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

Version: ~ [ linux-5.11-rc3 ] ~ [ linux-5.10.7 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.89 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.167 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.215 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.251 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.251 ] ~ [ 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-3.16.85 ] ~ [ 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-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 #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 #include <linux/percpu.h>
 33 #include <linux/list_sort.h>
 34 #include <linux/lockref.h>
 35 
 36 #include "gfs2.h"
 37 #include "incore.h"
 38 #include "glock.h"
 39 #include "glops.h"
 40 #include "inode.h"
 41 #include "lops.h"
 42 #include "meta_io.h"
 43 #include "quota.h"
 44 #include "super.h"
 45 #include "util.h"
 46 #include "bmap.h"
 47 #define CREATE_TRACE_POINTS
 48 #include "trace_gfs2.h"
 49 
 50 struct gfs2_glock_iter {
 51         int hash;                       /* hash bucket index           */
 52         unsigned nhash;                 /* Index within current bucket */
 53         struct gfs2_sbd *sdp;           /* incore superblock           */
 54         struct gfs2_glock *gl;          /* current glock struct        */
 55         loff_t last_pos;                /* last position               */
 56 };
 57 
 58 typedef void (*glock_examiner) (struct gfs2_glock * gl);
 59 
 60 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
 61 
 62 static struct dentry *gfs2_root;
 63 static struct workqueue_struct *glock_workqueue;
 64 struct workqueue_struct *gfs2_delete_workqueue;
 65 static LIST_HEAD(lru_list);
 66 static atomic_t lru_count = ATOMIC_INIT(0);
 67 static DEFINE_SPINLOCK(lru_lock);
 68 
 69 #define GFS2_GL_HASH_SHIFT      15
 70 #define GFS2_GL_HASH_SIZE       (1 << GFS2_GL_HASH_SHIFT)
 71 #define GFS2_GL_HASH_MASK       (GFS2_GL_HASH_SIZE - 1)
 72 
 73 static struct hlist_bl_head gl_hash_table[GFS2_GL_HASH_SIZE];
 74 static struct dentry *gfs2_root;
 75 
 76 /**
 77  * gl_hash() - Turn glock number into hash bucket number
 78  * @lock: The glock number
 79  *
 80  * Returns: The number of the corresponding hash bucket
 81  */
 82 
 83 static unsigned int gl_hash(const struct gfs2_sbd *sdp,
 84                             const struct lm_lockname *name)
 85 {
 86         unsigned int h;
 87 
 88         h = jhash(&name->ln_number, sizeof(u64), 0);
 89         h = jhash(&name->ln_type, sizeof(unsigned int), h);
 90         h = jhash(&sdp, sizeof(struct gfs2_sbd *), h);
 91         h &= GFS2_GL_HASH_MASK;
 92 
 93         return h;
 94 }
 95 
 96 static inline void spin_lock_bucket(unsigned int hash)
 97 {
 98         hlist_bl_lock(&gl_hash_table[hash]);
 99 }
100 
101 static inline void spin_unlock_bucket(unsigned int hash)
102 {
103         hlist_bl_unlock(&gl_hash_table[hash]);
104 }
105 
106 static void gfs2_glock_dealloc(struct rcu_head *rcu)
107 {
108         struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu);
109 
110         if (gl->gl_ops->go_flags & GLOF_ASPACE) {
111                 kmem_cache_free(gfs2_glock_aspace_cachep, gl);
112         } else {
113                 kfree(gl->gl_lksb.sb_lvbptr);
114                 kmem_cache_free(gfs2_glock_cachep, gl);
115         }
116 }
117 
118 void gfs2_glock_free(struct gfs2_glock *gl)
119 {
120         struct gfs2_sbd *sdp = gl->gl_sbd;
121 
122         call_rcu(&gl->gl_rcu, gfs2_glock_dealloc);
123         if (atomic_dec_and_test(&sdp->sd_glock_disposal))
124                 wake_up(&sdp->sd_glock_wait);
125 }
126 
127 /**
128  * gfs2_glock_hold() - increment reference count on glock
129  * @gl: The glock to hold
130  *
131  */
132 
133 static void gfs2_glock_hold(struct gfs2_glock *gl)
134 {
135         GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
136         lockref_get(&gl->gl_lockref);
137 }
138 
139 /**
140  * demote_ok - Check to see if it's ok to unlock a glock
141  * @gl: the glock
142  *
143  * Returns: 1 if it's ok
144  */
145 
146 static int demote_ok(const struct gfs2_glock *gl)
147 {
148         const struct gfs2_glock_operations *glops = gl->gl_ops;
149 
150         if (gl->gl_state == LM_ST_UNLOCKED)
151                 return 0;
152         if (!list_empty(&gl->gl_holders))
153                 return 0;
154         if (glops->go_demote_ok)
155                 return glops->go_demote_ok(gl);
156         return 1;
157 }
158 
159 
160 void gfs2_glock_add_to_lru(struct gfs2_glock *gl)
161 {
162         spin_lock(&lru_lock);
163 
164         if (!list_empty(&gl->gl_lru))
165                 list_del_init(&gl->gl_lru);
166         else
167                 atomic_inc(&lru_count);
168 
169         list_add_tail(&gl->gl_lru, &lru_list);
170         set_bit(GLF_LRU, &gl->gl_flags);
171         spin_unlock(&lru_lock);
172 }
173 
174 static void __gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
175 {
176         if (!list_empty(&gl->gl_lru)) {
177                 list_del_init(&gl->gl_lru);
178                 atomic_dec(&lru_count);
179                 clear_bit(GLF_LRU, &gl->gl_flags);
180         }
181 }
182 
183 static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
184 {
185         spin_lock(&lru_lock);
186         __gfs2_glock_remove_from_lru(gl);
187         spin_unlock(&lru_lock);
188 }
189 
190 /**
191  * gfs2_glock_put() - Decrement reference count on glock
192  * @gl: The glock to put
193  *
194  */
195 
196 void gfs2_glock_put(struct gfs2_glock *gl)
197 {
198         struct gfs2_sbd *sdp = gl->gl_sbd;
199         struct address_space *mapping = gfs2_glock2aspace(gl);
200 
201         if (lockref_put_or_lock(&gl->gl_lockref))
202                 return;
203 
204         lockref_mark_dead(&gl->gl_lockref);
205 
206         spin_lock(&lru_lock);
207         __gfs2_glock_remove_from_lru(gl);
208         spin_unlock(&lru_lock);
209         spin_unlock(&gl->gl_lockref.lock);
210         spin_lock_bucket(gl->gl_hash);
211         hlist_bl_del_rcu(&gl->gl_list);
212         spin_unlock_bucket(gl->gl_hash);
213         GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
214         GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
215         trace_gfs2_glock_put(gl);
216         sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
217 }
218 
219 /**
220  * search_bucket() - Find struct gfs2_glock by lock number
221  * @bucket: the bucket to search
222  * @name: The lock name
223  *
224  * Returns: NULL, or the struct gfs2_glock with the requested number
225  */
226 
227 static struct gfs2_glock *search_bucket(unsigned int hash,
228                                         const struct gfs2_sbd *sdp,
229                                         const struct lm_lockname *name)
230 {
231         struct gfs2_glock *gl;
232         struct hlist_bl_node *h;
233 
234         hlist_bl_for_each_entry_rcu(gl, h, &gl_hash_table[hash], gl_list) {
235                 if (!lm_name_equal(&gl->gl_name, name))
236                         continue;
237                 if (gl->gl_sbd != sdp)
238                         continue;
239                 if (lockref_get_not_dead(&gl->gl_lockref))
240                         return gl;
241         }
242 
243         return NULL;
244 }
245 
246 /**
247  * may_grant - check if its ok to grant a new lock
248  * @gl: The glock
249  * @gh: The lock request which we wish to grant
250  *
251  * Returns: true if its ok to grant the lock
252  */
253 
254 static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
255 {
256         const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
257         if ((gh->gh_state == LM_ST_EXCLUSIVE ||
258              gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
259                 return 0;
260         if (gl->gl_state == gh->gh_state)
261                 return 1;
262         if (gh->gh_flags & GL_EXACT)
263                 return 0;
264         if (gl->gl_state == LM_ST_EXCLUSIVE) {
265                 if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
266                         return 1;
267                 if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
268                         return 1;
269         }
270         if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
271                 return 1;
272         return 0;
273 }
274 
275 static void gfs2_holder_wake(struct gfs2_holder *gh)
276 {
277         clear_bit(HIF_WAIT, &gh->gh_iflags);
278         smp_mb__after_clear_bit();
279         wake_up_bit(&gh->gh_iflags, HIF_WAIT);
280 }
281 
282 /**
283  * do_error - Something unexpected has happened during a lock request
284  *
285  */
286 
287 static inline void do_error(struct gfs2_glock *gl, const int ret)
288 {
289         struct gfs2_holder *gh, *tmp;
290 
291         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
292                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
293                         continue;
294                 if (ret & LM_OUT_ERROR)
295                         gh->gh_error = -EIO;
296                 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
297                         gh->gh_error = GLR_TRYFAILED;
298                 else
299                         continue;
300                 list_del_init(&gh->gh_list);
301                 trace_gfs2_glock_queue(gh, 0);
302                 gfs2_holder_wake(gh);
303         }
304 }
305 
306 /**
307  * do_promote - promote as many requests as possible on the current queue
308  * @gl: The glock
309  * 
310  * Returns: 1 if there is a blocked holder at the head of the list, or 2
311  *          if a type specific operation is underway.
