fs/gfs2/log.c

   1 /*
   2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   3  * Copyright (C) 2004-2005 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 v.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 <asm/semaphore.h>
  16
  17 #include "gfs2.h"
  18 #include "bmap.h"
  19 #include "glock.h"
  20 #include "log.h"
  21 #include "lops.h"
  22 #include "meta_io.h"
  23
  24 #define PULL 1
  25
  26 static void do_lock_wait(struct gfs2_sbd *sdp, wait_queue_head_t *wq,
  27                          atomic_t *a)
  28 {
  29         wait_event(*wq, atomic_read(a) ? 0 : 1);
  30 }
  31
  32 static void lock_for_trans(struct gfs2_sbd *sdp)
  33 {
  34         do_lock_wait(sdp, &sdp->sd_log_trans_wq, &sdp->sd_log_flush_count);
  35         atomic_inc(&sdp->sd_log_trans_count);
  36 }
  37
  38 static void unlock_from_trans(struct gfs2_sbd *sdp)
  39 {
  40         gfs2_assert_warn(sdp, atomic_read(&sdp->sd_log_trans_count));
  41         if (atomic_dec_and_test(&sdp->sd_log_trans_count))
  42                 wake_up(&sdp->sd_log_flush_wq);
  43 }
  44
  45 static void gfs2_lock_for_flush(struct gfs2_sbd *sdp)
  46 {
  47         atomic_inc(&sdp->sd_log_flush_count);
  48         do_lock_wait(sdp, &sdp->sd_log_flush_wq, &sdp->sd_log_trans_count);
  49 }
  50
  51 static void gfs2_unlock_from_flush(struct gfs2_sbd *sdp)
  52 {
  53         gfs2_assert_warn(sdp, atomic_read(&sdp->sd_log_flush_count));
  54         if (atomic_dec_and_test(&sdp->sd_log_flush_count))
  55                 wake_up(&sdp->sd_log_trans_wq);
  56 }
  57
  58 /**
  59  * gfs2_struct2blk - compute stuff
  60  * @sdp: the filesystem
  61  * @nstruct: the number of structures
  62  * @ssize: the size of the structures
  63  *
  64  * Compute the number of log descriptor blocks needed to hold a certain number
  65  * of structures of a certain size.
  66  *
  67  * Returns: the number of blocks needed (minimum is always 1)
  68  */
  69
  70 unsigned int gfs2_struct2blk(struct gfs2_sbd *sdp, unsigned int nstruct,
  71                              unsigned int ssize)
  72 {
  73         unsigned int blks;
  74         unsigned int first, second;
  75
  76         blks = 1;
  77         first = (sdp->sd_sb.sb_bsize - sizeof(struct gfs2_log_descriptor)) / ssize;
  78
  79         if (nstruct > first) {
  80                 second = (sdp->sd_sb.sb_bsize - sizeof(struct gfs2_meta_header)) / ssize;
  81                 blks += DIV_RU(nstruct - first, second);
  82         }
  83
  84         return blks;
  85 }
  86
  87 void gfs2_ail1_start(struct gfs2_sbd *sdp, int flags)
  88 {
  89         struct list_head *head = &sdp->sd_ail1_list;
  90         uint64_t sync_gen;
  91         struct list_head *first, *tmp;
  92         struct gfs2_ail *first_ai, *ai;
  93
  94         gfs2_log_lock(sdp);
  95         if (list_empty(head)) {
  96                 gfs2_log_unlock(sdp);
  97                 return;
  98         }
  99         sync_gen = sdp->sd_ail_sync_gen++;
 100
 101         first = head->prev;
 102         first_ai = list_entry(first, struct gfs2_ail, ai_list);
 103         first_ai->ai_sync_gen = sync_gen;
 104         gfs2_ail1_start_one(sdp, first_ai);
 105
 106         if (flags & DIO_ALL)
 107                 first = NULL;
 108
 109         for (;;) {
 110                 if (first &&
 111                     (head->prev != first ||
 112                      gfs2_ail1_empty_one(sdp, first_ai, 0)))
 113                         break;
 114
 115                 for (tmp = head->prev; tmp != head; tmp = tmp->prev) {
 116                         ai = list_entry(tmp, struct gfs2_ail, ai_list);
 117                         if (ai->ai_sync_gen >= sync_gen)
