 75         .nelem_hint = GFS2_GL_HASH_SIZE * 3 / 4,
 76         .key_len = sizeof(struct lm_lockname),
 77         .key_offset = offsetof(struct gfs2_glock, gl_name),
 78         .head_offset = offsetof(struct gfs2_glock, gl_node),
 79 };
 80 
 81 static struct rhashtable gl_hash_table;
 82 
 83 void gfs2_glock_free(struct gfs2_glock *gl)
 84 {
 85         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
 86 
 87         if (gl->gl_ops->go_flags & GLOF_ASPACE) {
 88                 kmem_cache_free(gfs2_glock_aspace_cachep, gl);
 89         } else {
 90                 kfree(gl->gl_lksb.sb_lvbptr);
 91                 kmem_cache_free(gfs2_glock_cachep, gl);
 92         }
 93         if (atomic_dec_and_test(&sdp->sd_glock_disposal))
 94                 wake_up(&sdp->sd_glock_wait);
 95 }
 96 
 97 /**
 98  * gfs2_glock_hold() - increment reference count on glock
 99  * @gl: The glock to hold
100  *
101  */
102 
103 static void gfs2_glock_hold(struct gfs2_glock *gl)
104 {
105         GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
106         lockref_get(&gl->gl_lockref);
107 }
108 
109 /**
110  * demote_ok - Check to see if it's ok to unlock a glock
111  * @gl: the glock
112  *
113  * Returns: 1 if it's ok
114  */
115 
116 static int demote_ok(const struct gfs2_glock *gl)
117 {
118         const struct gfs2_glock_operations *glops = gl->gl_ops;
119 
120         if (gl->gl_state == LM_ST_UNLOCKED)
121                 return 0;
122         if (!list_empty(&gl->gl_holders))
123                 return 0;
124         if (glops->go_demote_ok)
125                 return glops->go_demote_ok(gl);
126         return 1;
127 }
128 
129 
130 void gfs2_glock_add_to_lru(struct gfs2_glock *gl)
131 {
132         spin_lock(&lru_lock);
133 
134         if (!list_empty(&gl->gl_lru))
135                 list_del_init(&gl->gl_lru);
136         else
137                 atomic_inc(&lru_count);
138 
139         list_add_tail(&gl->gl_lru, &lru_list);
140         set_bit(GLF_LRU, &gl->gl_flags);
141         spin_unlock(&lru_lock);
142 }
143 
144 static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
145 {
146         spin_lock(&lru_lock);
147         if (!list_empty(&gl->gl_lru)) {
148                 list_del_init(&gl->gl_lru);
149                 atomic_dec(&lru_count);
150                 clear_bit(GLF_LRU, &gl->gl_flags);
151         }
152         spin_unlock(&lru_lock);
153 }
154 
155 /**
156  * gfs2_glock_put() - Decrement reference count on glock
157  * @gl: The glock to put
158  *
159  */
160 
161 void gfs2_glock_put(struct gfs2_glock *gl)
162 {
163         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
164         struct address_space *mapping = gfs2_glock2aspace(gl);
165 
166         if (lockref_put_or_lock(&gl->gl_lockref))
167                 return;
168 
169         lockref_mark_dead(&gl->gl_lockref);
170 
171         gfs2_glock_remove_from_lru(gl);
172         spin_unlock(&gl->gl_lockref.lock);
173         rhashtable_remove_fast(&gl_hash_table, &gl->gl_node, ht_parms);
174         GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
175         GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
176         trace_gfs2_glock_put(gl);
177         sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
178 }
179 
180 /**
181  * may_grant - check if its ok to grant a new lock
182  * @gl: The glock
183  * @gh: The lock request which we wish to grant
184  *
185  * Returns: true if its ok to grant the lock
186  */
187 
188 static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
189 {
190         const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
191         if ((gh->gh_state == LM_ST_EXCLUSIVE ||
192              gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
193                 return 0;
194         if (gl->gl_state == gh->gh_state)
195                 return 1;
196         if (gh->gh_flags & GL_EXACT)
197                 return 0;
198         if (gl->gl_state == LM_ST_EXCLUSIVE) {
199                 if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
200                         return 1;
201                 if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
202                         return 1;
203         }
204         if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
205                 return 1;
206         return 0;
207 }
208 
209 static void gfs2_holder_wake(struct gfs2_holder *gh)
210 {
211         clear_bit(HIF_WAIT, &gh->gh_iflags);
212         smp_mb__after_atomic();
213         wake_up_bit(&gh->gh_iflags, HIF_WAIT);
214 }
215 
216 /**
217  * do_error - Something unexpected has happened during a lock request
218  *
219  */
220 
221 static void do_error(struct gfs2_glock *gl, const int ret)
222 {
223         struct gfs2_holder *gh, *tmp;
224 
225         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
226                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
227                         continue;
228                 if (ret & LM_OUT_ERROR)
229                         gh->gh_error = -EIO;
230                 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
231                         gh->gh_error = GLR_TRYFAILED;
232                 else
233                         continue;
234                 list_del_init(&gh->gh_list);
235                 trace_gfs2_glock_queue(gh, 0);
236                 gfs2_holder_wake(gh);
237         }
238 }
239 
240 /**
241  * do_promote - promote as many requests as possible on the current queue
242  * @gl: The glock
243  * 
244  * Returns: 1 if there is a blocked holder at the head of the list, or 2
245  *          if a type specific operation is underway.
246  */
247 
248 static int do_promote(struct gfs2_glock *gl)
249 __releases(&gl->gl_lockref.lock)
250 __acquires(&gl->gl_lockref.lock)
251 {
252         const struct gfs2_glock_operations *glops = gl->gl_ops;
253         struct gfs2_holder *gh, *tmp;
254         int ret;
255 
256 restart:
257         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
258                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
259                         continue;
260                 if (may_grant(gl, gh)) {
261                         if (gh->gh_list.prev == &gl->gl_holders &&
262                             glops->go_lock) {
263                                 spin_unlock(&gl->gl_lockref.lock);
264                                 /* FIXME: eliminate this eventually */
265                                 ret = glops->go_lock(gh);
266                                 spin_lock(&gl->gl_lockref.lock);
267                                 if (ret) {
268                                         if (ret == 1)
269                                                 return 2;
270                                         gh->gh_error = ret;
271                                         list_del_init(&gh->gh_list);
272                                         trace_gfs2_glock_queue(gh, 0);
273                                         gfs2_holder_wake(gh);
274                                         goto restart;
275                                 }
276                                 set_bit(HIF_HOLDER, &gh->gh_iflags);
277                                 trace_gfs2_promote(gh, 1);
278                                 gfs2_holder_wake(gh);
279                                 goto restart;
280                         }
281                         set_bit(HIF_HOLDER, &gh->gh_iflags);
282                         trace_gfs2_promote(gh, 0);
283                         gfs2_holder_wake(gh);
284                         continue;
285                 }
286                 if (gh->gh_list.prev == &gl->gl_holders)
287                         return 1;
288                 do_error(gl, 0);
289                 break;
290         }
291         return 0;
292 }
293 
294 /**
295  * find_first_waiter - find the first gh that's waiting for the glock
296  * @gl: the glock
297  */
298 
299 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
300 {
301         struct gfs2_holder *gh;
302 
303         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
304                 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
305                         return gh;
306         }
307         return NULL;
308 }
309 
310 /**
311  * state_change - record that the glock is now in a different state
312  * @gl: the glock
313  * @new_state the new state
314  *
315  */
316 
317 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
318 {
319         int held1, held2;
320 
321         held1 = (gl->gl_state != LM_ST_UNLOCKED);
322         held2 = (new_state != LM_ST_UNLOCKED);
323 
324         if (held1 != held2) {
325                 GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
326                 if (held2)
327                         gl->gl_lockref.count++;
328                 else
329                         gl->gl_lockref.count--;
330         }
331         if (held1 && held2 && list_empty(&gl->gl_holders))
332                 clear_bit(GLF_QUEUED, &gl->gl_flags);
333 
334         if (new_state != gl->gl_target)
335                 /* shorten our minimum hold time */
336                 gl->gl_hold_time = max(gl->gl_hold_time - GL_GLOCK_HOLD_DECR,
337                                        GL_GLOCK_MIN_HOLD);
338         gl->gl_state = new_state;
339         gl->gl_tchange = jiffies;
340 }
341 
342 static void gfs2_demote_wake(struct gfs2_glock *gl)
343 {
344         gl->gl_demote_state = LM_ST_EXCLUSIVE;
345         clear_bit(GLF_DEMOTE, &gl->gl_flags);
346         smp_mb__after_atomic();
347         wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
348 }
349 
350 /**
351  * finish_xmote - The DLM has replied to one of our lock requests
352  * @gl: The glock
353  * @ret: The status from the DLM
354  *
355  */
356 
357 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
358 {
359         const struct gfs2_glock_operations *glops = gl->gl_ops;
360         struct gfs2_holder *gh;
361         unsigned state = ret & LM_OUT_ST_MASK;
362         int rv;
363 
364         spin_lock(&gl->gl_lockref.lock);
365         trace_gfs2_glock_state_change(gl, state);
366         state_change(gl, state);
367         gh = find_first_waiter(gl);
368 
369         /* Demote to UN request arrived during demote to SH or DF */
370         if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
371             state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
372                 gl->gl_target = LM_ST_UNLOCKED;
373 
374         /* Check for state != intended state */
375         if (unlikely(state != gl->gl_target)) {
376                 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
377                         /* move to back of queue and try next entry */
