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

Version: ~ [ linux-5.6-rc1 ] ~ [ linux-5.5.2 ] ~ [ linux-5.4.17 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.102 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.170 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.213 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.213 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.81 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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         if (new_state != gl->gl_target)
413                 /* shorten our minimum hold time */
414                 gl->gl_hold_time = max(gl->gl_hold_time - GL_GLOCK_HOLD_DECR,
415                                        GL_GLOCK_MIN_HOLD);
416         gl->gl_state = new_state;
417         gl->gl_tchange = jiffies;
418 }
419 
420 static void gfs2_demote_wake(struct gfs2_glock *gl)
421 {
422         gl->gl_demote_state = LM_ST_EXCLUSIVE;
423         clear_bit(GLF_DEMOTE, &gl->gl_flags);
424         smp_mb__after_clear_bit();
425         wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
426 }
427 
428 /**
429  * finish_xmote - The DLM has replied to one of our lock requests
430  * @gl: The glock
431  * @ret: The status from the DLM
432  *
433  */
434 
435 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
436 {
437         const struct gfs2_glock_operations *glops = gl->gl_ops;
438         struct gfs2_holder *gh;
439         unsigned state = ret & LM_OUT_ST_MASK;
440         int rv;
441 
442         spin_lock(&gl->gl_spin);
443         trace_gfs2_glock_state_change(gl, state);
444         state_change(gl, state);
445         gh = find_first_waiter(gl);
446 
447         /* Demote to UN request arrived during demote to SH or DF */
448         if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
449             state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
450                 gl->gl_target = LM_ST_UNLOCKED;
451 
452         /* Check for state != intended state */
453         if (unlikely(state != gl->gl_target)) {
454                 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
455                         /* move to back of queue and try next entry */
456                         if (ret & LM_OUT_CANCELED) {
457                                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
458                                         list_move_tail(&gh->gh_list, &gl->gl_holders);
459                                 gh = find_first_waiter(gl);
460                                 gl->gl_target = gh->gh_state;
461                                 goto retry;
462                         }
463                         /* Some error or failed "try lock" - report it */
464                         if ((ret & LM_OUT_ERROR) ||
465                             (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
466                                 gl->gl_target = gl->gl_state;
467                                 do_error(gl, ret);
468                                 goto out;
469                         }
470                 }
471                 switch(state) {
472                 /* Unlocked due to conversion deadlock, try again */
473                 case LM_ST_UNLOCKED:
474 retry:
475                         do_xmote(gl, gh, gl->gl_target);
476                         break;
477                 /* Conversion fails, unlock and try again */
478                 case LM_ST_SHARED:
479                 case LM_ST_DEFERRED:
480                         do_xmote(gl, gh, LM_ST_UNLOCKED);
481                         break;
482                 default: /* Everything else */
483                         printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
484                         GLOCK_BUG_ON(gl, 1);
485                 }
486                 spin_unlock(&gl->gl_spin);
487                 return;
488         }
489 
490         /* Fast path - we got what we asked for */
491         if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
492                 gfs2_demote_wake(gl);
493         if (state != LM_ST_UNLOCKED) {
494                 if (glops->go_xmote_bh) {
495                         spin_unlock(&gl->gl_spin);
496                         rv = glops->go_xmote_bh(gl, gh);
497                         spin_lock(&gl->gl_spin);
498                         if (rv) {
499                                 do_error(gl, rv);
500                                 goto out;
501                         }
502                 }
503                 rv = do_promote(gl);
504                 if (rv == 2)
505                         goto out_locked;
506         }
507 out:
508         clear_bit(GLF_LOCK, &gl->gl_flags);
509 out_locked:
510         spin_unlock(&gl->gl_spin);
511 }
512 
513 /**
514  * do_xmote - Calls the DLM to change the state of a lock
515  * @gl: The lock state
516  * @gh: The holder (only for promotes)
517  * @target: The target lock state
518  *
519  */
520 
521 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
522 __releases(&gl->gl_spin)
523 __acquires(&gl->gl_spin)
524 {
525         const struct gfs2_glock_operations *glops = gl->gl_ops;
526         struct gfs2_sbd *sdp = gl->gl_sbd;
527         unsigned int lck_flags = gh ? gh->gh_flags : 0;
528         int ret;
529 
530         lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
531                       LM_FLAG_PRIORITY);
532         GLOCK_BUG_ON(gl, gl->gl_state == target);
533         GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
534         if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
535             glops->go_inval) {
536                 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
537                 do_error(gl, 0); /* Fail queued try locks */
538         }
539         gl->gl_req = target;
540         spin_unlock(&gl->gl_spin);
541         if (glops->go_xmote_th)
542                 glops->go_xmote_th(gl);
543         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
544                 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
545         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
546 
547         gfs2_glock_hold(gl);
548         if (sdp->sd_lockstruct.ls_ops->lm_lock) {
549                 /* lock_dlm */
550                 ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
551                 GLOCK_BUG_ON(gl, ret);
552         } else { /* lock_nolock */
553                 finish_xmote(gl, target);
554                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
555                         gfs2_glock_put(gl);
556         }
557 
558         spin_lock(&gl->gl_spin);
559 }
560 
561 /**
562  * find_first_holder - find the first "holder" gh
563  * @gl: the glock
564  */
565 
566 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
567 {
568         struct gfs2_holder *gh;
569 
570         if (!list_empty(&gl->gl_holders)) {
571                 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
572                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
573                         return gh;
574         }
575         return NULL;
576 }
577 
578 /**
579  * run_queue - do all outstanding tasks related to a glock
580  * @gl: The glock in question
581  * @nonblock: True if we must not block in run_queue
582  *
583  */
584 
585 static void run_queue(struct gfs2_glock *gl, const int nonblock)
586 __releases(&gl->gl_spin)
587 __acquires(&gl->gl_spin)
588 {
589         struct gfs2_holder *gh = NULL;
590         int ret;
591 
592         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
593                 return;
594 
595         GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
596 
597         if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
598             gl->gl_demote_state != gl->gl_state) {
599                 if (find_first_holder(gl))
