add hlist_bl_lock/unlock helpers
[linux-2.6.git] / fs / gfs2 / glock.c
1 /*
2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
3  * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
4  *
5  * This copyrighted material is made available to anyone wishing to use,
6  * modify, copy, or redistribute it subject to the terms and conditions
7  * of the GNU General Public License version 2.
8  */
9
10 #include <linux/sched.h>
11 #include <linux/slab.h>
12 #include <linux/spinlock.h>
13 #include <linux/buffer_head.h>
14 #include <linux/delay.h>
15 #include <linux/sort.h>
16 #include <linux/jhash.h>
17 #include <linux/kallsyms.h>
18 #include <linux/gfs2_ondisk.h>
19 #include <linux/list.h>
20 #include <linux/wait.h>
21 #include <linux/module.h>
22 #include <asm/uaccess.h>
23 #include <linux/seq_file.h>
24 #include <linux/debugfs.h>
25 #include <linux/kthread.h>
26 #include <linux/freezer.h>
27 #include <linux/workqueue.h>
28 #include <linux/jiffies.h>
29 #include <linux/rcupdate.h>
30 #include <linux/rculist_bl.h>
31 #include <linux/bit_spinlock.h>
32
33 #include "gfs2.h"
34 #include "incore.h"
35 #include "glock.h"
36 #include "glops.h"
37 #include "inode.h"
38 #include "lops.h"
39 #include "meta_io.h"
40 #include "quota.h"
41 #include "super.h"
42 #include "util.h"
43 #include "bmap.h"
44 #define CREATE_TRACE_POINTS
45 #include "trace_gfs2.h"
46
47 struct gfs2_glock_iter {
48         int hash;                       /* hash bucket index         */
49         struct gfs2_sbd *sdp;           /* incore superblock         */
50         struct gfs2_glock *gl;          /* current glock struct      */
51         char string[512];               /* scratch space             */
52 };
53
54 typedef void (*glock_examiner) (struct gfs2_glock * gl);
55
56 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl);
57 #define GLOCK_BUG_ON(gl,x) do { if (unlikely(x)) { __dump_glock(NULL, gl); BUG(); } } while(0)
58 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
59
60 static struct dentry *gfs2_root;
61 static struct workqueue_struct *glock_workqueue;
62 struct workqueue_struct *gfs2_delete_workqueue;
63 static LIST_HEAD(lru_list);
64 static atomic_t lru_count = ATOMIC_INIT(0);
65 static DEFINE_SPINLOCK(lru_lock);
66
67 #define GFS2_GL_HASH_SHIFT      15
68 #define GFS2_GL_HASH_SIZE       (1 << GFS2_GL_HASH_SHIFT)
69 #define GFS2_GL_HASH_MASK       (GFS2_GL_HASH_SIZE - 1)
70
71 static struct hlist_bl_head gl_hash_table[GFS2_GL_HASH_SIZE];
72 static struct dentry *gfs2_root;
73
74 /**
75  * gl_hash() - Turn glock number into hash bucket number
76  * @lock: The glock number
77  *
78  * Returns: The number of the corresponding hash bucket
79  */
80
81 static unsigned int gl_hash(const struct gfs2_sbd *sdp,
82                             const struct lm_lockname *name)
83 {
84         unsigned int h;
85
86         h = jhash(&name->ln_number, sizeof(u64), 0);
87         h = jhash(&name->ln_type, sizeof(unsigned int), h);
88         h = jhash(&sdp, sizeof(struct gfs2_sbd *), h);
89         h &= GFS2_GL_HASH_MASK;
90
91         return h;
92 }
93
94 static inline void spin_lock_bucket(unsigned int hash)
95 {
96         hlist_bl_lock(&gl_hash_table[hash]);
97 }
98
99 static inline void spin_unlock_bucket(unsigned int hash)
100 {
101         hlist_bl_unlock(&gl_hash_table[hash]);
102 }
103
104 static void gfs2_glock_dealloc(struct rcu_head *rcu)
105 {
106         struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu);
107
108         if (gl->gl_ops->go_flags & GLOF_ASPACE)
109                 kmem_cache_free(gfs2_glock_aspace_cachep, gl);
110         else
111                 kmem_cache_free(gfs2_glock_cachep, gl);
112 }
113
114 void gfs2_glock_free(struct gfs2_glock *gl)
115 {
116         struct gfs2_sbd *sdp = gl->gl_sbd;
117
118         call_rcu(&gl->gl_rcu, gfs2_glock_dealloc);
119         if (atomic_dec_and_test(&sdp->sd_glock_disposal))
120                 wake_up(&sdp->sd_glock_wait);
121 }
122
123 /**
124  * gfs2_glock_hold() - increment reference count on glock
125  * @gl: The glock to hold
126  *
127  */
128
129 void gfs2_glock_hold(struct gfs2_glock *gl)
130 {
131         GLOCK_BUG_ON(gl, atomic_read(&gl->gl_ref) == 0);
132         atomic_inc(&gl->gl_ref);
133 }
134
135 /**
136  * demote_ok - Check to see if it's ok to unlock a glock
137  * @gl: the glock
138  *
139  * Returns: 1 if it's ok
140  */
141
142 static int demote_ok(const struct gfs2_glock *gl)
143 {
144         const struct gfs2_glock_operations *glops = gl->gl_ops;
145
146         /* assert_spin_locked(&gl->gl_spin); */
147
148         if (gl->gl_state == LM_ST_UNLOCKED)
149                 return 0;
150         if (test_bit(GLF_LFLUSH, &gl->gl_flags))
151                 return 0;
152         if ((gl->gl_name.ln_type != LM_TYPE_INODE) &&
153             !list_empty(&gl->gl_holders))
154                 return 0;
155         if (glops->go_demote_ok)
156                 return glops->go_demote_ok(gl);
157         return 1;
158 }
159
160
161 /**
162  * __gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
163  * @gl: the glock
164  *
165  * If the glock is demotable, then we add it (or move it) to the end
166  * of the glock LRU list.
167  */
168
169 static void __gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
170 {
171         if (demote_ok(gl)) {
172                 spin_lock(&lru_lock);
173
174                 if (!list_empty(&gl->gl_lru))
175                         list_del_init(&gl->gl_lru);
176                 else
177                         atomic_inc(&lru_count);
178
179                 list_add_tail(&gl->gl_lru, &lru_list);
180                 spin_unlock(&lru_lock);
181         }
182 }
183
184 void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
185 {
186         spin_lock(&gl->gl_spin);
187         __gfs2_glock_schedule_for_reclaim(gl);
188         spin_unlock(&gl->gl_spin);
189 }
190
191 /**
192  * gfs2_glock_put_nolock() - Decrement reference count on glock
193  * @gl: The glock to put
194  *
195  * This function should only be used if the caller has its own reference
196  * to the glock, in addition to the one it is dropping.
