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crc32: add missed brackets in macro
[linux-2.6.git] / fs / gfs2 / glock.c
blobe2431313491f1e54e136be64dcc3b0c3ba1033bc
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 struct hlist_bl_head *bl = &gl_hash_table[hash];
97 bit_spin_lock(0, (unsigned long *)bl);
98 }
99
100 static inline void spin_unlock_bucket(unsigned int hash)
101 {
102 struct hlist_bl_head *bl = &gl_hash_table[hash];
103 __bit_spin_unlock(0, (unsigned long *)bl);
104 }
105
106 static void gfs2_glock_dealloc(struct rcu_head *rcu)
107 {
108 struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu);
109
110 if (gl->gl_ops->go_flags & GLOF_ASPACE)
111 kmem_cache_free(gfs2_glock_aspace_cachep, gl);
112 else
113 kmem_cache_free(gfs2_glock_cachep, gl);
114 }
115
116 void gfs2_glock_free(struct gfs2_glock *gl)
117 {
118 struct gfs2_sbd *sdp = gl->gl_sbd;
119
120 call_rcu(&gl->gl_rcu, gfs2_glock_dealloc);
121 if (atomic_dec_and_test(&sdp->sd_glock_disposal))
122 wake_up(&sdp->sd_glock_wait);
123 }
124
125 /**
126 * gfs2_glock_hold() - increment reference count on glock
127 * @gl: The glock to hold
128 *
129 */
130
131 void gfs2_glock_hold(struct gfs2_glock *gl)
132 {
133 GLOCK_BUG_ON(gl, atomic_read(&gl->gl_ref) == 0);
134 atomic_inc(&gl->gl_ref);
135 }
136
137 /**
138 * demote_ok - Check to see if it's ok to unlock a glock
139 * @gl: the glock
140 *
141 * Returns: 1 if it's ok
142 */
143
144 static int demote_ok(const struct gfs2_glock *gl)
145 {
146 const struct gfs2_glock_operations *glops = gl->gl_ops;
147
148 /* assert_spin_locked(&gl->gl_spin); */
149
150 if (gl->gl_state == LM_ST_UNLOCKED)
151 return 0;
152 if (test_bit(GLF_LFLUSH, &gl->gl_flags))
153 return 0;
154 if ((gl->gl_name.ln_type != LM_TYPE_INODE) &&
155 !list_empty(&gl->gl_holders))
156 return 0;
157 if (glops->go_demote_ok)
158 return glops->go_demote_ok(gl);
159 return 1;
160 }
161
162
163 /**
164 * __gfs2_glock_schedule_for_reclaim - Add a glock to the reclaim list
165 * @gl: the glock
166 *
167 * If the glock is demotable, then we add it (or move it) to the end
168 * of the glock LRU list.
169 */
170
171 static void __gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
172 {
173 if (demote_ok(gl)) {
174 spin_lock(&lru_lock);
175
176 if (!list_empty(&gl->gl_lru))
177 list_del_init(&gl->gl_lru);
178 else
179 atomic_inc(&lru_count);
180
181 list_add_tail(&gl->gl_lru, &lru_list);
182 spin_unlock(&lru_lock);
183 }
184 }
185
186 void gfs2_glock_schedule_for_reclaim(struct gfs2_glock *gl)
187 {
188 spin_lock(&gl->gl_spin);
189 __gfs2_glock_schedule_for_reclaim(gl);
190 spin_unlock(&gl->gl_spin);
191 }
192
193 /**
194 * gfs2_glock_put_nolock() - Decrement reference count on glock
195 * @gl: The glock to put
196 *
197 * This function should only be used if the caller has its own reference
198 * to the glock, in addition to the one it is dropping.
199 */
200
201 void gfs2_glock_put_nolock(struct gfs2_glock *gl)
202 {
203 if (atomic_dec_and_test(&gl->gl_ref))
204 GLOCK_BUG_ON(gl, 1);
205 }
206
207 /**
208 * gfs2_glock_put() - Decrement reference count on glock
209 * @gl: The glock to put
210 *
211 */
212
213 void gfs2_glock_put(struct gfs2_glock *gl)
214 {
215 struct gfs2_sbd *sdp = gl->gl_sbd;
216 struct address_space *mapping = gfs2_glock2aspace(gl);
217
218 if (atomic_dec_and_test(&gl->gl_ref)) {
219 spin_lock_bucket(gl->gl_hash);
220 hlist_bl_del_rcu(&gl->gl_list);
221 spin_unlock_bucket(gl->gl_hash);
222 spin_lock(&lru_lock);
223 if (!list_empty(&gl->gl_lru)) {
224 list_del_init(&gl->gl_lru);
225 atomic_dec(&lru_count);
226 }
227 spin_unlock(&lru_lock);
228 GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
229 GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
230 trace_gfs2_glock_put(gl);
231 sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
232 }
233 }
234
235 /**
236 * search_bucket() - Find struct gfs2_glock by lock number
237 * @bucket: the bucket to search
238 * @name: The lock name
239 *
240 * Returns: NULL, or the struct gfs2_glock with the requested number
241 */
242
243 static struct gfs2_glock *search_bucket(unsigned int hash,
244 const struct gfs2_sbd *sdp,
245 const struct lm_lockname *name)
246 {
247 struct gfs2_glock *gl;
248 struct hlist_bl_node *h;
249
250 hlist_bl_for_each_entry_rcu(gl, h, &gl_hash_table[hash], gl_list) {
251 if (!lm_name_equal(&gl->gl_name, name))
252 continue;
253 if (gl->gl_sbd != sdp)
254 continue;
255 if (atomic_inc_not_zero(&gl->gl_ref))
256 return gl;
257 }
258
259 return NULL;
260 }
261
262 /**
263 * may_grant - check if its ok to grant a new lock
264 * @gl: The glock
265 * @gh: The lock request which we wish to grant
266 *
267 * Returns: true if its ok to grant the lock
268 */
269
270 static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
271 {
272 const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
273 if ((gh->gh_state == LM_ST_EXCLUSIVE ||
274 gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
275 return 0;
276 if (gl->gl_state == gh->gh_state)
277 return 1;
278 if (gh->gh_flags & GL_EXACT)
279 return 0;
280 if (gl->gl_state == LM_ST_EXCLUSIVE) {
281 if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
282 return 1;
283 if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
284 return 1;
285 }
286 if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
287 return 1;
288 return 0;
289 }
290
291 static void gfs2_holder_wake(struct gfs2_holder *gh)
292 {
293 clear_bit(HIF_WAIT, &gh->gh_iflags);
294 smp_mb__after_clear_bit();
295 wake_up_bit(&gh->gh_iflags, HIF_WAIT);
296 }
297
298 /**
299 * do_error - Something unexpected has happened during a lock request
300 *
301 */
302
303 static inline void do_error(struct gfs2_glock *gl, const int ret)
304 {
305 struct gfs2_holder *gh, *tmp;
306
307 list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
308 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
309 continue;
310 if (ret & LM_OUT_ERROR)
311 gh->gh_error = -EIO;
312 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
313 gh->gh_error = GLR_TRYFAILED;
314 else
315 continue;
316 list_del_init(&gh->gh_list);
317 trace_gfs2_glock_queue(gh, 0);
318 gfs2_holder_wake(gh);
319 }
320 }
321
322 /**
323 * do_promote - promote as many requests as possible on the current queue
324 * @gl: The glock
325 *
326 * Returns: 1 if there is a blocked holder at the head of the list, or 2
327 * if a type specific operation is underway.