 118                                 continue;
 119                         ai->ai_sync_gen = sync_gen;
 120                         gfs2_ail1_start_one(sdp, ai);
 121                         break;
 122                 }
 123
 124                 if (tmp == head)
 125                         break;
 126         }
 127
 128         gfs2_log_unlock(sdp);
 129 }
 130
 131 int gfs2_ail1_empty(struct gfs2_sbd *sdp, int flags)
 132 {
 133         struct gfs2_ail *ai, *s;
 134         int ret;
 135
 136         gfs2_log_lock(sdp);
 137
 138         list_for_each_entry_safe_reverse(ai, s, &sdp->sd_ail1_list, ai_list) {
 139                 if (gfs2_ail1_empty_one(sdp, ai, flags))
 140                         list_move(&ai->ai_list, &sdp->sd_ail2_list);
 141                 else if (!(flags & DIO_ALL))
 142                         break;
 143         }
 144
 145         ret = list_empty(&sdp->sd_ail1_list);
 146
 147         gfs2_log_unlock(sdp);
 148
 149         return ret;
 150 }
 151
 152 static void ail2_empty(struct gfs2_sbd *sdp, unsigned int new_tail)
 153 {
 154         struct gfs2_ail *ai, *safe;
 155         unsigned int old_tail = sdp->sd_log_tail;
 156         int wrap = (new_tail < old_tail);
 157         int a, b, rm;
 158
 159         gfs2_log_lock(sdp);
 160
 161         list_for_each_entry_safe(ai, safe, &sdp->sd_ail2_list, ai_list) {
 162                 a = (old_tail <= ai->ai_first);
 163                 b = (ai->ai_first < new_tail);
 164                 rm = (wrap) ? (a || b) : (a && b);
 165                 if (!rm)
 166                         continue;
 167
 168                 gfs2_ail2_empty_one(sdp, ai);
 169                 list_del(&ai->ai_list);
 170                 gfs2_assert_warn(sdp, list_empty(&ai->ai_ail1_list));
 171                 gfs2_assert_warn(sdp, list_empty(&ai->ai_ail2_list));
 172                 kfree(ai);
 173         }
 174
 175         gfs2_log_unlock(sdp);
 176 }
 177
 178 /**
 179  * gfs2_log_reserve - Make a log reservation
 180  * @sdp: The GFS2 superblock
 181  * @blks: The number of blocks to reserve
 182  *
 183  * Returns: errno
 184  */
 185
 186 int gfs2_log_reserve(struct gfs2_sbd *sdp, unsigned int blks)
 187 {
 188         LIST_HEAD(list);
 189         unsigned int try = 0;
 190
 191         if (gfs2_assert_warn(sdp, blks) ||
 192             gfs2_assert_warn(sdp, blks <= sdp->sd_jdesc->jd_blocks))
 193                 return -EINVAL;
 194
 195         for (;;) {
 196                 gfs2_log_lock(sdp);
 197                 if (list_empty(&list)) {
 198                         list_add_tail(&list, &sdp->sd_log_blks_list);
 199                         while (sdp->sd_log_blks_list.next != &list) {
 200                                 DECLARE_WAITQUEUE(__wait_chan, current);
 201                                 set_current_state(TASK_UNINTERRUPTIBLE);
 202                                 add_wait_queue(&sdp->sd_log_blks_wait,
 203                                                &__wait_chan);
 204                                 gfs2_log_unlock(sdp);
 205                                 schedule();
 206                                 gfs2_log_lock(sdp);
 207                                 remove_wait_queue(&sdp->sd_log_blks_wait,
 208                                                   &__wait_chan);
 209                                 set_current_state(TASK_RUNNING);
 210                         }
 211                 }
 212                 /* Never give away the last block so we can
 213                    always pull the tail if we need to. */
 214                 if (sdp->sd_log_blks_free > blks) {
 215                         sdp->sd_log_blks_free -= blks;
 216                         list_del(&list);