312  */
313 
314 static int do_promote(struct gfs2_glock *gl)
315 __releases(&gl->gl_spin)
316 __acquires(&gl->gl_spin)
317 {
318         const struct gfs2_glock_operations *glops = gl->gl_ops;
319         struct gfs2_holder *gh, *tmp;
320         int ret;
321 
322 restart:
323         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
324                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
325                         continue;
326                 if (may_grant(gl, gh)) {
327                         if (gh->gh_list.prev == &gl->gl_holders &&
328                             glops->go_lock) {
329                                 spin_unlock(&gl->gl_spin);
330                                 /* FIXME: eliminate this eventually */
331                                 ret = glops->go_lock(gh);
332                                 spin_lock(&gl->gl_spin);
333                                 if (ret) {
334                                         if (ret == 1)
335                                                 return 2;
336                                         gh->gh_error = ret;
337                                         list_del_init(&gh->gh_list);
338                                         trace_gfs2_glock_queue(gh, 0);
339                                         gfs2_holder_wake(gh);
340                                         goto restart;
341                                 }
342                                 set_bit(HIF_HOLDER, &gh->gh_iflags);
343                                 trace_gfs2_promote(gh, 1);
344                                 gfs2_holder_wake(gh);
345                                 goto restart;
346                         }
347                         set_bit(HIF_HOLDER, &gh->gh_iflags);
348                         trace_gfs2_promote(gh, 0);
349                         gfs2_holder_wake(gh);
350                         continue;
351                 }
352                 if (gh->gh_list.prev == &gl->gl_holders)
353                         return 1;
354                 do_error(gl, 0);
355                 break;
356         }
357         return 0;
358 }
359 
360 /**
361  * find_first_waiter - find the first gh that's waiting for the glock
362  * @gl: the glock
363  */
364 
365 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
366 {
367         struct gfs2_holder *gh;
368 
369         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
370                 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
371                         return gh;
372         }
373         return NULL;
374 }
375 
376 /**
377  * state_change - record that the glock is now in a different state
378  * @gl: the glock
379  * @new_state the new state
380  *
381  */
382 
383 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
384 {
385         int held1, held2;
386 
387         held1 = (gl->gl_state != LM_ST_UNLOCKED);
388         held2 = (new_state != LM_ST_UNLOCKED);
389 
390         if (held1 != held2) {
391                 GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
392                 if (held2)
393                         gl->gl_lockref.count++;
394                 else
395                         gl->gl_lockref.count--;
396         }
397         if (held1 && held2 && list_empty(&gl->gl_holders))
398                 clear_bit(GLF_QUEUED, &gl->gl_flags);
399 
400         if (new_state != gl->gl_target)
401                 /* shorten our minimum hold time */
402                 gl->gl_hold_time = max(gl->gl_hold_time - GL_GLOCK_HOLD_DECR,
403                                        GL_GLOCK_MIN_HOLD);
404         gl->gl_state = new_state;
405         gl->gl_tchange = jiffies;
406 }
407 
408 static void gfs2_demote_wake(struct gfs2_glock *gl)
409 {
410         gl->gl_demote_state = LM_ST_EXCLUSIVE;
411         clear_bit(GLF_DEMOTE, &gl->gl_flags);
412         smp_mb__after_clear_bit();
413         wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
414 }
415 
416 /**
417  * finish_xmote - The DLM has replied to one of our lock requests
418  * @gl: The glock
419  * @ret: The status from the DLM
420  *
421  */
422 
423 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
424 {
425         const struct gfs2_glock_operations *glops = gl->gl_ops;
426         struct gfs2_holder *gh;
427         unsigned state = ret & LM_OUT_ST_MASK;
428         int rv;
429 
430         spin_lock(&gl->gl_spin);
431         trace_gfs2_glock_state_change(gl, state);
432         state_change(gl, state);
433         gh = find_first_waiter(gl);
434 
435         /* Demote to UN request arrived during demote to SH or DF */
436         if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
437             state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
438                 gl->gl_target = LM_ST_UNLOCKED;
439 
440         /* Check for state != intended state */
441         if (unlikely(state != gl->gl_target)) {
442                 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
443                         /* move to back of queue and try next entry */
444                         if (ret & LM_OUT_CANCELED) {
445                                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
446                                         list_move_tail(&gh->gh_list, &gl->gl_holders);
447                                 gh = find_first_waiter(gl);
448                                 gl->gl_target = gh->gh_state;
449                                 goto retry;
450                         }
451                         /* Some error or failed "try lock" - report it */
452                         if ((ret & LM_OUT_ERROR) ||
453                             (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
454                                 gl->gl_target = gl->gl_state;
455                                 do_error(gl, ret);
456                                 goto out;
457                         }
458                 }
459                 switch(state) {
460                 /* Unlocked due to conversion deadlock, try again */
461                 case LM_ST_UNLOCKED:
462 retry:
463                         do_xmote(gl, gh, gl->gl_target);
464                         break;
465                 /* Conversion fails, unlock and try again */
466                 case LM_ST_SHARED:
467                 case LM_ST_DEFERRED:
468                         do_xmote(gl, gh, LM_ST_UNLOCKED);
469                         break;
470                 default: /* Everything else */
471                         printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
472                         GLOCK_BUG_ON(gl, 1);
473                 }
474                 spin_unlock(&gl->gl_spin);
475                 return;
476         }
477 
478         /* Fast path - we got what we asked for */
479         if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
480                 gfs2_demote_wake(gl);
481         if (state != LM_ST_UNLOCKED) {
482                 if (glops->go_xmote_bh) {
483                         spin_unlock(&gl->gl_spin);
484                         rv = glops->go_xmote_bh(gl, gh);
485                         spin_lock(&gl->gl_spin);
486                         if (rv) {
487                                 do_error(gl, rv);
488                                 goto out;
489                         }
490                 }
491                 rv = do_promote(gl);
492                 if (rv == 2)
493                         goto out_locked;
494         }
495 out:
496         clear_bit(GLF_LOCK, &gl->gl_flags);
497 out_locked:
498         spin_unlock(&gl->gl_spin);
499 }
500 
501 /**
502  * do_xmote - Calls the DLM to change the state of a lock
503  * @gl: The lock state
504  * @gh: The holder (only for promotes)
505  * @target: The target lock state
506  *
507  */
508 
509 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
510 __releases(&gl->gl_spin)
511 __acquires(&gl->gl_spin)
512 {
513         const struct gfs2_glock_operations *glops = gl->gl_ops;
514         struct gfs2_sbd *sdp = gl->gl_sbd;
515         unsigned int lck_flags = gh ? gh->gh_flags : 0;
516         int ret;
517 
518         lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
519                       LM_FLAG_PRIORITY);
520         GLOCK_BUG_ON(gl, gl->gl_state == target);
521         GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
522         if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
523             glops->go_inval) {
524                 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
525                 do_error(gl, 0); /* Fail queued try locks */
526         }
527         gl->gl_req = target;
528         set_bit(GLF_BLOCKING, &gl->gl_flags);
529         if ((gl->gl_req == LM_ST_UNLOCKED) ||
530             (gl->gl_state == LM_ST_EXCLUSIVE) ||
531             (lck_flags & (LM_FLAG_TRY|LM_FLAG_TRY_1CB)))
532                 clear_bit(GLF_BLOCKING, &gl->gl_flags);
533         spin_unlock(&gl->gl_spin);
534         if (glops->go_sync)
535                 glops->go_sync(gl);
536         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
537                 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
538         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
539 
540         gfs2_glock_hold(gl);
541         if (sdp->sd_lockstruct.ls_ops->lm_lock) {
542                 /* lock_dlm */
543                 ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
544                 if (ret) {
545                         printk(KERN_ERR "GFS2: lm_lock ret %d\n", ret);
546                         GLOCK_BUG_ON(gl, 1);
547                 }
548         } else { /* lock_nolock */
549                 finish_xmote(gl, target);
550                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
