// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *   Copyright (C) International Business Machines Corp., 2000-2005
 */
/*
 *      jfs_xtree.c: extent allocation descriptor B+-tree manager
 */

#include <linux/fs.h>
#include <linux/module.h>
#include <linux/quotaops.h>
#include <linux/seq_file.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)

/* 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);

/*
 *      xt_getpage()
 *
 * function:    get the page buffer for a specified block address.
 *
 * parameters:
 *      ip      - pointer to the inode
 *      bn      - block number (s64) of the xtree page to be retrieved;
 *      mp      - pointer to a metapage pointer where the page buffer is returned;
 *
 * returns:
 *      A pointer to the xtree page (xtpage_t) on success, -EIO on error.
 */

static inline xtpage_t *xt_getpage(struct inode *ip, s64 bn, struct metapage **mp)
{
        xtpage_t *p;
        int rc;

        BT_GETPAGE(ip, bn, *mp, xtpage_t, PSIZE, p, rc, i_xtroot);

        if (rc)
                return ERR_PTR(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\n");
                BT_PUTPAGE(*mp);
                *mp = NULL;
                return ERR_PTR(-EIO);
        }
        return p;
}

/*
 *      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)
                        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;
}

/*
 *      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 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 */
                p = xt_getpage(ip, bn, &mp);
                if (IS_ERR(p))
                        return PTR_ERR(p);

                /* 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!\n");
                        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 */
        le16_add_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 */
                le16_add_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> */
                sp = xt_getpage(ip, parent->bn, &smp);
                if (IS_ERR(sp)) {
                        XT_PUTPAGE(rcmp);
                        return PTR_ERR(sp);
                }

                /*
                 * 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. */
                        le16_add_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. */
        rc = dquot_alloc_block(ip, lengthPXD(pxd));
        if (rc)
                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) {
                p = xt_getpage(ip, nextbn, &mp);
                if (IS_ERR(p)) {
                        XT_PUTPAGE(rmp);
                        return PTR_ERR(p);
                }

                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;
        int rc;

        sp = (xtpage_t *) &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. */
        rc = dquot_alloc_block(ip, lengthPXD(pxd));
        if (rc) {
                release_metapage(rmp);
                return rc;
        }

        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, "xtSearch did not find extent\n");
                return -EIO;
        }

        /* extension must be contiguous */
        xad = &p->xad[index];
        if ((offsetXAD(xad) + lengthXAD(xad)) != xoff) {
                XT_PUTPAGE(mp);
                jfs_error(ip->i_sb, "extension is not contiguous\n");
                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 */
                p = xt_getpage(ip, bn, &mp);
                if (IS_ERR(p))
                        return PTR_ERR(p);
                /*
                 * 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 */
                        p = xt_getpage(ip, bn, &mp);
                        if (IS_ERR(p))
                                return PTR_ERR(p);

                        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 */
                le16_add_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;
}

/*
 *      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, "Could not find extent\n");
                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,
                          "nXAD in not completely contained within XAD\n");
                return -EIO;
        }

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

        if (xoff < nxoff)
                goto coalesceRight;

        /*
         * coalesce with left XAD
         */
        /* 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, "xoff >= nxoff\n");
                return -EIO;
        }

        /*
         * 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 */
                p = xt_getpage(ip, bn, &mp);
                if (IS_ERR(p))
                        return PTR_ERR(p);
                /*
                 * 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 */
                        p = xt_getpage(ip, bn, &mp);
                        if (IS_ERR(p))
                                return PTR_ERR(p);

                        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 */
                p = xt_getpage(ip, bn, &mp);
                if (IS_ERR(p))
                        return PTR_ERR(p);

                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, "xtSearch failed\n");
                        return -EIO;
                }

                if (index0 != index) {
                        XT_PUTPAGE(mp);
                        jfs_error(ip->i_sb, "unexpected value of index\n");
                        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 */
                p = xt_getpage(ip, bn, &mp);
                if (IS_ERR(p))
                        return PTR_ERR(p);

                /*
                 * 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 */
                        p = xt_getpage(ip, bn, &mp);
                        if (IS_ERR(p))
                                return PTR_ERR(p);