600                         goto out_unlock;
601                 if (nonblock)
602                         goto out_sched;
603                 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
604                 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
605                 gl->gl_target = gl->gl_demote_state;
606         } else {
607                 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
608                         gfs2_demote_wake(gl);
609                 ret = do_promote(gl);
610                 if (ret == 0)
611                         goto out_unlock;
612                 if (ret == 2)
613                         goto out;
614                 gh = find_first_waiter(gl);
615                 gl->gl_target = gh->gh_state;
616                 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
617                         do_error(gl, 0); /* Fail queued try locks */
618         }
619         do_xmote(gl, gh, gl->gl_target);
620 out:
621         return;
622 
623 out_sched:
624         clear_bit(GLF_LOCK, &gl->gl_flags);
625         smp_mb__after_clear_bit();
626         gfs2_glock_hold(gl);
627         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
628                 gfs2_glock_put_nolock(gl);
629         return;
630 
631 out_unlock:
632         clear_bit(GLF_LOCK, &gl->gl_flags);
633         smp_mb__after_clear_bit();
634         return;
635 }
636 
637 static void delete_work_func(struct work_struct *work)
638 {
639         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
640         struct gfs2_sbd *sdp = gl->gl_sbd;
641         struct gfs2_inode *ip;
642         struct inode *inode;
643         u64 no_addr = gl->gl_name.ln_number;
644 
645         ip = gl->gl_object;
646         /* Note: Unsafe to dereference ip as we don't hold right refs/locks */
647 
648         if (ip)
649                 inode = gfs2_ilookup(sdp->sd_vfs, no_addr, 1);
650         else
651                 inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
652         if (inode && !IS_ERR(inode)) {
653                 d_prune_aliases(inode);
654                 iput(inode);
655         }
656         gfs2_glock_put(gl);
657 }
658 
659 static void glock_work_func(struct work_struct *work)
660 {
661         unsigned long delay = 0;
662         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
663         int drop_ref = 0;
664 
665         if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
666                 finish_xmote(gl, gl->gl_reply);
667                 drop_ref = 1;
668         }
669         spin_lock(&gl->gl_spin);
670         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
671             gl->gl_state != LM_ST_UNLOCKED &&
672             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
673                 unsigned long holdtime, now = jiffies;
674 
675                 holdtime = gl->gl_tchange + gl->gl_hold_time;
676                 if (time_before(now, holdtime))
677                         delay = holdtime - now;
678 
679                 if (!delay) {
680                         clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
681                         set_bit(GLF_DEMOTE, &gl->gl_flags);
682                 }
683         }
684         run_queue(gl, 0);
685         spin_unlock(&gl->gl_spin);
686         if (!delay)
687                 gfs2_glock_put(gl);
688         else {
689                 if (gl->gl_name.ln_type != LM_TYPE_INODE)
690                         delay = 0;
691                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
692                         gfs2_glock_put(gl);
693         }
694         if (drop_ref)
695                 gfs2_glock_put(gl);
696 }
697 
698 /**
699  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
700  * @sdp: The GFS2 superblock
701  * @number: the lock number
702  * @glops: The glock_operations to use
703  * @create: If 0, don't create the glock if it doesn't exist
704  * @glp: the glock is returned here
705  *
706  * This does not lock a glock, just finds/creates structures for one.
707  *
708  * Returns: errno
709  */
710 
711 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
712                    const struct gfs2_glock_operations *glops, int create,
713                    struct gfs2_glock **glp)
714 {
715         struct super_block *s = sdp->sd_vfs;
716         struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
717         struct gfs2_glock *gl, *tmp;
718         unsigned int hash = gl_hash(sdp, &name);
719         struct address_space *mapping;
720         struct kmem_cache *cachep;
721 
722         rcu_read_lock();
723         gl = search_bucket(hash, sdp, &name);
724         rcu_read_unlock();
725 
726         *glp = gl;
727         if (gl)
728                 return 0;
729         if (!create)
730                 return -ENOENT;
731 
732         if (glops->go_flags & GLOF_ASPACE)
733                 cachep = gfs2_glock_aspace_cachep;
734         else
735                 cachep = gfs2_glock_cachep;
736         gl = kmem_cache_alloc(cachep, GFP_KERNEL);
737         if (!gl)
738                 return -ENOMEM;
739 
740         atomic_inc(&sdp->sd_glock_disposal);
741         gl->gl_flags = 0;
742         gl->gl_name = name;
743         atomic_set(&gl->gl_ref, 1);
744         gl->gl_state = LM_ST_UNLOCKED;
745         gl->gl_target = LM_ST_UNLOCKED;
746         gl->gl_demote_state = LM_ST_EXCLUSIVE;
747         gl->gl_hash = hash;
748         gl->gl_ops = glops;
749         snprintf(gl->gl_strname, GDLM_STRNAME_BYTES, "%8x%16llx", name.ln_type, (unsigned long long)number);
750         memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
751         gl->gl_lksb.sb_lvbptr = gl->gl_lvb;
752         gl->gl_tchange = jiffies;
753         gl->gl_object = NULL;
754         gl->gl_sbd = sdp;
755         gl->gl_hold_time = GL_GLOCK_DFT_HOLD;
756         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
757         INIT_WORK(&gl->gl_delete, delete_work_func);
758 
759         mapping = gfs2_glock2aspace(gl);
760         if (mapping) {
761                 mapping->a_ops = &gfs2_meta_aops;
762                 mapping->host = s->s_bdev->bd_inode;
763                 mapping->flags = 0;
764                 mapping_set_gfp_mask(mapping, GFP_NOFS);
765                 mapping->assoc_mapping = NULL;
766                 mapping->backing_dev_info = s->s_bdi;
767                 mapping->writeback_index = 0;
768         }
769 
770         spin_lock_bucket(hash);
771         tmp = search_bucket(hash, sdp, &name);
772         if (tmp) {
773                 spin_unlock_bucket(hash);
774                 kmem_cache_free(cachep, gl);
775                 atomic_dec(&sdp->sd_glock_disposal);
776                 gl = tmp;
777         } else {
778                 hlist_bl_add_head_rcu(&gl->gl_list, &gl_hash_table[hash]);
779                 spin_unlock_bucket(hash);
780         }
781 
782         *glp = gl;
783 
784         return 0;
785 }
786 
787 /**
788  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
789  * @gl: the glock
790  * @state: the state we're requesting
791  * @flags: the modifier flags
792  * @gh: the holder structure
793  *
794  */
795 
796 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
797                       struct gfs2_holder *gh)
798 {
799         INIT_LIST_HEAD(&gh->gh_list);
800         gh->gh_gl = gl;
801         gh->gh_ip = (unsigned long)__builtin_return_address(0);
802         gh->gh_owner_pid = get_pid(task_pid(current));
803         gh->gh_state = state;
804         gh->gh_flags = flags;
805         gh->gh_error = 0;
806         gh->gh_iflags = 0;
807         gfs2_glock_hold(gl);
808 }
809 
810 /**
811  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
812  * @state: the state we're requesting
813  * @flags: the modifier flags
814  * @gh: the holder structure
815  *
816  * Don't mess with the glock.
