[GFS2] Fix bug where lock not held
[powerpc.git] / fs / gfs2 / log.c
1 /*
2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
3  * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
4  *
5  * This copyrighted material is made available to anyone wishing to use,
6  * modify, copy, or redistribute it subject to the terms and conditions
7  * of the GNU General Public License version 2.
8  */
9
10 #include <linux/sched.h>
11 #include <linux/slab.h>
12 #include <linux/spinlock.h>
13 #include <linux/completion.h>
14 #include <linux/buffer_head.h>
15 #include <linux/gfs2_ondisk.h>
16 #include <linux/crc32.h>
17 #include <linux/lm_interface.h>
18
19 #include "gfs2.h"
20 #include "incore.h"
21 #include "bmap.h"
22 #include "glock.h"
23 #include "log.h"
24 #include "lops.h"
25 #include "meta_io.h"
26 #include "util.h"
27 #include "dir.h"
28
29 #define PULL 1
30
31 /**
32  * gfs2_struct2blk - compute stuff
33  * @sdp: the filesystem
34  * @nstruct: the number of structures
35  * @ssize: the size of the structures
36  *
37  * Compute the number of log descriptor blocks needed to hold a certain number
38  * of structures of a certain size.
39  *
40  * Returns: the number of blocks needed (minimum is always 1)
41  */
42
43 unsigned int gfs2_struct2blk(struct gfs2_sbd *sdp, unsigned int nstruct,
44                              unsigned int ssize)
45 {
46         unsigned int blks;
47         unsigned int first, second;
48
49         blks = 1;
50         first = (sdp->sd_sb.sb_bsize - sizeof(struct gfs2_log_descriptor)) / ssize;
51
52         if (nstruct > first) {
53                 second = (sdp->sd_sb.sb_bsize -
54                           sizeof(struct gfs2_meta_header)) / ssize;
55                 blks += DIV_ROUND_UP(nstruct - first, second);
56         }
57
58         return blks;
59 }
60
61 /**
62  * gfs2_ail1_start_one - Start I/O on a part of the AIL
63  * @sdp: the filesystem
64  * @tr: the part of the AIL
65  *
66  */
67
68 static void gfs2_ail1_start_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
69 {
70         struct gfs2_bufdata *bd, *s;
71         struct buffer_head *bh;
72         int retry;
73
74         BUG_ON(!spin_is_locked(&sdp->sd_log_lock));
75
76         do {
77                 retry = 0;
78
79                 list_for_each_entry_safe_reverse(bd, s, &ai->ai_ail1_list,
80                                                  bd_ail_st_list) {
81                         bh = bd->bd_bh;
82
83                         gfs2_assert(sdp, bd->bd_ail == ai);
84
85                         if (!buffer_busy(bh)) {
86                                 if (!buffer_uptodate(bh)) {
87                                         gfs2_log_unlock(sdp);
88                                         gfs2_io_error_bh(sdp, bh);
89                                         gfs2_log_lock(sdp);
90                                 }
91                                 list_move(&bd->bd_ail_st_list, &ai->ai_ail2_list);
92                                 continue;
93                         }
94
95                         if (!buffer_dirty(bh))
96                                 continue;
97
98                         list_move(&bd->bd_ail_st_list, &ai->ai_ail1_list);
99
100                         gfs2_log_unlock(sdp);
101                         wait_on_buffer(bh);
102                         ll_rw_block(WRITE, 1, &bh);
103                         gfs2_log_lock(sdp);
104
105                         retry = 1;
106                         break;
107                 }
108         } while (retry);
109 }
110
111 /**
112  * gfs2_ail1_empty_one - Check whether or not a trans in the AIL has been synced
113  * @sdp: the filesystem
114  * @ai: the AIL entry
115  *
116  */
117
118 static int gfs2_ail1_empty_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai, int flags)
119 {
120         struct gfs2_bufdata *bd, *s;
