Merge branch 'vendor/OPENSSL'
[dragonfly.git] / sys / vfs / hammer / hammer_flusher.c
1 /*
2  * Copyright (c) 2008 The DragonFly Project.  All rights reserved.
3  * 
4  * This code is derived from software contributed to The DragonFly Project
5  * by Matthew Dillon <dillon@backplane.com>
6  * 
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in
15  *    the documentation and/or other materials provided with the
16  *    distribution.
17  * 3. Neither the name of The DragonFly Project nor the names of its
18  *    contributors may be used to endorse or promote products derived
19  *    from this software without specific, prior written permission.
20  * 
21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32  * SUCH DAMAGE.
33  * 
34  * $DragonFly: src/sys/vfs/hammer/hammer_flusher.c,v 1.45 2008/07/31 04:42:04 dillon Exp $
35  */
36 /*
37  * HAMMER dependancy flusher thread
38  *
39  * Meta data updates create buffer dependancies which are arranged as a
40  * hierarchy of lists.
41  */
42
43 #include "hammer.h"
44
45 static void hammer_flusher_master_thread(void *arg);
46 static void hammer_flusher_slave_thread(void *arg);
47 static void hammer_flusher_flush(hammer_mount_t hmp);
48 static void hammer_flusher_flush_inode(hammer_inode_t ip,
49                                         hammer_transaction_t trans);
50
51 /*
52  * Support structures for the flusher threads.
53  */
54 struct hammer_flusher_info {
55         TAILQ_ENTRY(hammer_flusher_info) entry;
56         struct hammer_mount *hmp;
57         thread_t        td;
58         int             runstate;
59         int             count;
60         hammer_flush_group_t flg;
61         hammer_inode_t  work_array[HAMMER_FLUSH_GROUP_SIZE];
62 };
63
64 typedef struct hammer_flusher_info *hammer_flusher_info_t;
65
66 /*
67  * Sync all inodes pending on the flusher.
68  *
69  * All flush groups will be flushed.  This does not queue dirty inodes
70  * to the flush groups, it just flushes out what has already been queued!
71  */
72 void
73 hammer_flusher_sync(hammer_mount_t hmp)
74 {
75         int seq;
76
77         seq = hammer_flusher_async(hmp, NULL);
78         hammer_flusher_wait(hmp, seq);
79 }
80
81 /*
82  * Sync all inodes pending on the flusher - return immediately.
83  *
84  * All flush groups will be flushed.
85  */
86 int
87 hammer_flusher_async(hammer_mount_t hmp, hammer_flush_group_t close_flg)
88 {
89         hammer_flush_group_t flg;
90         int seq = hmp->flusher.next;
91
92         TAILQ_FOREACH(flg, &hmp->flush_group_list, flush_entry) {
93                 if (flg->running == 0)
94                         ++seq;
95                 flg->closed = 1;
96                 if (flg == close_flg)
97                         break;
98         }
99         if (hmp->flusher.td) {
100                 if (hmp->flusher.signal++ == 0)
101                         wakeup(&hmp->flusher.signal);
102         } else {
103                 seq = hmp->flusher.done;
104         }
105         return(seq);
106 }
107
108 int
109 hammer_flusher_async_one(hammer_mount_t hmp)
110 {
111         int seq;
112
113         if (hmp->flusher.td) {
114                 seq = hmp->flusher.next;
115                 if (hmp->flusher.signal++ == 0)
116                         wakeup(&hmp->flusher.signal);
117         } else {
118                 seq = hmp->flusher.done;
119         }
120         return(seq);
121 }
122
123 /*
124  * Wait for the flusher to get to the specified sequence number.
125  * Signal the flusher as often as necessary to keep it going.