551                         gfs2_glock_put(gl);
552         }
553 
554         spin_lock(&gl->gl_spin);
555 }
556 
557 /**
558  * find_first_holder - find the first "holder" gh
559  * @gl: the glock
560  */
561 
562 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
563 {
564         struct gfs2_holder *gh;
565 
566         if (!list_empty(&gl->gl_holders)) {
567                 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
568                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
569                         return gh;
570         }
571         return NULL;
572 }
573 
574 /**
575  * run_queue - do all outstanding tasks related to a glock
576  * @gl: The glock in question
577  * @nonblock: True if we must not block in run_queue
578  *
579  */
580 
581 static void run_queue(struct gfs2_glock *gl, const int nonblock)
582 __releases(&gl->gl_spin)
583 __acquires(&gl->gl_spin)
584 {
585         struct gfs2_holder *gh = NULL;
586         int ret;
587 
588         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
589                 return;
590 
591         GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
592 
593         if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
594             gl->gl_demote_state != gl->gl_state) {
595                 if (find_first_holder(gl))
596                         goto out_unlock;
597                 if (nonblock)
598                         goto out_sched;
599                 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
600                 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
601                 gl->gl_target = gl->gl_demote_state;
602         } else {
603                 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
604                         gfs2_demote_wake(gl);
605                 ret = do_promote(gl);
606                 if (ret == 0)
607                         goto out_unlock;
608                 if (ret == 2)
609                         goto out;
610                 gh = find_first_waiter(gl);
611                 gl->gl_target = gh->gh_state;
612                 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
613                         do_error(gl, 0); /* Fail queued try locks */
614         }
615         do_xmote(gl, gh, gl->gl_target);
616 out:
617         return;
618 
619 out_sched:
620         clear_bit(GLF_LOCK, &gl->gl_flags);
621         smp_mb__after_clear_bit();
622         gl->gl_lockref.count++;
623         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
624                 gl->gl_lockref.count--;
625         return;
626 
627 out_unlock:
628         clear_bit(GLF_LOCK, &gl->gl_flags);
629         smp_mb__after_clear_bit();
630         return;
631 }
632 
633 static void delete_work_func(struct work_struct *work)
634 {
635         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
636         struct gfs2_sbd *sdp = gl->gl_sbd;
637         struct gfs2_inode *ip;
638         struct inode *inode;
639         u64 no_addr = gl->gl_name.ln_number;
640 
641         ip = gl->gl_object;
642         /* Note: Unsafe to dereference ip as we don't hold right refs/locks */
643 
644         if (ip)
645                 inode = gfs2_ilookup(sdp->sd_vfs, no_addr, 1);
646         else
647                 inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
648         if (inode && !IS_ERR(inode)) {
649                 d_prune_aliases(inode);
650                 iput(inode);
651         }
652         gfs2_glock_put(gl);
653 }
654 
655 static void glock_work_func(struct work_struct *work)
656 {
657         unsigned long delay = 0;
658         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
659         int drop_ref = 0;
660 
661         if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
662                 finish_xmote(gl, gl->gl_reply);
663                 drop_ref = 1;
664         }
665         spin_lock(&gl->gl_spin);
666         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
667             gl->gl_state != LM_ST_UNLOCKED &&
668             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
669                 unsigned long holdtime, now = jiffies;
670 
671                 holdtime = gl->gl_tchange + gl->gl_hold_time;
672                 if (time_before(now, holdtime))
673                         delay = holdtime - now;
674 
675                 if (!delay) {
676                         clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
677                         set_bit(GLF_DEMOTE, &gl->gl_flags);
678                 }
679         }
680         run_queue(gl, 0);
681         spin_unlock(&gl->gl_spin);
682         if (!delay)
683                 gfs2_glock_put(gl);
684         else {
685                 if (gl->gl_name.ln_type != LM_TYPE_INODE)
686                         delay = 0;
687                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
688                         gfs2_glock_put(gl);
689         }
690         if (drop_ref)
691                 gfs2_glock_put(gl);
692 }
693 
694 /**
695  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
696  * @sdp: The GFS2 superblock
697  * @number: the lock number
698  * @glops: The glock_operations to use
699  * @create: If 0, don't create the glock if it doesn't exist
700  * @glp: the glock is returned here
701  *
702  * This does not lock a glock, just finds/creates structures for one.
703  *
704  * Returns: errno
705  */
706 
707 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
708                    const struct gfs2_glock_operations *glops, int create,
709                    struct gfs2_glock **glp)
710 {
711         struct super_block *s = sdp->sd_vfs;
712         struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
713         struct gfs2_glock *gl, *tmp;
714         unsigned int hash = gl_hash(sdp, &name);
715         struct address_space *mapping;
716         struct kmem_cache *cachep;
717 
718         rcu_read_lock();
719         gl = search_bucket(hash, sdp, &name);
720         rcu_read_unlock();
721 
722         *glp = gl;
723         if (gl)
724                 return 0;
725         if (!create)
726                 return -ENOENT;
727 
728         if (glops->go_flags & GLOF_ASPACE)
729                 cachep = gfs2_glock_aspace_cachep;
730         else
731                 cachep = gfs2_glock_cachep;
732         gl = kmem_cache_alloc(cachep, GFP_KERNEL);
733         if (!gl)
734                 return -ENOMEM;
735 
736         memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
737 
738         if (glops->go_flags & GLOF_LVB) {
739                 gl->gl_lksb.sb_lvbptr = kzalloc(GFS2_MIN_LVB_SIZE, GFP_KERNEL);
740                 if (!gl->gl_lksb.sb_lvbptr) {
741                         kmem_cache_free(cachep, gl);
742                         return -ENOMEM;
743                 }
744         }
745 
746         atomic_inc(&sdp->sd_glock_disposal);
747         gl->gl_sbd = sdp;
748         gl->gl_flags = 0;
749         gl->gl_name = name;
750         gl->gl_lockref.count = 1;
751         gl->gl_state = LM_ST_UNLOCKED;
752         gl->gl_target = LM_ST_UNLOCKED;
753         gl->gl_demote_state = LM_ST_EXCLUSIVE;
754         gl->gl_hash = hash;
755         gl->gl_ops = glops;
756         gl->gl_dstamp = ktime_set(0, 0);
757         preempt_disable();
758         /* We use the global stats to estimate the initial per-glock stats */
759         gl->gl_stats = this_cpu_ptr(sdp->sd_lkstats)->lkstats[glops->go_type];
760         preempt_enable();
761         gl->gl_stats.stats[GFS2_LKS_DCOUNT] = 0;
762         gl->gl_stats.stats[GFS2_LKS_QCOUNT] = 0;
763         gl->gl_tchange = jiffies;
764         gl->gl_object = NULL;
765         gl->gl_hold_time = GL_GLOCK_DFT_HOLD;
766         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
767         INIT_WORK(&gl->gl_delete, delete_work_func);
768 
769         mapping = gfs2_glock2aspace(gl);
770         if (mapping) {
771                 mapping->a_ops = &gfs2_meta_aops;
772                 mapping->host = s->s_bdev->bd_inode;
773                 mapping->flags = 0;
774                 mapping_set_gfp_mask(mapping, GFP_NOFS);
775                 mapping->private_data = NULL;
776                 mapping->backing_dev_info = s->s_bdi;
777                 mapping->writeback_index = 0;
778         }
779 
780         spin_lock_bucket(hash);
781         tmp = search_bucket(hash, sdp, &name);
782         if (tmp) {
783                 spin_unlock_bucket(hash);
784                 kfree(gl->gl_lksb.sb_lvbptr);
785                 kmem_cache_free(cachep, gl);
786                 atomic_dec(&sdp->sd_glock_disposal);
787                 gl = tmp;
788         } else {
789                 hlist_bl_add_head_rcu(&gl->gl_list, &gl_hash_table[hash]);
790                 spin_unlock_bucket(hash);
791         }
792 
793         *glp = gl;
794 
795         return 0;
796 }
797 
798 /**
799  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
800  * @gl: the glock
801  * @state: the state we're requesting
802  * @flags: the modifier flags
803  * @gh: the holder structure
804  *
805  */
806 
807 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
808                       struct gfs2_holder *gh)
809 {
810         INIT_LIST_HEAD(&gh->gh_list);
811         gh->gh_gl = gl;
812         gh->gh_ip = (unsigned long)__builtin_return_address(0);
813         gh->gh_owner_pid = get_pid(task_pid(current));
814         gh->gh_state = state;
815         gh->gh_flags = flags;
816         gh->gh_error = 0;
817         gh->gh_iflags = 0;
818         gfs2_glock_hold(gl);
819 }
820 
821 /**
822  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
823  * @state: the state we're requesting
824  * @flags: the modifier flags
825  * @gh: the holder structure
826  *
827  * Don't mess with the glock.
