FreeBSD/Linux Kernel Cross Reference
sys/fs/jfs/jfs_logmgr.c

     /*
      *   Copyright (c) International Business Machines Corp., 2000-2002
      *   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/locks.h>
    #include <linux/blkdev.h>
    #include <linux/interrupt.h>
    #include <linux/smp_lock.h>
    #include <linux/completion.h>
    #include "jfs_incore.h"
    #include "jfs_filsys.h"
    #include "jfs_metapage.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 spinlock_t log_redrive_lock = SPIN_LOCK_UNLOCKED;
    DECLARE_WAIT_QUEUE_HEAD(jfs_IO_thread_wait);
    
    
    /*
     *      log read/write serialization (per log)
     */
    #define LOG_LOCK_INIT(log)      init_MUTEX(&(log)->loglock)
    #define LOG_LOCK(log)           down(&((log)->loglock))
    #define LOG_UNLOCK(log)         up(&((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 spinlock_t jfsLCacheLock = SPIN_LOCK_UNLOCKED;
   
   #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
   
   /*
    * external references
    */
   extern void txLazyUnlock(struct tblock * tblk);
   extern int jfs_stop_threads;
   extern struct completion jfsIOwait;
   
   /*
    * 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, char *uuid, int activate);
   
   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 void lbmIODone(struct buffer_head *bh, int);
   static void lbmStartIO(struct lbuf * bp);
   static void lmGCwrite(struct jfs_log * log, int cant_block);
   
   
   /*
    *      statistics
    */
   #ifdef CONFIG_JFS_STATISTICS
   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;
   
           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);
   
           /*
            * 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_del(&tblk->synclist);
                           list_add(&tblk->synclist, &mp->synclist);
                   }
           }
   
           LOGSYNC_UNLOCK(log);
   
           /*
            *      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 */
                           tblk->cqnext = NULL;
                           if (log->cqueue.head) {
                                   log->cqueue.tail->cqnext = tblk;
                                   log->cqueue.tail = tblk;
                           } else
                                   log->cqueue.head = log->cqueue.tail = tblk;
   
                           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 */
           tblk = log->cqueue.tail;
   
           /* 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)) && log->cqueue.head &&
               (!(tblk->xflag & COMMIT_LAZY) || test_bit(log_FLUSH, &log->flag))) {
                   /*
                    * 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;
   
           /*
            * 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 */
           tblk = xtblk = log->cqueue.head;
           gcpn = tblk->pn;
   
           while (tblk && tblk->pn == gcpn) {
                   xtblk = tblk;
   
                   /* state transition: (QUEUE, READY) -> COMMIT */
                   tblk->flag |= tblkGC_COMMIT;
                   tblk = tblk->cqnext;
           }
           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
    */
   void lmPostGC(struct lbuf * bp)
   {
           unsigned long flags;
           struct jfs_log *log = bp->l_log;
           struct logpage *lp;
           struct tblock *tblk;
   
           //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
            */
           while ((tblk = log->cqueue.head) && (tblk->flag & tblkGC_COMMIT)) {
                   /* 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 */
                   log->cqueue.head = tblk->cqnext;
                   if (log->cqueue.head == NULL)
                           log->cqueue.tail = NULL;
                   tblk->flag &= ~tblkGC_QUEUE;
                   tblk->cqnext = 0;
   
                   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 ((tblk = log->cqueue.head) &&
               ((log->gcrtc > 0) || (tblk->bp->l_wqnext != NULL) ||
                test_bit(log_FLUSH, &log->flag)))
                   /*
                    * 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).
    *      if not, explicitly run jfs_blogsync() to initiate
    *      getting of new sync address.
    *      calculate new value of i_nextsync which determines when
    *      this code is called again.
    *
    *      this is called only from lmLog().
    *
    * PARAMETER:   ip      - pointer to logs inode.
    *
    * RETURN:      0
    *                      
    * serialization: LOG_LOCK() held on entry/exit
    */
   int lmLogSync(struct jfs_log * log, int nosyncwait)
   {
           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;
   
           /*
            *      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);
                   /* ToDo: push dirty metapages out to disk */
   //              bmLogSync(log);
   
                   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);
   
           }
   
           /* if sync is different from last syncpt,
            * write a SYNCPT record with syncpt = sync.
            * reset syncpt = sync
            */
           if (log->sync != log->syncpt) {
                   struct super_block *sb = log->sb;
                   struct jfs_sb_info *sbi = JFS_SBI(sb);
   
                   /*
                    * We need to make sure all of the "written" metapages
                    * actually make it to disk
                    */
                   fsync_inode_data_buffers(sbi->ipbmap);
                   fsync_inode_data_buffers(sbi->ipimap);
                   fsync_inode_data_buffers(sb->s_bdev->bd_inode);
   