126  */
127 void
128 hammer_flusher_wait(hammer_mount_t hmp, int seq)
129 {
130         while ((int)(seq - hmp->flusher.done) > 0) {
131                 if (hmp->flusher.act != seq) {
132                         if (hmp->flusher.signal++ == 0)
133                                 wakeup(&hmp->flusher.signal);
134                 }
135                 tsleep(&hmp->flusher.done, 0, "hmrfls", 0);
136         }
137 }
138
139 void
140 hammer_flusher_wait_next(hammer_mount_t hmp)
141 {
142         int seq;
143
144         seq = hammer_flusher_async_one(hmp);
145         hammer_flusher_wait(hmp, seq);
146 }
147
148 void
149 hammer_flusher_create(hammer_mount_t hmp)
150 {
151         hammer_flusher_info_t info;
152         int i;
153
154         hmp->flusher.signal = 0;
155         hmp->flusher.act = 0;
156         hmp->flusher.done = 0;
157         hmp->flusher.next = 1;
158         hammer_ref(&hmp->flusher.finalize_lock);
159         TAILQ_INIT(&hmp->flusher.run_list);
160         TAILQ_INIT(&hmp->flusher.ready_list);
161
162         lwkt_create(hammer_flusher_master_thread, hmp,
163                     &hmp->flusher.td, NULL, 0, -1, "hammer-M");
164         for (i = 0; i < HAMMER_MAX_FLUSHERS; ++i) {
165                 info = kmalloc(sizeof(*info), hmp->m_misc, M_WAITOK|M_ZERO);
166                 info->hmp = hmp;
167                 TAILQ_INSERT_TAIL(&hmp->flusher.ready_list, info, entry);
168                 lwkt_create(hammer_flusher_slave_thread, info,
169                             &info->td, NULL, 0, -1, "hammer-S%d", i);
170         }
171 }
172
173 void
174 hammer_flusher_destroy(hammer_mount_t hmp)
175 {
176         hammer_flusher_info_t info;
177
178         /*
179          * Kill the master
180          */
181         hmp->flusher.exiting = 1;
182         while (hmp->flusher.td) {
183                 ++hmp->flusher.signal;
184                 wakeup(&hmp->flusher.signal);
185                 tsleep(&hmp->flusher.exiting, 0, "hmrwex", hz);
186         }
187
188         /*
189          * Kill the slaves
190          */
191         while ((info = TAILQ_FIRST(&hmp->flusher.ready_list)) != NULL) {
192                 KKASSERT(info->runstate == 0);
193                 TAILQ_REMOVE(&hmp->flusher.ready_list, info, entry);
194                 info->runstate = -1;
195                 wakeup(&info->runstate);
196                 while (info->td)
197                         tsleep(&info->td, 0, "hmrwwc", 0);
198                 TAILQ_REMOVE(&hmp->flusher.ready_list, info, entry);
199                 kfree(info, hmp->m_misc);
200         }
201 }
202
203 /*
204  * The master flusher thread manages the flusher sequence id and
205  * synchronization with the slave work threads.
206  */
207 static void
208 hammer_flusher_master_thread(void *arg)
209 {
210         hammer_flush_group_t flg;
211         hammer_mount_t hmp;
212
213         hmp = arg;
214
215         for (;;) {
216                 /*
217                  * Do at least one flush cycle.  We may have to update the
218                  * UNDO FIFO even if no inodes are queued.
219                  */
220                 for (;;) {
221                         while (hmp->flusher.group_lock)
222                                 tsleep(&hmp->flusher.group_lock, 0, "hmrhld", 0);
223                         hmp->flusher.act = hmp->flusher.next;
224                         ++hmp->flusher.next;
225                         hammer_flusher_clean_loose_ios(hmp);
226                         hammer_flusher_flush(hmp);
227                         hmp->flusher.done = hmp->flusher.act;
228                         wakeup(&hmp->flusher.done);
229                         flg = TAILQ_FIRST(&hmp->flush_group_list);
230                         if (flg == NULL || flg->closed == 0)
231                                 break;
232                         if (hmp->flags & HAMMER_MOUNT_CRITICAL_ERROR)
233                                 break;
234                 }
235
236                 /*
237                  * Wait for activity.
238                  */
239                 if (hmp->flusher.exiting && TAILQ_EMPTY(&hmp->flush_group_list))
240                         break;
241                 while (hmp->flusher.signal == 0)
242                         tsleep(&hmp->flusher.signal, 0, "hmrwwa", 0);
243
244                 /*
245                  * Flush for each count on signal but only allow one extra
246                  * flush request to build up.
247                  */
248                 if (--hmp->flusher.signal != 0)
249                         hmp->flusher.signal = 1;
250         }
251
252         /*
253          * And we are done.
254          */
255         hmp->flusher.td = NULL;
256         wakeup(&hmp->flusher.exiting);
257         lwkt_exit();
258 }
259
260 /*
261  * Flush all inodes in the current flush group.