121         struct buffer_head *bh;
122
123         list_for_each_entry_safe_reverse(bd, s, &ai->ai_ail1_list,
124                                          bd_ail_st_list) {
125                 bh = bd->bd_bh;
126
127                 gfs2_assert(sdp, bd->bd_ail == ai);
128
129                 if (buffer_busy(bh)) {
130                         if (flags & DIO_ALL)
131                                 continue;
132                         else
133                                 break;
134                 }
135
136                 if (!buffer_uptodate(bh))
137                         gfs2_io_error_bh(sdp, bh);
138
139                 list_move(&bd->bd_ail_st_list, &ai->ai_ail2_list);
140         }
141
142         return list_empty(&ai->ai_ail1_list);
143 }
144
145 void gfs2_ail1_start(struct gfs2_sbd *sdp, int flags)
146 {
147         struct list_head *head = &sdp->sd_ail1_list;
148         u64 sync_gen;
149         struct list_head *first;
150         struct gfs2_ail *first_ai, *ai, *tmp;
151         int done = 0;
152
153         gfs2_log_lock(sdp);
154         if (list_empty(head)) {
155                 gfs2_log_unlock(sdp);
156                 return;
157         }
158         sync_gen = sdp->sd_ail_sync_gen++;
159
160         first = head->prev;
161         first_ai = list_entry(first, struct gfs2_ail, ai_list);
162         first_ai->ai_sync_gen = sync_gen;
163         gfs2_ail1_start_one(sdp, first_ai); /* This may drop log lock */
164
165         if (flags & DIO_ALL)
166                 first = NULL;
167
168         while(!done) {
169                 if (first && (head->prev != first ||
170                               gfs2_ail1_empty_one(sdp, first_ai, 0)))
171                         break;
172
173                 done = 1;
174                 list_for_each_entry_safe_reverse(ai, tmp, head, ai_list) {
175                         if (ai->ai_sync_gen >= sync_gen)
176                                 continue;
177                         ai->ai_sync_gen = sync_gen;
178                         gfs2_ail1_start_one(sdp, ai); /* This may drop log lock */
179                         done = 0;
180                         break;
181                 }
182         }
183
184         gfs2_log_unlock(sdp);
185 }
186
187 int gfs2_ail1_empty(struct gfs2_sbd *sdp, int flags)
188 {
189         struct gfs2_ail *ai, *s;
190         int ret;
191
192         gfs2_log_lock(sdp);
193
194         list_for_each_entry_safe_reverse(ai, s, &sdp->sd_ail1_list, ai_list) {
195                 if (gfs2_ail1_empty_one(sdp, ai, flags))
196                         list_move(&ai->ai_list, &sdp->sd_ail2_list);
197                 else if (!(flags & DIO_ALL))
198                         break;
199         }
200
201         ret = list_empty(&sdp->sd_ail1_list);
202
203         gfs2_log_unlock(sdp);
204
205         return ret;
206 }
207
208
209 /**
210  * gfs2_ail2_empty_one - Check whether or not a trans in the AIL has been synced
211  * @sdp: the filesystem
212  * @ai: the AIL entry
213  *
214  */
215
216 static void gfs2_ail2_empty_one(struct gfs2_sbd *sdp, struct gfs2_ail *ai)
217 {
218         struct list_head *head = &ai->ai_ail2_list;
219         struct gfs2_bufdata *bd;
220
221         while (!list_empty(head)) {
222                 bd = list_entry(head->prev, struct gfs2_bufdata,
223                                 bd_ail_st_list);
224                 gfs2_assert(sdp, bd->bd_ail == ai);
225                 bd->bd_ail = NULL;
226                 list_del(&bd->bd_ail_st_list);
227                 list_del(&bd->bd_ail_gl_list);
228                 atomic_dec(&bd->bd_gl->gl_ail_count);
229                 brelse(bd->bd_bh);
230         }
231 }
232
233 static void ail2_empty(struct gfs2_sbd *sdp, unsigned int new_tail)
234 {
235         struct gfs2_ail *ai, *safe;
236         unsigned int old_tail = sdp->sd_log_tail;
