summaryrefslogblamecommitdiff
path: root/fs/jfs/jfs_logmgr.c
blob: 3315f0b1fbc0ad5106e28dd65369ac7e443739e1 (plain) (tree)
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918

































































                                                                            
                          



                                                                 
                        


                         
                           








                                                                             




                                              


                                                               










































































                                                                             
                                   

  






















                                                                                       
                                                          


































                                                                          
                            



















                                                                 
                                 






















































                                                                   
                                   






















                                                                










































































































































































































































































































































































































































































































































































































                                                                               


                                                               
                                       
                                                                 




                                               
                                                         








                                                                        



                                              











                                                                         








                                                               
                                         






                                                                     
                                           







                                                    
















































                                                                            




                                                                  

                                                                  











                                                                     




                                                         

                                                                    
   
                                                   
                      
                                  

                        


























                                                        
                                   




                                                                        
                                                             





                                                                         
                                                             





                                           
                                                                   
                                             

                               









































                                                                   
                                     















                                                       
                                     










                                                  
                                                                 
                               





























                                                        
                                   
                         
                                                                        
                                 
                                                     

                                       









                                                          
                                                     







                                                              
                                     


































































































































































































































                                                                               
                                   
















































                                                                      
                                     


















                                                                             
                                




























































                                                                                





                                                                 




                                                                         
                                                               






                                                       

                       













                                                                                
         
      
                                             














































                                                                   
                       





















































































































































                                                                                






                                                              
                                   


















                                                                          
                 























                                                     
                                          


                            






















































































                                                                        
                                     






















                                                                    
                                               
                                            
                                                   









































































































































                                                                            
                                               
                                            
                                                   








                                                           



                                     


                                            






















































































































































































                                                                               
            







                                                              

                                                   
                                        
                                       
                        
                                                              

                                                      
                 
                                         

                                            
                 











































































































































































                                                                            
/*
 *   Copyright (C) International Business Machines Corp., 2000-2004
 *   Portions Copyright (C) Christoph Hellwig, 2001-2002
 *
 *   This program is free software;  you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or 
 *   (at your option) any later version.
 * 
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program;  if not, write to the Free Software 
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

/*
 *	jfs_logmgr.c: log manager
 *
 * for related information, see transaction manager (jfs_txnmgr.c), and
 * recovery manager (jfs_logredo.c).
 *
 * note: for detail, RTFS.
 *
 *	log buffer manager:
 * special purpose buffer manager supporting log i/o requirements.
 * per log serial pageout of logpage
 * queuing i/o requests and redrive i/o at iodone
 * maintain current logpage buffer
 * no caching since append only
 * appropriate jfs buffer cache buffers as needed
 *
 *	group commit:
 * transactions which wrote COMMIT records in the same in-memory
 * log page during the pageout of previous/current log page(s) are
 * committed together by the pageout of the page.
 *
 *	TBD lazy commit:
 * transactions are committed asynchronously when the log page
 * containing it COMMIT is paged out when it becomes full;
 *
 *	serialization:
 * . a per log lock serialize log write.
 * . a per log lock serialize group commit.
 * . a per log lock serialize log open/close;
 *
 *	TBD log integrity:
 * careful-write (ping-pong) of last logpage to recover from crash
 * in overwrite.
 * detection of split (out-of-order) write of physical sectors
 * of last logpage via timestamp at end of each sector
 * with its mirror data array at trailer).
 *
 *	alternatives:
 * lsn - 64-bit monotonically increasing integer vs
 * 32-bit lspn and page eor.
 */

#include <linux/fs.h>
#include <linux/blkdev.h>
#include <linux/interrupt.h>
#include <linux/smp_lock.h>
#include <linux/completion.h>
#include <linux/kthread.h>
#include <linux/buffer_head.h>		/* for sync_blockdev() */
#include <linux/bio.h>
#include <linux/suspend.h>
#include <linux/delay.h>
#include <linux/mutex.h>
#include "jfs_incore.h"
#include "jfs_filsys.h"
#include "jfs_metapage.h"
#include "jfs_superblock.h"
#include "jfs_txnmgr.h"
#include "jfs_debug.h"


/*
 * lbuf's ready to be redriven.  Protected by log_redrive_lock (jfsIO thread)
 */
static struct lbuf *log_redrive_list;
static DEFINE_SPINLOCK(log_redrive_lock);


/*
 *	log read/write serialization (per log)
 */
#define LOG_LOCK_INIT(log)	mutex_init(&(log)->loglock)
#define LOG_LOCK(log)		mutex_lock(&((log)->loglock))
#define LOG_UNLOCK(log)		mutex_unlock(&((log)->loglock))


/*
 *	log group commit serialization (per log)
 */

#define LOGGC_LOCK_INIT(log)	spin_lock_init(&(log)->gclock)
#define LOGGC_LOCK(log)		spin_lock_irq(&(log)->gclock)
#define LOGGC_UNLOCK(log)	spin_unlock_irq(&(log)->gclock)
#define LOGGC_WAKEUP(tblk)	wake_up_all(&(tblk)->gcwait)

/*
 *	log sync serialization (per log)
 */
#define	LOGSYNC_DELTA(logsize)		min((logsize)/8, 128*LOGPSIZE)
#define	LOGSYNC_BARRIER(logsize)	((logsize)/4)
/*
#define	LOGSYNC_DELTA(logsize)		min((logsize)/4, 256*LOGPSIZE)
#define	LOGSYNC_BARRIER(logsize)	((logsize)/2)
*/


/*
 *	log buffer cache synchronization
 */
static DEFINE_SPINLOCK(jfsLCacheLock);

#define	LCACHE_LOCK(flags)	spin_lock_irqsave(&jfsLCacheLock, flags)
#define	LCACHE_UNLOCK(flags)	spin_unlock_irqrestore(&jfsLCacheLock, flags)

/*
 * See __SLEEP_COND in jfs_locks.h
 */
#define LCACHE_SLEEP_COND(wq, cond, flags)	\
do {						\
	if (cond)				\
		break;				\
	__SLEEP_COND(wq, cond, LCACHE_LOCK(flags), LCACHE_UNLOCK(flags)); \
} while (0)

#define	LCACHE_WAKEUP(event)	wake_up(event)


/*
 *	lbuf buffer cache (lCache) control
 */
/* log buffer manager pageout control (cumulative, inclusive) */
#define	lbmREAD		0x0001
#define	lbmWRITE	0x0002	/* enqueue at tail of write queue;
				 * init pageout if at head of queue;
				 */
#define	lbmRELEASE	0x0004	/* remove from write queue
				 * at completion of pageout;
				 * do not free/recycle it yet:
				 * caller will free it;
				 */
#define	lbmSYNC		0x0008	/* do not return to freelist
				 * when removed from write queue;
				 */
#define lbmFREE		0x0010	/* return to freelist
				 * at completion of pageout;
				 * the buffer may be recycled;
				 */
#define	lbmDONE		0x0020
#define	lbmERROR	0x0040
#define lbmGC		0x0080	/* lbmIODone to perform post-GC processing
				 * of log page
				 */
#define lbmDIRECT	0x0100

/*
 * Global list of active external journals
 */
static LIST_HEAD(jfs_external_logs);
static struct jfs_log *dummy_log = NULL;
static DEFINE_MUTEX(jfs_log_mutex);

/*
 * forward references
 */
static int lmWriteRecord(struct jfs_log * log, struct tblock * tblk,
			 struct lrd * lrd, struct tlock * tlck);

static int lmNextPage(struct jfs_log * log);
static int lmLogFileSystem(struct jfs_log * log, struct jfs_sb_info *sbi,
			   int activate);

static int open_inline_log(struct super_block *sb);
static int open_dummy_log(struct super_block *sb);
static int lbmLogInit(struct jfs_log * log);
static void lbmLogShutdown(struct jfs_log * log);
static struct lbuf *lbmAllocate(struct jfs_log * log, int);
static void lbmFree(struct lbuf * bp);
static void lbmfree(struct lbuf * bp);
static int lbmRead(struct jfs_log * log, int pn, struct lbuf ** bpp);
static void lbmWrite(struct jfs_log * log, struct lbuf * bp, int flag, int cant_block);
static void lbmDirectWrite(struct jfs_log * log, struct lbuf * bp, int flag);
static int lbmIOWait(struct lbuf * bp, int flag);
static bio_end_io_t lbmIODone;
static void lbmStartIO(struct lbuf * bp);
static void lmGCwrite(struct jfs_log * log, int cant_block);
static int lmLogSync(struct jfs_log * log, int hard_sync);



/*
 *	statistics
 */
#ifdef CONFIG_JFS_STATISTICS
static struct lmStat {
	uint commit;		/* # of commit */
	uint pagedone;		/* # of page written */
	uint submitted;		/* # of pages submitted */
	uint full_page;		/* # of full pages submitted */
	uint partial_page;	/* # of partial pages submitted */
} lmStat;
#endif


/*
 * NAME:	lmLog()
 *
 * FUNCTION:	write a log record;
 *
 * PARAMETER:
 *
 * RETURN:	lsn - offset to the next log record to write (end-of-log);
 *		-1  - error;
 *
 * note: todo: log error handler
 */
int lmLog(struct jfs_log * log, struct tblock * tblk, struct lrd * lrd,
	  struct tlock * tlck)
{
	int lsn;
	int diffp, difft;
	struct metapage *mp = NULL;
	unsigned long flags;

	jfs_info("lmLog: log:0x%p tblk:0x%p, lrd:0x%p tlck:0x%p",
		 log, tblk, lrd, tlck);

	LOG_LOCK(log);

	/* log by (out-of-transaction) JFS ? */
	if (tblk == NULL)
		goto writeRecord;

	/* log from page ? */
	if (tlck == NULL ||
	    tlck->type & tlckBTROOT || (mp = tlck->mp) == NULL)
		goto writeRecord;

	/*
	 *      initialize/update page/transaction recovery lsn
	 */
	lsn = log->lsn;