                        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 */
        le16_add_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;
}

/*
 *      xtInitRoot()
 *
 * initialize file root (inline in inode)
 */
void xtInitRoot(tid_t tid, struct inode *ip)
{
        xtroot_t *p;

        /*
         * acquire a transaction lock on the root
         *
         * action:
         */
        txLock(tid, ip, (struct metapage *) &JFS_IP(ip)->bxflag,
                      tlckXTREE | tlckNEW);
        p = &JFS_IP(ip)->i_xtroot;

        p->header.flag = DXD_INDEX | BT_ROOT | BT_LEAF;
        p->header.nextindex = cpu_to_le16(XTENTRYSTART);

        if (S_ISDIR(ip->i_mode))
                p->header.maxentry = cpu_to_le16(XTROOTINITSLOT_DIR);
        else {
                p->header.maxentry = cpu_to_le16(XTROOTINITSLOT);
                ip->i_size = 0;
        }


        return;
}


/*
 * We can run into a deadlock truncating a file with a large number of
 * xtree pages (large fragmented file).  A robust fix would entail a
 * reservation system where we would reserve a number of metadata pages
 * and tlocks which we would be guaranteed without a deadlock.  Without
 * this, a partial fix is to limit number of metadata pages we will lock
 * in a single transaction.  Currently we will truncate the file so that
 * no more than 50 leaf pages will be locked.  The caller of xtTruncate
 * will be responsible for ensuring that the current transaction gets
 * committed, and that subsequent transactions are created to truncate
 * the file further if needed.
 */
#define MAX_TRUNCATE_LEAVES 50

/*
 *      xtTruncate()
 *
 * function:
 *      traverse for truncation logging backward bottom up;
 *      terminate at the last extent entry at the current subtree
 *      root page covering new down size.
 *      truncation may occur within the last extent entry.
 *
 * parameter:
 *      int             tid,
 *      struct inode    *ip,
 *      s64             newsize,
 *      int             type)   {PWMAP, PMAP, WMAP; DELETE, TRUNCATE}
 *
 * return:
 *
 * note:
 *      PWMAP:
 *       1. truncate (non-COMMIT_NOLINK file)
 *          by jfs_truncate() or jfs_open(O_TRUNC):
 *          xtree is updated;
 *       2. truncate index table of directory when last entry removed
 *      map update via tlock at commit time;
 *      PMAP:
 *       Call xtTruncate_pmap instead
 *      WMAP:
 *       1. remove (free zero link count) on last reference release
 *          (pmap has been freed at commit zero link count);
 *       2. truncate (COMMIT_NOLINK file, i.e., tmp file):
 *          xtree is updated;
 *       map update directly at truncation time;
 *
 *      if (DELETE)
 *              no LOG_NOREDOPAGE is required (NOREDOFILE is sufficient);
 *      else if (TRUNCATE)
 *              must write LOG_NOREDOPAGE for deleted index page;
 *
 * pages may already have been tlocked by anonymous transactions
 * during file growth (i.e., write) before truncation;
 *
 * except last truncated entry, deleted entries remains as is
 * in the page (nextindex is updated) for other use
 * (e.g., log/update allocation map): this avoid copying the page
 * info but delay free of pages;
 *
 */
s64 xtTruncate(tid_t tid, struct inode *ip, s64 newsize, int flag)
{
        s64 teof;
        struct metapage *mp;
        xtpage_t *p;
        s64 bn;
        int index, nextindex;
        xad_t *xad;
        s64 xoff, xaddr;
        int xlen, len, freexlen;
        struct btstack btstack;
        struct btframe *parent;
        struct tblock *tblk = NULL;
        struct tlock *tlck = NULL;
        struct xtlock *xtlck = NULL;
        struct xdlistlock xadlock;      /* maplock for COMMIT_WMAP */
        struct pxd_lock *pxdlock;               /* maplock for COMMIT_WMAP */
        s64 nfreed;
        int freed, log;
        int locked_leaves = 0;