 217                         gfs2_log_unlock(sdp);
 218                         wake_up(&sdp->sd_log_blks_wait);
 219                         break;
 220                 }
 221
 222                 gfs2_log_unlock(sdp);
 223                 gfs2_ail1_empty(sdp, 0);
 224                 gfs2_log_flush(sdp);
 225
 226                 if (try++)
 227                         gfs2_ail1_start(sdp, 0);
 228         }
 229         lock_for_trans(sdp);
 230
 231         return 0;
 232 }
 233
 234 /**
 235  * gfs2_log_release - Release a given number of log blocks
 236  * @sdp: The GFS2 superblock
 237  * @blks: The number of blocks
 238  *
 239  */
 240
 241 void gfs2_log_release(struct gfs2_sbd *sdp, unsigned int blks)
 242 {
 243         unlock_from_trans(sdp);
 244
 245         gfs2_log_lock(sdp);
 246         sdp->sd_log_blks_free += blks;
 247         gfs2_assert_withdraw(sdp,
 248                              sdp->sd_log_blks_free <= sdp->sd_jdesc->jd_blocks);
 249         gfs2_log_unlock(sdp);
 250 }
 251
 252 static uint64_t log_bmap(struct gfs2_sbd *sdp, unsigned int lbn)
 253 {
 254         int new = 0;
 255         uint64_t dbn;
 256         int error;
 257
 258         error = gfs2_block_map(get_v2ip(sdp->sd_jdesc->jd_inode), lbn, &new, &dbn, NULL);
 259         gfs2_assert_withdraw(sdp, !error && dbn);
 260
 261         return dbn;
 262 }
 263
 264 /**
 265  * log_distance - Compute distance between two journal blocks
 266  * @sdp: The GFS2 superblock
 267  * @newer: The most recent journal block of the pair
 268  * @older: The older journal block of the pair
 269  *
 270  *   Compute the distance (in the journal direction) between two
 271  *   blocks in the journal
 272  *
 273  * Returns: the distance in blocks
 274  */
 275
 276 static inline unsigned int log_distance(struct gfs2_sbd *sdp,
 277                                         unsigned int newer,
 278                                         unsigned int older)
 279 {
 280         int dist;
 281
 282         dist = newer - older;
 283         if (dist < 0)
 284                 dist += sdp->sd_jdesc->jd_blocks;
 285
 286         return dist;
 287 }
 288
 289 static unsigned int current_tail(struct gfs2_sbd *sdp)
 290 {
 291         struct gfs2_ail *ai;
 292         unsigned int tail;
 293
 294         gfs2_log_lock(sdp);
 295
 296         if (list_empty(&sdp->sd_ail1_list))
 297                 tail = sdp->sd_log_head;
 298         else {
 299                 ai = list_entry(sdp->sd_ail1_list.prev,
 300                                 struct gfs2_ail, ai_list);
 301                 tail = ai->ai_first;
 302         }
 303
 304         gfs2_log_unlock(sdp);
 305
 306         return tail;
 307 }
 308
 309 static inline void log_incr_head(struct gfs2_sbd *sdp)
 310 {
 311         if (sdp->sd_log_flush_head == sdp->sd_log_tail)
 312                 gfs2_assert_withdraw(sdp,
 313                                 sdp->sd_log_flush_head == sdp->sd_log_head);
 314
 315         if (++sdp->sd_log_flush_head == sdp->sd_jdesc->jd_blocks) {
 316                 sdp->sd_log_flush_head = 0;
 317                 sdp->sd_log_flush_wrapped = 1;
 318         }
 319 }
 320
 321 /**
 322  * gfs2_log_get_buf - Get and initialize a buffer to use for log control data
 323  * @sdp: The GFS2 superblock
 324  *
 325  * Returns: the buffer_head
 326  */
 327
 328 struct buffer_head *gfs2_log_get_buf(struct gfs2_sbd *sdp)
 329 {
 330         uint64_t blkno = log_bmap(sdp, sdp->sd_log_flush_head);
 331         struct gfs2_log_buf *lb;
 332         struct buffer_head *bh;
 333
 334         lb = kzalloc(sizeof(struct gfs2_log_buf), GFP_NOFS | __GFP_NOFAIL);
 335         list_add(&lb->lb_list, &sdp->sd_log_flush_list);
 336