	LOGSYNC_LOCK(log, flags);

	/*
	 * initialize page lsn if first log write of the page
	 */
	if (mp->lsn == 0) {
		mp->log = log;
		mp->lsn = lsn;
		log->count++;

		/* insert page at tail of logsynclist */
		list_add_tail(&mp->synclist, &log->synclist);
	}

	/*
	 *      initialize/update lsn of tblock of the page
	 *
	 * transaction inherits oldest lsn of pages associated
	 * with allocation/deallocation of resources (their
	 * log records are used to reconstruct allocation map
	 * at recovery time: inode for inode allocation map,
	 * B+-tree index of extent descriptors for block
	 * allocation map);
	 * allocation map pages inherit transaction lsn at
	 * commit time to allow forwarding log syncpt past log
	 * records associated with allocation/deallocation of
	 * resources only after persistent map of these map pages
	 * have been updated and propagated to home.
	 */
	/*
	 * initialize transaction lsn:
	 */
	if (tblk->lsn == 0) {
		/* inherit lsn of its first page logged */
		tblk->lsn = mp->lsn;
		log->count++;

		/* insert tblock after the page on logsynclist */
		list_add(&tblk->synclist, &mp->synclist);
	}
	/*
	 * update transaction lsn:
	 */
	else {
		/* inherit oldest/smallest lsn of page */
		logdiff(diffp, mp->lsn, log);
		logdiff(difft, tblk->lsn, log);
		if (diffp < difft) {
			/* update tblock lsn with page lsn */
			tblk->lsn = mp->lsn;

			/* move tblock after page on logsynclist */
			list_move(&tblk->synclist, &mp->synclist);
		}
	}

	LOGSYNC_UNLOCK(log, flags);

	/*
	 *      write the log record
	 */
      writeRecord:
	lsn = lmWriteRecord(log, tblk, lrd, tlck);

	/*
	 * forward log syncpt if log reached next syncpt trigger
	 */
	logdiff(diffp, lsn, log);
	if (diffp >= log->nextsync)
		lsn = lmLogSync(log, 0);

	/* update end-of-log lsn */
	log->lsn = lsn;

	LOG_UNLOCK(log);

	/* return end-of-log address */
	return lsn;
}

/*
 * NAME:	lmWriteRecord()
 *
 * FUNCTION:	move the log record to current log page
 *
 * PARAMETER:	cd	- commit descriptor
 *
 * RETURN:	end-of-log address
 *			
 * serialization: LOG_LOCK() held on entry/exit
 */
static int
lmWriteRecord(struct jfs_log * log, struct tblock * tblk, struct lrd * lrd,
	      struct tlock * tlck)
{
	int lsn = 0;		/* end-of-log address */
	struct lbuf *bp;	/* dst log page buffer */
	struct logpage *lp;	/* dst log page */
	caddr_t dst;		/* destination address in log page */
	int dstoffset;		/* end-of-log offset in log page */
	int freespace;		/* free space in log page */
	caddr_t p;		/* src meta-data page */
	caddr_t src;
	int srclen;
	int nbytes;		/* number of bytes to move */
	int i;
	int len;
	struct linelock *linelock;
	struct lv *lv;
	struct lvd *lvd;
	int l2linesize;

	len = 0;

	/* retrieve destination log page to write */
	bp = (struct lbuf *) log->bp;
	lp = (struct logpage *) bp->l_ldata;
	dstoffset = log->eor;

	/* any log data to write ? */
	if (tlck == NULL)
		goto moveLrd;

	/*
	 *      move log record data
	 */
	/* retrieve source meta-data page to log */
	if (tlck->flag & tlckPAGELOCK) {
		p = (caddr_t) (tlck->mp->data);
		linelock = (struct linelock *) & tlck->lock;
	}
	/* retrieve source in-memory inode to log */
	else if (tlck->flag & tlckINODELOCK) {
		if (tlck->type & tlckDTREE)
			p = (caddr_t) &JFS_IP(tlck->ip)->i_dtroot;
		else
			p = (caddr_t) &JFS_IP(tlck->ip)->i_xtroot;
		linelock = (struct linelock *) & tlck->lock;
	}
#ifdef	_JFS_WIP
	else if (tlck->flag & tlckINLINELOCK) {

		inlinelock = (struct inlinelock *) & tlck;
		p = (caddr_t) & inlinelock->pxd;
		linelock = (struct linelock *) & tlck;
	}
#endif				/* _JFS_WIP */
	else {
		jfs_err("lmWriteRecord: UFO tlck:0x%p", tlck);
		return 0;	/* Probably should trap */
	}
	l2linesize = linelock->l2linesize;

      moveData:
	ASSERT(linelock->index <= linelock->maxcnt);

	lv = linelock->lv;
	for (i = 0; i < linelock->index; i++, lv++) {
		if (lv->length == 0)
			continue;

		/* is page full ? */
		if (dstoffset >= LOGPSIZE - LOGPTLRSIZE) {
			/* page become full: move on to next page */
			lmNextPage(log);

			bp = log->bp;
			lp = (struct logpage *) bp->l_ldata;
			dstoffset = LOGPHDRSIZE;
		}

		/*
		 * move log vector data
		 */
		src = (u8 *) p + (lv->offset << l2linesize);
		srclen = lv->length << l2linesize;
		len += srclen;
		while (srclen > 0) {
			freespace = (LOGPSIZE - LOGPTLRSIZE) - dstoffset;
			nbytes = min(freespace, srclen);
			dst = (caddr_t) lp + dstoffset;
			memcpy(dst, src, nbytes);
			dstoffset += nbytes;

			/* is page not full ? */
			if (dstoffset < LOGPSIZE - LOGPTLRSIZE)
				break;

			/* page become full: move on to next page */
			lmNextPage(log);

			bp = (struct lbuf *) log->bp;
			lp = (struct logpage *) bp->l_ldata;
			dstoffset = LOGPHDRSIZE;

			srclen -= nbytes;
			src += nbytes;
		}

		/*
		 * move log vector descriptor
		 */
		len += 4;
		lvd = (struct lvd *) ((caddr_t) lp + dstoffset);
		lvd->offset = cpu_to_le16(lv->offset);
		lvd->length = cpu_to_le16(lv->length);
		dstoffset += 4;
		jfs_info("lmWriteRecord: lv offset:%d length:%d",
			 lv->offset, lv->length);
	}

	if ((i = linelock->next)) {
		linelock = (struct linelock *) lid_to_tlock(i);
		goto moveData;
	}

	/*
	 *      move log record descriptor
	 */
      moveLrd:
	lrd->length = cpu_to_le16(len);

	src = (caddr_t) lrd;
	srclen = LOGRDSIZE;

	while (srclen > 0) {
		freespace = (LOGPSIZE - LOGPTLRSIZE) - dstoffset;
		nbytes = min(freespace, srclen);
		dst = (caddr_t) lp + dstoffset;
		memcpy(dst, src, nbytes);

		dstoffset += nbytes;
		srclen -= nbytes;

		/* are there more to move than freespace of page ? */
		if (srclen)
			goto pageFull;

		/*
		 * end of log record descriptor
		 */

		/* update last log record eor */
		log->eor = dstoffset;
		bp->l_eor = dstoffset;
		lsn = (log->page << L2LOGPSIZE) + dstoffset;

		if (lrd->type & cpu_to_le16(LOG_COMMIT)) {
			tblk->clsn = lsn;
			jfs_info("wr: tclsn:0x%x, beor:0x%x", tblk->clsn,
				 bp->l_eor);

			INCREMENT(lmStat.commit);	/* # of commit */

			/*
			 * enqueue tblock for group commit:
			 *
			 * enqueue tblock of non-trivial/synchronous COMMIT
			 * at tail of group commit queue
			 * (trivial/asynchronous COMMITs are ignored by
			 * group commit.)
			 */
			LOGGC_LOCK(log);

			/* init tblock gc state */
			tblk->flag = tblkGC_QUEUE;
			tblk->bp = log->bp;
			tblk->pn = log->page;
			tblk->eor = log->eor;

			/* enqueue transaction to commit queue */
			list_add_tail(&tblk->cqueue, &log->cqueue);

			LOGGC_UNLOCK(log);
		}

		jfs_info("lmWriteRecord: lrd:0x%04x bp:0x%p pn:%d eor:0x%x",
			le16_to_cpu(lrd->type), log->bp, log->page, dstoffset);

		/* page not full ? */
		if (dstoffset < LOGPSIZE - LOGPTLRSIZE)
			return lsn;

	      pageFull:
		/* page become full: move on to next page */
		lmNextPage(log);

		bp = (struct lbuf *) log->bp;
		lp = (struct logpage *) bp->l_ldata;
		dstoffset = LOGPHDRSIZE;
		src += nbytes;
	}

	return lsn;
}


/*
 * NAME:	lmNextPage()
 *
 * FUNCTION:	write current page and allocate next page.
 *
 * PARAMETER:	log
 *
 * RETURN:	0
 *			
 * serialization: LOG_LOCK() held on entry/exit
 */
static int lmNextPage(struct jfs_log * log)
{
	struct logpage *lp;
	int lspn;		/* log sequence page number */
	int pn;			/* current page number */
	struct lbuf *bp;
	struct lbuf *nextbp;
	struct tblock *tblk;

	/* get current log page number and log sequence page number */
	pn = log->page;
	bp = log->bp;
	lp = (struct logpage *) bp->l_ldata;
	lspn = le32_to_cpu(lp->h.page);

	LOGGC_LOCK(log);

	/*
	 *      write or queue the full page at the tail of write queue
	 */
	/* get the tail tblk on commit queue */
	if (list_empty(&log->cqueue))
		tblk = NULL;
	else
		tblk = list_entry(log->cqueue.prev, struct tblock, cqueue);

	/* every tblk who has COMMIT record on the current page,
	 * and has not been committed, must be on commit queue
	 * since tblk is queued at commit queueu at the time
	 * of writing its COMMIT record on the page before
	 * page becomes full (even though the tblk thread
	 * who wrote COMMIT record may have been suspended
	 * currently);
	 */