197  */
198
199 void gfs2_glock_put_nolock(struct gfs2_glock *gl)
200 {
201         if (atomic_dec_and_test(&gl->gl_ref))
202                 GLOCK_BUG_ON(gl, 1);
203 }
204
205 /**
206  * gfs2_glock_put() - Decrement reference count on glock
207  * @gl: The glock to put
208  *
209  */
210
211 void gfs2_glock_put(struct gfs2_glock *gl)
212 {
213         struct gfs2_sbd *sdp = gl->gl_sbd;
214         struct address_space *mapping = gfs2_glock2aspace(gl);
215
216         if (atomic_dec_and_test(&gl->gl_ref)) {
217                 spin_lock_bucket(gl->gl_hash);
218                 hlist_bl_del_rcu(&gl->gl_list);
219                 spin_unlock_bucket(gl->gl_hash);
220                 spin_lock(&lru_lock);
221                 if (!list_empty(&gl->gl_lru)) {
222                         list_del_init(&gl->gl_lru);
223                         atomic_dec(&lru_count);
224                 }
225                 spin_unlock(&lru_lock);
226                 GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
227                 GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
228                 trace_gfs2_glock_put(gl);
229                 sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
230         }
231 }
232
233 /**
234  * search_bucket() - Find struct gfs2_glock by lock number
235  * @bucket: the bucket to search
236  * @name: The lock name
237  *
238  * Returns: NULL, or the struct gfs2_glock with the requested number
239  */
240
241 static struct gfs2_glock *search_bucket(unsigned int hash,
242                                         const struct gfs2_sbd *sdp,
243                                         const struct lm_lockname *name)
244 {
245         struct gfs2_glock *gl;
246         struct hlist_bl_node *h;
247
248         hlist_bl_for_each_entry_rcu(gl, h, &gl_hash_table[hash], gl_list) {
249                 if (!lm_name_equal(&gl->gl_name, name))
250                         continue;
251                 if (gl->gl_sbd != sdp)
252                         continue;
253                 if (atomic_inc_not_zero(&gl->gl_ref))
254                         return gl;
255         }
256
257         return NULL;
258 }
259
260 /**
261  * may_grant - check if its ok to grant a new lock
262  * @gl: The glock
263  * @gh: The lock request which we wish to grant
264  *
265  * Returns: true if its ok to grant the lock
266  */
267
268 static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
269 {
270         const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
271         if ((gh->gh_state == LM_ST_EXCLUSIVE ||
272              gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
273                 return 0;
274         if (gl->gl_state == gh->gh_state)
275                 return 1;
276         if (gh->gh_flags & GL_EXACT)
277                 return 0;
278         if (gl->gl_state == LM_ST_EXCLUSIVE) {
279                 if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
280                         return 1;
281                 if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
282                         return 1;
283         }
284         if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
285                 return 1;
286         return 0;
287 }
288
289 static void gfs2_holder_wake(struct gfs2_holder *gh)
290 {
291         clear_bit(HIF_WAIT, &gh->gh_iflags);
292         smp_mb__after_clear_bit();
293         wake_up_bit(&gh->gh_iflags, HIF_WAIT);
294 }
295
296 /**
297  * do_error - Something unexpected has happened during a lock request
298  *
299  */
300
301 static inline void do_error(struct gfs2_glock *gl, const int ret)
302 {
303         struct gfs2_holder *gh, *tmp;
304
305         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
306                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
307                         continue;
308                 if (ret & LM_OUT_ERROR)
309                         gh->gh_error = -EIO;
310                 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
311                         gh->gh_error = GLR_TRYFAILED;
312                 else
313                         continue;
314                 list_del_init(&gh->gh_list);
315                 trace_gfs2_glock_queue(gh, 0);
316                 gfs2_holder_wake(gh);
317         }
318 }
319
320 /**
321  * do_promote - promote as many requests as possible on the current queue
322  * @gl: The glock
323  * 
324  * Returns: 1 if there is a blocked holder at the head of the list, or 2
325  *          if a type specific operation is underway.
326  */
327
328 static int do_promote(struct gfs2_glock *gl)
329 __releases(&gl->gl_spin)
330 __acquires(&gl->gl_spin)
331 {
332         const struct gfs2_glock_operations *glops = gl->gl_ops;
333         struct gfs2_holder *gh, *tmp;
334         int ret;
335
336 restart:
337         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
338                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
339                         continue;
340                 if (may_grant(gl, gh)) {
341                         if (gh->gh_list.prev == &gl->gl_holders &&
342                             glops->go_lock) {
343                                 spin_unlock(&gl->gl_spin);
344                                 /* FIXME: eliminate this eventually */
345                                 ret = glops->go_lock(gh);
346                                 spin_lock(&gl->gl_spin);
347                                 if (ret) {
348                                         if (ret == 1)
349                                                 return 2;
350                                         gh->gh_error = ret;
351                                         list_del_init(&gh->gh_list);
352                                         trace_gfs2_glock_queue(gh, 0);
353                                         gfs2_holder_wake(gh);
354                                         goto restart;
355                                 }
356                                 set_bit(HIF_HOLDER, &gh->gh_iflags);
357                                 trace_gfs2_promote(gh, 1);
358                                 gfs2_holder_wake(gh);
359                                 goto restart;
360                         }
361                         set_bit(HIF_HOLDER, &gh->gh_iflags);
362                         trace_gfs2_promote(gh, 0);
363                         gfs2_holder_wake(gh);
364                         continue;
365                 }
366                 if (gh->gh_list.prev == &gl->gl_holders)
367                         return 1;
368                 do_error(gl, 0);
369                 break;
370         }
371         return 0;
372 }
373
374 /**
375  * find_first_waiter - find the first gh that's waiting for the glock
376  * @gl: the glock
377  */
378
379 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
380 {
381         struct gfs2_holder *gh;
382
383         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
384                 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
385                         return gh;
386         }
387         return NULL;
388 }
389
390 /**
391  * state_change - record that the glock is now in a different state
392  * @gl: the glock
393  * @new_state the new state
394  *
395  */
396
397 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
398 {
399         int held1, held2;
400
401         held1 = (gl->gl_state != LM_ST_UNLOCKED);
402         held2 = (new_state != LM_ST_UNLOCKED);
403
404         if (held1 != held2) {
405                 if (held2)
406                         gfs2_glock_hold(gl);
407                 else
408                         gfs2_glock_put_nolock(gl);
409         }
410         if (held1 && held2 && list_empty(&gl->gl_holders))
411                 clear_bit(GLF_QUEUED, &gl->gl_flags);
412
413         gl->gl_state = new_state;
414         gl->gl_tchange = jiffies;
415 }
416
417 static void gfs2_demote_wake(struct gfs2_glock *gl)
418 {
419         gl->gl_demote_state = LM_ST_EXCLUSIVE;
420         clear_bit(GLF_DEMOTE, &gl->gl_flags);
421         smp_mb__after_clear_bit();
422         wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
423 }
424
425 /**
426  * finish_xmote - The DLM has replied to one of our lock requests
427  * @gl: The glock
428  * @ret: The status from the DLM
429  *
430  */
431
432 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
433 {
434         const struct gfs2_glock_operations *glops = gl->gl_ops;
435         struct gfs2_holder *gh;
436         unsigned state = ret & LM_OUT_ST_MASK;
437         int rv;
438
439         spin_lock(&gl->gl_spin);
440         trace_gfs2_glock_state_change(gl, state);
441         state_change(gl, state);
442         gh = find_first_waiter(gl);
443
444         /* Demote to UN request arrived during demote to SH or DF */
445         if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
446             state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
447                 gl->gl_target = LM_ST_UNLOCKED;
448
449         /* Check for state != intended state */
450         if (unlikely(state != gl->gl_target)) {
451                 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
452                         /* move to back of queue and try next entry */
453                         if (ret & LM_OUT_CANCELED) {
454                                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
455                                         list_move_tail(&gh->gh_list, &gl->gl_holders);