237         int wrap = (new_tail < old_tail);
238         int a, b, rm;
239
240         gfs2_log_lock(sdp);
241
242         list_for_each_entry_safe(ai, safe, &sdp->sd_ail2_list, ai_list) {
243                 a = (old_tail <= ai->ai_first);
244                 b = (ai->ai_first < new_tail);
245                 rm = (wrap) ? (a || b) : (a && b);
246                 if (!rm)
247                         continue;
248
249                 gfs2_ail2_empty_one(sdp, ai);
250                 list_del(&ai->ai_list);
251                 gfs2_assert_warn(sdp, list_empty(&ai->ai_ail1_list));
252                 gfs2_assert_warn(sdp, list_empty(&ai->ai_ail2_list));
253                 kfree(ai);
254         }
255
256         gfs2_log_unlock(sdp);
257 }
258
259 /**
260  * gfs2_log_reserve - Make a log reservation
261  * @sdp: The GFS2 superblock
262  * @blks: The number of blocks to reserve
263  *
264  * Returns: errno
265  */
266
267 int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks)
268 {
269         unsigned int try = 0;
270
271         if (gfs2_assert_warn(sdp, blks) ||
272             gfs2_assert_warn(sdp, blks <= sdp->sd_jdesc->jd_blocks))
273                 return -EINVAL;
274
275         mutex_lock(&sdp->sd_log_reserve_mutex);
276         gfs2_log_lock(sdp);
277         while(sdp->sd_log_blks_free <= blks) {
278                 gfs2_log_unlock(sdp);
279                 gfs2_ail1_empty(sdp, 0);
280                 gfs2_log_flush(sdp, NULL);
281
282                 if (try++)
283                         gfs2_ail1_start(sdp, 0);
284                 gfs2_log_lock(sdp);
285         }
286         sdp->sd_log_blks_free -= blks;
287         gfs2_log_unlock(sdp);
288         mutex_unlock(&sdp->sd_log_reserve_mutex);
289
290         down_read(&sdp->sd_log_flush_lock);
291
292         return 0;
293 }
294
295 /**
296  * gfs2_log_release - Release a given number of log blocks
297  * @sdp: The GFS2 superblock
298  * @blks: The number of blocks
299  *
300  */
301
302 void gfs2_log_release(struct gfs2_sbd *sdp, unsigned int blks)
303 {
304
305         gfs2_log_lock(sdp);
306         sdp->sd_log_blks_free += blks;
307         gfs2_assert_withdraw(sdp,
308                              sdp->sd_log_blks_free <= sdp->sd_jdesc->jd_blocks);
309         gfs2_log_unlock(sdp);
310         up_read(&sdp->sd_log_flush_lock);
311 }
312
313 static u64 log_bmap(struct gfs2_sbd *sdp, unsigned int lbn)
314 {
315         int error;
316         struct buffer_head bh_map;
317
318         error = gfs2_block_map(sdp->sd_jdesc->jd_inode, lbn, 0, &bh_map, 1);
319         if (error || !bh_map.b_blocknr)
320                 printk(KERN_INFO "error=%d, dbn=%llu lbn=%u", error, bh_map.b_blocknr, lbn);
321         gfs2_assert_withdraw(sdp, !error && bh_map.b_blocknr);
322
323         return bh_map.b_blocknr;
324 }
325
326 /**
327  * log_distance - Compute distance between two journal blocks
328  * @sdp: The GFS2 superblock
329  * @newer: The most recent journal block of the pair
330  * @older: The older journal block of the pair
331  *
332  *   Compute the distance (in the journal direction) between two
333  *   blocks in the journal
334  *
335  * Returns: the distance in blocks
336  */
337
338 static inline unsigned int log_distance(struct gfs2_sbd *sdp, unsigned int newer,
339                                         unsigned int older)
340 {
341         int dist;
342
343         dist = newer - older;
344         if (dist < 0)
345                 dist += sdp->sd_jdesc->jd_blocks;
346
347         return dist;
348 }
349
350 static unsigned int current_tail(struct gfs2_sbd *sdp)
351 {
352         struct gfs2_ail *ai;
353         unsigned int tail;
354
355         gfs2_log_lock(sdp);
356
357         if (list_empty(&sdp->sd_ail1_list)) {
358                 tail = sdp->sd_log_head;
359         } else {
