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Add linux-next specific files for 20110831
[linux-2.6/next.git] / fs / gfs2 / glock.c
blob88e8a23d0026375c52bf6fd3b69bfd2a87fca598
1 /*
2 * Copyright (C) Sistina Software, Inc. 1997-2003 All rights reserved.
3 * Copyright (C) 2004-2008 Red Hat, Inc. All rights reserved.
4 *
5 * This copyrighted material is made available to anyone wishing to use,
6 * modify, copy, or redistribute it subject to the terms and conditions
7 * of the GNU General Public License version 2.
8 */
9
10 #include <linux/sched.h>
11 #include <linux/slab.h>
12 #include <linux/spinlock.h>
13 #include <linux/buffer_head.h>
14 #include <linux/delay.h>
15 #include <linux/sort.h>
16 #include <linux/jhash.h>
17 #include <linux/kallsyms.h>
18 #include <linux/gfs2_ondisk.h>
19 #include <linux/list.h>
20 #include <linux/wait.h>
21 #include <linux/module.h>
22 #include <asm/uaccess.h>
23 #include <linux/seq_file.h>
24 #include <linux/debugfs.h>
25 #include <linux/kthread.h>
26 #include <linux/freezer.h>
27 #include <linux/workqueue.h>
28 #include <linux/jiffies.h>
29 #include <linux/rcupdate.h>
30 #include <linux/rculist_bl.h>
31 #include <linux/bit_spinlock.h>
32
33 #include "gfs2.h"
34 #include "incore.h"
35 #include "glock.h"
36 #include "glops.h"
37 #include "inode.h"
38 #include "lops.h"
39 #include "meta_io.h"
40 #include "quota.h"
41 #include "super.h"
42 #include "util.h"
43 #include "bmap.h"
44 #define CREATE_TRACE_POINTS
45 #include "trace_gfs2.h"
46
47 struct gfs2_glock_iter {
48 int hash; /* hash bucket index */
49 struct gfs2_sbd *sdp; /* incore superblock */
50 struct gfs2_glock *gl; /* current glock struct */
51 char string[512]; /* scratch space */
52 };
53
54 typedef void (*glock_examiner) (struct gfs2_glock * gl);
55
56 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl);
57 #define GLOCK_BUG_ON(gl,x) do { if (unlikely(x)) { __dump_glock(NULL, gl); BUG(); } } while(0)
58 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
59
60 static struct dentry *gfs2_root;
61 static struct workqueue_struct *glock_workqueue;
62 struct workqueue_struct *gfs2_delete_workqueue;
63 static LIST_HEAD(lru_list);
64 static atomic_t lru_count = ATOMIC_INIT(0);
65 static DEFINE_SPINLOCK(lru_lock);
66
67 #define GFS2_GL_HASH_SHIFT 15
68 #define GFS2_GL_HASH_SIZE (1 << GFS2_GL_HASH_SHIFT)
69 #define GFS2_GL_HASH_MASK (GFS2_GL_HASH_SIZE - 1)
70
71 static struct hlist_bl_head gl_hash_table[GFS2_GL_HASH_SIZE];
72 static struct dentry *gfs2_root;
73
74 /**
75 * gl_hash() - Turn glock number into hash bucket number
76 * @lock: The glock number
77 *
78 * Returns: The number of the corresponding hash bucket
79 */
80
81 static unsigned int gl_hash(const struct gfs2_sbd *sdp,
82 const struct lm_lockname *name)
83 {
84 unsigned int h;
85
86 h = jhash(&name->ln_number, sizeof(u64), 0);
87 h = jhash(&name->ln_type, sizeof(unsigned int), h);
88 h = jhash(&sdp, sizeof(struct gfs2_sbd *), h);
89 h &= GFS2_GL_HASH_MASK;
90
91 return h;
92 }
93
94 static inline void spin_lock_bucket(unsigned int hash)
95 {
96 hlist_bl_lock(&gl_hash_table[hash]);
97 }
98
99 static inline void spin_unlock_bucket(unsigned int hash)
100 {
101 hlist_bl_unlock(&gl_hash_table[hash]);
102 }
103
104 static void gfs2_glock_dealloc(struct rcu_head *rcu)
105 {
106 struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu);
107
108 if (gl->gl_ops->go_flags & GLOF_ASPACE)
109 kmem_cache_free(gfs2_glock_aspace_cachep, gl);
110 else
111 kmem_cache_free(gfs2_glock_cachep, gl);
112 }
113
114 void gfs2_glock_free(struct gfs2_glock *gl)
115 {
116 struct gfs2_sbd *sdp = gl->gl_sbd;
117
118 call_rcu(&gl->gl_rcu, gfs2_glock_dealloc);
119 if (atomic_dec_and_test(&sdp->sd_glock_disposal))
120 wake_up(&sdp->sd_glock_wait);
121 }
122
123 /**
124 * gfs2_glock_hold() - increment reference count on glock
125 * @gl: The glock to hold
126 *
127 */
128
129 void gfs2_glock_hold(struct gfs2_glock *gl)
130 {
131 GLOCK_BUG_ON(gl, atomic_read(&gl->gl_ref) == 0);
132 atomic_inc(&gl->gl_ref);
133 }
134
135 /**
136 * demote_ok - Check to see if it's ok to unlock a glock
137 * @gl: the glock
138 *
139 * Returns: 1 if it's ok
140 */
141
142 static int demote_ok(const struct gfs2_glock *gl)
143 {
144 const struct gfs2_glock_operations *glops = gl->gl_ops;
145
146 if (gl->gl_state == LM_ST_UNLOCKED)
147 return 0;
148 if (!list_empty(&gl->gl_holders))
149 return 0;
150 if (glops->go_demote_ok)
151 return glops->go_demote_ok(gl);
152 return 1;
153 }
154
155
156 void gfs2_glock_add_to_lru(struct gfs2_glock *gl)
157 {
158 spin_lock(&lru_lock);
159
160 if (!list_empty(&gl->gl_lru))
161 list_del_init(&gl->gl_lru);
162 else
163 atomic_inc(&lru_count);
164
165 list_add_tail(&gl->gl_lru, &lru_list);
166 set_bit(GLF_LRU, &gl->gl_flags);
167 spin_unlock(&lru_lock);
168 }
169
170 static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
171 {
172 spin_lock(&lru_lock);
173 if (!list_empty(&gl->gl_lru)) {
174 list_del_init(&gl->gl_lru);
175 atomic_dec(&lru_count);
176 clear_bit(GLF_LRU, &gl->gl_flags);
177 }
178 spin_unlock(&lru_lock);
179 }
180
181 /**
182 * __gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
183 * @gl: the glock
184 *
185 * If the glock is demotable, then we add it (or move it) to the end
186 * of the glock LRU list.
187 */
188
189 static void __gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
190 {
191 if (demote_ok(gl))
192 gfs2_glock_add_to_lru(gl);
193 }
194
195 /**
196 * gfs2_glock_put_nolock() - Decrement reference count on glock
197 * @gl: The glock to put
198 *
199 * This function should only be used if the caller has its own reference
200 * to the glock, in addition to the one it is dropping.