	/* is page bound with outstanding tail tblk ? */
	if (tblk && tblk->pn == pn) {
		/* mark tblk for end-of-page */
		tblk->flag |= tblkGC_EOP;

		if (log->cflag & logGC_PAGEOUT) {
			/* if page is not already on write queue,
			 * just enqueue (no lbmWRITE to prevent redrive)
			 * buffer to wqueue to ensure correct serial order
			 * of the pages since log pages will be added
			 * continuously
			 */
			if (bp->l_wqnext == NULL)
				lbmWrite(log, bp, 0, 0);
		} else {
			/*
			 * No current GC leader, initiate group commit
			 */
			log->cflag |= logGC_PAGEOUT;
			lmGCwrite(log, 0);
		}
	}
	/* page is not bound with outstanding tblk:
	 * init write or mark it to be redriven (lbmWRITE)
	 */
	else {
		/* finalize the page */
		bp->l_ceor = bp->l_eor;
		lp->h.eor = lp->t.eor = cpu_to_le16(bp->l_ceor);
		lbmWrite(log, bp, lbmWRITE | lbmRELEASE | lbmFREE, 0);
	}
	LOGGC_UNLOCK(log);

	/*
	 *      allocate/initialize next page
	 */
	/* if log wraps, the first data page of log is 2
	 * (0 never used, 1 is superblock).
	 */
	log->page = (pn == log->size - 1) ? 2 : pn + 1;
	log->eor = LOGPHDRSIZE;	/* ? valid page empty/full at logRedo() */

	/* allocate/initialize next log page buffer */
	nextbp = lbmAllocate(log, log->page);
	nextbp->l_eor = log->eor;
	log->bp = nextbp;

	/* initialize next log page */
	lp = (struct logpage *) nextbp->l_ldata;
	lp->h.page = lp->t.page = cpu_to_le32(lspn + 1);
	lp->h.eor = lp->t.eor = cpu_to_le16(LOGPHDRSIZE);

	return 0;
}


/*
 * NAME:	lmGroupCommit()
 *
 * FUNCTION:	group commit
 *	initiate pageout of the pages with COMMIT in the order of
 *	page number - redrive pageout of the page at the head of
 *	pageout queue until full page has been written.
 *
 * RETURN:	
 *
 * NOTE:
 *	LOGGC_LOCK serializes log group commit queue, and
 *	transaction blocks on the commit queue.
 *	N.B. LOG_LOCK is NOT held during lmGroupCommit().
 */
int lmGroupCommit(struct jfs_log * log, struct tblock * tblk)
{
	int rc = 0;

	LOGGC_LOCK(log);

	/* group committed already ? */
	if (tblk->flag & tblkGC_COMMITTED) {
		if (tblk->flag & tblkGC_ERROR)
			rc = -EIO;

		LOGGC_UNLOCK(log);
		return rc;
	}
	jfs_info("lmGroup Commit: tblk = 0x%p, gcrtc = %d", tblk, log->gcrtc);

	if (tblk->xflag & COMMIT_LAZY)
		tblk->flag |= tblkGC_LAZY;

	if ((!(log->cflag & logGC_PAGEOUT)) && (!list_empty(&log->cqueue)) &&
	    (!(tblk->xflag & COMMIT_LAZY) || test_bit(log_FLUSH, &log->flag)
	     || jfs_tlocks_low)) {
		/*
		 * No pageout in progress
		 *
		 * start group commit as its group leader.
		 */
		log->cflag |= logGC_PAGEOUT;

		lmGCwrite(log, 0);
	}

	if (tblk->xflag & COMMIT_LAZY) {
		/*
		 * Lazy transactions can leave now
		 */
		LOGGC_UNLOCK(log);
		return 0;
	}

	/* lmGCwrite gives up LOGGC_LOCK, check again */

	if (tblk->flag & tblkGC_COMMITTED) {
		if (tblk->flag & tblkGC_ERROR)
			rc = -EIO;

		LOGGC_UNLOCK(log);
		return rc;
	}

	/* upcount transaction waiting for completion
	 */
	log->gcrtc++;
	tblk->flag |= tblkGC_READY;

	__SLEEP_COND(tblk->gcwait, (tblk->flag & tblkGC_COMMITTED),
		     LOGGC_LOCK(log), LOGGC_UNLOCK(log));

	/* removed from commit queue */
	if (tblk->flag & tblkGC_ERROR)
		rc = -EIO;

	LOGGC_UNLOCK(log);
	return rc;
}

/*
 * NAME:	lmGCwrite()
 *
 * FUNCTION:	group commit write
 *	initiate write of log page, building a group of all transactions
 *	with commit records on that page.
 *
 * RETURN:	None
 *
 * NOTE:
 *	LOGGC_LOCK must be held by caller.
 *	N.B. LOG_LOCK is NOT held during lmGroupCommit().
 */
static void lmGCwrite(struct jfs_log * log, int cant_write)
{
	struct lbuf *bp;
	struct logpage *lp;
	int gcpn;		/* group commit page number */
	struct tblock *tblk;
	struct tblock *xtblk = NULL;

	/*
	 * build the commit group of a log page
	 *
	 * scan commit queue and make a commit group of all
	 * transactions with COMMIT records on the same log page.
	 */
	/* get the head tblk on the commit queue */
	gcpn = list_entry(log->cqueue.next, struct tblock, cqueue)->pn;

	list_for_each_entry(tblk, &log->cqueue, cqueue) {
		if (tblk->pn != gcpn)
			break;

		xtblk = tblk;

		/* state transition: (QUEUE, READY) -> COMMIT */
		tblk->flag |= tblkGC_COMMIT;
	}
	tblk = xtblk;		/* last tblk of the page */

	/*
	 * pageout to commit transactions on the log page.
	 */
	bp = (struct lbuf *) tblk->bp;
	lp = (struct logpage *) bp->l_ldata;
	/* is page already full ? */
	if (tblk->flag & tblkGC_EOP) {
		/* mark page to free at end of group commit of the page */
		tblk->flag &= ~tblkGC_EOP;
		tblk->flag |= tblkGC_FREE;
		bp->l_ceor = bp->l_eor;
		lp->h.eor = lp->t.eor = cpu_to_le16(bp->l_ceor);
		lbmWrite(log, bp, lbmWRITE | lbmRELEASE | lbmGC,
			 cant_write);
		INCREMENT(lmStat.full_page);
	}
	/* page is not yet full */
	else {
		bp->l_ceor = tblk->eor;	/* ? bp->l_ceor = bp->l_eor; */
		lp->h.eor = lp->t.eor = cpu_to_le16(bp->l_ceor);
		lbmWrite(log, bp, lbmWRITE | lbmGC, cant_write);
		INCREMENT(lmStat.partial_page);
	}
}

/*
 * NAME:	lmPostGC()
 *
 * FUNCTION:	group commit post-processing
 *	Processes transactions after their commit records have been written
 *	to disk, redriving log I/O if necessary.
 *
 * RETURN:	None
 *
 * NOTE:
 *	This routine is called a interrupt time by lbmIODone
 */
static void lmPostGC(struct lbuf * bp)
{
	unsigned long flags;
	struct jfs_log *log = bp->l_log;
	struct logpage *lp;
	struct tblock *tblk, *temp;

	//LOGGC_LOCK(log);
	spin_lock_irqsave(&log->gclock, flags);
	/*
	 * current pageout of group commit completed.
	 *
	 * remove/wakeup transactions from commit queue who were
	 * group committed with the current log page
	 */
	list_for_each_entry_safe(tblk, temp, &log->cqueue, cqueue) {
		if (!(tblk->flag & tblkGC_COMMIT))
			break;
		/* if transaction was marked GC_COMMIT then
		 * it has been shipped in the current pageout
		 * and made it to disk - it is committed.
		 */

		if (bp->l_flag & lbmERROR)
			tblk->flag |= tblkGC_ERROR;

		/* remove it from the commit queue */
		list_del(&tblk->cqueue);
		tblk->flag &= ~tblkGC_QUEUE;

		if (tblk == log->flush_tblk) {
			/* we can stop flushing the log now */
			clear_bit(log_FLUSH, &log->flag);
			log->flush_tblk = NULL;
		}

		jfs_info("lmPostGC: tblk = 0x%p, flag = 0x%x", tblk,
			 tblk->flag);

		if (!(tblk->xflag & COMMIT_FORCE))
			/*
			 * Hand tblk over to lazy commit thread
			 */
			txLazyUnlock(tblk);
		else {
			/* state transition: COMMIT -> COMMITTED */
			tblk->flag |= tblkGC_COMMITTED;

			if (tblk->flag & tblkGC_READY)
				log->gcrtc--;

			LOGGC_WAKEUP(tblk);
		}

		/* was page full before pageout ?
		 * (and this is the last tblk bound with the page)
		 */
		if (tblk->flag & tblkGC_FREE)
			lbmFree(bp);
		/* did page become full after pageout ?
		 * (and this is the last tblk bound with the page)
		 */
		else if (tblk->flag & tblkGC_EOP) {
			/* finalize the page */
			lp = (struct logpage *) bp->l_ldata;
			bp->l_ceor = bp->l_eor;
			lp->h.eor = lp->t.eor = cpu_to_le16(bp->l_eor);
			jfs_info("lmPostGC: calling lbmWrite");
			lbmWrite(log, bp, lbmWRITE | lbmRELEASE | lbmFREE,
				 1);
		}

	}

	/* are there any transactions who have entered lnGroupCommit()
	 * (whose COMMITs are after that of the last log page written.
	 * They are waiting for new group commit (above at (SLEEP 1))
	 * or lazy transactions are on a full (queued) log page,
	 * select the latest ready transaction as new group leader and
	 * wake her up to lead her group.
	 */
	if ((!list_empty(&log->cqueue)) &&
	    ((log->gcrtc > 0) || (tblk->bp->l_wqnext != NULL) ||
	     test_bit(log_FLUSH, &log->flag) || jfs_tlocks_low))
		/*
		 * Call lmGCwrite with new group leader
		 */
		lmGCwrite(log, 1);

