mm/ksm.c is doing an unneeded _notify in write_protect_page.

[nv-tegra-linux-2.6.git] / fs / jfs / jfs_dtree.c

/*
 *   Copyright (C) International Business Machines Corp., 2000-2004
 *
 *   This program is free software;  you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY;  without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
 *   the GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program;  if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

/*
 *      jfs_dtree.c: directory B+-tree manager
 *
 * B+-tree with variable length key directory:
 *
 * each directory page is structured as an array of 32-byte
 * directory entry slots initialized as a freelist
 * to avoid search/compaction of free space at insertion.
 * when an entry is inserted, a number of slots are allocated
 * from the freelist as required to store variable length data
 * of the entry; when the entry is deleted, slots of the entry
 * are returned to freelist.
 *
 * leaf entry stores full name as key and file serial number
 * (aka inode number) as data.
 * internal/router entry stores sufffix compressed name
 * as key and simple extent descriptor as data.
 *
 * each directory page maintains a sorted entry index table
 * which stores the start slot index of sorted entries
 * to allow binary search on the table.
 *
 * directory starts as a root/leaf page in on-disk inode
 * inline data area.
 * when it becomes full, it starts a leaf of a external extent
 * of length of 1 block. each time the first leaf becomes full,
 * it is extended rather than split (its size is doubled),
 * until its length becoms 4 KBytes, from then the extent is split
 * with new 4 Kbyte extent when it becomes full
 * to reduce external fragmentation of small directories.
 *
 * blah, blah, blah, for linear scan of directory in pieces by
 * readdir().
 *
 *
 *      case-insensitive directory file system
 *
 * names are stored in case-sensitive way in leaf entry.
 * but stored, searched and compared in case-insensitive (uppercase) order
 * (i.e., both search key and entry key are folded for search/compare):
 * (note that case-sensitive order is BROKEN in storage, e.g.,
 *  sensitive: Ad, aB, aC, aD -> insensitive: aB, aC, aD, Ad
 *
 *  entries which folds to the same key makes up a equivalent class
 *  whose members are stored as contiguous cluster (may cross page boundary)
 *  but whose order is arbitrary and acts as duplicate, e.g.,
 *  abc, Abc, aBc, abC)
 *
 * once match is found at leaf, requires scan forward/backward
 * either for, in case-insensitive search, duplicate
 * or for, in case-sensitive search, for exact match
 *
 * router entry must be created/stored in case-insensitive way
 * in internal entry:
 * (right most key of left page and left most key of right page
 * are folded, and its suffix compression is propagated as router
 * key in parent)
 * (e.g., if split occurs <abc> and <aBd>, <ABD> trather than <aB>
 * should be made the router key for the split)
 *
 * case-insensitive search:
 *
 *      fold search key;
 *
 *      case-insensitive search of B-tree:
 *      for internal entry, router key is already folded;
 *      for leaf entry, fold the entry key before comparison.
 *
 *      if (leaf entry case-insensitive match found)
 *              if (next entry satisfies case-insensitive match)
 *                      return EDUPLICATE;
 *              if (prev entry satisfies case-insensitive match)
 *                      return EDUPLICATE;
 *              return match;
 *      else
 *              return no match;
 *
 *      serialization:
 * target directory inode lock is being held on entry/exit
 * of all main directory service routines.
 *
 *      log based recovery:
 */

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

/* dtree split parameter */
struct dtsplit {
        struct metapage *mp;
        s16 index;
        s16 nslot;
        struct component_name *key;
        ddata_t *data;
        struct pxdlist *pxdlist;
};

#define DT_PAGE(IP, MP) BT_PAGE(IP, MP, dtpage_t, i_dtroot)

/* get page buffer for specified block address */
#define DT_GETPAGE(IP, BN, MP, SIZE, P, RC)\
{\
        BT_GETPAGE(IP, BN, MP, dtpage_t, SIZE, P, RC, i_dtroot)\
        if (!(RC))\
        {\
                if (((P)->header.nextindex > (((BN)==0)?DTROOTMAXSLOT:(P)->header.maxslot)) ||\
                    ((BN) && ((P)->header.maxslot > DTPAGEMAXSLOT)))\
                {\
                        BT_PUTPAGE(MP);\
                        jfs_error((IP)->i_sb, "DT_GETPAGE: dtree page corrupt");\
                        MP = NULL;\
                        RC = -EIO;\
                }\
        }\
}

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

#define DT_GETSEARCH(IP, LEAF, BN, MP, P, INDEX) \
        BT_GETSEARCH(IP, LEAF, BN, MP, dtpage_t, P, INDEX, i_dtroot)

/*
 * forward references
 */
static int dtSplitUp(tid_t tid, struct inode *ip,
                     struct dtsplit * split, struct btstack * btstack);

static int dtSplitPage(tid_t tid, struct inode *ip, struct dtsplit * split,
                       struct metapage ** rmpp, dtpage_t ** rpp, pxd_t * rxdp);

static int dtExtendPage(tid_t tid, struct inode *ip,
                        struct dtsplit * split, struct btstack * btstack);

static int dtSplitRoot(tid_t tid, struct inode *ip,
                       struct dtsplit * split, struct metapage ** rmpp);

static int dtDeleteUp(tid_t tid, struct inode *ip, struct metapage * fmp,
                      dtpage_t * fp, struct btstack * btstack);

static int dtRelink(tid_t tid, struct inode *ip, dtpage_t * p);

static int dtReadFirst(struct inode *ip, struct btstack * btstack);

static int dtReadNext(struct inode *ip,
                      loff_t * offset, struct btstack * btstack);

static int dtCompare(struct component_name * key, dtpage_t * p, int si);

static int ciCompare(struct component_name * key, dtpage_t * p, int si,
                     int flag);

static void dtGetKey(dtpage_t * p, int i, struct component_name * key,
                     int flag);

static int ciGetLeafPrefixKey(dtpage_t * lp, int li, dtpage_t * rp,
                              int ri, struct component_name * key, int flag);

static void dtInsertEntry(dtpage_t * p, int index, struct component_name * key,
                          ddata_t * data, struct dt_lock **);

static void dtMoveEntry(dtpage_t * sp, int si, dtpage_t * dp,
                        struct dt_lock ** sdtlock, struct dt_lock ** ddtlock,
                        int do_index);

static void dtDeleteEntry(dtpage_t * p, int fi, struct dt_lock ** dtlock);

static void dtTruncateEntry(dtpage_t * p, int ti, struct dt_lock ** dtlock);

static void dtLinelockFreelist(dtpage_t * p, int m, struct dt_lock ** dtlock);

#define ciToUpper(c)    UniStrupr((c)->name)

/*
 *      read_index_page()
 *
 *      Reads a page of a directory's index table.
 *      Having metadata mapped into the directory inode's address space
 *      presents a multitude of problems.  We avoid this by mapping to
 *      the absolute address space outside of the *_metapage routines
 */
static struct metapage *read_index_page(struct inode *inode, s64 blkno)
{
        int rc;
        s64 xaddr;
        int xflag;
        s32 xlen;

        rc = xtLookup(inode, blkno, 1, &xflag, &xaddr, &xlen, 1);
        if (rc || (xaddr == 0))
                return NULL;

        return read_metapage(inode, xaddr, PSIZE, 1);
}

/*
 *      get_index_page()
 *
 *      Same as get_index_page(), but get's a new page without reading
 */
static struct metapage *get_index_page(struct inode *inode, s64 blkno)
{
        int rc;
        s64 xaddr;
        int xflag;
        s32 xlen;

        rc = xtLookup(inode, blkno, 1, &xflag, &xaddr, &xlen, 1);
        if (rc || (xaddr == 0))
                return NULL;

        return get_metapage(inode, xaddr, PSIZE, 1);
}

/*
 *      find_index()
 *
 *      Returns dtree page containing directory table entry for specified
 *      index and pointer to its entry.
 *
 *      mp must be released by caller.
 */
static struct dir_table_slot *find_index(struct inode *ip, u32 index,
                                         struct metapage ** mp, s64 *lblock)
{
        struct jfs_inode_info *jfs_ip = JFS_IP(ip);
        s64 blkno;
        s64 offset;
        int page_offset;
        struct dir_table_slot *slot;
        static int maxWarnings = 10;

        if (index < 2) {
                if (maxWarnings) {
                        jfs_warn("find_entry called with index = %d", index);
                        maxWarnings--;
                }
                return NULL;
        }

        if (index >= jfs_ip->next_index) {
                jfs_warn("find_entry called with index >= next_index");
                return NULL;
        }

        if (jfs_dirtable_inline(ip)) {
                /*
                 * Inline directory table
                 */
                *mp = NULL;
                slot = &jfs_ip->i_dirtable[index - 2];
        } else {
                offset = (index - 2) * sizeof(struct dir_table_slot);
                page_offset = offset & (PSIZE - 1);
                blkno = ((offset + 1) >> L2PSIZE) <<
                    JFS_SBI(ip->i_sb)->l2nbperpage;

                if (*mp && (*lblock != blkno)) {
                        release_metapage(*mp);
                        *mp = NULL;
                }
                if (!(*mp)) {
                        *lblock = blkno;
                        *mp = read_index_page(ip, blkno);
                }
                if (!(*mp)) {
                        jfs_err("free_index: error reading directory table");
                        return NULL;
                }

                slot =
                    (struct dir_table_slot *) ((char *) (*mp)->data +
                                               page_offset);
        }
        return slot;
}

static inline void lock_index(tid_t tid, struct inode *ip, struct metapage * mp,
                              u32 index)
{
        struct tlock *tlck;
        struct linelock *llck;
        struct lv *lv;

        tlck = txLock(tid, ip, mp, tlckDATA);
        llck = (struct linelock *) tlck->lock;

        if (llck->index >= llck->maxcnt)
                llck = txLinelock(llck);
        lv = &llck->lv[llck->index];

        /*
         *      Linelock slot size is twice the size of directory table
         *      slot size.  512 entries per page.
         */
        lv->offset = ((index - 2) & 511) >> 1;
        lv->length = 1;
        llck->index++;
}

/*
 *      add_index()
 *
 *      Adds an entry to the directory index table.  This is used to provide
 *      each directory entry with a persistent index in which to resume
 *      directory traversals
 */
static u32 add_index(tid_t tid, struct inode *ip, s64 bn, int slot)
{
        struct super_block *sb = ip->i_sb;
        struct jfs_sb_info *sbi = JFS_SBI(sb);
        struct jfs_inode_info *jfs_ip = JFS_IP(ip);
        u64 blkno;
        struct dir_table_slot *dirtab_slot;
        u32 index;
        struct linelock *llck;
        struct lv *lv;
        struct metapage *mp;
        s64 offset;
        uint page_offset;
        struct tlock *tlck;
        s64 xaddr;

        ASSERT(DO_INDEX(ip));

        if (jfs_ip->next_index < 2) {
                jfs_warn("add_index: next_index = %d.  Resetting!",
                           jfs_ip->next_index);
                jfs_ip->next_index = 2;
        }

        index = jfs_ip->next_index++;

        if (index <= MAX_INLINE_DIRTABLE_ENTRY) {
                /*
                 * i_size reflects size of index table, or 8 bytes per entry.
                 */
                ip->i_size = (loff_t) (index - 1) << 3;

                /*
                 * dir table fits inline within inode
                 */
                dirtab_slot = &jfs_ip->i_dirtable[index-2];
                dirtab_slot->flag = DIR_INDEX_VALID;
                dirtab_slot->slot = slot;
                DTSaddress(dirtab_slot, bn);

                set_cflag(COMMIT_Dirtable, ip);

                return index;
        }
        if (index == (MAX_INLINE_DIRTABLE_ENTRY + 1)) {
                struct dir_table_slot temp_table[12];

                /*
                 * It's time to move the inline table to an external
                 * page and begin to build the xtree
                 */
                if (dquot_alloc_block(ip, sbi->nbperpage))
                        goto clean_up;
                if (dbAlloc(ip, 0, sbi->nbperpage, &xaddr)) {
                        dquot_free_block(ip, sbi->nbperpage);
                        goto clean_up;
                }

                /*
                 * Save the table, we're going to overwrite it with the
                 * xtree root
                 */
                memcpy(temp_table, &jfs_ip->i_dirtable, sizeof(temp_table));

                /*
                 * Initialize empty x-tree
                 */
                xtInitRoot(tid, ip);

                /*
                 * Add the first block to the xtree
                 */
                if (xtInsert(tid, ip, 0, 0, sbi->nbperpage, &xaddr, 0)) {
                        /* This really shouldn't fail */
                        jfs_warn("add_index: xtInsert failed!");
                        memcpy(&jfs_ip->i_dirtable, temp_table,
                               sizeof (temp_table));
                        dbFree(ip, xaddr, sbi->nbperpage);
                        dquot_free_block(ip, sbi->nbperpage);
                        goto clean_up;
                }
                ip->i_size = PSIZE;

                mp = get_index_page(ip, 0);
                if (!mp) {
                        jfs_err("add_index: get_metapage failed!");
                        xtTruncate(tid, ip, 0, COMMIT_PWMAP);
                        memcpy(&jfs_ip->i_dirtable, temp_table,
                               sizeof (temp_table));
                        goto clean_up;
                }
                tlck = txLock(tid, ip, mp, tlckDATA);
                llck = (struct linelock *) & tlck->lock;
                ASSERT(llck->index == 0);
                lv = &llck->lv[0];

                lv->offset = 0;
                lv->length = 6; /* tlckDATA slot size is 16 bytes */
                llck->index++;

                memcpy(mp->data, temp_table, sizeof(temp_table));

                mark_metapage_dirty(mp);
                release_metapage(mp);

                /*
                 * Logging is now directed by xtree tlocks
                 */
                clear_cflag(COMMIT_Dirtable, ip);
        }

        offset = (index - 2) * sizeof(struct dir_table_slot);
        page_offset = offset & (PSIZE - 1);
        blkno = ((offset + 1) >> L2PSIZE) << sbi->l2nbperpage;
        if (page_offset == 0) {
                /*
                 * This will be the beginning of a new page
                 */
                xaddr = 0;
                if (xtInsert(tid, ip, 0, blkno, sbi->nbperpage, &xaddr, 0)) {
                        jfs_warn("add_index: xtInsert failed!");
                        goto clean_up;
                }
                ip->i_size += PSIZE;

                if ((mp = get_index_page(ip, blkno)))
                        memset(mp->data, 0, PSIZE);     /* Just looks better */
                else
                        xtTruncate(tid, ip, offset, COMMIT_PWMAP);
        } else
                mp = read_index_page(ip, blkno);

        if (!mp) {
                jfs_err("add_index: get/read_metapage failed!");
                goto clean_up;
        }

        lock_index(tid, ip, mp, index);

        dirtab_slot =
            (struct dir_table_slot *) ((char *) mp->data + page_offset);
        dirtab_slot->flag = DIR_INDEX_VALID;
        dirtab_slot->slot = slot;
        DTSaddress(dirtab_slot, bn);

        mark_metapage_dirty(mp);
        release_metapage(mp);

        return index;

      clean_up:

        jfs_ip->next_index--;

        return 0;
}

/*
 *      free_index()
 *
 *      Marks an entry to the directory index table as free.
 */
static void free_index(tid_t tid, struct inode *ip, u32 index, u32 next)
{
        struct dir_table_slot *dirtab_slot;
        s64 lblock;
        struct metapage *mp = NULL;

        dirtab_slot = find_index(ip, index, &mp, &lblock);

        if (!dirtab_slot)
                return;

        dirtab_slot->flag = DIR_INDEX_FREE;
        dirtab_slot->slot = dirtab_slot->addr1 = 0;
        dirtab_slot->addr2 = cpu_to_le32(next);

        if (mp) {
                lock_index(tid, ip, mp, index);
                mark_metapage_dirty(mp);
                release_metapage(mp);
        } else
                set_cflag(COMMIT_Dirtable, ip);
}