817  *
818  */
819 
820 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
821 {
822         gh->gh_state = state;
823         gh->gh_flags = flags;
824         gh->gh_iflags = 0;
825         gh->gh_ip = (unsigned long)__builtin_return_address(0);
826         if (gh->gh_owner_pid)
827                 put_pid(gh->gh_owner_pid);
828         gh->gh_owner_pid = get_pid(task_pid(current));
829 }
830 
831 /**
832  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
833  * @gh: the holder structure
834  *
835  */
836 
837 void gfs2_holder_uninit(struct gfs2_holder *gh)
838 {
839         put_pid(gh->gh_owner_pid);
840         gfs2_glock_put(gh->gh_gl);
841         gh->gh_gl = NULL;
842         gh->gh_ip = 0;
843 }
844 
845 /**
846  * gfs2_glock_holder_wait
847  * @word: unused
848  *
849  * This function and gfs2_glock_demote_wait both show up in the WCHAN
850  * field. Thus I've separated these otherwise identical functions in
851  * order to be more informative to the user.
852  */
853 
854 static int gfs2_glock_holder_wait(void *word)
855 {
856         schedule();
857         return 0;
858 }
859 
860 static int gfs2_glock_demote_wait(void *word)
861 {
862         schedule();
863         return 0;
864 }
865 
866 static void wait_on_holder(struct gfs2_holder *gh)
867 {
868         unsigned long time1 = jiffies;
869 
870         might_sleep();
871         wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
872         if (time_after(jiffies, time1 + HZ)) /* have we waited > a second? */
873                 /* Lengthen the minimum hold time. */
874                 gh->gh_gl->gl_hold_time = min(gh->gh_gl->gl_hold_time +
875                                               GL_GLOCK_HOLD_INCR,
876                                               GL_GLOCK_MAX_HOLD);
877 }
878 
879 static void wait_on_demote(struct gfs2_glock *gl)
880 {
881         might_sleep();
882         wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
883 }
884 
885 /**
886  * handle_callback - process a demote request
887  * @gl: the glock
888  * @state: the state the caller wants us to change to
889  *
890  * There are only two requests that we are going to see in actual
891  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
892  */
893 
894 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
895                             unsigned long delay)
896 {
897         int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
898 
899         set_bit(bit, &gl->gl_flags);
900         if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
901                 gl->gl_demote_state = state;
902                 gl->gl_demote_time = jiffies;
903         } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
904                         gl->gl_demote_state != state) {
905                 gl->gl_demote_state = LM_ST_UNLOCKED;
906         }
907         if (gl->gl_ops->go_callback)
908                 gl->gl_ops->go_callback(gl);
909         trace_gfs2_demote_rq(gl);
910 }
911 
912 /**
913  * gfs2_glock_wait - wait on a glock acquisition
914  * @gh: the glock holder
915  *
916  * Returns: 0 on success
917  */
918 
919 int gfs2_glock_wait(struct gfs2_holder *gh)
920 {
921         wait_on_holder(gh);
922         return gh->gh_error;
923 }
924 
925 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
926 {
927         struct va_format vaf;
928         va_list args;
929 
930         va_start(args, fmt);
931 
932         if (seq) {
933                 struct gfs2_glock_iter *gi = seq->private;
934                 vsprintf(gi->string, fmt, args);
935                 seq_printf(seq, gi->string);
936         } else {
937                 vaf.fmt = fmt;
938                 vaf.va = &args;
939 
940                 printk(KERN_ERR " %pV", &vaf);
941         }
942 
943         va_end(args);
944 }
945 
946 /**
947  * add_to_queue - Add a holder to the wait queue (but look for recursion)
948  * @gh: the holder structure to add
949  *
950  * Eventually we should move the recursive locking trap to a
951  * debugging option or something like that. This is the fast
952  * path and needs to have the minimum number of distractions.