201 */
202
203 void gfs2_glock_put_nolock(struct gfs2_glock *gl)
204 {
205 if (atomic_dec_and_test(&gl->gl_ref))
206 GLOCK_BUG_ON(gl, 1);
207 }
208
209 /**
210 * gfs2_glock_put() - Decrement reference count on glock
211 * @gl: The glock to put
212 *
213 */
214
215 void gfs2_glock_put(struct gfs2_glock *gl)
216 {
217 struct gfs2_sbd *sdp = gl->gl_sbd;
218 struct address_space *mapping = gfs2_glock2aspace(gl);
219
220 if (atomic_dec_and_test(&gl->gl_ref)) {
221 spin_lock_bucket(gl->gl_hash);
222 hlist_bl_del_rcu(&gl->gl_list);
223 spin_unlock_bucket(gl->gl_hash);
224 gfs2_glock_remove_from_lru(gl);
225 GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
226 GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
227 trace_gfs2_glock_put(gl);
228 sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
229 }
230 }
231
232 /**
233 * search_bucket() - Find struct gfs2_glock by lock number
234 * @bucket: the bucket to search
235 * @name: The lock name
236 *
237 * Returns: NULL, or the struct gfs2_glock with the requested number
238 */
239
240 static struct gfs2_glock *search_bucket(unsigned int hash,
241 const struct gfs2_sbd *sdp,
242 const struct lm_lockname *name)
243 {
244 struct gfs2_glock *gl;
245 struct hlist_bl_node *h;
246
247 hlist_bl_for_each_entry_rcu(gl, h, &gl_hash_table[hash], gl_list) {
248 if (!lm_name_equal(&gl->gl_name, name))
249 continue;
250 if (gl->gl_sbd != sdp)
251 continue;
252 if (atomic_inc_not_zero(&gl->gl_ref))
253 return gl;
254 }
255
256 return NULL;
257 }
258
259 /**
260 * may_grant - check if its ok to grant a new lock
261 * @gl: The glock
262 * @gh: The lock request which we wish to grant
263 *
264 * Returns: true if its ok to grant the lock
265 */
266
267 static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
268 {
269 const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
270 if ((gh->gh_state == LM_ST_EXCLUSIVE ||
271 gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
272 return 0;
273 if (gl->gl_state == gh->gh_state)
274 return 1;
275 if (gh->gh_flags & GL_EXACT)
276 return 0;
277 if (gl->gl_state == LM_ST_EXCLUSIVE) {
278 if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
279 return 1;
280 if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
281 return 1;
282 }
283 if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
284 return 1;
285 return 0;
286 }
287
288 static void gfs2_holder_wake(struct gfs2_holder *gh)
289 {
290 clear_bit(HIF_WAIT, &gh->gh_iflags);
291 smp_mb__after_clear_bit();
292 wake_up_bit(&gh->gh_iflags, HIF_WAIT);
293 }
294
295 /**
296 * do_error - Something unexpected has happened during a lock request
297 *
298 */
299
300 static inline void do_error(struct gfs2_glock *gl, const int ret)
301 {
302 struct gfs2_holder *gh, *tmp;
303
304 list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
305 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
306 continue;
307 if (ret & LM_OUT_ERROR)
308 gh->gh_error = -EIO;
309 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
310 gh->gh_error = GLR_TRYFAILED;
311 else
312 continue;
313 list_del_init(&gh->gh_list);
314 trace_gfs2_glock_queue(gh, 0);
315 gfs2_holder_wake(gh);
316 }
317 }
318
319 /**
320 * do_promote - promote as many requests as possible on the current queue
321 * @gl: The glock
322 *
323 * Returns: 1 if there is a blocked holder at the head of the list, or 2
324 * if a type specific operation is underway.
325 */
326
327 static int do_promote(struct gfs2_glock *gl)
328 __releases(&gl->gl_spin)
329 __acquires(&gl->gl_spin)
330 {
331 const struct gfs2_glock_operations *glops = gl->gl_ops;
332 struct gfs2_holder *gh, *tmp;
333 int ret;
334
335 restart:
336 list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
337 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
338 continue;
339 if (may_grant(gl, gh)) {
340 if (gh->gh_list.prev == &gl->gl_holders &&
341 glops->go_lock) {
342 spin_unlock(&gl->gl_spin);
343 /* FIXME: eliminate this eventually */
344 ret = glops->go_lock(gh);
345 spin_lock(&gl->gl_spin);
346 if (ret) {
347 if (ret == 1)
348 return 2;
349 gh->gh_error = ret;
350 list_del_init(&gh->gh_list);
351 trace_gfs2_glock_queue(gh, 0);
352 gfs2_holder_wake(gh);
353 goto restart;
354 }
355 set_bit(HIF_HOLDER, &gh->gh_iflags);
356 trace_gfs2_promote(gh, 1);
357 gfs2_holder_wake(gh);
358 goto restart;
359 }
360 set_bit(HIF_HOLDER, &gh->gh_iflags);
361 trace_gfs2_promote(gh, 0);
362 gfs2_holder_wake(gh);
363 continue;
364 }
365 if (gh->gh_list.prev == &gl->gl_holders)
366 return 1;
367 do_error(gl, 0);
368 break;
369 }
370 return 0;
371 }
372
373 /**
374 * find_first_waiter - find the first gh that's waiting for the glock
375 * @gl: the glock
376 */
377
378 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
379 {
380 struct gfs2_holder *gh;
381
382 list_for_each_entry(gh, &gl->gl_holders, gh_list) {
383 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
384 return gh;
385 }
386 return NULL;
387 }
388
389 /**
390 * state_change - record that the glock is now in a different state
391 * @gl: the glock
392 * @new_state the new state
393 *
394 */
395
396 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
397 {
398 int held1, held2;
399
400 held1 = (gl->gl_state != LM_ST_UNLOCKED);
401 held2 = (new_state != LM_ST_UNLOCKED);
402
403 if (held1 != held2) {
404 if (held2)
405 gfs2_glock_hold(gl);
406 else
407 gfs2_glock_put_nolock(gl);
408 }
409 if (held1 && held2 && list_empty(&gl->gl_holders))
410 clear_bit(GLF_QUEUED, &gl->gl_flags);
411
412 if (new_state != gl->gl_target)
413 /* shorten our minimum hold time */
414 gl->gl_hold_time = max(gl->gl_hold_time - GL_GLOCK_HOLD_DECR,
415 GL_GLOCK_MIN_HOLD);
416 gl->gl_state = new_state;
417 gl->gl_tchange = jiffies;
418 }
419
420 static void gfs2_demote_wake(struct gfs2_glock *gl)
421 {
422 gl->gl_demote_state = LM_ST_EXCLUSIVE;
423 clear_bit(GLF_DEMOTE, &gl->gl_flags);
424 smp_mb__after_clear_bit();
425 wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
426 }
427
428 /**
429 * finish_xmote - The DLM has replied to one of our lock requests
430 * @gl: The glock
431 * @ret: The status from the DLM
432 *
433 */
434
435 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
436 {
437 const struct gfs2_glock_operations *glops = gl->gl_ops;
438 struct gfs2_holder *gh;
439 unsigned state = ret & LM_OUT_ST_MASK;
440 int rv;
441
442 spin_lock(&gl->gl_spin);
443 trace_gfs2_glock_state_change(gl, state);
444 state_change(gl, state);
445 gh = find_first_waiter(gl);
446
447 /* Demote to UN request arrived during demote to SH or DF */
448 if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
449 state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
450 gl->gl_target = LM_ST_UNLOCKED;
451
452 /* Check for state != intended state */
453 if (unlikely(state != gl->gl_target)) {
454 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
455 /* move to back of queue and try next entry */
456 if (ret & LM_OUT_CANCELED) {
457 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