/*
 *      modify_index()
 *
 *      Changes an entry in the directory index table
 */
static void modify_index(tid_t tid, struct inode *ip, u32 index, s64 bn,
                         int slot, struct metapage ** mp, s64 *lblock)
{
        struct dir_table_slot *dirtab_slot;

        dirtab_slot = find_index(ip, index, mp, lblock);

        if (!dirtab_slot)
                return;

        DTSaddress(dirtab_slot, bn);
        dirtab_slot->slot = slot;

        if (*mp) {
                lock_index(tid, ip, *mp, index);
                mark_metapage_dirty(*mp);
        } else
                set_cflag(COMMIT_Dirtable, ip);
}

/*
 *      read_index()
 *
 *      reads a directory table slot
 */
static int read_index(struct inode *ip, u32 index,
                     struct dir_table_slot * dirtab_slot)
{
        s64 lblock;
        struct metapage *mp = NULL;
        struct dir_table_slot *slot;

        slot = find_index(ip, index, &mp, &lblock);
        if (!slot) {
                return -EIO;
        }

        memcpy(dirtab_slot, slot, sizeof(struct dir_table_slot));

        if (mp)
                release_metapage(mp);

        return 0;
}

/*
 *      dtSearch()
 *
 * function:
 *      Search for the entry with specified key
 *
 * parameter:
 *
 * return: 0 - search result on stack, leaf page pinned;
 *         errno - I/O error
 */
int dtSearch(struct inode *ip, struct component_name * key, ino_t * data,
             struct btstack * btstack, int flag)
{
        int rc = 0;
        int cmp = 1;            /* init for empty page */
        s64 bn;
        struct metapage *mp;
        dtpage_t *p;
        s8 *stbl;
        int base, index, lim;
        struct btframe *btsp;
        pxd_t *pxd;
        int psize = 288;        /* initial in-line directory */
        ino_t inumber;
        struct component_name ciKey;
        struct super_block *sb = ip->i_sb;

        ciKey.name = kmalloc((JFS_NAME_MAX + 1) * sizeof(wchar_t), GFP_NOFS);
        if (!ciKey.name) {
                rc = -ENOMEM;
                goto dtSearch_Exit2;
        }


        /* uppercase search key for c-i directory */
        UniStrcpy(ciKey.name, key->name);
        ciKey.namlen = key->namlen;

        /* only uppercase if case-insensitive support is on */
        if ((JFS_SBI(sb)->mntflag & JFS_OS2) == JFS_OS2) {
                ciToUpper(&ciKey);
        }
        BT_CLR(btstack);        /* reset stack */

        /* init level count for max pages to split */
        btstack->nsplit = 1;

        /*
         *      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 */
                DT_GETPAGE(ip, bn, mp, psize, p, rc);
                if (rc)
                        goto dtSearch_Exit1;

                /* get sorted entry table of the page */
                stbl = DT_GETSTBL(p);

                /*
                 * binary search with search key K on the current page.
                 */
                for (base = 0, lim = p->header.nextindex; lim; lim >>= 1) {
                        index = base + (lim >> 1);

                        if (p->header.flag & BT_LEAF) {
                                /* uppercase leaf name to compare */
                                cmp =
                                    ciCompare(&ciKey, p, stbl[index],
                                              JFS_SBI(sb)->mntflag);
                        } else {
                                /* router key is in uppercase */

                                cmp = dtCompare(&ciKey, p, stbl[index]);


                        }
                        if (cmp == 0) {
                                /*
                                 *      search hit
                                 */
                                /* search hit - leaf page:
                                 * return the entry found
                                 */
                                if (p->header.flag & BT_LEAF) {
                                        inumber = le32_to_cpu(
                        ((struct ldtentry *) & p->slot[stbl[index]])->inumber);

                                        /*
                                         * search for JFS_LOOKUP
                                         */
                                        if (flag == JFS_LOOKUP) {
                                                *data = inumber;
                                                rc = 0;
                                                goto out;
                                        }

                                        /*
                                         * search for JFS_CREATE
                                         */
                                        if (flag == JFS_CREATE) {
                                                *data = inumber;
                                                rc = -EEXIST;
                                                goto out;
                                        }

                                        /*
                                         * search for JFS_REMOVE or JFS_RENAME
                                         */
                                        if ((flag == JFS_REMOVE ||
                                             flag == JFS_RENAME) &&
                                            *data != inumber) {
                                                rc = -ESTALE;
                                                goto out;
                                        }

                                        /*
                                         * JFS_REMOVE|JFS_FINDDIR|JFS_RENAME
                                         */
                                        /* save search result */
                                        *data = inumber;
                                        btsp = btstack->top;
                                        btsp->bn = bn;
                                        btsp->index = index;
                                        btsp->mp = mp;

                                        rc = 0;
                                        goto dtSearch_Exit1;
                                }

                                /* search hit - internal page:
                                 * descend/search its child page
                                 */
                                goto getChild;
                        }

                        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 (maxindex + 1) index.
                 */
                /*
                 * 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) {
                        /*
                         * search for JFS_LOOKUP, JFS_REMOVE, or JFS_RENAME
                         */
                        if (flag == JFS_LOOKUP || flag == JFS_REMOVE ||
                            flag == JFS_RENAME) {
                                rc = -ENOENT;
                                goto out;
                        }

                        /*
                         * search for JFS_CREATE|JFS_FINDDIR:
                         *
                         * save search result
                         */
                        *data = 0;
                        btsp = btstack->top;
                        btsp->bn = bn;
                        btsp->index = base;
                        btsp->mp = mp;

                        rc = 0;
                        goto dtSearch_Exit1;
                }

                /*
                 * search miss - internal 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
                 */
              getChild:
                /* update max. number of pages to split */
                if (BT_STACK_FULL(btstack)) {
                        /* Something's corrupted, mark filesystem dirty so
                         * chkdsk will fix it.
                         */
                        jfs_error(sb, "stack overrun in dtSearch!");
                        BT_STACK_DUMP(btstack);
                        rc = -EIO;
                        goto out;
                }
                btstack->nsplit++;

                /* push (bn, index) of the parent page/entry */
                BT_PUSH(btstack, bn, index);

                /* get the child page block number */
                pxd = (pxd_t *) & p->slot[stbl[index]];
                bn = addressPXD(pxd);
                psize = lengthPXD(pxd) << JFS_SBI(ip->i_sb)->l2bsize;

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

      out:
        DT_PUTPAGE(mp);

      dtSearch_Exit1:

        kfree(ciKey.name);

      dtSearch_Exit2:

        return rc;
}


/*
 *      dtInsert()
 *
 * function: insert an entry to directory tree
 *
 * parameter:
 *
 * return: 0 - success;
 *         errno - failure;
 */
int dtInsert(tid_t tid, struct inode *ip,
         struct component_name * name, ino_t * fsn, struct btstack * btstack)
{
        int rc = 0;
        struct metapage *mp;    /* meta-page buffer */
        dtpage_t *p;            /* base B+-tree index page */
        s64 bn;
        int index;
        struct dtsplit split;   /* split information */
        ddata_t data;
        struct dt_lock *dtlck;
        int n;
        struct tlock *tlck;
        struct lv *lv;

        /*
         *      retrieve search result
         *
         * dtSearch() returns (leaf page pinned, index at which to insert).
         * n.b. dtSearch() may return index of (maxindex + 1) of
         * the full page.
         */
        DT_GETSEARCH(ip, btstack->top, bn, mp, p, index);

        /*
         *      insert entry for new key
         */
        if (DO_INDEX(ip)) {
                if (JFS_IP(ip)->next_index == DIREND) {
                        DT_PUTPAGE(mp);
                        return -EMLINK;
                }
                n = NDTLEAF(name->namlen);
                data.leaf.tid = tid;
                data.leaf.ip = ip;
        } else {
                n = NDTLEAF_LEGACY(name->namlen);
                data.leaf.ip = NULL;    /* signifies legacy directory format */
        }
        data.leaf.ino = *fsn;

        /*
         *      leaf page does not have enough room for new entry:
         *
         *      extend/split the leaf page;
         *
         * dtSplitUp() will insert the entry and unpin the leaf page.
         */
        if (n > p->header.freecnt) {
                split.mp = mp;
                split.index = index;
                split.nslot = n;
                split.key = name;
                split.data = &data;
                rc = dtSplitUp(tid, ip, &split, btstack);
                return rc;
        }

        /*
         *      leaf page does have enough room for new entry:
         *
         *      insert the new data entry into the leaf page;
         */
        BT_MARK_DIRTY(mp, ip);
        /*
         * acquire a transaction lock on the leaf page
         */
        tlck = txLock(tid, ip, mp, tlckDTREE | tlckENTRY);
        dtlck = (struct dt_lock *) & tlck->lock;
        ASSERT(dtlck->index == 0);
        lv = & dtlck->lv[0];

        /* linelock header */
        lv->offset = 0;
        lv->length = 1;
        dtlck->index++;

        dtInsertEntry(p, index, name, &data, &dtlck);

        /* linelock stbl of non-root leaf page */
        if (!(p->header.flag & BT_ROOT)) {
                if (dtlck->index >= dtlck->maxcnt)
                        dtlck = (struct dt_lock *) txLinelock(dtlck);
                lv = & dtlck->lv[dtlck->index];
                n = index >> L2DTSLOTSIZE;
                lv->offset = p->header.stblindex + n;
                lv->length =
                    ((p->header.nextindex - 1) >> L2DTSLOTSIZE) - n + 1;
                dtlck->index++;
        }

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

        return 0;
}


/*
 *      dtSplitUp()
 *
 * function: propagate insertion bottom up;
 *
 * parameter:
 *
 * return: 0 - success;
 *         errno - failure;
 *      leaf page unpinned;
 */
static int dtSplitUp(tid_t tid,
          struct inode *ip, struct dtsplit * split, struct btstack * btstack)
{
        struct jfs_sb_info *sbi = JFS_SBI(ip->i_sb);
        int rc = 0;
        struct metapage *smp;
        dtpage_t *sp;           /* split page */
        struct metapage *rmp;
        dtpage_t *rp;           /* new right page split from sp */
        pxd_t rpxd;             /* new right page extent descriptor */
        struct metapage *lmp;
        dtpage_t *lp;           /* left child page */
        int skip;               /* index of entry of insertion */
        struct btframe *parent; /* parent page entry on traverse stack */
        s64 xaddr, nxaddr;
        int xlen, xsize;
        struct pxdlist pxdlist;
        pxd_t *pxd;
        struct component_name key = { 0, NULL };
        ddata_t *data = split->data;
        int n;
        struct dt_lock *dtlck;
        struct tlock *tlck;
        struct lv *lv;
        int quota_allocation = 0;

        /* get split page */
        smp = split->mp;
        sp = DT_PAGE(ip, smp);

        key.name = kmalloc((JFS_NAME_MAX + 2) * sizeof(wchar_t), GFP_NOFS);
        if (!key.name) {
                DT_PUTPAGE(smp);
                rc = -ENOMEM;
                goto dtSplitUp_Exit;
        }

        /*
         *      split leaf page
         *
         * The split routines insert the new entry, and
         * acquire txLock as appropriate.
         */
        /*
         *      split root leaf page:
         */
        if (sp->header.flag & BT_ROOT) {
                /*
                 * allocate a single extent child page
                 */
                xlen = 1;
                n = sbi->bsize >> L2DTSLOTSIZE;
                n -= (n + 31) >> L2DTSLOTSIZE;  /* stbl size */
                n -= DTROOTMAXSLOT - sp->header.freecnt; /* header + entries */
                if (n <= split->nslot)
                        xlen++;
                if ((rc = dbAlloc(ip, 0, (s64) xlen, &xaddr))) {
                        DT_PUTPAGE(smp);
                        goto freeKeyName;
                }

                pxdlist.maxnpxd = 1;
                pxdlist.npxd = 0;
                pxd = &pxdlist.pxd[0];
                PXDaddress(pxd, xaddr);
                PXDlength(pxd, xlen);
                split->pxdlist = &pxdlist;
                rc = dtSplitRoot(tid, ip, split, &rmp);

                if (rc)
                        dbFree(ip, xaddr, xlen);
                else
                        DT_PUTPAGE(rmp);

                DT_PUTPAGE(smp);

                if (!DO_INDEX(ip))
                        ip->i_size = xlen << sbi->l2bsize;

                goto freeKeyName;
        }

        /*
         *      extend first leaf page
         *
         * extend the 1st extent if less than buffer page size
         * (dtExtendPage() reurns leaf page unpinned)
         */
        pxd = &sp->header.self;
        xlen = lengthPXD(pxd);
        xsize = xlen << sbi->l2bsize;
        if (xsize < PSIZE) {
                xaddr = addressPXD(pxd);
                n = xsize >> L2DTSLOTSIZE;
                n -= (n + 31) >> L2DTSLOTSIZE;  /* stbl size */
                if ((n + sp->header.freecnt) <= split->nslot)
                        n = xlen + (xlen << 1);
                else
                        n = xlen;

                /* Allocate blocks to quota. */
                rc = dquot_alloc_block(ip, n);
                if (rc)
                        goto extendOut;
                quota_allocation += n;

                if ((rc = dbReAlloc(sbi->ipbmap, xaddr, (s64) xlen,
                                    (s64) n, &nxaddr)))
                        goto extendOut;

                pxdlist.maxnpxd = 1;
                pxdlist.npxd = 0;
                pxd = &pxdlist.pxd[0];
                PXDaddress(pxd, nxaddr)
                    PXDlength(pxd, xlen + n);
                split->pxdlist = &pxdlist;
                if ((rc = dtExtendPage(tid, ip, split, btstack))) {
                        nxaddr = addressPXD(pxd);
                        if (xaddr != nxaddr) {
                                /* free relocated extent */
                                xlen = lengthPXD(pxd);
                                dbFree(ip, nxaddr, (s64) xlen);
                        } else {
                                /* free extended delta */
                                xlen = lengthPXD(pxd) - n;
                                xaddr = addressPXD(pxd) + xlen;
                                dbFree(ip, xaddr, (s64) n);
                        }
                } else if (!DO_INDEX(ip))
                        ip->i_size = lengthPXD(pxd) << sbi->l2bsize;


              extendOut:
                DT_PUTPAGE(smp);
                goto freeKeyName;
        }

        /*
         *      split leaf page <sp> into <sp> and a new right page <rp>.
         *
         * return <rp> pinned and its extent descriptor <rpxd>
         */
        /*
         * allocate new directory page extent and
         * new index page(s) to cover page split(s)
         *
         * allocation hint: ?
         */
        n = btstack->nsplit;
        pxdlist.maxnpxd = pxdlist.npxd = 0;
        xlen = sbi->nbperpage;
        for (pxd = pxdlist.pxd; n > 0; n--, pxd++) {
                if ((rc = dbAlloc(ip, 0, (s64) xlen, &xaddr)) == 0) {
                        PXDaddress(pxd, xaddr);
                        PXDlength(pxd, xlen);
                        pxdlist.maxnpxd++;
                        continue;
                }

                DT_PUTPAGE(smp);

                /* undo allocation */
                goto splitOut;
        }

        split->pxdlist = &pxdlist;
        if ((rc = dtSplitPage(tid, ip, split, &rmp, &rp, &rpxd))) {
                DT_PUTPAGE(smp);