360                 ai = list_entry(sdp->sd_ail1_list.prev, struct gfs2_ail, ai_list);
361                 tail = ai->ai_first;
362         }
363
364         gfs2_log_unlock(sdp);
365
366         return tail;
367 }
368
369 static inline void log_incr_head(struct gfs2_sbd *sdp)
370 {
371         if (sdp->sd_log_flush_head == sdp->sd_log_tail)
372                 gfs2_assert_withdraw(sdp, sdp->sd_log_flush_head == sdp->sd_log_head);
373
374         if (++sdp->sd_log_flush_head == sdp->sd_jdesc->jd_blocks) {
375                 sdp->sd_log_flush_head = 0;
376                 sdp->sd_log_flush_wrapped = 1;
377         }
378 }
379
380 /**
381  * gfs2_log_get_buf - Get and initialize a buffer to use for log control data
382  * @sdp: The GFS2 superblock
383  *
384  * Returns: the buffer_head
385  */
386
387 struct buffer_head *gfs2_log_get_buf(struct gfs2_sbd *sdp)
388 {
389         u64 blkno = log_bmap(sdp, sdp->sd_log_flush_head);
390         struct gfs2_log_buf *lb;
391         struct buffer_head *bh;
392
393         lb = kzalloc(sizeof(struct gfs2_log_buf), GFP_NOFS | __GFP_NOFAIL);
394         list_add(&lb->lb_list, &sdp->sd_log_flush_list);
395
396         bh = lb->lb_bh = sb_getblk(sdp->sd_vfs, blkno);
397         lock_buffer(bh);
398         memset(bh->b_data, 0, bh->b_size);
399         set_buffer_uptodate(bh);
400         clear_buffer_dirty(bh);
401         unlock_buffer(bh);
402
403         log_incr_head(sdp);
404
405         return bh;
406 }
407
408 /**
409  * gfs2_log_fake_buf - Build a fake buffer head to write metadata buffer to log
410  * @sdp: the filesystem
411  * @data: the data the buffer_head should point to
412  *
413  * Returns: the log buffer descriptor
414  */
415
416 struct buffer_head *gfs2_log_fake_buf(struct gfs2_sbd *sdp,
417                                       struct buffer_head *real)
418 {
419         u64 blkno = log_bmap(sdp, sdp->sd_log_flush_head);
420         struct gfs2_log_buf *lb;
421         struct buffer_head *bh;
422
423         lb = kzalloc(sizeof(struct gfs2_log_buf), GFP_NOFS | __GFP_NOFAIL);
424         list_add(&lb->lb_list, &sdp->sd_log_flush_list);
425         lb->lb_real = real;
426
427         bh = lb->lb_bh = alloc_buffer_head(GFP_NOFS | __GFP_NOFAIL);
428         atomic_set(&bh->b_count, 1);
429         bh->b_state = (1 << BH_Mapped) | (1 << BH_Uptodate);
430         set_bh_page(bh, real->b_page, bh_offset(real));
431         bh->b_blocknr = blkno;
432         bh->b_size = sdp->sd_sb.sb_bsize;
433         bh->b_bdev = sdp->sd_vfs->s_bdev;
434
435         log_incr_head(sdp);
436
437         return bh;
438 }
439
440 static void log_pull_tail(struct gfs2_sbd *sdp, unsigned int new_tail, int pull)
441 {
442         unsigned int dist = log_distance(sdp, new_tail, sdp->sd_log_tail);
443
444         ail2_empty(sdp, new_tail);
445
446         gfs2_log_lock(sdp);
447         sdp->sd_log_blks_free += dist - (pull ? 1 : 0);
448         gfs2_assert_withdraw(sdp, sdp->sd_log_blks_free <= sdp->sd_jdesc->jd_blocks);
449         gfs2_log_unlock(sdp);
450
451         sdp->sd_log_tail = new_tail;
452 }
453
454 /**
455  * log_write_header - Get and initialize a journal header buffer
456  * @sdp: The GFS2 superblock
457  *
458  * Returns: the initialized log buffer descriptor
459  */
460
461 static void log_write_header(struct gfs2_sbd *sdp, u32 flags, int pull)
462 {
463         u64 blkno = log_bmap(sdp, sdp->sd_log_flush_head);
464         struct buffer_head *bh;
465         struct gfs2_log_header *lh;
466         unsigned int tail;
467         u32 hash;
468
469         bh = sb_getblk(sdp->sd_vfs, blkno);
470         lock_buffer(bh);
471         memset(bh->b_data, 0, bh->b_size);
472         set_buffer_uptodate(bh);
473         clear_buffer_dirty(bh);
474         unlock_buffer(bh);
475
476         gfs2_ail1_empty(sdp, 0);