828  *
829  */
830 
831 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
832 {
833         gh->gh_state = state;
834         gh->gh_flags = flags;
835         gh->gh_iflags = 0;
836         gh->gh_ip = (unsigned long)__builtin_return_address(0);
837         if (gh->gh_owner_pid)
838                 put_pid(gh->gh_owner_pid);
839         gh->gh_owner_pid = get_pid(task_pid(current));
840 }
841 
842 /**
843  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
844  * @gh: the holder structure
845  *
846  */
847 
848 void gfs2_holder_uninit(struct gfs2_holder *gh)
849 {
850         put_pid(gh->gh_owner_pid);
851         gfs2_glock_put(gh->gh_gl);
852         gh->gh_gl = NULL;
853         gh->gh_ip = 0;
854 }
855 
856 /**
857  * gfs2_glock_holder_wait
858  * @word: unused
859  *
860  * This function and gfs2_glock_demote_wait both show up in the WCHAN
861  * field. Thus I've separated these otherwise identical functions in
862  * order to be more informative to the user.
863  */
864 
865 static int gfs2_glock_holder_wait(void *word)
866 {
867         schedule();
868         return 0;
869 }
870 
871 static int gfs2_glock_demote_wait(void *word)
872 {
873         schedule();
874         return 0;
875 }
876 
877 /**
878  * gfs2_glock_wait - wait on a glock acquisition
879  * @gh: the glock holder
880  *
881  * Returns: 0 on success
882  */
883 
884 int gfs2_glock_wait(struct gfs2_holder *gh)
885 {
886         unsigned long time1 = jiffies;
887 
888         might_sleep();
889         wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
890         if (time_after(jiffies, time1 + HZ)) /* have we waited > a second? */
891                 /* Lengthen the minimum hold time. */
892                 gh->gh_gl->gl_hold_time = min(gh->gh_gl->gl_hold_time +
893                                               GL_GLOCK_HOLD_INCR,
894                                               GL_GLOCK_MAX_HOLD);
895         return gh->gh_error;
896 }
897 
898 /**
899  * handle_callback - process a demote request
900  * @gl: the glock
901  * @state: the state the caller wants us to change to
902  *
903  * There are only two requests that we are going to see in actual
904  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
905  */
906 
907 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
908                             unsigned long delay, bool remote)
909 {
910         int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
911 
912         set_bit(bit, &gl->gl_flags);
913         if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
914                 gl->gl_demote_state = state;
915                 gl->gl_demote_time = jiffies;
916         } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
917                         gl->gl_demote_state != state) {
918                 gl->gl_demote_state = LM_ST_UNLOCKED;
919         }
920         if (gl->gl_ops->go_callback)
921                 gl->gl_ops->go_callback(gl, remote);
922         trace_gfs2_demote_rq(gl, remote);
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                 seq_vprintf(seq, fmt, args);
934         } else {
935                 vaf.fmt = fmt;
936                 vaf.va = &args;
937 
938                 printk(KERN_ERR " %pV", &vaf);
939         }
940 
941         va_end(args);
942 }
943 
944 /**
945  * add_to_queue - Add a holder to the wait queue (but look for recursion)
946  * @gh: the holder structure to add
947  *
948  * Eventually we should move the recursive locking trap to a
949  * debugging option or something like that. This is the fast
950  * path and needs to have the minimum number of distractions.
951  * 
952  */
953 
954 static inline void add_to_queue(struct gfs2_holder *gh)
955 __releases(&gl->gl_spin)
956 __acquires(&gl->gl_spin)
957 {
958         struct gfs2_glock *gl = gh->gh_gl;
959         struct gfs2_sbd *sdp = gl->gl_sbd;
960         struct list_head *insert_pt = NULL;
961         struct gfs2_holder *gh2;
962         int try_futile = 0;
963 
964         BUG_ON(gh->gh_owner_pid == NULL);
965         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
966                 BUG();
967 
968         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
969                 if (test_bit(GLF_LOCK, &gl->gl_flags))
970                         try_futile = !may_grant(gl, gh);
971                 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
972                         goto fail;
973         }
974 
975         list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
976                 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
977                     (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
978                         goto trap_recursive;
979                 if (try_futile &&
980                     !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
981 fail:
982                         gh->gh_error = GLR_TRYFAILED;
983                         gfs2_holder_wake(gh);
984                         return;
985                 }
986                 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
987                         continue;
988                 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
989                         insert_pt = &gh2->gh_list;
990         }
991         set_bit(GLF_QUEUED, &gl->gl_flags);
992         trace_gfs2_glock_queue(gh, 1);
993         gfs2_glstats_inc(gl, GFS2_LKS_QCOUNT);
994         gfs2_sbstats_inc(gl, GFS2_LKS_QCOUNT);
995         if (likely(insert_pt == NULL)) {
996                 list_add_tail(&gh->gh_list, &gl->gl_holders);
997                 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
998                         goto do_cancel;
999                 return;
1000         }
1001         list_add_tail(&gh->gh_list, insert_pt);
1002 do_cancel:
1003         gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
1004         if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
1005                 spin_unlock(&gl->gl_spin);
1006                 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
1007                         sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
1008                 spin_lock(&gl->gl_spin);
1009         }
1010         return;
1011 
1012 trap_recursive:
1013         printk(KERN_ERR "original: %pSR\n", (void *)gh2->gh_ip);
1014         printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
1015         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1016                gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
1017         printk(KERN_ERR "new: %pSR\n", (void *)gh->gh_ip);
1018         printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
1019         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1020                gh->gh_gl->gl_name.ln_type, gh->gh_state);
1021         gfs2_dump_glock(NULL, gl);
1022         BUG();
1023 }
1024 
1025 /**
1026  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1027  * @gh: the holder structure
1028  *
1029  * if (gh->gh_flags & GL_ASYNC), this never returns an error
1030  *
1031  * Returns: 0, GLR_TRYFAILED, or errno on failure
1032  */
1033 
1034 int gfs2_glock_nq(struct gfs2_holder *gh)
1035 {
1036         struct gfs2_glock *gl = gh->gh_gl;
1037         struct gfs2_sbd *sdp = gl->gl_sbd;
1038         int error = 0;
1039 
1040         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
1041                 return -EIO;
1042 
1043         if (test_bit(GLF_LRU, &gl->gl_flags))
1044                 gfs2_glock_remove_from_lru(gl);
1045 
1046         spin_lock(&gl->gl_spin);
1047         add_to_queue(gh);
1048         if ((LM_FLAG_NOEXP & gh->gh_flags) &&
1049             test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1050                 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1051         run_queue(gl, 1);
1052         spin_unlock(&gl->gl_spin);
1053 
1054         if (!(gh->gh_flags & GL_ASYNC))
1055                 error = gfs2_glock_wait(gh);
1056 
1057         return error;
1058 }
1059 
1060 /**
1061  * gfs2_glock_poll - poll to see if an async request has been completed
1062  * @gh: the holder
1063  *
1064  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1065  */
1066 
1067 int gfs2_glock_poll(struct gfs2_holder *gh)
1068 {
1069         return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1070 }
1071 
1072 /**
1073  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1074  * @gh: the glock holder
1075  *
1076  */
1077 
1078 void gfs2_glock_dq(struct gfs2_holder *gh)
1079 {
1080         struct gfs2_glock *gl = gh->gh_gl;
1081         const struct gfs2_glock_operations *glops = gl->gl_ops;
1082         unsigned delay = 0;
1083         int fast_path = 0;
1084 
1085         spin_lock(&gl->gl_spin);
1086         if (gh->gh_flags & GL_NOCACHE)
1087                 handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1088 
1089         list_del_init(&gh->gh_list);
1090         if (find_first_holder(gl) == NULL) {
1091                 if (glops->go_unlock) {
1092                         GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1093                         spin_unlock(&gl->gl_spin);
1094                         glops->go_unlock(gh);
1095                         spin_lock(&gl->gl_spin);
1096                         clear_bit(GLF_LOCK, &gl->gl_flags);
1097                 }
1098                 if (list_empty(&gl->gl_holders) &&
1099                     !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1100                     !test_bit(GLF_DEMOTE, &gl->gl_flags))
1101                         fast_path = 1;
1102         }
1103         if (!test_bit(GLF_LFLUSH, &gl->gl_flags) && demote_ok(gl))
1104                 gfs2_glock_add_to_lru(gl);
1105 
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         might_sleep();
1125         wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
1126 }
1127 
1128 /**
1129  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1130  * @gh: the holder structure
1131  *
1132  */
1133 