262  */
263 static void
264 hammer_flusher_flush(hammer_mount_t hmp)
265 {
266         hammer_flusher_info_t info;
267         hammer_flush_group_t flg;
268         hammer_reserve_t resv;
269         hammer_inode_t ip;
270         hammer_inode_t next_ip;
271         int slave_index;
272         int count;
273
274         /*
275          * Just in-case there's a flush race on mount
276          */
277         if (TAILQ_FIRST(&hmp->flusher.ready_list) == NULL)
278                 return;
279
280         /*
281          * We only do one flg but we may have to loop/retry.
282          */
283         count = 0;
284         while ((flg = TAILQ_FIRST(&hmp->flush_group_list)) != NULL) {
285                 ++count;
286                 if (hammer_debug_general & 0x0001) {
287                         kprintf("hammer_flush %d ttl=%d recs=%d\n",
288                                 hmp->flusher.act,
289                                 flg->total_count, flg->refs);
290                 }
291                 if (hmp->flags & HAMMER_MOUNT_CRITICAL_ERROR)
292                         break;
293                 hammer_start_transaction_fls(&hmp->flusher.trans, hmp);
294
295                 /*
296                  * If the previous flush cycle just about exhausted our
297                  * UNDO space we may have to do a dummy cycle to move the
298                  * first_offset up before actually digging into a new cycle,
299                  * or the new cycle will not have sufficient undo space.
300                  */
301                 if (hammer_flusher_undo_exhausted(&hmp->flusher.trans, 3))
302                         hammer_flusher_finalize(&hmp->flusher.trans, 0);
303
304                 /*
305                  * Ok, we are running this flush group now (this prevents new
306                  * additions to it).
307                  */
308                 flg->running = 1;
309                 if (hmp->next_flush_group == flg)
310                         hmp->next_flush_group = TAILQ_NEXT(flg, flush_entry);
311
312                 /*
313                  * Iterate the inodes in the flg's flush_list and assign
314                  * them to slaves.
315                  */
316                 slave_index = 0;
317                 info = TAILQ_FIRST(&hmp->flusher.ready_list);
318                 next_ip = TAILQ_FIRST(&flg->flush_list);
319
320                 while ((ip = next_ip) != NULL) {
321                         next_ip = TAILQ_NEXT(ip, flush_entry);
322
323                         /*
324                          * Add ip to the slave's work array.  The slave is
325                          * not currently running.
326                          */
327                         info->work_array[info->count++] = ip;
328                         if (info->count != HAMMER_FLUSH_GROUP_SIZE)
329                                 continue;
330
331                         /*
332                          * Get the slave running
333                          */
334                         TAILQ_REMOVE(&hmp->flusher.ready_list, info, entry);
335                         TAILQ_INSERT_TAIL(&hmp->flusher.run_list, info, entry);
336                         info->flg = flg;
337                         info->runstate = 1;
338                         wakeup(&info->runstate);
339
340                         /*
341                          * Get a new slave.  We may have to wait for one to
342                          * finish running.
343                          */
344                         while ((info = TAILQ_FIRST(&hmp->flusher.ready_list)) == NULL) {
345                                 tsleep(&hmp->flusher.ready_list, 0, "hmrfcc", 0);
346                         }
347                 }
348
349                 /*
350                  * Run the current slave if necessary
351                  */
352                 if (info->count) {
353                         TAILQ_REMOVE(&hmp->flusher.ready_list, info, entry);
354                         TAILQ_INSERT_TAIL(&hmp->flusher.run_list, info, entry);
355                         info->flg = flg;
356                         info->runstate = 1;
357                         wakeup(&info->runstate);
358                 }
359
360                 /*
361                  * Wait for all slaves to finish running
362                  */
363                 while (TAILQ_FIRST(&hmp->flusher.run_list) != NULL)
364                         tsleep(&hmp->flusher.ready_list, 0, "hmrfcc", 0);
365
366                 /*
367                  * Do the final finalization, clean up
368                  */
369                 hammer_flusher_finalize(&hmp->flusher.trans, 1);
370                 hmp->flusher.tid = hmp->flusher.trans.tid;
371
372                 hammer_done_transaction(&hmp->flusher.trans);
373
374                 /*
375                  * Loop up on the same flg.  If the flg is done clean it up
376                  * and break out.  We only flush one flg.