458 list_move_tail(&gh->gh_list, &gl->gl_holders);
459 gh = find_first_waiter(gl);
460 gl->gl_target = gh->gh_state;
461 goto retry;
462 }
463 /* Some error or failed "try lock" - report it */
464 if ((ret & LM_OUT_ERROR) ||
465 (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
466 gl->gl_target = gl->gl_state;
467 do_error(gl, ret);
468 goto out;
469 }
470 }
471 switch(state) {
472 /* Unlocked due to conversion deadlock, try again */
473 case LM_ST_UNLOCKED:
474 retry:
475 do_xmote(gl, gh, gl->gl_target);
476 break;
477 /* Conversion fails, unlock and try again */
478 case LM_ST_SHARED:
479 case LM_ST_DEFERRED:
480 do_xmote(gl, gh, LM_ST_UNLOCKED);
481 break;
482 default: /* Everything else */
483 printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
484 GLOCK_BUG_ON(gl, 1);
485 }
486 spin_unlock(&gl->gl_spin);
487 return;
488 }
489
490 /* Fast path - we got what we asked for */
491 if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
492 gfs2_demote_wake(gl);
493 if (state != LM_ST_UNLOCKED) {
494 if (glops->go_xmote_bh) {
495 spin_unlock(&gl->gl_spin);
496 rv = glops->go_xmote_bh(gl, gh);
497 spin_lock(&gl->gl_spin);
498 if (rv) {
499 do_error(gl, rv);
500 goto out;
501 }
502 }
503 rv = do_promote(gl);
504 if (rv == 2)
505 goto out_locked;
506 }
507 out:
508 clear_bit(GLF_LOCK, &gl->gl_flags);
509 out_locked:
510 spin_unlock(&gl->gl_spin);
511 }
512
513 /**
514 * do_xmote - Calls the DLM to change the state of a lock
515 * @gl: The lock state
516 * @gh: The holder (only for promotes)
517 * @target: The target lock state
518 *
519 */
520
521 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
522 __releases(&gl->gl_spin)
523 __acquires(&gl->gl_spin)
524 {
525 const struct gfs2_glock_operations *glops = gl->gl_ops;
526 struct gfs2_sbd *sdp = gl->gl_sbd;
527 unsigned int lck_flags = gh ? gh->gh_flags : 0;
528 int ret;
529
530 lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
531 LM_FLAG_PRIORITY);
532 GLOCK_BUG_ON(gl, gl->gl_state == target);
533 GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
534 if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
535 glops->go_inval) {
536 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
537 do_error(gl, 0); /* Fail queued try locks */
538 }
539 gl->gl_req = target;
540 spin_unlock(&gl->gl_spin);
541 if (glops->go_xmote_th)
542 glops->go_xmote_th(gl);
543 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
544 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
545 clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
546
547 gfs2_glock_hold(gl);
548 if (sdp->sd_lockstruct.ls_ops->lm_lock) {
549 /* lock_dlm */
550 ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
551 GLOCK_BUG_ON(gl, ret);
552 } else { /* lock_nolock */
553 finish_xmote(gl, target);
554 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
555 gfs2_glock_put(gl);
556 }
557
558 spin_lock(&gl->gl_spin);
559 }
560
561 /**
562 * find_first_holder - find the first "holder" gh
563 * @gl: the glock
564 */
565
566 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
567 {
568 struct gfs2_holder *gh;
569
570 if (!list_empty(&gl->gl_holders)) {
571 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
572 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
573 return gh;
574 }
575 return NULL;
576 }
577
578 /**
579 * run_queue - do all outstanding tasks related to a glock
580 * @gl: The glock in question
581 * @nonblock: True if we must not block in run_queue
582 *
583 */
584
585 static void run_queue(struct gfs2_glock *gl, const int nonblock)
586 __releases(&gl->gl_spin)
587 __acquires(&gl->gl_spin)
588 {
589 struct gfs2_holder *gh = NULL;
590 int ret;
591
592 if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
593 return;
594
595 GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
596
597 if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
598 gl->gl_demote_state != gl->gl_state) {
599 if (find_first_holder(gl))
600 goto out_unlock;
601 if (nonblock)
602 goto out_sched;
603 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
604 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
605 gl->gl_target = gl->gl_demote_state;
606 } else {
607 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
608 gfs2_demote_wake(gl);
609 ret = do_promote(gl);
610 if (ret == 0)
611 goto out_unlock;
612 if (ret == 2)
613 goto out;
614 gh = find_first_waiter(gl);
615 gl->gl_target = gh->gh_state;
616 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
617 do_error(gl, 0); /* Fail queued try locks */
618 }
619 do_xmote(gl, gh, gl->gl_target);
620 out:
621 return;
622
623 out_sched:
624 clear_bit(GLF_LOCK, &gl->gl_flags);
625 smp_mb__after_clear_bit();
626 gfs2_glock_hold(gl);
627 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
628 gfs2_glock_put_nolock(gl);
629 return;
630
631 out_unlock:
632 clear_bit(GLF_LOCK, &gl->gl_flags);
633 smp_mb__after_clear_bit();
634 return;
635 }
636
637 static void delete_work_func(struct work_struct *work)
638 {
639 struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
640 struct gfs2_sbd *sdp = gl->gl_sbd;
641 struct gfs2_inode *ip;
642 struct inode *inode;
643 u64 no_addr = gl->gl_name.ln_number;
644
645 ip = gl->gl_object;
646 /* Note: Unsafe to dereference ip as we don't hold right refs/locks */
647
648 if (ip)
649 inode = gfs2_ilookup(sdp->sd_vfs, no_addr, 1);
650 else
651 inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
652 if (inode && !IS_ERR(inode)) {
653 d_prune_aliases(inode);
654 iput(inode);
655 }
656 gfs2_glock_put(gl);
657 }
658
659 static void glock_work_func(struct work_struct *work)
660 {
661 unsigned long delay = 0;
662 struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
663 int drop_ref = 0;
664
665 if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
666 finish_xmote(gl, gl->gl_reply);
667 drop_ref = 1;
668 }
669 spin_lock(&gl->gl_spin);
670 if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
671 gl->gl_state != LM_ST_UNLOCKED &&
672 gl->gl_demote_state != LM_ST_EXCLUSIVE) {
673 unsigned long holdtime, now = jiffies;
674
675 holdtime = gl->gl_tchange + gl->gl_hold_time;
676 if (time_before(now, holdtime))
677 delay = holdtime - now;
678
679 if (!delay) {
680 clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
681 set_bit(GLF_DEMOTE, &gl->gl_flags);
682 }
683 }
684 run_queue(gl, 0);
685 spin_unlock(&gl->gl_spin);
686 if (!delay)
687 gfs2_glock_put(gl);
688 else {
689 if (gl->gl_name.ln_type != LM_TYPE_INODE)
690 delay = 0;
691 if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
692 gfs2_glock_put(gl);
693 }
694 if (drop_ref)
695 gfs2_glock_put(gl);
696 }
697
698 /**
699 * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
700 * @sdp: The GFS2 superblock
701 * @number: the lock number
702 * @glops: The glock_operations to use
703 * @create: If 0, don't create the glock if it doesn't exist
704 * @glp: the glock is returned here
705 *
706 * This does not lock a glock, just finds/creates structures for one.