953  * 
954  */
955 
956 static inline void add_to_queue(struct gfs2_holder *gh)
957 __releases(&gl->gl_spin)
958 __acquires(&gl->gl_spin)
959 {
960         struct gfs2_glock *gl = gh->gh_gl;
961         struct gfs2_sbd *sdp = gl->gl_sbd;
962         struct list_head *insert_pt = NULL;
963         struct gfs2_holder *gh2;
964         int try_lock = 0;
965 
966         BUG_ON(gh->gh_owner_pid == NULL);
967         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
968                 BUG();
969 
970         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
971                 if (test_bit(GLF_LOCK, &gl->gl_flags))
972                         try_lock = 1;
973                 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
974                         goto fail;
975         }
976 
977         list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
978                 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
979                     (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
980                         goto trap_recursive;
981                 if (try_lock &&
982                     !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
983                     !may_grant(gl, gh)) {
984 fail:
985                         gh->gh_error = GLR_TRYFAILED;
986                         gfs2_holder_wake(gh);
987                         return;
988                 }
989                 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
990                         continue;
991                 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
992                         insert_pt = &gh2->gh_list;
993         }
994         set_bit(GLF_QUEUED, &gl->gl_flags);
995         trace_gfs2_glock_queue(gh, 1);
996         if (likely(insert_pt == NULL)) {
997                 list_add_tail(&gh->gh_list, &gl->gl_holders);
998                 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
999                         goto do_cancel;
1000                 return;
1001         }
1002         list_add_tail(&gh->gh_list, insert_pt);
1003 do_cancel:
1004         gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
1005         if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
1006                 spin_unlock(&gl->gl_spin);
1007                 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
1008                         sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
1009                 spin_lock(&gl->gl_spin);
1010         }
1011         return;
1012 
1013 trap_recursive:
1014         print_symbol(KERN_ERR "original: %s\n", gh2->gh_ip);
1015         printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
1016         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1017                gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
1018         print_symbol(KERN_ERR "new: %s\n", gh->gh_ip);
1019         printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
1020         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1021                gh->gh_gl->gl_name.ln_type, gh->gh_state);
1022         __dump_glock(NULL, gl);
1023         BUG();
1024 }
1025 
1026 /**
1027  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1028  * @gh: the holder structure
1029  *
1030  * if (gh->gh_flags & GL_ASYNC), this never returns an error
1031  *
1032  * Returns: 0, GLR_TRYFAILED, or errno on failure
1033  */
1034 
1035 int gfs2_glock_nq(struct gfs2_holder *gh)
1036 {
1037         struct gfs2_glock *gl = gh->gh_gl;
1038         struct gfs2_sbd *sdp = gl->gl_sbd;
1039         int error = 0;
1040 
1041         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
1042                 return -EIO;
1043 
1044         if (test_bit(GLF_LRU, &gl->gl_flags))
1045                 gfs2_glock_remove_from_lru(gl);
1046 
1047         spin_lock(&gl->gl_spin);
1048         add_to_queue(gh);
1049         if ((LM_FLAG_NOEXP & gh->gh_flags) &&
1050             test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1051                 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1052         run_queue(gl, 1);
1053         spin_unlock(&gl->gl_spin);
1054 
1055         if (!(gh->gh_flags & GL_ASYNC))
1056                 error = gfs2_glock_wait(gh);
1057 
1058         return error;
1059 }
1060 
1061 /**
1062  * gfs2_glock_poll - poll to see if an async request has been completed
1063  * @gh: the holder
1064  *
1065  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1066  */
1067 
1068 int gfs2_glock_poll(struct gfs2_holder *gh)
1069 {
1070         return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1071 }
1072 
1073 /**
1074  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1075  * @gh: the glock holder
1076  *
1077  */
1078 
1079 void gfs2_glock_dq(struct gfs2_holder *gh)
1080 {
1081         struct gfs2_glock *gl = gh->gh_gl;
1082         const struct gfs2_glock_operations *glops = gl->gl_ops;
1083         unsigned delay = 0;
1084         int fast_path = 0;
1085 
1086         spin_lock(&gl->gl_spin);
1087         if (gh->gh_flags & GL_NOCACHE)
1088                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1089 
1090         list_del_init(&gh->gh_list);
1091         if (find_first_holder(gl) == NULL) {
1092                 if (glops->go_unlock) {
1093                         GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1094                         spin_unlock(&gl->gl_spin);
1095                         glops->go_unlock(gh);
1096                         spin_lock(&gl->gl_spin);
1097                         clear_bit(GLF_LOCK, &gl->gl_flags);
1098                 }
1099                 if (list_empty(&gl->gl_holders) &&
1100                     !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1101                     !test_bit(GLF_DEMOTE, &gl->gl_flags))
1102                         fast_path = 1;
1103         }
1104         if (!test_bit(GLF_LFLUSH, &gl->gl_flags))
1105                 __gfs2_glock_schedule_for_reclaim(gl);
1106         trace_gfs2_glock_queue(gh, 0);
1107         spin_unlock(&gl->gl_spin);
1108         if (likely(fast_path))
1109                 return;
1110 
1111         gfs2_glock_hold(gl);
1112         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1113             !test_bit(GLF_DEMOTE, &gl->gl_flags) &&
1114             gl->gl_name.ln_type == LM_TYPE_INODE)
1115                 delay = gl->gl_hold_time;
1116         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1117                 gfs2_glock_put(gl);
1118 }
1119 
1120 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1121 {
1122         struct gfs2_glock *gl = gh->gh_gl;
1123         gfs2_glock_dq(gh);
1124         wait_on_demote(gl);
1125 }
1126 
1127 /**
1128  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1129  * @gh: the holder structure
1130  *
1131  */
1132 
1133 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1134 {