456                                 gh = find_first_waiter(gl);
457                                 gl->gl_target = gh->gh_state;
458                                 goto retry;
459                         }
460                         /* Some error or failed "try lock" - report it */
461                         if ((ret & LM_OUT_ERROR) ||
462                             (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
463                                 gl->gl_target = gl->gl_state;
464                                 do_error(gl, ret);
465                                 goto out;
466                         }
467                 }
468                 switch(state) {
469                 /* Unlocked due to conversion deadlock, try again */
470                 case LM_ST_UNLOCKED:
471 retry:
472                         do_xmote(gl, gh, gl->gl_target);
473                         break;
474                 /* Conversion fails, unlock and try again */
475                 case LM_ST_SHARED:
476                 case LM_ST_DEFERRED:
477                         do_xmote(gl, gh, LM_ST_UNLOCKED);
478                         break;
479                 default: /* Everything else */
480                         printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
481                         GLOCK_BUG_ON(gl, 1);
482                 }
483                 spin_unlock(&gl->gl_spin);
484                 return;
485         }
486
487         /* Fast path - we got what we asked for */
488         if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
489                 gfs2_demote_wake(gl);
490         if (state != LM_ST_UNLOCKED) {
491                 if (glops->go_xmote_bh) {
492                         spin_unlock(&gl->gl_spin);
493                         rv = glops->go_xmote_bh(gl, gh);
494                         spin_lock(&gl->gl_spin);
495                         if (rv) {
496                                 do_error(gl, rv);
497                                 goto out;
498                         }
499                 }
500                 rv = do_promote(gl);
501                 if (rv == 2)
502                         goto out_locked;
503         }
504 out:
505         clear_bit(GLF_LOCK, &gl->gl_flags);
506 out_locked:
507         spin_unlock(&gl->gl_spin);
508 }
509
510 /**
511  * do_xmote - Calls the DLM to change the state of a lock
512  * @gl: The lock state
513  * @gh: The holder (only for promotes)
514  * @target: The target lock state
515  *
516  */
517
518 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
519 __releases(&gl->gl_spin)
520 __acquires(&gl->gl_spin)
521 {
522         const struct gfs2_glock_operations *glops = gl->gl_ops;
523         struct gfs2_sbd *sdp = gl->gl_sbd;
524         unsigned int lck_flags = gh ? gh->gh_flags : 0;
525         int ret;
526
527         lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
528                       LM_FLAG_PRIORITY);
529         GLOCK_BUG_ON(gl, gl->gl_state == target);
530         GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
531         if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
532             glops->go_inval) {
533                 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
534                 do_error(gl, 0); /* Fail queued try locks */
535         }
536         gl->gl_req = target;
537         spin_unlock(&gl->gl_spin);
538         if (glops->go_xmote_th)
539                 glops->go_xmote_th(gl);
540         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
541                 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
542         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
543
544         gfs2_glock_hold(gl);
545         if (target != LM_ST_UNLOCKED && (gl->gl_state == LM_ST_SHARED ||
546             gl->gl_state == LM_ST_DEFERRED) &&
547             !(lck_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
548                 lck_flags |= LM_FLAG_TRY_1CB;
549
550         if (sdp->sd_lockstruct.ls_ops->lm_lock) {
551                 /* lock_dlm */
552                 ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
553                 GLOCK_BUG_ON(gl, ret);
554         } else { /* lock_nolock */
555                 finish_xmote(gl, target);
556                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
557                         gfs2_glock_put(gl);
558         }
559
560         spin_lock(&gl->gl_spin);
561 }
562
563 /**
564  * find_first_holder - find the first "holder" gh
565  * @gl: the glock
566  */
567
568 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
569 {
570         struct gfs2_holder *gh;
571
572         if (!list_empty(&gl->gl_holders)) {
573                 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
574                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
575                         return gh;
576         }
577         return NULL;
578 }
579
580 /**
581  * run_queue - do all outstanding tasks related to a glock
582  * @gl: The glock in question
583  * @nonblock: True if we must not block in run_queue
584  *
585  */
586
587 static void run_queue(struct gfs2_glock *gl, const int nonblock)
588 __releases(&gl->gl_spin)
589 __acquires(&gl->gl_spin)
590 {
591         struct gfs2_holder *gh = NULL;
592         int ret;
593
594         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
595                 return;
596
597         GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
598
599         if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
600             gl->gl_demote_state != gl->gl_state) {
601                 if (find_first_holder(gl))
602                         goto out_unlock;
603                 if (nonblock)
604                         goto out_sched;
605                 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
606                 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
607                 gl->gl_target = gl->gl_demote_state;
608         } else {
609                 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
610                         gfs2_demote_wake(gl);
611                 ret = do_promote(gl);
612                 if (ret == 0)
613                         goto out_unlock;
614                 if (ret == 2)
615                         goto out;
616                 gh = find_first_waiter(gl);
617                 gl->gl_target = gh->gh_state;
618                 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
619                         do_error(gl, 0); /* Fail queued try locks */
620         }
621         do_xmote(gl, gh, gl->gl_target);
622 out:
623         return;
624
625 out_sched:
626         clear_bit(GLF_LOCK, &gl->gl_flags);
627         smp_mb__after_clear_bit();
628         gfs2_glock_hold(gl);
629         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
630                 gfs2_glock_put_nolock(gl);
631         return;
632
633 out_unlock:
634         clear_bit(GLF_LOCK, &gl->gl_flags);
635         smp_mb__after_clear_bit();
636         return;
637 }
638
639 static void delete_work_func(struct work_struct *work)
640 {
641         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
642         struct gfs2_sbd *sdp = gl->gl_sbd;
643         struct gfs2_inode *ip;
644         struct inode *inode;
645         u64 no_addr = gl->gl_name.ln_number;
646
647         ip = gl->gl_object;
648         /* Note: Unsafe to dereference ip as we don't hold right refs/locks */
649
650         if (ip)
651                 inode = gfs2_ilookup(sdp->sd_vfs, no_addr);
652         else
653                 inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
654         if (inode && !IS_ERR(inode)) {
655                 d_prune_aliases(inode);
656                 iput(inode);
657         }
658         gfs2_glock_put(gl);
659 }
660
661 static void glock_work_func(struct work_struct *work)
662 {
663         unsigned long delay = 0;
664         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
665         int drop_ref = 0;
666
667         if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
668                 finish_xmote(gl, gl->gl_reply);
669                 drop_ref = 1;
670         }
671         spin_lock(&gl->gl_spin);
672         if (test_and_clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
673             gl->gl_state != LM_ST_UNLOCKED &&
674             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
675                 unsigned long holdtime, now = jiffies;
676                 holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
677                 if (time_before(now, holdtime))
678                         delay = holdtime - now;
679                 set_bit(delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE, &gl->gl_flags);
680         }
681         run_queue(gl, 0);
682         spin_unlock(&gl->gl_spin);
683         if (!delay ||
684             queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
685                 gfs2_glock_put(gl);
686         if (drop_ref)
687                 gfs2_glock_put(gl);
688 }
689
690 /**
691  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
692  * @sdp: The GFS2 superblock
693  * @number: the lock number
694  * @glops: The glock_operations to use
695  * @create: If 0, don't create the glock if it doesn't exist
696  * @glp: the glock is returned here
697  *
698  * This does not lock a glock, just finds/creates structures for one.
