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

Version: ~ [ linux-4.14 ] ~ [ linux-4.13.12 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.61 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.97 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.46 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.80 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.50 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.95 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.39.4 ] ~ [ linux-2.6.38.8 ] ~ [ linux-2.6.37.6 ] ~ [ linux-2.6.36.4 ] ~ [ linux-2.6.35.14 ] ~ [ linux-2.6.34.15 ] ~ [ linux-2.6.33.20 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.27.62 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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  1 /*
  2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
  3  * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
  4  *
  5  * This copyrighted material is made available to anyone wishing to use,
  6  * modify, copy, or redistribute it subject to the terms and conditions
  7  * of the GNU General Public License version 2.
  8  */
  9 
 10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 11 
 12 #include <linux/sched.h>
 13 #include <linux/slab.h>
 14 #include <linux/spinlock.h>
 15 #include <linux/buffer_head.h>
 16 #include <linux/delay.h>
 17 #include <linux/sort.h>
 18 #include <linux/hash.h>
 19 #include <linux/jhash.h>
 20 #include <linux/kallsyms.h>
 21 #include <linux/gfs2_ondisk.h>
 22 #include <linux/list.h>
 23 #include <linux/wait.h>
 24 #include <linux/module.h>
 25 #include <linux/uaccess.h>
 26 #include <linux/seq_file.h>
 27 #include <linux/debugfs.h>
 28 #include <linux/kthread.h>
 29 #include <linux/freezer.h>
 30 #include <linux/workqueue.h>
 31 #include <linux/jiffies.h>
 32 #include <linux/rcupdate.h>
 33 #include <linux/rculist_bl.h>
 34 #include <linux/bit_spinlock.h>
 35 #include <linux/percpu.h>
 36 #include <linux/list_sort.h>
 37 #include <linux/lockref.h>
 38 #include <linux/rhashtable.h>
 39 
 40 #include "gfs2.h"
 41 #include "incore.h"
 42 #include "glock.h"
 43 #include "glops.h"
 44 #include "inode.h"
 45 #include "lops.h"
 46 #include "meta_io.h"
 47 #include "quota.h"
 48 #include "super.h"
 49 #include "util.h"
 50 #include "bmap.h"
 51 #define CREATE_TRACE_POINTS
 52 #include "trace_gfs2.h"
 53 
 54 struct gfs2_glock_iter {
 55         struct gfs2_sbd *sdp;           /* incore superblock           */
 56         struct rhashtable_iter hti;     /* rhashtable iterator         */
 57         struct gfs2_glock *gl;          /* current glock struct        */
 58         loff_t last_pos;                /* last position               */
 59 };
 60 
 61 typedef void (*glock_examiner) (struct gfs2_glock * gl);
 62 
 63 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
 64 
 65 static struct dentry *gfs2_root;
 66 static struct workqueue_struct *glock_workqueue;
 67 struct workqueue_struct *gfs2_delete_workqueue;
 68 static LIST_HEAD(lru_list);
 69 static atomic_t lru_count = ATOMIC_INIT(0);
 70 static DEFINE_SPINLOCK(lru_lock);
 71 
 72 #define GFS2_GL_HASH_SHIFT      15
 73 #define GFS2_GL_HASH_SIZE       BIT(GFS2_GL_HASH_SHIFT)
 74 
 75 static const struct rhashtable_params ht_parms = {
 76         .nelem_hint = GFS2_GL_HASH_SIZE * 3 / 4,
 77         .key_len = offsetofend(struct lm_lockname, ln_type),
 78         .key_offset = offsetof(struct gfs2_glock, gl_name),
 79         .head_offset = offsetof(struct gfs2_glock, gl_node),
 80 };
 81 
 82 static struct rhashtable gl_hash_table;
 83 
 84 #define GLOCK_WAIT_TABLE_BITS 12
 85 #define GLOCK_WAIT_TABLE_SIZE (1 << GLOCK_WAIT_TABLE_BITS)
 86 static wait_queue_head_t glock_wait_table[GLOCK_WAIT_TABLE_SIZE] __cacheline_aligned;
 87 
 88 struct wait_glock_queue {
 89         struct lm_lockname *name;
 90         wait_queue_entry_t wait;
 91 };
 92 
 93 static int glock_wake_function(wait_queue_entry_t *wait, unsigned int mode,
 94                                int sync, void *key)
 95 {
 96         struct wait_glock_queue *wait_glock =
 97                 container_of(wait, struct wait_glock_queue, wait);
 98         struct lm_lockname *wait_name = wait_glock->name;
 99         struct lm_lockname *wake_name = key;
100 
101         if (wake_name->ln_sbd != wait_name->ln_sbd ||
102             wake_name->ln_number != wait_name->ln_number ||
103             wake_name->ln_type != wait_name->ln_type)
104                 return 0;
105         return autoremove_wake_function(wait, mode, sync, key);
106 }
107 
108 static wait_queue_head_t *glock_waitqueue(struct lm_lockname *name)
109 {
110         u32 hash = jhash2((u32 *)name, sizeof(*name) / 4, 0);
111 
112         return glock_wait_table + hash_32(hash, GLOCK_WAIT_TABLE_BITS);
113 }
114 
115 /**
116  * wake_up_glock  -  Wake up waiters on a glock
117  * @gl: the glock
118  */
119 static void wake_up_glock(struct gfs2_glock *gl)
120 {
121         wait_queue_head_t *wq = glock_waitqueue(&gl->gl_name);
122 
123         if (waitqueue_active(wq))
124                 __wake_up(wq, TASK_NORMAL, 1, &gl->gl_name);
125 }
126 
127 static void gfs2_glock_dealloc(struct rcu_head *rcu)
128 {
129         struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu);
130 
131         if (gl->gl_ops->go_flags & GLOF_ASPACE) {
132                 kmem_cache_free(gfs2_glock_aspace_cachep, gl);
133         } else {
134                 kfree(gl->gl_lksb.sb_lvbptr);
135                 kmem_cache_free(gfs2_glock_cachep, gl);
136         }
137 }
138 
139 void gfs2_glock_free(struct gfs2_glock *gl)
140 {
141         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
142 
143         rhashtable_remove_fast(&gl_hash_table, &gl->gl_node, ht_parms);
144         smp_mb();
145         wake_up_glock(gl);
146         call_rcu(&gl->gl_rcu, gfs2_glock_dealloc);
147         if (atomic_dec_and_test(&sdp->sd_glock_disposal))
148                 wake_up(&sdp->sd_glock_wait);
149 }
150 
151 /**
152  * gfs2_glock_hold() - increment reference count on glock
153  * @gl: The glock to hold
154  *
155  */
156 
157 void gfs2_glock_hold(struct gfs2_glock *gl)
158 {
159         GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
160         lockref_get(&gl->gl_lockref);
161 }
162 
163 /**
164  * demote_ok - Check to see if it's ok to unlock a glock
165  * @gl: the glock
166  *
167  * Returns: 1 if it's ok
168  */
169 
170 static int demote_ok(const struct gfs2_glock *gl)
171 {
172         const struct gfs2_glock_operations *glops = gl->gl_ops;
173 
174         if (gl->gl_state == LM_ST_UNLOCKED)
175                 return 0;
176         if (!list_empty(&gl->gl_holders))
177                 return 0;
178         if (glops->go_demote_ok)
179                 return glops->go_demote_ok(gl);
180         return 1;
181 }
182 
183 
184 void gfs2_glock_add_to_lru(struct gfs2_glock *gl)
185 {
186         spin_lock(&lru_lock);
187 
188         if (!list_empty(&gl->gl_lru))
189                 list_del_init(&gl->gl_lru);
190         else
191                 atomic_inc(&lru_count);
192 
193         list_add_tail(&gl->gl_lru, &lru_list);
194         set_bit(GLF_LRU, &gl->gl_flags);
195         spin_unlock(&lru_lock);
196 }
197 
198 static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
199 {
200         if (!(gl->gl_ops->go_flags & GLOF_LRU))
201                 return;
202 
203         spin_lock(&lru_lock);
204         if (!list_empty(&gl->gl_lru)) {
205                 list_del_init(&gl->gl_lru);
206                 atomic_dec(&lru_count);
207                 clear_bit(GLF_LRU, &gl->gl_flags);
208         }
209         spin_unlock(&lru_lock);
210 }
211 
212 /*
213  * Enqueue the glock on the work queue.  Passes one glock reference on to the
214  * work queue.
215  */
216 static void __gfs2_glock_queue_work(struct gfs2_glock *gl, unsigned long delay) {
217         if (!queue_delayed_work(glock_workqueue, &gl->gl_work, delay)) {
218                 /*
219                  * We are holding the lockref spinlock, and the work was still
220                  * queued above.  The queued work (glock_work_func) takes that
221                  * spinlock before dropping its glock reference(s), so it
222                  * cannot have dropped them in the meantime.
223                  */
224                 GLOCK_BUG_ON(gl, gl->gl_lockref.count < 2);
225                 gl->gl_lockref.count--;
226         }
227 }
228 
229 static void gfs2_glock_queue_work(struct gfs2_glock *gl, unsigned long delay) {
230         spin_lock(&gl->gl_lockref.lock);
231         __gfs2_glock_queue_work(gl, delay);
232         spin_unlock(&gl->gl_lockref.lock);
233 }
234 
235 static void __gfs2_glock_put(struct gfs2_glock *gl)
236 {
237         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
238         struct address_space *mapping = gfs2_glock2aspace(gl);
239 
240         lockref_mark_dead(&gl->gl_lockref);
241 
242         gfs2_glock_remove_from_lru(gl);
243         spin_unlock(&gl->gl_lockref.lock);
244         GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
245         GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
246         trace_gfs2_glock_put(gl);
247         sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
248 }
249 
250 /*
251  * Cause the glock to be put in work queue context.