 337         bh = lb->lb_bh = sb_getblk(sdp->sd_vfs, blkno);
 338         lock_buffer(bh);
 339         memset(bh->b_data, 0, bh->b_size);
 340         set_buffer_uptodate(bh);
 341         clear_buffer_dirty(bh);
 342         unlock_buffer(bh);
 343
 344         log_incr_head(sdp);
 345
 346         return bh;
 347 }
 348
 349 /**
 350  * gfs2_log_fake_buf - Build a fake buffer head to write metadata buffer to log
 351  * @sdp: the filesystem
 352  * @data: the data the buffer_head should point to
 353  *
 354  * Returns: the log buffer descriptor
 355  */
 356
 357 struct buffer_head *gfs2_log_fake_buf(struct gfs2_sbd *sdp,
 358                                       struct buffer_head *real)
 359 {
 360         uint64_t blkno = log_bmap(sdp, sdp->sd_log_flush_head);
 361         struct gfs2_log_buf *lb;
 362         struct buffer_head *bh;
 363
 364         lb = kzalloc(sizeof(struct gfs2_log_buf), GFP_NOFS | __GFP_NOFAIL);
 365         list_add(&lb->lb_list, &sdp->sd_log_flush_list);
 366         lb->lb_real = real;
 367
 368         bh = lb->lb_bh = alloc_buffer_head(GFP_NOFS | __GFP_NOFAIL);
 369         atomic_set(&bh->b_count, 1);
 370         bh->b_state = (1 << BH_Mapped) | (1 << BH_Uptodate);
 371         set_bh_page(bh, real->b_page, bh_offset(real));
 372         bh->b_blocknr = blkno;
 373         bh->b_size = sdp->sd_sb.sb_bsize;
 374         bh->b_bdev = sdp->sd_vfs->s_bdev;
 375
 376         log_incr_head(sdp);
 377
 378         return bh;
 379 }
 380
 381 static void log_pull_tail(struct gfs2_sbd *sdp, unsigned int new_tail, int pull)
 382 {
 383         unsigned int dist = log_distance(sdp, new_tail, sdp->sd_log_tail);
 384
 385         ail2_empty(sdp, new_tail);
 386
 387         gfs2_log_lock(sdp);
 388         sdp->sd_log_blks_free += dist - ((pull) ? 1 : 0);
 389         gfs2_assert_withdraw(sdp,
 390                              sdp->sd_log_blks_free <= sdp->sd_jdesc->jd_blocks);
 391         gfs2_log_unlock(sdp);
 392
 393         sdp->sd_log_tail = new_tail;
 394 }
 395
 396 /**
 397  * log_write_header - Get and initialize a journal header buffer
 398  * @sdp: The GFS2 superblock
 399  *
 400  * Returns: the initialized log buffer descriptor
 401  */
 402
 403 static void log_write_header(struct gfs2_sbd *sdp, uint32_t flags, int pull)
 404 {
 405         uint64_t blkno = log_bmap(sdp, sdp->sd_log_flush_head);
 406         struct buffer_head *bh;
 407         struct gfs2_log_header *lh;
 408         unsigned int tail;
 409         uint32_t hash;
 410
 411         bh = sb_getblk(sdp->sd_vfs, blkno);
 412         lock_buffer(bh);
 413         memset(bh->b_data, 0, bh->b_size);
 414         set_buffer_uptodate(bh);
 415         clear_buffer_dirty(bh);
 416         unlock_buffer(bh);
 417
 418         gfs2_ail1_empty(sdp, 0);
 419         tail = current_tail(sdp);
 420
 421         lh = (struct gfs2_log_header *)bh->b_data;
 422         memset(lh, 0, sizeof(struct gfs2_log_header));
 423         lh->lh_header.mh_magic = cpu_to_be32(GFS2_MAGIC);
 424         lh->lh_header.mh_type = cpu_to_be16(GFS2_METATYPE_LH);
 425         lh->lh_header.mh_format = cpu_to_be16(GFS2_FORMAT_LH);
 426         lh->lh_sequence = be64_to_cpu(sdp->sd_log_sequence++);
 427         lh->lh_flags = be32_to_cpu(flags);
 428         lh->lh_tail = be32_to_cpu(tail);
 429         lh->lh_blkno = be32_to_cpu(sdp->sd_log_flush_head);
 430         hash = gfs2_disk_hash(bh->b_data, sizeof(struct gfs2_log_header));
 431         lh->lh_hash = cpu_to_be32(hash);
 432
 433         set_buffer_dirty(bh);
 434         if (sync_dirty_buffer(bh))
 435                 gfs2_io_error_bh(sdp, bh);
 436         brelse(bh);
 437
 438         if (sdp->sd_log_tail != tail)