                   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;
  
          /* return if lmLogSync() from outside of transaction, e.g., sync() */
          if (nosyncwait)
                  return lsn;
  
          /* 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 (written > LOGSYNC_BARRIER(logsize) && logsize > 32 * LOGPSIZE) {
                  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:        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, struct jfs_log ** logptr)
  {
          int rc;
          struct block_device *bdev;
          struct jfs_log *log;
  
          if (!(log = kmalloc(sizeof(struct jfs_log), GFP_KERNEL)))
                  return ENOMEM;
          memset(log, 0, sizeof(struct jfs_log));
          init_waitqueue_head(&log->syncwait);
  
          log->sb = sb;           /* This should be a list */
  
          if (!(JFS_SBI(sb)->mntflag & JFS_INLINELOG))
                  goto externalLog;
  
          /*
           *      in-line log in host file system
           *
           * file system to log have 1-to-1 relationship;
           */
  
          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)))
                  goto free;
          goto out;
  
          /*
           *      external log as separate logical volume
           *
           * file systems to log may have n-to-1 relationship;
           */
        externalLog:
  
          /*
           * TODO: Check for already opened log devices
           */
  
          if (!(bdev = bdget(kdev_t_to_nr(JFS_SBI(sb)->logdev)))) {
                  rc = ENODEV;
                  goto free;
          }
  
          if ((rc = blkdev_get(bdev, FMODE_READ|FMODE_WRITE, 0, BDEV_FS))) {
                  rc = -rc;
                  goto free;
          }
  
          log->bdev = bdev;
          memcpy(log->uuid, JFS_SBI(sb)->loguuid, sizeof(log->uuid));
          
          /*
           * initialize log:
           */
          if ((rc = lmLogInit(log)))
                  goto close;
  
          /*
           * add file system to log active file system list
           */
          if ((rc = lmLogFileSystem(log, JFS_SBI(sb)->uuid, 1)))
                  goto shutdown;
  
        out:
          *logptr = log;
          return 0;
  
          /*
           *      unwind on error
           */
        shutdown:         /* unwind lbmLogInit() */
          lbmLogShutdown(log);
  
        close:            /* close external log device */
          blkdev_put(bdev, BDEV_FS);
  
        free:             /* free log descriptor */
          kfree(log);
  
          jfs_warn("lmLogOpen: exit(%d)", rc);
          return rc;
  }
  
  
  /*
   * NAME:        lmLogInit()
   *
   * FUNCTION:    log initialization at first log open.
   *
   *      logredo() (or logformat()) should have been run previously.
   *      initialize the log inode 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;
  
          jfs_info("lmLogInit: log:0x%p", log);
  
          /*
           * log inode is overlaid on generic inode where
           * dinode have been zeroed out by iRead();
           */
  
          /*
           * initialize log i/o
           */
          if ((rc = lbmLogInit(log)))
                  return rc;
  
          /*
           * validate log superblock
           */
  
  
          if (!test_bit(log_INLINELOG, &log->flag))
                  log->l2bsize = 12;      /* XXX kludge alert XXX */
          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 inode 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));
  
  //      ASSERT(log->eor == lp->h.eor);
  
          log->bp = bp;
          bp->l_pn = log->page;
          bp->l_eor = log->eor;
  
          /* initialize the group commit serialization lock */
          LOGGC_LOCK_INIT(log);
  
          /* if current page is full, move on to next page */
          if (log->eor >= LOGPSIZE - LOGPTLRSIZE)
                  lmNextPage(log);
  
          /* allocate/initialize the log write serialization lock */
          LOG_LOCK_INIT(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;
  
          /* 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);
  
          LOGSYNC_LOCK_INIT(log);
  
          INIT_LIST_HEAD(&log->synclist);
  
          log->cqueue.head = log->cqueue.tail = NULL;
          log->flush_tblk = NULL;
  
          log->count = 0;
  
          /*
           * initialize for lazy/group commit
           */
          log->clsn = lsn;
  
          /*
           * 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;
  
          return 0;
  
          /*
           *      unwind on error
           */
        errout30:         /* release log page */
          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
   *              log     - log inode
   *
   * RETURN:      errors from subroutines
   *
   * serialization:
   */
  int lmLogClose(struct super_block *sb, struct jfs_log * log)
  {
          int rc;
  
          jfs_info("lmLogClose: log:0x%p", log);
  
          if (!test_bit(log_INLINELOG, &log->flag))
                  goto externalLog;
          
          /*
           *      in-line log in host file system
           */
          rc = lmLogShutdown(log);
          goto out;
  
          /*
           *      external log as separate logical volume
           */
        externalLog:
          lmLogFileSystem(log, JFS_SBI(sb)->uuid, 0);
          rc = lmLogShutdown(log);
          blkdev_put(log->bdev, BDEV_FS);
  
        out:
          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;
  
          jfs_info("jfs_flush_journal: log:0x%p wait=%d", log, wait);
  