707 *
708 * Returns: errno
709 */
710
711 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
712 const struct gfs2_glock_operations *glops, int create,
713 struct gfs2_glock **glp)
714 {
715 struct super_block *s = sdp->sd_vfs;
716 struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
717 struct gfs2_glock *gl, *tmp;
718 unsigned int hash = gl_hash(sdp, &name);
719 struct address_space *mapping;
720 struct kmem_cache *cachep;
721
722 rcu_read_lock();
723 gl = search_bucket(hash, sdp, &name);
724 rcu_read_unlock();
725
726 *glp = gl;
727 if (gl)
728 return 0;
729 if (!create)
730 return -ENOENT;
731
732 if (glops->go_flags & GLOF_ASPACE)
733 cachep = gfs2_glock_aspace_cachep;
734 else
735 cachep = gfs2_glock_cachep;
736 gl = kmem_cache_alloc(cachep, GFP_KERNEL);
737 if (!gl)
738 return -ENOMEM;
739
740 atomic_inc(&sdp->sd_glock_disposal);
741 gl->gl_flags = 0;
742 gl->gl_name = name;
743 atomic_set(&gl->gl_ref, 1);
744 gl->gl_state = LM_ST_UNLOCKED;
745 gl->gl_target = LM_ST_UNLOCKED;
746 gl->gl_demote_state = LM_ST_EXCLUSIVE;
747 gl->gl_hash = hash;
748 gl->gl_ops = glops;
749 snprintf(gl->gl_strname, GDLM_STRNAME_BYTES, "%8x%16llx", name.ln_type, (unsigned long long)number);
750 memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
751 gl->gl_lksb.sb_lvbptr = gl->gl_lvb;
752 gl->gl_tchange = jiffies;
753 gl->gl_object = NULL;
754 gl->gl_sbd = sdp;
755 gl->gl_hold_time = GL_GLOCK_DFT_HOLD;
756 INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
757 INIT_WORK(&gl->gl_delete, delete_work_func);
758
759 mapping = gfs2_glock2aspace(gl);
760 if (mapping) {
761 mapping->a_ops = &gfs2_meta_aops;
762 mapping->host = s->s_bdev->bd_inode;
763 mapping->flags = 0;
764 mapping_set_gfp_mask(mapping, GFP_NOFS);
765 mapping->assoc_mapping = NULL;
766 mapping->backing_dev_info = s->s_bdi;
767 mapping->writeback_index = 0;
768 }
769
770 spin_lock_bucket(hash);
771 tmp = search_bucket(hash, sdp, &name);
772 if (tmp) {
773 spin_unlock_bucket(hash);
774 kmem_cache_free(cachep, gl);
775 atomic_dec(&sdp->sd_glock_disposal);
776 gl = tmp;
777 } else {
778 hlist_bl_add_head_rcu(&gl->gl_list, &gl_hash_table[hash]);
779 spin_unlock_bucket(hash);
780 }
781
782 *glp = gl;
783
784 return 0;
785 }
786
787 /**
788 * gfs2_holder_init - initialize a struct gfs2_holder in the default way
789 * @gl: the glock
790 * @state: the state we're requesting
791 * @flags: the modifier flags
792 * @gh: the holder structure
793 *
794 */
795
796 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
797 struct gfs2_holder *gh)
798 {
799 INIT_LIST_HEAD(&gh->gh_list);
800 gh->gh_gl = gl;
801 gh->gh_ip = (unsigned long)__builtin_return_address(0);
802 gh->gh_owner_pid = get_pid(task_pid(current));
803 gh->gh_state = state;
804 gh->gh_flags = flags;
805 gh->gh_error = 0;
806 gh->gh_iflags = 0;
807 gfs2_glock_hold(gl);
808 }
809
810 /**
811 * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
812 * @state: the state we're requesting
813 * @flags: the modifier flags
814 * @gh: the holder structure
815 *
816 * Don't mess with the glock.
817 *
818 */
819
820 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
821 {
822 gh->gh_state = state;
823 gh->gh_flags = flags;
824 gh->gh_iflags = 0;
825 gh->gh_ip = (unsigned long)__builtin_return_address(0);
826 if (gh->gh_owner_pid)
827 put_pid(gh->gh_owner_pid);
828 gh->gh_owner_pid = get_pid(task_pid(current));
829 }
830
831 /**
832 * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
833 * @gh: the holder structure
834 *
835 */
836
837 void gfs2_holder_uninit(struct gfs2_holder *gh)
838 {
839 put_pid(gh->gh_owner_pid);
840 gfs2_glock_put(gh->gh_gl);
841 gh->gh_gl = NULL;
842 gh->gh_ip = 0;
843 }
844
845 /**
846 * gfs2_glock_holder_wait
847 * @word: unused
848 *
849 * This function and gfs2_glock_demote_wait both show up in the WCHAN
850 * field. Thus I've separated these otherwise identical functions in
851 * order to be more informative to the user.
852 */
853
854 static int gfs2_glock_holder_wait(void *word)
855 {
856 schedule();
857 return 0;
858 }
859
860 static int gfs2_glock_demote_wait(void *word)
861 {
862 schedule();
863 return 0;
864 }
865
866 static void wait_on_holder(struct gfs2_holder *gh)
867 {
868 unsigned long time1 = jiffies;
869
870 might_sleep();
871 wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
872 if (time_after(jiffies, time1 + HZ)) /* have we waited > a second? */
873 /* Lengthen the minimum hold time. */
874 gh->gh_gl->gl_hold_time = min(gh->gh_gl->gl_hold_time +
875 GL_GLOCK_HOLD_INCR,
876 GL_GLOCK_MAX_HOLD);
877 }
878
879 static void wait_on_demote(struct gfs2_glock *gl)
880 {
881 might_sleep();
882 wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
883 }
884
885 /**
886 * handle_callback - process a demote request
887 * @gl: the glock
888 * @state: the state the caller wants us to change to
889 *
890 * There are only two requests that we are going to see in actual
891 * practise: LM_ST_SHARED and LM_ST_UNLOCKED
892 */
893
894 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
895 unsigned long delay)
896 {
897 int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
898
899 set_bit(bit, &gl->gl_flags);
900 if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
901 gl->gl_demote_state = state;
902 gl->gl_demote_time = jiffies;
903 } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
904 gl->gl_demote_state != state) {
905 gl->gl_demote_state = LM_ST_UNLOCKED;
906 }
907 if (gl->gl_ops->go_callback)
908 gl->gl_ops->go_callback(gl);
909 trace_gfs2_demote_rq(gl);
910 }
911
912 /**
913 * gfs2_glock_wait - wait on a glock acquisition
914 * @gh: the glock holder
915 *
916 * Returns: 0 on success
917 */
918
919 int gfs2_glock_wait(struct gfs2_holder *gh)
920 {
921 wait_on_holder(gh);
922 return gh->gh_error;
923 }
924
925 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
926 {
927 struct va_format vaf;
928 va_list args;
929
930 va_start(args, fmt);
931
932 if (seq) {
933 struct gfs2_glock_iter *gi = seq->private;
934 vsprintf(gi->string, fmt, args);
935 seq_printf(seq, gi->string);
936 } else {
937 vaf.fmt = fmt;
938 vaf.va = &args;
939
940 printk(KERN_ERR " %pV", &vaf);
941 }
942
943 va_end(args);
944 }
945
946 /**
947 * add_to_queue - Add a holder to the wait queue (but look for recursion)
948 * @gh: the holder structure to add
949 *
950 * Eventually we should move the recursive locking trap to a
951 * debugging option or something like that. This is the fast
952 * path and needs to have the minimum number of distractions.