	/* no transaction are ready yet (transactions are only just
	 * queued (GC_QUEUE) and not entered for group commit yet).
	 * the first transaction entering group commit
	 * will elect herself as new group leader.
	 */
	else
		log->cflag &= ~logGC_PAGEOUT;

	//LOGGC_UNLOCK(log);
	spin_unlock_irqrestore(&log->gclock, flags);
	return;
}

/*
 * NAME:	lmLogSync()
 *
 * FUNCTION:	write log SYNCPT record for specified log
 *	if new sync address is available
 *	(normally the case if sync() is executed by back-ground
 *	process).
 *	calculate new value of i_nextsync which determines when
 *	this code is called again.
 *
 * PARAMETERS:	log	- log structure
 * 		hard_sync - 1 to force all metadata to be written
 *
 * RETURN:	0
 *			
 * serialization: LOG_LOCK() held on entry/exit
 */
static int lmLogSync(struct jfs_log * log, int hard_sync)
{
	int logsize;
	int written;		/* written since last syncpt */
	int free;		/* free space left available */
	int delta;		/* additional delta to write normally */
	int more;		/* additional write granted */
	struct lrd lrd;
	int lsn;
	struct logsyncblk *lp;
	struct jfs_sb_info *sbi;
	unsigned long flags;

	/* push dirty metapages out to disk */
	if (hard_sync)
		list_for_each_entry(sbi, &log->sb_list, log_list) {
			filemap_fdatawrite(sbi->ipbmap->i_mapping);
			filemap_fdatawrite(sbi->ipimap->i_mapping);
			filemap_fdatawrite(sbi->direct_inode->i_mapping);
		}
	else
		list_for_each_entry(sbi, &log->sb_list, log_list) {
			filemap_flush(sbi->ipbmap->i_mapping);
			filemap_flush(sbi->ipimap->i_mapping);
			filemap_flush(sbi->direct_inode->i_mapping);
		}

	/*
	 *      forward syncpt
	 */
	/* if last sync is same as last syncpt,
	 * invoke sync point forward processing to update sync.
	 */

	if (log->sync == log->syncpt) {
		LOGSYNC_LOCK(log, flags);
		if (list_empty(&log->synclist))
			log->sync = log->lsn;
		else {
			lp = list_entry(log->synclist.next,
					struct logsyncblk, synclist);
			log->sync = lp->lsn;
		}
		LOGSYNC_UNLOCK(log, flags);

	}

	/* if sync is different from last syncpt,
	 * write a SYNCPT record with syncpt = sync.
	 * reset syncpt = sync
	 */
	if (log->sync != log->syncpt) {
		lrd.logtid = 0;
		lrd.backchain = 0;
		lrd.type = cpu_to_le16(LOG_SYNCPT);
		lrd.length = 0;
		lrd.log.syncpt.sync = cpu_to_le32(log->sync);
		lsn = lmWriteRecord(log, NULL, &lrd, NULL);

		log->syncpt = log->sync;
	} else
		lsn = log->lsn;

	/*
	 *      setup next syncpt trigger (SWAG)
	 */
	logsize = log->logsize;

	logdiff(written, lsn, log);
	free = logsize - written;
	delta = LOGSYNC_DELTA(logsize);
	more = min(free / 2, delta);
	if (more < 2 * LOGPSIZE) {
		jfs_warn("\n ... Log Wrap ... Log Wrap ... Log Wrap ...\n");
		/*
		 *      log wrapping
		 *
		 * option 1 - panic ? No.!
		 * option 2 - shutdown file systems
		 *            associated with log ?
		 * option 3 - extend log ?
		 */
		/*
		 * option 4 - second chance
		 *
		 * mark log wrapped, and continue.
		 * when all active transactions are completed,
		 * mark log vaild for recovery.
		 * if crashed during invalid state, log state
		 * implies invald log, forcing fsck().
		 */
		/* mark log state log wrap in log superblock */
		/* log->state = LOGWRAP; */

		/* reset sync point computation */
		log->syncpt = log->sync = lsn;
		log->nextsync = delta;
	} else
		/* next syncpt trigger = written + more */
		log->nextsync = written + more;

	/* if number of bytes written from last sync point is more
	 * than 1/4 of the log size, stop new transactions from
	 * starting until all current transactions are completed
	 * by setting syncbarrier flag.
	 */
	if (!test_bit(log_SYNCBARRIER, &log->flag) &&
	    (written > LOGSYNC_BARRIER(logsize)) && log->active) {
		set_bit(log_SYNCBARRIER, &log->flag);
		jfs_info("log barrier on: lsn=0x%x syncpt=0x%x", lsn,
			 log->syncpt);
		/*
		 * We may have to initiate group commit
		 */
		jfs_flush_journal(log, 0);
	}

	return lsn;
}

/*
 * NAME:	jfs_syncpt
 *
 * FUNCTION:	write log SYNCPT record for specified log
 *
 * PARAMETERS:	log	  - log structure
 * 		hard_sync - set to 1 to force metadata to be written
 */
void jfs_syncpt(struct jfs_log *log, int hard_sync)
{	LOG_LOCK(log);
	lmLogSync(log, hard_sync);
	LOG_UNLOCK(log);
}

/*
 * NAME:	lmLogOpen()
 *
 * FUNCTION:    open the log on first open;
 *	insert filesystem in the active list of the log.
 *
 * PARAMETER:	ipmnt	- file system mount inode
 *		iplog 	- log inode (out)
 *
 * RETURN:
 *
 * serialization:
 */
int lmLogOpen(struct super_block *sb)
{
	int rc;
	struct block_device *bdev;
	struct jfs_log *log;
	struct jfs_sb_info *sbi = JFS_SBI(sb);

	if (sbi->flag & JFS_NOINTEGRITY)
		return open_dummy_log(sb);
	
	if (sbi->mntflag & JFS_INLINELOG)
		return open_inline_log(sb);

	mutex_lock(&jfs_log_mutex);
	list_for_each_entry(log, &jfs_external_logs, journal_list) {
		if (log->bdev->bd_dev == sbi->logdev) {
			if (memcmp(log->uuid, sbi->loguuid,
				   sizeof(log->uuid))) {
				jfs_warn("wrong uuid on JFS journal\n");
				mutex_unlock(&jfs_log_mutex);
				return -EINVAL;
			}
			/*
			 * add file system to log active file system list
			 */
			if ((rc = lmLogFileSystem(log, sbi, 1))) {
				mutex_unlock(&jfs_log_mutex);
				return rc;
			}
			goto journal_found;
		}
	}

	if (!(log = kzalloc(sizeof(struct jfs_log), GFP_KERNEL))) {
		mutex_unlock(&jfs_log_mutex);
		return -ENOMEM;
	}
	INIT_LIST_HEAD(&log->sb_list);
	init_waitqueue_head(&log->syncwait);

	/*
	 *      external log as separate logical volume
	 *
	 * file systems to log may have n-to-1 relationship;
	 */

	bdev = open_by_devnum(sbi->logdev, FMODE_READ|FMODE_WRITE);
	if (IS_ERR(bdev)) {
		rc = -PTR_ERR(bdev);
		goto free;
	}

	if ((rc = bd_claim(bdev, log))) {
		goto close;
	}

	log->bdev = bdev;
	memcpy(log->uuid, sbi->loguuid, sizeof(log->uuid));
	
	/*
	 * initialize log:
	 */
	if ((rc = lmLogInit(log)))
		goto unclaim;

	list_add(&log->journal_list, &jfs_external_logs);

	/*
	 * add file system to log active file system list
	 */
	if ((rc = lmLogFileSystem(log, sbi, 1)))
		goto shutdown;

journal_found:
	LOG_LOCK(log);
	list_add(&sbi->log_list, &log->sb_list);
	sbi->log = log;
	LOG_UNLOCK(log);

	mutex_unlock(&jfs_log_mutex);
	return 0;

	/*
	 *      unwind on error
	 */
      shutdown:		/* unwind lbmLogInit() */
	list_del(&log->journal_list);
	lbmLogShutdown(log);

      unclaim:
	bd_release(bdev);

      close:		/* close external log device */
	blkdev_put(bdev);

      free:		/* free log descriptor */
	mutex_unlock(&jfs_log_mutex);
	kfree(log);

	jfs_warn("lmLogOpen: exit(%d)", rc);
	return rc;
}

static int open_inline_log(struct super_block *sb)
{
	struct jfs_log *log;
	int rc;

	if (!(log = kzalloc(sizeof(struct jfs_log), GFP_KERNEL)))
		return -ENOMEM;
	INIT_LIST_HEAD(&log->sb_list);
	init_waitqueue_head(&log->syncwait);

	set_bit(log_INLINELOG, &log->flag);
	log->bdev = sb->s_bdev;
	log->base = addressPXD(&JFS_SBI(sb)->logpxd);
	log->size = lengthPXD(&JFS_SBI(sb)->logpxd) >>
	    (L2LOGPSIZE - sb->s_blocksize_bits);
	log->l2bsize = sb->s_blocksize_bits;
	ASSERT(L2LOGPSIZE >= sb->s_blocksize_bits);

	/*
	 * initialize log.
	 */
	if ((rc = lmLogInit(log))) {
		kfree(log);
		jfs_warn("lmLogOpen: exit(%d)", rc);
		return rc;
	}

	list_add(&JFS_SBI(sb)->log_list, &log->sb_list);
	JFS_SBI(sb)->log = log;

	return rc;
}

static int open_dummy_log(struct super_block *sb)
{
	int rc;

	mutex_lock(&jfs_log_mutex);
	if (!dummy_log) {
		dummy_log = kzalloc(sizeof(struct jfs_log), GFP_KERNEL);
		if (!dummy_log) {
			mutex_unlock(&jfs_log_mutex);
			return -ENOMEM;
		}
		INIT_LIST_HEAD(&dummy_log->sb_list);
		init_waitqueue_head(&dummy_log->syncwait);
		dummy_log->no_integrity = 1;
		/* Make up some stuff */
		dummy_log->base = 0;
		dummy_log->size = 1024;
		rc = lmLogInit(dummy_log);
		if (rc) {
			kfree(dummy_log);
			dummy_log = NULL;
			mutex_unlock(&jfs_log_mutex);
			return rc;
		}
	}