378                         if (ret & LM_OUT_CANCELED) {
379                                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
380                                         list_move_tail(&gh->gh_list, &gl->gl_holders);
381                                 gh = find_first_waiter(gl);
382                                 gl->gl_target = gh->gh_state;
383                                 goto retry;
384                         }
385                         /* Some error or failed "try lock" - report it */
386                         if ((ret & LM_OUT_ERROR) ||
387                             (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
388                                 gl->gl_target = gl->gl_state;
389                                 do_error(gl, ret);
390                                 goto out;
391                         }
392                 }
393                 switch(state) {
394                 /* Unlocked due to conversion deadlock, try again */
395                 case LM_ST_UNLOCKED:
396 retry:
397                         do_xmote(gl, gh, gl->gl_target);
398                         break;
399                 /* Conversion fails, unlock and try again */
400                 case LM_ST_SHARED:
401                 case LM_ST_DEFERRED:
402                         do_xmote(gl, gh, LM_ST_UNLOCKED);
403                         break;
404                 default: /* Everything else */
405                         pr_err("wanted %u got %u\n", gl->gl_target, state);
406                         GLOCK_BUG_ON(gl, 1);
407                 }
408                 spin_unlock(&gl->gl_lockref.lock);
409                 return;
410         }
411 
412         /* Fast path - we got what we asked for */
413         if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
414                 gfs2_demote_wake(gl);
415         if (state != LM_ST_UNLOCKED) {
416                 if (glops->go_xmote_bh) {
417                         spin_unlock(&gl->gl_lockref.lock);
418                         rv = glops->go_xmote_bh(gl, gh);
419                         spin_lock(&gl->gl_lockref.lock);
420                         if (rv) {
421                                 do_error(gl, rv);
422                                 goto out;
423                         }
424                 }
425                 rv = do_promote(gl);
426                 if (rv == 2)
427                         goto out_locked;
428         }
429 out:
430         clear_bit(GLF_LOCK, &gl->gl_flags);
431 out_locked:
432         spin_unlock(&gl->gl_lockref.lock);
433 }
434 
435 /**
436  * do_xmote - Calls the DLM to change the state of a lock
437  * @gl: The lock state
438  * @gh: The holder (only for promotes)
439  * @target: The target lock state
440  *
441  */
442 
443 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
444 __releases(&gl->gl_lockref.lock)
445 __acquires(&gl->gl_lockref.lock)
446 {
447         const struct gfs2_glock_operations *glops = gl->gl_ops;
448         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
449         unsigned int lck_flags = (unsigned int)(gh ? gh->gh_flags : 0);
450         int ret;
451 
452         lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
453                       LM_FLAG_PRIORITY);
454         GLOCK_BUG_ON(gl, gl->gl_state == target);
455         GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
456         if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
457             glops->go_inval) {
458                 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
459                 do_error(gl, 0); /* Fail queued try locks */
460         }
461         gl->gl_req = target;
462         set_bit(GLF_BLOCKING, &gl->gl_flags);
463         if ((gl->gl_req == LM_ST_UNLOCKED) ||
464             (gl->gl_state == LM_ST_EXCLUSIVE) ||
465             (lck_flags & (LM_FLAG_TRY|LM_FLAG_TRY_1CB)))
466                 clear_bit(GLF_BLOCKING, &gl->gl_flags);
467         spin_unlock(&gl->gl_lockref.lock);
468         if (glops->go_sync)
469                 glops->go_sync(gl);
470         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
471                 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
472         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
473 
474         gfs2_glock_hold(gl);
475         if (sdp->sd_lockstruct.ls_ops->lm_lock) {
476                 /* lock_dlm */
477                 ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
478                 if (ret == -EINVAL && gl->gl_target == LM_ST_UNLOCKED &&
479                     target == LM_ST_UNLOCKED &&
480                     test_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags)) {
481                         finish_xmote(gl, target);
482                         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
483                                 gfs2_glock_put(gl);
484                 }
485                 else if (ret) {
486                         pr_err("lm_lock ret %d\n", ret);
487                         GLOCK_BUG_ON(gl, 1);
488                 }
489         } else { /* lock_nolock */
490                 finish_xmote(gl, target);
491                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
492                         gfs2_glock_put(gl);
493         }
494 
495         spin_lock(&gl->gl_lockref.lock);
496 }
497 
498 /**
499  * find_first_holder - find the first "holder" gh
500  * @gl: the glock
501  */
502 
503 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
504 {
505         struct gfs2_holder *gh;
506 
507         if (!list_empty(&gl->gl_holders)) {
508                 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
509                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
510                         return gh;
511         }
512         return NULL;
513 }
514 
515 /**
516  * run_queue - do all outstanding tasks related to a glock
517  * @gl: The glock in question
518  * @nonblock: True if we must not block in run_queue
519  *
520  */
521 
522 static void run_queue(struct gfs2_glock *gl, const int nonblock)
523 __releases(&gl->gl_lockref.lock)
524 __acquires(&gl->gl_lockref.lock)
525 {
526         struct gfs2_holder *gh = NULL;
527         int ret;
528 
529         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
530                 return;
531 
532         GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
533 
534         if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
535             gl->gl_demote_state != gl->gl_state) {
536                 if (find_first_holder(gl))
537                         goto out_unlock;
538                 if (nonblock)
539                         goto out_sched;
540                 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
541                 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
542                 gl->gl_target = gl->gl_demote_state;
543         } else {
544                 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
545                         gfs2_demote_wake(gl);
546                 ret = do_promote(gl);
547                 if (ret == 0)
548                         goto out_unlock;
549                 if (ret == 2)
550                         goto out;
551                 gh = find_first_waiter(gl);
552                 gl->gl_target = gh->gh_state;
553                 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
554                         do_error(gl, 0); /* Fail queued try locks */
555         }
556         do_xmote(gl, gh, gl->gl_target);
557 out:
558         return;
559 
560 out_sched:
561         clear_bit(GLF_LOCK, &gl->gl_flags);
562         smp_mb__after_atomic();
563         gl->gl_lockref.count++;
564         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
565                 gl->gl_lockref.count--;
566         return;
567 
568 out_unlock:
569         clear_bit(GLF_LOCK, &gl->gl_flags);
570         smp_mb__after_atomic();
571         return;
572 }
573 
574 static void delete_work_func(struct work_struct *work)
575 {
576         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
577         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
578         struct inode *inode;
579         u64 no_addr = gl->gl_name.ln_number;
580 
581         /* If someone's using this glock to create a new dinode, the block must
582            have been freed by another node, then re-used, in which case our
583            iopen callback is too late after the fact. Ignore it. */
584         if (test_bit(GLF_INODE_CREATING, &gl->gl_flags))
585                 goto out;
586 
587         inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
588         if (inode && !IS_ERR(inode)) {
589                 d_prune_aliases(inode);
590                 iput(inode);
591         }
592 out:
593         gfs2_glock_put(gl);
594 }
595 
596 static void glock_work_func(struct work_struct *work)
597 {
598         unsigned long delay = 0;
599         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
600         int drop_ref = 0;
601 
602         if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
603                 finish_xmote(gl, gl->gl_reply);
604                 drop_ref = 1;
605         }
606         spin_lock(&gl->gl_lockref.lock);
607         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
608             gl->gl_state != LM_ST_UNLOCKED &&
609             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
610                 unsigned long holdtime, now = jiffies;
611 
612                 holdtime = gl->gl_tchange + gl->gl_hold_time;
613                 if (time_before(now, holdtime))
614                         delay = holdtime - now;
615 
616                 if (!delay) {
617                         clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
618                         set_bit(GLF_DEMOTE, &gl->gl_flags);
619                 }
620         }
621         run_queue(gl, 0);
622         spin_unlock(&gl->gl_lockref.lock);
623         if (!delay)
624                 gfs2_glock_put(gl);
625         else {
626                 if (gl->gl_name.ln_type != LM_TYPE_INODE)
627                         delay = 0;
628                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
629                         gfs2_glock_put(gl);
630         }
631         if (drop_ref)
632                 gfs2_glock_put(gl);
633 }
634 
635 /**
636  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
637  * @sdp: The GFS2 superblock
638  * @number: the lock number
639  * @glops: The glock_operations to use
640  * @create: If 0, don't create the glock if it doesn't exist
641  * @glp: the glock is returned here
642  *
643  * This does not lock a glock, just finds/creates structures for one.
