/*
   *   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/completion.h>

  #include <linux/kthread.h>

  #include <linux/buffer_head.h>		/* for sync_blockdev() */
  #include <linux/bio.h>

  #include <linux/freezer.h>

  #include <linux/export.h>

  #include <linux/delay.h>

  #include <linux/mutex.h>

  #include <linux/seq_file.h>

  #include <linux/slab.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

  static void write_special_inodes(struct jfs_log *log,
  				 int (*writer)(struct address_space *))
  {
  	struct jfs_sb_info *sbi;
  
  	list_for_each_entry(sbi, &log->sb_list, log_list) {
  		writer(sbi->ipbmap->i_mapping);
  		writer(sbi->ipimap->i_mapping);
  		writer(sbi->direct_inode->i_mapping);
  	}
  }

  
  /*
   * 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;

  	unsigned long flags;
  
  	/* push dirty metapages out to disk */

  	if (hard_sync)

  		write_special_inodes(log, filemap_fdatawrite);

  	else

  		write_special_inodes(log, filemap_flush);

  
  	/*

  	 *	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("
   ... Log Wrap ... Log Wrap ... Log Wrap ...
  ");
  		/*

  		 *	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 valid for recovery.

  		 * if crashed during invalid state, log state

  		 * implies invalid 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
  ");

  				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 = blkdev_get_by_dev(sbi->logdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL,
  				 log);

  	if (IS_ERR(bdev)) {

  		rc = PTR_ERR(bdev);

  		goto free;
  	}

  	log->bdev = bdev;
  	memcpy(log->uuid, sbi->loguuid, sizeof(log->uuid));

  	/*
  	 * initialize log:
  	 */
  	if ((rc = lmLogInit(log)))

  		goto close;

  
  	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);

        close:		/* close external log device */

  	blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);

  
        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);

  	blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXCL);

  
  	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;
  
  	/* 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();

  		__set_current_state(TASK_RUNNING);

  		LOGGC_LOCK(log);
  		remove_wait_queue(&target->gcwait, &__wait);
  	}
  	LOGGC_UNLOCK(log);
  
  	if (wait < 2)
  		return;

  	write_special_inodes(log, filemap_fdatawrite);

  	/*
  	 * 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);

  			write_special_inodes(log, filemap_fdatawrite);

  			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;

  		printk(KERN_ERR "jfs_flush_journal: synclist not empty
  ");

  		list_for_each_entry(lp, &log->synclist, synclist) {
  			if (lp->xflag & COMMIT_PAGE) {
  				struct metapage *mp = (struct metapage *)lp;

  				print_hex_dump(KERN_ERR, "metapage: ",
  					       DUMP_PREFIX_ADDRESS, 16, 4,
  					       mp, sizeof(struct metapage), 0);
  				print_hex_dump(KERN_ERR, "page: ",
  					       DUMP_PREFIX_ADDRESS, 16,
  					       sizeof(long), mp->page,
  					       sizeof(struct page), 0);
  			} else
  				print_hex_dump(KERN_ERR, "tblock:",
  					       DUMP_PREFIX_ADDRESS, 16, 4,
  					       lp, sizeof(struct tblock), 0);

  		}

  	}

  #else
  	WARN_ON(!list_empty(&log->synclist));

  #endif

  	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 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
  ");
  
  	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);

  	} 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 void lbmIODone(struct bio *bio, int error)

  {
  	struct lbuf *bp = bio->bi_private;
  	struct lbuf *nextbp, *tail;
  	struct jfs_log *log;
  	unsigned long flags;

  	/*
  	 * 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;

  	}
  
  	/*

  	 *	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;

  	}
  
  	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 */
  	}

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

  	do {

  		spin_lock_irq(&log_redrive_lock);

  		while ((bp = log_redrive_list)) {

  			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);
  		}

  		if (freezing(current)) {

  			spin_unlock_irq(&log_redrive_lock);

  			try_to_freeze();

  		} else {

  			set_current_state(TASK_INTERRUPTIBLE);

  			spin_unlock_irq(&log_redrive_lock);

  			schedule();

  			__set_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

  static int jfs_lmstats_proc_show(struct seq_file *m, void *v)

  {

  	seq_printf(m,

  		       "JFS Logmgr stats
  "
  		       "================
  "
  		       "commits = %d
  "
  		       "writes submitted = %d
  "
  		       "writes completed = %d
  "
  		       "full pages submitted = %d
  "
  		       "partial pages submitted = %d
  ",
  		       lmStat.commit,
  		       lmStat.submitted,
  		       lmStat.pagedone,
  		       lmStat.full_page,
  		       lmStat.partial_page);

  	return 0;
  }

  static int jfs_lmstats_proc_open(struct inode *inode, struct file *file)
  {
  	return single_open(file, jfs_lmstats_proc_show, NULL);

  }

  
  const struct file_operations jfs_lmstats_proc_fops = {
  	.owner		= THIS_MODULE,
  	.open		= jfs_lmstats_proc_open,
  	.read		= seq_read,
  	.llseek		= seq_lseek,
  	.release	= single_release,
  };

  #endif /* CONFIG_JFS_STATISTICS */