	LOG_LOCK(dummy_log);
	list_add(&JFS_SBI(sb)->log_list, &dummy_log->sb_list);
	JFS_SBI(sb)->log = dummy_log;
	LOG_UNLOCK(dummy_log);
	mutex_unlock(&jfs_log_mutex);

	return 0;
}

/*
 * NAME:	lmLogInit()
 *
 * FUNCTION:	log initialization at first log open.
 *
 *	logredo() (or logformat()) should have been run previously.
 *	initialize the log from log superblock.
 *	set the log state in the superblock to LOGMOUNT and
 *	write SYNCPT log record.
 *		
 * PARAMETER:	log	- log structure
 *
 * RETURN:	0	- if ok
 *		-EINVAL	- bad log magic number or superblock dirty
 *		error returned from logwait()
 *			
 * serialization: single first open thread
 */
int lmLogInit(struct jfs_log * log)
{
	int rc = 0;
	struct lrd lrd;
	struct logsuper *logsuper;
	struct lbuf *bpsuper;
	struct lbuf *bp;
	struct logpage *lp;
	int lsn = 0;

	jfs_info("lmLogInit: log:0x%p", log);

	/* initialize the group commit serialization lock */
	LOGGC_LOCK_INIT(log);

	/* allocate/initialize the log write serialization lock */
	LOG_LOCK_INIT(log);

	LOGSYNC_LOCK_INIT(log);

	INIT_LIST_HEAD(&log->synclist);

	INIT_LIST_HEAD(&log->cqueue);
	log->flush_tblk = NULL;

	log->count = 0;

	/*
	 * initialize log i/o
	 */
	if ((rc = lbmLogInit(log)))
		return rc;

	if (!test_bit(log_INLINELOG, &log->flag))
		log->l2bsize = L2LOGPSIZE;
	
	/* check for disabled journaling to disk */
	if (log->no_integrity) {
		/*
		 * Journal pages will still be filled.  When the time comes
		 * to actually do the I/O, the write is not done, and the
		 * endio routine is called directly.
		 */
		bp = lbmAllocate(log , 0);
		log->bp = bp;
		bp->l_pn = bp->l_eor = 0;
	} else {
		/*
		 * validate log superblock
		 */
		if ((rc = lbmRead(log, 1, &bpsuper)))
			goto errout10;

		logsuper = (struct logsuper *) bpsuper->l_ldata;

		if (logsuper->magic != cpu_to_le32(LOGMAGIC)) {
			jfs_warn("*** Log Format Error ! ***");
			rc = -EINVAL;
			goto errout20;
		}

		/* logredo() should have been run successfully. */
		if (logsuper->state != cpu_to_le32(LOGREDONE)) {
			jfs_warn("*** Log Is Dirty ! ***");
			rc = -EINVAL;
			goto errout20;
		}

		/* initialize log from log superblock */
		if (test_bit(log_INLINELOG,&log->flag)) {
			if (log->size != le32_to_cpu(logsuper->size)) {
				rc = -EINVAL;
				goto errout20;
			}
			jfs_info("lmLogInit: inline log:0x%p base:0x%Lx "
				 "size:0x%x", log,
				 (unsigned long long) log->base, log->size);
		} else {
			if (memcmp(logsuper->uuid, log->uuid, 16)) {
				jfs_warn("wrong uuid on JFS log device");
				goto errout20;
			}
			log->size = le32_to_cpu(logsuper->size);
			log->l2bsize = le32_to_cpu(logsuper->l2bsize);
			jfs_info("lmLogInit: external log:0x%p base:0x%Lx "
				 "size:0x%x", log,
				 (unsigned long long) log->base, log->size);
		}

		log->page = le32_to_cpu(logsuper->end) / LOGPSIZE;
		log->eor = le32_to_cpu(logsuper->end) - (LOGPSIZE * log->page);

		/*
		 * initialize for log append write mode
		 */
		/* establish current/end-of-log page/buffer */
		if ((rc = lbmRead(log, log->page, &bp)))
			goto errout20;

		lp = (struct logpage *) bp->l_ldata;

		jfs_info("lmLogInit: lsn:0x%x page:%d eor:%d:%d",
			 le32_to_cpu(logsuper->end), log->page, log->eor,
			 le16_to_cpu(lp->h.eor));

		log->bp = bp;
		bp->l_pn = log->page;
		bp->l_eor = log->eor;

		/* if current page is full, move on to next page */
		if (log->eor >= LOGPSIZE - LOGPTLRSIZE)
			lmNextPage(log);

		/*
		 * initialize log syncpoint
		 */
		/*
		 * write the first SYNCPT record with syncpoint = 0
		 * (i.e., log redo up to HERE !);
		 * remove current page from lbm write queue at end of pageout
		 * (to write log superblock update), but do not release to
		 * freelist;
		 */
		lrd.logtid = 0;
		lrd.backchain = 0;
		lrd.type = cpu_to_le16(LOG_SYNCPT);
		lrd.length = 0;
		lrd.log.syncpt.sync = 0;
		lsn = lmWriteRecord(log, NULL, &lrd, NULL);
		bp = log->bp;
		bp->l_ceor = bp->l_eor;
		lp = (struct logpage *) bp->l_ldata;
		lp->h.eor = lp->t.eor = cpu_to_le16(bp->l_eor);
		lbmWrite(log, bp, lbmWRITE | lbmSYNC, 0);
		if ((rc = lbmIOWait(bp, 0)))
			goto errout30;

		/*
		 * update/write superblock
		 */
		logsuper->state = cpu_to_le32(LOGMOUNT);
		log->serial = le32_to_cpu(logsuper->serial) + 1;
		logsuper->serial = cpu_to_le32(log->serial);
		lbmDirectWrite(log, bpsuper, lbmWRITE | lbmRELEASE | lbmSYNC);
		if ((rc = lbmIOWait(bpsuper, lbmFREE)))
			goto errout30;
	}

	/* initialize logsync parameters */
	log->logsize = (log->size - 2) << L2LOGPSIZE;
	log->lsn = lsn;
	log->syncpt = lsn;
	log->sync = log->syncpt;
	log->nextsync = LOGSYNC_DELTA(log->logsize);

	jfs_info("lmLogInit: lsn:0x%x syncpt:0x%x sync:0x%x",
		 log->lsn, log->syncpt, log->sync);

	/*
	 * initialize for lazy/group commit
	 */
	log->clsn = lsn;

	return 0;

	/*
	 *      unwind on error
	 */
      errout30:		/* release log page */
	log->wqueue = NULL;
	bp->l_wqnext = NULL;
	lbmFree(bp);

      errout20:		/* release log superblock */
	lbmFree(bpsuper);

      errout10:		/* unwind lbmLogInit() */
	lbmLogShutdown(log);

	jfs_warn("lmLogInit: exit(%d)", rc);
	return rc;
}


/*
 * NAME:	lmLogClose()
 *
 * FUNCTION:	remove file system <ipmnt> from active list of log <iplog>
 *		and close it on last close.
 *
 * PARAMETER:	sb	- superblock
 *
 * RETURN:	errors from subroutines
 *
 * serialization:
 */
int lmLogClose(struct super_block *sb)
{
	struct jfs_sb_info *sbi = JFS_SBI(sb);
	struct jfs_log *log = sbi->log;
	struct block_device *bdev;
	int rc = 0;

	jfs_info("lmLogClose: log:0x%p", log);

	mutex_lock(&jfs_log_mutex);
	LOG_LOCK(log);
	list_del(&sbi->log_list);
	LOG_UNLOCK(log);
	sbi->log = NULL;

	/*
	 * We need to make sure all of the "written" metapages
	 * actually make it to disk
	 */
	sync_blockdev(sb->s_bdev);

	if (test_bit(log_INLINELOG, &log->flag)) {
		/*
		 *      in-line log in host file system
		 */
		rc = lmLogShutdown(log);
		kfree(log);
		goto out;
	}

	if (!log->no_integrity)
		lmLogFileSystem(log, sbi, 0);

	if (!list_empty(&log->sb_list))
		goto out;

	/*
	 * TODO: ensure that the dummy_log is in a state to allow
	 * lbmLogShutdown to deallocate all the buffers and call
	 * kfree against dummy_log.  For now, leave dummy_log & its
	 * buffers in memory, and resuse if another no-integrity mount
	 * is requested.
	 */
	if (log->no_integrity)
		goto out;

	/*
	 *      external log as separate logical volume
	 */
	list_del(&log->journal_list);
	bdev = log->bdev;
	rc = lmLogShutdown(log);

	bd_release(bdev);
	blkdev_put(bdev);

	kfree(log);

      out:
	mutex_unlock(&jfs_log_mutex);
	jfs_info("lmLogClose: exit(%d)", rc);
	return rc;
}


/*
 * NAME:	jfs_flush_journal()
 *
 * FUNCTION:	initiate write of any outstanding transactions to the journal
 *		and optionally wait until they are all written to disk
 *
 *		wait == 0  flush until latest txn is committed, don't wait
 *		wait == 1  flush until latest txn is committed, wait
 *		wait > 1   flush until all txn's are complete, wait
 */
void jfs_flush_journal(struct jfs_log *log, int wait)
{
	int i;
	struct tblock *target = NULL;
	struct jfs_sb_info *sbi;

	/* jfs_write_inode may call us during read-only mount */
	if (!log)
		return;

	jfs_info("jfs_flush_journal: log:0x%p wait=%d", log, wait);