644  *
645  * Returns: errno
646  */
647 
648 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
649                    const struct gfs2_glock_operations *glops, int create,
650                    struct gfs2_glock **glp)
651 {
652         struct super_block *s = sdp->sd_vfs;
653         struct lm_lockname name = { .ln_number = number,
654                                     .ln_type = glops->go_type,
655                                     .ln_sbd = sdp };
656         struct gfs2_glock *gl, *tmp = NULL;
657         struct address_space *mapping;
658         struct kmem_cache *cachep;
659         int ret, tries = 0;
660 
661         gl = rhashtable_lookup_fast(&gl_hash_table, &name, ht_parms);
662         if (gl && !lockref_get_not_dead(&gl->gl_lockref))
663                 gl = NULL;
664 
665         *glp = gl;
666         if (gl)
667                 return 0;
668         if (!create)
669                 return -ENOENT;
670 
671         if (glops->go_flags & GLOF_ASPACE)
672                 cachep = gfs2_glock_aspace_cachep;
673         else
674                 cachep = gfs2_glock_cachep;
675         gl = kmem_cache_alloc(cachep, GFP_NOFS);
676         if (!gl)
677                 return -ENOMEM;
678 
679         memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
680 
681         if (glops->go_flags & GLOF_LVB) {
682                 gl->gl_lksb.sb_lvbptr = kzalloc(GFS2_MIN_LVB_SIZE, GFP_NOFS);
683                 if (!gl->gl_lksb.sb_lvbptr) {
684                         kmem_cache_free(cachep, gl);
685                         return -ENOMEM;
686                 }
687         }
688 
689         atomic_inc(&sdp->sd_glock_disposal);
690         gl->gl_node.next = NULL;
691         gl->gl_flags = 0;
692         gl->gl_name = name;
693         gl->gl_lockref.count = 1;
694         gl->gl_state = LM_ST_UNLOCKED;
695         gl->gl_target = LM_ST_UNLOCKED;
696         gl->gl_demote_state = LM_ST_EXCLUSIVE;
697         gl->gl_ops = glops;
698         gl->gl_dstamp = ktime_set(0, 0);
699         preempt_disable();
700         /* We use the global stats to estimate the initial per-glock stats */
701         gl->gl_stats = this_cpu_ptr(sdp->sd_lkstats)->lkstats[glops->go_type];
702         preempt_enable();
703         gl->gl_stats.stats[GFS2_LKS_DCOUNT] = 0;
704         gl->gl_stats.stats[GFS2_LKS_QCOUNT] = 0;
705         gl->gl_tchange = jiffies;
706         gl->gl_object = NULL;
707         gl->gl_hold_time = GL_GLOCK_DFT_HOLD;
708         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
709         INIT_WORK(&gl->gl_delete, delete_work_func);
710 
711         mapping = gfs2_glock2aspace(gl);
712         if (mapping) {
713                 mapping->a_ops = &gfs2_meta_aops;
714                 mapping->host = s->s_bdev->bd_inode;
715                 mapping->flags = 0;
716                 mapping_set_gfp_mask(mapping, GFP_NOFS);
717                 mapping->private_data = NULL;
718                 mapping->writeback_index = 0;
719         }
720 
721 again:
722         ret = rhashtable_lookup_insert_fast(&gl_hash_table, &gl->gl_node,
723                                             ht_parms);
724         if (ret == 0) {
725                 *glp = gl;
726                 return 0;
727         }
728 
729         if (ret == -EEXIST) {
730                 ret = 0;
731                 tmp = rhashtable_lookup_fast(&gl_hash_table, &name, ht_parms);
732                 if (tmp == NULL || !lockref_get_not_dead(&tmp->gl_lockref)) {
733                         if (++tries < 100) {
734                                 cond_resched();
735                                 goto again;
736                         }
737                         tmp = NULL;
738                         ret = -ENOMEM;
739                 }
740         } else {
741                 WARN_ON_ONCE(ret);
742         }
743         kfree(gl->gl_lksb.sb_lvbptr);
744         kmem_cache_free(cachep, gl);
745         atomic_dec(&sdp->sd_glock_disposal);
746         *glp = tmp;
747 
748         return ret;
749 }
750 
751 /**
752  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
753  * @gl: the glock
754  * @state: the state we're requesting
755  * @flags: the modifier flags
756  * @gh: the holder structure
757  *
758  */
759 
760 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, u16 flags,
761                       struct gfs2_holder *gh)
762 {
763         INIT_LIST_HEAD(&gh->gh_list);
764         gh->gh_gl = gl;
765         gh->gh_ip = _RET_IP_;
766         gh->gh_owner_pid = get_pid(task_pid(current));
767         gh->gh_state = state;
768         gh->gh_flags = flags;
769         gh->gh_error = 0;
770         gh->gh_iflags = 0;
771         gfs2_glock_hold(gl);
772 }
773 
774 /**
775  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
776  * @state: the state we're requesting
777  * @flags: the modifier flags
778  * @gh: the holder structure
779  *
780  * Don't mess with the glock.
781  *
782  */
783 
784 void gfs2_holder_reinit(unsigned int state, u16 flags, struct gfs2_holder *gh)
785 {
786         gh->gh_state = state;
787         gh->gh_flags = flags;
788         gh->gh_iflags = 0;
789         gh->gh_ip = _RET_IP_;
790         put_pid(gh->gh_owner_pid);
791         gh->gh_owner_pid = get_pid(task_pid(current));
792 }
793 
794 /**
795  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
796  * @gh: the holder structure
797  *
798  */
799 
800 void gfs2_holder_uninit(struct gfs2_holder *gh)
801 {
802         put_pid(gh->gh_owner_pid);
803         gfs2_glock_put(gh->gh_gl);
804         gfs2_holder_mark_uninitialized(gh);
805         gh->gh_ip = 0;
806 }
807 
808 /**
809  * gfs2_glock_wait - wait on a glock acquisition
810  * @gh: the glock holder
811  *
812  * Returns: 0 on success
813  */
814 
815 int gfs2_glock_wait(struct gfs2_holder *gh)
816 {
817         unsigned long time1 = jiffies;
818 
819         might_sleep();
820         wait_on_bit(&gh->gh_iflags, HIF_WAIT, TASK_UNINTERRUPTIBLE);
821         if (time_after(jiffies, time1 + HZ)) /* have we waited > a second? */
822                 /* Lengthen the minimum hold time. */
823                 gh->gh_gl->gl_hold_time = min(gh->gh_gl->gl_hold_time +
824                                               GL_GLOCK_HOLD_INCR,
825                                               GL_GLOCK_MAX_HOLD);
826         return gh->gh_error;
827 }
828 
829 /**
830  * handle_callback - process a demote request
831  * @gl: the glock
832  * @state: the state the caller wants us to change to
833  *
834  * There are only two requests that we are going to see in actual
835  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
836  */
837 
838 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
839                             unsigned long delay, bool remote)
840 {
841         int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
842 
843         set_bit(bit, &gl->gl_flags);
844         if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
845                 gl->gl_demote_state = state;
846                 gl->gl_demote_time = jiffies;
847         } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
848                         gl->gl_demote_state != state) {
849                 gl->gl_demote_state = LM_ST_UNLOCKED;
850         }
851         if (gl->gl_ops->go_callback)
852                 gl->gl_ops->go_callback(gl, remote);
853         trace_gfs2_demote_rq(gl, remote);
854 }
855 
856 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
857 {
858         struct va_format vaf;
859         va_list args;
860 
861         va_start(args, fmt);
862 
863         if (seq) {
864                 seq_vprintf(seq, fmt, args);
865         } else {
866                 vaf.fmt = fmt;
867                 vaf.va = &args;
868 
869                 pr_err("%pV", &vaf);
870         }
871 
872         va_end(args);
873 }
874 
875 /**
876  * add_to_queue - Add a holder to the wait queue (but look for recursion)
877  * @gh: the holder structure to add
878  *
879  * Eventually we should move the recursive locking trap to a
880  * debugging option or something like that. This is the fast
881  * path and needs to have the minimum number of distractions.
