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jfs_logmgr.c

/*
 *   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/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();
            __set_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;

            printk(KERN_ERR "jfs_flush_journal: synclist not empty\n");
            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\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);
      } 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) != 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);
            }

            if (freezing(current)) {
                  spin_unlock_irq(&log_redrive_lock);
                  refrigerator();
            } 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
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 */

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