477         tail = current_tail(sdp);
478
479         lh = (struct gfs2_log_header *)bh->b_data;
480         memset(lh, 0, sizeof(struct gfs2_log_header));
481         lh->lh_header.mh_magic = cpu_to_be32(GFS2_MAGIC);
482         lh->lh_header.mh_type = cpu_to_be32(GFS2_METATYPE_LH);
483         lh->lh_header.mh_format = cpu_to_be32(GFS2_FORMAT_LH);
484         lh->lh_sequence = cpu_to_be64(sdp->sd_log_sequence++);
485         lh->lh_flags = cpu_to_be32(flags);
486         lh->lh_tail = cpu_to_be32(tail);
487         lh->lh_blkno = cpu_to_be32(sdp->sd_log_flush_head);
488         hash = gfs2_disk_hash(bh->b_data, sizeof(struct gfs2_log_header));
489         lh->lh_hash = cpu_to_be32(hash);
490
491         set_buffer_dirty(bh);
492         if (sync_dirty_buffer(bh))
493                 gfs2_io_error_bh(sdp, bh);
494         brelse(bh);
495
496         if (sdp->sd_log_tail != tail)
497                 log_pull_tail(sdp, tail, pull);
498         else
499                 gfs2_assert_withdraw(sdp, !pull);
500
501         sdp->sd_log_idle = (tail == sdp->sd_log_flush_head);
502         log_incr_head(sdp);
503 }
504
505 static void log_flush_commit(struct gfs2_sbd *sdp)
506 {
507         struct list_head *head = &sdp->sd_log_flush_list;
508         struct gfs2_log_buf *lb;
509         struct buffer_head *bh;
510
511         while (!list_empty(head)) {
512                 lb = list_entry(head->next, struct gfs2_log_buf, lb_list);
513                 list_del(&lb->lb_list);
514                 bh = lb->lb_bh;
515
516                 wait_on_buffer(bh);
517                 if (!buffer_uptodate(bh))
518                         gfs2_io_error_bh(sdp, bh);
519                 if (lb->lb_real) {
520                         while (atomic_read(&bh->b_count) != 1)  /* Grrrr... */
521                                 schedule();
522                         free_buffer_head(bh);
523                 } else
524                         brelse(bh);
525                 kfree(lb);
526         }
527
528         log_write_header(sdp, 0, 0);
529 }
530
531 /**
532  * gfs2_log_flush - flush incore transaction(s)
533  * @sdp: the filesystem
534  * @gl: The glock structure to flush.  If NULL, flush the whole incore log
535  *
536  */
537
538 void gfs2_log_flush(struct gfs2_sbd *sdp, struct gfs2_glock *gl)
539 {
540         struct gfs2_ail *ai;
541
542         down_write(&sdp->sd_log_flush_lock);
543
544         if (gl) {
545                 gfs2_log_lock(sdp);
546                 if (list_empty(&gl->gl_le.le_list)) {
547                         gfs2_log_unlock(sdp);
548                         up_write(&sdp->sd_log_flush_lock);
549                         return;
550                 }
551                 gfs2_log_unlock(sdp);
552         }
553
554         ai = kzalloc(sizeof(struct gfs2_ail), GFP_NOFS | __GFP_NOFAIL);
555         INIT_LIST_HEAD(&ai->ai_ail1_list);
556         INIT_LIST_HEAD(&ai->ai_ail2_list);
557
558         gfs2_assert_withdraw(sdp, sdp->sd_log_num_buf == sdp->sd_log_commited_buf);
559         gfs2_assert_withdraw(sdp,
560                         sdp->sd_log_num_revoke == sdp->sd_log_commited_revoke);
561
562         sdp->sd_log_flush_head = sdp->sd_log_head;
563         sdp->sd_log_flush_wrapped = 0;
564         ai->ai_first = sdp->sd_log_flush_head;
565
566         lops_before_commit(sdp);
567         if (!list_empty(&sdp->sd_log_flush_list))
568                 log_flush_commit(sdp);
569         else if (sdp->sd_log_tail != current_tail(sdp) && !sdp->sd_log_idle)
570                 log_write_header(sdp, 0, PULL);
571         lops_after_commit(sdp, ai);
572
573         gfs2_log_lock(sdp);
574         sdp->sd_log_head = sdp->sd_log_flush_head;
575         sdp->sd_log_blks_free -= sdp->sd_log_num_hdrs;
576         sdp->sd_log_blks_reserved = 0;
577         sdp->sd_log_commited_buf = 0;
578         sdp->sd_log_num_hdrs = 0;