882  * 
883  */
884 
885 static inline void add_to_queue(struct gfs2_holder *gh)
886 __releases(&gl->gl_lockref.lock)
887 __acquires(&gl->gl_lockref.lock)
888 {
889         struct gfs2_glock *gl = gh->gh_gl;
890         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
891         struct list_head *insert_pt = NULL;
892         struct gfs2_holder *gh2;
893         int try_futile = 0;
894 
895         BUG_ON(gh->gh_owner_pid == NULL);
896         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
897                 BUG();
898 
899         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
900                 if (test_bit(GLF_LOCK, &gl->gl_flags))
901                         try_futile = !may_grant(gl, gh);
902                 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
903                         goto fail;
904         }
905 
906         list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
907                 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
908                     (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
909                         goto trap_recursive;
910                 if (try_futile &&
911                     !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
912 fail:
913                         gh->gh_error = GLR_TRYFAILED;
914                         gfs2_holder_wake(gh);
915                         return;
916                 }
917                 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
918                         continue;
919                 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
920                         insert_pt = &gh2->gh_list;
921         }
922         set_bit(GLF_QUEUED, &gl->gl_flags);
923         trace_gfs2_glock_queue(gh, 1);
924         gfs2_glstats_inc(gl, GFS2_LKS_QCOUNT);
925         gfs2_sbstats_inc(gl, GFS2_LKS_QCOUNT);
926         if (likely(insert_pt == NULL)) {
927                 list_add_tail(&gh->gh_list, &gl->gl_holders);
928                 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
929                         goto do_cancel;
930                 return;
931         }
932         list_add_tail(&gh->gh_list, insert_pt);
933 do_cancel:
934         gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
935         if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
936                 spin_unlock(&gl->gl_lockref.lock);
937                 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
938                         sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
939                 spin_lock(&gl->gl_lockref.lock);
940         }
941         return;
942 
943 trap_recursive:
944         pr_err("original: %pSR\n", (void *)gh2->gh_ip);
945         pr_err("pid: %d\n", pid_nr(gh2->gh_owner_pid));
946         pr_err("lock type: %d req lock state : %d\n",
947                gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
948         pr_err("new: %pSR\n", (void *)gh->gh_ip);
949         pr_err("pid: %d\n", pid_nr(gh->gh_owner_pid));
950         pr_err("lock type: %d req lock state : %d\n",
951                gh->gh_gl->gl_name.ln_type, gh->gh_state);
952         gfs2_dump_glock(NULL, gl);
953         BUG();
954 }
955 
956 /**
957  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
958  * @gh: the holder structure
959  *
960  * if (gh->gh_flags & GL_ASYNC), this never returns an error
961  *
962  * Returns: 0, GLR_TRYFAILED, or errno on failure
963  */
964 
965 int gfs2_glock_nq(struct gfs2_holder *gh)
966 {
967         struct gfs2_glock *gl = gh->gh_gl;
968         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
969         int error = 0;
970 
971         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
972                 return -EIO;
973 
974         if (test_bit(GLF_LRU, &gl->gl_flags))
975                 gfs2_glock_remove_from_lru(gl);
976 
977         spin_lock(&gl->gl_lockref.lock);
978         add_to_queue(gh);
979         if (unlikely((LM_FLAG_NOEXP & gh->gh_flags) &&
980                      test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))) {
981                 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
982                 gl->gl_lockref.count++;
983                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
984                         gl->gl_lockref.count--;
985         }
986         run_queue(gl, 1);
987         spin_unlock(&gl->gl_lockref.lock);
988 
989         if (!(gh->gh_flags & GL_ASYNC))
990                 error = gfs2_glock_wait(gh);
991 
992         return error;
993 }
994 
995 /**
996  * gfs2_glock_poll - poll to see if an async request has been completed
997  * @gh: the holder
998  *
999  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1000  */
1001 
1002 int gfs2_glock_poll(struct gfs2_holder *gh)
1003 {
1004         return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1005 }
1006 
1007 /**
1008  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1009  * @gh: the glock holder
1010  *
1011  */
1012 
1013 void gfs2_glock_dq(struct gfs2_holder *gh)
1014 {
1015         struct gfs2_glock *gl = gh->gh_gl;
1016         const struct gfs2_glock_operations *glops = gl->gl_ops;
1017         unsigned delay = 0;
1018         int fast_path = 0;
1019 
1020         spin_lock(&gl->gl_lockref.lock);
1021         if (gh->gh_flags & GL_NOCACHE)
1022                 handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1023 
1024         list_del_init(&gh->gh_list);
1025         clear_bit(HIF_HOLDER, &gh->gh_iflags);
1026         if (find_first_holder(gl) == NULL) {
1027                 if (glops->go_unlock) {
1028                         GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1029                         spin_unlock(&gl->gl_lockref.lock);
1030                         glops->go_unlock(gh);
1031                         spin_lock(&gl->gl_lockref.lock);
1032                         clear_bit(GLF_LOCK, &gl->gl_flags);
1033                 }
1034                 if (list_empty(&gl->gl_holders) &&
1035                     !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1036                     !test_bit(GLF_DEMOTE, &gl->gl_flags))
1037                         fast_path = 1;
1038         }
1039         if (!test_bit(GLF_LFLUSH, &gl->gl_flags) && demote_ok(gl) &&
1040             (glops->go_flags & GLOF_LRU))
1041                 gfs2_glock_add_to_lru(gl);
1042 
1043         trace_gfs2_glock_queue(gh, 0);
1044         spin_unlock(&gl->gl_lockref.lock);
1045         if (likely(fast_path))
1046                 return;
1047 
1048         gfs2_glock_hold(gl);
1049         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1050             !test_bit(GLF_DEMOTE, &gl->gl_flags) &&
1051             gl->gl_name.ln_type == LM_TYPE_INODE)
1052                 delay = gl->gl_hold_time;
1053         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1054                 gfs2_glock_put(gl);
1055 }
1056 
1057 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1058 {
1059         struct gfs2_glock *gl = gh->gh_gl;
1060         gfs2_glock_dq(gh);
1061         might_sleep();
1062         wait_on_bit(&gl->gl_flags, GLF_DEMOTE, TASK_UNINTERRUPTIBLE);
1063 }
1064 
1065 /**
1066  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1067  * @gh: the holder structure
1068  *
1069  */
1070 
1071 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1072 {
1073         gfs2_glock_dq(gh);
1074         gfs2_holder_uninit(gh);
1075 }
1076 
1077 /**
1078  * gfs2_glock_nq_num - acquire a glock based on lock number
1079  * @sdp: the filesystem
1080  * @number: the lock number
1081  * @glops: the glock operations for the type of glock
1082  * @state: the state to acquire the glock in
1083  * @flags: modifier flags for the acquisition
1084  * @gh: the struct gfs2_holder
1085  *
1086  * Returns: errno
1087  */
1088 
1089 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1090                       const struct gfs2_glock_operations *glops,
1091                       unsigned int state, u16 flags, struct gfs2_holder *gh)
1092 {
1093         struct gfs2_glock *gl;
1094         int error;
1095 
1096         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1097         if (!error) {
1098                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1099                 gfs2_glock_put(gl);
1100         }
1101 
1102         return error;
1103 }
1104 
1105 /**
1106  * glock_compare - Compare two struct gfs2_glock structures for sorting
1107  * @arg_a: the first structure
1108  * @arg_b: the second structure
1109  *
1110  */
1111 
1112 static int glock_compare(const void *arg_a, const void *arg_b)
1113 {
1114         const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1115         const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1116         const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1117         const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1118 