	LOGGC_LOCK(log);

	if (!list_empty(&log->cqueue)) {
		/*
		 * This ensures that we will keep writing to the journal as long
		 * as there are unwritten commit records
		 */
		target = list_entry(log->cqueue.prev, struct tblock, cqueue);

		if (test_bit(log_FLUSH, &log->flag)) {
			/*
			 * We're already flushing.
			 * if flush_tblk is NULL, we are flushing everything,
			 * so leave it that way.  Otherwise, update it to the
			 * latest transaction
			 */
			if (log->flush_tblk)
				log->flush_tblk = target;
		} else {
			/* Only flush until latest transaction is committed */
			log->flush_tblk = target;
			set_bit(log_FLUSH, &log->flag);

			/*
			 * Initiate I/O on outstanding transactions
			 */
			if (!(log->cflag & logGC_PAGEOUT)) {
				log->cflag |= logGC_PAGEOUT;
				lmGCwrite(log, 0);
			}
		}
	}
	if ((wait > 1) || test_bit(log_SYNCBARRIER, &log->flag)) {
		/* Flush until all activity complete */
		set_bit(log_FLUSH, &log->flag);
		log->flush_tblk = NULL;
	}

	if (wait && target && !(target->flag & tblkGC_COMMITTED)) {
		DECLARE_WAITQUEUE(__wait, current);

		add_wait_queue(&target->gcwait, &__wait);
		set_current_state(TASK_UNINTERRUPTIBLE);
		LOGGC_UNLOCK(log);
		schedule();
		current->state = TASK_RUNNING;
		LOGGC_LOCK(log);
		remove_wait_queue(&target->gcwait, &__wait);
	}
	LOGGC_UNLOCK(log);

	if (wait < 2)
		return;

	list_for_each_entry(sbi, &log->sb_list, log_list) {
		filemap_fdatawrite(sbi->ipbmap->i_mapping);
		filemap_fdatawrite(sbi->ipimap->i_mapping);
		filemap_fdatawrite(sbi->direct_inode->i_mapping);
	}

	/*
	 * If there was recent activity, we may need to wait
	 * for the lazycommit thread to catch up
	 */
	if ((!list_empty(&log->cqueue)) || !list_empty(&log->synclist)) {
		for (i = 0; i < 200; i++) {	/* Too much? */
			msleep(250);
			if (list_empty(&log->cqueue) &&
			    list_empty(&log->synclist))
				break;
		}
	}
	assert(list_empty(&log->cqueue));

#ifdef CONFIG_JFS_DEBUG
	if (!list_empty(&log->synclist)) {
		struct logsyncblk *lp;

		list_for_each_entry(lp, &log->synclist, synclist) {
			if (lp->xflag & COMMIT_PAGE) {
				struct metapage *mp = (struct metapage *)lp;
				dump_mem("orphan metapage", lp,
					 sizeof(struct metapage));
				dump_mem("page", mp->page, sizeof(struct page));
			}
			else
				dump_mem("orphan tblock", lp,
					 sizeof(struct tblock));
		}
	}
#endif
	//assert(list_empty(&log->synclist));
	clear_bit(log_FLUSH, &log->flag);
}

/*
 * NAME:	lmLogShutdown()
 *
 * FUNCTION:	log shutdown at last LogClose().
 *
 *		write log syncpt record.
 *		update super block to set redone flag to 0.
 *
 * PARAMETER:	log	- log inode
 *
 * RETURN:	0	- success
 *			
 * serialization: single last close thread
 */
int lmLogShutdown(struct jfs_log * log)
{
	int rc;
	struct lrd lrd;
	int lsn;
	struct logsuper *logsuper;
	struct lbuf *bpsuper;
	struct lbuf *bp;
	struct logpage *lp;

	jfs_info("lmLogShutdown: log:0x%p", log);

	jfs_flush_journal(log, 2);

	/*
	 * write the last SYNCPT record with syncpoint = 0
	 * (i.e., log redo up to HERE !)
	 */
	lrd.logtid = 0;
	lrd.backchain = 0;
	lrd.type = cpu_to_le16(LOG_SYNCPT);
	lrd.length = 0;
	lrd.log.syncpt.sync = 0;
	
	lsn = lmWriteRecord(log, NULL, &lrd, NULL);
	bp = log->bp;
	lp = (struct logpage *) bp->l_ldata;
	lp->h.eor = lp->t.eor = cpu_to_le16(bp->l_eor);
	lbmWrite(log, log->bp, lbmWRITE | lbmRELEASE | lbmSYNC, 0);
	lbmIOWait(log->bp, lbmFREE);
	log->bp = NULL;

	/*
	 * synchronous update log superblock
	 * mark log state as shutdown cleanly
	 * (i.e., Log does not need to be replayed).
	 */
	if ((rc = lbmRead(log, 1, &bpsuper)))
		goto out;

	logsuper = (struct logsuper *) bpsuper->l_ldata;
	logsuper->state = cpu_to_le32(LOGREDONE);
	logsuper->end = cpu_to_le32(lsn);
	lbmDirectWrite(log, bpsuper, lbmWRITE | lbmRELEASE | lbmSYNC);
	rc = lbmIOWait(bpsuper, lbmFREE);

	jfs_info("lmLogShutdown: lsn:0x%x page:%d eor:%d",
		 lsn, log->page, log->eor);

      out:    
	/*
	 * shutdown per log i/o
	 */
	lbmLogShutdown(log);

	if (rc) {
		jfs_warn("lmLogShutdown: exit(%d)", rc);
	}
	return rc;
}


/*
 * NAME:	lmLogFileSystem()
 *
 * FUNCTION:	insert (<activate> = true)/remove (<activate> = false)
 *	file system into/from log active file system list.
 *
 * PARAMETE:	log	- pointer to logs inode.
 *		fsdev	- kdev_t of filesystem.
 *		serial  - pointer to returned log serial number
 *		activate - insert/remove device from active list.
 *
 * RETURN:	0	- success
 *		errors returned by vms_iowait().
 */
static int lmLogFileSystem(struct jfs_log * log, struct jfs_sb_info *sbi,
			   int activate)
{
	int rc = 0;
	int i;
	struct logsuper *logsuper;
	struct lbuf *bpsuper;
	char *uuid = sbi->uuid;

	/*
	 * insert/remove file system device to log active file system list.
	 */
	if ((rc = lbmRead(log, 1, &bpsuper)))
		return rc;

	logsuper = (struct logsuper *) bpsuper->l_ldata;
	if (activate) {
		for (i = 0; i < MAX_ACTIVE; i++)
			if (!memcmp(logsuper->active[i].uuid, NULL_UUID, 16)) {
				memcpy(logsuper->active[i].uuid, uuid, 16);
				sbi->aggregate = i;
				break;
			}
		if (i == MAX_ACTIVE) {
			jfs_warn("Too many file systems sharing journal!");
			lbmFree(bpsuper);
			return -EMFILE;	/* Is there a better rc? */
		}
	} else {
		for (i = 0; i < MAX_ACTIVE; i++)
			if (!memcmp(logsuper->active[i].uuid, uuid, 16)) {
				memcpy(logsuper->active[i].uuid, NULL_UUID, 16);
				break;
			}
		if (i == MAX_ACTIVE) {
			jfs_warn("Somebody stomped on the journal!");
			lbmFree(bpsuper);
			return -EIO;
		}
		
	}

	/*
	 * synchronous write log superblock:
	 *
	 * write sidestream bypassing write queue:
	 * at file system mount, log super block is updated for
	 * activation of the file system before any log record
	 * (MOUNT record) of the file system, and at file system
	 * unmount, all meta data for the file system has been
	 * flushed before log super block is updated for deactivation
	 * of the file system.
	 */
	lbmDirectWrite(log, bpsuper, lbmWRITE | lbmRELEASE | lbmSYNC);
	rc = lbmIOWait(bpsuper, lbmFREE);

	return rc;
}

/*
 *		log buffer manager (lbm)
 *		------------------------
 *
 * special purpose buffer manager supporting log i/o requirements.
 *
 * per log write queue:
 * log pageout occurs in serial order by fifo write queue and
 * restricting to a single i/o in pregress at any one time.
 * a circular singly-linked list
 * (log->wrqueue points to the tail, and buffers are linked via
 * bp->wrqueue field), and
 * maintains log page in pageout ot waiting for pageout in serial pageout.
 */

/*
 *	lbmLogInit()
 *
 * initialize per log I/O setup at lmLogInit()
 */
static int lbmLogInit(struct jfs_log * log)
{				/* log inode */
	int i;
	struct lbuf *lbuf;

	jfs_info("lbmLogInit: log:0x%p", log);

	/* initialize current buffer cursor */
	log->bp = NULL;

	/* initialize log device write queue */
	log->wqueue = NULL;

	/*
	 * Each log has its own buffer pages allocated to it.  These are
	 * not managed by the page cache.  This ensures that a transaction
	 * writing to the log does not block trying to allocate a page from
	 * the page cache (for the log).  This would be bad, since page
	 * allocation waits on the kswapd thread that may be committing inodes
	 * which would cause log activity.  Was that clear?  I'm trying to
	 * avoid deadlock here.
	 */
	init_waitqueue_head(&log->free_wait);

	log->lbuf_free = NULL;

	for (i = 0; i < LOGPAGES;) {
		char *buffer;
		uint offset;
		struct page *page;

		buffer = (char *) get_zeroed_page(GFP_KERNEL);
		if (buffer == NULL)
			goto error;
		page = virt_to_page(buffer);
		for (offset = 0; offset < PAGE_SIZE; offset += LOGPSIZE) {
			lbuf = kmalloc(sizeof(struct lbuf), GFP_KERNEL);
			if (lbuf == NULL) {
				if (offset == 0)
					free_page((unsigned long) buffer);
				goto error;
			}
			if (offset) /* we already have one reference */
				get_page(page);
			lbuf->l_offset = offset;
			lbuf->l_ldata = buffer + offset;
			lbuf->l_page = page;
			lbuf->l_log = log;
			init_waitqueue_head(&lbuf->l_ioevent);

			lbuf->l_freelist = log->lbuf_free;
			log->lbuf_free = lbuf;
			i++;
		}
	}

	return (0);

      error:
	lbmLogShutdown(log);
	return -ENOMEM;
}


/*
 *	lbmLogShutdown()
 *
 * finalize per log I/O setup at lmLogShutdown()
 */
static void lbmLogShutdown(struct jfs_log * log)
{
	struct lbuf *lbuf;

	jfs_info("lbmLogShutdown: log:0x%p", log);

	lbuf = log->lbuf_free;
	while (lbuf) {
		struct lbuf *next = lbuf->l_freelist;
		__free_page(lbuf->l_page);
		kfree(lbuf);
		lbuf = next;
	}
}


