/*
 *   Copyright (C) International Business Machines Corp., 2000-2005
 *
 *   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_xtree.c: extent allocation descriptor B+-tree manager
 */

#include <linux/fs.h>
#include <linux/quotaops.h>
#include "jfs_incore.h"
#include "jfs_filsys.h"
#include "jfs_metapage.h"
#include "jfs_dmap.h"
#include "jfs_dinode.h"
#include "jfs_superblock.h"
#include "jfs_debug.h"

/*
 * xtree local flag
 */
#define XT_INSERT       0x00000001

/*
 *      xtree key/entry comparison: extent offset
 *
 * return:
 *      -1: k < start of extent
 *       0: start_of_extent <= k <= end_of_extent
 *       1: k > end_of_extent
 */
#define XT_CMP(CMP, K, X, OFFSET64)\
{\
        OFFSET64 = offsetXAD(X);\
        (CMP) = ((K) >= OFFSET64 + lengthXAD(X)) ? 1 :\
                ((K) < OFFSET64) ? -1 : 0;\
}

/* write a xad entry */
#define XT_PUTENTRY(XAD, FLAG, OFF, LEN, ADDR)\
{\
        (XAD)->flag = (FLAG);\
        XADoffset((XAD), (OFF));\
        XADlength((XAD), (LEN));\
        XADaddress((XAD), (ADDR));\
}

#define XT_PAGE(IP, MP) BT_PAGE(IP, MP, xtpage_t, i_xtroot)

/* get page buffer for specified block address */
/* ToDo: Replace this ugly macro with a function */
#define XT_GETPAGE(IP, BN, MP, SIZE, P, RC)\
{\
        BT_GETPAGE(IP, BN, MP, xtpage_t, SIZE, P, RC, i_xtroot)\
        if (!(RC))\
        {\
                if ((le16_to_cpu((P)->header.nextindex) < XTENTRYSTART) ||\
                    (le16_to_cpu((P)->header.nextindex) > le16_to_cpu((P)->header.maxentry)) ||\
                    (le16_to_cpu((P)->header.maxentry) > (((BN)==0)?XTROOTMAXSLOT:PSIZE>>L2XTSLOTSIZE)))\
                {\
                        jfs_error((IP)->i_sb, "XT_GETPAGE: xtree page corrupt");\
                        BT_PUTPAGE(MP);\
                        MP = NULL;\
                        RC = -EIO;\
                }\
        }\
}

/* for consistency */
#define XT_PUTPAGE(MP) BT_PUTPAGE(MP)

#define XT_GETSEARCH(IP, LEAF, BN, MP, P, INDEX) \
        BT_GETSEARCH(IP, LEAF, BN, MP, xtpage_t, P, INDEX, i_xtroot)
/* xtree entry parameter descriptor */
struct xtsplit {
        struct metapage *mp;
        s16 index;
        u8 flag;
        s64 off;
        s64 addr;
        int len;
        struct pxdlist *pxdlist;
};


/*
 *      statistics
 */
#ifdef CONFIG_JFS_STATISTICS
static struct {
        uint search;
        uint fastSearch;
        uint split;
} xtStat;
#endif


/*
 * forward references
 */
static int xtSearch(struct inode *ip, s64 xoff, s64 *next, int *cmpp,
                    struct btstack * btstack, int flag);

static int xtSplitUp(tid_t tid,
                     struct inode *ip,
                     struct xtsplit * split, struct btstack * btstack);

static int xtSplitPage(tid_t tid, struct inode *ip, struct xtsplit * split,
                       struct metapage ** rmpp, s64 * rbnp);

static int xtSplitRoot(tid_t tid, struct inode *ip,
                       struct xtsplit * split, struct metapage ** rmpp);

#ifdef _STILL_TO_PORT
static int xtDeleteUp(tid_t tid, struct inode *ip, struct metapage * fmp,
                      xtpage_t * fp, struct btstack * btstack);

static int xtSearchNode(struct inode *ip,
                        xad_t * xad,
                        int *cmpp, struct btstack * btstack, int flag);

static int xtRelink(tid_t tid, struct inode *ip, xtpage_t * fp);
#endif                          /*  _STILL_TO_PORT */

/*
 *      xtLookup()
 *
 * function: map a single page into a physical extent;
 */
int xtLookup(struct inode *ip, s64 lstart,
             s64 llen, int *pflag, s64 * paddr, s32 * plen, int no_check)
{
        int rc = 0;
        struct btstack btstack;
        int cmp;
        s64 bn;
        struct metapage *mp;
        xtpage_t *p;
        int index;
        xad_t *xad;
        s64 next, size, xoff, xend;
        int xlen;
        s64 xaddr;

        *paddr = 0;
        *plen = llen;

        if (!no_check) {
                /* is lookup offset beyond eof ? */
                size = ((u64) ip->i_size + (JFS_SBI(ip->i_sb)->bsize - 1)) >>
                    JFS_SBI(ip->i_sb)->l2bsize;
                if (lstart >= size) {
                        jfs_err("xtLookup: lstart (0x%lx) >= size (0x%lx)",
                                (ulong) lstart, (ulong) size);
                        return 0;
                }
        }

        /*
         * search for the xad entry covering the logical extent
         */
//search:
        if ((rc = xtSearch(ip, lstart, &next, &cmp, &btstack, 0))) {
                jfs_err("xtLookup: xtSearch returned %d", rc);
                return rc;
        }

        /*
         *      compute the physical extent covering logical extent
         *
         * N.B. search may have failed (e.g., hole in sparse file),
         * and returned the index of the next entry.
         */
        /* retrieve search result */
        XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);

        /* is xad found covering start of logical extent ?
         * lstart is a page start address,
         * i.e., lstart cannot start in a hole;
         */
        if (cmp) {
                if (next)
                        *plen = min(next - lstart, llen);
                goto out;
        }

        /*
         * lxd covered by xad
         */
        xad = &p->xad[index];
        xoff = offsetXAD(xad);
        xlen = lengthXAD(xad);
        xend = xoff + xlen;
        xaddr = addressXAD(xad);

        /* initialize new pxd */
        *pflag = xad->flag;
        *paddr = xaddr + (lstart - xoff);
        /* a page must be fully covered by an xad */
        *plen = min(xend - lstart, llen);

      out:
        XT_PUTPAGE(mp);

        return rc;
}


/*
 *      xtLookupList()
 *
 * function: map a single logical extent into a list of physical extent;
 *
 * parameter:
 *      struct inode    *ip,
 *      struct lxdlist  *lxdlist,       lxd list (in)
 *      struct xadlist  *xadlist,       xad list (in/out)
 *      int             flag)
 *
 * coverage of lxd by xad under assumption of
 * . lxd's are ordered and disjoint.
 * . xad's are ordered and disjoint.
 *
 * return:
 *      0:      success
 *
 * note: a page being written (even a single byte) is backed fully,
 *      except the last page which is only backed with blocks
 *      required to cover the last byte;
 *      the extent backing a page is fully contained within an xad;
 */
int xtLookupList(struct inode *ip, struct lxdlist * lxdlist,
                 struct xadlist * xadlist, int flag)
{
        int rc = 0;
        struct btstack btstack;
        int cmp;
        s64 bn;
        struct metapage *mp;
        xtpage_t *p;
        int index;
        lxd_t *lxd;
        xad_t *xad, *pxd;
        s64 size, lstart, lend, xstart, xend, pstart;
        s64 llen, xlen, plen;
        s64 xaddr, paddr;
        int nlxd, npxd, maxnpxd;

        npxd = xadlist->nxad = 0;
        maxnpxd = xadlist->maxnxad;
        pxd = xadlist->xad;

        nlxd = lxdlist->nlxd;
        lxd = lxdlist->lxd;

        lstart = offsetLXD(lxd);
        llen = lengthLXD(lxd);
        lend = lstart + llen;

        size = (ip->i_size + (JFS_SBI(ip->i_sb)->bsize - 1)) >>
            JFS_SBI(ip->i_sb)->l2bsize;

        /*
         * search for the xad entry covering the logical extent
         */
      search:
        if (lstart >= size)
                return 0;

        if ((rc = xtSearch(ip, lstart, NULL, &cmp, &btstack, 0)))
                return rc;

        /*
         *      compute the physical extent covering logical extent
         *
         * N.B. search may have failed (e.g., hole in sparse file),
         * and returned the index of the next entry.
         */
//map:
        /* retrieve search result */
        XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);

        /* is xad on the next sibling page ? */
        if (index == le16_to_cpu(p->header.nextindex)) {
                if (p->header.flag & BT_ROOT)
                        goto mapend;

                if ((bn = le64_to_cpu(p->header.next)) == 0)
                        goto mapend;

                XT_PUTPAGE(mp);

                /* get next sibling page */
                XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
                if (rc)
                        return rc;

                index = XTENTRYSTART;
        }

        xad = &p->xad[index];

        /*
         * is lxd covered by xad ?
         */
      compare:
        xstart = offsetXAD(xad);
        xlen = lengthXAD(xad);
        xend = xstart + xlen;
        xaddr = addressXAD(xad);

      compare1:
        if (xstart < lstart)
                goto compare2;

        /* (lstart <= xstart) */

        /* lxd is NOT covered by xad */
        if (lend <= xstart) {
                /*
                 * get next lxd
                 */
                if (--nlxd == 0)
                        goto mapend;
                lxd++;

                lstart = offsetLXD(lxd);
                llen = lengthLXD(lxd);
                lend = lstart + llen;
                if (lstart >= size)
                        goto mapend;

                /* compare with the current xad */
                goto compare1;
        }
        /* lxd is covered by xad */
        else {                  /* (xstart < lend) */

                /* initialize new pxd */
                pstart = xstart;
                plen = min(lend - xstart, xlen);
                paddr = xaddr;

                goto cover;
        }

        /* (xstart < lstart) */
      compare2:
        /* lxd is covered by xad */
        if (lstart < xend) {
                /* initialize new pxd */
                pstart = lstart;
                plen = min(xend - lstart, llen);
                paddr = xaddr + (lstart - xstart);

                goto cover;
        }
        /* lxd is NOT covered by xad */
        else {                  /* (xend <= lstart) */

                /*
                 * get next xad
                 *
                 * linear search next xad covering lxd on
                 * the current xad page, and then tree search
                 */
                if (index == le16_to_cpu(p->header.nextindex) - 1) {
                        if (p->header.flag & BT_ROOT)
                                goto mapend;

                        XT_PUTPAGE(mp);
                        goto search;
                } else {
                        index++;
                        xad++;

                        /* compare with new xad */
                        goto compare;
                }
        }

        /*
         * lxd is covered by xad and a new pxd has been initialized
         * (lstart <= xstart < lend) or (xstart < lstart < xend)
         */
      cover:
        /* finalize pxd corresponding to current xad */
        XT_PUTENTRY(pxd, xad->flag, pstart, plen, paddr);

        if (++npxd >= maxnpxd)
                goto mapend;
        pxd++;

        /*
         * lxd is fully covered by xad
         */
        if (lend <= xend) {
                /*
                 * get next lxd
                 */
                if (--nlxd == 0)
                        goto mapend;
                lxd++;

                lstart = offsetLXD(lxd);
                llen = lengthLXD(lxd);
                lend = lstart + llen;
                if (lstart >= size)
                        goto mapend;

                /*
                 * test for old xad covering new lxd
                 * (old xstart < new lstart)
                 */
                goto compare2;
        }
        /*
         * lxd is partially covered by xad
         */
        else {                  /* (xend < lend) */