                /* undo allocation */
                goto splitOut;
        }

        if (!DO_INDEX(ip))
                ip->i_size += PSIZE;

        /*
         * 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 4 pages pinned at any time:
         * two children, left parent and right parent (when the parent splits).
         * keep the child pages 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 (<lp>, <rp>) pinned */
                lmp = smp;
                lp = sp;

                /*
                 * insert router entry in parent for new right child page <rp>
                 */
                /* get the parent page <sp> */
                DT_GETPAGE(ip, parent->bn, smp, PSIZE, sp, rc);
                if (rc) {
                        DT_PUTPAGE(lmp);
                        DT_PUTPAGE(rmp);
                        goto splitOut;
                }

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

                /*
                 * compute the key for the router entry
                 *
                 * key suffix compression:
                 * for internal pages that have leaf pages as children,
                 * retain only what's needed to distinguish between
                 * the new entry and the entry on the page to its left.
                 * If the keys compare equal, retain the entire key.
                 *
                 * note that compression is performed only at computing
                 * router key at the lowest internal level.
                 * further compression of the key between pairs of higher
                 * level internal pages loses too much information and
                 * the search may fail.
                 * (e.g., two adjacent leaf pages of {a, ..., x} {xx, ...,}
                 * results in two adjacent parent entries (a)(xx).
                 * if split occurs between these two entries, and
                 * if compression is applied, the router key of parent entry
                 * of right page (x) will divert search for x into right
                 * subtree and miss x in the left subtree.)
                 *
                 * the entire key must be retained for the next-to-leftmost
                 * internal key at any level of the tree, or search may fail
                 * (e.g., ?)
                 */
                switch (rp->header.flag & BT_TYPE) {
                case BT_LEAF:
                        /*
                         * compute the length of prefix for suffix compression
                         * between last entry of left page and first entry
                         * of right page
                         */
                        if ((sp->header.flag & BT_ROOT && skip > 1) ||
                            sp->header.prev != 0 || skip > 1) {
                                /* compute uppercase router prefix key */
                                rc = ciGetLeafPrefixKey(lp,
                                                        lp->header.nextindex-1,
                                                        rp, 0, &key,
                                                        sbi->mntflag);
                                if (rc) {
                                        DT_PUTPAGE(lmp);
                                        DT_PUTPAGE(rmp);
                                        DT_PUTPAGE(smp);
                                        goto splitOut;
                                }
                        } else {
                                /* next to leftmost entry of
                                   lowest internal level */

                                /* compute uppercase router key */
                                dtGetKey(rp, 0, &key, sbi->mntflag);
                                key.name[key.namlen] = 0;

                                if ((sbi->mntflag & JFS_OS2) == JFS_OS2)
                                        ciToUpper(&key);
                        }

                        n = NDTINTERNAL(key.namlen);
                        break;

                case BT_INTERNAL:
                        dtGetKey(rp, 0, &key, sbi->mntflag);
                        n = NDTINTERNAL(key.namlen);
                        break;

                default:
                        jfs_err("dtSplitUp(): UFO!");
                        break;
                }

                /* unpin left child page */
                DT_PUTPAGE(lmp);

                /*
                 * compute the data for the router entry
                 */
                data->xd = rpxd;        /* child page xd */

                /*
                 * parent page is full - split the parent page
                 */
                if (n > sp->header.freecnt) {
                        /* init for parent page split */
                        split->mp = smp;
                        split->index = skip;    /* index at insert */
                        split->nslot = n;
                        split->key = &key;
                        /* split->data = data; */

                        /* unpin right child page */
                        DT_PUTPAGE(rmp);

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

                        /* smp and rmp are pinned */
                }
                /*
                 * parent page is not full - insert router entry in parent page
                 */
                else {
                        BT_MARK_DIRTY(smp, ip);
                        /*
                         * acquire a transaction lock on the parent page
                         */
                        tlck = txLock(tid, ip, smp, tlckDTREE | tlckENTRY);
                        dtlck = (struct dt_lock *) & tlck->lock;
                        ASSERT(dtlck->index == 0);
                        lv = & dtlck->lv[0];

                        /* linelock header */
                        lv->offset = 0;
                        lv->length = 1;
                        dtlck->index++;

                        /* linelock stbl of non-root parent page */
                        if (!(sp->header.flag & BT_ROOT)) {
                                lv++;
                                n = skip >> L2DTSLOTSIZE;
                                lv->offset = sp->header.stblindex + n;
                                lv->length =
                                    ((sp->header.nextindex -
                                      1) >> L2DTSLOTSIZE) - n + 1;
                                dtlck->index++;
                        }

                        dtInsertEntry(sp, skip, &key, data, &dtlck);

                        /* exit propagate up */
                        break;
                }
        }

        /* unpin current split and its right page */
        DT_PUTPAGE(smp);
        DT_PUTPAGE(rmp);

        /*
         * free remaining extents allocated for split
         */
      splitOut:
        n = pxdlist.npxd;
        pxd = &pxdlist.pxd[n];
        for (; n < pxdlist.maxnpxd; n++, pxd++)
                dbFree(ip, addressPXD(pxd), (s64) lengthPXD(pxd));

      freeKeyName:
        kfree(key.name);

        /* Rollback quota allocation */
        if (rc && quota_allocation)
                dquot_free_block(ip, quota_allocation);

      dtSplitUp_Exit:

        return rc;
}


/*
 *      dtSplitPage()
 *
 * function: Split a non-root page of a btree.
 *
 * parameter:
 *
 * return: 0 - success;
 *         errno - failure;
 *      return split and new page pinned;
 */
static int dtSplitPage(tid_t tid, struct inode *ip, struct dtsplit * split,
            struct metapage ** rmpp, dtpage_t ** rpp, pxd_t * rpxdp)
{
        int rc = 0;
        struct metapage *smp;
        dtpage_t *sp;
        struct metapage *rmp;
        dtpage_t *rp;           /* new right page allocated */
        s64 rbn;                /* new right page block number */
        struct metapage *mp;
        dtpage_t *p;
        s64 nextbn;
        struct pxdlist *pxdlist;
        pxd_t *pxd;
        int skip, nextindex, half, left, nxt, off, si;
        struct ldtentry *ldtentry;
        struct idtentry *idtentry;
        u8 *stbl;
        struct dtslot *f;
        int fsi, stblsize;
        int n;
        struct dt_lock *sdtlck, *rdtlck;
        struct tlock *tlck;
        struct dt_lock *dtlck;
        struct lv *slv, *rlv, *lv;

        /* get split page */
        smp = split->mp;
        sp = DT_PAGE(ip, smp);

        /*
         * allocate the new right page for the split
         */
        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("dtSplitPage: ip:0x%p smp:0x%p rmp:0x%p", ip, smp, rmp);

        BT_MARK_DIRTY(rmp, ip);
        /*
         * acquire a transaction lock on the new right page
         */
        tlck = txLock(tid, ip, rmp, tlckDTREE | tlckNEW);
        rdtlck = (struct dt_lock *) & tlck->lock;

        rp = (dtpage_t *) rmp->data;
        *rpp = rp;
        rp->header.self = *pxd;

        BT_MARK_DIRTY(smp, ip);
        /*
         * acquire a transaction lock on the split page
         *
         * action:
         */
        tlck = txLock(tid, ip, smp, tlckDTREE | tlckENTRY);
        sdtlck = (struct dt_lock *) & tlck->lock;

        /* linelock header of split page */
        ASSERT(sdtlck->index == 0);
        slv = & sdtlck->lv[0];
        slv->offset = 0;
        slv->length = 1;
        sdtlck->index++;

        /*
         * initialize/update sibling pointers between 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);

        /*
         * initialize new right page
         */
        rp->header.flag = sp->header.flag;

        /* compute sorted entry table at start of extent data area */
        rp->header.nextindex = 0;
        rp->header.stblindex = 1;

        n = PSIZE >> L2DTSLOTSIZE;
        rp->header.maxslot = n;
        stblsize = (n + 31) >> L2DTSLOTSIZE;    /* in unit of slot */

        /* init freelist */
        fsi = rp->header.stblindex + stblsize;
        rp->header.freelist = fsi;
        rp->header.freecnt = rp->header.maxslot - fsi;

        /*
         *      sequential append at tail: append without split
         *
         * 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'll just 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 && split->index == sp->header.nextindex) {
                /* linelock header + stbl (first slot) of new page */
                rlv = & rdtlck->lv[rdtlck->index];
                rlv->offset = 0;
                rlv->length = 2;
                rdtlck->index++;

                /*
                 * initialize freelist of new right page
                 */
                f = &rp->slot[fsi];
                for (fsi++; fsi < rp->header.maxslot; f++, fsi++)
                        f->next = fsi;
                f->next = -1;

                /* insert entry at the first entry of the new right page */
                dtInsertEntry(rp, 0, split->key, split->data, &rdtlck);

                goto out;
        }

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

        /*
         * update prev pointer of previous right sibling page;
         */
        if (nextbn != 0) {
                DT_GETPAGE(ip, nextbn, mp, PSIZE, p, rc);
                if (rc) {
                        discard_metapage(rmp);
                        return rc;
                }

                BT_MARK_DIRTY(mp, ip);
                /*
                 * acquire a transaction lock on the next page
                 */
                tlck = txLock(tid, ip, mp, tlckDTREE | tlckRELINK);
                jfs_info("dtSplitPage: tlck = 0x%p, ip = 0x%p, mp=0x%p",
                        tlck, ip, mp);
                dtlck = (struct dt_lock *) & tlck->lock;

                /* linelock header of previous right sibling page */
                lv = & dtlck->lv[dtlck->index];
                lv->offset = 0;
                lv->length = 1;
                dtlck->index++;

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

                DT_PUTPAGE(mp);
        }

        /*
         * split the data between the split and right pages.
         */
        skip = split->index;
        half = (PSIZE >> L2DTSLOTSIZE) >> 1;    /* swag */
        left = 0;

        /*
         *      compute fill factor for split pages
         *
         * <nxt> traces the next entry to move to rp
         * <off> traces the next entry to stay in sp
         */
        stbl = (u8 *) & sp->slot[sp->header.stblindex];
        nextindex = sp->header.nextindex;
        for (nxt = off = 0; nxt < nextindex; ++off) {
                if (off == skip)
                        /* check for fill factor with new entry size */
                        n = split->nslot;
                else {
                        si = stbl[nxt];
                        switch (sp->header.flag & BT_TYPE) {
                        case BT_LEAF:
                                ldtentry = (struct ldtentry *) & sp->slot[si];
                                if (DO_INDEX(ip))
                                        n = NDTLEAF(ldtentry->namlen);
                                else
                                        n = NDTLEAF_LEGACY(ldtentry->
                                                           namlen);
                                break;

                        case BT_INTERNAL:
                                idtentry = (struct idtentry *) & sp->slot[si];
                                n = NDTINTERNAL(idtentry->namlen);
                                break;

                        default:
                                break;
                        }

                        ++nxt;  /* advance to next entry to move in sp */
                }

                left += n;
                if (left >= half)
                        break;
        }

        /* <nxt> poins to the 1st entry to move */

        /*
         *      move entries to right page
         *
         * dtMoveEntry() initializes rp and reserves entry for insertion
         *
         * split page moved out entries are linelocked;
         * new/right page moved in entries are linelocked;
         */
        /* linelock header + stbl of new right page */
        rlv = & rdtlck->lv[rdtlck->index];
        rlv->offset = 0;
        rlv->length = 5;
        rdtlck->index++;

        dtMoveEntry(sp, nxt, rp, &sdtlck, &rdtlck, DO_INDEX(ip));

        sp->header.nextindex = nxt;

        /*
         * finalize freelist of new right page
         */
        fsi = rp->header.freelist;
        f = &rp->slot[fsi];
        for (fsi++; fsi < rp->header.maxslot; f++, fsi++)
                f->next = fsi;
        f->next = -1;

        /*
         * Update directory index table for entries now in right page
         */
        if ((rp->header.flag & BT_LEAF) && DO_INDEX(ip)) {
                s64 lblock;

                mp = NULL;
                stbl = DT_GETSTBL(rp);
                for (n = 0; n < rp->header.nextindex; n++) {
                        ldtentry = (struct ldtentry *) & rp->slot[stbl[n]];
                        modify_index(tid, ip, le32_to_cpu(ldtentry->index),
                                     rbn, n, &mp, &lblock);
                }
                if (mp)
                        release_metapage(mp);
        }

        /*
         * the skipped index was on the left page,
         */
        if (skip <= off) {
                /* insert the new entry in the split page */
                dtInsertEntry(sp, skip, split->key, split->data, &sdtlck);

                /* linelock stbl of split page */
                if (sdtlck->index >= sdtlck->maxcnt)
                        sdtlck = (struct dt_lock *) txLinelock(sdtlck);
                slv = & sdtlck->lv[sdtlck->index];
                n = skip >> L2DTSLOTSIZE;
                slv->offset = sp->header.stblindex + n;
                slv->length =
                    ((sp->header.nextindex - 1) >> L2DTSLOTSIZE) - n + 1;
                sdtlck->index++;
        }
        /*
         * the skipped index was on the right page,
         */
        else {
                /* adjust the skip index to reflect the new position */
                skip -= nxt;

                /* insert the new entry in the right page */
                dtInsertEntry(rp, skip, split->key, split->data, &rdtlck);
        }

      out:
        *rmpp = rmp;
        *rpxdp = *pxd;

        return rc;
}


/*
 *      dtExtendPage()
 *
 * function: extend 1st/only directory leaf page
 *
 * parameter:
 *
 * return: 0 - success;
 *         errno - failure;
 *      return extended page pinned;
 */
static int dtExtendPage(tid_t tid,
             struct inode *ip, struct dtsplit * split, struct btstack * btstack)
{
        struct super_block *sb = ip->i_sb;
        int rc;
        struct metapage *smp, *pmp, *mp;
        dtpage_t *sp, *pp;
        struct pxdlist *pxdlist;
        pxd_t *pxd, *tpxd;
        int xlen, xsize;
        int newstblindex, newstblsize;
        int oldstblindex, oldstblsize;
        int fsi, last;
        struct dtslot *f;
        struct btframe *parent;
        int n;
        struct dt_lock *dtlck;
        s64 xaddr, txaddr;
        struct tlock *tlck;
        struct pxd_lock *pxdlock;
        struct lv *lv;
        uint type;
        struct ldtentry *ldtentry;
        u8 *stbl;

        /* get page to extend */
        smp = split->mp;
        sp = DT_PAGE(ip, smp);

        /* get parent/root page */
        parent = BT_POP(btstack);
        DT_GETPAGE(ip, parent->bn, pmp, PSIZE, pp, rc);
        if (rc)
                return (rc);

        /*
         *      extend the extent
         */
        pxdlist = split->pxdlist;
        pxd = &pxdlist->pxd[pxdlist->npxd];
        pxdlist->npxd++;

        xaddr = addressPXD(pxd);
        tpxd = &sp->header.self;
        txaddr = addressPXD(tpxd);
        /* in-place extension */
        if (xaddr == txaddr) {
                type = tlckEXTEND;
        }
        /* relocation */
        else {
                type = tlckNEW;

                /* save moved extent descriptor for later free */
                tlck = txMaplock(tid, ip, tlckDTREE | tlckRELOCATE);
                pxdlock = (struct pxd_lock *) & tlck->lock;
                pxdlock->flag = mlckFREEPXD;
                pxdlock->pxd = sp->header.self;
                pxdlock->index = 1;

                /*
                 * Update directory index table to reflect new page address
                 */
                if (DO_INDEX(ip)) {
                        s64 lblock;