252  */
253 void gfs2_glock_queue_put(struct gfs2_glock *gl)
254 {
255         gfs2_glock_queue_work(gl, 0);
256 }
257 
258 /**
259  * gfs2_glock_put() - Decrement reference count on glock
260  * @gl: The glock to put
261  *
262  */
263 
264 void gfs2_glock_put(struct gfs2_glock *gl)
265 {
266         if (lockref_put_or_lock(&gl->gl_lockref))
267                 return;
268 
269         __gfs2_glock_put(gl);
270 }
271 
272 /**
273  * may_grant - check if its ok to grant a new lock
274  * @gl: The glock
275  * @gh: The lock request which we wish to grant
276  *
277  * Returns: true if its ok to grant the lock
278  */
279 
280 static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
281 {
282         const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
283         if ((gh->gh_state == LM_ST_EXCLUSIVE ||
284              gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
285                 return 0;
286         if (gl->gl_state == gh->gh_state)
287                 return 1;
288         if (gh->gh_flags & GL_EXACT)
289                 return 0;
290         if (gl->gl_state == LM_ST_EXCLUSIVE) {
291                 if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
292                         return 1;
293                 if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
294                         return 1;
295         }
296         if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
297                 return 1;
298         return 0;
299 }
300 
301 static void gfs2_holder_wake(struct gfs2_holder *gh)
302 {
303         clear_bit(HIF_WAIT, &gh->gh_iflags);
304         smp_mb__after_atomic();
305         wake_up_bit(&gh->gh_iflags, HIF_WAIT);
306 }
307 
308 /**
309  * do_error - Something unexpected has happened during a lock request
310  *
311  */
312 
313 static void do_error(struct gfs2_glock *gl, const int ret)
314 {
315         struct gfs2_holder *gh, *tmp;
316 
317         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
318                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
319                         continue;
320                 if (ret & LM_OUT_ERROR)
321                         gh->gh_error = -EIO;
322                 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
323                         gh->gh_error = GLR_TRYFAILED;
324                 else
325                         continue;
326                 list_del_init(&gh->gh_list);
327                 trace_gfs2_glock_queue(gh, 0);
328                 gfs2_holder_wake(gh);
329         }
330 }
331 
332 /**
333  * do_promote - promote as many requests as possible on the current queue
334  * @gl: The glock
335  * 
336  * Returns: 1 if there is a blocked holder at the head of the list, or 2
337  *          if a type specific operation is underway.
338  */
339 
340 static int do_promote(struct gfs2_glock *gl)
341 __releases(&gl->gl_lockref.lock)
342 __acquires(&gl->gl_lockref.lock)
343 {
344         const struct gfs2_glock_operations *glops = gl->gl_ops;
345         struct gfs2_holder *gh, *tmp;
346         int ret;
347 
348 restart:
349         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
350                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
351                         continue;
352                 if (may_grant(gl, gh)) {
353                         if (gh->gh_list.prev == &gl->gl_holders &&
354                             glops->go_lock) {
355                                 spin_unlock(&gl->gl_lockref.lock);
356                                 /* FIXME: eliminate this eventually */
357                                 ret = glops->go_lock(gh);
358                                 spin_lock(&gl->gl_lockref.lock);
359                                 if (ret) {
360                                         if (ret == 1)
361                                                 return 2;
362                                         gh->gh_error = ret;
363                                         list_del_init(&gh->gh_list);
364                                         trace_gfs2_glock_queue(gh, 0);
365                                         gfs2_holder_wake(gh);
366                                         goto restart;
367                                 }
368                                 set_bit(HIF_HOLDER, &gh->gh_iflags);
369                                 trace_gfs2_promote(gh, 1);
370                                 gfs2_holder_wake(gh);
371                                 goto restart;
372                         }
373                         set_bit(HIF_HOLDER, &gh->gh_iflags);
374                         trace_gfs2_promote(gh, 0);
375                         gfs2_holder_wake(gh);
376                         continue;
377                 }
378                 if (gh->gh_list.prev == &gl->gl_holders)
379                         return 1;
380                 do_error(gl, 0);
381                 break;
382         }
383         return 0;
384 }
385 
386 /**
387  * find_first_waiter - find the first gh that's waiting for the glock
388  * @gl: the glock
389  */
390 
391 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
392 {
393         struct gfs2_holder *gh;
394 
395         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
396                 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
397                         return gh;
398         }
399         return NULL;
400 }
401 
402 /**
403  * state_change - record that the glock is now in a different state
404  * @gl: the glock
405  * @new_state the new state
406  *
407  */
408 
409 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
410 {
411         int held1, held2;
412 
413         held1 = (gl->gl_state != LM_ST_UNLOCKED);
414         held2 = (new_state != LM_ST_UNLOCKED);
415 
416         if (held1 != held2) {
417                 GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
418                 if (held2)
419                         gl->gl_lockref.count++;
420                 else
421                         gl->gl_lockref.count--;
422         }
423         if (held1 && held2 && list_empty(&gl->gl_holders))
424                 clear_bit(GLF_QUEUED, &gl->gl_flags);
425 
426         if (new_state != gl->gl_target)
427                 /* shorten our minimum hold time */
428                 gl->gl_hold_time = max(gl->gl_hold_time - GL_GLOCK_HOLD_DECR,
429                                        GL_GLOCK_MIN_HOLD);
430         gl->gl_state = new_state;
431         gl->gl_tchange = jiffies;
432 }
433 
434 static void gfs2_demote_wake(struct gfs2_glock *gl)
435 {
436         gl->gl_demote_state = LM_ST_EXCLUSIVE;
437         clear_bit(GLF_DEMOTE, &gl->gl_flags);
438         smp_mb__after_atomic();
439         wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
440 }
441 
442 /**
443  * finish_xmote - The DLM has replied to one of our lock requests
444  * @gl: The glock
445  * @ret: The status from the DLM
446  *
447  */
448 
449 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
450 {
451         const struct gfs2_glock_operations *glops = gl->gl_ops;
452         struct gfs2_holder *gh;
453         unsigned state = ret & LM_OUT_ST_MASK;
454         int rv;
455 
456         spin_lock(&gl->gl_lockref.lock);
457         trace_gfs2_glock_state_change(gl, state);
458         state_change(gl, state);
459         gh = find_first_waiter(gl);
460 
461         /* Demote to UN request arrived during demote to SH or DF */
462         if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
463             state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
464                 gl->gl_target = LM_ST_UNLOCKED;
465 
466         /* Check for state != intended state */
467         if (unlikely(state != gl->gl_target)) {
468                 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
469                         /* move to back of queue and try next entry */
470                         if (ret & LM_OUT_CANCELED) {
471                                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
472                                         list_move_tail(&gh->gh_list, &gl->gl_holders);
473                                 gh = find_first_waiter(gl);
474                                 gl->gl_target = gh->gh_state;
475                                 goto retry;
476                         }
477                         /* Some error or failed "try lock" - report it */
478                         if ((ret & LM_OUT_ERROR) ||
479                             (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
480                                 gl->gl_target = gl->gl_state;
481                                 do_error(gl, ret);
482                                 goto out;
483                         }
484                 }
485                 switch(state) {
486                 /* Unlocked due to conversion deadlock, try again */
487                 case LM_ST_UNLOCKED:
488 retry:
489                         do_xmote(gl, gh, gl->gl_target);
490                         break;
491                 /* Conversion fails, unlock and try again */
492                 case LM_ST_SHARED:
493                 case LM_ST_DEFERRED:
494                         do_xmote(gl, gh, LM_ST_UNLOCKED);
495                         break;
496                 default: /* Everything else */
497                         pr_err("wanted %u got %u\n", gl->gl_target, state);
498                         GLOCK_BUG_ON(gl, 1);
499                 }
500                 spin_unlock(&gl->gl_lockref.lock);
501                 return;
502         }
503 
504         /* Fast path - we got what we asked for */
505         if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
506                 gfs2_demote_wake(gl);
507         if (state != LM_ST_UNLOCKED) {
508                 if (glops->go_xmote_bh) {
509                         spin_unlock(&gl->gl_lockref.lock);
510                         rv = glops->go_xmote_bh(gl, gh);
511                         spin_lock(&gl->gl_lockref.lock);
512                         if (rv) {