                /*
                 * get next xad
                 *
                 * linear search next xad covering lxd on
                 * the current xad page, and then next xad page search
                 */
                if (index == le16_to_cpu(p->header.nextindex) - 1) {
                        if (p->header.flag & BT_ROOT)
                                goto mapend;

                        if ((bn = le64_to_cpu(p->header.next)) == 0)
                                goto mapend;

                        XT_PUTPAGE(mp);

                        /* get next sibling page */
                        XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
                        if (rc)
                                return rc;

                        index = XTENTRYSTART;
                        xad = &p->xad[index];
                } else {
                        index++;
                        xad++;
                }

                /*
                 * test for new xad covering old lxd
                 * (old lstart < new xstart)
                 */
                goto compare;
        }

      mapend:
        xadlist->nxad = npxd;

//out:
        XT_PUTPAGE(mp);

        return rc;
}


/*
 *      xtSearch()
 *
 * function:    search for the xad entry covering specified offset.
 *
 * parameters:
 *      ip      - file object;
 *      xoff    - extent offset;
 *      nextp   - address of next extent (if any) for search miss
 *      cmpp    - comparison result:
 *      btstack - traverse stack;
 *      flag    - search process flag (XT_INSERT);
 *
 * returns:
 *      btstack contains (bn, index) of search path traversed to the entry.
 *      *cmpp is set to result of comparison with the entry returned.
 *      the page containing the entry is pinned at exit.
 */
static int xtSearch(struct inode *ip, s64 xoff, s64 *nextp,
                    int *cmpp, struct btstack * btstack, int flag)
{
        struct jfs_inode_info *jfs_ip = JFS_IP(ip);
        int rc = 0;
        int cmp = 1;            /* init for empty page */
        s64 bn;                 /* block number */
        struct metapage *mp;    /* page buffer */
        xtpage_t *p;            /* page */
        xad_t *xad;
        int base, index, lim, btindex;
        struct btframe *btsp;
        int nsplit = 0;         /* number of pages to split */
        s64 t64;
        s64 next = 0;

        INCREMENT(xtStat.search);

        BT_CLR(btstack);

        btstack->nsplit = 0;

        /*
         *      search down tree from root:
         *
         * between two consecutive entries of <Ki, Pi> and <Kj, Pj> of
         * internal page, child page Pi contains entry with k, Ki <= K < Kj.
         *
         * if entry with search key K is not found
         * internal page search find the entry with largest key Ki
         * less than K which point to the child page to search;
         * leaf page search find the entry with smallest key Kj
         * greater than K so that the returned index is the position of
         * the entry to be shifted right for insertion of new entry.
         * for empty tree, search key is greater than any key of the tree.
         *
         * by convention, root bn = 0.
         */
        for (bn = 0;;) {
                /* get/pin the page to search */
                XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
                if (rc)
                        return rc;

                /* try sequential access heuristics with the previous
                 * access entry in target leaf page:
                 * once search narrowed down into the target leaf,
                 * key must either match an entry in the leaf or
                 * key entry does not exist in the tree;
                 */
//fastSearch:
                if ((jfs_ip->btorder & BT_SEQUENTIAL) &&
                    (p->header.flag & BT_LEAF) &&
                    (index = jfs_ip->btindex) <
                    le16_to_cpu(p->header.nextindex)) {
                        xad = &p->xad[index];
                        t64 = offsetXAD(xad);
                        if (xoff < t64 + lengthXAD(xad)) {
                                if (xoff >= t64) {
                                        *cmpp = 0;
                                        goto out;
                                }

                                /* stop sequential access heuristics */
                                goto binarySearch;
                        } else {        /* (t64 + lengthXAD(xad)) <= xoff */

                                /* try next sequential entry */
                                index++;
                                if (index <
                                    le16_to_cpu(p->header.nextindex)) {
                                        xad++;
                                        t64 = offsetXAD(xad);
                                        if (xoff < t64 + lengthXAD(xad)) {
                                                if (xoff >= t64) {
                                                        *cmpp = 0;
                                                        goto out;
                                                }

                                                /* miss: key falls between
                                                 * previous and this entry
                                                 */
                                                *cmpp = 1;
                                                next = t64;
                                                goto out;
                                        }

                                        /* (xoff >= t64 + lengthXAD(xad));
                                         * matching entry may be further out:
                                         * stop heuristic search
                                         */
                                        /* stop sequential access heuristics */
                                        goto binarySearch;
                                }

                                /* (index == p->header.nextindex);
                                 * miss: key entry does not exist in
                                 * the target leaf/tree
                                 */
                                *cmpp = 1;
                                goto out;
                        }

                        /*
                         * if hit, return index of the entry found, and
                         * if miss, where new entry with search key is
                         * to be inserted;
                         */
                      out:
                        /* compute number of pages to split */
                        if (flag & XT_INSERT) {
                                if (p->header.nextindex ==      /* little-endian */
                                    p->header.maxentry)
                                        nsplit++;
                                else
                                        nsplit = 0;
                                btstack->nsplit = nsplit;
                        }

                        /* save search result */
                        btsp = btstack->top;
                        btsp->bn = bn;
                        btsp->index = index;
                        btsp->mp = mp;

                        /* update sequential access heuristics */
                        jfs_ip->btindex = index;

                        if (nextp)
                                *nextp = next;

                        INCREMENT(xtStat.fastSearch);
                        return 0;
                }

                /* well, ... full search now */
              binarySearch:
                lim = le16_to_cpu(p->header.nextindex) - XTENTRYSTART;

                /*
                 * binary search with search key K on the current page
                 */
                for (base = XTENTRYSTART; lim; lim >>= 1) {
                        index = base + (lim >> 1);

                        XT_CMP(cmp, xoff, &p->xad[index], t64);
                        if (cmp == 0) {
                                /*
                                 *      search hit
                                 */
                                /* search hit - leaf page:
                                 * return the entry found
                                 */
                                if (p->header.flag & BT_LEAF) {
                                        *cmpp = cmp;

                                        /* compute number of pages to split */
                                        if (flag & XT_INSERT) {
                                                if (p->header.nextindex ==
                                                    p->header.maxentry)
                                                        nsplit++;
                                                else
                                                        nsplit = 0;
                                                btstack->nsplit = nsplit;
                                        }

                                        /* save search result */
                                        btsp = btstack->top;
                                        btsp->bn = bn;
                                        btsp->index = index;
                                        btsp->mp = mp;

                                        /* init sequential access heuristics */
                                        btindex = jfs_ip->btindex;
                                        if (index == btindex ||
                                            index == btindex + 1)
                                                jfs_ip->btorder = BT_SEQUENTIAL;
                                        else
                                                jfs_ip->btorder = BT_RANDOM;
                                        jfs_ip->btindex = index;

                                        return 0;
                                }
                                /* search hit - internal page:
                                 * descend/search its child page
                                 */
                                if (index < le16_to_cpu(p->header.nextindex)-1)
                                        next = offsetXAD(&p->xad[index + 1]);
                                goto next;
                        }

                        if (cmp > 0) {
                                base = index + 1;
                                --lim;
                        }
                }

                /*
                 *      search miss
                 *
                 * base is the smallest index with key (Kj) greater than
                 * search key (K) and may be zero or maxentry index.
                 */
                if (base < le16_to_cpu(p->header.nextindex))
                        next = offsetXAD(&p->xad[base]);
                /*
                 * search miss - leaf page:
                 *
                 * return location of entry (base) where new entry with
                 * search key K is to be inserted.
                 */
                if (p->header.flag & BT_LEAF) {
                        *cmpp = cmp;

                        /* compute number of pages to split */
                        if (flag & XT_INSERT) {
                                if (p->header.nextindex ==
                                    p->header.maxentry)
                                        nsplit++;
                                else
                                        nsplit = 0;
                                btstack->nsplit = nsplit;
                        }

                        /* save search result */
                        btsp = btstack->top;
                        btsp->bn = bn;
                        btsp->index = base;
                        btsp->mp = mp;

                        /* init sequential access heuristics */
                        btindex = jfs_ip->btindex;
                        if (base == btindex || base == btindex + 1)
                                jfs_ip->btorder = BT_SEQUENTIAL;
                        else
                                jfs_ip->btorder = BT_RANDOM;
                        jfs_ip->btindex = base;

                        if (nextp)
                                *nextp = next;

                        return 0;
                }

                /*
                 * search miss - non-leaf page:
                 *
                 * if base is non-zero, decrement base by one to get the parent
                 * entry of the child page to search.
                 */
                index = base ? base - 1 : base;

                /*
                 * go down to child page
                 */
              next:
                /* update number of pages to split */
                if (p->header.nextindex == p->header.maxentry)
                        nsplit++;
                else
                        nsplit = 0;

                /* push (bn, index) of the parent page/entry */
                if (BT_STACK_FULL(btstack)) {
                        jfs_error(ip->i_sb, "stack overrun in xtSearch!");
                        XT_PUTPAGE(mp);
                        return -EIO;
                }
                BT_PUSH(btstack, bn, index);

                /* get the child page block number */
                bn = addressXAD(&p->xad[index]);

                /* unpin the parent page */
                XT_PUTPAGE(mp);
        }
}

/*
 *      xtInsert()
 *
 * function:
 *
 * parameter:
 *      tid     - transaction id;
 *      ip      - file object;
 *      xflag   - extent flag (XAD_NOTRECORDED):
 *      xoff    - extent offset;
 *      xlen    - extent length;
 *      xaddrp  - extent address pointer (in/out):
 *              if (*xaddrp)
 *                      caller allocated data extent at *xaddrp;
 *              else
 *                      allocate data extent and return its xaddr;
 *      flag    -
 *
 * return:
 */
int xtInsert(tid_t tid,         /* transaction id */
             struct inode *ip, int xflag, s64 xoff, s32 xlen, s64 * xaddrp,
             int flag)
{
        int rc = 0;
        s64 xaddr, hint;
        struct metapage *mp;    /* meta-page buffer */
        xtpage_t *p;            /* base B+-tree index page */
        s64 bn;
        int index, nextindex;
        struct btstack btstack; /* traverse stack */
        struct xtsplit split;   /* split information */
        xad_t *xad;
        int cmp;
        s64 next;
        struct tlock *tlck;
        struct xtlock *xtlck;

        jfs_info("xtInsert: nxoff:0x%lx nxlen:0x%x", (ulong) xoff, xlen);

        /*
         *      search for the entry location at which to insert:
         *
         * xtFastSearch() and xtSearch() both returns (leaf page
         * pinned, index at which to insert).
         * n.b. xtSearch() may return index of maxentry of
         * the full page.
         */
        if ((rc = xtSearch(ip, xoff, &next, &cmp, &btstack, XT_INSERT)))
                return rc;

        /* retrieve search result */
        XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);

        /* This test must follow XT_GETSEARCH since mp must be valid if
         * we branch to out: */
        if ((cmp == 0) || (next && (xlen > next - xoff))) {
                rc = -EEXIST;
                goto out;
        }

        /*
         * allocate data extent requested
         *
         * allocation hint: last xad
         */
        if ((xaddr = *xaddrp) == 0) {
                if (index > XTENTRYSTART) {
                        xad = &p->xad[index - 1];
                        hint = addressXAD(xad) + lengthXAD(xad) - 1;
                } else
                        hint = 0;
                if ((rc = DQUOT_ALLOC_BLOCK(ip, xlen)))
                        goto out;
                if ((rc = dbAlloc(ip, hint, (s64) xlen, &xaddr))) {
                        DQUOT_FREE_BLOCK(ip, xlen);
                        goto out;
                }
        }