377                  */
378                 if (TAILQ_FIRST(&flg->flush_list) == NULL) {
379                         KKASSERT(TAILQ_EMPTY(&flg->flush_list));
380                         KKASSERT(flg->refs == 0);
381                         TAILQ_REMOVE(&hmp->flush_group_list, flg, flush_entry);
382                         kfree(flg, hmp->m_misc);
383                         break;
384                 }
385         }
386
387         /*
388          * We may have pure meta-data to flush, or we may have to finish
389          * cycling the UNDO FIFO, even if there were no flush groups.
390          */
391         if (count == 0 && hammer_flusher_haswork(hmp)) {
392                 hammer_start_transaction_fls(&hmp->flusher.trans, hmp);
393                 hammer_flusher_finalize(&hmp->flusher.trans, 1);
394                 hammer_done_transaction(&hmp->flusher.trans);
395         }
396
397         /*
398          * Clean up any freed big-blocks (typically zone-2). 
399          * resv->flush_group is typically set several flush groups ahead
400          * of the free to ensure that the freed block is not reused until
401          * it can no longer be reused.
402          */
403         while ((resv = TAILQ_FIRST(&hmp->delay_list)) != NULL) {
404                 if (resv->flush_group != hmp->flusher.act)
405                         break;
406                 hammer_reserve_clrdelay(hmp, resv);
407         }
408 }
409
410
411 /*
412  * The slave flusher thread pulls work off the master flush_list until no
413  * work is left.
414  */
415 static void
416 hammer_flusher_slave_thread(void *arg)
417 {
418         hammer_flush_group_t flg;
419         hammer_flusher_info_t info;
420         hammer_mount_t hmp;
421         hammer_inode_t ip;
422         int i;
423
424         info = arg;
425         hmp = info->hmp;
426
427         for (;;) {
428                 while (info->runstate == 0)
429                         tsleep(&info->runstate, 0, "hmrssw", 0);
430                 if (info->runstate < 0)
431                         break;
432                 flg = info->flg;
433
434                 for (i = 0; i < info->count; ++i) {
435                         ip = info->work_array[i];
436                         hammer_flusher_flush_inode(ip, &hmp->flusher.trans);
437                         ++hammer_stats_inode_flushes;
438                 }
439                 info->count = 0;
440                 info->runstate = 0;
441                 TAILQ_REMOVE(&hmp->flusher.run_list, info, entry);
442                 TAILQ_INSERT_TAIL(&hmp->flusher.ready_list, info, entry);
443                 wakeup(&hmp->flusher.ready_list);
444         }
445         info->td = NULL;
446         wakeup(&info->td);
447         lwkt_exit();
448 }
449
450 void
451 hammer_flusher_clean_loose_ios(hammer_mount_t hmp)
452 {
453         hammer_buffer_t buffer;
454         hammer_io_t io;
455
456         /*
457          * loose ends - buffers without bp's aren't tracked by the kernel
458          * and can build up, so clean them out.  This can occur when an
459          * IO completes on a buffer with no references left.
460          */
461         if ((io = TAILQ_FIRST(&hmp->lose_list)) != NULL) {
462                 crit_enter();   /* biodone() race */
463                 while ((io = TAILQ_FIRST(&hmp->lose_list)) != NULL) {
464                         KKASSERT(io->mod_list == &hmp->lose_list);
465                         TAILQ_REMOVE(&hmp->lose_list, io, mod_entry);
466                         io->mod_list = NULL;
467                         if (io->lock.refs == 0)
468                                 ++hammer_count_refedbufs;
469                         hammer_ref(&io->lock);
470                         buffer = (void *)io;
471                         hammer_rel_buffer(buffer, 0);
472                 }
473                 crit_exit();
474         }
475 }
476
477 /*
478  * Flush a single inode that is part of a flush group.
479  *
480  * Flusher errors are extremely serious, even ENOSPC shouldn't occur because
481  * the front-end should have reserved sufficient space on the media.  Any
482  * error other then EWOULDBLOCK will force the mount to be read-only.
483  */
484 static
485 void
486 hammer_flusher_flush_inode(hammer_inode_t ip, hammer_transaction_t trans)
487 {
488         hammer_mount_t hmp = ip->hmp;
489         int error;
490
491         hammer_flusher_clean_loose_ios(hmp);
492         error = hammer_sync_inode(trans, ip);
493
494         /*
495          * EWOULDBLOCK can happen under normal operation, all other errors
496          * are considered extremely serious.  We must set WOULDBLOCK
497          * mechanics to deal with the mess left over from the abort of the
498          * previous flush.