513                                 do_error(gl, rv);
514                                 goto out;
515                         }
516                 }
517                 rv = do_promote(gl);
518                 if (rv == 2)
519                         goto out_locked;
520         }
521 out:
522         clear_bit(GLF_LOCK, &gl->gl_flags);
523 out_locked:
524         spin_unlock(&gl->gl_lockref.lock);
525 }
526 
527 /**
528  * do_xmote - Calls the DLM to change the state of a lock
529  * @gl: The lock state
530  * @gh: The holder (only for promotes)
531  * @target: The target lock state
532  *
533  */
534 
535 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
536 __releases(&gl->gl_lockref.lock)
537 __acquires(&gl->gl_lockref.lock)
538 {
539         const struct gfs2_glock_operations *glops = gl->gl_ops;
540         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
541         unsigned int lck_flags = (unsigned int)(gh ? gh->gh_flags : 0);
542         int ret;
543 
544         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)) &&
545             target != LM_ST_UNLOCKED)
546                 return;
547         lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
548                       LM_FLAG_PRIORITY);
549         GLOCK_BUG_ON(gl, gl->gl_state == target);
550         GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
551         if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
552             glops->go_inval) {
553                 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
554                 do_error(gl, 0); /* Fail queued try locks */
555         }
556         gl->gl_req = target;
557         set_bit(GLF_BLOCKING, &gl->gl_flags);
558         if ((gl->gl_req == LM_ST_UNLOCKED) ||
559             (gl->gl_state == LM_ST_EXCLUSIVE) ||
560             (lck_flags & (LM_FLAG_TRY|LM_FLAG_TRY_1CB)))
561                 clear_bit(GLF_BLOCKING, &gl->gl_flags);
562         spin_unlock(&gl->gl_lockref.lock);
563         if (glops->go_sync)
564                 glops->go_sync(gl);
565         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
566                 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
567         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
568 
569         gfs2_glock_hold(gl);
570         if (sdp->sd_lockstruct.ls_ops->lm_lock) {
571                 /* lock_dlm */
572                 ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
573                 if (ret == -EINVAL && gl->gl_target == LM_ST_UNLOCKED &&
574                     target == LM_ST_UNLOCKED &&
575                     test_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags)) {
576                         finish_xmote(gl, target);
577                         gfs2_glock_queue_work(gl, 0);
578                 }
579                 else if (ret) {
580                         pr_err("lm_lock ret %d\n", ret);
581                         GLOCK_BUG_ON(gl, !test_bit(SDF_SHUTDOWN,
582                                                    &sdp->sd_flags));
583                 }
584         } else { /* lock_nolock */
585                 finish_xmote(gl, target);
586                 gfs2_glock_queue_work(gl, 0);
587         }
588 
589         spin_lock(&gl->gl_lockref.lock);
590 }
591 
592 /**
593  * find_first_holder - find the first "holder" gh
594  * @gl: the glock
595  */
596 
597 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
598 {
599         struct gfs2_holder *gh;
600 
601         if (!list_empty(&gl->gl_holders)) {
602                 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
603                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
604                         return gh;
605         }
606         return NULL;
607 }
608 
609 /**
610  * run_queue - do all outstanding tasks related to a glock
611  * @gl: The glock in question
612  * @nonblock: True if we must not block in run_queue
613  *
614  */
615 
616 static void run_queue(struct gfs2_glock *gl, const int nonblock)
617 __releases(&gl->gl_lockref.lock)
618 __acquires(&gl->gl_lockref.lock)
619 {
620         struct gfs2_holder *gh = NULL;
621         int ret;
622 
623         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
624                 return;
625 
626         GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
627 
628         if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
629             gl->gl_demote_state != gl->gl_state) {
630                 if (find_first_holder(gl))
631                         goto out_unlock;
632                 if (nonblock)
633                         goto out_sched;
634                 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
635                 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
636                 gl->gl_target = gl->gl_demote_state;
637         } else {
638                 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
639                         gfs2_demote_wake(gl);
640                 ret = do_promote(gl);
641                 if (ret == 0)
642                         goto out_unlock;
643                 if (ret == 2)
644                         goto out;
645                 gh = find_first_waiter(gl);
646                 gl->gl_target = gh->gh_state;
647                 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
648                         do_error(gl, 0); /* Fail queued try locks */
649         }
650         do_xmote(gl, gh, gl->gl_target);
651 out:
652         return;
653 
654 out_sched:
655         clear_bit(GLF_LOCK, &gl->gl_flags);
656         smp_mb__after_atomic();
657         gl->gl_lockref.count++;
658         __gfs2_glock_queue_work(gl, 0);
659         return;
660 
661 out_unlock:
662         clear_bit(GLF_LOCK, &gl->gl_flags);
663         smp_mb__after_atomic();
664         return;
665 }
666 
667 static void delete_work_func(struct work_struct *work)
668 {
669         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
670         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
671         struct inode *inode;
672         u64 no_addr = gl->gl_name.ln_number;
673 
674         /* If someone's using this glock to create a new dinode, the block must
675            have been freed by another node, then re-used, in which case our
676            iopen callback is too late after the fact. Ignore it. */
677         if (test_bit(GLF_INODE_CREATING, &gl->gl_flags))
678                 goto out;
679 
680         inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
681         if (inode && !IS_ERR(inode)) {
682                 d_prune_aliases(inode);
683                 iput(inode);
684         }
685 out:
686         gfs2_glock_put(gl);
687 }
688 
689 static void glock_work_func(struct work_struct *work)
690 {
691         unsigned long delay = 0;
692         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
693         unsigned int drop_refs = 1;
694 
695         if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
696                 finish_xmote(gl, gl->gl_reply);
697                 drop_refs++;
698         }
699         spin_lock(&gl->gl_lockref.lock);
700         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
701             gl->gl_state != LM_ST_UNLOCKED &&
702             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
703                 unsigned long holdtime, now = jiffies;
704 
705                 holdtime = gl->gl_tchange + gl->gl_hold_time;
706                 if (time_before(now, holdtime))
707                         delay = holdtime - now;
708 
709                 if (!delay) {
710                         clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
711                         set_bit(GLF_DEMOTE, &gl->gl_flags);
712                 }
713         }
714         run_queue(gl, 0);
715         if (delay) {
716                 /* Keep one glock reference for the work we requeue. */
717                 drop_refs--;
718                 if (gl->gl_name.ln_type != LM_TYPE_INODE)
719                         delay = 0;
720                 __gfs2_glock_queue_work(gl, delay);
721         }
722 
723         /*
724          * Drop the remaining glock references manually here. (Mind that
725          * __gfs2_glock_queue_work depends on the lockref spinlock begin held
726          * here as well.)
727          */
728         gl->gl_lockref.count -= drop_refs;
729         if (!gl->gl_lockref.count) {
730                 __gfs2_glock_put(gl);
731                 return;
732         }
733         spin_unlock(&gl->gl_lockref.lock);
734 }
735 
736 static struct gfs2_glock *find_insert_glock(struct lm_lockname *name,
737                                             struct gfs2_glock *new)
738 {
739         struct wait_glock_queue wait;
740         wait_queue_head_t *wq = glock_waitqueue(name);
741         struct gfs2_glock *gl;
742 
743         wait.name = name;
744         init_wait(&wait.wait);
745         wait.wait.func = glock_wake_function;
746 
747 again:
748         prepare_to_wait(wq, &wait.wait, TASK_UNINTERRUPTIBLE);
749         rcu_read_lock();
750         if (new) {
751                 gl = rhashtable_lookup_get_insert_fast(&gl_hash_table,
752                         &new->gl_node, ht_parms);
753                 if (IS_ERR(gl))
754                         goto out;
755         } else {
756                 gl = rhashtable_lookup_fast(&gl_hash_table,
757                         name, ht_parms);
758         }
759         if (gl && !lockref_get_not_dead(&gl->gl_lockref)) {
760                 rcu_read_unlock();
761                 schedule();
762                 goto again;
763         }
764 out:
765         rcu_read_unlock();
766         finish_wait(wq, &wait.wait);
767         return gl;
768 }
769 
770 /**
771  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
772  * @sdp: The GFS2 superblock
773  * @number: the lock number
774  * @glops: The glock_operations to use
775  * @create: If 0, don't create the glock if it doesn't exist
776  * @glp: the glock is returned here
777  *
778  * This does not lock a glock, just finds/creates structures for one.