/*
 *	lbmAllocate()
 *
 * allocate an empty log buffer
 */
static struct lbuf *lbmAllocate(struct jfs_log * log, int pn)
{
	struct lbuf *bp;
	unsigned long flags;

	/*
	 * recycle from log buffer freelist if any
	 */
	LCACHE_LOCK(flags);
	LCACHE_SLEEP_COND(log->free_wait, (bp = log->lbuf_free), flags);
	log->lbuf_free = bp->l_freelist;
	LCACHE_UNLOCK(flags);

	bp->l_flag = 0;

	bp->l_wqnext = NULL;
	bp->l_freelist = NULL;

	bp->l_pn = pn;
	bp->l_blkno = log->base + (pn << (L2LOGPSIZE - log->l2bsize));
	bp->l_ceor = 0;

	return bp;
}


/*
 *	lbmFree()
 *
 * release a log buffer to freelist
 */
static void lbmFree(struct lbuf * bp)
{
	unsigned long flags;

	LCACHE_LOCK(flags);

	lbmfree(bp);

	LCACHE_UNLOCK(flags);
}

static void lbmfree(struct lbuf * bp)
{
	struct jfs_log *log = bp->l_log;

	assert(bp->l_wqnext == NULL);

	/*
	 * return the buffer to head of freelist
	 */
	bp->l_freelist = log->lbuf_free;
	log->lbuf_free = bp;

	wake_up(&log->free_wait);
	return;
}


/*
 * NAME:	lbmRedrive
 *
 * FUNCTION:	add a log buffer to the the log redrive list
 *
 * PARAMETER:
 *     bp	- log buffer
 *
 * NOTES:
 *	Takes log_redrive_lock.
 */
static inline void lbmRedrive(struct lbuf *bp)
{
	unsigned long flags;

	spin_lock_irqsave(&log_redrive_lock, flags);
	bp->l_redrive_next = log_redrive_list;
	log_redrive_list = bp;
	spin_unlock_irqrestore(&log_redrive_lock, flags);

	wake_up_process(jfsIOthread);
}


/*
 *	lbmRead()
 */
static int lbmRead(struct jfs_log * log, int pn, struct lbuf ** bpp)
{
	struct bio *bio;
	struct lbuf *bp;

	/*
	 * allocate a log buffer
	 */
	*bpp = bp = lbmAllocate(log, pn);
	jfs_info("lbmRead: bp:0x%p pn:0x%x", bp, pn);

	bp->l_flag |= lbmREAD;

	bio = bio_alloc(GFP_NOFS, 1);

	bio->bi_sector = bp->l_blkno << (log->l2bsize - 9);
	bio->bi_bdev = log->bdev;
	bio->bi_io_vec[0].bv_page = bp->l_page;
	bio->bi_io_vec[0].bv_len = LOGPSIZE;
	bio->bi_io_vec[0].bv_offset = bp->l_offset;

	bio->bi_vcnt = 1;
	bio->bi_idx = 0;
	bio->bi_size = LOGPSIZE;

	bio->bi_end_io = lbmIODone;
	bio->bi_private = bp;
	submit_bio(READ_SYNC, bio);

	wait_event(bp->l_ioevent, (bp->l_flag != lbmREAD));

	return 0;
}


/*
 *	lbmWrite()
 *
 * buffer at head of pageout queue stays after completion of
 * partial-page pageout and redriven by explicit initiation of
 * pageout by caller until full-page pageout is completed and
 * released.
 *
 * device driver i/o done redrives pageout of new buffer at
 * head of pageout queue when current buffer at head of pageout
 * queue is released at the completion of its full-page pageout.
 *
 * LOGGC_LOCK() serializes lbmWrite() by lmNextPage() and lmGroupCommit().
 * LCACHE_LOCK() serializes xflag between lbmWrite() and lbmIODone()
 */
static void lbmWrite(struct jfs_log * log, struct lbuf * bp, int flag,
		     int cant_block)
{
	struct lbuf *tail;
	unsigned long flags;

	jfs_info("lbmWrite: bp:0x%p flag:0x%x pn:0x%x", bp, flag, bp->l_pn);

	/* map the logical block address to physical block address */
	bp->l_blkno =
	    log->base + (bp->l_pn << (L2LOGPSIZE - log->l2bsize));

	LCACHE_LOCK(flags);		/* disable+lock */

	/*
	 * initialize buffer for device driver
	 */
	bp->l_flag = flag;

	/*
	 *      insert bp at tail of write queue associated with log
	 *
	 * (request is either for bp already/currently at head of queue
	 * or new bp to be inserted at tail)
	 */
	tail = log->wqueue;

	/* is buffer not already on write queue ? */
	if (bp->l_wqnext == NULL) {
		/* insert at tail of wqueue */
		if (tail == NULL) {
			log->wqueue = bp;
			bp->l_wqnext = bp;
		} else {
			log->wqueue = bp;
			bp->l_wqnext = tail->l_wqnext;
			tail->l_wqnext = bp;
		}

		tail = bp;
	}

	/* is buffer at head of wqueue and for write ? */
	if ((bp != tail->l_wqnext) || !(flag & lbmWRITE)) {
		LCACHE_UNLOCK(flags);	/* unlock+enable */
		return;
	}

	LCACHE_UNLOCK(flags);	/* unlock+enable */

	if (cant_block)
		lbmRedrive(bp);
	else if (flag & lbmSYNC)
		lbmStartIO(bp);
	else {
		LOGGC_UNLOCK(log);
		lbmStartIO(bp);
		LOGGC_LOCK(log);
	}
}


/*
 *	lbmDirectWrite()
 *
 * initiate pageout bypassing write queue for sidestream
 * (e.g., log superblock) write;
 */
static void lbmDirectWrite(struct jfs_log * log, struct lbuf * bp, int flag)
{
	jfs_info("lbmDirectWrite: bp:0x%p flag:0x%x pn:0x%x",
		 bp, flag, bp->l_pn);

	/*
	 * initialize buffer for device driver
	 */
	bp->l_flag = flag | lbmDIRECT;

	/* map the logical block address to physical block address */
	bp->l_blkno =
	    log->base + (bp->l_pn << (L2LOGPSIZE - log->l2bsize));

	/*
	 *      initiate pageout of the page
	 */
	lbmStartIO(bp);
}


/*
 * NAME:	lbmStartIO()
 *
 * FUNCTION:	Interface to DD strategy routine
 *
 * RETURN:      none
 *
 * serialization: LCACHE_LOCK() is NOT held during log i/o;
 */
static void lbmStartIO(struct lbuf * bp)
{
	struct bio *bio;
	struct jfs_log *log = bp->l_log;

	jfs_info("lbmStartIO\n");

	bio = bio_alloc(GFP_NOFS, 1);
	bio->bi_sector = bp->l_blkno << (log->l2bsize - 9);
	bio->bi_bdev = log->bdev;
	bio->bi_io_vec[0].bv_page = bp->l_page;
	bio->bi_io_vec[0].bv_len = LOGPSIZE;
	bio->bi_io_vec[0].bv_offset = bp->l_offset;

	bio->bi_vcnt = 1;
	bio->bi_idx = 0;
	bio->bi_size = LOGPSIZE;

	bio->bi_end_io = lbmIODone;
	bio->bi_private = bp;

	/* check if journaling to disk has been disabled */
	if (log->no_integrity) {
		bio->bi_size = 0;
		lbmIODone(bio, 0, 0);
	} else {
		submit_bio(WRITE_SYNC, bio);
		INCREMENT(lmStat.submitted);
	}
}


/*
 *	lbmIOWait()
 */
static int lbmIOWait(struct lbuf * bp, int flag)
{
	unsigned long flags;
	int rc = 0;

	jfs_info("lbmIOWait1: bp:0x%p flag:0x%x:0x%x", bp, bp->l_flag, flag);

	LCACHE_LOCK(flags);		/* disable+lock */

	LCACHE_SLEEP_COND(bp->l_ioevent, (bp->l_flag & lbmDONE), flags);

	rc = (bp->l_flag & lbmERROR) ? -EIO : 0;

	if (flag & lbmFREE)
		lbmfree(bp);

	LCACHE_UNLOCK(flags);	/* unlock+enable */

	jfs_info("lbmIOWait2: bp:0x%p flag:0x%x:0x%x", bp, bp->l_flag, flag);
	return rc;
}

/*
 *	lbmIODone()
 *
 * executed at INTIODONE level
 */
static int lbmIODone(struct bio *bio, unsigned int bytes_done, int error)
{
	struct lbuf *bp = bio->bi_private;
	struct lbuf *nextbp, *tail;
	struct jfs_log *log;
	unsigned long flags;

	if (bio->bi_size)
		return 1;

	/*
	 * get back jfs buffer bound to the i/o buffer
	 */
	jfs_info("lbmIODone: bp:0x%p flag:0x%x", bp, bp->l_flag);

	LCACHE_LOCK(flags);		/* disable+lock */

	bp->l_flag |= lbmDONE;

	if (!test_bit(BIO_UPTODATE, &bio->bi_flags)) {
		bp->l_flag |= lbmERROR;

		jfs_err("lbmIODone: I/O error in JFS log");
	}

	bio_put(bio);

	/*
	 *      pagein completion
	 */
	if (bp->l_flag & lbmREAD) {
		bp->l_flag &= ~lbmREAD;