579         sdp->sd_log_commited_revoke = 0;
580
581         if (!list_empty(&ai->ai_ail1_list)) {
582                 list_add(&ai->ai_list, &sdp->sd_ail1_list);
583                 ai = NULL;
584         }
585         gfs2_log_unlock(sdp);
586
587         sdp->sd_vfs->s_dirt = 0;
588         up_write(&sdp->sd_log_flush_lock);
589
590         kfree(ai);
591 }
592
593 static void log_refund(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
594 {
595         unsigned int reserved = 0;
596         unsigned int old;
597
598         gfs2_log_lock(sdp);
599
600         sdp->sd_log_commited_buf += tr->tr_num_buf_new - tr->tr_num_buf_rm;
601         gfs2_assert_withdraw(sdp, ((int)sdp->sd_log_commited_buf) >= 0);
602         sdp->sd_log_commited_revoke += tr->tr_num_revoke - tr->tr_num_revoke_rm;
603         gfs2_assert_withdraw(sdp, ((int)sdp->sd_log_commited_revoke) >= 0);
604
605         if (sdp->sd_log_commited_buf)
606                 reserved += sdp->sd_log_commited_buf;
607         if (sdp->sd_log_commited_revoke)
608                 reserved += gfs2_struct2blk(sdp, sdp->sd_log_commited_revoke,
609                                             sizeof(u64));
610         if (reserved)
611                 reserved++;
612
613         old = sdp->sd_log_blks_free;
614         sdp->sd_log_blks_free += tr->tr_reserved -
615                                  (reserved - sdp->sd_log_blks_reserved);
616
617         gfs2_assert_withdraw(sdp, sdp->sd_log_blks_free >= old);
618         gfs2_assert_withdraw(sdp,
619                              sdp->sd_log_blks_free <= sdp->sd_jdesc->jd_blocks +
620                              sdp->sd_log_num_hdrs);
621
622         sdp->sd_log_blks_reserved = reserved;
623
624         gfs2_log_unlock(sdp);
625 }
626
627 /**
628  * gfs2_log_commit - Commit a transaction to the log
629  * @sdp: the filesystem
630  * @tr: the transaction
631  *
632  * Returns: errno
633  */
634
635 void gfs2_log_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
636 {
637         log_refund(sdp, tr);
638         lops_incore_commit(sdp, tr);
639
640         sdp->sd_vfs->s_dirt = 1;
641         up_read(&sdp->sd_log_flush_lock);
642
643         gfs2_log_lock(sdp);
644         if (sdp->sd_log_num_buf > gfs2_tune_get(sdp, gt_incore_log_blocks)) {
645                 gfs2_log_unlock(sdp);
646                 gfs2_log_flush(sdp, NULL);
647         } else {
648                 gfs2_log_unlock(sdp);
649         }
650 }
651
652 /**
653  * gfs2_log_shutdown - write a shutdown header into a journal
654  * @sdp: the filesystem
655  *
656  */
657
658 void gfs2_log_shutdown(struct gfs2_sbd *sdp)
659 {
660         down_write(&sdp->sd_log_flush_lock);
661
662         gfs2_assert_withdraw(sdp, !sdp->sd_log_blks_reserved);
663         gfs2_assert_withdraw(sdp, !sdp->sd_log_num_gl);
664         gfs2_assert_withdraw(sdp, !sdp->sd_log_num_buf);
665         gfs2_assert_withdraw(sdp, !sdp->sd_log_num_jdata);
666         gfs2_assert_withdraw(sdp, !sdp->sd_log_num_revoke);
667         gfs2_assert_withdraw(sdp, !sdp->sd_log_num_rg);
668         gfs2_assert_withdraw(sdp, !sdp->sd_log_num_databuf);
669         gfs2_assert_withdraw(sdp, !sdp->sd_log_num_hdrs);
670         gfs2_assert_withdraw(sdp, list_empty(&sdp->sd_ail1_list));
671
672         sdp->sd_log_flush_head = sdp->sd_log_head;
673         sdp->sd_log_flush_wrapped = 0;
674
675         log_write_header(sdp, GFS2_LOG_HEAD_UNMOUNT, 0);
676
677         gfs2_assert_warn(sdp, sdp->sd_log_blks_free == sdp->sd_jdesc->jd_blocks);
678         gfs2_assert_warn(sdp, sdp->sd_log_head == sdp->sd_log_tail);
679         gfs2_assert_warn(sdp, list_empty(&sdp->sd_ail2_list));
680
681         sdp->sd_log_head = sdp->sd_log_flush_head;
682         sdp->sd_log_tail = sdp->sd_log_head;
683
684         up_write(&sdp->sd_log_flush_lock);
685 }
686