                        mp = NULL;
                        stbl = DT_GETSTBL(sp);
                        for (n = 0; n < sp->header.nextindex; n++) {
                                ldtentry =
                                    (struct ldtentry *) & sp->slot[stbl[n]];
                                modify_index(tid, ip,
                                             le32_to_cpu(ldtentry->index),
                                             xaddr, n, &mp, &lblock);
                        }
                        if (mp)
                                release_metapage(mp);
                }
        }

        /*
         *      extend the page
         */
        sp->header.self = *pxd;

        jfs_info("dtExtendPage: ip:0x%p smp:0x%p sp:0x%p", ip, smp, sp);

        BT_MARK_DIRTY(smp, ip);
        /*
         * acquire a transaction lock on the extended/leaf page
         */
        tlck = txLock(tid, ip, smp, tlckDTREE | type);
        dtlck = (struct dt_lock *) & tlck->lock;
        lv = & dtlck->lv[0];

        /* update buffer extent descriptor of extended page */
        xlen = lengthPXD(pxd);
        xsize = xlen << JFS_SBI(sb)->l2bsize;

        /*
         * copy old stbl to new stbl at start of extended area
         */
        oldstblindex = sp->header.stblindex;
        oldstblsize = (sp->header.maxslot + 31) >> L2DTSLOTSIZE;
        newstblindex = sp->header.maxslot;
        n = xsize >> L2DTSLOTSIZE;
        newstblsize = (n + 31) >> L2DTSLOTSIZE;
        memcpy(&sp->slot[newstblindex], &sp->slot[oldstblindex],
               sp->header.nextindex);

        /*
         * in-line extension: linelock old area of extended page
         */
        if (type == tlckEXTEND) {
                /* linelock header */
                lv->offset = 0;
                lv->length = 1;
                dtlck->index++;
                lv++;

                /* linelock new stbl of extended page */
                lv->offset = newstblindex;
                lv->length = newstblsize;
        }
        /*
         * relocation: linelock whole relocated area
         */
        else {
                lv->offset = 0;
                lv->length = sp->header.maxslot + newstblsize;
        }

        dtlck->index++;

        sp->header.maxslot = n;
        sp->header.stblindex = newstblindex;
        /* sp->header.nextindex remains the same */

        /*
         * add old stbl region at head of freelist
         */
        fsi = oldstblindex;
        f = &sp->slot[fsi];
        last = sp->header.freelist;
        for (n = 0; n < oldstblsize; n++, fsi++, f++) {
                f->next = last;
                last = fsi;
        }
        sp->header.freelist = last;
        sp->header.freecnt += oldstblsize;

        /*
         * append free region of newly extended area at tail of freelist
         */
        /* init free region of newly extended area */
        fsi = n = newstblindex + newstblsize;
        f = &sp->slot[fsi];
        for (fsi++; fsi < sp->header.maxslot; f++, fsi++)
                f->next = fsi;
        f->next = -1;

        /* append new free region at tail of old freelist */
        fsi = sp->header.freelist;
        if (fsi == -1)
                sp->header.freelist = n;
        else {
                do {
                        f = &sp->slot[fsi];
                        fsi = f->next;
                } while (fsi != -1);

                f->next = n;
        }

        sp->header.freecnt += sp->header.maxslot - n;

        /*
         * insert the new entry
         */
        dtInsertEntry(sp, split->index, split->key, split->data, &dtlck);

        BT_MARK_DIRTY(pmp, ip);
        /*
         * linelock any freeslots residing in old extent
         */
        if (type == tlckEXTEND) {
                n = sp->header.maxslot >> 2;
                if (sp->header.freelist < n)
                        dtLinelockFreelist(sp, n, &dtlck);
        }

        /*
         *      update parent entry on the parent/root page
         */
        /*
         * acquire a transaction lock on the parent/root page
         */
        tlck = txLock(tid, ip, pmp, tlckDTREE | tlckENTRY);
        dtlck = (struct dt_lock *) & tlck->lock;
        lv = & dtlck->lv[dtlck->index];

        /* linelock parent entry - 1st slot */
        lv->offset = 1;
        lv->length = 1;
        dtlck->index++;

        /* update the parent pxd for page extension */
        tpxd = (pxd_t *) & pp->slot[1];
        *tpxd = *pxd;

        DT_PUTPAGE(pmp);
        return 0;
}


/*
 *      dtSplitRoot()
 *
 * 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:
 *
 * return: 0 - success;
 *         errno - failure;
 *      return new page pinned;
 */
static int dtSplitRoot(tid_t tid,
            struct inode *ip, struct dtsplit * split, struct metapage ** rmpp)
{
        struct super_block *sb = ip->i_sb;
        struct metapage *smp;
        dtroot_t *sp;
        struct metapage *rmp;
        dtpage_t *rp;
        s64 rbn;
        int xlen;
        int xsize;
        struct dtslot *f;
        s8 *stbl;
        int fsi, stblsize, n;
        struct idtentry *s;
        pxd_t *ppxd;
        struct pxdlist *pxdlist;
        pxd_t *pxd;
        struct dt_lock *dtlck;
        struct tlock *tlck;
        struct lv *lv;
        int rc;

        /* get split root page */
        smp = split->mp;
        sp = &JFS_IP(ip)->i_dtroot;

        /*
         *      allocate/initialize a single (right) child page
         *
         * N.B. at first split, a one (or two) block to fit new entry
         * is allocated; at subsequent split, a full page is allocated;
         */
        pxdlist = split->pxdlist;
        pxd = &pxdlist->pxd[pxdlist->npxd];
        pxdlist->npxd++;
        rbn = addressPXD(pxd);
        xlen = lengthPXD(pxd);
        xsize = xlen << JFS_SBI(sb)->l2bsize;
        rmp = get_metapage(ip, rbn, xsize, 1);
        if (!rmp)
                return -EIO;

        rp = rmp->data;

        /* Allocate blocks to quota. */
        rc = dquot_alloc_block(ip, lengthPXD(pxd));
        if (rc) {
                release_metapage(rmp);
                return rc;
        }

        BT_MARK_DIRTY(rmp, ip);
        /*
         * acquire a transaction lock on the new right page
         */
        tlck = txLock(tid, ip, rmp, tlckDTREE | tlckNEW);
        dtlck = (struct dt_lock *) & tlck->lock;

        rp->header.flag =
            (sp->header.flag & BT_LEAF) ? BT_LEAF : BT_INTERNAL;
        rp->header.self = *pxd;

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

        /*
         *      move in-line root page into new right page extent
         */
        /* linelock header + copied entries + new stbl (1st slot) in new page */
        ASSERT(dtlck->index == 0);
        lv = & dtlck->lv[0];
        lv->offset = 0;
        lv->length = 10;        /* 1 + 8 + 1 */
        dtlck->index++;

        n = xsize >> L2DTSLOTSIZE;
        rp->header.maxslot = n;
        stblsize = (n + 31) >> L2DTSLOTSIZE;

        /* copy old stbl to new stbl at start of extended area */
        rp->header.stblindex = DTROOTMAXSLOT;
        stbl = (s8 *) & rp->slot[DTROOTMAXSLOT];
        memcpy(stbl, sp->header.stbl, sp->header.nextindex);
        rp->header.nextindex = sp->header.nextindex;

        /* copy old data area to start of new data area */
        memcpy(&rp->slot[1], &sp->slot[1], IDATASIZE);

        /*
         * append free region of newly extended area at tail of freelist
         */
        /* init free region of newly extended area */
        fsi = n = DTROOTMAXSLOT + stblsize;
        f = &rp->slot[fsi];
        for (fsi++; fsi < rp->header.maxslot; f++, fsi++)
                f->next = fsi;
        f->next = -1;

        /* append new free region at tail of old freelist */
        fsi = sp->header.freelist;
        if (fsi == -1)
                rp->header.freelist = n;
        else {
                rp->header.freelist = fsi;

                do {
                        f = &rp->slot[fsi];
                        fsi = f->next;
                } while (fsi != -1);

                f->next = n;
        }

        rp->header.freecnt = sp->header.freecnt + rp->header.maxslot - n;

        /*
         * Update directory index table for entries now in right page
         */
        if ((rp->header.flag & BT_LEAF) && DO_INDEX(ip)) {
                s64 lblock;
                struct metapage *mp = NULL;
                struct ldtentry *ldtentry;

                stbl = DT_GETSTBL(rp);
                for (n = 0; n < rp->header.nextindex; n++) {
                        ldtentry = (struct ldtentry *) & rp->slot[stbl[n]];
                        modify_index(tid, ip, le32_to_cpu(ldtentry->index),
                                     rbn, n, &mp, &lblock);
                }
                if (mp)
                        release_metapage(mp);
        }
        /*
         * insert the new entry into the new right/child page
         * (skip index in the new right page will not change)
         */
        dtInsertEntry(rp, split->index, split->key, split->data, &dtlck);

        /*
         *      reset parent/root 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.
         *
         * The btree comparison code guarantees that the left-most key on any
         * level of the tree is never used, so it doesn't need to be filled in.
         */
        BT_MARK_DIRTY(smp, ip);
        /*
         * acquire a transaction lock on the root page (in-memory inode)
         */
        tlck = txLock(tid, ip, smp, tlckDTREE | tlckNEW | tlckBTROOT);
        dtlck = (struct dt_lock *) & tlck->lock;

        /* linelock root */
        ASSERT(dtlck->index == 0);
        lv = & dtlck->lv[0];
        lv->offset = 0;
        lv->length = DTROOTMAXSLOT;
        dtlck->index++;

        /* update page header of root */
        if (sp->header.flag & BT_LEAF) {
                sp->header.flag &= ~BT_LEAF;
                sp->header.flag |= BT_INTERNAL;
        }

        /* init the first entry */
        s = (struct idtentry *) & sp->slot[DTENTRYSTART];
        ppxd = (pxd_t *) s;
        *ppxd = *pxd;
        s->next = -1;
        s->namlen = 0;

        stbl = sp->header.stbl;
        stbl[0] = DTENTRYSTART;
        sp->header.nextindex = 1;

        /* init freelist */
        fsi = DTENTRYSTART + 1;
        f = &sp->slot[fsi];

        /* init free region of remaining area */
        for (fsi++; fsi < DTROOTMAXSLOT; f++, fsi++)
                f->next = fsi;
        f->next = -1;

        sp->header.freelist = DTENTRYSTART + 1;
        sp->header.freecnt = DTROOTMAXSLOT - (DTENTRYSTART + 1);

        *rmpp = rmp;

        return 0;
}


/*
 *      dtDelete()
 *
 * function: delete the entry(s) referenced by a key.
 *
 * parameter:
 *
 * return:
 */
int dtDelete(tid_t tid,
         struct inode *ip, struct component_name * key, ino_t * ino, int flag)
{
        int rc = 0;
        s64 bn;
        struct metapage *mp, *imp;
        dtpage_t *p;
        int index;
        struct btstack btstack;
        struct dt_lock *dtlck;
        struct tlock *tlck;
        struct lv *lv;
        int i;
        struct ldtentry *ldtentry;
        u8 *stbl;
        u32 table_index, next_index;
        struct metapage *nmp;
        dtpage_t *np;

        /*
         *      search for the entry to delete:
         *
         * dtSearch() returns (leaf page pinned, index at which to delete).
         */
        if ((rc = dtSearch(ip, key, ino, &btstack, flag)))
                return rc;

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

        /*
         * We need to find put the index of the next entry into the
         * directory index table in order to resume a readdir from this
         * entry.
         */
        if (DO_INDEX(ip)) {
                stbl = DT_GETSTBL(p);
                ldtentry = (struct ldtentry *) & p->slot[stbl[index]];
                table_index = le32_to_cpu(ldtentry->index);
                if (index == (p->header.nextindex - 1)) {
                        /*
                         * Last entry in this leaf page
                         */
                        if ((p->header.flag & BT_ROOT)
                            || (p->header.next == 0))
                                next_index = -1;
                        else {
                                /* Read next leaf page */
                                DT_GETPAGE(ip, le64_to_cpu(p->header.next),
                                           nmp, PSIZE, np, rc);
                                if (rc)
                                        next_index = -1;
                                else {
                                        stbl = DT_GETSTBL(np);
                                        ldtentry =
                                            (struct ldtentry *) & np->
                                            slot[stbl[0]];
                                        next_index =
                                            le32_to_cpu(ldtentry->index);
                                        DT_PUTPAGE(nmp);
                                }
                        }
                } else {
                        ldtentry =
                            (struct ldtentry *) & p->slot[stbl[index + 1]];
                        next_index = le32_to_cpu(ldtentry->index);
                }
                free_index(tid, ip, table_index, next_index);
        }
        /*
         * the leaf page becomes empty, delete the page
         */
        if (p->header.nextindex == 1) {
                /* delete empty page */
                rc = dtDeleteUp(tid, ip, mp, p, &btstack);
        }
        /*
         * the leaf page has other entries remaining:
         *
         * delete the entry from the leaf page.
         */
        else {
                BT_MARK_DIRTY(mp, ip);
                /*
                 * acquire a transaction lock on the leaf page
                 */
                tlck = txLock(tid, ip, mp, tlckDTREE | tlckENTRY);
                dtlck = (struct dt_lock *) & tlck->lock;

                /*
                 * Do not assume that dtlck->index will be zero.  During a
                 * rename within a directory, this transaction may have
                 * modified this page already when adding the new entry.
                 */

                /* linelock header */
                if (dtlck->index >= dtlck->maxcnt)
                        dtlck = (struct dt_lock *) txLinelock(dtlck);
                lv = & dtlck->lv[dtlck->index];
                lv->offset = 0;
                lv->length = 1;
                dtlck->index++;

                /* linelock stbl of non-root leaf page */
                if (!(p->header.flag & BT_ROOT)) {
                        if (dtlck->index >= dtlck->maxcnt)
                                dtlck = (struct dt_lock *) txLinelock(dtlck);
                        lv = & dtlck->lv[dtlck->index];
                        i = index >> L2DTSLOTSIZE;
                        lv->offset = p->header.stblindex + i;
                        lv->length =
                            ((p->header.nextindex - 1) >> L2DTSLOTSIZE) -
                            i + 1;
                        dtlck->index++;
                }

                /* free the leaf entry */
                dtDeleteEntry(p, index, &dtlck);

                /*
                 * Update directory index table for entries moved in stbl
                 */
                if (DO_INDEX(ip) && index < p->header.nextindex) {
                        s64 lblock;

                        imp = NULL;
                        stbl = DT_GETSTBL(p);
                        for (i = index; i < p->header.nextindex; i++) {
                                ldtentry =
                                    (struct ldtentry *) & p->slot[stbl[i]];
                                modify_index(tid, ip,
                                             le32_to_cpu(ldtentry->index),
                                             bn, i, &imp, &lblock);
                        }
                        if (imp)
                                release_metapage(imp);
                }

                DT_PUTPAGE(mp);
        }

        return rc;
}


/*
 *      dtDeleteUp()
 *
 * function:
 *      free empty pages as propagating deletion up the tree
 *
 * parameter:
 *
 * return:
 */
static int dtDeleteUp(tid_t tid, struct inode *ip,
           struct metapage * fmp, dtpage_t * fp, struct btstack * btstack)
{
        int rc = 0;
        struct metapage *mp;
        dtpage_t *p;
        int index, nextindex;
        int xlen;
        struct btframe *parent;
        struct dt_lock *dtlck;
        struct tlock *tlck;
        struct lv *lv;
        struct pxd_lock *pxdlock;
        int i;