499          */
500         if (error) {
501                 ip->flags |= HAMMER_INODE_WOULDBLOCK;
502                 if (error == EWOULDBLOCK)
503                         error = 0;
504         }
505         hammer_flush_inode_done(ip, error);
506         while (hmp->flusher.finalize_want)
507                 tsleep(&hmp->flusher.finalize_want, 0, "hmrsxx", 0);
508         if (hammer_flusher_undo_exhausted(trans, 1)) {
509                 kprintf("HAMMER: Warning: UNDO area too small!\n");
510                 hammer_flusher_finalize(trans, 1);
511         } else if (hammer_flusher_meta_limit(trans->hmp)) {
512                 hammer_flusher_finalize(trans, 0);
513         }
514 }
515
516 /*
517  * Return non-zero if the UNDO area has less then (QUARTER / 4) of its
518  * space left.
519  *
520  * 1/4 - Emergency free undo space level.  Below this point the flusher
521  *       will finalize even if directory dependancies have not been resolved.
522  *
523  * 2/4 - Used by the pruning and reblocking code.  These functions may be
524  *       running in parallel with a flush and cannot be allowed to drop
525  *       available undo space to emergency levels.
526  *
527  * 3/4 - Used at the beginning of a flush to force-sync the volume header
528  *       to give the flush plenty of runway to work in.
529  */
530 int
531 hammer_flusher_undo_exhausted(hammer_transaction_t trans, int quarter)
532 {
533         if (hammer_undo_space(trans) <
534             hammer_undo_max(trans->hmp) * quarter / 4) {
535                 return(1);
536         } else {
537                 return(0);
538         }
539 }
540
541 /*
542  * Flush all pending UNDOs, wait for write completion, update the volume
543  * header with the new UNDO end position, and flush it.  Then
544  * asynchronously flush the meta-data.
545  *
546  * If this is the last finalization in a flush group we also synchronize
547  * our cached blockmap and set hmp->flusher_undo_start and our cached undo
548  * fifo first_offset so the next flush resets the FIFO pointers.
549  *
550  * If this is not final it is being called because too many dirty meta-data
551  * buffers have built up and must be flushed with UNDO synchronization to
552  * avoid a buffer cache deadlock.
553  */
554 void
555 hammer_flusher_finalize(hammer_transaction_t trans, int final)
556 {
557         hammer_volume_t root_volume;
558         hammer_blockmap_t cundomap, dundomap;
559         hammer_mount_t hmp;
560         hammer_io_t io;
561         int count;
562         int i;
563
564         hmp = trans->hmp;
565         root_volume = trans->rootvol;
566
567         /*
568          * Exclusively lock the flusher.  This guarantees that all dirty
569          * buffers will be idled (have a mod-count of 0).
570          */
571         ++hmp->flusher.finalize_want;
572         hammer_lock_ex(&hmp->flusher.finalize_lock);
573
574         /*
575          * If this isn't the final sync several threads may have hit the
576          * meta-limit at the same time and raced.  Only sync if we really
577          * have to, after acquiring the lock.
578          */
579         if (final == 0 && !hammer_flusher_meta_limit(hmp))
580                 goto done;
581
582         if (hmp->flags & HAMMER_MOUNT_CRITICAL_ERROR)
583                 goto done;
584
585         /*
586          * Flush data buffers.  This can occur asynchronously and at any
587          * time.  We must interlock against the frontend direct-data write
588          * but do not have to acquire the sync-lock yet.
589          */
590         count = 0;
591         while ((io = TAILQ_FIRST(&hmp->data_list)) != NULL) {
592                 if (io->ioerror)
593                         break;
594                 if (io->lock.refs == 0)
595                         ++hammer_count_refedbufs;
596                 hammer_ref(&io->lock);
597                 hammer_io_write_interlock(io);
598                 KKASSERT(io->type != HAMMER_STRUCTURE_VOLUME);
599                 hammer_io_flush(io);
600                 hammer_io_done_interlock(io);
601                 hammer_rel_buffer((hammer_buffer_t)io, 0);
602                 ++count;
603         }
604
605         /*
606          * The sync-lock is required for the remaining sequence.  This lock
607          * prevents meta-data from being modified.
608          */
609         hammer_sync_lock_ex(trans);
610
611         /*
612          * If we have been asked to finalize the volume header sync the
613          * cached blockmap to the on-disk blockmap.  Generate an UNDO
614          * record for the update.