1135         gfs2_glock_dq(gh);
1136         gfs2_holder_uninit(gh);
1137 }
1138 
1139 /**
1140  * gfs2_glock_nq_num - acquire a glock based on lock number
1141  * @sdp: the filesystem
1142  * @number: the lock number
1143  * @glops: the glock operations for the type of glock
1144  * @state: the state to acquire the glock in
1145  * @flags: modifier flags for the acquisition
1146  * @gh: the struct gfs2_holder
1147  *
1148  * Returns: errno
1149  */
1150 
1151 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1152                       const struct gfs2_glock_operations *glops,
1153                       unsigned int state, int flags, struct gfs2_holder *gh)
1154 {
1155         struct gfs2_glock *gl;
1156         int error;
1157 
1158         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1159         if (!error) {
1160                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1161                 gfs2_glock_put(gl);
1162         }
1163 
1164         return error;
1165 }
1166 
1167 /**
1168  * glock_compare - Compare two struct gfs2_glock structures for sorting
1169  * @arg_a: the first structure
1170  * @arg_b: the second structure
1171  *
1172  */
1173 
1174 static int glock_compare(const void *arg_a, const void *arg_b)
1175 {
1176         const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1177         const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1178         const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1179         const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1180 
1181         if (a->ln_number > b->ln_number)
1182                 return 1;
1183         if (a->ln_number < b->ln_number)
1184                 return -1;
1185         BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1186         return 0;
1187 }
1188 
1189 /**
1190  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1191  * @num_gh: the number of structures
1192  * @ghs: an array of struct gfs2_holder structures
1193  *
1194  * Returns: 0 on success (all glocks acquired),
1195  *          errno on failure (no glocks acquired)
1196  */
1197 
1198 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1199                      struct gfs2_holder **p)
1200 {
1201         unsigned int x;
1202         int error = 0;
1203 
1204         for (x = 0; x < num_gh; x++)
1205                 p[x] = &ghs[x];
1206 
1207         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1208 
1209         for (x = 0; x < num_gh; x++) {
1210                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1211 
1212                 error = gfs2_glock_nq(p[x]);
1213                 if (error) {
1214                         while (x--)
1215                                 gfs2_glock_dq(p[x]);
1216                         break;
1217                 }
1218         }
1219 
1220         return error;
1221 }
1222 
1223 /**
1224  * gfs2_glock_nq_m - acquire multiple glocks
1225  * @num_gh: the number of structures
1226  * @ghs: an array of struct gfs2_holder structures
1227  *
1228  *
1229  * Returns: 0 on success (all glocks acquired),
1230  *          errno on failure (no glocks acquired)
1231  */
1232 
1233 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1234 {
1235         struct gfs2_holder *tmp[4];
1236         struct gfs2_holder **pph = tmp;
1237         int error = 0;
1238 
1239         switch(num_gh) {
1240         case 0:
1241                 return 0;
1242         case 1:
1243                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1244                 return gfs2_glock_nq(ghs);
1245         default:
1246                 if (num_gh <= 4)
1247                         break;
1248                 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1249                 if (!pph)
1250                         return -ENOMEM;
1251         }
1252 
1253         error = nq_m_sync(num_gh, ghs, pph);
1254 
1255         if (pph != tmp)
1256                 kfree(pph);
1257 
1258         return error;
1259 }
1260 
1261 /**
1262  * gfs2_glock_dq_m - release multiple glocks
1263  * @num_gh: the number of structures
1264  * @ghs: an array of struct gfs2_holder structures
1265  *
1266  */
1267 
1268 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1269 {
1270         while (num_gh--)
1271                 gfs2_glock_dq(&ghs[num_gh]);
1272 }
1273 
1274 /**
1275  * gfs2_glock_dq_uninit_m - release multiple glocks
1276  * @num_gh: the number of structures
1277  * @ghs: an array of struct gfs2_holder structures
1278  *
1279  */
1280 
1281 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1282 {
1283         while (num_gh--)
1284                 gfs2_glock_dq_uninit(&ghs[num_gh]);
1285 }
1286 
1287 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1288 {
1289         unsigned long delay = 0;
1290         unsigned long holdtime;
1291         unsigned long now = jiffies;
1292 
1293         gfs2_glock_hold(gl);
1294         holdtime = gl->gl_tchange + gl->gl_hold_time;
1295         if (test_bit(GLF_QUEUED, &gl->gl_flags) &&
1296             gl->gl_name.ln_type == LM_TYPE_INODE) {
1297                 if (time_before(now, holdtime))
1298                         delay = holdtime - now;
1299                 if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1300                         delay = gl->gl_hold_time;
1301         }
1302 
1303         spin_lock(&gl->gl_spin);
1304         handle_callback(gl, state, delay);
1305         spin_unlock(&gl->gl_spin);
1306         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1307                 gfs2_glock_put(gl);
1308 }
1309 
1310 /**
1311  * gfs2_should_freeze - Figure out if glock should be frozen
1312  * @gl: The glock in question
1313  *
1314  * Glocks are not frozen if (a) the result of the dlm operation is
1315  * an error, (b) the locking operation was an unlock operation or
1316  * (c) if there is a "noexp" flagged request anywhere in the queue
1317  *
1318  * Returns: 1 if freezing should occur, 0 otherwise
1319  */
1320 
1321 static int gfs2_should_freeze(const struct gfs2_glock *gl)
1322 {
1323         const struct gfs2_holder *gh;
1324 
1325         if (gl->gl_reply & ~LM_OUT_ST_MASK)
1326                 return 0;
1327         if (gl->gl_target == LM_ST_UNLOCKED)
1328                 return 0;
1329 
1330         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1331                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1332                         continue;
1333                 if (LM_FLAG_NOEXP & gh->gh_flags)
1334                         return 0;
1335         }
1336 
1337         return 1;
1338 }
1339 
1340 /**
1341  * gfs2_glock_complete - Callback used by locking
1342  * @gl: Pointer to the glock
1343  * @ret: The return value from the dlm
1344  *
1345  * The gl_reply field is under the gl_spin lock so that it is ok
1346  * to use a bitfield shared with other glock state fields.