1134 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1135 {
1136         gfs2_glock_dq(gh);
1137         gfs2_holder_uninit(gh);
1138 }
1139 
1140 /**
1141  * gfs2_glock_nq_num - acquire a glock based on lock number
1142  * @sdp: the filesystem
1143  * @number: the lock number
1144  * @glops: the glock operations for the type of glock
1145  * @state: the state to acquire the glock in
1146  * @flags: modifier flags for the acquisition
1147  * @gh: the struct gfs2_holder
1148  *
1149  * Returns: errno
1150  */
1151 
1152 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1153                       const struct gfs2_glock_operations *glops,
1154                       unsigned int state, int flags, struct gfs2_holder *gh)
1155 {
1156         struct gfs2_glock *gl;
1157         int error;
1158 
1159         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1160         if (!error) {
1161                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1162                 gfs2_glock_put(gl);
1163         }
1164 
1165         return error;
1166 }
1167 
1168 /**
1169  * glock_compare - Compare two struct gfs2_glock structures for sorting
1170  * @arg_a: the first structure
1171  * @arg_b: the second structure
1172  *
1173  */
1174 
1175 static int glock_compare(const void *arg_a, const void *arg_b)
1176 {
1177         const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1178         const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1179         const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1180         const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1181 
1182         if (a->ln_number > b->ln_number)
1183                 return 1;
1184         if (a->ln_number < b->ln_number)
1185                 return -1;
1186         BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1187         return 0;
1188 }
1189 
1190 /**
1191  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1192  * @num_gh: the number of structures
1193  * @ghs: an array of struct gfs2_holder structures
1194  *
1195  * Returns: 0 on success (all glocks acquired),
1196  *          errno on failure (no glocks acquired)
1197  */
1198 
1199 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1200                      struct gfs2_holder **p)
1201 {
1202         unsigned int x;
1203         int error = 0;
1204 
1205         for (x = 0; x < num_gh; x++)
1206                 p[x] = &ghs[x];
1207 
1208         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1209 
1210         for (x = 0; x < num_gh; x++) {
1211                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1212 
1213                 error = gfs2_glock_nq(p[x]);
1214                 if (error) {
1215                         while (x--)
1216                                 gfs2_glock_dq(p[x]);
1217                         break;
1218                 }
1219         }
1220 
1221         return error;
1222 }
1223 
1224 /**
1225  * gfs2_glock_nq_m - acquire multiple glocks
1226  * @num_gh: the number of structures
1227  * @ghs: an array of struct gfs2_holder structures
1228  *
1229  *
1230  * Returns: 0 on success (all glocks acquired),
1231  *          errno on failure (no glocks acquired)
1232  */
1233 
1234 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1235 {
1236         struct gfs2_holder *tmp[4];
1237         struct gfs2_holder **pph = tmp;
1238         int error = 0;
1239 
1240         switch(num_gh) {
1241         case 0:
1242                 return 0;
1243         case 1:
1244                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1245                 return gfs2_glock_nq(ghs);
1246         default:
1247                 if (num_gh <= 4)
1248                         break;
1249                 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1250                 if (!pph)
1251                         return -ENOMEM;
1252         }
1253 
1254         error = nq_m_sync(num_gh, ghs, pph);
1255 
1256         if (pph != tmp)
1257                 kfree(pph);
1258 
1259         return error;
1260 }
1261 
1262 /**
1263  * gfs2_glock_dq_m - release multiple glocks
1264  * @num_gh: the number of structures
1265  * @ghs: an array of struct gfs2_holder structures
1266  *
1267  */
1268 
1269 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1270 {
1271         while (num_gh--)
1272                 gfs2_glock_dq(&ghs[num_gh]);
1273 }
1274 
1275 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1276 {
1277         unsigned long delay = 0;
1278         unsigned long holdtime;
1279         unsigned long now = jiffies;
1280 
1281         gfs2_glock_hold(gl);
1282         holdtime = gl->gl_tchange + gl->gl_hold_time;
1283         if (test_bit(GLF_QUEUED, &gl->gl_flags) &&
1284             gl->gl_name.ln_type == LM_TYPE_INODE) {
1285                 if (time_before(now, holdtime))
1286                         delay = holdtime - now;
1287                 if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1288                         delay = gl->gl_hold_time;
1289         }
1290 
1291         spin_lock(&gl->gl_spin);
1292         handle_callback(gl, state, delay, true);
1293         spin_unlock(&gl->gl_spin);
1294         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1295                 gfs2_glock_put(gl);
1296 }
1297 
1298 /**
1299  * gfs2_should_freeze - Figure out if glock should be frozen
1300  * @gl: The glock in question
1301  *
1302  * Glocks are not frozen if (a) the result of the dlm operation is
1303  * an error, (b) the locking operation was an unlock operation or
1304  * (c) if there is a "noexp" flagged request anywhere in the queue
1305  *
1306  * Returns: 1 if freezing should occur, 0 otherwise
1307  */
1308 
1309 static int gfs2_should_freeze(const struct gfs2_glock *gl)
1310 {
1311         const struct gfs2_holder *gh;
1312 
1313         if (gl->gl_reply & ~LM_OUT_ST_MASK)
1314                 return 0;
1315         if (gl->gl_target == LM_ST_UNLOCKED)
1316                 return 0;
1317 
1318         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1319                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1320                         continue;
1321                 if (LM_FLAG_NOEXP & gh->gh_flags)
1322                         return 0;
1323         }
1324 
1325         return 1;
1326 }
1327 
1328 /**
1329  * gfs2_glock_complete - Callback used by locking
1330  * @gl: Pointer to the glock
1331  * @ret: The return value from the dlm
1332  *
1333  * The gl_reply field is under the gl_spin lock so that it is ok
1334  * to use a bitfield shared with other glock state fields.
1335  */
1336 
1337 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1338 {
1339         struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
1340 
1341         spin_lock(&gl->gl_spin);
1342         gl->gl_reply = ret;
1343 
1344         if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags))) {
1345                 if (gfs2_should_freeze(gl)) {
1346                         set_bit(GLF_FROZEN, &gl->gl_flags);
1347                         spin_unlock(&gl->gl_spin);
1348                         return;
1349                 }
1350         }
1351 
1352         gl->gl_lockref.count++;
1353         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1354         spin_unlock(&gl->gl_spin);
1355 
1356         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1357                 gfs2_glock_put(gl);
1358 }
1359 
1360 static int glock_cmp(void *priv, struct list_head *a, struct list_head *b)
1361 {
1362         struct gfs2_glock *gla, *glb;
1363 
1364         gla = list_entry(a, struct gfs2_glock, gl_lru);
1365         glb = list_entry(b, struct gfs2_glock, gl_lru);
1366 
1367         if (gla->gl_name.ln_number > glb->gl_name.ln_number)
1368                 return 1;
1369         if (gla->gl_name.ln_number < glb->gl_name.ln_number)
1370                 return -1;
1371 
1372         return 0;
1373 }
1374 
1375 /**
1376  * gfs2_dispose_glock_lru - Demote a list of glocks
1377  * @list: The list to dispose of
1378  *
1379  * Disposing of glocks may involve disk accesses, so that here we sort
1380  * the glocks by number (i.e. disk location of the inodes) so that if
1381  * there are any such accesses, they'll be sent in order (mostly).
1382  *
1383  * Must be called under the lru_lock, but may drop and retake this
1384  * lock. While the lru_lock is dropped, entries may vanish from the
1385  * list, but no new entries will appear on the list (since it is
1386  * private)
1387  */
1388 
1389 static void gfs2_dispose_glock_lru(struct list_head *list)
1390 __releases(&lru_lock)
1391 __acquires(&lru_lock)
1392 {
1393         struct gfs2_glock *gl;
1394 
1395         list_sort(NULL, list, glock_cmp);
1396 
1397         while(!list_empty(list)) {
1398                 gl = list_entry(list->next, struct gfs2_glock, gl_lru);
1399                 list_del_init(&gl->gl_lru);
1400                 if (!spin_trylock(&gl->gl_spin)) {
1401                         list_add(&gl->gl_lru, &lru_list);
1402                         atomic_inc(&lru_count);
1403                         continue;
1404                 }
1405                 clear_bit(GLF_LRU, &gl->gl_flags);
1406                 spin_unlock(&lru_lock);
1407                 gl->gl_lockref.count++;
1408                 if (demote_ok(gl))
1409                         handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1410                 WARN_ON(!test_and_clear_bit(GLF_LOCK, &gl->gl_flags));
1411                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1412                         gl->gl_lockref.count--;
1413                 spin_unlock(&gl->gl_spin);
1414                 spin_lock(&lru_lock);
1415         }
1416 }
1417 
1418 /**
1419  * gfs2_scan_glock_lru - Scan the LRU looking for locks to demote
1420  * @nr: The number of entries to scan
1421  *
1422  * This function selects the entries on the LRU which are able to
1423  * be demoted, and then kicks off the process by calling
1424  * gfs2_dispose_glock_lru() above.