328 */
329
330 static int do_promote(struct gfs2_glock *gl)
331 __releases(&gl->gl_spin)
332 __acquires(&gl->gl_spin)
333 {
334 const struct gfs2_glock_operations *glops = gl->gl_ops;
335 struct gfs2_holder *gh, *tmp;
336 int ret;
337
338 restart:
339 list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
340 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
341 continue;
342 if (may_grant(gl, gh)) {
343 if (gh->gh_list.prev == &gl->gl_holders &&
344 glops->go_lock) {
345 spin_unlock(&gl->gl_spin);
346 /* FIXME: eliminate this eventually */
347 ret = glops->go_lock(gh);
348 spin_lock(&gl->gl_spin);
349 if (ret) {
350 if (ret == 1)
351 return 2;
352 gh->gh_error = ret;
353 list_del_init(&gh->gh_list);
354 trace_gfs2_glock_queue(gh, 0);
355 gfs2_holder_wake(gh);
356 goto restart;
357 }
358 set_bit(HIF_HOLDER, &gh->gh_iflags);
359 trace_gfs2_promote(gh, 1);
360 gfs2_holder_wake(gh);
361 goto restart;
362 }
363 set_bit(HIF_HOLDER, &gh->gh_iflags);
364 trace_gfs2_promote(gh, 0);
365 gfs2_holder_wake(gh);
366 continue;
367 }
368 if (gh->gh_list.prev == &gl->gl_holders)
369 return 1;
370 do_error(gl, 0);
371 break;
372 }
373 return 0;
374 }
375
376 /**
377 * find_first_waiter - find the first gh that's waiting for the glock
378 * @gl: the glock
379 */
380
381 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
382 {
383 struct gfs2_holder *gh;
384
385 list_for_each_entry(gh, &gl->gl_holders, gh_list) {
386 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
387 return gh;
388 }
389 return NULL;
390 }
391
392 /**
393 * state_change - record that the glock is now in a different state
394 * @gl: the glock
395 * @new_state the new state
396 *
397 */
398
399 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
400 {
401 int held1, held2;
402
403 held1 = (gl->gl_state != LM_ST_UNLOCKED);
404 held2 = (new_state != LM_ST_UNLOCKED);
405
406 if (held1 != held2) {
407 if (held2)
408 gfs2_glock_hold(gl);
409 else
410 gfs2_glock_put_nolock(gl);
411 }
412 if (held1 && held2 && list_empty(&gl->gl_holders))
413 clear_bit(GLF_QUEUED, &gl->gl_flags);
414
415 gl->gl_state = new_state;
416 gl->gl_tchange = jiffies;
417 }
418
419 static void gfs2_demote_wake(struct gfs2_glock *gl)
420 {
421 gl->gl_demote_state = LM_ST_EXCLUSIVE;
422 clear_bit(GLF_DEMOTE, &gl->gl_flags);
423 smp_mb__after_clear_bit();
424 wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
425 }
426
427 /**
428 * finish_xmote - The DLM has replied to one of our lock requests
429 * @gl: The glock
430 * @ret: The status from the DLM
431 *
432 */
433
434 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
435 {
436 const struct gfs2_glock_operations *glops = gl->gl_ops;
437 struct gfs2_holder *gh;
438 unsigned state = ret & LM_OUT_ST_MASK;
439 int rv;
440
441 spin_lock(&gl->gl_spin);
442 trace_gfs2_glock_state_change(gl, state);
443 state_change(gl, state);
444 gh = find_first_waiter(gl);
445
446 /* Demote to UN request arrived during demote to SH or DF */
447 if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
448 state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
449 gl->gl_target = LM_ST_UNLOCKED;
450
451 /* Check for state != intended state */
452 if (unlikely(state != gl->gl_target)) {
453 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
454 /* move to back of queue and try next entry */
455 if (ret & LM_OUT_CANCELED) {
456 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
457 list_move_tail(&gh->gh_list, &gl->gl_holders);
458 gh = find_first_waiter(gl);
459 gl->gl_target = gh->gh_state;
460 goto retry;
461 }
462 /* Some error or failed "try lock" - report it */
463 if ((ret & LM_OUT_ERROR) ||
464 (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
465 gl->gl_target = gl->gl_state;
466 do_error(gl, ret);
467 goto out;
468 }
469 }
470 switch(state) {
471 /* Unlocked due to conversion deadlock, try again */
472 case LM_ST_UNLOCKED:
473 retry:
474 do_xmote(gl, gh, gl->gl_target);
475 break;
476 /* Conversion fails, unlock and try again */
477 case LM_ST_SHARED:
478 case LM_ST_DEFERRED:
479 do_xmote(gl, gh, LM_ST_UNLOCKED);
480 break;
481 default: /* Everything else */
482 printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
483 GLOCK_BUG_ON(gl, 1);
484 }
485 spin_unlock(&gl->gl_spin);
486 return;
487 }
488
489 /* Fast path - we got what we asked for */
490 if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
491 gfs2_demote_wake(gl);
492 if (state != LM_ST_UNLOCKED) {
493 if (glops->go_xmote_bh) {
494 spin_unlock(&gl->gl_spin);
495 rv = glops->go_xmote_bh(gl, gh);
496 spin_lock(&gl->gl_spin);
497 if (rv) {
498 do_error(gl, rv);
499 goto out;
500 }
501 }
502 rv = do_promote(gl);
503 if (rv == 2)
504 goto out_locked;
505 }
506 out:
507 clear_bit(GLF_LOCK, &gl->gl_flags);
508 out_locked:
509 spin_unlock(&gl->gl_spin);
510 }
511
512 /**
513 * do_xmote - Calls the DLM to change the state of a lock
514 * @gl: The lock state
515 * @gh: The holder (only for promotes)
516 * @target: The target lock state
517 *
518 */
519
520 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
521 __releases(&gl->gl_spin)
522 __acquires(&gl->gl_spin)
523 {
524 const struct gfs2_glock_operations *glops = gl->gl_ops;
525 struct gfs2_sbd *sdp = gl->gl_sbd;