1347  */
1348 
1349 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1350 {
1351         struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
1352 
1353         spin_lock(&gl->gl_spin);
1354         gl->gl_reply = ret;
1355 
1356         if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_flags))) {
1357                 if (gfs2_should_freeze(gl)) {
1358                         set_bit(GLF_FROZEN, &gl->gl_flags);
1359                         spin_unlock(&gl->gl_spin);
1360                         return;
1361                 }
1362         }
1363 
1364         spin_unlock(&gl->gl_spin);
1365         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1366         smp_wmb();
1367         gfs2_glock_hold(gl);
1368         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1369                 gfs2_glock_put(gl);
1370 }
1371 
1372 
1373 static int gfs2_shrink_glock_memory(struct shrinker *shrink,
1374                                     struct shrink_control *sc)
1375 {
1376         struct gfs2_glock *gl;
1377         int may_demote;
1378         int nr_skipped = 0;
1379         int nr = sc->nr_to_scan;
1380         gfp_t gfp_mask = sc->gfp_mask;
1381         LIST_HEAD(skipped);
1382 
1383         if (nr == 0)
1384                 goto out;
1385 
1386         if (!(gfp_mask & __GFP_FS))
1387                 return -1;
1388 
1389         spin_lock(&lru_lock);
1390         while(nr && !list_empty(&lru_list)) {
1391                 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1392                 list_del_init(&gl->gl_lru);
1393                 clear_bit(GLF_LRU, &gl->gl_flags);
1394                 atomic_dec(&lru_count);
1395 
1396                 /* Test for being demotable */
1397                 if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1398                         gfs2_glock_hold(gl);
1399                         spin_unlock(&lru_lock);
1400                         spin_lock(&gl->gl_spin);
1401                         may_demote = demote_ok(gl);
1402                         if (may_demote) {
1403                                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1404                                 nr--;
1405                         }
1406                         clear_bit(GLF_LOCK, &gl->gl_flags);
1407                         smp_mb__after_clear_bit();
1408                         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1409                                 gfs2_glock_put_nolock(gl);
1410                         spin_unlock(&gl->gl_spin);
1411                         spin_lock(&lru_lock);
1412                         continue;
1413                 }
1414                 nr_skipped++;
1415                 list_add(&gl->gl_lru, &skipped);
1416                 set_bit(GLF_LRU, &gl->gl_flags);
1417         }
1418         list_splice(&skipped, &lru_list);
1419         atomic_add(nr_skipped, &lru_count);
1420         spin_unlock(&lru_lock);
1421 out:
1422         return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
1423 }
1424 
1425 static struct shrinker glock_shrinker = {
1426         .shrink = gfs2_shrink_glock_memory,
1427         .seeks = DEFAULT_SEEKS,
1428 };
1429 
1430 /**
1431  * examine_bucket - Call a function for glock in a hash bucket
1432  * @examiner: the function
1433  * @sdp: the filesystem
1434  * @bucket: the bucket
1435  *
1436  */
1437 
1438 static void examine_bucket(glock_examiner examiner, const struct gfs2_sbd *sdp,
1439                           unsigned int hash)
1440 {
1441         struct gfs2_glock *gl;
1442         struct hlist_bl_head *head = &gl_hash_table[hash];
1443         struct hlist_bl_node *pos;
1444 
1445         rcu_read_lock();
1446         hlist_bl_for_each_entry_rcu(gl, pos, head, gl_list) {
1447                 if ((gl->gl_sbd == sdp) && atomic_read(&gl->gl_ref))
1448                         examiner(gl);
1449         }
1450         rcu_read_unlock();
1451         cond_resched();
1452 }
1453 
1454 static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
1455 {
1456         unsigned x;
1457 
1458         for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1459                 examine_bucket(examiner, sdp, x);
1460 }
1461 
1462 
1463 /**
1464  * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1465  * @gl: The glock to thaw
1466  *
1467  * N.B. When we freeze a glock, we leave a ref to the glock outstanding,
1468  * so this has to result in the ref count being dropped by one.
1469  */
1470 
1471 static void thaw_glock(struct gfs2_glock *gl)
1472 {
1473         if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1474                 return;
1475         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
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  * clear_glock - look at a glock and see if we can free it from glock cache
1483  * @gl: the glock to look at
1484  *
1485  */
1486 
1487 static void clear_glock(struct gfs2_glock *gl)
1488 {
1489         gfs2_glock_remove_from_lru(gl);
1490 
1491         spin_lock(&gl->gl_spin);
1492         if (gl->gl_state != LM_ST_UNLOCKED)
1493                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1494         spin_unlock(&gl->gl_spin);
1495         gfs2_glock_hold(gl);
1496         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1497                 gfs2_glock_put(gl);
1498 }
1499 
1500 /**
1501  * gfs2_glock_thaw - Thaw any frozen glocks
1502  * @sdp: The super block
1503  *
1504  */
1505 
1506 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1507 {
1508         glock_hash_walk(thaw_glock, sdp);
1509 }
1510 
1511 static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1512 {
1513         int ret;
1514         spin_lock(&gl->gl_spin);
1515         ret = __dump_glock(seq, gl);
1516         spin_unlock(&gl->gl_spin);
1517         return ret;
1518 }
1519 
1520 static void dump_glock_func(struct gfs2_glock *gl)
1521 {
1522         dump_glock(NULL, gl);
1523 }
1524 
1525 /**
1526  * gfs2_gl_hash_clear - Empty out the glock hash table
1527  * @sdp: the filesystem
1528  * @wait: wait until it's all gone
1529  *
1530  * Called when unmounting the filesystem.