        /*
         *      insert entry for new extent
         */
        xflag |= XAD_NEW;

        /*
         *      if the leaf page is full, split the page and
         *      propagate up the router entry for the new page from split
         *
         * The xtSplitUp() will insert the entry and unpin the leaf page.
         */
        nextindex = le16_to_cpu(p->header.nextindex);
        if (nextindex == le16_to_cpu(p->header.maxentry)) {
                split.mp = mp;
                split.index = index;
                split.flag = xflag;
                split.off = xoff;
                split.len = xlen;
                split.addr = xaddr;
                split.pxdlist = NULL;
                if ((rc = xtSplitUp(tid, ip, &split, &btstack))) {
                        /* undo data extent allocation */
                        if (*xaddrp == 0) {
                                dbFree(ip, xaddr, (s64) xlen);
                                DQUOT_FREE_BLOCK(ip, xlen);
                        }
                        return rc;
                }

                *xaddrp = xaddr;
                return 0;
        }

        /*
         *      insert the new entry into the leaf page
         */
        /*
         * acquire a transaction lock on the leaf page;
         *
         * action: xad insertion/extension;
         */
        BT_MARK_DIRTY(mp, ip);

        /* if insert into middle, shift right remaining entries. */
        if (index < nextindex)
                memmove(&p->xad[index + 1], &p->xad[index],
                        (nextindex - index) * sizeof(xad_t));

        /* insert the new entry: mark the entry NEW */
        xad = &p->xad[index];
        XT_PUTENTRY(xad, xflag, xoff, xlen, xaddr);

        /* advance next available entry index */
        p->header.nextindex =
            cpu_to_le16(le16_to_cpu(p->header.nextindex) + 1);

        /* Don't log it if there are no links to the file */
        if (!test_cflag(COMMIT_Nolink, ip)) {
                tlck = txLock(tid, ip, mp, tlckXTREE | tlckGROW);
                xtlck = (struct xtlock *) & tlck->lock;
                xtlck->lwm.offset =
                    (xtlck->lwm.offset) ? min(index,
                                              (int)xtlck->lwm.offset) : index;
                xtlck->lwm.length =
                    le16_to_cpu(p->header.nextindex) - xtlck->lwm.offset;
        }

        *xaddrp = xaddr;

      out:
        /* unpin the leaf page */
        XT_PUTPAGE(mp);

        return rc;
}


/*
 *      xtSplitUp()
 *
 * function:
 *      split full pages as propagating insertion up the tree
 *
 * parameter:
 *      tid     - transaction id;
 *      ip      - file object;
 *      split   - entry parameter descriptor;
 *      btstack - traverse stack from xtSearch()
 *
 * return:
 */
static int
xtSplitUp(tid_t tid,
          struct inode *ip, struct xtsplit * split, struct btstack * btstack)
{
        int rc = 0;
        struct metapage *smp;
        xtpage_t *sp;           /* split page */
        struct metapage *rmp;
        s64 rbn;                /* new right page block number */
        struct metapage *rcmp;
        xtpage_t *rcp;          /* right child page */
        s64 rcbn;               /* right child page block number */
        int skip;               /* index of entry of insertion */
        int nextindex;          /* next available entry index of p */
        struct btframe *parent; /* parent page entry on traverse stack */
        xad_t *xad;
        s64 xaddr;
        int xlen;
        int nsplit;             /* number of pages split */
        struct pxdlist pxdlist;
        pxd_t *pxd;
        struct tlock *tlck;
        struct xtlock *xtlck;

        smp = split->mp;
        sp = XT_PAGE(ip, smp);

        /* is inode xtree root extension/inline EA area free ? */
        if ((sp->header.flag & BT_ROOT) && (!S_ISDIR(ip->i_mode)) &&
            (le16_to_cpu(sp->header.maxentry) < XTROOTMAXSLOT) &&
            (JFS_IP(ip)->mode2 & INLINEEA)) {
                sp->header.maxentry = cpu_to_le16(XTROOTMAXSLOT);
                JFS_IP(ip)->mode2 &= ~INLINEEA;

                BT_MARK_DIRTY(smp, ip);
                /*
                 * acquire a transaction lock on the leaf page;
                 *
                 * action: xad insertion/extension;
                 */

                /* if insert into middle, shift right remaining entries. */
                skip = split->index;
                nextindex = le16_to_cpu(sp->header.nextindex);
                if (skip < nextindex)
                        memmove(&sp->xad[skip + 1], &sp->xad[skip],
                                (nextindex - skip) * sizeof(xad_t));

                /* insert the new entry: mark the entry NEW */
                xad = &sp->xad[skip];
                XT_PUTENTRY(xad, split->flag, split->off, split->len,
                            split->addr);

                /* advance next available entry index */
                sp->header.nextindex =

                    cpu_to_le16(le16_to_cpu(sp->header.nextindex) + 1);

                /* Don't log it if there are no links to the file */
                if (!test_cflag(COMMIT_Nolink, ip)) {
                        tlck = txLock(tid, ip, smp, tlckXTREE | tlckGROW);
                        xtlck = (struct xtlock *) & tlck->lock;
                        xtlck->lwm.offset = (xtlck->lwm.offset) ?
                            min(skip, (int)xtlck->lwm.offset) : skip;
                        xtlck->lwm.length =
                            le16_to_cpu(sp->header.nextindex) -
                            xtlck->lwm.offset;
                }

                return 0;
        }

        /*
         * allocate new index blocks to cover index page split(s)
         *
         * allocation hint: ?
         */
        if (split->pxdlist == NULL) {
                nsplit = btstack->nsplit;
                split->pxdlist = &pxdlist;
                pxdlist.maxnpxd = pxdlist.npxd = 0;
                pxd = &pxdlist.pxd[0];
                xlen = JFS_SBI(ip->i_sb)->nbperpage;
                for (; nsplit > 0; nsplit--, pxd++) {
                        if ((rc = dbAlloc(ip, (s64) 0, (s64) xlen, &xaddr))
                            == 0) {
                                PXDaddress(pxd, xaddr);
                                PXDlength(pxd, xlen);

                                pxdlist.maxnpxd++;

                                continue;
                        }

                        /* undo allocation */

                        XT_PUTPAGE(smp);
                        return rc;
                }
        }

        /*
         * Split leaf page <sp> into <sp> and a new right page <rp>.
         *
         * The split routines insert the new entry into the leaf page,
         * and acquire txLock as appropriate.
         * return <rp> pinned and its block number <rpbn>.
         */
        rc = (sp->header.flag & BT_ROOT) ?
            xtSplitRoot(tid, ip, split, &rmp) :
            xtSplitPage(tid, ip, split, &rmp, &rbn);

        XT_PUTPAGE(smp);

        if (rc)
                return -EIO;
        /*
         * propagate up the router entry for the leaf page just split
         *
         * insert a router entry for the new page into the parent page,
         * propagate the insert/split up the tree by walking back the stack
         * of (bn of parent page, index of child page entry in parent page)
         * that were traversed during the search for the page that split.
         *
         * the propagation of insert/split up the tree stops if the root
         * splits or the page inserted into doesn't have to split to hold
         * the new entry.
         *
         * the parent entry for the split page remains the same, and
         * a new entry is inserted at its right with the first key and
         * block number of the new right page.
         *
         * There are a maximum of 3 pages pinned at any time:
         * right child, left parent and right parent (when the parent splits)
         * to keep the child page pinned while working on the parent.
         * make sure that all pins are released at exit.
         */
        while ((parent = BT_POP(btstack)) != NULL) {
                /* parent page specified by stack frame <parent> */

                /* keep current child pages <rcp> pinned */
                rcmp = rmp;
                rcbn = rbn;
                rcp = XT_PAGE(ip, rcmp);

                /*
                 * insert router entry in parent for new right child page <rp>
                 */
                /* get/pin the parent page <sp> */
                XT_GETPAGE(ip, parent->bn, smp, PSIZE, sp, rc);
                if (rc) {
                        XT_PUTPAGE(rcmp);
                        return rc;
                }

                /*
                 * The new key entry goes ONE AFTER the index of parent entry,
                 * because the split was to the right.
                 */
                skip = parent->index + 1;

                /*
                 * split or shift right remaining entries of the parent page
                 */
                nextindex = le16_to_cpu(sp->header.nextindex);
                /*
                 * parent page is full - split the parent page
                 */
                if (nextindex == le16_to_cpu(sp->header.maxentry)) {
                        /* init for parent page split */
                        split->mp = smp;
                        split->index = skip;    /* index at insert */
                        split->flag = XAD_NEW;
                        split->off = offsetXAD(&rcp->xad[XTENTRYSTART]);
                        split->len = JFS_SBI(ip->i_sb)->nbperpage;
                        split->addr = rcbn;

                        /* unpin previous right child page */
                        XT_PUTPAGE(rcmp);

                        /* The split routines insert the new entry,
                         * and acquire txLock as appropriate.
                         * return <rp> pinned and its block number <rpbn>.
                         */
                        rc = (sp->header.flag & BT_ROOT) ?
                            xtSplitRoot(tid, ip, split, &rmp) :
                            xtSplitPage(tid, ip, split, &rmp, &rbn);
                        if (rc) {
                                XT_PUTPAGE(smp);
                                return rc;
                        }

                        XT_PUTPAGE(smp);
                        /* keep new child page <rp> pinned */
                }
                /*
                 * parent page is not full - insert in parent page
                 */
                else {
                        /*
                         * insert router entry in parent for the right child
                         * page from the first entry of the right child page:
                         */
                        /*
                         * acquire a transaction lock on the parent page;
                         *
                         * action: router xad insertion;
                         */
                        BT_MARK_DIRTY(smp, ip);

                        /*
                         * if insert into middle, shift right remaining entries
                         */
                        if (skip < nextindex)
                                memmove(&sp->xad[skip + 1], &sp->xad[skip],
                                        (nextindex -
                                         skip) << L2XTSLOTSIZE);

                        /* insert the router entry */
                        xad = &sp->xad[skip];
                        XT_PUTENTRY(xad, XAD_NEW,
                                    offsetXAD(&rcp->xad[XTENTRYSTART]),
                                    JFS_SBI(ip->i_sb)->nbperpage, rcbn);

                        /* advance next available entry index. */
                        sp->header.nextindex =
                            cpu_to_le16(le16_to_cpu(sp->header.nextindex) +
                                        1);

                        /* Don't log it if there are no links to the file */
                        if (!test_cflag(COMMIT_Nolink, ip)) {
                                tlck = txLock(tid, ip, smp,
                                              tlckXTREE | tlckGROW);
                                xtlck = (struct xtlock *) & tlck->lock;
                                xtlck->lwm.offset = (xtlck->lwm.offset) ?
                                    min(skip, (int)xtlck->lwm.offset) : skip;
                                xtlck->lwm.length =
                                    le16_to_cpu(sp->header.nextindex) -
                                    xtlck->lwm.offset;
                        }

                        /* unpin parent page */
                        XT_PUTPAGE(smp);

                        /* exit propagate up */
                        break;
                }
        }