526 unsigned int lck_flags = gh ? gh->gh_flags : 0;
527 int ret;
528
529 lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
530 LM_FLAG_PRIORITY);
531 GLOCK_BUG_ON(gl, gl->gl_state == target);
532 GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
533 if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
534 glops->go_inval) {
535 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
536 do_error(gl, 0); /* Fail queued try locks */
537 }
538 gl->gl_req = target;
539 spin_unlock(&gl->gl_spin);
540 if (glops->go_xmote_th)
541 glops->go_xmote_th(gl);
542 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
543 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
544 clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
545
546 gfs2_glock_hold(gl);
547 if (target != LM_ST_UNLOCKED && (gl->gl_state == LM_ST_SHARED ||
548 gl->gl_state == LM_ST_DEFERRED) &&
549 !(lck_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
550 lck_flags |= LM_FLAG_TRY_1CB;
551
552 if (sdp->sd_lockstruct.ls_ops->lm_lock) {
553 /* lock_dlm */
554 ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
555 GLOCK_BUG_ON(gl, ret);
556 } else { /* lock_nolock */
557 finish_xmote(gl, target);
558 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
559 gfs2_glock_put(gl);
560 }
561
562 spin_lock(&gl->gl_spin);
563 }
564
565 /**
566 * find_first_holder - find the first "holder" gh
567 * @gl: the glock
568 */
569
570 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
571 {
572 struct gfs2_holder *gh;
573
574 if (!list_empty(&gl->gl_holders)) {
575 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
576 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
577 return gh;
578 }
579 return NULL;
580 }
581
582 /**
583 * run_queue - do all outstanding tasks related to a glock
584 * @gl: The glock in question
585 * @nonblock: True if we must not block in run_queue
586 *
587 */
588
589 static void run_queue(struct gfs2_glock *gl, const int nonblock)
590 __releases(&gl->gl_spin)
591 __acquires(&gl->gl_spin)
592 {
593 struct gfs2_holder *gh = NULL;
594 int ret;
595
596 if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
597 return;
598
599 GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
600
601 if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
602 gl->gl_demote_state != gl->gl_state) {
603 if (find_first_holder(gl))
604 goto out_unlock;
605 if (nonblock)
606 goto out_sched;
607 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
608 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
609 gl->gl_target = gl->gl_demote_state;
610 } else {
611 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
612 gfs2_demote_wake(gl);
613 ret = do_promote(gl);
614 if (ret == 0)
615 goto out_unlock;
616 if (ret == 2)
617 goto out;
618 gh = find_first_waiter(gl);
619 gl->gl_target = gh->gh_state;
620 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
621 do_error(gl, 0); /* Fail queued try locks */
622 }
623 do_xmote(gl, gh, gl->gl_target);
624 out:
625 return;
626
627 out_sched:
628 clear_bit(GLF_LOCK, &gl->gl_flags);
629 smp_mb__after_clear_bit();
630 gfs2_glock_hold(gl);
631 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
632 gfs2_glock_put_nolock(gl);
633 return;
634
635 out_unlock:
636 clear_bit(GLF_LOCK, &gl->gl_flags);
637 smp_mb__after_clear_bit();
638 return;
639 }
640
641 static void delete_work_func(struct work_struct *work)
642 {
643 struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
644 struct gfs2_sbd *sdp = gl->gl_sbd;
645 struct gfs2_inode *ip;
646 struct inode *inode;
647 u64 no_addr = gl->gl_name.ln_number;
648
649 ip = gl->gl_object;
650 /* Note: Unsafe to dereference ip as we don't hold right refs/locks */
651
652 if (ip)
653 inode = gfs2_ilookup(sdp->sd_vfs, no_addr);
654 else
655 inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
656 if (inode && !IS_ERR(inode)) {
657 d_prune_aliases(inode);
658 iput(inode);
659 }
660 gfs2_glock_put(gl);
661 }
662
663 static void glock_work_func(struct work_struct *work)
664 {
665 unsigned long delay = 0;
666 struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
667 int drop_ref = 0;
668
669 if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
670 finish_xmote(gl, gl->gl_reply);
671 drop_ref = 1;
672 }
673 spin_lock(&gl->gl_spin);
674 if (test_and_clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
675 gl->gl_state != LM_ST_UNLOCKED &&
676 gl->gl_demote_state != LM_ST_EXCLUSIVE) {
677 unsigned long holdtime, now = jiffies;
678 holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
679 if (time_before(now, holdtime))
680 delay = holdtime - now;
681 set_bit(delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE, &gl->gl_flags);
682 }
683 run_queue(gl, 0);
684 spin_unlock(&gl->gl_spin);
685 if (!delay ||
686 queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
687 gfs2_glock_put(gl);
688 if (drop_ref)
689 gfs2_glock_put(gl);
690 }
691
692 /**
693 * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
694 * @sdp: The GFS2 superblock
695 * @number: the lock number
696 * @glops: The glock_operations to use
697 * @create: If 0, don't create the glock if it doesn't exist
698 * @glp: the glock is returned here
699 *
700 * This does not lock a glock, just finds/creates structures for one.