779  *
780  * Returns: errno
781  */
782 
783 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
784                    const struct gfs2_glock_operations *glops, int create,
785                    struct gfs2_glock **glp)
786 {
787         struct super_block *s = sdp->sd_vfs;
788         struct lm_lockname name = { .ln_number = number,
789                                     .ln_type = glops->go_type,
790                                     .ln_sbd = sdp };
791         struct gfs2_glock *gl, *tmp;
792         struct address_space *mapping;
793         struct kmem_cache *cachep;
794         int ret = 0;
795 
796         gl = find_insert_glock(&name, NULL);
797         if (gl) {
798                 *glp = gl;
799                 return 0;
800         }
801         if (!create)
802                 return -ENOENT;
803 
804         if (glops->go_flags & GLOF_ASPACE)
805                 cachep = gfs2_glock_aspace_cachep;
806         else
807                 cachep = gfs2_glock_cachep;
808         gl = kmem_cache_alloc(cachep, GFP_NOFS);
809         if (!gl)
810                 return -ENOMEM;
811 
812         memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
813 
814         if (glops->go_flags & GLOF_LVB) {
815                 gl->gl_lksb.sb_lvbptr = kzalloc(GFS2_MIN_LVB_SIZE, GFP_NOFS);
816                 if (!gl->gl_lksb.sb_lvbptr) {
817                         kmem_cache_free(cachep, gl);
818                         return -ENOMEM;
819                 }
820         }
821 
822         atomic_inc(&sdp->sd_glock_disposal);
823         gl->gl_node.next = NULL;
824         gl->gl_flags = 0;
825         gl->gl_name = name;
826         gl->gl_lockref.count = 1;
827         gl->gl_state = LM_ST_UNLOCKED;
828         gl->gl_target = LM_ST_UNLOCKED;
829         gl->gl_demote_state = LM_ST_EXCLUSIVE;
830         gl->gl_ops = glops;
831         gl->gl_dstamp = 0;
832         preempt_disable();
833         /* We use the global stats to estimate the initial per-glock stats */
834         gl->gl_stats = this_cpu_ptr(sdp->sd_lkstats)->lkstats[glops->go_type];
835         preempt_enable();
836         gl->gl_stats.stats[GFS2_LKS_DCOUNT] = 0;
837         gl->gl_stats.stats[GFS2_LKS_QCOUNT] = 0;
838         gl->gl_tchange = jiffies;
839         gl->gl_object = NULL;
840         gl->gl_hold_time = GL_GLOCK_DFT_HOLD;
841         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
842         INIT_WORK(&gl->gl_delete, delete_work_func);
843 
844         mapping = gfs2_glock2aspace(gl);
845         if (mapping) {
846                 mapping->a_ops = &gfs2_meta_aops;
847                 mapping->host = s->s_bdev->bd_inode;
848                 mapping->flags = 0;
849                 mapping_set_gfp_mask(mapping, GFP_NOFS);
850                 mapping->private_data = NULL;
851                 mapping->writeback_index = 0;
852         }
853 
854         tmp = find_insert_glock(&name, gl);
855         if (!tmp) {
856                 *glp = gl;
857                 goto out;
858         }
859         if (IS_ERR(tmp)) {
860                 ret = PTR_ERR(tmp);
861                 goto out_free;
862         }
863         *glp = tmp;
864 
865 out_free:
866         kfree(gl->gl_lksb.sb_lvbptr);
867         kmem_cache_free(cachep, gl);
868         atomic_dec(&sdp->sd_glock_disposal);
869 
870 out:
871         return ret;
872 }
873 
874 /**
875  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
876  * @gl: the glock
877  * @state: the state we're requesting
878  * @flags: the modifier flags
879  * @gh: the holder structure
880  *
881  */
882 
883 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, u16 flags,
884                       struct gfs2_holder *gh)
885 {
886         INIT_LIST_HEAD(&gh->gh_list);
887         gh->gh_gl = gl;
888         gh->gh_ip = _RET_IP_;
889         gh->gh_owner_pid = get_pid(task_pid(current));
890         gh->gh_state = state;
891         gh->gh_flags = flags;
892         gh->gh_error = 0;
893         gh->gh_iflags = 0;
894         gfs2_glock_hold(gl);
895 }
896 
897 /**
898  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
899  * @state: the state we're requesting
900  * @flags: the modifier flags
901  * @gh: the holder structure
902  *
903  * Don't mess with the glock.
904  *
905  */
906 
907 void gfs2_holder_reinit(unsigned int state, u16 flags, struct gfs2_holder *gh)
908 {
909         gh->gh_state = state;
910         gh->gh_flags = flags;
911         gh->gh_iflags = 0;
912         gh->gh_ip = _RET_IP_;
913         put_pid(gh->gh_owner_pid);
914         gh->gh_owner_pid = get_pid(task_pid(current));
915 }
916 
917 /**
918  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
919  * @gh: the holder structure
920  *
921  */
922 
923 void gfs2_holder_uninit(struct gfs2_holder *gh)
924 {
925         put_pid(gh->gh_owner_pid);
926         gfs2_glock_put(gh->gh_gl);
927         gfs2_holder_mark_uninitialized(gh);
928         gh->gh_ip = 0;
929 }
930 
931 /**
932  * gfs2_glock_wait - wait on a glock acquisition
933  * @gh: the glock holder
934  *
935  * Returns: 0 on success
936  */
937 
938 int gfs2_glock_wait(struct gfs2_holder *gh)
939 {
940         unsigned long time1 = jiffies;
941 
942         might_sleep();
943         wait_on_bit(&gh->gh_iflags, HIF_WAIT, TASK_UNINTERRUPTIBLE);
944         if (time_after(jiffies, time1 + HZ)) /* have we waited > a second? */
945                 /* Lengthen the minimum hold time. */
946                 gh->gh_gl->gl_hold_time = min(gh->gh_gl->gl_hold_time +
947                                               GL_GLOCK_HOLD_INCR,
948                                               GL_GLOCK_MAX_HOLD);
949         return gh->gh_error;
950 }
951 
952 /**
953  * handle_callback - process a demote request
954  * @gl: the glock
955  * @state: the state the caller wants us to change to
956  *
957  * There are only two requests that we are going to see in actual
958  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
959  */
960 
961 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
962                             unsigned long delay, bool remote)
963 {
964         int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
965 
966         set_bit(bit, &gl->gl_flags);
967         if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
968                 gl->gl_demote_state = state;
969                 gl->gl_demote_time = jiffies;
970         } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
971                         gl->gl_demote_state != state) {
972                 gl->gl_demote_state = LM_ST_UNLOCKED;
973         }
974         if (gl->gl_ops->go_callback)
975                 gl->gl_ops->go_callback(gl, remote);
976         trace_gfs2_demote_rq(gl, remote);
977 }
978 
979 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
980 {
981         struct va_format vaf;
982         va_list args;
983 
984         va_start(args, fmt);
985 
986         if (seq) {
987                 seq_vprintf(seq, fmt, args);
988         } else {
989                 vaf.fmt = fmt;
990                 vaf.va = &args;
991 
992                 pr_err("%pV", &vaf);
993         }
994 
995         va_end(args);
996 }
997 
998 /**
999  * add_to_queue - Add a holder to the wait queue (but look for recursion)
1000  * @gh: the holder structure to add
1001  *
1002  * Eventually we should move the recursive locking trap to a
1003  * debugging option or something like that. This is the fast
1004  * path and needs to have the minimum number of distractions.
1005  * 
1006  */
1007 
1008 static inline void add_to_queue(struct gfs2_holder *gh)
1009 __releases(&gl->gl_lockref.lock)
1010 __acquires(&gl->gl_lockref.lock)
1011 {
1012         struct gfs2_glock *gl = gh->gh_gl;
1013         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
1014         struct list_head *insert_pt = NULL;
1015         struct gfs2_holder *gh2;
1016         int try_futile = 0;
1017 
1018         BUG_ON(gh->gh_owner_pid == NULL);
1019         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
1020                 BUG();
1021 
1022         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
1023                 if (test_bit(GLF_LOCK, &gl->gl_flags))
1024                         try_futile = !may_grant(gl, gh);
1025                 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
1026                         goto fail;
1027         }
1028 
1029         list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
1030                 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
1031                     (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
1032                         goto trap_recursive;
1033                 if (try_futile &&
1034                     !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
1035 fail:
1036                         gh->gh_error = GLR_TRYFAILED;
1037                         gfs2_holder_wake(gh);
1038                         return;
1039                 }
1040                 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
1041                         continue;
1042                 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
1043                         insert_pt = &gh2->gh_list;
1044         }
1045         set_bit(GLF_QUEUED, &gl->gl_flags);
1046         trace_gfs2_glock_queue(gh, 1);
1047         gfs2_glstats_inc(gl, GFS2_LKS_QCOUNT);
1048         gfs2_sbstats_inc(gl, GFS2_LKS_QCOUNT);
1049         if (likely(insert_pt == NULL)) {
1050                 list_add_tail(&gh->gh_list, &gl->gl_holders);
1051                 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
1052                         goto do_cancel;
1053                 return;
1054         }
1055         list_add_tail(&gh->gh_list, insert_pt);
1056 do_cancel:
1057         gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
1058         if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
1059                 spin_unlock(&gl->gl_lockref.lock);
1060                 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
1061                         sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
1062                 spin_lock(&gl->gl_lockref.lock);
1063         }
1064         return;
1065 
1066 trap_recursive:
1067         pr_err("original: %pSR\n", (void *)gh2->gh_ip);
1068         pr_err("pid: %d\n", pid_nr(gh2->gh_owner_pid));
1069         pr_err("lock type: %d req lock state : %d\n",
1070                gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
1071         pr_err("new: %pSR\n", (void *)gh->gh_ip);
1072         pr_err("pid: %d\n", pid_nr(gh->gh_owner_pid));
1073         pr_err("lock type: %d req lock state : %d\n",
1074                gh->gh_gl->gl_name.ln_type, gh->gh_state);