1531  */
1532 
1533 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1534 {
1535         glock_hash_walk(clear_glock, sdp);
1536         flush_workqueue(glock_workqueue);
1537         wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
1538         glock_hash_walk(dump_glock_func, sdp);
1539 }
1540 
1541 void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1542 {
1543         struct gfs2_glock *gl = ip->i_gl;
1544         int ret;
1545 
1546         ret = gfs2_truncatei_resume(ip);
1547         gfs2_assert_withdraw(gl->gl_sbd, ret == 0);
1548 
1549         spin_lock(&gl->gl_spin);
1550         clear_bit(GLF_LOCK, &gl->gl_flags);
1551         run_queue(gl, 1);
1552         spin_unlock(&gl->gl_spin);
1553 }
1554 
1555 static const char *state2str(unsigned state)
1556 {
1557         switch(state) {
1558         case LM_ST_UNLOCKED:
1559                 return "UN";
1560         case LM_ST_SHARED:
1561                 return "SH";
1562         case LM_ST_DEFERRED:
1563                 return "DF";
1564         case LM_ST_EXCLUSIVE:
1565                 return "EX";
1566         }
1567         return "??";
1568 }
1569 
1570 static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags)
1571 {
1572         char *p = buf;
1573         if (flags & LM_FLAG_TRY)
1574                 *p++ = 't';
1575         if (flags & LM_FLAG_TRY_1CB)
1576                 *p++ = 'T';
1577         if (flags & LM_FLAG_NOEXP)
1578                 *p++ = 'e';
1579         if (flags & LM_FLAG_ANY)
1580                 *p++ = 'A';
1581         if (flags & LM_FLAG_PRIORITY)
1582                 *p++ = 'p';
1583         if (flags & GL_ASYNC)
1584                 *p++ = 'a';
1585         if (flags & GL_EXACT)
1586                 *p++ = 'E';
1587         if (flags & GL_NOCACHE)
1588                 *p++ = 'c';
1589         if (test_bit(HIF_HOLDER, &iflags))
1590                 *p++ = 'H';
1591         if (test_bit(HIF_WAIT, &iflags))
1592                 *p++ = 'W';
1593         if (test_bit(HIF_FIRST, &iflags))
1594                 *p++ = 'F';
1595         *p = 0;
1596         return buf;
1597 }
1598 
1599 /**
1600  * dump_holder - print information about a glock holder
1601  * @seq: the seq_file struct
1602  * @gh: the glock holder
1603  *
1604  * Returns: 0 on success, -ENOBUFS when we run out of space
1605  */
1606 
1607 static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1608 {
1609         struct task_struct *gh_owner = NULL;
1610         char flags_buf[32];
1611 
1612         if (gh->gh_owner_pid)
1613                 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1614         gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
1615                        state2str(gh->gh_state),
1616                        hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1617                        gh->gh_error,
1618                        gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1619                        gh_owner ? gh_owner->comm : "(ended)",
1620                        (void *)gh->gh_ip);
1621         return 0;
1622 }
1623 
1624 static const char *gflags2str(char *buf, const struct gfs2_glock *gl)
1625 {
1626         const unsigned long *gflags = &gl->gl_flags;
1627         char *p = buf;
1628 
1629         if (test_bit(GLF_LOCK, gflags))
1630                 *p++ = 'l';
1631         if (test_bit(GLF_DEMOTE, gflags))
1632                 *p++ = 'D';
1633         if (test_bit(GLF_PENDING_DEMOTE, gflags))
1634                 *p++ = 'd';
1635         if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1636                 *p++ = 'p';
1637         if (test_bit(GLF_DIRTY, gflags))
1638                 *p++ = 'y';
1639         if (test_bit(GLF_LFLUSH, gflags))
1640                 *p++ = 'f';
1641         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1642                 *p++ = 'i';
1643         if (test_bit(GLF_REPLY_PENDING, gflags))
1644                 *p++ = 'r';
1645         if (test_bit(GLF_INITIAL, gflags))
1646                 *p++ = 'I';
1647         if (test_bit(GLF_FROZEN, gflags))
1648                 *p++ = 'F';
1649         if (test_bit(GLF_QUEUED, gflags))
1650                 *p++ = 'q';
1651         if (test_bit(GLF_LRU, gflags))
1652                 *p++ = 'L';
1653         if (gl->gl_object)
1654                 *p++ = 'o';
1655         *p = 0;
1656         return buf;
1657 }
1658 
1659 /**
1660  * __dump_glock - print information about a glock
1661  * @seq: The seq_file struct
1662  * @gl: the glock
1663  *
1664  * The file format is as follows:
1665  * One line per object, capital letters are used to indicate objects
1666  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1667  * other objects are indented by a single space and follow the glock to
1668  * which they are related. Fields are indicated by lower case letters
1669  * followed by a colon and the field value, except for strings which are in
1670  * [] so that its possible to see if they are composed of spaces for
1671  * example. The field's are n = number (id of the object), f = flags,
1672  * t = type, s = state, r = refcount, e = error, p = pid.