        /* save object truncation type */
        if (tid) {
                tblk = tid_to_tblock(tid);
                tblk->xflag |= flag;
        }

        nfreed = 0;

        flag &= COMMIT_MAP;
        assert(flag != COMMIT_PMAP);

        if (flag == COMMIT_PWMAP)
                log = 1;
        else {
                log = 0;
                xadlock.flag = mlckFREEXADLIST;
                xadlock.index = 1;
        }

        /*
         * if the newsize is not an integral number of pages,
         * the file between newsize and next page boundary will
         * be cleared.
         * if truncating into a file hole, it will cause
         * a full block to be allocated for the logical block.
         */

        /*
         * release page blocks of truncated region <teof, eof>
         *
         * free the data blocks from the leaf index blocks.
         * delete the parent index entries corresponding to
         * the freed child data/index blocks.
         * free the index blocks themselves which aren't needed
         * in new sized file.
         *
         * index blocks are updated only if the blocks are to be
         * retained in the new sized file.
         * if type is PMAP, the data and index pages are NOT
         * freed, and the data and index blocks are NOT freed
         * from working map.
         * (this will allow continued access of data/index of
         * temporary file (zerolink count file truncated to zero-length)).
         */
        teof = (newsize + (JFS_SBI(ip->i_sb)->bsize - 1)) >>
            JFS_SBI(ip->i_sb)->l2bsize;

        /* clear stack */
        BT_CLR(&btstack);

        /*
         * start with root
         *
         * root resides in the inode
         */
        bn = 0;

        /*
         * first access of each page:
         */
      getPage:
        p = xt_getpage(ip, bn, &mp);
        if (IS_ERR(p))
                return PTR_ERR(p);

        /* process entries backward from last index */
        index = le16_to_cpu(p->header.nextindex) - 1;


        /* Since this is the rightmost page at this level, and we may have
         * already freed a page that was formerly to the right, let's make
         * sure that the next pointer is zero.
         */
        if (p->header.next) {
                if (log)
                        /*
                         * Make sure this change to the header is logged.
                         * If we really truncate this leaf, the flag
                         * will be changed to tlckTRUNCATE
                         */
                        tlck = txLock(tid, ip, mp, tlckXTREE|tlckGROW);
                BT_MARK_DIRTY(mp, ip);
                p->header.next = 0;
        }

        if (p->header.flag & BT_INTERNAL)
                goto getChild;

        /*
         *      leaf page
         */
        freed = 0;

        /* does region covered by leaf page precede Teof ? */
        xad = &p->xad[index];
        xoff = offsetXAD(xad);
        xlen = lengthXAD(xad);
        if (teof >= xoff + xlen) {
                XT_PUTPAGE(mp);
                goto getParent;
        }

        /* (re)acquire tlock of the leaf page */
        if (log) {
                if (++locked_leaves > MAX_TRUNCATE_LEAVES) {
                        /*
                         * We need to limit the size of the transaction
                         * to avoid exhausting pagecache & tlocks
                         */
                        XT_PUTPAGE(mp);
                        newsize = (xoff + xlen) << JFS_SBI(ip->i_sb)->l2bsize;
                        goto getParent;
                }
                tlck = txLock(tid, ip, mp, tlckXTREE);
                tlck->type = tlckXTREE | tlckTRUNCATE;
                xtlck = (struct xtlock *) & tlck->lock;
                xtlck->hwm.offset = le16_to_cpu(p->header.nextindex) - 1;
        }
        BT_MARK_DIRTY(mp, ip);

        /*
         * scan backward leaf page entries
         */
        for (; index >= XTENTRYSTART; index--) {
                xad = &p->xad[index];
                xoff = offsetXAD(xad);
                xlen = lengthXAD(xad);
                xaddr = addressXAD(xad);

                /*
                 * The "data" for a directory is indexed by the block
                 * device's address space.  This metadata must be invalidated
                 * here
                 */
                if (S_ISDIR(ip->i_mode) && (teof == 0))
                        invalidate_xad_metapages(ip, *xad);
                /*
                 * entry beyond eof: continue scan of current page
                 *          xad
                 * ---|---=======------->
                 *   eof
                 */
                if (teof < xoff) {
                        nfreed += xlen;
                        continue;
                }