1075         gfs2_dump_glock(NULL, gl);
1076         BUG();
1077 }
1078 
1079 /**
1080  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1081  * @gh: the holder structure
1082  *
1083  * if (gh->gh_flags & GL_ASYNC), this never returns an error
1084  *
1085  * Returns: 0, GLR_TRYFAILED, or errno on failure
1086  */
1087 
1088 int gfs2_glock_nq(struct gfs2_holder *gh)
1089 {
1090         struct gfs2_glock *gl = gh->gh_gl;
1091         struct gfs2_sbd *sdp = gl->gl_name.ln_sbd;
1092         int error = 0;
1093 
1094         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
1095                 return -EIO;
1096 
1097         if (test_bit(GLF_LRU, &gl->gl_flags))
1098                 gfs2_glock_remove_from_lru(gl);
1099 
1100         spin_lock(&gl->gl_lockref.lock);
1101         add_to_queue(gh);
1102         if (unlikely((LM_FLAG_NOEXP & gh->gh_flags) &&
1103                      test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))) {
1104                 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1105                 gl->gl_lockref.count++;
1106                 __gfs2_glock_queue_work(gl, 0);
1107         }
1108         run_queue(gl, 1);
1109         spin_unlock(&gl->gl_lockref.lock);
1110 
1111         if (!(gh->gh_flags & GL_ASYNC))
1112                 error = gfs2_glock_wait(gh);
1113 
1114         return error;
1115 }
1116 
1117 /**
1118  * gfs2_glock_poll - poll to see if an async request has been completed
1119  * @gh: the holder
1120  *
1121  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1122  */
1123 
1124 int gfs2_glock_poll(struct gfs2_holder *gh)
1125 {
1126         return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1127 }
1128 
1129 /**
1130  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1131  * @gh: the glock holder
1132  *
1133  */
1134 
1135 void gfs2_glock_dq(struct gfs2_holder *gh)
1136 {
1137         struct gfs2_glock *gl = gh->gh_gl;
1138         const struct gfs2_glock_operations *glops = gl->gl_ops;
1139         unsigned delay = 0;
1140         int fast_path = 0;
1141 
1142         spin_lock(&gl->gl_lockref.lock);
1143         if (gh->gh_flags & GL_NOCACHE)
1144                 handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1145 
1146         list_del_init(&gh->gh_list);
1147         clear_bit(HIF_HOLDER, &gh->gh_iflags);
1148         if (find_first_holder(gl) == NULL) {
1149                 if (glops->go_unlock) {
1150                         GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1151                         spin_unlock(&gl->gl_lockref.lock);
1152                         glops->go_unlock(gh);
1153                         spin_lock(&gl->gl_lockref.lock);
1154                         clear_bit(GLF_LOCK, &gl->gl_flags);
1155                 }
1156                 if (list_empty(&gl->gl_holders) &&
1157                     !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1158                     !test_bit(GLF_DEMOTE, &gl->gl_flags))
1159                         fast_path = 1;
1160         }
1161         if (!test_bit(GLF_LFLUSH, &gl->gl_flags) && demote_ok(gl) &&
1162             (glops->go_flags & GLOF_LRU))
1163                 gfs2_glock_add_to_lru(gl);
1164 
1165         trace_gfs2_glock_queue(gh, 0);
1166         if (unlikely(!fast_path)) {
1167                 gl->gl_lockref.count++;
1168                 if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1169                     !test_bit(GLF_DEMOTE, &gl->gl_flags) &&
1170                     gl->gl_name.ln_type == LM_TYPE_INODE)
1171                         delay = gl->gl_hold_time;
1172                 __gfs2_glock_queue_work(gl, delay);
1173         }
1174         spin_unlock(&gl->gl_lockref.lock);
1175 }
1176 
1177 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1178 {
1179         struct gfs2_glock *gl = gh->gh_gl;
1180         gfs2_glock_dq(gh);
1181         might_sleep();
1182         wait_on_bit(&gl->gl_flags, GLF_DEMOTE, TASK_UNINTERRUPTIBLE);
1183 }
1184 
1185 /**
1186  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1187  * @gh: the holder structure
1188  *
1189  */
1190 
1191 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1192 {
1193         gfs2_glock_dq(gh);
1194         gfs2_holder_uninit(gh);
1195 }
1196 
1197 /**
1198  * gfs2_glock_nq_num - acquire a glock based on lock number
1199  * @sdp: the filesystem
1200  * @number: the lock number
1201  * @glops: the glock operations for the type of glock
1202  * @state: the state to acquire the glock in
1203  * @flags: modifier flags for the acquisition
1204  * @gh: the struct gfs2_holder
1205  *
1206  * Returns: errno
1207  */
1208 
1209 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1210                       const struct gfs2_glock_operations *glops,
1211                       unsigned int state, u16 flags, struct gfs2_holder *gh)
1212 {
1213         struct gfs2_glock *gl;
1214         int error;
1215 
1216         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1217         if (!error) {
1218                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1219                 gfs2_glock_put(gl);
1220         }
1221 
1222         return error;
1223 }
1224 
1225 /**
1226  * glock_compare - Compare two struct gfs2_glock structures for sorting
1227  * @arg_a: the first structure
1228  * @arg_b: the second structure
1229  *
1230  */
1231 
1232 static int glock_compare(const void *arg_a, const void *arg_b)
1233 {
1234         const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1235         const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1236         const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1237         const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1238 
1239         if (a->ln_number > b->ln_number)
1240                 return 1;
1241         if (a->ln_number < b->ln_number)
1242                 return -1;
1243         BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1244         return 0;
1245 }
1246 
1247 /**
1248  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1249  * @num_gh: the number of structures
1250  * @ghs: an array of struct gfs2_holder structures
1251  *
1252  * Returns: 0 on success (all glocks acquired),
1253  *          errno on failure (no glocks acquired)
1254  */
1255 
1256 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1257                      struct gfs2_holder **p)
1258 {
1259         unsigned int x;
1260         int error = 0;
1261 
1262         for (x = 0; x < num_gh; x++)
1263                 p[x] = &ghs[x];
1264 
1265         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1266 
1267         for (x = 0; x < num_gh; x++) {
1268                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1269 
1270                 error = gfs2_glock_nq(p[x]);
1271                 if (error) {
1272                         while (x--)
1273                                 gfs2_glock_dq(p[x]);
1274                         break;
1275                 }
1276         }
1277 
1278         return error;
1279 }
1280 
1281 /**
1282  * gfs2_glock_nq_m - acquire multiple glocks
1283  * @num_gh: the number of structures
1284  * @ghs: an array of struct gfs2_holder structures
1285  *
1286  *
1287  * Returns: 0 on success (all glocks acquired),
1288  *          errno on failure (no glocks acquired)
1289  */
1290 
1291 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1292 {
1293         struct gfs2_holder *tmp[4];
1294         struct gfs2_holder **pph = tmp;
1295         int error = 0;
1296 
1297         switch(num_gh) {
1298         case 0:
1299                 return 0;
1300         case 1:
1301                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1302                 return gfs2_glock_nq(ghs);
1303         default:
1304                 if (num_gh <= 4)
1305                         break;
1306                 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1307                 if (!pph)
1308                         return -ENOMEM;
1309         }
1310 
1311         error = nq_m_sync(num_gh, ghs, pph);
1312 
1313         if (pph != tmp)
1314                 kfree(pph);
1315 
1316         return error;
1317 }
1318 
1319 /**
1320  * gfs2_glock_dq_m - release multiple glocks
1321  * @num_gh: the number of structures
1322  * @ghs: an array of struct gfs2_holder structures
1323  *
1324  */
1325 
1326 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1327 {
1328         while (num_gh--)
1329                 gfs2_glock_dq(&ghs[num_gh]);
1330 }
1331 
1332 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1333 {
1334         unsigned long delay = 0;
1335         unsigned long holdtime;
1336         unsigned long now = jiffies;
1337 
1338         gfs2_glock_hold(gl);
1339         holdtime = gl->gl_tchange + gl->gl_hold_time;
1340         if (test_bit(GLF_QUEUED, &gl->gl_flags) &&
1341             gl->gl_name.ln_type == LM_TYPE_INODE) {
1342                 if (time_before(now, holdtime))
1343                         delay = holdtime - now;
1344                 if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1345                         delay = gl->gl_hold_time;
1346         }
1347 
1348         spin_lock(&gl->gl_lockref.lock);
1349         handle_callback(gl, state, delay, true);
1350         __gfs2_glock_queue_work(gl, delay);
1351         spin_unlock(&gl->gl_lockref.lock);
1352 }
1353 
1354 /**
1355  * gfs2_should_freeze - Figure out if glock should be frozen
1356  * @gl: The glock in question
1357  *
1358  * Glocks are not frozen if (a) the result of the dlm operation is
1359  * an error, (b) the locking operation was an unlock operation or
1360  * (c) if there is a "noexp" flagged request anywhere in the queue
1361  *
1362  * Returns: 1 if freezing should occur, 0 otherwise
1363  */
1364 
1365 static int gfs2_should_freeze(const struct gfs2_glock *gl)
1366 {
1367         const struct gfs2_holder *gh;
1368 
1369         if (gl->gl_reply & ~LM_OUT_ST_MASK)
1370                 return 0;
1371         if (gl->gl_target == LM_ST_UNLOCKED)
1372                 return 0;
1373 
1374         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1375                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1376                         continue;
1377                 if (LM_FLAG_NOEXP & gh->gh_flags)
1378                         return 0;
1379         }
1380 
1381         return 1;
1382 }
1383 
1384 /**
1385  * gfs2_glock_complete - Callback used by locking
1386  * @gl: Pointer to the glock
1387  * @ret: The return value from the dlm
1388  *
1389  * The gl_reply field is under the gl_lockref.lock lock so that it is ok
1390  * to use a bitfield shared with other glock state fields.