615          */
616         if (final) {
617                 cundomap = &hmp->blockmap[0];
618                 dundomap = &root_volume->ondisk->vol0_blockmap[0];
619                 if (root_volume->io.modified) {
620                         hammer_modify_volume(trans, root_volume,
621                                              dundomap, sizeof(hmp->blockmap));
622                         for (i = 0; i < HAMMER_MAX_ZONES; ++i)
623                                 hammer_crc_set_blockmap(&cundomap[i]);
624                         bcopy(cundomap, dundomap, sizeof(hmp->blockmap));
625                         hammer_modify_volume_done(root_volume);
626                 }
627         }
628
629         /*
630          * Flush UNDOs
631          */
632         count = 0;
633         while ((io = TAILQ_FIRST(&hmp->undo_list)) != NULL) {
634                 if (io->ioerror)
635                         break;
636                 KKASSERT(io->modify_refs == 0);
637                 if (io->lock.refs == 0)
638                         ++hammer_count_refedbufs;
639                 hammer_ref(&io->lock);
640                 KKASSERT(io->type != HAMMER_STRUCTURE_VOLUME);
641                 hammer_io_flush(io);
642                 hammer_rel_buffer((hammer_buffer_t)io, 0);
643                 ++count;
644         }
645
646         /*
647          * Wait for I/Os to complete
648          */
649         hammer_flusher_clean_loose_ios(hmp);
650         hammer_io_wait_all(hmp, "hmrfl1");
651
652         if (hmp->flags & HAMMER_MOUNT_CRITICAL_ERROR)
653                 goto failed;
654
655         /*
656          * Update the on-disk volume header with new UNDO FIFO end position
657          * (do not generate new UNDO records for this change).  We have to
658          * do this for the UNDO FIFO whether (final) is set or not.
659          *
660          * Also update the on-disk next_tid field.  This does not require
661          * an UNDO.  However, because our TID is generated before we get
662          * the sync lock another sync may have beat us to the punch.
663          *
664          * This also has the side effect of updating first_offset based on
665          * a prior finalization when the first finalization of the next flush
666          * cycle occurs, removing any undo info from the prior finalization
667          * from consideration.
668          *
669          * The volume header will be flushed out synchronously.
670          */
671         dundomap = &root_volume->ondisk->vol0_blockmap[HAMMER_ZONE_UNDO_INDEX];
672         cundomap = &hmp->blockmap[HAMMER_ZONE_UNDO_INDEX];
673
674         if (dundomap->first_offset != cundomap->first_offset ||
675                    dundomap->next_offset != cundomap->next_offset) {
676                 hammer_modify_volume(NULL, root_volume, NULL, 0);
677                 dundomap->first_offset = cundomap->first_offset;
678                 dundomap->next_offset = cundomap->next_offset;
679                 hammer_crc_set_blockmap(dundomap);
680                 hammer_modify_volume_done(root_volume);
681         }
682
683         /*
684          * vol0_next_tid is used for TID selection and is updated without
685          * an UNDO so we do not reuse a TID that may have been rolled-back.
686          *
687          * vol0_last_tid is the highest fully-synchronized TID.  It is
688          * set-up when the UNDO fifo is fully synced, later on (not here).
689          */
690         if (root_volume->io.modified) {
691                 hammer_modify_volume(NULL, root_volume, NULL, 0);
692                 if (root_volume->ondisk->vol0_next_tid < trans->tid)
693                         root_volume->ondisk->vol0_next_tid = trans->tid;
694                 hammer_crc_set_volume(root_volume->ondisk);
695                 hammer_modify_volume_done(root_volume);
696                 hammer_io_flush(&root_volume->io);
697         }
698
699         /*
700          * Wait for I/Os to complete
701          */
702         hammer_flusher_clean_loose_ios(hmp);
703         hammer_io_wait_all(hmp, "hmrfl2");
704
705         if (hmp->flags & HAMMER_MOUNT_CRITICAL_ERROR)
706                 goto failed;
707
708         /*
709          * Flush meta-data.  The meta-data will be undone if we crash
710          * so we can safely flush it asynchronously.
711          *
712          * Repeated catchups will wind up flushing this update's meta-data
713          * and the UNDO buffers for the next update simultaniously.  This
714          * is ok.