                /*
                 * (xoff <= teof): last entry to be deleted from page;
                 * If other entries remain in page: keep and update the page.
                 */

                /*
                 * eof == entry_start: delete the entry
                 *           xad
                 * -------|=======------->
                 *       eof
                 *
                 */
                if (teof == xoff) {
                        nfreed += xlen;

                        if (index == XTENTRYSTART)
                                break;

                        nextindex = index;
                }
                /*
                 * eof within the entry: truncate the entry.
                 *          xad
                 * -------===|===------->
                 *          eof
                 */
                else if (teof < xoff + xlen) {
                        /* update truncated entry */
                        len = teof - xoff;
                        freexlen = xlen - len;
                        XADlength(xad, len);

                        /* save pxd of truncated extent in tlck */
                        xaddr += len;
                        if (log) {      /* COMMIT_PWMAP */
                                xtlck->lwm.offset = (xtlck->lwm.offset) ?
                                    min(index, (int)xtlck->lwm.offset) : index;
                                xtlck->lwm.length = index + 1 -
                                    xtlck->lwm.offset;
                                xtlck->twm.offset = index;
                                pxdlock = (struct pxd_lock *) & xtlck->pxdlock;
                                pxdlock->flag = mlckFREEPXD;
                                PXDaddress(&pxdlock->pxd, xaddr);
                                PXDlength(&pxdlock->pxd, freexlen);
                        }
                        /* free truncated extent */
                        else {  /* COMMIT_WMAP */

                                pxdlock = (struct pxd_lock *) & xadlock;
                                pxdlock->flag = mlckFREEPXD;
                                PXDaddress(&pxdlock->pxd, xaddr);
                                PXDlength(&pxdlock->pxd, freexlen);
                                txFreeMap(ip, pxdlock, NULL, COMMIT_WMAP);

                                /* reset map lock */
                                xadlock.flag = mlckFREEXADLIST;
                        }

                        /* current entry is new last entry; */
                        nextindex = index + 1;

                        nfreed += freexlen;
                }
                /*
                 * eof beyond the entry:
                 *          xad
                 * -------=======---|--->
                 *                 eof
                 */
                else {          /* (xoff + xlen < teof) */

                        nextindex = index + 1;
                }

                if (nextindex < le16_to_cpu(p->header.nextindex)) {
                        if (!log) {     /* COMMIT_WAMP */
                                xadlock.xdlist = &p->xad[nextindex];
                                xadlock.count =
                                    le16_to_cpu(p->header.nextindex) -
                                    nextindex;
                                txFreeMap(ip, (struct maplock *) & xadlock,
                                          NULL, COMMIT_WMAP);
                        }
                        p->header.nextindex = cpu_to_le16(nextindex);
                }

                XT_PUTPAGE(mp);

                /* assert(freed == 0); */
                goto getParent;
        }                       /* end scan of leaf page entries */

        freed = 1;

        /*
         * leaf page become empty: free the page if type != PMAP
         */
        if (log) {              /* COMMIT_PWMAP */
                /* txCommit() with tlckFREE:
                 * free data extents covered by leaf [XTENTRYSTART:hwm);
                 * invalidate leaf if COMMIT_PWMAP;
                 * if (TRUNCATE), will write LOG_NOREDOPAGE;
                 */
                tlck->type = tlckXTREE | tlckFREE;
        } else {                /* COMMIT_WAMP */

                /* free data extents covered by leaf */
                xadlock.xdlist = &p->xad[XTENTRYSTART];
                xadlock.count =
                    le16_to_cpu(p->header.nextindex) - XTENTRYSTART;
                txFreeMap(ip, (struct maplock *) & xadlock, NULL, COMMIT_WMAP);
        }

        if (p->header.flag & BT_ROOT) {
                p->header.flag &= ~BT_INTERNAL;
                p->header.flag |= BT_LEAF;
                p->header.nextindex = cpu_to_le16(XTENTRYSTART);