701 *
702 * Returns: errno
703 */
704
705 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
706 const struct gfs2_glock_operations *glops, int create,
707 struct gfs2_glock **glp)
708 {
709 struct super_block *s = sdp->sd_vfs;
710 struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
711 struct gfs2_glock *gl, *tmp;
712 unsigned int hash = gl_hash(sdp, &name);
713 struct address_space *mapping;
714 struct kmem_cache *cachep;
715
716 rcu_read_lock();
717 gl = search_bucket(hash, sdp, &name);
718 rcu_read_unlock();
719
720 *glp = gl;
721 if (gl)
722 return 0;
723 if (!create)
724 return -ENOENT;
725
726 if (glops->go_flags & GLOF_ASPACE)
727 cachep = gfs2_glock_aspace_cachep;
728 else
729 cachep = gfs2_glock_cachep;
730 gl = kmem_cache_alloc(cachep, GFP_KERNEL);
731 if (!gl)
732 return -ENOMEM;
733
734 atomic_inc(&sdp->sd_glock_disposal);
735 gl->gl_flags = 0;
736 gl->gl_name = name;
737 atomic_set(&gl->gl_ref, 1);
738 gl->gl_state = LM_ST_UNLOCKED;
739 gl->gl_target = LM_ST_UNLOCKED;
740 gl->gl_demote_state = LM_ST_EXCLUSIVE;
741 gl->gl_hash = hash;
742 gl->gl_ops = glops;
743 snprintf(gl->gl_strname, GDLM_STRNAME_BYTES, "%8x%16llx", name.ln_type, (unsigned long long)number);
744 memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
745 gl->gl_lksb.sb_lvbptr = gl->gl_lvb;
746 gl->gl_tchange = jiffies;
747 gl->gl_object = NULL;
748 gl->gl_sbd = sdp;
749 INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
750 INIT_WORK(&gl->gl_delete, delete_work_func);
751
752 mapping = gfs2_glock2aspace(gl);
753 if (mapping) {
754 mapping->a_ops = &gfs2_meta_aops;
755 mapping->host = s->s_bdev->bd_inode;
756 mapping->flags = 0;
757 mapping_set_gfp_mask(mapping, GFP_NOFS);
758 mapping->assoc_mapping = NULL;
759 mapping->backing_dev_info = s->s_bdi;
760 mapping->writeback_index = 0;
761 }
762
763 spin_lock_bucket(hash);
764 tmp = search_bucket(hash, sdp, &name);
765 if (tmp) {
766 spin_unlock_bucket(hash);
767 kmem_cache_free(cachep, gl);
768 atomic_dec(&sdp->sd_glock_disposal);
769 gl = tmp;
770 } else {
771 hlist_bl_add_head_rcu(&gl->gl_list, &gl_hash_table[hash]);
772 spin_unlock_bucket(hash);
773 }
774
775 *glp = gl;
776
777 return 0;
778 }
779
780 /**
781 * gfs2_holder_init - initialize a struct gfs2_holder in the default way
782 * @gl: the glock
783 * @state: the state we're requesting
784 * @flags: the modifier flags
785 * @gh: the holder structure
786 *
787 */
788
789 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
790 struct gfs2_holder *gh)
791 {
792 INIT_LIST_HEAD(&gh->gh_list);
793 gh->gh_gl = gl;
794 gh->gh_ip = (unsigned long)__builtin_return_address(0);
795 gh->gh_owner_pid = get_pid(task_pid(current));
796 gh->gh_state = state;
797 gh->gh_flags = flags;
798 gh->gh_error = 0;
799 gh->gh_iflags = 0;
800 gfs2_glock_hold(gl);
801 }
802
803 /**
804 * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
805 * @state: the state we're requesting
806 * @flags: the modifier flags
807 * @gh: the holder structure
808 *
809 * Don't mess with the glock.
810 *
811 */
812
813 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
814 {
815 gh->gh_state = state;
816 gh->gh_flags = flags;
817 gh->gh_iflags = 0;
818 gh->gh_ip = (unsigned long)__builtin_return_address(0);
819 if (gh->gh_owner_pid)
820 put_pid(gh->gh_owner_pid);
821 gh->gh_owner_pid = get_pid(task_pid(current));
822 }
823
824 /**
825 * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
826 * @gh: the holder structure
827 *
828 */
829
830 void gfs2_holder_uninit(struct gfs2_holder *gh)
831 {
832 put_pid(gh->gh_owner_pid);
833 gfs2_glock_put(gh->gh_gl);
834 gh->gh_gl = NULL;
835 gh->gh_ip = 0;
836 }
837
838 /**
839 * gfs2_glock_holder_wait
840 * @word: unused
841 *
842 * This function and gfs2_glock_demote_wait both show up in the WCHAN
843 * field. Thus I've separated these otherwise identical functions in
844 * order to be more informative to the user.
845 */
846
847 static int gfs2_glock_holder_wait(void *word)
848 {
849 schedule();
850 return 0;
851 }
852
853 static int gfs2_glock_demote_wait(void *word)
854 {
855 schedule();
856 return 0;
857 }
858
859 static void wait_on_holder(struct gfs2_holder *gh)
860 {
861 might_sleep();
862 wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
863 }
864
865 static void wait_on_demote(struct gfs2_glock *gl)
866 {
867 might_sleep();
868 wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
869 }
870
871 /**
872 * handle_callback - process a demote request
873 * @gl: the glock
874 * @state: the state the caller wants us to change to
875 *
876 * There are only two requests that we are going to see in actual
877 * practise: LM_ST_SHARED and LM_ST_UNLOCKED
878 */
879
880 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
881 unsigned long delay)
882 {
883 int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
884
885 set_bit(bit, &gl->gl_flags);
886 if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
887 gl->gl_demote_state = state;
888 gl->gl_demote_time = jiffies;
889 } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
890 gl->gl_demote_state != state) {
891 gl->gl_demote_state = LM_ST_UNLOCKED;
892 }
893 if (gl->gl_ops->go_callback)
894 gl->gl_ops->go_callback(gl);
895 trace_gfs2_demote_rq(gl);
896 }
897
898 /**
899 * gfs2_glock_wait - wait on a glock acquisition
900 * @gh: the glock holder
901 *
902 * Returns: 0 on success
903 */
904
905 int gfs2_glock_wait(struct gfs2_holder *gh)
906 {
907 wait_on_holder(gh);
908 return gh->gh_error;
909 }
910
911 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
912 {
913 struct va_format vaf;
914 va_list args;
915
916 va_start(args, fmt);
917
918 if (seq) {
919 struct gfs2_glock_iter *gi = seq->private;
920 vsprintf(gi->string, fmt, args);
921 seq_printf(seq, gi->string);
922 } else {
923 vaf.fmt = fmt;
924 vaf.va = &args;
925
926 printk(KERN_ERR " %pV", &vaf);
927 }
928
929 va_end(args);
930 }
931
932 /**
933 * add_to_queue - Add a holder to the wait queue (but look for recursion)
934 * @gh: the holder structure to add
935 *
936 * Eventually we should move the recursive locking trap to a
937 * debugging option or something like that. This is the fast
938 * path and needs to have the minimum number of distractions.