        /* unpin current right page */
        XT_PUTPAGE(rmp);

        return 0;
}


/*
 *      xtSplitPage()
 *
 * function:
 *      split a full non-root page into
 *      original/split/left page and new right page
 *      i.e., the original/split page remains as left page.
 *
 * parameter:
 *      int             tid,
 *      struct inode    *ip,
 *      struct xtsplit  *split,
 *      struct metapage **rmpp,
 *      u64             *rbnp,
 *
 * return:
 *      Pointer to page in which to insert or NULL on error.
 */
static int
xtSplitPage(tid_t tid, struct inode *ip,
            struct xtsplit * split, struct metapage ** rmpp, s64 * rbnp)
{
        int rc = 0;
        struct metapage *smp;
        xtpage_t *sp;
        struct metapage *rmp;
        xtpage_t *rp;           /* new right page allocated */
        s64 rbn;                /* new right page block number */
        struct metapage *mp;
        xtpage_t *p;
        s64 nextbn;
        int skip, maxentry, middle, righthalf, n;
        xad_t *xad;
        struct pxdlist *pxdlist;
        pxd_t *pxd;
        struct tlock *tlck;
        struct xtlock *sxtlck = NULL, *rxtlck = NULL;
        int quota_allocation = 0;

        smp = split->mp;
        sp = XT_PAGE(ip, smp);

        INCREMENT(xtStat.split);

        pxdlist = split->pxdlist;
        pxd = &pxdlist->pxd[pxdlist->npxd];
        pxdlist->npxd++;
        rbn = addressPXD(pxd);

        /* Allocate blocks to quota. */
        if (DQUOT_ALLOC_BLOCK(ip, lengthPXD(pxd))) {
                rc = -EDQUOT;
                goto clean_up;
        }

        quota_allocation += lengthPXD(pxd);

        /*
         * allocate the new right page for the split
         */
        rmp = get_metapage(ip, rbn, PSIZE, 1);
        if (rmp == NULL) {
                rc = -EIO;
                goto clean_up;
        }

        jfs_info("xtSplitPage: ip:0x%p smp:0x%p rmp:0x%p", ip, smp, rmp);

        BT_MARK_DIRTY(rmp, ip);
        /*
         * action: new page;
         */

        rp = (xtpage_t *) rmp->data;
        rp->header.self = *pxd;
        rp->header.flag = sp->header.flag & BT_TYPE;
        rp->header.maxentry = sp->header.maxentry;      /* little-endian */
        rp->header.nextindex = cpu_to_le16(XTENTRYSTART);

        BT_MARK_DIRTY(smp, ip);
        /* Don't log it if there are no links to the file */
        if (!test_cflag(COMMIT_Nolink, ip)) {
                /*
                 * acquire a transaction lock on the new right page;
                 */
                tlck = txLock(tid, ip, rmp, tlckXTREE | tlckNEW);
                rxtlck = (struct xtlock *) & tlck->lock;
                rxtlck->lwm.offset = XTENTRYSTART;
                /*
                 * acquire a transaction lock on the split page
                 */
                tlck = txLock(tid, ip, smp, tlckXTREE | tlckGROW);
                sxtlck = (struct xtlock *) & tlck->lock;
        }

        /*
         * initialize/update sibling pointers of <sp> and <rp>
         */
        nextbn = le64_to_cpu(sp->header.next);
        rp->header.next = cpu_to_le64(nextbn);
        rp->header.prev = cpu_to_le64(addressPXD(&sp->header.self));
        sp->header.next = cpu_to_le64(rbn);

        skip = split->index;

        /*
         *      sequential append at tail (after last entry of last page)
         *
         * if splitting the last page on a level because of appending
         * a entry to it (skip is maxentry), it's likely that the access is
         * sequential. adding an empty page on the side of the level is less
         * work and can push the fill factor much higher than normal.
         * if we're wrong it's no big deal -  we will do the split the right
         * way next time.
         * (it may look like it's equally easy to do a similar hack for
         * reverse sorted data, that is, split the tree left, but it's not.
         * Be my guest.)
         */
        if (nextbn == 0 && skip == le16_to_cpu(sp->header.maxentry)) {
                /*
                 * acquire a transaction lock on the new/right page;
                 *
                 * action: xad insertion;
                 */
                /* insert entry at the first entry of the new right page */
                xad = &rp->xad[XTENTRYSTART];
                XT_PUTENTRY(xad, split->flag, split->off, split->len,
                            split->addr);

                rp->header.nextindex = cpu_to_le16(XTENTRYSTART + 1);

                if (!test_cflag(COMMIT_Nolink, ip)) {
                        /* rxtlck->lwm.offset = XTENTRYSTART; */
                        rxtlck->lwm.length = 1;
                }

                *rmpp = rmp;
                *rbnp = rbn;

                jfs_info("xtSplitPage: sp:0x%p rp:0x%p", sp, rp);
                return 0;
        }

        /*
         *      non-sequential insert (at possibly middle page)
         */

        /*
         * update previous pointer of old next/right page of <sp>
         */
        if (nextbn != 0) {
                XT_GETPAGE(ip, nextbn, mp, PSIZE, p, rc);
                if (rc) {
                        XT_PUTPAGE(rmp);
                        goto clean_up;
                }

                BT_MARK_DIRTY(mp, ip);
                /*
                 * acquire a transaction lock on the next page;
                 *
                 * action:sibling pointer update;
                 */
                if (!test_cflag(COMMIT_Nolink, ip))
                        tlck = txLock(tid, ip, mp, tlckXTREE | tlckRELINK);

                p->header.prev = cpu_to_le64(rbn);

                /* sibling page may have been updated previously, or
                 * it may be updated later;
                 */

                XT_PUTPAGE(mp);
        }

        /*
         * split the data between the split and new/right pages
         */
        maxentry = le16_to_cpu(sp->header.maxentry);
        middle = maxentry >> 1;
        righthalf = maxentry - middle;

        /*
         * skip index in old split/left page - insert into left page:
         */
        if (skip <= middle) {
                /* move right half of split page to the new right page */
                memmove(&rp->xad[XTENTRYSTART], &sp->xad[middle],
                        righthalf << L2XTSLOTSIZE);

                /* shift right tail of left half to make room for new entry */
                if (skip < middle)
                        memmove(&sp->xad[skip + 1], &sp->xad[skip],
                                (middle - skip) << L2XTSLOTSIZE);

                /* insert new entry */
                xad = &sp->xad[skip];
                XT_PUTENTRY(xad, split->flag, split->off, split->len,
                            split->addr);

                /* update page header */
                sp->header.nextindex = cpu_to_le16(middle + 1);
                if (!test_cflag(COMMIT_Nolink, ip)) {
                        sxtlck->lwm.offset = (sxtlck->lwm.offset) ?
                            min(skip, (int)sxtlck->lwm.offset) : skip;
                }

                rp->header.nextindex =
                    cpu_to_le16(XTENTRYSTART + righthalf);
        }
        /*
         * skip index in new right page - insert into right page:
         */
        else {
                /* move left head of right half to right page */
                n = skip - middle;
                memmove(&rp->xad[XTENTRYSTART], &sp->xad[middle],
                        n << L2XTSLOTSIZE);

                /* insert new entry */
                n += XTENTRYSTART;
                xad = &rp->xad[n];
                XT_PUTENTRY(xad, split->flag, split->off, split->len,
                            split->addr);

                /* move right tail of right half to right page */
                if (skip < maxentry)
                        memmove(&rp->xad[n + 1], &sp->xad[skip],
                                (maxentry - skip) << L2XTSLOTSIZE);

                /* update page header */
                sp->header.nextindex = cpu_to_le16(middle);
                if (!test_cflag(COMMIT_Nolink, ip)) {
                        sxtlck->lwm.offset = (sxtlck->lwm.offset) ?
                            min(middle, (int)sxtlck->lwm.offset) : middle;
                }

                rp->header.nextindex = cpu_to_le16(XTENTRYSTART +
                                                   righthalf + 1);
        }

        if (!test_cflag(COMMIT_Nolink, ip)) {
                sxtlck->lwm.length = le16_to_cpu(sp->header.nextindex) -
                    sxtlck->lwm.offset;

                /* rxtlck->lwm.offset = XTENTRYSTART; */
                rxtlck->lwm.length = le16_to_cpu(rp->header.nextindex) -
                    XTENTRYSTART;
        }

        *rmpp = rmp;
        *rbnp = rbn;

        jfs_info("xtSplitPage: sp:0x%p rp:0x%p", sp, rp);
        return rc;

      clean_up:

        /* Rollback quota allocation. */
        if (quota_allocation)
                DQUOT_FREE_BLOCK(ip, quota_allocation);

        return (rc);
}


/*
 *      xtSplitRoot()
 *
 * function:
 *      split the full root page into original/root/split page and new
 *      right page
 *      i.e., root remains fixed in tree anchor (inode) and the root is
 *      copied to a single new right child page since root page <<
 *      non-root page, and the split root page contains a single entry
 *      for the new right child page.
 *
 * parameter:
 *      int             tid,
 *      struct inode    *ip,
 *      struct xtsplit  *split,
 *      struct metapage **rmpp)
 *
 * return:
 *      Pointer to page in which to insert or NULL on error.
 */
static int
xtSplitRoot(tid_t tid,
            struct inode *ip, struct xtsplit * split, struct metapage ** rmpp)
{
        xtpage_t *sp;
        struct metapage *rmp;
        xtpage_t *rp;
        s64 rbn;
        int skip, nextindex;
        xad_t *xad;
        pxd_t *pxd;
        struct pxdlist *pxdlist;
        struct tlock *tlck;
        struct xtlock *xtlck;

        sp = &JFS_IP(ip)->i_xtroot;

        INCREMENT(xtStat.split);

        /*
         *      allocate a single (right) child page
         */
        pxdlist = split->pxdlist;
        pxd = &pxdlist->pxd[pxdlist->npxd];
        pxdlist->npxd++;
        rbn = addressPXD(pxd);
        rmp = get_metapage(ip, rbn, PSIZE, 1);
        if (rmp == NULL)
                return -EIO;

        /* Allocate blocks to quota. */
        if (DQUOT_ALLOC_BLOCK(ip, lengthPXD(pxd))) {
                release_metapage(rmp);
                return -EDQUOT;
        }

        jfs_info("xtSplitRoot: ip:0x%p rmp:0x%p", ip, rmp);

        /*
         * acquire a transaction lock on the new right page;
         *
         * action: new page;
         */
        BT_MARK_DIRTY(rmp, ip);

        rp = (xtpage_t *) rmp->data;
        rp->header.flag =
            (sp->header.flag & BT_LEAF) ? BT_LEAF : BT_INTERNAL;
        rp->header.self = *pxd;
        rp->header.nextindex = cpu_to_le16(XTENTRYSTART);
        rp->header.maxentry = cpu_to_le16(PSIZE >> L2XTSLOTSIZE);

        /* initialize sibling pointers */
        rp->header.next = 0;
        rp->header.prev = 0;

        /*
         * copy the in-line root page into new right page extent
         */
        nextindex = le16_to_cpu(sp->header.maxentry);
        memmove(&rp->xad[XTENTRYSTART], &sp->xad[XTENTRYSTART],
                (nextindex - XTENTRYSTART) << L2XTSLOTSIZE);

        /*
         * insert the new entry into the new right/child page
         * (skip index in the new right page will not change)
         */
        skip = split->index;
        /* if insert into middle, shift right remaining entries */
        if (skip != nextindex)
                memmove(&rp->xad[skip + 1], &rp->xad[skip],
                        (nextindex - skip) * sizeof(xad_t));

        xad = &rp->xad[skip];
        XT_PUTENTRY(xad, split->flag, split->off, split->len, split->addr);