1119         if (a->ln_number > b->ln_number)
1120                 return 1;
1121         if (a->ln_number < b->ln_number)
1122                 return -1;
1123         BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1124         return 0;
1125 }
1126 
1127 /**
1128  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1129  * @num_gh: the number of structures
1130  * @ghs: an array of struct gfs2_holder structures
1131  *
1132  * Returns: 0 on success (all glocks acquired),
1133  *          errno on failure (no glocks acquired)
1134  */
1135 
1136 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1137                      struct gfs2_holder **p)
1138 {
1139         unsigned int x;
1140         int error = 0;
1141 
1142         for (x = 0; x < num_gh; x++)
1143                 p[x] = &ghs[x];
1144 
1145         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1146 
1147         for (x = 0; x < num_gh; x++) {
1148                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1149 
1150                 error = gfs2_glock_nq(p[x]);
1151                 if (error) {
1152                         while (x--)
1153                                 gfs2_glock_dq(p[x]);
1154                         break;
1155                 }
1156         }
1157 
1158         return error;
1159 }
1160 
1161 /**
1162  * gfs2_glock_nq_m - acquire multiple glocks
1163  * @num_gh: the number of structures
1164  * @ghs: an array of struct gfs2_holder structures
1165  *
1166  *
1167  * Returns: 0 on success (all glocks acquired),
1168  *          errno on failure (no glocks acquired)
1169  */
1170 
1171 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1172 {
1173         struct gfs2_holder *tmp[4];
1174         struct gfs2_holder **pph = tmp;
1175         int error = 0;
1176 
1177         switch(num_gh) {
1178         case 0:
1179                 return 0;
1180         case 1:
1181                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1182                 return gfs2_glock_nq(ghs);
1183         default:
1184                 if (num_gh <= 4)
1185                         break;
1186                 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1187                 if (!pph)
1188                         return -ENOMEM;
1189         }
1190 
1191         error = nq_m_sync(num_gh, ghs, pph);
1192 
1193         if (pph != tmp)
1194                 kfree(pph);
1195 
1196         return error;
1197 }
1198 
1199 /**
1200  * gfs2_glock_dq_m - release multiple glocks
1201  * @num_gh: the number of structures
1202  * @ghs: an array of struct gfs2_holder structures
1203  *
1204  */
1205 
1206 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1207 {
1208         while (num_gh--)
1209                 gfs2_glock_dq(&ghs[num_gh]);
1210 }
1211 
1212 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1213 {
1214         unsigned long delay = 0;
1215         unsigned long holdtime;
1216         unsigned long now = jiffies;
1217 
1218         gfs2_glock_hold(gl);
1219         holdtime = gl->gl_tchange + gl->gl_hold_time;
1220         if (test_bit(GLF_QUEUED, &gl->gl_flags) &&
1221             gl->gl_name.ln_type == LM_TYPE_INODE) {
1222                 if (time_before(now, holdtime))
1223                         delay = holdtime - now;
1224                 if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1225                         delay = gl->gl_hold_time;
1226         }
1227 
1228         spin_lock(&gl->gl_lockref.lock);
1229         handle_callback(gl, state, delay, true);
1230         spin_unlock(&gl->gl_lockref.lock);
1231         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1232                 gfs2_glock_put(gl);
1233 }
1234 
1235 /**
1236  * gfs2_should_freeze - Figure out if glock should be frozen
1237  * @gl: The glock in question
1238  *
1239  * Glocks are not frozen if (a) the result of the dlm operation is
1240  * an error, (b) the locking operation was an unlock operation or
1241  * (c) if there is a "noexp" flagged request anywhere in the queue
1242  *
1243  * Returns: 1 if freezing should occur, 0 otherwise
1244  */
1245 
1246 static int gfs2_should_freeze(const struct gfs2_glock *gl)
1247 {
1248         const struct gfs2_holder *gh;
1249 
1250         if (gl->gl_reply & ~LM_OUT_ST_MASK)
1251                 return 0;
1252         if (gl->gl_target == LM_ST_UNLOCKED)
1253                 return 0;
1254 
1255         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1256                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1257                         continue;
1258                 if (LM_FLAG_NOEXP & gh->gh_flags)
1259                         return 0;
1260         }
1261 
1262         return 1;
1263 }
1264 
1265 /**
1266  * gfs2_glock_complete - Callback used by locking
1267  * @gl: Pointer to the glock
1268  * @ret: The return value from the dlm
1269  *
1270  * The gl_reply field is under the gl_lockref.lock lock so that it is ok
1271  * to use a bitfield shared with other glock state fields.
1272  */
1273 
1274 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1275 {
1276         struct lm_lockstruct *ls = &gl->gl_name.ln_sbd->sd_lockstruct;
1277 
1278         spin_lock(&gl->gl_lockref.lock);
1279         gl->gl_reply = ret;
1280 
1281         if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags))) {
1282                 if (gfs2_should_freeze(gl)) {
1283                         set_bit(GLF_FROZEN, &gl->gl_flags);
1284                         spin_unlock(&gl->gl_lockref.lock);
1285                         return;
1286                 }
1287         }
1288 
1289         gl->gl_lockref.count++;
1290         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1291         spin_unlock(&gl->gl_lockref.lock);
1292 
1293         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1294                 gfs2_glock_put(gl);
1295 }
1296 
1297 static int glock_cmp(void *priv, struct list_head *a, struct list_head *b)
1298 {
1299         struct gfs2_glock *gla, *glb;
1300 
1301         gla = list_entry(a, struct gfs2_glock, gl_lru);
1302         glb = list_entry(b, struct gfs2_glock, gl_lru);
1303 
1304         if (gla->gl_name.ln_number > glb->gl_name.ln_number)
1305                 return 1;
1306         if (gla->gl_name.ln_number < glb->gl_name.ln_number)
1307                 return -1;
1308 
1309         return 0;
1310 }
1311 
1312 /**
1313  * gfs2_dispose_glock_lru - Demote a list of glocks
1314  * @list: The list to dispose of
1315  *
1316  * Disposing of glocks may involve disk accesses, so that here we sort
1317  * the glocks by number (i.e. disk location of the inodes) so that if
1318  * there are any such accesses, they'll be sent in order (mostly).
1319  *
1320  * Must be called under the lru_lock, but may drop and retake this
1321  * lock. While the lru_lock is dropped, entries may vanish from the
1322  * list, but no new entries will appear on the list (since it is
1323  * private)
1324  */
1325 
1326 static void gfs2_dispose_glock_lru(struct list_head *list)
1327 __releases(&lru_lock)
1328 __acquires(&lru_lock)
1329 {
1330         struct gfs2_glock *gl;
1331 
1332         list_sort(NULL, list, glock_cmp);
1333 
1334         while(!list_empty(list)) {
1335                 gl = list_entry(list->next, struct gfs2_glock, gl_lru);
1336                 list_del_init(&gl->gl_lru);
1337                 if (!spin_trylock(&gl->gl_lockref.lock)) {
1338 add_back_to_lru:
1339                         list_add(&gl->gl_lru, &lru_list);
1340                         atomic_inc(&lru_count);
1341                         continue;
1342                 }
1343                 if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1344                         spin_unlock(&gl->gl_lockref.lock);
1345                         goto add_back_to_lru;
1346                 }
1347                 clear_bit(GLF_LRU, &gl->gl_flags);
1348                 gl->gl_lockref.count++;
1349                 if (demote_ok(gl))
1350                         handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1351                 WARN_ON(!test_and_clear_bit(GLF_LOCK, &gl->gl_flags));
1352                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1353                         gl->gl_lockref.count--;
1354                 spin_unlock(&gl->gl_lockref.lock);
1355                 cond_resched_lock(&lru_lock);
1356         }
1357 }
1358 
1359 /**
1360  * gfs2_scan_glock_lru - Scan the LRU looking for locks to demote
1361  * @nr: The number of entries to scan
1362  *
1363  * This function selects the entries on the LRU which are able to
1364  * be demoted, and then kicks off the process by calling
1365  * gfs2_dispose_glock_lru() above.