                XT_PUTPAGE(mp); /* debug */
                goto out;
        } else {
                if (log) {      /* COMMIT_PWMAP */
                        /* page will be invalidated at tx completion
                         */
                        XT_PUTPAGE(mp);
                } else {        /* COMMIT_WMAP */

                        if (mp->lid)
                                lid_to_tlock(mp->lid)->flag |= tlckFREELOCK;

                        /* invalidate empty leaf page */
                        discard_metapage(mp);
                }
        }

        /*
         * the leaf page become empty: delete the parent entry
         * for the leaf page if the parent page is to be kept
         * in the new sized file.
         */

        /*
         * go back up to the parent page
         */
      getParent:
        /* pop/restore parent entry for the current child page */
        if ((parent = BT_POP(&btstack)) == NULL)
                /* current page must have been root */
                goto out;

        /* get back the parent page */
        bn = parent->bn;
        p = xt_getpage(ip, bn, &mp);
        if (IS_ERR(p))
                return PTR_ERR(p);

        index = parent->index;

        /*
         * child page was not empty:
         */
        if (freed == 0) {
                /* has any entry deleted from parent ? */
                if (index < le16_to_cpu(p->header.nextindex) - 1) {
                        /* (re)acquire tlock on the parent page */
                        if (log) {      /* COMMIT_PWMAP */
                                /* txCommit() with tlckTRUNCATE:
                                 * free child extents covered by parent [);
                                 */
                                tlck = txLock(tid, ip, mp, tlckXTREE);
                                xtlck = (struct xtlock *) & tlck->lock;
                                if (!(tlck->type & tlckTRUNCATE)) {
                                        xtlck->hwm.offset =
                                            le16_to_cpu(p->header.
                                                        nextindex) - 1;
                                        tlck->type =
                                            tlckXTREE | tlckTRUNCATE;
                                }
                        } else {        /* COMMIT_WMAP */

                                /* free child extents covered by parent */
                                xadlock.xdlist = &p->xad[index + 1];
                                xadlock.count =
                                    le16_to_cpu(p->header.nextindex) -
                                    index - 1;
                                txFreeMap(ip, (struct maplock *) & xadlock,
                                          NULL, COMMIT_WMAP);
                        }
                        BT_MARK_DIRTY(mp, ip);

                        p->header.nextindex = cpu_to_le16(index + 1);
                }
                XT_PUTPAGE(mp);
                goto getParent;
        }

        /*
         * child page was empty:
         */
        nfreed += lengthXAD(&p->xad[index]);

        /*
         * During working map update, child page's tlock must be handled
         * before parent's.  This is because the parent's tlock will cause
         * the child's disk space to be marked available in the wmap, so
         * it's important that the child page be released by that time.
         *
         * ToDo:  tlocks should be on doubly-linked list, so we can
         * quickly remove it and add it to the end.
         */

        /*
         * Move parent page's tlock to the end of the tid's tlock list
         */
        if (log && mp->lid && (tblk->last != mp->lid) &&
            lid_to_tlock(mp->lid)->tid) {
                lid_t lid = mp->lid;
                struct tlock *prev;

                tlck = lid_to_tlock(lid);

                if (tblk->next == lid)
                        tblk->next = tlck->next;
                else {
                        for (prev = lid_to_tlock(tblk->next);
                             prev->next != lid;
                             prev = lid_to_tlock(prev->next)) {
                                assert(prev->next);
                        }
                        prev->next = tlck->next;
                }
                lid_to_tlock(tblk->last)->next = lid;
                tlck->next = 0;
                tblk->last = lid;
        }

        /*
         * parent page become empty: free the page
         */
        if (index == XTENTRYSTART) {
                if (log) {      /* COMMIT_PWMAP */
                        /* txCommit() with tlckFREE:
                         * free child extents covered by parent;
                         * invalidate parent if COMMIT_PWMAP;
                         */
                        tlck = txLock(tid, ip, mp, tlckXTREE);
                        xtlck = (struct xtlock *) & tlck->lock;
                        xtlck->hwm.offset =
                            le16_to_cpu(p->header.nextindex) - 1;
                        tlck->type = tlckXTREE | tlckFREE;
                } else {        /* COMMIT_WMAP */