        /* update page header */
        rp->header.nextindex = cpu_to_le16(nextindex + 1);

        if (!test_cflag(COMMIT_Nolink, ip)) {
                tlck = txLock(tid, ip, rmp, tlckXTREE | tlckNEW);
                xtlck = (struct xtlock *) & tlck->lock;
                xtlck->lwm.offset = XTENTRYSTART;
                xtlck->lwm.length = le16_to_cpu(rp->header.nextindex) -
                    XTENTRYSTART;
        }

        /*
         *      reset the root
         *
         * init root with the single entry for the new right page
         * set the 1st entry offset to 0, which force the left-most key
         * at any level of the tree to be less than any search key.
         */
        /*
         * acquire a transaction lock on the root page (in-memory inode);
         *
         * action: root split;
         */
        BT_MARK_DIRTY(split->mp, ip);

        xad = &sp->xad[XTENTRYSTART];
        XT_PUTENTRY(xad, XAD_NEW, 0, JFS_SBI(ip->i_sb)->nbperpage, rbn);

        /* update page header of root */
        sp->header.flag &= ~BT_LEAF;
        sp->header.flag |= BT_INTERNAL;

        sp->header.nextindex = cpu_to_le16(XTENTRYSTART + 1);

        if (!test_cflag(COMMIT_Nolink, ip)) {
                tlck = txLock(tid, ip, split->mp, tlckXTREE | tlckGROW);
                xtlck = (struct xtlock *) & tlck->lock;
                xtlck->lwm.offset = XTENTRYSTART;
                xtlck->lwm.length = 1;
        }

        *rmpp = rmp;

        jfs_info("xtSplitRoot: sp:0x%p rp:0x%p", sp, rp);
        return 0;
}


/*
 *      xtExtend()
 *
 * function: extend in-place;
 *
 * note: existing extent may or may not have been committed.
 * caller is responsible for pager buffer cache update, and
 * working block allocation map update;
 * update pmap: alloc whole extended extent;
 */
int xtExtend(tid_t tid,         /* transaction id */
             struct inode *ip, s64 xoff,        /* delta extent offset */
             s32 xlen,          /* delta extent length */
             int flag)
{
        int rc = 0;
        int cmp;
        struct metapage *mp;    /* meta-page buffer */
        xtpage_t *p;            /* base B+-tree index page */
        s64 bn;
        int index, nextindex, len;
        struct btstack btstack; /* traverse stack */
        struct xtsplit split;   /* split information */
        xad_t *xad;
        s64 xaddr;
        struct tlock *tlck;
        struct xtlock *xtlck = NULL;

        jfs_info("xtExtend: nxoff:0x%lx nxlen:0x%x", (ulong) xoff, xlen);

        /* there must exist extent to be extended */
        if ((rc = xtSearch(ip, xoff - 1, NULL, &cmp, &btstack, XT_INSERT)))
                return rc;

        /* retrieve search result */
        XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);

        if (cmp != 0) {
                XT_PUTPAGE(mp);
                jfs_error(ip->i_sb, "xtExtend: xtSearch did not find extent");
                return -EIO;
        }

        /* extension must be contiguous */
        xad = &p->xad[index];
        if ((offsetXAD(xad) + lengthXAD(xad)) != xoff) {
                XT_PUTPAGE(mp);
                jfs_error(ip->i_sb, "xtExtend: extension is not contiguous");
                return -EIO;
        }

        /*
         * acquire a transaction lock on the leaf page;
         *
         * action: xad insertion/extension;
         */
        BT_MARK_DIRTY(mp, ip);
        if (!test_cflag(COMMIT_Nolink, ip)) {
                tlck = txLock(tid, ip, mp, tlckXTREE | tlckGROW);
                xtlck = (struct xtlock *) & tlck->lock;
        }

        /* extend will overflow extent ? */
        xlen = lengthXAD(xad) + xlen;
        if ((len = xlen - MAXXLEN) <= 0)
                goto extendOld;

        /*
         *      extent overflow: insert entry for new extent
         */
//insertNew:
        xoff = offsetXAD(xad) + MAXXLEN;
        xaddr = addressXAD(xad) + MAXXLEN;
        nextindex = le16_to_cpu(p->header.nextindex);

        /*
         *      if the leaf page is full, insert the new entry and
         *      propagate up the router entry for the new page from split
         *
         * The xtSplitUp() will insert the entry and unpin the leaf page.
         */
        if (nextindex == le16_to_cpu(p->header.maxentry)) {
                /* xtSpliUp() unpins leaf pages */
                split.mp = mp;
                split.index = index + 1;
                split.flag = XAD_NEW;
                split.off = xoff;       /* split offset */
                split.len = len;
                split.addr = xaddr;
                split.pxdlist = NULL;
                if ((rc = xtSplitUp(tid, ip, &split, &btstack)))
                        return rc;

                /* get back old page */
                XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
                if (rc)
                        return rc;
                /*
                 * if leaf root has been split, original root has been
                 * copied to new child page, i.e., original entry now
                 * resides on the new child page;
                 */
                if (p->header.flag & BT_INTERNAL) {
                        ASSERT(p->header.nextindex ==
                               cpu_to_le16(XTENTRYSTART + 1));
                        xad = &p->xad[XTENTRYSTART];
                        bn = addressXAD(xad);
                        XT_PUTPAGE(mp);

                        /* get new child page */
                        XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
                        if (rc)
                                return rc;

                        BT_MARK_DIRTY(mp, ip);
                        if (!test_cflag(COMMIT_Nolink, ip)) {
                                tlck = txLock(tid, ip, mp, tlckXTREE|tlckGROW);
                                xtlck = (struct xtlock *) & tlck->lock;
                        }
                }
        }
        /*
         *      insert the new entry into the leaf page
         */
        else {
                /* insert the new entry: mark the entry NEW */
                xad = &p->xad[index + 1];
                XT_PUTENTRY(xad, XAD_NEW, xoff, len, xaddr);

                /* advance next available entry index */
                p->header.nextindex =
                    cpu_to_le16(le16_to_cpu(p->header.nextindex) + 1);
        }

        /* get back old entry */
        xad = &p->xad[index];
        xlen = MAXXLEN;

        /*
         * extend old extent
         */
      extendOld:
        XADlength(xad, xlen);
        if (!(xad->flag & XAD_NEW))
                xad->flag |= XAD_EXTENDED;

        if (!test_cflag(COMMIT_Nolink, ip)) {
                xtlck->lwm.offset =
                    (xtlck->lwm.offset) ? min(index,
                                              (int)xtlck->lwm.offset) : index;
                xtlck->lwm.length =
                    le16_to_cpu(p->header.nextindex) - xtlck->lwm.offset;
        }

        /* unpin the leaf page */
        XT_PUTPAGE(mp);

        return rc;
}

#ifdef _NOTYET
/*
 *      xtTailgate()
 *
 * function: split existing 'tail' extent
 *      (split offset >= start offset of tail extent), and
 *      relocate and extend the split tail half;
 *
 * note: existing extent may or may not have been committed.
 * caller is responsible for pager buffer cache update, and
 * working block allocation map update;
 * update pmap: free old split tail extent, alloc new extent;
 */
int xtTailgate(tid_t tid,               /* transaction id */
               struct inode *ip, s64 xoff,      /* split/new extent offset */
               s32 xlen,        /* new extent length */
               s64 xaddr,       /* new extent address */
               int flag)
{
        int rc = 0;
        int cmp;
        struct metapage *mp;    /* meta-page buffer */
        xtpage_t *p;            /* base B+-tree index page */
        s64 bn;
        int index, nextindex, llen, rlen;
        struct btstack btstack; /* traverse stack */
        struct xtsplit split;   /* split information */
        xad_t *xad;
        struct tlock *tlck;
        struct xtlock *xtlck = 0;
        struct tlock *mtlck;
        struct maplock *pxdlock;

/*
printf("xtTailgate: nxoff:0x%lx nxlen:0x%x nxaddr:0x%lx\n",
        (ulong)xoff, xlen, (ulong)xaddr);
*/

        /* there must exist extent to be tailgated */
        if ((rc = xtSearch(ip, xoff, NULL, &cmp, &btstack, XT_INSERT)))
                return rc;

        /* retrieve search result */
        XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);

        if (cmp != 0) {
                XT_PUTPAGE(mp);
                jfs_error(ip->i_sb, "xtTailgate: couldn't find extent");
                return -EIO;
        }

        /* entry found must be last entry */
        nextindex = le16_to_cpu(p->header.nextindex);
        if (index != nextindex - 1) {
                XT_PUTPAGE(mp);
                jfs_error(ip->i_sb,
                          "xtTailgate: the entry found is not the last entry");
                return -EIO;
        }

        BT_MARK_DIRTY(mp, ip);
        /*
         * acquire tlock of the leaf page containing original entry
         */
        if (!test_cflag(COMMIT_Nolink, ip)) {
                tlck = txLock(tid, ip, mp, tlckXTREE | tlckGROW);
                xtlck = (struct xtlock *) & tlck->lock;
        }

        /* completely replace extent ? */
        xad = &p->xad[index];
/*
printf("xtTailgate: xoff:0x%lx xlen:0x%x xaddr:0x%lx\n",
        (ulong)offsetXAD(xad), lengthXAD(xad), (ulong)addressXAD(xad));
*/
        if ((llen = xoff - offsetXAD(xad)) == 0)
                goto updateOld;

        /*
         *      partially replace extent: insert entry for new extent
         */
//insertNew:
        /*
         *      if the leaf page is full, insert the new entry and
         *      propagate up the router entry for the new page from split
         *
         * The xtSplitUp() will insert the entry and unpin the leaf page.
         */
        if (nextindex == le16_to_cpu(p->header.maxentry)) {
                /* xtSpliUp() unpins leaf pages */
                split.mp = mp;
                split.index = index + 1;
                split.flag = XAD_NEW;
                split.off = xoff;       /* split offset */
                split.len = xlen;
                split.addr = xaddr;
                split.pxdlist = NULL;
                if ((rc = xtSplitUp(tid, ip, &split, &btstack)))
                        return rc;

                /* get back old page */
                XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
                if (rc)
                        return rc;
                /*
                 * if leaf root has been split, original root has been
                 * copied to new child page, i.e., original entry now
                 * resides on the new child page;
                 */
                if (p->header.flag & BT_INTERNAL) {
                        ASSERT(p->header.nextindex ==
                               cpu_to_le16(XTENTRYSTART + 1));
                        xad = &p->xad[XTENTRYSTART];
                        bn = addressXAD(xad);
                        XT_PUTPAGE(mp);

                        /* get new child page */
                        XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
                        if (rc)
                                return rc;

                        BT_MARK_DIRTY(mp, ip);
                        if (!test_cflag(COMMIT_Nolink, ip)) {
                                tlck = txLock(tid, ip, mp, tlckXTREE|tlckGROW);
                                xtlck = (struct xtlock *) & tlck->lock;
                        }
                }
        }
        /*
         *      insert the new entry into the leaf page
         */
        else {
                /* insert the new entry: mark the entry NEW */
                xad = &p->xad[index + 1];
                XT_PUTENTRY(xad, XAD_NEW, xoff, xlen, xaddr);

                /* advance next available entry index */
                p->header.nextindex =
                    cpu_to_le16(le16_to_cpu(p->header.nextindex) + 1);
        }