699  *
700  * Returns: errno
701  */
702
703 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
704                    const struct gfs2_glock_operations *glops, int create,
705                    struct gfs2_glock **glp)
706 {
707         struct super_block *s = sdp->sd_vfs;
708         struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
709         struct gfs2_glock *gl, *tmp;
710         unsigned int hash = gl_hash(sdp, &name);
711         struct address_space *mapping;
712         struct kmem_cache *cachep;
713
714         rcu_read_lock();
715         gl = search_bucket(hash, sdp, &name);
716         rcu_read_unlock();
717
718         *glp = gl;
719         if (gl)
720                 return 0;
721         if (!create)
722                 return -ENOENT;
723
724         if (glops->go_flags & GLOF_ASPACE)
725                 cachep = gfs2_glock_aspace_cachep;
726         else
727                 cachep = gfs2_glock_cachep;
728         gl = kmem_cache_alloc(cachep, GFP_KERNEL);
729         if (!gl)
730                 return -ENOMEM;
731
732         atomic_inc(&sdp->sd_glock_disposal);
733         gl->gl_flags = 0;
734         gl->gl_name = name;
735         atomic_set(&gl->gl_ref, 1);
736         gl->gl_state = LM_ST_UNLOCKED;
737         gl->gl_target = LM_ST_UNLOCKED;
738         gl->gl_demote_state = LM_ST_EXCLUSIVE;
739         gl->gl_hash = hash;
740         gl->gl_ops = glops;
741         snprintf(gl->gl_strname, GDLM_STRNAME_BYTES, "%8x%16llx", name.ln_type, (unsigned long long)number);
742         memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
743         gl->gl_lksb.sb_lvbptr = gl->gl_lvb;
744         gl->gl_tchange = jiffies;
745         gl->gl_object = NULL;
746         gl->gl_sbd = sdp;
747         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
748         INIT_WORK(&gl->gl_delete, delete_work_func);
749
750         mapping = gfs2_glock2aspace(gl);
751         if (mapping) {
752                 mapping->a_ops = &gfs2_meta_aops;
753                 mapping->host = s->s_bdev->bd_inode;
754                 mapping->flags = 0;
755                 mapping_set_gfp_mask(mapping, GFP_NOFS);
756                 mapping->assoc_mapping = NULL;
757                 mapping->backing_dev_info = s->s_bdi;
758                 mapping->writeback_index = 0;
759         }
760
761         spin_lock_bucket(hash);
762         tmp = search_bucket(hash, sdp, &name);
763         if (tmp) {
764                 spin_unlock_bucket(hash);
765                 kmem_cache_free(cachep, gl);
766                 atomic_dec(&sdp->sd_glock_disposal);
767                 gl = tmp;
768         } else {
769                 hlist_bl_add_head_rcu(&gl->gl_list, &gl_hash_table[hash]);
770                 spin_unlock_bucket(hash);
771         }
772
773         *glp = gl;
774
775         return 0;
776 }
777
778 /**
779  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
780  * @gl: the glock
781  * @state: the state we're requesting
782  * @flags: the modifier flags
783  * @gh: the holder structure
784  *
785  */
786
787 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
788                       struct gfs2_holder *gh)
789 {
790         INIT_LIST_HEAD(&gh->gh_list);
791         gh->gh_gl = gl;
792         gh->gh_ip = (unsigned long)__builtin_return_address(0);
793         gh->gh_owner_pid = get_pid(task_pid(current));
794         gh->gh_state = state;
795         gh->gh_flags = flags;
796         gh->gh_error = 0;
797         gh->gh_iflags = 0;
798         gfs2_glock_hold(gl);
799 }
800
801 /**
802  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
803  * @state: the state we're requesting
804  * @flags: the modifier flags
805  * @gh: the holder structure
806  *
807  * Don't mess with the glock.
808  *
809  */
810
811 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
812 {
813         gh->gh_state = state;
814         gh->gh_flags = flags;
815         gh->gh_iflags = 0;
816         gh->gh_ip = (unsigned long)__builtin_return_address(0);
817         if (gh->gh_owner_pid)
818                 put_pid(gh->gh_owner_pid);
819         gh->gh_owner_pid = get_pid(task_pid(current));
820 }
821
822 /**
823  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
824  * @gh: the holder structure
825  *
826  */
827
828 void gfs2_holder_uninit(struct gfs2_holder *gh)
829 {
830         put_pid(gh->gh_owner_pid);
831         gfs2_glock_put(gh->gh_gl);
832         gh->gh_gl = NULL;
833         gh->gh_ip = 0;
834 }
835
836 /**
837  * gfs2_glock_holder_wait
838  * @word: unused
839  *
840  * This function and gfs2_glock_demote_wait both show up in the WCHAN
841  * field. Thus I've separated these otherwise identical functions in
842  * order to be more informative to the user.
843  */
844
845 static int gfs2_glock_holder_wait(void *word)
846 {
847         schedule();
848         return 0;
849 }
850
851 static int gfs2_glock_demote_wait(void *word)
852 {
853         schedule();
854         return 0;
855 }
856
857 static void wait_on_holder(struct gfs2_holder *gh)
858 {
859         might_sleep();
860         wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
861 }
862
863 static void wait_on_demote(struct gfs2_glock *gl)
864 {
865         might_sleep();
866         wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
867 }
868
869 /**
870  * handle_callback - process a demote request
871  * @gl: the glock
872  * @state: the state the caller wants us to change to
873  *
874  * There are only two requests that we are going to see in actual
875  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
876  */
877
878 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
879                             unsigned long delay)
880 {
881         int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
882
883         set_bit(bit, &gl->gl_flags);
884         if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
885                 gl->gl_demote_state = state;
886                 gl->gl_demote_time = jiffies;
887         } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
888                         gl->gl_demote_state != state) {
889                 gl->gl_demote_state = LM_ST_UNLOCKED;
890         }
891         if (gl->gl_ops->go_callback)
892                 gl->gl_ops->go_callback(gl);
893         trace_gfs2_demote_rq(gl);
894 }
895
896 /**
897  * gfs2_glock_wait - wait on a glock acquisition
898  * @gh: the glock holder
899  *
900  * Returns: 0 on success
901  */
902
903 int gfs2_glock_wait(struct gfs2_holder *gh)
904 {
905         wait_on_holder(gh);
906         return gh->gh_error;
907 }
908
909 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
910 {
911         struct va_format vaf;
912         va_list args;
913
914         va_start(args, fmt);
915
916         if (seq) {
917                 struct gfs2_glock_iter *gi = seq->private;
918                 vsprintf(gi->string, fmt, args);
919                 seq_printf(seq, gi->string);
920         } else {
921                 vaf.fmt = fmt;
922                 vaf.va = &args;
923
924                 printk(KERN_ERR " %pV", &vaf);
925         }
926
927         va_end(args);
928 }
929
930 /**
931  * add_to_queue - Add a holder to the wait queue (but look for recursion)
932  * @gh: the holder structure to add
933  *
934  * Eventually we should move the recursive locking trap to a
935  * debugging option or something like that. This is the fast
936  * path and needs to have the minimum number of distractions.