939 *
940 */
941
942 static inline void add_to_queue(struct gfs2_holder *gh)
943 __releases(&gl->gl_spin)
944 __acquires(&gl->gl_spin)
945 {
946 struct gfs2_glock *gl = gh->gh_gl;
947 struct gfs2_sbd *sdp = gl->gl_sbd;
948 struct list_head *insert_pt = NULL;
949 struct gfs2_holder *gh2;
950 int try_lock = 0;
951
952 BUG_ON(gh->gh_owner_pid == NULL);
953 if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
954 BUG();
955
956 if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
957 if (test_bit(GLF_LOCK, &gl->gl_flags))
958 try_lock = 1;
959 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
960 goto fail;
961 }
962
963 list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
964 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
965 (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
966 goto trap_recursive;
967 if (try_lock &&
968 !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) &&
969 !may_grant(gl, gh)) {
970 fail:
971 gh->gh_error = GLR_TRYFAILED;
972 gfs2_holder_wake(gh);
973 return;
974 }
975 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
976 continue;
977 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
978 insert_pt = &gh2->gh_list;
979 }
980 set_bit(GLF_QUEUED, &gl->gl_flags);
981 trace_gfs2_glock_queue(gh, 1);
982 if (likely(insert_pt == NULL)) {
983 list_add_tail(&gh->gh_list, &gl->gl_holders);
984 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
985 goto do_cancel;
986 return;
987 }
988 list_add_tail(&gh->gh_list, insert_pt);
989 do_cancel:
990 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
991 if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
992 spin_unlock(&gl->gl_spin);
993 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
994 sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
995 spin_lock(&gl->gl_spin);
996 }
997 return;
998
999 trap_recursive:
1000 print_symbol(KERN_ERR "original: %s\n", gh2->gh_ip);
1001 printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
1002 printk(KERN_ERR "lock type: %d req lock state : %d\n",
1003 gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
1004 print_symbol(KERN_ERR "new: %s\n", gh->gh_ip);
1005 printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
1006 printk(KERN_ERR "lock type: %d req lock state : %d\n",
1007 gh->gh_gl->gl_name.ln_type, gh->gh_state);
1008 __dump_glock(NULL, gl);
1009 BUG();
1010 }
1011
1012 /**
1013 * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1014 * @gh: the holder structure
1015 *
1016 * if (gh->gh_flags & GL_ASYNC), this never returns an error
1017 *
1018 * Returns: 0, GLR_TRYFAILED, or errno on failure
1019 */
1020
1021 int gfs2_glock_nq(struct gfs2_holder *gh)
1022 {
1023 struct gfs2_glock *gl = gh->gh_gl;
1024 struct gfs2_sbd *sdp = gl->gl_sbd;
1025 int error = 0;
1026
1027 if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
1028 return -EIO;
1029
1030 spin_lock(&gl->gl_spin);
1031 add_to_queue(gh);
1032 if ((LM_FLAG_NOEXP & gh->gh_flags) &&
1033 test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1034 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1035 run_queue(gl, 1);
1036 spin_unlock(&gl->gl_spin);
1037
1038 if (!(gh->gh_flags & GL_ASYNC))
1039 error = gfs2_glock_wait(gh);
1040
1041 return error;
1042 }
1043
1044 /**
1045 * gfs2_glock_poll - poll to see if an async request has been completed
1046 * @gh: the holder
1047 *
1048 * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1049 */
1050
1051 int gfs2_glock_poll(struct gfs2_holder *gh)
1052 {
1053 return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1054 }
1055
1056 /**
1057 * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1058 * @gh: the glock holder
1059 *
1060 */
1061
1062 void gfs2_glock_dq(struct gfs2_holder *gh)
1063 {
1064 struct gfs2_glock *gl = gh->gh_gl;
1065 const struct gfs2_glock_operations *glops = gl->gl_ops;
1066 unsigned delay = 0;
1067 int fast_path = 0;
1068
1069 spin_lock(&gl->gl_spin);
1070 if (gh->gh_flags & GL_NOCACHE)
1071 handle_callback(gl, LM_ST_UNLOCKED, 0);
1072
1073 list_del_init(&gh->gh_list);
1074 if (find_first_holder(gl) == NULL) {
1075 if (glops->go_unlock) {
1076 GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1077 spin_unlock(&gl->gl_spin);
1078 glops->go_unlock(gh);
1079 spin_lock(&gl->gl_spin);
1080 clear_bit(GLF_LOCK, &gl->gl_flags);
1081 }
1082 if (list_empty(&gl->gl_holders) &&
1083 !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1084 !test_bit(GLF_DEMOTE, &gl->gl_flags))
1085 fast_path = 1;
1086 }
1087 __gfs2_glock_schedule_for_reclaim(gl);
1088 trace_gfs2_glock_queue(gh, 0);
1089 spin_unlock(&gl->gl_spin);
1090 if (likely(fast_path))
1091 return;
1092
1093 gfs2_glock_hold(gl);
1094 if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1095 !test_bit(GLF_DEMOTE, &gl->gl_flags))
1096 delay = gl->gl_ops->go_min_hold_time;
1097 if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1098 gfs2_glock_put(gl);
1099 }
1100
1101 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1102 {
1103 struct gfs2_glock *gl = gh->gh_gl;
1104 gfs2_glock_dq(gh);
1105 wait_on_demote(gl);
1106 }
1107
1108 /**
1109 * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1110 * @gh: the holder structure
1111 *
1112 */
1113
1114 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1115 {
1116 gfs2_glock_dq(gh);
1117 gfs2_holder_uninit(gh);
1118 }
1119
1120 /**
1121 * gfs2_glock_nq_num - acquire a glock based on lock number
1122 * @sdp: the filesystem
1123 * @number: the lock number
1124 * @glops: the glock operations for the type of glock
1125 * @state: the state to acquire the glock in
1126 * @flags: modifier flags for the aquisition
1127 * @gh: the struct gfs2_holder
1128 *
1129 * Returns: errno
1130 */
1131
1132 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1133 const struct gfs2_glock_operations *glops,
1134 unsigned int state, int flags, struct gfs2_holder *gh)
1135 {
1136 struct gfs2_glock *gl;
1137 int error;
1138
1139 error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1140 if (!error) {
1141 error = gfs2_glock_nq_init(gl, state, flags, gh);
1142 gfs2_glock_put(gl);
1143 }
1144
1145 return error;
1146 }
1147
1148 /**
1149 * glock_compare - Compare two struct gfs2_glock structures for sorting
1150 * @arg_a: the first structure
1151 * @arg_b: the second structure
1152 *
1153 */
1154
1155 static int glock_compare(const void *arg_a, const void *arg_b)
1156 {
1157 const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1158 const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1159 const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1160 const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1161
1162 if (a->ln_number > b->ln_number)
1163 return 1;
1164 if (a->ln_number < b->ln_number)
1165 return -1;
1166 BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1167 return 0;
1168 }
1169
1170 /**
1171 * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1172 * @num_gh: the number of structures
1173 * @ghs: an array of struct gfs2_holder structures
1174 *
1175 * Returns: 0 on success (all glocks acquired),
1176 * errno on failure (no glocks acquired)