                        /* free child extents covered by parent */
                        xadlock.xdlist = &p->xad[XTENTRYSTART];
                        xadlock.count =
                            le16_to_cpu(p->header.nextindex) -
                            XTENTRYSTART;
                        txFreeMap(ip, (struct maplock *) & xadlock, NULL,
                                  COMMIT_WMAP);
                }
                BT_MARK_DIRTY(mp, ip);

                if (p->header.flag & BT_ROOT) {
                        p->header.flag &= ~BT_INTERNAL;
                        p->header.flag |= BT_LEAF;
                        p->header.nextindex = cpu_to_le16(XTENTRYSTART);
                        if (le16_to_cpu(p->header.maxentry) == XTROOTMAXSLOT) {
                                /*
                                 * Shrink root down to allow inline
                                 * EA (otherwise fsck complains)
                                 */
                                p->header.maxentry =
                                    cpu_to_le16(XTROOTINITSLOT);
                                JFS_IP(ip)->mode2 |= INLINEEA;
                        }

                        XT_PUTPAGE(mp); /* debug */
                        goto out;
                } else {
                        if (log) {      /* COMMIT_PWMAP */
                                /* page will be invalidated at tx completion
                                 */
                                XT_PUTPAGE(mp);
                        } else {        /* COMMIT_WMAP */

                                if (mp->lid)
                                        lid_to_tlock(mp->lid)->flag |=
                                                tlckFREELOCK;

                                /* invalidate parent page */
                                discard_metapage(mp);
                        }

                        /* parent has become empty and freed:
                         * go back up to its parent page
                         */
                        /* freed = 1; */
                        goto getParent;
                }
        }
        /*
         * parent page still has entries for front region;
         */
        else {
                /* try truncate region covered by preceding entry
                 * (process backward)
                 */
                index--;

                /* go back down to the child page corresponding
                 * to the entry
                 */
                goto getChild;
        }

        /*
         *      internal page: go down to child page of current entry
         */
      getChild:
        /* save current parent entry for the child page */
        if (BT_STACK_FULL(&btstack)) {
                jfs_error(ip->i_sb, "stack overrun!\n");
                XT_PUTPAGE(mp);
                return -EIO;
        }
        BT_PUSH(&btstack, bn, index);

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

        /*
         * first access of each internal entry:
         */
        /* release parent page */
        XT_PUTPAGE(mp);

        /* process the child page */
        goto getPage;

      out:
        /*
         * update file resource stat
         */
        /* set size
         */
        if (S_ISDIR(ip->i_mode) && !newsize)
                ip->i_size = 1; /* fsck hates zero-length directories */
        else
                ip->i_size = newsize;

        /* update quota allocation to reflect freed blocks */
        dquot_free_block(ip, nfreed);

        /*
         * free tlock of invalidated pages
         */
        if (flag == COMMIT_WMAP)
                txFreelock(ip);

        return newsize;
}


/*
 *      xtTruncate_pmap()
 *
 * function:
 *      Perform truncate to zero length for deleted file, leaving the
 *      xtree and working map untouched.  This allows the file to
 *      be accessed via open file handles, while the delete of the file
 *      is committed to disk.
 *
 * parameter:
 *      tid_t           tid,
 *      struct inode    *ip,
 *      s64             committed_size)
 *
 * return: new committed size
 *
 * note:
 *
 *      To avoid deadlock by holding too many transaction locks, the
 *      truncation may be broken up into multiple transactions.
 *      The committed_size keeps track of part of the file has been
 *      freed from the pmaps.
 */
s64 xtTruncate_pmap(tid_t tid, struct inode *ip, s64 committed_size)
{
        s64 bn;
        struct btstack btstack;
        int cmp;
        int index;
        int locked_leaves = 0;
        struct metapage *mp;
        xtpage_t *p;
        struct btframe *parent;
        int rc;
        struct tblock *tblk;
        struct tlock *tlck = NULL;
        xad_t *xad;
        int xlen;
        s64 xoff;
        struct xtlock *xtlck = NULL;