1366  */
1367 
1368 static long gfs2_scan_glock_lru(int nr)
1369 {
1370         struct gfs2_glock *gl;
1371         LIST_HEAD(skipped);
1372         LIST_HEAD(dispose);
1373         long freed = 0;
1374 
1375         spin_lock(&lru_lock);
1376         while ((nr-- >= 0) && !list_empty(&lru_list)) {
1377                 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1378 
1379                 /* Test for being demotable */
1380                 if (!test_bit(GLF_LOCK, &gl->gl_flags)) {
1381                         list_move(&gl->gl_lru, &dispose);
1382                         atomic_dec(&lru_count);
1383                         freed++;
1384                         continue;
1385                 }
1386 
1387                 list_move(&gl->gl_lru, &skipped);
1388         }
1389         list_splice(&skipped, &lru_list);
1390         if (!list_empty(&dispose))
1391                 gfs2_dispose_glock_lru(&dispose);
1392         spin_unlock(&lru_lock);
1393 
1394         return freed;
1395 }
1396 
1397 static unsigned long gfs2_glock_shrink_scan(struct shrinker *shrink,
1398                                             struct shrink_control *sc)
1399 {
1400         if (!(sc->gfp_mask & __GFP_FS))
1401                 return SHRINK_STOP;
1402         return gfs2_scan_glock_lru(sc->nr_to_scan);
1403 }
1404 
1405 static unsigned long gfs2_glock_shrink_count(struct shrinker *shrink,
1406                                              struct shrink_control *sc)
1407 {
1408         return vfs_pressure_ratio(atomic_read(&lru_count));
1409 }
1410 
1411 static struct shrinker glock_shrinker = {
1412         .seeks = DEFAULT_SEEKS,
1413         .count_objects = gfs2_glock_shrink_count,
1414         .scan_objects = gfs2_glock_shrink_scan,
1415 };
1416 
1417 /**
1418  * examine_bucket - Call a function for glock in a hash bucket
1419  * @examiner: the function
1420  * @sdp: the filesystem
1421  * @bucket: the bucket
1422  *
1423  */
1424 
1425 static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
1426 {
1427         struct gfs2_glock *gl;
1428         struct rhash_head *pos;
1429         const struct bucket_table *tbl;
1430         int i;
1431 
1432         rcu_read_lock();
1433         tbl = rht_dereference_rcu(gl_hash_table.tbl, &gl_hash_table);
1434         for (i = 0; i < tbl->size; i++) {
1435                 rht_for_each_entry_rcu(gl, pos, tbl, i, gl_node) {
1436                         if ((gl->gl_name.ln_sbd == sdp) &&
1437                             lockref_get_not_dead(&gl->gl_lockref))
1438                                 examiner(gl);
1439                 }
1440         }
1441         rcu_read_unlock();
1442         cond_resched();
1443 }
1444 
1445 /**
1446  * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1447  * @gl: The glock to thaw
1448  *
1449  */
1450 
1451 static void thaw_glock(struct gfs2_glock *gl)
1452 {
1453         if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1454                 goto out;
1455         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1456         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0) {
1457 out:
1458                 gfs2_glock_put(gl);
1459         }
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_lockref.lock);
1473         if (gl->gl_state != LM_ST_UNLOCKED)
1474                 handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1475         spin_unlock(&gl->gl_lockref.lock);
1476         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1477                 gfs2_glock_put(gl);
1478 }
1479 
1480 /**
1481  * gfs2_glock_thaw - Thaw any frozen glocks
1482  * @sdp: The super block
1483  *
1484  */
1485 
1486 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1487 {
1488         glock_hash_walk(thaw_glock, sdp);
1489 }
1490 
1491 static void dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1492 {
1493         spin_lock(&gl->gl_lockref.lock);
1494         gfs2_dump_glock(seq, gl);
1495         spin_unlock(&gl->gl_lockref.lock);
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         set_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags);
1514         flush_workqueue(glock_workqueue);
1515         glock_hash_walk(clear_glock, sdp);
1516         flush_workqueue(glock_workqueue);
1517         wait_event_timeout(sdp->sd_glock_wait,
1518                            atomic_read(&sdp->sd_glock_disposal) == 0,
1519                            HZ * 600);
1520         glock_hash_walk(dump_glock_func, sdp);
1521 }
1522 
1523 void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1524 {
1525         struct gfs2_glock *gl = ip->i_gl;
1526         int ret;
1527 
1528         ret = gfs2_truncatei_resume(ip);
1529         gfs2_assert_withdraw(gl->gl_name.ln_sbd, ret == 0);
1530 
1531         spin_lock(&gl->gl_lockref.lock);
1532         clear_bit(GLF_LOCK, &gl->gl_flags);
1533         run_queue(gl, 1);
1534         spin_unlock(&gl->gl_lockref.lock);
1535 }
1536 
1537 static const char *state2str(unsigned state)
1538 {
1539         switch(state) {
1540         case LM_ST_UNLOCKED:
1541                 return "UN";
1542         case LM_ST_SHARED:
1543                 return "SH";
1544         case LM_ST_DEFERRED:
1545                 return "DF";
1546         case LM_ST_EXCLUSIVE:
1547                 return "EX";
1548         }
1549         return "??";
1550 }
1551 
1552 static const char *hflags2str(char *buf, u16 flags, unsigned long iflags)
1553 {
1554         char *p = buf;
1555         if (flags & LM_FLAG_TRY)
1556                 *p++ = 't';
1557         if (flags & LM_FLAG_TRY_1CB)
1558                 *p++ = 'T';
1559         if (flags & LM_FLAG_NOEXP)
1560                 *p++ = 'e';
1561         if (flags & LM_FLAG_ANY)
1562                 *p++ = 'A';
1563         if (flags & LM_FLAG_PRIORITY)
1564                 *p++ = 'p';
1565         if (flags & GL_ASYNC)
1566                 *p++ = 'a';
1567         if (flags & GL_EXACT)
1568                 *p++ = 'E';
1569         if (flags & GL_NOCACHE)
1570                 *p++ = 'c';
1571         if (test_bit(HIF_HOLDER, &iflags))
1572                 *p++ = 'H';
1573         if (test_bit(HIF_WAIT, &iflags))
1574                 *p++ = 'W';
1575         if (test_bit(HIF_FIRST, &iflags))
1576                 *p++ = 'F';
1577         *p = 0;
1578         return buf;
1579 }
1580 
1581 /**
1582  * dump_holder - print information about a glock holder
1583  * @seq: the seq_file struct
1584  * @gh: the glock holder
1585  *
1586  */
1587 
1588 static void 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         rcu_read_lock();
1594         if (gh->gh_owner_pid)
1595                 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1596         gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
1597                        state2str(gh->gh_state),
1598                        hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1599                        gh->gh_error,
1600                        gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1601                        gh_owner ? gh_owner->comm : "(ended)",
1602                        (void *)gh->gh_ip);
1603         rcu_read_unlock();
1604 }
1605 
1606 static const char *gflags2str(char *buf, const struct gfs2_glock *gl)
1607 {
1608         const unsigned long *gflags = &gl->gl_flags;
1609         char *p = buf;
1610 
1611         if (test_bit(GLF_LOCK, gflags))
1612                 *p++ = 'l';
1613         if (test_bit(GLF_DEMOTE, gflags))
1614                 *p++ = 'D';
1615         if (test_bit(GLF_PENDING_DEMOTE, gflags))
1616                 *p++ = 'd';
1617         if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1618                 *p++ = 'p';
1619         if (test_bit(GLF_DIRTY, gflags))
1620                 *p++ = 'y';
1621         if (test_bit(GLF_LFLUSH, gflags))
1622                 *p++ = 'f';
1623         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1624                 *p++ = 'i';
1625         if (test_bit(GLF_REPLY_PENDING, gflags))
1626                 *p++ = 'r';
1627         if (test_bit(GLF_INITIAL, gflags))
1628                 *p++ = 'I';
1629         if (test_bit(GLF_FROZEN, gflags))
1630                 *p++ = 'F';
1631         if (test_bit(GLF_QUEUED, gflags))
1632                 *p++ = 'q';
1633         if (test_bit(GLF_LRU, gflags))
1634                 *p++ = 'L';
1635         if (gl->gl_object)
1636                 *p++ = 'o';
1637         if (test_bit(GLF_BLOCKING, gflags))
1638                 *p++ = 'b';
1639         *p = 0;
1640         return buf;
1641 }
1642 
1643 /**
1644  * gfs2_dump_glock - print information about a glock
1645  * @seq: The seq_file struct
1646  * @gl: the glock
1647  *
1648  * The file format is as follows:
1649  * One line per object, capital letters are used to indicate objects
1650  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1651  * other objects are indented by a single space and follow the glock to
1652  * which they are related. Fields are indicated by lower case letters
1653  * followed by a colon and the field value, except for strings which are in
1654  * [] so that its possible to see if they are composed of spaces for
1655  * example. The field's are n = number (id of the object), f = flags,
1656  * t = type, s = state, r = refcount, e = error, p = pid.