        /*
         *      keep the root leaf page which has become empty
         */
        if (BT_IS_ROOT(fmp)) {
                /*
                 * reset the root
                 *
                 * dtInitRoot() acquires txlock on the root
                 */
                dtInitRoot(tid, ip, PARENT(ip));

                DT_PUTPAGE(fmp);

                return 0;
        }

        /*
         *      free the non-root leaf page
         */
        /*
         * acquire a transaction lock on the page
         *
         * write FREEXTENT|NOREDOPAGE log record
         * N.B. linelock is overlaid as freed extent descriptor, and
         * the buffer page is freed;
         */
        tlck = txMaplock(tid, ip, tlckDTREE | tlckFREE);
        pxdlock = (struct pxd_lock *) & tlck->lock;
        pxdlock->flag = mlckFREEPXD;
        pxdlock->pxd = fp->header.self;
        pxdlock->index = 1;

        /* update sibling pointers */
        if ((rc = dtRelink(tid, ip, fp))) {
                BT_PUTPAGE(fmp);
                return rc;
        }

        xlen = lengthPXD(&fp->header.self);

        /* Free quota allocation. */
        dquot_free_block(ip, xlen);

        /* free/invalidate its buffer page */
        discard_metapage(fmp);

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

                /*
                 * free the extent of the child page deleted
                 */
                index = parent->index;

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

                /*
                 * the parent has the single entry being deleted:
                 *
                 * free the parent page which has become empty.
                 */
                if (nextindex == 1) {
                        /*
                         * keep the root internal page which has become empty
                         */
                        if (p->header.flag & BT_ROOT) {
                                /*
                                 * reset the root
                                 *
                                 * dtInitRoot() acquires txlock on the root
                                 */
                                dtInitRoot(tid, ip, PARENT(ip));

                                DT_PUTPAGE(mp);

                                return 0;
                        }
                        /*
                         * free the parent page
                         */
                        else {
                                /*
                                 * acquire a transaction lock on the page
                                 *
                                 * write FREEXTENT|NOREDOPAGE log record
                                 */
                                tlck =
                                    txMaplock(tid, ip,
                                              tlckDTREE | tlckFREE);
                                pxdlock = (struct pxd_lock *) & tlck->lock;
                                pxdlock->flag = mlckFREEPXD;
                                pxdlock->pxd = p->header.self;
                                pxdlock->index = 1;

                                /* update sibling pointers */
                                if ((rc = dtRelink(tid, ip, p))) {
                                        DT_PUTPAGE(mp);
                                        return rc;
                                }

                                xlen = lengthPXD(&p->header.self);

                                /* Free quota allocation */
                                dquot_free_block(ip, xlen);

                                /* free/invalidate its buffer page */
                                discard_metapage(mp);

                                /* propagate up */
                                continue;
                        }
                }

                /*
                 * the parent has other entries remaining:
                 *
                 * delete the router entry from the parent page.
                 */
                BT_MARK_DIRTY(mp, ip);
                /*
                 * acquire a transaction lock on the page
                 *
                 * action: router entry deletion
                 */
                tlck = txLock(tid, ip, mp, tlckDTREE | tlckENTRY);
                dtlck = (struct dt_lock *) & tlck->lock;

                /* linelock header */
                if (dtlck->index >= dtlck->maxcnt)
                        dtlck = (struct dt_lock *) txLinelock(dtlck);
                lv = & dtlck->lv[dtlck->index];
                lv->offset = 0;
                lv->length = 1;
                dtlck->index++;

                /* linelock stbl of non-root leaf page */
                if (!(p->header.flag & BT_ROOT)) {
                        if (dtlck->index < dtlck->maxcnt)
                                lv++;
                        else {
                                dtlck = (struct dt_lock *) txLinelock(dtlck);
                                lv = & dtlck->lv[0];
                        }
                        i = index >> L2DTSLOTSIZE;
                        lv->offset = p->header.stblindex + i;
                        lv->length =
                            ((p->header.nextindex - 1) >> L2DTSLOTSIZE) -
                            i + 1;
                        dtlck->index++;
                }

                /* free the router entry */
                dtDeleteEntry(p, index, &dtlck);

                /* reset key of new leftmost entry of level (for consistency) */
                if (index == 0 &&
                    ((p->header.flag & BT_ROOT) || p->header.prev == 0))
                        dtTruncateEntry(p, 0, &dtlck);

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

                /* exit propagation up */
                break;
        }

        if (!DO_INDEX(ip))
                ip->i_size -= PSIZE;

        return 0;
}

#ifdef _NOTYET
/*
 * NAME:        dtRelocate()
 *
 * FUNCTION:    relocate dtpage (internal or leaf) of directory;
 *              This function is mainly used by defragfs utility.
 */
int dtRelocate(tid_t tid, struct inode *ip, s64 lmxaddr, pxd_t * opxd,
               s64 nxaddr)
{
        int rc = 0;
        struct metapage *mp, *pmp, *lmp, *rmp;
        dtpage_t *p, *pp, *rp = 0, *lp= 0;
        s64 bn;
        int index;
        struct btstack btstack;
        pxd_t *pxd;
        s64 oxaddr, nextbn, prevbn;
        int xlen, xsize;
        struct tlock *tlck;
        struct dt_lock *dtlck;
        struct pxd_lock *pxdlock;
        s8 *stbl;
        struct lv *lv;

        oxaddr = addressPXD(opxd);
        xlen = lengthPXD(opxd);

        jfs_info("dtRelocate: lmxaddr:%Ld xaddr:%Ld:%Ld xlen:%d",
                   (long long)lmxaddr, (long long)oxaddr, (long long)nxaddr,
                   xlen);

        /*
         *      1. get the internal parent dtpage covering
         *      router entry for the tartget page to be relocated;
         */
        rc = dtSearchNode(ip, lmxaddr, opxd, &btstack);
        if (rc)
                return rc;

        /* retrieve search result */
        DT_GETSEARCH(ip, btstack.top, bn, pmp, pp, index);
        jfs_info("dtRelocate: parent router entry validated.");

        /*
         *      2. relocate the target dtpage
         */
        /* read in the target page from src extent */
        DT_GETPAGE(ip, oxaddr, mp, PSIZE, p, rc);
        if (rc) {
                /* release the pinned parent page */
                DT_PUTPAGE(pmp);
                return rc;
        }

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

        lmp = NULL;
        if (p->header.prev) {
                prevbn = le64_to_cpu(p->header.prev);
                DT_GETPAGE(ip, prevbn, lmp, PSIZE, lp, rc);
                if (rc) {
                        DT_PUTPAGE(mp);
                        DT_PUTPAGE(pmp);
                        if (rmp)
                                DT_PUTPAGE(rmp);
                        return (rc);
                }
        }

        /* at this point, all xtpages to be updated are in memory */

        /*
         * update sibling pointers of sibling dtpages if any;
         */
        if (lmp) {
                tlck = txLock(tid, ip, lmp, tlckDTREE | tlckRELINK);
                dtlck = (struct dt_lock *) & tlck->lock;
                /* linelock header */
                ASSERT(dtlck->index == 0);
                lv = & dtlck->lv[0];
                lv->offset = 0;
                lv->length = 1;
                dtlck->index++;

                lp->header.next = cpu_to_le64(nxaddr);
                DT_PUTPAGE(lmp);
        }

        if (rmp) {
                tlck = txLock(tid, ip, rmp, tlckDTREE | tlckRELINK);
                dtlck = (struct dt_lock *) & tlck->lock;
                /* linelock header */
                ASSERT(dtlck->index == 0);
                lv = & dtlck->lv[0];
                lv->offset = 0;
                lv->length = 1;
                dtlck->index++;

                rp->header.prev = cpu_to_le64(nxaddr);
                DT_PUTPAGE(rmp);
        }

        /*
         * update the target dtpage to be relocated
         *
         * write LOG_REDOPAGE of LOG_NEW type for dst page
         * for the whole target page (logredo() will apply
         * after image and update bmap for allocation of the
         * dst extent), and update bmap for allocation of
         * the dst extent;
         */
        tlck = txLock(tid, ip, mp, tlckDTREE | tlckNEW);
        dtlck = (struct dt_lock *) & tlck->lock;
        /* linelock header */
        ASSERT(dtlck->index == 0);
        lv = & dtlck->lv[0];

        /* update the self address in the dtpage header */
        pxd = &p->header.self;
        PXDaddress(pxd, nxaddr);

        /* the dst page is the same as the src page, i.e.,
         * linelock for afterimage of the whole page;
         */
        lv->offset = 0;
        lv->length = p->header.maxslot;
        dtlck->index++;

        /* update the buffer extent descriptor of the dtpage */
        xsize = xlen << JFS_SBI(ip->i_sb)->l2bsize;

        /* unpin the relocated page */
        DT_PUTPAGE(mp);
        jfs_info("dtRelocate: target dtpage relocated.");

        /* the moved extent is dtpage, then a LOG_NOREDOPAGE log rec
         * needs to be written (in logredo(), the LOG_NOREDOPAGE log rec
         * will also force a bmap update ).
         */

        /*
         *      3. acquire maplock for the source extent to be freed;
         */
        /* for dtpage relocation, write a LOG_NOREDOPAGE record
         * for the source dtpage (logredo() will init NoRedoPage
         * filter and will also update bmap for free of the source
         * dtpage), and upadte bmap for free of the source dtpage;
         */
        tlck = txMaplock(tid, ip, tlckDTREE | tlckFREE);
        pxdlock = (struct pxd_lock *) & tlck->lock;
        pxdlock->flag = mlckFREEPXD;
        PXDaddress(&pxdlock->pxd, oxaddr);
        PXDlength(&pxdlock->pxd, xlen);
        pxdlock->index = 1;

        /*
         *      4. update the parent router entry for relocation;
         *
         * acquire tlck for the parent entry covering the target dtpage;
         * write LOG_REDOPAGE to apply after image only;
         */
        jfs_info("dtRelocate: update parent router entry.");
        tlck = txLock(tid, ip, pmp, tlckDTREE | tlckENTRY);
        dtlck = (struct dt_lock *) & tlck->lock;
        lv = & dtlck->lv[dtlck->index];

        /* update the PXD with the new address */
        stbl = DT_GETSTBL(pp);
        pxd = (pxd_t *) & pp->slot[stbl[index]];
        PXDaddress(pxd, nxaddr);
        lv->offset = stbl[index];
        lv->length = 1;
        dtlck->index++;

        /* unpin the parent dtpage */
        DT_PUTPAGE(pmp);

        return rc;
}

/*
 * NAME:        dtSearchNode()
 *
 * FUNCTION:    Search for an dtpage containing a specified address
 *              This function is mainly used by defragfs utility.
 *
 * NOTE:        Search result on stack, the found page is pinned at exit.
 *              The result page must be an internal dtpage.
 *              lmxaddr give the address of the left most page of the
 *              dtree level, in which the required dtpage resides.
 */
static int dtSearchNode(struct inode *ip, s64 lmxaddr, pxd_t * kpxd,
                        struct btstack * btstack)
{
        int rc = 0;
        s64 bn;
        struct metapage *mp;
        dtpage_t *p;
        int psize = 288;        /* initial in-line directory */
        s8 *stbl;
        int i;
        pxd_t *pxd;
        struct btframe *btsp;

        BT_CLR(btstack);        /* reset stack */

        /*
         *      descend tree to the level with specified leftmost page
         *
         *  by convention, root bn = 0.
         */
        for (bn = 0;;) {
                /* get/pin the page to search */
                DT_GETPAGE(ip, bn, mp, psize, p, rc);
                if (rc)
                        return rc;

                /* does the xaddr of leftmost page of the levevl
                 * matches levevl search key ?
                 */
                if (p->header.flag & BT_ROOT) {
                        if (lmxaddr == 0)
                                break;
                } else if (addressPXD(&p->header.self) == lmxaddr)
                        break;

                /*
                 * descend down to leftmost child page
                 */
                if (p->header.flag & BT_LEAF) {
                        DT_PUTPAGE(mp);
                        return -ESTALE;
                }

                /* get the leftmost entry */
                stbl = DT_GETSTBL(p);
                pxd = (pxd_t *) & p->slot[stbl[0]];

                /* get the child page block address */
                bn = addressPXD(pxd);
                psize = lengthPXD(pxd) << JFS_SBI(ip->i_sb)->l2bsize;
                /* unpin the parent page */
                DT_PUTPAGE(mp);
        }

        /*
         *      search each page at the current levevl
         */
      loop:
        stbl = DT_GETSTBL(p);
        for (i = 0; i < p->header.nextindex; i++) {
                pxd = (pxd_t *) & p->slot[stbl[i]];

                /* found the specified router entry */
                if (addressPXD(pxd) == addressPXD(kpxd) &&
                    lengthPXD(pxd) == lengthPXD(kpxd)) {
                        btsp = btstack->top;
                        btsp->bn = bn;
                        btsp->index = i;
                        btsp->mp = mp;

                        return 0;
                }
        }

        /* get the right sibling page if any */
        if (p->header.next)
                bn = le64_to_cpu(p->header.next);
        else {
                DT_PUTPAGE(mp);
                return -ESTALE;
        }

        /* unpin current page */
        DT_PUTPAGE(mp);

        /* get the right sibling page */
        DT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
        if (rc)
                return rc;

        goto loop;
}
#endif /* _NOTYET */

/*
 *      dtRelink()
 *
 * function:
 *      link around a freed page.
 *
 * parameter:
 *      fp:     page to be freed
 *
 * return:
 */
static int dtRelink(tid_t tid, struct inode *ip, dtpage_t * p)
{
        int rc;
        struct metapage *mp;
        s64 nextbn, prevbn;
        struct tlock *tlck;
        struct dt_lock *dtlck;
        struct lv *lv;

        nextbn = le64_to_cpu(p->header.next);
        prevbn = le64_to_cpu(p->header.prev);

        /* update prev pointer of the next page */
        if (nextbn != 0) {
                DT_GETPAGE(ip, nextbn, mp, PSIZE, p, rc);
                if (rc)
                        return rc;

                BT_MARK_DIRTY(mp, ip);
                /*
                 * acquire a transaction lock on the next page
                 *
                 * action: update prev pointer;
                 */
                tlck = txLock(tid, ip, mp, tlckDTREE | tlckRELINK);
                jfs_info("dtRelink nextbn: tlck = 0x%p, ip = 0x%p, mp=0x%p",
                        tlck, ip, mp);
                dtlck = (struct dt_lock *) & tlck->lock;

                /* linelock header */
                if (dtlck->index >= dtlck->maxcnt)
                        dtlck = (struct dt_lock *) txLinelock(dtlck);
                lv = & dtlck->lv[dtlck->index];
                lv->offset = 0;
                lv->length = 1;
                dtlck->index++;

                p->header.prev = cpu_to_le64(prevbn);
                DT_PUTPAGE(mp);
        }

        /* update next pointer of the previous page */
        if (prevbn != 0) {
                DT_GETPAGE(ip, prevbn, mp, PSIZE, p, rc);
                if (rc)
                        return rc;

                BT_MARK_DIRTY(mp, ip);
                /*
                 * acquire a transaction lock on the prev page
                 *
                 * action: update next pointer;
                 */
                tlck = txLock(tid, ip, mp, tlckDTREE | tlckRELINK);
                jfs_info("dtRelink prevbn: tlck = 0x%p, ip = 0x%p, mp=0x%p",
                        tlck, ip, mp);
                dtlck = (struct dt_lock *) & tlck->lock;