715          */
716         count = 0;
717         while ((io = TAILQ_FIRST(&hmp->meta_list)) != NULL) {
718                 if (io->ioerror)
719                         break;
720                 KKASSERT(io->modify_refs == 0);
721                 if (io->lock.refs == 0)
722                         ++hammer_count_refedbufs;
723                 hammer_ref(&io->lock);
724                 KKASSERT(io->type != HAMMER_STRUCTURE_VOLUME);
725                 hammer_io_flush(io);
726                 hammer_rel_buffer((hammer_buffer_t)io, 0);
727                 ++count;
728         }
729
730         /*
731          * If this is the final finalization for the flush group set
732          * up for the next sequence by setting a new first_offset in
733          * our cached blockmap and clearing the undo history.
734          *
735          * Even though we have updated our cached first_offset, the on-disk
736          * first_offset still governs available-undo-space calculations.
737          */
738         if (final) {
739                 cundomap = &hmp->blockmap[HAMMER_ZONE_UNDO_INDEX];
740                 if (cundomap->first_offset == cundomap->next_offset) {
741                         hmp->hflags &= ~HMNT_UNDO_DIRTY;
742                 } else {
743                         cundomap->first_offset = cundomap->next_offset;
744                         hmp->hflags |= HMNT_UNDO_DIRTY;
745                 }
746                 hammer_clear_undo_history(hmp);
747
748                 /*
749                  * Flush tid sequencing.  flush_tid1 is fully synchronized,
750                  * meaning a crash will not roll it back.  flush_tid2 has
751                  * been written out asynchronously and a crash will roll
752                  * it back.  flush_tid1 is used for all mirroring masters.
753                  */
754                 if (hmp->flush_tid1 != hmp->flush_tid2) {
755                         hmp->flush_tid1 = hmp->flush_tid2;
756                         wakeup(&hmp->flush_tid1);
757                 }
758                 hmp->flush_tid2 = trans->tid;
759         }
760
761         /*
762          * Cleanup.  Report any critical errors.
763          */
764 failed:
765         hammer_sync_unlock(trans);
766
767         if (hmp->flags & HAMMER_MOUNT_CRITICAL_ERROR) {
768                 kprintf("HAMMER(%s): Critical write error during flush, "
769                         "refusing to sync UNDO FIFO\n",
770                         root_volume->ondisk->vol_name);
771         }
772
773 done:
774         hammer_unlock(&hmp->flusher.finalize_lock);
775
776         if (--hmp->flusher.finalize_want == 0)
777                 wakeup(&hmp->flusher.finalize_want);
778         hammer_stats_commits += final;
779 }
780
781 /*
782  * Return non-zero if too many dirty meta-data buffers have built up.
783  *
784  * Since we cannot allow such buffers to flush until we have dealt with
785  * the UNDOs, we risk deadlocking the kernel's buffer cache.
786  */
787 int
788 hammer_flusher_meta_limit(hammer_mount_t hmp)
789 {
790         if (hmp->locked_dirty_space + hmp->io_running_space >
791             hammer_limit_dirtybufspace) {
792                 return(1);
793         }
794         return(0);
795 }
796
797 /*
798  * Return non-zero if too many dirty meta-data buffers have built up.
799  *
800  * This version is used by background operations (mirror, prune, reblock)
801  * to leave room for foreground operations.
802  */
803 int
804 hammer_flusher_meta_halflimit(hammer_mount_t hmp)
805 {
806         if (hmp->locked_dirty_space + hmp->io_running_space >
807             hammer_limit_dirtybufspace / 2) {
808                 return(1);
809         }
810         return(0);
811 }
812
813 /*
814  * Return non-zero if the flusher still has something to flush.
815  */
816 int
817 hammer_flusher_haswork(hammer_mount_t hmp)
818 {
819         if (hmp->flags & HAMMER_MOUNT_CRITICAL_ERROR)
820                 return(0);
821         if (TAILQ_FIRST(&hmp->flush_group_list) ||      /* dirty inodes */
822             TAILQ_FIRST(&hmp->volu_list) ||             /* dirty bufffers */
823             TAILQ_FIRST(&hmp->undo_list) ||
824             TAILQ_FIRST(&hmp->data_list) ||
825             TAILQ_FIRST(&hmp->meta_list) ||
826             (hmp->hflags & HMNT_UNDO_DIRTY)             /* UNDO FIFO sync */
827         ) {
828                 return(1);
829         }
830         return(0);
831 }
832