        /* save object truncation type */
        tblk = tid_to_tblock(tid);
        tblk->xflag |= COMMIT_PMAP;

        /* clear stack */
        BT_CLR(&btstack);

        if (committed_size) {
                xoff = (committed_size >> JFS_SBI(ip->i_sb)->l2bsize) - 1;
                rc = xtSearch(ip, xoff, NULL, &cmp, &btstack, 0);
                if (rc)
                        return rc;

                XT_GETSEARCH(ip, btstack.top, bn, mp, p, index);

                if (cmp != 0) {
                        XT_PUTPAGE(mp);
                        jfs_error(ip->i_sb, "did not find extent\n");
                        return -EIO;
                }
        } else {
                /*
                 * start with root
                 *
                 * root resides in the inode
                 */
                bn = 0;

                /*
                 * first access of each page:
                 */
      getPage:
                p = xt_getpage(ip, bn, &mp);
                if (IS_ERR(p))
                        return PTR_ERR(p);

                /* process entries backward from last index */
                index = le16_to_cpu(p->header.nextindex) - 1;

                if (p->header.flag & BT_INTERNAL)
                        goto getChild;
        }

        /*
         *      leaf page
         */

        if (++locked_leaves > MAX_TRUNCATE_LEAVES) {
                /*
                 * We need to limit the size of the transaction
                 * to avoid exhausting pagecache & tlocks
                 */
                xad = &p->xad[index];
                xoff = offsetXAD(xad);
                xlen = lengthXAD(xad);
                XT_PUTPAGE(mp);
                return (xoff + xlen) << JFS_SBI(ip->i_sb)->l2bsize;
        }
        tlck = txLock(tid, ip, mp, tlckXTREE);
        tlck->type = tlckXTREE | tlckFREE;
        xtlck = (struct xtlock *) & tlck->lock;
        xtlck->hwm.offset = index;


        XT_PUTPAGE(mp);

        /*
         * go back up to the parent page
         */
      getParent:
        /* pop/restore parent entry for the current child page */
        if ((parent = BT_POP(&btstack)) == NULL)
                /* current page must have been root */
                goto out;

        /* get back the parent page */
        bn = parent->bn;
        p = xt_getpage(ip, bn, &mp);
        if (IS_ERR(p))
                return PTR_ERR(p);

        index = parent->index;

        /*
         * parent page become empty: free the page
         */
        if (index == XTENTRYSTART) {
                /* txCommit() with tlckFREE:
                 * free child extents covered by parent;
                 * invalidate parent if COMMIT_PWMAP;
                 */
                tlck = txLock(tid, ip, mp, tlckXTREE);
                xtlck = (struct xtlock *) & tlck->lock;
                xtlck->hwm.offset = le16_to_cpu(p->header.nextindex) - 1;
                tlck->type = tlckXTREE | tlckFREE;

                XT_PUTPAGE(mp);

                if (p->header.flag & BT_ROOT) {

                        goto out;
                } else {
                        goto getParent;
                }
        }
        /*
         * parent page still has entries for front region;
         */
        else
                index--;
        /*
         *      internal page: go down to child page of current entry
         */
      getChild:
        /* save current parent entry for the child page */
        if (BT_STACK_FULL(&btstack)) {
                jfs_error(ip->i_sb, "stack overrun!\n");
                XT_PUTPAGE(mp);
                return -EIO;
        }
        BT_PUSH(&btstack, bn, index);

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

        /*
         * first access of each internal entry:
         */
        /* release parent page */
        XT_PUTPAGE(mp);

        /* process the child page */
        goto getPage;

      out:

        return 0;
}

#ifdef CONFIG_JFS_STATISTICS
int jfs_xtstat_proc_show(struct seq_file *m, void *v)
{
        seq_printf(m,
                       "JFS Xtree statistics\n"
                       "====================\n"
                       "searches = %d\n"
                       "fast searches = %d\n"
                       "splits = %d\n",
                       xtStat.search,
                       xtStat.fastSearch,
                       xtStat.split);
        return 0;
}
#endif