937  * 
938  */
939
940 static inline void add_to_queue(struct gfs2_holder *gh)
941 __releases(&gl->gl_spin)
942 __acquires(&gl->gl_spin)
943 {
944         struct gfs2_glock *gl = gh->gh_gl;
945         struct gfs2_sbd *sdp = gl->gl_sbd;
946         struct list_head *insert_pt = NULL;
947         struct gfs2_holder *gh2;
948         int try_lock = 0;
949
950         BUG_ON(gh->gh_owner_pid == NULL);
951         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
952                 BUG();
953
954         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
955                 if (test_bit(GLF_LOCK, &gl->gl_flags))
956                         try_lock = 1;
957                 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
958                         goto fail;
959         }
960
961         list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
962                 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
963                     (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
964                         goto trap_recursive;
965                 if (try_lock &&
966                     !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
967                     !may_grant(gl, gh)) {
968 fail:
969                         gh->gh_error = GLR_TRYFAILED;
970                         gfs2_holder_wake(gh);
971                         return;
972                 }
973                 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
974                         continue;
975                 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
976                         insert_pt = &gh2->gh_list;
977         }
978         set_bit(GLF_QUEUED, &gl->gl_flags);
979         trace_gfs2_glock_queue(gh, 1);
980         if (likely(insert_pt == NULL)) {
981                 list_add_tail(&gh->gh_list, &gl->gl_holders);
982                 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
983                         goto do_cancel;
984                 return;
985         }
986         list_add_tail(&gh->gh_list, insert_pt);
987 do_cancel:
988         gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
989         if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
990                 spin_unlock(&gl->gl_spin);
991                 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
992                         sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
993                 spin_lock(&gl->gl_spin);
994         }
995         return;
996
997 trap_recursive:
998         print_symbol(KERN_ERR "original: %s\n", gh2->gh_ip);
999         printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
1000         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1001                gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
1002         print_symbol(KERN_ERR "new: %s\n", gh->gh_ip);
1003         printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
1004         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1005                gh->gh_gl->gl_name.ln_type, gh->gh_state);
1006         __dump_glock(NULL, gl);
1007         BUG();
1008 }
1009
1010 /**
1011  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1012  * @gh: the holder structure
1013  *
1014  * if (gh->gh_flags & GL_ASYNC), this never returns an error
1015  *
1016  * Returns: 0, GLR_TRYFAILED, or errno on failure
1017  */
1018
1019 int gfs2_glock_nq(struct gfs2_holder *gh)
1020 {
1021         struct gfs2_glock *gl = gh->gh_gl;
1022         struct gfs2_sbd *sdp = gl->gl_sbd;
1023         int error = 0;
1024
1025         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
1026                 return -EIO;
1027
1028         spin_lock(&gl->gl_spin);
1029         add_to_queue(gh);
1030         if ((LM_FLAG_NOEXP & gh->gh_flags) &&
1031             test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1032                 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1033         run_queue(gl, 1);
1034         spin_unlock(&gl->gl_spin);
1035
1036         if (!(gh->gh_flags & GL_ASYNC))
1037                 error = gfs2_glock_wait(gh);
1038
1039         return error;
1040 }
1041
1042 /**
1043  * gfs2_glock_poll - poll to see if an async request has been completed
1044  * @gh: the holder
1045  *
1046  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1047  */
1048
1049 int gfs2_glock_poll(struct gfs2_holder *gh)
1050 {
1051         return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1052 }
1053
1054 /**
1055  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1056  * @gh: the glock holder
1057  *
1058  */
1059
1060 void gfs2_glock_dq(struct gfs2_holder *gh)
1061 {
1062         struct gfs2_glock *gl = gh->gh_gl;
1063         const struct gfs2_glock_operations *glops = gl->gl_ops;
1064         unsigned delay = 0;
1065         int fast_path = 0;
1066
1067         spin_lock(&gl->gl_spin);
1068         if (gh->gh_flags & GL_NOCACHE)
1069                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1070
1071         list_del_init(&gh->gh_list);
1072         if (find_first_holder(gl) == NULL) {
1073                 if (glops->go_unlock) {
1074                         GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1075                         spin_unlock(&gl->gl_spin);
1076                         glops->go_unlock(gh);
1077                         spin_lock(&gl->gl_spin);
1078                         clear_bit(GLF_LOCK, &gl->gl_flags);
1079                 }
1080                 if (list_empty(&gl->gl_holders) &&
1081                     !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1082                     !test_bit(GLF_DEMOTE, &gl->gl_flags))
1083                         fast_path = 1;
1084         }
1085         __gfs2_glock_schedule_for_reclaim(gl);
1086         trace_gfs2_glock_queue(gh, 0);
1087         spin_unlock(&gl->gl_spin);
1088         if (likely(fast_path))
1089                 return;
1090
1091         gfs2_glock_hold(gl);
1092         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1093             !test_bit(GLF_DEMOTE, &gl->gl_flags))
1094                 delay = gl->gl_ops->go_min_hold_time;
1095         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1096                 gfs2_glock_put(gl);
1097 }
1098
1099 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1100 {
1101         struct gfs2_glock *gl = gh->gh_gl;
1102         gfs2_glock_dq(gh);
1103         wait_on_demote(gl);
1104 }
1105
1106 /**
1107  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1108  * @gh: the holder structure
1109  *
1110  */
1111
1112 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1113 {
1114         gfs2_glock_dq(gh);
1115         gfs2_holder_uninit(gh);
1116 }
1117
1118 /**
1119  * gfs2_glock_nq_num - acquire a glock based on lock number
1120  * @sdp: the filesystem
1121  * @number: the lock number
1122  * @glops: the glock operations for the type of glock
1123  * @state: the state to acquire the glock in
1124  * @flags: modifier flags for the acquisition
1125  * @gh: the struct gfs2_holder
1126  *
1127  * Returns: errno
1128  */
1129
1130 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1131                       const struct gfs2_glock_operations *glops,
1132                       unsigned int state, int flags, struct gfs2_holder *gh)
1133 {
1134         struct gfs2_glock *gl;
1135         int error;
1136
1137         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1138         if (!error) {
1139                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1140                 gfs2_glock_put(gl);
1141         }
1142
1143         return error;
1144 }
1145
1146 /**
1147  * glock_compare - Compare two struct gfs2_glock structures for sorting
1148  * @arg_a: the first structure
1149  * @arg_b: the second structure
1150  *
1151  */
1152
1153 static int glock_compare(const void *arg_a, const void *arg_b)
1154 {
1155         const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1156         const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1157         const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1158         const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1159
1160         if (a->ln_number > b->ln_number)
1161                 return 1;
1162         if (a->ln_number < b->ln_number)
1163                 return -1;
1164         BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1165         return 0;
1166 }
1167
1168 /**
1169  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1170  * @num_gh: the number of structures
1171  * @ghs: an array of struct gfs2_holder structures
1172  *
1173  * Returns: 0 on success (all glocks acquired),
1174  *          errno on failure (no glocks acquired)
1175  */
1176
1177 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1178                      struct gfs2_holder **p)