953 *
954 */
955
956 static inline void add_to_queue(struct gfs2_holder *gh)
957 __releases(&gl->gl_spin)
958 __acquires(&gl->gl_spin)
959 {
960 struct gfs2_glock *gl = gh->gh_gl;
961 struct gfs2_sbd *sdp = gl->gl_sbd;
962 struct list_head *insert_pt = NULL;
963 struct gfs2_holder *gh2;
964 int try_lock = 0;
965
966 BUG_ON(gh->gh_owner_pid == NULL);
967 if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
968 BUG();
969
970 if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
971 if (test_bit(GLF_LOCK, &gl->gl_flags))
972 try_lock = 1;
973 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
974 goto fail;
975 }
976
977 list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
978 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
979 (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
980 goto trap_recursive;
981 if (try_lock &&
982 !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
983 !may_grant(gl, gh)) {
984 fail:
985 gh->gh_error = GLR_TRYFAILED;
986 gfs2_holder_wake(gh);
987 return;
988 }
989 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
990 continue;
991 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
992 insert_pt = &gh2->gh_list;
993 }
994 set_bit(GLF_QUEUED, &gl->gl_flags);
995 trace_gfs2_glock_queue(gh, 1);
996 if (likely(insert_pt == NULL)) {
997 list_add_tail(&gh->gh_list, &gl->gl_holders);
998 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
999 goto do_cancel;
1000 return;
1001 }
1002 list_add_tail(&gh->gh_list, insert_pt);
1003 do_cancel:
1004 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
1005 if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
1006 spin_unlock(&gl->gl_spin);
1007 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
1008 sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
1009 spin_lock(&gl->gl_spin);
1010 }
1011 return;
1012
1013 trap_recursive:
1014 print_symbol(KERN_ERR "original: %s\n", gh2->gh_ip);
1015 printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
1016 printk(KERN_ERR "lock type: %d req lock state : %d\n",
1017 gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
1018 print_symbol(KERN_ERR "new: %s\n", gh->gh_ip);
1019 printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
1020 printk(KERN_ERR "lock type: %d req lock state : %d\n",
1021 gh->gh_gl->gl_name.ln_type, gh->gh_state);
1022 __dump_glock(NULL, gl);
1023 BUG();
1024 }
1025
1026 /**
1027 * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1028 * @gh: the holder structure
1029 *
1030 * if (gh->gh_flags & GL_ASYNC), this never returns an error
1031 *
1032 * Returns: 0, GLR_TRYFAILED, or errno on failure
1033 */
1034
1035 int gfs2_glock_nq(struct gfs2_holder *gh)
1036 {
1037 struct gfs2_glock *gl = gh->gh_gl;
1038 struct gfs2_sbd *sdp = gl->gl_sbd;
1039 int error = 0;
1040
1041 if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
1042 return -EIO;
1043
1044 if (test_bit(GLF_LRU, &gl->gl_flags))
1045 gfs2_glock_remove_from_lru(gl);
1046
1047 spin_lock(&gl->gl_spin);
1048 add_to_queue(gh);
1049 if ((LM_FLAG_NOEXP & gh->gh_flags) &&
1050 test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1051 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1052 run_queue(gl, 1);
1053 spin_unlock(&gl->gl_spin);
1054
1055 if (!(gh->gh_flags & GL_ASYNC))
1056 error = gfs2_glock_wait(gh);
1057
1058 return error;
1059 }
1060
1061 /**
1062 * gfs2_glock_poll - poll to see if an async request has been completed
1063 * @gh: the holder
1064 *
1065 * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1066 */
1067
1068 int gfs2_glock_poll(struct gfs2_holder *gh)
1069 {
1070 return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1071 }
1072
1073 /**
1074 * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1075 * @gh: the glock holder
1076 *
1077 */
1078
1079 void gfs2_glock_dq(struct gfs2_holder *gh)
1080 {
1081 struct gfs2_glock *gl = gh->gh_gl;
1082 const struct gfs2_glock_operations *glops = gl->gl_ops;
1083 unsigned delay = 0;
1084 int fast_path = 0;
1085
1086 spin_lock(&gl->gl_spin);
1087 if (gh->gh_flags & GL_NOCACHE)
1088 handle_callback(gl, LM_ST_UNLOCKED, 0);
1089
1090 list_del_init(&gh->gh_list);
1091 if (find_first_holder(gl) == NULL) {
1092 if (glops->go_unlock) {
1093 GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1094 spin_unlock(&gl->gl_spin);
1095 glops->go_unlock(gh);
1096 spin_lock(&gl->gl_spin);
1097 clear_bit(GLF_LOCK, &gl->gl_flags);
1098 }
1099 if (list_empty(&gl->gl_holders) &&
1100 !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1101 !test_bit(GLF_DEMOTE, &gl->gl_flags))
1102 fast_path = 1;
1103 }
1104 if (!test_bit(GLF_LFLUSH, &gl->gl_flags))
1105 __gfs2_glock_schedule_for_reclaim(gl);
1106 trace_gfs2_glock_queue(gh, 0);
1107 spin_unlock(&gl->gl_spin);
1108 if (likely(fast_path))
1109 return;
1110
1111 gfs2_glock_hold(gl);
1112 if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1113 !test_bit(GLF_DEMOTE, &gl->gl_flags) &&
1114 gl->gl_name.ln_type == LM_TYPE_INODE)
1115 delay = gl->gl_hold_time;
1116 if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1117 gfs2_glock_put(gl);
1118 }
1119
1120 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1121 {
1122 struct gfs2_glock *gl = gh->gh_gl;
1123 gfs2_glock_dq(gh);
1124 wait_on_demote(gl);
1125 }
1126
1127 /**
1128 * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1129 * @gh: the holder structure
1130 *
1131 */
1132
1133 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1134 {
1135 gfs2_glock_dq(gh);
1136 gfs2_holder_uninit(gh);
1137 }
1138
1139 /**
1140 * gfs2_glock_nq_num - acquire a glock based on lock number
1141 * @sdp: the filesystem
1142 * @number: the lock number
1143 * @glops: the glock operations for the type of glock
1144 * @state: the state to acquire the glock in
1145 * @flags: modifier flags for the acquisition
1146 * @gh: the struct gfs2_holder
1147 *
1148 * Returns: errno
1149 */
1150
1151 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1152 const struct gfs2_glock_operations *glops,
1153 unsigned int state, int flags, struct gfs2_holder *gh)
1154 {
1155 struct gfs2_glock *gl;
1156 int error;
1157
1158 error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1159 if (!error) {
1160 error = gfs2_glock_nq_init(gl, state, flags, gh);
1161 gfs2_glock_put(gl);
1162 }
1163
1164 return error;
1165 }
1166
1167 /**
1168 * glock_compare - Compare two struct gfs2_glock structures for sorting
1169 * @arg_a: the first structure
1170 * @arg_b: the second structure
1171 *
1172 */
1173
1174 static int glock_compare(const void *arg_a, const void *arg_b)
1175 {
1176 const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1177 const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1178 const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1179 const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1180
1181 if (a->ln_number > b->ln_number)
1182 return 1;
1183 if (a->ln_number < b->ln_number)
1184 return -1;
1185 BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1186 return 0;
1187 }
1188
1189 /**
1190 * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1191 * @num_gh: the number of structures
1192 * @ghs: an array of struct gfs2_holder structures
1193 *
1194 * Returns: 0 on success (all glocks acquired),