1391  */
1392 
1393 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1394 {
1395         struct lm_lockstruct *ls = &gl->gl_name.ln_sbd->sd_lockstruct;
1396 
1397         spin_lock(&gl->gl_lockref.lock);
1398         gl->gl_reply = ret;
1399 
1400         if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags))) {
1401                 if (gfs2_should_freeze(gl)) {
1402                         set_bit(GLF_FROZEN, &gl->gl_flags);
1403                         spin_unlock(&gl->gl_lockref.lock);
1404                         return;
1405                 }
1406         }
1407 
1408         gl->gl_lockref.count++;
1409         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1410         __gfs2_glock_queue_work(gl, 0);
1411         spin_unlock(&gl->gl_lockref.lock);
1412 }
1413 
1414 static int glock_cmp(void *priv, struct list_head *a, struct list_head *b)
1415 {
1416         struct gfs2_glock *gla, *glb;
1417 
1418         gla = list_entry(a, struct gfs2_glock, gl_lru);
1419         glb = list_entry(b, struct gfs2_glock, gl_lru);
1420 
1421         if (gla->gl_name.ln_number > glb->gl_name.ln_number)
1422                 return 1;
1423         if (gla->gl_name.ln_number < glb->gl_name.ln_number)
1424                 return -1;
1425 
1426         return 0;
1427 }
1428 
1429 /**
1430  * gfs2_dispose_glock_lru - Demote a list of glocks
1431  * @list: The list to dispose of
1432  *
1433  * Disposing of glocks may involve disk accesses, so that here we sort
1434  * the glocks by number (i.e. disk location of the inodes) so that if
1435  * there are any such accesses, they'll be sent in order (mostly).
1436  *
1437  * Must be called under the lru_lock, but may drop and retake this
1438  * lock. While the lru_lock is dropped, entries may vanish from the
1439  * list, but no new entries will appear on the list (since it is
1440  * private)
1441  */
1442 
1443 static void gfs2_dispose_glock_lru(struct list_head *list)
1444 __releases(&lru_lock)
1445 __acquires(&lru_lock)
1446 {
1447         struct gfs2_glock *gl;
1448 
1449         list_sort(NULL, list, glock_cmp);
1450 
1451         while(!list_empty(list)) {
1452                 gl = list_entry(list->next, struct gfs2_glock, gl_lru);
1453                 list_del_init(&gl->gl_lru);
1454                 if (!spin_trylock(&gl->gl_lockref.lock)) {
1455 add_back_to_lru:
1456                         list_add(&gl->gl_lru, &lru_list);
1457                         atomic_inc(&lru_count);
1458                         continue;
1459                 }
1460                 if (test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1461                         spin_unlock(&gl->gl_lockref.lock);
1462                         goto add_back_to_lru;
1463                 }
1464                 clear_bit(GLF_LRU, &gl->gl_flags);
1465                 gl->gl_lockref.count++;
1466                 if (demote_ok(gl))
1467                         handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1468                 WARN_ON(!test_and_clear_bit(GLF_LOCK, &gl->gl_flags));
1469                 __gfs2_glock_queue_work(gl, 0);
1470                 spin_unlock(&gl->gl_lockref.lock);
1471                 cond_resched_lock(&lru_lock);
1472         }
1473 }
1474 
1475 /**
1476  * gfs2_scan_glock_lru - Scan the LRU looking for locks to demote
1477  * @nr: The number of entries to scan
1478  *
1479  * This function selects the entries on the LRU which are able to
1480  * be demoted, and then kicks off the process by calling
1481  * gfs2_dispose_glock_lru() above.
1482  */
1483 
1484 static long gfs2_scan_glock_lru(int nr)
1485 {
1486         struct gfs2_glock *gl;
1487         LIST_HEAD(skipped);
1488         LIST_HEAD(dispose);
1489         long freed = 0;
1490 
1491         spin_lock(&lru_lock);
1492         while ((nr-- >= 0) && !list_empty(&lru_list)) {
1493                 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1494 
1495                 /* Test for being demotable */
1496                 if (!test_bit(GLF_LOCK, &gl->gl_flags)) {
1497                         list_move(&gl->gl_lru, &dispose);
1498                         atomic_dec(&lru_count);
1499                         freed++;
1500                         continue;
1501                 }
1502 
1503                 list_move(&gl->gl_lru, &skipped);
1504         }
1505         list_splice(&skipped, &lru_list);
1506         if (!list_empty(&dispose))
1507                 gfs2_dispose_glock_lru(&dispose);
1508         spin_unlock(&lru_lock);
1509 
1510         return freed;
1511 }
1512 
1513 static unsigned long gfs2_glock_shrink_scan(struct shrinker *shrink,
1514                                             struct shrink_control *sc)
1515 {
1516         if (!(sc->gfp_mask & __GFP_FS))
1517                 return SHRINK_STOP;
1518         return gfs2_scan_glock_lru(sc->nr_to_scan);
1519 }
1520 
1521 static unsigned long gfs2_glock_shrink_count(struct shrinker *shrink,
1522                                              struct shrink_control *sc)
1523 {
1524         return vfs_pressure_ratio(atomic_read(&lru_count));
1525 }
1526 
1527 static struct shrinker glock_shrinker = {
1528         .seeks = DEFAULT_SEEKS,
1529         .count_objects = gfs2_glock_shrink_count,
1530         .scan_objects = gfs2_glock_shrink_scan,
1531 };
1532 
1533 /**
1534  * examine_bucket - Call a function for glock in a hash bucket
1535  * @examiner: the function
1536  * @sdp: the filesystem
1537  * @bucket: the bucket
1538  *
1539  * Note that the function can be called multiple times on the same
1540  * object.  So the user must ensure that the function can cope with
1541  * that.
1542  */
1543 
1544 static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
1545 {
1546         struct gfs2_glock *gl;
1547         struct rhashtable_iter iter;
1548 
1549         rhashtable_walk_enter(&gl_hash_table, &iter);
1550 
1551         do {
1552                 gl = ERR_PTR(rhashtable_walk_start(&iter));
1553                 if (IS_ERR(gl))
1554                         goto walk_stop;
1555 
1556                 while ((gl = rhashtable_walk_next(&iter)) && !IS_ERR(gl))
1557                         if (gl->gl_name.ln_sbd == sdp &&
1558                             lockref_get_not_dead(&gl->gl_lockref))
1559                                 examiner(gl);
1560 
1561 walk_stop:
1562                 rhashtable_walk_stop(&iter);
1563         } while (cond_resched(), gl == ERR_PTR(-EAGAIN));
1564 
1565         rhashtable_walk_exit(&iter);
1566 }
1567 
1568 /**
1569  * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1570  * @gl: The glock to thaw
1571  *
1572  */
1573 
1574 static void thaw_glock(struct gfs2_glock *gl)
1575 {
1576         if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags)) {
1577                 gfs2_glock_put(gl);
1578                 return;
1579         }
1580         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1581         gfs2_glock_queue_work(gl, 0);
1582 }
1583 
1584 /**
1585  * clear_glock - look at a glock and see if we can free it from glock cache
1586  * @gl: the glock to look at
1587  *
1588  */
1589 
1590 static void clear_glock(struct gfs2_glock *gl)
1591 {
1592         gfs2_glock_remove_from_lru(gl);
1593 
1594         spin_lock(&gl->gl_lockref.lock);
1595         if (gl->gl_state != LM_ST_UNLOCKED)
1596                 handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1597         __gfs2_glock_queue_work(gl, 0);
1598         spin_unlock(&gl->gl_lockref.lock);
1599 }
1600 
1601 /**
1602  * gfs2_glock_thaw - Thaw any frozen glocks
1603  * @sdp: The super block
1604  *
1605  */
1606 
1607 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1608 {
1609         glock_hash_walk(thaw_glock, sdp);
1610 }
1611 
1612 static void dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1613 {
1614         spin_lock(&gl->gl_lockref.lock);
1615         gfs2_dump_glock(seq, gl);
1616         spin_unlock(&gl->gl_lockref.lock);
1617 }
1618 
1619 static void dump_glock_func(struct gfs2_glock *gl)
1620 {
1621         dump_glock(NULL, gl);
1622 }
1623 
1624 /**
1625  * gfs2_gl_hash_clear - Empty out the glock hash table
1626  * @sdp: the filesystem
1627  * @wait: wait until it's all gone
1628  *
1629  * Called when unmounting the filesystem.