1179 {
1180         unsigned int x;
1181         int error = 0;
1182
1183         for (x = 0; x < num_gh; x++)
1184                 p[x] = &ghs[x];
1185
1186         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1187
1188         for (x = 0; x < num_gh; x++) {
1189                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1190
1191                 error = gfs2_glock_nq(p[x]);
1192                 if (error) {
1193                         while (x--)
1194                                 gfs2_glock_dq(p[x]);
1195                         break;
1196                 }
1197         }
1198
1199         return error;
1200 }
1201
1202 /**
1203  * gfs2_glock_nq_m - acquire multiple glocks
1204  * @num_gh: the number of structures
1205  * @ghs: an array of struct gfs2_holder structures
1206  *
1207  *
1208  * Returns: 0 on success (all glocks acquired),
1209  *          errno on failure (no glocks acquired)
1210  */
1211
1212 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1213 {
1214         struct gfs2_holder *tmp[4];
1215         struct gfs2_holder **pph = tmp;
1216         int error = 0;
1217
1218         switch(num_gh) {
1219         case 0:
1220                 return 0;
1221         case 1:
1222                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1223                 return gfs2_glock_nq(ghs);
1224         default:
1225                 if (num_gh <= 4)
1226                         break;
1227                 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1228                 if (!pph)
1229                         return -ENOMEM;
1230         }
1231
1232         error = nq_m_sync(num_gh, ghs, pph);
1233
1234         if (pph != tmp)
1235                 kfree(pph);
1236
1237         return error;
1238 }
1239
1240 /**
1241  * gfs2_glock_dq_m - release multiple glocks
1242  * @num_gh: the number of structures
1243  * @ghs: an array of struct gfs2_holder structures
1244  *
1245  */
1246
1247 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1248 {
1249         while (num_gh--)
1250                 gfs2_glock_dq(&ghs[num_gh]);
1251 }
1252
1253 /**
1254  * gfs2_glock_dq_uninit_m - release multiple glocks
1255  * @num_gh: the number of structures
1256  * @ghs: an array of struct gfs2_holder structures
1257  *
1258  */
1259
1260 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1261 {
1262         while (num_gh--)
1263                 gfs2_glock_dq_uninit(&ghs[num_gh]);
1264 }
1265
1266 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1267 {
1268         unsigned long delay = 0;
1269         unsigned long holdtime;
1270         unsigned long now = jiffies;
1271
1272         gfs2_glock_hold(gl);
1273         holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
1274         if (test_bit(GLF_QUEUED, &gl->gl_flags)) {
1275                 if (time_before(now, holdtime))
1276                         delay = holdtime - now;
1277                 if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1278                         delay = gl->gl_ops->go_min_hold_time;
1279         }
1280
1281         spin_lock(&gl->gl_spin);
1282         handle_callback(gl, state, delay);
1283         spin_unlock(&gl->gl_spin);
1284         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1285                 gfs2_glock_put(gl);
1286 }
1287
1288 /**
1289  * gfs2_should_freeze - Figure out if glock should be frozen
1290  * @gl: The glock in question
1291  *
1292  * Glocks are not frozen if (a) the result of the dlm operation is
1293  * an error, (b) the locking operation was an unlock operation or
1294  * (c) if there is a "noexp" flagged request anywhere in the queue
1295  *
1296  * Returns: 1 if freezing should occur, 0 otherwise
1297  */
1298
1299 static int gfs2_should_freeze(const struct gfs2_glock *gl)
1300 {
1301         const struct gfs2_holder *gh;
1302
1303         if (gl->gl_reply & ~LM_OUT_ST_MASK)
1304                 return 0;
1305         if (gl->gl_target == LM_ST_UNLOCKED)
1306                 return 0;
1307
1308         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1309                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1310                         continue;
1311                 if (LM_FLAG_NOEXP & gh->gh_flags)
1312                         return 0;
1313         }
1314
1315         return 1;
1316 }
1317
1318 /**
1319  * gfs2_glock_complete - Callback used by locking
1320  * @gl: Pointer to the glock
1321  * @ret: The return value from the dlm
1322  *
1323  * The gl_reply field is under the gl_spin lock so that it is ok
1324  * to use a bitfield shared with other glock state fields.
1325  */
1326
1327 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1328 {
1329         struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
1330
1331         spin_lock(&gl->gl_spin);
1332         gl->gl_reply = ret;
1333
1334         if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_flags))) {
1335                 if (gfs2_should_freeze(gl)) {
1336                         set_bit(GLF_FROZEN, &gl->gl_flags);
1337                         spin_unlock(&gl->gl_spin);
1338                         return;
1339                 }
1340         }
1341
1342         spin_unlock(&gl->gl_spin);
1343         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1344         smp_wmb();
1345         gfs2_glock_hold(gl);
1346         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1347                 gfs2_glock_put(gl);
1348 }
1349
1350
1351 static int gfs2_shrink_glock_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask)
1352 {
1353         struct gfs2_glock *gl;
1354         int may_demote;
1355         int nr_skipped = 0;
1356         LIST_HEAD(skipped);
1357
1358         if (nr == 0)
1359                 goto out;
1360
1361         if (!(gfp_mask & __GFP_FS))
1362                 return -1;
1363
1364         spin_lock(&lru_lock);
1365         while(nr && !list_empty(&lru_list)) {
1366                 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1367                 list_del_init(&gl->gl_lru);
1368                 atomic_dec(&lru_count);
1369
1370                 /* Test for being demotable */
1371                 if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1372                         gfs2_glock_hold(gl);
1373                         spin_unlock(&lru_lock);
1374                         spin_lock(&gl->gl_spin);
1375                         may_demote = demote_ok(gl);
1376                         if (may_demote) {
1377                                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1378                                 nr--;
1379                         }
1380                         clear_bit(GLF_LOCK, &gl->gl_flags);
1381                         smp_mb__after_clear_bit();
1382                         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1383                                 gfs2_glock_put_nolock(gl);
1384                         spin_unlock(&gl->gl_spin);
1385                         spin_lock(&lru_lock);
1386                         continue;
1387                 }
1388                 nr_skipped++;
1389                 list_add(&gl->gl_lru, &skipped);
1390         }
1391         list_splice(&skipped, &lru_list);
1392         atomic_add(nr_skipped, &lru_count);
1393         spin_unlock(&lru_lock);
1394 out:
1395         return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
1396 }
1397
1398 static struct shrinker glock_shrinker = {
1399         .shrink = gfs2_shrink_glock_memory,
1400         .seeks = DEFAULT_SEEKS,
1401 };
1402
1403 /**
1404  * examine_bucket - Call a function for glock in a hash bucket
1405  * @examiner: the function
1406  * @sdp: the filesystem
1407  * @bucket: the bucket
1408  *
1409  */
1410
1411 static void examine_bucket(glock_examiner examiner, const struct gfs2_sbd *sdp,
1412                           unsigned int hash)
1413 {
1414         struct gfs2_glock *gl;
1415         struct hlist_bl_head *head = &gl_hash_table[hash];
1416         struct hlist_bl_node *pos;
1417
1418         rcu_read_lock();
1419         hlist_bl_for_each_entry_rcu(gl, pos, head, gl_list) {
1420                 if ((gl->gl_sbd == sdp) && atomic_read(&gl->gl_ref))
1421                         examiner(gl);
1422         }
1423         rcu_read_unlock();
1424         cond_resched();
1425 }
1426
1427 static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
1428 {
1429         unsigned x;
1430
1431         for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1432                 examine_bucket(examiner, sdp, x);
1433 }
1434
1435
1436 /**
1437  * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1438  * @gl: The glock to thaw
1439  *
1440  * N.B. When we freeze a glock, we leave a ref to the glock outstanding,
1441  * so this has to result in the ref count being dropped by one.