1195 * errno on failure (no glocks acquired)
1196 */
1197
1198 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1199 struct gfs2_holder **p)
1200 {
1201 unsigned int x;
1202 int error = 0;
1203
1204 for (x = 0; x < num_gh; x++)
1205 p[x] = &ghs[x];
1206
1207 sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1208
1209 for (x = 0; x < num_gh; x++) {
1210 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1211
1212 error = gfs2_glock_nq(p[x]);
1213 if (error) {
1214 while (x--)
1215 gfs2_glock_dq(p[x]);
1216 break;
1217 }
1218 }
1219
1220 return error;
1221 }
1222
1223 /**
1224 * gfs2_glock_nq_m - acquire multiple glocks
1225 * @num_gh: the number of structures
1226 * @ghs: an array of struct gfs2_holder structures
1227 *
1228 *
1229 * Returns: 0 on success (all glocks acquired),
1230 * errno on failure (no glocks acquired)
1231 */
1232
1233 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1234 {
1235 struct gfs2_holder *tmp[4];
1236 struct gfs2_holder **pph = tmp;
1237 int error = 0;
1238
1239 switch(num_gh) {
1240 case 0:
1241 return 0;
1242 case 1:
1243 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1244 return gfs2_glock_nq(ghs);
1245 default:
1246 if (num_gh <= 4)
1247 break;
1248 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1249 if (!pph)
1250 return -ENOMEM;
1251 }
1252
1253 error = nq_m_sync(num_gh, ghs, pph);
1254
1255 if (pph != tmp)
1256 kfree(pph);
1257
1258 return error;
1259 }
1260
1261 /**
1262 * gfs2_glock_dq_m - release multiple glocks
1263 * @num_gh: the number of structures
1264 * @ghs: an array of struct gfs2_holder structures
1265 *
1266 */
1267
1268 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1269 {
1270 while (num_gh--)
1271 gfs2_glock_dq(&ghs[num_gh]);
1272 }
1273
1274 /**
1275 * gfs2_glock_dq_uninit_m - release multiple glocks
1276 * @num_gh: the number of structures
1277 * @ghs: an array of struct gfs2_holder structures
1278 *
1279 */
1280
1281 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1282 {
1283 while (num_gh--)
1284 gfs2_glock_dq_uninit(&ghs[num_gh]);
1285 }
1286
1287 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1288 {
1289 unsigned long delay = 0;
1290 unsigned long holdtime;
1291 unsigned long now = jiffies;
1292
1293 gfs2_glock_hold(gl);
1294 holdtime = gl->gl_tchange + gl->gl_hold_time;
1295 if (test_bit(GLF_QUEUED, &gl->gl_flags) &&
1296 gl->gl_name.ln_type == LM_TYPE_INODE) {
1297 if (time_before(now, holdtime))
1298 delay = holdtime - now;
1299 if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1300 delay = gl->gl_hold_time;
1301 }
1302
1303 spin_lock(&gl->gl_spin);
1304 handle_callback(gl, state, delay);
1305 spin_unlock(&gl->gl_spin);
1306 if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1307 gfs2_glock_put(gl);
1308 }
1309
1310 /**
1311 * gfs2_should_freeze - Figure out if glock should be frozen
1312 * @gl: The glock in question
1313 *
1314 * Glocks are not frozen if (a) the result of the dlm operation is
1315 * an error, (b) the locking operation was an unlock operation or
1316 * (c) if there is a "noexp" flagged request anywhere in the queue
1317 *
1318 * Returns: 1 if freezing should occur, 0 otherwise
1319 */
1320
1321 static int gfs2_should_freeze(const struct gfs2_glock *gl)
1322 {
1323 const struct gfs2_holder *gh;
1324
1325 if (gl->gl_reply & ~LM_OUT_ST_MASK)
1326 return 0;
1327 if (gl->gl_target == LM_ST_UNLOCKED)
1328 return 0;
1329
1330 list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1331 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1332 continue;
1333 if (LM_FLAG_NOEXP & gh->gh_flags)
1334 return 0;
1335 }
1336
1337 return 1;
1338 }
1339
1340 /**
1341 * gfs2_glock_complete - Callback used by locking
1342 * @gl: Pointer to the glock
1343 * @ret: The return value from the dlm
1344 *
1345 * The gl_reply field is under the gl_spin lock so that it is ok
1346 * to use a bitfield shared with other glock state fields.
1347 */
1348
1349 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1350 {
1351 struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
1352
1353 spin_lock(&gl->gl_spin);
1354 gl->gl_reply = ret;
1355
1356 if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_flags))) {
1357 if (gfs2_should_freeze(gl)) {
1358 set_bit(GLF_FROZEN, &gl->gl_flags);
1359 spin_unlock(&gl->gl_spin);
1360 return;
1361 }
1362 }
1363
1364 spin_unlock(&gl->gl_spin);
1365 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1366 smp_wmb();
1367 gfs2_glock_hold(gl);
1368 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1369 gfs2_glock_put(gl);
1370 }
1371
1372
1373 static int gfs2_shrink_glock_memory(struct shrinker *shrink,
1374 struct shrink_control *sc)
1375 {
1376 struct gfs2_glock *gl;
1377 int may_demote;
1378 int nr_skipped = 0;
1379 int nr = sc->nr_to_scan;
1380 gfp_t gfp_mask = sc->gfp_mask;
1381 LIST_HEAD(skipped);
1382
1383 if (nr == 0)
1384 goto out;
1385
1386 if (!(gfp_mask & __GFP_FS))
1387 return -1;
1388
1389 spin_lock(&lru_lock);
1390 while(nr && !list_empty(&lru_list)) {
1391 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1392 list_del_init(&gl->gl_lru);
1393 clear_bit(GLF_LRU, &gl->gl_flags);
1394 atomic_dec(&lru_count);
1395
1396 /* Test for being demotable */
1397 if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1398 gfs2_glock_hold(gl);
1399 spin_unlock(&lru_lock);
1400 spin_lock(&gl->gl_spin);
1401 may_demote = demote_ok(gl);
1402 if (may_demote) {
1403 handle_callback(gl, LM_ST_UNLOCKED, 0);
1404 nr--;
1405 }
1406 clear_bit(GLF_LOCK, &gl->gl_flags);
1407 smp_mb__after_clear_bit();
1408 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1409 gfs2_glock_put_nolock(gl);
1410 spin_unlock(&gl->gl_spin);
1411 spin_lock(&lru_lock);
1412 continue;
1413 }
1414 nr_skipped++;
1415 list_add(&gl->gl_lru, &skipped);
1416 set_bit(GLF_LRU, &gl->gl_flags);
1417 }
1418 list_splice(&skipped, &lru_list);
1419 atomic_add(nr_skipped, &lru_count);
1420 spin_unlock(&lru_lock);
1421 out:
1422 return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
1423 }
1424
1425 static struct shrinker glock_shrinker = {
1426 .shrink = gfs2_shrink_glock_memory,
1427 .seeks = DEFAULT_SEEKS,
1428 };
1429
1430 /**
1431 * examine_bucket - Call a function for glock in a hash bucket
1432 * @examiner: the function
1433 * @sdp: the filesystem
1434 * @bucket: the bucket
1435 *
1436 */
1437
1438 static void examine_bucket(glock_examiner examiner, const struct gfs2_sbd *sdp,
1439 unsigned int hash)
1440 {
1441 struct gfs2_glock *gl;
1442 struct hlist_bl_head *head = &gl_hash_table[hash];
1443 struct hlist_bl_node *pos;
1444
1445 rcu_read_lock();
1446 hlist_bl_for_each_entry_rcu(gl, pos, head, gl_list) {
1447 if ((gl->gl_sbd == sdp) && atomic_read(&gl->gl_ref))
1448 examiner(gl);
1449 }
1450 rcu_read_unlock();
1451 cond_resched();
1452 }
1453
1454 static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
1455 {
1456 unsigned x;
1457
1458 for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1459 examine_bucket(examiner, sdp, x);
1460 }
1461
1462
1463 /**
1464 * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1465 * @gl: The glock to thaw
1466 *
1467 * N.B. When we freeze a glock, we leave a ref to the glock outstanding,
1468 * so this has to result in the ref count being dropped by one.