		LCACHE_UNLOCK(flags);	/* unlock+enable */

		/* wakeup I/O initiator */
		LCACHE_WAKEUP(&bp->l_ioevent);

		return 0;
	}

	/*
	 *      pageout completion
	 *
	 * the bp at the head of write queue has completed pageout.
	 *
	 * if single-commit/full-page pageout, remove the current buffer
	 * from head of pageout queue, and redrive pageout with
	 * the new buffer at head of pageout queue;
	 * otherwise, the partial-page pageout buffer stays at
	 * the head of pageout queue to be redriven for pageout
	 * by lmGroupCommit() until full-page pageout is completed.
	 */
	bp->l_flag &= ~lbmWRITE;
	INCREMENT(lmStat.pagedone);

	/* update committed lsn */
	log = bp->l_log;
	log->clsn = (bp->l_pn << L2LOGPSIZE) + bp->l_ceor;

	if (bp->l_flag & lbmDIRECT) {
		LCACHE_WAKEUP(&bp->l_ioevent);
		LCACHE_UNLOCK(flags);
		return 0;
	}

	tail = log->wqueue;

	/* single element queue */
	if (bp == tail) {
		/* remove head buffer of full-page pageout
		 * from log device write queue
		 */
		if (bp->l_flag & lbmRELEASE) {
			log->wqueue = NULL;
			bp->l_wqnext = NULL;
		}
	}
	/* multi element queue */
	else {
		/* remove head buffer of full-page pageout
		 * from log device write queue
		 */
		if (bp->l_flag & lbmRELEASE) {
			nextbp = tail->l_wqnext = bp->l_wqnext;
			bp->l_wqnext = NULL;

			/*
			 * redrive pageout of next page at head of write queue:
			 * redrive next page without any bound tblk
			 * (i.e., page w/o any COMMIT records), or
			 * first page of new group commit which has been
			 * queued after current page (subsequent pageout
			 * is performed synchronously, except page without
			 * any COMMITs) by lmGroupCommit() as indicated
			 * by lbmWRITE flag;
			 */
			if (nextbp->l_flag & lbmWRITE) {
				/*
				 * We can't do the I/O at interrupt time.
				 * The jfsIO thread can do it
				 */
				lbmRedrive(nextbp);
			}
		}
	}

	/*
	 *      synchronous pageout:
	 *
	 * buffer has not necessarily been removed from write queue
	 * (e.g., synchronous write of partial-page with COMMIT):
	 * leave buffer for i/o initiator to dispose
	 */
	if (bp->l_flag & lbmSYNC) {
		LCACHE_UNLOCK(flags);	/* unlock+enable */

		/* wakeup I/O initiator */
		LCACHE_WAKEUP(&bp->l_ioevent);
	}

	/*
	 *      Group Commit pageout:
	 */
	else if (bp->l_flag & lbmGC) {
		LCACHE_UNLOCK(flags);
		lmPostGC(bp);
	}

	/*
	 *      asynchronous pageout:
	 *
	 * buffer must have been removed from write queue:
	 * insert buffer at head of freelist where it can be recycled
	 */
	else {
		assert(bp->l_flag & lbmRELEASE);
		assert(bp->l_flag & lbmFREE);
		lbmfree(bp);

		LCACHE_UNLOCK(flags);	/* unlock+enable */
	}

	return 0;
}

int jfsIOWait(void *arg)
{
	struct lbuf *bp;

	do {
		spin_lock_irq(&log_redrive_lock);
		while ((bp = log_redrive_list) != 0) {
			log_redrive_list = bp->l_redrive_next;
			bp->l_redrive_next = NULL;
			spin_unlock_irq(&log_redrive_lock);
			lbmStartIO(bp);
			spin_lock_irq(&log_redrive_lock);
		}
		spin_unlock_irq(&log_redrive_lock);

		if (freezing(current)) {
			refrigerator();
		} else {
			set_current_state(TASK_INTERRUPTIBLE);
			schedule();
			current->state = TASK_RUNNING;
		}
	} while (!kthread_should_stop());

	jfs_info("jfsIOWait being killed!");
	return 0;
}

/*
 * NAME:	lmLogFormat()/jfs_logform()
 *
 * FUNCTION:	format file system log
 *
 * PARAMETERS:
 *      log	- volume log
 *	logAddress - start address of log space in FS block
 *	logSize	- length of log space in FS block;
 *
 * RETURN:	0	- success
 *		-EIO	- i/o error
 *
 * XXX: We're synchronously writing one page at a time.  This needs to
 *	be improved by writing multiple pages at once.
 */
int lmLogFormat(struct jfs_log *log, s64 logAddress, int logSize)
{
	int rc = -EIO;
	struct jfs_sb_info *sbi;
	struct logsuper *logsuper;
	struct logpage *lp;
	int lspn;		/* log sequence page number */
	struct lrd *lrd_ptr;
	int npages = 0;
	struct lbuf *bp;

	jfs_info("lmLogFormat: logAddress:%Ld logSize:%d",
		 (long long)logAddress, logSize);

	sbi = list_entry(log->sb_list.next, struct jfs_sb_info, log_list);

	/* allocate a log buffer */
	bp = lbmAllocate(log, 1);

	npages = logSize >> sbi->l2nbperpage;

	/*
	 *      log space:
	 *
	 * page 0 - reserved;
	 * page 1 - log superblock;
	 * page 2 - log data page: A SYNC log record is written
	 *          into this page at logform time;
	 * pages 3-N - log data page: set to empty log data pages;
	 */
	/*
	 *      init log superblock: log page 1
	 */
	logsuper = (struct logsuper *) bp->l_ldata;

	logsuper->magic = cpu_to_le32(LOGMAGIC);
	logsuper->version = cpu_to_le32(LOGVERSION);
	logsuper->state = cpu_to_le32(LOGREDONE);
	logsuper->flag = cpu_to_le32(sbi->mntflag);	/* ? */
	logsuper->size = cpu_to_le32(npages);
	logsuper->bsize = cpu_to_le32(sbi->bsize);
	logsuper->l2bsize = cpu_to_le32(sbi->l2bsize);
	logsuper->end = cpu_to_le32(2 * LOGPSIZE + LOGPHDRSIZE + LOGRDSIZE);

	bp->l_flag = lbmWRITE | lbmSYNC | lbmDIRECT;
	bp->l_blkno = logAddress + sbi->nbperpage;
	lbmStartIO(bp);
	if ((rc = lbmIOWait(bp, 0)))
		goto exit;

	/*
	 *      init pages 2 to npages-1 as log data pages:
	 *
	 * log page sequence number (lpsn) initialization:
	 *
	 * pn:   0     1     2     3                 n-1
	 *       +-----+-----+=====+=====+===.....===+=====+
	 * lspn:             N-1   0     1           N-2
	 *                   <--- N page circular file ---->
	 *
	 * the N (= npages-2) data pages of the log is maintained as
	 * a circular file for the log records;
	 * lpsn grows by 1 monotonically as each log page is written
	 * to the circular file of the log;
	 * and setLogpage() will not reset the page number even if
	 * the eor is equal to LOGPHDRSIZE. In order for binary search
	 * still work in find log end process, we have to simulate the
	 * log wrap situation at the log format time.
	 * The 1st log page written will have the highest lpsn. Then
	 * the succeeding log pages will have ascending order of
	 * the lspn starting from 0, ... (N-2)
	 */
	lp = (struct logpage *) bp->l_ldata;
	/*
	 * initialize 1st log page to be written: lpsn = N - 1,
	 * write a SYNCPT log record is written to this page
	 */
	lp->h.page = lp->t.page = cpu_to_le32(npages - 3);
	lp->h.eor = lp->t.eor = cpu_to_le16(LOGPHDRSIZE + LOGRDSIZE);

	lrd_ptr = (struct lrd *) &lp->data;
	lrd_ptr->logtid = 0;
	lrd_ptr->backchain = 0;
	lrd_ptr->type = cpu_to_le16(LOG_SYNCPT);
	lrd_ptr->length = 0;
	lrd_ptr->log.syncpt.sync = 0;

	bp->l_blkno += sbi->nbperpage;
	bp->l_flag = lbmWRITE | lbmSYNC | lbmDIRECT;
	lbmStartIO(bp);
	if ((rc = lbmIOWait(bp, 0)))
		goto exit;

	/*
	 *      initialize succeeding log pages: lpsn = 0, 1, ..., (N-2)
	 */
	for (lspn = 0; lspn < npages - 3; lspn++) {
		lp->h.page = lp->t.page = cpu_to_le32(lspn);
		lp->h.eor = lp->t.eor = cpu_to_le16(LOGPHDRSIZE);

		bp->l_blkno += sbi->nbperpage;
		bp->l_flag = lbmWRITE | lbmSYNC | lbmDIRECT;
		lbmStartIO(bp);
		if ((rc = lbmIOWait(bp, 0)))
			goto exit;
	}

	rc = 0;
exit:
	/*
	 *      finalize log
	 */
	/* release the buffer */
	lbmFree(bp);

	return rc;
}

#ifdef CONFIG_JFS_STATISTICS
int jfs_lmstats_read(char *buffer, char **start, off_t offset, int length,
		      int *eof, void *data)
{
	int len = 0;
	off_t begin;

	len += sprintf(buffer,
		       "JFS Logmgr stats\n"
		       "================\n"
		       "commits = %d\n"
		       "writes submitted = %d\n"
		       "writes completed = %d\n"
		       "full pages submitted = %d\n"
		       "partial pages submitted = %d\n",
		       lmStat.commit,
		       lmStat.submitted,
		       lmStat.pagedone,
		       lmStat.full_page,
		       lmStat.partial_page);

	begin = offset;
	*start = buffer + begin;
	len -= begin;

	if (len > length)
		len = length;
	else
		*eof = 1;

	if (len < 0)
		len = 0;

	return len;
}
#endif /* CONFIG_JFS_STATISTICS */