        /* get back old XAD */
        xad = &p->xad[index];

        /*
         * truncate/relocate old extent at split offset
         */
      updateOld:
        /* update dmap for old/committed/truncated extent */
        rlen = lengthXAD(xad) - llen;
        if (!(xad->flag & XAD_NEW)) {
                /* free from PWMAP at commit */
                if (!test_cflag(COMMIT_Nolink, ip)) {
                        mtlck = txMaplock(tid, ip, tlckMAP);
                        pxdlock = (struct maplock *) & mtlck->lock;
                        pxdlock->flag = mlckFREEPXD;
                        PXDaddress(&pxdlock->pxd, addressXAD(xad) + llen);
                        PXDlength(&pxdlock->pxd, rlen);
                        pxdlock->index = 1;
                }
        } else
                /* free from WMAP */
                dbFree(ip, addressXAD(xad) + llen, (s64) rlen);

        if (llen)
                /* truncate */
                XADlength(xad, llen);
        else
                /* replace */
                XT_PUTENTRY(xad, XAD_NEW, xoff, xlen, xaddr);

        if (!test_cflag(COMMIT_Nolink, ip)) {
                xtlck->lwm.offset = (xtlck->lwm.offset) ?
                    min(index, (int)xtlck->lwm.offset) : index;
                xtlck->lwm.length = le16_to_cpu(p->header.nextindex) -
                    xtlck->lwm.offset;
        }

        /* unpin the leaf page */
        XT_PUTPAGE(mp);

        return rc;
}
#endif /* _NOTYET */

/*
 *      xtUpdate()
 *
 * function: update XAD;
 *
 *      update extent for allocated_but_not_recorded or
 *      compressed extent;
 *
 * parameter:
 *      nxad    - new XAD;
 *              logical extent of the specified XAD must be completely
 *              contained by an existing XAD;
 */
int xtUpdate(tid_t tid, struct inode *ip, xad_t * nxad)
{                               /* new XAD */
        int rc = 0;
        int cmp;
        struct metapage *mp;    /* meta-page buffer */
        xtpage_t *p;            /* base B+-tree index page */
        s64 bn;
        int index0, index, newindex, nextindex;
        struct btstack btstack; /* traverse stack */
        struct xtsplit split;   /* split information */
        xad_t *xad, *lxad, *rxad;
        int xflag;
        s64 nxoff, xoff;
        int nxlen, xlen, lxlen, rxlen;
        s64 nxaddr, xaddr;
        struct tlock *tlck;
        struct xtlock *xtlck = NULL;
        int newpage = 0;

        /* there must exist extent to be tailgated */
        nxoff = offsetXAD(nxad);
        nxlen = lengthXAD(nxad);
        nxaddr = addressXAD(nxad);

        if ((rc = xtSearch(ip, nxoff, NULL, &cmp, &btstack, XT_INSERT)))
                return rc;

        /* retrieve search result */
        XT_GETSEARCH(ip, btstack.top, bn, mp, p, index0);

        if (cmp != 0) {
                XT_PUTPAGE(mp);

                jfs_error(ip->i_sb, "xtUpdate: Could not find extent");
                return -EIO;
        }

        BT_MARK_DIRTY(mp, ip);
        /*
         * acquire tlock of the leaf page containing original entry
         */
        if (!test_cflag(COMMIT_Nolink, ip)) {
                tlck = txLock(tid, ip, mp, tlckXTREE | tlckGROW);
                xtlck = (struct xtlock *) & tlck->lock;
        }

        xad = &p->xad[index0];
        xflag = xad->flag;
        xoff = offsetXAD(xad);
        xlen = lengthXAD(xad);
        xaddr = addressXAD(xad);

        /* nXAD must be completely contained within XAD */
        if ((xoff > nxoff) ||
            (nxoff + nxlen > xoff + xlen)) {
                XT_PUTPAGE(mp);
                jfs_error(ip->i_sb,
                          "xtUpdate: nXAD in not completely contained within XAD");
                return -EIO;
        }

        index = index0;
        newindex = index + 1;
        nextindex = le16_to_cpu(p->header.nextindex);

#ifdef  _JFS_WIP_NOCOALESCE
        if (xoff < nxoff)
                goto updateRight;

        /*
         * replace XAD with nXAD
         */
      replace:                  /* (nxoff == xoff) */
        if (nxlen == xlen) {
                /* replace XAD with nXAD:recorded */
                *xad = *nxad;
                xad->flag = xflag & ~XAD_NOTRECORDED;

                goto out;
        } else                  /* (nxlen < xlen) */
                goto updateLeft;
#endif                          /* _JFS_WIP_NOCOALESCE */

/* #ifdef _JFS_WIP_COALESCE */
        if (xoff < nxoff)
                goto coalesceRight;

        /*
         * coalesce with left XAD
         */
//coalesceLeft: /* (xoff == nxoff) */
        /* is XAD first entry of page ? */
        if (index == XTENTRYSTART)
                goto replace;

        /* is nXAD logically and physically contiguous with lXAD ? */
        lxad = &p->xad[index - 1];
        lxlen = lengthXAD(lxad);
        if (!(lxad->flag & XAD_NOTRECORDED) &&
            (nxoff == offsetXAD(lxad) + lxlen) &&
            (nxaddr == addressXAD(lxad) + lxlen) &&
            (lxlen + nxlen < MAXXLEN)) {
                /* extend right lXAD */
                index0 = index - 1;
                XADlength(lxad, lxlen + nxlen);

                /* If we just merged two extents together, need to make sure the
                 * right extent gets logged.  If the left one is marked XAD_NEW,
                 * then we know it will be logged.  Otherwise, mark as
                 * XAD_EXTENDED
                 */
                if (!(lxad->flag & XAD_NEW))
                        lxad->flag |= XAD_EXTENDED;

                if (xlen > nxlen) {
                        /* truncate XAD */
                        XADoffset(xad, xoff + nxlen);
                        XADlength(xad, xlen - nxlen);
                        XADaddress(xad, xaddr + nxlen);
                        goto out;
                } else {        /* (xlen == nxlen) */

                        /* remove XAD */
                        if (index < nextindex - 1)
                                memmove(&p->xad[index], &p->xad[index + 1],
                                        (nextindex - index -
                                         1) << L2XTSLOTSIZE);

                        p->header.nextindex =
                            cpu_to_le16(le16_to_cpu(p->header.nextindex) -
                                        1);

                        index = index0;
                        newindex = index + 1;
                        nextindex = le16_to_cpu(p->header.nextindex);
                        xoff = nxoff = offsetXAD(lxad);
                        xlen = nxlen = lxlen + nxlen;
                        xaddr = nxaddr = addressXAD(lxad);
                        goto coalesceRight;
                }
        }

        /*
         * replace XAD with nXAD
         */
      replace:                  /* (nxoff == xoff) */
        if (nxlen == xlen) {
                /* replace XAD with nXAD:recorded */
                *xad = *nxad;
                xad->flag = xflag & ~XAD_NOTRECORDED;

                goto coalesceRight;
        } else                  /* (nxlen < xlen) */
                goto updateLeft;

        /*
         * coalesce with right XAD
         */
      coalesceRight:            /* (xoff <= nxoff) */
        /* is XAD last entry of page ? */
        if (newindex == nextindex) {
                if (xoff == nxoff)
                        goto out;
                goto updateRight;
        }

        /* is nXAD logically and physically contiguous with rXAD ? */
        rxad = &p->xad[index + 1];
        rxlen = lengthXAD(rxad);
        if (!(rxad->flag & XAD_NOTRECORDED) &&
            (nxoff + nxlen == offsetXAD(rxad)) &&
            (nxaddr + nxlen == addressXAD(rxad)) &&
            (rxlen + nxlen < MAXXLEN)) {
                /* extend left rXAD */
                XADoffset(rxad, nxoff);
                XADlength(rxad, rxlen + nxlen);
                XADaddress(rxad, nxaddr);

                /* If we just merged two extents together, need to make sure
                 * the left extent gets logged.  If the right one is marked
                 * XAD_NEW, then we know it will be logged.  Otherwise, mark as
                 * XAD_EXTENDED
                 */
                if (!(rxad->flag & XAD_NEW))
                        rxad->flag |= XAD_EXTENDED;

                if (xlen > nxlen)
                        /* truncate XAD */
                        XADlength(xad, xlen - nxlen);
                else {          /* (xlen == nxlen) */

                        /* remove XAD */
                        memmove(&p->xad[index], &p->xad[index + 1],
                                (nextindex - index - 1) << L2XTSLOTSIZE);

                        p->header.nextindex =
                            cpu_to_le16(le16_to_cpu(p->header.nextindex) -
                                        1);
                }

                goto out;
        } else if (xoff == nxoff)
                goto out;

        if (xoff >= nxoff) {
                XT_PUTPAGE(mp);
                jfs_error(ip->i_sb, "xtUpdate: xoff >= nxoff");
                return -EIO;
        }
/* #endif _JFS_WIP_COALESCE */

        /*
         * split XAD into (lXAD, nXAD):
         *
         *          |---nXAD--->
         * --|----------XAD----------|--
         *   |-lXAD-|
         */
      updateRight:              /* (xoff < nxoff) */
        /* truncate old XAD as lXAD:not_recorded */
        xad = &p->xad[index];
        XADlength(xad, nxoff - xoff);

        /* insert nXAD:recorded */
        if (nextindex == le16_to_cpu(p->header.maxentry)) {

                /* xtSpliUp() unpins leaf pages */
                split.mp = mp;
                split.index = newindex;
                split.flag = xflag & ~XAD_NOTRECORDED;
                split.off = nxoff;
                split.len = nxlen;
                split.addr = nxaddr;
                split.pxdlist = NULL;
                if ((rc = xtSplitUp(tid, ip, &split, &btstack)))
                        return rc;

                /* get back old page */
                XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
                if (rc)
                        return rc;
                /*
                 * if leaf root has been split, original root has been
                 * copied to new child page, i.e., original entry now
                 * resides on the new child page;
                 */
                if (p->header.flag & BT_INTERNAL) {
                        ASSERT(p->header.nextindex ==
                               cpu_to_le16(XTENTRYSTART + 1));
                        xad = &p->xad[XTENTRYSTART];
                        bn = addressXAD(xad);
                        XT_PUTPAGE(mp);

                        /* get new child page */
                        XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
                        if (rc)
                                return rc;

                        BT_MARK_DIRTY(mp, ip);
                        if (!test_cflag(COMMIT_Nolink, ip)) {
                                tlck = txLock(tid, ip, mp, tlckXTREE|tlckGROW);
                                xtlck = (struct xtlock *) & tlck->lock;
                        }
                } else {
                        /* is nXAD on new page ? */
                        if (newindex >
                            (le16_to_cpu(p->header.maxentry) >> 1)) {
                                newindex =
                                    newindex -
                                    le16_to_cpu(p->header.nextindex) +
                                    XTENTRYSTART;
                                newpage = 1;
                        }
                }
        } else {
                /* if insert into middle, shift right remaining entries */
                if (newindex < nextindex)
                        memmove(&p->xad[newindex + 1], &p->xad[newindex],
                                (nextindex - newindex) << L2XTSLOTSIZE);

                /* insert the entry */
                xad = &p->xad[newindex];
                *xad = *nxad;
                xad->flag = xflag & ~XAD_NOTRECORDED;