 439                 log_pull_tail(sdp, tail, pull);
 440         else
 441                 gfs2_assert_withdraw(sdp, !pull);
 442
 443         sdp->sd_log_idle = (tail == sdp->sd_log_flush_head);
 444         log_incr_head(sdp);
 445 }
 446
 447 static void log_flush_commit(struct gfs2_sbd *sdp)
 448 {
 449         struct list_head *head = &sdp->sd_log_flush_list;
 450         struct gfs2_log_buf *lb;
 451         struct buffer_head *bh;
 452         unsigned int d;
 453
 454         d = log_distance(sdp, sdp->sd_log_flush_head, sdp->sd_log_head);
 455
 456         gfs2_assert_withdraw(sdp, d + 1 == sdp->sd_log_blks_reserved);
 457
 458         while (!list_empty(head)) {
 459                 lb = list_entry(head->next, struct gfs2_log_buf, lb_list);
 460                 list_del(&lb->lb_list);
 461                 bh = lb->lb_bh;
 462
 463                 wait_on_buffer(bh);
 464                 if (!buffer_uptodate(bh))
 465                         gfs2_io_error_bh(sdp, bh);
 466                 if (lb->lb_real) {
 467                         while (atomic_read(&bh->b_count) != 1)  /* Grrrr... */
 468                                 schedule();
 469                         free_buffer_head(bh);
 470                 } else
 471                         brelse(bh);
 472                 kfree(lb);
 473         }
 474
 475         log_write_header(sdp, 0, 0);
 476 }
 477
 478 /**
 479  * gfs2_log_flush_i - flush incore transaction(s)
 480  * @sdp: the filesystem
 481  * @gl: The glock structure to flush.  If NULL, flush the whole incore log
 482  *
 483  */
 484
 485 void gfs2_log_flush_i(struct gfs2_sbd *sdp, struct gfs2_glock *gl)
 486 {
 487         struct gfs2_ail *ai;
 488
 489         ai = kzalloc(sizeof(struct gfs2_ail), GFP_NOFS | __GFP_NOFAIL);
 490         INIT_LIST_HEAD(&ai->ai_ail1_list);
 491         INIT_LIST_HEAD(&ai->ai_ail2_list);
 492         gfs2_lock_for_flush(sdp);
 493
 494         if (gl) {
 495                 gfs2_log_lock(sdp);
 496                 if (list_empty(&gl->gl_le.le_list)) {
 497                         gfs2_log_unlock(sdp);
 498                         gfs2_unlock_from_flush(sdp);
 499                         kfree(ai);
 500                         return;
 501                 }
 502                 gfs2_log_unlock(sdp);
 503         }
 504
 505         mutex_lock(&sdp->sd_log_flush_lock);
 506
 507         gfs2_assert_withdraw(sdp,
 508                         sdp->sd_log_num_buf == sdp->sd_log_commited_buf);
 509         gfs2_assert_withdraw(sdp,
 510                         sdp->sd_log_num_revoke == sdp->sd_log_commited_revoke);
 511
 512         sdp->sd_log_flush_head = sdp->sd_log_head;
 513         sdp->sd_log_flush_wrapped = 0;
 514         ai->ai_first = sdp->sd_log_flush_head;
 515
 516         lops_before_commit(sdp);
 517         if (!list_empty(&sdp->sd_log_flush_list))
 518                 log_flush_commit(sdp);
 519         else if (sdp->sd_log_tail != current_tail(sdp) && !sdp->sd_log_idle)
 520                 log_write_header(sdp, 0, PULL);
 521         lops_after_commit(sdp, ai);
 522         sdp->sd_log_head = sdp->sd_log_flush_head;
 523         if (sdp->sd_log_flush_wrapped)
 524                 sdp->sd_log_wraps++;
 525
 526         sdp->sd_log_blks_reserved =
 527                 sdp->sd_log_commited_buf =
 528                 sdp->sd_log_commited_revoke = 0;
 529
 530         gfs2_log_lock(sdp);
 531         if (!list_empty(&ai->ai_ail1_list)) {
 532                 list_add(&ai->ai_list, &sdp->sd_ail1_list);
 533                 ai = NULL;
 534         }
 535         gfs2_log_unlock(sdp);
 536
 537         mutex_unlock(&sdp->sd_log_flush_lock);
 538         sdp->sd_vfs->s_dirt = 0;
 539         gfs2_unlock_from_flush(sdp);