          LOGGC_LOCK(log);
  
          target = log->cqueue.head;
  
          if (target) {
                  /*
                   * This ensures that we will keep writing to the journal as long
                   * as there are unwritten commit records
                   */
  
                  if (test_bit(log_FLUSH, &log->flag)) {
                          /*
                           * We're already flushing.
                           * if flush_tblk is NULL, we are flushing everything,
                           * so leave it that way.  Otherwise, update it to the
                           * latest transaction
                           */
                          if (log->flush_tblk)
                                  log->flush_tblk = target;
                  } else {
                          /* Only flush until latest transaction is committed */
                          log->flush_tblk = target;
                          set_bit(log_FLUSH, &log->flag);
  
                          /*
                           * Initiate I/O on outstanding transactions
                           */
                          if (!(log->cflag & logGC_PAGEOUT)) {
                                  log->cflag |= logGC_PAGEOUT;
                                  lmGCwrite(log, 0);
                          }
                  }
          }
          if ((wait > 1) || test_bit(log_SYNCBARRIER, &log->flag)) {
                  /* Flush until all activity complete */
                  set_bit(log_FLUSH, &log->flag);
                  log->flush_tblk = NULL;
          }
  
          if (wait && target && !(target->flag & tblkGC_COMMITTED)) {
                  DECLARE_WAITQUEUE(__wait, current);
  
                  add_wait_queue(&target->gcwait, &__wait);
                  set_current_state(TASK_UNINTERRUPTIBLE);
                  LOGGC_UNLOCK(log);
                  schedule();
                  current->state = TASK_RUNNING;
                  LOGGC_LOCK(log);
                  remove_wait_queue(&target->gcwait, &__wait);
          }
          LOGGC_UNLOCK(log);
  
          if (wait < 2)
                  return;
  
          /*
           * If there was recent activity, we may need to wait
           * for the lazycommit thread to catch up
           */
          if (log->cqueue.head || !list_empty(&log->synclist)) {
                  for (i = 0; i < 800; i++) {     /* Too much? */
                          current->state = TASK_INTERRUPTIBLE;
                          schedule_timeout(HZ / 4);
                          if ((log->cqueue.head == NULL) &&
                              list_empty(&log->synclist))
                                  break;
                  }
          }
          assert(log->cqueue.head == NULL);
          assert(list_empty(&log->synclist));
          clear_bit(log_FLUSH, &log->flag);
  }
  
  /*
   * NAME:        lmLogShutdown()
   *
   * FUNCTION:    log shutdown at last LogClose().
   *
   *              write log syncpt record.
   *              update super block to set redone flag to 0.
   *
   * PARAMETER:   log     - log inode
   *
   * RETURN:      0       - success
   *                      
   * serialization: single last close thread
   */
  int lmLogShutdown(struct jfs_log * log)
  {
          int rc;
          struct lrd lrd;
          int lsn;
          struct logsuper *logsuper;
          struct lbuf *bpsuper;
          struct lbuf *bp;
          struct logpage *lp;
  
          jfs_info("lmLogShutdown: log:0x%p", log);
  
          jfs_flush_journal(log, 2);
  
          /*
           * We need to make sure all of the "written" metapages
           * actually make it to disk
           */
          fsync_no_super(log->sb->s_dev);
  
          /*
           * 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);
  
          /*
           * 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, char *uuid, int activate)
  {
          int rc = 0;
          int i;
          struct logsuper *logsuper;
          struct lbuf *bpsuper;
  
          /*
           * 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);
                                  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; i++) {
                  lbuf = kmalloc(sizeof(struct lbuf), GFP_KERNEL);
                  if (lbuf == 0)
                          goto error;
                  lbuf->l_bh.b_data = lbuf->l_ldata =
                      (char *) __get_free_page(GFP_KERNEL);
                  if (lbuf->l_ldata == 0) {
                          kfree(lbuf);
                          goto error;
                  }
                  lbuf->l_log = log;
                  init_waitqueue_head(&lbuf->l_ioevent);
  
                  lbuf->l_bh.b_size = LOGPSIZE;
                  lbuf->l_bh.b_dev = to_kdev_t(log->bdev->bd_dev);
                  lbuf->l_bh.b_end_io = lbmIODone;
                  lbuf->l_bh.b_private = lbuf;
                  lbuf->l_bh.b_page = virt_to_page(lbuf->l_ldata);
                  lbuf->l_bh.b_state = 0;
                  init_waitqueue_head(&lbuf->l_bh.b_wait);
  
                  lbuf->l_freelist = log->lbuf_free;
                  log->lbuf_free = lbuf;
          }
  