1630  */
1631 
1632 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1633 {
1634         set_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags);
1635         flush_workqueue(glock_workqueue);
1636         glock_hash_walk(clear_glock, sdp);
1637         flush_workqueue(glock_workqueue);
1638         wait_event_timeout(sdp->sd_glock_wait,
1639                            atomic_read(&sdp->sd_glock_disposal) == 0,
1640                            HZ * 600);
1641         glock_hash_walk(dump_glock_func, sdp);
1642 }
1643 
1644 void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1645 {
1646         struct gfs2_glock *gl = ip->i_gl;
1647         int ret;
1648 
1649         ret = gfs2_truncatei_resume(ip);
1650         gfs2_assert_withdraw(gl->gl_name.ln_sbd, ret == 0);
1651 
1652         spin_lock(&gl->gl_lockref.lock);
1653         clear_bit(GLF_LOCK, &gl->gl_flags);
1654         run_queue(gl, 1);
1655         spin_unlock(&gl->gl_lockref.lock);
1656 }
1657 
1658 static const char *state2str(unsigned state)
1659 {
1660         switch(state) {
1661         case LM_ST_UNLOCKED:
1662                 return "UN";
1663         case LM_ST_SHARED:
1664                 return "SH";
1665         case LM_ST_DEFERRED:
1666                 return "DF";
1667         case LM_ST_EXCLUSIVE:
1668                 return "EX";
1669         }
1670         return "??";
1671 }
1672 
1673 static const char *hflags2str(char *buf, u16 flags, unsigned long iflags)
1674 {
1675         char *p = buf;
1676         if (flags & LM_FLAG_TRY)
1677                 *p++ = 't';
1678         if (flags & LM_FLAG_TRY_1CB)
1679                 *p++ = 'T';
1680         if (flags & LM_FLAG_NOEXP)
1681                 *p++ = 'e';
1682         if (flags & LM_FLAG_ANY)
1683                 *p++ = 'A';
1684         if (flags & LM_FLAG_PRIORITY)
1685                 *p++ = 'p';
1686         if (flags & GL_ASYNC)
1687                 *p++ = 'a';
1688         if (flags & GL_EXACT)
1689                 *p++ = 'E';
1690         if (flags & GL_NOCACHE)
1691                 *p++ = 'c';
1692         if (test_bit(HIF_HOLDER, &iflags))
1693                 *p++ = 'H';
1694         if (test_bit(HIF_WAIT, &iflags))
1695                 *p++ = 'W';
1696         if (test_bit(HIF_FIRST, &iflags))
1697                 *p++ = 'F';
1698         *p = 0;
1699         return buf;
1700 }
1701 
1702 /**
1703  * dump_holder - print information about a glock holder
1704  * @seq: the seq_file struct
1705  * @gh: the glock holder
1706  *
1707  */
1708 
1709 static void dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1710 {
1711         struct task_struct *gh_owner = NULL;
1712         char flags_buf[32];
1713 
1714         rcu_read_lock();
1715         if (gh->gh_owner_pid)
1716                 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1717         gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
1718                        state2str(gh->gh_state),
1719                        hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1720                        gh->gh_error,
1721                        gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1722                        gh_owner ? gh_owner->comm : "(ended)",
1723                        (void *)gh->gh_ip);
1724         rcu_read_unlock();
1725 }
1726 
1727 static const char *gflags2str(char *buf, const struct gfs2_glock *gl)
1728 {
1729         const unsigned long *gflags = &gl->gl_flags;
1730         char *p = buf;
1731 
1732         if (test_bit(GLF_LOCK, gflags))
1733                 *p++ = 'l';
1734         if (test_bit(GLF_DEMOTE, gflags))
1735                 *p++ = 'D';
1736         if (test_bit(GLF_PENDING_DEMOTE, gflags))
1737                 *p++ = 'd';
1738         if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1739                 *p++ = 'p';
1740         if (test_bit(GLF_DIRTY, gflags))
1741                 *p++ = 'y';
1742         if (test_bit(GLF_LFLUSH, gflags))
1743                 *p++ = 'f';
1744         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1745                 *p++ = 'i';
1746         if (test_bit(GLF_REPLY_PENDING, gflags))
1747                 *p++ = 'r';
1748         if (test_bit(GLF_INITIAL, gflags))
1749                 *p++ = 'I';
1750         if (test_bit(GLF_FROZEN, gflags))
1751                 *p++ = 'F';
1752         if (test_bit(GLF_QUEUED, gflags))
1753                 *p++ = 'q';
1754         if (test_bit(GLF_LRU, gflags))
1755                 *p++ = 'L';
1756         if (gl->gl_object)
1757                 *p++ = 'o';
1758         if (test_bit(GLF_BLOCKING, gflags))
1759                 *p++ = 'b';
1760         *p = 0;
1761         return buf;
1762 }
1763 
1764 /**
1765  * gfs2_dump_glock - print information about a glock
1766  * @seq: The seq_file struct
1767  * @gl: the glock
1768  *
1769  * The file format is as follows:
1770  * One line per object, capital letters are used to indicate objects
1771  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1772  * other objects are indented by a single space and follow the glock to
1773  * which they are related. Fields are indicated by lower case letters
1774  * followed by a colon and the field value, except for strings which are in
1775  * [] so that its possible to see if they are composed of spaces for
1776  * example. The field's are n = number (id of the object), f = flags,
1777  * t = type, s = state, r = refcount, e = error, p = pid.
1778  *
1779  */
1780 
1781 void gfs2_dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1782 {
1783         const struct gfs2_glock_operations *glops = gl->gl_ops;
1784         unsigned long long dtime;
1785         const struct gfs2_holder *gh;
1786         char gflags_buf[32];
1787 
1788         dtime = jiffies - gl->gl_demote_time;
1789         dtime *= 1000000/HZ; /* demote time in uSec */
1790         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1791                 dtime = 0;
1792         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",
1793                   state2str(gl->gl_state),
1794                   gl->gl_name.ln_type,
1795                   (unsigned long long)gl->gl_name.ln_number,
1796                   gflags2str(gflags_buf, gl),
1797                   state2str(gl->gl_target),
1798                   state2str(gl->gl_demote_state), dtime,
1799                   atomic_read(&gl->gl_ail_count),
1800                   atomic_read(&gl->gl_revokes),
1801                   (int)gl->gl_lockref.count, gl->gl_hold_time);
1802 
1803         list_for_each_entry(gh, &gl->gl_holders, gh_list)
1804                 dump_holder(seq, gh);
1805 
1806         if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1807                 glops->go_dump(seq, gl);
1808 }
1809 
1810 static int gfs2_glstats_seq_show(struct seq_file *seq, void *iter_ptr)
1811 {
1812         struct gfs2_glock *gl = iter_ptr;
1813 
1814         seq_printf(seq, "G: n:%u/%llx rtt:%llu/%llu rttb:%llu/%llu irt:%llu/%llu dcnt: %llu qcnt: %llu\n",
1815                    gl->gl_name.ln_type,
1816                    (unsigned long long)gl->gl_name.ln_number,
1817                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTT],
1818                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTVAR],
1819                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTB],
1820                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SRTTVARB],
1821                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SIRT],
1822                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_SIRTVAR],
1823                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_DCOUNT],
1824                    (unsigned long long)gl->gl_stats.stats[GFS2_LKS_QCOUNT]);
1825         return 0;
1826 }
1827 
1828 static const char *gfs2_gltype[] = {
1829         "type",
1830         "reserved",
1831         "nondisk",
1832         "inode",
1833         "rgrp",
1834         "meta",
1835         "iopen",
1836         "flock",
1837         "plock",
1838         "quota",
1839         "journal",
1840 };
1841 
1842 static const char *gfs2_stype[] = {
1843         [GFS2_LKS_SRTT]         = "srtt",
1844         [GFS2_LKS_SRTTVAR]      = "srttvar",
1845         [GFS2_LKS_SRTTB]        = "srttb",
1846         [GFS2_LKS_SRTTVARB]     = "srttvarb",
1847         [GFS2_LKS_SIRT]         = "sirt",
1848         [GFS2_LKS_SIRTVAR]      = "sirtvar",
1849         [GFS2_LKS_DCOUNT]       = "dlm",
1850         [GFS2_LKS_QCOUNT]       = "queue",
1851 };
1852 
1853 #define GFS2_NR_SBSTATS (ARRAY_SIZE(gfs2_gltype) * ARRAY_SIZE(gfs2_stype))
1854 
1855 static int gfs2_sbstats_seq_show(struct seq_file *seq, void *iter_ptr)
1856 {
1857         struct gfs2_sbd *sdp = seq->private;
1858         loff_t pos = *(loff_t *)iter_ptr;
1859         unsigned index = pos >> 3;
1860         unsigned subindex = pos & 0x07;
1861         int i;
1862 
1863         if (index == 0 && subindex != 0)
1864                 return 0;
1865 
1866         seq_printf(seq, "%-10s %8s:", gfs2_gltype[index],
1867                    (index == 0) ? "cpu": gfs2_stype[subindex]);
1868 
1869         for_each_possible_cpu(i) {
1870                 const struct gfs2_pcpu_lkstats *lkstats = per_cpu_ptr(sdp->sd_lkstats, i);
1871 
1872                 if (index == 0)
1873                         seq_printf(seq, " %15u", i);
1874                 else
1875                         seq_printf(seq, " %15llu", (unsigned long long)lkstats->
1876                                    lkstats[index - 1].stats[subindex]);
1877         }
1878         seq_putc(seq, '\n');
1879         return 0;
1880 }
1881 
1882 int __init gfs2_glock_init(void)
1883 {
1884         int i, ret;
1885 
1886         ret = rhashtable_init(&gl_hash_table, &ht_parms);
1887         if (ret < 0)
1888                 return ret;
1889 
1890         glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
1891                                           WQ_HIGHPRI | WQ_FREEZABLE, 0);
1892         if (!glock_workqueue) {