                /* linelock header */
                if (dtlck->index >= dtlck->maxcnt)
                        dtlck = (struct dt_lock *) txLinelock(dtlck);
                lv = & dtlck->lv[dtlck->index];
                lv->offset = 0;
                lv->length = 1;
                dtlck->index++;

                p->header.next = cpu_to_le64(nextbn);
                DT_PUTPAGE(mp);
        }

        return 0;
}


/*
 *      dtInitRoot()
 *
 * initialize directory root (inline in inode)
 */
void dtInitRoot(tid_t tid, struct inode *ip, u32 idotdot)
{
        struct jfs_inode_info *jfs_ip = JFS_IP(ip);
        dtroot_t *p;
        int fsi;
        struct dtslot *f;
        struct tlock *tlck;
        struct dt_lock *dtlck;
        struct lv *lv;
        u16 xflag_save;

        /*
         * If this was previously an non-empty directory, we need to remove
         * the old directory table.
         */
        if (DO_INDEX(ip)) {
                if (!jfs_dirtable_inline(ip)) {
                        struct tblock *tblk = tid_to_tblock(tid);
                        /*
                         * We're playing games with the tid's xflag.  If
                         * we're removing a regular file, the file's xtree
                         * is committed with COMMIT_PMAP, but we always
                         * commit the directories xtree with COMMIT_PWMAP.
                         */
                        xflag_save = tblk->xflag;
                        tblk->xflag = 0;
                        /*
                         * xtTruncate isn't guaranteed to fully truncate
                         * the xtree.  The caller needs to check i_size
                         * after committing the transaction to see if
                         * additional truncation is needed.  The
                         * COMMIT_Stale flag tells caller that we
                         * initiated the truncation.
                         */
                        xtTruncate(tid, ip, 0, COMMIT_PWMAP);
                        set_cflag(COMMIT_Stale, ip);

                        tblk->xflag = xflag_save;
                } else
                        ip->i_size = 1;

                jfs_ip->next_index = 2;
        } else
                ip->i_size = IDATASIZE;

        /*
         * acquire a transaction lock on the root
         *
         * action: directory initialization;
         */
        tlck = txLock(tid, ip, (struct metapage *) & jfs_ip->bxflag,
                      tlckDTREE | tlckENTRY | tlckBTROOT);
        dtlck = (struct dt_lock *) & tlck->lock;

        /* linelock root */
        ASSERT(dtlck->index == 0);
        lv = & dtlck->lv[0];
        lv->offset = 0;
        lv->length = DTROOTMAXSLOT;
        dtlck->index++;

        p = &jfs_ip->i_dtroot;

        p->header.flag = DXD_INDEX | BT_ROOT | BT_LEAF;

        p->header.nextindex = 0;

        /* init freelist */
        fsi = 1;
        f = &p->slot[fsi];

        /* init data area of root */
        for (fsi++; fsi < DTROOTMAXSLOT; f++, fsi++)
                f->next = fsi;
        f->next = -1;

        p->header.freelist = 1;
        p->header.freecnt = 8;

        /* init '..' entry */
        p->header.idotdot = cpu_to_le32(idotdot);

        return;
}

/*
 *      add_missing_indices()
 *
 * function: Fix dtree page in which one or more entries has an invalid index.
 *           fsck.jfs should really fix this, but it currently does not.
 *           Called from jfs_readdir when bad index is detected.
 */
static void add_missing_indices(struct inode *inode, s64 bn)
{
        struct ldtentry *d;
        struct dt_lock *dtlck;
        int i;
        uint index;
        struct lv *lv;
        struct metapage *mp;
        dtpage_t *p;
        int rc;
        s8 *stbl;
        tid_t tid;
        struct tlock *tlck;

        tid = txBegin(inode->i_sb, 0);

        DT_GETPAGE(inode, bn, mp, PSIZE, p, rc);

        if (rc) {
                printk(KERN_ERR "DT_GETPAGE failed!\n");
                goto end;
        }
        BT_MARK_DIRTY(mp, inode);

        ASSERT(p->header.flag & BT_LEAF);

        tlck = txLock(tid, inode, mp, tlckDTREE | tlckENTRY);
        if (BT_IS_ROOT(mp))
                tlck->type |= tlckBTROOT;

        dtlck = (struct dt_lock *) &tlck->lock;

        stbl = DT_GETSTBL(p);
        for (i = 0; i < p->header.nextindex; i++) {
                d = (struct ldtentry *) &p->slot[stbl[i]];
                index = le32_to_cpu(d->index);
                if ((index < 2) || (index >= JFS_IP(inode)->next_index)) {
                        d->index = cpu_to_le32(add_index(tid, inode, bn, i));
                        if (dtlck->index >= dtlck->maxcnt)
                                dtlck = (struct dt_lock *) txLinelock(dtlck);
                        lv = &dtlck->lv[dtlck->index];
                        lv->offset = stbl[i];
                        lv->length = 1;
                        dtlck->index++;
                }
        }

        DT_PUTPAGE(mp);
        (void) txCommit(tid, 1, &inode, 0);
end:
        txEnd(tid);
}

/*
 * Buffer to hold directory entry info while traversing a dtree page
 * before being fed to the filldir function
 */
struct jfs_dirent {
        loff_t position;
        int ino;
        u16 name_len;
        char name[0];
};

/*
 * function to determine next variable-sized jfs_dirent in buffer
 */
static inline struct jfs_dirent *next_jfs_dirent(struct jfs_dirent *dirent)
{
        return (struct jfs_dirent *)
                ((char *)dirent +
                 ((sizeof (struct jfs_dirent) + dirent->name_len + 1 +
                   sizeof (loff_t) - 1) &
                  ~(sizeof (loff_t) - 1)));
}

/*
 *      jfs_readdir()
 *
 * function: read directory entries sequentially
 *      from the specified entry offset
 *
 * parameter:
 *
 * return: offset = (pn, index) of start entry
 *      of next jfs_readdir()/dtRead()
 */
int jfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
        struct inode *ip = filp->f_path.dentry->d_inode;
        struct nls_table *codepage = JFS_SBI(ip->i_sb)->nls_tab;
        int rc = 0;
        loff_t dtpos;   /* legacy OS/2 style position */
        struct dtoffset {
                s16 pn;
                s16 index;
                s32 unused;
        } *dtoffset = (struct dtoffset *) &dtpos;
        s64 bn;
        struct metapage *mp;
        dtpage_t *p;
        int index;
        s8 *stbl;
        struct btstack btstack;
        int i, next;
        struct ldtentry *d;
        struct dtslot *t;
        int d_namleft, len, outlen;
        unsigned long dirent_buf;
        char *name_ptr;
        u32 dir_index;
        int do_index = 0;
        uint loop_count = 0;
        struct jfs_dirent *jfs_dirent;
        int jfs_dirents;
        int overflow, fix_page, page_fixed = 0;
        static int unique_pos = 2;      /* If we can't fix broken index */

        if (filp->f_pos == DIREND)
                return 0;

        if (DO_INDEX(ip)) {
                /*
                 * persistent index is stored in directory entries.
                 * Special cases:        0 = .
                 *                       1 = ..
                 *                      -1 = End of directory
                 */
                do_index = 1;

                dir_index = (u32) filp->f_pos;

                if (dir_index > 1) {
                        struct dir_table_slot dirtab_slot;

                        if (dtEmpty(ip) ||
                            (dir_index >= JFS_IP(ip)->next_index)) {
                                /* Stale position.  Directory has shrunk */
                                filp->f_pos = DIREND;
                                return 0;
                        }
                      repeat:
                        rc = read_index(ip, dir_index, &dirtab_slot);
                        if (rc) {
                                filp->f_pos = DIREND;
                                return rc;
                        }
                        if (dirtab_slot.flag == DIR_INDEX_FREE) {
                                if (loop_count++ > JFS_IP(ip)->next_index) {
                                        jfs_err("jfs_readdir detected "
                                                   "infinite loop!");
                                        filp->f_pos = DIREND;
                                        return 0;
                                }
                                dir_index = le32_to_cpu(dirtab_slot.addr2);
                                if (dir_index == -1) {
                                        filp->f_pos = DIREND;
                                        return 0;
                                }
                                goto repeat;
                        }
                        bn = addressDTS(&dirtab_slot);
                        index = dirtab_slot.slot;
                        DT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
                        if (rc) {
                                filp->f_pos = DIREND;
                                return 0;
                        }
                        if (p->header.flag & BT_INTERNAL) {
                                jfs_err("jfs_readdir: bad index table");
                                DT_PUTPAGE(mp);
                                filp->f_pos = -1;
                                return 0;
                        }
                } else {
                        if (dir_index == 0) {
                                /*
                                 * self "."
                                 */
                                filp->f_pos = 0;
                                if (filldir(dirent, ".", 1, 0, ip->i_ino,
                                            DT_DIR))
                                        return 0;
                        }
                        /*
                         * parent ".."
                         */
                        filp->f_pos = 1;
                        if (filldir(dirent, "..", 2, 1, PARENT(ip), DT_DIR))
                                return 0;

                        /*
                         * Find first entry of left-most leaf
                         */
                        if (dtEmpty(ip)) {
                                filp->f_pos = DIREND;
                                return 0;
                        }

                        if ((rc = dtReadFirst(ip, &btstack)))
                                return rc;

                        DT_GETSEARCH(ip, btstack.top, bn, mp, p, index);
                }
        } else {
                /*
                 * Legacy filesystem - OS/2 & Linux JFS < 0.3.6
                 *
                 * pn = index = 0:      First entry "."
                 * pn = 0; index = 1:   Second entry ".."
                 * pn > 0:              Real entries, pn=1 -> leftmost page
                 * pn = index = -1:     No more entries
                 */
                dtpos = filp->f_pos;
                if (dtpos == 0) {
                        /* build "." entry */

                        if (filldir(dirent, ".", 1, filp->f_pos, ip->i_ino,
                                    DT_DIR))
                                return 0;
                        dtoffset->index = 1;
                        filp->f_pos = dtpos;
                }

                if (dtoffset->pn == 0) {
                        if (dtoffset->index == 1) {
                                /* build ".." entry */

                                if (filldir(dirent, "..", 2, filp->f_pos,
                                            PARENT(ip), DT_DIR))
                                        return 0;
                        } else {
                                jfs_err("jfs_readdir called with "
                                        "invalid offset!");
                        }
                        dtoffset->pn = 1;
                        dtoffset->index = 0;
                        filp->f_pos = dtpos;
                }

                if (dtEmpty(ip)) {
                        filp->f_pos = DIREND;
                        return 0;
                }

                if ((rc = dtReadNext(ip, &filp->f_pos, &btstack))) {
                        jfs_err("jfs_readdir: unexpected rc = %d "
                                "from dtReadNext", rc);
                        filp->f_pos = DIREND;
                        return 0;
                }
                /* get start leaf page and index */
                DT_GETSEARCH(ip, btstack.top, bn, mp, p, index);

                /* offset beyond directory eof ? */
                if (bn < 0) {
                        filp->f_pos = DIREND;
                        return 0;
                }
        }

        dirent_buf = __get_free_page(GFP_KERNEL);
        if (dirent_buf == 0) {
                DT_PUTPAGE(mp);
                jfs_warn("jfs_readdir: __get_free_page failed!");
                filp->f_pos = DIREND;
                return -ENOMEM;
        }

        while (1) {
                jfs_dirent = (struct jfs_dirent *) dirent_buf;
                jfs_dirents = 0;
                overflow = fix_page = 0;

                stbl = DT_GETSTBL(p);

                for (i = index; i < p->header.nextindex; i++) {
                        d = (struct ldtentry *) & p->slot[stbl[i]];

                        if (((long) jfs_dirent + d->namlen + 1) >
                            (dirent_buf + PAGE_SIZE)) {
                                /* DBCS codepages could overrun dirent_buf */
                                index = i;
                                overflow = 1;
                                break;
                        }

                        d_namleft = d->namlen;
                        name_ptr = jfs_dirent->name;
                        jfs_dirent->ino = le32_to_cpu(d->inumber);

                        if (do_index) {
                                len = min(d_namleft, DTLHDRDATALEN);
                                jfs_dirent->position = le32_to_cpu(d->index);
                                /*
                                 * d->index should always be valid, but it
                                 * isn't.  fsck.jfs doesn't create the
                                 * directory index for the lost+found
                                 * directory.  Rather than let it go,
                                 * we can try to fix it.
                                 */
                                if ((jfs_dirent->position < 2) ||
                                    (jfs_dirent->position >=
                                     JFS_IP(ip)->next_index)) {
                                        if (!page_fixed && !isReadOnly(ip)) {
                                                fix_page = 1;
                                                /*
                                                 * setting overflow and setting
                                                 * index to i will cause the
                                                 * same page to be processed
                                                 * again starting here
                                                 */
                                                overflow = 1;
                                                index = i;
                                                break;
                                        }
                                        jfs_dirent->position = unique_pos++;
                                }
                        } else {
                                jfs_dirent->position = dtpos;
                                len = min(d_namleft, DTLHDRDATALEN_LEGACY);
                        }

                        /* copy the name of head/only segment */
                        outlen = jfs_strfromUCS_le(name_ptr, d->name, len,
                                                   codepage);
                        jfs_dirent->name_len = outlen;

                        /* copy name in the additional segment(s) */
                        next = d->next;
                        while (next >= 0) {
                                t = (struct dtslot *) & p->slot[next];
                                name_ptr += outlen;
                                d_namleft -= len;
                                /* Sanity Check */
                                if (d_namleft == 0) {
                                        jfs_error(ip->i_sb,
                                                  "JFS:Dtree error: ino = "
                                                  "%ld, bn=%Ld, index = %d",
                                                  (long)ip->i_ino,
                                                  (long long)bn,
                                                  i);
                                        goto skip_one;
                                }
                                len = min(d_namleft, DTSLOTDATALEN);
                                outlen = jfs_strfromUCS_le(name_ptr, t->name,
                                                           len, codepage);
                                jfs_dirent->name_len += outlen;

                                next = t->next;
                        }

                        jfs_dirents++;
                        jfs_dirent = next_jfs_dirent(jfs_dirent);
skip_one:
                        if (!do_index)
                                dtoffset->index++;
                }

                if (!overflow) {
                        /* Point to next leaf page */
                        if (p->header.flag & BT_ROOT)
                                bn = 0;
                        else {
                                bn = le64_to_cpu(p->header.next);
                                index = 0;
                                /* update offset (pn:index) for new page */
                                if (!do_index) {
                                        dtoffset->pn++;
                                        dtoffset->index = 0;
                                }
                        }
                        page_fixed = 0;
                }

                /* unpin previous leaf page */
                DT_PUTPAGE(mp);

                jfs_dirent = (struct jfs_dirent *) dirent_buf;
                while (jfs_dirents--) {
                        filp->f_pos = jfs_dirent->position;
                        if (filldir(dirent, jfs_dirent->name,
                                    jfs_dirent->name_len, filp->f_pos,
                                    jfs_dirent->ino, DT_UNKNOWN))
                                goto out;
                        jfs_dirent = next_jfs_dirent(jfs_dirent);
                }

                if (fix_page) {
                        add_missing_indices(ip, bn);
                        page_fixed = 1;
                }

                if (!overflow && (bn == 0)) {
                        filp->f_pos = DIREND;
                        break;
                }

                DT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
                if (rc) {
                        free_page(dirent_buf);
                        return rc;
                }
        }

      out:
        free_page(dirent_buf);

        return rc;
}


/*
 *      dtReadFirst()
 *
 * function: get the leftmost page of the directory
 */
static int dtReadFirst(struct inode *ip, struct btstack * btstack)
{
        int rc = 0;
        s64 bn;
        int psize = 288;        /* initial in-line directory */
        struct metapage *mp;
        dtpage_t *p;
        s8 *stbl;
        struct btframe *btsp;
        pxd_t *xd;