1177 */
1178
1179 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1180 struct gfs2_holder **p)
1181 {
1182 unsigned int x;
1183 int error = 0;
1184
1185 for (x = 0; x < num_gh; x++)
1186 p[x] = &ghs[x];
1187
1188 sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1189
1190 for (x = 0; x < num_gh; x++) {
1191 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1192
1193 error = gfs2_glock_nq(p[x]);
1194 if (error) {
1195 while (x--)
1196 gfs2_glock_dq(p[x]);
1197 break;
1198 }
1199 }
1200
1201 return error;
1202 }
1203
1204 /**
1205 * gfs2_glock_nq_m - acquire multiple glocks
1206 * @num_gh: the number of structures
1207 * @ghs: an array of struct gfs2_holder structures
1208 *
1209 *
1210 * Returns: 0 on success (all glocks acquired),
1211 * errno on failure (no glocks acquired)
1212 */
1213
1214 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1215 {
1216 struct gfs2_holder *tmp[4];
1217 struct gfs2_holder **pph = tmp;
1218 int error = 0;
1219
1220 switch(num_gh) {
1221 case 0:
1222 return 0;
1223 case 1:
1224 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1225 return gfs2_glock_nq(ghs);
1226 default:
1227 if (num_gh <= 4)
1228 break;
1229 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1230 if (!pph)
1231 return -ENOMEM;
1232 }
1233
1234 error = nq_m_sync(num_gh, ghs, pph);
1235
1236 if (pph != tmp)
1237 kfree(pph);
1238
1239 return error;
1240 }
1241
1242 /**
1243 * gfs2_glock_dq_m - release multiple glocks
1244 * @num_gh: the number of structures
1245 * @ghs: an array of struct gfs2_holder structures
1246 *
1247 */
1248
1249 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1250 {
1251 while (num_gh--)
1252 gfs2_glock_dq(&ghs[num_gh]);
1253 }
1254
1255 /**
1256 * gfs2_glock_dq_uninit_m - release multiple glocks
1257 * @num_gh: the number of structures
1258 * @ghs: an array of struct gfs2_holder structures
1259 *
1260 */
1261
1262 void gfs2_glock_dq_uninit_m(unsigned int num_gh, struct gfs2_holder *ghs)
1263 {
1264 while (num_gh--)
1265 gfs2_glock_dq_uninit(&ghs[num_gh]);
1266 }
1267
1268 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1269 {
1270 unsigned long delay = 0;
1271 unsigned long holdtime;
1272 unsigned long now = jiffies;
1273
1274 gfs2_glock_hold(gl);
1275 holdtime = gl->gl_tchange + gl->gl_ops->go_min_hold_time;
1276 if (test_bit(GLF_QUEUED, &gl->gl_flags)) {
1277 if (time_before(now, holdtime))
1278 delay = holdtime - now;
1279 if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1280 delay = gl->gl_ops->go_min_hold_time;
1281 }
1282
1283 spin_lock(&gl->gl_spin);
1284 handle_callback(gl, state, delay);
1285 spin_unlock(&gl->gl_spin);
1286 if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1287 gfs2_glock_put(gl);
1288 }
1289
1290 /**
1291 * gfs2_should_freeze - Figure out if glock should be frozen
1292 * @gl: The glock in question
1293 *
1294 * Glocks are not frozen if (a) the result of the dlm operation is
1295 * an error, (b) the locking operation was an unlock operation or
1296 * (c) if there is a "noexp" flagged request anywhere in the queue
1297 *
1298 * Returns: 1 if freezing should occur, 0 otherwise
1299 */
1300
1301 static int gfs2_should_freeze(const struct gfs2_glock *gl)
1302 {
1303 const struct gfs2_holder *gh;
1304
1305 if (gl->gl_reply & ~LM_OUT_ST_MASK)
1306 return 0;
1307 if (gl->gl_target == LM_ST_UNLOCKED)
1308 return 0;
1309
1310 list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1311 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1312 continue;
1313 if (LM_FLAG_NOEXP & gh->gh_flags)
1314 return 0;
1315 }
1316
1317 return 1;
1318 }
1319
1320 /**
1321 * gfs2_glock_complete - Callback used by locking
1322 * @gl: Pointer to the glock
1323 * @ret: The return value from the dlm
1324 *
1325 * The gl_reply field is under the gl_spin lock so that it is ok
1326 * to use a bitfield shared with other glock state fields.
1327 */
1328
1329 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1330 {
1331 struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
1332
1333 spin_lock(&gl->gl_spin);
1334 gl->gl_reply = ret;
1335
1336 if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_flags))) {
1337 if (gfs2_should_freeze(gl)) {
1338 set_bit(GLF_FROZEN, &gl->gl_flags);
1339 spin_unlock(&gl->gl_spin);
1340 return;
1341 }
1342 }
1343
1344 spin_unlock(&gl->gl_spin);
1345 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1346 smp_wmb();
1347 gfs2_glock_hold(gl);
1348 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1349 gfs2_glock_put(gl);
1350 }
1351
1352
1353 static int gfs2_shrink_glock_memory(struct shrinker *shrink, int nr, gfp_t gfp_mask)
1354 {
1355 struct gfs2_glock *gl;
1356 int may_demote;
1357 int nr_skipped = 0;
1358 LIST_HEAD(skipped);
1359
1360 if (nr == 0)
1361 goto out;
1362
1363 if (!(gfp_mask & __GFP_FS))
1364 return -1;
1365
1366 spin_lock(&lru_lock);
1367 while(nr && !list_empty(&lru_list)) {
1368 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1369 list_del_init(&gl->gl_lru);
1370 atomic_dec(&lru_count);
1371
1372 /* Test for being demotable */
1373 if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1374 gfs2_glock_hold(gl);
1375 spin_unlock(&lru_lock);
1376 spin_lock(&gl->gl_spin);
1377 may_demote = demote_ok(gl);
1378 if (may_demote) {
1379 handle_callback(gl, LM_ST_UNLOCKED, 0);
1380 nr--;
1381 }
1382 clear_bit(GLF_LOCK, &gl->gl_flags);
1383 smp_mb__after_clear_bit();
1384 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1385 gfs2_glock_put_nolock(gl);
1386 spin_unlock(&gl->gl_spin);
1387 spin_lock(&lru_lock);
1388 continue;
1389 }
1390 nr_skipped++;
1391 list_add(&gl->gl_lru, &skipped);
1392 }
1393 list_splice(&skipped, &lru_list);
1394 atomic_add(nr_skipped, &lru_count);
1395 spin_unlock(&lru_lock);
1396 out:
1397 return (atomic_read(&lru_count) / 100) * sysctl_vfs_cache_pressure;
1398 }
1399
1400 static struct shrinker glock_shrinker = {
1401 .shrink = gfs2_shrink_glock_memory,
1402 .seeks = DEFAULT_SEEKS,
1403 };
1404
1405 /**
1406 * examine_bucket - Call a function for glock in a hash bucket
1407 * @examiner: the function
1408 * @sdp: the filesystem
1409 * @bucket: the bucket
1410 *
1411 */
1412
1413 static void examine_bucket(glock_examiner examiner, const struct gfs2_sbd *sdp,
1414 unsigned int hash)
1415 {
1416 struct gfs2_glock *gl;
1417 struct hlist_bl_head *head = &gl_hash_table[hash];
1418 struct hlist_bl_node *pos;
1419
1420 rcu_read_lock();
1421 hlist_bl_for_each_entry_rcu(gl, pos, head, gl_list) {
1422 if ((gl->gl_sbd == sdp) && atomic_read(&gl->gl_ref))
1423 examiner(gl);
1424 }
1425 rcu_read_unlock();
1426 cond_resched();
1427 }
1428
1429 static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
1430 {
1431 unsigned x;
1432
1433 for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1434 examine_bucket(examiner, sdp, x);
1435 }
1436
1437
1438 /**
1439 * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1440 * @gl: The glock to thaw
1441 *
1442 * N.B. When we freeze a glock, we leave a ref to the glock outstanding,
1443 * so this has to result in the ref count being dropped by one.