1893                 rhashtable_destroy(&gl_hash_table);
1894                 return -ENOMEM;
1895         }
1896         gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
1897                                                 WQ_MEM_RECLAIM | WQ_FREEZABLE,
1898                                                 0);
1899         if (!gfs2_delete_workqueue) {
1900                 destroy_workqueue(glock_workqueue);
1901                 rhashtable_destroy(&gl_hash_table);
1902                 return -ENOMEM;
1903         }
1904 
1905         ret = register_shrinker(&glock_shrinker);
1906         if (ret) {
1907                 destroy_workqueue(gfs2_delete_workqueue);
1908                 destroy_workqueue(glock_workqueue);
1909                 rhashtable_destroy(&gl_hash_table);
1910                 return ret;
1911         }
1912 
1913         for (i = 0; i < GLOCK_WAIT_TABLE_SIZE; i++)
1914                 init_waitqueue_head(glock_wait_table + i);
1915 
1916         return 0;
1917 }
1918 
1919 void gfs2_glock_exit(void)
1920 {
1921         unregister_shrinker(&glock_shrinker);
1922         rhashtable_destroy(&gl_hash_table);
1923         destroy_workqueue(glock_workqueue);
1924         destroy_workqueue(gfs2_delete_workqueue);
1925 }
1926 
1927 static void gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1928 {
1929         while ((gi->gl = rhashtable_walk_next(&gi->hti))) {
1930                 if (IS_ERR(gi->gl)) {
1931                         if (PTR_ERR(gi->gl) == -EAGAIN)
1932                                 continue;
1933                         gi->gl = NULL;
1934                         return;
1935                 }
1936                 /* Skip entries for other sb and dead entries */
1937                 if (gi->sdp == gi->gl->gl_name.ln_sbd &&
1938                     !__lockref_is_dead(&gi->gl->gl_lockref))
1939                         return;
1940         }
1941 }
1942 
1943 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1944         __acquires(RCU)
1945 {
1946         struct gfs2_glock_iter *gi = seq->private;
1947         loff_t n = *pos;
1948 
1949         rhashtable_walk_enter(&gl_hash_table, &gi->hti);
1950         if (rhashtable_walk_start(&gi->hti) != 0)
1951                 return NULL;
1952 
1953         do {
1954                 gfs2_glock_iter_next(gi);
1955         } while (gi->gl && n--);
1956 
1957         gi->last_pos = *pos;
1958 
1959         return gi->gl;
1960 }
1961 
1962 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1963                                  loff_t *pos)
1964 {
1965         struct gfs2_glock_iter *gi = seq->private;
1966 
1967         (*pos)++;
1968         gi->last_pos = *pos;
1969         gfs2_glock_iter_next(gi);
1970 
1971         return gi->gl;
1972 }
1973 
1974 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1975         __releases(RCU)
1976 {
1977         struct gfs2_glock_iter *gi = seq->private;
1978 
1979         gi->gl = NULL;
1980         rhashtable_walk_stop(&gi->hti);
1981         rhashtable_walk_exit(&gi->hti);
1982 }
1983 
1984 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1985 {
1986         dump_glock(seq, iter_ptr);
1987         return 0;
1988 }
1989 
1990 static void *gfs2_sbstats_seq_start(struct seq_file *seq, loff_t *pos)
1991 {
1992         preempt_disable();
1993         if (*pos >= GFS2_NR_SBSTATS)
1994                 return NULL;
1995         return pos;
1996 }
1997 
1998 static void *gfs2_sbstats_seq_next(struct seq_file *seq, void *iter_ptr,
1999                                    loff_t *pos)
2000 {
2001         (*pos)++;
2002         if (*pos >= GFS2_NR_SBSTATS)
2003                 return NULL;
2004         return pos;
2005 }
2006 
2007 static void gfs2_sbstats_seq_stop(struct seq_file *seq, void *iter_ptr)
2008 {
2009         preempt_enable();
2010 }
2011 
2012 static const struct seq_operations gfs2_glock_seq_ops = {
2013         .start = gfs2_glock_seq_start,
2014         .next  = gfs2_glock_seq_next,
2015         .stop  = gfs2_glock_seq_stop,
2016         .show  = gfs2_glock_seq_show,
2017 };
2018 
2019 static const struct seq_operations gfs2_glstats_seq_ops = {
2020         .start = gfs2_glock_seq_start,
2021         .next  = gfs2_glock_seq_next,
2022         .stop  = gfs2_glock_seq_stop,
2023         .show  = gfs2_glstats_seq_show,
2024 };
2025 
2026 static const struct seq_operations gfs2_sbstats_seq_ops = {
2027         .start = gfs2_sbstats_seq_start,
2028         .next  = gfs2_sbstats_seq_next,
2029         .stop  = gfs2_sbstats_seq_stop,
2030         .show  = gfs2_sbstats_seq_show,
2031 };
2032 
2033 #define GFS2_SEQ_GOODSIZE min(PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER, 65536UL)
2034 
2035 static int __gfs2_glocks_open(struct inode *inode, struct file *file,
2036                               const struct seq_operations *ops)
2037 {
2038         int ret = seq_open_private(file, ops, sizeof(struct gfs2_glock_iter));
2039         if (ret == 0) {
2040                 struct seq_file *seq = file->private_data;
2041                 struct gfs2_glock_iter *gi = seq->private;
2042 
2043                 gi->sdp = inode->i_private;
2044                 seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
2045                 if (seq->buf)
2046                         seq->size = GFS2_SEQ_GOODSIZE;
2047                 gi->gl = NULL;
2048         }
2049         return ret;
2050 }
2051 
2052 static int gfs2_glocks_open(struct inode *inode, struct file *file)
2053 {
2054         return __gfs2_glocks_open(inode, file, &gfs2_glock_seq_ops);
2055 }
2056 
2057 static int gfs2_glocks_release(struct inode *inode, struct file *file)
2058 {
2059         struct seq_file *seq = file->private_data;
2060         struct gfs2_glock_iter *gi = seq->private;
2061 
2062         gi->gl = NULL;
2063         return seq_release_private(inode, file);
2064 }
2065 
2066 static int gfs2_glstats_open(struct inode *inode, struct file *file)
2067 {
2068         return __gfs2_glocks_open(inode, file, &gfs2_glstats_seq_ops);
2069 }
2070 
2071 static int gfs2_sbstats_open(struct inode *inode, struct file *file)
2072 {
2073         int ret = seq_open(file, &gfs2_sbstats_seq_ops);
2074         if (ret == 0) {
2075                 struct seq_file *seq = file->private_data;
2076                 seq->private = inode->i_private;  /* sdp */
2077         }
2078         return ret;
2079 }
2080 
2081 static const struct file_operations gfs2_glocks_fops = {
2082         .owner   = THIS_MODULE,
2083         .open    = gfs2_glocks_open,
2084         .read    = seq_read,
2085         .llseek  = seq_lseek,
2086         .release = gfs2_glocks_release,
2087 };
2088 
2089 static const struct file_operations gfs2_glstats_fops = {
2090         .owner   = THIS_MODULE,
2091         .open    = gfs2_glstats_open,
2092         .read    = seq_read,
2093         .llseek  = seq_lseek,
2094         .release = gfs2_glocks_release,
2095 };
2096 
2097 static const struct file_operations gfs2_sbstats_fops = {
2098         .owner   = THIS_MODULE,
2099         .open    = gfs2_sbstats_open,
2100         .read    = seq_read,
2101         .llseek  = seq_lseek,
2102         .release = seq_release,
2103 };
2104 
2105 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
2106 {
2107         struct dentry *dent;
2108 
2109         dent = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
2110         if (IS_ERR_OR_NULL(dent))
2111                 goto fail;
2112         sdp->debugfs_dir = dent;
2113 
2114         dent = debugfs_create_file("glocks",
2115                                    S_IFREG | S_IRUGO,
2116                                    sdp->debugfs_dir, sdp,
2117                                    &gfs2_glocks_fops);
2118         if (IS_ERR_OR_NULL(dent))
2119                 goto fail;
2120         sdp->debugfs_dentry_glocks = dent;
2121 
2122         dent = debugfs_create_file("glstats",
2123                                    S_IFREG | S_IRUGO,
2124                                    sdp->debugfs_dir, sdp,
2125                                    &gfs2_glstats_fops);
2126         if (IS_ERR_OR_NULL(dent))
2127                 goto fail;
2128         sdp->debugfs_dentry_glstats = dent;
2129 
2130         dent = debugfs_create_file("sbstats",
2131                                    S_IFREG | S_IRUGO,
2132                                    sdp->debugfs_dir, sdp,
2133                                    &gfs2_sbstats_fops);
2134         if (IS_ERR_OR_NULL(dent))
2135                 goto fail;
2136         sdp->debugfs_dentry_sbstats = dent;
2137 
2138         return 0;
2139 fail:
2140         gfs2_delete_debugfs_file(sdp);
2141         return dent ? PTR_ERR(dent) : -ENOMEM;
2142 }
2143 
2144 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
2145 {
2146         if (sdp->debugfs_dir) {
2147                 if (sdp->debugfs_dentry_glocks) {
2148                         debugfs_remove(sdp->debugfs_dentry_glocks);
2149                         sdp->debugfs_dentry_glocks = NULL;
2150                 }
2151                 if (sdp->debugfs_dentry_glstats) {
2152                         debugfs_remove(sdp->debugfs_dentry_glstats);
2153                         sdp->debugfs_dentry_glstats = NULL;
2154                 }
2155                 if (sdp->debugfs_dentry_sbstats) {
2156                         debugfs_remove(sdp->debugfs_dentry_sbstats);
2157                         sdp->debugfs_dentry_sbstats = NULL;
2158                 }
2159                 debugfs_remove(sdp->debugfs_dir);
2160                 sdp->debugfs_dir = NULL;
2161         }
2162 }
2163 
2164 int gfs2_register_debugfs(void)
2165 {
2166         gfs2_root = debugfs_create_dir("gfs2", NULL);
2167         if (IS_ERR(gfs2_root))
2168                 return PTR_ERR(gfs2_root);
2169         return gfs2_root ? 0 : -ENOMEM;
2170 }
2171 
2172 void gfs2_unregister_debugfs(void)
2173 {
2174         debugfs_remove(gfs2_root);
2175         gfs2_root = NULL;
2176 }
2177 

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