1469 */
1470
1471 static void thaw_glock(struct gfs2_glock *gl)
1472 {
1473 if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1474 return;
1475 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1476 gfs2_glock_hold(gl);
1477 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1478 gfs2_glock_put(gl);
1479 }
1480
1481 /**
1482 * clear_glock - look at a glock and see if we can free it from glock cache
1483 * @gl: the glock to look at
1484 *
1485 */
1486
1487 static void clear_glock(struct gfs2_glock *gl)
1488 {
1489 gfs2_glock_remove_from_lru(gl);
1490
1491 spin_lock(&gl->gl_spin);
1492 if (gl->gl_state != LM_ST_UNLOCKED)
1493 handle_callback(gl, LM_ST_UNLOCKED, 0);
1494 spin_unlock(&gl->gl_spin);
1495 gfs2_glock_hold(gl);
1496 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1497 gfs2_glock_put(gl);
1498 }
1499
1500 /**
1501 * gfs2_glock_thaw - Thaw any frozen glocks
1502 * @sdp: The super block
1503 *
1504 */
1505
1506 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1507 {
1508 glock_hash_walk(thaw_glock, sdp);
1509 }
1510
1511 static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1512 {
1513 int ret;
1514 spin_lock(&gl->gl_spin);
1515 ret = __dump_glock(seq, gl);
1516 spin_unlock(&gl->gl_spin);
1517 return ret;
1518 }
1519
1520 static void dump_glock_func(struct gfs2_glock *gl)
1521 {
1522 dump_glock(NULL, gl);
1523 }
1524
1525 /**
1526 * gfs2_gl_hash_clear - Empty out the glock hash table
1527 * @sdp: the filesystem
1528 * @wait: wait until it's all gone
1529 *
1530 * Called when unmounting the filesystem.
1531 */
1532
1533 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1534 {
1535 glock_hash_walk(clear_glock, sdp);
1536 flush_workqueue(glock_workqueue);
1537 wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
1538 glock_hash_walk(dump_glock_func, sdp);
1539 }
1540
1541 void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1542 {
1543 struct gfs2_glock *gl = ip->i_gl;
1544 int ret;
1545
1546 ret = gfs2_truncatei_resume(ip);
1547 gfs2_assert_withdraw(gl->gl_sbd, ret == 0);
1548
1549 spin_lock(&gl->gl_spin);
1550 clear_bit(GLF_LOCK, &gl->gl_flags);
1551 run_queue(gl, 1);
1552 spin_unlock(&gl->gl_spin);
1553 }
1554
1555 static const char *state2str(unsigned state)
1556 {
1557 switch(state) {
1558 case LM_ST_UNLOCKED:
1559 return "UN";
1560 case LM_ST_SHARED:
1561 return "SH";
1562 case LM_ST_DEFERRED:
1563 return "DF";
1564 case LM_ST_EXCLUSIVE:
1565 return "EX";
1566 }
1567 return "??";
1568 }
1569
1570 static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags)
1571 {
1572 char *p = buf;
1573 if (flags & LM_FLAG_TRY)
1574 *p++ = 't';
1575 if (flags & LM_FLAG_TRY_1CB)
1576 *p++ = 'T';
1577 if (flags & LM_FLAG_NOEXP)
1578 *p++ = 'e';
1579 if (flags & LM_FLAG_ANY)
1580 *p++ = 'A';
1581 if (flags & LM_FLAG_PRIORITY)
1582 *p++ = 'p';
1583 if (flags & GL_ASYNC)
1584 *p++ = 'a';
1585 if (flags & GL_EXACT)
1586 *p++ = 'E';
1587 if (flags & GL_NOCACHE)
1588 *p++ = 'c';
1589 if (test_bit(HIF_HOLDER, &iflags))
1590 *p++ = 'H';
1591 if (test_bit(HIF_WAIT, &iflags))
1592 *p++ = 'W';
1593 if (test_bit(HIF_FIRST, &iflags))
1594 *p++ = 'F';
1595 *p = 0;
1596 return buf;
1597 }
1598
1599 /**
1600 * dump_holder - print information about a glock holder
1601 * @seq: the seq_file struct
1602 * @gh: the glock holder
1603 *
1604 * Returns: 0 on success, -ENOBUFS when we run out of space
1605 */
1606
1607 static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1608 {
1609 struct task_struct *gh_owner = NULL;
1610 char flags_buf[32];
1611
1612 if (gh->gh_owner_pid)
1613 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1614 gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
1615 state2str(gh->gh_state),
1616 hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1617 gh->gh_error,
1618 gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1619 gh_owner ? gh_owner->comm : "(ended)",
1620 (void *)gh->gh_ip);
1621 return 0;
1622 }
1623
1624 static const char *gflags2str(char *buf, const struct gfs2_glock *gl)
1625 {
1626 const unsigned long *gflags = &gl->gl_flags;
1627 char *p = buf;
1628
1629 if (test_bit(GLF_LOCK, gflags))
1630 *p++ = 'l';
1631 if (test_bit(GLF_DEMOTE, gflags))
1632 *p++ = 'D';
1633 if (test_bit(GLF_PENDING_DEMOTE, gflags))
1634 *p++ = 'd';
1635 if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1636 *p++ = 'p';
1637 if (test_bit(GLF_DIRTY, gflags))
1638 *p++ = 'y';
1639 if (test_bit(GLF_LFLUSH, gflags))
1640 *p++ = 'f';
1641 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1642 *p++ = 'i';
1643 if (test_bit(GLF_REPLY_PENDING, gflags))
1644 *p++ = 'r';
1645 if (test_bit(GLF_INITIAL, gflags))
1646 *p++ = 'I';
1647 if (test_bit(GLF_FROZEN, gflags))
1648 *p++ = 'F';
1649 if (test_bit(GLF_QUEUED, gflags))
1650 *p++ = 'q';
1651 if (test_bit(GLF_LRU, gflags))
1652 *p++ = 'L';
1653 if (gl->gl_object)
1654 *p++ = 'o';
1655 *p = 0;
1656 return buf;
1657 }
1658
1659 /**
1660 * __dump_glock - print information about a glock
1661 * @seq: The seq_file struct
1662 * @gl: the glock
1663 *
1664 * The file format is as follows:
1665 * One line per object, capital letters are used to indicate objects
1666 * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1667 * other objects are indented by a single space and follow the glock to
1668 * which they are related. Fields are indicated by lower case letters
1669 * followed by a colon and the field value, except for strings which are in
1670 * [] so that its possible to see if they are composed of spaces for
1671 * example. The field's are n = number (id of the object), f = flags,
1672 * t = type, s = state, r = refcount, e = error, p = pid.