1444 */
1445
1446 static void thaw_glock(struct gfs2_glock *gl)
1447 {
1448 if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1449 return;
1450 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1451 gfs2_glock_hold(gl);
1452 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1453 gfs2_glock_put(gl);
1454 }
1455
1456 /**
1457 * clear_glock - look at a glock and see if we can free it from glock cache
1458 * @gl: the glock to look at
1459 *
1460 */
1461
1462 static void clear_glock(struct gfs2_glock *gl)
1463 {
1464 spin_lock(&lru_lock);
1465 if (!list_empty(&gl->gl_lru)) {
1466 list_del_init(&gl->gl_lru);
1467 atomic_dec(&lru_count);
1468 }
1469 spin_unlock(&lru_lock);
1470
1471 spin_lock(&gl->gl_spin);
1472 if (gl->gl_state != LM_ST_UNLOCKED)
1473 handle_callback(gl, LM_ST_UNLOCKED, 0);
1474 spin_unlock(&gl->gl_spin);
1475 gfs2_glock_hold(gl);
1476 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1477 gfs2_glock_put(gl);
1478 }
1479
1480 /**
1481 * gfs2_glock_thaw - Thaw any frozen glocks
1482 * @sdp: The super block
1483 *
1484 */
1485
1486 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1487 {
1488 glock_hash_walk(thaw_glock, sdp);
1489 }
1490
1491 static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1492 {
1493 int ret;
1494 spin_lock(&gl->gl_spin);
1495 ret = __dump_glock(seq, gl);
1496 spin_unlock(&gl->gl_spin);
1497 return ret;
1498 }
1499
1500 static void dump_glock_func(struct gfs2_glock *gl)
1501 {
1502 dump_glock(NULL, gl);
1503 }
1504
1505 /**
1506 * gfs2_gl_hash_clear - Empty out the glock hash table
1507 * @sdp: the filesystem
1508 * @wait: wait until it's all gone
1509 *
1510 * Called when unmounting the filesystem.
1511 */
1512
1513 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1514 {
1515 glock_hash_walk(clear_glock, sdp);
1516 flush_workqueue(glock_workqueue);
1517 wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
1518 glock_hash_walk(dump_glock_func, sdp);
1519 }
1520
1521 void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1522 {
1523 struct gfs2_glock *gl = ip->i_gl;
1524 int ret;
1525
1526 ret = gfs2_truncatei_resume(ip);
1527 gfs2_assert_withdraw(gl->gl_sbd, ret == 0);
1528
1529 spin_lock(&gl->gl_spin);
1530 clear_bit(GLF_LOCK, &gl->gl_flags);
1531 run_queue(gl, 1);
1532 spin_unlock(&gl->gl_spin);
1533 }
1534
1535 static const char *state2str(unsigned state)
1536 {
1537 switch(state) {
1538 case LM_ST_UNLOCKED:
1539 return "UN";
1540 case LM_ST_SHARED:
1541 return "SH";
1542 case LM_ST_DEFERRED:
1543 return "DF";
1544 case LM_ST_EXCLUSIVE:
1545 return "EX";
1546 }
1547 return "??";
1548 }
1549
1550 static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags)
1551 {
1552 char *p = buf;
1553 if (flags & LM_FLAG_TRY)
1554 *p++ = 't';
1555 if (flags & LM_FLAG_TRY_1CB)
1556 *p++ = 'T';
1557 if (flags & LM_FLAG_NOEXP)
1558 *p++ = 'e';
1559 if (flags & LM_FLAG_ANY)
1560 *p++ = 'A';
1561 if (flags & LM_FLAG_PRIORITY)
1562 *p++ = 'p';
1563 if (flags & GL_ASYNC)
1564 *p++ = 'a';
1565 if (flags & GL_EXACT)
1566 *p++ = 'E';
1567 if (flags & GL_NOCACHE)
1568 *p++ = 'c';
1569 if (test_bit(HIF_HOLDER, &iflags))
1570 *p++ = 'H';
1571 if (test_bit(HIF_WAIT, &iflags))
1572 *p++ = 'W';
1573 if (test_bit(HIF_FIRST, &iflags))
1574 *p++ = 'F';
1575 *p = 0;
1576 return buf;
1577 }
1578
1579 /**
1580 * dump_holder - print information about a glock holder
1581 * @seq: the seq_file struct
1582 * @gh: the glock holder
1583 *
1584 * Returns: 0 on success, -ENOBUFS when we run out of space
1585 */
1586
1587 static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1588 {
1589 struct task_struct *gh_owner = NULL;
1590 char flags_buf[32];
1591
1592 if (gh->gh_owner_pid)
1593 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1594 gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
1595 state2str(gh->gh_state),
1596 hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1597 gh->gh_error,
1598 gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1599 gh_owner ? gh_owner->comm : "(ended)",
1600 (void *)gh->gh_ip);
1601 return 0;
1602 }
1603
1604 static const char *gflags2str(char *buf, const unsigned long *gflags)
1605 {
1606 char *p = buf;
1607 if (test_bit(GLF_LOCK, gflags))
1608 *p++ = 'l';
1609 if (test_bit(GLF_DEMOTE, gflags))
1610 *p++ = 'D';
1611 if (test_bit(GLF_PENDING_DEMOTE, gflags))
1612 *p++ = 'd';
1613 if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1614 *p++ = 'p';
1615 if (test_bit(GLF_DIRTY, gflags))
1616 *p++ = 'y';
1617 if (test_bit(GLF_LFLUSH, gflags))
1618 *p++ = 'f';
1619 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1620 *p++ = 'i';
1621 if (test_bit(GLF_REPLY_PENDING, gflags))
1622 *p++ = 'r';
1623 if (test_bit(GLF_INITIAL, gflags))
1624 *p++ = 'I';
1625 if (test_bit(GLF_FROZEN, gflags))
1626 *p++ = 'F';
1627 if (test_bit(GLF_QUEUED, gflags))
1628 *p++ = 'q';
1629 *p = 0;
1630 return buf;
1631 }
1632
1633 /**
1634 * __dump_glock - print information about a glock
1635 * @seq: The seq_file struct
1636 * @gl: the glock
1637 *
1638 * The file format is as follows:
1639 * One line per object, capital letters are used to indicate objects
1640 * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1641 * other objects are indented by a single space and follow the glock to
1642 * which they are related. Fields are indicated by lower case letters
1643 * followed by a colon and the field value, except for strings which are in
1644 * [] so that its possible to see if they are composed of spaces for
1645 * example. The field's are n = number (id of the object), f = flags,
1646 * t = type, s = state, r = refcount, e = error, p = pid.