1425  */
1426 
1427 static long gfs2_scan_glock_lru(int nr)
1428 {
1429         struct gfs2_glock *gl;
1430         LIST_HEAD(skipped);
1431         LIST_HEAD(dispose);
1432         long freed = 0;
1433 
1434         spin_lock(&lru_lock);
1435         while ((nr-- >= 0) && !list_empty(&lru_list)) {
1436                 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1437 
1438                 /* Test for being demotable */
1439                 if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1440                         list_move(&gl->gl_lru, &dispose);
1441                         atomic_dec(&lru_count);
1442                         freed++;
1443                         continue;
1444                 }
1445 
1446                 list_move(&gl->gl_lru, &skipped);
1447         }
1448         list_splice(&skipped, &lru_list);
1449         if (!list_empty(&dispose))
1450                 gfs2_dispose_glock_lru(&dispose);
1451         spin_unlock(&lru_lock);
1452 
1453         return freed;
1454 }
1455 
1456 static unsigned long gfs2_glock_shrink_scan(struct shrinker *shrink,
1457                                             struct shrink_control *sc)
1458 {
1459         if (!(sc->gfp_mask & __GFP_FS))
1460                 return SHRINK_STOP;
1461         return gfs2_scan_glock_lru(sc->nr_to_scan);
1462 }
1463 
1464 static unsigned long gfs2_glock_shrink_count(struct shrinker *shrink,
1465                                              struct shrink_control *sc)
1466 {
1467         return vfs_pressure_ratio(atomic_read(&lru_count));
1468 }
1469 
1470 static struct shrinker glock_shrinker = {
1471         .seeks = DEFAULT_SEEKS,
1472         .count_objects = gfs2_glock_shrink_count,
1473         .scan_objects = gfs2_glock_shrink_scan,
1474 };
1475 
1476 /**
1477  * examine_bucket - Call a function for glock in a hash bucket
1478  * @examiner: the function
1479  * @sdp: the filesystem
1480  * @bucket: the bucket
1481  *
1482  */
1483 
1484 static void examine_bucket(glock_examiner examiner, const struct gfs2_sbd *sdp,
1485                           unsigned int hash)
1486 {
1487         struct gfs2_glock *gl;
1488         struct hlist_bl_head *head = &gl_hash_table[hash];
1489         struct hlist_bl_node *pos;
1490 
1491         rcu_read_lock();
1492         hlist_bl_for_each_entry_rcu(gl, pos, head, gl_list) {
1493                 if ((gl->gl_sbd == sdp) && lockref_get_not_dead(&gl->gl_lockref))
1494                         examiner(gl);
1495         }
1496         rcu_read_unlock();
1497         cond_resched();
1498 }
1499 
1500 static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
1501 {
1502         unsigned x;
1503 
1504         for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1505                 examine_bucket(examiner, sdp, x);
1506 }
1507 
1508 
1509 /**
1510  * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1511  * @gl: The glock to thaw
1512  *
1513  */
1514 
1515 static void thaw_glock(struct gfs2_glock *gl)
1516 {
1517         if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1518                 goto out;
1519         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1520         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0) {
1521 out:
1522                 gfs2_glock_put(gl);
1523         }
1524 }
1525 
1526 /**
1527  * clear_glock - look at a glock and see if we can free it from glock cache
1528  * @gl: the glock to look at
1529  *
1530  */
1531 
1532 static void clear_glock(struct gfs2_glock *gl)
1533 {
1534         gfs2_glock_remove_from_lru(gl);
1535 
1536         spin_lock(&gl->gl_spin);
1537         if (gl->gl_state != LM_ST_UNLOCKED)
1538                 handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1539         spin_unlock(&gl->gl_spin);
1540         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1541                 gfs2_glock_put(gl);
1542 }
1543 
1544 /**
1545  * gfs2_glock_thaw - Thaw any frozen glocks
1546  * @sdp: The super block
1547  *
1548  */
1549 
1550 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1551 {
1552         glock_hash_walk(thaw_glock, sdp);
1553 }
1554 
1555 static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1556 {
1557         int ret;
1558         spin_lock(&gl->gl_spin);
1559         ret = gfs2_dump_glock(seq, gl);
1560         spin_unlock(&gl->gl_spin);
1561         return ret;
1562 }
1563 
1564 static void dump_glock_func(struct gfs2_glock *gl)
1565 {
1566         dump_glock(NULL, gl);
1567 }
1568 
1569 /**
1570  * gfs2_gl_hash_clear - Empty out the glock hash table
1571  * @sdp: the filesystem
1572  * @wait: wait until it's all gone
1573  *
1574  * Called when unmounting the filesystem.
1575  */
1576 
1577 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1578 {
1579         set_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags);
1580         flush_workqueue(glock_workqueue);
1581         glock_hash_walk(clear_glock, sdp);
1582         flush_workqueue(glock_workqueue);
1583         wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
1584         glock_hash_walk(dump_glock_func, sdp);
1585 }
1586 
1587 void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1588 {
1589         struct gfs2_glock *gl = ip->i_gl;
1590         int ret;
1591 
1592         ret = gfs2_truncatei_resume(ip);
1593         gfs2_assert_withdraw(gl->gl_sbd, ret == 0);
1594 
1595         spin_lock(&gl->gl_spin);
1596         clear_bit(GLF_LOCK, &gl->gl_flags);
1597         run_queue(gl, 1);
1598         spin_unlock(&gl->gl_spin);
1599 }
1600 
1601 static const char *state2str(unsigned state)
1602 {
1603         switch(state) {
1604         case LM_ST_UNLOCKED:
1605                 return "UN";
1606         case LM_ST_SHARED:
1607                 return "SH";
1608         case LM_ST_DEFERRED:
1609                 return "DF";
1610         case LM_ST_EXCLUSIVE:
1611                 return "EX";
1612         }
1613         return "??";
1614 }
1615 
1616 static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags)
1617 {
1618         char *p = buf;
1619         if (flags & LM_FLAG_TRY)
1620                 *p++ = 't';
1621         if (flags & LM_FLAG_TRY_1CB)
1622                 *p++ = 'T';
1623         if (flags & LM_FLAG_NOEXP)
1624                 *p++ = 'e';
1625         if (flags & LM_FLAG_ANY)
1626                 *p++ = 'A';
1627         if (flags & LM_FLAG_PRIORITY)
1628                 *p++ = 'p';
1629         if (flags & GL_ASYNC)
1630                 *p++ = 'a';
1631         if (flags & GL_EXACT)
1632                 *p++ = 'E';
1633         if (flags & GL_NOCACHE)
1634                 *p++ = 'c';
1635         if (test_bit(HIF_HOLDER, &iflags))
1636                 *p++ = 'H';
1637         if (test_bit(HIF_WAIT, &iflags))
1638                 *p++ = 'W';
1639         if (test_bit(HIF_FIRST, &iflags))
1640                 *p++ = 'F';
1641         *p = 0;
1642         return buf;
1643 }
1644 
1645 /**
1646  * dump_holder - print information about a glock holder
1647  * @seq: the seq_file struct
1648  * @gh: the glock holder
1649  *
1650  * Returns: 0 on success, -ENOBUFS when we run out of space
1651  */
1652 
1653 static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1654 {
1655         struct task_struct *gh_owner = NULL;
1656         char flags_buf[32];
1657 
1658         rcu_read_lock();
1659         if (gh->gh_owner_pid)
1660                 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1661         gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
1662                        state2str(gh->gh_state),
1663                        hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1664                        gh->gh_error,
1665                        gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1666                        gh_owner ? gh_owner->comm : "(ended)",
1667                        (void *)gh->gh_ip);
1668         rcu_read_unlock();
1669         return 0;
1670 }
1671 
1672 static const char *gflags2str(char *buf, const struct gfs2_glock *gl)
1673 {
1674         const unsigned long *gflags = &gl->gl_flags;
1675         char *p = buf;
1676 
1677         if (test_bit(GLF_LOCK, gflags))
1678                 *p++ = 'l';
1679         if (test_bit(GLF_DEMOTE, gflags))
1680                 *p++ = 'D';
1681         if (test_bit(GLF_PENDING_DEMOTE, gflags))
1682                 *p++ = 'd';
1683         if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1684                 *p++ = 'p';
1685         if (test_bit(GLF_DIRTY, gflags))
1686                 *p++ = 'y';
1687         if (test_bit(GLF_LFLUSH, gflags))
1688                 *p++ = 'f';
1689         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1690                 *p++ = 'i';
1691         if (test_bit(GLF_REPLY_PENDING, gflags))
1692                 *p++ = 'r';
1693         if (test_bit(GLF_INITIAL, gflags))
1694                 *p++ = 'I';
1695         if (test_bit(GLF_FROZEN, gflags))
1696                 *p++ = 'F';
1697         if (test_bit(GLF_QUEUED, gflags))
1698                 *p++ = 'q';
1699         if (test_bit(GLF_LRU, gflags))
1700                 *p++ = 'L';
1701         if (gl->gl_object)
1702                 *p++ = 'o';
1703         if (test_bit(GLF_BLOCKING, gflags))
1704                 *p++ = 'b';
1705         *p = 0;
1706         return buf;
1707 }
1708 
1709 /**
1710  * gfs2_dump_glock - print information about a glock
1711  * @seq: The seq_file struct
1712  * @gl: the glock
1713  *
1714  * The file format is as follows:
1715  * One line per object, capital letters are used to indicate objects
1716  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1717  * other objects are indented by a single space and follow the glock to
1718  * which they are related. Fields are indicated by lower case letters
1719  * followed by a colon and the field value, except for strings which are in
1720  * [] so that its possible to see if they are composed of spaces for
1721  * example. The field's are n = number (id of the object), f = flags,
1722  * t = type, s = state, r = refcount, e = error, p = pid.