1442  */
1443
1444 static void thaw_glock(struct gfs2_glock *gl)
1445 {
1446         if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1447                 return;
1448         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1449         gfs2_glock_hold(gl);
1450         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1451                 gfs2_glock_put(gl);
1452 }
1453
1454 /**
1455  * clear_glock - look at a glock and see if we can free it from glock cache
1456  * @gl: the glock to look at
1457  *
1458  */
1459
1460 static void clear_glock(struct gfs2_glock *gl)
1461 {
1462         spin_lock(&lru_lock);
1463         if (!list_empty(&gl->gl_lru)) {
1464                 list_del_init(&gl->gl_lru);
1465                 atomic_dec(&lru_count);
1466         }
1467         spin_unlock(&lru_lock);
1468
1469         spin_lock(&gl->gl_spin);
1470         if (gl->gl_state != LM_ST_UNLOCKED)
1471                 handle_callback(gl, LM_ST_UNLOCKED, 0);
1472         spin_unlock(&gl->gl_spin);
1473         gfs2_glock_hold(gl);
1474         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1475                 gfs2_glock_put(gl);
1476 }
1477
1478 /**
1479  * gfs2_glock_thaw - Thaw any frozen glocks
1480  * @sdp: The super block
1481  *
1482  */
1483
1484 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1485 {
1486         glock_hash_walk(thaw_glock, sdp);
1487 }
1488
1489 static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1490 {
1491         int ret;
1492         spin_lock(&gl->gl_spin);
1493         ret = __dump_glock(seq, gl);
1494         spin_unlock(&gl->gl_spin);
1495         return ret;
1496 }
1497
1498 static void dump_glock_func(struct gfs2_glock *gl)
1499 {
1500         dump_glock(NULL, gl);
1501 }
1502
1503 /**
1504  * gfs2_gl_hash_clear - Empty out the glock hash table
1505  * @sdp: the filesystem
1506  * @wait: wait until it's all gone
1507  *
1508  * Called when unmounting the filesystem.
1509  */
1510
1511 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1512 {
1513         glock_hash_walk(clear_glock, sdp);
1514         flush_workqueue(glock_workqueue);
1515         wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
1516         glock_hash_walk(dump_glock_func, sdp);
1517 }
1518
1519 void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1520 {
1521         struct gfs2_glock *gl = ip->i_gl;
1522         int ret;
1523
1524         ret = gfs2_truncatei_resume(ip);
1525         gfs2_assert_withdraw(gl->gl_sbd, ret == 0);
1526
1527         spin_lock(&gl->gl_spin);
1528         clear_bit(GLF_LOCK, &gl->gl_flags);
1529         run_queue(gl, 1);
1530         spin_unlock(&gl->gl_spin);
1531 }
1532
1533 static const char *state2str(unsigned state)
1534 {
1535         switch(state) {
1536         case LM_ST_UNLOCKED:
1537                 return "UN";
1538         case LM_ST_SHARED:
1539                 return "SH";
1540         case LM_ST_DEFERRED:
1541                 return "DF";
1542         case LM_ST_EXCLUSIVE:
1543                 return "EX";
1544         }
1545         return "??";
1546 }
1547
1548 static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags)
1549 {
1550         char *p = buf;
1551         if (flags & LM_FLAG_TRY)
1552                 *p++ = 't';
1553         if (flags & LM_FLAG_TRY_1CB)
1554                 *p++ = 'T';
1555         if (flags & LM_FLAG_NOEXP)
1556                 *p++ = 'e';
1557         if (flags & LM_FLAG_ANY)
1558                 *p++ = 'A';
1559         if (flags & LM_FLAG_PRIORITY)
1560                 *p++ = 'p';
1561         if (flags & GL_ASYNC)
1562                 *p++ = 'a';
1563         if (flags & GL_EXACT)
1564                 *p++ = 'E';
1565         if (flags & GL_NOCACHE)
1566                 *p++ = 'c';
1567         if (test_bit(HIF_HOLDER, &iflags))
1568                 *p++ = 'H';
1569         if (test_bit(HIF_WAIT, &iflags))
1570                 *p++ = 'W';
1571         if (test_bit(HIF_FIRST, &iflags))
1572                 *p++ = 'F';
1573         *p = 0;
1574         return buf;
1575 }
1576
1577 /**
1578  * dump_holder - print information about a glock holder
1579  * @seq: the seq_file struct
1580  * @gh: the glock holder
1581  *
1582  * Returns: 0 on success, -ENOBUFS when we run out of space
1583  */
1584
1585 static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1586 {
1587         struct task_struct *gh_owner = NULL;
1588         char flags_buf[32];
1589
1590         if (gh->gh_owner_pid)
1591                 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1592         gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
1593                        state2str(gh->gh_state),
1594                        hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1595                        gh->gh_error,
1596                        gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1597                        gh_owner ? gh_owner->comm : "(ended)",
1598                        (void *)gh->gh_ip);
1599         return 0;
1600 }
1601
1602 static const char *gflags2str(char *buf, const unsigned long *gflags)
1603 {
1604         char *p = buf;
1605         if (test_bit(GLF_LOCK, gflags))
1606                 *p++ = 'l';
1607         if (test_bit(GLF_DEMOTE, gflags))
1608                 *p++ = 'D';
1609         if (test_bit(GLF_PENDING_DEMOTE, gflags))
1610                 *p++ = 'd';
1611         if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1612                 *p++ = 'p';
1613         if (test_bit(GLF_DIRTY, gflags))
1614                 *p++ = 'y';
1615         if (test_bit(GLF_LFLUSH, gflags))
1616                 *p++ = 'f';
1617         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1618                 *p++ = 'i';
1619         if (test_bit(GLF_REPLY_PENDING, gflags))
1620                 *p++ = 'r';
1621         if (test_bit(GLF_INITIAL, gflags))
1622                 *p++ = 'I';
1623         if (test_bit(GLF_FROZEN, gflags))
1624                 *p++ = 'F';
1625         if (test_bit(GLF_QUEUED, gflags))
1626                 *p++ = 'q';
1627         *p = 0;
1628         return buf;
1629 }
1630
1631 /**
1632  * __dump_glock - print information about a glock
1633  * @seq: The seq_file struct
1634  * @gl: the glock
1635  *
1636  * The file format is as follows:
1637  * One line per object, capital letters are used to indicate objects
1638  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1639  * other objects are indented by a single space and follow the glock to
1640  * which they are related. Fields are indicated by lower case letters
1641  * followed by a colon and the field value, except for strings which are in
1642  * [] so that its possible to see if they are composed of spaces for
1643  * example. The field's are n = number (id of the object), f = flags,
1644  * t = type, s = state, r = refcount, e = error, p = pid.