1657  *
1658  */
1659 
1660 void gfs2_dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1661 {
1662         const struct gfs2_glock_operations *glops = gl->gl_ops;
1663         unsigned long long dtime;
1664         const struct gfs2_holder *gh;
1665         char gflags_buf[32];
1666 
1667         dtime = jiffies - gl->gl_demote_time;
1668         dtime *= 1000000/HZ; /* demote time in uSec */
1669         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1670                 dtime = 0;
1671         gfs2_print_dbg(seq, "G:  s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d v:%d r:%d m:%ld\n",
1672                   state2str(gl->gl_state),
1673                   gl->gl_name.ln_type,
1674                   (unsigned long long)gl->gl_name.ln_number,
1675                   gflags2str(gflags_buf, gl),
1676                   state2str(gl->gl_target),
1677                   state2str(gl->gl_demote_state), dtime,
1678                   atomic_read(&gl->gl_ail_count),
1679                   atomic_read(&gl->gl_revokes),
1680                   (int)gl->gl_lockref.count, gl->gl_hold_time);
1681 
1682         list_for_each_entry(gh, &gl->gl_holders, gh_list)
1683                 dump_holder(seq, gh);
1684 
1685         if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1686                 glops->go_dump(seq, gl);
1687 }
1688 
1689 static int gfs2_glstats_seq_show(struct seq_file *seq, void *iter_ptr)
1690 {
1691         struct gfs2_glock *gl = iter_ptr;
1692 
1693         seq_printf(seq, "G: n:%u/%llx rtt:%llu/%llu rttb:%llu/%llu irt:%llu/%llu dcnt: %llu qcnt: %llu\n",
1694                    gl->gl_name.ln_type,
1695                    (unsigned long long)gl->gl_name.ln_number,
1696                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTT],
1697                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTVAR],
1698                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTB],
1699                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTVARB],
1700                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SIRT],
1701                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SIRTVAR],
1702                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_DCOUNT],
1703                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_QCOUNT]);
1704         return 0;
1705 }
1706 
1707 static const char *gfs2_gltype[] = {
1708         "type",
1709         "reserved",
1710         "nondisk",
1711         "inode",
1712         "rgrp",
1713         "meta",
1714         "iopen",
1715         "flock",
1716         "plock",
1717         "quota",
1718         "journal",
1719 };
1720 
1721 static const char *gfs2_stype[] = {
1722         [GFS2_LKS_SRTT]         = "srtt",
1723         [GFS2_LKS_SRTTVAR]      = "srttvar",
1724         [GFS2_LKS_SRTTB]        = "srttb",
1725         [GFS2_LKS_SRTTVARB]     = "srttvarb",
1726         [GFS2_LKS_SIRT]         = "sirt",
1727         [GFS2_LKS_SIRTVAR]      = "sirtvar",
1728         [GFS2_LKS_DCOUNT]       = "dlm",
1729         [GFS2_LKS_QCOUNT]       = "queue",
1730 };
1731 
1732 #define GFS2_NR_SBSTATS (ARRAY_SIZE(gfs2_gltype) * ARRAY_SIZE(gfs2_stype))
1733 
1734 static int gfs2_sbstats_seq_show(struct seq_file *seq, void *iter_ptr)
1735 {
1736         struct gfs2_sbd *sdp = seq->private;
1737         loff_t pos = *(loff_t *)iter_ptr;
1738         unsigned index = pos >> 3;
1739         unsigned subindex = pos & 0x07;
1740         int i;
1741 
1742         if (index == 0 && subindex != 0)
1743                 return 0;
1744 
1745         seq_printf(seq, "%-10s %8s:", gfs2_gltype[index],
1746                    (index == 0) ? "cpu": gfs2_stype[subindex]);
1747 
1748         for_each_possible_cpu(i) {
1749                 const struct gfs2_pcpu_lkstats *lkstats = per_cpu_ptr(sdp->sd_lkstats, i);
1750 
1751                 if (index == 0)
1752                         seq_printf(seq, " %15u", i);
1753                 else
1754                         seq_printf(seq, " %15llu", (unsigned long long)lkstats->
1755                                    lkstats[index - 1].stats[subindex]);
1756         }
1757         seq_putc(seq, '\n');
1758         return 0;
1759 }
1760 
1761 int __init gfs2_glock_init(void)
1762 {
1763         int ret;
1764 
1765         ret = rhashtable_init(&gl_hash_table, &ht_parms);
1766         if (ret < 0)
1767                 return ret;
1768 
1769         glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
1770                                           WQ_HIGHPRI | WQ_FREEZABLE, 0);
1771         if (!glock_workqueue) {
1772                 rhashtable_destroy(&gl_hash_table);
1773                 return -ENOMEM;
1774         }
1775         gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
1776                                                 WQ_MEM_RECLAIM | WQ_FREEZABLE,
1777                                                 0);
1778         if (!gfs2_delete_workqueue) {
1779                 destroy_workqueue(glock_workqueue);
1780                 rhashtable_destroy(&gl_hash_table);
1781                 return -ENOMEM;
1782         }
1783 
1784         register_shrinker(&glock_shrinker);
1785 
1786         return 0;
1787 }
1788 
1789 void gfs2_glock_exit(void)
1790 {
1791         unregister_shrinker(&glock_shrinker);
1792         rhashtable_destroy(&gl_hash_table);
1793         destroy_workqueue(glock_workqueue);
1794         destroy_workqueue(gfs2_delete_workqueue);
1795 }
1796 
1797 static void gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1798 {
1799         do {
1800                 gi->gl = rhashtable_walk_next(&gi->hti);
1801                 if (IS_ERR(gi->gl)) {
1802                         if (PTR_ERR(gi->gl) == -EAGAIN)
1803                                 continue;
1804                         gi->gl = NULL;
1805                 }
1806         /* Skip entries for other sb and dead entries */
1807         } while ((gi->gl) && ((gi->sdp != gi->gl->gl_name.ln_sbd) ||
1808                               __lockref_is_dead(&gi->gl->gl_lockref)));
1809 }
1810 
1811 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1812 {
1813         struct gfs2_glock_iter *gi = seq->private;
1814         loff_t n = *pos;
1815         int ret;
1816 
1817         if (gi->last_pos <= *pos)
1818                 n = (*pos - gi->last_pos);
1819 
1820         ret = rhashtable_walk_start(&gi->hti);
1821         if (ret)
1822                 return NULL;
1823 
1824         do {
1825                 gfs2_glock_iter_next(gi);
1826         } while (gi->gl && n--);
1827 
1828         gi->last_pos = *pos;
1829         return gi->gl;
1830 }
1831 
1832 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1833                                  loff_t *pos)
1834 {
1835         struct gfs2_glock_iter *gi = seq->private;
1836 
1837         (*pos)++;
1838         gi->last_pos = *pos;
1839         gfs2_glock_iter_next(gi);
1840         return gi->gl;
1841 }
1842 
1843 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1844 {
1845         struct gfs2_glock_iter *gi = seq->private;
1846 
1847         gi->gl = NULL;
1848         rhashtable_walk_stop(&gi->hti);
1849 }
1850 
1851 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1852 {
1853         dump_glock(seq, iter_ptr);
1854         return 0;
1855 }
1856 
1857 static void *gfs2_sbstats_seq_start(struct seq_file *seq, loff_t *pos)