1723  *
1724  * Returns: 0 on success, -ENOBUFS when we run out of space
1725  */
1726 
1727 int gfs2_dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1728 {
1729         const struct gfs2_glock_operations *glops = gl->gl_ops;
1730         unsigned long long dtime;
1731         const struct gfs2_holder *gh;
1732         char gflags_buf[32];
1733         int error = 0;
1734 
1735         dtime = jiffies - gl->gl_demote_time;
1736         dtime *= 1000000/HZ; /* demote time in uSec */
1737         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1738                 dtime = 0;
1739         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",
1740                   state2str(gl->gl_state),
1741                   gl->gl_name.ln_type,
1742                   (unsigned long long)gl->gl_name.ln_number,
1743                   gflags2str(gflags_buf, gl),
1744                   state2str(gl->gl_target),
1745                   state2str(gl->gl_demote_state), dtime,
1746                   atomic_read(&gl->gl_ail_count),
1747                   atomic_read(&gl->gl_revokes),
1748                   (int)gl->gl_lockref.count, gl->gl_hold_time);
1749 
1750         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1751                 error = dump_holder(seq, gh);
1752                 if (error)
1753                         goto out;
1754         }
1755         if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1756                 error = glops->go_dump(seq, gl);
1757 out:
1758         return error;
1759 }
1760 
1761 static int gfs2_glstats_seq_show(struct seq_file *seq, void *iter_ptr)
1762 {
1763         struct gfs2_glock *gl = iter_ptr;
1764 
1765         seq_printf(seq, "G: n:%u/%llx rtt:%lld/%lld rttb:%lld/%lld irt:%lld/%lld dcnt: %lld qcnt: %lld\n",
1766                    gl->gl_name.ln_type,
1767                    (unsigned long long)gl->gl_name.ln_number,
1768                    (long long)gl->gl_stats.stats[GFS2_LKS_SRTT],
1769                    (long long)gl->gl_stats.stats[GFS2_LKS_SRTTVAR],
1770                    (long long)gl->gl_stats.stats[GFS2_LKS_SRTTB],
1771                    (long long)gl->gl_stats.stats[GFS2_LKS_SRTTVARB],
1772                    (long long)gl->gl_stats.stats[GFS2_LKS_SIRT],
1773                    (long long)gl->gl_stats.stats[GFS2_LKS_SIRTVAR],
1774                    (long long)gl->gl_stats.stats[GFS2_LKS_DCOUNT],
1775                    (long long)gl->gl_stats.stats[GFS2_LKS_QCOUNT]);
1776         return 0;
1777 }
1778 
1779 static const char *gfs2_gltype[] = {
1780         "type",
1781         "reserved",
1782         "nondisk",
1783         "inode",
1784         "rgrp",
1785         "meta",
1786         "iopen",
1787         "flock",
1788         "plock",
1789         "quota",
1790         "journal",
1791 };
1792 
1793 static const char *gfs2_stype[] = {
1794         [GFS2_LKS_SRTT]         = "srtt",
1795         [GFS2_LKS_SRTTVAR]      = "srttvar",
1796         [GFS2_LKS_SRTTB]        = "srttb",
1797         [GFS2_LKS_SRTTVARB]     = "srttvarb",
1798         [GFS2_LKS_SIRT]         = "sirt",
1799         [GFS2_LKS_SIRTVAR]      = "sirtvar",
1800         [GFS2_LKS_DCOUNT]       = "dlm",
1801         [GFS2_LKS_QCOUNT]       = "queue",
1802 };
1803 
1804 #define GFS2_NR_SBSTATS (ARRAY_SIZE(gfs2_gltype) * ARRAY_SIZE(gfs2_stype))
1805 
1806 static int gfs2_sbstats_seq_show(struct seq_file *seq, void *iter_ptr)
1807 {
1808         struct gfs2_glock_iter *gi = seq->private;
1809         struct gfs2_sbd *sdp = gi->sdp;
1810         unsigned index = gi->hash >> 3;
1811         unsigned subindex = gi->hash & 0x07;
1812         s64 value;
1813         int i;
1814 
1815         if (index == 0 && subindex != 0)
1816                 return 0;
1817 
1818         seq_printf(seq, "%-10s %8s:", gfs2_gltype[index],
1819                    (index == 0) ? "cpu": gfs2_stype[subindex]);
1820 
1821         for_each_possible_cpu(i) {
1822                 const struct gfs2_pcpu_lkstats *lkstats = per_cpu_ptr(sdp->sd_lkstats, i);
1823                 if (index == 0) {
1824                         value = i;
1825                 } else {
1826                         value = lkstats->lkstats[index - 1].stats[subindex];
1827                 }
1828                 seq_printf(seq, " %15lld", (long long)value);
1829         }
1830         seq_putc(seq, '\n');
1831         return 0;
1832 }
1833 
1834 int __init gfs2_glock_init(void)
1835 {
1836         unsigned i;
1837         for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
1838                 INIT_HLIST_BL_HEAD(&gl_hash_table[i]);
1839         }
1840 
1841         glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
1842                                           WQ_HIGHPRI | WQ_FREEZABLE, 0);
1843         if (!glock_workqueue)
1844                 return -ENOMEM;
1845         gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
1846                                                 WQ_MEM_RECLAIM | WQ_FREEZABLE,
1847                                                 0);
1848         if (!gfs2_delete_workqueue) {
1849                 destroy_workqueue(glock_workqueue);
1850                 return -ENOMEM;
1851         }
1852 
1853         register_shrinker(&glock_shrinker);
1854 
1855         return 0;
1856 }
1857 
1858 void gfs2_glock_exit(void)
1859 {
1860         unregister_shrinker(&glock_shrinker);
1861         destroy_workqueue(glock_workqueue);
1862         destroy_workqueue(gfs2_delete_workqueue);
1863 }
1864 
1865 static inline struct gfs2_glock *glock_hash_chain(unsigned hash)
1866 {
1867         return hlist_bl_entry(hlist_bl_first_rcu(&gl_hash_table[hash]),
1868                               struct gfs2_glock, gl_list);
1869 }
1870 
1871 static inline struct gfs2_glock *glock_hash_next(struct gfs2_glock *gl)
1872 {
1873         return hlist_bl_entry(rcu_dereference(gl->gl_list.next),
1874                               struct gfs2_glock, gl_list);
1875 }
1876 
1877 static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1878 {
1879         struct gfs2_glock *gl;
1880 
1881         do {
1882                 gl = gi->gl;
1883                 if (gl) {
1884                         gi->gl = glock_hash_next(gl);
1885                         gi->nhash++;
1886                 } else {
1887                         if (gi->hash >= GFS2_GL_HASH_SIZE) {
1888                                 rcu_read_unlock();
1889                                 return 1;
1890                         }
1891                         gi->gl = glock_hash_chain(gi->hash);
1892                         gi->nhash = 0;
1893                 }
1894                 while (gi->gl == NULL) {
1895                         gi->hash++;
1896                         if (gi->hash >= GFS2_GL_HASH_SIZE) {
1897                                 rcu_read_unlock();
1898                                 return 1;
1899                         }
1900                         gi->gl = glock_hash_chain(gi->hash);
1901                         gi->nhash = 0;
1902                 }
1903         /* Skip entries for other sb and dead entries */
1904         } while (gi->sdp != gi->gl->gl_sbd ||
1905                  __lockref_is_dead(&gi->gl->gl_lockref));
1906 
1907         return 0;
1908 }
1909 
1910 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1911 {
1912         struct gfs2_glock_iter *gi = seq->private;
1913         loff_t n = *pos;
1914 
1915         if (gi->last_pos <= *pos)
1916                 n = gi->nhash + (*pos - gi->last_pos);
1917         else
1918                 gi->hash = 0;
1919 
1920         gi->nhash = 0;
1921         rcu_read_lock();
1922 
1923         do {
1924                 if (gfs2_glock_iter_next(gi))
1925                         return NULL;
1926         } while (n--);
1927 
1928         gi->last_pos = *pos;
1929         return gi->gl;
1930 }