1647 *
1648 * Returns: 0 on success, -ENOBUFS when we run out of space
1649 */
1650
1651 static int __dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1652 {
1653 const struct gfs2_glock_operations *glops = gl->gl_ops;
1654 unsigned long long dtime;
1655 const struct gfs2_holder *gh;
1656 char gflags_buf[32];
1657 int error = 0;
1658
1659 dtime = jiffies - gl->gl_demote_time;
1660 dtime *= 1000000/HZ; /* demote time in uSec */
1661 if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1662 dtime = 0;
1663 gfs2_print_dbg(seq, "G: s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d r:%d\n",
1664 state2str(gl->gl_state),
1665 gl->gl_name.ln_type,
1666 (unsigned long long)gl->gl_name.ln_number,
1667 gflags2str(gflags_buf, &gl->gl_flags),
1668 state2str(gl->gl_target),
1669 state2str(gl->gl_demote_state), dtime,
1670 atomic_read(&gl->gl_ail_count),
1671 atomic_read(&gl->gl_ref));
1672
1673 list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1674 error = dump_holder(seq, gh);
1675 if (error)
1676 goto out;
1677 }
1678 if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1679 error = glops->go_dump(seq, gl);
1680 out:
1681 return error;
1682 }
1683
1684
1685
1686
1687 int __init gfs2_glock_init(void)
1688 {
1689 unsigned i;
1690 for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
1691 INIT_HLIST_BL_HEAD(&gl_hash_table[i]);
1692 }
1693
1694 glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
1695 WQ_HIGHPRI | WQ_FREEZABLE, 0);
1696 if (IS_ERR(glock_workqueue))
1697 return PTR_ERR(glock_workqueue);
1698 gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
1699 WQ_MEM_RECLAIM | WQ_FREEZABLE,
1700 0);
1701 if (IS_ERR(gfs2_delete_workqueue)) {
1702 destroy_workqueue(glock_workqueue);
1703 return PTR_ERR(gfs2_delete_workqueue);
1704 }
1705
1706 register_shrinker(&glock_shrinker);
1707
1708 return 0;
1709 }
1710
1711 void gfs2_glock_exit(void)
1712 {
1713 unregister_shrinker(&glock_shrinker);
1714 destroy_workqueue(glock_workqueue);
1715 destroy_workqueue(gfs2_delete_workqueue);
1716 }
1717
1718 static inline struct gfs2_glock *glock_hash_chain(unsigned hash)
1719 {
1720 return hlist_bl_entry(hlist_bl_first_rcu(&gl_hash_table[hash]),
1721 struct gfs2_glock, gl_list);
1722 }
1723
1724 static inline struct gfs2_glock *glock_hash_next(struct gfs2_glock *gl)
1725 {
1726 return hlist_bl_entry(rcu_dereference(gl->gl_list.next),
1727 struct gfs2_glock, gl_list);
1728 }
1729
1730 static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1731 {
1732 struct gfs2_glock *gl;
1733
1734 do {
1735 gl = gi->gl;
1736 if (gl) {
1737 gi->gl = glock_hash_next(gl);
1738 } else {
1739 gi->gl = glock_hash_chain(gi->hash);
1740 }
1741 while (gi->gl == NULL) {
1742 gi->hash++;
1743 if (gi->hash >= GFS2_GL_HASH_SIZE) {
1744 rcu_read_unlock();
1745 return 1;
1746 }
1747 gi->gl = glock_hash_chain(gi->hash);
1748 }
1749 /* Skip entries for other sb and dead entries */
1750 } while (gi->sdp != gi->gl->gl_sbd || atomic_read(&gi->gl->gl_ref) == 0);
1751
1752 return 0;
1753 }
1754
1755 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1756 {
1757 struct gfs2_glock_iter *gi = seq->private;
1758 loff_t n = *pos;
1759
1760 gi->hash = 0;
1761 rcu_read_lock();
1762
1763 do {
1764 if (gfs2_glock_iter_next(gi))
1765 return NULL;
1766 } while (n--);
1767
1768 return gi->gl;
1769 }
1770
1771 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1772 loff_t *pos)
1773 {
1774 struct gfs2_glock_iter *gi = seq->private;
1775
1776 (*pos)++;
1777
1778 if (gfs2_glock_iter_next(gi))
1779 return NULL;
1780
1781 return gi->gl;
1782 }
1783
1784 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1785 {
1786 struct gfs2_glock_iter *gi = seq->private;
1787
1788 if (gi->gl)
1789 rcu_read_unlock();
1790 gi->gl = NULL;
1791 }
1792
1793 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1794 {
1795 return dump_glock(seq, iter_ptr);
1796 }
1797
1798 static const struct seq_operations gfs2_glock_seq_ops = {
1799 .start = gfs2_glock_seq_start,
1800 .next = gfs2_glock_seq_next,
1801 .stop = gfs2_glock_seq_stop,
1802 .show = gfs2_glock_seq_show,
1803 };
1804
1805 static int gfs2_debugfs_open(struct inode *inode, struct file *file)
1806 {
1807 int ret = seq_open_private(file, &gfs2_glock_seq_ops,
1808 sizeof(struct gfs2_glock_iter));
1809 if (ret == 0) {
1810 struct seq_file *seq = file->private_data;
1811 struct gfs2_glock_iter *gi = seq->private;
1812 gi->sdp = inode->i_private;
1813 }
1814 return ret;
1815 }
1816
1817 static const struct file_operations gfs2_debug_fops = {
1818 .owner = THIS_MODULE,
1819 .open = gfs2_debugfs_open,
1820 .read = seq_read,
1821 .llseek = seq_lseek,
1822 .release = seq_release_private,
1823 };
1824
1825 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
1826 {
1827 sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
1828 if (!sdp->debugfs_dir)
1829 return -ENOMEM;
1830 sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
1831 S_IFREG | S_IRUGO,
1832 sdp->debugfs_dir, sdp,
1833 &gfs2_debug_fops);
1834 if (!sdp->debugfs_dentry_glocks)
1835 return -ENOMEM;
1836
1837 return 0;
1838 }
1839
1840 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
1841 {
1842 if (sdp && sdp->debugfs_dir) {
1843 if (sdp->debugfs_dentry_glocks) {
1844 debugfs_remove(sdp->debugfs_dentry_glocks);
1845 sdp->debugfs_dentry_glocks = NULL;
1846 }
1847 debugfs_remove(sdp->debugfs_dir);
1848 sdp->debugfs_dir = NULL;
1849 }
1850 }
1851
1852 int gfs2_register_debugfs(void)
1853 {
1854 gfs2_root = debugfs_create_dir("gfs2", NULL);
1855 return gfs2_root ? 0 : -ENOMEM;
1856 }
1857
1858 void gfs2_unregister_debugfs(void)
1859 {
1860 debugfs_remove(gfs2_root);
1861 gfs2_root = NULL;
1862 }
Linus' kernel tree