                /* advance next available entry index. */
                p->header.nextindex =
                    cpu_to_le16(le16_to_cpu(p->header.nextindex) + 1);
        }

        /*
         * does nXAD force 3-way split ?
         *
         *          |---nXAD--->|
         * --|----------XAD-------------|--
         *   |-lXAD-|           |-rXAD -|
         */
        if (nxoff + nxlen == xoff + xlen)
                goto out;

        /* reorient nXAD as XAD for further split XAD into (nXAD, rXAD) */
        if (newpage) {
                /* close out old page */
                if (!test_cflag(COMMIT_Nolink, ip)) {
                        xtlck->lwm.offset = (xtlck->lwm.offset) ?
                            min(index0, (int)xtlck->lwm.offset) : index0;
                        xtlck->lwm.length =
                            le16_to_cpu(p->header.nextindex) -
                            xtlck->lwm.offset;
                }

                bn = le64_to_cpu(p->header.next);
                XT_PUTPAGE(mp);

                /* get new right page */
                XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
                if (rc)
                        return rc;

                BT_MARK_DIRTY(mp, ip);
                if (!test_cflag(COMMIT_Nolink, ip)) {
                        tlck = txLock(tid, ip, mp, tlckXTREE | tlckGROW);
                        xtlck = (struct xtlock *) & tlck->lock;
                }

                index0 = index = newindex;
        } else
                index++;

        newindex = index + 1;
        nextindex = le16_to_cpu(p->header.nextindex);
        xlen = xlen - (nxoff - xoff);
        xoff = nxoff;
        xaddr = nxaddr;

        /* recompute split pages */
        if (nextindex == le16_to_cpu(p->header.maxentry)) {
                XT_PUTPAGE(mp);

                if ((rc = xtSearch(ip, nxoff, NULL, &cmp, &btstack, XT_INSERT)))
                        return rc;

                /* retrieve search result */
                XT_GETSEARCH(ip, btstack.top, bn, mp, p, index0);

                if (cmp != 0) {
                        XT_PUTPAGE(mp);
                        jfs_error(ip->i_sb, "xtUpdate: xtSearch failed");
                        return -EIO;
                }

                if (index0 != index) {
                        XT_PUTPAGE(mp);
                        jfs_error(ip->i_sb,
                                  "xtUpdate: unexpected value of index");
                        return -EIO;
                }
        }

        /*
         * split XAD into (nXAD, rXAD)
         *
         *          ---nXAD---|
         * --|----------XAD----------|--
         *                    |-rXAD-|
         */
      updateLeft:               /* (nxoff == xoff) && (nxlen < xlen) */
        /* update old XAD with nXAD:recorded */
        xad = &p->xad[index];
        *xad = *nxad;
        xad->flag = xflag & ~XAD_NOTRECORDED;

        /* insert rXAD:not_recorded */
        xoff = xoff + nxlen;
        xlen = xlen - nxlen;
        xaddr = xaddr + nxlen;
        if (nextindex == le16_to_cpu(p->header.maxentry)) {
/*
printf("xtUpdate.updateLeft.split p:0x%p\n", p);
*/
                /* xtSpliUp() unpins leaf pages */
                split.mp = mp;
                split.index = newindex;
                split.flag = xflag;
                split.off = xoff;
                split.len = xlen;
                split.addr = xaddr;
                split.pxdlist = NULL;
                if ((rc = xtSplitUp(tid, ip, &split, &btstack)))
                        return rc;

                /* get back old page */
                XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
                if (rc)
                        return rc;

                /*
                 * if leaf root has been split, original root has been
                 * copied to new child page, i.e., original entry now
                 * resides on the new child page;
                 */
                if (p->header.flag & BT_INTERNAL) {
                        ASSERT(p->header.nextindex ==
                               cpu_to_le16(XTENTRYSTART + 1));
                        xad = &p->xad[XTENTRYSTART];
                        bn = addressXAD(xad);
                        XT_PUTPAGE(mp);

                        /* get new child page */
                        XT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
                        if (rc)
                                return rc;

                        BT_MARK_DIRTY(mp, ip);
                        if (!test_cflag(COMMIT_Nolink, ip)) {
                                tlck = txLock(tid, ip, mp, tlckXTREE|tlckGROW);
                                xtlck = (struct xtlock *) & tlck->lock;
                        }
                }
        } else {
                /* if insert into middle, shift right remaining entries */
                if (newindex < nextindex)
                        memmove(&p->xad[newindex + 1], &p->xad[newindex],
                                (nextindex - newindex) << L2XTSLOTSIZE);

                /* insert the entry */
                xad = &p->xad[newindex];
                XT_PUTENTRY(xad, xflag, xoff, xlen, xaddr);

                /* advance next available entry index. */
                p->header.nextindex =
                    cpu_to_le16(le16_to_cpu(p->header.nextindex) + 1);
        }

      out:
        if (!test_cflag(COMMIT_Nolink, ip)) {
                xtlck->lwm.offset = (xtlck->lwm.offset) ?
                    min(index0, (int)xtlck->lwm.offset) : index0;
                xtlck->lwm.length = le16_to_cpu(p->header.nextindex) -
                    xtlck->lwm.offset;
        }

        /* unpin the leaf page */
        XT_PUTPAGE(mp);

        return rc;
}


/*
 *      xtAppend()
 *
 * function: grow in append mode from contiguous region specified ;
 *
 * parameter:
 *      tid             - transaction id;
 *      ip              - file object;
 *      xflag           - extent flag:
 *      xoff            - extent offset;
 *      maxblocks       - max extent length;
 *      xlen            - extent length (in/out);
 *      xaddrp          - extent address pointer (in/out):
 *      flag            -
 *
 * return:
 */
int xtAppend(tid_t tid,         /* transaction id */
             struct inode *ip, int xflag, s64 xoff, s32 maxblocks,
             s32 * xlenp,       /* (in/out) */
             s64 * xaddrp,      /* (in/out) */
             int flag)
{
        int rc = 0;
        struct metapage *mp;    /* meta-page buffer */
        xtpage_t *p;            /* base B+-tree index page */
        s64 bn, xaddr;
        int index, nextindex;
        struct btstack btstack; /* traverse stack */
        struct xtsplit split;   /* split information */
        xad_t *xad;
        int cmp;
        struct tlock *tlck;
        struct xtlock *xtlck;
        int nsplit, nblocks, xlen;
        struct pxdlist pxdlist;
        pxd_t *pxd;
        s64 next;

        xaddr = *xaddrp;
        xlen = *xlenp;
        jfs_info("xtAppend: xoff:0x%lx maxblocks:%d xlen:%d xaddr:0x%lx",
                 (ulong) xoff, maxblocks, xlen, (ulong) xaddr);

        /*
         *      search for the entry location at which to insert:
         *
         * xtFastSearch() and xtSearch() both returns (leaf page
         * pinned, index at which to insert).
         * n.b. xtSearch() may return index of maxentry of
         * the full page.
         */
        if ((rc = xtSearch(ip, xoff, &next, &cmp, &btstack, XT_INSERT)))
                return rc;

        /* retrieve search result */
        XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);

        if (cmp == 0) {
                rc = -EEXIST;
                goto out;
        }

        if (next)
                xlen = min(xlen, (int)(next - xoff));
//insert:
        /*
         *      insert entry for new extent
         */
        xflag |= XAD_NEW;

        /*
         *      if the leaf page is full, split the page and
         *      propagate up the router entry for the new page from split
         *
         * The xtSplitUp() will insert the entry and unpin the leaf page.
         */
        nextindex = le16_to_cpu(p->header.nextindex);
        if (nextindex < le16_to_cpu(p->header.maxentry))
                goto insertLeaf;

        /*
         * allocate new index blocks to cover index page split(s)
         */
        nsplit = btstack.nsplit;
        split.pxdlist = &pxdlist;
        pxdlist.maxnpxd = pxdlist.npxd = 0;
        pxd = &pxdlist.pxd[0];
        nblocks = JFS_SBI(ip->i_sb)->nbperpage;
        for (; nsplit > 0; nsplit--, pxd++, xaddr += nblocks, maxblocks -= nblocks) {
                if ((rc = dbAllocBottomUp(ip, xaddr, (s64) nblocks)) == 0) {
                        PXDaddress(pxd, xaddr);
                        PXDlength(pxd, nblocks);

                        pxdlist.maxnpxd++;

                        continue;
                }

                /* undo allocation */

                goto out;
        }

        xlen = min(xlen, maxblocks);

        /*
         * allocate data extent requested
         */
        if ((rc = dbAllocBottomUp(ip, xaddr, (s64) xlen)))
                goto out;

        split.mp = mp;
        split.index = index;
        split.flag = xflag;
        split.off = xoff;
        split.len = xlen;
        split.addr = xaddr;
        if ((rc = xtSplitUp(tid, ip, &split, &btstack))) {
                /* undo data extent allocation */
                dbFree(ip, *xaddrp, (s64) * xlenp);

                return rc;
        }

        *xaddrp = xaddr;
        *xlenp = xlen;
        return 0;

        /*
         *      insert the new entry into the leaf page
         */
      insertLeaf:
        /*
         * allocate data extent requested
         */
        if ((rc = dbAllocBottomUp(ip, xaddr, (s64) xlen)))
                goto out;

        BT_MARK_DIRTY(mp, ip);
        /*
         * acquire a transaction lock on the leaf page;
         *
         * action: xad insertion/extension;
         */
        tlck = txLock(tid, ip, mp, tlckXTREE | tlckGROW);
        xtlck = (struct xtlock *) & tlck->lock;

        /* insert the new entry: mark the entry NEW */
        xad = &p->xad[index];
        XT_PUTENTRY(xad, xflag, xoff, xlen, xaddr);

        /* advance next available entry index */
        p->header.nextindex =
            cpu_to_le16(le16_to_cpu(p->header.nextindex) + 1);

        xtlck->lwm.offset =
            (xtlck->lwm.offset) ? min(index,(int) xtlck->lwm.offset) : index;
        xtlck->lwm.length = le16_to_cpu(p->header.nextindex) -
            xtlck->lwm.offset;

        *xaddrp = xaddr;
        *xlenp = xlen;

      out:
        /* unpin the leaf page */
        XT_PUTPAGE(mp);

        return rc;
}
#ifdef _STILL_TO_PORT

/* - TBD for defragmentaion/reorganization -
 *
 *      xtDelete()
 *
 * function:
 *      delete the entry with the specified key.
 *
 *      N.B.: whole extent of the entry is assumed to be deleted.
 *
 * parameter:
 *
 * return:
 *      ENOENT: if the entry is not found.
 *
 * exception:
 */
int xtDelete(tid_t tid, struct inode *ip, s64 xoff, s32 xlen, int flag)
{
        int rc = 0;
        struct btstack btstack;
        int cmp;
        s64 bn;
        struct metapage *mp;
        xtpage_t *p;
        int index, nextindex;
        struct tlock *tlck;
        struct xtlock *xtlck;

        /*
         * find the matching entry; xtSearch() pins the page
         */
        if ((rc = xtSearch(ip, xoff, NULL, &cmp, &btstack, 0)))
                return rc;

        XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);
        if (cmp) {
                /* unpin the leaf page */
                XT_PUTPAGE(mp);
                return -ENOENT;
        }

        /*
         * delete the entry from the leaf page
         */
        nextindex = le16_to_cpu(p->header.nextindex);
        p->header.nextindex =
            cpu_to_le16(le16_to_cpu(p->header.nextindex) - 1);