 540
 541         kfree(ai);
 542 }
 543
 544 static void log_refund(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 545 {
 546         unsigned int reserved = 1;
 547         unsigned int old;
 548
 549         gfs2_log_lock(sdp);
 550
 551         sdp->sd_log_commited_buf += tr->tr_num_buf_new - tr->tr_num_buf_rm;
 552         gfs2_assert_withdraw(sdp, ((int)sdp->sd_log_commited_buf) >= 0);
 553         sdp->sd_log_commited_revoke += tr->tr_num_revoke - tr->tr_num_revoke_rm;
 554         gfs2_assert_withdraw(sdp, ((int)sdp->sd_log_commited_revoke) >= 0);
 555
 556         if (sdp->sd_log_commited_buf)
 557                 reserved += 1 + sdp->sd_log_commited_buf + sdp->sd_log_commited_buf/503;
 558         if (sdp->sd_log_commited_revoke)
 559                 reserved += gfs2_struct2blk(sdp, sdp->sd_log_commited_revoke,
 560                                             sizeof(uint64_t));
 561
 562         old = sdp->sd_log_blks_free;
 563         sdp->sd_log_blks_free += tr->tr_reserved -
 564                                  (reserved - sdp->sd_log_blks_reserved);
 565
 566         gfs2_assert_withdraw(sdp,
 567                              sdp->sd_log_blks_free >= old);
 568         gfs2_assert_withdraw(sdp,
 569                              sdp->sd_log_blks_free <= sdp->sd_jdesc->jd_blocks);
 570
 571         sdp->sd_log_blks_reserved = reserved;
 572
 573         gfs2_log_unlock(sdp);
 574 }
 575
 576 /**
 577  * gfs2_log_commit - Commit a transaction to the log
 578  * @sdp: the filesystem
 579  * @tr: the transaction
 580  *
 581  * Returns: errno
 582  */
 583
 584 void gfs2_log_commit(struct gfs2_sbd *sdp, struct gfs2_trans *tr)
 585 {
 586         log_refund(sdp, tr);
 587         lops_incore_commit(sdp, tr);
 588
 589         sdp->sd_vfs->s_dirt = 1;
 590         unlock_from_trans(sdp);
 591
 592         kfree(tr);
 593
 594         gfs2_log_lock(sdp);
 595         if (sdp->sd_log_num_buf > gfs2_tune_get(sdp, gt_incore_log_blocks)) {
 596                 gfs2_log_unlock(sdp);
 597                 gfs2_log_flush(sdp);
 598         } else
 599                 gfs2_log_unlock(sdp);
 600 }
 601
 602 /**
 603  * gfs2_log_shutdown - write a shutdown header into a journal
 604  * @sdp: the filesystem
 605  *
 606  */
 607
 608 void gfs2_log_shutdown(struct gfs2_sbd *sdp)
 609 {
 610         mutex_lock(&sdp->sd_log_flush_lock);
 611
 612         gfs2_assert_withdraw(sdp, !atomic_read(&sdp->sd_log_trans_count));
 613         gfs2_assert_withdraw(sdp, !sdp->sd_log_blks_reserved);
 614         gfs2_assert_withdraw(sdp, !sdp->sd_log_num_gl);
 615         gfs2_assert_withdraw(sdp, !sdp->sd_log_num_buf);
 616         gfs2_assert_withdraw(sdp, !sdp->sd_log_num_jdata);
 617         gfs2_assert_withdraw(sdp, !sdp->sd_log_num_revoke);
 618         gfs2_assert_withdraw(sdp, !sdp->sd_log_num_rg);
 619         gfs2_assert_withdraw(sdp, !sdp->sd_log_num_databuf);
 620         gfs2_assert_withdraw(sdp, list_empty(&sdp->sd_ail1_list));
 621
 622         sdp->sd_log_flush_head = sdp->sd_log_head;
 623         sdp->sd_log_flush_wrapped = 0;
 624
 625         log_write_header(sdp, GFS2_LOG_HEAD_UNMOUNT, 0);
 626
 627         gfs2_assert_withdraw(sdp, sdp->sd_log_blks_free ==
 628                              sdp->sd_jdesc->jd_blocks);
 629         gfs2_assert_withdraw(sdp, sdp->sd_log_head == sdp->sd_log_tail);
 630         gfs2_assert_withdraw(sdp, list_empty(&sdp->sd_ail2_list));
 631
 632         sdp->sd_log_head = sdp->sd_log_flush_head;
 633         if (sdp->sd_log_flush_wrapped)
 634                 sdp->sd_log_wraps++;
 635         sdp->sd_log_tail = sdp->sd_log_head;
 636
 637         mutex_unlock(&sdp->sd_log_flush_lock);
 638 }
 639