1858 {
1859         preempt_disable();
1860         if (*pos >= GFS2_NR_SBSTATS)
1861                 return NULL;
1862         return pos;
1863 }
1864 
1865 static void *gfs2_sbstats_seq_next(struct seq_file *seq, void *iter_ptr,
1866                                    loff_t *pos)
1867 {
1868         (*pos)++;
1869         if (*pos >= GFS2_NR_SBSTATS)
1870                 return NULL;
1871         return pos;
1872 }
1873 
1874 static void gfs2_sbstats_seq_stop(struct seq_file *seq, void *iter_ptr)
1875 {
1876         preempt_enable();
1877 }
1878 
1879 static const struct seq_operations gfs2_glock_seq_ops = {
1880         .start = gfs2_glock_seq_start,
1881         .next  = gfs2_glock_seq_next,
1882         .stop  = gfs2_glock_seq_stop,
1883         .show  = gfs2_glock_seq_show,
1884 };
1885 
1886 static const struct seq_operations gfs2_glstats_seq_ops = {
1887         .start = gfs2_glock_seq_start,
1888         .next  = gfs2_glock_seq_next,
1889         .stop  = gfs2_glock_seq_stop,
1890         .show  = gfs2_glstats_seq_show,
1891 };
1892 
1893 static const struct seq_operations gfs2_sbstats_seq_ops = {
1894         .start = gfs2_sbstats_seq_start,
1895         .next  = gfs2_sbstats_seq_next,
1896         .stop  = gfs2_sbstats_seq_stop,
1897         .show  = gfs2_sbstats_seq_show,
1898 };
1899 
1900 #define GFS2_SEQ_GOODSIZE min(PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER, 65536UL)
1901 
1902 static int gfs2_glocks_open(struct inode *inode, struct file *file)
1903 {
1904         int ret = seq_open_private(file, &gfs2_glock_seq_ops,
1905                                    sizeof(struct gfs2_glock_iter));
1906         if (ret == 0) {
1907                 struct seq_file *seq = file->private_data;
1908                 struct gfs2_glock_iter *gi = seq->private;
1909 
1910                 gi->sdp = inode->i_private;
1911                 gi->last_pos = 0;
1912                 seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
1913                 if (seq->buf)
1914                         seq->size = GFS2_SEQ_GOODSIZE;
1915                 gi->gl = NULL;
1916                 ret = rhashtable_walk_init(&gl_hash_table, &gi->hti, GFP_KERNEL);
1917         }
1918         return ret;
1919 }
1920 
1921 static int gfs2_glocks_release(struct inode *inode, struct file *file)
1922 {
1923         struct seq_file *seq = file->private_data;
1924         struct gfs2_glock_iter *gi = seq->private;
1925 
1926         gi->gl = NULL;
1927         rhashtable_walk_exit(&gi->hti);
1928         return seq_release_private(inode, file);
1929 }
1930 
1931 static int gfs2_glstats_open(struct inode *inode, struct file *file)
1932 {
1933         int ret = seq_open_private(file, &gfs2_glstats_seq_ops,
1934                                    sizeof(struct gfs2_glock_iter));
1935         if (ret == 0) {
1936                 struct seq_file *seq = file->private_data;
1937                 struct gfs2_glock_iter *gi = seq->private;
1938                 gi->sdp = inode->i_private;
1939                 gi->last_pos = 0;
1940                 seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
1941                 if (seq->buf)
1942                         seq->size = GFS2_SEQ_GOODSIZE;
1943                 gi->gl = NULL;
1944                 ret = rhashtable_walk_init(&gl_hash_table, &gi->hti, GFP_KERNEL);
1945         }
1946         return ret;
1947 }
1948 
1949 static int gfs2_sbstats_open(struct inode *inode, struct file *file)
1950 {
1951         int ret = seq_open(file, &gfs2_sbstats_seq_ops);
1952         if (ret == 0) {
1953                 struct seq_file *seq = file->private_data;
1954                 seq->private = inode->i_private;  /* sdp */
1955         }
1956         return ret;
1957 }
1958 
1959 static const struct file_operations gfs2_glocks_fops = {
1960         .owner   = THIS_MODULE,
1961         .open    = gfs2_glocks_open,
1962         .read    = seq_read,
1963         .llseek  = seq_lseek,
1964         .release = gfs2_glocks_release,
1965 };
1966 
1967 static const struct file_operations gfs2_glstats_fops = {
1968         .owner   = THIS_MODULE,
1969         .open    = gfs2_glstats_open,
1970         .read    = seq_read,
1971         .llseek  = seq_lseek,
1972         .release = gfs2_glocks_release,
1973 };
1974 
1975 static const struct file_operations gfs2_sbstats_fops = {
1976         .owner   = THIS_MODULE,
1977         .open    = gfs2_sbstats_open,
1978         .read    = seq_read,
1979         .llseek  = seq_lseek,
1980         .release = seq_release,
1981 };
1982 
1983 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
1984 {
1985         struct dentry *dent;
1986 
1987         dent = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
1988         if (IS_ERR_OR_NULL(dent))
1989                 goto fail;
1990         sdp->debugfs_dir = dent;
1991 
1992         dent = debugfs_create_file("glocks",
1993                                    S_IFREG | S_IRUGO,
1994                                    sdp->debugfs_dir, sdp,
1995                                    &gfs2_glocks_fops);
1996         if (IS_ERR_OR_NULL(dent))
1997                 goto fail;
1998         sdp->debugfs_dentry_glocks = dent;
1999 
2000         dent = debugfs_create_file("glstats",
2001                                    S_IFREG | S_IRUGO,
2002                                    sdp->debugfs_dir, sdp,
2003                                    &gfs2_glstats_fops);
2004         if (IS_ERR_OR_NULL(dent))
2005                 goto fail;
2006         sdp->debugfs_dentry_glstats = dent;
2007 
2008         dent = debugfs_create_file("sbstats",
2009                                    S_IFREG | S_IRUGO,
2010                                    sdp->debugfs_dir, sdp,
2011                                    &gfs2_sbstats_fops);
2012         if (IS_ERR_OR_NULL(dent))
2013                 goto fail;
2014         sdp->debugfs_dentry_sbstats = dent;
2015 
2016         return 0;
2017 fail:
2018         gfs2_delete_debugfs_file(sdp);
2019         return dent ? PTR_ERR(dent) : -ENOMEM;
2020 }
2021 
2022 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
2023 {
2024         if (sdp->debugfs_dir) {
2025                 if (sdp->debugfs_dentry_glocks) {
2026                         debugfs_remove(sdp->debugfs_dentry_glocks);
2027                         sdp->debugfs_dentry_glocks = NULL;
2028                 }
2029                 if (sdp->debugfs_dentry_glstats) {
2030                         debugfs_remove(sdp->debugfs_dentry_glstats);
2031                         sdp->debugfs_dentry_glstats = NULL;
2032                 }
2033                 if (sdp->debugfs_dentry_sbstats) {
2034                         debugfs_remove(sdp->debugfs_dentry_sbstats);
2035                         sdp->debugfs_dentry_sbstats = NULL;
2036                 }
2037                 debugfs_remove(sdp->debugfs_dir);
2038                 sdp->debugfs_dir = NULL;
2039         }
2040 }
2041 
2042 int gfs2_register_debugfs(void)
2043 {
2044         gfs2_root = debugfs_create_dir("gfs2", NULL);
2045         if (IS_ERR(gfs2_root))
2046                 return PTR_ERR(gfs2_root);
2047         return gfs2_root ? 0 : -ENOMEM;
2048 }
2049 
2050 void gfs2_unregister_debugfs(void)
2051 {
2052         debugfs_remove(gfs2_root);
2053         gfs2_root = NULL;
2054 }
2055 

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