1645  *
1646  * Returns: 0 on success, -ENOBUFS when we run out of space
1647  */
1648
1649 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1650 {
1651         const struct gfs2_glock_operations *glops = gl->gl_ops;
1652         unsigned long long dtime;
1653         const struct gfs2_holder *gh;
1654         char gflags_buf[32];
1655         int error = 0;
1656
1657         dtime = jiffies - gl->gl_demote_time;
1658         dtime *= 1000000/HZ; /* demote time in uSec */
1659         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1660                 dtime = 0;
1661         gfs2_print_dbg(seq, "G:  s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d r:%d\n",
1662                   state2str(gl->gl_state),
1663                   gl->gl_name.ln_type,
1664                   (unsigned long long)gl->gl_name.ln_number,
1665                   gflags2str(gflags_buf, &gl->gl_flags),
1666                   state2str(gl->gl_target),
1667                   state2str(gl->gl_demote_state), dtime,
1668                   atomic_read(&gl->gl_ail_count),
1669                   atomic_read(&gl->gl_ref));
1670
1671         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1672                 error = dump_holder(seq, gh);
1673                 if (error)
1674                         goto out;
1675         }
1676         if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1677                 error = glops->go_dump(seq, gl);
1678 out:
1679         return error;
1680 }
1681
1682
1683
1684
1685 int __init gfs2_glock_init(void)
1686 {
1687         unsigned i;
1688         for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
1689                 INIT_HLIST_BL_HEAD(&gl_hash_table[i]);
1690         }
1691
1692         glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
1693                                           WQ_HIGHPRI | WQ_FREEZABLE, 0);
1694         if (IS_ERR(glock_workqueue))
1695                 return PTR_ERR(glock_workqueue);
1696         gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
1697                                                 WQ_MEM_RECLAIM | WQ_FREEZABLE,
1698                                                 0);
1699         if (IS_ERR(gfs2_delete_workqueue)) {
1700                 destroy_workqueue(glock_workqueue);
1701                 return PTR_ERR(gfs2_delete_workqueue);
1702         }
1703
1704         register_shrinker(&glock_shrinker);
1705
1706         return 0;
1707 }
1708
1709 void gfs2_glock_exit(void)
1710 {
1711         unregister_shrinker(&glock_shrinker);
1712         destroy_workqueue(glock_workqueue);
1713         destroy_workqueue(gfs2_delete_workqueue);
1714 }
1715
1716 static inline struct gfs2_glock *glock_hash_chain(unsigned hash)
1717 {
1718         return hlist_bl_entry(hlist_bl_first_rcu(&gl_hash_table[hash]),
1719                               struct gfs2_glock, gl_list);
1720 }
1721
1722 static inline struct gfs2_glock *glock_hash_next(struct gfs2_glock *gl)
1723 {
1724         return hlist_bl_entry(rcu_dereference(gl->gl_list.next),
1725                               struct gfs2_glock, gl_list);
1726 }
1727
1728 static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1729 {
1730         struct gfs2_glock *gl;
1731
1732         do {
1733                 gl = gi->gl;
1734                 if (gl) {
1735                         gi->gl = glock_hash_next(gl);
1736                 } else {
1737                         gi->gl = glock_hash_chain(gi->hash);
1738                 }
1739                 while (gi->gl == NULL) {
1740                         gi->hash++;
1741                         if (gi->hash >= GFS2_GL_HASH_SIZE) {
1742                                 rcu_read_unlock();
1743                                 return 1;
1744                         }
1745                         gi->gl = glock_hash_chain(gi->hash);
1746                 }
1747         /* Skip entries for other sb and dead entries */
1748         } while (gi->sdp != gi->gl->gl_sbd || atomic_read(&gi->gl->gl_ref) == 0);
1749
1750         return 0;
1751 }
1752
1753 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1754 {
1755         struct gfs2_glock_iter *gi = seq->private;
1756         loff_t n = *pos;
1757
1758         gi->hash = 0;
1759         rcu_read_lock();
1760
1761         do {
1762                 if (gfs2_glock_iter_next(gi))
1763                         return NULL;
1764         } while (n--);
1765
1766         return gi->gl;
1767 }
1768
1769 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1770                                  loff_t *pos)
1771 {
1772         struct gfs2_glock_iter *gi = seq->private;
1773
1774         (*pos)++;
1775
1776         if (gfs2_glock_iter_next(gi))
1777                 return NULL;
1778
1779         return gi->gl;
1780 }
1781
1782 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1783 {
1784         struct gfs2_glock_iter *gi = seq->private;
1785
1786         if (gi->gl)
1787                 rcu_read_unlock();
1788         gi->gl = NULL;
1789 }
1790
1791 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1792 {
1793         return dump_glock(seq, iter_ptr);
1794 }
1795
1796 static const struct seq_operations gfs2_glock_seq_ops = {
1797         .start = gfs2_glock_seq_start,
1798         .next  = gfs2_glock_seq_next,
1799         .stop  = gfs2_glock_seq_stop,
1800         .show  = gfs2_glock_seq_show,
1801 };
1802
1803 static int gfs2_debugfs_open(struct inode *inode, struct file *file)
1804 {
1805         int ret = seq_open_private(file, &gfs2_glock_seq_ops,
1806                                    sizeof(struct gfs2_glock_iter));
1807         if (ret == 0) {
1808                 struct seq_file *seq = file->private_data;
1809                 struct gfs2_glock_iter *gi = seq->private;
1810                 gi->sdp = inode->i_private;
1811         }
1812         return ret;
1813 }
1814
1815 static const struct file_operations gfs2_debug_fops = {
1816         .owner   = THIS_MODULE,
1817         .open    = gfs2_debugfs_open,
1818         .read    = seq_read,
1819         .llseek  = seq_lseek,
1820         .release = seq_release_private,
1821 };
1822
1823 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
1824 {
1825         sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
1826         if (!sdp->debugfs_dir)
1827                 return -ENOMEM;
1828         sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
1829                                                          S_IFREG | S_IRUGO,
1830                                                          sdp->debugfs_dir, sdp,
1831                                                          &gfs2_debug_fops);
1832         if (!sdp->debugfs_dentry_glocks)
1833                 return -ENOMEM;
1834
1835         return 0;
1836 }
1837
1838 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
1839 {
1840         if (sdp && sdp->debugfs_dir) {
1841                 if (sdp->debugfs_dentry_glocks) {
1842                         debugfs_remove(sdp->debugfs_dentry_glocks);
1843                         sdp->debugfs_dentry_glocks = NULL;
1844                 }
1845                 debugfs_remove(sdp->debugfs_dir);
1846                 sdp->debugfs_dir = NULL;
1847         }
1848 }
1849
1850 int gfs2_register_debugfs(void)
1851 {
1852         gfs2_root = debugfs_create_dir("gfs2", NULL);
1853         return gfs2_root ? 0 : -ENOMEM;
1854 }
1855
1856 void gfs2_unregister_debugfs(void)
1857 {
1858         debugfs_remove(gfs2_root);
1859         gfs2_root = NULL;
1860 }