        /*
         * if the leaf page bocome empty, free the page
         */
        if (p->header.nextindex == cpu_to_le16(XTENTRYSTART))
                return (xtDeleteUp(tid, ip, mp, p, &btstack));

        BT_MARK_DIRTY(mp, ip);
        /*
         * acquire a transaction lock on the leaf page;
         *
         * action:xad deletion;
         */
        tlck = txLock(tid, ip, mp, tlckXTREE);
        xtlck = (struct xtlock *) & tlck->lock;
        xtlck->lwm.offset =
            (xtlck->lwm.offset) ? min(index, xtlck->lwm.offset) : index;

        /* if delete from middle, shift left/compact the remaining entries */
        if (index < nextindex - 1)
                memmove(&p->xad[index], &p->xad[index + 1],
                        (nextindex - index - 1) * sizeof(xad_t));

        XT_PUTPAGE(mp);

        return 0;
}


/* - TBD for defragmentaion/reorganization -
 *
 *      xtDeleteUp()
 *
 * function:
 *      free empty pages as propagating deletion up the tree
 *
 * parameter:
 *
 * return:
 */
static int
xtDeleteUp(tid_t tid, struct inode *ip,
           struct metapage * fmp, xtpage_t * fp, struct btstack * btstack)
{
        int rc = 0;
        struct metapage *mp;
        xtpage_t *p;
        int index, nextindex;
        s64 xaddr;
        int xlen;
        struct btframe *parent;
        struct tlock *tlck;
        struct xtlock *xtlck;

        /*
         * keep root leaf page which has become empty
         */
        if (fp->header.flag & BT_ROOT) {
                /* keep the root page */
                fp->header.flag &= ~BT_INTERNAL;
                fp->header.flag |= BT_LEAF;
                fp->header.nextindex = cpu_to_le16(XTENTRYSTART);

                /* XT_PUTPAGE(fmp); */

                return 0;
        }

        /*
         * free non-root leaf page
         */
        if ((rc = xtRelink(tid, ip, fp))) {
                XT_PUTPAGE(fmp);
                return rc;
        }

        xaddr = addressPXD(&fp->header.self);
        xlen = lengthPXD(&fp->header.self);
        /* free the page extent */
        dbFree(ip, xaddr, (s64) xlen);

        /* free the buffer page */
        discard_metapage(fmp);

        /*
         * propagate page deletion up the index tree
         *
         * If the delete from the parent page makes it empty,
         * continue all the way up the tree.
         * stop if the root page is reached (which is never deleted) or
         * if the entry deletion does not empty the page.
         */
        while ((parent = BT_POP(btstack)) != NULL) {
                /* get/pin the parent page <sp> */
                XT_GETPAGE(ip, parent->bn, mp, PSIZE, p, rc);
                if (rc)
                        return rc;

                index = parent->index;

                /* delete the entry for the freed child page from parent.
                 */
                nextindex = le16_to_cpu(p->header.nextindex);

                /*
                 * the parent has the single entry being deleted:
                 * free the parent page which has become empty.
                 */
                if (nextindex == 1) {
                        if (p->header.flag & BT_ROOT) {
                                /* keep the root page */
                                p->header.flag &= ~BT_INTERNAL;
                                p->header.flag |= BT_LEAF;
                                p->header.nextindex =
                                    cpu_to_le16(XTENTRYSTART);

                                /* XT_PUTPAGE(mp); */

                                break;
                        } else {
                                /* free the parent page */
                                if ((rc = xtRelink(tid, ip, p)))
                                        return rc;

                                xaddr = addressPXD(&p->header.self);
                                /* free the page extent */
                                dbFree(ip, xaddr,
                                       (s64) JFS_SBI(ip->i_sb)->nbperpage);

                                /* unpin/free the buffer page */
                                discard_metapage(mp);

                                /* propagate up */
                                continue;
                        }
                }
                /*
                 * the parent has other entries remaining:
                 * delete the router entry from the parent page.
                 */
                else {
                        BT_MARK_DIRTY(mp, ip);
                        /*
                         * acquire a transaction lock on the leaf page;
                         *
                         * action:xad deletion;
                         */
                        tlck = txLock(tid, ip, mp, tlckXTREE);
                        xtlck = (struct xtlock *) & tlck->lock;
                        xtlck->lwm.offset =
                            (xtlck->lwm.offset) ? min(index,
                                                      xtlck->lwm.
                                                      offset) : index;

                        /* if delete from middle,
                         * shift left/compact the remaining entries in the page
                         */
                        if (index < nextindex - 1)
                                memmove(&p->xad[index], &p->xad[index + 1],
                                        (nextindex - index -
                                         1) << L2XTSLOTSIZE);

                        p->header.nextindex =
                            cpu_to_le16(le16_to_cpu(p->header.nextindex) -
                                        1);
                        jfs_info("xtDeleteUp(entry): 0x%lx[%d]",
                                 (ulong) parent->bn, index);
                }

                /* unpin the parent page */
                XT_PUTPAGE(mp);

                /* exit propagation up */
                break;
        }

        return 0;
}


/*
 * NAME:        xtRelocate()
 *
 * FUNCTION:    relocate xtpage or data extent of regular file;
 *              This function is mainly used by defragfs utility.
 *
 * NOTE:        This routine does not have the logic to handle
 *              uncommitted allocated extent. The caller should call
 *              txCommit() to commit all the allocation before call
 *              this routine.
 */
int
xtRelocate(tid_t tid, struct inode * ip, xad_t * oxad,  /* old XAD */
           s64 nxaddr,          /* new xaddr */
           int xtype)
{                               /* extent type: XTPAGE or DATAEXT */
        int rc = 0;
        struct tblock *tblk;
        struct tlock *tlck;
        struct xtlock *xtlck;
        struct metapage *mp, *pmp, *lmp, *rmp;  /* meta-page buffer */
        xtpage_t *p, *pp, *rp, *lp;     /* base B+-tree index page */
        xad_t *xad;
        pxd_t *pxd;
        s64 xoff, xsize;
        int xlen;
        s64 oxaddr, sxaddr, dxaddr, nextbn, prevbn;
        cbuf_t *cp;
        s64 offset, nbytes, nbrd, pno;
        int nb, npages, nblks;
        s64 bn;
        int cmp;
        int index;
        struct pxd_lock *pxdlock;
        struct btstack btstack; /* traverse stack */

        xtype = xtype & EXTENT_TYPE;

        xoff = offsetXAD(oxad);
        oxaddr = addressXAD(oxad);
        xlen = lengthXAD(oxad);

        /* validate extent offset */
        offset = xoff << JFS_SBI(ip->i_sb)->l2bsize;
        if (offset >= ip->i_size)
                return -ESTALE; /* stale extent */

        jfs_info("xtRelocate: xtype:%d xoff:0x%lx xlen:0x%x xaddr:0x%lx:0x%lx",
                 xtype, (ulong) xoff, xlen, (ulong) oxaddr, (ulong) nxaddr);

        /*
         *      1. get and validate the parent xtpage/xad entry
         *      covering the source extent to be relocated;
         */
        if (xtype == DATAEXT) {
                /* search in leaf entry */
                rc = xtSearch(ip, xoff, NULL, &cmp, &btstack, 0);
                if (rc)
                        return rc;

                /* retrieve search result */
                XT_GETSEARCH(ip, btstack.top, bn, pmp, pp, index);

                if (cmp) {
                        XT_PUTPAGE(pmp);
                        return -ESTALE;
                }

                /* validate for exact match with a single entry */
                xad = &pp->xad[index];
                if (addressXAD(xad) != oxaddr || lengthXAD(xad) != xlen) {
                        XT_PUTPAGE(pmp);
                        return -ESTALE;
                }
        } else {                /* (xtype == XTPAGE) */

                /* search in internal entry */
                rc = xtSearchNode(ip, oxad, &cmp, &btstack, 0);
                if (rc)
                        return rc;

                /* retrieve search result */
                XT_GETSEARCH(ip, btstack.top, bn, pmp, pp, index);

                if (cmp) {
                        XT_PUTPAGE(pmp);
                        return -ESTALE;
                }

                /* xtSearchNode() validated for exact match with a single entry
                 */
                xad = &pp->xad[index];
        }
        jfs_info("xtRelocate: parent xad entry validated.");

        /*
         *      2. relocate the extent
         */
        if (xtype == DATAEXT) {
                /* if the extent is allocated-but-not-recorded
                 * there is no real data to be moved in this extent,
                 */
                if (xad->flag & XAD_NOTRECORDED)
                        goto out;
                else
                        /* release xtpage for cmRead()/xtLookup() */
                        XT_PUTPAGE(pmp);

                /*
                 *      cmRelocate()
                 *
                 * copy target data pages to be relocated;
                 *
                 * data extent must start at page boundary and
                 * multiple of page size (except the last data extent);
                 * read in each page of the source data extent into cbuf,
                 * update the cbuf extent descriptor of the page to be
                 * homeward bound to new dst data extent
                 * copy the data from the old extent to new extent.
                 * copy is essential for compressed files to avoid problems
                 * that can arise if there was a change in compression
                 * algorithms.
                 * it is a good strategy because it may disrupt cache
                 * policy to keep the pages in memory afterwards.
                 */
                offset = xoff << JFS_SBI(ip->i_sb)->l2bsize;
                assert((offset & CM_OFFSET) == 0);
                nbytes = xlen << JFS_SBI(ip->i_sb)->l2bsize;
                pno = offset >> CM_L2BSIZE;
                npages = (nbytes + (CM_BSIZE - 1)) >> CM_L2BSIZE;
/*
                npages = ((offset + nbytes - 1) >> CM_L2BSIZE) -
                          (offset >> CM_L2BSIZE) + 1;
*/
                sxaddr = oxaddr;
                dxaddr = nxaddr;

                /* process the request one cache buffer at a time */
                for (nbrd = 0; nbrd < nbytes; nbrd += nb,
                     offset += nb, pno++, npages--) {
                        /* compute page size */
                        nb = min(nbytes - nbrd, CM_BSIZE);

                        /* get the cache buffer of the page */
                        if (rc = cmRead(ip, offset, npages, &cp))
                                break;

                        assert(addressPXD(&cp->cm_pxd) == sxaddr);
                        assert(!cp->cm_modified);

                        /* bind buffer with the new extent address */
                        nblks = nb >> JFS_IP(ip->i_sb)->l2bsize;
                        cmSetXD(ip, cp, pno, dxaddr, nblks);

                        /* release the cbuf, mark it as modified */
                        cmPut(cp, true);

                        dxaddr += nblks;
                        sxaddr += nblks;
                }

                /* get back parent page */
                if ((rc = xtSearch(ip, xoff, NULL, &cmp, &btstack, 0)))
                        return rc;

                XT_GETSEARCH(ip, btstack.top, bn, pmp, pp, index);
                jfs_info("xtRelocate: target data extent relocated.");
        } else {                /* (xtype == XTPAGE) */

                /*
                 * read in the target xtpage from the source extent;
                 */
                XT_GETPAGE(ip, oxaddr, mp, PSIZE, p, rc);
                if (rc) {
                        XT_PUTPAGE(pmp);
                        return rc;
                }

                /*
                 * read in sibling pages if any to update sibling pointers;
                 */
                rmp = NULL;
                if (p->header.next) {
                        nextbn = le64_to_cpu(p->header.next);
                        XT_GETPAGE(ip, nextbn, rmp, PSIZE, rp, rc);