1931 
1932 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1933                                  loff_t *pos)
1934 {
1935         struct gfs2_glock_iter *gi = seq->private;
1936 
1937         (*pos)++;
1938         gi->last_pos = *pos;
1939         if (gfs2_glock_iter_next(gi))
1940                 return NULL;
1941 
1942         return gi->gl;
1943 }
1944 
1945 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1946 {
1947         struct gfs2_glock_iter *gi = seq->private;
1948 
1949         if (gi->gl)
1950                 rcu_read_unlock();
1951         gi->gl = NULL;
1952 }
1953 
1954 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1955 {
1956         return dump_glock(seq, iter_ptr);
1957 }
1958 
1959 static void *gfs2_sbstats_seq_start(struct seq_file *seq, loff_t *pos)
1960 {
1961         struct gfs2_glock_iter *gi = seq->private;
1962 
1963         gi->hash = *pos;
1964         if (*pos >= GFS2_NR_SBSTATS)
1965                 return NULL;
1966         preempt_disable();
1967         return SEQ_START_TOKEN;
1968 }
1969 
1970 static void *gfs2_sbstats_seq_next(struct seq_file *seq, void *iter_ptr,
1971                                    loff_t *pos)
1972 {
1973         struct gfs2_glock_iter *gi = seq->private;
1974         (*pos)++;
1975         gi->hash++;
1976         if (gi->hash >= GFS2_NR_SBSTATS) {
1977                 preempt_enable();
1978                 return NULL;
1979         }
1980         return SEQ_START_TOKEN;
1981 }
1982 
1983 static void gfs2_sbstats_seq_stop(struct seq_file *seq, void *iter_ptr)
1984 {
1985         preempt_enable();
1986 }
1987 
1988 static const struct seq_operations gfs2_glock_seq_ops = {
1989         .start = gfs2_glock_seq_start,
1990         .next  = gfs2_glock_seq_next,
1991         .stop  = gfs2_glock_seq_stop,
1992         .show  = gfs2_glock_seq_show,
1993 };
1994 
1995 static const struct seq_operations gfs2_glstats_seq_ops = {
1996         .start = gfs2_glock_seq_start,
1997         .next  = gfs2_glock_seq_next,
1998         .stop  = gfs2_glock_seq_stop,
1999         .show  = gfs2_glstats_seq_show,
2000 };
2001 
2002 static const struct seq_operations gfs2_sbstats_seq_ops = {
2003         .start = gfs2_sbstats_seq_start,
2004         .next  = gfs2_sbstats_seq_next,
2005         .stop  = gfs2_sbstats_seq_stop,
2006         .show  = gfs2_sbstats_seq_show,
2007 };
2008 
2009 #define GFS2_SEQ_GOODSIZE min(PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER, 65536UL)
2010 
2011 static int gfs2_glocks_open(struct inode *inode, struct file *file)
2012 {
2013         int ret = seq_open_private(file, &gfs2_glock_seq_ops,
2014                                    sizeof(struct gfs2_glock_iter));
2015         if (ret == 0) {
2016                 struct seq_file *seq = file->private_data;
2017                 struct gfs2_glock_iter *gi = seq->private;
2018                 gi->sdp = inode->i_private;
2019                 seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
2020                 if (seq->buf)
2021                         seq->size = GFS2_SEQ_GOODSIZE;
2022         }
2023         return ret;
2024 }
2025 
2026 static int gfs2_glstats_open(struct inode *inode, struct file *file)
2027 {
2028         int ret = seq_open_private(file, &gfs2_glstats_seq_ops,
2029                                    sizeof(struct gfs2_glock_iter));
2030         if (ret == 0) {
2031                 struct seq_file *seq = file->private_data;
2032                 struct gfs2_glock_iter *gi = seq->private;
2033                 gi->sdp = inode->i_private;
2034                 seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
2035                 if (seq->buf)
2036                         seq->size = GFS2_SEQ_GOODSIZE;
2037         }
2038         return ret;
2039 }
2040 
2041 static int gfs2_sbstats_open(struct inode *inode, struct file *file)
2042 {
2043         int ret = seq_open_private(file, &gfs2_sbstats_seq_ops,
2044                                    sizeof(struct gfs2_glock_iter));
2045         if (ret == 0) {
2046                 struct seq_file *seq = file->private_data;
2047                 struct gfs2_glock_iter *gi = seq->private;
2048                 gi->sdp = inode->i_private;
2049         }
2050         return ret;
2051 }
2052 
2053 static const struct file_operations gfs2_glocks_fops = {
2054         .owner   = THIS_MODULE,
2055         .open    = gfs2_glocks_open,
2056         .read    = seq_read,
2057         .llseek  = seq_lseek,
2058         .release = seq_release_private,
2059 };
2060 
2061 static const struct file_operations gfs2_glstats_fops = {
2062         .owner   = THIS_MODULE,
2063         .open    = gfs2_glstats_open,
2064         .read    = seq_read,
2065         .llseek  = seq_lseek,
2066         .release = seq_release_private,
2067 };
2068 
2069 static const struct file_operations gfs2_sbstats_fops = {
2070         .owner   = THIS_MODULE,
2071         .open    = gfs2_sbstats_open,
2072         .read    = seq_read,
2073         .llseek  = seq_lseek,
2074         .release = seq_release_private,
2075 };
2076 
2077 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
2078 {
2079         sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
2080         if (!sdp->debugfs_dir)
2081                 return -ENOMEM;
2082         sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
2083                                                          S_IFREG | S_IRUGO,
2084                                                          sdp->debugfs_dir, sdp,
2085                                                          &gfs2_glocks_fops);
2086         if (!sdp->debugfs_dentry_glocks)
2087                 goto fail;
2088 
2089         sdp->debugfs_dentry_glstats = debugfs_create_file("glstats",
2090                                                         S_IFREG | S_IRUGO,
2091                                                         sdp->debugfs_dir, sdp,
2092                                                         &gfs2_glstats_fops);
2093         if (!sdp->debugfs_dentry_glstats)
2094                 goto fail;
2095 
2096         sdp->debugfs_dentry_sbstats = debugfs_create_file("sbstats",
2097                                                         S_IFREG | S_IRUGO,
2098                                                         sdp->debugfs_dir, sdp,
2099                                                         &gfs2_sbstats_fops);
2100         if (!sdp->debugfs_dentry_sbstats)
2101                 goto fail;
2102 
2103         return 0;
2104 fail:
2105         gfs2_delete_debugfs_file(sdp);
2106         return -ENOMEM;
2107 }
2108 
2109 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
2110 {
2111         if (sdp->debugfs_dir) {
2112                 if (sdp->debugfs_dentry_glocks) {
2113                         debugfs_remove(sdp->debugfs_dentry_glocks);
2114                         sdp->debugfs_dentry_glocks = NULL;
2115                 }
2116                 if (sdp->debugfs_dentry_glstats) {
2117                         debugfs_remove(sdp->debugfs_dentry_glstats);
2118                         sdp->debugfs_dentry_glstats = NULL;
2119                 }
2120                 if (sdp->debugfs_dentry_sbstats) {
2121                         debugfs_remove(sdp->debugfs_dentry_sbstats);
2122                         sdp->debugfs_dentry_sbstats = NULL;
2123                 }
2124                 debugfs_remove(sdp->debugfs_dir);
2125                 sdp->debugfs_dir = NULL;
2126         }
2127 }
2128 
2129 int gfs2_register_debugfs(void)
2130 {
2131         gfs2_root = debugfs_create_dir("gfs2", NULL);
2132         return gfs2_root ? 0 : -ENOMEM;
2133 }
2134 
2135 void gfs2_unregister_debugfs(void)
2136 {
2137         debugfs_remove(gfs2_root);
2138         gfs2_root = NULL;
2139 }
2140 

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