        BT_CLR(btstack);        /* reset stack */

        /*
         *      descend leftmost path of the tree
         *
         * by convention, root bn = 0.
         */
        for (bn = 0;;) {
                DT_GETPAGE(ip, bn, mp, psize, p, rc);
                if (rc)
                        return rc;

                /*
                 * leftmost leaf page
                 */
                if (p->header.flag & BT_LEAF) {
                        /* return leftmost entry */
                        btsp = btstack->top;
                        btsp->bn = bn;
                        btsp->index = 0;
                        btsp->mp = mp;

                        return 0;
                }

                /*
                 * descend down to leftmost child page
                 */
                if (BT_STACK_FULL(btstack)) {
                        DT_PUTPAGE(mp);
                        jfs_error(ip->i_sb, "dtReadFirst: btstack overrun");
                        BT_STACK_DUMP(btstack);
                        return -EIO;
                }
                /* push (bn, index) of the parent page/entry */
                BT_PUSH(btstack, bn, 0);

                /* get the leftmost entry */
                stbl = DT_GETSTBL(p);
                xd = (pxd_t *) & p->slot[stbl[0]];

                /* get the child page block address */
                bn = addressPXD(xd);
                psize = lengthPXD(xd) << JFS_SBI(ip->i_sb)->l2bsize;

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


/*
 *      dtReadNext()
 *
 * function: get the page of the specified offset (pn:index)
 *
 * return: if (offset > eof), bn = -1;
 *
 * note: if index > nextindex of the target leaf page,
 * start with 1st entry of next leaf page;
 */
static int dtReadNext(struct inode *ip, loff_t * offset,
                      struct btstack * btstack)
{
        int rc = 0;
        struct dtoffset {
                s16 pn;
                s16 index;
                s32 unused;
        } *dtoffset = (struct dtoffset *) offset;
        s64 bn;
        struct metapage *mp;
        dtpage_t *p;
        int index;
        int pn;
        s8 *stbl;
        struct btframe *btsp, *parent;
        pxd_t *xd;

        /*
         * get leftmost leaf page pinned
         */
        if ((rc = dtReadFirst(ip, btstack)))
                return rc;

        /* get leaf page */
        DT_GETSEARCH(ip, btstack->top, bn, mp, p, index);

        /* get the start offset (pn:index) */
        pn = dtoffset->pn - 1;  /* Now pn = 0 represents leftmost leaf */
        index = dtoffset->index;

        /* start at leftmost page ? */
        if (pn == 0) {
                /* offset beyond eof ? */
                if (index < p->header.nextindex)
                        goto out;

                if (p->header.flag & BT_ROOT) {
                        bn = -1;
                        goto out;
                }

                /* start with 1st entry of next leaf page */
                dtoffset->pn++;
                dtoffset->index = index = 0;
                goto a;
        }

        /* start at non-leftmost page: scan parent pages for large pn */
        if (p->header.flag & BT_ROOT) {
                bn = -1;
                goto out;
        }

        /* start after next leaf page ? */
        if (pn > 1)
                goto b;

        /* get leaf page pn = 1 */
      a:
        bn = le64_to_cpu(p->header.next);

        /* unpin leaf page */
        DT_PUTPAGE(mp);

        /* offset beyond eof ? */
        if (bn == 0) {
                bn = -1;
                goto out;
        }

        goto c;

        /*
         * scan last internal page level to get target leaf page
         */
      b:
        /* unpin leftmost leaf page */
        DT_PUTPAGE(mp);

        /* get left most parent page */
        btsp = btstack->top;
        parent = btsp - 1;
        bn = parent->bn;
        DT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
        if (rc)
                return rc;

        /* scan parent pages at last internal page level */
        while (pn >= p->header.nextindex) {
                pn -= p->header.nextindex;

                /* get next parent page address */
                bn = le64_to_cpu(p->header.next);

                /* unpin current parent page */
                DT_PUTPAGE(mp);

                /* offset beyond eof ? */
                if (bn == 0) {
                        bn = -1;
                        goto out;
                }

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

                /* update parent page stack frame */
                parent->bn = bn;
        }

        /* get leaf page address */
        stbl = DT_GETSTBL(p);
        xd = (pxd_t *) & p->slot[stbl[pn]];
        bn = addressPXD(xd);

        /* unpin parent page */
        DT_PUTPAGE(mp);

        /*
         * get target leaf page
         */
      c:
        DT_GETPAGE(ip, bn, mp, PSIZE, p, rc);
        if (rc)
                return rc;

        /*
         * leaf page has been completed:
         * start with 1st entry of next leaf page
         */
        if (index >= p->header.nextindex) {
                bn = le64_to_cpu(p->header.next);

                /* unpin leaf page */
                DT_PUTPAGE(mp);

                /* offset beyond eof ? */
                if (bn == 0) {
                        bn = -1;
                        goto out;
                }

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

                /* start with 1st entry of next leaf page */
                dtoffset->pn++;
                dtoffset->index = 0;
        }

      out:
        /* return target leaf page pinned */
        btsp = btstack->top;
        btsp->bn = bn;
        btsp->index = dtoffset->index;
        btsp->mp = mp;

        return 0;
}


/*
 *      dtCompare()
 *
 * function: compare search key with an internal entry
 *
 * return:
 *      < 0 if k is < record
 *      = 0 if k is = record
 *      > 0 if k is > record
 */
static int dtCompare(struct component_name * key,       /* search key */
                     dtpage_t * p,      /* directory page */
                     int si)
{                               /* entry slot index */
        wchar_t *kname;
        __le16 *name;
        int klen, namlen, len, rc;
        struct idtentry *ih;
        struct dtslot *t;

        /*
         * force the left-most key on internal pages, at any level of
         * the tree, to be less than any search key.
         * this obviates having to update the leftmost key on an internal
         * page when the user inserts a new key in the tree smaller than
         * anything that has been stored.
         *
         * (? if/when dtSearch() narrows down to 1st entry (index = 0),
         * at any internal page at any level of the tree,
         * it descends to child of the entry anyway -
         * ? make the entry as min size dummy entry)
         *
         * if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & BT_LEAF))
         * return (1);
         */

        kname = key->name;
        klen = key->namlen;

        ih = (struct idtentry *) & p->slot[si];
        si = ih->next;
        name = ih->name;
        namlen = ih->namlen;
        len = min(namlen, DTIHDRDATALEN);

        /* compare with head/only segment */
        len = min(klen, len);
        if ((rc = UniStrncmp_le(kname, name, len)))
                return rc;

        klen -= len;
        namlen -= len;

        /* compare with additional segment(s) */
        kname += len;
        while (klen > 0 && namlen > 0) {
                /* compare with next name segment */
                t = (struct dtslot *) & p->slot[si];
                len = min(namlen, DTSLOTDATALEN);
                len = min(klen, len);
                name = t->name;
                if ((rc = UniStrncmp_le(kname, name, len)))
                        return rc;

                klen -= len;
                namlen -= len;
                kname += len;
                si = t->next;
        }

        return (klen - namlen);
}




/*
 *      ciCompare()
 *
 * function: compare search key with an (leaf/internal) entry
 *
 * return:
 *      < 0 if k is < record
 *      = 0 if k is = record
 *      > 0 if k is > record
 */
static int ciCompare(struct component_name * key,       /* search key */
                     dtpage_t * p,      /* directory page */
                     int si,    /* entry slot index */
                     int flag)
{
        wchar_t *kname, x;
        __le16 *name;
        int klen, namlen, len, rc;
        struct ldtentry *lh;
        struct idtentry *ih;
        struct dtslot *t;
        int i;

        /*
         * force the left-most key on internal pages, at any level of
         * the tree, to be less than any search key.
         * this obviates having to update the leftmost key on an internal
         * page when the user inserts a new key in the tree smaller than
         * anything that has been stored.
         *
         * (? if/when dtSearch() narrows down to 1st entry (index = 0),
         * at any internal page at any level of the tree,
         * it descends to child of the entry anyway -
         * ? make the entry as min size dummy entry)
         *
         * if (e->index == 0 && h->prevpg == P_INVALID && !(h->flags & BT_LEAF))
         * return (1);
         */

        kname = key->name;
        klen = key->namlen;

        /*
         * leaf page entry
         */
        if (p->header.flag & BT_LEAF) {
                lh = (struct ldtentry *) & p->slot[si];
                si = lh->next;
                name = lh->name;
                namlen = lh->namlen;
                if (flag & JFS_DIR_INDEX)
                        len = min(namlen, DTLHDRDATALEN);
                else
                        len = min(namlen, DTLHDRDATALEN_LEGACY);
        }
        /*
         * internal page entry
         */
        else {
                ih = (struct idtentry *) & p->slot[si];
                si = ih->next;
                name = ih->name;
                namlen = ih->namlen;
                len = min(namlen, DTIHDRDATALEN);
        }

        /* compare with head/only segment */
        len = min(klen, len);
        for (i = 0; i < len; i++, kname++, name++) {
                /* only uppercase if case-insensitive support is on */
                if ((flag & JFS_OS2) == JFS_OS2)
                        x = UniToupper(le16_to_cpu(*name));
                else
                        x = le16_to_cpu(*name);
                if ((rc = *kname - x))
                        return rc;
        }

        klen -= len;
        namlen -= len;

        /* compare with additional segment(s) */
        while (klen > 0 && namlen > 0) {
                /* compare with next name segment */
                t = (struct dtslot *) & p->slot[si];
                len = min(namlen, DTSLOTDATALEN);
                len = min(klen, len);
                name = t->name;
                for (i = 0; i < len; i++, kname++, name++) {
                        /* only uppercase if case-insensitive support is on */
                        if ((flag & JFS_OS2) == JFS_OS2)
                                x = UniToupper(le16_to_cpu(*name));
                        else
                                x = le16_to_cpu(*name);

                        if ((rc = *kname - x))
                                return rc;
                }

                klen -= len;
                namlen -= len;
                si = t->next;
        }

        return (klen - namlen);
}


/*
 *      ciGetLeafPrefixKey()
 *
 * function: compute prefix of suffix compression
 *           from two adjacent leaf entries
 *           across page boundary
 *
 * return: non-zero on error
 *
 */
static int ciGetLeafPrefixKey(dtpage_t * lp, int li, dtpage_t * rp,
                               int ri, struct component_name * key, int flag)
{
        int klen, namlen;
        wchar_t *pl, *pr, *kname;
        struct component_name lkey;
        struct component_name rkey;

        lkey.name = kmalloc((JFS_NAME_MAX + 1) * sizeof(wchar_t),
                                        GFP_KERNEL);
        if (lkey.name == NULL)
                return -ENOMEM;

        rkey.name = kmalloc((JFS_NAME_MAX + 1) * sizeof(wchar_t),
                                        GFP_KERNEL);
        if (rkey.name == NULL) {
                kfree(lkey.name);
                return -ENOMEM;
        }

        /* get left and right key */
        dtGetKey(lp, li, &lkey, flag);
        lkey.name[lkey.namlen] = 0;

        if ((flag & JFS_OS2) == JFS_OS2)
                ciToUpper(&lkey);

        dtGetKey(rp, ri, &rkey, flag);
        rkey.name[rkey.namlen] = 0;


        if ((flag & JFS_OS2) == JFS_OS2)
                ciToUpper(&rkey);

        /* compute prefix */
        klen = 0;
        kname = key->name;
        namlen = min(lkey.namlen, rkey.namlen);
        for (pl = lkey.name, pr = rkey.name;
             namlen; pl++, pr++, namlen--, klen++, kname++) {
                *kname = *pr;
                if (*pl != *pr) {
                        key->namlen = klen + 1;
                        goto free_names;
                }
        }

        /* l->namlen <= r->namlen since l <= r */
        if (lkey.namlen < rkey.namlen) {
                *kname = *pr;
                key->namlen = klen + 1;
        } else                  /* l->namelen == r->namelen */
                key->namlen = klen;

free_names:
        kfree(lkey.name);
        kfree(rkey.name);
        return 0;
}



/*
 *      dtGetKey()
 *
 * function: get key of the entry
 */
static void dtGetKey(dtpage_t * p, int i,       /* entry index */
                     struct component_name * key, int flag)
{
        int si;
        s8 *stbl;
        struct ldtentry *lh;
        struct idtentry *ih;
        struct dtslot *t;
        int namlen, len;
        wchar_t *kname;
        __le16 *name;

        /* get entry */
        stbl = DT_GETSTBL(p);
        si = stbl[i];
        if (p->header.flag & BT_LEAF) {
                lh = (struct ldtentry *) & p->slot[si];
                si = lh->next;
                namlen = lh->namlen;
                name = lh->name;
                if (flag & JFS_DIR_INDEX)
                        len = min(namlen, DTLHDRDATALEN);
                else
                        len = min(namlen, DTLHDRDATALEN_LEGACY);
        } else {
                ih = (struct idtentry *) & p->slot[si];
                si = ih->next;
                namlen = ih->namlen;
                name = ih->name;
                len = min(namlen, DTIHDRDATALEN);
        }

        key->namlen = namlen;
        kname = key->name;

        /*
         * move head/only segment
         */
        UniStrncpy_from_le(kname, name, len);

        /*
         * move additional segment(s)
         */
        while (si >= 0) {
                /* get next segment */
                t = &p->slot[si];
                kname += len;
                namlen -= len;
                len = min(namlen, DTSLOTDATALEN);
                UniStrncpy_from_le(kname, t->name, len);

                si = t->next;
        }
}


/*
 *      dtInsertEntry()
 *
 * function: allocate free slot(s) and
 *           write a leaf/internal entry
 *
 * return: entry slot index
 */
static void dtInsertEntry(dtpage_t * p, int index, struct component_name * key,
                          ddata_t * data, struct dt_lock ** dtlock)
{
        struct dtslot *h, *t;
        struct ldtentry *lh = NULL;
        struct idtentry *ih = NULL;
        int hsi, fsi, klen, len, nextindex;
        wchar_t *kname;
        __le16 *name;
        s8 *stbl;
        pxd_t *xd;
        struct dt_lock *dtlck = *dtlock;
        struct lv *lv;
        int xsi, n;
        s64 bn = 0;
        struct metapage *mp = NULL;

        klen = key->namlen;
        kname = key->name;

        /* allocate a free slot */
        hsi = fsi = p->header.freelist;
        h = &p->slot[fsi];
        p->header.freelist = h->next;
        --p->header.freecnt;

        /* open new linelock */
        if (dtlck->index >= dtlck->maxcnt)
                dtlck = (struct dt_lock *) txLinelock(dtlck);

        lv = & dtlck->lv[dtlck->index];
        lv->offset = hsi;

        /* write head/only segment */
        if (p->header.flag & BT_LEAF) {
                lh = (struct ldtentry *) h;
                lh->next = h->next;
                lh->inumber = cpu_to_le32(data->leaf.ino);
                lh->namlen = klen;
                name = lh->name;
                if (data->leaf.ip) {
                        len = min(klen, DTLHDRDATALEN);
                        if (!(p->header.flag & BT_ROOT))
                                bn = addressPXD(&p->header.self);
                        lh->index = cpu_to_le32(add_index(data->leaf.tid,
                                                          data->leaf.ip,
                                                          bn, index));
                } else
                        len = min(klen, DTLHDRDATALEN_LEGACY);
        } else {
                ih = (struct idtentry *) h;
                ih->next = h->next;
                xd = (pxd_t *) ih;
                *xd = data->xd;
                ih->namlen = klen;
                name = ih->name;
                len = min(klen, DTIHDRDATALEN);
        }