1673  *
1674  * Returns: 0 on success, -ENOBUFS when we run out of space
1675  */
1676 
1677 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1678 {
1679         const struct gfs2_glock_operations *glops = gl->gl_ops;
1680         unsigned long long dtime;
1681         const struct gfs2_holder *gh;
1682         char gflags_buf[32];
1683         int error = 0;
1684 
1685         dtime = jiffies - gl->gl_demote_time;
1686         dtime *= 1000000/HZ; /* demote time in uSec */
1687         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1688                 dtime = 0;
1689         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",
1690                   state2str(gl->gl_state),
1691                   gl->gl_name.ln_type,
1692                   (unsigned long long)gl->gl_name.ln_number,
1693                   gflags2str(gflags_buf, gl),
1694                   state2str(gl->gl_target),
1695                   state2str(gl->gl_demote_state), dtime,
1696                   atomic_read(&gl->gl_ail_count),
1697                   atomic_read(&gl->gl_revokes),
1698                   atomic_read(&gl->gl_ref), gl->gl_hold_time);
1699 
1700         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1701                 error = dump_holder(seq, gh);
1702                 if (error)
1703                         goto out;
1704         }
1705         if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1706                 error = glops->go_dump(seq, gl);
1707 out:
1708         return error;
1709 }
1710 
1711 
1712 
1713 
1714 int __init gfs2_glock_init(void)
1715 {
1716         unsigned i;
1717         for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
1718                 INIT_HLIST_BL_HEAD(&gl_hash_table[i]);
1719         }
1720 
1721         glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
1722                                           WQ_HIGHPRI | WQ_FREEZABLE, 0);
1723         if (IS_ERR(glock_workqueue))
1724                 return PTR_ERR(glock_workqueue);
1725         gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
1726                                                 WQ_MEM_RECLAIM | WQ_FREEZABLE,
1727                                                 0);
1728         if (IS_ERR(gfs2_delete_workqueue)) {
1729                 destroy_workqueue(glock_workqueue);
1730                 return PTR_ERR(gfs2_delete_workqueue);
1731         }
1732 
1733         register_shrinker(&glock_shrinker);
1734 
1735         return 0;
1736 }
1737 
1738 void gfs2_glock_exit(void)
1739 {
1740         unregister_shrinker(&glock_shrinker);
1741         destroy_workqueue(glock_workqueue);
1742         destroy_workqueue(gfs2_delete_workqueue);
1743 }
1744 
1745 static inline struct gfs2_glock *glock_hash_chain(unsigned hash)
1746 {
1747         return hlist_bl_entry(hlist_bl_first_rcu(&gl_hash_table[hash]),
1748                               struct gfs2_glock, gl_list);
1749 }
1750 
1751 static inline struct gfs2_glock *glock_hash_next(struct gfs2_glock *gl)
1752 {
1753         return hlist_bl_entry(rcu_dereference(gl->gl_list.next),
1754                               struct gfs2_glock, gl_list);
1755 }
1756 
1757 static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1758 {
1759         struct gfs2_glock *gl;
1760 
1761         do {
1762                 gl = gi->gl;
1763                 if (gl) {
1764                         gi->gl = glock_hash_next(gl);
1765                 } else {
1766                         gi->gl = glock_hash_chain(gi->hash);
1767                 }
1768                 while (gi->gl == NULL) {
1769                         gi->hash++;
1770                         if (gi->hash >= GFS2_GL_HASH_SIZE) {
1771                                 rcu_read_unlock();
1772                                 return 1;
1773                         }
1774                         gi->gl = glock_hash_chain(gi->hash);
1775                 }
1776         /* Skip entries for other sb and dead entries */
1777         } while (gi->sdp != gi->gl->gl_sbd || atomic_read(&gi->gl->gl_ref) == 0);
1778 
1779         return 0;
1780 }
1781 
1782 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1783 {
1784         struct gfs2_glock_iter *gi = seq->private;
1785         loff_t n = *pos;
1786 
1787         gi->hash = 0;
1788         rcu_read_lock();
1789 
1790         do {
1791                 if (gfs2_glock_iter_next(gi))
1792                         return NULL;
1793         } while (n--);
1794 
1795         return gi->gl;
1796 }
1797 
1798 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1799                                  loff_t *pos)
1800 {
1801         struct gfs2_glock_iter *gi = seq->private;
1802 
1803         (*pos)++;
1804 
1805         if (gfs2_glock_iter_next(gi))
1806                 return NULL;
1807 
1808         return gi->gl;
1809 }
1810 
1811 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1812 {
1813         struct gfs2_glock_iter *gi = seq->private;
1814 
1815         if (gi->gl)
1816                 rcu_read_unlock();
1817         gi->gl = NULL;
1818 }
1819 
1820 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1821 {
1822         return dump_glock(seq, iter_ptr);
1823 }
1824 
1825 static const struct seq_operations gfs2_glock_seq_ops = {
1826         .start = gfs2_glock_seq_start,
1827         .next  = gfs2_glock_seq_next,
1828         .stop  = gfs2_glock_seq_stop,
1829         .show  = gfs2_glock_seq_show,
1830 };
1831 
1832 static int gfs2_debugfs_open(struct inode *inode, struct file *file)
1833 {
1834         int ret = seq_open_private(file, &gfs2_glock_seq_ops,
1835                                    sizeof(struct gfs2_glock_iter));
1836         if (ret == 0) {
1837                 struct seq_file *seq = file->private_data;
1838                 struct gfs2_glock_iter *gi = seq->private;
1839                 gi->sdp = inode->i_private;
1840         }
1841         return ret;
1842 }
1843 
1844 static const struct file_operations gfs2_debug_fops = {
1845         .owner   = THIS_MODULE,
1846         .open    = gfs2_debugfs_open,
1847         .read    = seq_read,
1848         .llseek  = seq_lseek,
1849         .release = seq_release_private,
1850 };
1851 
1852 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
1853 {
1854         sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
1855         if (!sdp->debugfs_dir)
1856                 return -ENOMEM;
1857         sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
1858                                                          S_IFREG | S_IRUGO,
1859                                                          sdp->debugfs_dir, sdp,
1860                                                          &gfs2_debug_fops);
1861         if (!sdp->debugfs_dentry_glocks)
1862                 return -ENOMEM;
1863 
1864         return 0;
1865 }
1866 
1867 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
1868 {
1869         if (sdp && sdp->debugfs_dir) {
1870                 if (sdp->debugfs_dentry_glocks) {
1871                         debugfs_remove(sdp->debugfs_dentry_glocks);
1872                         sdp->debugfs_dentry_glocks = NULL;
1873                 }
1874                 debugfs_remove(sdp->debugfs_dir);
1875                 sdp->debugfs_dir = NULL;
1876         }
1877 }
1878 
1879 int gfs2_register_debugfs(void)
1880 {
1881         gfs2_root = debugfs_create_dir("gfs2", NULL);
1882         return gfs2_root ? 0 : -ENOMEM;
1883 }
1884 
1885 void gfs2_unregister_debugfs(void)
1886 {
1887         debugfs_remove(gfs2_root);
1888         gfs2_root = NULL;
1889 }
1890 

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