          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((unsigned long) lbuf->l_ldata);
                  kfree(lbuf);
                  lbuf = next;
          }
  
          log->bp = NULL;
  }
  
  
  /*
   *      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_bh.b_blocknr = bp->l_blkno;
          bp->l_ceor = 0;
  
          return bp;
  }
  
  
  /*
   *      lbmFree()
   *
   * release a log buffer to freelist
   */
  static void lbmFree(struct lbuf * bp)
  {
          unsigned long flags;
  
          LCACHE_LOCK(flags);
  
          lbmfree(bp);
  
          LCACHE_UNLOCK(flags);
  }
  
  static void lbmfree(struct lbuf * bp)
  {
          struct jfs_log *log = bp->l_log;
  
          assert(bp->l_wqnext == NULL);
  
          /*
           * return the buffer to head of freelist
           */
          bp->l_freelist = log->lbuf_free;
          log->lbuf_free = bp;
  
          wake_up(&log->free_wait);
          return;
  }
  
  
  /*
   * NAME:        lbmRedrive
   *
   * FUNCTION:    add a log buffer to the the log redrive list
   *
   * PARAMETER:
   *     bp       - log buffer
   *
   * NOTES:
   *      Takes log_redrive_lock.
   */
  static inline void lbmRedrive(struct lbuf *bp)
  {
          unsigned long flags;
  
          spin_lock_irqsave(&log_redrive_lock, flags);
          bp->l_redrive_next = log_redrive_list;
          log_redrive_list = bp;
          spin_unlock_irqrestore(&log_redrive_lock, flags);
  
          wake_up(&jfs_IO_thread_wait);
  }
  
  
  /*
   *      lbmRead()
   */
  static int lbmRead(struct jfs_log * log, int pn, struct lbuf ** bpp)
  {
          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;
          bp->l_bh.b_reqnext = NULL;
          clear_bit(BH_Uptodate, &bp->l_bh.b_state);
          lock_buffer(&bp->l_bh);
          set_bit(BH_Mapped, &bp->l_bh.b_state);
          set_bit(BH_Req, &bp->l_bh.b_state);
          bp->l_bh.b_rdev = bp->l_bh.b_dev;
          bp->l_bh.b_rsector = bp->l_blkno << (log->l2bsize - 9);
          generic_make_request(READ, &bp->l_bh);
          run_task_queue(&tq_disk);
  
          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)
  {
          jfs_info("lbmStartIO");
  
          bp->l_bh.b_reqnext = NULL;
          set_bit(BH_Dirty, &bp->l_bh.b_state);
  //      lock_buffer(&bp->l_bh);
          assert(!test_bit(BH_Lock, &bp->l_bh.b_state));
          set_bit(BH_Lock, &bp->l_bh.b_state);
  
          set_bit(BH_Mapped, &bp->l_bh.b_state);
          set_bit(BH_Req, &bp->l_bh.b_state);
          bp->l_bh.b_rdev = bp->l_bh.b_dev;
          bp->l_bh.b_rsector = bp->l_blkno << (bp->l_log->l2bsize - 9);
          generic_make_request(WRITE, &bp->l_bh);
  
          INCREMENT(lmStat.submitted);
          run_task_queue(&tq_disk);
  }
  
  
  /*
   *      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 buffer_head *bh, int uptodate)
  {
          struct lbuf *bp = bh->b_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 */
  
          unlock_buffer(&bp->l_bh);
          bp->l_flag |= lbmDONE;
  
          if (!uptodate) {
                  bp->l_flag |= lbmERROR;
  
                  jfs_err("lbmIODone: I/O error in JFS log");
          }
  
          /*
           *      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;
  
          lock_kernel();
  
          daemonize();
          current->tty = NULL;
          strcpy(current->comm, "jfsIO");
  
          unlock_kernel();
  
          spin_lock_irq(&current->sigmask_lock);
          sigfillset(&current->blocked);
          recalc_sigpending(current);
          spin_unlock_irq(&current->sigmask_lock);
  
          complete(&jfsIOwait);
  
          do {
                  DECLARE_WAITQUEUE(wq, current);
  
                  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);
                  }
                  add_wait_queue(&jfs_IO_thread_wait, &wq);
                  set_current_state(TASK_INTERRUPTIBLE);
                  spin_unlock_irq(&log_redrive_lock);
                  schedule();
                  current->state = TASK_RUNNING;
                  remove_wait_queue(&jfs_IO_thread_wait, &wq);
          } while (!jfs_stop_threads);
  
          jfs_info("jfsIOWait being killed!");
          complete(&jfsIOwait);
          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 = JFS_SBI(log->sb);
          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);
  
          /* 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 */

Cache object: dfd1fd4c1bcd32ebf45ea9bab3b526ca