        UniStrncpy_to_le(name, kname, len);

        n = 1;
        xsi = hsi;

        /* write additional segment(s) */
        t = h;
        klen -= len;
        while (klen) {
                /* get free slot */
                fsi = p->header.freelist;
                t = &p->slot[fsi];
                p->header.freelist = t->next;
                --p->header.freecnt;

                /* is next slot contiguous ? */
                if (fsi != xsi + 1) {
                        /* close current linelock */
                        lv->length = n;
                        dtlck->index++;

                        /* open new linelock */
                        if (dtlck->index < dtlck->maxcnt)
                                lv++;
                        else {
                                dtlck = (struct dt_lock *) txLinelock(dtlck);
                                lv = & dtlck->lv[0];
                        }

                        lv->offset = fsi;
                        n = 0;
                }

                kname += len;
                len = min(klen, DTSLOTDATALEN);
                UniStrncpy_to_le(t->name, kname, len);

                n++;
                xsi = fsi;
                klen -= len;
        }

        /* close current linelock */
        lv->length = n;
        dtlck->index++;

        *dtlock = dtlck;

        /* terminate last/only segment */
        if (h == t) {
                /* single segment entry */
                if (p->header.flag & BT_LEAF)
                        lh->next = -1;
                else
                        ih->next = -1;
        } else
                /* multi-segment entry */
                t->next = -1;

        /* if insert into middle, shift right succeeding entries in stbl */
        stbl = DT_GETSTBL(p);
        nextindex = p->header.nextindex;
        if (index < nextindex) {
                memmove(stbl + index + 1, stbl + index, nextindex - index);

                if ((p->header.flag & BT_LEAF) && data->leaf.ip) {
                        s64 lblock;

                        /*
                         * Need to update slot number for entries that moved
                         * in the stbl
                         */
                        mp = NULL;
                        for (n = index + 1; n <= nextindex; n++) {
                                lh = (struct ldtentry *) & (p->slot[stbl[n]]);
                                modify_index(data->leaf.tid, data->leaf.ip,
                                             le32_to_cpu(lh->index), bn, n,
                                             &mp, &lblock);
                        }
                        if (mp)
                                release_metapage(mp);
                }
        }

        stbl[index] = hsi;

        /* advance next available entry index of stbl */
        ++p->header.nextindex;
}


/*
 *      dtMoveEntry()
 *
 * function: move entries from split/left page to new/right page
 *
 *      nextindex of dst page and freelist/freecnt of both pages
 *      are updated.
 */
static void dtMoveEntry(dtpage_t * sp, int si, dtpage_t * dp,
                        struct dt_lock ** sdtlock, struct dt_lock ** ddtlock,
                        int do_index)
{
        int ssi, next;          /* src slot index */
        int di;                 /* dst entry index */
        int dsi;                /* dst slot index */
        s8 *sstbl, *dstbl;      /* sorted entry table */
        int snamlen, len;
        struct ldtentry *slh, *dlh = NULL;
        struct idtentry *sih, *dih = NULL;
        struct dtslot *h, *s, *d;
        struct dt_lock *sdtlck = *sdtlock, *ddtlck = *ddtlock;
        struct lv *slv, *dlv;
        int xssi, ns, nd;
        int sfsi;

        sstbl = (s8 *) & sp->slot[sp->header.stblindex];
        dstbl = (s8 *) & dp->slot[dp->header.stblindex];

        dsi = dp->header.freelist;      /* first (whole page) free slot */
        sfsi = sp->header.freelist;

        /* linelock destination entry slot */
        dlv = & ddtlck->lv[ddtlck->index];
        dlv->offset = dsi;

        /* linelock source entry slot */
        slv = & sdtlck->lv[sdtlck->index];
        slv->offset = sstbl[si];
        xssi = slv->offset - 1;

        /*
         * move entries
         */
        ns = nd = 0;
        for (di = 0; si < sp->header.nextindex; si++, di++) {
                ssi = sstbl[si];
                dstbl[di] = dsi;

                /* is next slot contiguous ? */
                if (ssi != xssi + 1) {
                        /* close current linelock */
                        slv->length = ns;
                        sdtlck->index++;

                        /* open new linelock */
                        if (sdtlck->index < sdtlck->maxcnt)
                                slv++;
                        else {
                                sdtlck = (struct dt_lock *) txLinelock(sdtlck);
                                slv = & sdtlck->lv[0];
                        }

                        slv->offset = ssi;
                        ns = 0;
                }

                /*
                 * move head/only segment of an entry
                 */
                /* get dst slot */
                h = d = &dp->slot[dsi];

                /* get src slot and move */
                s = &sp->slot[ssi];
                if (sp->header.flag & BT_LEAF) {
                        /* get source entry */
                        slh = (struct ldtentry *) s;
                        dlh = (struct ldtentry *) h;
                        snamlen = slh->namlen;

                        if (do_index) {
                                len = min(snamlen, DTLHDRDATALEN);
                                dlh->index = slh->index; /* little-endian */
                        } else
                                len = min(snamlen, DTLHDRDATALEN_LEGACY);

                        memcpy(dlh, slh, 6 + len * 2);

                        next = slh->next;

                        /* update dst head/only segment next field */
                        dsi++;
                        dlh->next = dsi;
                } else {
                        sih = (struct idtentry *) s;
                        snamlen = sih->namlen;

                        len = min(snamlen, DTIHDRDATALEN);
                        dih = (struct idtentry *) h;
                        memcpy(dih, sih, 10 + len * 2);
                        next = sih->next;

                        dsi++;
                        dih->next = dsi;
                }

                /* free src head/only segment */
                s->next = sfsi;
                s->cnt = 1;
                sfsi = ssi;

                ns++;
                nd++;
                xssi = ssi;

                /*
                 * move additional segment(s) of the entry
                 */
                snamlen -= len;
                while ((ssi = next) >= 0) {
                        /* is next slot contiguous ? */
                        if (ssi != xssi + 1) {
                                /* close current linelock */
                                slv->length = ns;
                                sdtlck->index++;

                                /* open new linelock */
                                if (sdtlck->index < sdtlck->maxcnt)
                                        slv++;
                                else {
                                        sdtlck =
                                            (struct dt_lock *)
                                            txLinelock(sdtlck);
                                        slv = & sdtlck->lv[0];
                                }

                                slv->offset = ssi;
                                ns = 0;
                        }

                        /* get next source segment */
                        s = &sp->slot[ssi];

                        /* get next destination free slot */
                        d++;

                        len = min(snamlen, DTSLOTDATALEN);
                        UniStrncpy_le(d->name, s->name, len);

                        ns++;
                        nd++;
                        xssi = ssi;

                        dsi++;
                        d->next = dsi;

                        /* free source segment */
                        next = s->next;
                        s->next = sfsi;
                        s->cnt = 1;
                        sfsi = ssi;

                        snamlen -= len;
                }               /* end while */

                /* terminate dst last/only segment */
                if (h == d) {
                        /* single segment entry */
                        if (dp->header.flag & BT_LEAF)
                                dlh->next = -1;
                        else
                                dih->next = -1;
                } else
                        /* multi-segment entry */
                        d->next = -1;
        }                       /* end for */

        /* close current linelock */
        slv->length = ns;
        sdtlck->index++;
        *sdtlock = sdtlck;

        dlv->length = nd;
        ddtlck->index++;
        *ddtlock = ddtlck;

        /* update source header */
        sp->header.freelist = sfsi;
        sp->header.freecnt += nd;

        /* update destination header */
        dp->header.nextindex = di;

        dp->header.freelist = dsi;
        dp->header.freecnt -= nd;
}


/*
 *      dtDeleteEntry()
 *
 * function: free a (leaf/internal) entry
 *
 * log freelist header, stbl, and each segment slot of entry
 * (even though last/only segment next field is modified,
 * physical image logging requires all segment slots of
 * the entry logged to avoid applying previous updates
 * to the same slots)
 */
static void dtDeleteEntry(dtpage_t * p, int fi, struct dt_lock ** dtlock)
{
        int fsi;                /* free entry slot index */
        s8 *stbl;
        struct dtslot *t;
        int si, freecnt;
        struct dt_lock *dtlck = *dtlock;
        struct lv *lv;
        int xsi, n;

        /* get free entry slot index */
        stbl = DT_GETSTBL(p);
        fsi = stbl[fi];

        /* open new linelock */
        if (dtlck->index >= dtlck->maxcnt)
                dtlck = (struct dt_lock *) txLinelock(dtlck);
        lv = & dtlck->lv[dtlck->index];

        lv->offset = fsi;

        /* get the head/only segment */
        t = &p->slot[fsi];
        if (p->header.flag & BT_LEAF)
                si = ((struct ldtentry *) t)->next;
        else
                si = ((struct idtentry *) t)->next;
        t->next = si;
        t->cnt = 1;

        n = freecnt = 1;
        xsi = fsi;

        /* find the last/only segment */
        while (si >= 0) {
                /* is next slot contiguous ? */
                if (si != xsi + 1) {
                        /* close current linelock */
                        lv->length = n;
                        dtlck->index++;

                        /* open new linelock */
                        if (dtlck->index < dtlck->maxcnt)
                                lv++;
                        else {
                                dtlck = (struct dt_lock *) txLinelock(dtlck);
                                lv = & dtlck->lv[0];
                        }

                        lv->offset = si;
                        n = 0;
                }

                n++;
                xsi = si;
                freecnt++;

                t = &p->slot[si];
                t->cnt = 1;
                si = t->next;
        }

        /* close current linelock */
        lv->length = n;
        dtlck->index++;

        *dtlock = dtlck;

        /* update freelist */
        t->next = p->header.freelist;
        p->header.freelist = fsi;
        p->header.freecnt += freecnt;

        /* if delete from middle,
         * shift left the succedding entries in the stbl
         */
        si = p->header.nextindex;
        if (fi < si - 1)
                memmove(&stbl[fi], &stbl[fi + 1], si - fi - 1);

        p->header.nextindex--;
}


/*
 *      dtTruncateEntry()
 *
 * function: truncate a (leaf/internal) entry
 *
 * log freelist header, stbl, and each segment slot of entry
 * (even though last/only segment next field is modified,
 * physical image logging requires all segment slots of
 * the entry logged to avoid applying previous updates
 * to the same slots)
 */
static void dtTruncateEntry(dtpage_t * p, int ti, struct dt_lock ** dtlock)
{
        int tsi;                /* truncate entry slot index */
        s8 *stbl;
        struct dtslot *t;
        int si, freecnt;
        struct dt_lock *dtlck = *dtlock;
        struct lv *lv;
        int fsi, xsi, n;

        /* get free entry slot index */
        stbl = DT_GETSTBL(p);
        tsi = stbl[ti];

        /* open new linelock */
        if (dtlck->index >= dtlck->maxcnt)
                dtlck = (struct dt_lock *) txLinelock(dtlck);
        lv = & dtlck->lv[dtlck->index];

        lv->offset = tsi;

        /* get the head/only segment */
        t = &p->slot[tsi];
        ASSERT(p->header.flag & BT_INTERNAL);
        ((struct idtentry *) t)->namlen = 0;
        si = ((struct idtentry *) t)->next;
        ((struct idtentry *) t)->next = -1;

        n = 1;
        freecnt = 0;
        fsi = si;
        xsi = tsi;

        /* find the last/only segment */
        while (si >= 0) {
                /* is next slot contiguous ? */
                if (si != xsi + 1) {
                        /* close current linelock */
                        lv->length = n;
                        dtlck->index++;

                        /* open new linelock */
                        if (dtlck->index < dtlck->maxcnt)
                                lv++;
                        else {
                                dtlck = (struct dt_lock *) txLinelock(dtlck);
                                lv = & dtlck->lv[0];
                        }

                        lv->offset = si;
                        n = 0;
                }

                n++;
                xsi = si;
                freecnt++;

                t = &p->slot[si];
                t->cnt = 1;
                si = t->next;
        }

        /* close current linelock */
        lv->length = n;
        dtlck->index++;

        *dtlock = dtlck;

        /* update freelist */
        if (freecnt == 0)
                return;
        t->next = p->header.freelist;
        p->header.freelist = fsi;
        p->header.freecnt += freecnt;
}


/*
 *      dtLinelockFreelist()
 */
static void dtLinelockFreelist(dtpage_t * p,    /* directory page */
                               int m,   /* max slot index */
                               struct dt_lock ** dtlock)
{
        int fsi;                /* free entry slot index */
        struct dtslot *t;
        int si;
        struct dt_lock *dtlck = *dtlock;
        struct lv *lv;
        int xsi, n;

        /* get free entry slot index */
        fsi = p->header.freelist;

        /* open new linelock */
        if (dtlck->index >= dtlck->maxcnt)
                dtlck = (struct dt_lock *) txLinelock(dtlck);
        lv = & dtlck->lv[dtlck->index];

        lv->offset = fsi;

        n = 1;
        xsi = fsi;

        t = &p->slot[fsi];
        si = t->next;

        /* find the last/only segment */
        while (si < m && si >= 0) {
                /* is next slot contiguous ? */
                if (si != xsi + 1) {
                        /* close current linelock */
                        lv->length = n;
                        dtlck->index++;

                        /* open new linelock */
                        if (dtlck->index < dtlck->maxcnt)
                                lv++;
                        else {
                                dtlck = (struct dt_lock *) txLinelock(dtlck);
                                lv = & dtlck->lv[0];
                        }

                        lv->offset = si;
                        n = 0;
                }

                n++;
                xsi = si;

                t = &p->slot[si];
                si = t->next;
        }

        /* close current linelock */
        lv->length = n;
        dtlck->index++;

        *dtlock = dtlck;
}


/*
 * NAME: dtModify
 *
 * FUNCTION: Modify the inode number part of a directory entry
 *
 * PARAMETERS:
 *      tid     - Transaction id
 *      ip      - Inode of parent directory
 *      key     - Name of entry to be modified
 *      orig_ino        - Original inode number expected in entry
 *      new_ino - New inode number to put into entry
 *      flag    - JFS_RENAME
 *
 * RETURNS:
 *      -ESTALE - If entry found does not match orig_ino passed in
 *      -ENOENT - If no entry can be found to match key
 *      0       - If successfully modified entry
 */
int dtModify(tid_t tid, struct inode *ip,
         struct component_name * key, ino_t * orig_ino, ino_t new_ino, int flag)
{
        int rc;
        s64 bn;
        struct metapage *mp;
        dtpage_t *p;
        int index;
        struct btstack btstack;
        struct tlock *tlck;
        struct dt_lock *dtlck;
        struct lv *lv;
        s8 *stbl;
        int entry_si;           /* entry slot index */
        struct ldtentry *entry;

        /*
         *      search for the entry to modify:
         *
         * dtSearch() returns (leaf page pinned, index at which to modify).
         */
        if ((rc = dtSearch(ip, key, orig_ino, &btstack, flag)))
                return rc;

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

        BT_MARK_DIRTY(mp, ip);
        /*
         * acquire a transaction lock on the leaf page of named entry
         */
        tlck = txLock(tid, ip, mp, tlckDTREE | tlckENTRY);
        dtlck = (struct dt_lock *) & tlck->lock;

        /* get slot index of the entry */
        stbl = DT_GETSTBL(p);
        entry_si = stbl[index];

        /* linelock entry */
        ASSERT(dtlck->index == 0);
        lv = & dtlck->lv[0];
        lv->offset = entry_si;
        lv->length = 1;
        dtlck->index++;

        /* get the head/only segment */
        entry = (struct ldtentry *) & p->slot[entry_si];

        /* substitute the inode number of the entry */
        entry->inumber = cpu_to_le32(new_ino);

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

        return 0;
}