1673 *
1674 * Returns: 0 on success, -ENOBUFS when we run out of space
1675 */
1676
1677 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1678 {
1679 const struct gfs2_glock_operations *glops = gl->gl_ops;
1680 unsigned long long dtime;
1681 const struct gfs2_holder *gh;
1682 char gflags_buf[32];
1683 int error = 0;
1684
1685 dtime = jiffies - gl->gl_demote_time;
1686 dtime *= 1000000/HZ; /* demote time in uSec */
1687 if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1688 dtime = 0;
1689 gfs2_print_dbg(seq, "G: s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d v:%d r:%d m:%ld\n",
1690 state2str(gl->gl_state),
1691 gl->gl_name.ln_type,
1692 (unsigned long long)gl->gl_name.ln_number,
1693 gflags2str(gflags_buf, gl),
1694 state2str(gl->gl_target),
1695 state2str(gl->gl_demote_state), dtime,
1696 atomic_read(&gl->gl_ail_count),
1697 atomic_read(&gl->gl_revokes),
1698 atomic_read(&gl->gl_ref), gl->gl_hold_time);
1699
1700 list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1701 error = dump_holder(seq, gh);
1702 if (error)
1703 goto out;
1704 }
1705 if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1706 error = glops->go_dump(seq, gl);
1707 out:
1708 return error;
1709 }
1710
1711
1712
1713
1714 int __init gfs2_glock_init(void)
1715 {
1716 unsigned i;
1717 for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
1718 INIT_HLIST_BL_HEAD(&gl_hash_table[i]);
1719 }
1720
1721 glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
1722 WQ_HIGHPRI | WQ_FREEZABLE, 0);
1723 if (IS_ERR(glock_workqueue))
1724 return PTR_ERR(glock_workqueue);
1725 gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
1726 WQ_MEM_RECLAIM | WQ_FREEZABLE,
1727 0);
1728 if (IS_ERR(gfs2_delete_workqueue)) {
1729 destroy_workqueue(glock_workqueue);
1730 return PTR_ERR(gfs2_delete_workqueue);
1731 }
1732
1733 register_shrinker(&glock_shrinker);
1734
1735 return 0;
1736 }
1737
1738 void gfs2_glock_exit(void)
1739 {
1740 unregister_shrinker(&glock_shrinker);
1741 destroy_workqueue(glock_workqueue);
1742 destroy_workqueue(gfs2_delete_workqueue);
1743 }
1744
1745 static inline struct gfs2_glock *glock_hash_chain(unsigned hash)
1746 {
1747 return hlist_bl_entry(hlist_bl_first_rcu(&gl_hash_table[hash]),
1748 struct gfs2_glock, gl_list);
1749 }
1750
1751 static inline struct gfs2_glock *glock_hash_next(struct gfs2_glock *gl)
1752 {
1753 return hlist_bl_entry(rcu_dereference(gl->gl_list.next),
1754 struct gfs2_glock, gl_list);
1755 }
1756
1757 static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1758 {
1759 struct gfs2_glock *gl;
1760
1761 do {
1762 gl = gi->gl;
1763 if (gl) {
1764 gi->gl = glock_hash_next(gl);
1765 } else {
1766 gi->gl = glock_hash_chain(gi->hash);
1767 }
1768 while (gi->gl == NULL) {
1769 gi->hash++;
1770 if (gi->hash >= GFS2_GL_HASH_SIZE) {
1771 rcu_read_unlock();
1772 return 1;
1773 }
1774 gi->gl = glock_hash_chain(gi->hash);
1775 }
1776 /* Skip entries for other sb and dead entries */
1777 } while (gi->sdp != gi->gl->gl_sbd || atomic_read(&gi->gl->gl_ref) == 0);
1778
1779 return 0;
1780 }
1781
1782 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1783 {
1784 struct gfs2_glock_iter *gi = seq->private;
1785 loff_t n = *pos;
1786
1787 gi->hash = 0;
1788 rcu_read_lock();
1789
1790 do {
1791 if (gfs2_glock_iter_next(gi))
1792 return NULL;
1793 } while (n--);
1794
1795 return gi->gl;
1796 }
1797
1798 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1799 loff_t *pos)
1800 {
1801 struct gfs2_glock_iter *gi = seq->private;
1802
1803 (*pos)++;
1804
1805 if (gfs2_glock_iter_next(gi))
1806 return NULL;
1807
1808 return gi->gl;
1809 }
1810
1811 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1812 {
1813 struct gfs2_glock_iter *gi = seq->private;
1814
1815 if (gi->gl)
1816 rcu_read_unlock();
1817 gi->gl = NULL;
1818 }
1819
1820 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1821 {
1822 return dump_glock(seq, iter_ptr);
1823 }
1824
1825 static const struct seq_operations gfs2_glock_seq_ops = {
1826 .start = gfs2_glock_seq_start,
1827 .next = gfs2_glock_seq_next,
1828 .stop = gfs2_glock_seq_stop,
1829 .show = gfs2_glock_seq_show,
1830 };
1831
1832 static int gfs2_debugfs_open(struct inode *inode, struct file *file)
1833 {
1834 int ret = seq_open_private(file, &gfs2_glock_seq_ops,
1835 sizeof(struct gfs2_glock_iter));
1836 if (ret == 0) {
1837 struct seq_file *seq = file->private_data;
1838 struct gfs2_glock_iter *gi = seq->private;
1839 gi->sdp = inode->i_private;
1840 }
1841 return ret;
1842 }
1843
1844 static const struct file_operations gfs2_debug_fops = {
1845 .owner = THIS_MODULE,
1846 .open = gfs2_debugfs_open,
1847 .read = seq_read,
1848 .llseek = seq_lseek,
1849 .release = seq_release_private,
1850 };
1851
1852 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
1853 {
1854 sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
1855 if (!sdp->debugfs_dir)
1856 return -ENOMEM;
1857 sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
1858 S_IFREG | S_IRUGO,
1859 sdp->debugfs_dir, sdp,
1860 &gfs2_debug_fops);
1861 if (!sdp->debugfs_dentry_glocks)
1862 return -ENOMEM;
1863
1864 return 0;
1865 }
1866
1867 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
1868 {
1869 if (sdp && sdp->debugfs_dir) {
1870 if (sdp->debugfs_dentry_glocks) {
1871 debugfs_remove(sdp->debugfs_dentry_glocks);
1872 sdp->debugfs_dentry_glocks = NULL;
1873 }
1874 debugfs_remove(sdp->debugfs_dir);
1875 sdp->debugfs_dir = NULL;
1876 }
1877 }
1878
1879 int gfs2_register_debugfs(void)
1880 {
1881 gfs2_root = debugfs_create_dir("gfs2", NULL);
1882 return gfs2_root ? 0 : -ENOMEM;
1883 }
1884
1885 void gfs2_unregister_debugfs(void)
1886 {
1887 debugfs_remove(gfs2_root);
1888 gfs2_root = NULL;
1889 }
linux-next